Abstract
In this paper, a design method of model reference adaptive control systems (MRACS) with inaccessible states using Liapunov's direct method is described.
First we introduce an error equation which governs a motion of the difference between the plant states and the model states. Then a full order observer is applied for thus obtained error equation, and the adaptive law is constructed by using the outputs of the observer. Stability of the whole MRACS is guaranteed as seen by applying the eventual stability theorem given by LaSalle and Rath in 1964.
The above mentioned MRACS problems have already been treated by Ohta (1974) from the point view of Popov's hyperstability theorem. But the condition obtained by him is too restrictive, so that it seems to be difficult to apply his method to general MRACS with inaccessible states. Such problems are also examined to compare Ohta's method with our method proposed here.
