Motion planning for cooperative sweeping with relocating obstacles

We propose an off-line planning algorithm for cooperative tasks of multiple mobile robots. Sweeping means a motion that a robot covers a 2D area by its effector. Sweeping of a whole work area and transporting some objects are fundamental and essential motions of mobile robot´s tasks. In this paper we deal with tasks which combines both sweeping and transporting. It is more effective if a robot can move an obstacle during a sweeping task as if we clean our room with relocating chairs. We develop models of sweeping and relocation of obstacles, and propose an algorithm to find an appropriate path for the robots and the way of relocation for each obstacle. We analyze the motions of robots with relocation in both time and space by applying the LT graph. On the basis of the analysis the algorithm avoids collisions between a robot and an obstacle, and equalizes the working time of each robot. By using the algorithm the total sweeping time can be minimized. We verify the efficiency of the algorithm through simulations, and apply the proposed algorithm to a real mobile robot system