Signal Compensation Method for Time-Varying Adaptive Control

This paper presents a new method to improve the performance of an adaptive controller under the time-varying environment. In general, under the time-varying environment the adaptive controller will not perform satisfactorily because the estimated parameters cannot track the real parameters exactly. Consequently, the resulting closed-loop system will differ from the one we expected. In order to obtain a satisfatory performance specified in the design criteria, the command sigal should be compensated to accommodate the deviation. In the new method, the resulting closed-loop system is treated as another time-varying plant to be controlled. We then design a higher order adaptive controller according to the original design criteria to control this inner closed-loop system. The simulation results show a significant performance improvement by using the new method.