LQG/LTR Design of a Robust Flight Controller for the STOL F-15
LQG/LTR Design of a Robust Flight Controller for the STOL F-15

Author: Gregory L. Gross

Publisher:

Published: 1985

Total Pages: 182

ISBN-13:

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A robust controller for the approach and landing phase of the Short Take-off and Landing (STOL) F-15 is developed via LQG/LTR (Linear System model, Quadratic cost, Gaussian models of uncertainty, used for controller synthesis, with Loop Transmission Recovery techniques of tuning the filter in the loop for control robustness enhancement) methods. Reduced-order full-state feedback controllers are synthesized using CGT/PT (Command Generator Tracking feedforward compensator to incorporate handling qualities, with Proportional plus Integral feedback) synthesis, specifically using implicit model following to provide good robustness characteristics in the full-state feedback case. The robustness is fully assessed using realistic simulations of the real-world system with meaningful deviations from design conditions. Once a Kalman filter is embedded into the loop to estimate states rather than assuming artificial access to all states, LTR methodology is used to preserve as much robustness as possible. A full assessment of performance and robustness of these final implementable designs is provided. Keywords: LQG/LTR, Multivariable Control, STOL, Kalman Filter, and Model Following Controller.

An LQG Up-and Away Flight Control Design for the STOL F-15 Aircraft
An LQG Up-and Away Flight Control Design for the STOL F-15 Aircraft

Author: Robert A. Houston

Publisher:

Published: 1985

Total Pages: 243

ISBN-13:

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A robust controller for the STOL F-15 aircraft is developed using the LQG/LTR (linear system model, quadratic cost, gaussian models of uncertainty used for controller synthesis, with loop transfer recovery techniques of tuning the filter in the loop for control robustness enhancement) methods. Full state feedback controllers are synthesized using CGT/PI (Command Generator Tracking feedforward compensator to provide direct incoporation of flying qualities into the design process, with proportional plus integral feedback control) synthesis, using implicit model following techniques to improve full state robustness characteristics. Finally, a Kalman filter is used to replace the unrealistic assumption of full state availability with estimated states, using a LTR scheme to recover as much full state robustness characteristics as possible. (Thesis) Keywords: Optimal Control, Model-Following Control, Robustness, Proportional-Integral Control, STOL Aircraft Control, Flight Control Systems.

A Lateral-directional Controller for High-angle-of-attack Flight
A Lateral-directional Controller for High-angle-of-attack Flight

Author: William A. Ehrenstrom

Publisher:

Published: 1983

Total Pages: 199

ISBN-13:

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A digital flight control system based on microprocessor technology has been designed, developed, and flight tested using the Avionics Research Aircraft (ARA). The control system utilizes the existing microprocessor system available in the aircraft's fly-by-wire control system. The command and stability augmentation control law was developed using modern control theory and is incorporated into existing flight control computer programs. Development of the model and control law, the gain scheduling procedure, and the flight test results are presented. The objctive of the study was to provide lateral-directional stability during high-angle-of-attack flight and into the stall regime. Flight test results show that it is indeed possile to design a control system which will eliminate lateral-directional instabilities and do so at a level higher than the pilot was able to attain.