Servo system, motor control method and device based on servo system, and medium

Abstract

The embodiment of the invention relates to the field of servo control, in particular to a servo system, a motor control method based on the servo system, equipment and a medium, and the system comprises a position loop control module, a speed loop control module and a motor module which are connected in sequence; the position loop control module comprises a position adjusting module, a speed feed-forward compensator and a speed error device; the position adjusting module is used for generating a speed instruction according to an obtained position instruction sent by the upper computer and a feedback position of the motor module; the speed feed-forward compensator is used for determining the compensation amount of the speed instruction according to the position instruction and a compensation formula; the speed error device is used for superposing the compensation amount and the speed instruction as a target speed instruction; the speed loop control module is used for receiving the target speed instruction, obtaining the feedback speed of a servo motor in the motor module, and outputting an electromagnetic torque instruction according to the target speed instruction and the feedback speed to drive the servo motor to work. By controlling the servo motor, the position dynamic following error can be reduced.

Description

Technical Field

[0001] The present invention relates to the field of servo control, and in particular to a servo system and a motor control method, device and medium based on the servo system. Background Art

[0002] Servo control technology is one of the core technologies of industrial automation equipment such as CNC machine tools and industrial robots. High-performance servo control is the guarantee of processing accuracy and work efficiency of these equipment. Servo control systems generally consist of three closed loops: position loop, speed loop and current loop. Usually the current loop has a high enough response bandwidth and can follow the current command well; the speed loop adopts pseudo-differential feedback control mode, which can reduce speed overshoot and improve anti-interference performance compared with the traditional PI (Proportional-Integral) control mode; the position loop usually adopts proportional control + feedforward control mode.

[0003] Although the pseudo-differential feedback control method of the speed loop can effectively reduce speed overshoot and improve anti-interference, it will offset the effect of integration, resulting in a delay in speed response and excessive position following deviation. However, CNC machine tools, industrial robots and other equipment have relatively high requirements for trajectory accuracy, and excessive position following deviation will inevitably reduce their trajectory accuracy. Summary of the invention

[0004] The purpose of the embodiments of the present invention is to provide a servo system and a motor control method, device, and medium based on the servo system. The present invention can compensate for the phase delay of the speed response, reduce the position following error, and improve the trajectory tracking accuracy of the device.

[0005] To solve the above technical problems, an embodiment of the present invention provides a servo system, including: a position loop control module, a speed loop control module and a motor module connected in sequence; the position loop control module includes a position adjustment module, a speed feedforward compensator and a speed error device; the position adjustment module is used to generate a speed instruction according to the position instruction issued by the host computer and the feedback position of the motor module; the speed feedforward compensator is used to determine the compensation amount of the speed instruction according to the position instruction and the compensation formula; the speed error device is used to superimpose the compensation amount and the speed instruction as a target speed instruction; the speed loop control module is used to receive the target speed instruction and obtain the feedback speed of the servo motor in the motor module, and output an electromagnetic torque instruction according to the target speed instruction and the feedback speed to drive the servo motor to work. In addition, the position adjustment module as described above includes a position error device and a position proportional regulator connected in sequence; the position error device is used to obtain the position instruction and the feedback position, and determine the position following error according to the position instruction and the feedback position; the position proportional regulator is used to generate the speed instruction according to the position following error.

[0006] In addition, the speed loop control module as described above includes: a speed PI regulator, an electromagnetic torque error device and a speed feedback proportional gain module; the speed PI regulator is used to obtain the target speed instruction and adjust the target speed instruction and output the adjustment result; the speed feedback proportional gain module is used to obtain the feedback speed and output the gain according to the feedback speed; the electromagnetic torque error device determines and outputs the electromagnetic torque instruction according to the adjustment result and the gain.

[0007] In addition, the motor module as described above includes: the servo motor and a speed integrator; the servo motor is used to perform a rotation operation according to the electromagnetic torque instruction; and the speed integrator is used to generate the feedback position according to the feedback speed of the servo motor.

[0008] In addition, the compensation formula as mentioned above is Where, G(s) is the speed feedforward compensator, J s is the system inertia, K v is the speed loop gain constant, and s is the Laplace operator.

[0009] In addition, the servo system as described above also includes: a disturbance torque adder; the disturbance torque adder is used to obtain the electromagnetic torque instruction and the load torque, and output the difference / sum between the electromagnetic torque instruction and the load torque as a target torque instruction instead of the electromagnetic torque instruction to the motor module to drive the servo motor.

