Consistent Point-to-Point Motion Planning of Anthropomorphic Arms

Abstract

This paper proposes a novel Point-to-Point (P2P) motion planning method which can ensure consistent external behaviors when applied on a group of anthropomorphic arms. Anthropomorphic arms are special kinds of manipulators which have a Spherical–Revolute–Spherical (S-R-S) structure like a human arm. Assuming they are covered by skin, the arms with equal lengths of upper arm and forearm will be seen as the same, although their internal mechanical structure, i.e., the joint arrangement, might be different. Their base frames are equivalent and related to human body’s anatomical planes, with respect to which task parameters are normally prescribed. Consequently, with the conventional joint space method, the arms with different joint arrangements will behave inconsistently when performing an identical task. This phenomenon is essentially unhuman-like. To conquer this problem, consistent P2P motion planning method is proposed. The proposed method constructs a virtual manipulator serving as motion generator on the arms’ unique corresponding physiological structure. The virtual manipulator motion is planned in the joint space. Simulations on an anthropomorphic arm and its variant are performed to prove consistency of the proposed method and inconsistency of the conventional joint space method.