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Aldair, Abdulshaheed Abdulhammed. "Neurofuzzy controller based full vehicle nonlinear active suspension systems." Thesis, University of Sussex, 2012. http://sro.sussex.ac.uk/id/eprint/38502/.
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To design a robust controller for active suspension systems is very important for guaranteeing the riding comfort for passengers and road handling quality for a vehicle. In this thesis, the mathematical model of full vehicle nonlinear active suspension systems with hydraulic actuators is derived to take into account all the motions of the vehicle and the nonlinearity behaviours of the active suspension system and hydraulic actuators. Four robust control types are designed and the comparisons among the robustness of those controllers against different disturbance types are investigated to select the best controller among them. The MATLAB SIMULINK toolboxes are used to simulate the proposed controllers with the controlled model and to display the responses of the controlled model under different types of disturbance. The results show that the neurofuzzy controller is more effective and robust than the other controller types. The implementation of the neurofuzzy controller using FPGA boards has been investigated in this work. The Xilinx ISE program is employed to synthesis the VHDL codes that describe the operation of the neurofuzzy controller and to generate the configuration file used to program the FPGA. The ModelSim program is used to simulate the operation of the VHDL codes and to obtain the expected output data of the FPGA boards. To confirm that FPGA the board used as the neurofuzzy controller system operated as expected, a MATLAB script file is used to compare the set of data obtained from the ModelSim program and the set of data obtained from the MATLAB SIMULINK model. The results show that the FPGA board is effective to be used as a neurofuzzy controller for full vehicle nonlinear active suspension systems. The active suspension system has a great performance for vibration isolation. However the main drawback of the active suspension is that it is high energy consumptive. Therefore, to use this suspension system in the proposed model, this drawback should be solved. Electromagnetic actuators are used to convert the vibration energy that arises from the rough road to useful electrical energy to reduce the energy consumption by the active suspension systems. The results show that the electromagnetic devices act as a power generator, i.e. the vibration energy excited by the rough road surface has been converted to a useful electrical energy supply for the actuators. Furthermore, when the nonlinear damper models are replaced by the electromagnetic actuators, riding comfort and the road handling quality are improved. As a result, two targets have been achieved by using hydraulic actuators with electromagnetic suspension systems: increasing fuel economy and improving the vehicle performance.
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Larin, Oleksiy O., Oleksii O. Vodka, Ruslan O. Kaidalov, and Volodymyr M. Bashtovoi. "Stochastic Dynamics of the Specialized Vehicle with Nonlinear Suspension." Thesis, NTU "KhPI", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/23647.
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This work deals with the theoretical modelling of the vertical dynamics of the vehicle which has an additional level of suspension for a cargo platform with the nonlinear stiffness. The paper presents the design scheme of the additional level of cushioning having a quasi-zero stiffness in the equilibrium position. The mathematical model of the dynamic behavior of specialized vehicles is developed as a nonlinear discrete system. The results of numeric calculations of the vehicle dynamic response on the stochastic load is represented based on the developed model. Vertical vibrations of the cargo platform caused by the kinematics random influence applied to the axels of the vehicle are analyzed. The load is applied to the axels of the vehicle with a time delay. The results of the comparative analysis are displayed for the frequencies and amplitudes of the vehicle vertical vibrations within two different suspensions: in the linear and nonlinear statements.
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Olson, Sean Michael. "Nonlinear compensation of a single degree of freedom magnetic suspension system." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12067.
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Marsh, Clive. "A nonlinear control design methodology for computer-controlled vehicle suspension systems." Thesis, Loughborough University, 1992. https://dspace.lboro.ac.uk/2134/27995.
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This study demonstrates a new nonlinear controller design methodology applicable to automotive suspension systems. It enhances the ability of the designer to tackle the complex design problem of a controller for a computer-controlled suspension. Based on the principles of optimal control, it permits the use of more general system models and cost functions than the standard linear optimal design techniques and hence, increases the freedom of the designer. It implements the control with an optimal, nonlinear feedback law and is shown to have the potential to improve vehicle performance.
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Mansour, Kamjou. "Characterizations of optical nonlinearities in carbon black suspension in liquids." Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc332586/.
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A complete study was conducted on optical limiting characterization in samples of carbon black microparticles in a mixture of deionized water and ethylene glyccol using nanosecodn and picosecond later pulses at 532 nm and 1064 nm.
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Viarbitskaya, Sviatlana. "Resonance-enhanced Second Harmonic Generation from spherical microparticles in aqueous suspension." Doctoral thesis, Stockholm University, AlbaNova University Center (together with KTH), 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7517.
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<p>Second harmonic generation (SHG) is a nonlinear optical effect sensitive to interfaces between materials with inversion symmetry. It is used as an effective tool for detection of the adsorption of a substance to microscopic particles, cells, liposomes, emulsions and similar structures, surface analysis and characterization of microparticles. The scattered second harmonic (SH) intensity from surfaces of suspended microparticles is characterized by its complex angular distribution dependence on the shape, size, and physical and chemical properties of the molecules making up the outer layer of the particles. In particular, the overall scattered SH intensity has been predicted to have a dramatic and nontrivial dependence on the particle size.</p><p>Results are reported for aqueous suspensions of polystyrene microspheres with different dye molecules adsorbed on their surfaces. They indicate that the scattered SH power has an oscillatory dependence on the particle size. It is also shown that adsorption of one of the dyes (malachite green) on polystyrene particles is strongly affected when SDS surfactants are added to the solution. For this system a rapid increase of the SH signal with increasing concentration of SDS was observed in the range of low SDS concentration.</p><p>Three different theoretical models are used to analyze the observed particle size dependence of SHG. The calculated angular and particle size dependences of the SH scattered power show that the models do not agree very well between each other when the size of the particles is of the order of the fundamental light wavelength, as here. One of the models - nonlinear Mie scattering - predicts oscillatory behaviour of the scattered SH power with the particle size, but fails to reproduce the position of the maxima and minima of the experimentally observed oscillations.</p><p>The obtained results on the size dependence of the SH can be used in all applications to increase the count rate by choosing particles of the size for which the SH efficiency was found to the highest. A new effect of cooperative malachite green and SDS interaction at the polystyrene surface can be employed, for example, in the areas of microbiology or biotechnology, where adsorption macromolecules, surfactants and dyes to polystyrene microparticles is widely used.</p>
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Kwong, Gordon Houng. "Approximations for Nonlinear Differential Algebraic Equations to Increase Real-time Simulation Efficiency." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/42753.
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Full-motion driving simulators require efficient real-time high fidelity vehicle models in order to provide a more realistic vehicle response. Typically, multi-body models are used to represent the vehicle dynamics, but these have the unfortunate drawback of requiring the solution of a set of coupled differential algebraic equations (DAE). DAE's are not conducive to real-time implementation such as in a driving simulator, without a very expensive processing capability. The primary objective of this thesis is to show that multi-body models constructed from DAE's can be reasonably approximated with linear models using suspension elements that have nonlinear constitutive relationships.
Three models were compared in this research, an experimental quarter-car test rig, a multi-body dynamics differential algebraic equation model, and a linear model with nonlinear suspension elements. Models constructed from differential algebraic equations are computationally expensive to compute and are difficult to realize for real-time simulations. Instead, a linear model with nonlinear elements was proposed for a more computationally efficient solution that would retain the nonlinearities of the suspension. Simplifications were made to the linear model with nonlinear elements to further reduce computation time for real-time simulation.
The development process of each model is fully described in this thesis. Each model was excited with the same input and their outputs were compared. It was found that the linear model with nonlinear elements provides a reasonably good approximation of actual model with the differential algebraic equations.<br>Master of Science
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Brown, R. D. "The effect of the nonlinear rear suspension on the traction of off-road motorcycles." Thesis, Cranfield University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396506.
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Mohan, Anant. "Nonlinear Investigation of the Use of Controllable Primary Suspensions to Improve Hunting in Railway Vehicles." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/33740.
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Hunting is a very common instability exhibited by rail vehicles operating at high speeds. The hunting phenomenon is a self excited lateral oscillation that is produced by the forward speed of the vehicle and the wheel-rail interactive forces that result from the conicity of the wheel-rail contours and the friction-creep characteristics of the wheel-rail contact geometry. Hunting can lead to severe ride discomfort and eventual physical damage to wheels and rails.
A comprehensive study of the lateral stability of a single wheelset, a single truck, and the complete rail vehicle has been performed. This study investigates bifurcation phenomenon and limit cycles in rail vehicle dynamics. Sensitivity of the critical hunting velocity to various primary and secondary stiffness and damping parameters has been examined.
This research assumes the rail vehicle to be moving on a smooth, level, and tangential track, and all parts of the rail vehicle to be rigid. Sources of nonlinearities in the rail vehicle model are the nonlinear wheel-rail profile, the friction-creep characteristics of the wheel-rail contact geometry, and the nonlinear vehicle suspension characteristics. This work takes both single-point and two-point wheel-rail contact conditions into account.
The results of the lateral stability study indicate that the critical velocity of the rail vehicle is most sensitive to the primary longitudinal stiffness. A method has been developed to eliminate hunting behavior in rail vehicles by increasing the critical velocity of hunting beyond the operational speed range. This method involves the semi-active control of the primary longitudinal stiffness using the wheelset yaw displacement. This approach is seen to considerably increase the critical hunting velocity.<br>Master of Science
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Lebel, David. "Statistical inverse problem in nonlinear high-speed train dynamics." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC2189/document.
