Mobility modeling is a critical step in the ground vehicle acquisition process for military vehicles. Mobility modeling tools, and in particular the NATO Reference Mobility Model (NRMM), have played a critical role in understanding the mission-level capabilities of ground vehicles. This understanding via modeling supports not only developers during early vehicle design but also decision makers in the field previewing the capabilities of ground vehicles in real-world deployments. Due to decades of field testing and operations, mobility modeling for traditional ground vehicles is well-understood; however, mobility modeling tools for evaluating autonomous mobility are sparse. Therefore, this dissertation proposes and derives a Reference Autonomous Mobility Model (RAMM). The RAMM leverages cutting-edge modeling and simulation tools to build a mobility model that serves as the mission-level mobility modeling tool currently lacking in the unmanned ground vehicle (UGV) community, thereby filling the current analysis gap in the autonomous vehicle acquisition cycle. The RAMM is built on (1) a thorough review of theories of verification and validation of simulations, (2) a novel framework for validating simulations of autonomous systems and (3) the mobility modeling framework already established by the NRMM. These building blocks brought to light the need for new, validated modeling and simulation (M&S) tools capable of simulating, at a highidelity, autonomous unmanned ground vehicle operations. This dissertation maps the derivation of the RAMM, starting with a history of verification of simulation models and a literature review of current autonomous mobility modeling methods. In light of these literature reviews, a new framework for V&V of simulations of autonomous systems is proposed, and the requirements for and derivation of the RAMM is presented. This dissertation concludes with an example application of the RAMM for route planning for autonomous UGVs. Once fully developed, the RAMM will serve as an integral part in the design, development, testing and evaluation, and ultimate fielding of autonomous UGVs for military applications.

Thesis (M.S.) -- University of Maryland, College Park, 1999. / Thesis research directed by Institute for Systems Research. "M.S. 99-6." Includes bibliographical references (leaves 75-78). Available also online as a PDF file via the World Wide Web.

Historiskt har soldater till fots burit sin personliga utrustning till fots. Den övriga utrustning som soldaten behövde transporterades ofta i vagnar dragna av olika dragdjur. Då stridstempot och framförallt framryckningshastigheten har ökat, har behovet av att bära med sig all nödvändig utrustning ökat. I takt med att nya system tillförts, har därmed också den burna vikten för den enskilde soldaten ökat. Undersökningen har genomförts som en komparativ studie av olika typer av obemannade markfarkoster, så kallade UGV-system, genom att deras möjligheter och begränsningar har analyserats och jämförts utifrån de krav som ställs av scenariot, och av den militära användaren, vid lösandet av en specifik taktisk uppgift. Kriterierna för jämförelse har med hjälp av konceptet militär nytta, framtaget av Andersson et al (2015), tagits fram ur scenariot. Studien kan konstatera att den militära nyttan med dessa UGV-system är att soldaternas egen rörlighet och uthållighet ökar, samtidigt som den skaderisk som tunga bördor innebär minskar. En soldat som inte är utmattad efter att ha burit tung utrustning har en högre stridsberedskap och agerar med större skärpa. Förbandens operativa rörlighet och uthållighet ökar också och beroende på vilket UGV-system som används återfinns olika grader av militär nytta. / Historically, soldiers on foot have carried their personal equipment. Other equipment that the soldier needed was often transported in wagons drawn by different beasts of burden. As the high operational tempo, and above all, forward speed has increased, the need to carry all necessary equipment also has grown. And, as new systems have been added, the load to carry for the individual soldier has thus increased. The survey has been conducted as a comparative study of different types of unmanned ground vehicles, so-called UGV systems, by analyzing their possibilities and limitations based on the requirements of the scenario and also the requirements by the military user in solving a specific tactical task. The criteria for comparison have been developed from the scenario using the concept of military utility, developed by Andersson et al. (2015). The study concludes that the military benefits connected to the UGV systems are that the individual mobility and endurance of the soldiers increases, and that the risk of injuries from carrying heavy loads decreases. A soldier not exhausted from carrying heavy loads has a higher combat preparedness and acts with greater focus. The operational mobility and endurance of the unit also increases and, depending on which UGV systems are used, different degrees of military benefit are to be found.

