| For the measurement and milling processing of high-precision instrument mounting brackets on large spacecraft with large size and low rigidity,such as space stations,traditional manufacturing methods are difficult to achieve rapid response requirements for product development,In order to improve the processing efficiency of products and solve the processing problems of large structural components,It is urgent to develop an intelligent flexible manufacturing unit which combines omnidirectional mobile platform and high-precision robot.In order to realize the automatic and precise milling,In this paper,based on the analysis of the requirements of spacecraft bracket milling technology,combined with the characteristics of the robot and processing mode,High accuracy articulated robot with Siemens 840 Dsl CNC control system is deeply studied in this paper,The main contents of this paper are as follows:(1)The processing object of the mobile robotic milling system was studied,and on the basis of analyzing the composition and workflow of the mobile robotic milling system,the key technical requirements of the mobile robotic milling system were summarized.Finally,The overall scheme of contorl planning of the mobile robotic milling system was proposed.(2)The robot kinematics configuration method based on Siemens 840 Dsl CNC control system is introduced,and the robot programming in the CNC control system is explained.The source of the robot joint angle error is analyzed,the multi-directional repetitive error of the robot is studied,Finally,joint feedback with additional secondary encoder systems on the first three joints is proposed.(3)The basic principle of laser tracker closed-loop feedback is analyzed,and the control model is also designed.According to the control principle,the user interface and control algorithm of laser tracker closed-loop feedback control software are developed,Finally,the compensation channel of laser tracker closed-loop feedback is established.(4)The experimental verification platform was constructed.Firstly,joint feedback is studied experimentally,the experimental results show that joint feedback can effectively improve the repetitive positioning accuracy and reduce the trajectory error.Secondly,the effect of laser tracker closed-loop feedback is verified by the accuracy test,the experimental results show that the compensation method of laser tracker closed-loop feedback is effective and feasible,and comprehensive error after compensation is less than ±0.126 mm.Finally,the milling experiment was carried out,The flatness of the workpiece after milling is better than 0.1mm,and the surfaceroughness is less than 1.6,which can meet the requirements of automatic and precise assembly of mobile robotic milling system. |
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