H-INFINITY CONTROL OF A CLASS OF NONLINEAR-SYSTEMS USING DESCRIBING FUNCTIONS AND SIMPLICIAL ALGORITHMS

This paper describes a new method for generating an H-infinity control ler for a nonlinear system whose nonlinearities are modeled as describ ing functions. It is a three-step approach: modeling (using the descri bing function approach), synthesis (using the H-infinity loop shifting technique), and robustness analysis (using the labeling technique of simplicial algorithms). The method is first demonstrated by designing an optimal H-infinity controller for a first-order linear unstable sys tem driven by a Bang-Bang actuator. A more complex example is used nex t to demonstrate loop shifting and simplicial algorithms as applied to a suboptimal problem. This system was implemented on a digital comput er and in analog circuit form to demonstrate the practicality of the m ethod.