[pt] A sub-divisão de um veículo em módulos é muito útil quando se quer estudar o comportamento dinâmico de um determinado subsistema e sua influência nos demais componentes. Em alguns casos, devido ao tipo de tratamento empregado para descrever os elementos, não se consegue perceber de que modo as variáveis inerentes a um subsistema interagem com as demais, e, por conseguinte, os subsistemas entre si. A abordagem modular baseada no fluxo de potência permite uma melhor identificação das relações de causa e efeito entre subsistemas, uma vez que se pode definir, de forma clara e consistente, quem são as variáveis de entrada e de saída de cada componente ou módulo, e, conseqüentemente, seus acoplamentos. Neste tipo de tratamento, aplicado aos sistemas mecânicos, uma vez estabelecida a cinemática de um subsistema, podese obter as relações entre os esforços que seus componentes produzem uns sobre os outros, a partir da caracterização da potência transmitida através dos seus diversos elementos. Este trabalho apresenta um procedimento semi-analítico de equacionamento modular aplicado à modelagem e integração dos sistemas de suspensão e direção de veículos terrestres, no qual as variáveis de entrada e saída indicam o fluxo de potência entre os elementos de todo o sistema. Tal abordagem tem como base a técnica dos Grafos de Ligação, empregada em sistemas multidomínio em geral, e usa alguns conceitos da metodologia dos Transformadores Cinemáticos, normalmente aplicada aos sistemas multicorpos. A partir da definição da geometria dos mecanismos em questão, encontram-se as matrizes que representam os vínculos cinemáticos entre seus elementos, das quais o funcionamento dos sistemas integrados pode ser simulado e analisado, e informações necessárias aos seus projetos determinadas. As equações (malhas) algébricas que existem em mecanismos com estrutura cinemática fechada são analiticamente resolvidas, evitando deste modo modelos matemáticos com equações diferenciais e algébricas simultâneas. Das relações cinemáticas, o modelo dinâmico (matrizes de inércia, rigidez e amortecimento, etc) é obtido, e novamente informações essenciais à análise e síntese dos sistemas podem ser determinadas. O comportamento no tempo desses modelos pode ser encontrado por um método de integração de equações diferenciais qualquer. Adota-se o Simulink/MatLab® para representar o modelo assim desenvolvido em diagrama de blocos, e conseqüentemente simulá-lo. Através deste tratamento, cada bloco da implementaçao em Simulink/MatLab® contém o correspondente modelo analítico de um único módulo, cujo estabelecimento depende das características dinâmicas do sistema que se deseja analisar. A vantagem de adotar tal representação, baseada no fluxo de potência, consiste no fato de que um módulo pode ser substituído por outro, descritivo de um elemento ou subsistema com a mesma função, porém com configuração física distinta, e, conseqüentemente, modelo matemático específico, sem qualquer alteração nos demais componentes do sistema. Este procedimento está sendo adotado para modelagem dos diversos sistemas veiculares, como os de suspensão, direção, transmissão e freios, e também os pneus, inseridos em um chassi, incluindo os graus de liberdade desejados do veículo, todos descritos de forma modular semi- analítica através da mesma abordagem, empregando a técnica de modelagem mais apropriada para representá-los. / [en] The sub-division of a vehicle in modules is very useful when we want to study the dynamical behavior of a certain sub-system and its influence in other components. In some cases, due to the type of treatment employed to describe the dynamic behavior of the elements, we don`t get to notice the way that inherent variables in a sub-system interacts with the others, and, consequently, the subsystems amongst themselves. The modular approach based on the power flow allows a better identification of the causal relationships among sub-systems, once it can define, in clear and consistent way, what are the input and output variables of each component or module, and, consequently, their couplings. In this type of treatment applied to the mechanical systems, once established the kinematics of a sub-system, it can be obtained the relationships among the efforts that their components produce on the other ones, from the characterization of the power transmitted