Speed bump energy harvester, which aims to harvest energy from the passing by vehicles by absorbing their kinetic and potential energy, is designed, fabricated, simulated, and tested in this research. The proposed design is analyzed with a theoretical modelling which has then been validated with a ground test. Result reveals that the prototype has been able to produce up to 600 watts of peak power and around 150 watts of RMS power which is significant number. Further analysis has been done which theoretically suggests that the numbers could be increased up to 1 KW by optimizing the speed bump design and varying the system parameters such as electrical damping, mechanical damping, velocity and weight of the vehicles. Overall, system is able to increase the overall energy density by using Mechanical Motion Rectification (MMR) technology which would allow the increase in the power generation almost by double. Furthermore, different vehicle models have been used to analyze the effectiveness and accuracy of the harvester and also, the effect of harvester on the dynamics of the vehicle has been studied and analyzed in detail. / Master of Science

This experimental study evaluates the dynamic response of five semi-active control policies as tested on a single suspension quarter-car system. Incorporating a magneto-rheological damper, the full-scale 2DOF quarter-car system was used to evaluate skyhook, groundhook, and hybrid control. Two alternative skyhook policies were also considered, namely displacement skyhook and relative displacement skyhook. As well as exploring the relative benefits of each of these controllers, the performance of each semi-active controller was compared to the performance of conventional passive damping. Each control policy is evaluated for its control performance under three different base excitations: chirp, step, and pure tone. Corresponding to the chirp input, transmissibilities and auto spectrums are considered for each control policy. Specifically, transmissibilities between the sprung mass displacement and the unsprung mass displacement are generated relative to the input displacement. Further, the ratio between the relative displacement across the damper and the input displacement is evaluated for each control technique. The chirp input also reveals the results of the auto spectrums of the sprung and unsprung mass accelerations. Both the step input and the pure tone input were used to generate time domain values of RMS and peak-to-peak displacements and accelerations. This study shows that semi-active control offers benefits beyond those of conventional passive damping. Further, traditional skyhook control is shown to outperform the less conventional alternative skyhook policies. / Master of Science

This study provides a comprehensive performance analysis of Wave-Adaptive Modular Vessels (WAM-V) using simulations and testing data. WAM-Vs are a new class of marine technology that build upon the advantages of lightweight, low-draft, catamaran construction. Independent suspensions above the hulls isolate the passengers and equipment from the harsh sea environment. Enhanced understanding of the relationship between suspension and vehicle performance is critical for future missions of interest to the U.S. Navy. Throughout this study, the dynamic properties of three different WAM-Vs were evaluated. A multi-body dynamics simulation was developed for the 100-ft WAM-V 'Proteus' based on an automotive 4-post shaker rig. The model was used to characterize the sensitivities of different suspension parameters and as a platform for future models. A 12-ft unmanned surface vessel (USV) was instrumented and sea trials were conducted in the San Francisco Bay. A dynamic 4-post simulation was created for the USV using displacement inputs calculated from acceleration data via a custom integration scheme. The data was used to validate the models by comparing the model outputs to sensor data from the USV. A vertical hydrodynamics testing rig was developed to investigate the interaction between the pontoons and the water surface to improve the understanding of how hydrodynamic forces affect suspension performance. A model was created to accurately simulate the hydrodynamic forces that result from vertical pontoon motion. The model was then scaled to fit a 33-ft WAM-V prototype. The 33-ft WAM-V was instrumented and sea trials were conducted in Norfolk, VA. The WAM-V's suspension was upgraded based on the testing results. A 2-post rig was also built for evaluating the 33-ft WAM-V's dynamics. Two dynamic models were made for the 33-ft WAM-V to evaluate different suspension designs. The results from this study have numerous impacts on the naval community and on the development of WAM-Vs. The methodology for testing and evaluation will allow for future WAM-V designs to be compared under controlled circumstances. The performance of WAM-Vs can then be compared against conventional platforms to determine their suitability for future missions. Simulation development will enable future WAM-Vs to be evaluated prior to undergoing sea trials. The hydrodynamic models become a powerful design tool that can be easily scaled and combined with the 4-post models. By providing the simulations and test data to future vessel designers, the designers will be able to intelligently evaluate numerous iterations early in the design phase, improving performance and safety. / Ph. D.

