Vibration control without estimated disturbance feedback for robot manipulators

This paper presents the vibration suppression control technique for the robot manipulators. To make the technique fit for practice, the presented robot controller is characterized by the function that considers the low-stiffness kept in the mechanical reduction gears in the robot joints. And it is designed as the sampled-data servo controller using the state space form digital disturbance observer. The reason not to utilize the transfer function form disturbance observer but the state space form one is to make the best use of the feature that the latter one can estimates not only disturbance but also the other state variables under the disturbance. And we suppose that the presented control method including above observer is essentially useful for such low-stiffness plants.