[0010] An embodiment of the present invention also provides a motor control method based on a servo system, which is applied to the servo system as described above, and the method includes: obtaining a position command issued by a host computer and a feedback position of a servo motor, and calculating a speed command based on the position command and the feedback position; calculating a compensation amount of the speed command based on the position command and a compensation formula, and superimposing the compensation amount and the speed command as a target speed command; obtaining the feedback speed of the servo motor, and calculating an electromagnetic torque command based on the target speed command and the feedback speed; and using the electromagnetic torque command to drive the servo motor to perform operations.

[0011] An embodiment of the present invention further provides an electronic device, comprising: a processor, a memory, and a program stored in the memory and executable on the processor, wherein the program, when executed by the processor, implements the steps in the motor control method based on the servo system as described above.

[0012] An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps in the motor control method based on the servo system as described above are implemented.

[0013] An embodiment of the present invention further provides a computer program product, including computer instructions, which, when executed by a processor, implement the steps in the motor control method based on the servo system as described above.

[0014] Compared with the related art, the embodiment of the present invention uses the position loop control module to obtain the position command issued by the host computer and the feedback position of the motor module to generate a speed command, and determines the compensation amount of the speed command according to the position command and the compensation formula, and superimposes the compensation amount and the speed command as the target speed command output. The servo motor is driven by the target speed command to compensate for the phase delay caused by speed following, reduce the position following error, and thus improve the trajectory tracking accuracy of the industrial automation equipment controlled by the servo motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] One or more embodiments are exemplarily described by the pictures in the corresponding drawings, and these exemplary descriptions do not constitute limitations on the embodiments.

[0016] Figure 1 The structure of the servo system provided by the embodiment of the present invention is shown in FIG. Figure 1 ;

[0017] Figure 2 The structure of the servo system provided by the embodiment of the present invention is shown in FIG. Figure 2 ;

[0018] Figure 3 The specific process of the motor control method based on the servo system provided by the embodiment of the present invention is Figure 1 ;

[0019] Figure 4 is a comparison diagram of position following error effects of the present invention and the prior art provided by an embodiment of the present invention;

[0020] Figure 5 It is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the embodiments of the present invention, many technical details are provided to enable readers to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present invention can be implemented.

[0022] Before describing the present solution in detail, the servo (control) system is described first. The servo system may include any combination of three control loops: position loop, speed loop and current loop. Among them, the current loop is nested in the speed loop, and the speed loop is nested in the position loop. The speed loop is the most common servo control loop. It compares the command speed with the actual speed through a tachometer or encoder, and issues a command to increase or decrease the motor speed accordingly. For applications that require motor control, a position loop is added to the outer loop of the speed loop in a so-called cascaded position / speed loop. The position loop determines the following error, that is, the deviation between the actual position and the command position, and issues a speed command to reduce or eliminate the following error. The main goal of the current loop is to control torque, which affects the speed and thus the position. The current loop is usually nested in the speed loop, making the current the innermost loop, the speed loop in the middle, and the position loop the outermost loop. Since the current loop response bandwidth is much higher than the position loop and the speed loop, it can be considered that the current can be accurately followed, so the present invention approximates the current loop as a straight-through loop in order to simplify the analysis.

[0023] An embodiment of the present invention relates to a servo system, such as Figure 1 As shown, it includes a position loop control module 1, a speed loop control module 2 and a motor module 3 connected in sequence; wherein, the position loop control module 1 includes a position adjustment module 11, a speed feedforward compensator 12 and a speed error device 13; the position adjustment module 11 is used to generate a speed instruction according to the position instruction issued by the host computer and the feedback position of the motor module 3; the speed feedforward compensator 12 is used to determine the compensation amount of the speed instruction according to the position instruction and the compensation formula; the speed error device 13 is used to superimpose the compensation amount and the speed instruction as the target speed instruction; the speed loop control module 2 is used to receive the target speed instruction and obtain the servo motor 31 ( Figure 1 The feedback speed (not shown) is output according to the target speed command and the feedback speed, and the electromagnetic torque command is output to drive the servo motor 31 to operate.

[0024] Specifically, the servo system in the present embodiment is mainly used to control a permanent magnet synchronous motor. In the present embodiment, the servo motor 31 is a permanent magnet synchronous motor in practical applications, which will not be described in detail later. The position loop control module 1 is a part of the position loop (not shown in the figure), which mainly plays a role of monitoring and adjustment. The position loop control module 1 receives a position instruction from the host computer, which is a target position value sent to the servo system, indicating the desired final position or position change. The position instruction can be an absolute position (for example, given a specific position value) or a relative position (for example, given a position change), and the present application does not make specific restrictions on this. In the present embodiment, the position instruction is used to instruct the servo motor 31 to rotate to a certain angle or rotate to a certain angle.

