Research On Kinematic Error Modeling And Self-calibration Method Of 3-RRRU Parallel Robot

The kinematics error modeling of 3-RRRU parallel robot,the coupling relation between error sources and accuracy,and the self-calibration method of error are systematically studied.At present,there are few data about the error of 3-RRRU parallel robot,so this paper is to compensate the error of robot's error and improve the accuracy of terminal trajectory,so that robot can better accomplish the target task.The main work of this paper can be summarized as the following aspects.1?Basing on the mechanism of 3-RRRU parallel robot,the inverse kinematics model of robot is established by D-H method.The forward kinematics model is deduced by geometric vector method,and the kinematics model is simulated based on MATLAB platform to verify the correctness of the model.2?Focusing on the accuracy problem of 3-RRRU parallel robot,the error model of robot is deduced and established based on the kinematic positive solution model.The error of the robot link,the driving angle error and the processing error of the static and dynamic platforms on the control precision is analyzed in detail.The coupling relationship between the above error and the working precision of the robot is systematically analyzed.The simulation results show that when the driving angle error is 0.001°~0.01°,the first branch of the driving angle error influences the accuracy of the controlled terminal most,which is 84.2um.When the processing error of the rod is 0.01 mm ~ 0.1mm,the accuracy of the controlled terminal is greatly affected by the passive rod near the dynamic platform,and the maximum terminal error is 137.2um.Static and moving platform circumcircle radius of the machining error is set to 0.1mm,the maximum execution robot terminal error is 568.4um.Therefore,comparing the processing error source of the liner rod and the error source of the driving angle,The machining error of the bar is higher than the accuracy of the robot due to the angle error due to the multiple links and the multiple links.Besides,the terminal control precision of the robot is greatest influenced by the processing error of the circumscribed circle radius of the static and dynamic platform.This study provides the theoretical basis for the optimal design of the robot structure.3?An error self-calibration method is proposed based on genetic algorithm.The selection operator,crossover operator and mutation operator are optimized by mathematical statistics,and the convergence speed and speediness of the whole algorithm are improved.Based on the error model,the target optimization function is deduced and established.The calibration procedure and experiment steps are designed.The laser tracker is used to detect the data of the dynamic trajectory of the 3-RRRU parallel robot.The genetic algorithm is used to optimize the multi-population iterative optimization.The precision threshold is set up to obtain the error of the robot,and the error calibration and compensation work is finished.