A Step-Switching Coordinate Strategy for AHV-VGI Based on Nonsingular Terminal Sliding Mode Control

This paper presents a step-switching coordinate strategy for Air-breathing hypersonic vehicle with variable-geometry scramjet inlet(AHV-VGI), which can improve the aerodynamic performance of hypersonic vehicle by moving the movable lip to capture more airflow. Firstly, we transform the longitudinal model of AHV-VGI into the strict feedback form and multiple nonlinear aerodynamic models are built with different elongation distance of translating cowl(EDTC). Secondly, the longitudinal model of AHV-VGI system with different EDTC is divided into the velocity subsystem and altitude subsystem, which is designed by a finite-time nonsingular terminal sliding mode control method. Then, the common Lyapunov function is constructed to prove the stability of the closed-looped switching system with the control algorithms. Finally, simulation results are provided to validate the effectiveness of these theoretical results.