Trails are essential transportation infrastructure supporting access to protected natural areas and providing recreation to hikers, runners, cyclists, equestrians, motorists, and many more worldwide. This research presents spatial studies intended to improve understanding of the environmental, managerial, and use-related factors that influence management of and physical and experiential conditions on long-distance hiking trails. The first study investigates a dataset from the Appalachian Trail (AT) to examine methods for using high resolution digital elevation models to measure terrain steepness near trails and along trails or potential trail routes. This analysis supports trail planning and assessment efforts because these terrain metrics strongly influence physical trail sustainability and are useful to evaluate the difficulty of travel along trails. The second study analyzes long-distance use patterns on the Pacific Crest Trail (PCT) as depicted by a computer model developed from a survey administered to long-distance hikers, trail counters, observations, and registers. In addition to describing use patterns, the process is intended to inform the selection of methods for visitor use monitoring in response to the complexity and level of controversy of management needs. The third study examines the spatial relationships between the PCT, a national scenic trail, and other congressionally designated land areas including wilderness, wild and scenic rivers, and national monuments and how this complexity is manifested in camping management strategies and impacts along the trail corridor. This analysis supports managing for the multiple congressional mandates across the PCT landscape and improves understanding and management of interagency transboundary travel on the trail. / Doctor of Philosophy / Trails are essential transportation infrastructure supporting access to protected natural areas and providing recreation to hikers, runners, cyclists, equestrians, motorists, and many more worldwide. This research presents spatial studies intended to improve understanding of the environmental, managerial, and use-related factors that influence management and physical and experiential conditions on long-distance hiking trails. The first study investigates a dataset from the Appalachian Trail (AT) to examine methods for using high resolution digital elevation models to measure terrain steepness near trails and along trails or potential trail routes to improve digital trail assessment and planning. The second study analyzes long-distance use patterns on the PCT as depicted by a computer model developed from a survey administered to long-distance hikers, trail counters, observations, and registers. The third study examines the complexity of managing transboundary long distance trails by quantifying the spatial relationships between the Pacific Crest Trail (PCT), a national scenic trail, and other congressionally designated land areas, and by reviewing camping impacts at high use locations on the trail corridor.

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

This thesis describes the preliminary design of a system for remote terrain exploration and environmental sampling on worlds with dense atmospheres. The motivation for the system is to provide a platform for long-term scientific studies of these celestial bodies. The proposed system consists of three main components: a buoyancy-driven glider, designed to operate at low altitude; a tethered energy harvester, extracting wind energy at high altitudes; and a base station to recharge the gliders. This system is self-sustaining, extracting energy from the planetary boundary layer. A nine degree of freedom vehicle dynamic model has been developed for the buoyancydriven glider. This model was used to illustrate anecdotal evidence of the stability and controllability of the system. A representative system was simulated to examine the energy harvesting concept. / Master of Science

