IEEE CSS Italy Chapter - Seminar "Addressing Limits of Operability of Scramjet Engines in Nonlinear Adaptive Flight Controllers for Hypersonic Vehicles" Prof. Andrea Serrani - Department of Electrical and Computer Engineering The Ohio State University
Abstract
Air breathing hypersonic vehicles ( offer a promising technology for reliable access to space for commercial and military applications. Among many outstanding problems in flight control system design for HSVs, one of the most challenging is to simultaneously account for the inevitable constraints on the control inputs and the stringent limits of vehicle operability at hypersonic speed.
In particular, state dependent constraints on the propulsion system arise as a result of the complex physics of combustion at hypersonic speed and the tight integration between engine and airframe The envelope of operating conditions for a typical scramjet engine is bounded by thermal and structural limitations, and combustion stability Lower bounds on the throttle setting arise from the necessity of maintaining a minimal fuel rate for thermal management, whereas trajectory dependent constraints on angle of attack and sideslip angle must also be imposed to avoid the occurrence of inlet unstart at a given. Mach number In addition, thermal chocking occurs from excessive heat addition in the combustor when acceleration commands are too aggressive, hence incompatible with the physical limit of the engine This talk considers the incorporation of limits of
operability of the scramjet engine in a previously developed adaptive guidance and flight control architecture for a 6 DOF model of a generic hypersonic air breathing vehicle A dynamic reference management is presented for the adaptive inner loop module of the flight controller that provides tracking of airspeed reference trajectories. A model recovery anti windup strategy is teamed with a reference governor so that feasible input reference trajectories (which depends on parameter
estimates) are provided to the adaptive controller, so that convergence to a feasible setpoint for the throttle setting is attained.
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