Semi-active suspensions have drawn particular attention due to their superior performance over the other types of suspensions. One of their advantages is that their damping coefficient can be controlled without the need for any external source of power. In this study, a handful of control approaches are implemented on a car models using MATLAB/Simulink. The investigated control methodologies are skyhook, groundhook, hybrid skyhook-groundhook, Acceleration Driven Damper, Power Driven Damper, H∞ Robust Control, Fuzzy Logic Controller, and Inverse ANFIS. H∞ Robust Control is an advanced method that guarantees transient performance and rejects external disturbances. It is shown that H∞ with the proposed modification, has the best performance although its relatively high cost of computation could be potentially considered as a drawback. Also, the proposed Inverse ANFIS controller uses the power of fuzzy systems along with neural networks to help improve vehicle ride metrics significantly. In this study, a novel approach is introduced to analyze and fine-tune semi-active suspension control algorithms. In some cases, such as military trucks moving on off-road terrains, it is critical to keep the vehicle ride quality in an acceptable range. Semi-active suspensions are used to have more control over the ride metrics compared to passive suspensions and also, be more cost-effective compared to active suspensions. The proposed methodology will investigate the skyhook-groundhook hybrid controller. This is accomplished by conducting sensitivity analysis of the controller performance to varying vehicle/road parameters. This approach utilizes sensitivity analysis and one-at-a-time methodology to find and reach the optimum point of vehicle suspensions. Furthermore, real-time tuning of the mentioned controller will be studied. The online tuning will help keep the ride quality of the vehicle close to its optimum point while the vehicle parameters are changing. A quarter-car model is used for all simulations and analyses. / Ph. D.

The ability of a Formula SAE sports car to negotiate a turn in a race is influenced by many parameters which include car's overall geometry, its shape, weight distribution, type of suspension used, spring and shock absorber characteristics that are used in the tire properties, static and dynamic loading. Steady-state cornering implies that the forces acting on the vehicle are unchanging for a given time. The suspension uprights form a connection between the wheel assembly and the suspension linkages. The criticality of the upright is that it is considered an un-suspended body, but in fact, it is subjected to very high stresses. The dynamic load imposed on the vehicle from various road conditions, cornering, braking and suspension assembly constraints generate stress on the upright body. The equations of motion generally govern vehicle dynamics. For a kinematic and rigid body dynamics analysis, a multibody dynamics (MBD) approach is popular. The results of the dynamic analysis yield internal loads which are used to analyze suspension components for structural stiffness and strength. Automotive companies with relatively lower structural loads have made the MBD approach popular because it is supposed to be computationally less expensive. Elastodynamics is an alternative approach to solving dynamics equations while considering the components to be elastic. This approach can capture the inertial and elastic responses of the components and the load path with varying positions of the components in a mechanism. In this research, a quarter-car suspension is modeled in a finite element code (Abaqus®), focusing on the vehicle upright but still modeling the connections and interactions of the quarter-car suspension system of a FSAE vehicle. The BEAM element modeling used for the suspension members captures the bending response. The overall model is created by making computationally conscious decisions, debugging and refining the interactions and connections to be representative. The modeling technique to create elastodynamic models is explored and established with a versatile set of suspension components and interactions providing a good experience with finite element modeling. The models are created with incremental steps and early steps are verified with hand calculations. A further vehicle verification and validation plan is the next immediate priority to gain confidence in the model for accurate simulations which can be used to predict accurate structural and dynamic results. With extending the model capabilities and computational capabilities, a quarter-car suspension model is powerful enough to run the entire track simulations for formula races and even durability load cases for commercial vehicles. Fatigue loading and abusive test cases would be the load cases to investigate possible failure modes. The quarter-car suspension model is a framework with different interactions, connections, components, boundary conditions and loads that are representative for different suspension configurations in different vehicles. The best practices of this modeling exercise are established and scalability to defeature or add details while preserving the connection behavior is achieved. / Master of Science

Yes / The rise of artificial intelligence in parallel with the fusion of the physical and digital worlds is sustained by the development and progressive adoption of cyber-physical systems (CPSs) and the Internet of Things (IoT). Cooperative and autonomous CPSs have been shown to have significant economic and societal potential in numerous domains, where human lives and the environment are at stake. To unlock the full potential of such systems, it is necessary to improve stakeholders' confidence in such systems, by providing safety assurances. Due to the open and adaptive nature of such systems, special attention was invested in the runtime assurance, based on the real-time monitoring of the system behaviour. IoT-enabled multi-agent systems have been widely used for different types of monitoring applications. In this paper, we discuss the opportunities for applying IoT-based solutions for the cooperative CPSs safety assurance through an illustrative example. Future research directions have been drawn based on the identification of the current challenges.

