Flying qualities reduction of fly-by-wire commercial aircraft with reconfiguration flight control laws

ABSTRACTEfforts to develop the next generation of aircraft with ever-increasing levels of performance – higher, farther, faster, cheaper – face great technical challenges. One of these technical challenges is to reduce structural weight of the aircraft. Another is to look to aircraft configurations that have been unrealizable to date. Both of these paths can lead to a rigid flex coupling phenomenon that can result in anything from poor flying qualities to the loss of an aircraft due to flutter. This has led to a need to develop an integrated flight and aeroelastic control capability where structural dynamics are included in the synthesis of flight control laws. Studies have indicated that the application of an integrated flight and aeroelastic control approach to a SensorCraft high-altitude long-endurance vehicle would provide substantial performance improvement(1,2). Better flying qualities and an expanded flight envelope through multi-flutter mode control are two areas of improvement afforded by integrated flight and aeroelastic control. By itself, multi-flutter mode control transforms the flutter barrier from a point of catastrophic structural failure to a benign region of flight. This paper discusses the history and issues associated with the development of such an integrated flight and aeroelastic control system for the X-56A aircraft.

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Dynamic Output Feedback Flight Control Laws using Eigenstructure Assignment

10.23919/acc.1986.4789009 ◽

1986 ◽

Cited By ~ 1

Author(s):

Kenneth M. Sobel ◽

Eliezer Y. Shapiro

Keyword(s):

Flight Control ◽

Output Feedback ◽

Dynamic Output Feedback ◽

Eigenstructure Assignment ◽

Control Laws ◽

Dynamic Output

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String Instabilities in Formation Flight: Limitations Due to Integral Constraints

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.1858444 ◽

2004 ◽

Vol 126 (4) ◽

pp. 873-879 ◽

Cited By ~ 3

Author(s):

P. Seiler ◽

A. Pant ◽

J. K. Hedrick

Keyword(s):

Flight Control ◽

Formation Control ◽

Energy Savings ◽

Feedback Loops ◽

Formation Flight ◽

Control Laws ◽

Aerodynamic Efficiency ◽

Preceding Vehicle ◽

Specific Control ◽

Theoretical Results

Flying in formation improves aerodynamic efficiency and, consequently, leads to an energy savings. One strategy for formation control is to follow the preceding vehicle. Many researchers have shown through simulation results and analysis of specific control laws that this strategy leads to amplification of disturbances as they propagate through the formation. This effect is known as string instability. In this paper, we show that string instability is due to a fundamental constraint on coupled feedback loops. The tradeoffs imposed by this constraint imply that predecessor following is an inherently poor strategy for formation flight control. Finally, we present two examples that demonstrate the theoretical results.

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Automatic Flight Control of Unmanned Helicopter Based on Nonlinear Model

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.472-475.1492 ◽

2012 ◽

Vol 472-475 ◽

pp. 1492-1499

Author(s):

Run Xia Guo

Keyword(s):

Nonlinear Model ◽

Flight Control ◽

Attitude Control ◽

Lyapunov Stability Theory ◽

Test Results ◽

Unmanned Helicopter ◽

Control Laws ◽

Control Approach ◽

State Dependent ◽

Compensation Technique

The Unmanned helicopter (UMH) movement was divided into two parts, namely, attitude and trajectory motion. And then a two-timescale nonlinear model was established. The paper improved and expanded state dependent riccati equation (SDRE) control approach, deriving analytical conditions for achieving global asymptotic stability with lyapunov stability theory. Proof was given. By combining improved SDRE control with nonlinear feed-forward compensation technique, the full envelop flight attitude control laws could be designed. On the basis of attitude control, trajectory controller was developed. Actual flight tests were carried out. Test results show that the control strategy is highly effective.

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Enhanced Disturbance-Observer-Based Control for a Class of Time-Delay System with Uncertain Sinusoidal Disturbances

Mathematical Problems in Engineering ◽

10.1155/2013/805687 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Xinyu Wen

Keyword(s):

Time Delay ◽

Flight Control ◽

Disturbance Observer ◽

Delay System ◽

Delay Systems ◽

Flight Control System ◽

Control Laws ◽

Nonlinear Disturbance Observer ◽

Dynamic Performances ◽

Uncertain Disturbance

This paper is concerned with disturbance-observer-based control (DOBC) for a class of time-delay systems with uncertain sinusoidal disturbances. The disturbances are decomposed as precise and uncertain parts using nonlinear disturbance observer (DO) after appropriate coordinate transformation. And then the two parts can be compensated by corresponding controller, respectively, such that the classic DOBC method is extended to uncertain disturbance rejection. One novel feature of the proposed method is that even if the precise disturbance parameters are inaccessible, the merits of DOBC can be inherited. By integrating the disturbance observers with feedback control laws with time delay, the disturbances can be rejected and the desired dynamic performances can be guaranteed. Finally, simulations for a flight control system are given to demonstrate the effectiveness of the results.

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Flying qualities criteria and flight control design

10.2514/6.1981-1823 ◽

1981 ◽

Cited By ~ 6

Author(s):

D. BERRY

Keyword(s):

Flight Control ◽

Control Design ◽

Flying Qualities

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A Case Study on the Detection and Prognosis of Internal Leakages in Electro-Hydraulic Flight Control Actuators

Actuators ◽

10.3390/act10090215 ◽

2021 ◽

Vol 10 (9) ◽

pp. 215

Author(s):

Antonio Carlo Bertolino ◽

Andrea De Martin ◽

Giovanni Jacazio ◽

Massimo Sorli

Keyword(s):

Flight Control ◽

Particle Filtering ◽

Health Management ◽

State Of The Art ◽

Commercial Aircraft ◽

Flight Data ◽

Prognostic System ◽

Hydraulic Servo ◽

Definition Of

Electro-hydraulic servo-actuators (EHSAs) are currently considered the state-of-the art solution for the control of the primary flight control systems of civil and military aircraft. Combining the expected service life of a commercial aircraft with the fact that electro-hydraulic technology is employed in the vast majority of currently in-service aircraft and is planned to be used on future platforms as well, the development of an effective Prognostic and Health Management (PHM) system could provide significant advantages to fleet operators and aircraft maintenance, such as the reduction of unplanned flight disruptions and increased availability of the aircraft. The occurrence of excessive internal leakage within the EHSAs is one of the most common causes of return from the field of flight control actuators, making this failure mode a priority in the definition of any dedicated PHM routine. This paper presents a case study on the design of a prognostic system for this degradation mode, in the context of a wider effort toward the definition of a prognostic framework suitable to work on in-flight data. The study is performed by means of a high-fidelity simulation model supported by experimental activities. Results of both the simulation and the experimental work are used to select a suitable feature, then implemented within the prognostic framework based on particle filtering. The algorithm is at first theoretically discussed, and then tested against several degradation patterns. Performances are evaluated through state-of-the-art metrics, showing promising results and providing the basis towards future applications on real in-flight data.

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