Human Arm Trajectory: Planning, Execution, and Control

Abstract

A three dimensional, five degrees of freedom human arm model has been developed to study the planning, execution and control of hand movement. The hand trajectory is assumed to derive from the population vector of neural cells of motor cortex. The real time calculation of joint trajectories from the hand trajectory is based on a biologically inspired algorithm. The instantaneous angular velocity for each joint is determined by the cross product of two vectors: the joint vector and the error vector. A nonlinear gain modulation adjusts the gain for each degree of freedom according to the instantaneous joint position relative to its physiological limit. The algorithm does not use inverse kinematics to determine joint trajectories from the hand position, and can be adapted to situations where the final target position is moving, for example, to track or to intercept a moving object. Several simulation results are presented to illustrate the merit of the algorithm.