Kinematically-Redundant Variations of the 3-RRR Mechanism and Local Optimization-Based Singularity Avoidance

摘要

To avoid the singular loci of the 3-RRR mechanism that exist within its workspace, this paper applies kinematic redundancy. First, three feasible kinematic redundancy configurations for the 3-RRR mechanism are presented and singularity analysis of the kinematically redundant mechanisms is described. Then, based on local optimization suitable for real-time control, a general, simple, and effective redundancy resolution algorithm for the mechanisms is developed. Here, the cost function in the optimization is designed to avoid the most problematic singularity configurations, where the end-effector can be locally moved even though all actuated joints are locked. The kinematically redundant mechanisms are shown to effectively avoid singularities and correspondingly increase the singularity-free workspace.