DESIGNING OF A NEW ONLINE TIME DELAY OBSERVER AND ITS APPLICATION IN UNKNOWN TIME VARYING DELAY

Abstract

In this paper, a novel observer has been designed for the online estimation of time delay in SISOLTI continuous time systems with unknown and time variant delay in the control input. It is obvious that Laplace transfer function of a delayed system includes a time delay factor. In this article, it is assumed that the only unknown and time variant parameter in the system is the very system’s time delay parameter. The main idea used in designing the proposed observer is based on the establishment of duality principle between controller and observer, such that a direct adaptive controller structure (MRAS) is indirectly used for designing an estimator. For this, the main sections in an MRAS control system are organized the way that designing the controller will lead to designing the delay estimator in the dual problem. In fact, adaptation law in designing the controller will express the same estimator mechanism in the dual problem. Also, in designing the estimation mechanism, the two methods, one based on Lyapunov Theory and the other based on MIT rule, are used. Finally, simulation results on a Wi-Fi network as a benchmark system, show desirable performance of the proposed estimator in dealing with time varying and uncertain delays.