Robust $H_{\infty}$ Control and Smooth Transition of Thrust Closed-Loop and Inlet Unstart for Scramjet

To meet the performance requirements of fast and accurate control for the scramjet control system, this study utilizes a control-oriented model based on small perturbation dynamics. The main thrust closed-loop control and inlet unstart protection control systems are designed based on the robust <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$H_{\infty}$</tex> control algorithm. A soft switching method is employed to achieve smooth transitions between the two control modes, reducing control signal fluctuations during controller switching. Simulation results demonstrate that the designed controllers exhibit excellent control performance, enabling overshoot-free control of the scramjet. Compared to a direct switching system, the control system with soft switching achieves smooth and non-disruptive transitions, effectively suppressing control oscillations caused by switching processes, and ensuring the control effectiveness and operational safety of the engine.