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Controle robusto multivariável para um veículo submersível autônomo.; Multivariable robust control for an autonomous underwater vehicle.

Cutipa Luque, Juan Carlos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 02/03/2007 PT
Relevância na Pesquisa
96.58%
Este trabalho trata do controle dos movimentos de um Veículo Submersível Autônomo (VSA). Veículos submersíveis são difíceis de controlar devido à alta não linearidade de seus modelos, ao forte acoplamento de movimentos, ao desconhecimento de certas dinâmicas, às incertezas do próprio modelo, devido a distúrbios externos impostos pelo ambiente e devido ao ruído de sensores. A dificuldade de controle pode ser exacerbada quando o veículo é subatuado. Para realização deste trabalho foi escolhido um VSA do tipo torpedo, cujo modelo matemático disponível na literatura foi devidamente modificado para garantir uma melhor descrição de seus movimentos em seis graus de liberdade (6-GL). O modelo foi então validado através de simulações numéricas. Para a síntese dos controladores utilizou-se uma técnica de controle avançada. Mais especificamente, utilizou-se a abordagem do controle H1 para sistemas multivariáveis. Assim foram obtidos controladores centralizados capazes de superar o problema do forte acoplamento de movimentos. Técnicas de controle avançado permitem também considerar as informações disponíveis sobre perturbações, incertezas, ruídos e diferentes tipos de entrada já na fase de síntese, o que permite obter controladores com desempenho adequado numa ampla faixa de operação. Neste trabalho...

Sistema de controle ótimo para veículo submersível semi-autônomo.; Optimal control system for a semi-autonomous underwater vehicle.

Fernandes, Daniel de Almeida
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/06/2008 PT
Relevância na Pesquisa
76.51%
Este trabalho apresenta aspectos teóricos e práticos relevantes do desenvolvimento do Sistema de Navegação e Controle (SNC) a ser implementado em um Veículo Submarino Semi-Autônomo (VSSA), tipo não carenado e auto propelido, que está em desenvolvimento e construção na Escola Politécnica da USP, para a Petrobrás. Os três graus de liberdade horizontais são controlados para seguirem trajetórias pré-definidas, enviadas como sinais de referência para navegação por uma estação de apoio localizada na superfície, responsável pela guiagem do veículo. Os sinais de referência enviados são acústicos propagados pela água. A implementação física do SNC e o controle dos três graus de liberdade verticais não fazem parte do escopo deste trabalho. O SNC consiste em um controlador determinístico, um seguidor de trajetórias linear quadrático alimentado por um vetor de estados estimado assintoticamente. Por segurança, em caso de falha de algum sensor, e para filtrar ruídos nos sinais medidos, um estimador de estados de ordem plena é utilizado conjuntamente. Pela simplicidade de síntese e implementação, esta arquitetura de controle é considerada a melhor alternativa para capacitar o VSSA a executar os movimentos semi-autônomos desejados. As técnicas de controle utilizadas requerem a linearização do modelo matemático não-linear que descreve o comportamento dinâmico do veículo. O modelo é obtido de maneira simplificada. Os resultados são gerados por simulações com o modelo não-linear.; This work presents theoretical and practical aspects of the development of the Navigation and Control System (NCS) to be implemented into a Petrobras' Semi-Autonomous Underwater Vehicle (SAUV)...

Identificação e controle de um veículo submersível autônomo sub-atuado.; Identification and control of a sub-actuated autonomous underwater vehicle.

Cutipa Luque, Juan Carlos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 22/06/2012 PT
Relevância na Pesquisa
86.61%
O presente trabalho apresenta a descrição de um modelo matemático completo em seis graus de liberdade para um Veículo Submersível Autônomo (VSA) sub-atuado. Desenvolveram-se métodos de identificação de sistemas para identificar o modelo não linear do veículo. A fim de evitar problemas de divergência na estimação de parâmetros hidrodinâmicos do modelo, usou-se o método de transformação paramétrica. Usou-se o filtro estendido de Kalman como estratégia para o processo de estimação de parâmetros quando ruídos de natureza gaussiana estavam presentes no modelo e nas medidas. Com o objetivo de estimar um maior número de parâmetros de uma só vez, empregou-se o método de máxima verossimilhança. Os experimentos mostraram que o filtro de Kalman responde bem à estimação de parâmetros específicos, porém, divergiu facilmente à estimação de múltiplos parâmetros. Uma alternativa que apresentou melhor desempenho foi o método de máxima verossimilhança. Testaram-se manobras circulares e de zig-zags para a obtenção de dados do veículo. Para os ensaios experimentais, utilizou-se o VSA sub-atuado do Laboratório de Veículos Não Tripulados (LVNT) do Departamento de Engenharia Mecatrônica da Escola Politécnica da Universidade de São Paulo. Validou-se o modelo identificado mediante o simulador do veículo. Numa segunda etapa...

