A Design Method of MRACS for the Plants with Slowly Varying Undeterministic Disturbance

The Method Using a Time Delay Controller

Abstract

This paper is to propose a design method of MRACS (Model Reference Adaptive Control System) for unknown plants with slowly-varying disturbance w(t), by which the output error from the desired behavior can be reduced to a small value.
The control system is composed by using time delay controllers which compensate the effect of disturbance. To insure the stability of the control system an adaptive adjustment law with dead-zone is introduced. As analyzed theoretically, by the proposed control method the influence of the disturbance on the output will be reduced to the level of [w(t)-w(t-T)], where T is the delay time. So when the disturbance varies solowly, the steady state error can be made sufficiently small by selecting a small delay time T. Especially when the disturbance is constant, such as step-wise, it is possible to let the steady state error be zero. The effectiveness of the proposed method is illustrated by some computer simulations.