This paper investigates the problem of speed cruise control in high-speed trains, which are modeled as large-scale systems with each car considered as an independent subsystem. Decoupled \({\mathcal H}_{\infty}\) controllers are employed for each car. To address parameter uncertainties and time-varying delays, a comprehensive analysis of the robustness and time-delay stability of the large-scale system was conducted, which led to the design of decoupled controllers. Simulations and comparative analyses were conducted to validate the correctness of the control algorithm and demonstrate the feasibility of controlling high-speed trains as large-scale time-delay systems. This study has yielded theoretical results in large-scale system control, successfully applying results to high-speed train control. The idea and method offer new perspectives and lay the foundation for addressing more complex issues in high-speed trains.