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Ce travail de thèse traite du développement d'une méthode de télédiagnostique de l'état de santé des suspensions des trains à grande vitesse à partir de mesures de la réponse dynamique du train en circulation par des accéléromètres embarqués. Un train en circulation est un système dynamique dont l'excitation provient des irrégularités de la géométrie de la voie ferrée. Ses éléments de suspension jouent un rôle fondamental de sécurité et de confort. La réponse dynamique du train étant dépendante des caractéristiques mécaniques des éléments de suspension, il est possible d'obtenir en inverse des informations sur l'état de ces éléments à partir de mesures accélérométriques embarquées. Connaître l'état de santé réel des suspensions permettrait d'améliorer la maintenance des trains. D’un point de vue mathématique, la méthode de télédiagnostique proposée consiste à résoudre un problème statistique inverse. Elle s'appuie sur un modèle numérique de dynamique ferroviaire et prend en compte l'incertitude de modèle ainsi que les erreurs de mesures. Les paramètres mécaniques associés aux éléments de suspension sont identifiés par calibration Bayésienne à partir de mesures simultanées des entrées (les irrégularités de la géométrie de la voie) et sorties (la réponse dynamique du train) du système. La calibration Bayésienne classique implique le calcul de la fonction de vraisemblance à partir du modèle stochastique de réponse et des données expérimentales. Le modèle numérique étant numériquement coûteux d'une part, ses entrées et sorties étant fonctionnelles d'autre part, une méthode de calibration Bayésienne originale est proposée. Elle utilise un métamodèle par processus Gaussien de la fonction de vraisemblance. Cette thèse présente comment un métamodèle aléatoire peut être utilisé pour estimer la loi de probabilité des paramètres du modèle. La méthode proposée permet la prise en compte du nouveau type d'incertitude induit par l'utilisation d'un métamodèle. Cette prise en compte est nécessaire pour une estimation correcte de la précision de la calibration. La nouvelle méthode de calibration Bayésienne a été testée sur le cas applicatif ferroviaire, et a produit des résultats concluants. La validation a été faite par expériences numériques. Par ailleurs, l'évolution à long terme des paramètres mécaniques de suspensions a été étudiée à partir de mesures réelles de la réponse dynamique du train<br>The work presented here deals with the development of a health-state monitoring method for high-speed train suspensions using in-service measurements of the train dynamical response by embedded acceleration sensors. A rolling train is a dynamical system excited by the track-geometry irregularities. The suspension elements play a key role for the ride safety and comfort. The train dynamical response being dependent on the suspensions mechanical characteristics, information about the suspensions state can be inferred from acceleration measurements in the train by embedded sensors. This information about the actual suspensions state would allow for providing a more efficient train maintenance. Mathematically, the proposed monitoring solution consists in solving a statistical inverse problem. It is based on a train-dynamics computational model, and takes into account the model uncertainty and the measurement errors. A Bayesian calibration approach is adopted to identify the probability distribution of the mechanical parameters of the suspension elements from joint measurements of the system input (the track-geometry irregularities) and output (the train dynamical response).Classical Bayesian calibration implies the computation of the likelihood function using the stochastic model of the system output and experimental data. To cope with the fact that each run of the computational model is numerically expensive, and because of the functional nature of the system input and output, a novel Bayesian calibration method using a Gaussian-process surrogate model of the likelihood function is proposed. This thesis presents how such a random surrogate model can be used to estimate the probability distribution of the model parameters. The proposed method allows for taking into account the new type of uncertainty induced by the use of a surrogate model, which is necessary to correctly assess the calibration accuracy. The novel Bayesian calibration method has been tested on the railway application and has achieved conclusive results. Numerical experiments were used for validation. The long-term evolution of the suspension mechanical parameters has been studied using actual measurements of the train dynamical response
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Tusset, Ângelo Marcelo. "Controle ótimo aplicado em modelo de suspensão veicular não-linear controlada através de amortecedor magneto-reológico." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/15395.
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Este trabalho apresenta uma proposta para o controle da suspensão veicular utilizando o amortecedor magneto-reológico, sendo o controle proposto composto pela associação de duas estratégias de controle, o controle ótimo e o controle fuzzy. O Controle ótimo é utilizado para determinar a força a ser utilizada pelo amortecedor magneto-reológico, e o controle fuzzy é utilizado para determinar a corrente elétrica, a ser utilizada no amortecedor magento-reológico e é obtido considerando o modelo de Mandani. Para o controle fuzzy, são consideradas duas entradas, a velocidade de deslocamento do pistão do amortecedor e a força prevista pelo controle ótimo, e uma saída, a corrente elétrica [A]. Para demonstrar a eficiência do controle proposto são consideradas simulações computacionais, utilizando um modelo matemático não-linear de um quarto de veículo. A análise do desempenho do controle é realizada, considerando excitações provocadas por irregularidades na pista, as irregularidades são representadas por entradas tipo degrau, impulso e senoidal. As simulações computacionais são realizadas, utilizando o Matlab® e o Simulink. Os resultados das simulações demonstram que o controle proposto aumenta a segurança do veículo e melhora sua dirigibilidade, reduzindo o deslocamento vertical do conjunto eixo e roda e o espaço de trabalho do amortecedor, quando comparado como o sistema passivo. Também contribui com o conforto dos passageiros, reduzindo as oscilações da carroceria, mantendo os níveis de aceleração abaixo dos considerados desconfortáveis pela norma BS 6841, 1987. Para verificar o comportamento do controle proposto, diante de incertezas, são realizadas simulações computacionais, considerando a possibilidade de erros paramétricos. As simulações, considerando os erros paramétricos, demonstram que o controle ótimo, mesmo quando sujeito a incertezas, permanece sendo estável e ótimo.<br>This work presents a proposal for control of vehicular suspension using the magneto-rheological damper, the proposed control is composed by association of two control strategy, the optimal control and the fuzzy control. The optimal control is used to determine the power to be applied by the magneto-rheological damper, and the fuzzy control is used to determine the electric current to be used in the magneto-rheological damper and is obtained considering the Mandani's model. For the fuzzy control two inputs are considered, the velocity of the piston's damper and the force provided by the optimal control, and one output, the electric current [A]. To demonstrate the efficiency of the proposed control, computational simulations are considered using a nonlinear mathematical model for a quarter-car. The performance of the control is analyzed considering excitements provoked by irregularities in the track, the irregularities are represented by entrances step type, pulse and sinusoidal. The computational simulations are performed using the Matlab® and the Simulink. The results of simulations show that the proposed control increases the vehicle security and improves the drive ability by reducing the vertical wheel displacement and the workspace to be used by the damper when compared to the passive system. It also helps with the comfort of passengers, reducing the bodywork oscillations, maintaining levels of accelerating below considered uncomfortable by standard BS 6841, 1987. To verify the behavior of the proposed control, in the face of uncertainty, computational simulations are carried out, considering the possibility of parametric errors. The simulations, show that the Optimal Control, even when subject to uncertainties, remains stable and optimal.
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Murali, madhavan rathai Karthik. "Synthesis and real-time implementation of parameterized NMPC schemes for automotive semi-active suspension systems." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALT052.
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Cette thèse traite de la synthèse et de la mise en œuvre en temps réel (RT) de schémas de contrôle prédictif non linéaire paramétré (pNMPC) pour les systèmes de suspension semi-active des automobiles. Le schéma pNMPC est basé sur une technique d'optimisation par simulation en boîte noire. Le point essentiel de la méthode est de paramétrer finement le profil d'entrée et de simuler le système pour chaque entrée paramétrée et d'obtenir la valeur approximative de l'objectif et de la violation des contraintes pour le problème pNMPC. Avec les résultats obtenus de la simulation, l'entrée admissible (si elle existe) ayant la valeur objective minimale ou, à défaut, la valeur de violation de contrainte la plus faible est sélectionnée et injectée dans le système et ceci est répété indéfiniment à chaque période de décision. La méthode a été validée expérimentalement sur dSPACE MicroAutoBoX II (MABXII) et les résultats montrent de bonnes performances de l'approche proposée. La méthode pNMPC a également été étendue à une méthode pNMPC parallélisée et la méthode proposée a été mise en œuvre pour le contrôle du système de suspension semi-active d'un demi-véhicule. Cette méthode a été mise en œuvre grâce à des unités de traitement graphique (GPU) qui servent de plate-forme modèle pour la mise en œuvre d'algorithmes parallèles par le biais de ses processeurs multi-cœurs. De plus, une version stochastique de la méthode pNMPC parallélisée est proposée sous le nom de schéma pNMPC à Scénario-Stochastique (SS-pNMPC). Cette méthode a été mise en œuvre et testée sur plusieurs cartes NVIDIA embarquées pour valider la faisabilité de la méthode proposée pour le contrôle du système de suspension semi-active d'un demi-véhicule. En général, les schémas pNMPC parallélisés offrent de bonnes performances et se prêtent bien à un large espace de paramétrage en entrée. Enfin, la thèse propose un outil logiciel appelé "pNMPC - A code generation software tool for implementation of derivative free pNMPC scheme for embedded control systems". L'outil logiciel de génération de code (S/W) a été programmé en C/C++ et propose également une interface avec MATLAB/Simulink. Le logiciel de génération de code a été testé pour divers exemples, tant en simulation que sur du matériel embarqué en temps réel (MABXII), et les résultats semblent prometteurs et viables pour la mise en œuvre de la RT pour des applications réelles. L'outil de génération de code S/W comprend également une fonction de génération de code GPU pour une mise en œuvre parallèle. Pour conclure, la thèse a été menée dans le cadre du projet EMPHYSIS et les objectifs du projet s'alignent sur cette thèse et les méthodes pNMPC proposées sont compatibles avec la norme eFMI<br>This thesis discusses the synthesis and real-time (RT) implementation of parameterized Nonlinear Model Predictive Control (pNMPC) schemes for automotive semi-active suspension systems. The pNMPC scheme uses a black-box simulation-based optimization method. The crux of the method is to finitely parameterize the input profile and simulate the system for each parameterized input and obtain the approximate objective and constraint violation value for the pNMPC problem. With the obtained results from the simulation, the input with minimum objective value or the least constraint violation value is selected and injected into the system and this is repeated in a receding horizon fashion. The method was experimentally validated on dSPACE MicroAutoBoX II (MABXII) and the results display good performance of the proposed approach. The pNMPC method was also augmented to parallelized pNMPC and the proposed method was implemented for control of semi-active suspension system for a half car vehicle. This method was implemented by virtue of Graphic Processing Units (GPUs) which serves as a paragon platform for implementation of parallel algorithms through its multi-core processors. Also, a stochastic version of the parallelized pNMPC method is proposed which is termed as Scenario-Stochastic pNMPC (SS-pNMPC) scheme and the method was implemented and tested on several NVIDIA embedded boards to verify and validate the RT feasibility of the proposed method for control of semi-active suspension system for a half car vehicle. In general, the parallelized pNMPC schemes provide good performance and also, fares well for large input parameterization space. Finally, the thesis proposes a software tool termed “pNMPC – A code generation software tool for implementation of derivative free pNMPC scheme for embedded control systems”. The code generation software (S/W) tool was programmed in C/C++ and also, provides interface to MATLAB/Simulink. The S/W tested for variety of examples both in simulation as well as on RT embedded hardware (MABXII) and the results looks promising and viable for RT implementation for real world applications. The code generation S/W tool also includes GPU code generation feature for parallel implementation. To conclude, the thesis was conducted under the purview of the EMPHYSIS project and the goals of the project align with this thesis and the proposed pNMPC methods are amenable with eFMI standard
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Song, Xubin. "Design of Adaptive Vibration Control Systems with Applicaion to Magneto-Rheological Dampers." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/29556.
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The design of nonlinear adaptive control systems for reducing vibration transmission in applications such as transportation systems is discussed. The systems studied include suspension systems, such as those used in vehicles, employing nonlinear magneto-rheological (MR) dampers that are controlled to provide improved vibration isolation. Magneto-rheological dampers use a novel class of smart fluid whose apparent viscosity changes as it is exposed to a magnetic field. The developed adaptive control scheme is designed to deal with the nonlinearities and uncertainties that commonly arise in most suspension applications. Some of the nonlinearities that are considered include time-varying characteristics, displacement-dependent effects, and hysterisis damping of magneto-rheological dampers. The uncertainties include mass and stiffness variations that can commonly occur in a suspension system. A number of nonlinear analytical models are developed and used in numerical simulation to evaluate the validity and effectiveness of the developed adaptive controllers. Further, the results of the numerical study are used in an experimental evaluation of the controllers on a seat suspension for heavy vehicles. The analytical and experimental evaluation both indicate the effectiveness of the proposed adaptive control technique in controlling vibration transmission in the presence of both system nonlinearities and uncertainties. The manuscript will provide a detail account of the modeling, dynamic analysis, adaptive control development, and testing that was performed throughout this study.<br>Ph. D.
