Indirect Adaptive Feed-Forward Tracking Controllers

This paper presents a general indirect adaptive feed-forward control scheme for the purpose of tracking time varying signals. An approach which allows independent design of the adaptive identifier and the feed-forward tracking controller is given and so is the characterization of its tracking performance. When disturbances and unmodeled dynamics exist, methods such as signal filtering, dead zone and constrained parameter estimation are important for obtaining robust adaptive identifies, without which the standard approach could not be successful. Application to a hydraulic servo system, the dynamics of which are nonlinear, time varying and of infinite order, demonstrates the usefulness of the proposed adaptive scheme.