A static balance torque compensation method and device

Abstract

The present application discloses a static balancing torque compensation method and device. First, when the static balancing torque compensation switch is turned on, a first static balancing torque compensation value is obtained; second, when the servo motor is turned on and the brake of the servo motor is not released, the first static balancing torque compensation value is used as the feedforward input of the current loop of the servo driver; after the brake of the servo motor is released, the first static balancing torque compensation value is adjusted, and the speed of the servo motor is monitored; when the acceleration of the speed of the servo motor is greater than a first threshold, the adjustment of the first static balancing torque compensation value is stopped, and the current first static balancing torque compensation value is used as the second static balancing torque compensation value; wherein the second static balancing torque compensation value is the static balancing torque compensation value of the servo driver this time; finally, based on the second static balancing torque compensation value, the static balancing torque of the servo driver is compensated.

Description

Technical Field

[0001] The present application relates to the field of robotics technology, and in particular to a static balancing torque compensation method and device. Background Art

[0002] When completing a specific task, the robot system usually needs to achieve posture changes through the coordinated actions of various joints. In this process, the joints of the robot system not only need to overcome their own gravity to do work, but also need to overcome the unbalanced torque generated by the weight of the mechanical components. Especially at the moment of enabling, due to the effect of gravity, the end of the robot may fall (commonly known as the "nodding phenomenon"), which may cause damage to the device.

[0003] At present, to enable instantaneous static balance torque compensation, it is necessary to determine the accurate gravity torque value of each position. However, due to the nonlinearity of the robot system, joint flexibility, and various uncertain factors such as load state, it is impossible to accurately estimate the magnitude of gravity torque at each position. The method of obtaining gravity torque by identifying system parameters usually has timeliness issues, and it is necessary to sacrifice the real-time performance of the system to a certain extent.

[0004] In the related art, the Chinese invention patent "A static balance torque adaptive compensation method, device and storage medium" with publication number CN112511057B determines whether to enable and compensate according to the motor torque feedback value, which can achieve compensation at the moment of enabling and reduce the nodding phenomenon at the moment of enabling. The Chinese invention patent "A gravity compensation method, device, storage medium and robot" with publication number CN108972626A obtains the model parameters and load parameters of the robot, and outputs the gravity compensation value according to the above parameters before starting and enabling and when the brake is not opened.

[0005] However, the Chinese invention patent with publication number CN112511057B calculates the static balance torque compensation value before enabling, and performs first-order low-pass filtering on the original feedback torque in real time, which is not suitable for the working condition where the motor torque changes rapidly during the enabling process, and there are errors in the compensation value under different motion postures, and the nodding phenomenon cannot be completely avoided; the Chinese invention patent with publication number CN108972626A needs to re-enter the model parameters every time the robot posture changes, which increases the complexity of the operation and reduces the real-time performance of the system. At the same time, the calculation of the compensation value is greatly affected by the model parameters. It can be seen that the existing static balance torque compensation method has poor real-time performance and poor compensation effect. Summary of the invention

[0006] To this end, the present application provides a static balancing torque compensation method and device to solve the problems of poor real-time performance and poor compensation effect of the static balancing torque compensation method in the prior art.

[0007] In order to achieve the above objectives, this application provides the following technical solutions:

[0008] In a first aspect, a static balancing torque compensation method is provided, the method comprising:

[0009] When the static balancing torque compensation switch is turned on, obtaining a first static balancing torque compensation value; wherein the first static balancing torque compensation value is the static balancing torque of the servo drive when the servo motor was turned on last time;

[0010] When the servo motor is turned on and the holding brake of the servo motor is not released, using the first static balance torque compensation value as a feedforward input of the current loop of the servo drive;

[0011] After the holding brake of the servo motor is released, adjusting the first static balancing torque compensation value and monitoring the rotation speed of the servo motor;

[0012] When the acceleration of the rotation speed of the servo motor is greater than a first threshold, the adjustment of the first static balance torque compensation value is stopped, and the current first static balance torque compensation value is used as the second static balance torque compensation value; wherein the second static balance torque compensation value is the static balance torque compensation value of the servo drive this time;

[0013] The static balancing torque of the servo drive is compensated based on the second static balancing torque compensation value.