Titre de l'écran-titre (visionné le 9 novembre 2023) / Les apprentis qui s'engagent dans le développement de leurs habiletés scripturales doivent mobiliser simultanément de très nombreuses connaissances liées notamment aux caractéristiques du genre de texte à écrire et à la syntaxe, et cela peut s'avérer complexe pour eux. Si c'est le cas pour un enfant tout-venant, ce l'est d'autant plus pour un enfant qui vit avec une surdité et qui peut avoir développé un retard de langage. En effet, un tel retard peut entrainer des difficultés dans l'apprentissage de l'écrit puisque celui-ci repose entre autres sur les connaissances élaborées à l'oral. Néanmoins, il est possible d'escompter qu'une intervention appropriée s'inscrivant dans une perspective développementale où le réel niveau de l'enfant est constamment situé et pris en compte peut favoriser le développement des compétences en écriture de l'enfant vivant avec une surdité. C'est dans ce contexte que s'inscrit la présente étude de cas qui vise à expérimenter une approche, d'écriture créative partagée (Sirois, 2022 ; Sirois et al., 2021 ; Sirois et al., accepté ; Sirois et al. 2012), auprès d'une élève du primaire vivant avec une surdité afin de la soutenir dans son apprentissage de l'écrit. Au quotidien, cette approche a été déployée auprès d'une élève âgée de 10 ans, scolarisée dans une approche oraliste, qui a mis de l'avant sa créativité, son imaginaire et ses représentations dans une démarche de coconstruction de récits avec l'étudiante-chercheure. Les interventions réalisées par l'étudiante chercheure ont été analysées sous l'angle de l'étayage apporté, plus particulièrement en ce qui concerne la macrostructure et la cohérence du texte ainsi que la syntaxe, et elles ont fait ressortir l'importance du soutien dans la zone de proche développement de l'élève prenant la forme de discussions, de questionnements et de propositions dans la planification et la mise à l'écrit du texte. Afin d'analyser le cheminement de l'élève dans l'apprentissage de l'écriture, des textes ont été produits sans soutien au début et à la fin de l'expérimentation. Au terme de l'intervention en écriture créative partagée, l'analyse de la production finale a mis en lumière la progression de l'enfant qui a réalisé un récit plus élaboré et cohérent, et contenant des phrases plus complexes que dans les productions initiales. L'approche expérimentée a donc été bénéfique au développement de la structuration du récit et de la syntaxe à l'écrit chez cette enfant. / Apprentices who engage in the development of their scriptural skills must simultaneously mobilize a significant amount of knowledge related in particular to the characteristics of the type of text to be written and to syntax. If this is the case for a young child, it is even more for a child who lives with deafness and who may have developed a language delay. Indeed, such a delay can lead to difficulties in learning to write since it is based, among other things, on knowledge of oral language. Nevertheless, it is possible to expect that an appropriate intervention, part of a developmental perspective where the real level of the child is constantly located and considered, can promote the development of writing skills of the child living with deafness. It is in this context that this case study fits, which aims to experiment shared creative writing (Sirois, 2022; Sirois et al., 2021; Sirois et al., accepted; Sirois et al. 2012) with an elementary school student living with deafness to support her learning of writing. Daily, this approach has been deployed with the student, putting her creativity, her imagination and her representations forward in a process of co-construction of texts with the undergraduate researcher. The interventions deployed by the undergraduate researcher were analyzed from the perspective of the support provided, more particularly about the macrostructure and the coherence of the text as well as the syntax, and they highlighted the importance of support in the zone of proximal development of the student in the form of discussions, questions and proposals in the planning and writing of the text. In order to analyze the progress of the student in writing, texts were produced at the beginning and at the end of the experiment. After three months of interventions in shared creative writing, the final production highlights the progress of the child who has produced a more elaborate and coherent story, and containing more complex sentences than in the initial productions. The experimented approach seems to have been beneficial in the development of the story's structure and syntax in writing for the child living with deafness.

This paper presents a new approach to the feature-matching problem for 3D reconstruction by taking advantage of GPS and IMU data, along with a prior calibrated stereo camera system. It is expected that pose estimates and calibration can be used to increase feature matching speed and accuracy. Given pose estimates of cameras and extracted features from images, the algorithm first enumerates feature matches based on stereo projection constraints in 2D and then backprojects them to 3D. Then, a grid search algorithm over potential camera poses is proposed to match the 3D features and find the largest group of 3D feature matches between pairs of stereo frames. This approach will provide pose accuracy to within the space that each grid region covers. Further refinement of relative camera poses is performed with an iteratively re-weighted least squares (IRLS) method in order to reject outliers in the 3D matches. The algorithm is shown to be capable of running in real-time correctly, where the majority of processing time is taken by feature extraction and description. The method is shown to outperform standard open source software for reconstruction from imagery. / Master of Science

