Observer based Vibration Damping controller design for a two link Lightweight Manipulator

Vibration of the light manipulator seriously affects the safety of human-machine interaction and the precision of motion control. In order to suppress the vibration of the manipulator, the coupling torque decoupling is the first problem to be solved. In addition, the coupling torque between the manipulator's joints can also cause other vibrations, reducing the vibration suppression effect. In this paper, a 7-DOF manipulator is equivalent to a two-link manipulator to simplify the size and complexity of the controller design. For a simplified two-link manipulator, a coupled torque observer is proposed to decouple the system into two independent joint systems based on the use of joint torque sensors. The two-link manipulator adopts a decentralized structure control based on the decoupling system. A two joints are controlled by an equivalent rigid body state observer to suppress vibration. Some simulations are finally performed to confirm the decoupling effect of coupled torque observer and the vibration reduction effect of equivalent rigid body state observer.