Redundancy Analysis of Articulated Robot Arms and Its Utilization for Tasks with Priority

Abstract

In this paper, fundamental characteristics of redundancy in motion degrees of freedom of articulated robot arms are made clear and principles for utilizing the redundancy are investigated.Analyzing small motions around specified reference conditions for robot arms with articulated joints of general construction, the redundancy of the articulated robot arms is defined as degree of freedom for determining joint angles corresponding to certain specified operation at those conditions. The redundancy is also investigated by using null spaces and ranges of Jacobian matrices which are defined for the robot arm motion. Then, we formulate the utilization of the redundancy based upon the newly introduced concept “tasks with priority”. Finally, we show experimental results of the trajectory tracking of an articulated robot arm with provisions for an obstacle and discuss the effectiveness of the utilization of the redundancy.