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Thylén, Christian. "Förenklad numerisk analys av hängbroars verkningssätt : Utveckling av programmet SusB med tillämpning av CalFEM toolbox." Thesis, KTH, Bro- och stålbyggnad, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-36952.
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Oliveira, Fernando Emerenciano Nunes de. "Controles semiativos e observador de estados não linear aplicados em suspensão veicular com amortecedor magneto-reológico." Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2904.
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Comprovadamente, o sistema de suspensão veicular passivo é uma proposta confiável e econômica de solução tanto para redução dos níveis de vibração do chassi e da roda, quanto para a redução dos níveis de aceleração do chassi. Embora este sistema seja amplamente empregado nos veículos, ele apresenta a desvantagem que seus parâmetros não podem ser modificados de acordo com as variações geradas pela pista. Com isso surge o emprego da utilização do sistema de suspensão ativa, que possibilita a variação dos parâmetros da suspensão a tempo real, no entanto, o emprego deste tipo de suspensão requer um elevado nível de energia para o funcionamento correto de seus atuadores, acarretando na inviabilidade de algumas aplicações. Para solucionar as desvantagens encontradas para o sistema de suspensão passivo e ativo, surge o sistema de suspensão semiativo, que reúne as vantagens do sistema ativo, porém com um menor consumo de energia, gerando consequentemente uma opção de controle confiável e econômica de solução para os problemas de dirigibilidade e conforto veicular. O presente trabalho pretende realizar duas avaliações, sendo a primeira, a avaliação e comparação de um sistema de suspensão passivo com o desempenho de quatro controladores semiativos (on/off, skyhook, groundhook e híbrido) e a segunda é testar os mesmos controladores, porém considerando a dinâmica de um amortecedor magnético-reológico através do modelo de LuGre. Estes controladores serão aplicados a um modelo não linear de um quarto de carro com dois graus de liberdade, sendo as suas variáveis estimadas, através de um observador de estados não linear. A análise para a comparação dos sistemas será realizada através de simulações numéricas utilizando o software MatLab®. As simulações dos distúrbios gerados pela pista serão realizadas através de uma função degrau e uma função pulso com o objetivo de avaliar o desempenho de cada controlador. Após a implementação dos algoritmos de controle, foi possível verificar que o sistema de suspensão semiativo, frente às excitações propostas, apresentou um desempenho superior em relação ao conforto. Contudo, não tão significativas quanto ao do conforto, o sistema controlável também, comparativamente ao sistema passivo, apresentou melhoras no requisito dirigibilidade.<br>Proven, the passive vehicle suspension system is a reliable and cost-effective solution solution for both chassis and wheel vibration levels reduction and chassis acceleration levels reduction. Although this system is widely used in vehicles, it has the disadvantage that its parameters can not be modified according to the variations generated by the track. This results in the use of the active suspension system, which allows the variation of the parameters of the suspension in real time, however, the use of this type of suspension requires a high level of energy for the correct operation of its actuators, resulting in the unfeasibility of some applications. To solve the disadvantages found for the passive and active suspension system, the semiactive suspension system arises, which combines the advantages of the active system, but with a lower energy consumption, consequently generating a reliable and economical solution control option to the problems of maneuverability and vehicular comfort. The present work intends to perform two evaluations, the first being the evaluation and comparison of a passive suspension system with the performance of four semi-active controllers (on/off, skyhook, groundhook and hybrid) and the second is to test the same controllers, but considering the dynamics of a magneticrheological damper through the LuGre model. These controllers will be applied to a nonlinear model of a quarter-car with two degrees of freedom, with its variables being estimated through a nonlinear state observer. The analysis for the comparison of the systems will be performed through numerical simulations using MatLab® software. The simulations of the disturbances generated by the track will be performed through a step function and a pulse function in order to evaluate the performance of each controller. After the implementation of the control algorithms, it was possible to verify that the system of semi-active suspension against the proposed excitations presented a superior performance in relation to comfort. However, not as significant as comfort, the controllable system alo compared to the passive system, presented improvements in the steerability requirement.
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El-Ganainy, Ramy. "Optical Nonlinear Interactions In Dielectric Nano-Suspensions." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4122.
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This work is divided into two main parts. In the first part (chapters 2-7) we consider the nonlinear response of nano-particle colloidal systems. Starting from the Nernst-Planck and Smoluchowski equations, we demonstrate that in these arrangements the underlying nonlinearities as well as the nonlinear Rayleigh losses depend exponentially on optical intensity. Two different nonlinear regimes are identified depending on the refractive index contrast of the nanoparticles involved and the interesting prospect of self-induced transparency is demonstrated. Soliton stability is systematically analyzed for both 1D and 2D configurations and their propagation dynamics in the presence of Rayleigh losses is examined. We also investigate the modulation instability of plane waves and the transverse instabilities of soliton stripe beams propagating in nonlinear nano-suspensions. We show that in these systems, the process of modulational instability depends on the boundary conditions. On the other hand, the transverse instability of soliton stripes can exhibit new features as a result of 1D collapse caused by the exponential nonlinearity. Many-body effects on the systems' nonlinear response are also examined. Mayer cluster expansions are used in order to investigate particle-particle interactions. We show that the optical nonlinearity of these nano-suspensions can range anywhere from exponential to polynomial depending on the initial concentration and the chemistry of the electrolyte solution. The consequence of these inter-particle interactions on the soliton dynamics and their stability properties are also studied. The second part deals with linear and nonlinear properties of optical nano-wires and the coupled mode formalism of parity-time (PT) symmetric waveguides. Dispersion properties of AlGaAs nano-wires are studied and it is shown that the group velocity dispersion in such waveguides can be negative, thus enabling temporal solitons. We have also studied power flow in nano-waveguides and we have shown that under certain conditions, optical pulses propagating in such structures will exhibit power circulations. Finally PT symmetric waveguides were investigated and a suitable coupled mode theory to describe these systems was developed.<br>Ph.D.<br>Optics and Photonics<br>Optics and Photonics<br>Optics PhD
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Maillou, Balbine. "Caractérisation et identification non-paramétrique des non-linéarités de suspensions de haut-parleurs." Thesis, Le Mans, 2015. http://www.theses.fr/2015LEMA1028.
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Ce travail de thèse porte sur le comportement mécanique en basses fréquences de l'équipage mobile du haut-parleur électrodynamique, et plus spécifiquement de ses suspensions. Les propriétés des suspensions sont difficiles à identifier du fait de l'assemblage géométrique mis en oeuvre et du fait des matériaux employés, à l'origine de comportements viscoélastiques non-linéaires. En régime linéaire, le modèle de Thiele et Small permet une bonne description du comportement du haut-parleur, l'équipage mobile étant modélisé par un système masse-ressort-amortissement linéaire. En régime non-linéaire, ce modèle n'est plus suffisant et la démarche adoptée est celle de l'identification de systèmes non-linéaires, outil d'aide à la modélisation analytique. Un modèle sans a priori physique est choisi : le modèle « Hammerstein Généralisé ». Son identification requiert l'acquisition de signaux expérimentaux. Un banc de mesure a donc été élaboré et permet de caractériser l'équipage mobile découplé du moteur magnétique, lorsqu'il est soumis à un déplacement axial de grande amplitude et imposé par un pot vibrant. Le pot vibrant étant lui-même non-linéaire, une nouvelle méthode d'identification du modèle « Hammerstein Généralisé » a été développée, adaptée à la configuration de systèmes non-linéaires en série. Enfin, les paramètres d'un modèle dit de «Thiele et Small étendu» sont déduits à partir des paramètres du modèle «Hammerstein Généralisé» et permettent de mettre en évidence l'évolution de la raideur et de l'amortissement avec la fréquence d'excitation et le déplacement de la membrane, ainsi que la dépendance des phénomènes observés avec le niveau d'excitation<br>This thesis deals with the low frequencies mechanical behavior of the electrodynamic loudspeaker moving part, and especially with the suspensions, whose properties are among the most difficult to identify because of both assembly geometry and intrinsic materials, leading to nonlinear viscoelastic behaviors. In small signal domain, the Thiele and Small model describes the behavior of the whole loudspeaker with a good fit, the moving part behavior being modeled by a simple linear mass-spring system, with mass, damping and stiffness parameters. In large-signal domain, this model is no longer sufficient. Our approach is then to perform nonlinear system identification as a tool helping to improve analytical models. A model without physical knowledge is chosen : « Generalized Hammerstein ». Its identification requires the acquisition of experimental signals. A multi sensor experimental set up were so carried out and allows to characterize the whole moving part of a loudspeaker, without magnetic motor, attached to a rigid stand and excited with high axial displacement values, by means of a shaker. Shaker being itself a nonlinear device, a new method of « Generalized Hammerstein » model identification was developped, dedicated to nonlinear systems in series. Finally, parameters of an «expanded Thiele and Small» model are derived from the «Generalized Hammerstein» model parameters. This allows to highlight the evolution of the stiffness and damping with the frequency of excitation, with the displacement of the membrane, as well as the dependence of observed phenomena with the excitation level
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Zargar, Bahram. "Model development, validation and nonlinear control of pneumatic suspensions." Thesis, University of Ottawa (Canada), 2007. http://hdl.handle.net/10393/27499.
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Pneumatic suspensions are widely used at present in the truck industry. The passive controllability of the parameters of these suspensions makes them suitable for load adapted suspensions. However, active control of these systems is challenging because of their parameter uncertainties and their highly nonlinear behavior. The ultimate goal of this research is to develop an active pneumatic suspension system to improve the ride comfort and performance of car suspensions. For this purpose, dimensional analysis was applied to the half car model of the Honda Civic. The conventional suspension of the Honda Civic was replaced by a pneumatic suspension. Its scaled half car model was designed and built. The parameters of the air spring were identified by carrying out a series of static experiments and frequency analysis on the physical air spring/load system. The mathematical model was validated by experimental results. Different nonlinear controllers were applied to the mathematical model of a quarter car Honda Civic equipped with an active pneumatic suspension. The first order sliding mode feedback linearization controller (SMFLC) with parameter estimator offers the best ride comfort and performance. The performance of this controller is further studied on the half car model in the presence of different model uncertainties.
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Harrer, Christian Josef [Verfasser]. "Active and Nonlinear Microrheology of Dense Colloidal Suspensions / Christian Josef Harrer." Konstanz : Bibliothek der Universität Konstanz, 2013. http://d-nb.info/1041224648/34.
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Bongono, Juilien. "Caracterisation des suspensions par des methodes optiques. modelisation par reseaux de neurones." Thesis, Saint-Etienne, EMSE, 2010. http://www.theses.fr/2010EMSE0577/document.
