Research On The Technology And Application Of Robot Accuracy Compensation Based On Secondary Feedback

Industrial robots play an important role in the transition and upgrading process of aerospace manufacturing technology due to their high flexibility,high efficiency,and low manufacturing and maintenance costs.However,because of the series structure design,the industrial robot has a poor absolute positioning accuracy and low processing stability,which limits its promotion in the aerospace manufacturing field.The existing robot error compensation technologies fail to fundamentally reflect the relationship between positioning accuracy and motion characteristics.In this paper,according to the principle of robot motion control,a robot error compensation method based on secondary feedback is proposed to improve the absolute positioning accuracy of the robot.The main work of this paper is as follows:(1)Propose the robot secondary feedback error compensation strategy.Based on the multidirectional pose accuracy variation indicator of the robot,it is analyzed and verified that joint reversal error mainly influence the multi-directional pose accuracy variation,which is the main reason that the existing robot offline calibration methods can not further improve the absolute positioning accuracy of the robot.According to the complexity of modeling of joint reversal error,a robot secondary feedback error compensation strategy is proposed.(2)Elaborate the robot secondary feedback error compensation theory,which provides a theoretical basis for the application of error compensation method.Based on the analysis of the mechanism of the error sources,a chebyshev polynomial error estimation model considering both geometric error and non-geometric error is established to estimate positioning error of the robot.The positioning error is then mapped to the joint angle by means of the joint mapping model and a PD controller is designed to decrease the control error of the joint angle and realize the online correction of the positioning error.(3)Verify the effectiveness of the robot secondary feedback error compensation method.The calibration of absolute linear gratings at the joints of the robot is accomplished as the control basis of robot error compensation.The robot secondary feedback control environment is then established,and the process of the robot secondary feedback error compensation method is elaborated.Finally,experiments are conducted to verify the effectiveness of the proposed method.The results show that this method can compensate the joint reversal error effectively and the maximum absolute positioning error of the robot is reduced by 76.8% compared with uncompensated.(4)Propose and verify the robotic automatic drilling comprehensive compensation method,and realize the application of the robot error compensation method in robotic drilling system.The overall scheme design and workflow of the robotic drilling system are introduced.Based on the error analysis of the robotic drilling system,the comprehensive compensation method for maintaining the drilling positioning accuracy is proposed and verified.Drilling experiments show that the drilling accuracy of the robotic drilling system can reach 0.25 mm.