PID composite controller and its tuning for flexible link robots

This paper proposes a PID-type composite controller for controlling flexible arms modeled by the singular perturbation approach, and investigates a tuning method based on the proposed controller structure. For the slow sub-controller, a PD plus disturbance observer is used, which eventually takes on PID form, and for the fast sub-controller, modal feedback PID control is utilized. The effects of design parameters of the controller on the closed loop response are investigated. Through simulation and experiments, the adequacy and performance of the proposed method are verified.