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La sédimentation des suspensions aqueuses de particules minérales microniques, polydisperses et concentrées a été analysée à l’aide du Turbiscan MA 2000 fondé sur la diffusion multiple de la lumière, en vue d’établir la procédure qui permet de déceler la présence d’une morphologie fractale, puis de déduire les règles de comportements des suspensions fractales par la modélisation avec les réseaux de neurones. Le domaine des interactions interparticulaires physicochimiques (0 à 10% volumique en solide) a été privilégié.La méthodologie de détermination de la structure multifractale des agglomérats et de la suspension a été proposée. La modification structurale des agglomérats qui est à l’origine de comportements non linéaires des suspensions et qui dépend des propriétés cohésives des particules primaires, est interprétée par la variation de la mobilité électrophorétique des particules en suspension. Une approche d’estimation de ces modifications structurales par les réseaux de neurones, à travers la dimension fractale, a été présentée. Les limites du modèle à assimiler ces comportements particuliers ont été expliquées comme résultant du faible nombre d’exemples et de la grande variabilité des mesures aux faibles fractions volumiques en solide<br>The sedimentation of aqueous suspensions of micron-sized mineral particles, polydisperses and concentrated, was analyzed using the Turbiscan MA 2000 based on the multiple light scattering in order to establish the procedure to detect the presence of a fractal morphology, and then to deduce the set of laws of fractal behavior of suspensions by modeling with neural networks. The methodology for determining the multifractal structure of agglomerates and the suspension was proposed. The structural modifications of the agglomerates at the origin of the nonlinear behavior of suspensions and which depends on cohesive properties of primary particles, is interpreted by the change of the electrophoretic mobility of suspended particles. The estimation by neural networks of these structural changes, through the fractal dimension has been presented. The limits of the model to learn these specific behaviors have been explained as resulting from the low number of examples and the great variability in the measurements at low volume fractions of solid
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Knotek, Jan. "Lávka pro pěší podporovaná kabely." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392119.
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The subject of this diploma thesis is design a cable-supported pedestrian bridge. Three different variants of the solution were created for the design. For detailed processing, variant no.2 was chosen - a suspended bridge with a pylon in the middle of the span. The main task is the static design of the supporting structure. The model for the lengthways is created in ANSYS. The SCIA engineer was used to solve crosswise. The assessment and dimensioning was done according to the limit state principles and valid standards.
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Svahn, Fredrik. "Low-cost control of discontinuous systems including impacts and friction." Licentiate thesis, Stockholm : Farkost och flyg, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4581.
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Swatzel, James Paul. "A partial differential equation to model the Tacoma Narrows Bridge failure." CSUSB ScholarWorks, 2004. https://scholarworks.lib.csusb.edu/etd-project/2631.
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The purpose of this thesis was to examine a partial differential equation to model the Tacoma Narrows bridge failure. This thesis will examine the equation developed by Lazer and McKenna to model a suspension bridge in no wind.
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Tomisová, Gabriela. "Předpjatý pás přes hluboké údolí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265226.
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The topic of this thesis is a design of stress ribbon bridge across the deep valley. The construction of the footbridge contains stress ribbon bridge with external cables and final prestressing tendons. The bridge deck is in a parabolic arc and the suspension cables are in two bend down parabolic arcs. The construction is reproduced for evaluation of longitudinal direction in the Ansys 14.0 programme and for transversal direction in the Scia Engineer 15.1 programme. The model was solved in several phases, nonlinerally. The pier was reproduced in the Scia Engineer 15.1 programme for local effect of action. The construction was evaluated for dynamic action. The construction is assessed according to the actual EN standards.
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Fernandes, Julio Cesar de Moraes [UNESP]. "Influência das não linearidades geométricas em sistemas de suspensão com amortecimento assimétrico sob excitação harmônica." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/132496.
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000852137.pdf: 2643913 bytes, checksum: 095f34948be7c9f12b30f5dac4abbc41 (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>O objetivo deste trabalho é estudar o comportamento dinâmico de sistemas de suspensão veicular que empregam amortecimento viscoso assimétrico, com foco na melhoria do conforto para os passageiros, considerando não linearidade geométricas presentes no sistema. Estudos anteriores comprovam que o uso de amortecedores assimétricos nestes tipos de sistema pode ser vantajoso com relação ao conforto dos passageiros. Porém, nota-se que há uma deficiência no entendimento do comportamento dinâmico deste tipo de sistema. Portanto, análises mais aprofundadas deste problema devem ser realizadas. A modelagem e o comportamento de duas configurações de suspensões, uma com amortecimento viscoso simétrico e outra com amortecimento viscoso assimétrico são apresentados e comparados. As simulações são feitas usando um modelo de quarto de carro para analisar a dinâmica vertical. A configuração geométrica de um sistema de suspensão é levada em consideração na modelagem da força de amortecimento e da força da mola, de forma a incluir não linearidade geométricas no modelo. O perfil de pavimento é introduzido no sistema através de uma excitação harmônica. Diversos valores de frequência de excitação são utilizados para descrever as diferentes irregularidades de diferentes tipos de pavimento. Os modelos matemáticos referentes aos sistemas de suspensão descritos são analisados através de simulação numérica. Através da análise computacional e métodos usuais em dinâmica não linear, incluindo históricos de deslocamento, plano de fase e resposta em frequencia é possível identificar regiões nas quais fenômenos indesejados ocorrem. Para esta análise, foram variados os valores do coeficiente de amortecimento tanto para a compressão quanto para a extensão do amortecedor e estabelecida uma razão de assimetria. Através da modelagem e simulações computacionais deste estudo é possível verificar que a escolha da...<br>The objective of this work is to study the dynamical behaviour of vehicle supension system employing asynmetrical viscous damping, with a focus on improving passenger comfort, considering geometric nonlinearities which are present in the system. Previous studies have shown that the use of asymmetrical dampers in these types of systems can be advantageous with regard to the comfort of the passengers. However, there is a deficiency in understanding the dynamic behaviour of such systems. Therefore, further analysis of this problem should be conducted. The modeling and the behaviour of suspensions of two configurations, one with symmetrical viscous damping and another with asymmetrical viscous damping are presented and compared. The simulations are performed using a quarter-car model to analyze the vertical dynamics. The geometric configuration of a suspension system is taken into account in modeling the damping force and spring force, to include geometrical nonlinearities in the model. The road profile is introduced into the system through a harmonic excitation. Several values of excitation frequency are used to describe the various irregularities of different types of road. Mathematical models of the described suspension systems are analyzed by numerical simulation. Through computational analysis and usual methods in nonlinear dynamics, including time history, phase plane and frequency response, it is possible to identify regions where unwanted phenomena occur. For this analysis, the values of the damping coefficient for the compression and extension of the damper were varied, establishing an asymmetry ratio. Through modeling and computer simulations in this study, the choice of the asymmetry ratio diminishes the effects that the unever road causes on the displacement and acceleration of the sprung mass. This decrease can also improve the comfort for the passengers
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Fernandes, Julio Cesar de Moraes. "Influência das não linearidades geométricas em sistemas de suspensão com amortecimento assimétrico sob excitação harmônica /." Bauru, 2015. http://hdl.handle.net/11449/132496.
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Orientador: Marcos Silveira<br>Banca: Paulo José Paupitz Gonçalves<br>Banca: Samuel da Silva<br>Resumo: O objetivo deste trabalho é estudar o comportamento dinâmico de sistemas de suspensão veicular que empregam amortecimento viscoso assimétrico, com foco na melhoria do conforto para os passageiros, considerando não linearidade geométricas presentes no sistema. Estudos anteriores comprovam que o uso de amortecedores assimétricos nestes tipos de sistema pode ser vantajoso com relação ao conforto dos passageiros. Porém, nota-se que há uma deficiência no entendimento do comportamento dinâmico deste tipo de sistema. Portanto, análises mais aprofundadas deste problema devem ser realizadas. A modelagem e o comportamento de duas configurações de suspensões, uma com amortecimento viscoso simétrico e outra com amortecimento viscoso assimétrico são apresentados e comparados. As simulações são feitas usando um modelo de quarto de carro para analisar a dinâmica vertical. A configuração geométrica de um sistema de suspensão é levada em consideração na modelagem da força de amortecimento e da força da mola, de forma a incluir não linearidade geométricas no modelo. O perfil de pavimento é introduzido no sistema através de uma excitação harmônica. Diversos valores de frequência de excitação são utilizados para descrever as diferentes irregularidades de diferentes tipos de pavimento. Os modelos matemáticos referentes aos sistemas de suspensão descritos são analisados através de simulação numérica. Através da análise computacional e métodos usuais em dinâmica não linear, incluindo históricos de deslocamento, plano de fase e resposta em frequencia é possível identificar regiões nas quais fenômenos indesejados ocorrem. Para esta análise, foram variados os valores do coeficiente de amortecimento tanto para a compressão quanto para a extensão do amortecedor e estabelecida uma razão de assimetria. Através da modelagem e simulações computacionais deste estudo é possível verificar que a escolha da...<br>Abstract: The objective of this work is to study the dynamical behaviour of vehicle supension system employing asynmetrical viscous damping, with a focus on improving passenger comfort, considering geometric nonlinearities which are present in the system. Previous studies have shown that the use of asymmetrical dampers in these types of systems can be advantageous with regard to the comfort of the passengers. However, there is a deficiency in understanding the dynamic behaviour of such systems. Therefore, further analysis of this problem should be conducted. The modeling and the behaviour of suspensions of two configurations, one with symmetrical viscous damping and another with asymmetrical viscous damping are presented and compared. The simulations are performed using a quarter-car model to analyze the vertical dynamics. The geometric configuration of a suspension system is taken into account in modeling the damping force and spring force, to include geometrical nonlinearities in the model. The road profile is introduced into the system through a harmonic excitation. Several values of excitation frequency are used to describe the various irregularities of different types of road. Mathematical models of the described suspension systems are analyzed by numerical simulation. Through computational analysis and usual methods in nonlinear dynamics, including time history, phase plane and frequency response, it is possible to identify regions where unwanted phenomena occur. For this analysis, the values of the damping coefficient for the compression and extension of the damper were varied, establishing an asymmetry ratio. Through modeling and computer simulations in this study, the choice of the asymmetry ratio diminishes the effects that the unever road causes on the displacement and acceleration of the sprung mass. This decrease can also improve the comfort for the passengers<br>Mestre
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Pelikán, Adam. "Střecha plaveckého stadionu." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226932.
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This diploma thesis is about designing the structure of roof of swimming stadium. Three solutions are created - concrete arc with tie, steel truss slab and concrete pretensioned membrane. One choosed solution - concrete pretensioned membrane - is afterwards developed. In the beginning there are several designs of geometry fulfilling the requirements for given type of structure being created. In part of static calculation, the parametrical mathematical model in form of macro in APDL language for Ansys software has been created. Afterwards all the parameters (initial state of cables, level of pretension, dimensions of membrane and peripheral frame, etc.) has been optimized in order to the membrane be fulfilling criterias for ultimate limit state and serviceability limit state. Afterwards other selected parts of structure has been checked. On basis of designed geometry and design checks in static calculation the drawings of conctruction and designed parts has been created. In the end, the 3D model of the structure has been created in graphical software Rhinoceros. Then visualizations of structure in concstruction stages and after completion has been rendered.
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Mazotti, Adriano César [UNESP]. "Comportamento dinâmico de suspensão eletromecânica: análise da resposta devido ao amortecimento e à rigidez não linear." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/115918.