through their several elements. This paper presents a semi-analytical procedure of modular modeling applied to the suspension and steering systems of a ground vehicle, in which the input and output variables indicate the power flow among the elements of the whole system. Such approach has as base the Bond Graphs technique, used in multidomain systems in general, and uses some concepts of the Kinematic Transformers methodology, usually applied to the multibody systems. From the mechanisms geometry, the matrices that represent the kinematics links between its elements are found, the operation of the integrated systems can be simulated and analyzed, and information about its design can be obtained. The algebraic loops (equations) inherent to mechanisms with closed kinematic structure are solved analytically, and there is not a mathematical model with simultaneous algebraic and differential equations. From the kinematic relations, the dynamic model (inertial, stiffness and damping matrices) is obtained, and again essential information to the systems analysis and synthesis can be determined. The models time behavior can be found by any differential equations integration method. The Simulink/Matlab is adopted to represent the model developed by block diagrams, and consequently to simulate it. Through this treatment, each block in the Simulink/Matlab implementation contains the correspondent analytical model of a single module, whose establishment depends on the dynamic characteristics of the system to be analyzed. The advantage of adopting such representation, based on the power flow, consists in the fact that a module can be substituted for other, descriptive of an element or sub-system with the same function, however with different physical configuration, and, consequently, specific mathematical model, without any alteration in the other components of the system. This procedure is being adopted for modeling all vehicular systems, like the suspension, steering, transmission and brakes systems, and also the tires, inserted in the chassis, including the desired degrees of freedom of the vehicle, all described in a semi- analytical modular way by the same approach, using the most appropriate modeling technique to represent them.

[pt] O presente trabalho apresenta um conceito para um sistema de evasão de colisões, simulado usando modelos 3D de três veículos diferentes implementados em MATLAB. Dois destes veículos foram parametrizados com dados genéricos, caracterizando automóveis de médio e grande porte. Em seguida, utilizados para realização de simulações iniciais e demonstração de conceitos. O terceiro conjunto de dados foi construído com informações do Apollo N, um veículo super esportivo. Estes diferentes conjuntos de dados foram utilizados para avaliar a capacidade do controlador de trabalhar com veículos de diferentes portes e dinâmicas de direção. A abordagem para acionar o sistema baseia-se no cálculo do tempo para a colisão (TTC; timeto- collision). O conceito foi adotado para detectar situações onde o motorista não é capaz de evitar um acidente. Depois de ser acionado, o sistema deve decidir qual manobra é a mais apropriada, dadas as condições de aderência da pista e o risco associado. O primeiro objetivo deste trabalho é desenvolver um sistema autônomo de frenagem que deve ser capaz de avaliar o risco de uma possível colisão e decidir se o condutor é capaz de evitá-la. Uma vez que o motorista não tenha tempo suficiente para reagir, o sistema deve acionar os freios automaticamente a fim de evitar um possível acidente. Além disso, o veículo possui um sistema anti-travamento (ABS), desenvolvido usando controle Fuzzy. O desempenho do controlador ABS foi avaliado em simulações usando os conjuntos de dados e testado em um veículo em escala. Em casos mais críticos, quando há baixa aderência, o veículo não é capaz de frear em uma distância razoável. Levando-se em consideração tal situação, um controle autônomo de esterçamento também foi desenvolvido, visando a possibilidade de uma manobra alternativa de evasão. Este segundo sistema foi avaliado em simulações utilizando veículos com características subesterçantes e sobreesterçantes. Os resultados mostraram que o controle de esterçamento foi capaz de realizar manobras evasivas produzindo valores razoáveis de acelerações laterais, em veículos com diferentes