[0014] In the above solution, optionally, adjusting the first static balancing torque compensation value and monitoring the rotation speed of the servo motor includes:

[0015] Performing positive increasing adjustment on the first static balancing torque compensation value, and monitoring the rotation speed of the servo motor;

[0016] When the rotation speed of the servo motor is less than a second threshold, stopping the positive increase adjustment of the first static balancing torque compensation value;

[0017] When the acceleration of the rotation speed of the servo motor is greater than the third threshold value, the first static balancing torque compensation value after positive adjustment is reversely increased and adjusted, and the rotation speed of the servo motor is monitored.

[0018] In the above solution, optionally, after taking the current first static balance torque compensation value as the second static balance torque compensation value, the method further includes:

[0019] When the servo motor is turned off, a current feedback value of the servo motor at a current moment is obtained, and the current feedback value at the current moment is stored.

[0020] In the above scheme, optionally, when adjusting the first static balance torque compensation value, the difference between the third static balance torque compensation value and the fourth static balance torque compensation value is less than the set difference; wherein the third static balance torque compensation value and the fourth static balance torque compensation value are the static balance torque compensation values ​​corresponding to two adjacent adjustments during the adjustment process of the first static balance torque compensation value.

[0021] In the above solution, optionally, before obtaining the first static balance torque compensation value when the static balance torque compensation is turned on, the method further includes:

[0022] The static balancing torque compensation switch is controlled to be turned on.

[0023] In the above solution, optionally, the method further includes:

[0024] After the holding brake of the servo motor is released, if the servo motor meets a preset condition, the holding brake of the servo motor is controlled and the PWM output of the servo motor is blocked.

[0025] In the above solution, optionally, the preset condition includes at least one of the following:

[0026] The current running distance of the servo motor is greater than the safe running distance of the servo motor;

[0027] The current speed of the servo motor is greater than the preset speed of the servo motor;

[0028] The acceleration of the servo motor is greater than a preset acceleration of the servo motor.

[0029] In a second aspect, a static balancing torque compensation device is provided, characterized in that the device comprises:

[0030] An acquisition module, used for acquiring a first static balance torque compensation value when the static balance torque compensation switch is turned on; wherein the first static balance torque compensation value is the static balance torque of the servo drive when the servo motor is turned on last time;

[0031] A first control module, configured to use the first static balance torque compensation value as a feedforward input of a current loop of the servo driver when the servo motor is turned on and the brake of the servo motor is not released;

[0032] an adjusting module, configured to adjust the first static balancing torque compensation value and monitor the rotation speed of the servo motor after the holding brake of the servo motor is released;

[0033] A second control module is used to stop adjusting the first static balance torque compensation value when the acceleration of the rotation speed of the servo motor is greater than a first threshold value, and use the current first static balance torque compensation value as the second static balance torque compensation value; wherein the second static balance torque compensation value is the static balance torque compensation value of the servo drive this time;

[0034] A compensation module is used to compensate the static balancing torque of the servo drive based on the second static balancing torque compensation value.

[0035] Compared with the prior art, this application has at least the following beneficial effects:

[0036] A static balancing torque compensation method provided in an embodiment of the present application comprises the following steps: first, when the static balancing torque compensation switch is turned on, a first static balancing torque compensation value is obtained; wherein the first static balancing torque compensation value is the previous static balancing torque compensation value of the servo drive; secondly, when the servo motor is turned on and the brake of the servo motor is not released, the first static balancing torque compensation value is used as the feedforward input of the current loop of the servo drive; after the brake of the servo motor is released, the first static balancing torque compensation value is adjusted, and the rotation speed of the servo motor is monitored; when the acceleration of the rotation speed of the servo motor is greater than a first threshold, the adjustment of the first static balancing torque compensation value is stopped, and the current first static balancing torque compensation value is used as the second static balancing torque compensation value; wherein the second static balancing torque compensation value is the static balancing torque compensation value of the servo drive this time; finally, based on the second static balancing torque compensation value, the static balancing torque of the servo drive is compensated. In the present application, when the servo motor is turned on and the brake is not released, the first static balance torque compensation value saved last time is read as a feedforward input to ensure that the motor does not produce unnecessary movement due to the influence of gravity before the brake is released, thereby avoiding the risk of the robot arm falling; after the brake of the servo motor is released, the first static balance torque compensation value is adjusted and the speed of the servo motor is monitored in real time to ensure that the dynamic adjustment of the compensation value can adapt to the current working conditions, improve the accuracy of the compensation value, and ensure the smooth operation of the servo motor; in the process of monitoring the acceleration of the servo motor speed, when the acceleration exceeds the set first threshold value, the adjustment of the compensation value is stopped, and the compensation value at this time is used as the second static balance torque compensation value, which is further used for the static balance torque compensation of this servo drive, thereby ensuring the response speed and accuracy of the servo system, good real-time performance, and good compensation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more intuitively illustrate the prior art and the present application, exemplary drawings are given below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing the present application; for example, those skilled in the art are capable of easily making conventional adjustments or further optimizations to the addition / reduction / attribution division, specific shapes, positional relationships, connection methods, dimensional ratios, etc. of certain units (components) based on the technical concepts and exemplary drawings disclosed in the present application.

