When evaluating the benefits of the artificial reefs, the generally is performed by sending divers or using Remotely Operated Vehicles (ROV). But to do the observation work, the deep sea is too dangerous for human being to work longer time, and ROV has no capable navigation system. So underwater survey became difficulty. The thesis integrates LXT Tracking System, Global Positioning System, Motion Sensor, Gyro Compass and the ROV original sensors such as : pressure sensor and magnetic compass to resolve the navigation problem of ROV, together with the high-density data of Multibeam echo sounder to rebuild the status of the seabed and artificial reefs. The thesis tries to apply the technology of Virtual Reality (VR) in ROV to being the interface. The results demonstrate the VR interface can display the position of ROV in three-dimensional space actually. And it can show the position of ROV navigation and warning message in real time when sailing. So the VR Navigation System will improve the ability of operating ROV greatly.

The main focus of about this thesis is to design an anti-interference depth controller for underwater remotely operated vehicles(ROV). Since the underwater remotely operated vehicle experiences combination effects of nonlinearities, uncertain and time-varying parameters, and unknown disturbances, demand of robustness for the controller needs to be extremely strict. Therefore, an anti-interference depth controller using PID control and Sliding-mode control is developed. The Matlab simulation tool is employed to simulate the depth control performance of the behavior of the ROV. The simulation is also considered about the model uncertainty of ROV.

The use of Remotely Operated Vehicles (ROVs) in exploring and building infrastructure in the ocean is expanding. ROVs are performing tasks underwater that would be difficult or impossible to do with human divers. These vehicles are being used in increasingly complicated and demanding environments that require improvements in the methods for controlling these vehicles. Currently, research into semi-autonomous control is being conducted to aide ROV pilots in compensating for environmental disturbances and unknown dynamics. To effectively implement semi-autonomous control, precise thrust forces must be elicited from the thrusters. This work discusses a low-level thruster controller that can be used as part of a semi- autonomous guidance, navigation and control system for a ROV. A thruster dynamics model describing the thrust force of a propeller-type underwater thruster was derived and implemented for the thruster on the Saab Seaeye Falcon ROV. The thruster dynamics model described is a quadratic equation that uses the propeller velocity to determine thrust force. This model includes a mechanism for compensation against the external motion of the thruster, such as occurs when the ROV moves through the water. Several experiments were performed to fully characterize the quadratic thruster dynamics model and test its ability to accurately predict thrust force based on a known ambient water velocity and propeller angular velocity. The drag force was calculated and removed from the force measurements to get the thrust force used in the model. The model coefficients were determined and then the resulting model was tested against experimental data to determine the efficacy of the model in the lab environment and compare it to a widely used linear thruster dynamics model. The results showed the quadratic model improved upon the linear model, and the quadratic model was valid over a larger range of ambient water velocities. The quadratic model was then inverted to provide a thruster control algorithm that determines the propeller angular velocity necessary to produce a desired thrust force. This algorithm was used to design a low-level thruster controller. This controller was designed to be used on an existing vehicle where thrust force feedback is not available and difficult or expensive to add. This allows it to be used in a wider range of applications than controllers that rely on such feedback to operate. The controller was implemented using a PID control loop to drive the angular velocity of the propeller to the desired rate. An iso-parametric mapping, which transforms the linear PID output to the non-linear thruster input, was added to provide a faster response time for the controller over the entire range of the propeller velocity. The performance of this low-level thruster controller was demonstrated in the test environment. The low-level thruster controller followed a desired thrust force under a range of ambient water velocities. The thruster characterization and low-level thruster controller was designed to be used on an existing ROV. The motivation behind this work is to build a controller that may be implemented for use by a high-level vehicle controller. The low-level thruster controller presented here does not depend on sensors or equipment that is largely unavailable on vehicles without costly retrofits, and the experimental characterization does not require intimate knowledge of the inner workings of the thruster. This makes it easy to implement and generalize to a variety of thrusters. The results of this work show a low-level thruster controller than can be used in a control schema for existing ROVs. / Graduate / 0547 / matt@amosbuchanan.net

