WO2013013522A1 - 可重构计算机数字控制系统与数字控制方法、重构方法 - Google Patents

可重构计算机数字控制系统与数字控制方法、重构方法 Download PDF

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WO2013013522A1
WO2013013522A1 PCT/CN2012/074644 CN2012074644W WO2013013522A1 WO 2013013522 A1 WO2013013522 A1 WO 2013013522A1 CN 2012074644 W CN2012074644 W CN 2012074644W WO 2013013522 A1 WO2013013522 A1 WO 2013013522A1
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instruction
module
linkage
control
real
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PCT/CN2012/074644
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French (fr)
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江俊逢
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Jiang Junfeng
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    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05BCONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00Programme-control systems
    • G05B19/02Programme-control systems electric
    • G05B19/18Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/414Structure of the control system, e.g. common controller or multiprocessor systems, interface to servo, programmable interface controller

Definitions

  • the present invention belongs to the field of advanced control and advanced manufacturing, and specifically relates to a PC-based, all-round open, standardized reconfigurable computer digital control system and its digital control method and reconstruction method to adapt to reconfigurable manufacturing.
  • Technical Background Reconfigurable manufacturing systems are the cutting edge of advanced manufacturing and the future direction of manufacturing systems.
  • the National Research Council published a study on “The Challenges of Manufacturing in 2020”, ranking reconfigurable manufacturing systems as the top 10 key technologies.
  • Decisive for reconfigurable manufacturing systems is the Reconfigurable Machine Tools (RMT).
  • the reconfigurable computer digital control system should be an open digital control system, which is the consensus in the field.
  • the so-called motion controller-based open CNC system embedded in the PC mode has become the mainstream of the existing open CNC system.
  • the motion controller has become a high-tech industry and is popular all over the world.
  • the open motion controller is hailed as a new generation of industrial controllers in the United States and is considered to be the third industrial revolution in the future.
  • the numerical control system only decompresses the digital control information compressed in the tool path and feed rate.
  • the interpolation iterative control method is a decompression method of digital control information.
  • the basic technical solution of the interpolation iterative control method is to use the interpolation iteration for the given Tool Path curve and the tool feed speed under the control of the real-time operating system with the interpolation period as the time-sharing period.
  • the algorithm calculates the digital control information of the relevant coordinate axes in real time, and distributes them to the servo drive for execution in real time to control the deterministic motion relationship between the mechanical systems.
  • the digital control information generated by the interpolation is immediately distributed to the servo drive for immediate execution on the one hand, and iterated as the input of the next interpolation cycle to generate the next digital control.
  • Information which constitutes a real-time iteration of digital control information.
  • the digital control information is continuously generated, distributed, transmitted, and executed, and then iterated in a process iterative manner to form a real-time iteration of the control process.
  • the so-called platform independence generally means that the application software can run on multiple different kinds of CPUs and on multiple operating systems.
  • the former is hardware platform independent, and the latter is software platform independent.
  • the so-called hardware platform is the basic component of the software platform and application software running, at the bottom of the basic architecture; the so-called software platform is the basic component of the application software operation, between the hardware platform and the application software of the basic architecture.
  • the so-called NC core software is the basic software in the application software, that is, the application software module involving motion control, axis control and motion control management. For the simplicity of the description, the NC core software is simply referred to as the numerical control application software.
  • the software platform generally includes an operating system, a graphics system, and an application programming interface APT, wherein the core is a real-time operating system.
  • the multitasking operating system is just A management mechanism for internal and external resources and a response mechanism for responding to internal and external environmental changes, adapted to the management of internal and external resources and internal and external environmental changes.
  • the interpolation iterative control method transforms the management mechanism and strain mechanism of the real-time operating system into a universal control mechanism, and the real-time operating system becomes a real-time interpolation iteration to generate
  • the real-time control center of digital control information the existing CNC system forms a system architecture centered on the real-time operating system.
  • the operation rules of the interpolation iterative control algorithm are closely coupled with the task scheduling rules of the real-time operating system to form a real-time digital control method, namely the interpolation and iterative control method.
  • the interpolation iterative control method runs through the entire history of digital control technology and numerical control system, and creates the "interpolation era" of the numerical control system. .
  • the interpolation iterative control algorithm is a decompression method for digital control information, and the interpolation calculation must be performed in real time under the control of the real-time operating system.
  • the real-time operating system has high-precision timing function, multi-level interrupt nesting processing mechanism and real-time scheduling mechanism, and its core is process scheduling and thread scheduling. Real-time complexity complicates process scheduling and thread scheduling. Parallel algorithms further complicate process scheduling and thread scheduling.
  • the concurrency of thread concurrency is extremely complex compared to the concurrency of machine instruction-level pipelines and the concurrency of processor-level processes.
  • the problem is that once the speed of motion increases, or the motion accuracy increases, or the linkage axis increases, or the linkage parameters increase, the interpolation cycle of the real-time operating system must grow exponentially, requiring more bits and higher speed CPUs, more More real-time real-time operating system, more optimized real-time scheduling capabilities, and more advanced interpolation iterative control algorithms.
  • the problem is that in order to develop a large and complex interrupt system, it is necessary to be proficient in digital control technology, proficient in computer hardware and software architecture, and proficient in parallel algorithms and multi-threaded programming.
  • the open-ended existing CNC system based on the IEEE definition is completely "computerized". In terms of architecture, it is essentially a general-purpose computer system that needs to be configured with a real-time operating system.
  • the numerical control application software is only one dedicated application system, which is open. Sex can only be defined as "plug and play" for CNC applications.
  • the real-time control process is both an iterative process of digital control information and an iterative process of real-time control process, which is inseparable from the interpolation iterative control algorithm.
  • the high-speed and high-precision interpolation iterative algorithm is natural. Become the core technology in the existing CNC technology. Therefore, Sakamoto's Open System Environment for Controller believes that open CNC systems without advanced control algorithms are only evolutionary, not ideal and revolutionary.
  • the existing open CNC system based on IEEE definition is divided into two parts: system platform and application software.
  • the application software is further divided into human-machine control layer and motion control layer.
  • the motion control layer is the core of the CNC system to complete the real-time control process, and is composed of some standard components.
  • this is an architecture for application software configuration. This means that existing open digital control systems based on IEEE definitions are object-oriented rather than process-oriented.
  • the core issue of digital control systems is the real-time control of the toolpath curve.
  • the real-time control process of the tool path curve necessarily needs to be reconstructed.
  • the corresponding interpolation iterative algorithm must be developed and applied in the numerical control application software. Configure the corresponding real-time control module. Therefore, corresponding to the reconstruction of the mechanical system, the reconstruction of the real-time control process necessarily involves the modification of the real-time control module, or the replacement and addition of the real-time control module. Apart from this, there is no other technical means.
  • the real-time control process is the process of generating the coordinate value increment under the interpolation period control, the allocation process, the sending process, and the execution process. Therefore, the real-time control process is inseparable from the geometric characteristics of the tool path curve, the process characteristics of the machining process, and the kinematics/dynamics characteristics of the mechanical system. It is inseparable from the hardware platform such as the number of bits of the CPU and the operation speed. Software platforms are inseparable, and are inseparable from the interpolation iteration algorithm. This fundamentally limits the reconfiguration of the real-time control process. In other words, in the existing open CNC system based on IEEE definition, the real-time control process of the tool path curve cannot be opened and has no reconfigurability.
  • the communication cycle is the system parameter
  • Networking is an important technical feature of advanced manufacturing technology.
  • the ISO/OSI Open Systems Interconnection Reference Model is aimed at communication models between computer networks.
  • the fieldbus standard simplifies the bus architecture, and is mainly composed of a physical layer, a data link layer, and an application layer.
  • the field bus causes the communication cycle to become another system parameter, and a series of problems such as real-time communication protocol and compatibility of data representation cause high complexity and high cost of internal communication.
  • the data format of the digital control information in the real-time control process including the feed equivalent (nano or micron), the number of bytes of data, etc., will change.
  • a user layer communication protocol must be established in the field bus to standardize the data format, timing relationship and error correction mode in the data exchange within the open CNC system.
  • the communication cycle in the fieldbus becomes a factor that constrains the reconfigurability of the digital control system.
  • the G code standard is adopted as the programming interface of the NC machining program.
  • the tape was used as the basic physical medium for input, in order to standardize the characters on the tape, a coding standard for the tape perforation, that is, the G code standard was established.
  • the G code standard is the original product of the initial stage of information technology. Due to the limitation of the tape, there is inevitably a defect that the amount of information is too small. Therefore, each manufacturer has extended the basic semantics of the G code, resulting in the dependence of the G code program and the corresponding hardware. The NC machining program is not interchangeable between different CNC systems, resulting in incompatibility between various CNC systems. . Therefore, as a programming interface, the G code standard does not have the consistency of the human-machine interface, which becomes one of the bottlenecks for the further development of the numerical control technology, and also restricts the openness and reconfigurability of the digital control system.
  • One is to develop more bits, higher speed CPUs and more real-time operating systems with more digits and real-time performance. For example, in 2009, China’s national “high-end CNC machine tools and cornerstone manufacturing equipment”
  • the special plan is to list 64-bit CPU, 64-bit real-time operating system, and multi-axis linkage CNC system with an interpolation period of 0.125ms as a key technology.
  • Japan has developed a 64-bit ultra-fast chip and NURBS interpolation iterative control algorithm for motion controllers driven by the OSEC program.
  • the third is to develop a fully soft open CNC system based on ultra-high speed processor and real-time operating system.
  • the so-called all-soft open CNC system in the image, is to fully PC the digital control system with the support of real-time operating system.
  • the primary factor is the control concept generated by the IEEE definition.
  • the numerical control system is for the working machine, and its task is only to manufacture digital control information, that is, multi-dimensional associated data flow, for the working machine.
  • the multi-dimensional associated data flow cannot entrain the interpolation cycle, communication cycle, contour step length and the like which are not required by the working machine. Other information.
  • the first principle error defined by the IEEE is that, in terms of control concepts, the IEEE defines the CNC system as a real-time command center that controls the working machine, without the concept of associated data streams.
  • the second principle error defined by IEEE is that, in terms of architecture, the IEEE definition ignores the process essence of digital control, object-oriented rather than process-oriented, without the concept of control flow, defining the numerical control system as a kind of real-time operation that needs to be configured.
  • a general purpose computer system of the system A general purpose computer system of the system.
  • the third principle error defined by IEEE is that in the control method, the IEEE definition ignores the interpolation iterative control algorithm is only a decompression method of digital control information, thus the management mechanism of the internal and external resources of the real-time operating system and the response to the internal and external environment.
  • the changing strain mechanism is seen as a universal control mechanism that will The operation rules of the interpolation iterative control algorithm are closely coupled with the task scheduling rules of the real-time operating system to form a real-time control method.
  • Objects are just a kind of artificial abstraction about things in a particular hierarchy, and processes are the dynamic behavior of things moving in different hierarchies.
  • the IEEE definition completely ignores the process essence of digital control, and regards the digital control process as an object, which leads to iteration of digital control information and iteration of control flow. It is impossible to involve the openness of digital control information, the openness of digital control process and digital control. The openness of the interface between processes.
  • IEEE defines the numerical control system as the center, the defined openness is the openness of the computer system itself, the so-called open CNC system architecture is transplanted from the computer system, is an object-oriented to achieve control
  • the modular structure of the software does not reflect the technical characteristics of the CNC system throughout the control process.
  • the IEEE definition fails to examine the architecture of the open CNC system from the macroscopic view of the manufacturing system.
  • the architecture of the general computer system leads to an open concept that is ambiguous and has not been unified.
  • Descriptive vocabulary such as interoperability, portability, scalability, and interchangeability have become open-ended so-called technical specifications that hinder the standardization process of CNC systems.
  • IEEE defines object-oriented rather than process-oriented, ignoring the essence of computer digital control, CNC system is "computerized", the development of digital control technology is led to the so-called “advanced control algorithm”
  • the core problem of the CNC system is the openness and reconfigurability of the real-time control process.
  • the real-time control module cannot be opened due to object orientation, which fundamentally restricts the development of the numerical control system.
  • IEEE defines the architecture based on general computer system, limited to the functional division of numerical control software and the interface between them. For the process characteristics of digital control, the definition of system theory is lacking. Therefore, the numerical control system is defined as the configuration.
  • a general-purpose computer system of numerical control software thereby essentially defining an open numerical control system as a rigid integrated manufacturing system for manufacturing digital control information.
  • the IEEE definition is not centered on the working machine, but is centered on the numerical control system, resulting in a large amount of redundant information such as the interpolation period and the contour step, which violates the principle of simplicity. These redundant information consumes a lot of computing resources and violates economic principles.
  • the openness of the process is completely different from the openness of the object. The openness of the process necessarily involves the control flow of the generation, distribution, transmission, and execution of digital control information.
  • the IEEE defines no concept of controlling the process at all.
  • the architecture of an open CNC system defined by IEEE is not an architecture in which control resources are configured in accordance with a control flow for manufacturing digital control information.
  • the IEEE definition does not regard digital control information as a product, and does not involve the openness of digital control information.
  • G code standard is the programming interface used by existing CNC programs.
  • the G code programming interface does not have the consistency of the human machine interface.
  • the IEEE definition of the human-machine interface is too abstract, and the so-called "consistency of human-machine interface" avoids the openness of the programming interface.
  • the IEEE definition is not an open definition of a computer digital control system. It merely attempts to standardize the "plug and play" problem of the application software. It does not solve the openness of the numerical control system. Instead, it imposes the numerical control system on the architecture as a general purpose. The special computer system under the computer system architecture, so that the development of the numerical control system is firmly nailed to the "interpolation era”.
  • the digital control information produced by the numerical control system, the method of manufacturing digital control information, and the process and process interface for manufacturing digital control information are all It is closed, non-standard, and non-reconfigurable.
  • the digital control information produced becomes an internal item of the existing numerical control system. This fundamentally negates the openness and reconfigurability of the CNC system, artificially complicates the existing digital control technology and the existing open CNC system, and sets an insurmountable obstacle for the reconstruction of the CNC system. Inevitably, the existing open CNC system cannot be evolved into the control machine that the third industrial revolution hopes.
  • the inventor abandoned the IEEE definition of an open CNC system and defined the open CNC system as:
  • the so-called open CNC system is a computer numerical control system that configures embedded subsystems according to the control flow. It has an open human-machine interface, open digital control information, an open digital control information manufacturing method, and an open digital control information manufacturing process. An open interface between the digital control information manufacturing process, open application software.”
  • the openness defined by the IEEE only covers the openness of the application software and the openness of the human-machine interface when operating the computer.
  • the openness of the open CNC system has the following five aspects: 1), the openness of the human-machine interface, including the human-machine interface in all control process interfaces of the digital control information manufacturing process, especially the openness of the programming interface;
  • the openness of the digital control information refers to the openness and transparency of the digital control information generated in the digital control information generating unit.
  • the openness of the so-called digital control information manufacturing method refers to the manufacturing method that allows the user (or developer) to construct or integrate his own digital control information, that is, the real-time control method is fully softwareized and the "plug and play" of the application software.
  • the so-called openness of the digital control information manufacturing process refers to the openness and transparency of each sub-process of digital control information.
  • the internal interface of the CNC system is used to exchange information between the internal functional components of the system.
  • the openness of the interface between the so-called digital control information manufacturing processes refers to the openness of the internal interface.
  • the so-called openness of the human-machine interface refers to the openness of the programming interface.
  • the inventor invented the data flow association control method (Data- in the invention patent "Data Flow Control Method and Architecture of Computer Digital Control System” (Chinese Patent No.: ZL200710124304.9, Authorization Announcement Date: August 19, 2009) Stream Related Control (DRC control), which makes the existing CNC system farewell to the era of interpolation, has entered the era of data stream correlation control, and has produced a new generation of control machine, namely the data stream correlation control machine (DRC control machine).
  • the inventor discloses a standardized DRC control machine and its reconstruction method in the invention patent "a standardized control machine" (application number: 200910110439.9 PCT international application number: PCT/CN2010/072914), according to the generation and distribution of digital control information
  • the control flow is transmitted and executed to configure the control resource.
  • the standardized DRC control unit is composed of a digital control information generating unit, a digital control information distribution transmitting unit and a digital control information executing unit.
  • the inventor regards digital control information as a product, and the process of manufacturing digital control information by generating, distributing, transmitting, and executing digital control information is called a control flow.
  • the corresponding production equipment is configured and professionalized and standardized production is the only way for the manufacturing industry to go through.
  • the process is the basis for division of labor, professionalization, and standardized production. Foundation.
  • digital control information as a product, there must be a process flow for manufacturing digital control information.
  • the corresponding embedded subsystem must also be configured in the information manufacturing process in accordance with the control flow for manufacturing digital control information.
  • the inventor divides the control flow into three sub-processes: a digital control information generation process, a digital control information distribution transmission process, and a digital control information execution process.
  • the process of assigning and transmitting digital control information is like “military order”.
  • the execution process of digital control information is more "sports speed" and must be real-time.
  • the architecture of the open CNC system can be decoupled into a digital control information generating component (digital information manufacturing system), a digital control information distribution transmitting component (data flow controller), and a digital control information executing component.
  • a digital control information generating component digital information manufacturing system
  • a digital control information distribution transmitting component data flow controller
  • a digital control information executing component Three functional components (servo drive and I/O device).
  • step type discrete position information in the form of "' ⁇ "
  • incremental type discrete position information composed of increments of coordinate values
  • X, y, Z, A, B, W, E, and H are parameters that need real-time control (for example, W is the width of the laser pulse, E is the energy of the laser pulse, and H is the laser pulse) frequency).
  • W is the width of the laser pulse
  • E is the energy of the laser pulse
  • H is the laser pulse
  • the switch that controls the process parameters can be regarded as a virtual coordinate axis, and the parameter value is regarded as the coordinate value of the virtual coordinate axis.
  • the coordinate axis linkage is unified with the real-time control of the process parameters, which is called multi-axis multi-parameter linkage.
  • the coordinate axis includes a virtual coordinate axis.
  • Table 1 is a schematic diagram of the 8-linked multi-dimensional associated data stream.
  • the incremental discretization is AXi, ⁇ , ⁇ , ⁇ , Z Wi, ⁇ , ⁇ 3 ⁇ 4.
  • the line segments ( ⁇ Xi, ⁇ , ⁇ , ⁇ ) are referred to as L-segments of the tool path curve.
  • the X-axis first feeds ⁇ and then feeds ⁇ 2 until ⁇ ⁇ , y, Z, A, B, W, E, H and so on. Therefore, it is redundant.
  • the tool path curve it can be set appropriately, for example, it will be set to A t n . Adjust the subscripts 0, 1, ..., n-1 to 1, ..., n.
  • Table 1 indicates that for data flow correlation control, there is no essential difference between the process parameters that need real-time control and the coordinate values.
  • the switch that controls the process parameters can be regarded as a virtual coordinate axis, and the parameter value is regarded as a virtual coordinate axis. Coordinate values, so that the coordinate axis linkage and the real-time control of the process parameters are unified, which is called multi-axis multi-parameter linkage.
  • the coordinate axis includes a virtual coordinate axis.
  • the digital control information of the tool path curve includes two parts.
  • the first part is the L-segment, which describes the increment of the coordinate value when the relevant coordinate axes are linked and the required linkage, which is used to control the linkage of the relevant coordinate axes to produce the required composite displacement.
  • the second part is a T-segment, describing the follow-up between the resultant displacements, used to control the time interval between the resultant displacements.
  • the L segmentation also includes a quasi-deterministic error such as a backlash, a pitch error, a non-perpendicularity and a non-parallelism error between the drive chains, such as a deterministic error or a thermal deformation error.
  • the L segmentation of the toolpath curve forms an associated data stream under the control of the T segmentation.
  • the associated data stream can be divided into a stepped associated data stream and an incremental associated data stream.
  • the digital image generated by the L-segment of the tool path curve in the storage space is called the linkage table of the tool path curve.
  • the digital image generated by the ⁇ segmentation of the toolpath curve in the storage space is called the follower table of the toolpath curve.
  • the core task of the digital control technology is to generate the linkage table and the follower table of the tool path curve.
  • the so-called real-time control is to assign the coordinate value increment in the transmission linkage table to the corresponding servo drive device according to the control rhythm in the follow-up table.
  • L segmentation is dynamically generated in the real-time control process.
  • the digital control information generating component does not need to configure the real-time operating system, there is no interpolation cycle, and the control rhythm is not equal in length.
  • the so-called digital control information generation process is the process by which the digital control information generation component manufactures the associated data stream, that is, the linkage table of the tool path curve and the generation process of the follower table.
  • the digital control information generating unit generates a DRC NC program in accordance with the order determined by the machining process.
  • the DRC NC program consists of motion commands for controlling the machining of the workpiece.
  • Motion instructions include status instructions, switch instructions, and track instructions.
  • the status command is used to operate the auxiliary function; the switch command is used to control the I/O device; the track command is used to control the servo drive device to complete the path of a tool path curve.
  • the digital control information generating component generates a linkage table of the tool path curve by discrete geometric programming, generates a follower table of the tool path curve by the discrete motion planning, and generates a linkage table and a follower table of the standard file form according to the given data format.
  • the conventional PLC is used to control the tool magazine, or the soft PLC is used to generate the control flow of the combination logic to control the tool change process in the tool magazine.
  • the present invention does not relate to a control flow for tool magazine control.
  • the DRC NC program is a fully digital, commercial "digital control information" product manufactured by digital control information generation components.
  • the generation process of the DRC NC program is a programming process using motion instructions. Therefore, the digital control information generating component is both an open platform for numerical control programming and an open development platform for numerical control technology.
  • the so-called digital control information distribution process is that the digital control information distribution transmitting component allocates the coordinate value increments in the linkage table to the relevant servo driving device, for example, assigns ⁇ , ⁇ ⁇ , ⁇ , ⁇ , ⁇ to X, y, Servo drive devices with five axes, Z, A, B, etc.
  • the so-called digital control information transmission process is that the digital control information distribution transmitting unit controls the transmission of the digital control information in real time in accordance with the control law.
  • the so-called digital control information is executed by the servo drive device to write coordinate values into the position loop and drive the coordinate axis feed.
  • the generation of digital control information is not real-time, and the distribution, transmission, and execution of digital control information are real-time.
  • the inventor further found that the control flow of the digital control information is divided into the generation process, the distribution process, the transmission process, and the execution process, resulting in a significant improvement of the architecture of the DRC control machine, becoming a PC-based, all-round open , standardized reconfigurable computer numerical control system.
  • DRC Control Data-stream Related Control
  • the PC-based standardized control machine (referred to as the DRC control machine) is adapted to the requirements of the CNC system for the third industrial revolution.
  • the present invention improves the DRC control machine, and proposes a PC-based, all-round open, standardized reconfigurable computer digital control system.
  • a reconfigurable computer numerical control system comprising: a PC system, an interpreter program memory, a real-time control module, a servo drive device, an I/O device, a serial interface, a linkage interface, an I/O interface;
  • the PC system is connected to the servo driving device through a serial interface, and is connected to the I/O device through an I/O interface, and is used for generating a DRC numerical control program for controlling a workpiece machining process, including a state instruction generating module and a switching instruction.
  • the state instruction generating module is configured to generate a state instruction that controls the auxiliary process
  • the switch instruction generation module is configured to generate a switch instruction for controlling an I/O device
  • the trajectory command generating module is configured to generate a trajectory command for controlling a servo drive device to complete a path curve pass process
  • the trajectory instruction generation module includes a discrete geometric planning module and a discrete motion planning module; the discrete geometric planning module is configured to generate an L-segment linkage table storing a tool path curve; and the L segmentation is used to control coordinate axis linkage Generating a synthetic displacement; the linkage table is divided into an axis linkage table of each axis, the axis linkage table is used for storing an L-segment component of the relevant coordinate axis, and the coordinate axis is controlled to generate an axis displacement; the discrete motion planning module is configured to store a T-segment of the tool path curve and a follow-up table of the status word; the T-segment is used to control a time interval between the axis displacements; the status word is used to specify a coordinate axis of the linkage;
  • the DRC numerical control program generating module is configured to link a state command, a switch command, and a track command to a DRC numerical control program according to a machining process;
  • the axis linkage table distribution module is configured to allocate the axis linkage table to the servo driving device through the serial interface;
  • the DRC numerical control program running module is configured to run the DRC numerical control program, execute a state instruction control auxiliary process, execute a switch instruction to control an I/O device through the I/O interface, and execute a track instruction to start the real-time control module to pass the
  • the linkage interface controls the servo drive device to complete the machining process of the tool path curve;
  • the interpretation program memory is configured to store the state instruction, the switch instruction, and an interpretation program of the track instruction;
  • the servo drive device is provided with an axis linkage table initialization module and an axis linkage table control module; the axis linkage table initialization module is configured to set an execution flag, and according to the sequence code of the track instruction, the first of the axis linkage table The address is written to the L pointer; following the linkage command, the axis linkage table control module reads the coordinate value increment of the axis from the axis linkage table according to the L pointer and writes the position loop, and drives the coordinate axis feed to generate Synthetic displacement.
  • the number of bytes of the status word is a user parameter.
  • the axis linkage table file further includes a feature table; the feature table is used to identify a logical attribute of the coordinate axis; and the logical attribute includes a feed equivalent, a number of bytes of data, and an electronic gear ratio.
  • Each data bit of the linkage interface is respectively connected to a servo drive device.
  • the serial interface is a field bus, an RS232 interface, an RS485 interface, a USB interface, or a wireless interface.
  • the DRC numerical control program running module includes a motion instruction fetching module, a state instruction execution module, a switch instruction execution module, and a track instruction execution module;
  • the motion instruction fetching module is configured to write a first address of the DRC numerical control program into the motion instruction pointer And reading the motion instruction, writing the function byte of the motion instruction into the motion instruction register, and writing the address of the next motion instruction to the motion instruction pointer;
  • the motion instruction pointer is used to specify the address of the next motion instruction;
  • the motion instruction is a state instruction, and the state instruction execution module is configured to execute an interpretation program of the state instruction; if the motion instruction is a switch instruction, the switch instruction execution module is configured to execute an interpretation program of the switch instruction;
  • the motion instruction is a track instruction, and the track instruction execution module is configured to execute an interpretation program of the track instruction.
  • the track instruction execution module sets a running flag to start the real-time control module;
  • the real-time control module includes a linkage coordinate axis setting module, a linkage command setting module, a rhythm control module, and an end point control module;
  • the setting module is configured to write the first address of the following table to the T pointer, read the status word from the following table and write the status word register, and specify the coordinate axis of the linkage;
  • the timing time in the T-divided timer is up,
  • the rhythm control module is used to start the pulse generator to output a pulse Transmitting, by the linkage interface, a linkage command to the servo drive device specified by the status word register;
  • the end point control module is configured to control an end point of the track instruction, and if the T pointer is equal to the last address of the follower table, When the end
  • the digital control method of a reconfigurable computer numerical control system proposed by the present invention comprises the following steps:
  • Step 1 DRC NC program generation steps: For PC system 1 Generate DRC NC program, including the following steps:
  • Step 101 The trajectory instruction generating step: the trajectory command generating module generates a trajectory command for controlling the servo drive device 4 to complete the path curve passing process, including a discrete geometric planning step and a discrete motion planning step; and the discrete geometric planning step is used for the discrete geometric planning module Generating an L-segment linkage table storing a tool path curve; the L segmentation is used to control the coordinate axis linkage to generate a composite displacement; the linkage table is divided into an axis linkage table of each axis, and is used for storing the L-segment component of each coordinate axis Controlling the coordinate axis to generate an axis displacement; the discrete motion planning step is used by the discrete motion planning module to generate a T-segment of the tool path curve and a follow-up table of the status word; the T-segment is used to control between the axis displacements Time interval; The status word is used to specify the coordinate axis of the linkage.
