Human-Like Motion Planning for a 4-DOF Anthropomorphic Arm Based on Arm’s Inherent Characteristics

Abstract

Human-likeness of an anthropomorphic arm is mainly exhibited by the main arm consisting of shoulder and elbow joints as well as upper arm and forearm. In this paper, we focus on a 4-DOF anthropomorphic arm and propose a novel approach to generate human-like motion, considering human physiological and psychological factors. According to the features of musculoskeletal system of human upper limb, the 3-DOF shoulder joint is simplified with two rotations: one is about a fixed axis through shoulder center and the other is about the axis of humerus. In addition with elbow joint and a special rotation about the shoulder-wrist line, they constitute the basic motion primitives (MPs) which are macroscopic compared with the joint space but microscopic compared with the Cartesian space. Therefore, planning motion based on MPs combines intuitiveness and flexibility. Two basic kinds of motion planning, point-to-point motion planning and linear trajectory planning, are conducted. The different psychological concerns, i.e., predicting the next step of configuration and relieving the brain burden, are taken into account. Simulations are performed to verify the feasibility and validation of the proposed approach. Comparisons between simulation results with the proposed method and that with traditional joint and Cartesian space methods prove the improvement in human-likeness.