Accelerating Convergence of Sum-of-Square Stability Analysis of Coupled Differential-Difference Equations

This article aims at accelerating the convergence of Lyapunov-Krasovskii stability analysis of coupled differential-difference equations using sum-of-square formulation. Under the assumption that the single integral and double integral terms are both positive definite, a necessary and sufficient condition for the quadratic integral expression is obtained. This result is applied to the Lyapunov-Krasovskii functional and derivative conditions. The method is less conservative than the previous method with identical order of polynomials. The effectiveness of this method is illustrated by numerical examples.