Abstract
Resently various design methods of MRACS (Model Reference Adaptive Control System) have been proposed for plant with deterministic disturbance. But in order to apply MRACS to practical systems, it is desirable that MRACS can also be valid for undeterministic disturbance. For bounded disturbance, there have existed an stable adaptive control method which assures the output error of plant to be bounded by using a dead-zone, but this method cannot make the output error tend to zero. Therefore the method is not an active way in the sence of decreasing the effect of disturbance.
This paper deals with a design method of MRACS for discrete plant with unknown parameters in the presence of disturbances. The disturbances are assumed to be: (1) polynomial of time, or (2) periodic, or (3) varying slowly, or (4) the linear combination of (1), (2), (3). By introducing a disturbance compensator, the MRACS is composed with no increasing of numbers of parameter needed to adjust. It is possible to make the output error tend to asymptotically zero with time for the cases (1) and (2). For the cases (3) and (4), it is possible to reduce the effect of disturbances to a small value. The stability of this MRACS, and the boundedness of all signals in the system are proved if the plant is minimum phase and the disturbance is bounded. The effectiveness of this proposed method is illustrated by computer simulations.