[0038] Figure 1 A schematic flow chart of a static balancing torque compensation method provided in an embodiment of the present application;

[0039] Figure 2 A schematic diagram of the relationship between a first static balancing torque compensation value and a current loop of a servo drive provided in an embodiment of the present application. DETAILED DESCRIPTION

[0040] The present application is further described below in detail through specific embodiments in conjunction with the accompanying drawings.

[0041] In the description of this application: unless otherwise specified, the meaning of "plurality" is two or more. The terms "first", "second", "third", etc. in this application are intended to distinguish the objects referred to, and do not have special meanings in terms of technical connotations (for example, they should not be understood as emphasizing the importance or order, etc.). Expressions such as "including", "comprising", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

[0042] The terms such as "upper", "lower", "left", "right", "middle", etc. cited in this application are usually used to indicate the general relative position relationship for the purpose of intuitive understanding by referring to the drawings, and are not absolute limitations on the position relationship in the actual product.

[0043] It should be understood that the servo system, servo drive and servo motor are three closely related components in industrial automation and control systems, which together constitute a complete servo control system.

[0044] The servo system is a closed-loop control system used to accurately control position, speed, and torque. It is usually used in applications that require high precision and high response speed, such as robots, CNC machine tools, and automated production lines.

[0045] A servo system usually consists of a controller, a servo drive, a servo motor, and a feedback device. The controller is used to generate target instructions (such as position, speed, or torque) and send them to the servo drive; the servo drive is used to adjust the operation of the servo motor according to the controller's instructions; the servo motor is used to execute the controller's instructions and achieve mechanical movement by rotating; the feedback device is used to monitor the operating status of the servo motor in real time and feed it back to the controller. The feedback device can be, for example, an encoder or a resolver.

[0046] The servo drive is a key component in the servo system, responsible for receiving instructions from the controller and adjusting the current, voltage and frequency of the servo motor to precisely control the movement of the motor.

[0047] The servo drive is used to receive command signals from the controller (such as position, speed or torque commands), and is also used to adjust the drive current and voltage of the motor to achieve precise control. It is also used to implement multi-layer closed-loop control such as current loop, speed loop and position loop, and is also used to monitor and protect the motor to prevent overload, overheating and other faults.

[0048] The servo motor is the actuator in the servo system, which can accurately perform rotational motion according to the control of the servo drive to achieve the required mechanical output.

[0049] The servo motor is used to receive the current and voltage provided by the servo driver, generate corresponding torque and speed, and is also used to achieve high-precision position and speed control. It is also used to provide real-time position information and speed information to the driver and controller through feedback devices (such as encoders).

[0050] In short, the servo system sends instructions through the controller, the servo driver adjusts the operation of the servo motor, the servo motor performs specific movements, and is monitored and adjusted in real time through the feedback device to achieve the accuracy and stability of closed-loop control.

[0051] It should be understood that the current loop of the servo drive is an important closed-loop control link in the servo control system, which is mainly responsible for accurately controlling the current (or torque) of the servo motor. In the servo system, the current loop is usually the innermost control loop, and the outer layer may include the speed loop and the position loop. The main function of the current loop is to quickly and accurately adjust the drive current of the motor according to the given current command to achieve the required motor torque.

[0052] The current loop receives the current command signal from the speed loop or the position loop, which indicates the driving current (or torque) currently required by the motor.

[0053] The current sensor detects the actual current value of the motor in real time and feeds the detection signal back to the current loop controller.

