A Novel Sensitivity Analysis Method for Geometric Errors of a Parallel Spindle Head

Geometric errors are the main factors affecting the output accuracy of the parallel spindle head, and it is necessary to perform a sensitivity analysis to extract the critical geometric errors. The traditional sensitivity analysis method analyzes the output position and orientation errors independently, and then there are multiple sensitivity indices, which makes it difficult to determine the critical geometric errors. In this paper, we propose a sensitivity index that can comprehensively consider position and orientation errors based on the tool center point (TCP) position error model. First, the configuration of the hybrid machine tool is introduced and the TCP position error model is derived. Then the effective cutting length is introduced and the sensitivity analysis index is defined. After that, the sensitivity analysis of the 3-DOF parallel spindle head is performed using the proposed sensitivity index, and the effectiveness of the proposed method is verified by simulation. The proposed sensitivity analysis method can provide important guidance for machine tool accuracy design.