No description available.

No description available.

For decades vehicle control has been extensively studied to investigate and improve vehicle stability and performance. Such controllers are designed to improve driving safety while the driver is still in control of the vehicle. It is known that human drivers are capable to learn and adapt to their built-in vehicle controller in order to improve their control actions based on their past driving experiences with the same vehicle controller. Although the learning curve varies for different human drivers, it results in a more constructive cooperation between the human driver and the computer-based vehicle controller, leading to globally optimal vehicle stability. The main intent of this research is to develop a novel cooperative interaction model between the human driver and vehicle controller in order to obtain globally optimal vehicle steering and lateral control. Considering the vehicle driver-controller interactions as a common two-player game problem where both players attempt to improve their payoffs, i.e., minimize their objective functions, the Game Theory approach is applied to obtain the optimal driver's steering inputs and controller's corrective yaw moment. Extending this interaction model to include more realistic scenarios, the model is discretized and a road preview model is added to account for the driver's preview-time characteristic. Also, a robust interaction model is developed to stabilize the vehicle performance while taking bounded uncertainty effects in driver's steering behavior into consideration using the Integral Sliding Mode control methodology. For evaluation purposes, a nonlinear vehicle dynamics model is developed that captures nonlinear tire characteristics and includes driver steering controllability and vehicle speed control systems such as cruise control, differential braking, and anti-lock braking systems. A graphical user interface (GUI) is developed in MATLAB to ease the use of the vehicle model and hopefully encourage its widespread application in the future. Simulation results indicate that the proposed cooperative interaction model, which is the end-product of human driver's and vehicle controller's mutual understanding of each other's objective and performance quality, results in more optimal and stable vehicle performance in lateral and yaw motions compared to the existing LQR controllers that tend to independently optimize the driver and vehicle controller inputs. / Ph. D.

The focus of Location-Aware Adaptive Vehicle Dynamics System (LAAVDS) research is to develop a system to avoid situations in which the vehicle exceeds its handling capabilities. The proposed method is predictive, estimating the ability of the vehicle to successfully navigate upcoming terrain, and it is assumed that the future vehicle states and local driving environment is known. An Intervention Strategy must be developed such that the vehicle is navigated successfully along a road via modest changes to the driver's commands and do so in a manner that is in harmony with the driver's intentions and not in a distracting or irritating manner. Clearly this research relies on the numerous new technologies being developed to capture and convey information about the local driving environment (e.g., bank angle, elevation changes, curvature, and friction coefficient) to the vehicle and driver. / Ph. D.

The vertical load on a moving tire was estimated by using accelerometers attached to the inner liner of a tire. The acceleration signal was processed to obtain the contact patch length created by the tire on the road surface. Then an appropriate equation relating the patch length to the vertical load is used to calculate the load. In order to obtain the needed data, tests were performed on a flat-track test machine at the Goodyear Innovation Center in Akron, Ohio; tests were also conducted on the road using a trailer setup at the Intelligent Transportation Laboratory in Danville, Virginia. During the tests, a number of different loads were applied; the tire-wheel setup was run at different speeds with the tire inflated to two different pressures. Tests were also conducted with a camber applied to the wheel. An algorithm was developed to estimate load using the collected data. It was then shown how the estimated load could be used in a control algorithm that applies a suitable control input to maintain the yaw stability of a moving vehicle. A two degree of freedom bicycle model was used for developing the control strategy. A linear quadratic regulator (LQR) was designed for the purpose of controlling the yaw rate and maintaining vehicle stability. / Master of Science

Capturing what is going on and what may happen related to vehicle handling behaviour in cases of desired or non-desired actions and interventions has a crucial importance. Strategies implemented to improve vehicle stability or algorithms and control modules designed to compensate the non-desired effects on handling behavior may appear to be inadequate as the vehicle goes through uncountable experiences. The importance of understanding and introducing the possible sources of undesired effects which may be encountered throughout driving action cannot be underemphasized. One of the possibilities that may lead the driver face with unexpected results concerning vehicle&rsquo / s handling is suspension damper failure, which has not yet been dealt with adequately in the literature. The fast developing technology and consequently the expanding utilization of chassis electronics and electronic vehicle components make the investigation of damper failure phenomenon essential since reliability decreases by the continuously increasing introduction of electronic means. In this study, possible failure types of dampers including electrical failure are taken into account, their effects on vehicle stability under critical driving conditions are examined. Shortcomings and comments are made on criticality of failed damper and its failure point. This work as a result, constitutes a particular contribution to the literature in that it brings up a concrete knowledge to the stated research area.

No description available.

It is possible to obtain information about the stability conditions of a vehicle by observing and comparing existing signals involved in the rotational motion of the vehicle around the vertical axis. Accurate information about the current state of a vehicle is critical for the development and function of new active safety features in a vehicle. Therefore, the goal of this thesis is to create a new signal based on already existing signals from the vehicle electronic control unit for detecting understeering and oversteering of a vehicle. The signal should consider all the factors that affect the evaluation of the vehicle´s stability conditions. The results show that the developed signal can, in certain conditions, detect understeering and oversteering. Issues arise in situations such as banked curves or low-mu surfaces. In those cases, the signal is not fully able to describe the vehicle behavior.

