This paper presents a centralized force/position controller for a heavy object manipulation in a multi-manipulator cooperative system. System dynamics of cooperative manipulating tasks comes from complex interaction of the object with robot manipulators and the environment. In this paper, focussing on the interaction effects in the system as well as by noting the role of imposed kinematics and force constraints, manipulator coordination and minimizing internal forces a pre-designed impedance behaviour between manipulator end effectors and the object is developed. The stability of the feedback system is then presented through passivity theorem and simulation results are finally provided with three manipulators handling the object supporting the relevance of the theoretical results. ARTICLE HISTORY

Decentralized force and motion control of a heavy object with lathing tools, in a cooperative multiple manipulator system is studied in this paper. Interaction of the object with robot manipulators and the environment and interaction of manipulators with each other that produce internal forces in the object are complexities in the system dynamics of cooperative manipulation tasks. In this paper, impedance behaviour between manipulator end-effectors (EE) and the object is developed to achieve springy links that lead to impedance effect between the object and the environment. Then, by focusing on the interaction effects in the system as well as the role of imposed kinematics and force constraints, each manipulator will have its own controller for coordination tasks, environment force regulation and internal forces minimization, without force/torque sensors in the EE. The relevance of the theoretical findings is illustrated using simulation results involving three robots manipulating a common object.