Design and Control of a Parallel Robot for Mold Polishing

Abstract

A novel redundantly actuated parallel robot for mold polishing work is proposed. Cogging-less direct drive motors are implemented in the prototype. Instead of using conventional spherical sliding bearings, ball bearings with appropriate preload are implemented in the rolling pairs of the prototype. These mechanical parts enable fine force control for mold polishing work. The rated force of the robot perpendicular to the surface on the workpiece is 20 N with a tangential force of 5 N, which enable the robot to execute polishing tasks as well as skilled workers. In addition, the polishing velocity along the tangential direction is 60 m/min, which exceeds skilled workers’ velocity of 10 m/min. High speed feed contributes to reducing the polishing force and improving the quality of the surface of the mold. Kinematics, statics, dynamics and control of redundantly actuated parallel robot are discussed in this paper. Impedance control was implemented to the prototype for stably executing the mold polishing work.