Opportunities and limitations of adaptive augmented control for launch vehicle attitude control in atmospheric flight

This paper investigates the benefits and the possible issues related to the use of an Adaptive Augmented Control system for launch vehicle attitude control in atmospheric flight. A time-frozen analysis is conducted, assuming a linear timeinvariant model of the rocket rigid body dynamics plus flexibility and parasite TVC dynamics for two launch-vehicle configurations, representative of a small launch vehicle and a large one, whose data are available in literature. The AAC system architecture is recalled and critically analyzed. An automatic gain tuning procedure is devised for the AAC adaptation gains, while refined tuning guidelines are provided for spectral damper filters. Eects of the AAC on the stability and robustness with respect to the baseline, that is non-augmented, controlled system are discussed by means of numerical simulations carried out in the time domain as well as using tools from linear system analysis in the frequency domain.