JP2004110359A - Numerical control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make each axis control part to execute synchronizing interpolation control by using an absolute time. <P>SOLUTION: This personal computer 110 generates absolute time instruction data indicating the processing time of each axis by executing the operation of numerical control processing, and transmits generated absolute time instruction data to an LAN 115 being a network in an asynchronous communication system. A plurality of servo amplifiers 130-13n fetch the absolute time instruction data from the LAN 115, and mutually execute synchronizing interpolation control according to an incorporated internal timer indicating an absolute time. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a numerical control system.
[0002]
[Prior art]
In a conventional numerical control device, synchronous interpolation control performed between a plurality of axis control units (hereinafter, referred to as “servo amplifiers”) for controlling each axis is realized by a relative time command based on a synchronous signal. That is, in the conventional numerical controller, synchronization is performed between a plurality of servo amplifiers based on a synchronization signal having a certain period, and synchronous interpolation control is performed between the plurality of servo amplifiers based on command data such as position data and speed data. are doing.
[0003]
By the way, in the synchronous interpolation control method based on the relative time command based on the synchronous signal, a dedicated synchronous communication is required between the numerical controller and the servo amplifier. (Serial Realtime Communication System) and other communication standards have been formulated. However, since the communication performance is greatly related to the control performance, each numerical control device maker actually depends on its own dedicated communication system in order to obtain characteristics.
[0004]
In order to reduce the complexity of the cables concentrated on the numerical control unit, the numerical control unit, the screen control unit, and a plurality of servo amplifiers are connected via a general-purpose network, and the components are distributed. There has been proposed a numerical control system in which the control is performed (for example, see Patent Document 1). In the numerical control system disclosed in Patent Document 1, it is presumed that synchronous interpolation control between a plurality of servo amplifiers is realized by a relative time command based on a synchronous signal.
[0005]
In recent years, a numerical control system using a personal computer (hereinafter, referred to as a “PC”) has been proposed with the background of higher performance and lower price. That is, a numerical controller is mounted in an expansion slot of a personal computer, the numerical controller is connected to a storage device via a bus, and a plurality of servo amplifiers are connected to the numerical controller via a dedicated communication cable. A numerical control system has been proposed (for example, see Patent Documents 2 and 3).
[0006]
In the numerical control systems disclosed in Patent Documents 2 and 3, a movement command is calculated by a CPU of a personal computer from a processing program and processing data stored in a storage device, and the calculated movement command is transmitted to the numerical control device via a bus. Input is performed asynchronously without overflowing to a communication data buffer provided in an internal servo control unit. Synchronous interpolation control between a plurality of servo amplifiers is realized by a relative time command based on a synchronization signal.
[0007]
[Patent Document 1]
JP-A-9-73310 (paragraphs 0009 to 0012, FIG. 1).
[Patent Document 2]
WO 01/44882 pamphlet (pages 7 to 9, FIG. 1).
[Patent Document 3]
JP-A-9-146623 (paragraphs 0030 to 0033, FIG. 1).
[0008]
[Problems to be solved by the invention]
However, a synchronous interpolation control method using a relative time command based on a synchronous signal requires an OS, CPU, and synchronous communication interface dedicated to numerical control processing, so that it is expensive and has flexibility to meet various demands of users. There is a problem that lacks.
[0009]
The personal computer has an asynchronous communication function, and in recent years, it has become possible to perform high-speed asynchronous communication via a network such as a LAN. By simply transmitting the stored data to a plurality of servo amplifiers at high speed through a network such as a LAN using an asynchronous communication function, if synchronous interpolation control can be performed among the plurality of servo amplifiers, it is inexpensive and A flexible numerical control system can be built, but how to configure it is a problem.
[0010]
The present invention has been made in view of the above, and by enabling each axis control unit to perform synchronous interpolation control using absolute time, a numerical control system that is inexpensive and can flexibly respond to various requests of users. The purpose is to obtain.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a numerical control system according to the present invention performs an operation of a numerical control process to generate absolute time command data representing a processing time of each axis, and transmits the generated absolute time command data to an asynchronous communication. Numerical control processing means for transmitting data to the network of the system, and connected to the numerical control processing means via the network of the asynchronous communication system, mutually fetching the absolute time command data from the network and inter-communicating with each other in accordance with an internal timer indicating the absolute time. And a plurality of axis control means for performing synchronous interpolation control.
[0012]
According to the present invention, when the numerical control processing means performs an operation of the numerical control processing to generate absolute time command data representing a processing time of each axis, and transmits the generated absolute time command data to the network of the asynchronous communication system. A plurality of axis control means connected to the numerical control processing means via the network of the asynchronous communication system take in the absolute time command data from the network, and perform synchronous interpolation control between them in accordance with an internal timer indicating an absolute time incorporated therein. Is carried out.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of a numerical control system according to the present invention will be described below in detail with reference to the accompanying drawings.
[0014]
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a numerical control system according to Embodiment 1 of the present invention. The numerical control calculation means used in the present invention calculates the numerical control processing, specifically, calculates the movement amount of each axis from the analysis of the machining program, and generates absolute time command data representing the processing time of each axis. A function can be added, and an asynchronous communication function with a network such as a LAN is provided. This numerical control operation means can be realized using a computer device such as a workstation or a personal computer, for example. In this embodiment, a configuration example using a personal computer is shown from the viewpoint of inexpensive configuration.