  • Step 102 State instruction generation step: The state instruction generation module generates a state instruction for controlling the auxiliary process.
  • Step 103 The switch command generating step: The switch command generating module generates a switch command for controlling the I/O device.
  • Step 104 The DRC numerical control program generating step: the DRC numerical control program generating module links the state command, the switch command, and the track command to a DRC numerical control program according to a machining process.
  • Step 2 Axis linkage table assignment step: The axis linkage table assignment module 15 distributes the axis linkage table to the servo drive unit 4 via the serial interface 6.
  • Step 3 DRC NC program running steps: DRC NC program running module 16 Run the DRC NC program, including the following steps:
  • the motion instruction fetching step the motion instruction fetch module 161 writes the first address of the DRC NC program to the motion instruction pointer and reads the motion instruction, and writes the function byte of the motion instruction into the motion instruction register, and sets the address of the next motion instruction.
  • State instruction execution step If the motion instruction in the motion instruction fetch step is a status instruction, the status instruction execution module 162 executes an interpretation program of the status instruction;
  • the switch instruction execution step if the motion instruction in the motion instruction fetching step is a switch instruction, the switch instruction execution module 163 executes an interpretation program of the switch instruction;
  • the trajectory instruction execution step if the motion instruction in the motion instruction fetching step is a trajectory instruction, the trajectory instruction execution module 163 executes an interpretation program of the trajectory instruction.
  • the trajectory instruction execution step sets the operation flag, and starts the following real-time control steps:
  • Step a linkage axis setting step: According to the sequence code of the track instruction, the linkage axis setting module 31 writes the first address of the following table to the T pointer, reads the status word from the following table, and writes the status word. Register, specifying the coordinate axis of the linkage;
  • Step c rhythm control step: The timing time in the T split timer is up, the rhythm control module 33 starts the pulse generator to output a pulse, and sends a linkage command to the servo drive device 4 specified by the status word register through the linkage interface 7;
  • Step d linkage table control step: following the linkage command, the axis linkage table control module 41 of the servo drive device 4 reads the coordinate value increment from the axis linkage table according to the L pointer, writes the position loop, and drives the coordinate axis into Give a synthetic displacement;
  • Step e End point control step: The end point control module 34 controls the end point of the track command. If the T pointer is equal to the last address of the follower table, that is, the end point of the track command is reached, the running flag is turned off; otherwise, the T pointer points to the next repeating step. b to step e.
  • the reconstruction method of a reconfigurable computer numerical control system proposed by the present invention comprises the following steps: Step 1. Reconstructing a discrete coordinate system: PC system 1 reconstructs a discrete coordinate system; the discrete coordinate system includes orthogonal discrete coordinates And non-orthogonal discrete coordinate systems.
  • Step 2 reconstructing a structure constant database: the PC system 1 reconstructs a structure constant database; the structure constant database stores a fine structure constant of the coordinate axis and a coordinate system parameter; the fine structure constant of the coordinate axis includes a line displacement error, an angular displacement Error, backlash;
  • the coordinate system parameters include non-parallelism and non-perpendicularity between the coordinate axes.
  • Step 3 Reconstructing the state instruction: the PC system 1 reconstructs the state instruction; the state instruction is used to control the auxiliary process;
  • Step 4 Reconstruct the switch command: The PC system 1 reconstructs the switch command; the switch command is used to control the I/O device. Compared with the prior art, the original beneficial effects produced by the present invention are:
  • Finite state machine processing data model is used to describe complex control tasks with different levels of real-time requirements.
  • Finite state machine is anti A highly abstract modeling tool for the system, the structure is complex and reusable for developers; for the user, it is like a spider web maze, no openness.
  • Data flow association control is not object-oriented, but process-oriented. According to the process characteristics of digital control, the present invention proposes a machining process model for an open numerical control system.
  • the interpolation cycle of the real-time operating system and the communication cycle of the field bus are two system clocks. Following the cycle of the interpolation cycle and the communication cycle, the digital control information of the tool path is continuously generated, distributed, transmitted, and executed, so that the real-time iteration of the digital control information and the real-time iteration of the control process are repeated.
  • the real-time control process of the toolpath curve includes both real-time iteration of the digital control information and real-time iteration of the control process, as well as real-time communication processes, including the accuracy and speed of the interpolation iterative algorithm, and the geometry of the toolpath curve.
  • a series of complex factors such as characteristics, process characteristics of the machining process, kinematics/kinetics of the mechanical system, hardware platforms such as the number of bits of the processor and the operating speed, and software platforms such as real-time operating systems.
  • the invention configures the control resources according to the control flow of the generation, distribution, transmission and execution of the digital control information, and the process of generating and controlling the digital control information is not real-time, and the real-time control process of the toolpath curve is simplified to start the real-time control module according to
  • the coordinate value increments in the table are successively written into the position loop, and the corresponding coordinate axes are driven to generate a composite displacement.
  • the extremely complex real-time communication cancels the control of the real-time control process of the fieldbus, thus transforming the real-time control process of the toolpath curve into the real-time transmission of the simplest linkage command, completely eliminating the real-time control of the operating system and the fieldbus.
  • the constraints of the process have realized the openness of the real-time control method and the real-time control process, leading to major changes in the digital control method.
  • Multi-axis synchronous drive technology is a key technology to be solved in the existing numerical control technology.
  • the dual-axis synchronous drive technology is listed as a key technology in the existing CNC technology.
  • multi-axis synchronization depends on the real-time synchronization mechanism of periodic communication in the fieldbus.
  • the multi-axis synchronization depends on the linkage command transmitted in real time through the linkage interface, and the coordinate axes of the linkage are specified by the status word.
  • the linkage command is a parallel synchronization pulse
  • the status word is a user parameter
  • the linkage interface is similar to a parallel interface under the control of a status word. Therefore, the present invention solves the problem of multi-axis synchronization mechanism with extremely simple technical means, and has high-speed and high-precision synchronization capability, thereby converting complex multi-axis synchronous drive technology into a simple conventional technique.
  • Reconstruction of the mechanical system means a change in the motion relationship of the coordinate axes and an increase or decrease in the coordinate axes, especially the increase in the coordinate axis. Therefore, the reconfigurability of the real-time control process of the tool path curve becomes the core problem of the reconfigurable computer digital control system, which requires the real-time control method to be completely software-based.
  • the real-time control process is independent of the software platform such as the operating system and field bus. Independent of the programming interface.
  • the existing open CNC system based on IEEE is object-oriented rather than process-oriented, and the real-time control process of the tool path curve cannot be opened and has no reconfigurability.
  • dedicated interpolation instructions must be defined and a specific real-time interpolation control module must be configured. Therefore, the interpolation instructions under the G code standard are not reconfigurable.
  • the prior art based on the IEEE definition can only increase the real-time interpolation control module or modify the existing real-time interpolation control module. Obviously, this is far from the connotation of reconfigurability.
  • the prior art based on IEEE can only resort to the high-speed CPU of 64 bits or more and the stronger real-time of 64-bit or more.
  • the trajectory command in the present invention has only one format, regardless of the type of curve in the tool path curve. There are no refactoring issues.
  • the DRC numerical control program, the shaft linkage table, the follower table and the like manufactured by the PC system include all the digital control information required for controlling the servo drive device and the I/O device, and the digital control information is open, manufactured.
  • the method of digitally controlling information is open; in addition, the present invention also de-realizes the digital control information distribution process, and converts the real-time transmission of digital control information into a real-time transmission of extremely simple linkage commands, and the digital control information distribution process is also open. .
  • the real-time control process of the tool path curve is simplified to start the real-time control module.
  • the real-time control module is open, with a built-in hardened file reading module that operates independently of the PC's operating system and does not require any embedded real-time operating system.
  • the invention has neither an interpolation cycle nor a communication cycle, and fully realizes the softwareization of the real-time control method, completely solving the reconstruction problem of the real-time control process of the toolpath curve.
  • Both the status command and the switch command are inseparable from the specific structure of the mechanical system and are a personalization function. After the mechanical system is reconfigured, state commands and switching instructions often need to be reconstructed.
  • the structure and function of the status command and the switch command are extremely simple, and it is a simple and familiar technique for the user to redefine the state command and the switch command at the user layer of the PC and to write the interpretation program.
  • the reconstruction of the digital control system also involves the reconstruction of the internal interface, especially the reconstruction of the motion control level real-time interface.
  • the invention divides the motion control interface into a non-real time serial interface and a real-time linkage interface.
  • the linkage interface of the present invention is not a communication interface, and the linkage command is only a synchronization pulse.
  • the non-real time interface of the present invention is a standard serial interface, such as a standard USB interface or other standard serial interface supported by the UART, which is a conventional technique.
  • the non-real time interface does not need to be reconstructed.
  • the PC system, the real-time control module, and the motion control interface are independent of the software platform such as the operating system, and are also independent of the hardware platform.
  • the reconfigurable computer numerical control system proposed by the present invention is platform independent.
  • the reconstruction of the digital control system also involves a programming interface.
  • the NC machining program in the form of G code must be controlled under the control of the real-time operating system, thus being related to the software and hardware platform.
  • the G code standard does not have the consistency of the human machine interface.
  • the DRC numerical control program replaces the G code program with a standardized file system, and has a man-machine interface consistency, and there is no reconstruction problem.
  • the reconstruction of the digital control system involves only the reconstruction of the discrete coordinate system and the reconstruction of the structure constant database.
  • the present invention converts the reconstruction method of the reconfigurable computer digital control system into a conventional technical means in the PC, has excellent reconfigurability, and completely solves the reconstruction problem of the reconfigurable computer digital control system.
  • the architecture of the reconfigurable computer digital control system proposed by the present invention configures control resources based on a control flow of generation, distribution, transmission, and execution of digital control information.
  • the invention is in the figures During the control information distribution process, the axis linkage table is distributed to the servo drive device through the non-real-time serial interface, thereby de-realizing the digital control information distribution process, which significantly simplifies the architecture of the reconfigurable computer digital control system.
  • the digital control information generating unit is a standardized component based on the PC.
  • the digital control information files such as the DRC NC program, the axis linkage table, and the follower table manufactured by the digital control information generating unit are standard files, and are independent of software platforms such as the operating system.
  • the standardized file system becomes the carrier of digital control information, realizing the openness of digital control information.
  • the real-time control module does not need to be configured with an operating system, and its core function is only to write ⁇ into the T-split timer, and in the state word control, the linkage command is sent in real time through the linkage interface, and the function and structure are extremely simple and can be standardized.
  • the standardization of digital control systems also involves the standardization of internal interfaces, in particular the standardization of real-time interfaces at the motion control level.
  • fieldbus technology In the existing open CNC system based on IEEE definition, in order to realize real-time allocation of coordinate value increments, fieldbus technology has become the mainstream technology of motion control interface between CNC system and servo drive device.
  • the fieldbus technology is based on the ISO/OSI open system interconnection reference model, completely ignoring the process characteristics of digital control, completely ignoring the essential characteristics of numerical control devices that are different from computer networks.
  • the communication cycle becomes the system clock, and the data link layer and the application layer and its protocol are real-time, and the data representation is compatible with a series of problems, which consume a lot of computing resources.
  • the invention divides the motion control interface into a non-real time serial interface and a real-time linkage interface.
  • the axis linkage table of each axis is assigned to the corresponding servo drive via the serial interface.
  • the communication cycle is not a system parameter, and there is no synchronization mechanism, which avoids the real-time nature of the communication protocol and other complicated problems.
  • the axis linkage table is a standard file, and there is no compatibility problem with data representation.
  • the serial interface can be any standard serial interface, such as a standard USB interface or other standard serial interface supported by the UART.
  • the linkage command is just a sync pulse.
  • the linkage interface is similar to an interrupt control line.
  • the linkage interface can be standardized. Therefore, the linkage interface and the non-serial interface are both standardized, and the standardization problem of the motion control interface is solved.
  • the G code standard is adopted as the programming interface of the NC machining program.
  • the tape was used as the basic physical medium for input, in order to standardize the characters on the tape, a coding standard for the tape perforation, that is, the G code standard was established.
  • the G code standard is the original product of the initial stage of information technology. Due to the limitation of the tape, there is inevitably a defect that the amount of information is too small. Therefore, each manufacturer has extended the basic semantics of the G code, resulting in the dependence of the G code program and the corresponding hardware.
  • the CNC machining program is not interchangeable between different CNC systems, and does not have the consistency of human-machine interface. The various CNC systems are incompatible with each other, hindering the exchange and sharing of control information, and restricting the openness and reconfigurability of the digital control system from the programming interface.
  • each axis must have the same logical properties. Once the logical attributes of the coordinate axes are different, for example, the feed equivalent (nano, micron, etc.) is different, the number of bytes of the data is different, etc., the functions and structures of the numerical control system must be changed accordingly, from real-time control process and real-time communication. The two aspects of the process restrict the openness and reconfigurability of the system.
  • the DRC numerical control program is written by using a state command, a switch command, and a track command according to the order determined by the machining process.
  • the DRC NC program is oriented to the control flow, and the trajectory command is oriented to the machining process of the tool path curve.
  • the axis linkage table and the follower table carry all the digital control information required to process the tool path curve, which is manufactured by the digital control information generating component in a non-real time, thus allowing each coordinate axis to have a different logical attribute.
  • the above DRC NC program, axis linkage table, and follower table are transmitted in the system in the form of standardized files, and are also transferred between different CNC systems in the form of files.
  • the above documents conform to the file specification and use file systems such as FAT16 and FAT32.
  • the standardized file becomes the carrier of digital control information, has nothing to do with the hardware platform, has nothing to do with the software platform such as the operating system, has extensive platform independence, and realizes the openness of digital control information.
  • the above-mentioned DRC numerical control program, axis linkage table and follow-up table all adopt standardized file system, realize the standardization of control information, and become an easy-to-standardized programming interface.
  • the reconfigurable computer digital control system proposed by the present invention realizes the openness of digital control information, the openness of the digital control method, the process of generating digital control information, the process of distribution, the process of sending, and the whole process of execution. Sexuality has laid a solid foundation for the standardization of digital control systems.
  • the state instruction, the switching instruction, the trajectory instruction and the DRC numerical control program proposed by the invention are oriented to the working machine, the logic structure is simple, the human-machine interface is consistent, the PC-based and no compilation is required,
  • the open, universal, and efficient motion description language and logic description language of CNC technology fully support users to expand the application of CNC technology and maintain the consistency of human-machine interface.
  • the interpolation cycle and the communication cycle are two system parameters, which not only consume a large amount of computing resources, but also generate, distribute, transmit, and execute digital control information.
  • the real-time control process leads to real-time operating system and fieldbus becoming two key links that restrict the reliability of the CNC system.
  • the operating system is an extremely complex system that may contain hundreds of thousands of potential vulnerabilities. These vulnerabilities often take years, ten years of maintenance time to fix, and are difficult to eliminate completely. According to statistics, the factors that affect the reliability of computer systems are only a few percent of hardware errors. The vast majority of errors come from system management. Obviously, system management errors are basically derived from the operating system. Therefore, for the reliability of computer numerical control systems, the real-time operating system is like the sword of Damocles.
  • the communication process is exposed to harsh industrial environments.
  • the fieldbus causes the communication cycle to become a system parameter, and the communication protocol's real-time performance and data representation compatibility lead to a series of problems.
  • Internal communication is highly complex and is another important reason for reliability.
  • the PC does not participate in the real-time control process of the toolpath curve, and the operation of the real-time control module is independent of the operating system of the PC, and there is no need to configure any embedded real-time operating system.
  • the invention separates the digital control information distribution process from the real-time control process of the digital control information, completes the process of distributing the digital control information in one communication process, and the communication cycle is no longer a system parameter.
  • the linkage interface of the present invention simply transmits the synchronization pulse unidirectionally, and the function and structure are highly simplified.
  • the present invention solves two key links that restrict the reliability of the numerical control system from the source, and has high reliability.
  • the control machine expected by the third industrial revolution
  • the architecture of modern manufacturing equipment can be abstracted into three systems, namely, power, work and control.
  • the power machine provides energy
  • the control machine sends control information to the working machine and the power machine
  • the working machine obtains energy from the power machine to complete the manufacture of the product.
  • the symbol of the second industrial revolution was the birth of a power machine.
  • the steam engine, internal combustion engine, and electric motor replaced human power and animal power.
  • the third industrial revolution will be based on automation, the birth of the control machine.
  • FIG. 1 is a first schematic diagram of a process model based on a control flow
  • Figure 2 is a second diagram of the machining process model based on the control flow
  • FIG. 3 is a schematic structural diagram of a numerical control system in a specific embodiment
  • FIG 4 is a functional block diagram of the PC system of Figure 1;
  • Figure 5 is a functional block diagram of the real-time control module of Figure 1;
  • Figure 6 is a functional block diagram of the servo drive device of Figure 1.
  • DETAILED DESCRIPTION In order to ensure that the machine tool structure and its layout can be quickly reorganized according to the changes of the processed products, the modular structure becomes the basic technical feature of the reconfigurable machine tool. Often, the concept of modularity and its implementation are limited to machine tool builders. However, in reconfigurable machine tools, the concept of modularity and its implementation must extend to the user. In other words, user orientation is an essential feature of reconfigurability.
  • reconfigurability refers to the ability of the user to quickly reorganize the structure, layout, and machining functions of the machine tool based on changes in the product being processed.
  • Reconfigurable computer digital control systems are also generally considered to be modular in relation to the modularity of reconfigurable machine tools.
  • the core function of the digital control system is to control the machining process of the tool path curve in real time. This means that for reconfigurable computer numerical control systems, the real-time control of the toolpath curve must be open and thus user-oriented.
  • the real-time control process of the tool path curve cannot be opened.
  • the numerical control application software system for real-time control process becomes a large and complex interrupt with parallel algorithm, multi-process/multi-threaded nested call and multiple real-time nested interrupts under the control of real-time operating system. system.
  • the real-time control process of the tool path curve is inseparable from the geometric characteristics of the tool path curve, the process characteristics of the machining process, and the kinematics/dynamics characteristics of the mechanical system. It is inseparable from the hardware platforms such as the number of bits of the CPU and the operation speed. It is inseparable from software platforms such as real-time operating systems, and is inseparable from the interpolation iterative algorithm.
  • the so-called real-time control modular structure is essentially an object-oriented modular structure, that is, different real-time control modules are configured for different tool path curves.
  • this object-oriented modular structure is not user-oriented, but is aimed at CNC manufacturing companies, and runs counter to the essential features of reconfigurability.
  • relying on this object-oriented modular structure to achieve reconfigurability of a digital control system is only an illusion.
  • the so-called reconfigurable computer digital control system is a computer digital control system that configures the embedded subsystem according to the control flow, with real-time control method software, real-time control process and processor platform digits, speed and other hardware platforms, and operating system The independence of the software platform, and the independence from the programming interface.
  • Data flow association control configures control resources in accordance with the flow of manufacturing digital control information.
  • the DRC numerical control program becomes a fully digital and commercial "digital control information" product manufactured by digital control information generating components.
  • the digital control information generating component is not only an open platform of numerical control programming but also an open development platform of numerical control technology, and the real-time control method is completely softwareized.
  • the servo drive device In the architecture of the existing open CNC system, the servo drive device is regarded as a functional component of the CNC machine tool and is not in the category of the CNC system. According to the above definition of the reconfigurable computer digital control system, the present invention further improves the DRC control machine from the aspects of control flow, architecture, field bus, programming interface and the like. These problems require the servo drive to be incorporated into the CNC system, revisiting the function and structure of the servo drive.
  • the servo drive device includes a servo motor and its motion control system, which is mainly used to control the rotation speed and rotation angle of the servo motor.
  • the so-called speed control is also called speed mode, that is, speed control, used to control the speed of the spindle;
  • the so-called corner control is also called position mode. That is, position control, used to control the displacement of the coordinate axis.
  • the servo drive device is in the position mode, and the digital control information received and executed is discrete position information of the coordinate axis, and the position feedback information is processed by the embedded system in the servo drive device.
  • the spindle speed it is regarded as a process parameter, which is attributed to the switch quantity control with parameters.
  • the core task of the digital control technology is to generate a linkage table and a follower table of the tool path curve.
  • the so-called real-time control process is based on the control rhythm in the follow-up table, the process of assigning coordinate increments, the sending process, and the execution process.
  • Servo drive devices such as B, etc.; servo drives such as X, y, Z, A, B receive ⁇ 2 , ⁇ ⁇ 2 , ⁇ 2 , ⁇ 2 , ⁇ 2 , write their position loops, drive X, y, Z, A, B, etc. 5 axes linkage, to achieve the synthetic displacement AL 2 ; so repeated, so as to produce the synthetic displacement required by the cutting curve according to the control rhythm, until the end of the tool path curve. Generate component generation.
  • the digital control information distribution transmission process can be separated into digital control information.
  • the real-time control process is that the X, y, Z, A, 8 and other servo drive devices follow the control rhythm in the follower table.
  • the coordinate value increments are read synchronously in real time in five axis linkage tables and executed.
  • the machining data model of the CNC system is the basis for planning the architecture and developing the CNC technology.
  • the processing data model is used to describe the function, behavior, starting process, and the relationship between each object in the numerical control system, especially for complex, Multiple control tasks required by different levels of real-time requirements are clearly described. Therefore, the processing data model using the Finite State Machine (FSM) plays an important role in the development of open digital control systems.
  • FSM Finite State Machine
  • the finite state machine is a highly abstract modeling tool for reactive systems. For developers, the structure is complex and the reusability is poor. For the user, it is like a spider web maze, and there is no openness.
  • Data flow association control is not object-oriented, but process-oriented.
  • An open machining process model must be proposed for open CNC systems based on the digitally controlled process characteristics.
  • the invention divides the control flow into four sub-processes: a digital control information generation process, a digital control information distribution process, a digital control information transmission process and a digital control information execution process, and then the digital control information distribution process is controlled from the digital control information in real time. Separation becomes a non-real-time process.
  • the architecture of the digital control system is decoupled into a digital control information generating component, a digital control information distributing component, a digital control information transmitting component, and a digital control information execution.
  • a digital control information execution unit includes a servo drive and an I/O device.
  • the control process can be divided into a real-time process and a non-real-time process. From the perspective of reconfigurability, the functions and structures of the four functional components should be re-examined, and the real-time and non-real-time process control methods should be re-examined.
  • the structure of the DRC NC program as the digital control processing should be re-examined from the aspect of reconfigurability to support the real-time control process and the non-real-time distribution process.
  • the program interface refers to a programming interface between machining programs when exchanging machining programs between different numerical control systems.
  • the DRC NC program becomes the programming interface. After the digital control information distribution process is separated from the real-time control process of the digital control information, the file becomes digital control in the control flow. The carrier of information. Therefore, the DRC NC program file is independent of the operating system platform. However, from the perspective of reconfigurability, the DRC NC program should be used as a programming interface and should be independent of the field bus.
  • the axis linkage table is allocated to the servo drive device in real time, the real-time control process is highly simplified, the real-time communication process of the internal interface is highly simplified, and the function of the internal interface is The structure and structure should be revisited to support the reconfigurability of the real-time communication process.
  • the invention provides a reconfigurable computer numerical control system, from an open architecture of a digital control system, a control method of a real-time process and a non-real-time process, a structure and a programming interface of a DRC numerical control program, a function and structure of an internal interface, and a servo
  • the DRC control machine is further improved in terms of functions and structures of the driving device to meet the requirements of the third industrial revolution for the reconfigurable computer digital control system.
  • the machining process of the workpiece can generally be divided into auxiliary process, tool change process and tool pass process.
  • the auxiliary process involves auxiliary functions and status settings controlled by the I/O device.
  • the tool change process involves tool magazine control.
  • the conventional PLC is used to control the tool magazine, or the soft PLC is used to generate the control flow of the combination logic to control the tool change process.
  • the present invention does not relate to a control method of a PLC and an I/O device.
  • the pass process involves real-time control of the tool path curve.
  • the CNC system has only three working states: auxiliary function operation, switch quantity control, and real-time control of the tool path curve.
  • the data flow association control describes the three working states by using three types of motion commands: a status command, a switch command, and a track command.
  • Status instructions can be divided into system initialization status instructions and system operation status instructions.
  • the system initialization status command is used to set/modify some parameters, such as setting the initialization parameters of the servo drive, initialization parameters of the tool magazine, and so on.
  • the system running status command is used to set the running status of the system. For example, set the running status of automatic, manual, specified block, start, end, pause, etc. to realize functions such as detection, parameter adjustment and fault diagnosis.
  • Status instructions include function bytes, auxiliary bytes.
  • the function byte is 2 bytes and is used to describe the basic functions of the status instruction, including the identification code and the instruction code.
  • the first function byte is the identification of the status instruction.
  • the second function byte is the function code of the status instruction, which has a total of 256 status instructions.
  • the auxiliary byte is a number of bytes that identify multiple parameter values for the status instruction, each parameter occupying 2 bytes.
  • the status command also includes a diagnostic command for allocating a series of specific data to the servo drive to diagnose a fault in the linkage table assignment process.
  • the switch command is used to describe the parameters of the switch and its control.
  • the present invention is considered to be a virtual coordinate axis if the switch carries process parameters that require real-time control.
  • the switch is a conventional PLC control if it does not carry process parameters that require real-time control.
  • the spindle speed control can be regarded as a switch carrying parameters (speed).
  • the tool change command is a regular PLC control.
  • the present invention treats the tool change command as a switch command. As a conventional technique, the present invention does not relate to a specific control process of a tool change command.
  • the switching instructions include function bytes and auxiliary bytes.
  • the function byte is 2 bytes and is used to describe the basic functions of the switch instruction, including the identification code and the instruction code.
  • the first function byte is the identification of the switch instruction.
  • B 4 ⁇ B. 5-digit signature, the number of identification parameters, can carry up to 32 parameters.
  • the second function byte is the function code of the switch command, a total of 256 switch commands.
  • the auxiliary byte is a number of bytes that identify multiple parameter values for the switch instruction, each parameter occupying 2 bytes.
  • the user (or developer) can define its own auxiliary byte and define its function by rewriting the interpreter. Therefore, the instruction format of the status instruction and the instruction format of the switch instruction are both open, supporting the secondary development of the user (or developer).
  • the process parameters that need real-time control are carried by the switch.
  • This switch is called the virtual coordinate axis
  • the process parameter is called the coordinate value of the virtual coordinate axis. Therefore, in the present invention, the coordinate axis includes a virtual coordinate axis.
  • the track instruction is a single-byte instruction, only one format, the instruction code is:
  • the sequence code establishes a correspondence between the path command of the tool path curve and the linkage table and the follower table carried by the tool path; the linkage table is used to control the linkage of the relevant coordinate axes to generate the required composite displacement; the follower table is used for control The time interval between the synthetic displacements.
  • the track command has only one format, regardless of the type of curve in the tool path curve.
  • DRC NC program
  • the path of the tool center is called the Tool Path.
  • the L segmentation ⁇ , ⁇ ⁇ , ⁇ , ⁇ , AW ⁇ ⁇ , / 3 ⁇ 4 of a tool path curve is called the L segmentation linkage table in the data file of the storage space.
  • is an unsigned 2-byte binary integer.
  • the coordinate value increment ( ⁇ ⁇ ⁇ ) is the signed binary integer represented by the original code, and the highest bit is the sign bit (+/-), which corresponds to the forward/reverse rotation of the coordinate axis.
  • the feed equivalent (nano or micron) of the coordinate value increment ⁇ yi, etc., and the number of bytes occupied by the data may be different.
  • the numerical control equipment has only three working states: auxiliary function operation, logic control of I/O device, and real-time control of the tool path curve. Therefore, the machining process of the workpiece can be generally divided into an auxiliary process, a tool change process and a tool change process.