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000800685.pdf: 1492848 bytes, checksum: 66d029b83fe3516cc9b217657df61d80 (MD5)<br>Este trabalho explora os diferentes tipos de comportamento dinâmicos, encontrados em sistemas eletromecânicos linear e não-linear análogos, sendo o sistema eletromecânico não-linear constituído de rigidez tipo Duffing. A modelagem matemática dos sistemas físicos hipotéticos é realizada através de técnicas Langrangeanas, inclusive para a modelagem que aborda componentes eletromagnéticos de um circuito RLC. O transdutor utilizado no acoplamento dos subsistemas é o de bobina móvel e magnetismo permanente e tem suas equações conhecidas na literatura. Os modelos são baseados em absorvedores utilizados no automobilismo, no entanto são abordados de forma simplificada, comparando-se com o modelo completo de uma suspensão de automóvel. No trabalho é investigada a influência dos parâmetros do circuito RLC, que podem ser responsáveis pelo aumento do amortecimento mecânico. É feita a correlação do amortecimento mecânico com os parâmetros de resistência e capacitância elétrica para o modelo linear. É realizada também a análise dos autovalores do modelo linear e lugar natural das raízes. Para o modelo não-linear é realizada a análise do comportamento dinâmico, levando-se em consideração a variação da capacitância para quatro valores de frequência da força externa ao sistema. Essa análise mostra a diversidade de comportamento dinâmicos encontrados para esse modelo. As variedades de comportamento dinâmicos resultantes do modelo não-linear variam entre dinâmicas caóticas, periódicas, quasi-periódicas e multiperiódica. Indica a possibilidade de utilização do parâmetro da capacitância como parâmetro de controle do sistema e mostra que a resistência elétrica dissipa a energia oirunda do domínio mecânico, fato esse que abre a discussão para as possibilidades de geração de energia<br>This work investigates the different types of dynamic behaviour, found in linear and nonlinear electromechanical system, which are analogue, being the nonlinear electromechanical system constituted of rigidity type Duffing. The mathematical modelling of the hypothetical physical system is realized with Langrangian techniques, including for the modeling of the system is a moving coil and permanent magnet tranducer, which it have their equations deducted in other studies. The models are based in absorbers utilized in automobiles, however in this investigation it is discussed in a simplified way, if it is compared with a complete model of and automobile supension. This work investigates the influence of the RLC circuit parameters, which it may be responsible by the increasing of the mechanical damping. It is realized the correlation of the mechanical damping with resistance and capacitance, for the linear model. It is realized the anlysis of the eigenvalues it is found de root locus of the linear model. For the nonlinear model it is realized the analysis of the dynamic behaviour, considering the variation of the capacitance, for each one of the four values of frequency of the external force. This analysis shows the diversity of dynamic behaviours found for the nonlinear model. The variations of dynamic behaviours resulted of the nonlinear model varies around some types of dynamics, which can be, chaotic, periodic, quasi periodic, quasi periodic and multi periodic. That's indicate the possibility of utilization of the capacitance as control parameter of the system and shows the dissipation of energy by the resistance, this energy is from the mechanical domain, this fact open the discussion for the energy generation possibilities
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Mazotti, Adriano César. "Comportamento dinâmico de suspensão eletromecânica : análise da resposta devido ao amortecimento e à rigidez não linear /." Bauru, 2014. http://hdl.handle.net/11449/115918.
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Orientador: Bento Rodrigues de Pontes Junior<br>Co-orientador: Marcos Silveira<br>Banca: Marcio Antonio Bazani<br>Banca: Paulo José Paupitz Gonçalves<br>Resumo: Este trabalho explora os diferentes tipos de comportamento dinâmicos, encontrados em sistemas eletromecânicos linear e não-linear análogos, sendo o sistema eletromecânico não-linear constituído de rigidez tipo Duffing. A modelagem matemática dos sistemas físicos hipotéticos é realizada através de técnicas Langrangeanas, inclusive para a modelagem que aborda componentes eletromagnéticos de um circuito RLC. O transdutor utilizado no acoplamento dos subsistemas é o de bobina móvel e magnetismo permanente e tem suas equações conhecidas na literatura. Os modelos são baseados em absorvedores utilizados no automobilismo, no entanto são abordados de forma simplificada, comparando-se com o modelo completo de uma suspensão de automóvel. No trabalho é investigada a influência dos parâmetros do circuito RLC, que podem ser responsáveis pelo aumento do amortecimento mecânico. É feita a correlação do amortecimento mecânico com os parâmetros de resistência e capacitância elétrica para o modelo linear. É realizada também a análise dos autovalores do modelo linear e lugar natural das raízes. Para o modelo não-linear é realizada a análise do comportamento dinâmico, levando-se em consideração a variação da capacitância para quatro valores de frequência da força externa ao sistema. Essa análise mostra a diversidade de comportamento dinâmicos encontrados para esse modelo. As variedades de comportamento dinâmicos resultantes do modelo não-linear variam entre dinâmicas caóticas, periódicas, quasi-periódicas e multiperiódica. Indica a possibilidade de utilização do parâmetro da capacitância como parâmetro de controle do sistema e mostra que a resistência elétrica dissipa a energia oirunda do domínio mecânico, fato esse que abre a discussão para as possibilidades de geração de energia<br>Abstract: This work investigates the different types of dynamic behaviour, found in linear and nonlinear electromechanical system, which are analogue, being the nonlinear electromechanical system constituted of rigidity type Duffing. The mathematical modelling of the hypothetical physical system is realized with Langrangian techniques, including for the modeling of the system is a moving coil and permanent magnet tranducer, which it have their equations deducted in other studies. The models are based in absorbers utilized in automobiles, however in this investigation it is discussed in a simplified way, if it is compared with a complete model of and automobile supension. This work investigates the influence of the RLC circuit parameters, which it may be responsible by the increasing of the mechanical damping. It is realized the correlation of the mechanical damping with resistance and capacitance, for the linear model. It is realized the anlysis of the eigenvalues it is found de root locus of the linear model. For the nonlinear model it is realized the analysis of the dynamic behaviour, considering the variation of the capacitance, for each one of the four values of frequency of the external force. This analysis shows the diversity of dynamic behaviours found for the nonlinear model. The variations of dynamic behaviours resulted of the nonlinear model varies around some types of dynamics, which can be, chaotic, periodic, quasi periodic, quasi periodic and multi periodic. That's indicate the possibility of utilization of the capacitance as control parameter of the system and shows the dissipation of energy by the resistance, this energy is from the mechanical domain, this fact open the discussion for the energy generation possibilities<br>Mestre
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Madeira, Fabiano Gomes [UNESP]. "Análise dinâmica de mecanismo articulado de suspensão com não-linearidade na rigidez devido à geometria e à excitação por desbalanceamento rotativo na condição não ideal." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/115917.
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000800632.pdf: 2649005 bytes, checksum: 0e6f6ee2cc449b2d9d89392080c49c79 (MD5)<br>Essa dissertação trata da dinâmica de um sistema com não-linearidade na rigidez devido à geometria do mecanismo articulado de duas barras, identificado como NLGS ao longo do texto. Na Introdução do trabalho são mostrados exemplos de sistema com rigidez não-linear devido á geometria, destacando a aplicação desse tipo de sistema como isolador de vibração e também discute-se sobre a exposição humana à vibração como motivação e justificativa para o trabalho, ressaltando-se as frequências de ressonância das diversas partes do corpo humano. Na sequência faz-se a revisão bibliográfica sobre o assunto de vibrações para auxiliar na compreensão do trabalho. Após esses capítulos introdutórios é feita a apresentação e a modelagem matemática dos sistemas dinâmicos estudados: sistema NLGS ideal, sistema com rigidez não-linear e sistema não ideal. As equações de movimento são deduzidas pelo método de Lagrange. Após a dedução das equações de movimento faz-se a integração numérica utilizando o método de Runge-Kutta de quarta e quinta ordem e obtém-se a resposta dos sistemas (deslocamento, velocidade e aceleração). Como resultado da integração numérica são construídas algumas curvas, tais como: histórico de deslocamento, histórico de frequência, plano de fase, FFT, resposta em frequência e diagrama de bifurcação para ajudar na compreensão do comportamento dinâmico dos sistemas. Com base nos resultados obtidos percebe-se que os sistemas NLGS não ideal, NLGS ideal e com rigidez não linear apresentam um comportamento complexo devido à rigidez não-linear. Nesses três sistemas tem-se indicação de regime de movimento caótico inclusive. No sistema não ideal observa-se o efeito Sommerfeld, o qual deixa evidente a captura da rotação do motor pela frequência natural do sistema e o salto na curva da amplitude de deslocamento em função da frequência do motor. Fazendo um comparativo entre o...<br>This dissertation concerns with the dynamics of a system with nonlinearity in the stiffness due to geometry of a pivot mechanism of two bars, called NLGS in the text. In the Introduction are shown examples of system with nonlinear stiffness due to geometry, emphasizing the application of this kind of system as vibration isolator and is also discussed about the human exposure to vibration as motivation and justification in the research, emphaizing the different resonance frequencies of the human body. In the sequence is carried out the literature review about vibrations to help on understanding the research. After these introductory chapters is done the presentation and mathematical modeling of the studied dynamic systems: non-ideal NLGS system, ideal NLGS system, nonlinear stiffness system and non-ideal system. The equations of motion are deduced by Langrange's method. After the deduction of the equations of motion is carried out the numerical integration using the fourth and fifth order Runger-Kutta's method and it is gotten the response of the systems (displacement, velocity and acceleration). As result of the numerical integration some curves are plotted, such as: displacement history, frequency history, phase portrait, FFT, frequency response and bifurcation diagram to help on understanding the dynamic behavior of the systems. Based on the results is noticed that the following systems have a complex behavior due to nonlinear stiffness: non-ideal NLGS, ideal NLGS and nonlinear stiffness system. In these three systems there are indications of chaotic motion. In the non-ideal system the Sommerfeld effect is observed, evidencing the capture of the frequency of motor by the natural frequency of the system and the jump in the curve of frequency response. Comparing the non-ideal NLGS system and the non-ideal system conludes that the Sommerfeld effect is eliminated and the maximum amplitude of displacement is reduced by 27% in the non-ideal...
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Madeira, Fabiano Gomes. "Análise dinâmica de mecanismo articulado de suspensão com não-linearidade na rigidez devido à geometria e à excitação por desbalanceamento rotativo na condição não ideal /." Bauru, 2014. http://hdl.handle.net/11449/115917.
