Disturbance Rejection: on-line refinement of controllers by closed loop modelling

Many practical applications of control system design based on input-output measurements permit the repeated application of a system identification procedure operating on closed loop data together with successive refinement of the designed controller. Recently several iterative schemes for mutually enhanced plant identification and robust control design have been proposed [l]-[3]. In this paper we shall analyze the methodology of [1] from the viewpoint of closed loop signal conditioning and investigate the effect of the noise modelling error and plant modelling error on the closed loop performance.