  • the auxiliary process involves auxiliary function operation
  • the tool change process involves tool magazine control
  • the pass process involves real-time control of the tool path curve.
  • the CNC system has three types of motion commands: state commands, switch commands, and track commands.
  • state commands e.g., state commands
  • switch commands e.g., switch commands
  • track commands e.g., track commands
  • the user uses the status command, the switch command, and the track command to describe the entire machining process of the workpiece.
  • the set of motion instructions that are determined by the machining process is the NC machining program of the workpiece machining process, and the present invention is referred to as the DRC NC program.
  • the DRC NC program is a digital product manufactured by a digital control information manufacturing system, thereby fully digitizing the traditional form of control information, such as paper, G code programs, and the like.
  • the DRC numerical control program is composed of motion instructions for controlling the machining process of the workpiece; the motion instructions include state commands, switch commands, and track commands; Status commands are used to operate the auxiliary functions.
  • the switch command is used to control the I/O device.
  • the path command is used to control the servo drive to complete the path of a tool path curve.
  • the structure of the DRC NC program is also the digital structure of the product.
  • the structure of the DRC NC program determines the function and structure of the DRC controller. Conversely, the function and structure of the DRC controller affect the structure of the DRC NC program.
  • the machining of the workpiece generally involves multiple passes. Each pass process completes a knife path curve.
  • a tool path curve usually consists of several segments of curves.
  • the geometry of each segment may be the same or different.
  • the axes of each segment may or may not be the same.
  • the invention is not segmented according to the geometry of the curve, but is segmented according to the coordinate axes of the linkage.
  • the axes of the linkages in each segment are the same and are described by a track command. Therefore, the processing of a tool path often uses multiple track commands.
  • the sequence code in the track command is used to number the track commands in the processing order.
  • the linkage table is divided into an axis linkage table according to the coordinate axes of the linkage.
  • the X-axis linkage table for ( i ⁇ , . , ., ⁇ )
  • the trajectory command corresponds to the axis linkage table and the follower table of the tool path curve.
  • the status word is set in the follow-up table to identify the coordinate axes in the segment.
  • the status word is one byte, and the number of bytes can be 32, 16, or 8.
  • an 8-bit status word can specify 8 linked coordinate axes. From low to high, each bit of the status word controls the enable state and data path of a servo drive. For example, the status word "11100000" specifies the servo drive, status word for axes such as X, y, Z, etc.
  • the number of digits and the number of status words are user parameters.
  • the user can set the number of bits and the number of bytes of the status word through the status command.
  • each axis linkage table file to identify the logical attributes of the axes in the segment curve; the logical attributes of the axis include the feed equivalent (nano, micro, etc.), the number of bytes occupied by the data, Includes servo parameters such as electronic gear ratio. Therefore, each axis allows different feedrates, different numbers of data bytes, and different electronic gear ratios in one machining process to meet the needs of high-speed, high-precision machining.
  • the file directory In order to access files by name, the file directory includes a large amount of information such as file name, physical address, file structure, and access control.
  • the DRC NC program, the axis linkage table, and the follower table all adopt the standard file format.
  • the rich information and the large amount of information of the programming interface are difficult to implement by the G code program programming interface.
  • the DRC NC program is an executable file; the axis linkage table and the follower table are data files.
  • the DRC NC program, the axis linkage table, and the follower table all use standard file systems such as FAT16 and FAT32.
  • a file system is a method of organizing files on disk.
  • FAT File Allocation Table
  • the file reading module is configured to read related sector addresses and data area addresses of the FAT table, the FDT table, the BPB table, and the like, and does not need to configure an operating system, thereby independently completing all functions of file management: opening, creating, or deleting Files, enumerates and searches for files, supports long file names, and more.
  • the data flow association control is process oriented, and the control resources are configured in accordance with a control flow for manufacturing digital control information.
  • the non-real-timeization of the axis linkage table allocation process leads to the separation of the digital control information distribution process from the real-time control process of the digital control information.
  • the control process is divided into the digital control information generation process, the digital control information distribution process, and the digital control information transmission process.
  • the four sub-processes of the digital control information execution process, the architecture of the digital control system is decoupled into four functional components: a digital control information generating component, a digital control information distributing component, a digital control information transmitting component, and a digital control information executing component.
  • control processes can be divided into real-time processes and non-real-time processes.
  • the digital control information generation process and the digital control information distribution process are non-real-time processes, and the digital control information transmission process and the digital control information execution process are real-time processes.
  • the process of digital control information generation is the process of manufacturing the associated data stream, that is, the process of generating the linkage table and the follower table of the tool path curve.
  • the digital control information generation process also includes the generation process of the DRC NC program, that is, the programming process of the machining process.
  • the digital control information generation process is a non-real time process.
  • the digital control information generating unit generates a DRC numerical control program, which includes the following contents:
  • the mechanical attribute includes a linear structure error such as a linear displacement error of the coordinate axis, an angular displacement error, a backlash, and the coordinate axis Coordinate system parameters such as non-parallelism and non-perpendicularity;
  • plan the tool path curve complete the tool compensation and tool path planning, and generate the tool path curve file
  • the link status command, the switch command, and the track command, the DRC digital control program is generated; the last motion command is the "stop" status command for ending the machining.
  • the digital control information distribution process is to assign an axis linkage table to the servo drive. Assign control information in the catalog of the axis linkage table.
  • the digital control information transmission process and the digital control information execution process involve the operation of the DRC NC program.
  • the DRC NC program running process is also the execution process of the motion instruction, including reading the motion instruction from the DRC numerical control program and the interpretation program for executing the motion instruction.
  • the function byte of the motion instruction is written into the motion instruction register, and the other bytes are analyzed and processed, and the address of the next motion instruction is written into the motion instruction pointer; during execution, the interpretation program of the motion instruction is executed, The function specified by the motion instruction is completed.
  • the interpretation of the track instruction is executed.
  • the state instruction and the execution of the switch instruction are auxiliary processes, and the requirements for real-time performance are not high, which is a conventional technique.
  • the execution process of the trajectory command is the pass process, which is the real-time control process of a tool path curve, which is the core function of the CNC system.
  • the machining of the workpiece generally involves multiple passes. A machining curve is completed for each pass. A path command is used to describe the path of a tool path curve. Each track command corresponds to an axis linkage table and a follower table. In the DRC NC program, there are generally m track commands, so there are m axis linkage tables and m follower tables.
  • a tool path curve usually consists of several segments of curves, and the geometry of each segment may be different.
  • curved segments with different geometrical structures are considered as different toolpath curves.
  • the difference in geometry means that the axes of the linkage are different.
  • a tool path composed of a plurality of arcs and a plurality of straight lines on the XY plane uses a track command because the coordinate axes of the linkage are the same.
  • the axis linkage table of the m track commands is stored in the axis linkage table file memory of the servo drive device, and the follow-up table of the m track commands is stored in the follower table file memory of the real-time control module. Therefore, it is necessary to establish a connection with the following table for the separated axis linkage table.
  • Each track command carries a sequence code that identifies the position of the track command in the DRC NC program.
  • the axis linkage table includes an axis linkage table of each track instruction as a subfile, and the directory includes a sequence code; the follower table includes a follower table of each track instruction as a subfile, and the directory also includes the sequence code. Therefore, for all the trajectory commands, the sequence code establishes a correspondence relationship between each trajectory command and its axis linkage table and the follower table.
  • the linkage of the relevant coordinate axes is controlled, and only the coordinate axis corresponding to the state word is required to be synchronously transmitted by the servo drive device. pulse.
  • the set of synchronization pulses under the control of the status word is referred to as a linkage command.
  • the digital control information execution process is a process in which the servo drive device follows the linkage command to control the coordinate axis feed to generate a synthetic displacement.
  • the servo drive device After receiving the linkage command, the servo drive device reads the coordinate value increment from the axis linkage table according to the L pointer, writes the position loop, and drives the coordinate axis feed to generate a composite displacement; the L pointer is incremented by 1 until the L pointer is equal to the axis linkage table. Last address.
  • the interface of the numerical control system can be generally divided into an internal interface and an external interface.
  • the external interface refers to the network interface.
  • the network interface is used for exchanging information between different digital control systems in the workshop management network, and generally adopts an industrial Ethernet interface, etc., and is a conventional technology.
  • the internal interface of the digital control system is used to exchange information between the four functional components such as the digital control information generating unit, the digital control information distributing unit, the digital control information transmitting unit, and the digital control information executing unit.
  • the invention divides the internal interface into a real-time interface and a non-real-time interface.
  • the real-time interface includes a linkage interface and an I/O interface.
  • the I/O interface is used to send a switch command to a switch in an I/O device, which is a conventional technique.
  • the present invention refers to a real-time interface as a linkage interface for transmitting a linkage command to a servo drive device.
  • the real-time communication interface is extremely complicated, and there is no reconfigurability. It only consumes a large amount of computing resources and configures different fieldbuses. This situation has led to the establishment of 5.6 models of China National Standard "GB/T 18759.2-2006 ⁇ Mechanical and electrical equipment ⁇ Open CNC system "Part 2 Architecture", requiring support for various fieldbuses (eg CAN, Profibus, Sercos, etc.) . In fact, there are 12 international standards for fieldbus, and there are more enterprise standards for manufacturers. Unfortunately, multiple standards mean no standards.
  • the field bus uses the periodic communication method to synchronously transmit the coordinate value increment generated by the interpolation to the servo drive device in real time.
  • the communication cycle becomes the system parameter, the real-time synchronization mechanism and the data representation compatibility. Become the key to transmission.
  • the axis linkage table is allocated to the servo drive device in a non-real time, and the real-time communication process is degenerated into a servo drive designated to the status word according to the control rhythm.
  • the device sends the linkage command in real time in one direction, the real-time control process is highly simplified, and the linkage interface is highly simplified.
  • the linkage command is only a sync pulse, and the linkage interface is not a communication interface.
  • the linkage interface is not a communication interface.
  • the non-real time interface is used to distribute the axis linkage table to the servo drive in a non-real time in the auxiliary process.
  • the axis linkage table is a standard file, and there is no problem of separately establishing a communication protocol.
  • the non-real-time interface can be any standard serial interface, including fieldbus, RS232 and RS485 interfaces, USB interfaces, mobile storage, wireless interfaces, and the like.
  • the so-called programming interface refers to the program interface between the machining programs when exchanging machining programs between different CNC systems.
  • the G code standard is adopted as the programming interface of the NC machining program.
  • the DRC NC program is characterized by:
  • the G code standard is adopted as the programming interface of the NC machining program.
  • the tape was used as the basic physical medium for input, in order to standardize the characters on the tape, a coding standard for the tape perforation, that is, the G code standard was established.
  • G code programs are object oriented.
  • different interpolation commands are used to describe the different curves in a tool path curve.
  • different interpolation iteration algorithms must be used to implement different interpolation instructions.
  • the real-time processing of the curve is real-time by the interpolation iterative algorithm, which results in the interpolation iterative algorithm becoming an object-oriented closed real-time control algorithm.
  • the path command is oriented to the machining process of the tool path curve.
  • the DRC NC program is oriented to the control process.
  • each axis must have the same logical properties. Once the logical attributes of the coordinate axes are different, for example, the feed equivalent (nano, micron, etc.) is different, the number of bytes of the data is different, etc., the functions and structures of the numerical control system must be changed accordingly, from real-time control process and real-time communication. The two aspects of the process restrict the openness and reconfigurability of the system.
  • the G code standard is the original product of the initial stage of information technology. Due to the limitation of the tape, there is inevitably a defect that the amount of information is too small. Therefore, each manufacturer has extended the basic semantics of the G code, resulting in the dependence of the G code program and the corresponding hardware.
  • the NC machining program is not interchangeable between different CNC systems, resulting in incompatibility between various CNC systems. It hinders the exchange and sharing of control information, does not have the consistency of human-machine interface, and restricts the openness and reconfigurability of digital control system from the aspect of programming interface.
  • the axis linkage table and the follower table carry all the digital control information required for processing the tool path curve, which is manufactured by the digital control information generating component in a non-real time, allowing each coordinate axis to have different logic attributes.
  • the DRC NC program, the axis linkage table, the follower table, etc. are transmitted in the system in the form of standardized files, and are also transferred between different CNC systems in the form of files.
  • These files conform to the file specification and use standard file systems such as FAT16 and FAT32.
  • the standardized file becomes the carrier of digital control information, has nothing to do with the hardware platform, has nothing to do with the software platform such as the operating system, has extensive platform independence, and realizes the openness of digital control information.
  • the standardized file replaces the G code program and becomes an easy-to-standardize programming interface that facilitates the standardization of control information.
  • the execution of the trajectory instruction involves a digital control information transmitting unit and a servo drive unit.
  • the digital control information transmitting component is simply referred to as a real-time control module, including a linkage coordinate axis setting module, a linkage command setting module, a rhythm control module, and an endpoint control module.
  • the real-time control module sends a linkage command.
  • L pointer Used to read the coordinate value component in the axis linkage table.
  • the trajectory instruction execution module sets the operation flag to start the real-time control module.
  • the real-time control module dominates the execution of the trajectory command according to the control rhythm, and the real-time control process of the coordinate axis linkage is transformed into the following process:
  • Step 1 linkage axis setting steps: According to the sequence code of the track instruction, the linkage axis setting module writes the first address of the following table to the T pointer, reads the status word from the following table and writes the status word register, specifying Linked coordinate axes;
  • Step 3 Rhythm control step: ⁇ The timing time in the split timer is up, the rhythm control module starts the pulse generator to output a pulse, and sends a linkage command to the servo drive device specified by the status word register through the linkage interface;
  • Step 4 End point control step: The end point control module controls the end point of the track command. If the ⁇ pointer is equal to the last address of the follow-up table, that is, the end point of the track command is reached, the running flag is turned off; otherwise, the ⁇ pointer points to the next repeat step 2 to step 4;
  • the track instruction execution module queries the running flag of the real-time control module. If the end point of the track command is reached, the next motion instruction is executed.
  • the servo drive After the servo drive receives the axis linkage table, set the execution flag to "1"; according to the sequence code of the axis linkage table of the track command, write the first address of the axis linkage table to the L pointer; according to the feature table in the axis linkage table file, Set the logical properties of the axes.
  • the axis linkage table control module After the servo drive receives the linkage command, following the linkage command, the axis linkage table control module reads the coordinate value increment from its axis linkage table according to the L pointer, writes the position loop, and drives the coordinate axis feed to generate a composite displacement; 1 . Until the L pointer is equal to the last address of the axis linkage table, set the execution flag to "0" to prepare the axis linkage table for the next track command.
  • the real-time control process of the so-called tool path is to control the process in which the servo drive specified by the status word reads the coordinate value increment from the axis linkage table and writes it to the position loop according to the control rhythm.
  • the real-time control module generates a linkage command; following the linkage command, the servo drive continuously drives the coordinate axis feed to produce a composite displacement. This cycle is repeated until the ⁇ pointer reaches the end address of the slave table, that is, the end of the trajectory command is reached.
  • the interpolation cycle of the real-time operating system and the communication cycle of the field bus are two system clocks. Following the cycle of the interpolation cycle and the communication cycle, the digital control information of the toolpath curve is continuously generated, distributed, transmitted, and executed, so that the real-time iteration of the digital control information and the real-time iteration of the control process are repeated.
  • the real-time control process of the toolpath curve includes both real-time iteration of the digital control information and real-time iteration of the control process.
  • Including the real-time communication process including the accuracy and speed of the interpolation iterative algorithm, the geometric characteristics of the tool path curve, the process characteristics of the machining process, the kinematics/dynamics characteristics of the mechanical system, the number of bits and the speed of the processor, and other hardware platforms, A series of complex factors such as real-time operating systems and other software platforms.
  • the technical solution configures control resources according to a control flow of generating, allocating, transmitting, and executing digital control information, wherein the generating process and the assigning process are non-real-time processes, and the sending process and the executing process are real-time processes.
  • the linkage command; the servo drive device follows the linkage command, and the coordinate value increments in the axis linkage table are successively written into the position loop, and the corresponding coordinate axes are driven to generate a combined displacement.
  • the digital control information execution process is decoupled into a linked information execution process and a location information execution process.
  • the technical solution replaces the extremely complicated real-time communication with the simplest one-way transmission of the linkage command, and cancels the control right of the current bus to the real-time control process. Therefore, the above technical solution completely eliminates the contract between the operating system and the current bus to the real-time control process, and points out the direction for the system implementation technology of the reconfigurable digital control system.
  • Figure 1 is a process model diagram based on the control flow, where the solid line represents the real-time process and the dashed line represents the non-real-time process.
  • the execution of the feedback information in the servo drive can be added to Figure 1, as shown in Figure 2.
  • a band plays a symphony
  • a symphony is equivalent to a knife curve
  • various instruments are equivalent to coordinate axes
  • an actor is equivalent to a servo drive
  • a real-time operating system is equivalent to a band conductor.
  • the digital control information generating unit is based on the PC, and includes a state command generating module, a switch command generating module, a track command generating module, and a DRC numerical control program generating module.
  • the digital control information distribution process is to assign the coordinate value increments in the linkage table to the relevant servo drive device, for example, assign XXi, ⁇ , ⁇ , ⁇ to the five coordinate axes of X, y, Z, A, B, etc.
  • Servo drive unit assign XXi, ⁇ , ⁇ , ⁇ to the five coordinate axes of X, y, Z, A, B, etc.
  • the digital control information distribution unit includes an axis linkage table file memory, an axis linkage table allocation module, and a serial interface.
  • the digital control information transmitting means is for transmitting the interlocking command in real time to the servo drive specified by the control word in accordance with the control rhythm.
  • the digital control information transmitting component is referred to as a real-time control module.
  • the follower file is a standard file written by the operating system of the PC following the file system specification such as the FAT16, FAT32 file system specification.
  • the real-time control module further includes a follow-up table file memory, and is configured with a solidified file reading module for reading related sector addresses and data area addresses of the FAT table, the FDT table, the BPB table, and the like. Therefore, it has nothing to do with the PC hardware and software platform.
  • dual-port RAM is usually used as a data exchange interface between CPUs.
  • the dual-port RAM is used for storing the follow-up table file
  • the digital control information execution unit includes a servo drive device and an I/O device.
  • the present embodiment does not relate to a control flow for controlling an I/O device.
  • the digital control information execution process is that the servo drive device writes the coordinate value increment to the position loop and drives the coordinate axis feed.
  • the motion control interface includes a non-real time interface and a linkage interface.
  • the non-real time interface is various standard serial interfaces, such as a field bus, an RS232 interface, an RS485 interface, a USB interface, a mobile memory, a wireless interface, and the like.
  • a servo drive is connected to a data bit of the linkage interface, similar to an interrupt control line.
  • the numerical control application system includes a DRC numerical control program, an interpretation program memory, and a DRC numerical control program operation module.
  • the DRC NC program running module includes a motion instruction fetching module, a state instruction execution module, a switch instruction execution module, and a track instruction execution module.
  • the motion instruction fetch module is used to write the first address of the DRC NC program to the motion instruction pointer and read the motion instruction, write the function byte of the motion instruction into the motion instruction register, and write the address of the next motion instruction to the motion instruction pointer.
  • the motion instruction pointer is used to specify an address of the next motion instruction; if the motion instruction is a state instruction, the state instruction execution module executes an interpretation program of the state instruction; if the motion instruction is a switch instruction, the switch instruction execution module executes the switch An interpreter of the instruction; if the motion instruction is a track instruction, the track instruction execution module executes an interpretation program of the track instruction.
  • FIG. 3 is a schematic diagram of an architecture of a reconfigurable numerical control system
  • FIG. 4 to FIG. 6 are functional block diagrams of various components, including a PC system 1, an interpreter memory 2, a real-time control module 3, and a servo drive device 4, I. /O device 5, serial interface 6, linkage interface 7, I/O interface 8.
  • the PC system 1 is connected to the servo drive unit 4 via the serial interface 6, and is connected to the I/O device 5 via the I/O interface 8.
  • the PC system 1 includes a digital control information generating unit, a digital control information distributing unit, and a numerical control application system, which are connected to a real-time control module through an internal bus such as a PCI, and execute components through a serial interface, an I/O interface, and a digital control information. Connections form a monolithic architecture.
  • the PC system 1 can also be connected to the real-time control module through dual-port RAM, and the two share the follower table.
  • the PC system 1 is used to generate a DRC numerical control program for controlling the workpiece machining process, including a state instruction generation module 11, a switch instruction generation module 12, a trajectory instruction generation module 13, a DRC numerical control program generation module 14, an axis linkage table distribution module 15, and a DRC numerical control system.
  • the program runs module 16.
  • the status command generation module 11 is configured to generate a status instruction that controls the auxiliary process.
  • the switch command generation module 12 is configured to generate a switch command that controls the I/O device.
  • the trajectory command generation module 13 is configured to generate a trajectory command for controlling the servo drive device to complete the path curve pass process.
  • the trajectory instruction generation module includes a discrete geometric planning module and a discrete motion planning module.
  • the discrete geometric planning module is configured to generate a linkage table of L segments storing a tool path curve; the L segmentation is used for The control coordinate axis linkage generates a synthetic displacement; the linkage table is divided into an axis linkage table of each axis; the axis linkage table is used for storing the L segmentation component of the relevant coordinate axis, and controlling the coordinate axis to generate the axis displacement.
  • the discrete motion planning module is configured to store a T-segment of the tool path curve and a follow-up table of the status word; the T-segment is used to control a time interval between the axis displacements; the status word is used to specify a coordinate axis of the linkage .
  • the DRC NC program generation module 14 is used to link the status command, the switch command, and the track command to the DRC NC program according to the machining process.
  • the axis linkage table assignment module 15 is for distributing the axis linkage table to the servo drive unit 4 via the serial interface 6.
  • the DRC NC program running module 16 is used to run the DRC numerical control program, execute the status command control auxiliary process, execute the switch command, control the I/O device through the I/O interface 8, and execute the track command to start the real-time control module 3 to control the servo through the linkage interface 7.
  • the drive unit 4 completes the machining process of the tool path curve.
  • the motion instruction fetch module 161, the state instruction execution module 162, the switch instruction execution module 163, and the track instruction execution module 164 are included.
  • the motion instruction fetch module 161 is configured to write the address of the DRC NC program to the motion instruction pointer and read the motion instruction, write the function byte of the motion instruction into the motion instruction register, and write the address of the next motion instruction to the motion instruction pointer.
  • the motion instruction pointer is used to specify the address of the next motion instruction. If the motion instruction is a status instruction, the status instruction execution module 162 is configured to execute an interpretation program of the status instruction; if the motion instruction is a switch instruction, the switch instruction execution module 163 is configured to execute the switch instruction An interpreter; if the motion instruction is a trajectory instruction, the trajectory instruction execution module 164 is configured to execute an interpreter of the trajectory instruction.
  • the interpreter memory 2 is used to store the above-mentioned state command, switch command, and trace command interpretation program.
  • the linkage command is used to control synchronization between the coordinate axes specified by the status word;
  • the servo drive unit 4 is provided with an axis linkage table initialization module 41 and an axis linkage table control module 42.
  • the axis linkage table initialization module 41 is configured to set an execution flag, and write the first address of the axis linkage table to the L pointer according to the sequence code of the track instruction; set the coordinate axis according to the feature table in the axis linkage table file Logical attributes.
  • the axis linkage table control module 42 reads the coordinate value increment of the axis from the axis linkage table according to the L pointer and writes the position loop, and drives the coordinate axis feed to generate a composite displacement until the L pointer is equal to the axis linkage.
  • the execution flag is turned off.
  • the axis linkage table file further includes a feature table; the feature table is used to identify a logical attribute of the coordinate axis; and the logic attribute includes a feed equivalent, a number of bytes of data, and an electronic gear ratio.
  • the interpolation iterative algorithm requires that the linked axes must have the same logical attributes.
  • the serial interface 6 is only used for transmitting the axis linkage table of the servo drive device 4 in the non-real-time process, and thus, the specific structure thereof is not limited, the field bus, the RS232 interface, the RS485 interface, the USB interface or the wireless Interfaces, etc. can be used. This means that it is not necessary to set standards for the serial interface 6, in other words, the serial interface 6 has been standardized.
  • the system implementation technical solution of the reconfigurable computer digital control system has the following technical features:
  • control flow is divided into four sub-processes: digital control information generation process, digital control information distribution process, digital control information transmission process and digital control information execution process, and corresponding control resources are configured;
  • the digital control information generation process and the digital control information distribution process are not real-time;
  • the DRC NC program written by the status command, switch command, and track command is used as the programming interface; the track command has only one format, regardless of the curve type in the tool path curve.
  • the trajectory command is separated from the linkage table and the follower table; the axis linkage table of each coordinate axis in the linkage table is used as a separate subfile, and is allocated to the servo drive device through the non-real time serial interface in the auxiliary process and stored in its axis linkage In the table memory; the follower table sets the status word, which is used to specify the coordinate axis of the linkage, the number of bytes of the status word is the user parameter; the axis linkage table file sets the feature table, which is used to set the logical attribute of the coordinate axis, thereby the coordinate axis The processing problem of the logical attribute is moved forward to the servo drive device;
  • the file conforms to the file specification and uses standard file systems such as FAT16, FAT32.
  • Standardized files become the carrier of digital control information, independent of the hardware platform, and independent of software platforms such as operating systems.
  • the PC system includes a digital control information generating component, a digital control information distributing component, and a numerical control application system; the real-time control module acts as an external device such as a hard disk, through an internal bus such as PCI or through dual-port RAM sharing.
  • the form of the follower table is connected to the PC system.
  • the PC system transfers control of the real-time control process of the toolpath curve to the real-time control module.
  • the coordinate value increments are successively written into the position loop, and the corresponding coordinate axes are driven to generate a combined displacement.
  • the above technical features of the technical solution simplifies the real-time control method of the tool path curve to the greatest extent, and leads to a major change in the architecture and real-time control method of the reconfigurable computer digital control system, and solves the problem with extremely simple technical means. Reconstruct the reconstruction problem of computer numerical control system.
  • the digital control method based on the above reconfigurable computer digital control system includes the following steps: Step 1. DRC NC program generation step: For the PC system 1 to generate the DRC NC program, the following steps are included:
  • Step 101 Trajectory instruction generation step: The trajectory instruction generation module generates a trajectory instruction for controlling the servo drive device to complete the path curve path, including discrete geometric planning steps and discrete motion planning steps; discrete geometric planning steps are used for discrete geometric planning module generation
  • the linkage table of the L segmentation of the tool path curve is stored; the L segmentation is used to control the coordinate axis linkage to generate a composite displacement; the linkage table is divided into an axis linkage table of each axis, and is used for storing the L segmentation component of each coordinate axis, Controlling the coordinate axis to generate an axis displacement;
  • the discrete motion planning step is used by the discrete motion planning module to generate a follower table of the T segmentation and the status word storing the tool path curve; the T segmentation is used to control the time between the axis displacements Interval;
  • the status word is used to specify the coordinate axis of the linkage.
  • Step 102 State instruction generation step: The state instruction generation module generates a state instruction for controlling the auxiliary process.
  • Step 103 The switch command generating step: The switch command generating module generates a switch command for controlling the I/O device.
  • Step 104 The DRC numerical control program generating step: the DRC numerical control program generating module links the state command, the switch command, and the track command to a DRC numerical control program according to a machining process.
  • Step 2 Axis linkage table assignment step: The axis linkage table assignment module 15 distributes the axis linkage table to the servo drive unit 4 via the serial interface 6.
  • Step 3 DRC NC program running steps: DRC NC program running module 16 Run the DRC NC program, including the following steps:
  • the motion instruction fetching step the motion instruction fetch module 161 writes the first address of the DRC NC program to the motion instruction pointer and reads the motion instruction, and writes the function byte of the motion instruction into the motion instruction register, and sets the address of the next motion instruction.