dinâmicas de direção. / [en] This work presents a concept for a collision avoidance system simulated using 3D-models of three different vehicles implemented in MATLAB. Two of the vehicle data sets were built with generic information, used to characterize mid-size and full-size vehicles. These standard vehicles were used in initial simulations and for demonstration of some concepts. The third data set was built with information from the Apollo N, a super sportive car. These different data sets were used to evaluate the controller s capacity to work with a range of vehicles, with different sizes and driving characteristics. The approach for triggering the system is based on the time-to-colision (TTC) estimation. This concept was adopted to recognize when the driver is not able to avoid an accident. After being triggered, the system must decide which maneuver is the most appropriate for the given friction and risk conditions. The first goal of this work is to develop an autonomous braking system which evaluates the risk of a possible collision and decides if the driver is able to avoid it. Once the driver has not enough time to react, the system must trigger the brakes automatically in order to avoid the accident. The vehicle is equipped with an embedded Anti-lock Brake System (ABS) developed using Fuzzy control. The ABS controller s performance was evaluated in simulations using the data sets and tested in a scaled vehicle. In more critical cases, when there is low friction, the vehicle is not able to brake in a reasonable distance. Considering this situation, an autonomous steering control was implemented in order to make an alternative avoidance maneuver. This second system was evaluated in simulations using vehicles with understeering and oversteering characteristics. The results pointed out that the autonomous steering control was able to perform avoidance maneuvers in a reasonable range of lateral accelerations, in vehicles with different driving tendencies. / [de] Die vorliegende Arbeit prasentiert ein Konzept fur ein Kollisionsvermeidungssystem. Dieses wird anhand von drei verschiedenen 3DFahrzeugmodellen mit Hilfe von MATLAB simuliert. Zwei der FahrzeugDatensatze basieren auf generischen Informationen, die jeweils ein Automobil der Mittelklasse und der Oberklasse reprasentieren. Diese Standardfahrzeuge wurden fur anfangliche Simulationen und zur Demonstration einiger Konzepte verwendet. Das dritte Fahrzeugmodell wurde mit Hilfe der Daten des Sportwagens Apollo N aufgebaut. Durch die Verwendung der verschiedenen Datensatze soll die Funktionsfahigkeit der Regelung auch bei verschiedenen Fahrzeugtypen mit unterschiedlichen Dimensionen und Fahreigenschaften uberpruft werden.Die Grundlage zum Auslosen des Systems ist die Abschatzung der Zeit bis zur Kollision (TTC; time-to-collision). Dieses Konzept wurde aufgegriffen, um zu entscheiden, wann der Fahrer nicht mehr in der Lage ist einen Unfall zu vermeiden. Nachdem das System ausgelost wird muss dieses anhand der Traktionsverhaltnisse und Gefahrensituation entscheiden, welches Manover am besten geeignet ist. Das erste Teilziel ist die Entwicklung eines autonomen Bremssystems, welches eine bevorstehende Kollision erkennen muss und entscheidet ob der Fahrer die Kollision eigenstandig vermeiden kann. Sobald der Fahrer nicht mehr genug Zeit hat selbst zu reagieren, muss das System die Bremsen automatisch betatigen um den Unfall zu vermeiden. Hierzu ist das Fahrzeug mit einem Antiblockiersystem (ABS) ausgestattet. Dieses wurde mit Hilfe eines Fuzzy-Kontrollers realisiert. Die Funktionstuchtigkeit der ABS-Regelung wurde mit Simulationen und anhand eines realen, skalierten Fahrzeugmodells getestet. In kritischen Situationen, kann es aufgrund der Traktionsverhaltnisse vorkommen, dass das Fahrzeug nicht mehr in der Lage ist innerhalb einer ausreichenden Strecke zum Stehen zu kommen. Um fur solche Situationen ein alternatives Ausweichmanöver anwenden zu konnen, wurde ein automatischer Lenkeingriff implementiert. Dieses System wurde anhand von Simulationen an Fahrzeugmodellen mit Ubersteuernden und Untersteuernden Eigenschaften uberprüft. Die Ergebnisse zeigten, dass die automatische Lenkeingriff-Regelung in der Lage war auch bei Fahrzeugen mit unterschiedlichen Fahreigenschaften Ausweichmanöver unter Einhaltung angemessener Querbeschleunigungen durchzufuhren.