Ground motions from earthquakes are known to be affected by earth's surface topography. Topographic effects are a result of several physical phenomena such as the focusing or defocusing of seismic waves reflected from a topographic feature and the interference between direct and diffracted seismic waves. This typically causes an amplification of ground motion on convex features such as hills and ridges and a de-amplification on concave features such as valleys and canyons. Topographic effects are known to be frequency dependent and the spectral accelerations can sometimes reach high values causing significant damages to the structures located on the feature. Topographically correlated damage pattern have been observed in several earthquakes and topographic amplifications have also been observed in several recorded ground motions. This phenomenon has also been extensively studied through numerical analyses. Even though different studies agree on the nature of topographic effects, quantifying these effects have been challenging. The current literature has no consensus on how to predict topographic effects at a site. With population centers growing around regions of high seismicity and prominent topographic relief, such as California, and Japan, the quantitative estimation of the effects have become very important. In this dissertation, we address this shortcoming by developing empirical models that predict topographic effects at a site. These models are developed through an extensive empirical study of recorded ground motions from two large strong-motion datasets namely the California small to medium magnitude earthquake dataset and the global NGA-West2 datasets, and propose topographic modification factors that quantify expected amplification or deamplification at a site. To develop these models, we required a parameterization of topography. We developed two types of topographic parameters at each recording stations. The first type of parameter is developed using the elevation data around the stations, and comprise of parameters such as smoothed slope, smoothed curvature, and relative elevation. The second type of parameter is developed using a series of simplistic 2D numerical analysis. These numerical analyses compute an estimate of expected 2D topographic amplification of a simple wave at a site in several different directions. These 2D amplifications are used to develop a family of parameters at each site. We study the trends in the ground motion model residuals with respect to these topographic parameters to determine if the parameters can capture topographic effects in the recorded data. We use statistical tests to determine if the trends are significant, and perform mixed effects regression on the residuals to develop functional forms that can be used to predict topographic effect at a site. Finally, we compare the two types of parameters, and their topographic predictive power. / Ph. D.

The purpose of this study was to describe the use of Cape Hatteras National Seashore from visitors and local residents of the Outer Banks, and to explore the differences in use for off-road vehicle (ORV) users and pedestrians within each of these user groups. During the summer of 1978, 598 visitors were randomly sampled at Cape Hatteras and sent mail-back questionnaires. Eighty percent of the 598 eligible respondents returned the questionnaire, providing half the data for this study. Four hundred thirty-two local residents were systematically sampled from phone books of residents of the Outer Banks of North Carolina, and sent mail-back questionnaires in the winter of 1978. Sixty percent of the 342 eligible respondents returned the questionnaire, providing the other half of the data used in this study. It was found that the ORV and pedestrian visitors used the seashore quite differently, visiting many locations in different proportions and participating in activities differently. Seasonal and experience-related differences were present. Local resident ORV owners and non-ORV owners were different in their use of Cape Hatteras for recreational purposes as well. The ORV owner was a much more active user of the seashore than the non-ORV owner. Many implications for planning and management of Cape Hatteras are suggested. Based upon the results obtained, no substantive conclusions can be made about whether user conflict exists between ORV and non-ORV users. / Master of Science

