Simple adaptive control of uncertain plants

This paper considers adaptive control of various systems with unknown time-varying or nonlinear dynamics in an attempt to show that practical adaptive control can be both simple and robust. The simplified adaptive control methodology used is based on the observation that most real-world systems, even nonstationary or non nonlinear, can be stabilized by simple controller configurations. More complex controllers may be needed only in order to improve the performance of the control systems. In the adaptive scheme, the stabilizability properties of the plants are used only to satisfy the necessary conditions that guarantee robustness of simple adaptive controllers. The desired performance is then imposed upon the plant by these adaptive controllers that force the plant to follow the input-output behavior of low-order reference models. Numerous examples from the recent literature of control with uncertainty are used to illustrate the power of these adaptive techniques.