[pt] Modelagem e Controle Não Linear de um Veículo Terrestre sobre Suspensão descreve um estudo em dinâmica veicular no qual inicialmente apresenta-se um modelo analítico para representar a geração de forças longitudinais e laterais no contato do pneu com o solo. Em seguida é desenvolvido, para um automóvel de passeio terrestre sobre suspensão, um modelo não linear de 4 graus de liberdade (velocidades longitudinal, lateral, de guinada e de rolagem), e a sua linearização. Expande-se esse modelo para um de 8 graus de liberdade, no qual inclui-se o movimento de rotação axial de cada uma das quatro rodas, e consideram-se os movimentos do veículo somente no plano, sem efeitos de pitch ou bounce, mas apresentando alguma relação de distribuição de cargas devido ao roll. Descrevem-se ainda modelos em Grafos de Ligação para os três dinâmicas de um veículo terrestre (longitudinal, lateral e vertical) e seus acoplamentos, visando futuras análises mais detalhadas desse sistema. Todos os modelos em malha aberta são validados através simulações computacionais em diversas condições típicas de operação. Na segunda parte desse trabalho é apresentada a estratégia proposta para o tratamento do problema de controle direcional do veículo em uma manobra qualquer, empregando a metodologia da linearização por realimentação, tendo como base o modelo linear de 4 graus de liberdade. São analisados os resultados encontrados através de simulação computacional para a malha fechada com diferentes combinações de parâmetros, empregando os modelos não lineares de 4 e 8 graus de liberdade. Conclui-se discutindo a possibilidade de generalização deste procedimento para diferentes aplicações em Dinâmica Veicular. / [en] Modeling and Non Linear Control of a Ground Vehicle's Steering describles a study in vehicle dynamics, which presents an analytic model representing the generation of longitudinal and lateral forces at the contact patch between tire and ground. Next it is developed, for a typical passenger car, a non-linear model with four degrees of freedom (longitudinal, lateral, yaw and roll velocities), and its linearization. This model is then expanded to another one with eight degrees of freedom, which includes the axial rotation of each one of the four wheels, and considers the vehicle's movement only at a known plane, whithoud pitch and bounce effects, but including some load distribution among the wheels, due to roll. Computational simulation in varius typical operation condition validate all open loop models. The second part of this work presents the proposed strategy for directional control of a vehicle at any type of manoeuvre, using the feedback linearization methodology, directly applied to the linear four degrees of freedom model. Theresults obtained trhough computational simulation for a closed loop model with different parameters are analysed using both nonlinear four and eight degrees of freedom models. The possibility of generalizing this procedure to distinct applications in Vehicle Dynamics is, then, discussed.

[pt] A crescente demanda por sistemas de transporte autônomos e inteligentes exige o desenvolvimento de técnicas avançadas de controle e estimativa, visando garantir operações seguras e eficientes. Devido à natureza não linear da dinâmica veicular e seus fenômenos característicos, os métodos clássicos de estimativa e controle podem não alcançar resultados adequados, o que incentiva a pesquisa de novos algoritmos. Por algumas contribuições, a primeira parte deste trabalho trata de algoritmos de estimação, tanto para identificação de parâmetros invariantes no tempo, quanto para estimação de estados e parâmetros variantes no tempo. Especial destaque é dados aos algoritmos de Estimação de Estados por Horizonte Móvel (MHSE), que se apresenta como robusto e preciso, devido ao problema de otimização com restrição em que se baseia. Este algoritmo é avaliado em dinâmica longitudinal de veículos, para estimativa de deslizamento longitudinal e coeficiente de atrito pneu-estrada. Apesar de sua eficiência, o alto custo computacional torna necessária a busca por alternativas sub-ótimas, e o emprego de Redes Neurais que mapeiam os resultados da otimização é uma solução promissora, que é tratada como Estimação por Horizonte Móvel com Redes Neurais (NNMHE). O NNMHE é avaliado em uma estimativa do estado de carga (SOC) de baterias para veículos elétricos, demonstrando, através de dados experimentais, que o NNMHE emula com precisão o problema de otimização e a literatura indica sua aplicação efetiva em hardwares embarcados. Por fim, é apresentada uma contribuição sobre o controle preditivo baseado em modelo não linear (NMPC). É proposto e avaliado seu uso compondo uma nova estrutura de controle hierárquica para veículos elétricos com motores independentes nas rodas, através do qual é possível controlar adequadamente o veículo em tarefas de rastreamento de velocidade e trajetória, com reduzido esforço computacional. O controle é avaliado usando dados experimentais de pneus obtidos, que aproximam a simulação de situações reais. / [en] The