A unified distributed cooperation strategy for multiple object handling robots

Based on the constrain-move concept, previously introduced by the authors (1997), a unified approach to develop cooperation strategies for a group of multiple robots to lift/lower the object and to carry it along a desired path is introduced. In this method, when transferring the load, a group of robots, called constrain making robots, constrain the object's movements which are orthogonal to its desired path. To lift/lower the object, these robots confine angular and horizontal movements of the load by constraining its sides. The remaining robots push the object toward its goal. It is discussed that, the weight of the load can be used by the robots as a natural constrain on the object. Doing so, there is no need for the robots to confine the object any more. Instead, the object lifting robots must lift the object in such a way that the natural constraint on the object is held. A distributed cooperation strategy for the robots to fulfil this requirement is reexamined. Some experimental results are also given to show the effectiveness of the proposed approach.