General-Weighted Least-Norm Control for Redundant Manipulators

This paper presents the general-weighted least-norm (GWLN) method for the control of redundant manipulators by a new concept of virtual joints, which consist of the performance function of subtasks. The GWLN method enables the redundant manipulator to perform multiple subtasks with the assumption that all the subtasks can be represented by the inequalities as the joint limits avoidance subtask. The number of subtasks to be coped with might be even larger than the number of joints if they do not happen simultaneously. The simulations in contrast to the traditional gradient projection method (GPM) and the recent directional GPM have been made to manifest the advantages of the proposed method. An experiment on the seven-degree-of-freedom redundant manipulator illustrates the good performance for tracking a given trajectory of end-effector position, while both guaranteeing the obstacle free and not violating the joint limits.