rising demand of autonomous and intelligent transportation systems requires the development of advanced control and estimation techniques, aiming to ensure safety and efficient operations. Due to the nonlinear nature of vehicle dynamics and its characteristic phenomena, classical estimation and control methods may not achieve adequate results, which encourages the research of novel algorithms. By some contributions, the first part of this work deals with estimation algorithms, both for identification of time invariant parameters and for estimation of states and time varying parameters. Special emphasis is given to Moving-Horizon State Estimation (MHSE), which is presented to be robust and accurate, due to the constrained optimization problem on which it is based. This algorithm is evaluated in vehicle longitudinal dynamics, for slip and tire-road friction estimation. Despite its efficiency, the high computational cost makes it necessary to search for suboptimal alternatives, and the employ of a Neural Networks that maps the optimization results is a promising solution, which is treated as Neural Networks Moving-Horizon Estimation (NNMHE). The NNMHE is evaluated on a state-of-charge (SOC) estimation of batteries for electric vehicles, demonstrating, through experimental data, that the NNMHE emulates accurately the optimization problem, and the literature indicates its effectively application on embedded hardware. Finally, a contribution about Nonlinear Model-based Predictive Control (NMPC) is presented. It is proposed and evaluated its use compounding a novel hierarchical control framework for electric vehicles with independent in-wheel motors, through which it is possible to adequately control the vehicle on velocity and path tracking tasks, with reduced computational effort. The control is evaluated using experimental obtained tire data, which approaches the simulation to real situations.

[pt] Os veículos automatizados devem trafegar em determinado ambiente detectando, planejando e seguindo uma trajetória segura. De modo a se mostrarem mais seguros que seres humanos, eles devem ser capazes de executar essas tarefas tão bem ou melhor do que motoristas humanos sob diferentes condições críticas. Uma parte essencial no estudo de veículos automatizados o desenvolvimento de modelos representativos que sejam precisos e computacionalmente eficientes. Assim, para lidar com esses problemas, o presente trabalho aplica métodos de inteligência computational e identificação de sistemas para realizar modelagem de veículos e controle de rastreamento de trajetória. Primeiro, arquiteturas neurais são usadas para capturar as características do pneu na interação entre a dinâmica lateral e longitudinal do veículo, reduzindo o custo computacional em controladores preditivos. Em segundo lugar, uma combinação de modelos caixa-preta é usada para melhorar o controle preditivo. Em seguida, uma abordagem híbrida combina modelos baseados na física e orientados por dados com modelagem de caixa-preta das discrepâncias. Essa abordagem é escolhida para melhorar a precisão da modelagem de veículos, propondo um modelo de discrepância para capturar incompatibilidades entre modelos de veículos e dados medidos. Os resultados são mostrados quando os métodos propostos são aplicados a sistemas com dados simulados/reais e comparados com abordagens encontradas na literatura, mostrando um aumento de precisão (até 40 por cento) em termos de métricas baseadas em erro, com menor esforço computacional (redução de até 88 por cento) do que os controladores preditivos convencionais. / [en] Automated vehicles must travel in a given environment detecting, planning, and following a safe path. In order to be safer than humans, they must be able to perform these tasks as well or better than human drivers under different critical conditions. An essential part of the study of automated vehicles is the development of representative models that are accurate and computationally efficient. Thus, to cope with these problems, the present work applies artificial neural networks and system identification methods to perform vehicle modeling and trajectory tracking control. First, neural architectures are used to capture tire characteristics present in the interaction between lateral and longitudinal vehicle dynamics, reducing computational costs for predictive controllers. Secondly, a combination of black-box models is used to improve predictive control. Then, a hybrid approach combines physics-based and data-driven models with black-box modeling of the discrepancies. This approach is chosen to improve the accuracy of vehicle modeling by proposing a discrepancy model to capture mismatches between vehicle models and measured data. Results are shown when the proposed methods are applied to systems with simulated/real data and compared with approaches found in the literature, showing an increase of accuracy (up to 40 percent) in terms of error-based metrics while having lesser computational effort (reduction by up to 88 percent) than conventional predictive controllers.

