Velocityalteration Strategy For Collsion-Free Trajectory Planning of Two Robots

Abstract

Two robots working in a shared workspace can be programmed by planning the trajectory of each robot independently. To account for collision avoidance between them, a real-time velocity tuning strategy based on fast and accurate collision detection is proposed in this paper to determine the step of next motion of slave (low priority) robot for collision-free trajectory planning of two robots with priorities. The effectiveness of the method depends largely on a newly developed method of accurate estimate of distance between links. Under the control of the proposed strategy, the master robot always moves at a constant speed while the slave robot moves at the selected velocity, based on a tradeoff between collision trend index and velocity reduction in one servoing time, to keep moving as long as possible and as fast as possible while avoid possible collisions along the path. The collision trend index is a fusion of distance and relative velocity between links of two robots to reflect the possibility of collision at present and in the future. Graphic simulations of two PUMA560 robot arms working in common workspace but with independent goals are conducted to demonstrate the collision avoidance capability of the proposed approach as compared to the approach based on bounding volumes. It shows that a potential benefit of our approach is less number of speed alterations required to react to potential collisions.