American Institute of Aeronautics and Astronautics
A linear fractional transformation (LFT) model of the linearized equation of the lateral-directional axes of the X-38 crew return vehicle is developed to facilitate the analysis of flight control systems. The LFT model represents uncertainty in nine aerodynamic stability derivatives at a given flight condition with frequency-domain performance specifications. The X-38 LFT model combined with a controller at specific flight conditions is used to determine the aerodynamic coefficients that result in the worst-case performance and gain/phase margin of the closed-loop system. The objective is to verify that a given controller remains stable and achieves desired performance objectives for all predefined aerodynamic variations at select operating conditions along its flight trajectory.
Shin, J., Balas, G. J., and Packard, A. K. (2001). "Worst-Case Analysis of the X-38 Crew Return Vehicle Flight Control System." Journal of Guidance, Control, and Dynamics. 24(2), 261-269.
Reprinted with permission of the American Institute of Aeronautics and Astronautics, Inc. See http://www.aiaa.org/content.cfm?pageid=2 for more information.
Shin, Jong-Yeob; Balas, Gary J.; Packard, Andrew K..
Worst-Case Analysis of the X-38 Crew Return Vehicle Flight Control System.
American Institute of Aeronautics and Astronautics.
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