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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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Networked Digital Library of Theses and Dissertations.
Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
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Showing 361 to 368 of 368 (0.054 seconds)| 361 |
EXPANDING THE AUTONOMOUS SURFACE VEHICLE NAVIGATION PARADIGM THROUGH INLAND WATERWAY ROBOTIC DEPLOYMENTReeve David Lambert (13113279) 19 July 2022 (has links)
<p>This thesis presents solutions to some of the problems facing Autonomous Surface Vehicle (ASV) deployments in inland waterways through the development of navigational and control systems. Fluvial systems are one of the hardest inland waterways to navigate and are thus used as a use-case for system development. The systems are built to reduce the reliance on a-prioris during ASV operation. This is crucial for exceptionally dynamic environments such as fluvial bodies of water that have poorly defined routes and edges, can change course in short time spans, carry away and deposit obstacles, and expose or cover shoals and man-made structures as their water level changes. While navigation of fluvial systems is exceptionally difficult potential autonomous data collection can aid in important scientific missions in under studied environments.</p>
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<p>The work has four contributions targeting solutions to four fundamental problems present in fluvial system navigation and control. To sense the course of fluvial systems for navigable path determination a fluvial segmentation study is done and a novel dataset detailed. To enable rapid path computations and augmentations in a fast moving environment a Dubins path generator and augmentation algorithm is presented ans is used in conjunction with an Integral Line-Of-Sight (ILOS) path following method. To rapidly avoid unseen/undetected obstacles present in fluvial environments a Deep Reinforcement Learning (DRL) agent is built and tested across domains to create dynamic local paths that can be rapidly affixed to for collision avoidance. Finally, a custom low-cost and deployable ASV, BREAM (Boat for Robotic Engineering and Applied Machine-Learning), capable of operating in fluvial environments is presented along with an autonomy package used in providing base level sensing and autonomy processing capability to varying platforms.</p>
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<p>Each of these contributions form a part of a larger documented Fluvial Navigation Control Architecture (FNCA) that is proposed as a way to aid in a-priori free navigation of fluvial waterways. The architecture relates the navigational structures into high, mid, and low-level controller Guidance and Navigational Control (GNC) layers that are designed to increase cross vehicle and domain deployments. Each component of the architecture is documented, tested, and its application to the control architecture as a whole is reported.</p>
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AI based prediction of road users' intents and reactionsGurudath, Akshay January 2022 (has links)
Different road users follow different behaviors and intentions in the trajectories that they traverse. Predicting the intent of these road users at intersections would not only help increase the comfort of drive in autonomous vehicles, but also help detect potential accidents. In this thesis, the research objective is to build models that predicts future positions of road users (pedestrians,cyclists and autonomous shuttles) by capturing behaviors endemic to different road users. Firstly, a constant velocity state space model is used as a benchmark for intent prediction, with a fresh approach to estimate parameters from the data through the EM algorithm. Then, a neural network based LSTM sequence modeling architecture is used to better capture the dynamics of road user movement and their dependence on the spatial area. Inspired by the recent success of transformers and attention in text mining, we then propose a mechanism to capture the road users' social behavior amongst their neighbors. To achieve this, past trajectories of different road users are forward propagated through the LSTM network to obtain representative feature vectors for each road users' behaviour. These feature vectors are then passed through an attention-layer to obtain representations that incorporate information from other road users' feature vectors, which are in-turn used to predict future positions for every road user in the frame. It is seen that the attention based LSTM model slightly outperforms the plain LSTM models, while both substantially outperform the constant velocity model. A comparative qualitative analysis is performed to assess the behaviors that are captured/missed by the different models. The thesis concludes with a dissection of the behaviors captured by the attention module.
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The Study of Behavior of Passenger Car-Semi-Autonomous Trailer Connections under LoadYury Kuleshov (11187051) 27 July 2021 (has links)
<div><p>A variety of passenger car-trailer connections exist on the market. One specific type of the connections provides a tensile force measurement capability for the purpose of providing feedback for the semi-autonomous trailer’s control system. Semi-autonomous trailer is an innovative technology that can encourage drivers to use smaller vehicles for towing, which will contribute to restoration and improvement of urban infrastructure (NAE Grand Challenges for Engineering, 2020). The vehicle-semi-autonomous trailer connection’s safety concerns depend on multiple factors, but start with either a mechanical, or an electrical failure. The topic of safety of passenger car-semi-autonomous trailer connections is not well present in literature. The connections’ mechanical failures under load are in the focus of this work. The author addressed the following research question and the sub question. How do the existing “passenger car-trailer” connections with tensile force measurement capability compare to one another under load in terms of the possible failure? What is the failure mode of each of the compared connections? The author selected three prototypes from the literature, built three-dimensional (3D) models in SolidWorks 2018 and simulated the tests in the program’s add-on in accordance with the requirements of an industry standard on real-life testing of specific vehicle systems. The author compared the three prototypes by a number of different parameters. The research showed that none of the three existing prototypes are public road-ready in terms of safety. The study can be useful for future designers of passenger-car-semi-autonomous trailer connections.</p></div>
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Empirical Data Based Predictive Warning System on an Automated Guided Vehicle / Empiriskt databaserat predikterande varningsystem för självkörande truckarBlåberg, Anton, Lindahl, Gustav January 2022 (has links)
An Automated Guided Vehicle (AGV) must follow protective regulations to avoidcrashing into people when autonomously driving in industries. These safety norms require AGVs to enable protective fields, which perform hard braking when objects enter aspecific area in front of the vehicle. Warning fields, or warning systems, are similar fieldsthat decrease the speed of the AGV before objects enter the protective fields to enable asteadier driving. Today at Toyota Material Handling Manufacturing Sweden (TMHMS),warning systems have been implemented but the systems are too sensitive to objects outside of the AGVs path.The purpose of this thesis is to develop a predictive warning system based on empiricaldata from previous driving scenarios. By storing previous positions, the warning systemcould estimate a trajectory based on simple statistics and deploy speed limiting decisionsif objects appear in the upcoming predicted path.The predictive warning system was compared to the current warning system and adeactivated warning system setup in driving performance and driving dynamics. Performance was measured by measuring time to finish an industry-like test track and dynamicswas subjectively rated from a group of experienced AGV developers from TMHMS. Results showed that a predictive warning system drove the test track faster and with betterdynamics than the current warning system and the no warning system setup.Key findings are that a predictive warning system based on empirical data performedbetter in most cases but has some extra requirements to function. Firstly, the method require the AGV to mostly drive on previously driven paths to produce good results. Secondly the warning system requires a somewhat powerful on board computer to handlethe computations. Finally, the warning system requires spatial awareness of pose for thevehicle, as well as structure and shape for deployed protective fields.
