Dynamics of cooperating manipulators for fixtureless assembly and robust control based on fuzzy logic

This article presents the modeling of the dynamics of two cooperating robot manipulators performing assembly tasks such as the peg-in-hole job while coordinating the payload along the desired trajectory. The system has uncertainty due to unknown mass and moment of inertia of the manipulators and the payload, and has disturbances due to coupling forces between manipulators and due to frictional forces during the assembly process. To control the uncertain system, a robust control algorithm with computed torque control is proposed. The robust control algorithm includes fuzzy logic that has two functions: one is to regulate the magnitude of the input torque of the manipulators to not go beyond the torque saturation. The other function is to reduce trajectory tracking errors. To validate the proposed control algorithm, a numerical example using dual 3 degree-of-freedom manipulators is shown. (C) 1999 John Wiley & Sons, Inc.