This thesis presents the development of a full vehicle model tailored for real-time simulation applications. A comprehensive modular simulation framework is developed with the primary goal of providing an accurate and flexible vehicle model for real-time simulations. The vehicle model is developed using a multibody dynamics approach, leveraging efficient formulations and symbolic manipulation to generate cost-effective analytical models. This work presents the model's underlying theory and practical implementation, showcasing the framework's modularity that facilitates seamless integration of external models. This adaptability enables the model's application in a wide range of scenarios, ranging from vehicle dynamics analysis to the development of advanced driver assistance systems. The simulation framework is utilized for Hardware-in-the-Loop (HIL) and Driver-in-the-Loop (DIL) simulations, proving its efficacy in real-world scenarios. Validation against commercial simulation software and real-world vehicle telemetry data further corroborated the model's fidelity and accuracy. Beyond the core vehicle model, this research introduces innovative models that significantly contribute to the simulation efficiency and accuracy. A novel Limited Slip Differential (LSD) model is proposed, employing a smooth equation switching approach to improve numerical efficiency and address issues of conventional approaches such as robustness and the non-exact representation of the locked state. Furthermore, a Symbolic-Numerical Approach is presented for analyzing structure compliance, with a specific application to vehicle suspension compliance analysis. This approach exploits the symbolic manipulation capabilities of computer algebra software to generate efficient analytical models for the suspension's Kinematics and Compliance (K&C) characteristics. This approach not only provides a comprehensive methodology for analyzing suspension compliance but also offers a framework for the generation of symbolic models for any compliant mechanisms, enhancing efficiency in simulation, design, sensitivity analyses, and optimization tasks. In essence, this Ph.D. thesis presents a comprehensive vehicle model for real-time simulation applications, featuring a flexible and modular framework alongside novel models that address specific challenges in vehicle dynamics simulation. Real-time capabilities of the developed model enable closed-loop simulations making it a powerful tool for virtual prototyping, performance evaluation, and controller development in the automotive domain. Practical applications in the field of autonomous vehicles and advanced driver assistance systems showcase the applicability of the proposed framework and models, offering a user-friendly framework for future research and development.

<p dir="ltr">Car design is a complex task because of how highly integrated system of systems it is. Fine?designed car models take years of design and optimization and are usually done by specialty teams who are dedicated to each sub-system. This thesis delves into designing a simplified electric race car from scratch with focus on the performance envelope of it. First, a 3D CAD model was done using SolidWorks. That section deals with spatial engineering and strategic placement of major car components for best performance. Having most of the parts in place gives a rough estimate of CoG (Center of Gravity) location, which is needed for vehicle dynamics analysis, which are discussed later in the report. The target for this project car is to have innovative aerodynamics features which might not have been used before because of bulky internal combustion engines restricting available space. One of them is an airfoil-like fascia which makes the center part of the car act as a one big wing. That is believed to give a significant reduction in drag loads on the car. The approach for aerodynamics design and analysis started with a model representing the car’s OML (Outer Mold line) which was simulated separately using Siemens StarCCM+. After understanding the car’s body aero behavior, a rear wing was added to provide extra rear downforce for better handling and stability. The rear wing design was explained in detail. Unfortunately, due to time restrictions as well as software access issues, the aerodynamic analysis of the full car with rear wing is left for future work. After having an estimate about aero loads acting on the car, vehicle dynamics analysis could start. The first subject studied in vehicle dynamics was front-view suspension geometry analysis. Taking the available packaging and geometry into consideration, a 2D model was done in SolidWorks to optimize camber gain. This analysis gave the motion ratio of the front and rear pushrod suspension system which was needed to analyze the performance of the one-eighth car model, ½ car pitch model, and ½ car roll model. These models gave insights into the decision-making process for spring and damping rates to reach a good balance between performance and comfort. This project acts as a hub for further development and studies related to car design.</p>