Drag coefficient estimation model to simulate dynamic control of autonomous underwater vehicle (AUV) motion

Tan, K.; Lu, T.F.; Anvar, A.
Fonte: The Modelling and Simulation Society of Aust & NZ; Australia Publicador: The Modelling and Simulation Society of Aust & NZ; Australia
Tipo: Conference paper
Publicado em //2013 EN
Relevância na Pesquisa
96.69%
A vehicle dynamics model is crucial for the design of control system for an autonomous underwater vehicle (AUV). However, it is not a simple task to determine the hydrodynamic forces especially the drag coefficient involved for any particular vehicle model. This paper describes a novel approach to approximate the drag coefficient of any given vehicle shapes and sizes using fourth order regression method. The vehicle is subjected to pre-conditioning phase, where it can be done with CFD modelling or subject to simple experimental test within an open environment. In the pre-conditioning phase, the vehicle is required to navigate freely around custom test environment to obtain the drag profile in real-time. With sufficient data, using the correlation 3D graph of drag coefficient and the change in angles, the drag profile of any given shape can be determined. The accuracy of the model is based on the frequency of trial runs, as well as the efficiency of the vehicle’s on-board inertial navigation sensors. In this paper, the proposed approach is being demonstrated using ANSYS-CFX and the results obtained provide close approximation to the real drag coefficient. Therefore, the proposed novel approach is promising and can be used to find the drag coefficients for any given underwater vehicle at any conditions.; http://www.mssanz.org.au/modsim2013/index.html; Kuan M.Tan...

Cross body thruster control and modeling of a body of revolution Autonomous Underwater Vehicle

Doherty, Sean Michael.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Relevância na Pesquisa
66.71%
Cross body thrusters permit a body of revolution Autonomous Underwater Vehicle to retain the energy efficiency of forward travel while increasing the ability to maneuver in confined areas such as harbors and piers. This maneuverability also permits more deliberate underwater surveys using a fixed, mounted forward and downward looking sonar. This work develops the necessary hydrodynamic coefficients, using methods applied to earlier vehicles, to develop a valid computer simulation model. Additionally, this work develops a polynomial regression translating thruster input in RPM to an applied force output, which is incorporated into the vehicle model. This model is then employed to examine the response and control, specifically at low speed, of a body-of-revolution Autonomous Underwater Vehicle equipped with off-axis cross-body thrusters. These results are then utilized to develop a series of PID controllers for use onboard the REMUS Autonomous Underwater Vehicle.

Naval Postgraduate School Center for Autonomous Underwater Vehicle Research / 2003 Annual Report

Kragelund, Sean
Fonte: Monterey, California : Naval Postgraduate School Publicador: Monterey, California : Naval Postgraduate School
Tipo: Relatório
EN_US
Relevância na Pesquisa
96.54%
This report presents a summary of the work completed in 2003 at the NPS Center for Autonomous Underwater Vehicle (AUV) Research and provides a preview of future work planned for 2004.

A computer simulation study of rule-based control of an autonomous underwater vehicle

MacPherson, David L.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
86.56%
Approved for public release; distribution is unlimited; Man has an ever-increasing desire for machines to do his work for him. Unmanned vehicles that perform routine or hazardous tasks are receJ.vJ.ng a great deal of attention. Vehicles for unmanned submersible applications are becoming more feasible as strides are made in very large scale integration of computer hardware. This work focuses on development of algorithms and ideas for the computer control of military Autonomous Underwater Vehicles (AUVs). Both a Lisp machine and a graphics workstation, communicating via an Ethernet network, were used in this thesis to develop AUV simulator software. The emphasis has been placed on developing a computer graphic simulation of the control panel of an AUV and on a family of programs that define AUV missions. An AUV mission is a complete. software plan designed to control an AUV as it executes the steps to achieve '" some goal or objective. AUV missions are executed by this simulator in a fully autonomous mode once certain mission parameters are supplied by a human user.; http://archive.org/details/computersimulati00macp; This thesis is prepared in conjunction with research funded by the Naval Postgraduate School under the cognizance of the Naval Surface Weapons Center...

