TWI834071B - Multi-axis servo control system - Google Patents

Abstract

A multi-axis servo control system includes a plurality of motors and a plurality of drive control apparatuses. The drive control apparatuses are mutually connected through an external field bus. Each drive control apparatus includes a control unit and a plurality of drive units. The drive units and the control unit are connected in series by a plurality of local buses to form a series-connected communication path of sequentially transmitting data. Each drive unit controls at least one of the motors. The control unit receives multi-axis position commands through the external field bus, and the drive units correspondingly receive multi-axis commands through the local field buses so as to control the motors in a distribution manner.

Description

Multi-axis servo control system

The present invention relates to a multi-axis servo control system, in particular to a multi-axis servo control system with decentralized control of position commands and current commands.

Please refer to Figures 1 and 2, which are schematic structural diagrams of the first type and the second type of the existing multi-axis servo control system respectively. As shown in Figure 1, the first type used is a single independent servo driver controlling the rotation of a single-axis motor, which means that one servo driver controls the rotation of one motor. As shown in Figure 1, it is three servo drives. The driver 100A is used with the corresponding three motors 200A. In this type of application, two servo drives 100A are connected through a communication bus (field bus) 300A. In this way, each servo drive 100A can receive control commands from the upper controller (or host computer), and then control all the control commands. The corresponding motor 200A is controlled. Among them, the communication bus can be EtherCAT, CANOpen, PROFINET, etc., but it is not limited to this. Each 100A servo drive contains at least a controller and a power module. The controller is used to plan and control the speed of the motor, and the power module is used to provide the current output of the drive. However, in this type of control system, since each motor 200A is controlled by the corresponding servo driver 100A, in multi-axis applications, synchronization is limited by the communication cycle of the communication bus, so its synchronization is poor.

As shown in Figure 2, the second type used is a single independent servo driver controlling multiple motors. As shown in Figure 2, each servo driver 100A controls three motors 200A, but there is no limit to three. , as long as the output current (power) that the servo driver 100A can supply is within the allowable range, the number to maintain the normal operation of the motor 200A can be driven and controlled. Likewise, two servo drives The controllers 100A are connected through the communication bus 300A, and receive control commands from the upper controller through the communication bus 300A. However, due to the limitation of the output current (power), the upper limit of the number of motors 200A or the rated output of the motor 200A has been limited at the beginning of the servo drive 100A design, so its expandability and replaceability (replacement) Poor.

For this reason, how to design a multi-axis servo control system, especially a multi-axis servo control system with decentralized control of position commands and current commands, to solve the problems and technical bottlenecks of the existing technology is what the inventor of this case is studying. important topic.

The purpose of the present invention is to provide a multi-axis servo control system to solve the problems of the existing technology.

In order to achieve the aforementioned purpose, the multi-axis servo control system proposed by the present invention includes a plurality of motors and a plurality of drive control devices. A plurality of drive control devices are connected to each other through an external communication bus. Each drive control device includes a control unit and a plurality of drive units. A plurality of drive units and the control unit are connected in series through a plurality of local buses to form a series communication loop that can transmit data sequentially. Each drive unit is used to control at least one of the motors. The control unit receives multi-axis position commands through the external communication bus, and the driving units receive multi-axis commands correspondingly through the local bus to control the motors in a distributed manner.

In one embodiment, the local bus is a high-speed bus; the local bus starts from an output end of the control unit, connects the driving units sequentially in series, and finally feeds back to the control unit. An input end is terminated to form a serial communication loop that can transmit data sequentially.

In one embodiment, each drive unit includes a processor, and the control unit includes a processor; the series communication loop includes the processor of the control unit, the output end of the control unit, An input terminal of each driving unit, the processor of each driving unit, an output terminal of each driving unit, the input terminal of the control unit and the processor of the control unit.

In one embodiment, the control unit includes a command processor and a command synchronizer. The command synchronizer is connected to the command processor.

In one embodiment, the control unit includes a command generator, a command processor and a command synchronizer. The command processor is connected to the command generator. The command synchronizer is connected to the command processor.

In one embodiment, the control unit is a slave controller, providing a slave operation mode for controlling the drive units that are also the drive control device.

In one embodiment, the control unit is a master station controller that provides a master station operation mode for controlling the drive units of the same drive control device and the drive units of other drive control devices. control unit and such drive units. The drive unit includes a current loop unit. The current loop unit receives a current command and a current value, and compares the current command and the current value to generate a current control signal.

