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Andresen, Simen. "Underwater Robotics : control of marine manipulator-vehicle systems." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25875.
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For using underwater vehicle-manipulator systems (UVMS) in a challenging envi-ronment, it is important to have a good mathematical description of the systemwhich accounts for disturbances such as ocean currents. The dynamics equation onmatrix form is therefore derived and different properties such as positive definitenessand skew symmetry is obtained. Based on the derived equations, a sliding modecontroller has been designed in order to track trajectories in the configuration spaceof the UVMS. The controller is robust when it comes to uncertainties in dynamicsparameters and uncertainties in ocean current, yielding global asymptotic stabilityas long as the uncertainties are bounded.Furthermore, a kinematic control system has been designed for facilitating humanoperation of a UVMS, by allowing an operator to only control the end effectormotion. The rest of the motion is then resolved through a weighted least-normpseudo inverse solution of the Jacobian matrix, in order to avoid mechanical jointlimits. Moreover, the vehicle’s motion is controlled by an event based algorithm tolimit the motion of the vehicle. This is done by attaching a 3D meshed polygon tothe vehicle frame and check if the end effector is inside or outside this mesh. Themesh then represents the space, relative to the manipulator, were the end effectoris fully dexterous. The vehicle will then be commanded to move only when the endeffector reaches the outside of the meshed polygon.A simulator has been implemented, based on the derived equations. The simula-tions of the UVMS, with the two controllers, yields good tracking results for trackingtrajectories both in the workspace of the end effector and in the configuration spaceof the UVMS.
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Ludwig, Peter M. "Formation control for multi-vehicle robotic minesweeping." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA380324.
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Sarafis, Ilias Thoma. "Electrically driven underwater manipulator for remote operated vehicles." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262585.
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Pérez, Soler Javier. "Visibility in underwater robotics: Benchmarking and single image dehazing." Doctoral thesis, Universitat Jaume I, 2017. http://hdl.handle.net/10803/432778.
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Dealing with underwater visibility is one of the most important challenges in autonomous underwater robotics. The light transmission in the water medium degrades images making the interpretation of the scene difficult and consequently compromising the whole intervention. This thesis contributes by analysing the impact of the underwater image degradation in commonly used vision algorithms through benchmarking. An online framework for underwater research that makes possible to analyse results under different conditions is presented. Finally, motivated by the results of experimentation with the developed framework, a deep learning solution is proposed capable of dehazing a degraded image in real time restoring the original colors of the image.Una de las dificultades más grandes de la robótica autónoma submarina es lidiar con la falta de visibilidad en imágenes submarinas. La transmisión de la luz en el agua degrada las imágenes dificultando el reconocimiento de objetos y en consecuencia la intervención. Ésta tesis se centra en el análisis del impacto de la degradación de las imágenes submarinas en algoritmos de visión a través de benchmarking, desarrollando un entorno de trabajo en la nube que permite analizar los resultados bajo diferentes condiciones. Teniendo en cuenta los resultados obtenidos con este entorno, se proponen métodos basados en técnicas de aprendizaje profundo para mitigar el impacto de la degradación de las imágenes en tiempo real introduciendo un paso previo que permita recuperar los colores originales.
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Marut, Kenneth Joseph. "Underwater Robotic Propulsors Inspired by Jetting Jellyfish." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/64199.
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Underwater surveillance missions both for defense and civilian applications are continually demanding the need for unmanned underwater vehicles or UUVs. Unmanned vehicles are needed to meet the logistical requirements for operation over long distances, greater depths, long duration, and harsh conditions. In order to design UUVs that not only satisfy these needs but are also adaptive and efficient, there has been increasing interest in taking inspiration from nature. These biomimetic/bio-inspired UUVs are expected to provide significant improvement over the conventional propeller based vehicles by taking advantage of flexible bodies and smart actuation. In this thesis, jetting jellyfish were utilized as the inspiration to understand the fundamentals of this new form of propulsion and subsequently translate the understanding onto the engineered platform to validate the hypothesis and construct robust models. Jetting jellyfish species are generally smaller in dimensions than rowing jellyfish, consume lower energy for transport, and exhibit higher proficiency.
In the second chapter, a bio-inspired stationary jet propulsion mechanism that utilizes an iris diaphragm actuation system was developed. Detailed discussion is provided on the design methodology and factors playing the leading role in controlling the vortex formation. The propulsion mechanism was intended to mimic the morphological and deformation features of Sarsia sp. jellyfish that measures approximately 1 cm in diameter. The performance of experimental model was analyzed and modeled to elucidate the role of structure and fluid displacement.
Utilizing the results from Chapter 2, a free-swimming jellyfish-inspired robot (named JetPRo) was developed (also utilizing an iris diaphragm) in Chapter 3 and characterized for relevant propulsive metrics. A combination of theoretical modeling and experimental analysis was used to optimize the JetPRo's gait for maximum steady-state swimming velocity.
Next, an attempt was made towards creating a free-swimming jetting robot (named JP2) using a guided cable mechanism to achieve the desired actuation and improve the propulsion while simplifying the drive mechanism. Using JP2 robotic model, a systematic set of experiments were conducted and the results were used to refine the theory. Based upon the comprehensive computational analysis, an optimized swimming gait was predicted and then validated.
A modular robot inspired by siphonophores was developed and initial efforts were made in laying down the foundation for understanding of this complex locomotion mechanism. Siphonophores are colonial organisms consisting of several jetting bodies attached to a central stem. An experimental model was developed mimicking the multimodal swimming propulsion utilized by Siphonophores. Several swimming gaits inspired by the natural animal were replicated and the preliminary performance of the experimental model was quantified. Using these results, an analysis is presented towards further improving the design and assembly of a siphonophore-inspired robot.Master of Science
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Nicholson, John W. "Autonomous optimal rendezvous of underwater vehicles." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FNicholson.pdf.
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El-Fakdi, Sencianes Andrés. "Gradient-based reinforcement learning techniques for underwater robotics behavior learning." Doctoral thesis, Universitat de Girona, 2011. http://hdl.handle.net/10803/7610.
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Darrerament, l'interès pel desenvolupament d'aplicacions amb robots submarins autònoms (AUV) ha crescut de forma considerable. Els AUVs són atractius gràcies al seu tamany i el fet que no necessiten un operador humà per pilotar-los. Tot i això, és impossible comparar, en termes d'eficiència i flexibilitat, l'habilitat d'un pilot humà amb les escasses capacitats operatives que ofereixen els AUVs actuals. L'utilització de AUVs per cobrir grans àrees implica resoldre problemes complexos, especialment si es desitja que el nostre robot reaccioni en temps real a canvis sobtats en les condicions de treball. Per aquestes raons, el desenvolupament de sistemes de control autònom amb l'objectiu de millorar aquestes capacitats ha esdevingut una prioritat. Aquesta tesi tracta sobre el problema de la presa de decisions utilizant AUVs. El treball presentat es centra en l'estudi, disseny i aplicació de comportaments per a AUVs utilitzant tècniques d'aprenentatge per reforç (RL). La contribució principal d'aquesta tesi consisteix en l'aplicació de diverses tècniques de RL per tal de millorar l'autonomia dels robots submarins, amb l'objectiu final de demostrar la viabilitat d'aquests algoritmes per aprendre tasques submarines autònomes en temps real. En RL, el robot intenta maximitzar un reforç escalar obtingut com a conseqüència de la seva interacció amb l'entorn. L'objectiu és trobar una política òptima que relaciona tots els estats possibles amb les accions a executar per a cada estat que maximitzen la suma de reforços totals. Així, aquesta tesi investiga principalment dues tipologies d'algoritmes basats en RL: mètodes basats en funcions de valor (VF) i mètodes basats en el gradient (PG). Els resultats experimentals finals mostren el robot submarí Ictineu en una tasca autònoma real de seguiment de cables submarins. Per portar-la a terme, s'ha dissenyat un algoritme anomenat mètode d'Actor i Crític (AC), fruit de la fusió de mètodes VF amb tècniques de PG.A considerable interest has arisen around Autonomous Underwater Vehicle (AUV) applications. AUVs are very useful because of their size and their independence from human operators. However, comparison with humans in terms of efficiency and flexibility is often unequal. The development of autonomous control systems able to deal with such issues becomes a priority. The use of AUVs for covering large unknown dynamic underwater areas is a very complex problem, mainly when the AUV is required to react in real time to unpredictable changes in the environment. This thesis is concerned with the field of AUVs and the problem of action-decision. The methodology chosen to solve this problem is Reinforcement Learning (RL). The work presented here focuses on the study and development of RL-based behaviors and their application to AUVs in real robotic tasks. The principal contribution of this thesis is the application of different RL techniques for autonomy improvement of an AUV, with the final purpose of demonstrating the feasibility of learning algorithms to help AUVs perform autonomous tasks. In RL, the robot tries to maximize a scalar evaluation obtained as a result of its interaction with the environment with the aim of finding an optimal policy to map the state of the environment to an action which in turn will maximize the accumulated future rewards. Thus, this dissertation is based on the principals of RL theory, surveying the two main classes of RL algorithms: Value Function (VF)-based methods and Policy Gradient (PG)-based techniques. A particular class of algorithms, Actor-Critic methods, born of the combination of PG algorithms with VF methods, is used for the final experimental results of this thesis: a real underwater task in which the underwater robot Ictineu AUV learns to perform an autonomous cable tracking task.
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Nawrot, Michael T. "Conceptual design of a thrust-vectoring tailcone for underwater robotics." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/75671.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 66-67).
Thrust-vectoring on Autonomous Underwater Vehicles is an appealing directional-control solution because it improves turning radius capabilities. Unfortunately, thrust-vectoring requires the entire propulsion system be articulated in two degrees of freedom. Consequently, substantial internal volume must be utilized for this system, reducing payload and battery capacity. To combat this problem, an alternative thrust-vectoring system is desired for an existing vehicle. A number of alternative design strategies and concepts are explored herein. One design concept is then chosen and feasibility calculations are performed. Analysis of hydrodynamic loading, actuators, bearings, and structural components is conducted. The design is then reviewed and improvements are suggested.
by Michael T. Nawrot.
