Repulsive reaction vector generator for whole-arm collision avoidance of 7-DoF redundant robot manipulator

In this paper, we propose a repulsive reaction vector generator (RVG) for whole-arm collision avoidance of 7-DoF redundant robot manipulator, and elucidate the case of spherical-revolute-spherical (S-R-S) type manipulator. Furthermore, this article discusses the obstacle-avoiding function of RVG, in which the generated reaction vector can aid the manipulator to achieve collision avoidance in an intuitive way by taking arm angle as the redundant parameter. First of all, we use six representative points to describe the manipulator, and generate the repulsive vectors according to the relationship between obstacle and the tip, wrist, and arm body of the manipulator, respectively. Next, after the pose of the manipulator, including position, orientation, and arm angle, is rectified by the reaction vector, the command would be sent to proposed vOTG to complete the reactive motion. As a result, the manipulator can achieve intuitive repulsive reaction, active whole-arm collision avoidance, and meanwhile avoiding the minor-risk obstacle by rotating the arm plane. Experimental results with NTU-iCeiRA arm developed in our lab and Microsoft Kinect depth sensor are presented.