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.

The Master's thesis deals with the simulations kinematics and dynamics of experimental four-wheeled vehicle with all-wheel steering and all-wheel drive. Suggestion of vehicle stability systems ABS/ASR for traction control is included. There are several dynamics models with their comparison. The estimation of important vehicle parameters is implemented. Based on knowledge the simple vehicle stability system ABS/ASR is created.

[ES] Las inundaciones pueden llegar a desestabilizar los vehículos y estos, a su vez, pueden exacerbar los efectos negativos de las inundaciones cuando son arrastrados por el flujo, generando no solamente pérdidas económicas sino también de vidas humanas. En las ciudades, la mayor parte de las muertes durante las inundaciones ocurre al interior de los vehículos debido a que los conductores intentan cruzar con sus vehículos por zonas inundadas (Jonkzman and Kelman 2005; Drobot et al. 2007; Kellar and Schmidlin 2012). En países desarrollados, un alto porcentaje de estas muertes ocurre durante inundaciones relámpago cuando los conductores intentan cruzar por zonas inundadas en lugar de evitarlas (Fitzgerald et al. 2010; Kellar y Schmidlin 2012). Debido a esto, en áreas sujetas a inundaciones relámpago, casi la mitad de las víctimas son pasajeros atrapados en sus vehículos (Versini et al. 2010a) Entre las partes de las vías que resultan afectadas por las crecidas de los ríos se encuentran los puentes, las cuales son obras de infraestructura muy importantes. Un alto porcentaje de los fallos de los puentes a nivel mundial se presenta debido a las crecidas de los ríos, lo cual tiene un impacto negativo en los vehículos y los sistemas de transporte. Debido a esto, con el fin de realizar una adecuada gestión de las inundaciones es necesario determinar el riesgo de inestabilidad al que están sometidos los vehículos en una zona inundable. Sin embargo, a pesar del impacto negativo de las inundaciones, hasta la fecha se dispone de pocos estudios que permitan determinar los efectos negativos que las condiciones climáticas generan sobre los sistemas de transporte (Molarius et al., 2014). En esta investigación se desarrolló una nueva metodología para calcular este riesgo a partir de las características de las crecidas, los puentes, los vehículos, y el tráfico vehicular. Esta metodología fue generada a partir de una estructura conceptual y un desarrollo matemático novedosos y permite determinar el riesgo a través de la integral estadística de la amenaza de inestabilidad y la vulnerabilidad de los coches. En áreas urbanas y en las intersecciones entre las corrientes de agua y las vías, la amenaza se establece a través de una función de estabilidad de autos parcialmente sumergidos, las características geométricas de los vehículos y las características hidrodinámicas de las crecidas (calados y velocidades) y su probabilidad de ocurrencia, mientras que la vulnerabilidad se calcula por medio de la combinación de la susceptibilidad y la exposición de los coches. En puentes, la peligrosidad se obtiene a través del análisis de los datos de caudal disponibles y la vulnerabilidad mediante el análisis del estado estructural del puente, las características de la cuenca y del cauce aguas arriba y aguas abajo de la estructura, la estabilidad del canal y la potencial acumulación de acarreos. La metodología desarrollada se implementó para determinar el riesgo en los siguientes casos de estudio, los cuales están localizados en territorio español: (i) en las áreas urbanas correspondientes a los municipios de Alfafar y Massanassa, (ii) en los sitios de intersección entre vías y ríos localizados en el municipio de Godelleta; y (iii) en 12 puentes fluviales. Los resultados obtenidos podrían estar indicando que el método propuesto tiene en cuenta los elementos más importantes que deben considerarse al establecer este tipo de riesgo. La metodología desarrollada permite obtener un panorama detallado del riesgo de desestabilización de los vehículos debido a inundaciones en una zona determinada. En consecuencia, la implementación de esta metodología puede ayudar a disminuir los efectos negativos antes y durante este tipo de eventos, resultando de gran ayuda para las entidades encargadas de la planificación urbana y de la protección civil con el fin de diseñar e implementar acciones que permitan disminu / [CAT] Les inundacions poden desestabilitzar els vehicles i aquests, al mateix temps, poden exacerbar els efectes negatius de les inundacions quan són arrossegats pel flux, generant no solament pèrdues econòmiques sinó també de vides humanes. A les ciutats, la major part de les morts durant les inundacions ocorre a l'interior dels vehicles pel fet que els conductors intenten creuar amb els seus vehicles per zones inundades (Jonkzman and Kelman 2005; Drobot et al. 2007; Kellar and Schmidlin 2012). En països desenvolupats, un alt percentatge d'aquestes