S.B.
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Lewis, Amy Jeannette. "Surveying Underwater Shipwrecks with Probabilistic Roadmaps." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2059.
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Almost two thirds of the Earth's surface is covered in ocean, and yet, only about 5% of it is mapped. There are an unknown amount of sunken ships, planes, and other artifacts hidden below the sea. Extensive search via boat and a sonar tow fish following a standard lawnmower pattern is used to identify sites of interest. Then, if a site has been determined to potentially be historically significant, the most common next step is a survey by either a human dive team or remotely operated vehicle. These are time consuming, error prone, and potentially dangerous options, but autonomous underwater vehicles (AUVs) are a possible solution.
This thesis introduces a system for automatically generating paths for AUVs to survey and map shipwrecks. Most AUVs include software to set a lawnmower path for a given region of ocean, and individualized paths can be set via specifying GPS encoded nodes for the AUV to pass through. This thesis presents an algorithm for generating an individualized path that permits the AUV, equipped with a camera to "see" all sides of a region of interest (i.e. a shipwreck). This allows the region of interest to be completely documented. Photogrammetry can then be used to reconstruct a three-dimensional model, but a path is needed to do so. Paths are generated by a probabilistic roadmap algorithm that uses a rapidly-exploring random tree to quickly cover the volume of exploration space and generate small maps with good coverage. The roadmap is constructed out of nodes, each having its own weight. The weight of a given node is calculated using an objective function which measures an approximate view coverage by casting rays from the virtual view and intersecting them with the region of interest. In addition, the weight of a node is increased if this node allows the AUV to see a new side of the region of interest. In each iteration of the algorithm, a node to expand off of is selected based off its location in space or its high weight, a new node with a given amount of freedom is generated, and then added to the roadmap. The algorithm has degrees of freedom in position, pitch, and yaw as well as the objective function to encourage the path to see all sides of the region of interest. Once all sides of the region of interest have been viewed, a path is determined to be complete.
The algorithm was tested in a virtual world where the virtual camera acted as the AUV. All of the images collected from our automatically generated path were used to create 3D models and point clouds using photogrammetry. To measure the effectiveness of our paths versus the pre-packaged lawnmower paths, the 3D models and point clouds created from our algorithm were compared to those generated from running a standard lawnmower pattern. The paths generated by our algorithm captured images that could be used in a 3D reconstruction which were more detailed and showed better coverage of the region of interest than those from the lawnmower pattern.
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Tena, Ruiz Ioseba Joaquin. "Enhanced concurrent mapping and localisation using forward-looking sonar." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/503.
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Budd, Johnathan. "SEATURTLE: Sustained Engagement Autonomous Tracking of Underwater RepTiLEs." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:14398555.
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While oceans cover the majority of our planet, these vast expanses remain relatively unexplored. Among the most interesting parts of the ocean are the shallow reef systems, which contain a huge amount of the planet’s biodiversity. The Sustained Engagement Autonomous Tracking of Underwater RepTiLEs or SEATURTLE is a low cost Autonomous Underwater Vehicle designed to carry out missions in these shallow environments. Its small displacement and precise movement make it ideal for navigating tight spaces, and its package of sensors make it easily adaptable to a variety of missions. For this project the vehicle was configured to autonomously track tagged objects underwater, using image recognition and the April Tags system.
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Kodogiannis, Vassilios S. "Neural network techniques for modelling and learning control of an underwater robotic vehicle." Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240643.
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Marco, Rider Jaime. "Optical communication with underwater snake robots : Design and implementation of an underwater wireless optical communication system." Thesis, Mittuniversitetet, Institutionen för elektronikkonstruktion, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-37803.
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Eelume AS is a norwegian company that develops autonomous underwater vehicles. Their flagship model is an underwater snake robot that performs inspection, maintenance and repair operations. For the time being, Eelume has been using acoustic communications between their AUV's and the docking station, but it has a big drawback: bandwidth. Eelume is interested in streaming live high-quality video from their AUV's to the docking station, which requires several megabits per second. As underwater radio frequency communications are not possible, wireless optical communications seem to be the best available alternative. The focus of this Thesis is to design an underwater wireless optical communications system that could be implemented on the Eelume AUV, although it is designed as a standalone embedded system that could be integrated into any other platform. Two prototypes were designed and tested through-air: a low-cost system featuring a PIN photodiode that can stream a 1.5 Mbps video signal over 0.5 meters and a high-sensitivity system featuring an avalanche photodiode that can stream a 2.5 Mbps video signal over 10.5 meters. Even if further underwater testing is needed and some inherent limitations in the design like the precise calibration or the ambient light noise effects could be mitigated. The results achieved by this high-sensitivity system demonstrates that a high-bandwidth mid-range underwater wireless optical communication system featuring a blue/green LED array as the light source and an avalanche photodiode as the photodetector is a viable solution for streaming live high-quality video over several meters even in very turbid seawaters.
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Plakas, Konstantinos. "Video sequence analysis for subsea robotics." Thesis, Heriot-Watt University, 2001. http://hdl.handle.net/10399/1186.
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Bewley, Michael Stuart. "Hierarchical Classification of Scientific Taxonomies with Autonomous Underwater Vehicles." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14511.
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Autonomous Underwater Vehicles (AUVs) have catalysed a significant shift in the way marine habitats are studied. It is now possible to deploy an AUV from a ship, and capture tens of thousands of georeferenced images in a matter of hours. There is a growing body of research investigating ways to automatically apply semantic labels to this data, with two goals. The task of manually labelling a large number of images is time consuming and error prone. Further, there is the potential to change AUV surveys from being geographically defined (based on a pre-planned route), to permitting the AUV to adapt the mission plan in response to semantic observations. This thesis focusses on frameworks that permit a unified machine learning approach with applicability to a wide range of geographic areas, and diverse areas of interest for marine scientists. This can be addressed through the use of hierarchical classification; in which machine learning algorithms are trained to predict not just a binary or multi-class outcome, but a hierarchy of related output labels which are not mutually exclusive, such as a scientific taxonomy. In order to investigate classification on larger hierarchies with greater geographic diversity, the BENTHOZ-2015 data set was assembled as part of a collaboration between five Australian research groups. Existing labelled data was re-mapped to the CATAMI hierarchy, in total more than 400,000 point labels, conforming to a hierarchy of around 150 classes. The common hierarchical classification approach of building a network of binary classifiers was applied to the BENTHOZ-2015 data set, and a novel application of Bayesian Network theory and probability calibration was used as a theoretical foundation for the approach, resulting in improved classifier performance. This was extended to a more complex hidden node Bayesian Network structure, which permits inclusion of additional sensor modalities, and tuning for better performance in particular geographic regions.
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Tunuguntla, Sai S. "On Finding the Location of an Underwater Mobile Robot Using Optimization Techniques." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36822.
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This research aims at solving an engineering design problem encountered in the field of robotics using mathematical programming techniques. The problem addressed is an indispensable part of designing the operation of Ursula, an underwater mobile robot, and involves finding its location as it moves along the circumference of a nuclear reactor vessel. The study has been conducted with an intent to aid a laser based global positioning system to make this determination.
The physical nature of this problem enables it to be conceptualized as a position and orientation determination problem. Ursula tests the weldments in the reactor vessel, and its position and orientation needs to be found continuously in real-time. The kinematic errors in the setup and the use of a laser based positioning system distinguish this from traditional position and orientation determination problems. The aim of this research effort is to construct a suitable representative mathematical model for this problem, and to design and compare various solution methodologies that are computationally competitive, numerically stable, and accurate.Master of Science
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Yuen, Nicholas Y. "Communication on limited-mobility underwater sensor networks." Scholarly Commons, 2013. https://scholarlycommons.pacific.edu/uop_etds/232.
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More than 70% of Earth's surface is covered by water. Earth's underwater world holds many exciting forms of life and undiscovered possibilities. It is sometimes referred to as "The Unexplored Frontier." We still do not fully understand the entirety of what happens in this mysterious world. The field of underwater sensor networks is a means of monitoring these environments. However, underwater sensor networks are still fraught with challenges; one of the main challenges being communication. In this thesis we look to improve communication in underwater sensor networks. We expand a simulation environment that models node to node communication in an underwater sensor network that utilizes AquaNodes. We address issues with the first iteration of the environment, expand it to include packet-loss for acoustic communication, and make the addition of three dimensional topologies. We found that acoustic packet-loss had a larger impact on the energy consumption of the communication algorithms with more acoustic communication and three dimensional topologies do not affect the communication algorithms. In addition to expanding the simulation environment we also explore using UAVs as a means of extracting data out of underwater sensor network. We conduct field experiments to characterize radio communication, develop an energy model to understand the energy limitations of an UAV, and develop overall policies for using an UAV with an underwater sensor network that utilizes AquaNodes. We learned that node to node radio communication range on the surface of the water had shorter ranges than on land. We also learned that node to UAV communication range was dependant on the altitude of the UAV. Overall, we found that using an UAV as a data mule was a viable method of extracting data out of certain underwater sensor network configurations.
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García, Sánchez Juan Carlos. "Towards a predictive interface for the specification of intervention tasks in underwater robotics." Doctoral thesis, Universitat Jaume I, 2021. http://dx.doi.org/10.6035/14101.2021.93456.