This analytical study evaluates the response characteristics of a two-degree-of freedom quarter-car model, using passive and semi-active dampers, along with a seven-degree-of-freedom full vehicle model. The behaviors of the semi-actively suspended vehicles have been evaluated using skyhook, groundhook, and hybrid control policies, and compared to the behaviors of the passively-suspended vehicles. The relationship between vibration isolation, suspension deflection, and road-holding is studied for the quarter-car model. Three main performance indices are used as a measure of vibration isolation (which can be seen as a comfort index), suspension travel requirements, and road-holding quality. After performing numerical simulations on a seven-degree-of-freedom full vehicle model in order to confirm the general trends found for the quarter-car model, these three indices are minimized using optimization techniques. The results of this study indicate that the hybrid control policy yields better comfort than a passive suspension, without reducing the road-holding quality or increasing the suspension displacement for typical passenger cars. The results also indicate that for typical passenger cars, the hybrid control policy results in a better compromise between comfort, road-holding and suspension travel requirements than the skyhook and groundhook control policies. Finally, the numerical simulations performed on a seven-degree-of-freedom full vehicle model indicate that the motion of the quarter-car model is not only a good approximation of the heave motion of a full-vehicle model, but also of the pitch and roll motions since both are very similar to the heave motion. / Master of Science

This study experimentally evaluates the dynamic response of a single vehicle suspension incorporating a magneto-rheological (MR) damper. A full-scale two-degree-of-freedom (2DOF) quarter-car test apparatus has been constructed at the Advanced Vehicle Dynamics Lab at Virginia Tech to evaluate the response of a vehicle suspension under the different control schemes of skyhook, groundhook, and hybrid semiactive control. The quarter-car apparatus was constructed using materials from 80/20 Incorporated and a hydraulic actuation system from MTS. A dSPACE AutoBox was used both for controlling the MR dampers and acquiring data. The first task was to understand the baseline dynamic response of the quarter-car system with only a passive damper. Next, the passive damper was replaced with a controllable MR damper. The control schemes of skyhook, groundhook, and hybrid semiactive control were applied to the MR damper. The physical response of the quarter-car with the different control schemes was then compared to the analytical prediction for the response, with favorable results. The response of the quarter-car with the semiactive damper was also compared to the response of the quarter-car with a passive damper, and the resulting limitations of passive damping are discussed. Finally, the practical implications of this study are shown in a discussion of the physical implementation of the MR dampers in the Virginia Tech FutureCar, a full-size Chevrolet Lumina. Although the actual skyhook, groundhook, and hybrid semiactive control schemes were not implemented on the vehicle, the results were promising and generated several recommendations for future research. / Master of Science

O objetivo deste trabalho é estudar a influência da rigidez do quadro na dirigibilidade de um veículo de competição fórmula SAE (protótipo E2-M, da equipe EESC-USP) em ambiente multicorpos com o software Adams/Car. Um modelo contendo os subsistemas de suspensão, direção, pneumático, powertrain, barra estabilizadora e quadro foi construído em ambiente multicorpos com componentes modelados como corpos rígidos. Posteriormente foram elaborados três modelos de quadros flexíveis com diferentes valores de rigidez torcional para substituir o quadro rígido. Estes foram obtidos através da análise modal com o auxílio do método dos elementos finitos. Para comparação da dinâmica lateral dos modelos, típicas manobras do estudo de dirigibilidade foram consideradas tais como rampsteer, step-steer e single lane change. Os resultados obtidos foram de aceleração lateral e velocidade de guinada. Pelas condições avaliadas, pode-se concluir que a rigidez torcional de um quadro para o protótipo E2-M pode estar entre 700 e 1500 N.m/o. Essa variação de rigidez representou 5 kg de massa no quadro. Porém deve-se fazer uma avaliação modal com a massa suspensa calibrada para verificar se não existe acoplamento de modos e freqüências com outros subsistemas. / This dissertation is intended to study the influence of frame stiffness in handling of a Formula SAE vehicle (E2-M prototype from EESC-USP Formula SAE team) in multibody with Adams/Car software. A model containing the subsystems of suspension, steering, tires, powertrain, frame and stabilizing bar was built considering rigid bodies. Subsequently, three models of flexible frames were developed with different values of torsional stiffness to replace the rigid frame. They were obtained through modal analysis with the aid of finite element method. For the handling investigation, maneuvers such as ramp-steer, step-steer and single lane change were considered. The results evaluated were lateral acceleration and yaw velocity. According to results, the torsional stiffness for the E2-M prototype can be between 700 and 1500 Nm/o. But an eigenvalue analyses is also necessary to verify if there is no coupling of modes of the calibrated sprung mass with other subsystems.

