Design and analysis of a compliant polishing manipulator with tensegrity-based parallel mechanism

Abstract

Tensegrity mechanisms are lighter weight, lower inertial force and higher strength to weight ratio compared with conventional ones. This paper proposes a four-DOF automatic device for polishing the surface of a workspiece, in which a passive tensegrity-based parallel mechanism is connected to an industrial robot arm through an adjustable spring-loaded prismatic joint. The device consists of moving and base platforms that are connected by three compliant spring legs and one rigid central leg. A major advantage of this device is that attitude of polishing tool mounted on the moving platform can be changed automatically to fit the polished workspiece surface without any sensors, due to the three compliant spring legs. The kinematics, statics and stiffness problems of the mechanism are considered and solved. Finally, an experiment is executed on the surface of a discarded car shell, to verify the reliability of the polishing device within ranges of some parameters.