Disturbance Rejection Through an External Model

Abstract

This paper considers the use of external models for the cancellation of disturbances that can be regarded as output of stable (in the sense of Lyapunov) autonomous systems. The external model is set up outside the feedback loop so that the design of the feedback controller is accomplished without favoring particular disturbances. External model controllers can, therefore, be add-on devices to existing control systems. An application to track-following in a disk-file actuator system is presented.