In one embodiment, the driving unit further includes a command processing unit and a command synchronization unit. The command processing unit receives the current command and processes the current command. The command synchronization unit is connected to the command processing unit, receives the processed current command, and synchronizes the current command to provide it to the current loop unit.

In one embodiment, the driving unit further includes a current processing unit. The current processing unit receives the sampled current value and processes the current value to provide it to the current loop unit.

In one embodiment, the driving unit further includes a feedback processing unit. The feedback processing unit receives a plurality of feedback commands and performs communication packet processing on the feedback commands to provide output to the local bus.

The technical effects achieved by the proposed multi-axis servo control system: 1. Distributed computing realized through the processing and control of current (torque) commands by the drive unit and the processing and control of position (speed) commands by the control unit, not only The calculation amount of the control unit can be greatly reduced (since the processing and control of current (torque) commands are executed through the drive unit), a controller with a better cost and relatively low-level functions can be selected, and the expansion of the drive control device can also be improved. stability and replaceability; 2. The high-speed local bus realizes a complete communication transmission loop of series feedback through the wiring method of the backplane, which can avoid data distortion and attenuation; 3. Through the detailed calculation of the control unit, the command data subdivision, and then provided to the drive unit that controls each axis motor, so that the drive unit can finely control each axis motor; 4. The control unit can be operated in slave mode and master mode, thus increasing the flexibility and diversity of the use of the control unit .

In order to further understand the technology, means and effects adopted by the present invention to achieve the intended purpose, please refer to the following detailed description and drawings of the present invention. It is believed that the purpose, features and characteristics of the present invention can be understood in depth and For specific understanding, however, the attached drawings are only for reference and illustration, and are not intended to limit the present invention.

100: Drive control device

200: Motor

300: Communication bus

400:Local bus

10:Control unit

20:Drive unit

101:Command generator

102:Command processor

104:Command synchronizer

100A: Servo drive

200A: Motor

300A: Communication bus

Figure 1: It is a schematic diagram of the architecture of the first type of existing multi-axis servo control system.

Figure 2: It is a schematic structural diagram of the second type of existing multi-axis servo control system.

Figure 3 is a schematic diagram of the architecture of the multi-axis servo control system of the present invention.

Figure 4 is a schematic diagram of the design of the high-speed local bus of the present invention.

Figure 5: is a schematic diagram of the control method of the control unit of the present invention.

Figure 6 is a schematic diagram of the control method of the drive unit of the present invention.

Figure 7: is a schematic diagram of the control unit of the present invention as a slave station.

Figure 8: It is a schematic diagram of the control unit of the present invention serving as the master station.

The technical content and detailed description of the present invention are as follows with reference to the drawings.

Please refer to Figure 3, which is a schematic diagram of the architecture of the multi-axis servo control system of the present invention. The multi-axis servo control system includes multiple motors 200 and multiple drive control devices 100 . A plurality of drive control devices 100 are connected to each other through an external communication bus (field bus) 300 . As shown in FIG. 3 , two sets of drive control devices 100 are taken as an example, but the present invention is not limited thereto. Among them, in the present invention, the multi-axis motor 200 is applied, but it is not limited to conveying and handling devices, pick and place devices, surface adhesive technology (SMT), positioning devices for visual inspection, spot welding and The field of mechanical automation operations and robotic arm operations such as reciprocating measurement.

Each drive control device 100 includes a control unit 10 and a plurality of drive units 20 . The plurality of driving units 20 are connected in series to each other, and the driving units 20 and the control unit 10 through a plurality of local buses 400 to form a series communication loop that can transmit data sequentially. Each driving unit 20 is used to control at least one of the motors 200 . However, the number and form of the motors 200 controlled by each driving unit 20 are not limited to the situation shown in FIG. 3 .

The control unit 10 receives multi-axis position commands (or multi-axis speed commands) through the external communication bus 300, and the driving units 20 correspondingly receive multi-axis commands through the local bus 400 to control the motors 200 in a distributed manner. Specifically, Details will be explained later.

As shown in Figure 3, the present invention provides a multi-axis servo control system (servo drive design for multi-axis motor control), which decentralizes traditional multi-axis motor control and consists of a control unit 10 and a drive unit (or servo unit, servo drive). The unit) 20, the local bus 400, and the motor 200 are independently composed, and maintain the connection method of a single external communication bus 300. The characteristics of this control system architecture are:

1. The high-speed local bus 400 adopts input and output connections, which will be described in detail later.

2. The control unit 10 is responsible for synchronous control of the position and speed of each axis motor 200 and the motion process of each axis, which will be described in detail later.

