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Journal ArticleDOI

Nonlinear dynamics and control of helicopter ground resonance

26 Feb 2021-Journal of Vibration and Control (SAGE PublicationsSage UK: London, England)-pp 107754632199693
TL;DR: In this paper, ground resonance is mitigated by using passive lead-lag dampers that provide sufficence in reducing aero-mechanical instability in helicopters that use soft in-plane rotors.
Abstract: Ground resonance is an aero-mechanical instability in helicopters that use soft in-plane rotors. Traditionally, ground resonance is mitigated by using passive lead–lag dampers that provide sufficie...
Citations
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Proceedings ArticleDOI
05 Dec 2022
TL;DR: In this paper , a study on the use of adaptive leg landing gear to eliminate ground resonance (GR) in helicopters is presented, and the dynamic characteristics of the system are analyzed.
Abstract: Ground resonance (GR) is a potentially destructive mechanical instability involving the coupling of the regressive rotor mode to the fuselage motion. Vibration can be disastrous if measures are not taken in time to mitigate vibrations. This paper presents a study on the use of adaptive landing gear to eliminate GR in helicopters. A GR model considering adaptive landing gear is established, and the dynamic characteristics of the system are analyzed. In this paper, the Linear Quadratic Regulator (LQR) controller is applied to suppress the GR. The setting of the weighting matrix coefficients directly determines the effect of the control system. Therefore, a design method of LQR weighting matrix based on multi-objective genetic algorithm is proposed, which enables the control system to meet multiple performance indicators concurrently. Numerical simulations of GR suppression were performed for the rotor speed range where GR is most likely to occur. The results show that even if the rotor system is not equipped with any dampers, the suppression of helicopter GR can be achieved by using the control strategy proposed in this paper to control the adaptive landing gear. Therefore, the application of adaptive leg landing gear to helicopters can provide some ideas to eliminate GR.
Proceedings ArticleDOI
05 Dec 2022
TL;DR: In this paper , a study on the use of adaptive leg landing gear to eliminate ground resonance (GR) in helicopters is presented, and the dynamic characteristics of the system are analyzed.
Abstract: Ground resonance (GR) is a potentially destructive mechanical instability involving the coupling of the regressive rotor mode to the fuselage motion. Vibration can be disastrous if measures are not taken in time to mitigate vibrations. This paper presents a study on the use of adaptive landing gear to eliminate GR in helicopters. A GR model considering adaptive landing gear is established, and the dynamic characteristics of the system are analyzed. In this paper, the Linear Quadratic Regulator (LQR) controller is applied to suppress the GR. The setting of the weighting matrix coefficients directly determines the effect of the control system. Therefore, a design method of LQR weighting matrix based on multi-objective genetic algorithm is proposed, which enables the control system to meet multiple performance indicators concurrently. Numerical simulations of GR suppression were performed for the rotor speed range where GR is most likely to occur. The results show that even if the rotor system is not equipped with any dampers, the suppression of helicopter GR can be achieved by using the control strategy proposed in this paper to control the adaptive landing gear. Therefore, the application of adaptive leg landing gear to helicopters can provide some ideas to eliminate GR.
Journal ArticleDOI
TL;DR: In this article , a novel weighted variational mode decomposition (VMD)- extreme gradient boosting (xgboost) helicopter fuselage vibration prediction model is proposed, and the vibration response is predicted by xgboost algorithm based on the reconstructed data.
Abstract: Purpose Helicopter fuselage vibration prediction is important to keep a safety and comfortable flight process. The helicopter vibration mechanism model is difficult to meet of demand for accurate vibration prediction. Thus, the purpose of this paper is to develop an intelligent algorithm for accurate helicopter fuselage vibration analysis. Design/methodology/approach In this research, a novel weighted variational mode decomposition (VMD)- extreme gradient boosting (xgboost) helicopter fuselage vibration prediction model is proposed. The vibration data is decomposed and reconstructed by the signal clustering results. The vibration response is predicted by xgboost algorithm based on the reconstructed data. The information transfer order between the controllable flight data and flight attitude are analyzed. Findings The mean absolute percentage error (MAPE), root mean square error (RMSE) and mean absolute error (MAE) of the proposed weighted VMD-xgboost model are decreased by 6.8%, 31.5% and 32.8% compared with xgboost model. The established weighted VMD-xgboost model has the highest prediction accuracy with the lowest mean MAPE, RMSE and MAE of 4.54%, 0.0162, and 0.0131, respectively. The attitude of horizontal tail and cycle pitch are the key factors to vibration. Originality/value A novel weighted VMD-xgboost intelligent prediction methods is proposed. The prediction effect of xgboost model is highly improved by using the signal-weighted reconstruction technique. In addition, the data set used is collected from actual helicopter flight process.
References
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Proceedings ArticleDOI
06 Aug 2002
TL;DR: A concept for the optimization of nonlinear functions using particle swarm methodology is introduced, and the evolution of several paradigms is outlined, and an implementation of one of the paradigm is discussed.
Abstract: A concept for the optimization of nonlinear functions using particle swarm methodology is introduced. The evolution of several paradigms is outlined, and an implementation of one of the paradigms is discussed. Benchmark testing of the paradigm is described, and applications, including nonlinear function optimization and neural network training, are proposed. The relationships between particle swarm optimization and both artificial life and genetic algorithms are described.