For decades, Remotely Operated underwater Vehicles (ROVs) have been helping mankind explore the depths of the ocean, and build and maintain infrastructure on the seafloor. Since the first ROV was developed in 1953, the number of uses for these vehicles has exploded. They are now an essential part of maintaining the world's energy resources, collecting scientific data about our oceans, and performing underwater search and recovery. This research will discuss guidance, navigation, and control algorithms for use as a low-level position controller for ROVs, which will enable semi-autonomous behaviour for the vehicle. Semi-autonomous behaviour is when the pilot issues high-level position commands and the low-level controller handles station keeping and maneuvering between the commanded positions. In this configuration, the low level controller compensates for the environmental disturbances and unknown dynamics (such as current and tether dynamics), allowing the pilot to focus on other aspects of the task (such as manipulator control). In this work, the design,implementation,and testing of a complete guidance, navigation, and control system is presented. A Saab Sea-Eye Falcon ROV is augmented with a suite of navigation instruments. The augmented vehicle is characterized and a dynamic model is developed. This model is used in an extended Kalman filter, which will be shown to produce a position estimate for the vehicle with an error of less than ±6 cm. The navigation system is combined with a guidance system and adaptive controller to enable semi-autonomous behaviour. With this suite of software, the ROV can operate semi-autonomously. The resulting ROV system is a research platform, from which the underwater community can continue research into algorithms for optimal control, remote operations, and other performance enhancing technologies. / Graduate / 0771 / 0547 / allycin2@gmail.com

As global change alters the chemical and physical dynamics of the ocean, it is increasingly necessary to determine ecological responses across environmental gradients. The benthic ecosystems of fjords often contain a multitude of environmental gradients conducive to multivariate field studies. In this thesis, I describe the benthic community structure of two British Columbian fjords in relation to markedly different environmental variables. In Chapter 2, I show a strong correlation between suspension-feeder abundance and flow structure on the steep fjord walls of Douglas Channel, BC. I also describe distinct assemblages with depth and with location along the fjord head-mouth axis. Using a suite of biological traits, I show that the deep portion (> 400 m depth) of the most seaward site is the most taxonomically and functionally diverse in the fjord. My results suggest fjord walls form an expansive ecosystem containing diverse and dense assemblages of suspension feeders relevant to the flow of energy through fjord basins and as biodiversity reservoirs. In Chapter 3, I extend a long-term hypoxia time-series (2006 -2016) to document the response of soft-bottom epibenthic megafauna of Saanich Inlet, BC to a prolonged hypoxic event in 2016 that caused abundance declines, community aggregation and shifts in species composition more extreme than those seen in the 2013 hypoxia cycle. I also assess community threshold responses along the oxygen gradient; I found community transitions consistent across years and with Northeast Pacific oxygen thresholds based in ecophysiological studies. Taken together, these studies show a strong coupling between oceanographic conditions and the community structure of fjord benthos. I suggest that climate-driven alterations in North Pacific oceanographic regimes may portend major changes in fjord ecosystems. / Graduate

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.

