Workspace and Singularity Analysis of a Novel Six-DOF Parallel Minimanipulator

Abstract

Workspace and singularity analysis of a novel three-limbed, six degree-of-freedom (DOF) minimanipulator is presented. The minimanipulator limbs are inextensible and its actuators are base-mounted. The lower ends of the limbs are connected to bidirectional linear stepper motors which are constrained to move on a base plane. The minimanipulator is capable of providing high positional resolution and high stiffness. A discretization algorithm is used to determine the minimanipulator workspace for a given platform orientation. The algorithm uses the bisection method and the inverse kinematics of the minimanipulator to find the cross-sectional boundaries of the workspace. Necessary and sufficient conditions for both inverse and direct kinematics singularities are obtained. The latter which could occur within the minimanipulator workspace is discussed in more detail. The Jocobian matrix is used to obtain some of the singularities. An alternative approach is used to determine additional singular configurations.