ABSTRACT
Adaptive control can be viewed as a special type of nonlinear feedback control, since when the adaption/adaptive action is on, the linear control system, as a whole, behaves like a nonlinear system. In an adaptive control, in most cases, the states of the systems are such that some change slowly with time and the latter can be regarded as parameters also. In an adaptive control, there is a feature for automatic adjustment of the controllers in real time to achieve and maintain a desired level of performance of the control system. The adaptive controller is a dynamic system with online parameter estimation in most cases, and being adaptive, the adaptive control system/scheme then becomes inherently nonlinear. In explicit indirect adaptive control (EIAC), the identification error is used for updating the control parameters, whereas for IDAC, for the same purpose, the control error is used. For the EIAC, if the adaptive observer/estimator/filtering algorithm converges, then the adaptive controller should also converge.