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Robots play a critical role in our everyday lives, performing tasks as diverse as maintenance, surveillance, exploration in harsh environments, or search and rescue operations. Concerning the different environments where they operate, the submarine is one of those that has increased its activity the most. Nowadays, there are three types of robots: ROVs, AUVs and HROVs. Despite the differences in structure and capabilities, there is a problem common to all three: the human-robot interaction has various deficiencies, and the user continues to play a central role from the point of view of decision-making. This thesis is focused on research related to human-robot interaction: the use of algorithms to assist the user during the mission specification (making the user interface easy to use), the exploration of a multimodal interface and the proposal for a robot control architecture (allowing change from autonomous to teleoperated, or vice versa).Los robots desempeñan un papel fundamental en nuestra vida cotidiana, realizando tareas tan diversas como mantenimiento, vigilancia, exploración en entornos hostiles u operaciones de búsqueda y rescate. De entre todos los entornos donde actúan, el submarino es uno de los que más ha aumentado su actividad. Los tipos de robots utilizados son: ROVs, AUVs y HROVs. Existe un problema común a los tres: la interacción hombre-robot presenta diversas deficiencias y el usuario sigue jugando un papel central desde el punto de vista de la toma de decisiones. La presente tesis está centrada en la investigación relacionada con la interacción hombre-robot: el uso de algoritmos para asistir al usuario durante la especificación de la misión (haciendo que la interfaz de usuario sea fácil de usar), la exploración de una interfaz multimodal y la propuesta de una arquitectura de control del robot (permitiendo cambiar desde autónomo a teleoperado, o viceversa).
Programa de Doctorat en Informàtica
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McVicker, William D. "Mapping and Visualizing Ancient Water Storage Systems with an ROV -- An Approach Based on Fusing Stationary Scans within a Particle Filter." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/885.
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This paper presents a new method for constructing 2D maps of enclosed un- derwater structures using an underwater robot equipped with only a 2D scanning sonar, compass and depth sensor. In particular, no motion model or odometry is used. To accomplish this, a two step offline SLAM method is applied to a set of stationary sonar scans. In the first step, the change in position of the robot between each consecutive pair of stationary sonar scans is estimated using a particle filter. This set of pair wise relative scan positions is used to create an estimate of each scan’s position within a global coordinate frame using a weighted least squares fit that optimizes consistency between the relative positions of the entire set of scans. In the second step of the method, scans and their estimated positions act as inputs to a mapping algorithm that constructs 2D octree-based evidence grid maps of the site.
This work is motivated by a multi-year archaeological project that aims to construct maps of ancient water storage systems, i.e. cisterns, on the islands of Malta and Gozo. Cisterns, wells, and water galleries within fortresses, churches and homes operated as water storage systems as far back as 2000 B.C. Using a Remotely Operated Vehicle (ROV) these water storage systems located around the islands were explored while collecting video, still images, sonar, depth, and compass measurements. Data gathered from 5 different expeditions has produced maps of over 90 sites. Presented are results from applying the new mapping method to both a swimming pool of known size and to several of the previously unexplored water storage systems.
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Finbow, Maximillian. "The dynamic modelling and development of a controller for a general purpose remotely operated underwater vehicle." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20538.
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A preliminary mathematical model for the UCT SEAHOG Remotely operated underwater vehicle (ROV) is developed, including estimation of the rigid body, hydrodynamic and hydrostatic properties of the robot. A single state thruster model is developed and verified according to real life test data. A closed-loop speed controller is developed for the thruster module using a standard PI scheme and is implemented on an MSP430 microcontroller using software fixed-point algorithms. The complete ROV system is simulated in Simulink® in an open-loop configuration to gain insight into the expected motion from the vehicle. Controllers for depth and heading holding are designed using standard PID linearized control methods with gain scheduling and are then assessed within the complete system in a simulation environment. In addition, upgrades and maintenance are performed on the Power Pod, light and camera modules. Redesign, manufacture and testing of the SEAHOG junction box is performed, including a design solution to connect the tether power and fibre-optic lines at the surface and on the ROV. An extensive overhaul of the SEAHOG GUI is performed, utilising multicore processing architecture in LabVIEW and resulting in a user-orientated interface capable of controlling and monitoring all existing system data from the robot.
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Maalouf, Divine. "Contribution to nonlinear adaptive control of low inertia underwater robots." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20196/document.
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L'utilisation des véhicules sous-marins (ROV, AUV, gliders) s'est considérablement accrue ces dernières décennies, aussi bien dans le domaine de l'offshore ou de l'océanographie, que pour des applications militaires. Dans cette thèse, nous abordons le problème particulier de la commande des véhicules sous-marins à faible inertie et fort rapport puissance/inertie. Ces derniers constituent des systèmes fortement non linéaires, dont la dynamique est susceptible de varier au cours du temps (charge embarquée, caractéristiques des propulseurs, variation de salinité...) et qui sont très sensibles aux perturbations environnementales (chocs, traction sur l'ombilical...). Afin d'assurer des performances de suivi de trajectoire satisfaisantes, il est nécessaire d'avoir recours à une commande adaptative qui compense les incertitudes ou les variations des paramètres du modèle dynamique, mais également qui rejette les perturbations, telles que les chocs. A cette fin, nous proposons dans ce manuscrit, l'étude théorique et la validation expérimentale de plusieurs lois de commande pour véhicules sous-marins. Nous analysons tout d'abord des approches classiques dans ce domaine (commande PID et commande par retour d'état non linéaire), puis nous les comparons avec deux autres architectures de commande. La première est la commande adaptative L1 non linéaire, introduite en 2010 notamment pour la commande des véhicules aériens, et implémentée pour la première fois sur un véhicule sous-marin. Le découplage entre adaptation et robustesse permet l'utilisation de très grands gains d'adaptation (et donc une convergence plus rapide des paramètres estimés, sans aucune connaissance a priori), sans pour autant dégrader la stabilité. La seconde méthode, que nous proposons et qui constitue l'apport principal de cette thèse, est une évolution de la commande L1, permettant d'en améliorer les performances lors du suivi d'une trajectoire variable. Nous présentons une analyse de stabilité de cette commande, ainsi que sa comparaison expérimentale avec les autres lois de commande (commande PID, commande adaptative par retour d'état non linéaire et commande adaptative L1 standard). Ces expérimentations ont été réalisées sur un mini-ROV et plusieurs scenarii ont été étudiés, permettant ainsi d'évaluer, pour chaque loi, sa robustesse et son aptitude à rejeter les perturbationsUnderwater vehicles have gained an increased interest in the last decades given the multiple tasks they can accomplish in various fields, ranging from scientific to industrial and military applications. In this thesis, we are particularly interested in the category of vehicles having a high power to weight ratio. Different challenges in autonomous control of such highly unstable systems arise from the inherent nonlinearities and the time varyingbehavior of their dynamics. These challenges can be increased by the low inertia of this class of vehicles combined with their powerful actuation. A self tuning controller is therefore required in order to avoid any performance degradation during a specific mission. The closed-loop system is expected to compensate for different kinds of disturbances or changes in the model parameters. To solve this problem, we propose in this work the design,analysis and experimental validation of different control schemes on an underwater vehicle. Classical methods are initially proposed, namely the PID controller and the nonlinear adaptive state feedback (NASF) one, followed by two more advanced schemes based on the recently developed L1 adaptive controller. This last method stands out among the other developed ones in its particular architecture where robustness and adaptation are decoupled. In this thesis, the original L1 adaptive controller has been designed and successfullyvalidated then an extended version of it is proposed in order to deal with the observed time lags occurring in presence of a varying reference trajectory. The stability of this latter controller is then analysed and real-time experimental results for different operating conditions are presented and discussed for each proposed controller, assessing their performance and robustness
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Reis, Gregory M. "Augmented Terrain-Based Navigation to Enable Persistent Autonomy for Underwater Vehicles in GPS-Denied Environments." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3736.
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Aquatic robots, such as Autonomous Underwater Vehicles (AUVs), play a major role in the study of ocean processes that require long-term sampling efforts and commonly perform navigation via dead-reckoning using an accelerometer, a magnetometer, a compass, an IMU and a depth sensor for feedback. However, these instruments are subjected to large drift, leading to unbounded uncertainty in location. Moreover, the spatio-temporal dynamics of the ocean environment, coupled with limited communication capabilities, make navigation and localization difficult, especially in coastal regions where the majority of interesting phenomena occur. To add to this, the interesting features are themselves spatio-temporally dynamic, and effective sampling requires a good understanding of vehicle localization relative to the sampled feature.
Therefore, our work is motivated by the desire to enable intelligent data collection of complex dynamics and processes that occur in coastal ocean environments to further our understanding and prediction capabilities. The study originated from the need to localize and navigate aquatic robots in a GPS-denied environment and examine the role of the spatio-temporal dynamics of the ocean into the localization and navigation processes. The methods and techniques needed range from the data collection to the localization and navigation algorithms used on-board of the aquatic vehicles. The focus of this work is to develop algorithms for localization and navigation of AUVs in GPS-denied environments. We developed an Augmented terrain-based framework that incorporates physical science data, i.e., temperature, salinity, pH, etc., to enhance the topographic map that the vehicle uses to navigate. In this navigation scheme, the bathymetric data are combined with the physical science data to enrich the uniqueness of the underlying terrain map and increase the accuracy of underwater localization. Another technique developed in this work addresses the problem of tracking an underwater vehicle when the GPS signal suddenly becomes unavailable. The methods include the whitening of the data to reveal the true statistical distance between datapoints and also incorporates physical science data to enhance the topographic map.
Simulations were performed at Lake Nighthorse, Colorado, USA, between April 25th and May 2nd 2018 and at Big Fisherman's Cove, Santa Catalina Island, California, USA, on July 13th and July 14th 2016. Different missions were executed on different environments (snow, rain and the presence of plumes).
Results showed that these two methodologies for localization and tracking work for reference maps that had been recorded within a week and the accuracy on the average error in localization can be compared to the errors found when using GPS if the time in which the observations were taken are the same period of the day (morning, afternoon or night). The whitening of the data had positive results when compared to localizing without whitening.
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Smart, Royce Raymond, and roycesmart@hotmail com. "Evolutionary Control of Autonomous Underwater Vehicles." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20090331.143104.
