Design and Projected Performance of a Flapping Foil AUV

The design and construction of a biomimetic flapping foil autonomous underwater vehicle is detailed. The vehicle was designed as a proof of concept for the use of oscillating foils as the sole source of motive power for a cruising and hovering underwater vehicle. Primary vehicle design requirements included scalability and flexibility in terms of the number and placement of foils, so as to maximize experimental functionality. This goal was met by designing an independent self-contained module to house each foil, requiring only direct current power and a connection to the vehicle’s Ethernet local area network for operation. The results of tests on the foil modules in the Massachusetts Institute of Technology (MIT) Marine Hydrodynamics Water Tunnel and the MIT Ship Model Testing Tank are both used to demonstrate fundamental properties of flapping foils and to predict the performance of the specific vehicle design based on the limits of the actuators. The maximum speed of the vehicle is estimated based on the limitations of the specific actuator and is shown to be a strong function of the vehicle drag coefficient. When using four foils, the maximum speed increases from 1 m/s with a vehicle Cd of 1.4 to 2 m/s when Cd = 0.1, where Cd is based on vehicle frontal area. Finally, issues of vehicle control are considered, including the decoupling of speed and pitch control using pitch-biased maneuvering and the tradeoff between actuator bandwidth and authority during both the cruising and hovering operation

Advances in Intelligent Robotics and Collaborative Automation

This book provides an overview of a series of advanced research lines in robotics as well as of design and development methodologies for intelligent robots and their intelligent components. It represents a selection of extended versions of the best papers presented at the Seventh IEEE International Workshop on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications IDAACS 2013 that were related to these topics. Its contents integrate state of the art computational intelligence based techniques for automatic robot control to novel distributed sensing and data integration methodologies that can be applied to intelligent robotics and automation systems. The objective of the text was to provide an overview of some of the problems in the field of robotic systems and intelligent automation and the approaches and techniques that relevant research groups within this area are employing to try to solve them.The contributions of the different authors have been grouped into four main sections:• Robots• Control and Intelligence• Sensing• Collaborative automationThe chapters have been structured to provide an easy to follow introduction to the topics that are addressed, including the most relevant references, so that anyone interested in this field can get started in the area

Hydrodynamic Optimization of a torpedo-shaped hull

Nowadays, it is not fully clear how the Ocean seabed can contribute to Earth ecosystems. However, several steps are being taken to completely understand Ocean’s seabed. Lately, many methods are being developed to explore the Oceans, although there is one method which fulfill the desired trade-off (between low operational costs and high quality data collection). This efficient method developed to explore the Ocean’s depth is known as submarine vehicles, and the most efficient of them, to explore and mapping, is certainly the Autonomous Underwater Vehicle (AUV). The increasing use of AUV’s is leading to a point in which its design parameters are crucial. Characteristics as high endurance, long operation time, high maneuverability and range are demanded at an early design stage; thus, it is essential to find an optimum hull shape design to improve these characteristics. This thesis presents the effect of hydrodynamic forces of axisymmetric underwater vehicles through the variation of the shape of a torpedo-shaped hull body. Furthermore, this thesis is intended to analyze, experimentally, the length-to-Diameter (D) ratios of nose (N) and tail (T), as well as its shapes, in order to find the optimum ratios and shape combinations for the minimization of Drag. The experimental tests were conducted in the towing tank of the University of Beira Interior (UBI). However, due to the Towing Tank dimensions, the development of a scaled model had to be made. A similarity between the scaled model and the full-scale prototype must be done to assume similar flow conditions. Several torpedo-shaped combinations were tested experimentally and further validated the numerical simulations. Moreover, parameters such as the pitch angles (or Angle of Attack (AoA)) [0 - 20°] and velocities [0.50 – 1 m/s] were investigated to understand their influence on the hydrodynamic Drag. The experimental setup is hereby fully described, showing the various procedures adopted until the data collection phase. A strain gauge system (load cell) was used to measure the Drag induced by the hull body. Experimental results demonstrate an optimum configuration for N/D = 0.8 (Elliptical shape) and T/D = 1.6 (Conical shape). From the experimental and numerical data, it could be seen that the Drag increases with the increase of velocity. Same occurrence happens for AoA, where Drag increases with higher AoA’s. Therefore, it can be concluded that the influence of AoA on Drag is higher for greater velocities. The experimental measurements have been used to validate results obtained from a Computational Fluid Dynamics (CFD) software that uses Reynolds Average Navier-Stokes (RANS) equations (ANSYSTM FLUENT). A mesh-independency study was made to investigate two turbulence models: Standard ?-e and ?-? SST models. Standard ?-e showed to be the most appropriate model to this study with a lower computational cost. Results between Experimental and Numerical methods showed a good agreement, considering the conditions mentioned.Hoje em dia, não é ainda completamente claro de que maneira o fundo dos oceanos podem contribuir para os Ecossistemas da Terra. Contudo, vários esforços estão a ser feito para compreender em profundidade os fundos marinhos dos Oceanos. Atualmente, o método mais eficiente, já desenvolvido, para explorar a profundeza dos oceanos é conhecido como veículos submarinos, e especificamente, o mais eficiente para pesquisa e exploração destes é conhecido como Veículo Autónomo Subaquático (AUV). O aumento do uso de AUV’s tem levado a um ponto em que os parâmetros de projeto são cruciais. Características como a resistência ao avanço, o alto tempo de operação, a grande manobrabilidade e o grande alcance são exigidos numa fase primária de projeto; desta forma, é fundamental encontrar uma forma ótima do corpo hidrodinâmico, ainda durante a fase de projeto, ambicionando melhorar as suas características. Esta dissertação apresenta o efeito das forças hidrodinâmicas de veículos subaquáticos axi- simétricos através da variação da forma de um corpo em forma de torpedo. Além disso, nesta dissertação pretende-se ainda analisar, experimentalmente, os rácios comprimento/diâmetro do nariz e da cauda do corpo, assim como as suas formas, para que seja possível os rácios e combinação ótimos do ponto de vista da minimização da resistência ao avanço. Os testes experimentais foram feitos num tanque de água da Universidade da Beira Interior (UBI). No entanto, devido às dimensões do tanque de água, o desenvolvimento de um modelo à escala foi a opção mais viável. Uma similaridade entre o modelo à escala e o protótipo foi feita para garantir as mesmas condições de escoamento entre ambos. Várias combinações foram testadas experimentalmente e seguidamente validadas por simulações numéricas. Adicionalmente, parâmetros como o ângulo de ataque (de 0 - 20°) e a velocidade (entre 0.50 – 1 m/s) foram alterados para perceber a sua influência na resistência hidrodinâmica. A preparação experimental é totalmente descrita, mostrando vários procedimentos adotados até à fase de recolha de dados. Um sistema de tensão/compressão (célula de carga) foi utilizado para medir a resistência induzido pelo corpo. Os resultados experimentais demonstraram uma configuração ótima que se situa nas proximidades de N/D = 0.8 (Forma Elítica) e T/D = 1.6 (Forma Cónica). Pode ser visto que a resistência aumenta com o aumento da velocidade. Da mesma forma para os ângulos de ataque, a resistência aumenta para ângulos de ataque maiores. Os dados experimentais foram usados para validar os resultados obtidos de um software CFD que usa as equações RANS. Um estudo de independência da malha foi feito para investigar dois modelos turbulentos: Modelos Standard ?-e e ?-? SST. O modelo turbulento Standard ?-e mostrou ser o mais apropriado para este estudo com um menor custo computacional. Os resultados entre os métodos experimentais e numéricos mostraram uma boa concordância, considerando as condições mencionadas

