1-Actuator 3-DoF Manipulation Using an Underactuated Mechanism with Multiple Nonparallel and Viscoelastic Passive Joints

Abstract

This paper presents a nonprehensile manipulation based on the vibration of a plate, in which three degrees of freedom (DoF) of a planar part are controlled using only one actuator. First, the model of a manipulator with a flat plate end effector is proposed. The manipulator employs an underactuated mechanism including an active joint and multiple passive viscoelastic joints, in which the joint axes are arranged nonparallel to each other. Based on the model, the orbit of the plate for a sinusoidal displacement input to the active joint is theoretically derived. It is revealed that not only the orbital shape but also the orbital direction can be varied according to the input frequency. Based on the switching frequency of the orbital direction, a design index for the mechanical parameters is shown. Subsequently, the contribution of the switching of the orbital direction to the three-DoF manipulation of a part is explored via simulation. Eight primitives utilizing the plate orbital motions in both counter-clockwise and clockwise directions are provided. Finally, the proposed method is demonstrated by experiments.