Robust Adaptive Algorithms for Reconfigurable Flight Control Systems
Robust Adaptive Algorithms for Reconfigurable Flight Control Systems

Author:

Publisher:

Published: 1998

Total Pages: 0

ISBN-13:

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The objective of the project was to develop adaptive algorithms for application to reconfigurable flight control. An emphasis of the research was on robustness issues related to unmodelled dynamics and actuator saturation. Areas of investigation included: (1) the development of real time parameter identification algorithms for situations where the information content of the data varies significantly over time; (2) the incorporation of integral compensation in adaptive control algorithms with bias cancellation capabilities; and (3) the design of command limiting methods for the alleviation of problems associated with actuator saturation. The results showed that relatively simple multivariable adaptive control algorithms could be designed that were effective in providing flight control reconfiguration over a wide range of flight conditions. A detailed fighter aircraft model was used to evaluate the performance of the reconfigurable control laws in simulations.

New Adaptive Methods for Reconfigurable Flight Control Systems. Appendix I (of 2).
New Adaptive Methods for Reconfigurable Flight Control Systems. Appendix I (of 2).

Author:

Publisher:

Published: 1995

Total Pages: 116

ISBN-13:

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The report discusses methods for the design of reconfigurable flight control systems. Model reference adaptive control algorithms were developed which allow for the rapid identification of aircraft parameters after failures or damages and for automatic control redesign. These algorithms are simple enough that they can be implemented in real-time with existing computers. Simulation results were obtained using a detailed nonlinear model of a fighter aircraft. The results demonstrate the ability of the adaptive algorithms to automatically readjust trim values after failures, to restore tracking of the pilot commands despite the loss of actuator effectiveness, and to coordinate the use of the remaining surfaces in order to maintain the decoupling between- the rotational axes. The report also discusses analytical results that were obtained during the course of the research regarding the stability and convergence properties of multivariable adaptive control algorithms, the use of averaging methods for the analysis of transient response and robustness, and the estimation of uncertainty in dynamic models. A modified recursive least-squares algorithm with forgetting factor is also described which gives fast adaptation under normal conditions while keeping the sensitivity to noise limited when signal to noise ratios are poor.

Application of Sliding Mode Methods to the Design of Reconfigurable Flight Control Systems
Application of Sliding Mode Methods to the Design of Reconfigurable Flight Control Systems

Author: Scott R. Wells

Publisher:

Published: 2002

Total Pages: 624

ISBN-13:

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Observer-based sliding mode control is investigated for application to aircraft reconfigurable flight control. An overview of reconfigurable flight control is given, including a review of the current state-of-the-art within the subdisciplines of fault detection parameter identification, adaptive control schemes, and dynamic control allocation. Of the adaptive control methods reviewed, sliding mode control (SMC) appears promising due its property of invariance to matched uncertainty. An overview of SMC is given and its properties are demonstrated. Sliding mode methods, however, are difficult to implement because unmodeled parasitic dynamics cause immediate and severe instability. This presents a challenge for all practical applications with limited bandwidth actuators. One method to deal with parasitic dynamics is the use of an asymptotic observer. Observer-based SMC is investigated, and a method for selecting observer gains is offered. An additional method for shaping the feedback loop using a filter is also developed. It is shown that this SMC prefilter is equivalent to a form of model reference hedging. A complete design procedure is given which takes advantage of the sliding mode boundary layer to recast the SMC as a linear control law. Frequency domain loop shaping is then used to design the sliding manifold. Finally, three aircraft applications are demonstrated. An F-18/HARV is used to demonstrate SISO and MIMO designs. The third application is a linear six degree-of-freedom advanced tailless fighter model. The observer-based SMC is seen to provide excellent tracking with superior robustness to parameter changes and actuator failures.

Robust Adaptive Flight Control Systems in the Presence of Time Delay
Robust Adaptive Flight Control Systems in the Presence of Time Delay

Author: Megumi Matsutani

Publisher:

Published: 2013

Total Pages: 165

ISBN-13:

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Adaptive control technology is a promising candidate to deliver high performance in aircraft systems in the presence of uncertainties. Currently, there is a lack of robustness guarantees against time delay with the difficulty arising from the fact that the underlying problem is nonlinear and time varying. Existing results for this problem have been quite limited, with most results either being local or at best, semi-global. In this thesis, robust adaptive control for a class of plants with global boundedness in the presence of time-delay is established. This class of plants pertains to linear systems whose states are accessible. The global boundedness is accomplished using a standard adaptive control law with a projection algorithm for a range of non-zero delays. The upper bound of such delays, i.e. the delay margin, is explicitly computed. The results of this thesis provide a highly desirable fundamental property of adaptive control, robustness to time-delays, a necessary step towards developing theoretically verifiable flight control systems.

Fault-tolerant Flight Control and Guidance Systems
Fault-tolerant Flight Control and Guidance Systems

Author: Guillaume J. J. Ducard

Publisher: Springer Science & Business Media

Published: 2009-05-14

Total Pages: 268

ISBN-13: 1848825617

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This book offers a complete overview of fault-tolerant flight control techniques. Discussion covers the necessary equations for the modeling of small UAVs, a complete system based on extended Kalman filters, and a nonlinear flight control and guidance system.

Challenges and Paradigms in Applied Robust Control
Challenges and Paradigms in Applied Robust Control

Author: Andrzej Bartoszewicz

Publisher: BoD – Books on Demand

Published: 2011-11-16

Total Pages: 476

ISBN-13: 9533073381

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The main objective of this book is to present important challenges and paradigms in the field of applied robust control design and implementation. Book contains a broad range of well worked out, recent application studies which include but are not limited to H-infinity, sliding mode, robust PID and fault tolerant based control systems. The contributions enrich the current state of the art, and encourage new applications of robust control techniques in various engineering and non-engineering systems.