Autonomous navigation with high speed in rough terrain is one of the most challenging tasks for wheeled robots. To achieve mobility over this terrain, a high agility wheeled robot should adapt and react fast to optimally traverse this challenging environment. Therefore, this dissertation is geared towards the design and development of a novel reconfigurable wheeled robot paradigm for rough terrain applications. This research focuses on the design, modeling, analysis and control of the reconfigurable wheeled robot, TIGER, with an elastic actuated mechanism for improving the robot's dynamic stability on rough terrain by controlling the robot's ground clearance, body roll and pitch angles. The elastic actuated mechanism mainly consists of a linear actuator connected in series with a shock absorber. Four sets of the elastic actuated mechanism are used to create different robot configurations to adapt to the terrain. Three main aspects were considered in this research in order to extend the ability of the robot to effectively navigate in rough terrain. The first aspect focuses on designing an agile reconfigurable wheeled robot by including an elastic actuated mechanism for improving maneuverability, longitudinal/lateral stability, and rollover prevention. Robot agility, stability, and high speed have been considered during the design process. The new design provides different configuration modes. These configurations allow for controlling the robot's Center Of Mass (COM) height and optimally distribute the vertical force on each tire for enhancing the tractive efficiency, mobility and dynamic stability. The second aspect presents the robot kinematic and dynamic modeling and analysis. The robot dynamics model is represented with fourteen degrees of freedom (DOF), where the dynamic behaviors of the robot body, suspension system, forces and moments on the tires are included. The dynamic behavior is controlled using the linear actuators' position and speed as inputs to determine the resulting ground clearance, body roll, and pitch angles. Sensors are integrated onboard the robot to calculate the robot's states in real time for use in feedback control. The third aspect focuses on introducing a technique for estimating the robot state-space dynamic model and control the Elastic Actuated Mechanism (EAM) using only a noisy Inertial Measurement Unit (IMU) with COM position uncertainty. The simulation results show that the observer estimates the actual behavior of the robot with 95% accuracy and up to 20% COM uncertainty. The Root Mean Square (RMS) has been reduced by 21% for bounce, 51% for pitch and 50% for roll acceleration. / Ph. D. / Wheeled mobile robots are being used for rough terrain applications in the field of robotics as a practical solution to accomplish various tasks. Unfortunately, most of the wheeled robots are not able to perform high dynamically tasks with high speed in rough terrain due to complex suspension design, high power-to-weight ratio, high cost and complexity of controlling highly nonlinear model in real-time. Therefore, this dissertation is geared towards the design and development of a novel reconfigurable wheeled robot paradigm for rough terrain applications. This research focuses on the design, modeling, analysis and control of the reconfigurable wheeled robot, TIGER, with an elastic actuated mechanism for improving the robot’s dynamic stability on rough terrain by controlling the robot’s ground clearance, body roll and pitch angles. The elastic actuated mechanism mainly consists of a linear actuator connected in series with a shock absorber. Four sets of the elastic actuated mechanism are used to create different robot configurations to adapt to the terrain. Three main aspects were considered in this research in order to extend the ability of the robot to effectively navigate in rough terrain. The first aspect focuses on designing an agile reconfigurable wheeled robot by including an elastic actuated mechanism for improving maneuverability, longitudinal/lateral stability, and rollover prevention. Robot agility, stability, and high speed have been considered during the design process. The new design provides different configuration modes. These configurations allow for controlling the robot’s COM height and optimally distribute the vertical force on each tire for enhancing the tractive efficiency, mobility and dynamic stability. The second aspect presents the robot kinematic and dynamic modeling and analysis. The robot dynamics model is represented with fourteen degrees of freedom (DOF), where the dynamic behaviors of the robot body, suspension system, forces and moments on the tires are included. The dynamic behavior is controlled using the linear actuators’ position and speeds as inputs to determine the resulting ground clearance, body roll, and pitch angles. Sensors are integrated onboard the robot to calculate the robot’s states in real time for use in feedback control. The third aspect focuses on introducing a technique for estimating the robot state-space dynamic model and control the EAM using only a noisy IMU with COM position uncertainty. The simulation results show that the observer estimates the actual behavior of the robot with 95% accuracy and up to 20% COM uncertainty. The RMS has been reduced by 21% for bounce, 51% for pitch and 50% for roll acceleration.

