CN-121989220-A - Control method and control system of mechanical arm

CN121989220ACN 121989220 ACN121989220 ACN 121989220ACN-121989220-A

Abstract

The invention provides a control method and a control system of a mechanical arm. The control method of the mechanical arm comprises the steps of outputting a first driving force by using a driver to control the mechanical arm to be positioned at a first position, and outputting a second driving force by using the driver to control the mechanical arm to be positioned at a second position. The second position is different from the first position. The control method also includes the first driving force and the second driving force respectively including an anti-friction force and a movement force. The anti-friction force is greater than the movement force. The control method also includes adjusting the second driving force by the control loop, the first position and the second position to control the mechanical arm. The first position and the second position are related to the friction force of the mechanical arm.

Inventors

LI QINGWEI
Lin Kuiyou
LAI JUNWEN

Assignees

达明机器人股份有限公司

Dates

Publication Date: 20260508
Application Date: 20241118
Priority Date: 20241104

Claims (12)

1. A method of controlling a robotic arm, comprising: The mechanical arm is controlled to be positioned at a first position by utilizing a driver to output a first driving force, the mechanical arm is controlled to be positioned at a second position by utilizing the driver to output a second driving force, the second position is different from the first position, the first driving force and the second driving force respectively comprise an anti-friction force and a movement force, the anti-friction force is larger than the movement force, and The second driving force is adjusted by a control loop, the first position and the second position to control the mechanical arm, wherein the first position and the second position are related to a friction force of the mechanical arm.
2. The control method of claim 1, further comprising: Receiving, by a controller, a command position information and an actual position information from a position encoder coupled to a joint motor as the driver; receiving a current moment command message and a previous moment command message from a speed controller by a gain adjustment module; calculating a moment command absolute difference between the current moment command information and the previous moment command information by the gain adjustment module, and comparing the moment command absolute difference with a counting threshold; When the moment command absolute difference value is smaller than the counting threshold value, obtaining a position absolute difference value of the command position information and the actual position information; comparing the absolute difference value of the position with a gain mapping curve by the gain adjusting module to obtain a current gain value, and The current gain value is updated to the control loop by the gain adjustment module.
3. The control method as set forth in claim 2, further comprising: when the absolute difference value of the moment command is larger than or equal to the counting threshold value, a counter is started to count by the gain adjustment module; Resetting the counter and taking the absolute difference of the position when the counting time is greater than two seconds, and When the counting time is less than or equal to two seconds, the counter keeps counting; wherein the count threshold is 0.5 times the rated torque of the articulation motor.
4. The control method according to claim 2, further comprising controlling the rotation state of the joint motor according to the current gain value and a torque absolute difference by means of a current controller; the absolute difference value of the moment is an absolute difference value between updated moment command information generated by the speed controller according to a speed absolute difference value and the current gain value and current moment information of the joint motor sensed by a current sensor; the absolute difference value of the speed is the absolute difference value between speed control information provided by the controller according to the current gain value and actual speed information generated by a speed calculator based on the actual position information.
5. The control method of claim 4 wherein the gain map is generated by: Setting a resolution of the position encoder; setting a first gain section, a second gain section and a third gain section of the control loop; The gain adjustment module calculates according to the resolution of the position encoder and the expressions of a gain dead zone position, a gain center position and a gain recovery position, and And forming the gain mapping curve by using the first gain section, the second gain section, the third gain section, the gain dead zone position, the gain center position and the gain recovery position.
6. The control method according to claim 5, wherein the gain ratio of the first gain section is 5, the gain ratio of the second gain section is 80, and the gain ratio of the third gain section is 1; wherein the gain dead zone position has a position pulse number of 3, the gain center position has a position pulse number of 0.00005 times the resolution, and the gain recovery position has a position pulse number of 0.00025 times the resolution.
7. A control system for a robotic arm, comprising: A driver for outputting a first driving force to control the mechanical arm to be at a first position, a second driving force to control the mechanical arm to be at a second position different from the first position, wherein the first driving force and the second driving force respectively comprise an anti-friction force and a movement force, the anti-friction force is larger than the movement force, and And the control loop adjusts the second driving force according to the first position and the second position to control the mechanical arm, wherein the first position and the second position are related to a friction force of the mechanical arm.
8. The control system of claim 7, further comprising: A controller coupled to a position encoder of the robot arm coupled to a joint motor as the driver, the controller being configured to receive a position absolute difference between a command position information and an actual position information provided by the position encoder; A speed controller coupled to the controller, the speed controller configured to generate a current moment command information and a previous moment command information, and The gain adjustment module is coupled to the controller, the speed controller and the position encoder, and is configured to receive the current moment command information, the previous moment command information and the position absolute difference value, calculate a moment command absolute difference value between the current moment command information and the previous moment command information, and compare the moment command absolute difference value with a counting threshold; When the moment command absolute difference is smaller than the counting threshold, the gain adjusting module is used for comparing the position absolute difference with a gain mapping curve to obtain a current gain value, and the gain adjusting module is used for updating the current gain value to the control loop.
9. The control system of claim 8, wherein when the absolute difference of the torque command is greater than or equal to the count threshold, a counter is started to count by the gain adjustment module; When the counting time is more than two seconds, resetting the counter and obtaining the absolute difference value of the position; wherein the counter keeps counting when the count time is less than or equal to two seconds; wherein the count threshold is 0.5 times the rated torque of the articulation motor.
10. The control system of claim 8, further comprising: A current controller coupled to the joint motor, the gain adjustment module and the speed controller, the current controller being configured to control the position of the joint motor according to the current gain value and a torque absolute difference value, and A speed calculator coupled to the position encoder and the speed controller, the speed calculator configured to generate an actual speed information based on the actual position information received from the position encoder; the absolute difference value of the moment is an absolute difference value between updated moment command information generated by the speed controller according to a speed absolute difference value and the current gain value and current moment information of the joint motor sensed by a current sensor of the mechanical arm; The absolute difference value of the speed is the absolute difference value between the speed control information provided by the controller according to the current gain value and the actual speed information generated by the speed calculator.
11. The control system of claim 10, wherein the gain mapping curve comprises: A first gain section, a second gain section and a third gain section generated by the gain adjustment module; a gain dead zone position, a gain center position and a gain recovery position generated by the gain adjustment module according to a resolution of the position encoder, and Mapping relation between the first gain section, the second gain section and the third gain section and the gain dead zone position, the gain center position and the gain recovery position.
12. The control system of claim 11, wherein the gain ratio of the first gain section is 5, the gain ratio of the second gain section is 80, and the gain ratio of the third gain section is 1; wherein the gain dead zone position has a position pulse number of 3, the gain center position has a position pulse number of 0.00005 times the resolution, and the gain recovery position has a position pulse number of 0.00025 times the resolution.