The thesis is composed of two main parts. The first part deals with a microscopic traffic flow theory. Models describing the individual acceleration, deceleration and lane-changing behavior are formulated and the emerging collective traffic dynamics are investigated by means of numerical simulations. The models and simulation tools presented provide the methodical prerequisites for the second part of the thesis in which a novel concept of a traffic-adaptive control strategy for ACC systems is presented. The impact of such systems on the traffic dynamics can solely be investigated and assessed by traffic simulations. The focus is on future adaptive cruise control (ACC) systems and their potential applications in the context of vehicle-based intelligent transportation systems. In order to ensure that ACC systems are implemented in ways that improve rather than degrade traffic conditions, the thesis proposes an extension of ACC systems towards traffic-adaptive cruise control by means of implementing an actively jam-avoiding driving strategy. The newly developed traffic assistance system introduces a driving strategy layer which modifies the driver's individual settings of the ACC driving parameters depending on the local traffic situation. Whilst the conventional operational control layer of an ACC system calculates the response to the input sensor data in terms of accelerations and decelerations on a short time scale, the automated adaptation of the ACC driving parameters happens on a somewhat longer time scale of, typically, minutes. By changing only temporarily the comfortable parameter settings of the ACC system in specific traffic situations, the driving strategy is capable of improving the traffic flow efficiency whilst retaining the comfort for the driver. The traffic-adaptive modifications are specified relative to the driver settings in order to maintain the individual preferences. The proposed system requires an autonomous real-time detection of the five traffic states by each ACC-equipped vehicle. The formulated algorithm is based on the evaluation of the locally available data such as the vehicle's velocity time series and its geo-referenced position (GPS) in conjunction with a digital map. It is assumed that the digital map is complemented by information about stationary bottlenecks as most of the observed traffic flow breakdowns occur at these fixed locations. By means of a heuristic, the algorithm determines which of the five traffic states mentioned above applies best to the actual traffic situation. Optionally, inter-vehicle and infrastructure-to-car communication technologies can be used to further improve the accuracy of determining the respective traffic state by providing non-local information. By means of simulation, we found that the automatic traffic-adaptive driving strategy improves traffic stability and increases the effective road capacity. Depending on the fraction of ACC vehicles, the driving strategy "passing a bottleneck" effects a reduction of the bottleneck strength and therefore delays (or even prevents) the breakdown of traffic flow. Changing to the driving mode "leaving the traffic jam" increases the outflow from congestion resulting in reduced queue lengths in congested traffic and, consequently, a faster recovery to free flow conditions. The current travel time (as most important criterion for road users) and the cumulated travel time (as an indicator of the system performance) are used to evaluate the impact on the quality of service. While traffic congestion in the reference scenario was completely eliminated when simulating a proportion of 25% ACC vehicles, travel times were significantly reduced even with much lower penetration rates. Moreover, the cumulated travel times decreased consistently with the increase in the proportion of ACC vehicles. / In der Arbeit wird ein neues verkehrstelematisches Konzept für ein verkehrseffizientes Fahrverhalten entwickelt und als dezentrale Strategie zur Vermeidung und Auflösung von Verkehrsstaus auf Richtungsfahrbahnen vorgestellt. Die operative Umsetzung erfolgt durch ein ACC-System, das um eine, auf Informationen über die lokale Verkehrssituation basierende, automatisierte Fahrstrategie erweitert wird. Die Herausforderung bei einem Eingriff in das individuelle Fahrverhalten besteht - unter Berücksichtigung von Sicherheits-, Akzeptanz- und rechtlichen Aspekten - im Ausgleich der Gegensätze Fahrkomfort und Verkehrseffizienz. Während sich ein komfortables Fahren durch große Abstände bei geringen Fahrzeugbeschleunigungen