XY-Theta Positioning Table with Parallel Kinematics and Unlimited Theta Rotation

Abstract

Parallel robots are increasingly being used in industry for positioning and alignment. They have the advantage of being rigid, quick, and accurate. However, most parallel robots have very limited rotational capabilities and in cases where unlimited rotation is necessary, the only option used to be adding a rotary table. There however exists one overlooked XY-theta parallel robot design that can reach any point within a circular workspace at any orientation. This unique design consists of three pivots moving independently along a common circular path. These pivots are connected individually to three linear guides attached to a mobile platform in a symmetric "Y" shape. By studying the kinematics of this parallel robot, this paper shows that not only is the dextrous workspace large but the kinematic accuracy is high and uniform