Positional Error Compensation Technology For Industrial Robot Based On Spatial Similarity

The positional accuracy of the riveting hole is an important technical index in aircraft component assembly,so the robot error compensation technology is the key technology to improve the absolute accuracy of the robots and ensure the drilling accuracy of the automatic drilling and riveting system.In this paper,the positional error compensation technology for industrial robot based on spatial similarity is researched.Based on the robot kinematic error model,the robot error similarity is analyzed,researched and verified for error compensation;A robot positional error estimation and compensation model based on error similarity is built,and the robot's absolute positional accuracy is significantly improved;An optimal sample model is built for error compensation,and a multi-objective optimization method based on genetic algorithm is proposed to solve the optimal sample sets,which effectively improved the samples' distribution rationality and sampling efficiency;A comprehensive compensation method for maintaining the automatic drilling coordination accuracy is proposed and verified,so that the highprecision drilling of the robotic drilling and riveting system is realized.The main work of this paper is as follows:(1)Establish the robot kinematic model with joint constraints and the robot error model with the MD-H parameters,which provides a theoretical basis for the study of error similarity: The robot forward kinematic model is established with D-H parameters,and the robot inverse kinematic model is established with joint constraints,which implements the unique mapping of the joint space and the operation space;The robot kinematic error model is established with MD-H parameters,and the robot kinematic parameter calibration method is introduced.(2)Propose and verify the robot positional error estimation and feed-forward compensation method,and realize the open-loop compensation for the robot's absolute positional errors: The robot positional error similarity theory is analyzed and verified,and the quantitative representation model of error similarity is established with robot error model and variogram function;The robot positional error mapping method and optimal linear unbiased estimation method based on error similarity is proposed to estimate the robot's positional error;Based on error similarity,a positional error feedforward compensation method is proposed to compensate the positional errors;Experiments show that the proposed methods can improve the robot's absolute accuracy by approximately 80%.(3)Establish the optimal sample model for error compensation,propose and verified the multiobjective optimization method of robot samples based on genetic algorithm: As the existing sample optimization method based on observability does not apply to the error compensation method without parameter calibration,a mathematical model of the robot optimal samples for error compensation is established;To solve the mathematical model,a multi-objective optimization method of robot samples based on genetic algorithm is proposed,and the optimal sample set is solved;The contrast experiments show that the optimal sample can effectively improve the samples' distribution rationality and sampling efficiency of the error compensation.(4)Propose and verify the comprehensive compensation method for maintaining the automatic drilling coordination accuracy,and apply the robot error compensation method to robotic drilling system: The hardware and software system and the working principle of the robotic drilling system are introduced.Based on the analysis of the coordination errors of the robotic drilling system,the comprehensive compensation method for maintaining the automatic drilling coordination accuracy is proposed;Drilling experiments show that the drilling accuracy of the robotic drilling system can reach0.35 mm.