Sistemas de controle distribuídos cujas malhas são fechadas através de uma rede de comunicação são chamados de sistemas de controle distribuídos em redes de comunicação (NCS - Networked Control System). Este tipo de arquitetura permite a divisão do sistema de controle em módulos interconectados através da rede de comunicação, proporcionando a divisão do processamento, a redução de custo e de peso, além de facilitar o diagnóstico e manutenção do sistema e de aumentar a sua exibilidade e agilidade; e por isso seu emprego na indústria está se tornando comum (e.g., y-by-wire e drive-by-wire). Porém, a distribuição do processamento e a inserção de uma rede de comunicação aumenta a complexidade da análise e do projeto deste tipo de sistema. Um dos fatores que contribui para esse aumento da complexidade é a presença de atrasos aleatórios nos sinais de controle, causados pela dinâmica do sistema computacional (conjunto de hardware e software) que serve como plataforma para implementação do sistema de controle digital. Este trabalho faz um estudo sobre este tipo de sistema sob a perspectiva destes sinais com atrasos. Para isso, faz-se uso dos toolboxes para MATLAB: TrueTime e Jitterbug. Através destas ferramentas, mostra-se a existência de uma relação de compromisso entre o desempenho do controle e o desempenho do sistema computacional. Através deste estudo, é proposto uma solução de um sistema de controle do tipo NCS para um ROV (do inglês Remotely Operated Vehicle), modelado através de 6 equações diferenciais desacopladas não-lineares. Este tipo de veículo tem uma relevância econômica significativa para o Brasil, visto que é utilizado em operações de manutenção e instalação de plataformas de extração do petróleo que está depositado em profundidades que variam de mil a 2 mil metros. Para este NCS proposto, são utilizados controladores do tipo PI com estrutura feedback-feedfoward cujos parâmetros de projeto são obtidos em função dos atrasos inseridos pelo sistema computacional. / Distributed control systems wherein the control loops are closed through a communication network are called Networked Control Systems (NCSs). This type of architecture allows the control systems division into modules interconnected through the communication network, providing the processing division, reduction of cost and weight, and facilitates the systems diagnosis and maintenance, and increases their exibility and agility. Therefore its use in industry is becoming common (eg, y-by-wire and drive-by-wire). However, the processing distribution and the communication network insertion increase the system analysis and design complexity. One of the factors that contributes to this increased complexity is the presence of random time delays, caused by the dynamics of the computer system (set of hardware and software) used as a platform for digital control system implementation. This work deals with the networked control systems under these random time delays view. For this, it is used two MATLAB toolboxes: Jitterbug and TrueTime. With these tools, it is shown the existence of a relationship between the performance of control and performance of computer system. With this study, it proposed a solution of a NCS for a ROV (Vehicle Operated Remotely), modeled by 6 differential nonlinear decoupled equations. This type of vehicle has a significant economic relevance for Brazil, as it is used in maintenance and installation of platforms for oil extraction deposited at depths ranging from thousand to 2 thousand meters. For this proposed NCS are adopted PI controllers with feedfoward-feedback structure whose parameters design are given in terms of delay inserted by the computer system.

Sistemas de controle distribuídos cujas malhas são fechadas através de uma rede de comunicação são chamados de sistemas de controle distribuídos em redes de comunicação (NCS - Networked Control System). Este tipo de arquitetura permite a divisão do sistema de controle em módulos interconectados através da rede de comunicação, proporcionando a divisão do processamento, a redução de custo e de peso, além de facilitar o diagnóstico e manutenção do sistema e de aumentar a sua exibilidade e agilidade; e por isso seu emprego na indústria está se tornando comum (e.g., y-by-wire e drive-by-wire). Porém, a distribuição do processamento e a inserção de uma rede de comunicação aumenta a complexidade da análise e do projeto deste tipo de sistema. Um dos fatores que contribui para esse aumento da complexidade é a presença de atrasos aleatórios nos sinais de controle, causados pela dinâmica do sistema computacional (conjunto de hardware e software) que serve como plataforma para implementação do sistema de controle digital. Este trabalho faz um estudo sobre este tipo de sistema sob a perspectiva destes sinais com atrasos. Para isso, faz-se uso dos toolboxes para MATLAB: TrueTime e Jitterbug. Através destas ferramentas, mostra-se a existência de uma relação de compromisso entre o desempenho do controle e o desempenho do sistema computacional. Através deste estudo, é proposto uma solução de um sistema de controle do tipo NCS para um ROV (do inglês Remotely Operated Vehicle), modelado através de 6 equações diferenciais desacopladas não-lineares. Este tipo de veículo tem uma relevância econômica significativa para o Brasil, visto que é utilizado em operações de manutenção e instalação de plataformas de extração do petróleo que está depositado em profundidades que variam de mil a 2 mil metros. Para este NCS proposto, são utilizados controladores do tipo PI com estrutura feedback-feedfoward cujos parâmetros de projeto são obtidos em função dos atrasos inseridos pelo sistema computacional. / Distributed control systems wherein the control loops are closed through a communication network are called Networked Control Systems (NCSs). This type of architecture allows the control systems division into modules interconnected through the communication network, providing the processing division, reduction of cost and weight, and facilitates the systems diagnosis and maintenance, and increases their exibility and agility. Therefore its use in industry is becoming common (eg, y-by-wire and drive-by-wire). However, the processing distribution and the communication network insertion increase the system analysis and design complexity. One of the factors that contributes to this increased complexity is the presence of random time delays, caused by the dynamics of the computer system (set of hardware and software) used as a platform for digital control system implementation. This work deals with the networked control systems under these random time delays view. For this, it is used two MATLAB toolboxes: Jitterbug and TrueTime. With these tools, it is shown the existence of a relationship between the performance of control and performance of computer system. With this study, it proposed a solution of a NCS for a ROV (Vehicle Operated Remotely), modeled by 6 differential nonlinear decoupled equations. This type of vehicle has a significant economic relevance for Brazil, as it is used in maintenance and installation of platforms for oil extraction deposited at depths ranging from thousand to 2 thousand meters. For this proposed NCS are adopted PI controllers with feedfoward-feedback structure whose parameters design are given in terms of delay inserted by the computer system.

