Design and Kinematics Modeling of a Novel 3-DOF Monolithic Manipulator Featuring Improved Scott-Russell Mechanisms

Abstract

This paper proposes the design of a novel 3-DOF monolithic manipulator. This manipulator is capable of performing planar manipulations with three kinematically coupled DOFs, i.e., the translations in the X and Y axes and the rotation about the Z axis. An improved Scott-Russell (ISR) mechanism is utilized to magnify the displacement of the piezoelectric actuator (PEA). Unlike the SR mechanism, a set of leaf parallelograms is incorporated into the drive point of the ISR mechanism as a prismatic joint. As a result, the linearity of motion and stability are improved. With circular flexure hinges being treated as revolute joints, the forward kinematics and inverse kinematics of the 3-DOF manipulator are analytically derived. Computational analyses are performed to validate the established kinematics models. Due to the unwanted compliance of the flexure hinges, the actual displacement amplification ratio of the ISR mechanism is smaller than its theoretical value. This is the main cause of the discrepancies between the analytical and computational results. The reachable workspace and the static/dynamic characteristics of the 3-DOF manipulator are also analyzed.