Object Handling Using Two Arms Without Grasping

Abstract

Two cooperative manipulators equipped with open-palm end effectors are particularly suited to handle large objects. This can be achieved by having one palm push from one end and the other from the opposite end. This article studies modeling and coordinated control of two-arm pushing operations. The performance of such tasks requires simultaneous control of the motion trajectory of the object and the interaction force. Control of the interaction force is essential to avoid dropping or crushing objects. The motion and force control problem is complicated by the presence of unilateral constraints, as the manipulators can only push the object. The control problem is first formulated in the state space. A coordinated control method is then presented that utilizes a state feedback to de couple the motion control subsystem from the force control subsystem. The unilateral constraints are satisfied during the entire motion period by using a proposed force control plan ning algorithm. The effectiveness of the control method is verified by simulations.