Advances in Intelligent Robotics and Collaborative Automation

This book provides an overview of a series of advanced research lines in robotics as well as of design and development methodologies for intelligent robots and their intelligent components. It represents a selection of extended versions of the best papers presented at the Seventh IEEE International Workshop on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications IDAACS 2013 that were related to these topics. Its contents integrate state of the art computational intelligence based techniques for automatic robot control to novel distributed sensing and data integration methodologies that can be applied to intelligent robotics and automation systems. The objective of the text was to provide an overview of some of the problems in the field of robotic systems and intelligent automation and the approaches and techniques that relevant research groups within this area are employing to try to solve them.The contributions of the different authors have been grouped into four main sections:• Robots• Control and Intelligence• Sensing• Collaborative automationThe chapters have been structured to provide an easy to follow introduction to the topics that are addressed, including the most relevant references, so that anyone interested in this field can get started in the area

Development of an Energy Efficient Stern Flap for Improved EEDI of a Typical High speed Displacement Vessel

The surge in maritime trade is leading to large scale deployment of high-speed displacement ships by all nations. Cargo vessels are designed for a voyage in pre-determined routes at consistent speeds. On the other hand, high-speed displacement vessel engines designed with a capability to cater for top speeds are under-utilised during their normal course of operation. This sub-optimal utilisation impacts efficiency and increases emissions. In this study, a most favourable stern flap is designed for reducing the energy efficiency design index of a typical high-speed displacement vessel with a slender hull. CFD simulations and experimental model testing were conducted for 12 different stern flap configurations for determining most favourable flap design in the Froude no of 0.17-0.48. Performance of the most favourable stern flap was established by calculating, energy efficiency design index (EEDI) and fuel consumption based on typical operating profile. NOx, VOC and PM emissions were estimated in with and without flap condition. Studies demonstrated that the stern flap reduced effective power demand, average fuel consumption and emissions by about 8 per cent, which when considered for the ship’s operating life cycle, are significant. The most favourable stern flap reduced EEDI by 3.74 units and 1.98 units as compared to the bare hull condition and the required EEDI respectively, thereby demonstrating that EEDI could be used as an index to indicate stern flap efficiency

A new concept of highly modular ASV for extremely shallow water applications

This paper describe SWAMP, a prototype Autonomous Surface Vehicle (ASV) representing the base for the design and development of an innovative class of reliable modular reconfigurable lightweight ASVs for extremely shallow water applications. The design of SWAMP-class ASVs is based on a holistic approach involving different aspects of robotics such as the use of soft materials, the mechanical design of innovative propulsion system integrated with the vessel hull, the adoption of modular mechanical and computing architecture able to support multi-agent distributed GNC systems