Full textAbstract:
The goal of Evolutionary Robotics (ER) is the development of automatic processes for the synthesis of robot control systems using evolutionary computation. The idea that it may be possible to synthesise robotic control systems using an automatic design process is appealing. However, ER is considerably more challenging and less automatic than its advocates would suggest. ER applies methods from the field of neuroevolution to evolve robot control systems. Neuroevolution is a machine learning algorithm that applies evolutionary computation to the design of Artificial Neural Networks (ANN). The aim of this thesis is to assay the practical characteristics of neuroevolution by performing bulk experiments on a set of Reinforcement Learning (RL) problems. This thesis was conducted with the view of applying neuroevolution to the design of neurocontrollers for small low-cost Autonomous Underwater Vehicles (AUV). A general approach to neuroevolution for RL problems is presented. The is selected to evolve ANN connection weights on the basis that it has shown competitive performance on continuous optimisation problems, is self-adaptive and can exploit dependencies between connection weights. Practical implementation issues are identified and discussed. A series of experiments are conducted on RL problems. These problems are representative of problems from the AUV domain, but manageable in terms of problem complexity and computational resources required. Results from these experiments are analysed to draw out practical characteristics of neuroevolution. Bulk experiments are conducted using the inverted pendulum problem. This popular control benchmark is inherently unstable, underactuated and non-linear: characteristics common to underwater vehicles. Two practical characteristics of neuroevolution are demonstrated: the importance of using randomly generated evaluation sets and the effect of evaluation noise on search performance. As part of these experiments, deficiencies in the benchmark are identified and modifications suggested. The problem of an underwater vehicle travelling to a goal in an obstacle free environment is studied. The vehicle is modelled as a Dubins car, which is a simplified model of the high-level kinematics of a torpedo class underwater vehicle. Two practical characteristics of neuroevolution are demonstrated: the importance of domain knowledge when formulating ANN inputs and how the fitness function defines the set of evolvable control policies. Paths generated by the evolved neurocontrollers are compared with known optimal solutions. A framework is presented to guide the practical application of neuroevolution to RL problems that covers a range of issues identified during the experiments conducted in this thesis. An assessment of neuroevolution concludes that it is far from automatic yet still has potential as a technique for solving reinforcement problems, although further research is required to better understand the process of evolutionary learning. The major contribution made by this thesis is a rigorous empirical study of the practical characteristics of neuroevolution as applied to RL problems. A critical, yet constructive, viewpoint is taken of neuroevolution. This viewpoint differs from much of the reseach undertaken in this field, which is often unjustifiably optimistic and tends to gloss over difficult practical issues.
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Vidal, Garcia Eduard. "Online 3D view planning for autonomous underwater exploration." Doctoral thesis, Universitat de Girona, 2019. http://hdl.handle.net/10803/668814.
Full textAbstract:
Autonomous underwater vehicles are used nowadays in many applications. One of
the applications is mapping of a particular area of the ocean. Quen the robot
needs to cover the area of interest and no prior knowledge of the area to be
covered is avaialbe, a robotic exploration algorithm is used.
This thesis develops a robotic exploration algorithm for autonomous
underwater vehicles. The proposed algorithm allows the full exploration of a
2D or 3D environment, using acoustic sensors such as a scanning profiling sonar or a multibeam, and optical cameras.
The validity of the proposed algorithm is demonstrated through numerous
experiments carried out in different locations of the catalan coast, using
different vehicles and sensor suitesEls robots autònoms submarins s'utilitzen actualment en moltes aplicacions. Una d'elles és el mapeig d'una zona concreta de l'oceà. Quan el robot ha de cobrir la zona d'interès sense utilitzar informaciò prèvia sobre l'entorn a mapejar, s'utilitzen algorismes d'exploració robòtica. Aquesta tesi desenvolupa un algorisme d'exploració robòtica per a robots autònoms submarins. L'algorisme proposat permet explorar un entorn 2D o 3D en la seva totalitat, utilitzant sensors acústics, com per exemple un sonar perfilador o multifeix, i càmeres òptiques. La validesa de l'algorisme es demostra en experiments portats a terme a diferents entorns de la costa catalana, utilitzant múltiples vehicles i múltiples sensors
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Andersson, Adam. "Range Gated Viewing with Underwater Camera." Thesis, Linköping University, Department of Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-4244.
Full textAbstract:
The purpose of this master thesis, performed at FOI, was to evaluate a range gated underwater camera, for the application identification of bottom objects. The master thesis was supported by FMV within the framework of “arbetsorder Systemstöd minjakt (Jan Andersson, KC Vapen)”. The central part has been field trials, which have been performed in both turbid and clear water. Conclusions about the performance of the camera system have been done, based on resolution and contrast measurements during the field trials. Laboratory testing has also been done to measure system specific parameters, such as the effective gate profile and camera gate distances.
The field trials shows that images can be acquired at significantly longer distances with the tested gated camera, compared to a conventional video camera. The distance where the target can be detected is increased by a factor of 2. For images suitable for mine identification, the increase is about 1.3. However, studies of the performance of other range gated systems shows that the increase in range for mine identification can be about 1.6. Gated viewing has also been compared to other technical solutions for underwater imaging.
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Norström, Christer. "Underwater 3-D imaging with laser triangulation." Thesis, Linköping University, Department of Electrical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6125.
Full textAbstract:
The objective of this master thesis was to study the performance of an active triangulation system for 3-D imaging in underwater applications. Structured light from a 20 mW laser and a conventional video camera was used to collect data for generation of 3-D images. Different techniques to locate the laser line and transform it into spatial coordinates were developed and evaluated. A field- and a laboratory trial were performed.
From the trials we can conclude that the distance resolution is much higher than the lateral- and longitudinal resolution. The lateral resolution can be improved either by using a high frame rate camera or simply by using a low scanning speed. It is possible to obtain a range resolution of less than a millimeter. The maximum range of vision was 5 meters under water measured on a white target and 3 meters for a black target in clear sea water. These results are however dependent on environmental and system parameters such as laser power, laser beam divergence and water turbidity. A higher laser power would for example increase the maximum range.
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Sfard, Nathan. "Towards Autonomous Localization of an Underwater Drone." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1866.
Full textAbstract:
Autonomous vehicle navigation is a complex and challenging task. Land and aerial vehicles often use highly accurate GPS sensors to localize themselves in their environments. These sensors are ineffective in underwater environments due to signal attenuation. Autonomous underwater vehicles utilize one or more of the following approaches for successful localization and navigation: inertial/dead-reckoning, acoustic signals, and geophysical data. This thesis examines autonomous localization in a simulated environment for an OpenROV Underwater Drone using a Kalman Filter. This filter performs state estimation for a dead reckoning system exhibiting an additive error in location measurements. We evaluate the accuracy of this Kalman Filter by analyzing the effect each parameter has on accuracy, then choosing the best combination of parameter values to assess the overall accuracy of the Kalman Filter. We find that the two parameters with the greatest effects on the system are the constant acceleration and the measurement uncertainty of the system. We find the filter employing the best combination of parameters can greatly reduce measurement error and improve accuracy under typical operating conditions.
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Manii, Esfandiar. "AUTONOMOUS TRACKING AND FOLLOWING OF SHARKS WITH AN AUTONOMOUS UNDERWATER VEHICLE." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/729.
Full textAbstract:
This thesis presents the integration of an acoustic tracking system within an autonomous underwater AUV (AUV) to enable real-time tracking of sharks tagged with artificial acoustic sources. The tracking system consists of two hydrophones and a receiver unit that outputs a measurement of the relative angle to the tagged shark. Since only two hydrophones are used, the sign of the relative angle measurement is unknown. To overcome this ambiguity, a particle filter algorithm was developed to estimate the position of the acoustic source. When combined with an active control system that drives vehicle to obtain different orientations with respect to the acoustic source, real-time autonomous localization, tracking, and following of a tagged shark is shown to be possible. Four types of ocean experiments were used to validate the system including: 1) AUV tracking of a stationary tag, 2) AUV tracking of a tagged kayak, 3) AUV tracking of a tagged AUV, and 4) AUV tracking of a tagged shark. These experiments were analyzed with respect to the localization error, associated error variance, and distance between the AUV and the tag. The final shark tracking experiments took place in SeaPlane Lagoon, Los Angeles, CA, where the AUV was able to autonomously track and follow a tagged Leopard Shark for several hours.
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Doolittle, Daniel Foster. "Automated Fish Species Classification using Artificial Neural Networks and Autonomous Underwater Vehicles." W&M ScholarWorks, 2003. https://scholarworks.wm.edu/etd/1539617813.
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Törnblom, Nils. "Underwater 3D Surface Scanning using Structured Light." Thesis, Uppsala universitet, Centrum för bildanalys, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-138205.
Full textAbstract:
In this thesis project, an underwater 3D scanner based on structured light has been constructed and developed. Two other scanners, based on stereoscopy and a line-swept laser, were also tested. The target application is to examine objects inside the water filled reactor vessel of nuclear power plants. Structured light systems (SLS) use a projector to illuminate the surface of the scanned object, and a camera to capture the surfaces' reflection. By projecting a series of specific line-patterns, the pixel columns of the digital projector can be identified off the scanned surface. 3D points can then be triangulated using ray-plane intersection. These points form the basis the final 3D model. To construct an accurate 3D model of the scanned surface, both the projector and the camera need to be calibrated. In the implemented 3D scanner, this was done using the Camera Calibration Toolbox for Matlab. The codebase of this scanner comes from the Matlab implementation by Lanman & Taubin at Brown University. The code has been modified and extended to meet the needs of this project. An examination of the effects of the underwater environment has been performed, both theoretically and experimentally. The performance of the scanner has been analyzed, and different 3D model visualization methods have been tested. In the constructed scanner, a small pico projector was used together with a high pixel count DSLR camera. Because these are both consumer level products, the cost of this system is just a fraction of commercial counterparts, which uses professional components. Yet, thanks to the use of a high pixel count camera, the measurement resolution of the scanner is comparable to the high-end of industrial structured light scanners.
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Carreras, Pérez Marc. "A proposal of a behavior-based control architecture with reinforcement learning for an autonomous underwater robot." Doctoral thesis, Universitat de Girona, 2003. http://hdl.handle.net/10803/7718.