[0054] The current loop controller compares the current command value with the actual current value and calculates an error signal (ie, the difference between the command current and the actual current).

[0055] Through the PI (proportional-integral) or PID (proportional-integral-differential) control algorithm, the current loop controller calculates the required control voltage based on the error signal to adjust the drive current of the motor.

[0056] The current loop controller outputs a control signal to the power amplifier to adjust the drive voltage or current of the motor so that the actual current quickly follows the command current.

[0057] The current loop has the characteristics of fast response and can complete current regulation in a very short time (usually milliseconds or faster). Its main goal is to ensure that the motor can maintain stable torque output under changing load conditions.

[0058] In a servo drive, the implementation of the current loop usually involves a current sensor, a PI / PID controller, a PWM modulator, and a power amplifier. The current sensor is used to measure the actual current value of the motor in real time. Common current sensors include Hall effect sensors and shunt resistors. The PI / PID controller is used to calculate the regulation signal based on the measured current error signal using the PI or PID control algorithm. The PWM modulator is used to convert the regulation signal output by the controller into a PWM (pulse width modulation) signal for driving the motor, and to control the driving voltage and current of the motor by adjusting the PWM duty cycle. The power amplifier is used to amplify the PWM signal to the current and voltage levels required to drive the motor.

[0059] like Figure 1 and Figure 2 As shown, a static balancing torque compensation method is provided, the method comprising:

[0060] When the static balancing torque compensation switch is turned on, obtaining a first static balancing torque compensation value; wherein the first static balancing torque compensation value is the static balancing torque of the servo drive when the servo motor was turned on last time;

[0061] When the servo motor is turned on and the holding brake of the servo motor is not released, using the first static balance torque compensation value as a feedforward input of the current loop of the servo drive;

[0062] After the holding brake of the servo motor is released, adjusting the first static balancing torque compensation value and monitoring the rotation speed of the servo motor;

[0063] When the acceleration of the rotation speed of the servo motor is greater than a first threshold, the adjustment of the first static balance torque compensation value is stopped, and the current first static balance torque compensation value is used as the second static balance torque compensation value; wherein the second static balance torque compensation value is the static balance torque compensation value of the servo drive this time;

[0064] The static balancing torque of the servo drive is compensated based on the second static balancing torque compensation value.

[0065] This embodiment relates to a static balancing torque compensation method, which aims to solve the problem that the mechanical arm may fall due to gravity at the moment of enabling in the servo system. Through a series of steps, this method can effectively perform feedforward input compensation on the current loop of the servo drive, thereby smoothly controlling the movement of the servo motor. The specific technical effects are as follows:

[0066] Prevent the robot arm from falling: When the servo motor is turned on and the brake is not released, the first static balance torque compensation value saved last time is read as the feedforward input to ensure that the motor does not produce unnecessary movement due to gravity before the brake is released, thereby avoiding the risk of the robot arm falling.

[0067] Dynamic adjustment of compensation value: After the servo motor's brake is released, the first static balance torque compensation value is adjusted and the servo motor's speed is monitored in real time to ensure that the dynamic adjustment of the compensation value can adapt to the current working conditions. This process improves the accuracy of the compensation value and ensures the smooth operation of the servo motor.

[0068] Real-time monitoring and adjustment: When the acceleration of the servo motor speed is monitored, when the acceleration exceeds the set first threshold, the compensation value is stopped from being adjusted, and the compensation value at this time is used as the second static balance torque compensation value, which is further used for the static balance torque compensation of the servo drive. This real-time monitoring and adjustment mechanism ensures the response speed and accuracy of the system and improves the stability of the system.

[0069] Memory and update of compensation value: By saving and updating the static balance torque compensation value in the servo drive, it is ensured that compensation can be performed based on the last compensation result each time the system is turned on, reducing the adjustment time each time the system is started and improving the system efficiency and user experience.

[0070] This embodiment effectively prevents the drop phenomenon at the moment of enabling by applying the first static balancing torque compensation value when the servo motor is turned on and the brake is not released; it can overcome the nonlinearity and uncertainty of the system to a certain extent and improve the accuracy of compensation by real-time monitoring and dynamic adjustment of the compensation value; by using the compensation value stored in the memory as the initial compensation input and dynamically adjusting the compensation value during actual operation, the calculation and adjustment time is reduced and the real-time performance of the system is improved; by controlling the compensation value change within the cycle to be very small and combining it with low-pass filtering processing, the smooth operation of the motor is ensured, sudden acceleration and deceleration is avoided, and the stability and smooth operation of the system are improved.

