Cooperative Obstacle-Avoidance Pushing Transportation of a Planar Object with One Leader and Two Follower Mobile Robots

This paper proposes a cooperative obstacle-avoidance pushing transportation system using one leader and two follower mobile robots. Its usefulness and effectiveness are illustrated and confirmed numerically as well as experimentally. The cooperative obstacle-avoidance pushing transportation control consists of the obstacle configuration measurement phase by the leader mobile robot, the trajectory-planning phase and the pushing transfer control phase by the two follower mobile robots. In the obstacle configuration measurement phase, the leader mobile robot moves by use of the obstacle-avoidance vehicle control method constructed with six infrared sensors and the pattern recognition algorithm, and three waypoints for the trajectory planning of the follower mobile robots are extracted. In the trajectory-planning phase, the two follower mobile robots receive the three modified waypoints from the leader mobile robot through wireless communication systems, and the obstacle-avoidance trajectories by use of cubic spiral and straight-line segments are generated. Then, in the pushing transfer control phase, a planar object is transported with the pushing and constraining forces resulting from the passive compliance mechanisms attached to the follower mobile robots, and the shock is effectively reduced by the passive compliance mechanisms. From the numerical simulation and experimental results using autonomous mobile robots (MK-01X developed by Fuji Heavy Industries Ltd.), it is confirmed that the planar object can be successfully transported by pushing from the start configuration to the goal in spite of the existence of the obstacle.