Volvo trucks are involved in a project with vehicle combinations longer than 25.25 meters and/or with a weight of more than 64 tons. Those combinations are called high capacity transport (HCT). Some of the vehicle combinations are now driven with exemptions for the coupling equipment. The exemption is needed because according to a standard the theoretical transmitted forces between the dolly and the truck exceed the value that the coupling components have been certified for. The theoretical transmitted forces are called performance indexes. This limits the development but the exception could be avoided by using a hinged drawbar on the dolly.  This thesis aims to investigate what needs to be done in order to introduce dolly with hinged drawbar in longer and heavier vehicle combinations. A literature study and interviews were conducted to find problems that could be expected when using hinged drawbar on dolly and to investigate how the performance indexes for a specific vehicle combination should be calculated. Thereafter a dolly was put together through a product development process. Then concepts to solve a problem that was noticed through the literature study were developed. The concepts were sketched, evaluated in a matrix and thereafter the winning concept was modelled in detail in computer aided design (CAD).   According to the traffic definition in Sweden a dolly with hinged drawbar is violating the law. It defines a dolly as a module with rigid drawbar. On the other hand, the European Union defining a dolly as a trailer with fifth- wheel made to convert a semi-trailer into a full trailer. They don’t mention anything that contradicts to the usage of hinged drawbar. So the Swedish definition of a dolly needs to be challenged.   Simulations have shown that the braking performance will be worse when using a dolly with hinged drawbar compared to using a dolly with rigid drawbar. Therefore concepts to improve the braking performance of the dolly have been developed. The concept was to look the fifthwheel from pivoting around a horizontal axle perpendicular to the driving direction. By doing so the dolly and semi-trailer will become more like a full trailer and that would better the braking performance.  Through interviews and literature study it was noticed that the high performance indexes were calculated in an incorrect way. The highest forces are generated through interaction forces which are only affected by the vehicles closest to the coupling components. Therefore a calculation model need to be modified for this. Three calculation models were tested on the vehicle-combination. Two of these generated performance indexes that were reasonable. The calculation models were ISO-combination 3 and a model developed by Sweatman (1980). These two calculation models are modified for vehicle combinations that includes three vehicles. / Volvo lastvagnar ingår i ett forskningsprojekt med lastbilskombinationer som är längre än 25,25  meter och/eller väger mer än 64 ton. Ett sådant fordon kallas högkapacitetstransport (HCT). Idag körs vissa av dessa fordon med dispenser för kopplingsutrustningen. Detta då de teoretiska överförda krafterna mellan lastbil och dolly enligt en standard får värden som är högre än vad kopplingsutrustningen är certifierad med. De teoretiska överförda krafterna benämns som prestandaindex. Denna dispens skulle kunna undvikas genom att använda en ledad dragstång på dollyn.  Detta examensarbete syftar till att undersöka vad som behöver göras för att introducera dolly med ledad dragstång i längre och tyngre fordonskombinationer. En litteraturundersökning samt intervjuer genomfördes för att upptäcka problem som kan uppstå vid användande av dolly med ledad dragstång. Även en undersökning gällande hur prestandaindex ska beräknas på rätt sätt genomfördes.  Därefter konstruerades en dolly genom en produktutvecklingsprocess. Koncept för att lösa ett problem som noterades under litteraturundersökningen utvecklades. Koncepten skissades och blev sedan utvärderade genom en matris. Det vinnande konceptet konstruerades i CAD.   Från litteraturstudien visade det sig att det finns en motstridighet i den svenska definitionen gällande användandet av ledad dragstång på dolly. I Sverige definieras dolly som en kärra. En kärra definieras som en modul med stel dragstång. Däremot definierar EU dolly som en trailer som konverterar en semi-trailer till en full trailer. Där nämns ingenting som kan stoppa användandet av dolly med ledad dragstång. Därför borde den svenska definitionen utmanas.   En dolly med ledad dragstång förväntas ha sämre bromsprestanda än en vanlig dolly. Koncept utvecklades för att förbättra bromsprestandan på dollyn. Konceptet som vann var att låsa vändskivan från att vridas runt en horisontell axel vinkelrätt till åkriktningen. På så viss blir kombinationen dolly, semi-trailer mer som en full trailer vilket skulle innebära en bättre bromsprestanda.  Från intervjuer med kunniga personer och från litteraturstudien framkom det att de höga prestanda indexen var felaktigt beräknade. Det blev även känt att de största krafterna genereras genom interaktionskrafter som endast påverkas av de närmaste fordonens vikt. Tre olika beräkningsmodeller testades där två utav dem gav värden som kan anses vara rimliga. Beräkningsmodellerna var ISO-kombination 3 och en modell utvecklad av Sweatman (1980). Dessa två är anpassad för kombinationer som innehåller 3 fordon.