[0015]
That is, in FIG. 1, a personal computer 110 as a computer device has a CPU, a memory such as a hard disk as an external storage device, and an asynchronous communication function with a network such as a LAN.
[0016]
The plurality of servo amplifiers 130 to 13n as the axis control units control the servo motors 140 to 14n of the corresponding axes. In the present embodiment, a synchronous interpolation control function using absolute time and a network such as a LAN are used. It has an asynchronous communication function.
[0017]
The switching hub 120 is a device that includes a switching circuit and is generally provided to enable dedicated communication between two devices in a network such as a LAN.
[0018]
The numerical control system shown in FIG. 1 has a configuration in which a personal computer 110 and a plurality of servo amplifiers 130 to 13n are connected via a switching hub 120 disposed on a LAN 115 as a network, for example. A high-level network 125 such as an intranet or the Internet can be connected to the switching hub 120. On the LAN 115, asynchronous communication using, for example, TCP / IP is performed.
[0019]
The servo amplifiers 130 to 13n are wired-OR connected by a hot line 180 for notifying an emergency stop or the like. The hot line 180 is also wired OR-connected with the emergency stop switch 190. In this embodiment, the hot line 180 shows a case where a dedicated communication cable is used. However, the hot line 180 may be configured with a wireless line using a dedicated frequency.
[0020]
FIG. 2 is a block diagram showing a configuration example of the personal computer shown in FIG. In FIG. 2, a personal computer 110 has a personal computer CPU 210 added with a function of executing processing from analysis of a machining program to calculation of a movement amount of each axis, and a main memory 220 used by the personal computer CPU 210 to implement the functions of the personal computer 110. , An external storage device 230 such as a hard disk in which machining programs and machining data (three-dimensional CAD data) are also stored, an internal timer 240 indicating an absolute time, a signal exchange with a servo amplifier via the LAN 115, and a servo on the LAN 115. The configuration is such that a LAN interface circuit 250 for transmitting amplifier communication data 290 is connected via an internal bus 260.
[0021]
A communication data buffer memory 255 for temporarily storing communication data is connected to the LAN interface circuit 250. A PC card interface circuit 270 is connected to the internal bus 260 so that a card type NC 280, which is a numerical controller equipped with a dedicated CPU, can be connected by plug and play.
[0022]
As shown in FIG. 1, the hotline 180 may be connected to the personal computer 110 in some cases. However, since the hot line 180 is used for notifying an emergency stop or the like among the servo amplifiers 130 to 13n, and the personal computer 110 can communicate with the servo amplifier via the LAN 115, the hot line 180 is used in FIG. Is omitted from the drawing.
[0023]
FIG. 3 is a block diagram showing a configuration example of the servo amplifier shown in FIG. The servo amplifiers 130 to 13n all have the same configuration. FIG. 3 illustrates the servo amplifier 130 as a representative.
[0024]
3, a servo amplifier 130 exchanges signals via a LAN 115 with a servo amplifier CPU 310 realizing a function as an axis control unit, a main memory 320 used by the servo amplifier CPU 310, and transmits servo amplifier communication data 290 from the LAN 115. The configuration is such that a LAN interface circuit 330 for taking in and the like, a servo motor rotation control circuit 340 for rotating and driving the servo motor 140, and an internal timer 350 indicating an absolute time are connected via an internal bus 370. A communication data buffer memory 335 for temporarily storing communication data is connected to the LAN interface circuit 330.
[0025]
Further, an I / O interface circuit 360 for transmitting and receiving signals via the hot line 180 is provided. As shown in FIG. 3, the signal (internal signal) of the hot line 180 includes an emergency stop signal 181, a synchronization time reset signal 182, and a synchronization time correction signal 183. These are transmitted through independent signal lines.
[0026]
The I / O interface circuit 360 directly exchanges signals with the servo amplifier CPU 310 and the internal timer 350. That is, the failure occurrence notification signal EMG and the interrupt signal INTERRUPT are exchanged between the I / O interface circuit 360 and the servo amplifier CPU 310. Further, a reset signal RESET, a synchronization time correction signal CORRECT, and a timer signal TIMER are exchanged between the I / O interface circuit 360 and the internal timer 350.
[0027]
Here, in the present invention, since the synchronous interpolation control is performed between the servo amplifiers using the absolute time command data, the internal timer 350 of each servo amplifier needs to be accurately adjusted. As the method, there are the following methods (1) to (4).
[0028]
(1) A high-precision timer is used as the internal timer 350 of each servo amplifier. For example, it is preferable to use an atomic clock having an accuracy of about 10-13 to 10-16 or more. However, accurate timers, such as atomic clocks, are expensive and the equipment is large, making it difficult to obtain at present. Therefore, the absolute time is secured by performing the synchronization deviation correction using a normal timer, and the time of the internal timer 350 of each servo amplifier is adjusted by the methods (2) and (3).
[0029]
(2) For example, the internal timer 350 of each servo amplifier is set from the personal computer 110 by year / month / day / hour / minute through asynchronous communication, and is set to seconds (s) / milliseconds (ms) / microseconds ( μs) and nanoseconds (ns) are set as follows using the emergency stop signal 181 provided for the hot line 180 for emergency use or the synchronization time reset signal 182 provided for exclusive use.
