Practical criterion in the stability analysis of linear control system with time-delay

Criterions for stability of a linear control system with time-delay are widely applied in various fields such as microwave electronics, mobile satellites communication. Although conventional criterions by characteristic equations Is perfect from a theoretic point of view, it Is not very practical for real calculation, since the characteristic equation of a linear control system with time-delay is a transcendental equation. This paper present a practical criterion for stability analysis. By introducing some one-to-one transformations the transcendental characteristic equation concerned is converted to a polynomial. Based on this, a criterion which can be easily used by engineers is obtained.