[0025] Feedback position and feedback speed refer to feedback information obtained from the servo motor 31. Generally speaking, an encoder, a position sensor or other feedback device is installed in the servo system, and the feedback signal of the motor is obtained through the feedback device such as the encoder. The feedback signals obtained by different feedback devices are different (such as: the feedback signal of the position sensor is the feedback position, and the feedback signal of the speed sensor is the feedback speed). The position loop control module 1 can generate a corresponding speed command to adjust the position error according to the received position command and feedback position. The speed command represents the target speed value sent to the servo system, which is used to control the servo motor 31 to operate at the target speed. Therefore, the position loop control module 1 can obtain the position command and feedback position issued by the host computer and generate a speed command output.

[0026] Correspondingly, the position loop control module 1 includes a position adjustment module 11, a speed feedforward compensator 12 and a speed error device 13. Figure 1 After the position command is issued by the position adjustment module 11 in the position loop control module 1 (not shown), the speed command is generated according to the acquired position command and the feedback position of the motor module 3. At the same time, the speed feedforward compensator 12 calculates the compensation amount according to the acquired position command and the compensation formula, and the compensation amount is used to compensate the speed command. The speed error device 13 obtains the speed command and the compensation amount, and superimposes the compensation amount and the speed command as the target speed command output. Since the speed loop in this embodiment is a type I system and the speed feedforward compensator 12 is provided in the position loop control module 1. Therefore, there is a correlation between the position loop transfer function and the compensation formula of the speed feedforward compensator 12 in the position loop control module 1, and the speed feedforward compensator 12 can directly determine the compensation amount of the speed command to be input to the speed loop control module 2 according to the position command and the compensation formula. The speed loop control module 2 receives the target speed command and obtains the feedback speed of the servo motor 31 in the motor module 3, and outputs the electromagnetic torque command according to the target speed command and the feedback speed to drive the servo motor 31 to work.

[0027] In an example, Figure 2 As shown, the position regulation module 1 includes a position error device 111 and a position proportional regulator 112 which are connected in sequence; the position error device 111 is used to obtain the position instruction and the feedback position, and determine the position following error according to the position instruction and the feedback position; the position proportional regulator 112 is used to generate a speed instruction according to the position following error.

[0028] Specifically, Figure 2 As shown, the position error device 111 is used to determine the position of the With feedback position θ m Determine the position following error; the position proportional regulator 112 is used to generate a speed command according to the following error At the same time, the speed feedforward compensator 12 obtains the position instruction And the compensation formula calculates the compensation amount, which is related to the speed command After being superimposed by the speed error device 13, it is output as the target speed instruction.

[0029] In another example, Figure 2 As shown, the speed loop control module 2 includes: a speed PI regulator 21, an electromagnetic torque error device 22 and a speed feedback proportional gain module 23; wherein the speed PI regulator 21 is used to obtain a target speed command and adjust the target speed command to output an adjustment result; the speed feedback proportional gain module 23 is used to obtain a feedback speed and output a gain according to the feedback speed; the electromagnetic torque error device 22 determines and outputs an electromagnetic torque command T according to the adjustment result and the gain. e .

[0030] Accordingly, in another example, Figure 2 As shown, the motor module 3 includes: a servo motor 31 and a speed integrator 32; the servo motor is used to e Speed ​​integrator 32 is used according to the feedback speed ω of the servo motor 31 m Generate feedback position θ m .

[0031] Specifically, according to Figure 2 It can be seen that the speed loop of the present invention adopts a pseudo differential feedback control method, wherein the speed feedback coefficient in the speed feedback proportional gain module 23 is Among them, J s is the system inertia, K vi is the speed loop integral constant, the speed loop transfer function can be simplified as:

[0032] Among them, K v is the speed loop gain constant, s is the Laplace operator, J sis the system inertia of the servo system.

[0033] Accordingly, the transfer function of the entire system is as follows:

[0034]

[0035] in, is the position command, θ m is the feedback position, G(s) is the speed feedforward compensator, K p is the position loop gain constant; K v is the speed loop gain constant.

[0036] From the above formula (1), it can be seen that the speed loop response is a type I system, which has the advantage of small overshoot, but the speed following will have a phase delay. If the position loop adopts the traditional proportional + feedforward control method at this time, the position following deviation is large. However, in this embodiment, a speed feedforward compensator is designed to compensate the speed command

[0037] In one example, the compensation formula is Among them, G(s) is the speed feedforward compensator, J s is the system inertia, K v is the speed loop gain constant, and s is the Laplace operator.

[0038] Specifically, in order to compensate for the phase delay caused by speed following, let equation (2) Calculate the compensation formula Compared with the traditional speed feedforward link, item.

