Research On Error Analysis And Compensation For Space Micromanipulator

Space micromanipulators can replace human beings in the space station for precision operation,such as bioengineering experiments,maintenance of precision machinery and microelectronics and other precision operations.These operations require micromanipulators have very high accuracy.Manufacturing errors,assembly errors and other factors cause the pose errors in the pose of the robot end-effector.Robots can have a high repeatitive positioning accuracy,but the absolute positioning accuracy is generally lower.The macro-micro combined micromanipulator not only has sufficient working space,but also has high positioning accuracy.Generally,error space of the macro-platform is smaller than working space of the micro-platform.In order to improve the absolute positioning accuracy of the self-developed space micromanipulator,it is one of the most effective methods to analyze and compensate the error of the macro-manipulator.In this paper,the error analysis and compensation for macro-manipulator of micromanipulator are mainly studied.The error distribution and variation rules of the macro-manipulator are studied to guide manufacture,assembly and calibration of macro-manipulator.The actual kinematic parameters of the manipulator are identified by the kinematic calibration to improve its absolute positioning accuracy,and an improved POE(Product of Exponential)calibration method is proposed.The main research content of this paper include:(1)Kinematics of micromanipulator.The self-developed space micromanipulator is introduced.The forward kinematics and inverse kinematics of the macro-manipulator are solved by DH method and POE method respectively.The conversion relationship between the two corresponding parameters is analyzed.(2)Error analysis of micromanipulator.The error source of micromanipulator is analyzed,and the error model is established to solve the spatial cumulative error.The quasi-Monte Carlo method is used to carry out error analysis.The error distribution of the working plane and the sensitivity and influence law of the joint errors on the pose of the macro-manipulator are obtained.(3)Kinematic calibration method of micromanipulator.The improved robot error model is established by POE method.The calibration methods based on pose measurement and position measurement are given respectively.Comparing with classical methods,calibration simulation experiments of macro-manipulator and different manipulators are carried out by MATLAB.(4)Kinematic calibration experiment of micromanipulator.The working principle of the laser tracker is analyzed.The base frame is determined by laser tracker AT960.The three points fixed at the end of the manipulator are used to solve the pose of the tool frame in the base frame.The measured data are imported into the calibration program,then the accurate DH and POE parameters can be obtained.Verification shows that the accuracy of the calibrated manipulator is significantly improved.