morts ocorre durant inundacions llampec quan els conductors intenten creuar per zones inundades en lloc d'evitar-les (Fitzgerald et al. 2010; Kellar i Schmidlin 2012). A causa d'això, en àrees subjectes a inundacions llampec, quasi la meitat de les víctimes són passatgers atrapats en els seus propis vehicles (Versini et al. 2010a) Entre les parts de les vies que resulten afectades per les crescudes dels rius es troben els ponts, les quals són obres d'infraestructura molt importants. Un alt percentatge de les fallades dels ponts a nivell mundial es presenta com a conseqüència de les crescudes dels rius, la qual cosa té un impacte altament negatiu en els vehicles i els sistemes de transport.. A causa d'això, amb la finalitat de realitzar una adequada gestió de les inundacions és necessari determinar el risc d'inestabilitat al qual estan sotmesos els vehicles en una zona inundable. No obstant això, malgrat l'impacte negatiu de les inundacions, fins a la data es disposa de pocs estudis que permeten determinar els efectes negatius que les condicions climàtiques generen sobre els sistemes de transport (Molarius et al., 2014). En la present investigació es va desenvolupar una nova metodologia per a calcular aquest risc a partir de les característiques de les crescudes, els ponts, els vehicles, i el trànsit vehicular. Aquesta metodologia va ser generada a partir d'una estructura conceptual i un desenvolupament matemàtic nous i permet determinar el risc a través de la integral estadística de l'amenaça d'inestabilitat i la vulnerabilitat dels cotxes. En àrees urbanes i en les interseccions entre els corrents d'aigua i les vies, l'amenaça s'estableix a través d'una funció d'estabilitat de cotxes parcialment submergits, les característiques geomètriques dels vehicles i les característiques hidrodinàmiques de les crescudes (calats i velocitats) i la seua probabilitat d'ocurrència, mentre que la vulnerabilitat es calcula per mitjà de la combinació de la susceptibilitat i l'exposició dels cotxes. En ponts, la perillositat s'obté a través de l'anàlisi de les dades de cabal disponibles i la vulnerabilitat mitjançant l'anàlisi de l'estat estructural del pont, les característiques de la conca i del llit aigües amunt i aigües avall de l'estructura, l'estabilitat del canal i la potencial acumulació d'enderrocs. La metodologia desenvolupada es va implementar per a determinar el risc en els següents casos d'estudi, els quals estan localitzats en territori espanyol: (i) en les àrees urbanes corresponents als municipis d'Alfafar i Massanassa, (ii) en els llocs d'intersecció entre vies i rius localitzats en el municipi de Godelleta; i (iii) en 12 ponts fluvials. Els resultats obtinguts podrien estar indicant que el mètode proposat té en compte els elements més importants que han de considerar-se en establir aquest tipus de risc. La metodologia desenvolupada permet obtindre un panorama detallat del risc de desestabilització dels vehicles a causa d'inundacions en una zona determinada. En conseqüència, la implementació d'aquesta metodologia pot ajudar a disminuir els efectes negatius abans i durant aquesta mena d'esdeveniments, resultant de gran ajuda per a les entitats encarregades de la planificació urbana i de la protecció civil amb la finalitat de dissenyar i implementar accions que permeten disminuir els efectes negatius de les inundacions. / [EN] Flooding can destabilize vehicles which might, in turn, exacerbate the negative effects of floods when vehicles are swept away by flows, leading to economic loss and fatalities. The main cause of death in cities during flood events corresponds to cars being swept away when they are driven by flooded roads (Jonkzman and Kelman 2005; Drobot et al. 2007; Kellar and Schmidlin 2012). In developed countries a high percentage of these deaths occurs during flash floods when drivers try to cross overflowing water bodies instead of avoiding them (Fitzgerald et al. 2010; Kellar and Schmidlin 2012). Hence, in areas subject to flash floods almost half of the victims are passengers trapped inside their own vehicles (Versini et al. 2010a). Among the parts of the roads that are most affected by floods are bridges, which are very important infrastructure works for society. Because of this, a high percentage of bridge failures worldwide occur as a result of river floods, which has highly negative impacts for vehicles and transportation systems. Therefore, in order to suitably manage floods, it is necessary to determine the risk of instability to which vehicles in flood-prone areas are subject. However, Despite the negative impact of floods, very few studies have centred on determining the negative effects of floods on transport systems (Molarius et al., 2014). In this research, a new methodology to estimate this risk based on the characteristics of vehicles, floods, bridges and vehicular traffic was developed. This methodology was generated from a novel conceptual structure and