  • State instruction execution step If the motion instruction in the motion instruction fetch step is a status instruction, the status instruction execution module 162 executes an interpretation program of the status instruction;
  • the switch instruction execution step if the motion instruction in the motion instruction fetch step is a switch instruction, the switch instruction execution module 163 executes an interpretation program of the switch instruction;
  • the trajectory instruction execution step if the motion instruction in the motion instruction fetching step is a trajectory instruction, the trajectory instruction execution module 163 executes the interpretation program of the trajectory instruction.
  • the PC system 1 first assigns an axis linkage table to the servo drive unit 4 via the serial interface 6, and then runs the DRC NC program.
  • the trajectory command execution module 164 starts the real-time control module 3, and transfers the control right of the real-time control process of the tool path curve to the real-time control module 3.
  • the real-time control module 3 sends a linkage command to the servo drive device 4 through the linkage interface 7 according to the control rhythm At i : ..., ⁇ ) in the follow-up table; each servo drive device 4 follows the linkage command, and each The increment of the coordinate values in the self-axis linkage table is successively written into the position loop, driving the respective coordinate axes to feed, and the resultant displacement is generated. Repeatedly, until the T pointer is equal to the last address of the slave table, that is, the end of the track command is reached, the running flag is turned off, and the DRC NC program running module executes the next motion command.
  • trajectory instruction execution module 164 hands over the control to the real-time control module 3, it is in the query state, and queries the running state of the real-time control module 3. If the run flag is off, the next motion command is executed until the stop command is executed, ending the machining of the workpiece.
  • the real-time control process of the tool path includes the following steps:
  • Step a linkage axis setting step: According to the sequence code of the track instruction, the linkage axis setting module 31 writes the first address of the following table to the T pointer, reads the status word from the following table, and writes the status word. Register, specifying the coordinate axis of the linkage;
  • Step c rhythm control step: The timing time in the T split timer is up, the rhythm control module 33 starts the pulse generator to output a pulse, and sends a linkage command to the servo drive device 4 specified by the status word register through the linkage interface 7;
  • Step d linkage table control step: following the linkage command, the axis linkage table control module 41 of the servo drive device 4 reads the coordinate value increment from the axis linkage table according to the L pointer, writes the position loop, and drives the coordinate axis into Give a synthetic displacement;
  • Step e End point control step: The end point control module 34 controls the end point of the track command. If the T pointer is equal to the last address of the follower table, that is, the end point of the track command is reached, the running flag is turned off; otherwise, the T pointer points to the next repeating step. b to step e. For the reconstruction of mechanical systems, motion planning must first be performed on the mechanical system.
  • the motion planning of the mechanical system is regarded as a conventional CAE technique.
  • the reconstruction of the reconfigurable computer digital control system in this embodiment involves the following problems.
  • CAE performs motion planning and structural optimization on the mechanical system to obtain the motion relationship of the mechanical system.
  • the discrete coordinate system For the reconstructed mechanical system, the discrete coordinate system must be reconstructed.
  • the mechanical properties change.
  • the mechanical properties include line displacement error of the coordinate axis, angular displacement error, Fine structure constants such as backlash, and coordinate system parameters such as non-parallelism and non-perpendicularity between coordinate axes.
  • the status command relates to the auxiliary function operation
  • the switch command relates to the switch quantity control in the I/O device, both of which are inseparable from the specific structure of the mechanical system, and are personalized functions. After the mechanical system is reconfigured, state commands and switching instructions often need to be reconstructed.
  • the definition of the state instruction and the switching instruction and the interpretation operation thereof are all based on the PC, and are open.
  • the user can define the parameter values in their auxiliary bytes and implement their own defined functions by rewriting the interpreter.
  • the definition of the state instruction and the switch instruction in the PC, and the preparation of the interpretation operation program are performed at the user level, and are independent of the hardware platform and software platform of the PC, and are reconfigurable.
  • the core issue of digital control systems is the real-time control of the toolpath curve.
  • the real-time control process of the tool path curve necessarily needs to be reconstructed.
  • the reconstruction of the real-time control process involves the reconstruction of the trajectory instructions and the reconstruction of the linkage interface.
  • the real-time control process is both an iterative process of digital control information and an iterative process of real-time control process. Therefore, the real-time control process is inseparable from the geometric characteristics of the tool path curve, the process characteristics of the machining process, and the kinematics/dynamics characteristics of the mechanical system. It is inseparable from the hardware platform such as the number of bits of the CPU and the operation speed. Software platforms are inseparable, and are inseparable from the interpolation iteration algorithm.
  • the real-time control process of the tool path curve cannot be opened and is not reconfigurable. For different curve types, dedicated interpolation instructions must be defined and specific interpolation modules configured. Therefore, the interpolation instructions under the G code standard are not reconfigurable.
  • the trajectory command in this technical solution has only one format, which is only related to the number of linked coordinate axes, and has nothing to do with the curve type in the tool path curve. There is no refactoring problem.
  • the prior art regards 5-axis linkage as the most advanced technology.
  • the coordinate axes of the linkage are specified by the status word in the follow-up table, and the number of bits and the number of bytes of the status word are user parameters.
  • An 8-bit status word controls 8 coordinate axes, and a 16-bit status word controls 16 axis linkages. Therefore, for the vast majority of users, there is no refactoring problem. If the number of axes of the mechanical system exceeds the number of bits of a status word, in this technical solution, the user parameter of the status word only needs to be set to 2 or more bytes, and two or more linkage interfaces are configured. Therefore, there is no need to refactor.
  • the format of the trajectory instructions proposed by this technical scheme is applicable to any mechanical system and has wide versatility.
  • the technical solution simplifies the real-time control process of the tool path curve to start the real-time control module.
  • the linkage interface of the technical solution is not a real-time communication interface, and the linkage command is only a synchronization pulse.
  • the linkage interface is similar to an interrupt control line. Therefore, the linkage interface proposed by the technical solution does not have a reconstruction problem.
  • the non-real-time interface is a standard serial interface, such as a standard USB interface or other standard serial interface supported by the UART, which is a conventional technique.
  • the non-real time interface does not need to be reconstructed.
  • the technical solution converts the reconstruction method of the reconfigurable computer digital control system into a conventional technical means in the PC, has excellent reconfigurability, and completely solves the reconstruction problem of the reconfigurable computer digital control system.
  • the method for reconstructing the reconfigurable computer digital control system of the technical solution includes the following steps:
  • Step 1 Reconstruct the discrete coordinate system:
  • the PC system reconstructs the discrete coordinate system;
  • the discrete coordinate system includes an orthogonal discrete coordinate system and a non-orthogonal discrete coordinate system.
  • Step 2 reconstructing a structure constant database: a PC system reconstructing a structure constant database; the structure constant database stores a fine structure constant of the coordinate axis and a coordinate system parameter; the fine structure constant of the coordinate axis includes a line displacement error and an angular displacement error Backlash; the coordinate system parameters include non-parallelism and non-perpendicularity between the coordinate axes.
  • Step 3 Reconstruct the state instruction: the PC system reconstructs the state instruction;
  • Step 4 Reconstruct the switch command: The PC system reconstructs the switch command.
  • the connection mode between the PC system and the real-time control module can be other than the specific manners used in this embodiment. It is to be understood by those skilled in the art that the present invention may be made in the form of the present invention without departing from the spirit and scope of the invention.

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Abstract

公开了一种基于PC(1)的、全方位开放的、标准化的可重构计算机数字控制系统及其数字控制方法与重构方法。本发明提出了一种面向过程的、开放的加工过程模型。该方法按照数字控制信息的生成、分配、发送、执行的控制流程配置控制资源,与处理器的位数与速度、操作系统等软硬件平台无关,与编程口无关,其具有优良的可重构性。本发明将刀路曲线的实时控制转化为最简单的联动命令的实时发送,具有简单可靠的高速高精度多轴同步能力,导致数字控制方法的重大变革。

Description

可重构计算机数字控制系统与数字控制方法、 重构方法
技术领域 本发明属先进控制与先进制造领域, 具体涉及一种基于 PC的、 全方位开放 的、 标准化的可重构计算机数字控制系统及其数字控制方法与重构方法, 以适 应可重构制造系统对数字控制系统的要求。 技术背景 可重构制造系统是先进制造的研究前沿,是未来制造系统的发展方向。 1998 年, 美国国家研究委员会发表了 "2020年制造业面临的挑战" 的研究报告, 将 可重构制造系统列为 10大关键技术的第一位。 对可重构制造系统具有决定性意 义的是可重构机床 RMT (Reconfigurable Machine Tools)。 十余年来, 数字信息技 术突飞猛进, 可重构机床毫无进展, 其原因在于可重构机床必须建立在可重构 计算机数字控制系统的基础上。 没有可重构计算机数字控制系统, 可重构机床 则成无米之炊。
数字控制系统的可重构性成为可重构制造系统中亟待解决的关键技术。
可重构计算机数字控制系统应该是一种开放式数字控制系统, 这是本领域 的共识。
自从 1952年美国 MIT研制出第一台电子管数控系统以来,历经晶体管、 集 成电路、 小型计算机、 微型计算机之后, 数控系统于上世纪八十年代发展为基 于 PC的开放式数控系统,产生了现有开放式数控系统的三种模式: PC嵌入 NC 模式、 NC嵌入 PC模式、 软开放式模式。
NC嵌入 PC模式的所谓基于运动控制器的开放式数控系统成为现有开放式 数控系统的主流, 运动控制器成为一个高新技术产业并风靡全球。 开放式运动 控制器在美国被誉为新一代的工业控制器, 在日本被认为是将来的第三次工业 革命。
IEEE( Institute of Electrical and Electronics Engineers ,电气电子工程师十办会 ) 关于开放式数控系统的定义为:
"符合系统规范的应用系统可以运行在多个销售商的不同平台上, 可以与其 它系统的应用进行互操作, 并且具有一致风格的用户交互界面。 "
中国国家标准《GB/T 18759. 1-2002·机械电气设备 ·开放式数控系统《第 1部 分 总则》抓住 IEEE定义的本质并遵循 IEEE定义的基本原则, 在 3.1款中直截 了当将开放性定义为应用软件的"即插即用", 将开放式数控系统定义为:
"指应用软件构筑于遵循公开性、 可扩展性、 兼容性原则的系统平台之上的 数控系统, 使应用软件具备可移植性、 互操作性和人机界面的一致性。 " 开放式体系结构是实现高性能、 智能化数字控制的关键技术。 然而, 近三 十年来, 在 IEEE定义的误导下, 正如文献《高性能运动控制在数控系统中的应 用综述》(载 《信息与控制》, 2003年第 3期, 中国自动化学会和中国科学院沈 阳自动化研究所联合主办, 作者: 王军平, 王安, 敬忠良, 陈全世)所指出的, "开放式体系结构还没有统一、 明确的概念内涵, 系统实现技术还处于百家争 鸣时代", "开放式体系结构的研究还处于初期阶段"。
从信息论的角度来看, 数控系统只是将压缩在刀路曲线与进给速度中的数 字控制信息解压。 在基于 IEEE定义的现有开放式数控系统中, 插补迭代控制方 法就是数字控制信息的一种解压方法。
插补迭代控制方法的基本技术方案是, 对于给定的刀路(Tool Path )曲线与 刀具的进给速度, 在实时操作系统的控制下, 以插补周期为分时周期, 采用插 补迭代算法实时计算相关坐标轴的数字控制信息, 并实时分配发送给伺服驱动 装置执行, 以控制机械系统之间的确定性运动关系。 在每个插补周期中, 由插 补所生成的数字控制信息, 一方面立即实时分配发送给伺服驱动装置执行, 另 一方面又作为下一个插补周期的输入进行迭代以生成下一个数字控制信息, 从 而构成数字控制信息的实时迭代。 跟随插补周期的节拍, 数字控制信息不断地 生成、 分配、 发送、 执行, 从而又以过程迭代的方式周而复始, 构成控制过程 的实时迭代。
发明人发现,基于 IEEE定义的现有开放式数控系统没有可重构性的基本原 因有四点:
第一、 平台相关性
所谓平台无关性一般指的是应用软件可以在多个不同品种的 CPU上运行以 及多个操作系统上运行。 前者为硬件平台无关性, 后者为软件平台无关性。
中国国家标准《GB/T 18759. 1-2002·机械电气设备 ·开放式数控系统《第 1部 分 总则》将开放式数控系统的基本体系结构分为应用软件和系统平台, 系统平 台由硬件平台与软件平台组成。 所谓硬件平台, 是软件平台和应用软件运行的 基础部件, 处于基本体系结构的最底层; 所谓软件平台, 是应用软件运行的基 础部件,处于基本体系结构的硬件平台和应用软件之间。所谓 NC核心软件则是 应用软件中的基础软件, 也就是涉及运动控制、 轴控制和运动控制管理的应用 软件模块。 为叙述的简便, 将 NC核心软件简称为数控应用软件。