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Orientador: Bento Rodrigues de Pontes Junior<br>Banca: Marcio Antonio Bazani<br>Banca: Marcos Silveira<br>Resumo: Essa dissertação trata da dinâmica de um sistema com não-linearidade na rigidez devido à geometria do mecanismo articulado de duas barras, identificado como NLGS ao longo do texto. Na Introdução do trabalho são mostrados exemplos de sistema com rigidez não-linear devido á geometria, destacando a aplicação desse tipo de sistema como isolador de vibração e também discute-se sobre a exposição humana à vibração como motivação e justificativa para o trabalho, ressaltando-se as frequências de ressonância das diversas partes do corpo humano. Na sequência faz-se a revisão bibliográfica sobre o assunto de vibrações para auxiliar na compreensão do trabalho. Após esses capítulos introdutórios é feita a apresentação e a modelagem matemática dos sistemas dinâmicos estudados: sistema NLGS ideal, sistema com rigidez não-linear e sistema não ideal. As equações de movimento são deduzidas pelo método de Lagrange. Após a dedução das equações de movimento faz-se a integração numérica utilizando o método de Runge-Kutta de quarta e quinta ordem e obtém-se a resposta dos sistemas (deslocamento, velocidade e aceleração). Como resultado da integração numérica são construídas algumas curvas, tais como: histórico de deslocamento, histórico de frequência, plano de fase, FFT, resposta em frequência e diagrama de bifurcação para ajudar na compreensão do comportamento dinâmico dos sistemas. Com base nos resultados obtidos percebe-se que os sistemas NLGS não ideal, NLGS ideal e com rigidez não linear apresentam um comportamento complexo devido à rigidez não-linear. Nesses três sistemas tem-se indicação de regime de movimento caótico inclusive. No sistema não ideal observa-se o efeito Sommerfeld, o qual deixa evidente a captura da rotação do motor pela frequência natural do sistema e o salto na curva da amplitude de deslocamento em função da frequência do motor. Fazendo um comparativo entre o...<br>Abstract: This dissertation concerns with the dynamics of a system with nonlinearity in the stiffness due to geometry of a pivot mechanism of two bars, called NLGS in the text. In the Introduction are shown examples of system with nonlinear stiffness due to geometry, emphasizing the application of this kind of system as vibration isolator and is also discussed about the human exposure to vibration as motivation and justification in the research, emphaizing the different resonance frequencies of the human body. In the sequence is carried out the literature review about vibrations to help on understanding the research. After these introductory chapters is done the presentation and mathematical modeling of the studied dynamic systems: non-ideal NLGS system, ideal NLGS system, nonlinear stiffness system and non-ideal system. The equations of motion are deduced by Langrange's method. After the deduction of the equations of motion is carried out the numerical integration using the fourth and fifth order Runger-Kutta's method and it is gotten the response of the systems (displacement, velocity and acceleration). As result of the numerical integration some curves are plotted, such as: displacement history, frequency history, phase portrait, FFT, frequency response and bifurcation diagram to help on understanding the dynamic behavior of the systems. Based on the results is noticed that the following systems have a complex behavior due to nonlinear stiffness: non-ideal NLGS, ideal NLGS and nonlinear stiffness system. In these three systems there are indications of chaotic motion. In the non-ideal system the Sommerfeld effect is observed, evidencing the capture of the frequency of motor by the natural frequency of the system and the jump in the curve of frequency response. Comparing the non-ideal NLGS system and the non-ideal system conludes that the Sommerfeld effect is eliminated and the maximum amplitude of displacement is reduced by 27% in the non-ideal...<br>Mestre
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Motta, Daniel da Silva. "Modelagem de uma suspensão veicular com elementos não lineares e comparação de seu desempenho com um modelo semi-ativo." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263860.
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Orientador: Douglas Eduardo Zampieri<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica<br>Made available in DSpace on 2018-08-05T06:44:34Z (GMT). No. of bitstreams: 1
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Previous issue date: 2005<br>Resumo: Este trabalho analisa e compara sistemas semi-ativos de controle de suspensões veiculares com um sistema passivo não-linear. O modelo matemático do sistema de suspensão, detalhado nesta dissertação, tem sete graus de liberdade, de modo a representar um veículo completo com suas quatro rodas. As duas leis de controle semi-ativas utilizadas foram baseadas na teoria do skyhook, sendo que em uma destas leis, o coeficiente de amortecimento varia continuamente (semi-ativa CVD) e, na outra, este coeficiente pode assumir um valor máximo ou um valor mínimo (semi-ativa ON-OFF). Para a análise dos sistemas foi desenvolvido um programa usando a ferramenta computacional SIMULINK, programa que permite a avaliação de diversas situações de sistemas veiculares. Os resultados evidenciam uma alternância de melhor desempenho entre os sistemas passivo não linear, semi-ativo ON-OFF e semi-ativo CVD, sendo que para uma avaliação mais detalhada do desempenho dos sistemas semi-ativos se faz necessária uma otimização dos parâmetros utilizados nas leis de controle. Neste trabalho fica bastante evidente a importância de se considerar o comportamento não linear do conjunto amortecedor e mola no sistema passivo<br>Abstract: This work describes the analysis and comparison of a vehicle suspension semi-active controlled to a non linear passive system. The mathematic model of a suspension system, detailed in this work, has seven degrees of freedom in order to represent a full vehicle system. The two semi-active control laws used in this work are based on the skyhook theory. In the first one the damping coefficient is continuously variable (semi-active CVD) and, in the second one the damping coefficient can assume a maximum or a minimum value (semi-active ON-OFF). To analyze the systems, it was developed a program using the SIMULINK computational tool. This program can evaluate different situations of vehicle suspension systems. The results show that the non linear passive system, semi-active ON-OFF and semi-active CVD alternate the better performance. To have a better understanding of semi-active performance, an optimization of the parameters used in the control laws is needed. This work also explains the importance of considering the non linear behavior of passive systems elements<br>Mestrado<br>Mecanica dos Sólidos e Projeto Mecanico<br>Mestre em Engenharia Mecânica
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Jerrelind, Jenny. "Design and Control of Products Including Parts with Impacts." Doctoral thesis, KTH, Farkost- och flygteknik, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3734.
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Today's product development process should be rapid andcost-efficient, and should result in innovative and reliableproducts. A crucial factor is the dynamic behaviour of theproduct. This thesis focuses on theoretical, numerical andexperimental approaches to achieve a comprehensiveunderstanding of dynamical phenomena occurring in nonlinearproducts, especially in products with parts that includeimpacts. The aim is to show the usefulness of nonlineartheories to better understand and optimise the dynamicbehaviour of products and thereby account for nonlinearphenomena already in the product development process. This is achieved through an investigation of researchefforts in the field of nonlinear dynamics; identification ofimportant research directions; a study on the effect ofcouplings between nonlinear parts; a detailed study on thedynamic behaviour of a product component; investigations oflow-cost strategies for controlling the dynamics of a nonlinearsystem; and the design and implementation of experimentalset-ups of two studied products. The investigation of research efforts shows that nonlinearparts are frequently included in products. Most common areparts that are nonlinear due to impacts and friction. Twoimportant areas are identified; to study coupling effectsbetween nonlinear subsystems and to study how nonlinearanalysis can be used to improve existing designs. Considering the studied products; a pantograph on a trainand a Braille printer, it can be concluded that thecharacteristics of a part can largely affect the dynamicbehaviour of the product. Typical nonlinear behaviour, such ascoexisting solutions and irregular motions, do occur. Theanalysis of the pan- tograph motion shows important aspects toconsider in the modelling process; coupling effects. In thecase of the Braille printer it is shown possible to create alow-cost control, by taking advantage of an existingdiscontinuity, to achieve a desired motion. Altogether, this work contributes to improved understandingof the be- haviour of nonlinear parts in products, especiallythose including impacts, pro- viding greater knowledge aboutaspects to consider in the design process. Keywords:Nonlinear Dynamics, Impacts, Discontinuities,Subsystems, Chaos, Irregular Behaviour, Printer Dynamics,Suspensions, Coupled Systems, Control.<br>QC 20100621
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Barillon, Franck. "Méthodologies de couplage fort des systèmes dynamiques : approches linéaires et non-linéaires." Thesis, Ecully, Ecole centrale de Lyon, 2011. http://www.theses.fr/2011ECDL0012/document.
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Dans cette thèse, nous nous sommes intéressés au comportement vibratoire d’un véhicule soumis à une excitation moteur dans deux plages de régimes différentes : basses fréquences (0 – 50 Hz) et moyennes fréquences (200 – 800 Hz). Le but était de fournir des méthodologies numériques permettant de prendre en compte les phénomènes de couplage vibratoires existant entre les différents sous-systèmes constitutifs d’une caisse automobile.En basses fréquences, nous avons adopté une approche globale où chaque sous-système a été caractérisé séparément. Tout d’abord, le comportement de la caisse a été caractérisé expérimentalement et numériquement par une méthode jusqu’alors réservée au domaine aéronautique dite d’appropriation modale. Les résultats numériques ont alors été confrontés aux résultats expérimentaux. Par ailleurs, le comportement non-linéaire en amplitude et en fréquence des pièces de filtration moteur (SMO) a été déterminé sur banc de mesure. Un fort comportement non-linéaire a pu être constaté et ces caractérisations ont été exploitées en construisant des nappes raideur-fréquence-amplitude. Dans un second temps, des méthodes numériques permettant de réaliser l’assemblage non - linéaire de la caisse et du groupe moto – propulseur (GMP) via les pièces de filtration non linéaires ont été mises en place. Pour ce faire, nous avons développé une méthode dite de Balance Harmonique (HBM) qui permet de prédire la dynamique non-linéaire de systèmes complexes. Afin d’appliquer cette méthode à une structure industrielle, nous avons utilisé une méthode de condensation sur les degrés de liberté non-linéaires, technique bien adaptée aux cas de structures linéaires reliées localement par des éléments de liaison non-linéaires. Cette méthode a tout d’abord été validée sur un périmètre restreint comprenant un GMP relié à un bâti rigide par ses pièces de filtration. A cette occasion, des phénomènes non-linéaires importants ont été constatés expérimentalement. Un modèle numérique de GMP a été construit et l’utilisation de la méthode HBM a permis de retrouver ces constats. Enfin, après avoir réalisé l’assemblage non-linéaire des trois sous-systèmes GMP - SMO - Caisse, la structure a été excitée de plusieurs manières différentes : appropriation numérique non-linéaire et excitation réelle d’un GMP. En moyennes fréquences, nous avons présenté dans ce mémoire une étude importante pour le groupe Renault concernant la caractérisation des pièces de filtration en moyennes fréquences. Au cours de la thèse, une méthodologie numérique basée sur la méthode FBS permettant de déconfiner (ou découpler) une suspension moteur initialement reliée à un banc de mesure a été proposée. La faisabilité numérique du déconfinement a ainsi été démontrée. Cette méthode permet donc, en dépit de phénomènes de couplage avec le banc de mesure, d’obtenir le comportement vibratoire intrinsèque de la pièce<br>In this thesis we studied the vibratory behaviour of a whole vehicle under engine excitation at low frequencies (0 – 50 Hz) and medium frequencies (200 – 800 Hz). The aim of the thesis was to provide numerical methodologies to take into account coupling effects between all the sub-systems constituting a whole car. In low frequencies, we used a global approach where each subsystem was characterized separately before coupling. First the car body was characterised both experimentally and numerically using a modal appropriation method that is commonly used in the aeronautic field. Numerical shapes of the modes were correlated to experimental shapes. In addition, the amplitude and frequency non linear behaviour of the engine mounts was measured on a test bench. A strong non linear behaviour was observed and stiffness – frequency – amplitude layers were constructed based on those data.Secondly, numerical methods were developed in order to calculate the coupled non linear response between the engine, the engine mounts and the car body. We used a harmonic balance method that allows calculating the non linear dynamics of complex mechanical systems. In order to apply this method to large industrial finite element models, a condensation method on non linear degrees of freedom was developed. This technique is well adapted to problems of linear structures linked together with localnon linear joints. This method was validated on the isolated engine linked to a bench by the engine mounts. Strong non linear phenomena on the rigid body modes of the engine were observed experimentally.A numerical model of the engine was developed and the HBM method allowed reproducing these non linear phenomena. Eventually, the non linear model of the whole vehicle was coupled and excited by different efforts. First we calculated the response of the assembly using the appropriation method. Then, the structure was excited by a real four – cylinder engine excitation.In medium frequencies, we presented an important study for the group Renault concerning the stiffness measurement of the engine mounts. A numerical methodology based on the FRF Based Substructuring(FBS) method was developed. This method was applied to uncouple an engine mount initially coupled to a test bench. The numerical feasibility of the method was proved and allowed to get the own vibratory behaviour of the engine mount despite coupling phenomena with the test bench
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陳祈銘. "Nonlinear and Adaptive Fuzzy Control for Active Suspension Systems." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/96685958682727585076.