[0030]
That is, if the servo amplifier CPU 310 of one of the servo amplifiers 130 to 13n generates the failure occurrence notification signal EMG before the processing is started, the emergency stop signal 181 from the I / O interface circuit 360 of that servo amplifier becomes hot. The signal is sent out to the line 180, and all other servo amplifiers are notified. Upon receiving the emergency stop signal 181 from the hot line 180, the I / O interface circuits 360 of all other servo amplifiers output a reset signal RESET to the internal timer 350. As a result, absolute time adjustment is performed in all the other servo amplifiers.
[0031]
Alternatively, before the start of machining, a synchronization time reset signal 182 is sent from one of the servo amplifiers 130 to 13n to the hot line 180 to reset all the servo amplifiers. When receiving the synchronization time reset signal 182 from the hot line 180, the I / O interface circuits 360 of all the servo amplifiers output a reset signal RESET to the internal timer 350. As a result, absolute time adjustment is performed in all the other servo amplifiers. The synchronization time reset signal 182 may be sent from the personal computer 110 to the hotline 180.
[0032]
(3) Alternatively, the setting of the internal timer 350 of each servo amplifier is obtained from the radio clock or the GPS satellite by the long wave JJY (standard frequency station) linked to the atomic clock for the year / month / date / hour / minute / second. The time is set in seconds using the absolute time, and the seconds (s), milliseconds (ms), microseconds (μs), nanoseconds (ns), etc. are provided on the hot line 180 as described in (2). The setting is made using the emergency stop signal 181 or the synchronization time reset signal 182.
[0033]
(4) As a special case, when a servo amplifier CPU 310 of a certain servo amplifier generates a failure occurrence notification signal EMG, an emergency stop signal 181 is sent from the I / O interface circuit 360 of the servo amplifier to the hot line 180, and another Notified to all servo amplifiers. When receiving the emergency stop signal 181 from the hot line 180, the I / O interface circuits 360 of all the other servo amplifiers generate an interrupt signal INTERRUPT for the servo amplifier CPU 310 and a reset signal for the internal timer 350. RESET is output. As a result, absolute time adjustment is performed in all other healthy servo amplifiers.
[0034]
Next, a description will be given of a method of correcting the synchronization deviation of the absolute time in the internal timer 350 of each servo amplifier. Normal timers have an error of several seconds per month. For example, in the case of a timer including an error of ± 10 seconds per month, an error of approximately ± 13.89 ms occurs during processing for one hour (= 10 seconds ÷ 30 days ÷ 24 hours).
[0035]
This absolute time synchronization deviation correction is performed using a synchronization time correction signal 183 provided on the hot line 180. That is, when one of the servo amplifiers 130 to 13n outputs a timer signal TIMER, which is a digital signal having a period of 1 ms, from the internal timer 350 of the device to the I / O interface circuit 360, the I / O interface circuit 360 issues a hot line. A synchronization time correction signal 183 is sent to 180. In all other servo amplifiers, when the I / O interface circuit 360 takes in the synchronization time correction signal 183 from the hot line 180, it outputs a synchronization time correction signal CORRECT to the internal timer 350. As a result, in all the other servo amplifiers, the synchronization deviation of the absolute time is corrected.
[0036]
If the error of the internal timer 350 between the servo amplifiers is corrected in units of one second using the synchronization time correction signal 183, if the timer includes an error of ± 10 seconds per month, approximately ± 3. Since an error of 86 μs is corrected every time, the error remains about ± 3.86 μs even after processing for one hour. Naturally, if the correction cycle is set to 1 ms or less, the range of the error can be further improved. It goes without saying that the synchronization time correction signal 183 may be sent from the personal computer 110 to the hotline 180.
[0037]
Next, the operation of the personal computer 110 will be described with reference to FIGS. FIG. 4 is a flowchart illustrating the operation of the personal computer shown in FIG. FIG. 5 is a diagram illustrating a coordinate system in which an X axis and a Y axis are used as synchronous interpolation control axes.
[0038]
In FIG. 5, coordinate positions L1 (X1, Y1) and L2 (X2, Y2) are absolute positions. The moving distance L from the absolute position L1 (X1, Y1) to the absolute position L2 (X2, Y2) is moved at the moving speed V. The coordinate position ΔLm (ΔXm, ΔYm) based on the X-axis movement distance ΔXm per unit time Δt and the X-axis movement distance ΔYm per unit time Δt is the movement per unit time Δt from the absolute position L1 (X1, Y1). This is the absolute position per unit time Δt obtained as the distance ΔLm. The distance Ln from the absolute position ΔLm (ΔXm, ΔYm) per unit time Δt to the absolute position L2 (X2, Y2) is the remaining distance.
[0039]
In FIG. 4, a machining program or three-dimensional CAD data stored in advance in the external storage device 230 is read (step ST1), and analysis data ｛absolute position L1 (X1, Y1), L2 (X2, Y2), moving speed V, moving distance L, etc. are obtained (step ST2).
