PATH PLANNING FOR TWO COOPERATING ROBOTS

We investigate the problem of finding collision-free paths for two planar robots which coordinately carry a rectangular object from an initial position and orientation to a destination position and orientation in a cluttered 2-D environment. The robot arms and the carried object construct a 6-link closed chain. The path planning problem for the 6-link closed chain is solved by using two major algorithms: the collision-free feasible configuration finding algorithm and the collision-free path finding algorithm. The collision-free feasible configuration finding algorithm finds all collision-free feasible configurations (CFFCs) of the 6-link closed chain in each discrete interval of two joint angles. The collision-free path finding algorithm builds a connection graph by CFFCs and the transitions between any two groups of CFFCs at adjacent joint intervals. Then a graph search method is used to find a collision-free path for each joint of the robots.