Machining, Measurement, and Control Laboratory

Compensation of Gravity-induced Motion Errors on a Parallel Kinematic Machine Tool
Toshihiro Ikuda, Soichi Ibaraki, Yoshiaki Kakino (Kyoto University)
Masao Nakagawa, Tetsuya Matsushita (Okuma Corp.)

This paper presents a methodology to compensate contouring errors introduced by the gravity on a Hexapod-type parallel kinematic machine tool with the Stewart platform. We first present a kinematic model to predict the elastic deformation of struts caused by the gravity. The positioning error at the tool tip is given as the superposition of the deformation of each strut. It is experimentally verified on a commercial parallel kinematic machine tool that the machine's contouring error is significantly reduced by compensating gravity-induced errors on a reference trajectory.