O aumento no número de veículos tem levado a um exagerado aumento das colisões. Para diminuir a quantidade e a gravidade dos acidentes, a segurança veicular passou a ser um ponto determinante na concepção de um automóvel. Dentre as principais frentes de estudo da segurança veicular está a redução da energia cinética transmitida aos ocupantes quando de uma colisão. Neste caso, os projetos de veículos empregam absorvedores de impacto, também conhecidos pelo termo em inglês crash box, para absorver a energia cinética do impacto em energia de deformação da estrutura. Este estudo tem por objetivo avaliar o desempenho dos absorvedores de energia mais comuns na literatura e na indústria. A avaliação ocorre por meio de simulações numéricas usando o método dos elementos finitos e por considerações teóricas de várias medidas de eficiência. Uma vez identificados os absorvedores de melhor desempenho ao impacto, estes são considerados como base para análises paramétricas de forma e material de modo a se aumentar sua eficiência. / The increase in vehicle production has lead to an increase in the number os colisions. To reduce the amount and severity of accident vehicle safety became an important issue in automobile design. Among the main vehicle safety researches is the reduction in the kinectic energy transmitted to the occupants in a colision event. Impact absorbers or crash boxes transform the impact kinectic energy into plastic deformation. This research aims to asses the performance of the most common energy absorbers used in the industry. The assesment is done trough numerical simulations by finite element analysis and trough theoretical approaches using different effciency measures. The most successful absorbers are used as basis for optimizing its shape and material usage.

Entre as etapas do desenvolvimento de automóveis pode-se apontar a definição das características de suas suspensões. A fase de definição da suspensão pode ser dividida dentro do seguinte cenário: a escolha de um determinado tipo de suspensão, os pontos (geometria) e quais os valores de rigidez/amortecimento para todo o sistema irá resultar em um comportamento dinâmico desejado para o veículo, bem como a viabilidade de produção. Além disso, o entendimento da interação entre os parâmetros de suspensão, é crucial para a otimização do desempenho. Este trabalho pretende propor um método para aperfeiçoar a fase de \"tuning\" da suspensão, com foco principal no conforto. O veículo considerado é um caminhão comercial, e entre os seus parâmetros considerados estão rigidezes de molas da cabine e suspensão, amortecimento da suspensão de cabine e curvas do amortecedor da suspensão primária. O modelo virtual do veículo foi desenvolvido em ambiente ADAMS, o qual, previamente à otimização, foi validado contra dados experimentais. Métricas foram especialmente desenvolvidas levando em consideração aspectos subjetivos de conforto veicular, para dessa forma eliminar a variabilidade entre as avaliações subjetivas e análises das simulações. Os resultados mostraram expressivas melhorias no conforto e através de dados experimentais essas melhorias foram confirmadas. / Among the development phases of an automotive vehicle one can point out the definition of the characteristics of its suspensions. Suspension definition phase can be understood as the following scenario: given a suspension type, which hard points (geometric) and what values of stiffness/damping for the whole system will result in a desired dynamic behavior for the vehicle as well as production feasibility. Moreover, understanding the iteration among the suspension parameters, even considering just the tuning ones, is crucial for performance optimization. This work intends to propose a method for vehicle tuning characteristics optimization, having as a target the ride comfort. The vehicle considered here is a commercial truck, and among its parameters one considers cabin and suspension springs, cabin dampers and suspension damper curves. A vehicle model was developed in ADAMS environment and prior to the optimization the vehicle was validated against experimental data. Metrics were specially developed to take into account subjective aspects of ride, and, in this way, eliminating the gap between subjective evaluations and simulations analysis. Results showed improvements in ride comfort. The resulting setup was measured and the improvements were confirmed with experimental data.

