Robust, Practical Adaptive Control for Launch Vehicles

A modern mechanization of a classical adaptive control concept is presented with an application to launch vehicle attitude control systems. Due to a rigorous flight certification environment, many adaptive control concepts are infeasible when applied to high-risk aerospace systems; methods of stabil...

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Bibliographic Details
Published inNASA Center for AeroSpace Information (CASI). Conference Proceedings
Main Authors Orr, Jeb S, VanZwieten, Tannen S
Format Conference Proceeding
LanguageEnglish
Published Hampton NASA/Langley Research Center 13.08.2012
Subjects
Adaptive control
Aerospace systems
Algorithms
Attitude control
Automatic pilots
Bending
Complexity
Computer simulation
Control stability
Design standards
Feedback control
Flexible bodies
Flight control
Launch vehicles
Linear filters
Mechanization
Performance enhancement
Research vehicles
Robust control
Spacecraft
Stability analysis
Thrust vector control
Vehicles
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Summary:A modern mechanization of a classical adaptive control concept is presented with an application to launch vehicle attitude control systems. Due to a rigorous flight certification environment, many adaptive control concepts are infeasible when applied to high-risk aerospace systems; methods of stability analysis are either intractable for high complexity models or cannot be reconciled in light of classical requirements. Furthermore, many adaptive techniques appearing in the literature are not suitable for application to conditionally stable systems with complex flexible-body dynamics, as is often the case with launch vehicles. The present technique is a multiplicative forward loop gain adaptive law similar to that used for the NASA X-15 flight research vehicle. In digital implementation with several novel features, it is well-suited to application on aerodynamically unstable launch vehicles with thrust vector control via augmentation of the baseline attitude/attitude-rate feedback control scheme. The approach is compatible with standard design features of autopilots for launch vehicles, including phase stabilization of lateral bending and slosh via linear filters. In addition, the method of assessing flight control stability via classical gain and phase margins is not affected under reasonable assumptions. The algorithm s ability to recover from certain unstable operating regimes can in fact be understood in terms of frequency-domain criteria. Finally, simulation results are presented that confirm the ability of the algorithm to improve performance and robustness in realistic failure scenarios.