This study focuses on developing a better comprehension of the mobility of lightweight autonomous vehicles with varying locomotion platforms on sand. This research involves four segments. The first segment is a review of military criteria for the development of lightweight unmanned ground vehicles, followed by a review a review of current methodologies for evaluating the terramechanic (vehicle-ground interaction) mobility measures of heavyweight wheeled and tracked vehicles, and ending with a review of the defining properties of deformable terrain with specific emphasis on sand. These present a basis for understanding what currently defines mobility and how mobility is quantified for traditional heavyweight wheeled and tracked vehicles, as well as an understanding of the environment of operation (sandy terrain) for the lightweight vehicles in this study. The second segment involves the identification of key properties associated with the mobility and operation of lightweight vehicles on sand as related to given mission criteria, so as to form a quantitative assessment system to compare lightweight vehicles of varying locomotion platforms. A table based on the House of Quality shows the relationships—high, low, or adverse—between mission profile requirements and general performance measures and geometries of vehicles under consideration for use. This table, when combined with known values for vehicle metrics, provides information for an index formula used to quantitatively compare the mobility of a user-chosen set of vehicles, regardless of their methods of locomotion. This table identifies several important or fundamental terramechanics properties that necessitate model development for robots with novel locomotion platforms and testing for lightweight wheeled and tracked vehicles so as to consider the adaptation of counterpart heavyweight terramechanics models for use. The third segment is a study of robots utilizing novel forms of locomotion, emphasizing the kinematics of locomotion (gait and foot placement) and proposed starting points for the development of terramechanics models so as to compare their mobility and performance with more traditional wheeled and tracked vehicles. In this study several new autonomous vehicles—bipedal, self-excited dynamic tripedal, active spoke-wheel—that are currently under development are explored. The final segment involves experimentation of several lightweight vehicles and robots on sand. A preliminary experimentation was performed evaluating a lightweight autonomous tracked vehicle for its performance and operation on sand. A bipedal robot was then tested to study the foot-ground interaction with and sinkage into a medium-grade sand, utilizing a one of the first-developed walking gaits. Finally, a comprehensive set of experiments was performed on a lightweight wheeled vehicle. While the terramechanics properties of wheeled and tracked vehicles, such as the contact patch pressure distribution, have been understood and models have been developed for heavy vehicles, the feasibility of extrapolating them to the analysis of light vehicles is still under analysis. A wheeled all-terrain vehicle was tested for effects of sand gradation, vehicle speed, and vehicle payload on measures of pressure and sinkage in the contact patch, and preliminary analysis is presented on the sinkage of the wheeled all-terrain vehicle. These four segments—review of properties of sandy terrain and measures of and criteria for the mobility of lightweight vehicles operating on sandy terrain, the development of the comparison matrix and indexing function, modeling and development of novel forms of locomotion, and physical experimentation of lightweight tracked and wheeled vehicles as well as a bipedal robot—combine to give an overall picture of mobility that spans across different forms of locomotion. / Master of Science

O desempenho de um veículo de passeio em manobras de arrancada em aclives elevados é um fator muito importante a ser considerado no desenvolvimento de um novo projeto ou modificação de um projeto já existente. Este desempenho é influenciado por várias características do veículo, tais como: perfil e forma da curva de torque do motor, massa do veículo, relações de transmissão, tamanho do pneu entre outros. Este trabalho propõe uma metodologia de simulação para prever o desempenho de um veículo com tração dianteira em aclives elevados, através da utilização de um modelo de simulação desenvolvido na plataforma Matlab Simulink. Essa metodologia consiste na validação de um modelo de simulação capaz de representar todo o procedimento que envolve a saída de um veículo em um aclive elevado, levando em consideração a variação da rotação do motor, do pedal do acelerador, acoplamento da embreagem e o acionamento do freio de estacionamento. Uma medição real em veículo foi feita onde se registrou este comportamento e estes dados foram utilizados como valores de entrada no modelo de simulação. Para a correlação do modelo de simulação, foram utilizados os gráficos que representam a variação do espaço percorrido, velocidade e aceleração longitudinal, onde os resultados práticos e teóricos mostraram-se próximos mostrando que o modelo de simulação desenvolvido em MatLab/Simulink é uma opção a ser utilizada, principalmente nas fases inicias de projeto e para otimização de projetos já existentes. / The performance of a passenger vehicle maneuvering uphill sprint high is a very important factor to be considered in developing a new project or modifying an existing project. This performance is influenced by various characteristics of the vehicle, such as profile and shape of engine torque curve, vehicle weight, gear ratios, tire size and others. This paper proposes an analysis methodology to simulate the performance of a vehicle with front wheel drive in high slopes, through the use of a simulation model developed on the Matlab Simulink. This methodology consists in validating a simulation model capable of representing the entire procedure involving the removal of a vehicle in a high slope, taking into account the variation of engine speed, accelerator pedal, the clutch engaging and brake actuation parking. An actual measurement of vehicle was registered where this behavior and these data were used as input values in the simulation model. For the simulation model correlation, It was used the graphs represent the change in the space covered, vehicle speed and vehicle longitudinal acceleration, where the practical and theoretical results proved to be the next showing that the simulation model developed in Matlab/Simulink is an option be used, especially in the early stages of design and optimization of existing designs.