35,104 citations

Journal ArticleDOI
TL;DR: In this article, a model for controllable fluid dampers is proposed that can effectively portray the behavior of a typical magnetorheological (MR) damper and compared with experimental results for a prototype damper.
Abstract: Semiactive control devices have received significant attention in recent years because they offer the adaptability of active control devices without requiring the associated large power sources. Magnetorheological (MR) dampers are semiactive control devices that use MR fluids to produce controllable dampers. They potentially offer highly reliable operation and can be viewed as fail-safe in that they become passive dampers should the control hardware malfunction. To develop control algorithms that take full advantage of the unique features of the MR damper, models must be developed that can adequately characterize the damper's intrinsic nonlinear behavior. Following a review of several idealized mechanical models for controllable fluid dampers, a new model is proposed that can effectively portray the behavior of a typical MR damper. Comparison with experimental results for a prototype damper indicates that the model is accurate over a wide range of operating conditions and is adequate for control design an...

1,897 citations

Journal ArticleDOI
TL;DR: In this article, the performance of a number of recently proposed semi-active control algorithms for use with multiple magnetorheological (MR) dampers is evaluated through a numerical example, and the advantages of each algorithm are discussed.
Abstract: This paper presents the results of a study to evaluate the performance of a number of recently proposed semiactive control algorithms for use with multiple magnetorheological (MR) dampers. Various control algorithms used in recent semiactive control studies are considered including the Lyapunov controller, decentralized bang-bang controller, modulated homogeneous friction algorithm, and a clipped optimal controller. Each algorithm is formulated for use with the MR damper. Additionally, each algorithm uses measurements of the absolute acceleration and device displacements for determining the control action to ensure that the algorithms could be implemented on a physical structure. The performance of the algorithms is compared through a numerical example, and the advantages of each algorithm are discussed. The numerical example considers a six-story structure controlled with MR dampers on the lower two floors. In simulation, an El Centro earthquake is used to excite the system, and the reduction in the drif...

633 citations

BookDOI
01 Jan 2013

102 citations

Journal ArticleDOI
TL;DR: In this article, a single-degree-of-freedom (SDOF) isolation system with an MR fluid damper under harmonic excitations is studied and compared with those of the system with a conventional viscous damper.
Abstract: Semi-active control systems are becoming more popular because they offer both the reliability of passive systems and the versatility of active control systems without imposing heavy power demands. In particular, it has been found that magnetorheological (MR) fluids can be designed to be very effective vibration control actuators, which use MR fluids to produce controllable damping force. The objective of this paper is to study a single-degree-of-freedom (SDOF) isolation system with an MR fluid damper under harmonic excitations. A mathematical model of the MR fluid damper with experimental verification is adopted. The motion characteristics of the SDOF system with the MR damper are studied and compared with those of the system with a conventional viscous damper. The energy dissipated and equivalent damping coefficient of the MR damper in terms of input voltage, displacement amplitude and frequency are investigated. The relative displacement with respect to the base excitation is also quantified and compared with that of the conventional viscous damper through updating the equivalent damping coefficient with changing driving frequency. In addition, the transmissibility of the MR damper system with semi-active control is also discussed. The results of this study are valuable for understanding the characteristics of the MR damper to provide effective damping for the purpose of vibration isolation or suppression.

87 citations