Geometric approach to the accuracy analysis of a class of 3-DOF planar parallel robots

摘要

Parallel robots are increasingly being used in industry for precise positioning and alignment. They have the advantage of being rigid, quick, and accurate. With their increasing use comes a need to develop a methodology to compare different parallel robot designs. However no simple method exists to adequately compare the accuracy of parallel robots. Certain indices have been used in the past such as dexterity, manipulability and global conditioning index, but none of them works perfectly when a robot has translational and rotational degrees of freedom. In a direct response to these problems, this paper presents a simple geometric approach to computing the exact local maximum position error and local maximum orientation error, given actuator inaccuracies. This approach works for a class of three-degree-of-freedom planar fully-parallel robots whose maximal workspace is bounded by circular arcs and line segments and is free of singularities. The approach is illustrated on three particular designs.