Automotive development has always been need-based and the product of today is an evolutionover several decades and a diversied technology application to deliver better products to theend users. Steady increase in the deployment of on-board electronics and software is characterizedby the demand and stringent regulations. Today, almost every function on-board a modernvehicle is either monitored or controlled electronically.One such specic demand for AB Volvo arose out of construction trucks in the US market. Usersseldom have/had a view of the operational boundaries of the drivetrain components, resultingin inappropriate use causing damage, poor traction and steering performance. Also, AB Volvo'sstand-alone traction assistance functions were not suciently capable to handle the vehicle useconditions. Hence, the goal was set to automate and synchronize the traction assistance devicesand software functions to improve the traction and steerability under a variety of road conditions.The rst steps in this thesis involved understanding the drivetrain components from design andoperational boundary perspective. The function descriptions of the various traction softwarefunctions were reviewed and a development/integration plan drafted. A literature survey wascarried out seeking potential improvement in traction from dierential locking and also its eectson steerability. A benchmarking exercise was carried out to identify competitor and suppliertechnologies available for the traction device automation task.The focus was then shifted to developing and validating the traction controller in a simulationenvironment. Importance was given to modeling of drivetrain components and renement ofvehicle behavior to study and understand the eects of dierential locking and develop a differentiallock control strategy. The modeling also included creating dierent road segments toreplicate use environment and simulating vehicle performance in the same, to reduce test timeand costs. With well-correlated vehicle performance results, a dierential lock control strategywas developed and simulated to observe traction improvement. It was then implemented onan all-wheel drive construction truck using dSPACE Autobox to test, validate and rene thecontroller.Periodic test sessions carried out at Hallered proving ground, Sweden were important to re-ne the control strategy. Feedback from test drivers and inputs from cross-functional teamswere essential to develop a robust controller and the same was tested for vehicle suitability andrepeatability of results. When comparing with the existing traction software functions, the integrateddierential lock and transfer case lock controller showed signicantly better performanceunder most test conditions. Repeatable results proved the reliability of developed controller.The correlation between vehicle test scenarios and simulation environment results indicated theaccuracy of software models and control strategy, bi-directionally.Finally, the new traction assistance device controller function was demonstrated within ABVolvo to showcase the traction improvement and uncompromising steerability.