A Mission Planning Expert System with Three-Dimensional Path Optimization for the NPS Model 2 Autonomous Underwater Vehicle

Ong, Seow Meng
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
86.68%
Approved for public release; distribution is unlimited; Unmanned vehicle technology has matured significantly over the last two decades. This is evidenced by its widespread use in industrial and military applications ranging from deep-ocean exploration to anti-submarine warefare. Indeed, the feasiblity of short-range, special-purpose vehicles (whether aunonomous or remotely operated) is no longer in question. The research efforts have now begun to shift their focus on development of reliable, longer-range, high-endurance and fully autonomous systems. One of the major underlying technologies required to realize this goal is Artificial Intelligence (AI). The latter offers great potential to endow vehicles with the intelligence needed for full autonomy and extended range capability; this involves the increased application of AI technologies to support mission planning and execution, navigation and contingency planning. This thesis addresses two issues associated with the above goal for Autonomous Underwater Vehicles (AUV's). Firstly, a new approach is proposed for path planning in underwater environments that is capable of dealing with uncharted obstacles and which requires significantly less planning time and computer memory. Secondly...

A software architecture for a small autonomous underwater vehicle navigation system

Stevens, Clark D.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 145 p.
EN_US
Relevância na Pesquisa
96.54%
Approved for public release; distribution is unlimited.; This thesis documents the development of an interim Small Autonomous Underwater Vehicle (AUV) Navigation System (SANS), a self-contained, externally mountable navigation package. The purpose of SANS is to determine the position of a submerged object of interest located by an AUV. The volume of SANS must not exceed 120 cubic inches and total system accuracy of 10.0 meters rms or better is required. An Inertial Navigation System (INS) is implemented to compute the ascent path during transit from an object of interest to the surface. INS hardware components include miniature spin gyroscopes, a compass and a depth transducer interfaced through an analog to digital converter. Global Positioning System (GPS) is used to determine the AUV's location after reaching the surface. The reciprocal of the ascent vector is applied to the AUV's GPS position to accurately determine the location of the target of interest. A primarily object- oriented software architecture is implemented here with extensive software testing to verify the proper operation of key modules. The objective of this thesis is to quantify the adequacy of the selected components in meeting these requirements and to develop a breadboard design demonstrating the basic functions of the interim SANS. This research concludes that the components selected for the interim SANS meet the accuracy requirements provided the AUV maintains a climb angle which is equal to or steeper than 12 degrees from a typical mission depth of 20 meters.; Lieutenant Commander...

Horizontal steering control in docking the ARIES AUV; Horizontal steering control in docking the ARIES autonomous underwater vehicle

Tan, Wee Kiat
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xiv, 85 p. : ill.
Relevância na Pesquisa
76.52%
Approved for public release, distribution is unlimited; To keep the operational cost down and increase the mission time with minimum human intervention, autonomous recovery or docking operation of an Autonomous Underwater Vehicle (AUV) is required. Central to the successful autonomous docking process of the AUV is the capability of the AUV being able to track and steer itself accurately towards the dock which is constantly perturbed by wave motion effects. In addition, for accurate acoustic homing during the final stages of the docking, the AUV requires acoustic systems with high update rates. Equipped with acoustic modem, ARIES had experimentally been tested to have an update rate of only about 0.3 Hz. These delayed data can potentially cause a false commanded reference input to the tracking system in between the updates and cause ARIES to miss the moving cage's entrance. This thesis attempts to investigate the effectiveness on the use of cross track error and line of sight error sliding mode controller coupled with dynamic waypoints allocation in horizontal steering of ARIES in docking operations. In the absence of cage heading updates, a predictive method based on angular rate and direction of motion was used to estimate the dynamics of the moving cage. Further analysis was performed in order to understand the limitations of such an implementation.; Civilian...