auszeichnet, erfordert ein verkehrsoptimierendes Verhalten kleinere Abstände und eine schnellere Anpassung an Geschwindigkeitsänderungen der umgebenden Fahrzeuge. Als allgemeiner Lösungsansatz wird eine verkehrsadaptive Fahrstrategie vorgeschlagen, die ein ACC-System mittels Anpassung der das Fahrverhalten charakterisierenden Parameter umsetzt. Die Wahl der Parameter erfolgt in Abhängigkeit von der lokalen Verkehrssituation, die auf der Basis der im Fahrzeug zur Verfügung stehenden Informationen automatisch detektiert wird. Durch die Unterscheidung verschiedener Verkehrssituationen wird ein temporärer Wechsel in ein verkehrseffizientes Fahrregime (zum Beispiel beim Herausfahren aus einem Stau) ermöglicht. Machbarkeit und Wirkungspotenzial der verkehrsadaptiven Fahrstrategie werden im Rahmen eines mikroskopischen Modellierungsansatzes simuliert und hinsichtlich der kollektiven Verkehrsdynamik, insbesondere der Stauentstehung und Stauauflösung, auf mehrspurigen Richtungsfahrbahnen bewertet. Die durchgeführte Modellbildung, insbesondere die Formulierung eines komplexen Modells des menschlichen Fahrverhaltens, ermöglicht eine detaillierte Analyse der im Verkehr relevanten kollektiven Stabilität und einer von der Stabilität abhängigen stochastischen Streckenkapazität. Ein tieferes Verständnis der Stauentstehung und -ausbildung wird durch das allgemeine Konzept der Engstelle erreicht. Dieses findet auch bei der Entwicklung der Strategie für ein stauvermeidendes Fahrverhalten Anwendung. In der Arbeit wird die stauvermeidende und stauauflösende Wirkung eines individuellen, verkehrsadaptiven Fahrverhaltens bereits für geringe Ausstattungsgrade nachgewiesen. Vor dem Hintergrund einer zu erwartenden Verbreitung von ACC-Systemen ergibt sich damit eine vielversprechende Option für die Steigerung der Verkehrsleistung durch ein teilautomatisiertes Fahren. Der entwickelte Ansatz einer verkehrsadaptiven Fahrstrategie ist unabhängig vom ACC-System. Er erweitert dessen Funktionalität im Hinblick auf zukünftige, informationsbasierte Fahrerassistenzsysteme um eine neue fahrstrategische Dimension. Die lokale Interpretation der Verkehrssituation kann neben einer verkehrsadaptiven ACC-Regelung auch der Entwicklung zukünftiger Fahrerinformationssysteme dienen.

The thesis is composed of two main parts. The first part deals with a microscopic traffic flow theory. Models describing the individual acceleration, deceleration and lane-changing behavior are formulated and the emerging collective traffic dynamics are investigated by means of numerical simulations. The models and simulation tools presented provide the methodical prerequisites for the second part of the thesis in which a novel concept of a traffic-adaptive control strategy for ACC systems is presented. The impact of such systems on the traffic dynamics can solely be investigated and assessed by traffic simulations. The focus is on future adaptive cruise control (ACC) systems and their potential applications in the context of vehicle-based intelligent transportation systems. In order to ensure that ACC systems are implemented in ways that improve rather than degrade traffic conditions, the thesis proposes an extension of ACC systems towards traffic-adaptive cruise control by means of implementing an actively jam-avoiding driving strategy. The newly developed traffic assistance system introduces a driving strategy layer which modifies the driver's individual settings of the ACC driving parameters depending on the local traffic situation. Whilst the conventional operational control layer of an ACC system calculates the response to the input sensor data in terms of accelerations and decelerations on a short time scale, the automated adaptation of the ACC driving parameters happens on a somewhat longer time scale of, typically, minutes. By changing only temporarily the comfortable parameter settings of the ACC system in specific traffic situations, the driving strategy is capable of improving the traffic flow efficiency whilst retaining the comfort for the driver. The traffic-adaptive modifications are specified relative to the driver settings in order to maintain the individual preferences. The proposed system requires an autonomous real-time detection of the five traffic states by each ACC-equipped vehicle. The formulated algorithm is based on the evaluation of the locally available data such as the vehicle's velocity time series and its geo-referenced position (GPS) in conjunction with a digital map. It is assumed that the digital map is complemented