[0040]
Next, a minute line segment calculation process is executed using the obtained analysis data {absolute position L1 (X1, Y1), L2 (X2, Y2), moving speed V, moving distance L, etc.}, and the per unit time Δt The movement amount ΔLm is obtained (step ST3), and the axis coordinate division calculation process is further executed to obtain the movement distances ΔXm and ΔYm per unit time Δt in each axis direction, thereby dividing the movement amount into each coordinate (step ST4). ). Then, the moving distance ΔLm per unit time is obtained from the moving distances ΔXm and ΔYm per unit time divided into the respective axes, the remaining distance Ln is obtained, and it is determined whether the remaining distance Ln ≦ the moving distance ΔLm. (Step ST5) Until the remaining distance Ln ≦ the moving distance ΔLm (Step ST5: No), the processing of Step ST3 and Step ST4 is repeated.
[0041]
When the remaining distance Ln ≦ the moving distance ΔLm is satisfied (step ST5: Yes), the interpolated absolute position command data {data ID, control axis number, position command, time command} is obtained, and is temporarily stored in the external storage device 230. (Step ST6). This storage operation in the external storage device 230 is repeated until a predetermined amount can be stored in the external storage device 230 (step ST7).
[0042]
When a certain amount of absolute position command data {data ID, control axis number, position command, time command} can be stored in the external storage device 230 (step ST7: Yes), the absolute position command is read from the external storage device 230. The data is temporarily stored in the communication data buffer memory 255 (step ST8), and transmitted to the servo amplifiers 130 to 13n via the LAN 115 at an appropriate timing (step ST9).
[0043]
Next, the operation of each servo amplifier will be described with reference to FIG. FIG. 6 is a flowchart illustrating the operation of the servo amplifier shown in FIG. In FIG. 6, when the absolute position command data {data IDn, control axis number AX1n, absolute time command T, position command F} interpolated from the LAN is received (step ST21), it is temporarily stored in the communication data buffer memory 335. (Step ST22). The storage operation in the communication data buffer memory 335 is repeated until a predetermined amount can be accumulated in the communication data buffer memory 335 (step ST23).
[0044]
When a certain amount is accumulated in the communication data buffer memory 335 (step ST23: Yes), all the absolute position command data are read from the communication data buffer memory 335, and the communication data buffer memory 335 is received so that the next communication data can be received. Is erased (step ST24).
[0045]
Next, in the asynchronous communication, the order of the received data and the like may change. Therefore, the absolute position command data is rearranged based on the data IDn of the absolute position command data, the control axis number AX1n, and the absolute time command T, and the main memory 320 (step ST25). In step ST25, when a communication packet that could not be received occurs for some reason, data interpolation (linear interpolation, spline interpolation, etc.) is performed from the data before and after the packet and written to the main memory. Is
[0046]
Next, the absolute position command data is read from the main memory 320 (step ST26), and a comparison is made between the absolute time command data T and the real time data t of the internal timer 350 (step ST27). It is determined whether or not it is not (Step ST28), and the processing of Step ST26 and Step ST27 is repeated until T = t (Step ST28: No).
[0047]
Then, when T = t (step ST28: Yes), the rotation speed of the servo motor is calculated based on the absolute position command data (step ST29), and the drive current of the servo motor is controlled to rotate the servo motor. (Step ST30). Thus, the servo motor can be rotated while synchronizing the plurality of servo amplifiers 130 to 13n.
[0048]
As described above, according to this embodiment, the personal computer 110 transmits the absolute time command to the plurality of servo amplifiers 130 to 13n by asynchronous communication via the LAN 115, so that the plurality of servo amplifiers 130 to 13n Synchronous interpolation control can be performed.
[0049]
Then, from the upper network 125 connected to the switching hub 120, the three-dimensional CAD data in step 1 in FIG. 4, the analysis data in step ST2, the moving amount ΔLm in step ST3, and the moving distance ΔXm in step ST4 in FIG. , ΔYm, and the absolute position command data in step ST6 can be downloaded, so that numerical control data can be transmitted directly from an external host computer or the like via the Internet instead of the personal computer 110, and processing by synchronous interpolation control can be performed. Will be possible.
[0050]
In addition, since the hot line 180 is provided between the servo amplifiers 130 to 13n for safety reasons, the servo amplifier that has detected an abnormality sends an emergency stop signal 181 on the hot line 180, so that the servo amplifier immediately transmits to another servo amplifier. The occurrence of an abnormality is notified, and a stop operation or the like can be performed. The emergency stop can also be performed by manually operating the emergency stop switch 190 connected to the hot line 180.
[0051]
It should be noted that the stop information can be notified to the personal computer 110 by a method using the same hot line 180 as described above or via the LAN 115. The personal computer 110 performs processing such as displaying an alarm on the display screen. However, this measure is limited to a case where the personal computer 110 is not directly connected to a machine (for example, a motor or an I / O device that controls in real time) that stops the operation quickly for safety.
[0052]
When the emergency stop signal 181 of the hot line 180 is used, for example, synchronous interpolation control is performed between the plurality of servo amplifiers 130 to 13n, and when processing is in progress, data is no longer sent or It is possible that absolute time command data older than the absolute time indicated by the timer 350 has been transmitted. For example, when there are a plurality of machine tools having the numerical control system having the configuration shown in FIG. 1 and all the systems are connected via the upper network 125, the upper network 125 becomes congested for some reason. This can occur when communication delay occurs.