[0039] In another example, the servo system further includes: a disturbance torque adder 20; the disturbance torque adder 20 is used to obtain the electromagnetic torque instruction T e With load torque T L , and the electromagnetic torque command T e With load torque T L The difference / sum is output as a target torque command instead of an electromagnetic torque command to the motor module 3 to drive the servo motor 31 .

[0040] Compared with the related art, the embodiment of the present invention adds a speed feedforward compensator to determine the compensation amount of the speed command according to the transfer function of the position command and the position loop, and superimposes the compensation amount with the speed command as the target speed command output. The compensation amount can compensate for the phase delay caused by speed following and reduce the position following error.

[0041] Based on the above servo system, another embodiment of the present invention relates to a motor control method based on a servo system, which can be applied to any servo control operation with relatively high requirements for trajectory accuracy. The control method of the present invention can be performed based on the servo system of the above embodiment. On this basis, the specific process of the motor control method based on the servo system provided in this embodiment is as follows: Figure 3 As shown, the specific steps include:

[0042] Step 101: Obtain the position command issued by the host computer and the feedback position of the servo motor, and calculate the speed command according to the position command and the feedback position;

[0043] Step 102: Calculate the compensation amount of the speed command according to the position command and the compensation formula, and superimpose the compensation amount and the speed command as the target speed command;

[0044] Step 103: Obtain the feedback speed of the servo motor, and calculate the electromagnetic torque command according to the target speed command and the feedback speed;

[0045] Step 104: Use the electromagnetic torque command to drive the servo motor to operate.

[0046] Specifically, since the speed loop in this embodiment is a type I system and a speed feedforward compensator is provided in the position loop control module, the position loop transfer function is associated with the target compensation coefficient of the speed feedforward compensator in the position loop control module, and the speed feedforward compensator can directly determine the compensation amount of the speed command to be input to the speed loop control module according to the position command and the compensation formula.

[0047] It should be noted that the steps in this embodiment are described in sequence according to the linear characteristics of the servo system and the order of the modules in the servo system, which does not mean a strict execution order. In fact, the above steps will constitute a closed execution system when executed. In practical applications, the execution order can be reasonably adjusted according to the specific execution situation.

[0048] It is not difficult to find that this embodiment is a method embodiment corresponding to the above embodiment, and the relevant technical details mentioned in the above embodiment are still valid in this embodiment. In order to reduce repetition, they are not repeated here. Accordingly, the relevant technical details mentioned in this embodiment can also be applied in the above embodiment.

[0049] Specifically, since the speed loop in this embodiment adopts a pseudo differential feedback control method, the effect of the integral is offset, that is, the speed loop in this embodiment is a type I system. In addition to the pseudo differential feedback control method mentioned above, other control methods can also be used, as long as the speed loop in this embodiment is a type I system, and this application does not make any specific restrictions on the control method used.

[0050] In order to better demonstrate the effect of reducing position following error brought by this solution, Figure 4 As shown, this embodiment also provides a set of verification comparisons.

[0051] The position command adopts the 7-segment S-curve commonly used in industry, the position movement is 5 revolutions, the profile speed is 1000r / min, the acceleration is set to 50ms from 0r / min to 1000r / min, and the speed feedforward coefficient is set to 100%. The position tracking errors of the three control structures of traditional P-PI control, P-PDF (pseudo-differential feedback) control without speed feedforward compensator and P-PDF control speed feedforward compensator of the present invention are compared.

[0052] from Figure 4 It can be seen that in the acceleration and deceleration stage, when the speed loop adopts P-PDF control without the compensation method proposed in the patent, the dynamic position tracking error is twice as large as that of the traditional P-PI control structure. After P-PDF control is combined with the dynamic response improvement compensation method proposed in this patent, the position tracking error is significantly reduced, which is an order of magnitude smaller than the traditional P-PI control position error. The experimental results show that the present invention can effectively reduce the dynamic position tracking error and improve the trajectory tracking accuracy of the servo system.

[0053] The step division of the above methods is only for the purpose of clear description. When implemented, they can be combined into one step or some steps can be split and decomposed into multiple steps. As long as they include the same logical relationship, they are all within the scope of protection of this patent; adding insignificant modifications to the algorithm or process or introducing insignificant designs without changing the core design of the algorithm and process are all within the scope of protection of this patent.

[0054] Another embodiment of the present invention relates to an electronic device, such as Figure 5 As shown, it includes at least one processor 401; and a memory 402 that is communicatively connected to the at least one processor 401; wherein the memory 402 stores instructions that can be executed by the at least one processor 401, and the instructions are executed by the at least one processor 401 so that the at least one processor 401 can execute the above-mentioned motor control method based on the servo system.

