A Calibration Approach for the Parallel Kinematics Machines Tools Based on Error Sensitivity Analysis

Abstract

In order to identify the geometrical parameters of parallel kinematics machines tools (PKM), a new parameters identification method is presented. The identification method is proposed based on a pose discrepancy model, which is deduced from the error between the nominal and measurement relative distance of two different spatial locations of the moving platform. In the identification method, an error sensitivity matrix, which expresses the sensitivity between the pose error and geometrical structural parameters error of PKM, can be created with numerical methods. The results of different numerical methods are analyzed. A measurement method to get the precise lengths of legs is presented, which decrease the number of identified parameters. In an experiment, the error of PKM is reduced from 6.71mm to 1.144mm. Therefore, the identification method is verified effective and feasible.