Este trabalho aplica um procedimento para análise do desempenho de um autoveículo rodoviário (Kadett GS 2.0 da General Motors do Brasil), em aceleração e desaceleração (freagem), considerando o \"passeio do centro de gravidade\" e as \"restrições impostas pelo binômio pneumático x pavimento\". A dinâmica do processo de frenagem do veículo/exemplo é estudada, obtendo-se a desaceleração e o espaço percorrido, como função do \"passeio do centro de gravidade\" e duas \"restrições impostas pelo pneumático x pavimento\". Comparações teórico-experimentais são realizadas. Para o controle do processo de frenagem do veículo/exemplo, obtém-se uma \"função-transferência\" que muda continuamente o balanceamento das forças de frenagem nos eixos, utilizando-se, para isto, de sinais oriundos de um acelerômetro e de um sensor de peso instalados no veículo. Esta função otimiza o processo de frenagem para qualquer carregamento permissível do veículo e em qualquer nível de desaceleração (qualquer tipo de piso). Deste veículo obtêm-se os diagramas de rendimento, aceleração líquida para cada marcha engrenada, e, posteriormente, o \"tempo de aceleração\" e \"retomada de velocidade\", como função do \"passeio do centro de gravidade\" e das \"restrições impostas pelo pneumático x pavimento\". Comparações teórico-experimentais são também realizadas. Em todos os casos, foram obtidos bons resultados na comparação teórico-experimental, validando o modelo matemático elaborado e o procedimento de análise. / This work applies a procedure for the analysis of the performance of a road vehicle, (General Motors do Brasil, Kadett GS 2.0), in acceleration and deceleration (braking), which takes into consideration the centre of gravity envelope and the restrictions imposed by the tyre/surface relationship. A study is made of the dynamic braking process of the vehicle/example, and the deceleration and distance covered are obtained as a functions of the c.g. position and the tyre/surface relationship. Comparisons are made between theory and experiment. A transfer function is obtained for the control of the braking process of the vehicle/example, that continually changes the balance of the braking forces on the axles, thorugh the use of signals transmitted from an accelerometer (g - meter) and a sensor giving the installed weight of the vehicle. This function optimizes the braking process for any permissible vehicle load and deceleration level, for any type of surface. The performance diagrams, the acceleration in each gear, and, following these the acceleration time and time-to-return-to-normal-speed are obtained as functions of the position of the c.g. and the restrictions imposed by the tyre/surface relationship. Comparisons of theory with practice are also made. In all cases, comparisons between theory and practice give good results, validating the mathematical model and the analysis procedure.

Este trabalho aplica um procedimento para análise do desempenho de um autoveículo rodoviário (Kadett GS 2.0 da General Motors do Brasil), em aceleração e desaceleração (freagem), considerando o \"passeio do centro de gravidade\" e as \"restrições impostas pelo binômio pneumático x pavimento\". A dinâmica do processo de frenagem do veículo/exemplo é estudada, obtendo-se a desaceleração e o espaço percorrido, como função do \"passeio do centro de gravidade\" e duas \"restrições impostas pelo pneumático x pavimento\". Comparações teórico-experimentais são realizadas. Para o controle do processo de frenagem do veículo/exemplo, obtém-se uma \"função-transferência\" que muda continuamente o balanceamento das forças de frenagem nos eixos, utilizando-se, para isto, de sinais oriundos de um acelerômetro e de um sensor de peso instalados no veículo. Esta função otimiza o processo de frenagem para qualquer carregamento permissível do veículo e em qualquer nível de desaceleração (qualquer tipo de piso). Deste veículo obtêm-se os diagramas de rendimento, aceleração líquida para cada marcha engrenada, e, posteriormente, o \"tempo de aceleração\" e \"retomada de velocidade\", como função do \"passeio do centro de gravidade\" e das \"restrições impostas pelo pneumático x pavimento\". Comparações teórico-experimentais são também realizadas. Em todos os casos, foram obtidos bons resultados na comparação teórico-experimental, validando o modelo matemático elaborado e o procedimento de análise. / This work applies a procedure for the analysis of the performance of a road vehicle, (General Motors do Brasil, Kadett GS 2.0), in acceleration and deceleration (braking), which takes into consideration the centre of gravity envelope and the restrictions imposed by the tyre/surface relationship. A study is made of the dynamic braking process of the vehicle/example, and the deceleration and distance covered are obtained as a functions of the c.g. position and the tyre/surface relationship. Comparisons are made between theory and experiment. A transfer function is obtained for the control of the braking process of the vehicle/example, that continually changes the balance of the braking forces on the axles, thorugh the use of signals transmitted from an accelerometer (g - meter) and a sensor giving the installed weight of the vehicle. This function optimizes the braking process for any permissible vehicle load and deceleration level, for any type of surface. The performance diagrams, the acceleration in each gear, and, following these the acceleration time and time-to-return-to-normal-speed are obtained as functions of the position of the c.g. and the restrictions imposed by the tyre/surface relationship. Comparisons of theory with practice are also made. In all cases, comparisons between theory and practice give good results, validating the mathematical model and the analysis procedure.