A crescente preocupação ambiental e a necessidade de se criar produtos mais eficientes têm impulsionado os pesquisadores a realizarem estudos acerca da aerodinâmica veicular. Estes dois fatores constituem os principais motivos, pelos quais existe uma grande procura por conhecimento nesta área. Esta ciência pode ser considerada relativamente nova e ainda carece de uma base de dados. Entender como a aerodinâmica se relaciona com o consumo de combustível nos automóveis, à medida que o arrasto impõe resistência ao deslocamento dos mesmos, é algo que tem estimulado as indústrias automotivas a investirem grandes esforços na obtenção de ferramentas, que possam representar as condições de tráfego normais e, assim conseguir prever o desempenho do produto em desenvolvimento. Os túneis de vento e a simulação computacional surgem neste ambiente como as principais ferramentas de análise e predição do escoamento ao redor do veículo. Por isso seu entendimento faz-se de extrema necessidade. Ter conhecimento sobre a concepção do seu projeto, como funcionam, seus pontos fortes e suas fraquezas, são requisitos necessários para a pessoa que deseja estudar esta ciência. O presente trabalho traz uma contextualização histórica da aerodinâmica veicular nas indústrias automotiva e automobilística, além de apresentar aspectos técnicos relacionados aos túneis de vento e simulação computacional. Abordando as vantagens e desvantagens de cada ferramenta, expõe-se o fato de que estas ferramentas são complementares no estudo aerodinâmico. Para exemplificar a utilização dessas ferramentas, foi realizado um estudo aerodinâmico sobre uma geometria básica, que representa com similaridade os veículos tipo hatchback, denominada Modelo SAE em ambiente computacional. Os conceitos acerca do arrasto veicular e estabilidade veicular foram expostos para embasar este estudo. Este modelo foi submetido a diferentes geometrias traseiras e condições de escoamento simétricas e assimétricas. Este estudo demonstrou que o arrasto e a estabilidade veicular compreendem conceitos distintos e, dessa forma, é possível diminuir o arrasto de um veículo sem haver perda de estabilidade. / The growing environmental concern and the necessity to create more efficient products have motivated researchers to conduct studies about the aerodynamic vehicle. These two aspects are the main reasons which are promoting a great demand for knowledge in this theme. This science may be considered relatively new and still lacks more databases. Understand how aerodynamics is related to automobiles fuel consumption such as drag resistance imposed to their displacement, is something that has made the automotive industries invest considerable effort in obtaining tools which may represent the normal traffic conditions and thus, able to predict the performance of the product in development stage. The wind tunnels and computer simulations appear in this environment as the main tools for analysis and prediction of the flow around vehicle. The understanding about them is so of utmost necessity. Knowing how it was designed, how they work, their strengths and weaknesses are essential requirements for the person who wants to study this science. This material presents a historical development of vehicle aerodynamics in automotive and motor-racing industries, indeed technical aspects related to wind tunnels and computational fluid dynamics. Exposing the advantages and disadvantages of both tools, it is evidenced these tools complement each other during an aerodynamic study. To exemplify these tools utility an aerodynamic research was conducted using a basic form geometry known as SAE Model that represents with similarity the hatchback vehicles in the market. Drag and vehicle stability concepts were exposed to build a solid basis for this study. This model was submitted to different rear geometries, symmetric and asymmetric flow conditions. It could be demonstrated that drag and vehicle stability have distinct concepts and therefore it is possible diminish the first without damaging the later.

Les véhicules modernes sont de plus en plus équipés de nouveaux organes visant à améliorer la sécurité des occupants. Ces nouveaux systèmes sont souvent des organes actifs utilisant des données de capteurs sur le véhicule. Cependant, en cas de mauvais fonctionnement d'un capteur, les conséquences pour le véhicule peuvent être dramatiques. Afin de garantir la sécurité dans le véhicule, des nouvelles méthodologies de détections de défauts adaptées pour les véhicules sont proposées. Les méthodologies présentées sont étendues de la méthode de l'espace de parité pour les systèmes à paramètres variant (LPV). En outre, la transformation du problème de détection de défauts pour la détection de situations critiques est également proposée. Des résultats applicatifs réalisés sur un véhicule réel dans le cadre du projet INOVE illustrent les performances des détections de défauts et la détection de perte de stabilité du véhicule. / Modern vehicles are increasingly equipped with new mechanisms to improve occupant safety. These new systems are often active parts using data from sensors on the vehicle. However, in case of malfunction of a sensor, the consequences for the vehicle can be dramatic. To ensure safety in the vehicle, new methodologies for detection of faults suitable for vehicles are proposed. The developed methodologies are extended from the method of parity space for linear parameter varying systems (LPV). In addition, the transformation of fault detection problem for the detection of critical situations is also available. Application of results achieved on a real vehicle within the INOVE project illustrate the performance of fault detection and detection of loss of stability of the vehicle.