On hybrid position/force cooperative control of multimanipulator based on workspace disturbance observer

In the coordinated motion of cooperative multimanipulators carrying an object, their actuators must generate motion inducing forces and internal forces (grasping forces). When the desired motion inducing force and the internal force are completely resolved, then the position control and the force control can be realized independently. Otherwise, conflicting motions may occur. This paper proposes a hybrid position/force cooperative control scheme based on a workspace disturbance observer which realizes a robust motion control system. Conflicting motion can be avoided because the disturbance observer based position and force control are allowed to operate in the opposite direction to each other. The disturbance observer is also used to make the system parameter relatively fixed to some value, such that a fixed gain controller can be chosen to achieve the desired system performance. Finally, simulation results show the validity of the proposed hybrid position/force cooperative control scheme for multimanipulators.