Parameter identification of a perturbed servomechanism operating in closed loop under PID control

This paper presents a methodology for closed-loop identification of a position-controlled servomechanism subject to a constant disturbance. A Proportional Integral Derivative controller, which stabilizes the servomechanism without knowledge about its parameters, closes the loop. Theoretical results show that the integral action plays a fundamental role in counteracting the effect of the disturbance on the parameter estimates. Experiments on a laboratory prototype show that the estimates obtained under disturbance conditions remain closer to that obtained under disturbance-free conditions.