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碩士<br>國立中興大學<br>機械工程學系<br>87<br>An active suspension system is inherently nonlinear due to the nonlinear electrohydraulic actuator dynamics. In this thesis, we propose a fuzzy auto-tuning PD control and an adaptive fuzzy sliding mode control for active suspension systems, and compare their performance with backstepping control proposed by Lin and Kanellakopoulos[11]. The Taguchi method is used for the optimal selection of the controller parameters.
The fuzzy auto-tuning PD controller is composed of a PD control with gains auto-tuned using a fuzzy system and nonlinear controls based on the electrohydraulic actuator nonlinear model. The design methodology is similar to the backstepping approach based on the cascade structure of the active suspension systems, however, it is much more simpler. As for the adaptive fuzzy sliding mode control, the traditional sliding mode control, backstepping control and adaptive fuzzy systems design methodology are integrated, and the Lyapunov theory is used to construct and analyze the stable adaptive system. The centers of the consequents of an adaptive fuzzy system are on-line adapted to update the gain of the switching part of the sliding control to compensate for the uncertainty.
Computer simulations show that the ability of the backstepping control to reject the road disturbance is better than the other two strategies, but its response speed is rather slow, and its robustness is very poor. The suggested adaptive fuzzy sliding mode control can work well and have good robustness. Form implementation point of view, the fuzzy self-tuning PD control is more practical than the other twos since its control performance is good and the required computation is much lower.
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Huang, Chao-Ming, and 黃兆銘. "Nonlinear Controller Design of Repulsive Maglev Suspension Guiding System." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/97131423013391887515.
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博士<br>國立臺灣大學<br>機械工程學研究所<br>87<br>The most popular approach to achieve ultra-high precision positioning is to use compound actuators. The compound actuators generally include flexure type actuators to achieve very fine positioning resolution, and ball-screws to cover the large travels. These compound actuator configurations have dominated the equipment market in recent years; however, these configurations are still associated with some problems. First of all, the flexure mechanisms driven by piezo-electric actuators are usually highly oscillatory. Secondly, the different actuator resolutions make the system behavior highly non-linear. It is also well known that the lubrication for the ball-screws requires special treatment. The alternate approaches to avoid friction and backlash is to adopt a non-contact bearing mechanisms. These include air-lubricated levitation, electrostatic levitation, and magnetic levitation (maglev). In this thesis, a Repulsive Maglev Suspension Guiding System (RMSGS) is designed for this purpose. But according to the unstable nature of maglev system, a closed-loop controller is necessary.
In this thesis, we want to stabilize the RMSGS and improve the system stiffness by designing a nonlinear controller. Based on three nonlinear control frameworks, Jacobian Linearization, Input-Output Feedback Linearization and Approximate Input-Output Feedback Linearization, we combine the Adaptive Sliding Mode Control individually to improve the robustness of closed-loop system. Real experimental tests, simulations, and theoretical analyses all prove that the Adaptive Sliding Mode Control based on Approximate Input-Output Feedback Linearization and Backstepping has the best result, not only in transient response but also closed-loop frequency response.
First, we transform the nonlinear model of system to polynomial model by means of Approximate Input-Output Feedback Linearization, and then we can find some dynamics from the polynomial model, which are helpful to system stability. By applying Avoid Cancellation to these helpful dynamics, the improvement of system bandwidth, stiffness and settling time could be obtained.
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Chou, Tzu Ming, and 周子明. "A Nonlinear Control for Two-dimensional Magnetic Suspension System." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/30784535871437919830.
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碩士<br>國立清華大學<br>動力機械學系<br>84<br>This paper presents a practical design and implementation
method of multivariable sliding mode control for magnetic
suspension system represented by a nonlinear dynamic model. On
the basis of the Lyapunov function approach,the proposed design
method ensure the existence of a control law to satisfy the
sliding mode con- dition. The designed controller was
successfully implemented in an experimental magnetic suspension
system. Experimental results showed that the system was well
under the control of a predeter- minate sliding mode dynamics
and verified the capabilities of the controller.
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Hsieh, I.-Che, and 謝易哲. "The Internal Resonance Analysis of A Nonlinear Suspension Elastic Beam." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/17136422008815509868.
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碩士<br>淡江大學<br>航空太空工程學系碩士班<br>99<br>The internal resonance (I.R.) of a Bernoulli-Euler Beam with nonlinear suspensions (cubic nonlinear springs) and with different end supports was studied in this thesis. The Bernoulli-Euler Beam is suspended by nonlinear springs (similar to Winkler Type Foundation) to the top ceiling. Four different types of boundary conditions are considered in the study, which are hinged-hinged, hinged-roller support, fixed-fixed, and spring-spring support, respectively. A simple Aerodynamic loading is included to simulate this suspension bridge vibration system. This research is to find the I.R. conditions for the boundary conditions aforementioned and subjected to Aerodynamic and simple harmonic loadings. The method of Multiple Scales (MOMS) is applied to get the conditions for I.R. The classical structural Dynamic analysis is also employed for finding mode shapes of the beam for different boundary conditions. By using the orthogonal properties, this problem can be deduced to a to a time domain ordinary differential equation. The I.R. condition for the cases studied can be determined analytically. The analytical predictions are confirmed by the Fixed Point plots and phase plots.
This research found that the 3:1 I.R. occurred in the case of hinged-hinged boundary conditions in the 1 and 3 modes. The 3:1 I.R. also occurred in the case of hinged-roller boundary conditions in the 1 and 3 modes. The 3:1 I.R. occurred in the case of fixed-fixed boundary conditions in the 2 and 4 modes. The 3:1 I.R. occurred in the case of spring-spring boundary conditions in the 2 and 4 modes.
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Ru, Lee Chang, and 李承儒. "Nonlinear Dynamic Analysis of Suspension Bridge by the VFIFE Method." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/hxs34a.
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碩士<br>國立中央大學<br>土木工程學系<br>103<br>This paper studies the dynamic response of the Suspension bridge after the earthquake force. Suspension bridge is Flexible structure. Determining the security status of suspension by force after the destruction failure. And using VFIFE to analyze the dynamic response. In this case, Bitan Suspension bridge is used. By using data of temperature and human being to build the model. And apply external forces into model to determining structure failure.
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Chen, Ying-Zuo, and 陳盈佐. "Development of a Magnetic Suspension System with Nonlinear Control Approach." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/49340542893041534753.
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碩士<br>國立東華大學<br>電機工程學系<br>98<br>Magnetic suspension systems are highly nonlinear and essentially unstable systems. In the current drive, according to the equivalent circuit scheme of electromagnet, a feedback circuit is proposed to improve the transient response and relative stability of the current drive.
First, in the proposed controller, the feedback linearization technique is used to transform the dynamic model of the magnetic suspension system to linear model. Then, according to the linearization dynamics a sliding-mode controller based on the linear model is designed, and the stability of this controller law is approved by Lyapunov Stability Theory.
At last, simulation and experimental results are illustrated to validate the control method for tracking applications.
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Joarder, Mahmud Niroopam. "Influence of nonlinear asymmetric suspension properties on the ride characteristics of road vehicle." Thesis, 2003. http://spectrum.library.concordia.ca/1935/1/MQ77979.pdf.
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The suspension springs and dampers, employed in road vehicles, typically exhibit nonlinear and asymmetric force-deflection and force-velocity characteristics. The asymmetric characteristics of the suspension components are characterized to investigate the phenomenon of drift in dynamic equilibrium, also known as the 'ride height drift'. A quarter-vehicle model, incorporating nonlinear and asymmetric suspension components, is mathematically modeled and simulated using 'simulink'. Suspension damper is represented by multistage nonlinear asymmetric characteristics, while the stiffness is treated as a nonlinear cubical spring, asymmetric in compression and rebound. The model results are validated by comparing the responses over a wide frequency range with the published data. A comprehensive parametric study is performed to establish the influence of variation in design and operating parameters of suspension components on 'ride height drifting' phenomenon. The study clearly reveals that the 'ride height drifting' phenomenon is a direct result of asymmetric properties of the suspension damper. The magnitude of the drift increases with an increase in asymmetry as well as amplitude of excitation, and it approaches maximum corresponding to the wheel hop natural frequency. Reduced damping with a fixed asymmetry also tends to increase the magnitude of drift over the entire frequency range. The results further suggest that, the suspension spring with hardening and softening characteristics in compression and extension, respectively, yields the sprung mass drift in the opposite direction. Suspension springs with asymmetric characteristics may thus reduce the magnitude of the sprung mass drift.
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游本呈. "The Effect of Nonlinear Suspension on the Dynamic Performance of Automatic Ball Balancer." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/93796227309926226104.
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Chang, Ji-Jing, and 張繼靖. "Dynamic Analyses of Vehicles with Nonlinear Secondary Suspension Damping Running on Tracks with Irregularity." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/05628114688004322083.
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碩士<br>國立臺灣科技大學<br>機械工程系<br>93<br>This thesis studies the vertical and lateral dynamic behavior of a vehicle running on a slab track with vertical and lateral irregularities. In this work, both the carbody and rails are assumed as Euler beams, and the carbody is equipped with nonlinear lateral dampers. First, the discretized eqations of motion of the elastic carbody and rails are formulated by the finite element method, and the equations of motion of bogies and wheelsets are derived by Newton’s second law. Then, these equations are assembled to yield the equations of motion for the vehicle and track systems, respectively. Through the interactive forces between wheels and tracks, the vehicle and track systems will be coupled. These interactive forces include the normal contact forces and tangential creep forces. The normal contact force is simulated by nonlinear Hertzian’s theory for elastic contacts, and the tangential creep force is simulated by Kalker’s linear creep theory. The tangential creep force is further modified by the Johnson’s nonlinear method to control its range. Finally, Newmark’s method is applied to obtain the dynamic responses of the vehicle and track systems at each time step.