mathematical development and allows to determine the risk by the statistical integral of the instability hazard and the vehicles' vulnerability. In urban areas and stream crossings, the hazard is determined by a stability criterion of partially submerged cars, the geometric characteristics of the vehicles and the hydrodynamic characteristics of the floods (depths and velocities) and their probability of occurrence, while vulnerability is calculated by combining the susceptibility and exposure of cars. In bridges, the hazard is obtained by analysing available discharge data and the vulnerability by examining the structural condition of the bridge, the characteristics of the watershed and watercourse upstream and downstream of the structure, the stability of the channel and the potential accumulation of debris. The developed methodology was implemented to determine the risk in the following case studies, which are located in Spanish territory: (i) in the urban areas corresponding to the towns of Alfafar and Massanassa; (ii) in the stream crossings located in the municipality of Godelleta; and (iii) in 12 river bridges located. The results obtained could be indicating that the proposed method takes into account the most important elements to be considered when establishing this type of risk. The developed methodology provides a detailed vision of the vehicle instability risk due to flooding in a given area. Consequently, implementing this methodology can help to reduce negative effects before and during flooding events, which is extremely helpful for those organizations in charge of urban planning and civil protection to design and take actions that cushion the negative effects of flooding. / I thank Colciencias for financing this research through call 728-2015. / Bocanegra Vinasco, RA. (2020). Evaluation of the risk due to fluvial flooding in vehicles and road infrastructures at basin scale [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/157654 / TESIS

Stability is an important criterion in the design and performance of launch vehicles. Present day launch vehicles have become more and more flexible due to the constraints of weight reduction, necessarily imposed for enhanced performance of the vehicle. Due to higher flexibility, the launch vehicle stability becomes a concern. Instability in the launch vehicles has been noticed due to three major sources: thrust, aerodynamic forces and combustion induced instabilities. Instability in the launch vehicles may pose problem to the structural integrity leading to structural failure or it may lead to the deviation in the trajectory of the vehicle. Several structural failures of launch vehicles due to instabilities have been reported in the literature. The prediction of the structural response due to various excitations such as thrust and aerodynamic loading is essential to identify any failure scenarios and to limit the vibrations transmitted to the payload. Therefore, determination of dynamic and stability characteristics of a launch vehicle under the influence of different parameters, is of vital importance. Disciplines such as, flight mechanics (dynamics), structural dynamics, aerodynamics, propulsion, guidance and control are closely related in the design and analysis of launch vehicles. Typically, flight mechanics, guidance and control problems consider a rigid vehicle for modeling and simulation purposes. The disciplines of structural dynamics and aeroelasticity consider a flexible vehicle. In order to bring in the effect of flexibility on the flight dynamics of the launch vehicle, structural dynamics and aeroelasticity aspects need to be effected. The preliminary design of a new launch vehicle requires inputs from different disciplines and parametric studies are required to finalise the vehicle configuration. The study of the effect of different parameters on the dynamics and stability of launch vehicles is required. In this context, there is a need to develop an integrated approach that provides tools for the design and analysis of a launch vehicle. The availability of integrated modeling and simulation tools will reduce the requirement of costly prototype development and testing. In the present thesis, an attempt has been made to develop a numerical tool to conduct parametric studies for launch vehicle dynamics and stability. The developed tool is suitable for prediction of onset of instabilities under the influence of different parameters. The approach developed in this thesis is also well suited for specialized analysis of problems involving vertical launch, stage separation, engine shutdown and internal stress wave propagation related to structural integrity. Stability problems due to thrust and the aerodynamic forces (aeroelastic stability) in the launch vehicles/ missiles have been reported in the literature. Most of these works have modeled the vehicle as a beam or by using discrete degrees of freedom. In these works, the effect