A computer simulation study of mission planning and control for the NPS autonomous underwater vehicle

Nordman, Douglas B.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
96.69%
Approved for public release; distribution is unlimited.; Autonomous vehicles will operate where humans cannot or do not want to go. The last·decade's advances in computer· processor capability and speed, component miniaturization, signal processing, and high-energy-density power supplies have made remotely-operated vehicles (ROVs) a reality. These reliable, long-range, highendurance vehicles now perform a number of tasks in research, industrial, and military applications, but they are still incapable of truly autonomous behavior. The U.S. Navy has identified a number of autonomous vehicle missions, and the Naval Postgraduate School is extending ROV technology to build an autonomous underwater vehicle (AUV). The mission controller for the NPS AUV is a knowledge-based artificial intelligence (AI) system requiring thorough analysis and testing before the AUV is operational. Rapid prototyping of this software has been demonstrated by developing controller code on a LISP machine and using an Ethernet link with a graphics workstation to simulate the controller's environment. This thesis updates and improves the earlier simulator and its hardware, and describes the development of a new testing simulator designed to examine AUV controller subsystems and vehicle models before integrating them with the full AUV for its test environment missions. This AUV simulator is fully autonomous once initial mission parameters are selected.; http://archive.org/details/computersimulati00nord; This thesis is prepared in conjunction with research funded by the Naval Postgraduate School under the cognizance of the Naval Surface Warfare Center...

Design of a video recording and tracking system for the NPS Autonomous Underwater Vehicle (AUV)

Dussourd, Xavier
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Relatório
Relevância na Pesquisa
96.73%
The Naval Postgraduate School (NPS) is on the leading edge of Autonomous Underwater Vehicle (AUV) research and is currently developing a new AUV named ARIES. AUVs are principally designed to realize reconnaissance missions. To achieve such tasks, they usually utilize precise range-based sonars. Unfortunately, sonars are often unable to provide a good and efficient description of their environment due to the unclear aspect of many sonar images. To overcome such problems, the ARIES vehicle has a video camera to obtain understandable, classifiable images. This project explains the design of the video system installed on the ARIES AUV. The video system allows the AUV to automatically record and to easily understand the images provide by the AUV's camera. In this way, the AUV is now an efficient "witness" of its surroundings. This project then describes how to utilize the video for vehicle navigation. Such a capability is demonstrated by the simulation of the recovery between an AUV and a host submarine, using an underwater beacon and a light-tracking system. These results show that the use of in-water video for contact recording and navigational tracking can be practical and effective.; Prepared for: Center for Autonomous Underwater Vehicle (CAUVR) funded by the Office Naval Research (ONR) (Dr. Tom Curtain)

Design of a Power Bus for a New Autonomous Underwater Vehicle (AUV)

Lalaque, Samuel
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Relatório
Relevância na Pesquisa
86.48%
The views expressed in this thesis are those of the author and do not reflect the offical policy or position of the Deparment of Defense or the U.S. Government.; The Naval Postgraduate School had developed its own AUV called the Phoenix. A successor of the Phoenix is under construction. This new boat, larger, need to have more power than its predecessor to fight the wave current and to have the ability of station keeping in a dynamic environment. In that way, the power capacity will be increased to match and even overtake the range of the first NPS AUV. The Phoenix currently uses a 24 volts batteries pack. The new boat will use a 48 volts batteries pack. Moreover, some components will be replaced or removed for the new configuration (camera, acoustic modem, etc...). All this change requires designing a new power bus to give electric power in all the boat. Described in this project is the adaptation of all the Phoenix's components to this new power bus. This adaptation included the choice of new components and the design of the new power bus that will provide energy in the new boat. This project also provides a simulation of the screw motors on Simulink. This simulation, as the beginning of the electric modelization of the boat, provides a complex model of the screw motors. It is simplified at the end to obtain a faster but sufficiently accurate simulation.; Prepared for: Center for Autonomous Underwater Vehicle Research (CAUVR) funded by the Office of Naval Research.; 0001498WR30175

A mine search algorithm for the Naval Postgraduate School Autonomous Underwater Vehicle

