Real-time velocity alteration strategy for collision-free trajectory planning of two articulated robot manipulators (Q1610635)

This paper presents a real-time approach for collision-free trajectory planning via velocity alternation in a robotic system with two articulated robot manipulators. The authors present a detection algorithm capable of permitting two robots with priorities to work in a shared workspace with independent goals and without collisions. The minimum distance between the links of two moving robots is estimated by a novel method developed by the authors. Enclosing and enclosed ellipsoids, acting as outer-inner approximations to the convex polyhedra defined by the robotic links, permit fast and accurate estimation of the distance between links and detection of potential collisions. The authors' proposed strategy is implemented in an environment where the paths of the robots in space are pre-planned and velocities are pre-programmed as piecewise constant, but adjustable. With this strategy, one robot -- the master -- always moves at a constant speed, while the other robot -- the slave -- moves at a velocity selected according to a tradeoff between a computed collision trend index and a goal to move as fast and as far as possible. Simulations with two PMUA 560 robot arms working in a common workplace with independent goals were conducted. The authors believe that their strategy results in fewer speed alterations compared to competing approaches.