of thrust or aerodynamic forces on the flexible body modes is investigated and it is shown that the instability may occur in one of the bending modes due to change in the parameters such as thrust or aerodynamic forces. Traditionally, the dynamic characteristics are obtained in a body-fixed coordinate system, whereas the prediction of trajectory (rigid body dynamics) is carried out in an inertial frame of reference. Only few works have addressed the coupling of the rigid body motion and the flexible body dynamics of a vehicle. But these works also, do not consider the total derivative of displacements with respect to an inertial frame of reference. When the integrated equations of motion are derived in an inertial frame of reference, the rigid body motion and the elastic displacements are highly coupled. In this thesis, the rigid body motion and the flexible body dynamics is studied in an inertial frame of reference. The flexible body dynamics of the moving vehicle is studied in an inertial frame of reference, including velocity induced curvature effects, which have not been considered so far in the published literature. A detailed mechanics based model is developed to analyze the problem of structural instabilities in launch vehicles. Coupling among the rigid-body modes, the longitudinal vibrational modes and the transverse vibrational modes due to asymmetric lifting-body cross-section are considered. The model also incorporates the effects of aerodynamic forces and the propulsive thrust of the vehicle. The propulsive thrust is considered as a follower force. The model is one-dimensional, and it can be employed to idealized slender vehicles with complex shapes. The governing differential equations along with the boundary conditions are derived using Extended Hamilton’s principle. Subsequently, the modeling of the propulsive thrust and the aerodynamic forces are included in the formulation. In the literature, the propulsive thrust has generally been modeled as a follower force applied at the nozzle end. Few of the works in the literature have modeled the combustion process in the solid rocket motor and the liquid propellant engine in detail. This is required to understand the combustion induced instabilities. In the present thesis, the propulsive thrust is considered as a follower force and few of the combustion parameters affecting the thrust are considered. In the literature, the modeling of the aerodynamic forces acting on a launch vehicle has been carried out using general purpose computational fluid dynamics (CFD) codes or by using empirical methods. CFD codes are used to obtain the pressure and the shear stress distribution on the vehicle surface by the solution of Navier Stokes/ Euler equations. The empirical methods have been used to obtain the distributed aerodynamic forces acting on the vehicle. The aerodynamic forces are expressed in terms of distributed aerodynamic coefficients. In the present work, the modeling of the aerodynamic forces has been carried out in two different ways: using a CFD package and by using empirical methods. The stability of a system can be studied by determining the system response with time. Eigenvalue analysis is another tool to investigate the stability of a linear system. To study the stability characteristics of the system using eigenvalue analysis, a computational framework has been developed. For this purpose, the finite element discretization of the system is carried out. Further to that, two different methods are utilized for finite element discretization of the vehicle structure: Fourier Transform based Spectral Finite Element method (SFEM) and an hp Finite Element method (FEM). The conventional FEM is a versatile tool for modeling complicated structures and to obtain the solution of the system of equations for a variety of forcing functions. The SFEM is more suitable for obtaining the solution for simple 1D and 2D structures subjected to shock and transient loads, having high frequency content. In this thesis, the spectral finite element model is developed for a vehicle subjected to the propulsive thrust and the aerodynamic forces. Prediction of instability using SFEM, means solving a nonlinear eigenvalue problem. Standard computer codes or routines are not available for solving a nonlinear eigenvalue problem. A computer code has been written to solve the nonlinear eigenvalue problem using one of the algorithms available in the literature. An hp finite element model is also developed for launch vehicle. The finite element stiffness and damping matrices due to the thrust, the aerodynamic forces and the rigid body velocity and acceleration are derived using Lagrange’s equations of motion. A standard linear eigenvalue problem and a polynomial eigenvalue problem is formulated for determination of instability regimes of the vehicle. It is important to understand the influence of different parameters such as thrust, velocity, angle of attack