[0053]
In such a case, if data is no longer sent during the synchronous interpolation control execution process (during processing), the plurality of servo amplifiers 130 to 13n determine that communication has been disconnected for some reason. If the absolute time command data older than the absolute time indicated by 350 is transmitted, it is determined that it is late. Then, the servo amplifier that has detected the abnormality stops the corresponding servo motor immediately, notifies the other servo amplifiers using the emergency stop signal 181 of the hot line 180, and can stop those servo motors.
[0054]
On the other hand, in this embodiment, the occurrence of the above-described situation of stopping the servomotor can be avoided by, for example, taking the following measures. That is, a general switching hub capable of providing a communication data buffer memory with a sufficient capacity on the servo amplifier side or a higher-speed LAN (for example, 100 Mbps, 1 Gbps, etc.) and capable of dedicated communication between two devices. If you use a connection method that closes communication within one numerical control system inside the machine tool using, the communication inside the system will not be crowded, so do not perform stop operation due to reasons such as communication not being in time Can be
[0055]
Next, communication data and the like transmitted from the personal computer 110 to the servo amplifiers 130 to 13n as described above will be described with reference to FIGS. FIG. 7 is a diagram showing a configuration example of communication data from the personal computer shown in FIG. 1 to the servo amplifier. FIG. 8 is a diagram in which the time of the communication interval between the personal computer and the servo amplifier shown in FIG. 1 is calculated as a relationship between the communication speed of the LAN and the interpolation cycle. FIG. 9 is a diagram in which the amount of servo communication data stored in the external storage device of the personal computer shown in FIG. 1 is calculated as a relationship between the interpolation cycle and the processing time.
[0056]
In FIG. 7, "effective bit width", "data effective range", and "use bit width" are defined for each type of data. Data for controlling one axis is composed of 768 bits. The total of eight axes is 768 bytes.
[0057]
The breakdown (data type) includes a data ID, an axis control number, a time command (absolute time) that can represent time from the date to nanosecond (ns), and a position (absolute time) from the origin of the machine coordinate system. The position includes a position command (absolute position command) capable of expressing the position from a unit of meter (m) to a unit of nanometer (nm), and others (set values of control commands and servo parameters).
[0058]
In FIG. 7, the reason why the time command is given is that, in this embodiment, unlike the conventional synchronous communication method in which time-series continuous interpolation data is sequentially transmitted at regular intervals, the communication cycle is set in the same manner as the interpolation cycle. This is because an asynchronous communication method that is not guaranteed to be kept constant is employed.
[0059]
In other words, in this embodiment, a commonly used communication means such as a LAN having a low cost and high data transfer capability is used, and the time for executing the interpolation data is instructed to a plurality of servo amplifiers in absolute time. This is because the interpolation process is executed based on the absolute time command data using the internal timer indicating the absolute time.
[0060]
FIG. 8 shows the communication interval between the personal computer and the servo amplifier when the LAN communication speed and the interpolation period Δt are changed. In FIG. 8, the types of LAN include 10BASE-T (data transfer speed of 10 Mbit / sec, memory capacity required for servo amplifier of 1250 kByte / sec) and 100BASE-TX (data transfer speed of 100 Mbit / sec, required for servo amplifier). A memory capacity of 12.50 MByte / sec and a 1000 BASE (a data transfer speed of 1000 Mbit / sec, a memory capacity of 125 MByte / sec necessary for the servo amplifier) are shown.
[0061]
The interpolation cycle Δt, the data capacity (8 axes), and the data transfer rate are (3,5 ms, 768 Byte, 214.29 kByte), (0.35 ms, 768 Byte, 2.09 MByte), and (0.035 ms, 768 Byte, 20.93 MByte). However, the transfer efficiency by LAN is assumed to be 100%.
[0062]
In the conventional synchronous system, the communication cycle and the interpolation cycle are the same. For example, if one communication data is 768 bytes (for eight axes) in the conventional synchronous system with a communication cycle Δt = 3.5 ms, the communication cycle is the same. In order to obtain the data of the interpolation period Δt, in the method according to the present embodiment, when 10BASE-T is used, communication of about 1 second in about 5.97 seconds may be established between the personal computer and the servo amplifier. Will be.
[0063]
In this case, the servo amplifier only needs to have a memory capacity (= 1.25 Mbytes) for data transfer for at least one second. This memory capacity can be realized by using not only the communication data buffer memory 335 but also the main memory 320.
[0064]
Since the transfer efficiency of the LAN depends on the number of connected devices (personal computers, servo amplifiers, and the like), when a higher-speed communication can be performed using a 100BASE-TX or 1000BASE LAN, the servo amplifier is used. It is possible to respond flexibly by increasing the memory capacity on the side.
[0065]
In addition, even if the interpolation cycle Δt is shorter than 0.35 ms or 0.035 ms in order to perform high-precision machining such as nanometer interpolation, the LAN speed can be increased without changing the system configuration. It can respond flexibly by increasing the capacity of the servo amplifier memory. FIG. 8 shows that such a judgment material is provided.