[0071] In summary, this embodiment realizes effective compensation for the static balance torque of the servo drive, thereby solving the drop problem, nonlinearity and uncertainty problem and real-time problem of the servo system at the moment of enabling proposed in the background technology, and improving the stability and accuracy of the system.

[0072] In this embodiment, the step of adjusting the first static balancing torque compensation value and monitoring the rotation speed of the servo motor includes:

[0073] Performing positive increasing adjustment on the first static balancing torque compensation value, and monitoring the rotation speed of the servo motor;

[0074] When the rotation speed of the servo motor is less than a second threshold, stopping the positive increase adjustment of the first static balancing torque compensation value;

[0075] When the acceleration of the rotation speed of the servo motor is greater than the third threshold value, the first static balancing torque compensation value after positive adjustment is reversely increased and adjusted, and the rotation speed of the servo motor is monitored.

[0076] It should be noted that the second threshold and the third threshold can be set by the staff themselves, and this embodiment does not make any specific limitation on this.

[0077] For example, the second threshold may be 0.01.

[0078] It should be noted that when the rotation speed of the servo motor is less than the second threshold, that is, it is considered that the rotation speed of the servo motor approaches 0, the positive increase adjustment of the first static balancing torque compensation value is stopped and the current compensation value c1 is recorded.

[0079] If the acceleration of the servo motor's rotation speed is greater than the second threshold, resulting in the forward direction (step 1) stopping increasing, the compensation value (step 2) is reduced until the speed approaches 0. The servo start compensation process is considered to be completed, and the compensation value c2 at this time is recorded.

[0080] During the entire servo-on process, determine whether the robot posture changes; if the posture changes, update the compensation value C2 at this time in real time; and when the servo is turned off, save the compensation value C2 to the memory.

[0081] In this embodiment, after taking the current first static balance torque compensation value as the second static balance torque compensation value, the method further includes:

[0082] When the servo motor is turned off, a current feedback value of the servo motor at a current moment is obtained, and the current feedback value at the current moment is stored.

[0083] In this embodiment, when the first static balance torque compensation value is adjusted, the difference between the third static balance torque compensation value and the fourth static balance torque compensation value is less than the set difference; wherein the third static balance torque compensation value and the fourth static balance torque compensation value are the static balance torque compensation values ​​corresponding to two adjacent adjustments during the adjustment process of the first static balance torque compensation value.

[0084] In this embodiment, before obtaining the first static balance torque compensation value when the static balance torque compensation is turned on, the method further includes:

[0085] The static balancing torque compensation switch is controlled to be turned on.

[0086] In this embodiment, the method further includes:

[0087] After the holding brake of the servo motor is released, if the servo motor meets a preset condition, the holding brake of the servo motor is controlled and the PWM output of the servo motor is blocked.

[0088] In this embodiment, the preset condition includes at least one of the following:

[0089] The current running distance of the servo motor is greater than the safe running distance of the servo motor;

[0090] The current speed of the servo motor is greater than the preset speed of the servo motor;

[0091] The acceleration of the servo motor is greater than a preset acceleration of the servo motor.

[0092] In one embodiment, a static balancing torque compensation device is provided, characterized in that the device comprises:

[0093] An acquisition module, used for acquiring a first static balance torque compensation value when the static balance torque compensation switch is turned on; wherein the first static balance torque compensation value is the static balance torque of the servo drive when the servo motor is turned on last time;

[0094] A first control module, configured to use the first static balance torque compensation value as a feedforward input of a current loop of the servo driver when the servo motor is turned on and the brake of the servo motor is not released;

[0095] an adjusting module, configured to adjust the first static balancing torque compensation value and monitor the rotation speed of the servo motor after the holding brake of the servo motor is released;

[0096] A second control module is used to stop adjusting the first static balance torque compensation value when the acceleration of the rotation speed of the servo motor is greater than a first threshold value, and use the current first static balance torque compensation value as the second static balance torque compensation value; wherein the second static balance torque compensation value is the static balance torque compensation value of the servo drive this time;

[0097] A compensation module is used to compensate the static balancing torque of the servo drive based on the second static balancing torque compensation value.