etc. on the stability of a launch vehicle. Parametric studies are important during the preliminary design phase of a vehicle to identify the instability regimes. The design parameters can be changed to reduce the possibility of instabilities. Numerical simulations are carried out to determine the unstable regimes of a slender launch vehicle for propulsive thrust and velocity as the parameters, neglecting the aerodynamic forces. Comparison between the results based on a Fourier spectral finite element model and a hp finite element model are carried out. Phenomenon of static instability (divergence) and dynamic instability (flutter) are observed. Determination of mode shapes of the vehicle is important for deciding the placement of sensors and actuators on the vehicle. In this context, eigenvectors (mode shapes) for different end thrust and speed are analyzed. Further, numerical simulations are also carried out to determine the instabilities in a slender launch vehicle considering the combined effects of propulsive thrust, aerodynamic forces and mass variation. The finite element model simulation results for aeroelastic effects are compared with the published literature. Stability of a vehicle is analysed for velocity (free stream Mach number) as a parameter, at maximum propulsive thrust, including the effect of aerodynamic forces and mass variation. Phenomenon of static instability (divergence) and dynamic instability (flutter) are observed. With the increase in the Mach number, branching (splitting) and merging of the modes is observed. At higher Mach numbers, divergence and flutter are observed in different modes simultaneously. Numerical simulations are carried out for a typical nosecone launch vehicle configuration to analyse the aeroelastic stability at two different Mach numbers using empirical aerodynamic data. The phenomenon of flow separation and reattachment is observed at the cone-cylinder junction. The stability of a typical vehicle under propulsive thrust and aerodynamic forces is investigated using CFD derived aerodynamic data. The aerodynamic pressure and shear stress distribution for a launch vehicle are obtained from the CFD analysis. The effect of different parameters such as combustion chamber pressure, tip mass and slenderness ratio on the stability of a vehicle is studied. In the later part of the thesis, solution methodology for the time domain response for a coupled axial and transverse motion of a vehicle is developed. The axial responses (displacements and velocities) of a typical vehicle subjected to axial thrust are determined using direct integration of the equations of motion. The axial displacements due to two different thrust histories are compared. The axial velocities with time at different locations are determined. The time domain and the frequency domain responses for a representative vehicle subjected to a transverse shock force are determined using Spectral Finite Element method (SFEM). The system of equations for a coupled axial and transverse motion of a vehicle is developed. Numerical simulations are carried out to determine the coupled axial and transverse response of a vehicle subjected to axial and transverse forces. The coupling of rigid body motion with the elastic displacements is illustrated. The thesis is comprised of seven chapters. The first chapter gives a detailed introduction to launch vehicles and covers literature survey of launch vehicle dynamics and stability. The dynamics and stability related aspects of flexible structures are also discussed. In chapter 2, a detailed mathematical model of a slender launch vehicle is developed to analyze the problem of structural instabilities. Chapter 3 deals with the finite element discretization of the vehicle structure using two different methods: Fourier spectral finite element method and an hp finite element method. In chapters 4 and 5, numerical simulations are carried out to determine the instabilities in a slender launch vehicle considering the effects of propulsive thrust, aerodynamic forces and mass variation. In chapter 6, solution methodology for the time domain response for a coupled axial and transverse motion of a vehicle is developed. The last chapter gives the conclusions and the future scope of work. To summarize, this thesis is a comprehensive document, that not only describes some detailed mathematical models for launch vehicle stability studies, but also presents the effect of aerodynamic, propulsion and structural loads on the launch vehicle stability. Linear stability analysis of a representative vehicle is carried out for prediction of onset of the instabilities under the influence of different parameters such as velocity, thrust, combustion factors etc. The correlation between the stability analysis and the time domain response is established. In short, the matter presented in this thesis can serve as a useful design aide for those working in the launch vehicle design.