[pt] Foi desenvolvido neste trabalho um conjunto de procedimentos computacionais com o objetivo de estudar o comportamento da dinâmica de veículos terrestres. Utilizando recursos de armazenamento em banco de dados, programas de simulação de modelos dinâmicos e geração de animações gráficas são possível analisar o comportamento dos veículos, representados por modelos matemáticos consagrados ou que estejam sendo desenvolvidos. A característica mais importante da estrutura computacional implementada neste trabalho é o conceito de modularidade, ou seja, diversos modelos dinâmicos podem ser empregados e simulados, a partir da alteração ou adaptação de alguns módulos, sem que seja necessário modificar a estrutura computacional desenvolvida. O ambiente de banco de dados pode armazenar os parâmetros de veículos e pneus, além da descrição da pista e da trajetória a ser percorrida. O objetivo é que todas as inofrmações pertinentes ao estudo da dinâmica de veículos estejam contidas neste banco de dados, e que futuramente ele s torne um ponto de referencia para consultas diversas nesta área. Já o ambiente de animação gráfica permite representar a trajetória real percorrida pelo veículo, que depende de suas características dinâmicas, e os seus movimentos típicos, como as rotações em torno do eixo lateral e longitudinal, além de possibilitar a visualização do contexto no qual o veículo está inserido e o acompanhamento do percurso através de câmeras localizadas em posições escolhidas pelo usuário. / [en] It has been developed a set of computacional procedures with the objective of studying the synamic behavior of ground vehicles. By using database resources, dynamic simulation models and graphic animation generation it is possible to abnalyze vehicles behavior, represented by well known mathematical models or new ones. The most important charateristic about the developed computacional enviromment it is modulatity, which means that many different dynamics models can be employed and simulated with the daptation of some modules, without beng necessary to modify the main structure. The database environment can store the vehicles and tires parameters, and the track and tragetory description. The main obejective is to store on the database all the concerned information necessary to the study of vehicles dynamic. The graphical animation environment displays the simulated vehicle trajectory, which depends on vehicle dynamic characteristics and is typical movements, as the rotation around the lateral (pitch) and longitudinal axis. The graphical animation environment is also important to allow the visualization od the context where the vehicles are inserted, not mentioning the path tracking through video cameras pre configured by the user.

[pt] Neste trabalho são apresentados modelos para a dinâmica vertical e para a dinâmica lateral de veículos terrestres e desenvolve-se um procedimento para o aclopamento desses modelos. A simulação computacional é empregada para a análise e comparação do desempenho de veículos com suspensão convencional e ativa, quanto à dirigibilidade e estabilidade em curva. É realizado um estudo sobre a influencia dos parâmetros típicos dessas suspensões no comportamento das principais variáveis que caracterizam a dinâmica dos veículos, utilizando dados reais. / [en] In this work models of vertical and lateral vehicle dynamics are presented. A procedure to couple them is also developed. A numerical simulation is applied to analyze and compare the performance between a vehicle with a conventional suspension and another with an active suspension. An analysis, based on real data, of how some chacteristic parameters of those suspensions influence the behavior of the main variables that characterize the vehicle dynamics is also performed.

Unmanned vehicle systems, specifically Unmanned Air Vehicles (UAVs) and Unmanned Ground Vehicles (UGVs) have found potential use in both military and civilian applications. For many applications, unmanned vehicle systems are required to navigate in urban environments where obstacles with various types and sizes exist. The main contribution of this research is to offer vision-based path planning, collision avoidance, and target tracking strategies for Unmanned Air and Ground vehicles operating in urban environments. Two vision-based local-level frame mapping and planning techniques are first developed for Miniature Air Vehicles (MAVs). The techniques build maps and plan paths in the local-level frame of MAVs directly using the camera measurements without transforming to the inertial frame. Using a depth map of an environment obtained by computer vision methods, the first technique employs an extended Kalman Filter (EKF) to estimate the range, azimuth to, and height of obstacles, and constructs local spherical maps around MAVs. Based on the maps, the Rapidly-Exploring Random Tree (RRT) algorithm is used to plan collision-free Dubins paths. The second technique constructs local multi-resolution maps using an occupancy grid, which give higher resolution to the areas that are close to MAVs and give lower resolution to the areas that are far away. The maps are built using a log-polar representation. The two planning techniques are demonstrated in simulation and flight tests. Based on the observation that a camera does not provide accurate time-to-collision (TTC) measurements, two and three dimensional observability-based planning algorithms are explored. The techniques estimate both TTC and bearing using bearing-only measurements. A nonlinear observability analysis of state estimation process is conducted to obtain the conditions for complete observability of the system. Using the conditions, the observability-based planning algorithms are designed to minimize the estimation uncertainties while simultaneously avoiding collisions. The two dimensional planning algorithm parameterizes an obstacle using TTC and azimuth, and constructs local polar maps. The three dimensional planning algorithm parameterizes an obstacle using inverse TTC, azimuth, and elevation, and constructs local spherical maps. The algorithms are demonstrated in simulation. Lastly, a probabilistic path planning algorithm is developed for tracking a moving target in urban environments using UAVs and UGVs. The algorithm takes into account occlusions due to obstacles. It models the target using a dynamic occupancy grid and updates the target location using a Bayesian filter. Based on the target's current and probable future locations, a decentralized path planning algorithm is designed to generate suboptimal paths that maximize the sum of the joint probability of detection for all vehicles over a finite look-ahead horizon. Results demonstrate the planning algorithm is successful in solving the moving target tracking problem in urban environments.

