Research On Robot Positioning Technology Based On Joint Feedback

Due to its high flexibility,high efficiency and stable quality,the automatic drilling and riveting system with industrial robots is gradually being used in the aviation manufacturing industry.However,the low absolute positioning accuracy has always been a barrier to its popularization and application.Based on the analysis of multi-directional repetitive positioning errors and their effects,it is found that the multi-directional repetitive positioning error is the main reason that the compensation accuracy cannot be further improved.In order to further improve the positioning accuracy of the robot,a method of position error compensation based on joint feedback is proposed.The main contents are as follows:(1)The position error compensation strategy based on joint feedback is proposed.Based on the kinematic model of the robot,the main factors affecting the position error and the position uncertainty are analyzed.The influence of multi-directional repetitive positioning error on the error compensation is analyzed.According to the diversity and complexity of the multi-directional repetitive positioning error,a method of using grating feedback to eliminate joint reverse error and a position error compensation strategy based on joint feedback.(2)Clarify the principle of position error compensation based on joint feedback.According to the principle of error similarity,a Cartesian position error prediction model is established.Through the error mapping model,the position error can be transformed into the joint angle error.The PD feedback control model can be used to correct the joint angle error and compensate the position error.(3)The position error compensation verification platform based on joint feedback is constructed.With the help of hardware and software platform of automated drilling system,a real-time interactive environment of feedback correction is set up.The data acquisition and position correction are processed in parallel through two-thread data exchange to complete the correction of position error.(4)Experimental verification based on joint feedback position error compensation technique.The experimental results show that joint feedback can significantly reduce the multi-directional repetitive positioning error of the end effector.The proposed position error compensation method based on joint feedback is effective and feasible.After compensation,the position accuracy is better than ? 0.2mm,and the accuracy of borehole location is better than ? 0.25 mm.