A New Coastal Crawler Prototype to Expand the Ecological Monitoring Radius of OBSEA Cabled Observatory

The use of marine cabled video observatories with multiparametric environmental data collection capability is becoming relevant for ecological monitoring strategies. Their ecosystem surveying can be enforced in real time, remotely, and continuously, over consecutive days, seasons, and even years. Unfortunately, as most observatories perform such monitoring with fixed cameras, the ecological value of their data is limited to a narrow field of view, possibly not representative of the local habitat heterogeneity. Docked mobile robotic platforms could be used to extend data collection to larger, and hence more ecologically representative areas. Among the various state-of-the-art underwater robotic platforms available, benthic crawlers are excellent candidates to perform ecological monitoring tasks in combination with cabled observatories. Although they are normally used in the deep sea, their high positioning stability, low acoustic signature, and low energetic consumption, especially during stationary phases, make them suitable for coastal operations. In this paper, we present the integration of a benthic crawler into a coastal cabled observatory (OBSEA) to extend its monitoring radius and collect more ecologically representative data. The extension of the monitoring radius was obtained by remotely operating the crawler to enforce back-and-forth drives along specific transects while recording videos with the onboard cameras. The ecological relevance of the monitoring-radius extension was demonstrated by performing a visual census of the species observed with the crawler’s cameras in comparison to the observatory’s fixed cameras, revealing non-negligible differences. Additionally, the videos recorded from the crawler’s cameras during the transects were used to demonstrate an automated photo-mosaic of the seabed for the first time on this class of vehicles. In the present work, the crawler travelled in an area of 40 m away from the OBSEA, producing an extension of the monitoring field of view (FOV), and covering an area approximately 230 times larger than OBSEA’s camera. The analysis of the videos obtained from the crawler’s and the observatory’s cameras revealed differences in the species observed. Future implementation scenarios are also discussed in relation to mission autonomy to perform imaging across spatial heterogeneity gradients around the OBSEA

Design considerations for engineering autonomous underwater vehicles

Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2007Autonomous Underwater Vehicles (AUVs) have been established as a viable tool for Oceanographic Sciences. Being untethered and independent, AUVs fill the gap in Ocean Exploration left by the existing manned submersible and remotely operated vehicles (ROV) technology. AUVs are attractive as cheaper and efficient alternatives to the older technologies and are breaking new ground in many applications. Designing an autonomous vehicle to work in the harsh environment of the deep ocean comes with its set of challenges. This paper discusses how the current engineering technologies can be adapted to the design of AUVs. Recently, as the AUV technology has matured, we see AUVs being used in a variety of applications ranging from sub-surface sensing to sea-floor mapping. The design of the AUV, with its tight constraints, is very sensitive to the target application. Keeping this in mind, the goal of this thesis is to understand how some of the major issues affect the design of the AUV. This paper also addresses the mechanical and materials issues, power system design, computer architecture, navigation and communication systems, sensor considerations and long term docking aspects that affect AUV design. With time, as the engineering sciences progress, the AUV design will have to change in order to optimize its performance. Thus, the fundamental issues discussed in this paper can assist in meeting the challenge of maintaining AUV design on par with modern technology.This work was funded by the NSF Center for Subsurface Sensing and Imaging Systems (CenSSIS) Engineering Research Center (ENC) grant no. EEC-99868321

Desenvolvimento de um sistema de lançamento e recolha dos AUVs SEACon através dos submarinos da classe TRIDENTE

Os submarinos da classe TRIDENTE têm capacidade para que o planeamento, lançamento, operação e recolha dos Autonomous Underwater Vehicles (AUVs) sejam efetuados a partir do seu interior. Contudo ainda não foram desenvolvidos os sistemas de lançamento e recolha (L/R) que o permitam efetuar sem recurso a um elemento mergulhador no exterior do navio. A solução que se apresenta com esta dissertação consiste na utilização dos tubos de lançamento de torpedos para lançar e recolher os AUVs SEACon da Marinha Portuguesa. Deste modo, projetou-se, construiu-se e testou-se o funcionamento de um dispositivo, para assentar nos tubos de lançamento dos torpedos e ser amovível (ou seja, que não condiciona a operacionalidade dos submarinos no que toca ao seu armamento), a partir do qual os AUVs podem ser lançados para o exterior do navio em submersão. Os sistemas de recolha dos AUVs já utilizados noutras marinhas, requerem ainda muitas alterações à estrutura ou operação dos submarinos pelo que se estudou, avaliou e propõe uma hipótese que envolva o menor número de alterações possível aos sistemas dos submarinos da classe TRIDENTE e que seja passível de ser implementada a curto-prazo. O estudo efetuado tem em consideração os sistemas já conhecidos e implementados noutras marinhas. A abordagem ao projeto é feita com base na teoria Axiomática de Projeto (AP), em que são definidos os requisitos relativos a este sistema, avaliadas as várias propostas de solução dos respetivos problemas e desenvolvida a solução bem como o respetivo dimensionamento e análise com recurso a métodos computacionais e experimentais. Foram efetuadas atividades experimentais para comparar duas abordagens diferentes no que diz respeito ao funcionamento do sistema de L/R, tendo-se comprovado o funcionamento.Portuguese manned submarines of the TRIDENTE class, have the capability to launch, operate and recover Autonomous Underwater Vehicles (AUVs). This is currently done with the help of divers outside the submarine. The solution developed in this work makes use of the torpedoes tubes to do the launch and recover of the Portuguese AUVs SEACon. The aim of this work is to design, develop and test a piece that fits in the torpedoes tube and that is removable (to preserve all operation and weaponry capabilities of the submarine if AUVs are not needed). The launch and recovery systems used in some navies require several changes in what concerns to the structure and to the operation modes of the submarine. The goal of this thesis is to study, evaluate and propose a design that makes minimum changes to the submarine’s systems and it is possible to install in in short-term. The design process used is based on the axiomatic design (AD) theory considering the functional requirements to this system and comparing the existing launch and recovery systems from other navies in order to develop a suitable solution to the Portuguese Navy needs. Thus, solution is further dimensioned and tested with computational and experimental methods. Two experiments were carried out in order to compare two different approaches to the L/R system operation

