A configuration space approach to collision avoidance of a two-robot system

This paper suggests an efficient approach to collision avoidance of a pract ical two-robot system. The approach is based on the C-space of one robot, a nd we consider only two and three dimensional C-space in which nearly all i ndustrial manipulators can be reasonably represented for collision avoidanc e problems. The C-space of one robot is discretized with the concentric cir cles or spheres centered at the goal configuration. We then introduce the c oncept of free arc which is a set of the candidate configuration points on the concentric circle or sphere at each sampling time to avoid collisions. It is represented simply with respect to the coordinate frame attached to t he goal configuration. The free are is used as a tool for collision avoidan ce of a two-robot system and sub-optimality can be considered in determinin g a collision-free path. The main contribution of this paper is that it pro vides a method to construct C-obstacles in a time-varying environment more efficiently than the existing methods (e.g. slice projection method(1)) by restricting the search space at the expense of sacrificing completeness. Th us, it enables us to implement a practical collision avoidance algorithm fo r a two-robot system with decreased computational cost. Simulation results for two 2-d.o.f. manipulators and two PUMA robots are presented to show the efficacy of the proposed method.