软件平台一般包括操作系统、 图形系统及应用编程接口 APT, 其中核心是 实时操作系统。
从计算机与计算机应用的发展历史来看, 采用分时运行多个用户程序的多 任务操作系统是一个划时代的进展。 然而, 在本质上, 多任务操作系统只是为 适应内部与外部资源的管理以及内部与外部的环境变化而构建的一种内外资源 的管理机制以及响应内外环境变化的应变机制。
在基于 IEEE定义的现有开放式数控系统中,插补迭代控制方法将实时操作 系统的管理机制与应变机制转变为一种普适的控制机制, 实时操作系统便成为 进行实时插补迭代以生成数字控制信息的实时控制中心, 现有数控系统形成了 以实时操作系统为中心的系统架构。 插补迭代控制算法的运算规则与实时操作 系统的任务调度规则紧密耦合在一起构成一种实时的数字控制方法, 即插补迭 代控制方法。 插补迭代控制方法贯穿于数字控制技术与数控系统的全部历史, 创建了数控系统的"插补时代"。。
在基于 IEEE定义的现有开放式数控系统中,插补迭代控制算法作为数字控 制信息的一种解压方法, 必须在实时操作系统的控制下实时地进行插补计算。 实时操作系统具有高精度计时功能、 多级中断嵌套处理机制与实时调度机制, 其核心是进程调度与线程调度。 实时性将进程调度与线程调度复杂化。 并行算 法又将进程调度与线程调度进一步复杂化。 与机器指令级流水线的并发性和处 理器级进程的并发性相比, 线程的并发性所面临的不确定性极为复杂。
进程与线程, 再加上并行算法, 导致实时操作系统的高度复杂化以及数控 应用软件的高度复杂化。 对于高速高精度的多轴系统, 数控应用软件势必成为 采用并行算法、 涉及多进程 /多线程嵌套调用以及多重实时嵌套中断的一个庞大 而复杂的中断系统。
问题在于, 一旦运动速度提高、 或运动精度提高、 或联动轴增加、 或联动 参数增加, 实时操作系统的插补周期必然以指数形式增长, 从而需要更多位数 更高速度的 CPU、 更多位数更强实时性的实时操作系统、 更优化的实时调度能 力、 以及更先进的插补迭代控制算法。
问题还在于, 为了研发那个庞大而复杂的中断系统, 既要精通数字控制技 术, 又要精通计算机软硬体系结构, 还要精通并行算法与多线程编程。 这就意 味着, 数控应用软件成为所谓的专家型系统, 即只有精通上述技术的复合型专 家才能研发的系统, 用户无法进行二次开发, 从而完全丧失了开放性。
因此, 基于 IEEE定义的开放式现有数控系统完全"被计算机化", 在体系结 构上, 实质上成为需要配置实时操作系统的通用计算机系统, 数控应用软件只 是其中的一个专用应用系统, 其开放性只能定义为数控应用软件的"即插即用"。
由此可见, 在本质上, 基于 IEEE定义的现有开放式数控系统并不具有平台 无关性, 而是相反, 具有平台相关性, 对于高速高精度的多轴系统来说, 更是 平台强相关性。
基于 IEEE定义的现有开放式数控系统既然具有平台强相关性,在本质上便 失去了重构的基石出。 第二、 实时控制过程不具有可重构性
在基于 IEEE定义的现有开放式数控系统中, 实时控制过程既是数字控制信 息的迭代过程又是实时控制过程的迭代过程, 与插补迭代控制算法密不可分, 高速高精度的插补迭代算法自然成为现有数控技术中的核心技术。 故而, 曰本 的 OSEC计划( Open System Environment for Controller )认为 , 没有先进的控制 算法的开放式数控系统只是进化性的、 不是理想的和革命性的。
在体系结构上,基于 IEEE定义的现有开放式数控系统被划分为系统平台和 应用软件两大部分, 应用软件进而划分为人机控制层和运动控制层。 运动控制 层是数控系统完成实时控制过程的内核, 由一些标准组件构成。 显然, 这是一 种面向应用软件配置的体系结构。 这就意味着, 基于 IEEE定义的现有开放式数 控系统是面向对象而不是面向过程的。
数字控制系统的核心问题是实时控制刀路曲线。 相应于机械系统的重构, 刀路曲线的实时控制过程必然需要重构。
在基于 IEEE定义的现有开放式数控系统中, 对于不同的刀路曲线, 例如, 直线、 圓弧、 抛物线、 渐开线、 NURBS曲线等, 必须研发相应的插补迭代算法 并在数控应用软件中配置相应的实时控制模块。 因此, 相应于机械系统的重构, 实时控制过程的重构必然涉及实时控制模块的修改, 或替换、 增加实时控制模 块。 舍此之外, 再无其他技术手段。
显然, 这与数字控制系统可重构性的内涵相距甚远。
发明人发现, 对于数字控制来说, 过程比对象更具本质特征。 数字控制系 统中的数字控制是一个过程, 而不是对象。 然而, 基于 IEEE定义的现有开放式 数控系统是面向对象而不是面向过程的。
在插补迭代控制方法中, 实时控制过程就是插补周期控制下的坐标值增量 的生成过程、 分配过程、 发送过程、 执行过程的周而复始。 因而, 实时控制过 程与刀路曲线的几何特征、 加工过程的工艺特征、 机械系统的运动学 /动力学特 征等密不可分, 与 CPU的位数、 运算速度等硬件平台密不可分, 与实时操作系 统等软件平台密不可分, 与插补迭代算法密不可分。 这就从根本上限制了实时 控制过程的重构。 换言之, 在基于 IEEE定义的现有开放式数控系统中, 刀路曲 线的实时控制过程无法开放, 不具有可重构性。
第三、 通信周期为系统参数
网络化是先进制造技术的重要技术特征。
中国国家标准 "GB/T 18759.1-2002·机械电气设备 ·开放式数控系统*第 1 部 分: 总则 · 5. 2. 4. 2"规定, 外部通信应符合有关的国家标准或国际标准, 内部 通信应符合 ISO标准通信模型。 外部通信用于数控系统与车间管理网之间, 其按口可称为网络接口, 例如 工业以太网接口或其他现场总线( Field bus )。
继而, 对于内部通信接口, 中国国家标准《GB/T 18759. 3-2009. 机械电气 设备. 开放式数控系统. 第 3部分 总线接口与通信协议》 以 ISO/OSI开放系统 互联参考模型为基石出, 规范了一种现场总线, 称之为 "开放式数控系统总线", 用于连接 "数控装置、 伺服驱动装置、 主轴驱动装置、 传感器装置、 I/O装置", 以实现这些 "装置间的数字式、 双向、 多点的通信", 并满足系统对周期性、 实 时性、 同步、 可靠性、 安全性、 开放性等方面的要求。 另一种数控系统现场总 线标准 《机床数控系统 NCUC-Bus现场总线协议规范 (草案)》 的草案已公开、 也以 ISO/OSI开放系统互联参考模型为基础。
众所周知, ISO/OSI开放系统互联参考模型是针对计算机网络之间的通信模 型。 所述现场总线标准对总线体系结构进行了简化, 主要由物理层、 数据链路 层与应用层构成。 所述现场总线导致通信周期成为另一个系统参数, 通信协议 的实时性、 数据表示的兼容性等一系列问题导致内部通信高度复杂化与高成本。
相应于机械系统的重构, 实时控制过程中的数字控制信息的数据格式, 包 括进给当量(纳米或微米)、 数据的字节数等都将发生变化。 在所述现场总线中 必须制定用户层通信协议, 对开放式数控系统内部的数据交换中的数据格式、 时序关系和纠错方式予以规范。 因而, 与实时操作系统中的插补周期类似, 现 场总线中的通信周期反而成为制约数字控制系统可重构性的因素。
对于可重构计算机数字控制系统来说, 为此必须耗费大量计算资源配用于 支持各类现场总线(例如 CAN、 Profibus, Sercos等)。
第四、 编程接口与人机界面的一致性
在基于 IEEE定义的开放式现有数控系统中,采用 G代码标准作为数控加工 程序的编程接口。 上世纪 50年代纸带作为输入的基本物理介质时, 为规范在纸 带上表示字符, 制定了纸带穿孔的编码标准, 即 G代码标准。
G代码标准是信息技术起步阶段的原始产物, 受纸带的限制不可避免地存 在信息量过少的缺陷。 各个厂商因而对 G代码都进行了基本语义之外的扩张, 导致 G代码程序与相应硬件的依赖, 数控加工程序在不同的数控系统之间不具 有互换性, 造成各种数控系统互不兼容。 因而, 作为编程接口, G代码标准不 具备人机界面的一致性, 成为数控技术进一步发展的瓶颈之一, 也制约了数字 控制系统的开放性与可重构性。
上述四个方面的问题导致基于 IEEE定义的现有开放式数控系统只有三种技 术方案来解决数字控制系统的开放性。
其一是研发更多位数、 更高速度的 CPU与更多位数、 实时性更强的实时操 作系统。 例如, 2009年, 中国国家 "高档数控机床与基石出制造装备" 科技重大 专项计划将 64位 CPU、 64位实时操作系统、以及插补周期达到 0.125ms的多轴 联动数控系统列为关键技术。
其二是研发更先进的插补迭代控制算法。 例如, 日本在 OSEC计划推动下, 研发出用于运动控制器的 64位超高速芯片与 NURBS插补迭代控制算法。
其三是研发基于超高速处理器与实时操作系统的全软开放式数控系统。 所 谓全软开放式数控系统, 形象地说, 就是在实时操作系统支持下将数字控制系 统完全 PC化。
显然, 上述三种技术方案都依赖实时操作系统, 刀路曲线的实时控制过程 无法开放。 一个严峻的事实是, 在基于 IEEE定义的现有开放式数控系统中, 相 应于机械系统的重构, 特别是相应于高速高精度多轴系统的重构, 无论是 NC 嵌入 PC模式还是软开放式模式, 都不能解决上述四个方面的问题, 特别是, 都 不能解决实时控制过程的可重构性, 只能重新研发那个庞大而复杂的中断系统。
因此, 中国国家标准 "GB/T 18759. 1-2002·机械电气设备 ·开放式数控系统* 第 1 部分 总则"未对数控系统的可重构性进行技术界定, 也未对可重构数控系 统作任何说明, 仅在 4. 5. 2款中将可重构性列为开放式数控系统中有待实现的 最高层次而已。 换言之, 对基于 IEEE定义的现有开放式数控系统来说, 可重构 性只是一个美妙的设想。
发明人发现, IEEE关于开放式数控系统的定义是阻碍可重构计算机数字控 制系统发展的根本原因,其首要因素是 IEEE定义所产生的控制观念。在观念上, 必须对现有数字控制技术进行变革, 树立以工作机为中心的控制观念。 数控系 统是为工作机服务的, 其任务只是为工作机制造数字控制信息即多维关联数据 流, 所述多维关联数据流不能夹带工作机不需要的插补周期、 通信周期、 轮廓 步长等冗余信息。
对于数字控制来说, 过程比对象更具本质特征。 数控系统中的数字控制是 一个过程, 而不是对象。 IEEE定义下的现有数控系统的体系结构, 与历史上天 文学中地心说的托勒密体系结构类似, 均缘于观念的错误。
发明人进而发现, IEEE定义存在三个原则性错误。
IEEE定义的第一个原则性错误是,在控制观念上, IEEE定义将数控系统定 位为控制工作机的实时指挥中心, 没有关联数据流的概念。
IEEE定义的第二个原则性错误是,在体系结构上, IEEE定义忽视了数字控 制的过程本质, 面向对象而不是面向过程, 没有控制流程的概念, 将数控系统 定义为一种需要配置实时操作系统的通用计算机系统。
IEEE定义的第三个原则性错误是,在控制方法上, IEEE定义忽视了插补迭 代控制算法只是数字控制信息的一种解压方法, 从而将实时操作系统的内外资 源的管理机制以及响应内外环境变化的应变机制视为一种普适的控制机制, 将 插补迭代控制算法的运算规则与实时操作系统的任务调度规则紧密耦合在一起 构成一种实时控制方法。
因此, IEEE定义必然产生下述问题:
1)、 一切事物都处于过程之中, 都要遍历产生、 发展、 消亡等阶段并演化出 层次结构。 在过程的不同层次中事物演化出的结构便成为对象。 一切对象都在 过程中实现其功能。
对象只是关于事物在特定层次结构的一种人为抽象, 过程则是事物在不同 层次结构中实际运动的动态行为。 IEEE定义完全忽视了数字控制的过程本质, 将数字控制过程视为对象, 导致数字控制信息的迭代与控制流程的迭代, 不可 能涉及数字控制信息的开放性、 数字控制过程的开放性与数字控制过程之间的 界面的开放性。
2 )、 IEEE定义以数控系统为中心, 所定义的开放性是计算机系统本身应具 有的开放性, 所谓开放式数控系统的体系结构是从计算机系统移植过来的, 是 一种面向对象以便实现控制软件模块化的体系结构, 不能反映数控系统在整个 控制过程中的技术特征。
3 )、 IEEE定义未能从制造系统的宏观视野来审视开放式数控系统的体系结 构, 采用通用计算机系统的体系结构, 导致开放式的概念含糊不清, 至今也未 能统一。 互操作性、 可移植性、 可伸缩性、 可互换性等描述性词汇便成为开放 式的所谓技术规范, 阻碍了数控系统的标准化进程。
4 )、 IEEE定义面向对象而不是面向过程, 忽视了计算机数字控制的本质, 数控系统 "被计算机化", 数字控制技术的发展被引向所谓 "先进的控制算法"
(曰本 OSEC计划), 即插补迭代控制算法的精度与速度, 从而误导了数字控制 技术的发展方向。
5 )、 数控系统的核心问题是实时控制过程的开放性与可重构性。 在 IEEE定 义的开放式数控系统中, 实时控制模块因面向对象而无法开放, 从根本上制约 了数控系统的发展。
6 )、 IEEE定义基于通用计算机系统的体系结构, 局限于数控软件的功能划 分及其相互之间的操作界面, 对于数字控制的过程特征缺乏系统学范畴的界定, 因而, 数控系统被定义为配置了数控软件的通用计算机系统, 从而在实质上将 开放式数控系统定义为制造数字控制信息的刚性集成制造系统。
7 )、 IEEE定义不是以工作机为中心, 而是以数控系统为中心, 从而产生了 插补周期、 轮廓步长等大量冗余信息, 违反了简单性原则。 这些冗余信息消耗 了大量计算资源, 违反了经济性原则。 8 )、 过程的开放性与对象的开放性是完全不同的。 过程的开放性必然涉及 数字控制信息的生成、 分配、 发送、 执行的控制流程。 IEEE定义完全没有控制 流程的观念。
IEEE定义的开放式数控系统的体系结构不是按照制造数字控制信息的控制 流程来配置控制资源的体系结构。
9 )、 IEEE定义没有将数字控制信息看作是一种产品, 未涉及数字控制信息 的开放性。
10 ) , G代码标准是现有数控程序采用的编程接口。 G代码编程接口不具备 人机界面的一致性。 IEEE定义关于人机界面的表述过于抽象, 所谓 "人机界面 的一致性" 回避了编程接口的开放性。
因此, IEEE定义不是一个关于计算机数字控制系统的开放性定义, 只是试 图规范应用软件的"即插即用"问题,并未解决数控系统的开放性,反而在体系结 构上将数控系统强制为通用计算机系统架构下的专用计算机系统, 从而将数控 系统的发展牢牢地钉死于"插补时代"。
综上所述, 在 IEEE定义的错误观念主导下的现有开放式数控系统中, 数控 系统所制造的数字控制信息、 制造数字控制信息的方法、 以及制造数字控制信 息的过程与过程界面, 都是封闭的、 非标准的、 不可重构的。 所制造的数字控 制信息成为现有数控系统的内部物品。 这就从根本上否定了数控系统的开放性 与可重构性, 人为地将现有数字控制技术与现有开放式数控系统高度复杂化, 为数控系统的重构设置了难以逾越的障碍, 必然导致现有开放式数控系统无法 演化为第三次工业革命所期盼的控制机。
发明人舍弃 IEEE关于开放式数控系统的定义, 将开放式数控系统定义为:
"所谓开放式数控系统是按照控制流程配置嵌入式子系统的计算机数字控 制系统, 具有开放的人机界面、 开放的数字控制信息、 开放的数字控制信息制 造方法、 开放的数字控制信息制造过程、 数字控制信息制造过程之间的开放的 界面、 开放的应用软件。 "
这一定义同样适用于所述嵌入式子系统, 因而是一个系统学与分形几何学 相结合的定义。 在所定义的开放式数控系统中不存在数字控制信息的迭代与控 制流程的迭代, 控制信息流的拓朴结构是一种线性拓朴结构。 应用软件的开放 性就是"即插即用"。
IEEE定义的开放性只涉及应用软件的开放性以及操作使用计算机时的人机 界面的开放性。
发明人的这一定义表明, 开放式数控系统的开放性具有下述五个方面的内 涵: 1 )、 人机界面的开放性, 包括数字控制信息制造过程的所有控制过程界面 中的人机界面, 特别是编程接口的开放性;
2 )、 数字控制信息的开放性;
3 )、 数字控制信息的制造方法的开放性;
4 )、 数字控制信息的制造过程的开放性;
5 )、 数字控制信息制造过程之间的界面的开放性。
所谓数字控制信息的开放性指的是数字控制信息生成部件中生成的数字控 制信息的公开性与透明性。
所谓数字控制信息制造方法的开放性指的是允许用户 (或开发商)构造或 集成自己的数字控制信息的制造方法, 也就是实时控制方法完全软件化与应用 软件的"即插即用"。
所谓数字控制信息制造过程的开放性指的是数字控制信息的每个子过程的 公开性与透明性。
数控系统的内部接口用于系统内部功能部件之间交换信息。
所谓数字控制信息制造过程之间的界面的开放性指的是内部接口的开放 性。
所谓人机界面的开放性指的是编程接口的开放性。
由此可见, 发明人的上述开放式数控系统的定义反映了现代制造业的发展 环境对控制机所提出的标准化问题, 以适应工作机、 动力机等产业的标准化进 程。
发明人在发明专利《计算机数字控制系统数据流关联控制方法与体系结构》 (中国专利号: ZL200710124304.9, 授权公告日: 2009年 8月 19日 ) 中发明了 数据流关联控制方法 (Data-stream Related Control, DRC控制), 使现有数控系 统告别了插补时代, 迈入了数据流关联控制时代, 产生了新一代控制机即数据 流关联控制机(DRC控制机)。
发明人在发明专利 《一种标准化控制机》(申请号: 200910110439.9 PCT 国际申请号: PCT/CN2010/072914 )公开了一种标准化 DRC控制机及其重构方 法, 按照数字控制信息的生成、 分配发送、 执行的控制流程来配置控制资源, 所述标准化 DRC控制机由数字控制信息生成部件, 数字控制信息分配发送部件 与数字控制信息执行部件构成。
发明人将数字控制信息看作是一种产品, 将数字控制信息的生成、 分配、 发送、 执行这一制造数字控制信息的工艺流程称之为控制流程。
根据工艺流程配置相应的生产设备, 进行专业化标准化生产, 这是制造业 走过的必由之路。 显然, 工艺流程是分工合作、 实现专业化、 标准化生产的基 础。 将数字控制信息看作是一种产品, 则必然存在制造数字控制信息的工艺流 程。
正如在机械制造中必须按照机械制造的工艺流程来配置相应的加工设备一 样, 在信息制造中也必须按照制造数字控制信息的控制流程来配置相应的嵌入 式子系统。
发明人将控制流程划分为数字控制信息生成过程、 数字控制信息分配发送 过程与数字控制信息执行过程等三个子过程。
发明人发现, 数字控制信息的生成过程, 包括数字控制信息的解压过程、 数字控制信息的优化过程以及确定性误差的补偿过程等, 理应是 "运筹帷幄之 中, 决胜千里之外", 是一个非实时过程。 而数字控制信息的分配发送过程则有 如"军令如山", 数字控制信息的执行过程更是"兵贵神速", 都必须是实时的。
按照制造数字控制信息的控制流程, 开放式数控系统的体系结构可解耦为 数字控制信息生成部件(数字信息制造系统)、 数字控制信息分配发送部件(数 据流控制器)、 数字控制信息执行部件(伺服驱动装置与 I/O装置)等三个功能 部件。
在数字控制技术中, 由" 'Ό"形态的离散位置信息一般称为步进型, 由坐标 值增量构成的离散位置信息则称之为增量型。
设刀路(Tool Path )曲线为 X、 y、 Z、 A、 B、 W、 E、 H等 8个变量的函数。 其中, X、 y、 Z、 A、 B为联动的坐标轴, W、 E、 H为需要实时控制的参数(例 如, W为激光脉冲的宽度、 E为激光脉冲的能量、 H为激光脉冲的频率)。 对于 数据流关联控制来说, 需要实时控制的工艺参数与坐标值并无任何本质上的差 别, 可以将控制该工艺参数的开关视为虚拟坐标轴, 参数值视为该虚拟坐标轴 的坐标值, 从而将坐标轴联动与工艺参数的实时控制统一起来, 称之为多轴多 参数联动。 在本发明中, 坐标轴包括虚拟坐标轴。
表 1为 8联动的多维关联数据流的示意图。
表 1
Figure imgf000012_0001
表 1中, 时间 Τ被离散分割为 η个区间: Xti , i = Ι,. , ., η 。 Xti ( i = 1,..., n ) 称之为该刀路曲线的 T分割。 X、 y、 Z、 A、 B、 W、 E、 H等在 内的坐标值 增量离散为 AXi、 △ 、 △ 、 ΔΑι, ΔΒι, Z Wi、 △ 、 △¾。 线段 (△ Xi、 △ 、 △ 、 ΔΑι, 称之为该刀路曲线的 L分割。
在实时控制过程中, X轴首先进给 ΔΧ 经过 ^后再进给 ΔΧ2, 直到 ΔΧη, y、 Z、 A、 B、 W、 E、 H等轴也是如此。 因而, 是冗余的故舍去。 另外, 为 了统一控制步骤, 增加 At。。 M。与刀路曲线无关, 可适当设定, 例如, 将 设 定为 Atn。 将下标 0,1,..., n-1调整为 1,..., n。 为叙述的方便起见, 且有别于插补 周期, 将 T分割中的 ( i = l,..., n )称之为控制节律。
表 1 指出, 对于数据流关联控制来说, 需要实时控制的工艺参数与坐标值 并无本质上的差别, 可以将控制该工艺参数的开关视为虚拟坐标轴, 参数值视 为虚拟坐标轴的坐标值, 从而将坐标轴联动与工艺参数的实时控制统一起来, 称之为多轴多参数联动。 在本发明中, 坐标轴包括虚拟坐标轴。
由此可见, 刀路曲线的数字控制信息包括两部分。 第一部分是 L分割, 描 述相关坐标轴联动时的坐标值增量及其所要求的联动性, 用于控制相关坐标轴 联动以产生所要求的合成位移。 第二部分是 T分割, 描述所述合成位移之间的 随动性, 用于控制所述合成位移之间的时间间隔。 所述 L分割还包括传动链之 间的反向间隙、 螺距误差、 不垂直度与不平行度误差等确定性误差或热变形误 差之类的准确定性误差。
刀路曲线的 L分割在 T分割的控制下形成关联数据流。 根据离散位置信息 的" 'Ό"形态或坐标值增量形态,关联数据流可分为步进型关联数据流与增量型 关联数据流。
按给定的数据格式, 刀路曲线的 L分割在存储空间生成的数字映像称之为 刀路曲线的联动表。 按给定的数据格式, 刀路曲线的 Τ分割在存储空间生成的 数字映像称之为刀路曲线的随动表。
显然, 数字控制技术的核心任务是生成刀路曲线的联动表与随动表, 所谓 实时控制就是按照随动表中的控制节律向相应的伺服驱动装置分配发送联动表 中的坐标值增量。
在基于 IEEE定义的现有开放式数控系统中, L分割是在实时控制过程中 动态产生的。 控制节律 ( i = 1,..., n )称之为插补周期, 是等长的。 在实时 操作系统的控制下, 插补迭代控制算法在插补周期 ( i = n ) 中产生△ Li ( ΔΧι, △ 、 △ 、 ΔΑι, ΔΒι )„ 插补周期从而成为一个系统参数。
在数据流关联控制中, 数字控制信息生成部件无须配置实时操作系统, 不 存在插补周期, 控制节律 不是等长的。
从表 1 可以清楚地看出, 数字控制的基本问题就是制造关联数据流。 实时 控制过程的基本问题就是关联数据流的实时控制。
对于给定的工件, 所谓数字控制信息生成过程就是数字控制信息生成部件 制造关联数据流的过程, 即刀路曲线的联动表与随动表的生成过程。 根据加工工艺确定的顺序, 数字控制信息生成部件生成 DRC数控程序。
DRC数控程序由运动指令构成, 用于控制工件的加工过程。 运动指令包括 状态指令、 开关指令、 轨迹指令。 状态指令用于操作辅助功能; 开关指令用于 控制 I/O装置;轨迹指令用于控制伺服驱动装置,完成一条刀路曲线的走刀过程。
数字控制信息生成部件通过离散几何规划生成刀路曲线的联动表, 通过离 散运动规划生成刀路曲线的随动表, 并按给定的数据格式, 生成标准文件形态 的联动表与随动表。
一般采用常规的 PLC控制刀库,或采用软 PLC生成组合逻辑的控制流来控 制刀库中的换刀过程。 作为常规技术, 本发明不涉及用于刀库控制的控制流。
DRC数控程序是数字控制信息生成部件所制造的完全数字化、商品化的"数 字控制信息"产品。 DRC数控程序的生成过程就是采用运动指令的编程过程。 因 而, 数字控制信息生成部件既是数控编程的开放式平台又是数控技术的开放式 开发平台。
所谓数字控制信息分配过程就是数字控制信息分配发送部件将联动表中的 坐标值增量分配给相关的伺服驱动装置, 例如, 将△ 、 ΑΎι, △ 、 ΔΑ,, Δ 分配给 X、 y、 Z、 A、 B等 5个坐标轴的伺服驱动装置。
所谓数字控制信息的发送过程就是数字控制信息分配发送部件按照控制节 律实时控制数字控制信息的发送。
所谓数字控制信息的执行过程就是伺服驱动装置将坐标值增量写入位置 环, 驱动坐标轴进给。
在基于数据流关联控制的所述 DRC控制机中, 数字控制信息的生成不是实 时的, 数字控制信息的分配发送、 执行则是实时的。
发明人发现, 如果将 DRC数控程序的结构予以改进, 数字控制信息分配过 程则转化为非实时过程, 因而可将数字控制信息分配过程与数字控制信息发送 过程分离, 将控制流程划分为数字控制信息生成过程、 数字控制信息分配过程、 数字控制信息发送过程与数字控制信息执行过程等四个子过程, 将开放式数控 系统的体系结构解耦为数字控制信息生成部件、 数字控制信息分配部件、 数字 控制信息发送部件、 数字控制信息执行部件等四个功能部件。
继而, 发明人进一步发现, 数字控制信息的控制流程划分为生成过程、 分 配过程、 发送过程、 执行过程之后, 导致 DRC控制机的体系结构的重大改进, 成为一种基于 PC的、 全方位开放的、 标准化的可重构计算机数字控制系统。 发明内容 数据流关联控制( Data-stream Related Control, 简称 DRC控制 )的目的是为 第三次工业革命提出一种控制信息、 控制方法、 控制过程与体系结构全方位开 放的、 基于 PC的标准化控制机(简称为 DRC控制机), 以适应第三次工业革命 对数控系统的要求。
基于数字控制信息分配过程的非实时性, 本发明将 DRC控制机进行改进, 提出一种基于 PC的、 全方位开放的、 标准化的可重构计算机数字控制系统。
本发明的技术方案如下所述。
一种可重构计算机数字控制系统, 其特征在于, 包括 PC系统、 解译程序存 储器、 实时控制模块、 伺服驱动装置、 I/O装置、 串行接口、 联动接口、 I/O接 口;
所述 PC系统通过串行接口与所述伺服驱动装置连接, 通过 I/O接口与所述 I/O装置连接, 用于生成控制工件加工过程的 DRC数控程序, 包括状态指令生 成模块、 开关指令生成模块、 轨迹指令生成模块、 DRC数控程序生成模块、 轴 联动表分配模块、 DRC数控程序运行模块;
所述状态指令生成模块用于生成控制辅助过程的状态指令;
所述开关指令生成模块用于生成控制 I/O装置的开关指令;
所述轨迹指令生成模块用于生成控制伺服驱动装置完成刀路曲线走刀过程 的轨迹指令;
其中, 所述轨迹指令生成模块包括离散几何规划模块与离散运动规划模块; 所述离散几何规划模块用于生成存储有刀路曲线的 L分割的联动表;所述 L 分割用于控制坐标轴联动产生合成位移; 所述联动表区分为各个轴的轴联动表, 所述轴联动表用于存储相关坐标轴的 L分割分量, 控制该坐标轴产生轴位移; 所述离散运动规划模块用于存储有刀路曲线的 T分割与状态字的随动表; 所述 T分割用于控制所述轴位移之间的时间间隔; 所述状态字用于指定联动的 坐标轴;
所述 DRC数控程序生成模块, 用于根据加工工艺将状态指令、 开关指令、 轨迹指令链接为 DRC数控程序;
所述轴联动表分配模块用于通过所述串行接口向所述伺服驱动装置分配所 述轴联动表;
所述 DRC数控程序运行模块用于运行所述 DRC数控程序, 执行状态指令 控制辅助过程、 执行开关指令通过所述 I/O接口控制 I/O装置、 执行轨迹指令启 动所述实时控制模块通过所述联动接口控制所述伺服驱动装置完成刀路曲线的 加工过程;
所述解译程序存储器用于存储所述状态指令、 所述开关指令、 所述轨迹指 令的解释程序; 所述实时控制模块用于按照所随动表中的控制节律 ( i = n ), 通过 所述联动接口向所述伺服驱动装置发送联动命令; 所述联动命令用于控制所述 状态字指定的坐标轴之间的同步;
所述伺服驱动装置设有轴联动表初始化模块与轴联动表控制模块; 所述轴 联动表初始化模块用于设置执行标志, 并根据所述轨迹指令的顺序码, 将所述 轴联动表的首地址写入 L指针; 跟随所述联动命令, 所述轴联动表控制模块根 据 L指针从所述轴联动表中读取该轴的坐标值增量并写入位置环, 驱动坐标轴 进给产生合成位移。
进一步地, 上述可重构计算机数字控制系统中, 所述状态字的字节数为用 户参数。
所述轴联动表文件还包括特征表; 所述特征表用于标识该坐标轴的逻辑属 性; 所述逻辑属性包括进给当量、 数据的字节数、 电子齿轮传动比。
所述联动接口的每个数据位分别连接一个伺服驱动装置。
所述串行接口为现场总线、 RS232接口、 RS485接口、 USB接口或无线接 口。