[0066]
Next, in FIG. 9, as the accumulated data amount of the interpolated absolute time command data accumulated in the external storage device 230 of the personal computer 110, a data amount of Δt time (eight axes) and a data amount of one second (eight axes) are shown. The data amount for one hour (8 axes) and the data amount for one day (8 axes) are shown. The interpolation periods Δt are shown as 3.5 ms, 0.35 ms and 0.035 ms.
[0067]
For example, when the absolute time command data for about 1 hour is accumulated at a time, a storage capacity of about 753.35 MByte is required for an interpolation cycle of 3.5 ms. However, if a hard disk or the like is used for the external storage device 230, the system can be configured at low cost. Further, when processing for one hour or more is performed with a capacity of 753.35 MBytes, it can be easily realized by deleting transmitted data and sequentially writing data exceeding one hour there. In this case, a point to be noted is that the minimum necessary data determined in relation to the data generation time of the personal computer CPU 210 is calculated and stored in the external storage device 230 in advance so that the transmission data is not lost.
[0068]
As described above, according to this embodiment, unlike the conventional numerical control method in which the dedicated CPU is used for the dedicated OS to perform the interpolation processing, all the interpolation processing can be calculated by the personal computer 110. Therefore, the program that executes each process can be constructed in a development environment that is easy for the user to customize, and the user can implement his or her own application.
[0069]
In particular, in FIG. 4, by customizing the analysis data in step ST2, the movement amount ΔLm in step ST3, the movement distances ΔXm and ΔYm in step ST4, and the absolute position command data in step ST6, a user-specific special Special processing can be realized by performing interpolation control.
[0070]
Further, in FIG. 4, the communication data transmitted from the personal computer 110 to the servo amplifiers 130 to 13n is the absolute position command data divided for each axis. However, since the asynchronous communication is performed using the absolute time command data, the transmission is performed. If absolute time command data for designating the time to execute the processing is added to the data, the data to be transmitted to the servo amplifier includes the three-dimensional CAD data in step ST1, the analysis data in step ST2, and the movement amount ΔLm in step ST3. , And the moving distances ΔXm and ΔYm in step ST4 may be used. The processing start time is added to the three-dimensional CAD data in step ST1, and a time obtained by adding the processing time to the processing start time is added to the remaining three data.
[0071]
When data in each processing stage is transmitted as described above, the remaining processes after the transmission data are calculated by the servo amplifier CPU 310 on the servo amplifier side. If the number of remaining processes increases, the load on the personal computer CPU 210 on the personal computer side decreases, and the calculation load on the servo amplifier side increases accordingly. Therefore, an expensive and high-speed CPU and a large-capacity memory are required on the servo amplifier side. Here, since a series of processes in steps ST1 to ST4 can all be performed asynchronously, an algorithm is used that can obtain the same calculation result regardless of whether the process is performed on the personal computer side or the servo amplifier side.
[0072]
By the way, it is difficult to immediately respond to a speed change during manual machining, such as a setup operation of a machine tool, unless all the arithmetic processing of steps ST1 to ST4 can be performed in real time.
[0073]
Therefore, during setup or the like, a PC card type card-type NC 280 connectable by plug-and-play as shown in FIG. 2 is connected to the PC card interface circuit 270 of the personal computer 110, and steps ST1 to ST1 are performed on the card-type NC 280. The series of processes in ST4 is performed in real time so that manual numerical control that requires responsiveness can be performed.
[0074]
In this case, since a LAN is used as the communication means, responsiveness is reduced if the capacity of the communication data buffer memory 255 is large. Therefore, it is preferable to sufficiently execute a simulation such as a tool path check and a machining check on a personal computer before machining to prevent data change during machining by manual operation.
[0075]
Further, in actual machining other than the setup, or when executing a machining program whose operation has been confirmed, the card NC may be removed from the personal computer, and the personal computer 110 may perform the arithmetic processing of steps ST1 to ST4.
[0076]
Embodiment 2 FIG.
FIG. 10 is a block diagram showing a configuration of a servo amplifier in a numerical control system according to Embodiment 2 of the present invention. FIG. 11 is a block diagram showing details of the A / D interface circuit 1060 shown in FIG. In FIG. 10, the same or equivalent components in the configuration shown in FIG. 3 are denoted by the same reference numerals. Here, a description will be given focusing on a portion relating to the second embodiment.
[0077]
That is, in servo amplifier 1030 shown in FIG. 10, A / D interface circuit 1060 is provided instead of I / O interface circuit 360 in servo amplifier 130 shown in FIG. Then, the signal of the hot line 180 input / output to / from the A / D interface circuit 1060 is only one of the emergency stop signal / synchronization time correction signal 184 which also serves as the emergency stop signal 181 and the synchronization time correction signal 183.
[0078]
Each signal of the hot line 180 shown in FIG. 1 is wired-OR connected. For example, the emergency stop signal 181 is a pulse signal which becomes a high level for a predetermined time width by a pull-up resistor when the emergency stop is released. Therefore, as shown in FIG. 11, the emergency stop signal / synchronization time correction signal 184 is converted into an emergency stop signal 184a having the same waveform as that of the emergency stop signal 181, when the time correction analog signal 184b is used. This is a signal to be superimposed.
