Addressing limits of operability of the scramjet engine in adaptive control of a generic hypersonic vehicle

This paper considers the incorporation of limits of operability of the scramjet engine in a previously developed adaptive guidance and flight control architecture for the 6-DOF model of a generic hypersonic air-breathing vehicle. Lower bounds on the throttle setting arise from the necessity of maintaining a minimal fuel rate due to thermal management considerations, whereas an upper bound must also be imposed to avoid the occurrence of inlet unstart. A dynamic reference management is presented for the adaptive inner-loop module of the flight control architecture that provides tracking of airspeed reference trajectories. A feasible input reference trajectory (which depends on the parameter estimates) is provided to the adaptive controller so that convergence to a feasible setpoint for the throttle setting is attained. A simulation study is presented to validate the proposed methodology.