所述 DRC数控程序运行模块包括运动指令取指模块、 状态指令执行模块、 开关指令执行模块、 轨迹指令执行模块; 所述运动指令取指模块用于将 DRC数 控程序的首地址写入运动指令指针并读取运动指令, 将运动指令的功能字节写 入运动指令寄存器, 将下一条运动指令的地址写入运动指令指针; 所述运动指 令指针用于指定下一条运动指令的地址; 如果所述运动指令为状态指令, 所述 状态指令执行模块用于执行该状态指令的解译程序; 如果所述运动指令为开关 指令, 所述开关指令执行模块用于执行该开关指令的解译程序; 如果所述运动 指令为轨迹指令, 所述轨迹指令执行模块用于执行该轨迹指令的解译程序。
进一步地, 所述轨迹指令执行模块设置运行标志, 启动所述实时控制模块; 所述实时控制模块包括联动坐标轴设置模块、 联动命令设置模块、 节律控制模 块、 终点控制模块; 所述联动坐标轴设置模块用于将随动表的首地址写入 T指 针, 从所述随动表中读取状态字并写入状态字寄存器, 指定联动的坐标轴; 所 述联动命令设置模块用于读取所述随动表中的 ( i = l,..., n )并写入 T分割定 时器; T分割定时器中的定时时间到, 所述节律控制模块用于启动脉冲发生器输 出一个脉冲, 通过联动接口向所述状态字寄存器指定的伺服驱动装置发送联动 命令; 所述终点控制模块用于控制所述轨迹指令的终点, 如果所述 T指针等于 所述随动表的末地址, 即到达所述轨迹指令的终点, 关闭运行标志; 否则, T 指针指向下一个△ 。 进一步地, 所述实时控制模块还包括随动表文件存储器与文件读取模块, 通过内部总线与所述 PC系统 1连接;所述随动表文件存储器用于接收并存储所 述随动表文件; 所述文件读取模块用于读取所述随动表文件。
进一步地, 所述实时控制模块通过双口 RAM与 PC系统连接; 所述双口 RAM中存储所述随动表。 本发明提出的一种可重构计算机数字控制系统的数字控制方法包括下述步 骤:
步骤 1、 DRC数控程序生成步骤: 用于 PC系统 1生成 DRC数控程序, 包 括下述步骤:
步骤 101、 轨迹指令生成步骤: 轨迹指令生成模块生成控制伺服驱动装置 4 完成刀路曲线走刀过程的轨迹指令, 包括离散几何规划步骤与离散运动规划步 骤; 离散几何规划步骤用于离散几何规划模块生成存储有刀路曲线的 L分割的 联动表; 所述 L分割用于控制坐标轴联动产生合成位移; 所述联动表区分为各 个轴的轴联动表, 用于存储各个坐标轴的 L分割分量, 控制该坐标轴产生轴位 移; 离散运动规划步骤用于离散运动规划模块生成存储有刀路曲线的 T分割与 状态字的随动表; 所述 T分割用于控制所述轴位移之间的时间间隔; 所述状态 字用于指定联动的坐标轴。
步骤 102、状态指令生成步骤: 状态指令生成模块生成控制辅助过程的状态 指令。
步骤 103、 开关指令生成步骤: 开关指令生成模块生成控制 I/O装置的开关 指令。
步骤 104、 DRC数控程序生成步骤: DRC数控程序生成模块根据加工工艺 将所述状态指令、 所述开关指令、 所述轨迹指令链接为 DRC数控程序。
步骤 2、 轴联动表分配步骤: 轴联动表分配模块 15通过串行接口 6向伺服 驱动装置 4分配所述轴联动表。
步骤 3、 DRC数控程序运行步骤: DRC数控程序运行模块 16运行所述 DRC 数控程序, 包括下述步骤:
运动指令取指步骤: 运动指令取指模块 161将 DRC数控程序的首地址写 入运动指令指针并读取运动指令,将运动指令的功能字节写入运动指令寄存器, 将下一条运动指令的地址写入运动指令指针; 所述运动指令指针用于指定下一 条运动指令的地址;
状态指令执行步骤: 如果运动指令取指步骤中的运动指令为状态指令, 状 态指令执行模块 162则执行该状态指令的解译程序;
开关指令执行步骤: 如果运动指令取指步骤中的运动指令为开关指令, 开 关指令执行模块 163则执行该开关指令的解译程序; 轨迹指令执行步骤: 如果运动指令取指步骤中的运动指令为轨迹指令, 轨 迹指令执行模块 163则执行该轨迹指令的解译程序。
进一步的, 上述可重构计算机数字控制系统的数字控制方法中, 所述轨迹 指令执行步骤设置运行标志, 并启动下述实时控制步骤:
步骤 a、 联动坐标轴设置步骤: 根据所述轨迹指令的顺序码, 联动坐标轴 设置模块 31将随动表的首地址写入 T指针, 从随动表中读取状态字并写入状 态字寄存器, 指定联动的坐标轴;
步骤 b、联动命令设置步骤: 根据 T指针, 联动命令设置模块 32读取随动 表中的 ( i = l,..., n ) 并写入 T分割定时器;
步骤 c、 节律控制步骤: T分割定时器中的定时时间到, 节律控制模块 33 启动脉冲发生器输出一个脉冲, 通过联动接口 7向状态字寄存器指定的伺服驱 动装置 4发送联动命令;
步骤 d、 联动表控制步骤: 跟随所述联动命令, 伺服驱动装置 4的轴联动 表控制模块 41根据 L指针从其轴联动表中读取坐标值增量, 写入位置环, 驱 动坐标轴进给产生合成位移;
步骤 e、 终点控制步骤: 终点控制模块 34控制轨迹指令的终点, 如果 T指 针等于随动表的末地址, 即到达所述轨迹指令的终点, 关闭运行标志; 否则, T 指针指向下一个 重复步骤 b至步骤 e。
本发明提出的一种可重构计算机数字控制系统的重构方法包括下述步骤: 步骤 1、 重构离散坐标系: PC系统 1重构离散坐标系; 所述离散坐标系包 括正交离散坐标系与非正交离散坐标系。
步骤 2、 重构结构常数数据库: PC系统 1重构结构常数数据库; 所述结构 常数数据库存储坐标轴的精细结构常数与坐标系参数; 所述坐标轴的精细结构 常数包括线位移误差、 角位移误差、 反向间隙; 所述坐标系参数包括坐标轴之 间的不平行度、 不垂直度。
步骤 3、 重构状态指令: PC系统 1重构状态指令; 所述状态指令用于控制 辅助过程;
步骤 4、 重构开关指令: PC系统 1重构开关指令; 所述开关指令用于控制 I/O装置。 与现有技术对比, 本发明产生的原创性有益效果为:
1、 基于控制流程的加工过程模型
基于 IEEE定义的现有开放式数控系统面向对象,采用有限状态机加工数据 模型描述复杂的、 具有不同层次实时性要求的多个控制任务。 有限状态机是反 应式系统的一种高度抽象的建模工具, 对开发商而言, 结构复杂, 复用性差; 对用户而言, 则犹如蛛网式迷宫, 毫无开放性。
数据流关联控制不是面向对象, 而是面向过程。 根据数字控制的过程特征, 本发明为开放式数控系统提出一种加工过程模型。
与基于 IEEE定义的现有开放式数控系统的有限状态机模型对比,这种加工 过程模型是开放的, 极为清楚地描述了开放式数控系统的体系结构, 揭示了在 不同的控制流程中合理配置控制资源的技术方案与关键技术。
2、 数字控制方法的重大变革
在基于 IEEE定义的现有开放式数控系统中, 实时操作系统的插补周期与现 场总线的通信周期是两个系统时钟。 跟随插补周期与通信周期的节拍, 刀路曲 线的数字控制信息不断地生成、 分配、 发送、 执行, 从而以数字控制信息的实 时迭代与控制过程的实时迭代的方式周而复始。 在这种体系结构中, 刀路曲线 的实时控制过程既包括数字控制信息的实时迭代与控制过程的实时迭代, 又包 括实时通信过程, 涉及插补迭代算法的精度与速度、 刀路曲线的几何特征、 加 工过程的工艺特征、 机械系统的运动学 /动力学特征、 处理器的位数与运算速度 等硬件平台、 实时操作系统等软件平台等一系列复杂因素。
本发明按照数字控制信息的生成、 分配、 发送、 执行的控制流程配置控制 资源, 并将数字控制信息的生成过程与分配过程非实时化, 刀路曲线的实时控 制过程简化为启动实时控制模块按照随动表中的 ( i = l ,. . . , n )指定的节律, 通过联动接口向状态字指定的伺服驱动装置单向发送联动命令; 伺服驱动装置 则跟随联动命令, 将所述轴联动表中的坐标值增量逐次写入位置环, 驱动相应 坐标轴联动产生合成位移。
本发明以随动表中的节律 ( i = l , . . ., n )取代了插补周期, 取消了实时操 作系统对实时控制过程的控制权, 以最简单的单向发送的联动命令取代了极为 复杂的实时通信, 取消了现场总线对实时控制过程的控制权, 从而将刀路曲线 的实时控制过程转化为最简单的联动命令的实时发送, 彻底清除了操作系统与 现场总线对实时控制过程的制约, 实现了实时控制方法与实时控制过程的开放 性, 导致数字控制方法的重大变革。
3、 高精度多轴同步机制
多轴同步驱动技术是现有数控技术中亟待解决的关键技术。 国家 "高档数 控机床与基础制造装备" 2009年度科技重大专项 "课题 18 全数字高档数控装 置" 将双轴同步驱动技术列为现有数控技术中的一项关键技术。
在基于 IEEE定义的开放式数控系统中, 多轴同步取决于现场总线中周期 通信的实时同步机制。
简单就是美。 在本发明中, 多轴同步取决于通过联动接口实时发送的联动命令, 联动的 坐标轴则由状态字指定。 所述联动命令为并行的同步脉冲, 所述状态字为用户 参数, 所述联动接口类似于状态字控制下的并行接口。 因此, 本发明以极为简 单的技术手段解决了多轴同步机制问题, 具有高速高精度的同步能力, 从而将 复杂的多轴同步驱动技术转化为简单的常规技术。
4、 优良的可重构性
机械系统的重构意味着坐标轴运动关系的改变与坐标轴的增减, 特别是坐 标轴的增加。 因而, 刀路曲线的实时控制过程的可重构性成为可重构计算机数 字控制系统的核心问题, 这就要求实时控制方法完全软件化, 实时控制过程与 操作系统、 现场总线等软件平台无关、 与编程接口无关。
基于 IEEE定义的现有开放式数控系统面向对象而不是面向过程,刀路曲线 的实时控制过程无法开放, 不具有可重构性。 对于不同的曲线类型, 必须定义 专用的插补指令并配置特定的实时插补控制模块, 因而, G代码标准下的插补 指令也不具有可重构性。 相应于坐标轴运动关系的改变, 基于 IEEE定义的现有 技术只能是增加实时插补控制模块或修改现有实时插补控制模块。 显然, 这与 可重构性的内涵相距甚远。 相应于坐标轴的增加, 特别是相应于 5轴及 5轴以 上的机械系统的重构, 基于 IEEE定义的现有技术则只能求助于 64位以上的高 速 CPU、 64位以上的更强实时性的实时操作系统、 更优化的实时调度能力、 以 及更先进的插补迭代控制算法, 而且必须重新研发那个庞大而复杂的中断系统。 显然, 这已不是重构问题了。
本发明中的轨迹指令只有一种格式, 与刀路曲线中的曲线类型无关。 不存 在重构问题。
在本发明中, PC系统所制造的 DRC数控程序、 轴联动表、 随动表等文件 包括了控制伺服驱动装置与 I/O装置所需要的全部数字控制信息,数字控制信息 是开放的, 制造数字控制信息的方法是开放的; 此外, 本发明还将数字控制信 息分配过程非实时化, 将数字控制信息的实时发送转化为极为简单的联动命令 的实时发送, 数字控制信息分配过程也是开放的。
相应于坐标轴的增加, 在本发明中只涉及状态字的位数与字节数。 作为用 户参数, 状态字的位数与字节数不存在重构问题。
在本发明将刀路曲线的实时控制过程简化为启动实时控制模块。 所述实时 控制模块是开放的, 通过内置固化的文件读取模块, 其运行与 PC的操作系统无 关, 也无须配置任何嵌入式实时操作系统。
本发明既没有插补周期, 也没有通信周期, 全面实现了实时控制方法的软 件化, 完全解决了刀路曲线的实时控制过程的重构问题。 相应于机械系统的重构, 还涉及辅助功能操作与 I/O装置中的开关量控制。 这就涉及本发明中的状态指令与开关指令。
状态指令与开关指令都与机械系统的特定结构密不可分, 属于个性化功能。 机械系统重构后, 状态指令与开关指令往往需要重构。
在本发明中, 状态指令与开关指令的结构与功能极为简单, 对于用户来说, 在 PC 的用户层重新定义状态指令与开关指令并编写其解译程序是熟悉的简单 技术。
数字控制系统的重构还涉及内部接口的重构, 特别是运动控制级实时接口 的重构。 本发明将运动控制接口分为非实时串行接口与实时联动接口。
本发明的联动接口并非通信接口, 联动命令只是同步脉冲。 在发送端, 联 动接口类似按 Ati ( i = Ι , . , . , η )所指定的节律不断地单向传输状态字的并行接口; 在接收端, 一个伺服驱动装置分别与联动接口的一个数据位连接, 联动接口类 似一根中断控制线。 因而, 本发明提出的联动接口不存在重构问题。
本发明的非实时接口是一个标准串行接口, 例如标准的 USB接口或 UART 支持下的其他标准串行接口, 属于常规技术。 所述非实时接口无须重构。
在本发明中, PC系统、 实时控制模块、 运动控制接口均与操作系统等软件 平台无关, 也与硬件平台无关。 因而, 本发明提出的可重构计算机数字控制系 统具有平台无关性。
数字控制系统的重构还涉及编程接口。在基于 IEEE定义的现有开放式数控 系统中, G代码形式的数控加工程序必须在实时操作系统的掌控下进行, 从而 与软硬平台相关。 作为编程接口, G代码标准不具备人机界面的一致性。 在本 发明中, 所述 DRC数控程序采用标准化文件系统取代 G代码程序, 具有人机界 面的一致性, 不存在重构问题。
因此, 在本发明中, 数字控制系统的重构仅涉及离散坐标系的重构与结构 常数数据库的重构。 这些问题均属于 PC中的常规技术。
综上所述, 机械系统重构后, 对于本发明所提出的可重构计算机数字控制 系统, 轨迹指令与刀路曲线的实时控制过程、 联动接口与非实时接口均无须重 构, 需要重构的仅限于离散坐标系与结构常数数据库, 以及在 PC的用户层重新 定义状态指令与开关指令, 编写其解译运行程序。 因而, 本发明将可重构计算 机数字控制系统的重构方法转化为 PC 中的常规技术手段, 具有优良的可重构 性, 完全解决了可重构计算机数字控制系统的重构问题。
5、 标准化
1)、 体系结构的标准化
本发明提出的可重构计算机数字控制系统的体系结构, 基于数字控制信息 的生成、 分配、 发送、 执行的控制流程配置控制资源。 特别是, 本发明在数字 控制信息分配过程中通过非实时串行接口向伺服驱动装置分配轴联动表, 从而 将数字控制信息的分配过程非实时化, 显著简化了可重构计算机数字控制系统 的体系结构。
在本发明提出的可重构计算机数字控制系统中, 数字控制信息生成部件基 于 PC, 是一个标准化部件。 数字控制信息生成部件所制造的 DRC数控程序、 轴联动表、 随动表等数字控制信息文件都是标准文件, 与操作系统等软件平台 无关。 标准化文件系统成为数字控制信息的载体, 实现了数字控制信息的开放 性。
在本发明中, 实时控制模块无须配置操作系统, 其核心功能仅在于将△ 写入 T分割定时器, 在状态字控制下通过联动接口实时发送联动命令, 功能与 结构极为简单, 可以标准化。
2)、 运动控制接口的标准化
数字控制系统的标准化还涉及内部接口的标准化, 特别是运动控制级实时 接口的标准化。
在基于 IEEE定义的现有开放式数控系统中,为了实现坐标值增量的实时分 配, 现场总线技术成为数控系统与伺服驱动装置之间的运动控制接口的主流技 术。 所述现场总线技术以 ISO/OSI开放系统互联参考模型为基础, 完全忽视了 数字控制的过程特征, 完全忽视了数控设备区别于计算机网络的本质特征。 通 信周期成为系统时钟, 数据链路层与应用层及其协议的实时性, 数据表示的兼 容性等一系列问题耗费了大量计算资源。
现场总线的国际标准多达 12个, 厂商的企业标准更多。 这种状况导致中国 国家标准" GB/T 18759.2-2006·机械电气设备 ·开放式数控系统*第 2部分体系结 构"设置了 5.6款, 要求支持各类现场总线(例如 CAN、 Profibus, Sercos等)。
不幸的是, 多标准就意味着没有标准。
本发明将运动控制接口分为非实时串行接口与实时联动接口。 在辅助过程 中, 将每个坐标轴的轴联动表通过串行接口分配给相应的伺服驱动装置。 在所 述串行接口中, 通信周期并非系统参数, 不存在同步机制, 避免了通信协议的 实时性及其他复杂问题。 所述轴联动表为标准文件, 不存在数据表示的兼容性 问题。 因而, 所述串行接口可以是任何标准串行接口, 例如标准的 USB接口或 UART支持下的其他标准串行接口。
所述联动命令只是一个同步脉冲。 在发送端, 联动接口类似按 (i = 1,..., n) 的节律不断地单向传输状态字的并行接口; 在接收端, 一个伺服驱动装置分 别与联动接口的一个数据位连接, 联动接口则类似一根中断控制线。 显然, 所 述联动接口可以标准化。 因此, 所述联动接口与所述非串行接口都是标准化的, 解决了运动控制接 口的标准化问题。
3)、 编程接口的标准化
在基于 IEEE定义的现有开放式数控系统中,采用 G代码标准作为数控加工 程序的编程接口。 上世纪 50年代纸带作为输入的基本物理介质时, 为规范在纸 带上表示字符, 制定了纸带穿孔的编码标准, 即 G代码标准。
在 G代码程序中, 用不同的插补指令来描述一条刀路曲线中的不同曲线。 对于不同的曲线又必须使用不同的插补迭代算法来实现不同的插补指令, 曲线 的实时加工过程被插补迭代算法实时化, 从而导致插补迭代算法成为面向对象 的封闭的实时控制算法, 从实时控制过程方面制约了数字控制系统的开放性与 可重构性。
G代码标准是信息技术起步阶段的原始产物, 受纸带的限制不可避免地存 在信息量过少的缺陷。 各个厂商因而对 G代码都进行了基本语义之外的扩张, 导致 G代码程序与相应硬件的依赖, 数控加工程序在不同的数控系统之间不具 有互换性, 不具备人机界面的一致性, 造成各种数控系统互不兼容, 阻碍控制 信息的交换与共享, 从编程接口方面制约了数字控制系统的开放性与可重构性。
在插补迭代算法中, 每个坐标轴必须具有相同的逻辑属性。 一旦坐标坐标 轴的逻辑属性不同, 例如, 进给当量(纳米、 微米等) 不同、 数据的字节数不 同等, 数控系统的功能与结构都要发生相应的变化, 从实时控制过程与实时通 信过程两方面制约了系统的开放性与可重构性。
在本发明提出的可重构计算机数字控制系统中, 根据加工工艺确定的顺序, 采用状态指令、 开关指令、 轨迹指令来编写 DRC数控程序。
DRC数控程序面向控制流程, 轨迹指令面向刀路曲线的加工过程。 轨迹指 令的轴联动表与随动表携带加工刀路曲线所需要的全部数字控制信息, 由数字 控制信息生成部件非实时地制造出来, 因而允许每个坐标轴具有不同的逻辑属 性。
上述 DRC数控程序、 轴联动表、 随动表都以标准化文件的形态在系统中进 行传送, 也以文件的形态在不同的数控系统之间进行传送。
上述文件符合文件规范, 采用诸如 FAT16、 FAT32等文件系统。 标准化文件 成为数字控制信息的载体, 与硬件平台无关, 与操作系统等软件平台无关, 具 有广泛的平台无关性, 实现了数字控制信息的开放性。 上述 DRC数控程序、 轴 联动表、 随动表都采用标准化文件系统, 实现了控制信息的标准化, 成为一种 易于标准化的编程接口。 综上所述, 本发明提出的可重构计算机数字控制系统实现了数字控制信息 的开放性, 数字控制方法的开放性, 数字控制信息的生成过程、 分配过程、 发 送过程、 执行过程的全程开放性, 为数字控制系统的标准化奠定了坚实的基础。
6、 通用高效的开放式数控语言
与现有 G代码数控语言对比, 本发明提出的状态指令、 开关指令、 轨迹指 令与 DRC数控程序面向工作机, 逻辑结构简单, 具有人机界面的一致性, 基于 PC且无须编译, 是一种关于数控技术的开放的、 通用的、 高效率的运动描述语 言和逻辑描述语言, 充分支持用户自行拓展数控技术的应用并始终保持人机界 面的一致性。
7、 高可靠性
众所周知, 在基于 IEEE定义的现有开放式数控系统中, 插补周期与通信周 期是两个系统参数, 不仅耗费了大量的计算资源, 而且将数字控制信息的生成、 分配、 发送、 执行的整个控制流程实时化, 导致实时操作系统与现场总线成为 制约数控系统可靠性的两个关键环节。
操作系统是一个极为复杂的系统, 可能隐含有几百上千个潜在的漏洞。 这 些漏洞往往需要几年、 十几年的维护时间来修复, 并且也很难彻底消除。 统计 资料指出, 影响计算机系统可靠性的因素, 硬件错误仅占百分之几, 绝大多数 的错误来源于系统的管理。 显然, 系统管理的错误则基本上来源于操作系统。 因此, 对于计算机数字控制系统的可靠性来说, 实时操作系统犹如达摩克利斯 之剑。
通信过程暴露于恶劣的工业环境中,在基于 IEEE定义的现有开放式数控系 统中, 现场总线导致通信周期也成为一个系统参数, 通信协议的实时性、 数据 表示的兼容性等一系列问题导致内部通信高度复杂化, 是影响可靠性的另一个 重要原因。
在本发明中, PC不介入刀路曲线的实时控制过程, 实时控制模块的运行与 PC的操作系统无关, 也无须配置任何嵌入式实时操作系统。
本发明将数字控制信息分配过程从数字控制信息的实时控制过程中分离, 在一次通信过程中完成数字控制信息的分配过程, 通信周期不再是系统参数。 特别是, 与现场总线中的实时周期通信过程对比, 本发明中的联动接口只是简 单地单向发送同步脉冲, 功能与结构高度简化。
综上所述, 本发明从源头上解决了制约数控系统可靠性的两个关键环节, 具有高可靠性。
8、 第三次工业革命所期盼的控制机 在一般的意义上, 现代制造装备的体系结构可抽象为三个系统, 即动力机、 工作机和控制机。 动力机提供能量, 控制机向工作机与动力机发送控制信息, 工作机从动力机获取能量完成产品的制造。
第一次工业革命的标志是工作机的诞生, 机械代替手工工具。
第二次工业革命的标志是动力机的诞生, 蒸汽机、 内燃机、 电机代替了人 力、 畜力。
第三次工业革命将以自动化为主要标志, 即控制机的诞生。
从制造业的观点来看, 上述划分是符合逻辑的。
在制造业中, 数字控制系统扮演控制机的角色。 然而, 现有数字控制系统 在开放性、 可重构性、 标准化以及数字控制技术的软件化等方面存在严重缺陷, 并非可以与动力机、 工作机相提并论, 难以成为第三次工业革命所期盼的控制 机。
与基于 IEEE定义的现有开放式数控系统相比,本发明提出的可重构计算机 数字控制系统具有高度简化的实时控制过程与数字控制方法、 数字控制技术完 全软件化、 可靠性高、 可以标准化、 价格低廉、 易于普及等显著优点。 因而, 作为一种基于 PC的、 全方位开放的、 可重构的、 标准化的开放式数控系统, 本 发明提出的可重构计算机数字控制系统正是第三次工业革命所期盼的控制机。 附图说明 图 1为基于控制流程的加工过程模型图一;
图 2为基于控制流程的加工过程模型图二;
图 3为具体实施方式中数控系统的体系结构示意图;
图 4为图 1中的 PC系统的功能模块图;
图 5为图 1中的实时控制模块的功能模块图;
图 6为图 1中的伺服驱动装置的功能模块图。 具体实施方式 为了保证机床结构及其布局可以根据所加工产品的变化进行快速重组, 模 块化结构成为可重构机床的基本技术特征。 通常, 模块化的概念及其实施仅局 限在机床制造企业内部。 然而, 在可重构机床中, 模块化的概念及其实施必须 延伸到用户, 换言之, 面向用户是可重构性的本质特征。
在可重构机床中, 所谓可重构性, 指的是用户可以根据所加工产品的变化 对机床的结构、 布局、 加工功能进行快速重组的能力。
相对于可重构机床的模块化, 通常认为可重构计算机数字控制系统也应模 块化。 数字控制系统的核心功能是实时控制刀路曲线的加工过程。 这就意味着, 对于可重构计算机数字控制系统来说, 刀路曲线的实时控制过程必须是开放的, 从而成为面向用户的。
在背景技术中已说明, 在基于 IEEE定义的现有开放式数控系统中, 刀路曲 线的实时控制过程无法开放。 其原因在于, 一方面, 用于实时控制过程的数控 应用软件系统成为实时操作系统掌控下的采用并行算法、 涉及多进程 /多线程嵌 套调用以及多重实时嵌套中断的一个庞大而复杂的中断系统。 另一方面, 刀路 曲线的实时控制过程与刀路曲线的几何特征、 加工过程的工艺特征、 机械系统 的运动学 /动力学特征密不可分,与 CPU的位数、运算速度等硬件平台密不可分, 与实时操作系统等软件平台密不可分, 与插补迭代算法密不可分。
因而, 在基于 IEEE定义的现有开放式数控系统中, 所谓实时控制的模块化 结构实质上是面向对象的模块化结构, 也就是对于不同的刀路曲线, 配置不同 的实时控制模块。 不幸的是, 这种面向对象的模块化结构并不是面向用户的, 而是面向数控系统制造企业的, 与可重构性的本质特征完全背道而驰。 因而, 依赖这种面向对象的模块化结构来实现数字控制系统的可重构性只是一种幻 觉。
人与机床是数字控制系统的两个服务对象, 三者之间必然存在信息交换问 题。 在背景技术中已说明, 在基于 IEEE定义的现有开放式数控系统中, 在人机 界面上采用 G代码标准作为编程接口, 在运动控制级采用现场总线, 从而导致 编程接口与现场总线成为基于 IEEE定义的现有开放式数控系统没有可重构性的 重要因素。
基于上述分析, 发明人将可重构计算机数字控制系统定义为:
所谓可重构计算机数字控制系统是按照控制流程配置嵌入式子系统的计算 机数字控制系统, 具有实时控制方法软件化, 实时控制过程与处理器位数、 速 度等硬件平台的无关性、 与操作系统等软件平台的无关性、 以及与编程接口的 无关性。
数据流关联控制按照制造数字控制信息的流程来配置控制资源。 DRC数控 程序成为数字控制信息生成部件所制造的完全数字化、商品化的"数字控制信息" 产品。 所述数字控制信息生成部件既是数控编程的开放式平台又是数控技术的 开放式开发平台, 实时控制方法完全软件化。
在现有开放式数控系统的体系结构中, 伺服驱动装置视为数控机床的功能 部件, 不属于数控系统的范畴。 根据可重构计算机数字控制系统的上述定义, 本发明从控制流程、 体系结构、 现场总线、 编程接口等方面进一步改进 DRC 控制机。 这些问题都需要将伺服驱动装置纳入数控系统之中, 重新审视伺服驱 动装置的功能与结构。 在机床的数字控制中, 伺服驱动装置包括伺服电机及其运动控制系统, 主 要用于控制伺服电机的转速与转角。 所谓转速控制又称速度模式, 也就是速度 控制, 用于控制主轴的转速; 所谓转角控制又称位置模式。 也就是位置控制, 用于控制坐标轴的位移。 在本发明中, 伺服驱动装置为位置模式, 其接收与执 行的数字控制信息为坐标轴的离散位置信息, 位置反馈信息由伺服驱动装置内 的嵌式入系统处理。 至于主轴的转速则视为工艺参数, 归于带参数的开关量控 制。
从背景技术可知, 在数据流关联控制中, 数字控制技术的核心任务是生成 刀路曲线的联动表与随动表。 所谓实时控制过程, 就是按照随动表中的控制节 律, 坐标值增量的分配过程、 发送过程、 执行过程的周而复始。
例如, 为实现 X、 y、 Z、 A、 B 等 5个坐标轴的 5轴联动, 首先从联动表 中读取 ΔΧ Ayi, AZ^ AA^ 并通过运动控制接口分别发送给 X、 y、 Z、 A、 B等伺服驱动装置; X、 y、 Z、 A、 B等伺服驱动装置接收 ΔΧ^ Αγ,, △Ζ ΔΑ 后, 写入其位置环, 驱动 X、 y、 Z、 A、 B等 5轴联动, 实现 合成位移 ; 再经过△ 后, 从联动表中读取 ΔΧ2、 Ay2, ΔΖ2, ΔΑ2, Δ Β2并通过运动控制接口分别发送给 X、 y、 Z、 A、 B等伺服驱动装置; X、 y、 Z、 A、 B等伺服驱动装置接收 ΔΧ2、 Αγ2, ΔΖ2, ΔΑ2, ΔΒ2后, 写入其位置环, 驱动 X、 y、 Z、 A、 B等 5轴联动, 实现合成位移 AL2; 如此周而复始, 从而 按照控制节律产生刀路曲线所要求的合成位移, 直至刀路曲线的终点。 生成部件生成。
联动表中的 L分割
△Li ( \Xi、 △ 、 △ 、 ΔΑι, ΔΒι), i= Ι,.,.,η,
可以按△ 、 Ay,, △ 、 ΔΑ,, 分离为 5个子表, 称之为所述刀路曲线的 轴联动表。 如果将 X、 y、 Z、 A、 B等 5轴的轴联动表在辅助过程中分配给 X、 y、 Z、 A、 B等伺服驱动装置, 数字控制信息分配发送过程得以分离为数字控制 信息分配过程与数字控制信息发送过程, 从而将数字控制信息分配过程非实时 化, 并从数字控制信息的实时控制过程中分离出来。
这样一来, 对于 X、 y、 Z、 A、 B等 5轴联动的刀路曲线, 其实时控制过程 就是, X、 y、 Z、 A、 8等伺服驱动装置按随动表中的控制节律 ^ (1=1,...,1 ), 从 XXi (i= 1,·..,η)、 Δγι (i= Ι,.,.,η), ΔΖι (i= Ι,.,.,η), ΔΑι (i= Ι,.,.,η), ΔΒ, (i=l,...,n)等 5个轴联动表中实时同步地读取坐标值增量并予以执行。
数字控制信息分配过程的非实时化导致下述四方面的重要改进。
1)、 加工过程模型与体系结构 文献《开放式数控技术及其在我国的发展状况》(《航空制造技术》, 2010年 第 3期, 作者: 富宏亚 梁全)指出, 数控系统的开放性可以分为 3 类: 数控 系统软件的开放性、 加工数据模型的开放性和硬件实施平台的开放性。
数控系统的加工数据模型是规划体系结构与开发数控技术的基础。
