| With the rapid development of aviation industry,production requirements of high quality,high efficiency and low cost in aircraft manufacturing assembly technology are needed.Automatic drilling technology has an important significance for improving the efficiency of aircraft assembly and drilling quality.Based on 3-RPS+PP hybrid mechanism,a5-DOF automatic drilling mechanism for aircraft assembly is designed.The structural parameter calibration of the automatic drilling hybrid mechanism is studied mainly to improve the processing accuracy.Efficiency and high quality processing of aviation parts are achieved,which has important scientific significance and application value.The main research contents are as follows:(1)Automatic drilling hybrid mechanism is designed.The functional requirements of the automatic drilling mechanism is analyzed,and the structure of the automatic drilling mechanism is selected preliminarily;The degree of freedom for the mechanism is analyzed based on the screw theory;The general design scheme of the automatic drilling mechanism is completed,and the final form of hybrid mechanism is determined;The structure of the automatic drilling mechanism is designed in detail,and The key components is selected.Finally,the corresponding 3D model is established.(2)The method of separate calibration of automatic drilling hybrid mechanism is proposed.The kinematics inverse kinematics model of the mechanism is established according to analytic method.For the series mechanism,the error model is built based on the analysis of its structure error source.The model of the parameter identification of the series mechanism is deduced.Then,kinematic modeling considering the structure parameters error is accomplished and error compensation of the series mechanism is realized.For the parallel mechanism,the error sources of the parallel mechanism are analyzed in detail,and the sensitivity of the error sources is analyzed.The error parameters to be identified are selected.A calibration model is established based on inverse solution.The parameters are identified by the Levenberg-Marquardt algorithm.The geometrical parameters of the control system are modified by the identification result,and the error compensation of the parallel mechanism is realized.Finally,the correctness of the calibration method is verified by means of parametric modeling and simulation in the ADAMS.(3)The calibration experiment of the parallel mechanism is completed.The experiment is designed based on the calibration model of the parallel mechanism.The data is measured by the measurement system based on the cable encoder,and the homogeneous transform matrix is obtained.The calibration is completed after calibration calculation.Comparing the errors before and after the compensation,the output precision of the parallel mechanism can be improved effectively by calibration.And,correctness of the calibration method in this thesis is verified. |
