Kinematic Optimization of a 2-DOF U, 2PSS Parallel Wrist Device

The wrist plays the crucial role of orienting a hand or end effector without significant translational motion, a critical requirement of successful manipulation. In this paper, we present the kinematic design optimization a two degree of freedom universal, two-prismatic-spherical-spherical (U, 2-PSS) parallel wrist mechanism. By varying the geometric parameters of the mechanism, we examine configurations that maximize the Global Conditioning Index, a metric describing the quality of the motion and torque, over the desired workspace, which mimics a healthy human wrist range of motion in circumduction (flexion/extension and abduction/adduction). We further investigate the effects of sizing constraints on the resulting optimized design which satisfies the imposed sizing constraints.