The focus of this dissertation is to improve autonomous navigation in unstructured terrain conditions, with specific application to unmanned casualty extraction in disaster scenarios. Robotic systems are being widely employed for search and rescue applications, especially in disaster scenarios. But a majority of these are focused solely on the search aspect of the problem. This dissertation proposes a conceptual design of a Semi-Autonomous Victim Extraction Robot (SAVER) capable of safe and effective unmanned casualty extraction, thereby reducing the risk to the lives of first responders. In addition, the proposed design addresses the limitations of existing state-of-the-art rescue robots specifically in the aspect of head and neck stabilization as well as fast and safe evacuation. One of the primary capabilities needed for effective casualty extraction is reliable navigation in unstructured terrain conditions. Autonomous navigation in unstructured terrain, particularly for systems with tracked locomotion mode involves unique challenges in path planning and trajectory tracking. The dynamics of robot-terrain interaction, along with additional factors such as slip experienced by the vehicle, slope of the terrain, and actuator limitations of the robotic system, need to be taken into consideration. To realize these capabilities, this dissertation proposes a hybrid navigation architecture that employs a physics engine to perform fast and accurate state expansion inside a graph-based planner. Tracked skid-steer systems experience significant slip, especially while turning. This greatly affects the trajectory tracking accuracy of the robot. In order to enable efficient trajectory tracking in varying terrain conditions, this dissertation proposes the use of an active disturbance rejection controller. The proposed controller is capable of estimating and counter acting the effects of slip in real-time to improve trajectory tracking. As an extension of the above application, this dissertation also proposes the use of support vector machine architecture to perform terrain identification, solely based on the estimated slip parameters. Combining all of the above techniques, an overall architecture is proposed to assist and inform tele-operation of tracked robotic systems in unstructured terrain conditions. All of the above proposed techniques have been validated through simulations and experiments in indoor and simple outdoor terrain conditions. / Doctor of Philosophy / This dissertation explores ways to improve autonomous navigation in unstructured terrain conditions, with specific applications to unmanned casualty extraction in disaster scenarios. Search and rescue applications often put the lives of first responders at risk. Using robotic systems for human rescue in disaster scenarios can keep first responders out of danger. To enable safe robotic casualty extraction, this dissertation proposes a novel rescue robot design concept named SAVER. The proposed design concept consists of several subsystems including a declining stretcher bed, head and neck support system, and robotic arms that conceptually enable safe casualty manipulation and extraction based on high-level commands issued by a remote operator. In order to enable autonomous navigation of the proposed conceptual system in challenging outdoor terrain conditions, this dissertation proposes improvements in planning, trajectory tracking control and terrain estimation. The proposed techniques are able to take into account the dynamic effects of robot-terrain interaction including slip experienced by the vehicle, slope of the terrain and actuator limitations. The proposed techniques have been validated through simulations and experiments in indoor and simple outdoor terrain conditions. The applicability of the above techniques in improving tele-operation of rescue robotic systems in unstructured terrain is also discussed at the end of this dissertation.

For realistic predictions of vehicle performance in off-road conditions, it is critical to incorporate in the simulation accurate representations of the variability of the terrain profile. It is not practically feasible to measure the terrain at a sufficiently large number of points, or, if measured, to use such data directly in the simulation. Dedicated modeling techniques and computational methods that realistically and efficiently simulate off-road operating conditions are thus necessary. Many studies have been recently conducted to identify effective and appropriate ways to reduce experimental data in order to preserve only essential information needed to re-create the main terrain characteristics, for future use. This thesis focuses on modeling terrain profiles using the finite difference approach for solving linear second-order stochastic partial differential equations. We currently use this approach to model non-stationary terrain profiles in two dimensions (i.e., surface maps). Certain assumptions are made for the values of the model coefficients to obtain the terrain profile through the fast computational approach described, while preserving the stochastic properties of the original terrain topology. The technique developed is illustrated to recreate the stochastic properties of a sample of terrain profile measured experimentally. To further analyze off-road conditions, stochastic soil properties are incorporated into the terrain topology. Soil models can be developed empirically by measuring soil data at several points, or they can be created by using mathematical relations such as the Bekker's pressure-sinkage equation for homogeneous soils. In this thesis, based on a previously developed stochastic soil model, the polynomial chaos method is incorporated in the soil model. In a virtual proving ground, the wheel and soil interaction has to be simulated in order to analyze vehicle maneuverability over different soil types. Simulations have been created on a surface map for different case studies: stepping with a rigid plate, rigid wheel and flexible wheel, and rolling of a rigid wheel and flexible wheel. These case studies had various combinations of stochastic or deterministic terrain profile, stochastic or deterministic soil model, and an object to run across the surface (e.g., deterministic terrain profile, stochastic soil model, rolling rigid wheel). This thesis develops a comprehensive terrain and soil simulation environment for off-road mobility studies. Moreover, the technique developed to simulate stochastic terrain profile can be employed to simulate other stochastic systems modeled by PDEs. / Master of Science