Cooperative Sweeping in Environments with Movable Obstacles

In this paper, we propose an off-line planning algorithm for cooperative tasks of multiple mobile robots. Sweeping means a motion that a robot covers a 2-dimensional area by its effecter. Sweeping of a whole work area and transporting some objects are fundamental and essential motions of mobile robot’s tasks. It is more effective if a robot can move an obstacle during a sweepingr task as if we clean our room with relocating chairs. This is the most basic task that combines sweeping and transporting. We make models of sweeping and relocation of obstacles, and propose an algorithm to find appropriate path for robot and way of relocation for each obstacle. We analyze 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 equalize working time of each robot. By the algorithm total time to sweep will be minimized. We verify the efficiency of the algorithm through simulations, and apply the proposed algorithm to real mobile robot system.