Description

Control method and control system of mechanical arm Technical Field The present invention relates to a control method and a control system for a mechanical arm, and more particularly, to a control method and a control system for a joint motor in a mechanical arm. Background As the development of the current automated production increases the demand of the mechanical arm, and the performance of the mechanical arm, such as the control technology of the mechanical arm, is also a place for each industry to ink. In order to improve the control accuracy of the robot arm, the known method adjusts the gain of the control according to the angular velocity. For example, when the angular velocity is less than the threshold value, the gain is reduced in a linear or curved manner for control purposes. However, such known techniques cannot handle the state of the robot arm when it is running at very low speed, moving in small steps, or stationary. Because in these states, the torque output by the joint motor is affected by the friction force, so that the mechanical arm swings back and forth or suddenly moves, resulting in reduced precision and performance of the mechanical arm, and thus problems of shutdown and factory shutdown due to mistaken touch of the mechanical arm may occur. Therefore, there is a strong need to improve the performance and accuracy of the robot arm under stationary and micro-motion conditions. Disclosure of Invention According to the control method and the control system of the mechanical arm provided by the embodiment of the invention, the absolute difference value of the moment command between the current moment command information and the previous moment command information is compared with the counting threshold value, and the absolute difference value of the position of the command position information and the actual position information is substituted into the gain mapping curve to obtain the current (new) gain value and update the current gain value to the controller, so that the control precision of the joint motor is improved when the mechanical arm is stationary and slightly moved, the performance of the mechanical arm is improved, and the problems of shutdown or factory shutdown and the like caused by the fact that the motion state of the mechanical arm mistakenly touches the safety threshold value are reduced. In addition, the control capability of friction force is improved, so that the influence of variability of mechanism components of the joint motor and the mechanical arm can be reduced. According to a first aspect of the present invention, a method for controlling a robot arm is provided. The control method comprises the steps of outputting a first driving force by a driver to control the mechanical arm to be positioned at a first position, and outputting a second driving force by the driver to control the mechanical arm to be positioned at a second position. The second position is different from the first position. The control method also includes the first driving force and the second driving force respectively including an anti-friction force and a movement force. The anti-friction force is greater than the movement force. The control method also includes adjusting the second driving force by the control loop, the first position and the second position to control the mechanical arm. The first position and the second position are related to the friction force of the mechanical arm. According to a second aspect of the present invention, a control system for a robot arm is presented. The control system comprises a driver, wherein the driver outputs a first driving force to control the mechanical arm to be positioned at a first position, and the driver outputs a second driving force to control the mechanical arm to be positioned at a second position. The second position is different from the first position. The first driving force and the second driving force respectively comprise anti-friction force and movement force. The anti-friction force is greater than the movement force. The control system also comprises a control loop for adjusting the second driving force according to the first position and the second position so as to control the mechanical arm. The first position and the second position are related to the friction force of the mechanical arm. Drawings In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanied with figures are described in detail below, wherein: FIG. 1 illustrates a functional block diagram of an example of a robotic arm and control system according to an embodiment of the invention. Fig. 2 shows a gain map plot of a control system according to an embodiment of the invention. Fig. 3A shows a graph comparing the movement speed of a joint motor according to an embodiment of the present invention with the movement speed of a known joint motor. Fig. 3B shows a comparison of a robot arm mo