[0079]
The A / D interface circuit 1060 includes a digital input / output buffer circuit 1061 relating to the emergency stop signal 184a and an emergency stop signal / synchronization time correction signal taken from the hot line 180, as shown in FIG. An analog amplifier circuit 1062 for amplifying the analog signal 184b of the specific voltage level 184, and the A / D which converts the amplified analog signal 1070 into a digital signal 1072 and outputs it to the internal timer 350 as a synchronization time correction signal CORRECT. A converter 1063, a D / A converter 1064 for converting a timer signal TIMER, which is a digital signal 1072 having a period of 1 ms input from the internal timer 350, to an analog signal 1070, and an analog signal having a specific voltage level based on the converted analog signal 1070. The emergency stop signal / synchronization time correction signal 184 generated with the grayed signal 184b, and an analog output circuit 1065 to be sent to the hot line 180.
[0080]
The digital input / output buffer circuit 1061 receives the failure occurrence notification signal EMG, which is a pulse signal 1074 having a predetermined time width, from the servo amplifier CPU 310, and sends an emergency stop signal / synchronization time correction signal 184 emergency stop signal 184 a to the hotline 180. Output. In addition, upon receiving an emergency stop signal 184 a of the emergency stop signal / synchronization time correction signal 184 from the hot line 180, it outputs an interrupt signal INTERRUPT to the servo amplifier CPU 310 and outputs a reset signal RESET to the internal timer 350.
[0081]
Here, it is assumed that the input voltage of the digital input / output buffer circuit 1061 is 2.0 V or higher, the output voltage is 2.5 V or lower, and the absolute maximum input voltage is 3.3 V. The analog signal 184b of the emergency stop signal / synchronization time correction signal 184 input from the hot line 180 at a period of 1 ms is, for example, a frequency signal of 1 kHz (amplitude ± 0.5 V or less, reference voltage 2.5 V).
[0082]
In the synchronization time correction, the personal computer 110 or one servo amplifier generates a timer signal TIMER which is a digital signal 1072 having a 1 ms period, and the other servo amplifiers output a synchronization time correction signal CORRECT every 1 ms to the timer signal TIMER. The same digital signal 1072 can be obtained.
[0083]
As described above, according to the second embodiment, the hot line signal lines used for time setting and synchronization deviation correction can be combined, so that the configuration of the hot line can be simplified.
[0084]
Embodiment 3 FIG.
FIG. 12 is a block diagram showing a configuration of a servo amplifier in a numerical control system according to Embodiment 3 of the present invention. In FIG. 12, the same reference numerals are given to the same or equivalent components in the configuration shown in FIG. Here, a description will be given focusing on a portion relating to the third embodiment.
[0085]
In the servo amplifier 1230 shown in FIG. 12, a comparator circuit 1270 is provided in the servo amplifier 1030 shown in FIG. Comparator circuit 1270 performs the time comparison process in steps ST27 and ST28 shown in FIG.
[0086]
That is, the comparator circuit 1270 compares the absolute time command data D_TIME from the servo amplifier CPU 310 with the real time data R_TIME from the internal timer 350. As a result of the comparison, if they are not the same, an input request signal D_IN requesting the servo amplifier CPU 310 to input the next data is output. If they are the same, the absolute coordinate data D_OUT is output to the servo motor rotation control circuit 340.
[0087]
Since the time comparison processing in steps ST27 and ST28 shown in FIG. 6 is performed in real time, the load on the servo amplifier CPU 310 is large. According to the third embodiment, the time comparison process in steps ST27 and ST28 can be performed at high speed by hardware, so that the load on servo amplifier CPU 310 can be reduced. In the third embodiment, an example of application to the second embodiment has been described. However, it is needless to say that the third embodiment can be similarly applied to the first embodiment.
[0088]
As described above, the numerical control system according to the present invention is capable of realizing synchronous interpolation control between a plurality of servo amplifiers by transmitting absolute time command data to the plurality of servo amplifiers by an asynchronous communication method, so that the numerical control system can be implemented on a large scale. A numerical control system that is highly accurate and that can flexibly respond to various user requirements can be configured using, for example, an inexpensive personal computer, LAN, or the like.
[0089]
Here, the entity that transmits the absolute time command data, that is, the numerical control processing means is the personal computer 110 as a computer device or the host computer of the upper network 125 in FIG. 1, but the present invention is not limited to this. Instead, for example, an asynchronous communication function may be added to a conventional numerical controller, or an asynchronous communication function may be added to a servo amplifier having a built-in numerical controller and having a high processing capability.
[0090]
In addition, in FIG. 1, the LAN 115 is a wired LAN, but may be a wireless LAN, and communication means such as an optical cable and satellite communication may be used. That is, according to the present invention, if the communication speed is high, and if there is a memory of sufficient and necessary capacity and an accurate internal timer, servo control can be performed via a wide area network such as the Internet, wireless communication, or satellite communication. Since synchronous interpolation control of the motor becomes possible, a large-scale numerical control system can be constructed.
[0091]
For example, if it is applied to the mirror control of a solar power generation satellite orbiting the earth, a numerical control system that can synchronously control a servo motor that controls each of a plurality of mirrors in units of several nanometers and integrate sunlight, etc. Can be constructed.