Full textAbstract:
Aquesta tesi proposa l'ús d'un seguit de tècniques pel control a alt nivell d'un robot autònom i també per l'aprenentatge automàtic de comportaments. L'objectiu principal de la tesis fou el de dotar d'intel·ligència als robots autònoms que han d'acomplir unes missions determinades en entorns desconeguts i no estructurats. Una de les premisses tingudes en compte en tots els passos d'aquesta tesis va ser la selecció d'aquelles tècniques que poguessin ésser aplicades en temps real, i demostrar-ne el seu funcionament amb experiments reals. El camp d'aplicació de tots els experiments es la robòtica submarina.En una primera part, la tesis es centra en el disseny d'una arquitectura de control que ha de permetre l'assoliment d'una missió prèviament definida. En particular, la tesis proposa l'ús de les arquitectures de control basades en comportaments per a l'assoliment de cada una de les tasques que composen la totalitat de la missió. Una arquitectura d'aquest tipus està formada per un conjunt independent de comportaments, els quals representen diferents intencions del robot (ex.: "anar a una posició", "evitar obstacles",...). Es presenta una recerca bibliogràfica sobre aquest camp i alhora es mostren els resultats d'aplicar quatre de les arquitectures basades en comportaments més representatives a una tasca concreta. De l'anàlisi dels resultats se'n deriva que un dels factors que més influeixen en el rendiment d'aquestes arquitectures, és la metodologia emprada per coordinar les respostes dels comportaments. Per una banda, la coordinació competitiva és aquella en que només un dels comportaments controla el robot. Per altra banda, en la coordinació cooperativa el control del robot és realitza a partir d'una fusió de totes les respostes dels comportaments actius. La tesis, proposa un esquema híbrid d'arquitectura capaç de beneficiar-se dels principals avantatges d'ambdues metodologies.
En una segona part, la tesis proposa la utilització de l'aprenentatge per reforç per aprendre l'estructura interna dels comportaments. Aquest tipus d'aprenentatge és adequat per entorns desconeguts i el procés d'aprenentatge es realitza al mateix temps que el robot està explorant l'entorn. La tesis presenta també un estat de l'art d'aquest camp, en el que es detallen els principals problemes que apareixen en utilitzar els algoritmes d'aprenentatge per reforç en aplicacions reals, com la robòtica. El problema de la generalització és un dels que més influeix i consisteix en permetre l'ús de variables continues sense augmentar substancialment el temps de convergència. Després de descriure breument les principals metodologies per generalitzar, la tesis proposa l'ús d'una xarxa neural combinada amb l'algoritme d'aprenentatge per reforç Q_learning. Aquesta combinació proporciona una gran capacitat de generalització i una molt bona disposició per aprendre en tasques de robòtica amb exigències de temps real. No obstant, les xarxes neurals són aproximadors de funcions no-locals, el que significa que en treballar amb un conjunt de dades no homogeni es produeix una interferència: aprendre en un subconjunt de l'espai significa desaprendre en la resta de l'espai. El problema de la interferència afecta de manera directa en robòtica, ja que l'exploració de l'espai es realitza sempre localment. L'algoritme proposat en la tesi té en compte aquest problema i manté una base de dades representativa de totes les zones explorades. Així doncs, totes les mostres de la base de dades s'utilitzen per actualitzar la xarxa neural, i per tant, l'aprenentatge és homogeni.
Finalment, la tesi presenta els resultats obtinguts amb la arquitectura de control basada en comportaments i l'algoritme d'aprenentatge per reforç. Els experiments es realitzen amb el robot URIS, desenvolupat a la Universitat de Girona, i el comportament après és el seguiment d'un objecte mitjançant visió per computador. La tesi detalla tots els dispositius desenvolupats pels experiments així com les característiques del propi robot submarí. Els resultats obtinguts demostren la idoneïtat de les propostes en permetre l'aprenentatge del comportament en temps real. En un segon apartat de resultats es demostra la capacitat de generalització de l'algoritme d'aprenentatge mitjançant el "benchmark" del "cotxe i la muntanya". Els resultats obtinguts en aquest problema milloren els resultats d'altres metodologies, demostrant la millor capacitat de generalització de les xarxes neurals.
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Boardman, Michael Jay. "Multiple Robot Boundary Tracking with Phase and Workload Balancing." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/360.
Full textAbstract:
This thesis discusses the use of a cooperative multiple robot system as applied to distributed tracking and sampling of a boundary edge. Within this system the boundary edge is partitioned into subsegments, each allocated to a particular robot such that workload is balanced across the robots. Also, to minimize the time between sampling local areas of the boundary edge, it is desirable to minimize the difference between each robot’s progression (i.e. phase) along its allocated sub segment of the edge. The paper introduces a new distributed controller that handles both workload and phase balancing. Simulation results are used to illustrate the effectiveness of the controller in an Autonomous Underwater Vehicle (AUV) under ice edge sampling application. Successful results from experimentation with three iRobot(R) Creates are also presented.
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Kim, Andrew Y. "A Comparative Study of Feature Detection Methods for AUV Localization." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1852.
Full textAbstract:
Underwater localization is a difficult task when it comes to making the system autonomous due to the unpredictable environment. The fact that radio signals such as GPS cannot be transmitted through water makes autonomous movement and localization underwater even more challenging. One specific method that is widely used for autonomous underwater navigation applications is Simultaneous Localization and Mapping (SLAM), a technique in which a map is created and updated while localizing the vehicle within the map. In SLAM, feature detection is used in landmark extraction and data association by examining each pixel and differentiating landmarks pixels from those of the background. Previous research on the performance of different feature detection methods have been done in environments such as cisterns and caverns where the effects of the ocean are reduced. Our objective, however, is to achieves robust localization in the open ocean environment of the Cal Poly pier. This thesis performs a comparative study between different feature detection methods including Scale Invariant Feature Transform (SIFT), Speeded-Up Robust Features (SURF), and Oriented FAST and Rotated BRIEF (ORB) on different sensors. We evaluate the feature detection and matching performance of these algorithms in a simulated open-ocean environment.
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DI, VITO Daniele. "Planning and Control of Underwater Vehicle-Manipulator Systems." Doctoral thesis, Università degli studi di Cassino, 2020. http://hdl.handle.net/11580/75128.
Full textAbstract:
Robotics is increasingly attracting interest for more and more applications. In particular, underwater robotics is having a large development since the need of mineral resources is growing. The latter pushes to find out new deposits on the seabed. Therefore, the construction and the maintenance of underwater structures are necessary, e.g., submarine pipelines for carrying oil and gas. However, performing any task on the seabed is very dangerous for the man, for obvious reasons. Thus, several Autonomous Underwater Vehicles (AUVs), equipped with manipulators as well, have been implemented in recent years, aimed at physically substituting the man.
The control of Underwater Vehicles-Manipulator Systems (UVMSs) require full control of the vehicle. Indeed, cruise vehicles with rudder and stern are not suitable for carrying a manipulator since they are not able to counteract the interaction forces with the arm itself. Furthermore, for a rigid body moving in a fluid there exist several hydrodynamic effects acting on it. In particular, among the latter, the restoring generalized forces, which are gravity and buoyancy, and the ocean current are of major concern in designing the control law since they influence the steady-state position and orientation errors. Beyond Proportional-Integral-Derivative actions (PID), several adaptive control laws have been proposed in literature for compensating these effects. However, they all are designed starting from the dynamic models written either in the earth-fixed or in the vehicle-fixed frame, respectively. Nevertheless, some hydrodynamic terms are constant in earth-fixed frame, e.g., the restoring linear force, and some others are constant in the vehicle-fixed frame, e.g., the restoring moment. Thus, in this thesis work, a mixed earth/vehicle-fixed frame-based adaptive control able to build each dynamic compensation action in the proper reference frame is proposed. In particular, a reduced version has been derived within the aim to achieve null steady state error under modelling uncertainty and presence of ocean current with respect to a minimal number of parameters. Furthermore, the effects of including the thruster dynamics within the full-dimensional adaptive control are investigated. Simulations and comparisons with other control laws, such as PID, show the better performance of the proposed technique.
The proposed adaptive control law has been also tested within the EC-funded ROBUST Project with the interuniversity Center of Integrated Systems for the Marine Environment (ISME). The ROBUST system has been designed and implemented for performing sea bed material identification merging the capabilities of an AUV and a robotic manipulator with a LIBS (Laser Induced Breakdown Spectroscopy) sensor mounted on its end-effector. Thus, the adaptive technique has been used for the vehicle dynamic control.
Redundant systems can be exploited to perform multiple tasks simultaneously. For this purpose, the Multi-Task Priority (MTP) inverse kinematics algorithm can be used. As well known in literature, the latter is based on the Closed Loop Inverse Kinematics (CLIK) and allows to manage a prioritized hierarchy of equality-based tasks, which are control functions characterized by a specific desired value, e.g, position and orientation. In addition to the latter there exists another category of control functions which are named set-based tasks since their value can range between an upper and lower bound, respectively. One of the most common set-based tasks is for instance the obstacle avoidance. Indeed, the obstacle distance has to respect a lower bound (a minimum distance value). However, it can assume values greater than the latter.
Within the aim to control systems taking into account safety-related tasks, it is necessary to manage both equality and set-based tasks. Thus, the Set-Based Task-Priority Inverse Kinematics (SBTPIK) is proposed in this thesis. In particular, simulations and experiments with fixed and mobile base manipulators show the effectiveness of the algorithm as well as its integration into an assistive control framework for Remotely Operated Vehicles (ROVs).
The SBTPIK validity is also demonstrated through its application within the EC-funded DexROV Project with ISME. More in detail, a via-satellite remotely controlled UVMS has been developed to perform several kind of tasks such as oil and gas pipelines maintenance. Therefore, it has been necessary to manage multiple tasks ensuring the safety system. Thus, the SBTPIK has been applied to fulfill this objective.