3. The drive unit 20 is responsible for current control, current sampling and position feedback of the motor 200 . Among them, one driving unit 20 controls more than one motor 200; therefore, by simply replacing the driving unit 20 with a larger output power, it can drive and control motors 200 with more or larger rated power without affecting the overall performance. The operation of the machine is better, so the expandability and replaceability (replacement) are better.

4. The control unit 10 can be used in two modes: master and slave, providing commands to control each axis motor 200. When it is a master station, it can actively control other servo drives (i.e., the drive control device 100) and multiple motors 200 connected to its multiple servo drives through the external communication bus 300; when it is a slave station, it can control its own multiple servo drives. The multiple connected motors 200 are driven and passively receive external bus commands, which will be described in detail later.

Please refer to Figure 4, which is a schematic diagram of the design of the high-speed local bus of the present invention. The high-speed local bus 400 of the present invention is designed with hardware (for example, in this embodiment, it is implemented by backplane wiring) and adopts a series feedback method (the local bus 400 in the drive control device 100 on the left is on the right The expansion of the local bus 400 in the drive control device 100 takes the control unit 10 as the starting station and transmits data to the input terminal in (or input module in) of the first serially connected drive unit 20. After the received data is processed by the processor 402, the data is transmitted to the input terminal in of the second serial drive unit 20 through the output terminal out (or output module out). In this way, the input terminal in of the last series-connected driving unit 20 is reached. Finally, it is output to another input terminal in of the previous driving unit 20 through the output terminal out of the last serially connected driving unit 20, and then returned to the other input terminal of the control unit 10 in sequence, thus forming a complete communication transmission loop. In this way, the data is communicated and transmitted through the series feedback method to avoid data distortion and attenuation.

Please refer to FIG. 5 , which is a schematic diagram of the control method of the control unit of the present invention. The control unit 10 receives the multi-axis command data transmitted by the external communication bus 300 (i.e., the command for the first axis, the command for the second axis...the command for the Nth axis), where the multi-axis command data is transmitted by the upper controller. Provided, and the command data includes position, speed, torque...etc. In this embodiment, the control unit 10 includes a command processor 102 and a command synchronizer 104. After receiving the multi-axis command data, the control unit 10 processes the multi-axis command data through the command processor 102, including command smoothing processing, command interpolation processing, etc. Then, after the command synchronizer 104 synchronizes the processed command data, the synchronized command data is transmitted to the first drive unit 20 through the high-speed local bus 400, and each drive unit 20 is sequentially connected through the local bus 400. The command data of the driving unit 20 is transmitted, and finally the command data is transmitted back to the control unit 10 . Then, the control unit 10 processes the status information of each axis and transmits the processed information back to the communication bus 300 . In other words, the time schedule controlled by each axis motor 200 is executed by the control unit 10 . Therefore, through the detailed operation of the command processor 102 and the command synchronizer 104 of the control unit 10, the multi-axis command data provided by the upper controller subdivides the command data at the second (second) or millisecond (ms) level into micro Seconds (us) or even nanoseconds (ns) level commands are provided to the driving unit 20 that controls each axis motor 200 , so that the driving unit 20 can control each axis motor 200 precisely (finely). In this embodiment, the control unit 10 only needs to be responsible for processing command data, and the current control of each axis motor 200 is responsible for the corresponding driving unit 20 to achieve distributed computing effects.

It is worth mentioning that the control unit 10 has position command control and current command control, where the position command corresponds to the speed command and the current command corresponds to the torque command. In existing traditional control mechanisms, position (speed) command control and current (torque) command control are usually processed in the same processor or controller. However, in the present invention, the processing and control of the current (torque) command is performed through the drive unit 20 , while the processing and control of the position (speed) command is performed through the control unit 10 . In other words, due to the modularity advantage of the present invention, the current (torque) command and the position (speed) command can be executed in different (ie, the drive unit 20 and the control unit 10 ) processors or controllers respectively. This not only significantly reduces the control The calculation amount of the unit 10 (since the processing and control of the current (torque) command is executed through the drive unit 20), a controller with better cost and relatively low-level functions can be selected, and the scalability and scalability of the drive control device 100 can also be improved. Replaceability.

