Numerical Investigation of Model Reference Adaptive Control for Hypersonic Aircraft

Abstract

To address the attitude control of hypersonic aircraft, an approach of direct model reference adaptive control (MRAC) is followed. The basis for MRAC is that a system of which only the outputs are known has to track a reference model that can be a simple approximation of the actual system. By combining the output error, the model state, and the model control parameters into a reference signal, proportional and integral gains can be computed that are adapted to the value of the reference signal. To apply MRAC it is necessary that the controlled nonlinearsystemisalmoststrictlypassive.Thedesignofthecombinedlongitudinal/lateralMRACsystemiscentred around a linearized reference model of the winged cone cone guration at a Mach 5.6 e ght condition. The results of some fundamental response tests are discussed, as well as altitude and cross-range transitions. It appears that MRAC seems to be a promising concept when applied to hypersonic space planes. Although it is too early to say that the current cone guration of the controller is robust with respect to design uncertainties and environmental perturbations,therearestillmany improvementspossiblethatwillenhanceperformance.Onedrawback,however, is the large number of design parameters that can be tuned to ine uence the performance.