Research On Position And Attitude Errors Of 3PRS-XY Series-parallel Machine Tool

The hybrid machine tool is a new type of automated processing equipment developed at the end of the last century,which has combined with the technology of machine tools and robots.It has been concerned by the researcher as it has high precision and good carrying capacity.The thesis studies a machine tool of a new 3PRS-XY series-parallel mechanism with three adjustable pedestals and variable working space.The mechanism model of the hybrid machine tool is established,and the kinematics,dynamics and pose error of the machine tool is analyzed.Some corrected arithmetic for different errors is proposed,which are verified by examples.The main research contents are as follows:(1)Aiming at the structural characteristics of the machine tool with the adjustable pedestal and variable working space,kinematics modeling of the series-parallel machine tool is established.The forward kinematic equation and reverse kinematic equation of the machine tool are solved according to the geometrical relationship,and the working space of the parallel mechanism is obtained based on the forward kinematic analysis of the 3-PRS parallel mechanism.The influence of the base on the working space is analyzed too.(2)The dynamic analysis of the 3-PRS parallel mechanism is carried out based on the kinematic analysis.The kinematic and dynamic simulation is conducted by establishing the 3D modeling of the parallel mechanism.The significant influence on the driving force and power consumption of the moving platform is discussed respectively,when the parallel mechanism is affected by the force added on the end-effector,the friction of sliding block or the common force of the two.(3)According to the structure characteristic of the three branch chains is completely symmetrical,the error model of the spindle platform is established with one of the branched chain as the research object by using the matrix differential method.The influence of the adjustable pedestal on the end-effector error is analyzed based on the forward kinematic analysis.(4)Aiming at various mechanism errors resulting from manufacturing and assembling process,the least square method in space of for the mechanism end errors is corrected is adopted.Concerning the clearance errors existing in the spherical pair and column pair at both ends of the linkage,the direct error compensation method for the errors is analyzed.