System Development Based On Radian Laser Tracker And The Research Of Robot Spatial Error Analysis And Compensation

With the development of science and technology and the need of industrial upgrading,the demand for industrial robots is increasing year by year.The trend of "machine replacement" is becoming more and more obvious.At present,one of the main obstacles to the large-scale commercial application of robots is that its absolute positioning accuracy is difficult to meet application requirements.Therefore,we started with the research of robot calibration method,and sought a solution to improve the absolute positioning accuracy of robot by analyzing the spatial distribution of robot pose errors.Main researches of this paper content include:(1)Realization one-key calibration by secondary development of the Radian laser tracker.Laser tracker is an important measuring device for robot calibration.In order to establish the control mechanism between the tracker and the upper computer of the robot,the Radian laser tracker of API company was programmed for secondary development to realize one-key calibration,so as to facilitate the calibration of the robot by the laser tracker and improve the detection efficiency.(2)The indirect compensation methods of industrial robots were analyzed and studied.According to the kinematic model of the robot,the mapping relation between forward and inverse kinematics was deduced.In addition,the kinematic parameter errors were identified based on Newton iteration method.Indirect compensation methods,such as differential error compensation and Newton-Raphson,were compared and analyzed.The results show that the accuracy of differential error compensation is higher.(3)The research of spatial error distribution of robots based on error influencing factors.Based on the kinematic error model of robot,the error influencing factors were found which are used as the evaluation index of the continuous working space errors.Based on the error modeling of the kinematic parameters that affect the robot’s positioning accuracy,this method used the principle of matrix norm inequality to determine the influence of the extended jacobian matrix on the robot’s terminal error,and took its conditional number as the error influencing factor to judge the influence degree of the robot’s spatial error.A single factor error model was established for joint rotation angle,link length,link offset distance and joint twist angle,and then the composition of the expanded jacobian matrix and the spatial distribution of the influencing factors were analyzed.Finally,measures were taken to reduce the errors.The method was applied to the spatial error distribution of kawasaki RS010 N industrial robot to determine the optimal working space.(4)Research on the parameter error optimization compensation method of robot inverse kinematics.Aiming at the low precision of direct compensation of ten parameters in the existing kinematics,a method of parameter error optimization compensation in inverse kinematics was proposed.In this method,the joint angle was calculated by the inverse kinematics which only compensated ten parameters directly and was used as the initial value of the iteration,and the angle calculated by the full parameters compensated the forward kinematics as the destination angle,and set up a set of differential equations composed of attitude matrix and position vector.Newton iteration method was used to solve the error joint angle of each joint,so that the joint angle calculated by direct compensation tend to the target value.The simulation results in MATLAB environment show that the method of parameter error optimization compensation in inverse kinematics could effectively improve the accuracy of robot inverse kinematics.