Discrete-Time Adaptive Control Using Multiple Models

In a recent paper [1] the authors proposed a new methodology for the adaptive control of a linear time-invariant plant using multiple models which is significantly different from the "switching" and "switching and tuning" methods which have been in use for over a decade. Extensive simulation studies have also revealed that the performance using the new method is far superior to earlier methods. In this paper an attempt is made to extend the same concepts to the adaptive control of discrete-time systems. It is well known that the control of discrete-time systems is simpler than the control of their continuous-time counterparts, that they find wider application in practice, and that the proofs of stability are substantially simpler. Also, in many cases (e. g. periodic systems) discrete-time control may be possible when even the formulation of tractable problems in continuous-time is impossible. The objective of this paper is to examine how the methodology proposed differs in the two cases with regard to transparency of the principal concepts, and effectiveness in practical applications.