Sub-optimal collision-free motion planning of a two-robot system using free arc

This paper presents a method for planning collision-free motion of a two-ro bot system. The concept of free are is introduced for the purpose of develo ping the method in the C-space. Free are is defined as a set composed of th e configuration points of a robot manipulator satisfying its collision-free motion constraint at each sampling time, represented with respect to the c oordinate frame having the origin at the goal configuration in the C-space. Thus, both the motion constraint and the collision constraint of a robot m anipulator are represented in the form of free are. Then, the free are is u sed as a tool for collision-free motion planning, and optimality is conside red when the collision-free path is determined from the free arcs. This con cept enables us to transform the problem of collision-free motion planning into a Sub-Optimal Collision Avoidance Problem (SOCAP). The presented metho d is implemented in a real two-robot system which consists of two industria l SCARA type manipulators, and the experimental results are provided to sho w the validity of the method. (C) 1998 Elsevier Science Ltd. AII rights res erved.