[pt] O desempenho de veículos automotivos é um importante atributo a ser avaliado quando motores de combustão interna e novos combustíveis estão sendo desenvolvidos. A previsão desse parâmetro também é de suma importância, uma vez que os testes de desempenho de automóveis em pista requerem prazos de realização e altos custos com equipamentos, aluguel da pista, contratação de pessoas e deslocamento de veículos e combustíveis. Além disso, seus resultados são diretamente afetados por irregularidades na superfície da pista e variações nas condições climáticas, como pressão ambiente, temperatura, umidade do ar e velocidade do vento. Assim, este trabalho tem como objetivo utilizar os dados coletados em testes de bancada com um motor de combustão interna com a finalidade de modelar os testes de retomada de velocidade de um automóvel convencional leve. A metodologia proposta simula a força de tração nas rodas a partir do torque medido no dinamômetro do motor ou a partir das curvas de pressão no interior da câmara de combustão com o auxílio de modelos de atrito para motores de ignição por centelha. Para validar o modelo proposto, foi necessário realizar testes de retomada de velocidade com o carro em um dinamômetro de chassi. Além disso, foram utilizadas sete misturas diferentes de etanol e gasolina, e concluiu-se que o etanol anidro puro promoveu maior capacidade de aceleração na maioria dos experimentos, mas apresentou maior consumo de combustível. Os combustíveis hidratados reduziram o desempenho, mas melhoraram a eficiência global. As simulações demonstraram alta precisão em relação ao experimento, com média da diferença do tempo de recuperação da velocidade de 0,51 segundos e desvio padrão de 0,078. Além disso, as simulações de desempenho de aceleração tiveram erros menores que 5,25 por cento. Além disso, a realização desses testes em laboratório tem a vantagem de um maior controle das condições ambientais da sala e dos parâmetros de operação do motor. / [en] Vehicle performance is an important feature to be evaluated when internal combustion engines and new fuels are being developed. Predicting this parameter is also of great significance, once track testing requires long periods of time to be done and high costs with equipment, rental of the track, hiring people and displacement of vehicles and fuels. In addition, their results are directly affected by track surface irregularities and variations in weather conditions such as ambient pressure, temperature, air humidity and wind speed. Thus, this work aims to use collected data in bench tests with an internal combustion engine in order to modeling an automobile speed recovery time. The proposed methodology simulates the traction force on the wheels based on the measured torque in engine dynamometer or from the pressure curves inside the combustion chamber with the aid of friction models for spark ignition engines. In order to validate the proposed model, it became necessary to perform speed recovery tests with the car on a chassis dynamometer. Also, seven different mixtures of ethanol and gasoline were used, and it was concluded that pure anhydrous ethanol promoted a higher acceleration capacity in most of the experiments but it had higher fuel consumption. Hydrated fuels reduced performance but improved global efficiency. The simulations demonstrated a high precision in relation to the experiment, with a speed recovery time diference average of 0.51 seconds and standard deviation of 0.078. Also, the acceleration performance simulations had errors smaller than 5.25 percent. In addition, doing these tests in laboratory has the advantage of a greater control of the room ambient conditions and the engine operating parameters.

<p dir="ltr">This article-based research traces the evolution and advancements of vehicular aerodynamic concepts and emphasizes on the significance of vehicle aerodynamics for high-performance vehicles. The thesis further explores the scope of integrating advanced vehicle aerodynamic concepts into consumer vehicles. The thesis aims to point out the significant improvements achieved with the integration of active aerodynamic concepts in terms of both vehicle performance as well as efficiency figures for consumer vehicles. Additionally, exploring the scope for the development of these advanced active aerodynamic systems as third-party modifications is the secondary objective of the presented research. The thesis also highlights the development and integration of unique active aerodynamic systems featured in performance vehicles and analyzes the performance gains achieved using MATLAB program-based simulations supported by a graphical representation of analyzed output data. The study of Active aerodynamic systems for both performance/track-oriented and consumer vehicles remains to be the primary emphasis for the presented thesis.</p>