When working under water at great depths, or in tough environments, remotely controlled underwater vehicles, so called ROV:s, are a good tool too use. With the help of these robots it is possible to work for longer periods of time and at larger depths then with ordinary divers. Ocean Robotics is a company from Linköping, Sweden, that has over 40 years of experience with ROV:s. They produce several different models for different kind of jobs. The purpose of this project was to develop a concept of a device that keeps the tension constant on the tether that connects the ROV with the operator. The tension needs to be constant when the tether is being rolled in on and out from the winch. The work was executed on behalf of Ocean Robotics and a prerequisite was that it should be possible to integrate the device with the winch system they have today. The work have followed Ulrich and Eppingers method for product development and together with requirements from the contractor several concepts was generated. The concepts were validated in a decision matrix and the concepts with the highest score was modeled in the CAD-program CREO Parametrics. The concepts got further developed and was compared against each other once again. Which generated the final concept. Furthermore a couple of friction tests were executed to find appropriate materials for the construction. The final concept will be mounted on the winch and connected to Ocean Robotics self reversing screw. To measure the tension on the tether a load cell is used and the tether is fed by a rubberized wheel that is driven by an electric motor. To adjust the force around the tether a trapezoidal thread is driven by another electric motor, which adjust the pinch wheels height. The tether goes as a tangent between the two wheels that has a profile that insures that the force goes around the tether.

Arbetet undersöker vilken militär nytta en obemannad autonom undervattensfarkost med syntetisk apertursonar tillför vid sökning efter sjöminor. Genom systemanalys jämförs obemannad autonom undervattensfarkost och syntetisk apertursonar mot ett referenssystem för minsökning som finns i försvarsmakten. Referenssystemet är en fjärrstyrd undervattensfarkost med minjaktsonar. Resultatet med arbetet redovisas som slutsatser och rekommendationer utifrån de grundläggande förmågorna; verkan, uthållighet, rörelse och skydd samt systemets effektivitet vid minsökning. / This thesis studies the military benefits of autonomous underwater vehicle equipped with synthetic aperture sonar conducting mine reconnaissance. The autonomous underwater vehicle and synthetic aperture sonar are compared through system analysis using a reference system within the Swedish Armed Forces. The reference system is a remote operated underwater vehicle with mine hunting sonar. The result is presented as conclusions and recommendations based on the basic capabilities; effect, mobility, endurance, protection as well as the theoretical effectiveness of the system conducting mine reconnaissance.