Error model and accuracy analysis of a six-DOF Stewart Platform

Precision machining operations necessitate highly accurate, rigid, and stable machine-tool structures. In response to this need, parallel architecture machines, based on the concepts of the Stewart Platform, are emerging. In this paper, considering major inaccuracy factors related to the manufacture, geometry, and kinematics, of such machines, first and second order error models are presented, and followed by a comparative assessment of these models in conjunction with illustrative examples. Furthermore, in order to understand the character and propagation of errors of 6-DOF Stewart Platform based machine tools, sensitivity analysis is adopted to describe the contribution of each error component to the total position and orientation error of the mechanism. An automated error analysis system that computes and graphically depicts the error distributions throughout the workspace along with the results of sensitivity analysis is developed and demonstrated.