The Structural Parameter Calibration And Accuracy Evaluation Of The C-shaped Gantry Parallel Machine Tool

Due to the influence of manufacturing,assembly and driving errors,the actual accuracy of parallel machine tools is far below the design accuracy.These errors seriously affect the machining efficiency and quality of machine tools.In order to improve the precision of the parallel machine tool.In this paper,using the C-shaped gantry parallel machine tool as the research object,and improve the precision of the machine by using the method of kinematic calibration,the kinematic calibration has the characteristics of low cost,high efficiency,is a feasible and economical method to improve the precision of parallel machine tool.The main work is as follows:1)Analyze the structural characteristics of the parallel machine tool,set up the machine tool coordinate system that accords with its characteristics,then carry on kinematics analysis to it,build the position inverse solution equation of the parallel machine tool,and calculate the working space of the machine tool.2)Error Jacobi matrix 45 structural parameters of direction vector error including Hooke hinge installation position error,telescopic rod length error and redundant linear module based on vector differential method,and the Matlab calculated various error sources on the parallel machine and moving platform position and attitude influence.3)Calibration model based on inverse kinematics is established,and the actual value of the structural parameters of the parallel machine tool is solved by Gauss-Newton nonlinear least square method.The feasibility of the calibration algorithm is proved by Matlab simulation.4)According to the structural characteristics of the C-shaped gantry parallel,a pose measurement method based on parallel three coordinate measuring machine is proposed,and building the error model of the parallel three coordinate measuring machine,and the feasibility of its accuracy is verified.5)Step by step calibration method is used to calibrate the 45 structural parameters of the parallel machine tool.The motion accuracy of the machine tool is compared and analyzed before and after the experiment to verify the effectiveness of the calibration experiment.