[EN] Nowadays, there are many electronic products that incorporate elements and features coming from the research in the field of mobile robotics. For instance, the well-known vacuum cleaning robot Roomba by iRobot, which belongs to the field of service robotics, one of the most active within the sector. There are also numerous autonomous robotic systems in industrial warehouses and plants. It is the case of Autonomous Guided Vehicles (AGVs), which are able to drive completely autonomously in very structured environments. Apart from industry and consumer electronics, within the automotive field there are some devices that give intelligence to the vehicle, derived in most cases from advances in mobile robotics. In fact, more and more often vehicles incorporate Advanced Driver Assistance Systems (ADAS), such as navigation control with automatic speed regulation, lane change and overtaking assistant, automatic parking or collision warning, among other features. However, despite all the advances there are some problems that remain unresolved and can be improved. Collisions and rollovers stand out among the most common accidents of vehicles with manual or autonomous driving. In fact, it is almost impossible to guarantee driving without accidents in unstructured environments where vehicles share the space with other moving agents, such as other vehicles and pedestrians. That is why searching for techniques to improve safety in intelligent vehicles, either autonomous or manual-assisted driving, is still a trending topic within the robotics community. This thesis focuses on the design of tools and techniques for planning and control of intelligent vehicles in order to improve safety and comfort. The dissertation is divided into two parts, the first one on autonomous driving and the second one on manual-assisted driving. The main link between them is the use of clothoids as mathematical formulation for both trajectory generation and collision detection. Among the problems solved the following stand out: obstacle avoidance, rollover avoidance and advanced driver assistance to avoid collisions with pedestrians. / [ES] En la actualidad se comercializan infinidad de productos de electrónica de consumo que incorporan elementos y características procedentes de avances en el sector de la robótica móvil. Por ejemplo, el conocido robot aspirador Roomba de la empresa iRobot, el cual pertenece al campo de la robótica de servicio, uno de los más activos en el sector. También hay numerosos sistemas robóticos autónomos en almacenes y plantas industriales. Es el caso de los vehículos autoguiados (AGVs), capaces de conducir de forma totalmente autónoma en entornos muy estructurados. Además de en la industria y en electrónica de consumo, dentro del campo de la automoción también existen dispositivos que dotan de cierta inteligencia al vehículo, derivados la mayoría de las veces de avances en robótica móvil. De hecho, cada vez con mayor frecuencia los vehículos incorporan sistemas avanzados de asistencia al conductor (ADAS por sus siglas en inglés), tales como control de navegación con regulación automática de velocidad, asistente de cambio de carril y adelantamiento, aparcamiento automático o aviso de colisión, entre otras prestaciones. No obstante, pese a todos los avances siguen existiendo problemas sin resolver y que pueden mejorarse. La colisión y el vuelco destacan entre los accidentes más comunes en vehículos con conducción tanto manual como autónoma. De hecho, la dificultad de conducir en entornos desestructurados compartiendo el espacio con otros agentes móviles, tales como coches o personas, hace casi imposible garantizar la conducción sin accidentes. Es por ello que la búsqueda de técnicas para mejorar la seguridad en vehículos inteligentes, ya sean de conducción autónoma o manual asistida, es un tema que siempre está en auge en la comunidad robótica. La presente tesis se centra en el diseño de herramientas y técnicas de planificación y control de vehículos inteligentes, para la mejora de la seguridad y el confort. La disertación se ha dividido en dos partes, la primera sobre conducción autónoma y la segunda sobre conducción manual asistida. El principal nexo de unión es el uso de clotoides como elemento de generación de trayectorias y detección de colisiones. Entre los problemas que se resuelven destacan la evitación de obstáculos, la evitación de vuelcos y la asistencia avanzada al conductor para evitar colisiones con peatones. / [CAT] En l'actualitat es comercialitzen infinitat de productes d'electrònica de consum que incorporen elements i característiques procedents d'avanços en el sector de la robòtica mòbil. Per exemple, el conegut robot aspirador Roomba de l'empresa iRobot, el qual pertany al camp de la robòtica de servici, un dels més actius en el sector. També hi ha nombrosos sistemes robòtics autònoms en magatzems i plantes industrials. És el cas dels vehicles