[0092]
【The invention's effect】
As described above, according to the present invention, the numerical control processing means and the plurality of axis control means are connected via the network of the asynchronous communication system, and the numerical control processing means performs the calculation of the numerical control processing and When absolute time command data representing the processing time of the axis is generated and the generated absolute time command data is transmitted to the network of the asynchronous communication system, a plurality of axis control means take in the absolute time command data from the network and store the absolute time command data. Synchronous interpolation control is performed between each other according to the internal timer indicating that there is no need to use a dedicated CPU for numerical control processing or a dedicated synchronous communication interface, and it is inexpensive and flexibly responds to various user requests. A possible numerical control system is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a numerical control system according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration example of a personal computer shown in FIG.
FIG. 3 is a block diagram illustrating a configuration example of a servo amplifier illustrated in FIG. 1;
FIG. 4 is a flowchart illustrating the operation of the personal computer shown in FIG.
FIG. 5 is a diagram illustrating a coordinate system in which an X axis and a Y axis are used as synchronous interpolation control axes.
FIG. 6 is a flowchart illustrating an operation of the servo amplifier shown in FIG. 1;
FIG. 7 is a diagram showing a configuration example of communication data from the personal computer shown in FIG. 1 to the servo amplifier.
8 is a diagram in which a time of a communication interval between the personal computer and the servo amplifier shown in FIG. 1 is calculated as a relationship between a communication speed of the LAN and an interpolation cycle.
9 is a diagram in which a data amount for servo communication stored in an external storage device of the personal computer shown in FIG. 1 is calculated as a relationship between an interpolation cycle and a processing time.
FIG. 10 is a block diagram showing a configuration of a servo amplifier in a numerical control system according to a second embodiment of the present invention.
FIG. 11 is a block diagram showing details of an A / D interface circuit shown in FIG. 10;
FIG. 12 is a block diagram showing a configuration of a servo amplifier in a numerical control system according to Embodiment 3 of the present invention.
[Explanation of symbols]
110 PC, 115 LAN, 120 switching hub, 130-13n, 1030, 1230 Axis control unit (servo amplifier), 125 upper network, 180 hot line, 181 emergency stop signal, 182 synchronization time reset signal, 183 synchronization time correction signal , 184 emergency stop signal / synchronization time correction signal, 190 emergency stop switch, 140-14n servo motor, 210 personal computer CPU, 220, 320 main memory, 230 external storage device, 240, 350 internal timer, 250, 330 LAN interface circuit, 255,335 Communication data buffer memory, 270 PC card interface circuit, 280 card type NC (PC card type), 290 Servo amplifier communication data, 310 Servo amplifier CPU, 340 Servo mode Data rotation control circuit, 360 I / O interface circuit, 1060 A / D interface circuit, 1061 digital input / output buffer circuit, 1062 analog amplifier circuit, 1063 A / D converter, 1064 analog output circuit, 1065 D / A converter, 1270 Comparator circuit.

Claims (9)

Numerical control processing means for performing calculation of numerical control processing to generate absolute time command data representing the processing time of each axis, and transmitting the generated absolute time command data to the network of the asynchronous communication system,
A plurality of axis control means connected to the numerical control processing means via the network of the asynchronous communication system, and performing synchronous interpolation control between them in accordance with an internal timer indicating an absolute time incorporated by taking in the absolute time command data from the network; When,
A numerical control system comprising: 2. The numerical value according to claim 1, wherein at least the plurality of axis control units are connected by a hot line which is a dedicated wired or wireless transmission path, and can transmit and receive an emergency stop signal via the hot line. Control system. The numerical control system according to claim 1, wherein the internal timer provided in each of the plurality of axis control units is a high-precision timer. The plurality of axis control means sets an absolute time of an internal timer provided for each of them, up to year, month, day, hour, minute by communication with the numerical control processing means via the network, and seconds / milliseconds 3. The numerical control system according to claim 2, wherein microseconds and nanoseconds are set to be the same among the plurality of axis control means using the hot line. The plurality of axis control means obtains and sets the absolute time of the internal timer provided for each of the plurality of axes up to the year, month, day, hour, and minute from the absolute time supply means, and sets seconds, milliseconds, microseconds, and nanoseconds. 3. The numerical control system according to claim 2, wherein the setting is made to be the same among the plurality of axis control means using the hot line. 4. At least one of the plurality of axis control means transmits a timer value of the internal timer of the own axis control means for each fixed period to the hot line in the form of a digital signal, and all the remaining axis control means are The numerical control system according to any one of claims 2 to 5, wherein an internal timer of the self-axis control means is corrected using the timer value taken from a hot line. The axis control means for transmitting the timer value to the hot line converts the timer value of the internal timer of the self-axis control means for each fixed period into an analog signal, and the converted analog signal is provided on the hot line. The numerical control system according to claim 6, wherein the transmission is performed by being superimposed on the stop signal. The plurality of axis control means,
A hardware circuit that performs a comparison operation of a match / mismatch between the absolute time in the transmitted absolute time command data and the real time indicated by the internal timer,
The numerical control system according to claim 1 or 2, further comprising: When the numerical control processing means is a computer device capable of mounting a PC card,
The computer device includes:
A card type NC of a PC card type for generating and processing the absolute time command data in real time is connected.
3. The numerical control system according to claim 1, wherein:

Images