Two-DOF actuator module design and development based on fully decoupled parallel structure

Abstract

This paper presents a two-DOF actuator module for weight device manipulations. Minimum requirements for a two-DOF actuator module are high accurate positioning, long stroke motion, and fully motion decoupling to utilize standalone stage. Also, the shape and compactness should be considered to utilize for kinematic linkage of the parallel manipulator. In order to achieve minimum requirements, we proposed the fully decoupled parallel structure that is a kind of the motion converting mechanism consisting of reduction unit, decoupling unit, primary motion unit, and secondary motion unit. Moreover, we utilized conventional mechanical components to assemble mechanical units. The conventional mechanical components commonly involve undesired motions such as straightness error, flatness error, angular runout, and backlash. To minimize the undesired motion, we design the final prototype of actuator module by considering preload and paired joint in all of the motion components. Finally, to validate system performance, we performed several experimental tests, namely, positioning accuracy, closed-loop control response, and axis selection. The results show root mean square error 45 nm and standard deviation 44 nm.