Error Analysis And Simulation Of 3-TPT Parallel Machine Tool

The parallel machine tool (PMT) is a novel class of manufacturing equipment which rises in recent years. Because of the advantages, such as its high ratio of stiffness to mass, high speed, good parts-modularizing and low manufacturing cost, it has been an important development direction of new generation machine tool. The dissertation studied the structure, kinematics, kinematics ability, error and simulation of 3-TPT parallel machine tool developed by Northeastern University, and provided necessary fundamental theory for further kinematics calibration and error compensation. The details are as below:1) The structure characters and kinematics problems of 3-TPT parallel machine tool were analyzed in detail. The problems included analysis of structure and degree of freedom, analysis and simulation of direct and inverse solution of position, calculation of Jacobian matrix, analysis and simulation of direct and inverse solution of velocity and acceleration.2) The indexes of workspace, singularity, operability and smartness of the 3-TPT parallel machine tool were analyzed. Through analyzing the singularity and smartness of mechanism in workspace, we could find that there were no singularity and uncertain configuration, and it had good operability and smartness.3) The error of 3-TPT parallel machine tool was analyzed and simulated in detail. The basic classification of parallel machine tool error and error sources which influence the precision of parallel machine tool were introduced. Then it pointed out that the key of precision analysis of parallel machine tool was to establish position error model of moving platform, and put forward the idea of establishing the error model of parallel machine tool. The error model of 3-TPT parallel machine tool was established based on matrix method and error individual contributions theory separately. Random sampling of legs' error and gimbals' clearance error was got, and their effects on moving platform were analyzed with Monte-Carlo method. The simulation indicated that the position synthesis error of moving platform in working space was smaller, and the effect of legs' error on position synthesis error of moving platform was smaller than that of gimbals'.