Trailing edge flap control methodology for vibration reduction of helicopter with dissimilar blades

Roget, Beatrice; Chopra, Inderjit

doi:10.2514/6.2001-1433

Cited by 7 publications

(18 citation statements)

References 3 publications

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“…This scheme is a re ned version of a previous work by the present authors. 24 In theory, reduction of xed-system vibratory loads can be achieved by using the same control inputs to all blades with the appropriate phase. However, when the rotor is dissimilar, the required trailing-edge ap de ection angles for minimization may become too large.…”

Section: Individual Flap Control Methodologymentioning

confidence: 99%

“…However, when the rotor is dissimilar, the required trailing-edge ap de ection angles for minimization may become too large. 24 Because some degree of rotor dissimilarity is always present, it may be important to control each trailing-edge ap individually.…”

Section: Individual Flap Control Methodologymentioning

confidence: 99%

“…In Ref. 24, three constraints were imposed to guide the choice of the optimal control inputs: 1) All blades should contribute to the same level in the reduction of the k N =rev xed-frame load (k > 1).…”

Section: Individual Flap Control Methodologymentioning

confidence: 99%

“…Because of these dif culties, existing control schemes designed for helicopter vibration reduction are based on xed-frame measurements and assume tracked rotor systems with identical blades, resulting in degraded performance when the algorithm is applied to a rotor with blade-to-blade dissimilarities. 24 The objective of this research is to develop a re ned time-domain control methodology and to demonstrate numerically that complete vibration reduction can be achieved in helicopters with on-blade actuators, by generating individual optimal control inputs to each blade while using exclusively xed-system measurements.…”

Section: Introductionmentioning

confidence: 99%

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Robust Individual Blade Control Algorithm for a Dissimilar Rotor

Roget

Chopra

2002

Journal of Guidance, Control, and Dynamics

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A new control methodology is formulated for vibration reduction at the rotor hub by controlling trailingedge aps. The novelty of the proposed methodology lies in its ability to control each rotor blade separately and optimally, taking into account blade-to-blade dissimilarities, while using exclusively xed-frame measurements. The controller is formulated in the time domain and adaptively generates in real time individual control inputs to the trailing-edge aps to achieve vibration reduction. Numerical simulations using a hingeless rotor model show that the controller generates control inputs to each blade, taking blade dissimilarities into account, and successfully minimizes hub vibrations. NomenclatureC T =¾ = blade loading F = xed-frame load F 0 = uncontrolled xed-frame load I K = identity matrix of size, K k N=rev = integer multiple of N times the rotor frequency N = number of rotor blades N s = number of samples per revolution R = rotor radius S = permutation matrix ® = sectional angle of attack ± = ap de ection angle @®=@± = ap effectiveness ¹ = advance ratio Ä = rotor revolutions per minute Subscripts k = blade number n = iteration number

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Section: Individual Flap Control Methodologymentioning

confidence: 99%

Section: Individual Flap Control Methodologymentioning

confidence: 99%

Section: Individual Flap Control Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Robust Individual Blade Control Algorithm for a Dissimilar Rotor

Roget

Chopra

2002

Journal of Guidance, Control, and Dynamics

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“…1,4,5 Further assumptions were taken to avoid the complications in controller design, the unsteady aerodynamic models were reduced to a quasi-steady model. [6][7][8][9][10] However, these models lack accuracy in predicting the complex features of coupled aeroelastic motion. This have been proven by the experimental correlation studies, which emphasize the necessity of performing a coupled CFD/CSD analysis with complex wake modeling for accurate prediction.…”

Section: Motivation For a Novel Framework For Helicopter Vibrationmentioning

confidence: 99%

Advances in Helicopter Vibration Control Methods Time-Periodic Reduced Order Modeling and H2/H-Infinity Controller Design

Ulker¹,

Nitzsche²

2012

53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

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Ottawa, ON, K1S5B6, CANADA This paper presents the implementation of recent developments in system theory within a novel framework to enhance the vibration control of helicopters. Particular focus is given to the vibration control of helicopters flying in a forward flight regime, where the system exhibits time-periodic behavior. The objective of this framework is to provide high performance controllers that can satisfy stability and design performance criteria when implemented in high-fidelity computer simulations or in real time experiments. The framework emphasizes the integration of state-of-the art coupled Computational Fluid Dynamics (CFD) /Computational Structural Dynamics (CSD) analysis in the controller design process to obtain accurate reduced-order aeroelastic models of the helicopter rotor system. Design of time-periodic H2 and H∞ controllers are proposed owing to their rigorous stability formulation based on Floquet-Lyapunov theory, and advantages over time-lifted controllers. Within this framework, the time-periodic system models in state-space form were identified using robust subspace model identification method. The time-periodic H2 and H∞ synthesis problem was solved using both Linear Matrix Inequality and periodic Riccati based formulations. The controllers performance were validated using the high-fidelity aeroelastic simulations. The computational efficiency of using these advanced methods, and the necessity of using the novel framework were demonstrated by implementing an actively controlled flap strategy for vibration suppression of helicopters. Nomenclature δ Ψ , ∆ Ψ time step of the aeroelastic model and the reduced-order model,respectively δ i trailing edge flap deflection of blade number i, positive downward λ(Ψ k ) characteristic multipliers, eigenvalues of monodromy matrix µ advance ratio Ψ τ monodromy matrix θ 0 , θ 1c , θ 1s collective and cyclic pitch A k , B k , C k , D k state-space matrices of the system at tag time k F L () lower Linear Fractional Transformation F z,i rotating frame vertical load at the root of the blade for blade number i F Z non-rotating frame vertical hub load for the rotor system k sampled tag time index in one period K k controller system model at tag time t K ∞ k and K 2 k H ∞ and H 2 Controller system model at tag time k m k number of inputs at tag time k M X non-rotating frame hub roll moment of the rotor system M y,i rotating frame blade pitch moment of blade number i M Y non-rotating frame hub pitch moment of the rotor system N period of the system in sampled-time

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Demonstration of optimizing piezoelectric polarization in the design of a flextensional actuator
Gibert
¹
,
Austin
²

2006
Struct Multidisc Optim
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0
5
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Trailing edge flap control methodology for vibration reduction of helicopter with dissimilar blades

Cited by 7 publications

References 3 publications

Robust Individual Blade Control Algorithm for a Dissimilar Rotor

Robust Individual Blade Control Algorithm for a Dissimilar Rotor

Advances in Helicopter Vibration Control Methods Time-Periodic Reduced Order Modeling and H2/H-Infinity Controller Design

Demonstration of optimizing piezoelectric polarization in the design of a flextensional actuator

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