autoguiats (AGVs), els quals són capaços de conduir de forma totalment autònoma en entorns molt estructurats. A més de en la indústria i en l'electrònica de consum, dins el camp de l'automoció també existeixen dispositius que doten al vehicle de certa intel·ligència, la majoria de les vegades derivats d'avanços en robòtica mòbil. De fet, cada vegada amb més freqüència els vehicles incorporen sistemes avançats d'assistència al conductor (ADAS per les sigles en anglés), com ara control de navegació amb regulació automàtica de velocitat, assistent de canvi de carril i avançament, aparcament automàtic o avís de col·lisió, entre altres prestacions. No obstant això, malgrat tots els avanços segueixen existint problemes sense resoldre i que poden millorar-se. La col·lisió i la bolcada destaquen entre els accidents més comuns en vehicles amb conducció tant manual com autònoma. De fet, la dificultat de conduir en entorns desestructurats compartint l'espai amb altres agents mòbils, tals com cotxes o persones, fa quasi impossible garantitzar la conducció sense accidents. És per això que la recerca de tècniques per millorar la seguretat en vehicles intel·ligents, ja siguen de conducció autònoma o manual assistida, és un tema que sempre està en auge a la comunitat robòtica. La present tesi es centra en el disseny d'eines i tècniques de planificació i control de vehicles intel·ligents, per a la millora de la seguretat i el confort. La dissertació s'ha dividit en dues parts, la primera sobre conducció autònoma i la segona sobre conducció manual assistida. El principal nexe d'unió és l'ús de clotoides com a element de generació de trajectòries i detecció de col·lisions. Entre els problemes que es resolen destaquen l'evitació d'obstacles, l'evitació de bolcades i l'assistència avançada al conductor per evitar col·lisions amb vianants. / Girbés Juan, V. (2016). Clothoid-based Planning and Control in Intelligent Vehicles (Autonomous and Manual-Assisted Driving) [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/65072 / TESIS

An Over-Actuated (OA) vehicle is a system that presents more control variables than degrees of freedom. Therefore, more than one configuration of the control input can drive the system to a desired state in the state space, and this redundancy can be exploited to fulfill other tasks or solve further problems. In particular, nowadays, challenges concerning electric vehicles regarding their autonomy and solutions to reduce energy consumption are becoming more and more attractive. OA vehicles, on this problem, offer the possibility of using the redundancy to choose the control input, among possible ones, so as to minimize energy consumption. In this regard, the research objective is to investigate different techniques to control in real-time an over-actuated autonomous driving vehicle to guarantee trajectory following and stability with the aim of minimizing energy consumption. The research project focuses on a vehicle able to drive and steer the four wheels (4WD, 4WS) independently. This work extends the contribution of previous theoretical energy-based research developed and provides a control algorithm that must work in real-time on a prototype vehicle (RCV-E) developed at the Integrated Transport Research Lab (ITRL) within KTH with the over-actuation investigated. To this end, the control algorithm has to balance the complexity of a multi-input system, the optimal allocation objectives, and the agility to run in real-time on the MicroAutoBox II - dSPACE system mounted on the vehicle. The solution proposed is a two-level controller which handles separately high and low-rate dynamics with an adequate level of complexity. The upper level is responsible for trajectory following and energy minimization. The allocation problem is solved in two steps. A Linear Time-Varying Model Predictive Controller (LTV-MPC) solves the trajectory-following problem and allocates the forces at the wheels considering the wheel energy losses due to longitudinal and lateral sliding. The second step re-allocates the longitudinal forces between the front and rear axles by considering each side of the vehicle independently to minimize energy loss in the motors. The lower level is responsible for transforming the forces at the wheels into torques and steering angles; it runs at a faster rate than the upper level to account for the high-frequency dynamics of the wheels. Last, the overall control strategy is tested in simulation concerning the trajectory-following and energy minimization performance. The real-time performance are assessed on MircoAutoBox II, the control interface used on the RCV-E. / Ett fordon med olika grad av över-aktuering är ett system som har fler kontrollvariabler än frihetsgrader. Därför kan mer än en konfiguration av styrinmatningen driva systemet till ett önskat tillstånd i tillståndsrummet, och denna redundans kan utnyttjas för att utföra andra uppgifter eller