CN-122008220-A - Friction compensation method and system for full working stroke of robot linear joint module

CN122008220ACN 122008220 ACN122008220 ACN 122008220ACN-122008220-A

Abstract

The invention discloses a friction compensation method and a system for a full working stroke of a robot linear joint module, which belong to the technical field of robot control, wherein the method comprises the steps of establishing an improved nonlinear friction model of the robot linear joint module; the method comprises the steps of segmenting the working stroke position of a linear joint module, calibrating static friction parameters, pre-sliding friction parameters and sliding friction parameters of different positions of the working stroke in a calibration mode, fitting nonlinear friction force models of different working stroke positions according to calibration results, storing model parameters, automatically calculating friction compensation quantity according to the running position and speed of the current linear joint module and combining the model parameters in the working mode, and carrying out friction compensation by utilizing the friction compensation quantity. The invention solves the problems of model mismatch and poor compensation precision caused by inconsistent full-stroke friction characteristics in the prior art, realizes fine and self-adaptive friction compensation, and effectively improves the control precision and the robustness of the linear joint module.

Inventors

YUAN CHENG
WU GUICHENG
CHEN WEI
MENG LINGHUI
WANG HAO

Assignees

四川航天烽火伺服控制技术有限公司

Dates

Publication Date: 20260512
Application Date: 20260313

Claims (9)

1. The friction compensation method for the full working stroke of the robot linear joint module is characterized by comprising the following steps of: s1, establishing an improved nonlinear friction model of a robot linear joint module; S2, segmenting the working stroke position of the linear joint module; S3, calibrating static friction parameters of different positions of the working stroke in a calibration mode; S4, calibrating pre-sliding friction parameters at different positions of the working stroke in a calibration mode; s5, calibrating sliding friction parameters at different positions of the working stroke in a calibration mode; s6, fitting nonlinear friction force models at different working stroke positions based on the step S1 according to the calibration results of the steps S3 to S5, and storing model parameters; S7, under the working mode, automatically calculating the friction compensation quantity according to the running position and speed of the current linear joint module and combining the model parameters; s8, performing friction compensation by using the friction compensation quantity.
2. The friction compensation method for the full working stroke of the robot linear joint module according to claim 1, wherein the improved robot linear joint module nonlinear friction model introduces a low-speed detection dead zone on the basis of Karnopp models to avoid compensation direction shake around zero speed, and a cosine function is adopted to fit transition characteristics from static friction to sliding friction in a pre-sliding stage.
3. The friction compensation method for the full working stroke of the robot linear joint module according to claim 1, wherein in the step S2, the full working stroke L of the linear joint module is equally divided into N segments, and starting point positions of the segments are L n , n=0, 1.
4. The friction compensation method for full working stroke of a robot linear joint module according to claim 3, wherein the step S3 specifically comprises: Resetting the joint module to the position of l 0 , and sequentially recording the maximum torque current value and the corresponding speed of each segment from l 0 until the joint module runs a full stroke; And (3) static friction negative calibration, namely sequentially recording the maximum torque current value and the corresponding speed of each segment from the last segment until the position of the resetting point l 0 is returned.
5. The friction compensation method for full working stroke of a robot linear joint module according to claim 3, wherein step S4 specifically comprises: Resetting the joint module to the position of l 0 , and sequentially recording the torque current minimum value and the sliding friction boundary speed corresponding to the torque current minimum value between the segments from l 0 until the joint module runs a full stroke; And (3) pre-sliding friction negative calibration, namely sequentially recording the torque current minimum value between the segments from the last segment to the corresponding sliding friction boundary speed until the position of the restoring point l 0 is returned.
6. The friction compensation method for full working stroke of a robot linear joint module according to claim 3, wherein step S5 specifically comprises: Resetting the joint module to the position of l 0 , controlling the linear joint module to travel a complete stroke at constant speed at different speeds, and recording torque current values at different sections at different speeds; And (3) sliding friction negative calibration, namely starting from the last segment, controlling the linear joint module to respectively travel a complete stroke at constant speed at different speeds, and recording torque current values at different segments at different speeds.
7. The friction compensation method for the full working stroke of the robot linear joint module according to claim 1, wherein the formula fitted in the step S6 is as follows: Wherein, the The frictional force is indicated by the fact that, Indicating the current speed of the vehicle, Indicating the critical speed of the static friction, Indicating the sliding friction boundary velocity of the slide, Indicating the maximum static friction force of the steel plate, Indicating the minimum friction force during the pre-slip phase, Indicating coulomb friction.
8. The friction compensation method for full working stroke of a robot linear joint module according to claim 1, wherein step S8 specifically comprises: Collecting a speed loop following error value of a current linear joint module, and adjusting the magnitude of a friction compensation factor through the following error value; And determining the current friction compensation quantity according to the friction compensation factor and the current working stroke position of the linear joint module, and converting the friction compensation quantity into a torque current value to be compensated into a current loop reference signal of the linear joint module.
9. The utility model provides a friction compensation system of full working stroke of robot straight line joint module which characterized in that includes: the nonlinear friction model building module is used for building an improved nonlinear friction model of the robot linear joint module; The stroke position segmentation module is used for segmenting the working stroke position of the linear joint module; the calibration module is used for calibrating static friction parameters, pre-sliding friction parameters and sliding friction parameters of different positions of the working stroke in a calibration mode; the friction fitting module is used for fitting nonlinear friction models at different working stroke positions according to the calibration result of the calibration module and storing model parameters; the friction compensation amount calculating module is used for automatically calculating the friction compensation amount according to the running position and speed of the current linear joint module and the model parameters in a working mode; and the friction compensation module is used for carrying out friction compensation by utilizing the friction compensation quantity.