[0055] The memory 402 and the processor 401 are connected in a bus manner, and the bus may include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors 401 and the memory 402 together. The bus can also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver can be one element or multiple elements, such as multiple receivers and transmitters, providing a unit for communicating with various other devices on a transmission medium. The data processed by the processor 401 is transmitted on a wireless medium via an antenna, and further, the antenna also receives data and transmits the data to the processor 401.

[0056] The processor 401 is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interfaces, voltage regulation, power management and other control functions. The memory 402 can be used to store data used by the processor 401 when performing operations.

[0057] Another embodiment of the present invention relates to a computer-readable storage medium storing a computer program, which implements the above method embodiment when executed by a processor.

[0058] The embodiment of the present invention also provides a computer program product, including computer instructions, which, when executed by a processor, implement the above Figure 3 The various processes of the method embodiments shown in the figure can achieve the same technical effect. To avoid repetition, they will not be described here. That is, those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including a number of instructions to enable a device (which can be a single-chip microcomputer, chip, etc.) or a processor (processor) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program code.

[0059] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0060] Those skilled in the art will appreciate that the above embodiments are specific embodiments for implementing the present application, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A servo system, characterized in that: include: A position loop control module, a speed loop control module and a motor module connected in sequence; The position loop control module includes a position adjustment module, a speed feedforward compensator and a speed error device; the position adjustment module is used to generate a speed instruction according to the position instruction issued by the host computer and the feedback position of the motor module; The speed feedforward compensator is used to determine the compensation amount of the speed command according to the position command and the compensation formula; The speed error device is used to superimpose the compensation amount and the speed instruction as a target speed instruction; The speed loop control module is used to receive the target speed instruction and obtain the feedback speed of the servo motor in the motor module, and output an electromagnetic torque instruction according to the target speed instruction and the feedback speed to drive the servo motor to operate.

2. The servo system according to claim 1, characterized in that: The position adjustment module includes a position error device and a position proportional regulator connected in sequence; the position error device is used to obtain the position instruction and the feedback position, and determine the position following error according to the position instruction and the feedback position; The position proportional regulator is used to generate the speed instruction according to the position following error.

3. The servo system according to claim 2, characterized in that: The speed loop control module includes: a speed PI regulator, an electromagnetic torque error device and a speed feedback proportional gain module; The speed PI regulator is used to obtain the target speed instruction and adjust the target speed instruction to output the adjustment result; The speed feedback proportional gain module is used to obtain the feedback speed and output a gain according to the feedback speed; The electromagnetic torque error device determines and outputs the electromagnetic torque instruction according to the adjustment result and the gain.

4. The servo system according to claim 3, characterized in that: The motor module comprises: the servo motor and a speed integrator; The servo motor is used to perform a rotation operation according to the electromagnetic torque instruction; the speed integrator is used to generate the feedback position according to the feedback speed of the servo motor.

5. The servo system according to claim 4, characterized in that: The compensation formula is: Where, G(s) is the speed feedforward compensator, J s is the system inertia, K v is the speed loop gain constant, and s is the Laplace operator.

6. The servo system according to claim 1, characterized in that: The servo system further comprises: a disturbance torque adder; The disturbance torque adder is used to obtain the electromagnetic torque command and the load torque, and output the difference / sum between the electromagnetic torque command and the load torque as a target torque command instead of the electromagnetic torque command to the motor module to drive the servo motor.

7. A motor control method based on a servo system, applied to the servo system according to claims 1-6, characterized in that: The method comprises: Obtaining the position command issued by the host computer and the feedback position of the servo motor, and calculating the speed command according to the position command and the feedback position; Calculating a compensation amount of the speed command according to the position command and the compensation formula, and superimposing the compensation amount and the speed command as a target speed command; Acquiring a feedback speed of the servo motor, and calculating an electromagnetic torque command according to the target speed command and the feedback speed; The electromagnetic torque instruction is used to drive the servo motor to perform operation.

8. An electronic device comprising: A processor, a memory, and a program stored in the memory and executable on the processor, wherein when the program is executed by the processor, the steps of the motor control method based on the servo system as claimed in claim 7 are implemented.

9. A computer-readable storage medium, characterized in that: A computer program is stored on the computer-readable storage medium, and when the computer program is executed by the processor, the steps in the motor control method based on the servo system as claimed in claim 7 are implemented.

10. A computer program product, characterized in that The method comprises computer instructions, which implement the steps of the motor control method based on the servo system as claimed in claim 7 when the computer instructions are executed by a processor.

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