Abstract
In the model reference adaptive control system (MRACS) by indirect approach, the control input to plant is adaptively synthesized by using the estimates obtained from plant parameter identification. In the conventional schemes, the identification model is constructed corresponding to a plant-output representation, which requires a division by a parameter estimate for synthesizing the control input. This means that the control input may become unbounded. This defect can be overcome by constructing the identification model corresponding to a plant-input representation. This paper presents a design method for discrete type of MRACS based on the above idea.
In this paper, a nonminimal representation with respect to the plant input is first derived and then two schemes-constant gain type and variable gain type-are presented for identifying the parameters of the above representation. A method is then given for synthesizing the control input using the identified values, and the asymptotic staility of the overall adaptive system is discussed by Liapunov's second method. Finally, the computer simulation results are presented and it is demonstrated that the variable gain type of adjustment law yields a superior adaptation response to the constant gain type.
