Expand the Workspace of a Two limbs Redundantly Driven Rarllel Robot

Abstract

A singularity free mode changes of a redundantly driven two limbs six-DOF parallel robot ATARIGI is proposed in this paper. The parallel robot has multiple solutions to the inverse and forward kinematics. By changing postures from one solution to another, the parallel robot can expand its workspace. Conditions that ATARIGI loses redundancy but keeps the non-singularity are derived. Using the conditions, singularity free mode changes that the bending direction of the elbow (over and under) of each limb and direction of the gripper (up and down) can be achieved. By the combination of the singularity-free mode changes, ATARIGI switches its postures between ”the elbows-over and gripper-down, suitable posture for the bottom working area,” and ”the elbows-under and gripper-up, suitable for the upper working area.”