O objetivo deste trabalho é estudar a influência da rigidez do quadro na dirigibilidade de um veículo de competição fórmula SAE (protótipo E2-M, da equipe EESC-USP) em ambiente multicorpos com o software Adams/Car. Um modelo contendo os subsistemas de suspensão, direção, pneumático, powertrain, barra estabilizadora e quadro foi construído em ambiente multicorpos com componentes modelados como corpos rígidos. Posteriormente foram elaborados três modelos de quadros flexíveis com diferentes valores de rigidez torcional para substituir o quadro rígido. Estes foram obtidos através da análise modal com o auxílio do método dos elementos finitos. Para comparação da dinâmica lateral dos modelos, típicas manobras do estudo de dirigibilidade foram consideradas tais como rampsteer, step-steer e single lane change. Os resultados obtidos foram de aceleração lateral e velocidade de guinada. Pelas condições avaliadas, pode-se concluir que a rigidez torcional de um quadro para o protótipo E2-M pode estar entre 700 e 1500 N.m/o. Essa variação de rigidez representou 5 kg de massa no quadro. Porém deve-se fazer uma avaliação modal com a massa suspensa calibrada para verificar se não existe acoplamento de modos e freqüências com outros subsistemas. / This dissertation is intended to study the influence of frame stiffness in handling of a Formula SAE vehicle (E2-M prototype from EESC-USP Formula SAE team) in multibody with Adams/Car software. A model containing the subsystems of suspension, steering, tires, powertrain, frame and stabilizing bar was built considering rigid bodies. Subsequently, three models of flexible frames were developed with different values of torsional stiffness to replace the rigid frame. They were obtained through modal analysis with the aid of finite element method. For the handling investigation, maneuvers such as ramp-steer, step-steer and single lane change were considered. The results evaluated were lateral acceleration and yaw velocity. According to results, the torsional stiffness for the E2-M prototype can be between 700 and 1500 Nm/o. But an eigenvalue analyses is also necessary to verify if there is no coupling of modes of the calibrated sprung mass with other subsystems.

The wheel-rail contact is at the core of all research related to vehicletrackinteraction. This tiny interface governs the dynamic performanceof rail vehicles through the forces it transmits and, like any high stressconcentration zone, it is subjected to serious damage phenomena. Thus,a clear understanding of the rolling contact between wheel and rail is keyto realistic vehicle dynamics simulation and damage analysis. In a multi-body dynamics simulation, the demanding contact problemshould be evaluated at about every millisecond for several wheel-rail pairs.Hence, a rigorous treatment of the contact is highly time-consuming.Simplifying assumptions are therefore made to accelerate the simulationprocess. This gives rise to a trade-o between the accuracy and computationaleciency of the contact model in use. Conventionally, Hertz+FASTSIM is used for calculation of the contactforces thanks to its low computational cost. However, the elliptic patchand pressure distribution obtained by Hertz' theory is often not realisticin wheel-rail contact. Moreover, the use of parabolic traction bound inFASTSIM causes considerable error in the tangential stress estimation.This combination leads to inaccurate damage predictions. Fast non-elliptic contact models are proposed by others to tacklethis issue while avoiding the tedious numerical procedures. The studiesconducted in the present work show that the accuracy of these models iscase-dependent. To improve the accuracy of non-elliptic patch and pressure estimation,a new method is proposed. The method is implemented in an algorithmnamed ANALYN. Comparisons show improvements in patch and, particularly,pressure estimations using ANALYN. In addition, an alternative to the widely-used FASTSIM is developed, named FaStrip. Unlike FASTSIM, it employs an elliptic traction boundand is able to estimate the non-linear characteristic of tangential stressdistribution. Comparisons show more accurate estimation of tangentialstress and slip velocity distribution as well as creep forces with FaStrip. Ultimately, an ecient non-elliptic wheel-rail contact model consistingof ANALYN and FaStrip is proposed. The reasonable computationalcost of the model enables it to be used on-line in dynamics simulationand its accuracy can improve the damage predictions. / <p>QC 20160202</p>

