Task-priority redundancy resolution with robustness to algorithmic singularities

Abstract

The task-priority strategy allows redundancy resolution by adding a null-space motion to the basic pseudoinverse joint velocity solution such that the fulfillment of the given primary task is not affected while attempting to satisfy also a secondary task. A problem with this technique is related to the occurrence of algorithmic singularities at which the null-space motion required to achieve the secondary task may give infeasible joint velocities; this represents a severe limitation on practical applicability of the method. In this paper a task-priority redundancy resolution technique is introduced which is suitably devised to properly handle the occurrence of algorithmic singularities. The method is applied to a simple three-degree-of-freedom planar manipulator in numerical case studies to illustrate its potential in comparison to the existing techniques.