基于 IEEE定义的现有开放式数控系统面向对象,加工数据模型用于描述数 控系统中每个对象的功能、 行为、 起始过程、 以及它们之间相互操纵的关系, 特别是针对复杂的、 具有不同层次实时性要求的多个控制任务进行清楚的描述。 因而, 采用有限状态机 ( Finite State Machine, FSM )的加工数据模型在开放式数 控系统的开发中占有重要的地位。 例如, 中国国家标准 《GB/T 18759. 1-2002· 机械电气设备 *开放式数控系统 *第 1部分 总则》、 《GB/T 18759.2-2006·机械电 气设备 ·开放式数控系统*第 2部分: 体系结构》都清楚地规范了有限状态机模 型。 有限状态机是反应式系统的一种高度抽象的建模工具, 对开发商而言, 结 构复杂, 复用性差; 对用户而言, 则犹如蛛网式迷宫, 毫无开放性。
数据流关联控制不是面向对象, 而是面向过程, 必须根据数字控制的过程 特征, 为开放式数控系统提出一种开放的加工过程模型。
本发明将控制流程划分为数字控制信息生成过程、 数字控制信息分配过程、 数字控制信息发送过程与数字控制信息执行过程等四个子过程, 进而将数字控 制信息分配过程从数字控制信息的实时控制过程分离, 成为非实时过程。
数字控制信息分配过程从数字控制信息的实时控制过程中分离后, 所述数 字控制系统的体系结构解耦为数字控制信息生成部件、 数字控制信息分配部件、 数字控制信息发送部件、 数字控制信息执行部件等四个功能部件。 数字控制信 息执行部件包括伺服驱动装置与 I/O装置。
所述控制流程可分为实时过程与非实时过程。 从可重构性来看, 所述四个 功能部件的功能与结构应重新审视, 所述实时过程与非实时过程的控制方法应 重新审视。
2 )、 文件结构
数字控制信息分配过程从数字控制信息的实时控制过程中分离后, 作为数 控加工的 DRC数控程序的结构, 应从可重构性方面来重新审视, 以支持所述实 时控制过程与非实时分配过程。
3 )、 编程接口
所述程序接口指的是不同数控系统之间交换加工程序时, 加工程序之间的 编程接口。
在不同数控系统之间, DRC数控程序成为编程接口。 数字控制信息分配过 程从数字控制信息的实时控制过程中分离后, 在控制流程中, 文件成为数字控 制信息的载体。 因此, 所述 DRC数控程序文件与操作系统平台无关。 然而, 从 可重构性来看, 所述 DRC数控程序作为编程接口, 应与现场总线无关。
4 )、 内部接口
数字控制信息分配过程从数字控制信息的实时控制过程中分离后, 轴联动 表非实时地分配给伺服驱动装置, 实时控制过程得以高度简化, 内部接口的实 时通信过程得以高度简化, 内部接口的功能与结构应重新审视, 以支持实时通 信过程的可重构性。 本发明提出一种可重构计算机数字控制系统, 从数字控制系统的开放式体 系结构、实时过程与非实时过程的控制方法、 DRC数控程序的结构与编程接口、 内部接口的功能与结构、 伺服驱动装置的功能与结构等方面对所述 DRC控制 机进一步予以改进, 以适应第三次工业革命对可重构计算机数字控制系统的要 求。
下面将结合附图及具体实施例对本发明的技术方案进行详细描述。
工件的加工过程一般可划分为辅助过程、 换刀过程与走刀过程。
辅助过程涉及由 I/O装置控制的辅助功能与状态设置。
换刀过程涉及刀库控制。 对于换刀过程, 一般采用常规的 PLC控制刀库, 或采用软 PLC生成组合逻辑的控制流来控制换刀过程。本发明不涉及 PLC及 I/O 装置的控制方法。
走刀过程涉及刀路曲线的实时控制。
因此, 在工件的加工过程中, 数控系统只有三种工作状态: 辅助功能操作、 开关量控制、 刀路曲线的实时控制。 数据流关联控制用状态指令、 开关指令、 轨迹指令三类运动指令来描述这三种工作状态。
一、 运动指令
1 )、 状态指令与辅助功能操作
状态指令用于描述辅助功能。
状态指令可分为系统初始化状态指令与系统运行状态指令。
系统初始化状态指令用于设置 /修改一些参数, 例如设定伺服驱动装置的初 始化参数、 刀库的初始化参数等。 系统运行状态指令用于设定系统的运行状态, 例如, 设置自动、 手动、 指定程序段、 启动、 结束、 暂停等运行状态, 实现检 测、 参数调整、 故障诊断等功能。
状态指令包括功能字节、 辅助字节。
( 1 )、 功能字节
功能字节为 2个字节, 用于描述该状态指令的基本功能, 包括标识码与指 令码。 第 1个功能字节为状态指令的标识。
B7 : 状态指令或开关指令的标识, 例如, B7 = l ;
B6: 状态指令的标识码, 例如, B6 = 0;
B5: 标识状态指令的参数状态, 带参数 /不带参数;
B4 ~ B。: 5位特征码, 标识参数的个数, 最多可携带 32个参数。 第 2个功能字节为状态指令的功能码, 共 256条状态指令。
( 2 )、 辅助字节
辅助字节为多个字节, 标识该状态指令的多个参数值, 每个参数占 2 个字 节。
状态指令还包括诊断指令, 用于向伺服驱动装置分配发送一系列的特定数 据, 以诊断联动表分配过程中的故障。
2 )、 开关指令与开关的实时控制
开关指令用于描述开关及其控制的参数。
所述开关如果携带需要实时控制的工艺参数, 本发明视为虚拟坐标轴。 所述开关如果不携带需要实时控制的工艺参数, 则属于常规的 PLC控制。 主轴转速控制可视为携带参数(转速) 的开关。
换刀指令属于常规的 PLC控制。 本发明将换刀指令视为一种开关指令。 作 为常规技术, 本发明不涉及换刀指令的具体控制过程。
开关指令包括功能字节、 辅助字节。
( 1 )、 功能字节
功能字节为 2个字节, 用于描述该开关指令的基本功能, 包括标识码与指 令码。
第 1个功能字节为开关指令的标识。
B7: 状态指令或开关指令的标识, 例如, B7 = 0;
B6: 开关指令的标识码, 例如, B6 = l ;
B5: 标识开关指令的参数状态, 带参数 /不带参数;
B4 ~ B。: 5位特征码, 标识参数的个数, 最多可携带 32个参数。 第 2个功能字节为开关指令的功能码, 共 256条开关指令。
( 2 )、 辅助字节
辅助字节为多个字节, 标识该开关指令的多个参数值, 每个参数占 2 个字 节。
对于状态指令与开关指令, 用户 (或开发商)可自行定义其辅助字节并通 过解释程序的重写自行定义其功能。 因而, 状态指令的指令格式与开关指令的 指令格式都是开放的, 支持用户 (或开发商) 的二次开发。
3 )、 轨迹指令与刀路曲线的实时控制 在 DRC控制中,对于一条刀路曲线,用一条轨迹指令来控制伺服驱动装置, 实现坐标轴联动。
在 DRC控制中, 需要实时控制的工艺参数由开关携带, 该开关称为虚拟坐 标轴, 工艺参数称为该虚拟坐标轴的坐标值。 因此, 在本发明中, 坐标轴包括 虚拟坐标轴。
轨迹指令为单字节指令, 只有一种格式, 其指令码为:
B7: 轨迹指令的标识, 例如, B7 = 0;
B6 ~ B。: 7位顺序码, 用于对轨迹指令编号。
顺序码在刀路曲线的轨迹指令与其所携带的联动表、 随动表之间建立—— 对应关系; 联动表用于控制相关坐标轴联动以产生所要求的合成位移; 随动表 用于控制所述合成位移之间的时间间隔。
在本发明中, 轨迹指令只有一种格式, 与刀路曲线中的曲线类型无关。 二、 DRC数控程序
在一次走刀过程中, 刀具中心的轨迹称为刀路曲线(Tool Path )。
按给定的数据格式, 一条刀路曲线的 L分割△ 、 Λ △ 、 ΔΑ,, ΔΒ,, AW^ △ 、 / ¾在存储空间的数据文件称之为 L分割的联动表。 按给定的数 据格式, 该刀路曲线的 T分割 ( i = l,..., n )在存储空间的数据文件称之为 T 分割的随动表。 L分割与 T分割称之为刀路曲线的关联数据流。
T分割中, △ 为无符号的 2字节二进制整数。
L分割中, 坐标值增量( ΔΧ^ ΔΥι )为原码表示的带符号的二进制整数, 最高位为符号位(+/- ), 对应坐标轴的正转 /反转。 特别是, 坐标值增量 △yi等) 的进给当量(纳米或微米)、 数据所占字节数都可以不同。
在工件的加工过程中, 数控设备只有辅助功能操作、 I/O装置的逻辑控制、 刀路曲线的实时控制等三种工作状态。 因此, 工件的加工过程一般可划分为辅 助过程、 换刀过程与走刀过程。 辅助过程涉及辅助功能操作, 换刀过程涉及刀 库控制, 走刀过程涉及刀路曲线的实时控制。
与这三种工作状态相对应, 数控系统有三类运动指令: 状态指令、 开关指 令、 轨迹指令。 根据加工工艺确定的顺序, 用户使用状态指令、 开关指令、 轨 迹指令来描述工件的整个加工过程。
这种由加工工艺确定了顺序的运动指令之集合就是该工件加工过程的数控 加工程序, 本发明称之为 DRC数控程序。
DRC数控程序是数字控制信息制造系统所制造的数字化产品, 从而将控制 信息的传统形态, 如图纸、 G代码程序等予以完全数字化。
DRC数控程序由运动指令构成, 用于控制工件的加工过程; 运动指令包括 状态指令、 开关指令、 轨迹指令; 状态指令用于操作辅助功能。
开关指令用于控制 I/O装置。
轨迹指令用于控制伺服驱动装置, 完成一条刀路曲线的走刀过程。
三、 DRC数控程序的结构
作为数字控制信息的数字化产品, DRC数控程序的结构也就是产品的数字 化结构。 DRC数控程序的结构决定了 DRC控制机的功能与结构, 反之, DRC 控制机的功能与结构又影响 DRC数控程序的结构。
工件的加工过程一般包括多个走刀过程。 每个走刀过程完成一条刀路曲线 的力口工。
一条刀路曲线通常由若干段曲线构成, 每段曲线的几何结构可能相同也可 能不相同, 合成每段曲线的坐标轴因之可能相同也可能不相同。
本发明不按照曲线的几何结构分段, 而是按联动的坐标轴分段。 每段曲线 中联动的坐标轴相同, 用一条轨迹指令来描述。 因而, 一条刀路曲线的加工达 程往往使用多条轨迹指令。
轨迹指令中的顺序码, 用于对轨迹指令按加工顺序编号。
在本发明中, 按照联动的坐标轴, 所述联动表划分为轴联动表。 例如, 关 于 ( i = Ι,. , ., η ) 的 X轴联动表, 关于△ (i = Ι,. , ., η ) 的 y轴联动表, 等 等。
轨迹指令与刀路曲线的轴联动表、 随动表相对应。
随动表中设置状态字, 用于标识该段曲线中联动的坐标轴。 状态字为一个 字节, 字节的位数可以为 32、 16、 8。 例如, 8位状态字可指定 8个联动的坐标 轴。 从低位到高位, 状态字的每位控制一个伺服驱动装置的使能状态及数据通 道。 例如, 状态字 " 11100000" 指定 X、 y、 Z 等轴的伺服驱动装置、 状态字
"00011000" 指定 A、 B等轴的伺服驱动装置。
将状态字的位数与个数为用户参数。 用户可通过状态指令设置状态字的位 数与字节数。
在每个轴联动表文件中设置特征表, 用于标识该段曲线中坐标轴的逻辑属 性; 坐标轴的逻辑属性包括进给当量(纳米、 微米等)、 数据所占的字节数, 还 包括电子齿轮传动比等伺服参数。 因此, 在一次加工过程中, 允许每个坐标轴 具有不同的进给当量、 不同的数据字节数、 不同的电子齿轮传动比, 以适应高 速高精度加工的需要。
为实现按名存取文件, 文件目录中包括文件名、 物理地址、 文件结构、 存 取控制等大量信息。
DRC数控程序、 轴联动表、 随动表均采用标准文件格式, 其编程接口的信 息之丰富、 信息量之大是 G代码程序编程接口难以实现的。 DRC数控程序为可执行文件; 轴联动表、 随动表为数据文件。 DRC数控程 序、 轴联动表、 随动表均采用诸如 FAT16、 FAT32之类的标准文件系统。
文件系统是在磁盘上组织文件的方法。 FAT ( File Allocation Table )是一种 广泛使用的标准化文件系统。 为了实现单片机系统的海量数据存储并支持单片 机系统与使用操作系统的计算机通过文件系统交换数据, 市场上已开发出一些 文件读取模块。 所述文件读取模块用于读取 FAT表、 FDT表、 BPB表等相关的 扇区地址和数据区的地址, 无须配置操作系统, 从而独立地完成文件管理的全 部功能: 打开、 新建或删除文件、 枚举和搜索文件、 支持长文件名等。
四、 控制流程
数据流关联控制面向过程, 按照制造数字控制信息的控制流程来配置控制 资源。
轴联动表分配过程的非实时化导致数字控制信息分配过程从数字控制信息 的实时控制过程中分离, 控制流程因之划分为数字控制信息生成过程、 数字控 制信息分配过程、 数字控制信息发送过程与数字控制信息执行过程等四个子过 程, 数字控制系统的体系结构因之解耦为数字控制信息生成部件、 数字控制信 息分配部件、 数字控制信息发送部件、 数字控制信息执行部件等四个功能部件。
从实时性来看, 控制流程可分为实时过程与非实时过程。 数字控制信息生 成过程与数字控制信息分配过程为非实时过程, 数字控制信息发送过程与数字 控制信息执行过程为实时过程。
1 )、 数字控制信息生成过程
数字控制信息生成过程就是制造关联数据流的过程, 即刀路曲线的联动表 与随动表的生成过程。 数字控制信息生成过程还包括 DRC数控程序的生成过程 即加工过程的编程过程。
数字控制信息生成过程是非实时过程。
数字控制信息生成部件生成 DRC数控程序, 包括以下内容:
( 1 )、 根据机械系统的运动学特征, 建立正交离散坐标系 /非正交离散坐标 系;
( 2 )、 根据机械系统的机械属性, 建立结构常数数据库用于存储所述机械 属性; 所述机械属性包括坐标轴的线位移误差、 角位移误差、 反向间隙等精细 结构常数, 以及坐标轴之间的不平行度、 不垂直度等坐标系参数;
( 3 )、 根据加工工艺, 进行刀路曲线规划, 完成刀具补偿与刀路路径规划, 生成刀路曲线文件;
( 4 )、 对刀路曲线文件中的每条刀路曲线进行离散几何规划与离散运动规 划, 生成该刀路曲线的轴联动表与随动表, 生成相应的轨迹指令及其轴联动表 与随动表; ( 5 )、 根据用户程序, 生成相应的状态指令;
( 6 )、根据用户程序,完成 I/O装置中的开关量控制,生成相应的开关指令;
( 7 )、 根据加工工艺, 链接状态指令、 开关指令、 轨迹指令, 生成 DRC数 控程序; 最后一条运动指令为结束加工的 "停机" 状态指令。
2 )、 数字控制信息分配过程
数字控制信息分配过程就是向伺服驱动装置分配轴联动表。 分配控制信息 在轴联动表的目录中。
通过将轴联动表事先分配给相应的伺服驱动装置, 从而将联动表的分配过 程非实时化。
3 )、 数字控制信息发送过程
数字控制信息发送过程与数字控制信息执行过程涉及 DRC数控程序的运 行过程。
DRC数控程序运行过程也就是运动指令的执行过程, 包括从 DRC数控程 序中读取运动指令与执行该运动指令的解译程序。
在取指过程中, 运动指令的功能字节写入运动指令寄存器, 分析处理其他 字节, 下一条运动指令的地址写入运动指令指针; 在执行过程中, 执行该运动 指令的解译程序, 完成所述运动指令指定的功能。
如果译码判定为状态指令, 则执行该状态指令的解译程序;
如果译码判定为开关指令, 则执行该开关指令的解译程序;
如果译码判定为轨迹指令, 则执行该轨迹指令的解译程序。
状态指令与开关指令执行过程属于辅助过程, 对实时性的要求不高, 属于 常规技术。
轨迹指令的执行过程就是走刀过程, 也就是一条刀路曲线的实时控制过程, 是数控系统的核心功能。
工件的加工过程一般包括多个走刀过程。 每个走刀过程完成一条刀路曲线 的加工。 用一条轨迹指令描述一条刀路曲线的走刀过程, 每条轨迹指令对应一 个轴联动表与一个随动表。 在 DRC数控程序中, 一般有 m条轨迹指令, 因而, 有 m个轴联动表与 m个随动表。
一条刀路曲线通常由若干段曲线构成, 每段曲线的几何结构可能不同。 在 发明中, 几何结构不同的曲线段视为不同的刀路曲线。 在这里, 几何结构不同 意味着联动的坐标轴不同。 例如, XY平面上由若干条圓弧与若干条直线构成的 刀路曲线, 由于联动的坐标轴相同, 故使用一条轨迹指令。
数字控制信息分配过程非实时化后, m条轨迹指令的轴联动表存储在伺服 驱动装置的轴联动表文件存储器, m条轨迹指令的随动表存储在实时控制模块 的随动表文件存储器。 因而, 必须为分离后的轴联动表与随动表建立联系。 每条轨迹指令携带顺序码, 标识该轨迹指令在 DRC数控程序中的位置。 轴 联动表中包括每条轨迹指令的轴联动表作为子文件, 其目录包括顺序码; 随动 表中包括每条轨迹指令的随动表作为子文件, 其目录也包括顺序码。 因而, 对 于所有的轨迹指令, 顺序码为每条轨迹指令与其轴联动表、 随动表建立了对应 关系。
这样一来, 数字控制信息分配过程非实时化后, 在刀路曲线的实时控制过 程中, 为控制相关坐标轴进行联动, 只须按照状态字指定的坐标轴向相关伺服 驱动装置单向发送同步脉冲。 为叙述简单起见, 将状态字控制下的这组同步脉 冲称之为联动命令。
因而, 数字控制信息分配过程非实时化后, 数字控制信息发送过程便简化 为按照控制节律 ( i = l,..., n ), 向轨迹指令的状态字指定的伺服驱动装置单 向发送联动命令。
4 )、 数字控制信息执行过程
数字控制信息执行过程就是伺服驱动装置跟随联动命令控制坐标轴进给产 生合成位移的过程。
伺服驱动装置接收联动命令后,根据 L指针从轴联动表中读取坐标值增量, 写入位置环, 驱动坐标轴进给产生合成位移; L指针加 1 , 直至 L指针等于轴联 动表的末地址。
五、 接口
数控系统的接口一般可分为内部接口与外部接口。
1 )、 外部接口
外部接口指的是网络接口。
所述网络接口用于车间管理网中不同数字控制系统之间交换信息, 一般可 采用工业以太网接口等, 属于常规技术。
2 )、 联动接口
数字控制系统的内部接口用于数字控制信息生成部件、 数字控制信息分配 部件、 数字控制信息发送部件、 数字控制信息执行部件等四个功能部件之间交 换信息。 本发明将内部接口划分为实时接口与非实时接口。
实时接口包括联动接口与 I/O接口。 I/O接口用于向 I/O装置中的开关发送 开关指令, 属于常规技术。
本发明将实时接口称之为联动接口, 用于向伺服驱动装置发送联动命令。 在 G代码程序中, 实时通信接口极为复杂, 没有可重构性, 只能耗费大量 计算资源配置不同的现场总线。这种状况导致中国国家标准 "GB/T 18759.2-2006· 机械电气设备 ·开放式数控系统《第 2部分体系结构"设置了 5.6款,要求支持各 类现场总线(例如 CAN、 Profibus, Sercos等)。 事实上, 现场总线的国际标准已有 12种之多, 厂商的企业标准更多。 不幸 的是, 多标准就意味着没有标准。
在基于 IEEE定义的现有开放式数控系统中,现场总线采用周期通信方式向 伺服驱动装置实时同步传输插补产生的坐标值增量, 通信周期成为系统参数, 实时同步机制、 数据表示的兼容性成为传输的关键。
在本发明中, 数字控制信息分配过程从数字控制信息的实时控制过程中分 离后, 轴联动表非实时地分配给伺服驱动装置, 实时通信过程退化为按照控制 节律, 向状态字指定的伺服驱动装置单向实时发送联动命令, 实时控制过程得 以高度简化, 联动接口得以高度简化。
在发送端, 联动接口类似按 ( i = l , . . . , n ) 的节律不断地单向传输状态字 的并行接口; 在接收端, 一个伺服驱动装置分别与联动接口的一个数据位连接, 类似一根中断控制线。
对于伺服驱动装置来说, 联动命令只是同步脉冲, 联动接口并非通信接口。 因而, 在本发明中, 不存在实时通信过程。
3 )、 非实时接口
非实时接口用于在辅助过程向伺服驱动装置非实时地分配轴联动表。
重要的是, 轴联动表的分配过程是非实时的, 不存在实时性问题因而无须 实时同步机制, 不存在周期通信因而通信周期不再是系统参数。 轴联动表为标 准文件, 不存在另外制定通信协议的问题。
因此,非实时接口可以是任何标准串行接口,包括现场总线、 RS232与 RS485 接口、 USB接口、 移动存储器、 无线接口等。
六、 编程接口
所谓编程接口指的是不同数控系统之间交换加工程序时, 加工程序之间的 程序接口。
在基于 IEEE定义的开放式现有数控系统中,采用 G代码标准作为数控加工 程序的编程接口。
与现有 G代码的数控加工程序不同, DRC数控程序的特征在于:
1)、 G代码程序面向对象, DRC数控程序面向控制流程
在基于 IEEE定义的现有开放式数控系统中,采用 G代码标准作为数控加工 程序的编程接口。 上世纪 50年代纸带作为输入的基本物理介质时, 为规范在纸 带上表示字符, 制定了纸带穿孔的编码标准, 即 G代码标准。
G代码程序是面向对象的。 在 G代码程序中, 用不同的插补指令来描述一 条刀路曲线中的不同曲线。 对于不同的曲线又必须使用不同的插补迭代算法来 实现不同的插补指令, 曲线的实时加工过程被插补迭代算法实时化, 从而导致 插补迭代算法成为面向对象的封闭的实时控制算法。 在 DRC数控程序中,轨迹指令面向刀路曲线的加工过程。 DRC数控程序是 面向控制流程的。
2 )、 控制信息的标准化
在插补迭代算法中, 每个坐标轴必须具有相同的逻辑属性。 一旦坐标坐标 轴的逻辑属性不同, 例如, 进给当量 (纳米、 微米等) 不同、 数据的字节数不 同等, 数控系统的功能与结构都要发生相应的变化, 从实时控制过程与实时通 信过程两方面制约了系统的开放性与可重构性。
G代码标准是信息技术起步阶段的原始产物, 受纸带的限制不可避免地存 在信息量过少的缺陷。 各个厂商因而对 G代码都进行了基本语义之外的扩张, 导致 G代码程序与相应硬件的依赖, 数控加工程序在不同的数控系统之间不具 有互换性, 造成各种数控系统互不兼容, 阻碍控制信息的交换与共享, 不具备 人机界面的一致性, 从编程接口方面制约了数字控制系统的开放性与可重构性。
轨迹指令的轴联动表与随动表携带加工刀路曲线所需要的全部数字控制信 息, 由数字控制信息生成部件非实时地制造出来, 允许每个坐标轴具有不同的 逻辑属性。
DRC数控程序、 轴联动表、 随动表等都以标准化文件的形态在系统中进行 传送, 也以文件的形态在不同的数控系统之间进行传送。 这些文件符合文件规 范, 采用诸如 FAT16、 FAT32等标准文件系统。 标准化文件成为数字控制信息的 载体, 与硬件平台无关, 与操作系统等软件平台无关, 具有广泛的平台无关性, 实现了数字控制信息的开放性。 标准化文件取代 G代码程序, 成为一种易于标 准化的编程接口, 有利于控制信息的标准化。
七、 刀路曲线的实时控制
轨迹指令的执行过程涉及数字控制信息发送部件与伺服驱动装置。 为简单 起见, 数字控制信息发送部件简称为实时控制模块, 包括联动坐标轴设置模块、 联动命令设置模块、 节律控制模块、 终点控制模块。
1、 实时控制模块发送联动命令
T指针: 用于读取随动表中的 ( i = l, · . ., !! )。
L指针: 用于读取轴联动表中的坐标值分量。
执行轨迹指令时, 轨迹指令执行模块设置运行标志, 启动实时控制模块。 实时控制模块按照控制节律主导着轨迹指令的执行过程, 坐标轴联动的实 时控制过程转化为下述过程:
步骤 1、 联动坐标轴设置步骤: 根据轨迹指令的顺序码, 联动坐标轴设置 模块将随动表的首地址写入 T指针, 从随动表中读取状态字并写入状态字寄存 器, 指定联动的坐标轴;
步骤 2、 联动命令设置步骤: 根据 T指针, 联动命令设置模块读取随动表 中的 ( i = l,..., n )并写入 T分割定时器;
步骤 3、 节律控制步骤: Τ分割定时器中的定时时间到, 节律控制模块启 动脉冲发生器输出一个脉冲, 通过联动接口向状态字寄存器指定的伺服驱动装 置发送联动命令;
步骤 4、 终点控制步骤: 终点控制模块控制轨迹指令的终点, 如果 Τ指针等 于随动表的末地址, 即到达轨迹指令的终点, 关闭运行标志; 否则, Τ指针指向 下一个 重复步骤 2至步骤 4;
轨迹指令执行模块查询实时控制模块的运行标志, 如果到达轨迹指令的终 点, 则执行下一条运动指令。
2、 伺服驱动装置控制坐标轴进给
伺服驱动装置接收轴联动表后, 将执行标志置 " 1 " ; 根据轨迹指令的轴联 动表的顺序码, 将轴联动表的首地址写入 L指针; 根据轴联动表文件中的特征 表, 设置坐标轴的逻辑属性。
伺服驱动装置接收联动命令后, 跟随联动命令, 轴联动表控制模块根据 L 指针从其轴联动表中读取坐标值增量, 写入位置环, 驱动坐标轴进给产生合成 位移; L指针加 1 , 直至 L指针等于轴联动表的末地址, 将执行标志置 "0" , 准 备执行下一条轨迹指令的轴联动表。
这样一来, 所谓刀路曲线的实时控制过程, 就是按照控制节律, 控制被状 态字指定的伺服驱动装置从轴联动表中读取坐标值增量并写入其位置环的过 程。 实时控制模块产生联动命令; 跟随联动命令, 伺服驱动装置不断地驱动坐 标轴进给产生合成位移。 如此周而复始, 直至 Τ指针到达随动表的末地址, 即 到达所述轨迹指令的终点。
例如, 对于 X、 y、 Z、 A、 B等 5轴联动, 状态字为 "11111000" , 其实时 控制过程就是, 实时控制模块不断地将随动表中的控制节律△ ( i = 1,..., n )写 入 T分割定时器, 产生联动命令并通过联动接口向 X、 y、 Z、 A、 B等伺服驱动 装置发送联动命令; X、 y、 Z、 A、 B 等伺服驱动装置则跟随联动命令, 各自 的轴联动表控制模块分别从各自的轴联动表中不断地同步读取△ 、 ΔΥι, ΔΖ ,,
/ 8 1并写入位置环, 驱动坐标轴进给产生合成位移。 如此周复始, 直至 所述刀路曲线的终点。
八、 体系结构的系统实现技术方案
在基于 IEEE定义的现有开放式数控系统中, 实时操作系统的插补周期与现 场总线的通信周期是两个系统时钟。 跟随插补周期与通信周期的节拍, 刀路曲 线的数字控制信息不断地生成、 分配、 发送、 执行, 从而以数字控制信息的实 时迭代与控制过程的实时迭代的方式周而复始。 在这种体系结构中, 刀路曲线 的实时控制过程既包括数字控制信息的实时迭代与控制过程的实时迭代, 又包 括实时通信过程, 涉及插补迭代算法的精度与速度、 刀路曲线的几何特征、 加 工过程的工艺特征、 机械系统的运动学 /动力学特征、 处理器的位数与运算速度 等硬件平台、 实时操作系统等软件平台等一系列复杂因素。
本技术方案按照数字控制信息的生成、 分配、 发送、 执行的控制流程配置 控制资源, 其中, 生成过程与分配过程为非实时过程, 发送过程与执行过程为 实时过程。
本技术方案将刀路曲线的实时控制过程简化为按照随动表中的控制节律△ t: ( i = l , . . ., n ), 通过联动接口向状态字指定的伺服驱动装置单向发送联动命令; 伺服驱动装置则跟随联动命令, 将所述轴联动表中的坐标值增量逐次写入位置 环, 驱动相应坐标轴联动产生合成位移。 因而, 数字控制信息执行过程解耦为 联动信息执行过程与位置信息执行过程。
本技术方案以随动表中的控制节律△ ( i = l , . . ., n )取代了插补周期, 取消 了实时操作系统对实时控制过程的控制权。 本技术方案以最简单的单向发送的 联动命令取代了极为复杂的实时通信, 取消了现埸总线对实时控制过程的控制 权。 因而, 上述技术方案彻底清除了操作系统与现埸总线对实时控制过程的制 约, 为可重构数字控制系统的系统实现技术指明了方向。
图 1 为基于控制流程的加工过程模型图, 其中实线表示实时过程, 虚线表 示非实时过程。 为清楚起见, 可在图 1 中增添伺服驱动装置中反馈信息的执行 过程, 如图 2。
与基于 IEEE定义的现有开放式数控系统的加工数据模型对比,上述加工过 程模型极为清楚地描述了开放式数控系统的体系结构, 揭示了在不同的控制流 程中合理配置控制资源的技术方案与关键技术。
为了更清楚地说明本技术方案,并与基于 IEEE定义的现有开放式数控系统 的系统实现技术进行对比, 举一个形象化的例子。
一个乐队演奏交响乐, 交响乐曲相当于刀路曲线, 各种乐器相当于坐标轴, 演员相当于伺服驱动装置, 实时操作系统则相当于乐队指挥。
在基于 IEEE定义的现有开放式数控系统中, 在交响乐曲的演奏过程 (刀路 曲线的加工过程) 中, 演员们 (伺服驱动装置) 与乐队指挥(实时操作系统) 事先不知道演奏什么曲调的交响乐曲 (刀路曲线), 乐队指挥必须在演奏现场将 交响乐曲按等长的时间片 (插补周期)分成若干曲段(实时插补计算出坐标值 增量), 并将每段曲子通过某种实时方式逐次告知每个演员 (伺服驱动装置通过 现场总线进行实时通信), 每个演员逐次实时记录每段曲子进行演奏。 这种模式 的极端复杂性是显而易见的。
在本技术方案中, 通过排练(离散几何规划与离散运动规划), 交响乐曲按 其内在的旋律(随动表中的不等长节律△ )划分为若干曲段(L分割 ), 并为每 个演员事先分配一个标记着曲段顺序的乐谱(分配轴联动表 ), 乐队指挥(实时 控制模块)在演奏现场只须按照随动表中的控制节律 ( i = 1,..., n ), 用指挥 棒(通过联动接口发送联动命令)告知每个演员, 每个演员则跟随指挥棒发出 的命令翻阅自己的乐谱(轴联动表) 进行演奏。 这种模式的高度简单性也是显 而易见的。
