A pusher/steerer model for strongly cooperative mobile robot manipulation

Presents an empirical example of a strongly cooperative manipulation system (the pusher/steerer system), whose capabilities derive from the redistribution of resources typically used in a single robot system. The authors define strongly cooperative strategies to be, intuitively, those which are not trivially serializable. In the authors' system, one robot steers, and the other pushes; the object lies between them. The steerer is the only agent that has information about the path, while the pusher exerts the necessary motive force, and rotates to follow changes in the object's orientation. The system is asynchronous, with no explicit communication between the robots. The authors are interested in studying manipulation systems of this type, because they are strongly cooperative; that is, the two robots must act in concert to achieve the goal. The authors have performed over one hundred pusher/steerer manipulation experiments with two of their mobile robots, TOMMY and LILY. As the authors' analysis predicts, they have found that their system allows a wide variety of paths and manipulable objects for these robots.