by information about stationary bottlenecks as most of the observed traffic flow breakdowns occur at these fixed locations. By means of a heuristic, the algorithm determines which of the five traffic states mentioned above applies best to the actual traffic situation. Optionally, inter-vehicle and infrastructure-to-car communication technologies can be used to further improve the accuracy of determining the respective traffic state by providing non-local information. By means of simulation, we found that the automatic traffic-adaptive driving strategy improves traffic stability and increases the effective road capacity. Depending on the fraction of ACC vehicles, the driving strategy "passing a bottleneck" effects a reduction of the bottleneck strength and therefore delays (or even prevents) the breakdown of traffic flow. Changing to the driving mode "leaving the traffic jam" increases the outflow from congestion resulting in reduced queue lengths in congested traffic and, consequently, a faster recovery to free flow conditions. The current travel time (as most important criterion for road users) and the cumulated travel time (as an indicator of the system performance) are used to evaluate the impact on the quality of service. While traffic congestion in the reference scenario was completely eliminated when simulating a proportion of 25% ACC vehicles, travel times were significantly reduced even with much lower penetration rates. Moreover, the cumulated travel times decreased consistently with the increase in the proportion of ACC vehicles. / In der Arbeit wird ein neues verkehrstelematisches Konzept für ein verkehrseffizientes Fahrverhalten entwickelt und als dezentrale Strategie zur Vermeidung und Auflösung von Verkehrsstaus auf Richtungsfahrbahnen vorgestellt. Die operative Umsetzung erfolgt durch ein ACC-System, das um eine, auf Informationen über die lokale Verkehrssituation basierende, automatisierte Fahrstrategie erweitert wird. Die Herausforderung bei einem Eingriff in das individuelle Fahrverhalten besteht - unter Berücksichtigung von Sicherheits-, Akzeptanz- und rechtlichen Aspekten - im Ausgleich der Gegensätze Fahrkomfort und Verkehrseffizienz. Während sich ein komfortables Fahren durch große Abstände bei geringen Fahrzeugbeschleunigungen auszeichnet, erfordert ein verkehrsoptimierendes Verhalten kleinere Abstände und eine schnellere Anpassung an Geschwindigkeitsänderungen der umgebenden Fahrzeuge. Als allgemeiner Lösungsansatz wird eine verkehrsadaptive Fahrstrategie vorgeschlagen, die ein ACC-System mittels Anpassung der das Fahrverhalten charakterisierenden Parameter umsetzt. Die Wahl der Parameter erfolgt in Abhängigkeit von der lokalen Verkehrssituation, die auf der Basis der im Fahrzeug zur Verfügung stehenden Informationen automatisch detektiert wird. Durch die Unterscheidung verschiedener Verkehrssituationen wird ein temporärer Wechsel in ein verkehrseffizientes Fahrregime (zum Beispiel beim Herausfahren aus einem Stau) ermöglicht. Machbarkeit und Wirkungspotenzial der verkehrsadaptiven Fahrstrategie werden im Rahmen eines mikroskopischen Modellierungsansatzes simuliert und hinsichtlich der kollektiven Verkehrsdynamik, insbesondere der Stauentstehung und Stauauflösung, auf mehrspurigen Richtungsfahrbahnen bewertet. Die durchgeführte Modellbildung, insbesondere die Formulierung eines komplexen Modells des menschlichen Fahrverhaltens, ermöglicht eine detaillierte Analyse der im Verkehr relevanten kollektiven Stabilität und einer von der Stabilität abhängigen stochastischen Streckenkapazität. Ein tieferes Verständnis der Stauentstehung und -ausbildung wird durch das allgemeine Konzept der Engstelle erreicht. Dieses findet auch bei der Entwicklung der Strategie für ein stauvermeidendes Fahrverhalten Anwendung. In der Arbeit wird die stauvermeidende und stauauflösende Wirkung eines individuellen, verkehrsadaptiven Fahrverhaltens bereits für geringe Ausstattungsgrade nachgewiesen. Vor dem Hintergrund einer zu erwartenden Verbreitung von ACC-Systemen ergibt sich damit eine vielversprechende Option für die Steigerung der Verkehrsleistung durch ein teilautomatisiertes Fahren. Der entwickelte Ansatz einer verkehrsadaptiven Fahrstrategie ist unabhängig vom ACC-System. Er erweitert dessen Funktionalität im Hinblick auf zukünftige, informationsbasierte Fahrerassistenzsysteme um eine neue fahrstrategische Dimension. Die lokale Interpretation der Verkehrssituation kann neben einer verkehrsadaptiven ACC-Regelung auch der Entwicklung zukünftiger Fahrerinformationssysteme dienen.