1、 若干定义
1 )、 数字控制信息生成部件
数字控制信息生成部件基于 PC, 包括状态指令生成模块、 开关指令生成模 块、 轨迹指令生成模块、 DRC数控程序生成模块。
2 )、 数字控制信息分配部件
数字控制信息分配过程就是将联动表中的坐标值增量分配给相关伺服驱动 装置, 例如, 将 XXi、 Δγι, △ 、 ΔΑι, 分配给 X、 y、 Z、 A、 B等 5个 坐标轴的伺服驱动装置。
数字控制信息分配部件包括轴联动表文件存储器、 轴联动表分配模块、 串 行接口。
3 )数字控制信息发送部件
数字控制信息发送部件用于按照控制节律向状态字指定的伺服驱动装置实 时发送联动命令。 为简便起见, 数字控制信息发送部件改称为实时控制模块。
实时控制模块涉及从文件存储器读取随动表中的 i = l, ..., η )与状态字。 随动表文件是由 PC的操作系统遵循诸如 FAT16、 FAT32文件系统规范写入随 动表文件存储器的标准文件。 在本技术方案中, 实时控制模块还包括随动表文 件存储器, 并配置了固化的文件读取模块, 用于读取 FAT表、 FDT表、 BPB表 等相关的扇区地址和数据区的地址, 从而与 PC的软硬件平台无关。
在多 CPU系统中, 通常采用双口 RAM作为 CPU之间的数据交换接口。 在 本技术方案中, 双口 RAM用于存储随动表文件, 实时控制模块通过双口 RAM 与 PC系统连接, 并读取 PC写入双口 RAM中的随动表中的 ( i = 1,..., n )与 状态字, 却与 PC的操作系统无关。
4 )、 数字控制信息执行部件
数字控制信息执行部件包括伺服驱动装置与 I/O装置。作为常规技术,本实 施方式不涉及用于控制 I/O装置的控制流。
数字控制信息执行过程就是伺服驱动装置将坐标值增量写入位置环, 驱动 坐标轴进给。
5 )、 运动控制接口
运动控制接口包括非实时接口、 联动接口。 所述非实时接口为各种标准串行接口, 例如现场总线、 RS232接口、 RS485 接口、 USB接口、 移动存储器、 无线接口等。
所述联动接口, 在发送端, 类似按 (i = l,..., n) 的节律不断地单向传输 状态字的并行接口, 包括状态字寄存器、 T指针、 T分割定时器、 脉冲发生器; 在接收端, 一个伺服驱动装置分别与联动接口的一个数据位连接, 类似一根中 断控制线。
6 )、 数控应用程序系统
数控应用程序系统包括 DRC数控程序、解译程序存储器、 DRC数控程序运 行模块。
DRC数控程序运行模块包括运动指令取指模块、 状态指令执行模块、 开关 指令执行模块、 轨迹指令执行模块。
运动指令取指模块用于将 DRC数控程序的首地址写入运动指令指针并读 取运动指令, 将运动指令的功能字节写入运动指令寄存器, 将下一条运动指令 的地址写入运动指令指针;所述运动指令指针用于指定下一条运动指令的地址; 如果运动指令为状态指令, 状态指令执行模块执行该状态指令的解译程序; 如果运动指令为开关指令, 开关指令执行模块执行该开关指令的解译程序; 如 果运动指令为轨迹指令, 轨迹指令执行模块执行该轨迹指令的解译程序。
2、 体系结构
图 3为一种可重构数控系统的体系结构示意图, 图 4至图 6为各部件的功 能模块图, 包括 PC系统 1、 解译程序存储器 2、 实时控制模块 3、 伺服驱动装 置 4、 I/O装置 5、 串行接口 6、 联动接口 7、 I/O接口 8。 PC系统 1通过串行接 口 6与伺服驱动装置 4连接, 通过 I/O接口 8与 I/O装置 5连接。 PC系统 1包 括数字控制信息生成部件、 数字控制信息分配部件、 数控应用程序系统, 通过 诸如 PCI之类的内部总线与实时控制模块连接, 通过串行接口、 I/O接口与数字 控制信息执行部件连接, 构成整体式的体系结构。
PC系统 1还可以通过双口 RAM与实时控制模块连接, 二者共享随动表。
PC系统 1用于生成控制工件加工过程的 DRC数控程序, 包括状态指令生 成模块 11、 开关指令生成模块 12、 轨迹指令生成模块 13、 DRC数控程序生成 模块 14、 轴联动表分配模块 15、 DRC数控程序运行模块 16。
上述模块的功能为:
状态指令生成模块 11用于生成控制辅助过程的状态指令。
开关指令生成模块 12用于生成控制 I/O装置的开关指令。
轨迹指令生成模块 13用于生成控制伺服驱动装置完成刀路曲线走刀过程的 轨迹指令。 轨迹指令生成模块包括离散几何规划模块与离散运动规划模块。 离 散几何规划模块用于生成存储有刀路曲线的 L分割的联动表; 所述 L分割用于 控制坐标轴联动产生合成位移; 所述联动表区分为各个轴的轴联动表; 所述轴 联动表用于存储相关坐标轴的 L分割分量, 控制该坐标轴产生轴位移。 离散运 动规划模块用于存储有刀路曲线的 T分割与状态字的随动表; 所述 T分割用于 控制所述轴位移之间的时间间隔; 所述状态字用于指定联动的坐标轴。
DRC数控程序生成模块 14, 用于根据加工工艺将状态指令、 开关指令、 轨 迹指令链接为 DRC数控程序。
轴联动表分配模块 15用于通过串行接口 6向伺服驱动装置 4分配轴联动表。
DRC数控程序运行模块 16用于运行 DRC数控程序, 执行状态指令控制辅 助过程、 执行开关指令通过 I/O接口 8控制 I/O装置 5、 执行轨迹指令启动实时 控制模块 3通过联动接口 7控制伺服驱动装置 4完成刀路曲线的加工过程。 包 括运动指令取指模块 161、 状态指令执行模块 162、 开关指令执行模块 163、 轨 迹指令执行模块 164。 运动指令取指模块 161用于将 DRC数控程序的地址写入 运动指令指针并读取运动指令, 将运动指令的功能字节写入运动指令寄存器, 将下一条运动指令的地址写入运动指令指针; 所述运动指令指针用于指定下一 条运动指令的地址。 如果所述运动指令为状态指令, 所述状态指令执行模块 162 用于执行该状态指令的解译程序; 如果所述运动指令为开关指令, 所述开关指 令执行模块 163 用于执行该开关指令的解译程序; 如果所述运动指令为轨迹指 令, 所述轨迹指令执行模块 164用于执行该轨迹指令的解释程序。
解译程序存储器 2用于存储上述状态指令、 开关指令、 轨迹指令的解译程 序。
实时控制模块 3通过内部总线与 PC系统 1连接,用于按照随动表中的控制 节律 ( i = 1,..., n ), 通过联动接口 7向伺服驱动装置 4发送联动命令; 所述 联动命令用于控制所述状态字指定的坐标轴之间的同步;
伺服驱动装置 4设有轴联动表初始化模块 41与轴联动表控制模块 42。接收 轴联动表后, 轴联动表初始化模块 41用于设置执行标志, 根据轨迹指令的顺序 码, 将轴联动表的首地址写入 L指针; 根据轴联动表文件中的特征表, 设置坐 标轴的逻辑属性。 跟随联动命令, 轴联动表控制模块 42根据 L指针从轴联动表 中读取该轴的坐标值增量并写入位置环,驱动坐标轴进给产生合成位移,直至 L 指针等于所述轴联动表的末地址, 关闭执行标志。
在本技术方案中, 轴联动表文件还包括特征表; 所述特征表用于标识该坐 标轴的逻辑属性; 所述逻辑属性包括进给当量、 数据的字节数、 电子齿轮传动 比。 在基于 IEEE定义的现有开放式数控系统中, 插补迭代算法要求联动的坐标 轴必须具有相同的逻辑属性。 一旦坐标坐标轴的逻辑属性不同, 例如, 进给当 量(纳米、 微米等) 不同、 数据的字节数不同等, 数控系统的功能与结构都要 发生相应的变化, 从实时控制过程与实时通信过程两方面制约了系统的开放性 与可重构性。 因而, 本技术方案的这一技术特征克服了上述缺陷。
在本技术方案中, 串行接口 6仅用于在非实时过程中伺服驱动装置 4传输 轴联动表, 因而, 其具体结构不受任任限制, 现场总线、 RS232接口、 RS485 接口、 USB接口或无线接口等均可以采用。 这就意味着, 不必为串行接口 6制 定标准, 换言之, 串行接口 6已经标准化了。 综上所述, 在本技术方案中, 可重构计算机数字控制系统的系统实现技术 方案具有下述技术特征:
控制流程划分为数字控制信息生成过程、 数字控制信息分配过程、 数字控 制信息发送过程与数字控制信息执行过程等四个子过程并配置相应的控制资 源;
数字控制信息生成过程与数字控制信息分配过程非实时化;
状态指令、 开关指令、 轨迹指令编写的 DRC数控程序作为编程接口; 轨迹指令只有一种格式, 与刀路曲线中的曲线类型无关。
轨迹指令与联动表、 随动表分离; 联动表中的每个坐标轴的轴联动表作为 独立的子文件, 在辅助过程中通过非实时串行接口分配给伺服驱动装置并存储 在其轴联动表存储器中; 随动表设置状态字, 用于指定联动的坐标轴, 状态字 的字节数为用户参数; 轴联动表文件设置特征表, 用于设置坐标轴的逻辑属性, 从而将坐标轴逻辑属性的处理问题前移至伺服驱动装置;
所述文件符合文件规范, 采用诸如 FAT16、 FAT32等标准文件系统。 标准化 文件成为数字控制信息的载体, 与硬件平台无关, 与操作系统等软件平台无关。
在体系结构方面, PC系统包括数字控制信息生成部件、 数字控制信息分配 部件、 数控应用程序系统; 实时控制模块作为硬盘之类的外部设备, 通过诸如 PCI之类的内部总线或通过双口 RAM共享随动表的形式与 PC系统连接。
PC系统将刀路曲线的实时控制过程的控制权移交给实时控制模块。 实时控 制模块则按照随动表中的控制节律△ (i = n ), 通过联动接口向状态字指 定的伺服驱动装置发送联动命令; 伺服驱动装置则跟随联动命令, 将所述轴联 动表中的坐标值增量逐次写入位置环, 驱动相应坐标轴联动产生合成位移。
本技术方案的的上述技术特征最大程度地简化了刀路曲线的实时控制方 法, 导致可重构计算机数字控制系统的体系结构与实时控制方法的重大变革, 并以极为简单的技术手段解决了可重构计算机数字控制系统的重构问题。 基于上述可重构计算机数字控制系统的数字控制方法, 包括下述步骤: 步骤 1、 DRC数控程序生成步骤: 用于 PC系统 1生成 DRC数控程序, 包 括下述步骤:
步骤 101、轨迹指令生成步骤: 轨迹指令生成模块生成控制伺服驱动装置完 成刀路曲线走刀过程的轨迹指令, 包括离散几何规划步骤与离散运动规划步骤; 离散几何规划步骤用于离散几何规划模块生成存储有刀路曲线的 L分割的联动 表; 所述 L分割用于控制坐标轴联动产生合成位移; 所述联动表区分为各个轴 的轴联动表, 用于存储各个坐标轴的 L分割分量, 控制该坐标轴产生轴位移; 离散运动规划步骤用于离散运动规划模块生成存储有刀路曲线的 T分割与状态 字的随动表; 所述 T分割用于控制所述轴位移之间的时间间隔; 所述状态字用 于指定联动的坐标轴。
步骤 102、状态指令生成步骤: 状态指令生成模块生成控制辅助过程的状态 指令。
步骤 103、 开关指令生成步骤: 开关指令生成模块生成控制 I/O装置的开关 指令。
步骤 104、 DRC数控程序生成步骤: DRC数控程序生成模块根据加工工艺 将所述状态指令、 所述开关指令、 所述轨迹指令链接为 DRC数控程序。
步骤 2、 轴联动表分配步骤: 轴联动表分配模块 15通过串行接口 6向伺服 驱动装置 4分配所述轴联动表。
步骤 3、 DRC数控程序运行步骤: DRC数控程序运行模块 16运行所述 DRC 数控程序, 包括下述步骤:
运动指令取指步骤: 运动指令取指模块 161将 DRC数控程序的首地址写 入运动指令指针并读取运动指令,将运动指令的功能字节写入运动指令寄存器, 将下一条运动指令的地址写入运动指令指针; 所述运动指令指针用于指定下一 条运动指令的地址;
状态指令执行步骤: 如果运动指令取指步骤中的运动指令为状态指令, 状 态指令执行模块 162则执行该状态指令的解译程序;
开关指令执行步骤: 如果运动指令取指步骤中的运动指令为开关指令, 开 关指令执行模块 163则执行该开关指令的解译程序;
轨迹指令执行步骤: 如果运动指令取指步骤中的运动指令为轨迹指令, 轨 迹指令执行模块 163则执行该轨迹指令的解译程序。
PC系统 1通过串行接口 6首先向伺服驱动装置 4分配轴联动表, 然后运行 DRC数控程序。 其中运行轨迹指令时, 轨迹指令执行模块 164启动实时控制模 块 3 , 将刀路曲线的实时控制过程的控制权移交给实时控制模块 3。
实时控制模块 3按照随动表中的控制节律 At i : ..., η ), 通过联动接口 7 向伺服驱动装置 4发送联动命令; 各个伺服驱动装置 4则跟随联动命令, 将各 自轴联动表中的坐标值增量逐次写入位置环, 驱动各自的坐标轴进给, 产生合 成位移。 如此周而复始, 直至 T指针等于随动表的末地址, 即到达该轨迹指令 的终点, 关闭运行标志, DRC数控程序运行模块执行下一条运动指令。
轨迹指令执行模块 164将控制权移交给实时控制模块 3之后, 处于查询状 态, 查询实时控制模块 3的运行状态。 如果运行标志关闭, 则执行下一条运动 指令, 直至执行停机指令, 结束工件的加工过程。
具体地, 刀路曲线的实时控制过程包括下述步骤:
步骤 a、 联动坐标轴设置步骤: 根据所述轨迹指令的顺序码, 联动坐标轴 设置模块 31将随动表的首地址写入 T指针, 从随动表中读取状态字并写入状 态字寄存器, 指定联动的坐标轴;
步骤 b、联动命令设置步骤: 根据 T指针, 联动命令设置模块 32读取随动 表中的 ( i = l,..., n ) 并写入 T分割定时器;
步骤 c、 节律控制步骤: T分割定时器中的定时时间到, 节律控制模块 33 启动脉冲发生器输出一个脉冲, 通过联动接口 7向状态字寄存器指定的伺服驱 动装置 4发送联动命令;
步骤 d、 联动表控制步骤: 跟随所述联动命令, 伺服驱动装置 4的轴联动 表控制模块 41根据 L指针从其轴联动表中读取坐标值增量, 写入位置环, 驱 动坐标轴进给产生合成位移;
步骤 e、 终点控制步骤: 终点控制模块 34控制轨迹指令的终点, 如果 T指 针等于随动表的末地址, 即到达所述轨迹指令的终点, 关闭运行标志; 否则, T 指针指向下一个 重复步骤 b至步骤 e。 对于机械系统的重构, 首先必须对机械系统进行运动规划。
CAD/CAM/CAE技术的广泛应用,特别是 CAE技术用计算机辅助求解复杂 机械系统的多维运动关系、 刚度、 稳定性、 动力学响应、 热变形等问题的分析 计算以及结构性能的优化设计, 已成为机械系统的运动规划和结构优化中必不 可少的数值计算工具。 因此, 在本实施方式中, 机械系统的运动规划视为常规 CAE技术。
本实施方式中的可重构计算机数字控制系统的重构涉及以下问题。
1 )、 离散坐标系的重构问题
机械系统重构后 , CAE对机械系统进行运动规划和结构优化 , 得到机械系 统的运动关系。 对重构后的机械系统, 必须重建离散坐标系。
2 )、 结构常数数据库的重构问题
机械系统重构后, 机械属性发生变化。 根据机械系统重构后的机械属性, 重构结构常数数据库; 所述机械属性包括坐标轴的线位移误差、 角位移误差、 反向间隙等精细结构常数, 以及坐标轴之间的不平行度、 不垂直度等坐标系参 数。
3 )、 状态指令与开关指令的重构问题
状态指令涉及辅助功能操作,开关指令涉及 I/O装置中的开关量控制,二者 都与机械系统的特定结构密不可分, 属于个性化功能。 机械系统重构后, 状态 指令与开关指令往往需要重构。
在本技术方案中, 状态指令与开关指令的定义及其解译运行都基于 PC, 是 开放的。 用户可自行定义其辅助字节中的参数值并通过重写解译程序实现自行 定义的功能。
在 PC中定义状态指令与开关指令, 编写其解译运行程序均在用户层进行, 与 PC的硬件平台、 软件平台无关, 是可重构的。
4 )、 实时控制过程的重构问题
数字控制系统的核心问题是实时控制刀路曲线。 相应于机械系统的重构, 刀路曲线的实时控制过程必然需要重构。
实时控制过程的重构涉及轨迹指令的重构与联动接口的重构。
基于 IEEE定义的现有开放式数控系统是面向对象而不是面向过程的。在插 补迭代控制方法中, 实时控制过程既是数字控制信息的迭代过程又是实时控制 过程的迭代过程。 因而, 实时控制过程与刀路曲线的几何特征、 加工过程的工 艺特征、 机械系统的运动学 /动力学特征等密不可分, 与 CPU的位数、 运算速度 等硬件平台密不可分, 与实时操作系统等软件平台密不可分, 与插补迭代算法 密不可分。 刀路曲线的实时控制过程无法开放, 不具有可重构性。 对于不同的 曲线类型, 必须定义专用的插补指令并配置特定的插补模块, 因而, G代码标 准下的插补指令是不可重构的。
本技术方案中的轨迹指令只有一种格式, 只与联动的坐标轴的个数有关, 与刀路曲线中的曲线类型无关。 不存在重构问题。
现有技术将 5 轴联动视为最尖端技术。 在本技术方案中, 联动的坐标轴由 随动表中的状态字指定, 状态字的位数与字节数则是用户参数。 一个 8位的状 态字可控制 8个坐标轴联动, 一个 16位的状态字可控制 16个坐标轴联动。 因 而, 对于绝大多数的用户来说, 不存在重构问题。 机械系统的轴数如果超过一 个状态字的位数, 在本技术方案中, 只须将状态字的用户参数设置为 2个或 2 个以上字节, 并配置 2个或 2个以上的联动接口, 因而也无须重构。 本技术方 案提出的轨迹指令的格式适用于任何机械系统, 具有广泛的通用性。
本技术方案将刀路曲线的实时控制过程简化为启动实时控制模块。 通过内 置固化的文件读取模块, 其运行与 PC的操作系统无关, 也无须配置任何嵌入式 实时操作系统。 本技术方案的联动接口并非实时通信接口, 联动命令只是同步脉冲。 在发 送端, 联动接口类似按 ( i = l , . . . , n )指定的节律不断地单向传输状态字的并 行接口; 在接收端, 一个伺服驱动装置分别与联动接口的一个数据位连接, 联 动接口类似一根中断控制线。 因而, 本技术方案提出的联动接口不存在重构问 题。
5 )、 非实时接口的重构问题
非实时接口是一个标准串行接口, 例如标准的 USB接口或 UART支持下的 其他标准串行接口, 属于常规技术。 对于机械系统的重构, 所述非实时接口无 须重构。
综上所述, 机械系统重构后, 对于本发明所提出的可重构计算机数字控制 系统, 轨迹指令与刀路曲线的实时控制过程、 联动接口与非实时接口均无须重 构, 需要重构的仅限于离散坐标系与结构常数数据库, 以及在 PC的用户层重新 定义状态指令与开关指令, 编写其解译运行程序。 因而, 本技术方案将可重构 计算机数字控制系统的重构方法转化为 PC中的常规技术手段,具有优良的可重 构性, 完全解决了可重构计算机数字控制系统的重构问题。
具体的, 本技术方案的可重构计算机数字控制系统的重构方法, 包括下述 步骤:
步骤 1、 重构离散坐标系: PC系统重构离散坐标系; 所述离散坐标系包括 正交离散坐标系与非正交离散坐标系。
步骤 2、 重构结构常数数据库: PC系统重构结构常数数据库; 所述结构常 数数据库存储坐标轴的精细结构常数与坐标系参数; 所述坐标轴的精细结构常 数包括线位移误差、 角位移误差、 反向间隙; 所述坐标系参数包括坐标轴之间 的不平行度、 不垂直度。
步骤 3、 重构状态指令: PC系统重构状态指令;
步骤 4、 重构开关指令: PC系统重构开关指令。 以上内容是结合具体的优选实施方式对可重构计算机数字控制系统所作的 进一步详细说明, 不能认定本发明的具体实施只局限于这些说明。 例如, PC系 统与实时控制模块的连接方式, 除本实施例中采用的具体方式外, 还可以采用 其他多种连接方式。 对于本发明所属技术领域的普通技术人员来说, 在不脱离 本发明构思的前提下, 还可以在其他方面做出若干简单推演或替换, 都应当视 为属于本发明的保护范围。

Claims

权利要求书
1、 一种可重构计算机数字控制系统, 其特征在于, 包括 PC系统、 解译程 序存储器、 实时控制模块、 伺服驱动装置、 I/O装置、 串行接口、 联动接口、 I/O 接口;
所述 PC系统通过串行接口与所述伺服驱动装置连接, 通过 I/O接口与所述 I/O装置连接, 用于生成控制工件加工过程的 DRC数控程序, 包括状态指令生 成模块、 开关指令生成模块、 轨迹指令生成模块、 DRC数控程序生成模块、 轴 联动表分配模块、 DRC数控程序运行模块;
所述状态指令生成模块用于生成控制辅助过程的状态指令;
所述开关指令生成模块用于生成控制 I/O装置的开关指令;
所述轨迹指令生成模块用于生成控制伺服驱动装置完成刀路曲线走刀过程 的轨迹指令;
所述 DRC数控程序生成模块, 用于根据加工工艺将状态指令、 开关指令、 轨迹指令链接为 DRC数控程序;
其中, 所述轨迹指令生成模块包括离散几何规划模块与离散运动规划模块; 所述离散几何规划模块用于生成存储有刀路曲线的 L分割的联动表;所述 L 分割用于控制坐标轴联动产生合成位移; 所述联动表区分为各个轴的轴联动表, 所述轴联动表用于存储相关坐标轴的 L分割分量, 控制该坐标轴产生轴位移; 所述离散运动规划模块用于存储有刀路曲线的 T分割与状态字的随动表; 所述 T分割用于控制所述轴位移之间的时间间隔; 所述状态字用于指定联动的 坐标轴;
所述轴联动表分配模块用于通过所述串行接口向所述伺服驱动装置分配所 述轴联动表;
所述 DRC数控程序运行模块用于运行所述 DRC数控程序, 执行状态指令 控制辅助过程、 执行开关指令通过所述 I/O接口控制 I/O装置、 执行轨迹指令启 动所述实时控制模块通过所述联动接口控制所述伺服驱动装置完成刀路曲线的 加工过程;
所述解译程序存储器用于存储所述状态指令、 所述开关指令、 所述轨迹指 令的解释程序;
所述实时控制模块用于按照所述随动表中的控制节律 ( i = 1,..., n ), 通 过所述联动接口向所述伺服驱动装置发送联动命令; 所述联动命令用于控制所 述状态字指定的坐标轴之间的同步;
所述伺服驱动装置设有轴联动表初始化模块与轴联动表控制模块; 所述轴联动表初始化模块用于设置执行标志, 根据所述轨迹指令的顺序码, 将所述轴联动表的地址写入 L指针; 跟随所述联动命令, 所述轴联动表控制模块根据 L指针从所述轴联动表中 读取该轴的坐标值增量并写入位置环, 驱动坐标轴进给产生合成位移。
2、 如权利要求 1所述的可重构计算机数字控制系统, 其特征还在于, 所述 状态字的字节数为用户参数。
3、 如权利要求 1所述的可重构计算机数字控制系统, 其特征还在于, 所述 轴联动表文件还包括特征表; 所述特征表用于标识该坐标轴的逻辑属性; 所述 逻辑属性包括进给当量、 数据的字节数、 电子齿轮传动比。
4、 如权利要求 1所述的可重构计算机数字控制系统, 其特征还在于, 所述 联动接口的每个数据位分别连接一个伺服驱动装置。
5、 如权利要求 1所述的可重构计算机数字控制系统, 其特征还在于, 所述 串行接口为现场总线、 RS232接口、 RS485接口、 USB接口或无线接口。
6、 如权利要求 1至 5中任意一项所述的可重构计算机数字控制系统, 其特 征还在于, 所述 DRC数控程序运行模块包括运动指令取指模块、 状态指令执行 模块、 开关指令执行模块、 轨迹指令执行模块;
所述运动指令取指模块用于将 DRC数控程序的地址写入运动指令指针并 读取运动指令, 将运动指令的功能字节写入运动指令寄存器, 将下一条运动指 令的地址写入运动指令指针; 所述运动指令指针用于指定下一条运动指令的地 址;
如果所述运动指令为状态指令, 所述状态指令执行模块用于执行该状态指 令的解释程序;
如果所述运动指令为开关指令, 所述开关指令执行模块用于执行该开关指 令的解释程序;
如果所述运动指令为轨迹指令, 所述轨迹指令执行模块用于执行该轨迹指 令的解释程序。
7、 如权利要求 6所述的可重构计算机数字控制系统, 其特征还在于, 所述 轨迹指令执行模块设置运行标志, 启动所述实时控制模块;
所述实时控制模块包括联动坐标轴设置模块、 联动命令设置模块、 节律控 制模块、 终点控制模块;
所述联动坐标轴设置模块用于将随动表的地址写入 T指针, 从所述随动表 中读取状态字并写入状态字寄存器, 指定联动的坐标轴;
所述联动命令设置模块用于读取所述随动表中的 ( i = Ι,. , ., η )并写入 Τ 分割定时器;
Τ分割定时器中的定时时间到, 所述节律控制模块用于启动脉冲发生器输 出一个脉冲, 通过联动接口向所述状态字寄存器指定的伺服驱动装置 4发送联 动命令; 所述终点控制模块用于控制所述轨迹指令的终点, 如果所述 T指针等于所 述随动表的末地址, 即到达所述轨迹指令的终点, 关闭运行标志; 否则, T指针 指向下一个 。
8、 如权利要求 7所述的可重构计算机数字控制系统, 其特征还在于, 所述 实时控制模块还包括随动表文件存储器与文件读取模块, 通过内部总线与所述 PC系统连接;
所述随动表文件存储器用于接收并存储所述随动表文件;
所述文件读取模块用于读取所述随动表文件。
9、如权利要求 7所述的可重构计算机数字控制系统, 其特征还在于, 所述 实时控制模块通过双口 RAM与 PC系统连接;
所述双口 RAM中存储所述随动表。
10、 一种可重构计算机数字控制系统的数字控制方法, 其特征在于, 包括 下述步骤:
步骤 1、 DRC数控程序生成步骤: 用于 PC系统生成 DRC数控程序, 包括 下述步骤:
步骤 101、轨迹指令生成步骤: 轨迹指令生成模块生成控制伺服驱动装置完 成刀路曲线走刀过程的轨迹指令, 包括离散几何规划步骤与离散运动规划步骤; 离散几何规划步骤用于离散几何规划模块生成存储有刀路曲线的 L分割的联动 表; 所述 L分割用于控制坐标轴联动产生合成位移; 所述联动表区分为各个轴 的轴联动表, 用于存储各个坐标轴的 L分割分量, 控制该坐标轴产生轴位移; 离散运动规划步骤用于离散运动规划模块生成存储有刀路曲线的 T分割与状态 字的随动表; 所述 T分割用于控制所述轴位移之间的时间间隔; 所述状态字用 于指定联动的坐标轴。
步骤 102、状态指令生成步骤: 状态指令生成模块生成控制辅助过程的状态 指令。
步骤 103、 开关指令生成步骤: 开关指令生成模块生成控制 I/O装置的开关 指令。
步骤 104、 DRC数控程序生成步骤: DRC数控程序生成模块根据加工工艺 将所述状态指令、 所述开关指令、 所述轨迹指令链接为 DRC数控程序。
步骤 2、 轴联动表分配步骤: 轴联动表分配模块通过串行接口向伺服驱动装 置分配所述轴联动表。
步骤 3、 DRC数控程序运行步骤: DRC数控程序运行模块运行所述 DRC 数控程序, 包括下述步骤:
运动指令取指步骤: 运动指令取指模块将 DRC数控程序的首地址写入运 动指令指针并读取运动指令, 将运动指令的功能字节写入运动指令寄存器, 将 下一条运动指令的地址写入运动指令指针; 所述运动指令指针用于指定下一条 运动指令的地址;
状态指令执行步骤: 如果运动指令取指步骤中的运动指令为状态指令, 状 态指令执行模块则执行该状态指令的解译程序;
开关指令执行步骤: 如果运动指令取指步骤中的运动指令为开关指令, 开 关指令执行模块则执行该开关指令的解译程序;
轨迹指令执行步骤: 如果运动指令取指步骤中的运动指令为轨迹指令, 轨 迹指令执行模块则执行该轨迹指令的解译程序。
11、如权利要求 10所述的可重构计算机数字控制系统的数字控制方法,其 特征还在于: 所述轨迹指令执行步骤设置运行标志,并启动下述实时控制步骤: 步骤 a、 联动坐标轴设置步骤: 根据所述轨迹指令的顺序码, 联动坐标轴 设置模块将随动表的首地址写入 T指针, 从随动表中读取状态字并写入状态字 寄存器, 指定联动的坐标轴;
步骤 b、 联动命令设置步骤: 根据 T指针, 联动命令设置模块读取随动表 中的 ( i = l,..., n )并写入 T分割定时器;
步骤 c、 节律控制步骤: T分割定时器中的定时时间到, 节律控制模块启 动脉冲发生器输出一个脉冲, 通过联动接口向状态字寄存器指定的伺服驱动装 置发送联动命令;
步骤 d、 联动表控制步骤: 跟随所述联动命令, 伺服驱动装置的轴联动表 控制模块根据 L指针从其轴联动表中读取坐标值增量, 写入位置环, 驱动坐标 轴进给产生合成位移;
步骤 e、 终点控制步骤: 终点控制模块控制轨迹指令的终点, 如果 T指针等 于随动表的末地址, 即到达所述轨迹指令的终点, 关闭运行标志; 否则, T指针 指向下一个 重复步骤 b至步骤 e。
12、 一种可重构计算机数字控制系统的重构方法, 其特征在于, 包括下述 步骤:
步骤 1、 重构离散坐标系: PC系统重构离散坐标系; 所述离散坐标系包括 正交离散坐标系与非正交离散坐标系。
步骤 2、 重构结构常数数据库: PC系统重构结构常数数据库; 所述结构常 数数据库存储坐标轴的精细结构常数与坐标系参数; 所述坐标轴的精细结构常 数包括线位移误差、 角位移误差、 反向间隙; 所述坐标系参数包括坐标轴之间 的不平行度、 不垂直度。
步骤 3、 重构状态指令: PC系统重构状态指令; 所述状态指令用于控制辅 助过程;
步骤 4、 重构开关指令: PC系统重构开关指令; 所述开关指令用于控制 I/O 装置。
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