Adaptive Attitude and Vibration Control of the NASA Ares Crew Launch Vehicle

Abstract

The control system of the NASA Crew Launch Vehicle is designed to meet performance and robustness requirements during its ascent ∞ight phase. However, the controller bandwidth and the attainable level of robust performance is limited by the degree of ∞exibility inherent in the long and slender design that has been adopted for this vehicle. Since there remains a substantial degree of uncertainty regarding the structural dynamics of this vehicle, the degree of risk associated with ∞ight control is reduced by permitting a greater level of robust performance to be attained by augmenting the existing ∞ight control system design with an adaptive element. Attitude stabilization and ∞exible mode suppression of the model is achieved by using a model reference adaptive controller designed to maintain nominal tracking performance in the presence of disturbances, parametric uncertainties and unmodeled dynamics. The control law employs an output feedback neural network adaptive element which augments an existing decoupled gain scheduled linear control law in a centralized manner to expand the class of uncertainty the system can potentially suppress. The resulting closed loop system can be shown to be uniformly ultimately bounded through a Lyapunov-like stability analysis.