Scramjet Operation Guaranteed Longitudinal Control of Air-Breathing Hypersonic Vehicles

Abstract

Due to the unique airframe/scramjet integration of air-breathing hypersonic vehicles (AHVs), flight status has complex influences on scramjet efficiency. This article studies the longitudinal control problem of AHVs configured with the variable geometry inlet, in parallel with full considerations on scramjet operation. In velocity loop, an adaptive velocity reference generator is constructed to accommodate the state-dependent constraint on fuel-to-air equivalency ratio that is required by the avoidance of scramjet thermal choking. Meanwhile in altitude loop, the state-dependent constraint on angle-of-attack is handled by robust adaptive control laws, in which case the inlet inhales enough airflow. The developed controller is able to maintain necessary conditions for scramjet operation while accommodating practical uncertain factors and ensuring satisfactory tracking performances.