On Nonlinear Dynamics and Flight Control at High Angles of Attack With Uncertain Aerodynamics

Pereira, Mateus de Freitas Virgílio; Prado, Igor Afonso Acampora; Castro, Davi Ferreira de; Balthazar, José Manoel; Silva, Roberto Gil Annes da; Nabarrete, Airton

doi:10.1115/imece2016-67108

Cited by 4 publications

(3 citation statements)

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“…Pedro and Mansfield present a detailed nonlinear aircraft model considering thrust vectoring as an augmented control signal along with a nonlinear dynamic inversion controller for pitch acceleration longitudinal mode of the aircraft at high AoA and post-stall considerations [19]. In another work, an optimal feedback method recovers a fighter aircraft with uncertain aerodynamic coefficients and stochastic parametric uncertainties at high AoA, from stall condition by employing polynomial chaos expansion [20].…”

Section: Adaptive Inverse Compensation Techniquesmentioning

confidence: 99%

Adaptive Compensation at High Angles of Attack

Deb¹,

Burkholder²,

Tao³

2021

Adaptive Compensation of Nonlinear Actuators for Flight Control Applications

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High AoA flight poses unique aerodynamic challenges, and these issues are studied extensively over the years [1]. An air vehicle at high AoA allows the pilot to rapidly nose-point to ensures a decisive action on the enemy. That is why next-generation aircraft must be able to operate consistently at higher and higher AoA than before and in a controlled fashion, thereby posing newer challenges in control, especially with the possible deployment of SJAs. Freezing conditions can also promote a local high AoA flow condition where ice accumulation on the tail leading edge may have an equivalent effect of a full-span stall strip [2]. The trend in the next-generation air vehicle design is towards increased exploitation of high-AoA aerodynamics and flow-field interactions. The relevance of high AoA studies is widespread, contrary to the general understanding that the pilot of a light single-engine propeller-driven air vehicle may also encounter high AoA aerodynamics as frequently as the pilot of a modern high-performance fighter.Boundary layer flow separation is an undesirable phenomenon in almost all technical scenarios, and especially the point of flow separation and the AoA at which such an event occurs on the wings of air vehicles is of interest in this work. Flow separation causes loss of lift and (or) increased drag and reduction in retained energy. Therefore, there has been extensive research on the study of flow separation and ways and means to eliminate or delay the event. At high AoA, there is diminished flow attachment, and the separation takes place further and further away from the leading edge, thereby providing a diminished lift force. The resultant flows get controlled by airframe shaping or actively ensured by mechanical, pneumatic or active flow control devices like SJAs. In recent work, Linehan et al. demonstrate a servo-controlled sliding alula actuator to reorient separated flows at high AoA without undesired transients caused by the shedding effect of a stall vortex using a customized autopilot board and a 9-axis IMU for feedback control [3]. Other actuators which are used in high AoA separation control include weakly ionized plasma actuators consisting of

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Section: Adaptive Inverse Compensation Techniquesmentioning

confidence: 99%

Adaptive Compensation at High Angles of Attack

Deb¹,

Burkholder²,

Tao³

2021

Adaptive Compensation of Nonlinear Actuators for Flight Control Applications

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“…Consequently, disregarding nonlinear aspects can be a limiting factor in the capabilities of the representative model of the system and consequently of its electronic controllers. According to [2], for a more realistic model, the nonlinearities and uncertainties intrinsically present must be considered to avoid unstable regions of operation, thus enabling more efficient and realistic control projects.…”

Section: Introductionmentioning

confidence: 99%

“…2. Velocity componentsConsidering Fig.2, one can define the following mathematical speed ratios[10] as { = taṅ =̇tan +̇sec2 (2)Replacing (2) in (1), one obtains…”

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confidence: 99%

SDRE and LQR Controls Comparison Applied in High-Performance Aircraft in a Longitudinal Flight

Santos

Kossoski

Balthazar

et al. 2021

IJRCS

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This paper presents the design of the LQR (Linear Quadratic Regulator) and SDRE (State-Dependent Riccati Equation) controllers for the flight control of the F-8 Crusader aircraft considering the nonlinear model of longitudinal movement of the aircraft. Numerical results and analysis demonstrate that the designed controllers can lead to significant improvements in the aircraft's performance, ensuring stability in a large range of attack angle situations. When applied in flight conditions with an angle of attack above the stall situation and influenced by the gust model, it was demonstrated that the LQR and SDRE controllers were able to smooth the flight response maintaining conditions in balance for an angle of attack up to 56% above stall angle. However, for even more difficult situations, with angles of attack up to 76% above the stall angle, only the SDRE controller proved to be efficient and reliable in recovering the aircraft to its stable flight configuration.

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