lösa andra problem. I synnerhet blir det i dag allt mer attraktivt med utmaningar som rör elfordon när det gäller deras självklörande drift och lösningar för att minska energiförbrukningen. Överaktuerat fordon ger möjlighet att använda redundansen för att välja en av de möjliga styrinmatningarna för att minimera energiförbrukningen. Forskningsmålet är att undersöka olika tekniker för att i realtid styra ett självkörande fordon som är överaktuerat för att garantera banföljning och stabilitet i syfte att minimera energiförbrukningen. Forskningsprojektet är inriktat på ett fordon som kan köra och styra de fyra hjulen (4WD, 4WS) självständigt. Detta arbete utökar bidraget från den tidigare teoretisk energi-baserade forskning som utvecklats genom att tillhandahålla en regleralgoritm som måste fungera i realtid på ett prototypfordon (RCV-E) som utvecklats vid ITRL inom KTH med den undersökta överaktueringen. I detta syfte måste regleralgoritmen balansera komplexiteten hos ett system med flera ingångar, målen för optimal tilldelning och smidigheten samt att fungera i realtid på MicroAutoBox II - dSPACE-systemet som är monterat på fordonet. Den föreslagna lösningen är en tvåstegsstyrning som hanterar dynamiken med hög och låg hastighet separat med en lämplig komplexitetsnivå. Den övre nivån ansvarar för banföljning och energiminimering. Tilldelningsproblemet löses i två steg. En LTV-MPC löser banföljningsproblemet och fördelar krafterna på hjulen med hänsyn till energiförlusterna på hjulen på grund av longitudinell och lateral glidning. I det andra steget omfördelas de längsgående krafterna mellan fram- och bakaxlarna genom att varje fordonssida beaktas oberoende av varandra för att minimera energiförlusterna i motorerna. Den lägre nivån ansvarar för att omvandla krafterna vid hjulen till vridmoment och styrvinklar; den körs i snabbare takt än den övre nivån för att ta hänsyn till hjulens högfrekventa dynamik. Slutligen testas den övergripande reglerstrategin i simulering med avseende på banföljning och energiminimering, och därefter på MircoAutoBox II monterad på RCV-E för att bedöma realtidsprestanda. / Un veicolo sovra-attuato è un sistema che presenta più variabili di controllo che gradi di libertà. Pertanto, più di una configurazione dell’ingresso di controllo può portare il sistema a uno stato desiderato nello spazio degli stati e questa ridondanza può essere sfruttata per svolgere altri compiti o risolvere ulteriori problemi. In particolare, al giorno d’oggi le sfide relative ai veicoli elettrici per quanto riguarda la loro autonomia e le soluzioni per ridurre il consumo energetico stanno diventando sempre più interessanti. I veicoli sovra-attuati, riguardo a questo problema, offrono la possibilità di utilizzare la ridondanza per scegliere l’ingresso di controllo, tra quelli possibili, che minimizza i consumi energetici. A questo proposito, l’obiettivo della ricerca è studiare diverse tecniche per controllare, in tempo reale, un veicolo a guida autonoma sovra-attuato per garantire l’inseguimento della traiettoria e la stabilità con l’obiettivo di minimizzare il consumo energetico. Questo studio si concentra su un veicolo in grado di guidare e sterzare le quattro ruote (4WD, 4WS) in modo indipendente, ed estende il contributo delle precedenti ricerche teoriche fornendo un algoritmo di controllo che deve funzionare in tempo reale su un prototipo di veicolo (RCV-E) sviluppato presso l’ITRL all’interno del KTH, che presenta la sovra-attuazione studiata. A tal fine, l’algoritmo di controllo deve bilanciare la complessità di un sistema a più ingressi, gli obiettivi di allocazione dell’azione di controllo ottimale e l’agilità di funzionamento in tempo reale sul sistema MicroAutoBox II - dSPACE montato sul veicolo. La soluzione proposta è un controllore a due livelli che gestisce separatamente le dinamiche ad alta e bassa frequenza. Il livello superiore è responsabile dell’inseguimento della traiettoria e della minimizzazione dell’energia. Il problema di allocazione viene risolto in due fasi. Un LTV-MPC risolve il problema dell’inseguimento della traiettoria e assegna le forze alle ruote tenendo conto delle perdite di energia agli pneumatici dovute al loro scorrimento longitudinale e laterale. Il secondo passo rialloca le forze longitudinali tra l’asse anteriore e quello posteriore considerando ciascun lato del veicolo in modo indipendente per minimizzare le perdite di energia nei motori. Il livello inferiore è responsabile della trasformazione delle forze alle ruote in coppia e angolo di sterzo; funziona a una più alta frequenza rispetto al livello superiore per tenere conto delle dinamiche veloci delle ruote. Infine, la strategia di controllo viene testata in simulazione per quanto riguarda le prestazioni di inseguimento della traiettoria e di minimizzazione dell’energia, e successivamente su MircoAutoBox II montato sull’RCV-E per valutare le prestazioni in tempo reale.