Rodrigues Neto, Jose Augusto
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 88 p.;28 cm.
EN_US
Relevância na Pesquisa
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Approved for public release; distribution unlimited.; This thesis develops, implements and tests a mine search algorithm for the Naval Postgraduate School Autonomous Underwater Vehicle (Phoenix). The vehicle is 72 inches long and displaces 400 pounds. Its maneuvers are performed using two propellers and four thrustem. It contains two embedded computer systems. The algorithm directs the autonomous search of a specified area mapping all obstacles and computing an estimate of the cumulative probability of detection. The algorithm uses no prior knowledge of the terrain or the location of mines. The algorithm, which is written in Lisp, can execute on the vehicle's computer systems. Along with the search and mapping capabilities, the algorithm executes obstacle avoidance. The algorithm is tested in several simulated scenarios with different placement of mines and obstacles; the amount of resources used and the fraction of the area searched is computed. A similar algorithm that uses hill-climbing search is implemented for comparison. In all cases, the newly developed algorithm performed equal or better than the one that uses hill-climbing.; Brazilian Navy author.

Ada implementation of concurrent execution of multiple tasks in the strategic and tactical levels of the rational behavior model for the NPS Phoenix Autonomous Underwater Vehicle (AUV)

Holden, Michael John
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 150 p. ;|c28 cm.
Relevância na Pesquisa
76.53%
Approved for public release; distribution is unlimited; Current autonomous vehicle control systems are limited to inefficient sequential operation because of a lack of concurrency in program execution. When one segment of a sequential control system is delayed or fails, the remaining segments cannot be executed unless extensive error-handling routines are invoked. Undersea robotic vehicles in particular are subject to potential catastrophic loss in the event of minor program faults. The problem addressed by this thesis is to provide concurrent execution and higher level abstraction in reliable and maintainable control software, specifically for the Naval Postgraduate School's Phoenix Autonomous Underwater Vehicle (AUV) and within the framework of the Rational Behavior Model (RBM) Strategic and Tactical Levels. The approach taken for this work was to design and implement the RBM Strategic and Tactical level control software using Ada. The program design adds concurrency using the Ada task construct to create objects that perform separate operations simultaneously. For comparison purposes, the same functionality in a non-concurrent program was also implemented in the LISP programming language. The result was a concurrent REM control software system in Ada...

Virtual Long Baseline (VLBL) autonomous underwater vehicle navigation using a single transponder

LaPointe, Cara E. G.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Tese de Doutorado Formato: 94 p. : ill. (some col.) ;
Relevância na Pesquisa
76.69%
CIVINS; This thesis presents a simulation of autonomous underwater vehicle navigation using a single transponder to create a virtual long baseline (VLBL). Similarly to LBL systems, ranges in a VLBL are calculated between the vehicle and the transponder, but the vehicle position is determined by advancing multiple ranges from a single transponder along the vehicles dead reckoning track. Vehicle position is then triangulated using these successive ranges in a manner analogous to a 'running fix' in surface ship navigation. Navigation data from bottom survey operations of an underwater vehicle called the Autonomous Benthic Explorer (ABE) were used in the simulation. The results of this simulation are presented along with a discussion of the benefits, limitations, and implications of its extension to real-time operations. A cost savings analysis was also conducted based both on the idea that a single surveyed beacon could be deployed for underwater navigation and on the further extension of this problem that the 'single beacon' used for navigation could be located on the ship itself.; Contract number: N62271-97-G-0026.; CIVINS; US Navy (USN) author.

Incorporation of global positioning system into autonomous underwater vehicle navigation

Kwak, S.H.; McKeon, J. B.; Clynch, J. R.; Mcghee, R.B.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Relevância na Pesquisa
76.53%
The article of record may be found at http://dx.doi.org/10.1109/AUV.1992.225224; Autonomous Underwater Vehicle Technology, 1992. AUV '92., Proceedings of the 1992 Symposium on; The authors provide a brief introduction to the global positioning system (GPS). In addition, the issues of incorporating GPS into autonomous underwater vehicles (AUVs) navigation are explored. Test results conducted on a stationary GPS receiver are analyzed for suitability in AUV navigation. These results meet the minimum criteria of AUV employment as established. It was demonstrated that small, low-cost, low-power GPS receivers, in general, are suitable for AUV applications. In addition, a system design that the Naval Postgraduate School is now pursuing to incorporate GPS into AUV navigation is presented

