Decoupling Vibration Control for a Two-Link Manipulator

Abstract

Due to the influence of the coupling torque in the two-link manipulator, the disturbance observer (DOB) method cannot achieve an ideal vibration suppression effect. A velocity controller is proposed, including a decoupler and a rigid-body state observer (RBSO), to simultaneously decrease the coupling torque and vibrations. The two-link manipulator is modelled as a two-input two-output (TITO) system in this paper. The decoupler is designed based on the dynamic model of the TITO system in a simplified structure. The RBSO contains a state observer (SOB) and a damper. The SOB obtains a rigid-body velocity from its state variable. The damper feeds back the error between the rigid-body velocity and link velocity to a proportional-integral controller to add system damping, achieving vibration suppression. The effectiveness to decrease coupling torque and vibrations of the proposed method are verified in simulations.