Geometric error measurement and compensation of a six-degree-of-freedom hybrid positioning stage

Abstract

This paper presents the geometric error measurement and compensation of a six-degree-of-freedom (6-DOF) hybrid positioning stage consisting of a 3-DOF parallel kinematic mechanism and a 3-DOF serial mechanism. The parallel kinematic mechanism uses ball joints and wedge-shaped mechanisms to provide the required rotational and sliding movement. The advantages of this mechanism include a simple structure, easy assembly, and zero accumulated linkage errors. The study commences by describing the kinematic mechanisms of the positioning stage, and then evaluates the degrees of freedom of the parallel kinematic mechanism. Subsequently, a homogeneous transformation matrix approach is employed to perform an inverse analysis of the kinematics of the entire positioning stage. The study then discusses the effects of geometric errors caused by imprecision in the manufacturing and assembly processes on the positional accuracy of the stage. Finally, a coordinate measuring machine is used to measure the translation and orientation errors of the positioning stage. By comparing the measured data with the values derived from the inverse kinematics analysis, an error compensation model is constructed.