Numerical results show that when a vehicle runs along perfect straight tracks, the dynamic responses of the vehicle/track systems do not have much difference between the cases with linear or nonlinear lateral dampers. But when it runs along perfect curved tracks, the dynamic behavior of the vehicle/track systems will vary due to the centrifugal force. The types of lateral dampers will affect the responses of the vehicle/track systems. The lateral displacement of the carbody with nonlinear lateral dampers tends to go back to the original position. When a vehicle runs on tracks with vertical and/or lateral irregularities, the dynamic responses of vehicle system will be affected. The effect of the vehicle speed on the responses of the vehicle system will be more noticeable for higher vehicle speeds.
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Chang, Chia-Man, and 張家嫚. "The Study of A Nonlinear Suspension Elastic Beam with An End Point Dynamic Vibration Absorber." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/71955259940263791315.
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碩士<br>淡江大學<br>航空太空工程學系碩士班<br>101<br>This study investigated the performance of a mass-spring dynamic vibration absorber (DVA) at the free end of a hinged-free elastic beam under simple harmonic excitation. This beam system was suspended by suspension cables. These cables were simulated by cubic nonlinear springs to examine the nonlinear characteristics of this system. The combination of mass and spring constant of the tip-attached dynamic vibration absorber (DVA) were investigated. This time-dependent non-homogeneous boundary condition problem was solved by Mindlin-Goodman method. By using the shifting polynomial function, one can transform this system to a homogeneous boundary problem. The method of multiple scales (MOMS) was performed to solve the nonlinear equations. The 1:3 internal resonance was found at the 1st and 2nd modes of this beam system. The fixed point plots were obtained and compared with the numerical results to verify the system internal resonance. The Poincare Map was also utilized to identify the system instability frequency region of the jump phenomenon. The parameters of the tip attached DVA were studied. The internal resonance can be avoid for the existence of the DVA. The optimal DVA mass and the spring constant were provided for best beam vibration reduction. Finally, the wind speeds and aerodynamic loads were included to investigate the stability of this system. The system stability was analyzed by Floquet theory and Floquet multipliers. The basin of attraction charts were made to verify the effects of the combinations of DVA’s mass and the spring constant at diverge speed.
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Bau, Guo Fang, and 郭芳寶. "Vehicle Carried Suspension Bridge Construction Stage Nonlinear Analysis – Taking Swing Column Bridge Tower as an Example." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/wcgdsy.
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碩士<br>國立高雄應用科技大學<br>土木工程與防災科技研究所<br>101<br>The purpose of this paper is to perform nonlinear analysis on Swing column vehicle carried suspension bridges during construction stage. Researches were focused on suspension bridges which had rotating shafts supported design at bottom of bridge tower that it bears purely axis, shear forces, and reducing bending stresses. Study was on nonlinear analyzing on Swing column vehicle carried suspension bridge during construction stage.Research methods were, after confirmation of geometrical shapes and initial states of suspension bridges, built up analysis models using SAP2000 finite element software and carried out numerical simulations; to predict strain and internal forces spreading of main cable, bridge tower, and stiffening girder on each construction stages respectively and compared with three construction stage instances of vehicle carried suspension bridge in this paper for analysis; to study linear changes of main cable, calculated length errors of main cable and suspension cable; and to predict structural displacement and changes of internal forces of three Swing column vehicle carried suspension bridges during construction stages to ensure suspension bridges construction precision.Finally, dynamic analysis was applied on three suspension bridge construction instances.Several important discoveries were resulted by this research: (1) while building finite element models for suspension bridges designer should consider geometrical and material nonlinear interferences in addition to actual construction steps in order to predict the correspondence and displacement of each structural element of suspension bridges precisely. (2) The main cable of suspension bridge was a parabola curve in its initial construction state. Main cable turned into funicular curve when adding stiffening girder segments. The actual shapes of main cable depended on Sag/Span Ratio, sling separation, dead load of stiffening girder. (3) Along with construction stages stiffening girders were segment connected which increased vertical stiffness and vibration frequency of suspension bridge effectively. The dead load of stiffening girder at the same time could promote axial forces of main cable which greatly helped in resisting vibration of main cable and twisting of stiffening girder. (4) It is inferred by this paper that before closing stiffening girder, all stretches caused by temperature were absorbed by main cable, which caused larger displacement of tower top; conversely, after closing of stiffening girder, the stretches caused by temperature were absorbed by movable supports that connect bridge abutment and stiffening girder, therefore the displacement of tower top would not be interfered too much. (5) Linear changes of main cable during construction stage for both three-span and single-span suspension bridges would be interfered by central sag of side span main cables.The research results of this paper were expected to be references of Swing column suspension bridge nonlinear analysis and construction control.
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Zambare, Hrishikesh B. "Nonlinear design, modeling and simulation of magneto rheological suspension: a control system and systems engineering approach." Thesis, 2017. https://doi.org/10.7912/C2GW8S.
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Indiana University-Purdue University Indianapolis (IUPUI)<br>Suspension has been the most important subsystem of the vehicle viewed as a system. The ride comfort and vehicle handling performance are affected by the suspension design. Automotive technology has been continuously incorporating developments over the past few decades to provide the end users with a better comfort of driving. Multi-objective optimization of MR damper with objective function of maximizing damping force generated by MR damper with the geometrical parametric constraint function is achieved in this research using pattern search optimization technique.
Research focuses on design, modeling, and simulation of active suspension using non-linear theory of the Magneto-Rheological (MR) damper with consideration of the hysteresis behavior for a quarter car model. The research is based on the assumption that each wheel experiences same disturbance excitation. Hysteresis is analyzed using Bingham, Dahl’s, and Bouc-Wen models. Research includes simulation of passive, Bingham, Dahl, and Bouc-wen models. Modeled systems are analyzed for the six road profiles, including road type C according to international standards ISO/TC108/SC2N67. Furthermore, the comparative study of the models for the highest comfort with less overshoot and settling time of vehicle sprung mass are executed. The Bouc-Wen model is 36.91 percent more comfortable than passive suspension in terms of damping force requirements and has a 26.16 percent less overshoot, and 88.31 percent less settling time. The simulation of the Bouc-Wen model yields a damping force requirement of 2003 N which is 97.63 percent in agreement with analytically calculated damping force generated by MR damper. PID controller implementation has improved the overshoot response of Bouc-Wen model in the range of 17.89 percent-81.96 percent for the different road profiles considered in this research without compromising on the settling time of system. PID controller implementation further improves the passenger comfort and vehicle ride handling capabilities.
The interdisciplinary approach of systems engineering principles for the suspension design provides unique edge to this research. Classical systems engineering tools and MBSE approach are applied in the design of the MR damper. Requirement traceability successfully validates the optimized MR damper.
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Lin, Chao-Ping, and 林昭平. "Investigation of the Nonlinear Optical Response of the Transparent Nanoparticle Suspension in Glycerol Solution in Steady State Using the Z-scan Technique." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/15504883501643292037.
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碩士<br>國立臺灣大學<br>物理研究所<br>101<br>The nonlinear optical response of the nanoparticle suspension has been a subject of interest for about three decades. For self-focusing, it can be dated back to $1982$ when A. Ashkin demonstrated the optical gradient force can give rise to self-trapped beams. Such self-focusing can also arises from the Soret effect, which can be achieved with much lower peak intensity when the particle size in the suspension is of the order of nanometer.
In this thesis, we focus on the nonlinear optical response of the transparent nanoparticle suspension in glycerol solution using Z-scan technique. In the beginning, we propose a model to investigate the possibility of the self-focusing induced by the radiation pressure. A counter-propagating experiment shows the radiation force is not the dominant mechanism. But the experimental results possess radial symmetry. Therefore, we make the assumption that the refractive index change of the nonlinear optical response is a function of radial distance from the center of the laser beam. To investigate the form of this distribution, we set up a Z-scan experiment and obtain characteristic curves of various samples. Comparing these curves with that obtained from theoretical results, we suggest the dominant mechanism is a combination of the thermal lens and the Soret effect. Also, the results show that the Soret effect is the major nonlinear effect when there are nanoparticles in the solution. Finally, we discuss a way to extract the dynamics of the nanoparticle based on the principle of the Z-scan experiment.
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Henrich, Oliver [Verfasser]. "Nonlinear rheology of colloidal suspensions / vorgelegt von Oliver Henrich." 2007. http://d-nb.info/987191047/34.
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Singh, Jagdish Pratap. "Non-Dimensional Kinetoelastic Maps for Nonlinear Behavior of Compliant Suspensions." Thesis, 2014. http://hdl.handle.net/2005/3137.
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Compliant suspensions are often used in micromechanical devices and precision mechanisms as substitutes for kinematic joints. While their small-displacement behavior is easily captured in simple formulae, large-displacement behavior requires nonlinear finite element analysis. In this work, we present a method that helps capture the geometrically nonlinear behavior of compliant suspensions using parameterized non-dimensional maps. The maps are created by performing one nonlinear finite element analysis for any one loading condition for one instance of a suspension of a given topology and fixed proportions. These maps help retrieve behavioral information for any other instance of the same suspension with changed size, cross-section dimensions, material, and loading. Such quantities as multi-axial stiffness, maximum stress, natural frequency, etc. ,can be quickly and accurately estimated from the maps. These quantities are non-dimensionalized using suitable factors that include loading, size, cross-section, and material properties. The maps are useful in not only understanding the limits of performance of the topology of a given suspension with fixed proportions but also in design. We have created the maps for 20 different suspensions. Case studies are included to illustrate the effectiveness of the method in microsystem design as well as in precision mechanisms. In particular, the method and 2D plots of non-dimensional kinetoelastic maps provide a comprehensive view of sensitivity, cross-axis sensitivity, linearity, maximum stress, and bandwidth for microsensors and microactuators.
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Hu, Jia-Wei, and 胡嘉偉. "Nonlinear Control of Full-Vehicle Active Suspensions with Backstepping Design Scheme." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/95073328858015888511.
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碩士<br>國立暨南國際大學<br>電機工程學系<br>95<br>In recent years, due to the prosperous developments of high technologies and automobile industries, lots of new technologies are applied in the design of vehicles. Therefore, the comfortable security design for active suspension system has become the researchful goal of all kinds of advanced car. The dual objective is to minimize the vertical forces transmitted to the passengers for improving the ride quality and to maximize the tire-to-road contact for enhancing the handling performance and driving safety, when designing the automotive vehicle suspension. In the design of vehicle suspension systems, the various performance parameters which should be considered are given as follows: body motion, ride quality, road handling and suspension travel. This thesis develops a novel nonlinear backstepping design for the control of full-vehicle active suspension systems to improve the conflicting objectives which are inherent tradeoff between ride quality and suspension travel. Suspension travel means the space variation between body and tire. In order to avoid the suspension hits the vehicle body, the controllers must have the ability to prevent the suspension form hitting its travel limitation. The novelty is in use of nonlinear filter whose effective bandwidth depends on the magnitudes of suspension travel. Therefore, this kind of design allows the close-loop system with the ability to execute in different operating regions. In other words, the nonlinear controller can smoothly transfer its priority between the conflicting objectives of ride comfort and suspension travel.