The SBTPIK is a local motion control algorithm which efficiently performs on redundant systems since it handles real-time changes in the environment. However, it is prone to local minimum as any local motion controllers. Motion planners, on the other hand, are global methods and they are able to take into consideration the same system constraints. Nevertheless, their implementation often requires sacrificing some of the constraints or the redundancy exploitation. For this reason, in this thesis an approach based on merging the global and local planners in an effort to preserve the features of both ones is proposed. In particular, the global planner is implemented as a sampling-based algorithm which works in the reduced-dimensionality of the robot work space applying the Cartesian constraints only. The output trajectory is then checked against the inverse kinematics algorithm verifying the fulfillment of the other task constraints. The SBTPIK is then used also in real-time to ensure a reactive behaviour. During the movement, the motion planner runs in background
to adapt to changes in the environment, human presence or, in general, to continuously optimize the path. The proposed method has been simulated within the DexROV and ROBUST frameworks and experimentally validated in laboratory with a mockup represented by the Kinova Jaco2 7 DOFs (Degrees of Freedom) manipulator.
The SBTPIK framework has been successfully used in assistive applications as well, aimed at allowing users with severe motion disabilities to perform manipulation tasks that may help in daily-life operations. Tests have been performed using the Kinova Jaco2 7 DOFs manipulator operated via a P300-based Brain Computer Interface (BCI). More in detail, the P300 paradigm is based on the P300 potential which is a component of the Event Related Potentials (ERPs), i.e., a fluctuation in the EEG generated by the electrophysiological response to a significant sensorial stimulus or event. In particular, the P300 consists of a positive shift in the EEG signal approximately 300-400ms after a task relevant stimulus. Thus, the user with motion disabilities can generate command through a proper P300-based Graphical Interface (GUI). It is worth noticing that the present thesis focuses on underwater robotics therefore the BCI topic is not discussed in this work.
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Carrera, Viñas Arnau. "Robot learning applied to autonomous underwater vehicles for intervention tasks." Doctoral thesis, Universitat de Girona, 2017. http://hdl.handle.net/10803/450868.
Full textAbstract:
The interest in performing underwater tasks using Autonomous Underwater
Vehicles (AUVs) has been growing over the past few years. In this thesis, a
flexible framework for underwater interventions using a Learning by
Demonstration algorithm as a core has been developed. This algorithm allows
to the robot's user to transfer a skill or knowledge to the I-AUV using a
natural and intuitive form.
The developed framework for interventions has been tailored to the GIRONA 500
AUV in order to enable it to perform an underwater valve turning task under
different conditions. The GIRONA 500 has been equipped with a 4 DOF
Manipulator and a custom end-effector.
Throughout this thesis, the experiments developed have been carried out in a
mock-up scenario of a sub-sea installation with a valve panel. The difficulty
of the task has been increased gradually in order to test the new
improvements and the robustness in the proposed frameworkDurant les últimes dècades ha augmentat l’interès en la utilització de Vehicles Autònoms Submarins (AUVs) per realitzar tasques submarines. En aquesta tesis s’ha desenvolupat un marc de treball (framework) per a realitzar intervencions submarines amb AUVs basat en un algorisme d’Aprenentatge per Demostració (LbD). Aquest algorisme permet a l’usuari del robot transferir el seu coneixement al vehicle d’intervenció d’una forma natural. El framework desenvolupat s’ha ajustat a les característiques del GIRONA 500 AUV, amb l’objectiu de que pugui girar vàlvules submarines en diverses condicions. El GIRONA 500 s’ha equipat amb un braç robòtic i un element terminal personalitzat. Al llarg de tota la tesis s’ha utilitzat com entorn de desenvolupament un tanc d’aigua amb una recreació d’un escenari d’intervenció subaquàtic on s’han de girar determinades vàlvules d’un panell. El grau de dificultat de la tasca s’ha incrementat de forma gradual, per tal de poder provar les noves millores
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Ferrera, Maxime. "Monocular Visual-Inertial-Pressure fusion for Underwater localization and 3D mapping." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS089.
Full textAbstract:
Cette thèse aborde le problème de la localisation et cartographie 3D sous-marine en temps-réel. Dans le domaine de l'archéologie sous-marine, des véhicules téléopérés (ROV – Remotely Operated Vehicle) sont utilisés pour étudier les sites. La localisation et la cartographie précises en temps-réel sont des informations essentielles pour le pilotage manuel ou automatique de ces engins. Bien que plusieurs solutions de localisation existent, la plupart d'entre elles reposent sur l'utilisation de capteurs tels que les lochs Doppler (DVL – Doppler Velocity Log) ou les centrales inertielles à gyroscopes à fibre optique,qui sont très coûteux et peuvent être trop volumineux ou trop lourds pour les ROVs les plus petits. Les systèmes de positionnement acoustique sont également fréquemment utilisés en complément des systèmes précédents, mais leur fréquence d’échantillonnage et leur précision sont limitées.Dans cette thèse, nous étudions l'utilisation de capteurs à faible coût pour la localisation sous-marine.Notre étude porte sur l'utilisation d'une caméra monoculaire, d'un capteur de pression et d'une centrale inertielle MEMS (Micro ElectroMechanical System) à faible coût comme seul moyen de localisation et de cartographie en contexte archéologique sous-marin.Nous avons mené une évaluation de différentes méthodes de suivi de point d'intérêts sur des images affectées par des perturbations typiques rencontrées dans un contexte sous-marin. À partir des résultats obtenus nous avons développé une méthode monoculaire de SLAM (Simultaneous Localization and Mapping) robuste aux perturbations spécifiques de l’environnement sous-marin. Ensuite, nous proposons une extension de cette méthode pour intégrer étroitement les mesures du capteur de pression etde la centrale inertielle dans l’algorithme de SLAM. La méthode finale fournit une localisation très précise et s'exécute en temps-réel. En outre, un module de reconstruction 3D dense, en ligne, compatible avec une configuration monoculaire, est également proposé. Deux prototypes compacts et légers de ce système nt été conçus et utilisés pour enregistrer des jeux de données qui ont été publiés. En outre, ces prototypes ont été utilisés avec succès pour tester et valider en conditions réelles les algorithmes de localisation et de cartographie proposésThis thesis addresses the problem of real-time 3D localization and mapping in underwater environments.In the underwater archaeology field, Remotely Operated Vehicles (ROVs) are used to conduct deep-seasurveys and excavations. Providing both accurate localization and mapping information in real-time iscrucial for manual or automated piloting of the robots. While many localization solutions already existfor underwater robots, most of them rely on very accurate sensors, such as Doppler velocity logs or fiberoptic gyroscopes, which are very expensive and may be too bulky for small ROVs. Acoustic positioningsystems are also commonly used for underwater positioning, but they provide low frequencymeasurements, with limited accuracy.In this thesis, we study the use of low-cost sensors for accurate underwater localization. Our studyinvestigates the use of a monocular camera, a pressure sensor and a low-cost MEMS-IMU as the onlymeans of performing localization and mapping in the context of underwater archaeology.We have conducted an evaluation of different features tracking methods on images affected by typicaldisturbances met in an underwater context. From the results obtained with this evaluation, we havedeveloped a monocular Visual SLAM (Simultaneous Localization and Mapping) method, robust to thespecific disturbances of underwater environments. Then, we propose an extension of this method totightly integrate the measurements of a pressure sensor and an IMU in the SLAM algorithm. The finalmethod provides a very accurate localization and runs in real-time. In addition, an online dense 3Dreconstruction module, compliant with a monocular setup, is also proposed. Two lightweight and compactprototypes of this system have been designed and used to record datasets that have been publiclyreleased. Furthermore, these prototypes have been successfully used to test and validate the proposedlocalization and mapping algorithms in real-case scenarios
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Voisin-Denoual, Maxime. "Monocular Visual Odometry for Underwater Navigation : An examination of the performance of two methods." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229907.
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This thesis examines two methods for monocular visual odometry, FAST + KLT and ORBSLAM2, in the case of underwater environments.This is done by implementing and testing the methods on different underwater datasets. The results for the FAST + KLT provide no evidence that this method is effective in underwater settings. However, results for the ORBSLAM2 indicate that good performance is possible whenproperly tuned and provided with good camera calibration. Still, thereremain challenges related to, for example, sand bottom environments and scale estimation in monocular setups. The conclusion is therefore that the ORBSLAM2 is the most promising method of the two tested for underwater monocular visual odometry.Denna uppsats undersöker två metoder för monokulär visuell odometri, FAST + KLT och ORBSLAM2, i det särskilda fallet av miljöer under vatten. Detta görs genom att implementera och testa metoderna på olika undervattensdataset. Resultaten för FAST + KLT ger inget stöd för att metoden skulle vara effektiv i undervattensmiljöer. Resultaten för ORBSLAM2, däremot, indikerar att denna metod kan prestera bra om den justeras på rätt sätt och får bra kamerakalibrering. Samtidigt återstår dock utmaningar relaterade till exempelvis miljöer med sandbottnar och uppskattning av skala i monokulära setups. Slutsatsen är därför att ORBSLAM2 är den mest lovande metoden av de två testade för monokulär visuell odometri under vatten.
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Palmer, Jacob N. "Radio propagation analysis for improved UAV data muling of surfaced underwater sensor nodes." Scholarly Commons, 2015. https://scholarlycommons.pacific.edu/uop_etds/218.
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The present work examines waypoint selection and evaluation mechanisms for data muling water sensor nodes via unmanned air vehicle. We present a mathematical model for predicting signal strength with respect to distance and height using a two-ray propagation model in conjunction with the individual radiation patterns of transmitting and receiving antennas. Signal quality over space is then be used to select best waypoints. Packet reception rate is related to the received signal strength indicator through experimentation and serves as a data efficiency indicator. Both models are then used to gather performance metrics of several simple path planning schemes. Both hover-only and in-flight communication are compared. Packet reception rate limitations were found to dramatically limit the effectiveness of waypoint selection regardless of power efficiency.
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Hurtós, Vilarnau Natàlia. "Forward-looking sonar mosaicing for underwater environments." Doctoral thesis, Universitat de Girona, 2014. http://hdl.handle.net/10803/285086.
