hadi chahkandi nejad - IAU Birjand Branch. Department of Electrical Engineering, Head of Department.
Mohsen Farshad - Faculty of Electrical and Computer Engineering, University of Birjand, Birjand, Iran
Ramazan Havangi - Faculty of electrical and computer engineering, University of Birjand, Birjand, Iran.

In this study, an adaptive controller for LTI systems with unknown and time varying input time delay is presented with the purpose of tracking. Due to the large area considered for time delay variations, the structure of the proposed controller is considered to be in form of Multiple Model Adaptive Control (MMAC). The presented adaptive control system is of indirect type, i.e., at any moment of time, first, one band of time delay is identified using a proposed estimator, and then with a switching rule in the supervisory subdivision, the main control signal, which is a linear combination of multiple controllers output, forms. In fact, each of the multiple controllers in MMAC structure with optimal weights, participate in forming the main control signal. The multiple controllers used in this study are of PID type. It should be noted that the parameters for each of the multiple controllers, for the system under control, are adjusted offline and proportional to its corresponding time-delay sub-band using the genetic algorithm. Finally, simulation results show the relatively desirable performance of the proposed control system and observer in facing with large unknown and time varying delays.

Adaptive control, Time Varying Input Delay, Delay Estimation, Kalman Filtering, Satellite telecommunications