[0098] The technical features of the above embodiments may be arbitrarily combined (as long as there is no contradiction in the combination of these technical features). To make the description concise, not all possible combinations of the technical features in the above embodiments are described; these embodiments that are not explicitly written should also be considered to be within the scope of this specification.

Claims

1. A static balancing torque compensation method, characterized in that: The method comprises: When the static balancing torque compensation switch is turned on, obtaining a first static balancing torque compensation value; wherein the first static balancing torque compensation value is the static balancing torque of the servo drive when the servo motor was turned on last time; When the servo motor is turned on and the holding brake of the servo motor is not released, using the first static balance torque compensation value as a feedforward input of the current loop of the servo drive; After the holding brake of the servo motor is released, adjusting the first static balancing torque compensation value and monitoring the rotation speed of the servo motor; When the acceleration of the rotation speed of the servo motor is greater than a first threshold, the adjustment of the first static balance torque compensation value is stopped, and the current first static balance torque compensation value is used as the second static balance torque compensation value; wherein the second static balance torque compensation value is the static balance torque compensation value of the servo drive this time; Based on the second static balancing torque compensation value, compensating the static balancing torque of the servo drive; When adjusting the first static balance torque compensation value, the difference between the third static balance torque compensation value and the fourth static balance torque compensation value is less than the set difference; wherein the third static balance torque compensation value and the fourth static balance torque compensation value are the static balance torque compensation values ​​corresponding to two adjacent adjustments during the adjustment process of the first static balance torque compensation value.

2. The method according to claim 1, characterized in that The step of adjusting the first static balance torque compensation value and monitoring the rotation speed of the servo motor includes: Performing positive increasing adjustment on the first static balancing torque compensation value, and monitoring the rotation speed of the servo motor; When the rotation speed of the servo motor is less than a second threshold, stopping the positive increase adjustment of the first static balancing torque compensation value; When the acceleration of the rotation speed of the servo motor is greater than the third threshold value, the first static balancing torque compensation value after positive adjustment is reversely increased and adjusted, and the rotation speed of the servo motor is monitored.

3. The method according to claim 1, characterized in that After taking the current first static balance torque compensation value as the second static balance torque compensation value, the method further includes: When the servo motor is turned off, a current feedback value of the servo motor at a current moment is obtained, and the current feedback value at the current moment is stored.

4. The method according to claim 1, characterized in that: Before obtaining the first static balance torque compensation value when the static balance torque compensation is turned on, the method further includes: The static balancing torque compensation switch is controlled to be turned on.

5. The method according to claim 1, characterized in that: The method further comprises: After the holding brake of the servo motor is released, if the servo motor meets a preset condition, the holding brake of the servo motor is controlled and the PWM output of the servo motor is blocked.

6. The method according to claim 5, characterized in that The preset condition includes at least one of the following: The current running distance of the servo motor is greater than the safe running distance of the servo motor; The current speed of the servo motor is greater than the preset speed of the servo motor; The acceleration of the servo motor is greater than a preset acceleration of the servo motor.

7. A static balancing torque compensation device, characterized in that: The device comprises: An acquisition module, used for acquiring a first static balance torque compensation value when the static balance torque compensation switch is turned on; wherein the first static balance torque compensation value is the static balance torque of the servo drive when the servo motor is turned on last time; A first control module, configured to use the first static balance torque compensation value as a feedforward input of a current loop of the servo driver when the servo motor is turned on and the brake of the servo motor is not released; an adjusting module, configured to adjust the first static balancing torque compensation value and monitor the rotation speed of the servo motor after the holding brake of the servo motor is released; A second control module is used to stop adjusting the first static balance torque compensation value when the acceleration of the rotation speed of the servo motor is greater than a first threshold value, and use the current first static balance torque compensation value as the second static balance torque compensation value; wherein the second static balance torque compensation value is the static balance torque compensation value of the servo drive this time; A compensation module, configured to compensate the static balancing torque of the servo drive based on the second static balancing torque compensation value; When adjusting the first static balance torque compensation value, the difference between the third static balance torque compensation value and the fourth static balance torque compensation value is less than the set difference; wherein the third static balance torque compensation value and the fourth static balance torque compensation value are the static balance torque compensation values ​​corresponding to two adjacent adjustments during the adjustment process of the first static balance torque compensation value.

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