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Vehicle operations in underwater environments are frequently compromised by poor visibility conditions. In this thesis, we propose an end-to-end mosaicing framework tailored to the characteristics of forward-looking sonar imagery in order to build consistent overviews of planar underwater areas regardless of water visibility. Our solution targets versatility: it enables the generation of acoustic mosaics that involve roto-translational motions and comprise different vehicle tracklines, it is suitable for a wide range of scenarios, it can be applicable on data collected with minimally instrumented vehicles, and it allows both offline and real-time operation. To this end, we address the key problem of image registration on forward-looking sonar images and we provide solutions for the global alignment of the sonar frames along the trajectory as well as their blending into a smooth acoustic mosaic. To validate the full proposed framework, an extensive experimental section is reported showing successful results in relevant field applications.Freqüentment, les operacions amb vehicles en entorns submarins estan condicionades a la visibilitat de l’aigua. En aquesta tesi, proposem un sistema complet per a la construcció de mapes subaquàtics adaptat a les característiques dels sonars de visió frontal, per tal de construir mosaics d’imatges acústiques independentment de la visibilitat de l’aigua. La solució proposada permet la generació de mapes que involucren moviments roto-translacionals i múltiples transectes, és adequada per un ampli ventall d’escenaris i permet la generació de mosaics tant en mode post-processat com en temps real. Proposem un nou mètode per al registre d'imatges d'aquest tipus de sonar, així com també solucions per a dur a terme l'alineament global de les imatges al llarg d'una trajectòria i per a fusionar les imatges en un mosaic acústic. Per tal de validar el funcionament de tot el sistema es presenten experiments demonstrant resultats satisfactòris en el marc d'aplicacions reals.
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Galceran, Yebenes Enric. "Coverage path planning for autonomous underwater vehicles." Doctoral thesis, Universitat de Girona, 2014. http://hdl.handle.net/10803/133832.
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This thesis proposes new methods to find collision-free paths allowing an AUV to cover an area of the ocean floor with its sensors, which is known as coverage path planning. First, we propose a coverage path planning method to plan 2D, safe-altitude surveys which provides a principled way to account for obstacles in AUV survey planning. Its main advantage is that it minimizes redundant coverage when the vehicle navigates at constant depth, leading to shorter paths. Second, we provide a method to account for the uncertainty in the vehicle position estimates when planning 2D surveys. The method minimizes the uncertainty induced by the path and leads to better maps of the ocean floor as a result. Third, we provide a coverage path planning method suitable for inspecting areas of the ocean floor including 3D structures. The resulting coverage paths enable applications requiring close proximity and allow viewpoints for full 3D sensing of the structure. Moreover, by contrast to most existing methods, we provide two techniques to adapt the planned path in realtime using sensor information acquired on-line during the mission, rather than only planning the path off-line and relying on the unrealistic assumption of an idealized path execution by the AUV. The proposed methods are validated in simulation and in experiments with a real-world AUVAquesta tesi proposa nous mètodes per generar camins lliures de col·lisions per a vehicles submarins autònoms que permeten cobrir una àrea del fons de l'oceà usant els sensors del vehicle, tasca coneguda com a planificació de camins de cobertura. Primer, proposem un mètode de planificació de camins de cobertura per a planificar missions en un espai 2D a una altitud segura, proporcionant una manera fonamentada de tenir en compte obstacles en la planificació de missions per a vehicles submarins autònoms. L'avantatge principal del mètode proposat és que minimitza la cobertura redundant sorgida quan el vehicle navega a profunditat constant, obtenint camins més curts com a resultat. Segon, presentem un mètode per tenir en compte la incertesa de les estimacions de posició del vehicle durant la planificació de missions 2D. Aquest mètode minimitza la incertesa induïda pel camí i genera mapes més acurats del fons oceànic com a resultat. Tercer, presentem un mètode de planificació de camins de cobertura adequat per inspeccionar àrees del fons oceànic amb estructures 3D. Els camins de cobertura resultants permeten tasques que requereixen proximitat al fons i permeten una completa percepció 3D de les estructures d'interès. A més, a diferència de la majoria dels mètodes existents, proporcionem dues tècniques per adaptar els camins planificats en temps real utilitzant informació sensorial adquirida durant la missió, per contra de planificar només abans de l'execució de la missió i confiar en la poc realista assumpció d'una execució idealitzada del camí per part del vehicle. Els mètodes proposats han estat validats en simulació i en experiments amb un vehicle submarí autònom real
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Sosnowski, Stefan Georg [Verfasser], Kolja [Akademischer Betreuer] Kühnlenz, and Sandra [Akademischer Betreuer] Hirche. "Advances in Social and Underwater Robotics through Biomimetic Design / Stefan Georg Sosnowski. Gutachter: Kolja Kühnlenz ; Sandra Hirche. Betreuer: Kolja Kühnlenz." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1047185334/34.
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Palomer, Vila Albert. "3D underwater SLAM using sonar and laser sensors." Doctoral thesis, Universitat de Girona, 2018. http://hdl.handle.net/10803/665536.
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This thesis presents a SLAM algorithm using a multibeam echosounder, a new
1/2
underwater laser scanner for online 3D perception and two applications of
this new laser scanner: inspection and intervention.
The SLAM algorithm using a multibeam echosounder presents a new 3D
probabilistic registration method. The results of this registration method
are used as updates of an extended Kalman filter where the positions of the
different submaps is estimated.
This thesis also presents the model and calibration of the new underwater
laser scanner. This new sensor outperforms in resolution, precision and 3D
scanning frquency the acoustic multibeam and the state of the art laser
scanners.
Finally, this sensor in used in the inspection, using SLAM, of a submerged
structure, and in two manipulation experiments. One using path planning in an
unknown environment and the other one grasping an object at the bottom of the
water tankAquesta tesi presenta el desenvolupament d’un algorisme de SLAM utilitzant una sonda acústica multifeix, el desenvolupament d’un sensor d’escaneig làser per percepció 3D online i la aplicació d’aquest sensor en dos tasques submarines: inspecció i intervenció. L’algorisme de SLAM amb sonda acústica introdueix un nou mètode de registre probabilístic 3D. Els resultats d’aquest es fan servir com a actualitzacions d’un filtre estès de Kalman on s’estima la posició dels diferents submapes. La tesi presenta tant el modelat com el calibratge del nou escàner làser submarí. Aquest sensor incrementa, respecte el sensor acústic i els escàners làsers de l’estat de l’art, la resolució, precisió i freqüència d’escaneig 3D. Finalment aquest sensor s’utilitza en la inspecció, fent servir SLAM, d’una estructura submarina, i en la manipulació en un experiment de planificació de trajectòria en un entorn desconegut i en un d’agafar un objecte del fons del tanc d’aigua
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Bosch, Alay Josep. "Underwater navigation and mapping with an omnidirecional optical sensor." Doctoral thesis, Universitat de Girona, 2018. http://hdl.handle.net/10803/664260.
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Omnidirectional vision has received increasing interest during the last decade from the computer vision community. However, the use of omnidirectional cameras underwater is still very limited. In this thesis we propose several methods to create a reference resource for designing, calibrating and using underwater omnidirectional multi-camera systems (OMS). The first problem we address is their design and calibration. Next, we study stitching strategies to generate omnidirectional panoramas from individual images. Finally, we focus on potential underwater applications. We first explore the promising uses of omnidirectional cameras to create immersive virtual experiences and secondly, we demonstrate the capabilities of omnidirectional cameras as complementary sensors for the navigation of underwater robots. To validate all presented algorithms, two custom omnidirectional cameras were built and several experiments with divers and underwater robots have been carried out to collect the necessary data.Durant l'última dècada s'ha despertat un interès creixent per a la visió omnidireccional en l'àmbit de la visió per computador. Tot i això, l'ús de càmeres omnidireccionals submarines encara és molt limitat. En aquesta tesi doctoral hem creat un recurs de referència per al disseny, calibratge i ús de càmeres omnidireccionals submarines de tipus multi-càmera. El primer problema que tractem és el seu disseny i calibratge. Després ens centrem en l'estudi d’estratègies de combinació d'imatges per tal de generar imatges panoràmiques partint de múltiples imatges capturades per diferents càmeres. Finalment, ens centrem en les aplicacions potencials de les càmeres omnidireccionals submarines. Primer, explorem els prometedors usos de les càmeres per tal de crear experiències virtuals immersives. Després, demostrem les capacitats de les càmeres omnidireccionals com a sensors complementaris per a la navegació de robots. Per tal de validar tots els algoritmes presentats s'han dissenyat dues càmeres omnidireccionals i s'han realitzat múltiples experiments.
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Smith, Ryan N. "Geometric Control Theory and its Application to Underwater Vehicles." Thesis, University of Hawaii at Manoa, 2008. https://eprints.qut.edu.au/40141/1/40141.pdf.
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This dissertation is based on theoretical study and experiments which extend geometric control theory to practical applications within the field of ocean engineering. We present a method for path planning and control design for underwater vehicles by use of the architecture of differential geometry. In addition to the theoretical design of the trajectory and control strategy, we demonstrate the effectiveness of the method via the implementation onto a test-bed autonomous underwater vehicle.
Bridging the gap between theory and application is the ultimate goal of control theory. Major developments have occurred recently in the field of geometric control which narrow this gap and which promote research linking theory and application. In particular, Riemannian and affine differential geometry have proven to be a very effective approach to the modeling of mechanical systems such as underwater vehicles. In this framework, the application of a kinematic reduction allows us to calculate control strategies for fully and under-actuated vehicles via kinematic decoupled motion planning. However, this method has not yet been extended to account for external forces such as dissipative viscous drag and buoyancy induced potentials acting on a submerged vehicle. To fully bridge the gap between theory and application, this dissertation addresses the extension of this geometric control design method to include such forces.