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Uncontrolled intersection coordination of the autonomous vehicle based on multi-agent reinforcement learning.McSey, Isaac Arnold January 2023 (has links)
This study explores the application of multi-agent reinforcement learning (MARL) to enhance the decision-making, safety, and passenger comfort of Autonomous Vehicles (AVs)at uncontrolled intersections. The research aims to assess the potential of MARL in modeling multiple agents interacting within a shared environment, reflecting real-world situations where AVs interact with multiple actors. The findings suggest that AVs trained using aMARL approach with global experiences can better navigate intersection scenarios than AVs trained on local (individual) experiences. This capability is a critical precursor to achieving Level 5 autonomy, where vehicles are expected to manage all aspects of the driving task under all conditions. The research contributes to the ongoing discourse on enhancing autonomous vehicle technology through multi-agent reinforcement learning and informs the development of sophisticated training methodologies for autonomous driving.
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Evaluating the expressiveness of specification languages : for stochastic safety-critical systemsJamil, Fahad Rami January 2024 (has links)
This thesis investigates the expressiveness of specification languages for stochastic safety-critical systems, addressing the need for expressiveness in describing system behaviour formally. Through a case study and specification language enhancements, the research explores the impact of different frameworks on a set of specifications. The results highlight the importance of continuous development in the specification languages to meet the complex behaviours of systems with probabilistic properties. The findings emphasise the need for extending the chosen specification languages more formally, to ensure that the languages can capture the complexity of the systems they describe. The research contributes valuable insights into improving the expressiveness of specification languages for ensuring system safety and operational reliability.
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The autonomous crewmate : A sociotechnical perspective to implementation of autonomous vehicles in sea rescueLundblad, Oscar January 2020 (has links)
The usage of autonomous vehicles is starting to appear in several different domains and the domain of public safety is no exception. Wallenberg Artificial Intelligence, Autonomous Systems and Software Program (WASP) has created a research arena for public safety (WARA-PS) to explore experimental features, usages, and implementation of autonomous vehicles within the domain of public safety. Collaborating in the arena are several companies, universities, and researchers. This thesis examines, in collaboration with Combitech, a company partnered in WARA-PS, how the implementation of autonomous vehicles affects the sociotechnical system of a search and rescue operation during a drifting boat with potential castaways. This is done by creating a case together with domain experts, analyzing the sociotechnical system within the case using cognitive work analysis and then complementing the analyses with the unmanned autonomous vehicles of WARA-PS. This thesis has shown how the WARA-PS vehicles can be implemented in the case of a drifting boat with potential castaways and how the implementation affects the sociotechnical system. Based on the analyses and opinions of domain experts’ future guidelines has been derived to further the work with sociotechnical aspects in WARA-PS. / WARA-PS
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Interaction Design for Remote Control of Military Unmanned Ground VehiclesSaleh, Diana January 2021 (has links)
The fast technology development for military unmanned ground vehicles (UGVs) has led to a considerable demand to explore the soldier’s role in an interactive UGV system. This thesis explores how to design interactive systems for UGVs for infantry soldiers in the Swedish Armed Force. This was done through a user-centered design approach in three steps; (1) identifying the design drivers of the targeted military context through qualitative observations and user interviews, (2) using the design drivers to investigate concepts for controlling the UGV, and (3) create and evaluate a prototype of an interactive UGV system design. Results from interviews indicated that design drivers depend on the physical and psychological context of the intended soldiers. In addition, exploring the different concepts showed that early conceptual designs helped the user express their needs of a non-existing system. Furthermore, the results indicate that an interactive UGV system does not necessarily need to be at the highest level of autonomy in order to be useful for the soldiers on the field. The final prototype of an interactive UGV system was evaluated using a demonstration video, a Technology Acceptance Model (TAM), and semi-structured user interviews. Results from this evaluation suggested that the soldiers see the potential usefulness of an interactive UGV system but are not entirely convinced. In conclusion, this thesis argues that in order to design an interactive UGV system, the most critical aspect is the soldiers’ acceptance of the new system. Moreover, for soldiers to accept the concept of military UGVs, it is necessary to understand the context of use and the needs of the soldiers. This is done by involving the soldiers already in the conceptual design process and then throughout the development phases.
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