We use the concept of Lyapunov stability instead of the M-matrix or quasi-diagonal dominance techniques to treat the robust stability problem for large-scale time-delay systems. The allowable bounds of structured and unstructured uncertainties which maintain the stability of the systems are derived. For the unstructured uncertain system, the robustness bounds are obtained directly from the system matrices even without solving the Lyapunov equation. Two main results are also applicable to the stability test and stabilization design.