Description

Friction compensation method and system for full working stroke of robot linear joint module Technical Field The invention relates to the technical field of robot control, in particular to a friction compensation method and a system for a full working stroke of a robot linear joint module. Background Along with the continuous acceleration of the digital and intelligent transformation development of the equipment manufacturing industry in China, the robot industry has been widely applied in the fields of automobiles, medical treatment, aerospace and the like. The humanoid robot gradually becomes a core force for replacing manual work to perform simple and repeated work by virtue of the anthropomorphic body structure, accurate motion control, continuous and stable operation capability and the characteristic of mass replication. The linear joint module is used as a core execution device of the humanoid robot, and the performance of the linear joint module directly determines the accuracy and stability of the humanoid robot for executing the brain instruction. The linear joint module is generally composed of a frameless torque motor, a planetary ball/column screw pair, an integrated driving controller, a multi-circle absolute displacement sensor, a force sensor and the like. Because friction factors exist in a bearing, a screw pair and the like in the joint module, the control precision of the joint module is directly affected, and the problems of low-speed crawling, positioning errors, reverse jump, track movement deviation and the like are caused. In the face of this problem, practitioners use the following means to reduce or suppress the effects of friction, largely in three directions: ① The design of the screw pair transmission is improved, the machining precision of the screw pair is improved, better lubricant is selected, the lubricity between moving parts is enhanced, and the friction between the moving parts of the screw can be directly reduced. ② The control gain of the joint module is improved, and when non-following phenomena similar to low-speed crawling and the like occur, the controller can quickly respond, so that the influence caused by friction is reduced. ③ And compensating at the control end according to the friction characteristic of the joint module, namely calibrating in advance or fitting the friction characteristic curve of the joint module in a self-adaptive mode, and compensating in a control loop. The above method has the following problems: the first method is limited by objective factors such as process level, production cost, design margin and the like, and is difficult to use in actual scenes. While the second method can reduce the friction effect to some extent, too high gain may cause mechanical resonance problems and increase the operational noise of the joint module. The third method relies on the characteristics and parameters of the friction model being built. The friction characteristics of each point of the working stroke of the joint module are inconsistent, the problem that the model or the compensation parameters are easy to mismatch exists, the compensation is failed, and the performance and the stability of the joint module are reduced. Disclosure of Invention The invention aims to overcome the technical problems in the prior art and provides a friction compensation method and a system for a full working stroke of a robot linear joint module, wherein friction compensation parameters of each point in the full working stroke are automatically loaded by executing a no-load automatic calibration program, the friction compensation based on the working stroke is automatically carried out in normal operation, and meanwhile, compensation factors can be automatically optimized according to the following effect in the operation process so as to achieve the optimal compensation effect. The aim of the invention is realized by the following technical scheme: The invention provides a friction compensation method for a full working stroke of a robot linear joint module, which comprises the following steps: s1, establishing an improved nonlinear friction model of a robot linear joint module; S2, segmenting the working stroke position of the linear joint module; S3, calibrating static friction parameters of different positions of the working stroke in a calibration mode; S4, calibrating pre-sliding friction parameters at different positions of the working stroke in a calibration mode; s5, calibrating sliding friction parameters at different positions of the working stroke in a calibration mode; s6, fitting nonlinear friction force models at different working stroke positions based on the step S1 according to the calibration results of the steps S3 to S5, and storing model parameters; S7, under the working mode, automatically calculating the friction compensation quantity according to the running position and speed of the current linear joint module and combining the model parameters;