Este trabalho apresenta um mecanismo alternativo para suspensões veiculares traseiras, com mobilidade igual a três, de arquitetura paralela e assimétrico, com três cadeias cinemáticas ativas distintas. O mecanismo é capaz de variar simultaneamente os ângulos de cambagem e de esterçamento das rodas traseiras do veículo, além de atuar sobre a rolagem da massa suspensa. Aplicando-se métodos de síntese de mecanismos paralelos, obtiveram-se topologias de mecanismos de suspensão com estrutura cinemática paralela e, por meio de um critério sistemático, selecionou-se uma estrutura cinemática que atendeu aos três movimentos independentes no espaço tridimensional, desejados para o mecanismo. Um modelo cinemático e outro cinetoestático foram desenvolvidos para verificar a adequação do mecanismo à aplicação veicular. Três análises são apresentadas para avaliar o potencial do mecanismo paralelo sintetizado em aplicações veiculares: análise de desempenho, análise de viabilidade e análise cinemática. Na análise de desempenho, constatou-se que, a atuação do mecanismo sobre os ângulos de cambagem e de esterçamento das rodas traseiras, bem como a atuação sobre a rolagem da massa suspensa trazem benefícios sobre o comportamento dinâmico do veículo, quando comparado com o desempenho dinâmico de um veículo com suspensão convencional. Por meio da análise de viabilidade, determinou-se o curso, a velocidade, a força e a potência demandada pelo sistema de atuação, onde se observou que a atuação do mecanismo pode ser obtida a partir de atuadores comerciais. Nas análises de desempenho e viabilidade o comportamento dinâmico do veículo foi simulado em três manobras distintas: curva de raio constante em regime permanente, dupla mudança de faixa e manobra do anzol (fishhook), empregando uma cosimulação entre os programas CarSim e MATLAB/SIMULINK. Pela análise cinemática, percebeu-se que não há configurações singulares dentro do espaço de trabalho especificado para o mecanismo. O espaço de trabalho disponível atende ao especificado para a aplicação proposta do mecanismo e os erros que os ângulos de cambagem e de esterçamento possam apresentar, devido à imprecisão no posicionamento dos atuadores ou às tolerâncias inerentes ao processo de fabricação das peças do mecanismo, não comprometem os ganhos no comportamento dinâmico que o veículo com o mecanismo proposto apresentou nas simulações da análise de desempenho. / This work introduces an alternative three-degree-of-freedom mechanism for automotive rear suspensions, capable to adjust simultaneously the camber, toe and roll angles. Topologically, the mechanism is parallel and asymmetric with three distinct active kinematic chains. The mechanism is able to adjust the camber, toe and roll angles simultaneously. After applying the methods to perform synthesis of mechanisms, the architecture candidates were ranked in accordance with some proposed indices. Two mathematical models are developed: the kinematic and kinetostatic ones. In order to evaluate how promising this mechanism is, three analyses are conducted: a performance analysis, a feasibility analysis and a kinematic analysis. The obtained results have shown the capability of the mechanism actuation to improve vehicle handling performance, when compared to a car equipped with a conventional suspension system. Moreover, the mechanism feasibility analysis has shown that the actuators stroke, velocity and force can be obtained by using standard hydraulic or eletromechanical actuators. The evaluation was based on three maneuvers: a steady-state cornering, a fishhook and a double lane change. Regarding to the kinematic analysis, three considerations were made. First, there is not singular configuration inside the workspace. Second, the available workspace can attend the camber and rear steer angles stroke. Third, the vehicle dynamic behavior is not affected by the errors due to the manufacturing tolerance and actuators position inaccuracy.

Le mouvement en essaim est défini par l'action d'un ensemble d'individusautopropulsés se déplaçant en groupe uniquement à l’aide de la connaissance locale de leur environnement.L'objectif scientifique de la thèse consiste à mettre en oeuvre ce type demodèle de comportement appliqué à un flot de véhicules se déplaçant sur un profilroutier, et ce afin d'assister le conducteur dans ses actions à la fois pour son confortet sa sécurité.A partir de l’analyse d’une synthèse bibliographique, une stratégie dehiérarchisation a été mise en place afin de créer un système d’aide à la conduite ouADAS (de l’anglais « Advanced Driver Assistance System »). Ainsi, dans un premiertemps, il s’agit de générer une trajectoire à partir de ce type de modèle qui respecteles contraintes autoroutières. Ensuite, la dynamique du véhicule est prise en compteafin de transmettre au conducteur via une régulation de vitesse et un retour haptiqueau volant, les deux étant basés notamment sur la commande CRONE, lesmanoeuvres nécessaires au suivi de cette trajectoire. Enfin, le système d’aide à laconduite est mis en oeuvre, non seulement sur un simulateur dynamique de conduiteafin de recueillir le ressenti des conducteur, mais aussi au sein d’un logiciel desimulation de trafic pour évaluer les gains obtenus dans le cas d’un ensemble devéhicules équipés. / Swarm behavior refers to individuals travelling in a group and using only localknowledge of their environment.The scientific objective of the thesis is to implement this type of behaviormodel to vehicles traveling on road, in order to assist the driver in his actions for bothits comfort and security.From a literature review, a prioritization strategy was set up to create anAdvanced Driver Assistance System (ADAS). At first, it is to generate a path from thistype of model that respects the motorway constraints. Then, vehicle dynamics istaken into account in order to transmit to the driver through cruise control and hapticfeedback steering wheel, both based on the CRONE control, maneuvers needed tofollow this trajectory. Finally, the driver assistance system is not only implemented ona dynamic driving simulator to gather driver’s feelings but it is also implemented intraffic simulation software to evaluate gains obtained for a set of equipped vehicles.