Please refer to FIG. 6 , which is a schematic diagram of the control method of the drive unit of the present invention. In one embodiment, the driving unit 20 can implement current loop control through a control chip. The driving unit 20 of the present invention includes a current sampling unit 21, a current processing unit 22, a command processing unit 23, a command synchronization unit 24, a current loop unit 25, a pulse width modulation signal (PWM) unit 26 and a feedback processing unit. 27. The current sampling unit 21 receives the current feedback signal and performs sampling processing on the current feedback signal, for example, performing signal sampling through a Delta-Sigma (Δ-Σ) modulation method. The current processing unit 22 receives the sampled current feedback signal to process the current feedback. The command processing unit 23 receives command data input from the local bus 400 to provide local high-speed command data processing. The command synchronization unit 24 is a command synchronization timing mechanism to synchronize command data. The current loop unit 25 receives the synchronization command data provided by the command synchronization unit 24 and the feedback current information provided by the current processing unit 22 to perform current loop control. The PWM unit 26 generates a controlled PWM signal output according to the current loop control of the current loop unit 25 to control the actual current of the motor 200 . The feedback processing unit 27 is used to receive encoder feedback (encoder feedback), end encoder feedback (end optical ruler feedback) and pressure (force) sensor feedback (force sensor feedback) to perform encoder communication packet processing. .

Specifically, the driving unit 20 receives the command data transmitted from the control unit 10 and performs position control loop, speed control loop and encoder position processing of the motor 200 . Among them, the command data includes but is not limited to current command, electrical angle, speed and communication delay compensation amount, etc. The transmission and reception have error detection and correction mechanisms.

Because the drive unit 20 will transmit the current command, electrical angle and communication delay compensation amount to the drive units 20 of other axes each time it is interrupted, it is necessary to command the synchronization unit 24 to synchronize the timing processing module to transfer each The axis drive unit 20 performs a time synchronization mechanism to ensure that encoder sampling, current feedback sampling, and PWM effective time are synchronized among multiple axes.

Through current feedback sampling, the feedback data is decoded by the current processing unit 22, and then used with a self-designed Sync Filter architecture to transmit the current feedback information back to the current loop for control. The current sampling method includes but is not limited to Delta-Sigma(Δ-Σ), ADC, etc.

The current loop control of the current loop unit 25 includes PI (differential-integral) control, d-q axis (direct-quadrature axis) current conversion, SVPWM control, voltage decoupling, and dead time compensation. The current loop control of the current loop unit 25 controls the comparison value calculated by SVPWM, and realizes the six-bridge control of the IGBT through the PWM unit 26.

The feedback processing unit 27 receives encoder feedback signals, terminal encoder signals and pressure sensor signals. These communication formats all include ECC (error correcting code) functions. After the feedback processing unit 27 decodes the communication packet, it transmits the data back to the control unit 10 through local bus 400 communication, thereby performing full closed-loop control of position and torque.

In the present invention, the operating role of the control unit 10 can be divided into two modes: slave mode and master mode. Please refer to Figure 7, which is a schematic diagram of the control unit of the present invention serving as a slave station. When the control unit 10 acts as a slave, multi-axis command data is provided through a host controller, a programmable logic controller (PLC) or a motion controller. Therefore, the driving unit 20 receives the multi-axis command data and can further drive and control the motor 200 of each axis. In slave mode operation, the control unit 10 passively receives multi-axis command data provided by the upper controller, and refines the command data through the command processor 102 and the command synchronizer 104, so that the drive unit 20 can accurately ( Finely) control each axis motor 200.

The master station device shown on the right side of Figure 7 (can be a third-party upper master station controller). The third-party upper master controller (master device) plans the commands of each axis and transmits them to each slave device (slave device) through the communication bus 300. Relevant slave station information will also be sent back to the third party through the communication bus 300. master station controller. For the slave device, each slave device will provide multi-axis command information to the third-party slave device, so that the third-party slave device can control each axis motor 200 in the slave device respectively.

Please refer to Figure 8, which is a schematic diagram of the control unit of the present invention serving as the master station. In the master mode, the control unit 10 has the function of a master controller, which means that in addition to controlling the local drive unit 20 , the control unit 10 can also generate command information through the communication bus 300 through the command generator 101 Transmitted to other slave devices to control other slave devices. In other words, when the control unit 10 itself can serve as the master controller, there is no need for a third-party upper master controller. Therefore, the planning, interpolation, and synchronization processing of each axis command data can be completed in the control unit 10 . In one embodiment, through program programming, the user can be provided with program programming for external axis or internal axis control, and the programmed program can be downloaded to the control unit 10. In this way, the control unit 10 operating as a master mode The motor 200 of the external axis and/or the internal axis is controlled according to the programmed program.

