Presentation of a New Online Method, for Time Variant and Unknown Input Time Delay Estimation, in Continuous SISO-LTI Systems

Author(s): Hadi Chahkandi Nejad*, Mohsen Farshad, Ramazan Havangi

Journal Name: International Journal of Sensors, Wireless Communications and Control

Volume 10 , Issue 6 , 2020


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Abstract:

Aim: In this paper, a novel estimator is presented, for online time delay estimation, in single input-single output LTI systems, with time variant and uncertain delay in control input.

Background: The main studies made on systems with time-varying delay are divided into three general categories: (1) Identification and estimation of the delay. (2) Criteria presented for stability and robust stability. (3) Control methods presented with goals like tracking.

Objective: It is obvious that Laplace transfer function of a delayed system includes a time delay factor (exponential and non-rational). In this study, it is assumed that the only uncertain and time varying parameter in the system is the system’s time delay. The objective of this paper is to online estimate of this time delay.

Methods: For designing the proposed estimator, first, a Pade approximation is used for exponential factor of time delay to rationalize the system transfer function. Therefore, the new transfer function, which is an approximation of the main transfer function of the system, will include a time delay parameter (time-variant). After writing a state space realization of the mentioned transfer function and considering time delay parameter as an extra state variable, a system of nonlinear state equations will be generated. Eventually, using a kalman filter (linear and extended for linearized and nonlinear state equations), the systems states, such as system time delay, are estimated.

Results: Simulations were made on a sample system with input time delay, for different types of time delay signal.

Conclusion: Finally, simulations results show rather desirable performance of the proposed estimator in dealing with time varying and uncertain delays.

Keywords: Kalman filter, LTI systems, time varying input delay, uncertainty, delay estimation, pade.

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Article Details

VOLUME: 10
ISSUE: 6
Year: 2020
Published on: 10 February, 2021
Page: [935 - 944]
Pages: 10
DOI: 10.2174/2210327910666191216155745
Price: $25

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