Three-dimensional visualization of mission planning and control for the NPS autonomous underwater vehicle

Zyda, Michael J.; Mcghee, Robert B.; Kwak, Sehung; Nordman, Douglas B.; Rogers, Ray C.; Marco, David
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Relevância na Pesquisa
76.57%
The article of record may be found at http://dx.doi.org/10.1109/48.107150; Oceanic Engineering, IEEE Journal of; The Naval Postgraduate School (NPS) is constructing a small autonomous underwater vehicle (AUV) with an onboard mission control computer. The mission controller software for this vehicle is a knowledge-based artificial intelligence (AI) system requiring thorough analysis and testing before the AUV is operational. The manner in which rapid prototyping of this software has been demonstrated by developing a controller code on a LISP machine and using an Ethernet link with a graphics workstation to simulate the controller's environment is discussed. The development of a testing simulator using a knowledge engineering environment (KEE) expert system shell that examines AUV controller subsystems and vehicle models before integrating them with the full AUV for its test environment missions is discussed. This AUV simulator utilizes an interactive mission planning control console and is fully autonomous once initial parameters are selected

Geostatistical Prediction of Ocean Outfall Plume Characteristics Based on an Autonomous Underwater Vehicle

Ramos, Patrícia
Fonte: InTech Publicador: InTech
Tipo: Artigo de Revista Científica
Publicado em 11/07/2013 ENG
Relevância na Pesquisa
86.56%
Geostatistics has been successfully used to analyze and characterize the spatial variability of environmental properties. Besides giving estimated values at unsampled locations, it provides a measure of the accuracy of the estimate, which is a significant advantage over traditional methods used to assess pollution. In this work universal block kriging is novelty used to model and map the spatial distribution of salinity measurements gathered by an Autonomous Underwater Vehicle in a sea outfall monitoring campaign, with the aim of distinguishing the effluent plume from the receiving waters, characterizing its spatial variability in the vicinity of the discharge and estimating dilution. The results demonstrate that geostatistical methodology can provide good estimates of the dispersion of effluents that are very valuable in assessing the environmental impact and managing sea outfalls. Moreover, since accurate measurements of the plume’s dilution are rare, these studies might be very helpful in the future to validate dispersion models.; This work was supported by project WWECO- Environmental Assessment and Modeling of Wastewater Discharges using Autonomous Underwater Vehicles Bio-optical Observations-funded by the Foundation for Science and Technology (FCT) under the Program for Research Projects in all scientific areas (Programa de Projectos de Investigação em todos os domínos científicos) (ref. PTDC/MAR/74059/2006).

Virtual long baseline (VLBL) autonomous underwater vehicle navigation using a single transponder; VLBL autonomous underwater vehicle navigation using a single transponder

LaPointe, Cara Elizabeth Grupe
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 1822950 bytes; 94 leaves; 1822613 bytes; application/pdf; application/pdf
ENG
Relevância na Pesquisa
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(cont.) Therefore, accurate underwater navigation using a single location transponder would provide dramatic time and cost savings for underwater vehicle operations. This thesis presents a simulation of autonomous underwater vehicle navigation using a single transponder to create a virtual long baseline (VLBL). Similarly to LBL systems, ranges in a VLBL are calculated between the vehicle and the transponder, but the vehicle position is determined by advancing multiple ranges from a single transponder along the vehicles dead reckoning track. Vehicle position is then triangulated using these successive ranges in a manner analogous to a 'running fix' in surface ship navigation. Navigation data from bottom survey operations of an underwater vehicle called the Autonomous Benthic Explorer (ABE) were used in the simulation. The results of this simulation are presented along with a discussion of the benefits, limitations, and implications of its extension to real-time operations. A cost savings analysis was also conducted based both on the idea that a single surveyed beacon could be deployed for underwater navigation and on the further extension of this problem that the 'single beacon' used for navigation could be located on the ship itself.; Acoustic long baseline (LBL) navigation systems are often used for precision underwater vehicle navigation. LBL systems triangulate the position of the vehicle by calculating the range between the vehicle and multiple transponders with known locations. A typical LBL system incorporates between two and twelve acoustic transponders. The vehicle interrogates the beacons acoustically...