Conceito de Operação dos Veículos Submarinos Autónomos SeaCon a partir dos Submarinos da Classe Tridente

Os veículos submarinos autónomos (AUV´s) surgiram no contexto militar (século XX) como um instrumento de progressão da força naval. Os AUV’s são pequenos submarinos não tripulados que executam missões pré-programadas sem intervenção de um operador, contribuindo assim para um acréscimo das capacidades inerentes às missões da Marinha, tanto em missões de caráter científico (e.g. recolha de dados oceanográficos) como operacional (e.g. guerra de minas). É objetivo deste trabalho a apresentação de uma solução para a operação de AUV’s da classe SeaCon a partir dos submarinos da classe Tridente. Os AUV´s SeaCon foram desenvolvidos pela Faculdade de Engenharia da Universidade do Porto em colaboração com a Marinha, no âmbito do projeto SeaCon financiado pelo Ministério da Defesa Nacional, mas encontram-se em fase de melhoramento (parceria de I&D SeaCon II). Esta solução permitirá dotar a Marinha de capacidades únicas a nível Europeu, sendo que tal só é possível em virtude da capacidade de desenvolvimento nacional nesta área. Estas capacidades complementam as capacidades únicas da nova arma submarina da Marinha e contribuirão para melhor as adaptar a novos ambientes de operação. A metodologia empregue neste trabalho inspira-se na metodologia proposta no Standard do IEEE (1220-2005) para o processo que Engenharia de Sistemas que estrutura todos os passos desde a análise e definição dos requisitos até à síntese de um sistema solução. O trabalho foi orientado para a apresentação de uma solução que privilegia a utilização de sistemas do submarino e do AUV, restringindo as modificações às necessárias à sua operação como sistema. O conceito de operação engloba o planeamento, lançamento, operação e recolha do AUV a partir do submarino (vertente mecânica, técnica e operacional). A solução proposta consiste no lançamento do AUV a partir do sistema de tubos lançadores de armas e a recolha pela eclusa, sendo objetivo do conceito de operação a flexibilidade de utilização dos dois sistemas.Autonomous Underwater Vehicles (AUV’s) first appeared within a military context (Twentieth Century) as a naval progression instrument. AUV’s are small unmanned submarines who execute pre-programmed missions, without the intervention of an operator, hence contributing for an increase in the Navy’s inherent capabilities, in scientific featured missions (e.g. oceanographic data collection) as well as operational missions (e.g. minesweeping operations). This work aims to present a solution regarding the operational use of SeaCon Class AUV’s in combination with Tridente Class Submarines. The SeaCon AUV’s have been developed by Oporto University’s Engineering College in collaboration with the Portuguese Navy, in light of the SeaCon project, which is funded by the portuguese’s Ministry of Defense, however, it is currently in an improvement phase (I&D SeaCon II partnership). This solution will allow the Navy to endow unique european level capabilities, given that such a possibility will only exist with a national level ability to develop the study area. These capabilities complement the unique features of the portuguese’s newest submarine weapon and will contribute to better adapt to new operational environments. This work’s methodology is inspired in the IEEE (1220-2005) standard methodology proposal for system engineering process, which structures all process steps from requisition’s analysis and definition to a system’s synthetized solution. The work was guided in order to present a solution which privileges the use of the AUV’s and submarine’s systems, restricting modifications to its operation needs as a system. The operation concept encompasses the AUV’s planning, launch, operation and recovery from the submarine (mechanical, technical and operational components). The proposed solution specifies the AUV’s launch from the submarine’s torpedo tube launchers and its recovery through the hatchway, being the operation concept’s main objective to achieve flexibility in the use of both systems