To sum up, the present invention has the following features and advantages:

1. The distributed computing implemented through the processing and control of the current (torque) command by the drive unit 20 and the processing and control of the position (speed) command by the control unit 10 can not only greatly reduce the calculation amount of the control unit 10 (due to The processing and control of current (torque) commands are performed through the drive unit 20), which allows the selection of a controller with lower cost and relatively low-level functions, and also improves the expandability and replaceability of the drive control device 100.

2. The high-speed local bus uses backplane wiring to achieve a complete communication transmission loop with series feedback, which can avoid data distortion and attenuation.

3. Through the detailed calculation of the control unit 10, the command data is subdivided and then provided to the drive unit 20 that controls each axis motor 200, so that the drive unit 20 can control each axis motor 200 in a precise manner.

4. The control unit 10 can operate in slave mode and master mode, thus improving the flexibility and diversity of use of the control unit 10.

The above are only detailed descriptions and drawings of the preferred embodiments of the present invention. However, the characteristics of the present invention are not limited thereto and are not used to limit the present invention. The entire scope of the present invention should be determined by the following patent application scope. Subject to the present invention, all embodiments that are within the spirit of the patentable scope of the present invention and similar changes thereof shall be included in the scope of the present invention. Any person familiar with the art can easily think of such changes or modifications in the field of the present invention. Modifications may be covered by the following patent scope of this case.

100: Drive control device

200: Motor

300: Communication bus

400:Local bus

10:Control unit

20:Drive unit

Claims (11)

A multi-axis servo control system includes: a plurality of motors; and a plurality of drive control devices, which are connected to each other through an external communication bus. Each of the drive control devices includes: a control unit; and a plurality of drive units, and the control unit is connected to the control unit through a plurality of local The bus is connected in series to form a series communication loop that can transmit data sequentially; each drive unit is used to control at least one of the motors; wherein the control units are connected to each other through the external communication bus, and through the The external communication bus receives multi-axis position commands; any one of the control units can provide multi-axis commands to the drive units belonging to the drive control device or the drive units of other drive control devices, so that the drive units can pass The local bus accordingly receives multi-axis commands to control the motors in a distributed manner. The multi-axis servo control system as described in claim 1, wherein the local bus is a high-speed bus; the local bus starts from an output end of the control unit and connects the drive units in series. , and finally ends by feeding back to an input end of the control unit, so as to form the serial communication loop that can transmit data sequentially. The multi-axis servo control system as claimed in claim 2, wherein each drive unit includes a processor, and the control unit includes a processor; The series communication loop includes the processor of the control unit, the output end of the control unit, an input end of each drive unit, the processor of each drive unit, an output end of each drive unit, the The input of the control unit and the processor of the control unit. The multi-axis servo control system as claimed in claim 1, wherein the control unit includes: a command processor; and a command synchronizer connected to the command processor. The multi-axis servo control system of claim 1, wherein the control unit includes: a command generator; a command processor connected to the command generator; and a command synchronizer connected to the command processor. The multi-axis servo control system as claimed in claim 1, wherein the control unit is a slave controller that provides a slave operation mode for controlling the drive units that are also the drive control device. The multi-axis servo control system as described in claim 1, wherein the control unit is a master station controller that provides a master station operation mode to control the drive units that are also the drive control device and other drives. The control unit and the driving units of the driving units of the control device. The multi-axis servo control system as claimed in claim 1, wherein the drive unit includes: a current loop unit that receives a current command and a current value to compare the current command and the current value to generate a current control signal. . The multi-axis servo control system of claim 8, wherein the drive unit further includes: a command processing unit that receives the current command and processes the current command; and A command synchronization unit is connected to the command processing unit, receives the processed current command, and synchronizes the current command to provide it to the current loop unit. The multi-axis servo control system of claim 8, wherein the drive unit further includes: a current processing unit that receives the sampled current value and processes the current value to provide it to the current loop unit. The multi-axis servo control system as described in claim 8, wherein the drive unit further includes: a feedback processing unit that receives a plurality of feedback commands and performs communication packet processing on the feedback commands to provide them to the local bus. output.