Research On Measurement And Compensation Of Absolute Positioning Accuracry Of Industrial Robots

The repetitive positioning accuracy of today's industrial robots is generally high,while the absolute positioning accuracy is very low.As robot offline programming applications become more and more extensive,industrial robots are required to have higher absolute positioning accuracy.This paper takes the Xinsong SR4 C industrial robot as the object and discusses how to improve its absolute positioning accuracy as follows:Combined with the actual structural characteristics of the Xinsong SR4 C robot,the kinematics model was established by DH modeling method.Based on this,the forward and backward kinematics of the robot was deduced,and the model was simulated by Matlab robot library.The accuracy of the established model is verified by comparison with the pose data in the robot controller.The error sources that affect the positioning accuracy of the robot are analyzed.The geometric error model of the robot is derived by the idea of differential transformation.The least squares identification algorithm of robot kinematics parameters is write by Matlab.For the RV reducer of the key component of the robot,a universal speed reducer precision detection platform was designed,which realized the accuracy detection of the RV-40 E reducer of Jinyue Machinery Technology.A method of correcting the error of the reducer by using the method of space circle fitting is proposed.A laser tracker is used for robot calibration experiments,and a set of end effectors is designed according to the experimental requirements.According to the obtained geometric error model,the actual D-H parameters are obtained through the least squares identification and the model parameters in the control cabinet are updated.The linearity accuracy and repeatability of 14 national standards were used to verify the compensation effect.After calibration,the distance accuracy(AD)decreased from-1.947 mm before compensation to-1.665 mm,and the distance repeatability(RD)decreased from 0.096 to 0.091.A set of measuring device for the end position of the robot based on laser displacement sensor and standard template is designed.The laser displacement sensor and the self-designed standard template are used as the main experimental equipment.The least squares algorithm is used to identify the actual kinematic parameters and update the control.cabinet.After calibration,the average position error value is reduced to 14.63% before calibration;the root mean square error value is reduced to 15.03% before calibration.