No description available.

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

The problem of roadway navigation and obstacle avoidance for unmanned ground vehicles has typically needed very expensive sensing to operate properly. To reduce the cost of sensing, it is proposed that an algorithm be developed that uses a single visual camera to image the roadway, determine where the lane of travel is in the image, and segment that lane. The algorithm would need to be as accurate as current lane finding algorithms as well as faster than a standard k- means segmentation across the entire image. This algorithm, named IRIS, was developed and tested on several sets of roadway images. The algorithm was tested for its accuracy and speed, and was found to be better than 86% accurate across all data sets for an optimal choice of algorithm parameters. IRIS was also found to be faster than a k-means segmentation across the entire image. IRIS was found to be adequate for fulfilling the design goals for the algorithm. IRIS is a feasible system for lane identification and segmentation, but it is not currently a viable system. More work to increase the speed of the algorithm and the accuracy of lane detection and to extend the inherent lane model to more complex road types is needed. IRIS represents a significant step forward in the single camera roadway perception field. / Master of Science

Veículos autônomos são objeto de crescente estudo em todo o mundo. Face à Engenharia de Transportes, é tema que deve provocar uma revolução nas próximas décadas, pois é concreta a tendência ao uso destes veículos na sociedade. Podem se citar como grandes beneficiados a segurança, a logística, o fluxo de trânsito, o meio ambiente e também os portadores de deficiências. Com o objetivo de fazer um veículo atingir um ponto com coordenadas conhecidas de forma autônoma, uma plataforma veicular terrestre em escala foi utilizada, a qual recebeu um sistema computacional micro controlado e tecnologias para proporcionar mobilidade através de motores elétricos para tração e servo-motores para direcionamento; posicionamento por satélite através de receptor GNSS e bússola eletrônica para orientação; sensoriamento por ultra-som para evitar colisões; e comunicação sem fio, a fim de se realizar remotamente monitoramento e instrução em tempo real através de um aplicativo para computador pessoal (PC). Foi desenvolvido um algoritmo de navegação que, fazendo uso dos recursos disponíveis, proporcionou autonomia ao veículo, de forma a navegar para pontos com coordenadas conhecidas sem controle humano. Os testes realizados visaram avaliar a capacidade de autonomia do veículo, a trajetória de navegação realizada e a acurácia de chegada aos pontos de destino. O veículo foi capaz de atingir os pontos em todos os testes realizados, sendo considerado funcional seu algoritmo de navegação e também os sistemas de mobilidade, posicionamento, sensoriamento e comunicação. / Autonomous vehicles are an on growing research target around the world. Face to Transports Engineering, it is a subject which is expected to make a revolution on the next decades. The great benefits are on security, logistic, traffic flow, environment and handicap. With the goal to make a vehicle navigate autonomously to known geodesics coordinates, a reduced scale terrestrial vehicular platform was used. This platform received a microcontrolled computational system and technologies to give it mobility, through electrical motors for traction and servo-motors for direction; satellite positioning, through a GNSS receiver and magnetic compass for orientation; ultrasound sensing in order to avoid collision; and wireless communication, in order to do remote monitoring and instruction at real time through a PC application. It was developed a navigation algorithm which, from the available resources, gave autonomy to the vehicle, in order to navigate to known geodesics coordinates without human control. The test set was intended to evaluate the autonomy capacity of the vehicle, the navigation trajectory that was done and the arrival accuracy to the destination points. The vehicle reached the destination points on all tests done, being evaluated as functional its navigation algorithm and also the mobility, positioning, sensing and communication systems.