On characteristic roots and stability charts of delay differential equations

2011 ◽  
Vol 22 (8) ◽  
pp. 892-917 ◽  
Author(s):  
D. Breda
Author(s):  
Sun Yi ◽  
Sangseok Yu

In this short paper, the preliminary result of a new method for estimation of time-delays of time-delay systems is presented. The presented method makes use of the Lambert W function, and is for scalar first-order delay differential equations (DDEs). Possible extension to general systems of DDEs and application to physical systems are also discussed.


2017 ◽  
Vol 24 (17) ◽  
pp. 3944-3951 ◽  
Author(s):  
Samukham Surya ◽  
C. P. Vyasarayani ◽  
Tamás Kalmár-Nagy

In this work, we develop a homotopy continuation method to find the characteristic roots of delay differential equations with multiple delays. We introduce a homotopy parameter μ into the characteristic equation in such a way that for μ = 0 this equation contains only one exponential term (corresponding to the largest delay) and for μ = 1 the original characteristic equation is recovered. For μ = 0, all the characteristic roots can be expressed in terms of the Lambert W function. Pseudo-arclength continuation is then used to trace the roots as a function of μ. We demonstrate the method on several test cases. Cases where it may fail are also discussed.


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