TY  - JOUR
AU  - Yi, Sun 
AU  - Choi, Wonchang 
AU  - Abu-Lebdeh, Taher 
PY  - 2012
TI  - Time-Delay Estimation using the Characteristic Roots of Delay Differential Equations
JF  - American Journal of Applied Sciences
VL  - 9
IS  - 6
DO  - 10.3844/ajassp.2012.955.960
UR  - https://thescipub.com/abstract/ajassp.2012.955.960
AB  - Problem statement: For ordinary dynamic systems (i.e., non-delayed), various methods such as linear least-squares, gradient-weighted least-squares, Kalman filtering and other robust techniques have been widely used in signal processing, robotics, civil engineering. On the other hand, time-delay estimation of systems with unknown time-delay is still a challenging problem due to difficulty in formulation caused. Approach: The presented method makes use of the Lambert W function and analytical solutions of scalar first-order Delay Differential Equations (DDEs). The Lambert W function has been known to be useful in solving delay differential equations. From the solutions in terms of the Lambert W function, the dominant characteristic roots can be obtained and used to estimate time-delays. The function is already embedded in various software packages (e.g., MATLAB) and thus, the presented method can be readily used for time-delay systems. Results: The presented method and the provided examples show ease of formulation and accuracy of time-delay estimation. Conclusion: Estimation of time-delays can be conducted in an analytical way. The presented method will be extended to general systems of DDEs and application to physical systems.