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In this paper, Constrain-Move strategy is generalized for a team of four object-lifting robots. The effects of redundancy in the number of cooperative robots on the system and robot-object contact stability are also studied. In addition, a distributed coordination method is proposed to ensure the contact and system stability. In the presented cooperation strategy, the robots support the load on its bottom face and there is no lateral artificial constraint on the object. The distributed coordination protocol is designed in such a way that with minimum volume of communication and
implementing their own local sensors, the robots can lift the object while its Euler angles and robot-object contact are controlled. Stability condition for the system is attained mathematically. Simulation results are given to support the applicability of the presented system.