We incorporate the hydrodynamic drag experienced by the vehicle by modifying the Levi-Civita affine connection and demonstrate a method for the compensation of potential forces experienced during a prescribed motion. We present the design method for multiple different missions and include experimental results which validate both the extension of the theory and the ability to implement control strategies designed through the use of geometric techniques.
By use of the extension presented in this dissertation, the underwater vehicle application successfully demonstrates the applicability of geometric methods to design implementable motion planning solutions for complex mechanical systems having equal or fewer input forces than available degrees of freedom. Thus, we provide another tool with which to further increase the autonomy of underwater vehicles.
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Bays, Matthew Jason. "Stochastic Motion Planning for Applications in Subsea Survey and Area Protection." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26763.
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This dissertation addresses high-level path planning and cooperative control for autonomous vehicles. The objective of our work is to closely and rigorously incorporate classication and detection performance into path planning algorithms, which is not addressed with typical approaches found in literature. We present novel path planning algorithms for two different applications in which autonomous vehicles are tasked with engaging targets within a stochastic environment. In the first application an autonomous underwater vehicle (AUV) must reacquire and identify clusters of discrete underwater objects. Our planning algorithm ensures that mission objectives are met with a desired probability of success. The utility of our approach is verified through field trials. In the second application, a team of vehicles must intercept mobile targets before the targets enter a specified area. We provide a formal framework for solving the second problem by jointly minimizing a cost function utilizing Bayes risk.Ph. D.
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Bender, Asher. "Autonomous Exploration of Large-Scale Natural Environments." Thesis, The University of Sydney, 2013. http://hdl.handle.net/2123/9450.
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This thesis addresses issues which arise when using robotic platforms to explore large-scale, natural environments. Two main problems are identified: the volume of data collected by autonomous platforms and the complexity of planning surveys in large environments. Autonomous platforms are able to rapidly accumulate large data sets. The volume of data that must be processed is often too large for human experts to analyse exhaustively in a practical amount of time or in a cost-effective manner. This burden can create a bottleneck in the process of converting observations into scientifically relevant data. Although autonomous platforms can collect precisely navigated, high-resolution data, they are typically limited by finite battery capacities, data storage and computational resources. Deployments are also limited by project budgets and time frames. These constraints make it impractical to sample large environments exhaustively. To use the limited resources effectively, trajectories which maximise the amount of information gathered from the environment must be designed. This thesis addresses these problems. Three primary contributions are presented: a new classifier designed to accept probabilistic training targets rather than discrete training targets; a semi-autonomous pipeline for creating models of the environment; and an offline method for autonomously planning surveys. These contributions allow large data sets to be processed with minimal human intervention and promote efficient allocation of resources. In this thesis environmental models are established by learning the correlation between data extracted from a digital elevation model (DEM) of the seafloor and habitat categories derived from in-situ images. The DEM of the seafloor is collected using ship-borne multibeam sonar and the in-situ images are collected using an autonomous underwater vehicle (AUV). While the thesis specifically focuses on mapping and exploring marine habitats with an AUV, the research applies equally to other applications such as aerial and terrestrial environmental monitoring and planetary exploration.
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Prados, Gutiérrez Ricard. "Image blending techniques and their application in underwater mosaicing." Doctoral thesis, Universitat de Girona, 2013. http://hdl.handle.net/10803/111333.
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The fusion of several images of the same scene into a single and larger composite is known as photo-mosaic. Unfortunately, the seams along image boundaries are often noticeable, due to photometrical and geometrical registration inaccuracies. Image blending is the merging step in which those artefacts are minimized. Processing bottlenecks and the lack of medium-specific processing tools have restricted underwater photo-mosaics to small areas despite the hundreds of thousands of square meters that modern surveys can cover. Producing these mosaics is difficult due to the challenging nature of the underwater environment and the image acquisition conditions. This thesis proposes strategies and solutions to tackle the problems of very large underwater optical surveys (Giga-mosaics), presenting contributions in the image preprocessing, enhancing and blending steps, resulting in an improved visual quality in the final photo-mosaicLa unió de diverses imatges d’una mateixa escena en una d’única i més gran és coneguda com a foto-mosaic. Malauradament, els límits de les imatges són habitualment perceptibles, degut a imprecisions en els registres fotomètric i geomètric. La fusió d'imatges és l'etapa del procés d'unió a la qual aquests artefactes són minimitzats. Els colls d'ampolla en el processament i la manca d'eines específiques pel tractament del medi han restringint els foto-mosaics submarins a àrees reduïdes, malgrat que els estudis actuals poden cobrir centenars de milers de m2. . La producció d'aquests mosaics és complexa donada la naturalesa del medi subaquàtic i les condicions d'adquisició de les imatges. Aquesta tesi proposa estratègies i solucions per afrontar el problema de la generació de foto-mosaics submarins de grans dimensions (Giga-mosaics), i presenta contribucions en les etapes de preprocessament, realçat i fusió d’imatges, donant lloc a una qualitat visual millorada del foto-mosaic final
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Leborne, François. "Contributions à la commande de bras manipulateurs de robot sous-marin pour la manipulation à grande profondeur d'échantillons biologiques déformables." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS044/document.
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Dans le cadre de la collecte sous-marine d'échantillons biologiques et minéraux pour la recherche scientifique par un robot sous-marin équipé de bras manipulateurs, ce projet de thèse a pour but principal le développement de nouvelles techniques de manipulation des échantillons, plus fiables, permettant d'en assurer l'intégrité physique et leur exploitabilité par les chercheurs. Les nouvelles techniques de manipulation proposées prennent en compte l'actionnement particulier des nouveaux bras électriques sous-marins équipant les engins récents, afin d'augmenter la précision du positionnement des outils embarqués par le manipulateur. Un outil amovible, compliant, et mesurant les efforts d'interaction entre les bras du sous-marin et leur environnement est aussi proposé, et des méthodes permettant de tirer partie des caractéristiques de cet outil sont développées et testées expérimentalement. L'engin sous-marin hybride HROV Ariane, équipé de deux bras électriques hétérogènes, offre la plateforme opérationnelle pour la validation expérimentale des solutions proposéesThe research carried out in the scope of this doctorate degree aims to develop innovative techniques to improve the collection of biological and mineral samples underwater using robotic manipulators. The end goal is to enhance the handling by robotic means in order to maximise sample quality provided to marine scientists. The proposed techniques are based on an in-depth analysis of the robotic arm actuators used in most recent underwater intervention vehicles, in order to improve the accuracy of the positionning of the tools held by the manipulator arms. An instrumented tool has also been developed with the aim to measure the reaction forces and adapt the interaction between the arm's end-effector and its environment to improve samples handling. These methods and the other contributions described in this thesis have been experimentally validated using Ifremer's hybrid-ROV Ariane equipped with two electrically actuated heterogeneous robotic arms
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Mallios, Angelos. "Sonar scan matching for simultaneous localization and mapping in confined underwater environments." Doctoral thesis, Universitat de Girona, 2014. http://hdl.handle.net/10803/134727.
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This thesis presents the development of a localization and mapping algorithm for an autonomous underwater vehicle (AUV). It is based on probabilistic scan matching of raw sonar scans within a pose-based simultaneous localization and mapping(SLAM) frameworkAquesta tesis presenta el desenvolupament d’un algoritme de localització i mapeig per un vehicle submarí autònom (AUV). L’algoritme es basa en tècniques probabilístiques de scan matching utilitzant scans de sonar dins un sistema de localització i construcció simultània de mapes (SLAM) basat en posició
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Youakim, Isaac Dina Nagui. "Advanced underwater vehicle manipulation through real-time motion planning." Doctoral thesis, Universitat de Girona, 2019. http://hdl.handle.net/10803/667910.
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A key challenge in autonomous mobile manipulation is the ability to
determine in real-time how to safely execute complex tasks when placed in an
unknown world. In response to those arising needs in the underwater domain,
this thesis focused on investigating the use of Motion Planning to increase
the autonomy of I-AUVs. we initially present a modeling and integration of
our I-AUV through MoveIt! framework, in the presence of virtual obstacles.
Then, we performed a deep analysis of the state of the art motion planning
techniques. Later, we identified planner specifications for underwater
intervention: Real-Time response for a high DOF system, Consistency,
Efficient trajectories in terms of safety, and system loose coupling. As a
consequence, we propose a new motion planning algorithm under the umbrella of
search-based method, that exploits the loose coupling nature of an I-AUV
while generating consistent, efficient, and safe trajectories in unknown
environments. The proposed algorithm has been validated both in simulation
and in a water tankLa capacitat de decidir en temps real com executar de manera segura uns tasca complexa en un entorn desconegut és un repte clau en la manipulació mòbil autònoma. Per abordar-ho, s'utilitzen habitualment tècniques de Planificació de Moviment tant en robots terrestres, mentre la seva aplicació a l'àmbit submarí roman inexplorada. Aquesta tesi doctoral avança l’estat de l’art investigant l'ús dels mètodes de Planificació de Moviment per augmentar l'autonomia dels I-AUVs per aplicacions d'Inspecció, Manteniment i Reparació executades en entorns desconeguts. A través del nostre treball, presentem la modelització i integració del nostre I-AUV en MoveIt!. Amb l’objectiu de fonamentar científicament l'elecció del mètode de Planificació de Moviment apropiat al nostre problema, s’ha dut a terme un anàlisi comparatiu de l'estat de l'art. L’anàlisi dels resultats ens ha permès establir les guies per a l'elecció de la tècnica més apropiada a les nostres necessitats. Posteriorment, s'han identificat les especificacions desitjades pels planificadors en aplicacions d’intervenció submarina: Resposta a temps real d'un sistema amb un elevat nombre de graus de llibertat, Consistència Generació de trajectòries eficients en termes de seguretat, així com l’ús de sistemes dèbilment acoblats. A partir dels resultats de l’anàlisi, es proposa un nou algoritme de planificació de moviment, dintre de la família dels mètodes de cerca, que explota l'acoblament dèbil entre el manipulador i el vehicle, generant, al mateix temps, trajectòries consistents, eficients i segures en entorns desconeguts