Design and Prototyping of a Partially Decoupled 4-DOF 3T1R Parallel Manipulator With High-Load Carrying Capacity

Abstract

In this paper, a new four degrees of freedom 3T1R parallel manipulator with high-load carrying capacity is presented. This manipulator generates Schönflies motions, in which the moving platform carries out three independent translations and one rotation about one axis of fixed orientation. The particularity of the proposed architecture is the decoupling of the displacements of the platform in the horizontal plane from the platform’s translation along the vertical axis. Such a decoupling allows the cancellation of the gravity loads on the actuators, which displace the platform in the horizontal plane. A prototype of the proposed manipulator with four degrees of freedom and an experimental validation of the suggested concept are also presented. Two cases have been examined on the built prototype: a manipulator with payload and one without. It was shown that the input torques of actuators displacing the platform in the horizontal plane for these two cases are the same; i.e., the payload does not bring any load to the actuators.