This thesis describes an investigation into vehicle handling control using active differentials in the rear axle of a motor vehicle. Such devices are able to transfer torque between the rear wheels and have traditionally been used to improve traction whilst minimising the impact on vehicle handling. However, the capacity to generate a lateral torque difference across an axle also gives them the potential to be used for yaw moment control. In order to generate a rigorous assessment of this potential, the investigation is carried out in three distinct phases. Firstly, an analysis of the scope for modifying vehicle handling given unrestricted control over torque transfer between the rear wheels is carded out in the simulation environment. For this purpose an idealised yaw sideslip controller is developed. This is used to show that an ideal active differential can have significant yaw moment authority in terms of generating both understeer and oversteer and that this can be used to actively modify a vehicle's handling balance and apply stability control at the limits of adhesion. In the second phase, the capabilities of two types of contemporary active differential, the torque vectoring differential (TVD) and active limited slip differential (ALSID), are then assessed against the ideal differential and against a brake based yaw moment controller. TVDs are found to be able to offer very similar performance to both their ideal counterpart and to the brake based system. They Gan also deliver this performance with a fraction of the energy loss that is observed in the brakes, thus making TVDs a viable proposition for applying continuous yaw control below the limits of adhesion. ALSDs, on the other hand do not offer equivalent functionality to an ideal active differential but are still shown to be very effective stability control devices. In the third phase, the ALSID results are validated on a prototype vehicle where it is shown that they do indeed offer substantial stability improvements both on high and low-P surfaces. However in order to deliver such benefits and be practical for implementation, it is also shown that significant redevelopment of the idealised controller is required. Finally, with the ALSID operating alongside a commercial brake based stability control system, it is proven that substantial reductions in brake intervention can be achieved without significant controller integration.

A utilização de motores elétricos diretamente nos cubos de roda é uma alternativa de propulsão para um veiculo elétrico ou híbrido muito interessante, pois não necessita do uso de sistemas complexos de transmissão, tornando o conjunto mecânico muito mais simples e, consequentemente, reduzindo a sua massa, atritos e custos. Entretanto, a adição dos motores nas rodas causa o incremento da massa não suspensa, e isto irá afetar o comportamento de dirigibilidade do veículo. Dessa forma, com ajuda da ferramenta de multicorpos, será identificado o que ocorrerá devido ao acréscimo de massa compatível com os motores elétricos de última geração. Para isto, uma série de análises comparativas será realizada, com modelos de veículos baseados na técnica de multicorpos, para o caso de um carro de passeio compacto. Primeiramente, uma análise modal comparando um carro convencional aos carros com a utilização dos motores, no eixo traseiro ou no dianteiro, e uma posterior avaliação das frequências obtidas. Em sequência, também foram realizadas manobras padrão com o modelo de veículo completo e foram observadas maiores influências nos resultados das análises em regime transiente, como a manobra de troca de faixa e a manobra do anzol (\"fishhook\"). Com a ajuda destes resultados, foi possível identificar que as instalações dos motores elétricos nos cubos traseiros causam uma menor influência negativa no desempenho de dirigibilidade, quando comparado com o caso instalado no eixo dianteiro. Através de uma otimização realizada com a ajuda de uma análise de sensibilidade das variáveis do sistema (D.O.E.), baseada na manobra do anzol, foi possível identificar que alterações nas molas, amortecedores e barra estabilizadora são capazes de mitigar os efeitos indesejáveis causados pelo incremento de massa não suspensa. / The electric motors directly in wheel hubs usage is an alternative of propulsion for a electric or hybrid vehicle, since it does not need the use of complex systems of transmission, making the mechanical assembly simpler and, consequently, reducing its mass , frictions and costs. However, the addition of the motors in the wheels causes an increase unsprung mass, and this will affect the vehicle handlings behavior. In that way, with the assistance of the multibody tool, it will be identified the consequences of mass addition, compatible with the moderns electric motors of. In this work, a series of comparative analyzes will be carried out, with vehicle models based on multibody techniques, in the situation of a compact car. First, a modal analysis comparing a conventional car to with the vehicle using hub driven motors, in rear or front axle, and an evaluation of the obtained frequencies. In the sequence, standard maneuvers were also performed with the complete vehicle model, and greater influences were observed in the transient analysis results, such as lane change and fishhook maneuver. With help of these results, it was possible to identify; that the installation of the electric motors in the rear hubs causes a smaller negative influence on the handling performance when compared to the case installed on the front axle. Through an optimization performed with the aid of a system variable sensitivity analysis (D.O.E.) based on the fish hook maneuver, it was possible to identify thtat changes on springs, shock absorbers and stabilizer bar are able to mitigate the undesirable effects caused by the increase of unsprung mass.