12,113 research outputs found
Multi-actuated AUV body for windfarm inspection : lessons from the bio-inspired RoboFish field trials
An innovative magnetic joint design has been developed as part of the construction of a bio-inspired Autonomous Underwater Vehicle (AUV) for wind farm inspection. This paper presents our design solutions for a jointed watertight AUV body made using current 3D printing techniques to achieves water tightness and resilient composite metal-polymer bonding.The design avoids dynamic interfaces and the need for rotary seals yet achieves robustness and strength. Test results prove a successful implementation of the magnetic connection between a freely rotating inner shaft and a driven outer shaft in a fish-like jointed AUV body
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
Development and testing of a dual accelerometer vector sensor for AUV acoustic surveys
This paper presents the design, manufacturing and testing of a Dual Accelerometer Vector Sensor (DAVS). The device was built within the activities of theWiMUST project, supported under the Horizon 2020 Framework Programme, which aims to improve the efficiency of the methodologies used to perform geophysical acoustic surveys at sea by the use of Autonomous Underwater Vehicles (AUVs). The DAVS has the potential to contribute to this aim in various ways, for example, owing to its spatial filtering capability, it may reduce the amount of post processing by discriminating the bottom from the surface reflections. Additionally, its compact size allows easier integration with AUVs and hence facilitates the vehicle manoeuvrability compared to the classical towed arrays. The present paper is focused on results related to acoustic wave azimuth estimation as an example of its spatial filtering capabilities. The DAVS device consists of two tri-axial accelerometers and one hydrophone moulded in one unit. Sensitivity and directionality of these three sensors were measured in a tank, whilst the direction estimation capabilities of the accelerometers paired with the hydrophone, forming a vector sensor, were evaluated on a Medusa Class AUV, which was sailing around a deployed sound source. Results of these measurements are presented in this paper.European Union [645141]info:eu-repo/semantics/publishedVersio
An Autonomous Surface Vehicle for Long Term Operations
Environmental monitoring of marine environments presents several challenges:
the harshness of the environment, the often remote location, and most
importantly, the vast area it covers. Manual operations are time consuming,
often dangerous, and labor intensive. Operations from oceanographic vessels are
costly and limited to open seas and generally deeper bodies of water. In
addition, with lake, river, and ocean shoreline being a finite resource,
waterfront property presents an ever increasing valued commodity, requiring
exploration and continued monitoring of remote waterways. In order to
efficiently explore and monitor currently known marine environments as well as
reach and explore remote areas of interest, we present a design of an
autonomous surface vehicle (ASV) with the power to cover large areas, the
payload capacity to carry sufficient power and sensor equipment, and enough
fuel to remain on task for extended periods. An analysis of the design and a
discussion on lessons learned during deployments is presented in this paper.Comment: In proceedings of MTS/IEEE OCEANS, 2018, Charlesto
Multidisciplinary Development of Autonomous Underwater Vehicle Fleet
Eco-Dolphin – Cooperative Fleet for Surveillance Mission
SIAM, Society for Industrial & Applied Mathematics, members have been working for two years on the design, construction and testing of three highly integrated and streamlined autonomous underwater vehicles called Eco-Dolphins. This project is being developed at Embry-Riddle Aeronautical University’s Daytona Beach campus. The Leverage lab is used to create detailed mathematical models and conduct preliminary research for both electrical and mechanical systems. The campus Composites lab is used for the fabrication of structural and aesthetic components used by the high adaptable platform. The Autonomous Underwater Vehicle testing is conducted in the Universities Nonlinear Waves lab. The first phase of design, production and assembly of the yellow Eco-Dolphin prototype has been done in twelve months. The design includes an internal attitude control system, combined with internal propulsion from brushless direct current thrusters, thus allowing the vehicle to ascend and descend. The Eco-Dolphins promise is to be a unique, highly optimized and a competitive underwater vehicle fleet. The team has also successfully completed the second phase of the program, which involved tracking the Eco-Dolphins while submerged underwater. Work has been conducted to add a GPS system for surface tracking. Converting the acoustic system from tethered to wireless to make the ground station more robust. The Eco-Dolphin is configured with recently developed control system software that utilizes a relay combination of Wireless, Sonar and GPS radio wave communication. The current progress on the blue Eco-dolphin will be completed by the summer of 2014, for testing in littoral waters of central Florida. Through the addition of three sequential (yellow, blue, red) vehicles, therefore allows for better position and orientation data to be sent to the teams buoy network. The three vehicles, three buoy communication structure, multiply the data points collected for surveillance and underwater mapping purposes. This additional complexity improves the reliability and increases the application of the product through error elimination software. The team gives hands on research experience to SIAM members through applied mathematics. The outcome of the research goals, results in the application of many fields of study beyond mathematics. When combined the fleet can cooperatively fulfill multitask missions, advanced surveillance and environmental monitoring can be conducted. This opportunity opens the way for better balance between sustainable developments of the coastline
A geometrical approach to the motion planning problem for a submerged rigid body
The main focus of this paper is the motion planning problem for a deeply submerged rigid body. The equations of motion are formulated and presented by use of the framework of differential geometry and these equations incorporate external dissipative and restoring forces. We consider a kinematic reduction of the affine connection control system for the rigid body submerged in an ideal fluid, and present an extension of this reduction to the forced affine connection control system for the rigid body submerged in a viscous fluid. The motion planning strategy is based on kinematic motions; the integral curves of rank one kinematic reductions. This method is of particular interest to autonomous underwater vehicles which can not directly control all six degrees of freedom (such as torpedo shaped AUVs) or in case of actuator failure (i.e., under-actuated scenario). A practical example is included to illustrate our technique
Decoupled Sampling-Based Motion Planning for Multiple Autonomous Marine Vehicles
There is increasing interest in the deployment and operation of multiple autonomous marine vehicles (AMVs) for a number of challenging scientific and commercial operational mission scenarios. Some of the missions, such as geotechnical surveying and 3D marine habitat mapping, require that a number of heterogeneous vehicles operate simultaneously in small areas, often in close proximity of each other. In these circumstances safety, reliability, and efficient multiple vehicle operation are key ingredients for mission success. Additionally, the deployment and operation of multiple AMVs at sea are extremely costly in terms of the logistics and human resources required for mission supervision, often during extended periods of time. These costs can be greatly minimized by automating the deployment and initial steering of a vehicle fleet to a predetermined configuration, in preparation for the ensuing mission, taking into account operational constraints. This is one of the core issues addressed in the scope of the Widely Scalable Mobile Underwater Sonar Technology project (WiMUST), an EU Horizon 2020 initiative for underwater robotics research. WiMUST uses a team of cooperative autonomous ma- rine robots, some of which towing streamers equipped with hydrophones, acting as intelligent sensing and communicat- ing nodes of a reconfigurable moving acoustic network. In WiMUST, the AMVs maintain a fixed geometric formation through cooperative navigation and motion control. Formation initialization requires that all the AMVs start from scattered positions in the water and maneuver so as to arrive at required target configuration points at the same time in a completely au- tomatic manner. This paper describes the decoupled prioritized vehicle motion planner developed in the scope of WiMUST that, together with an existing system for trajectory tracking, affords a fleet of vehicles the above capabilities, while ensuring inter- vehicle collision and streamer entanglement avoidance. Tests with a fleet of seven marine vehicles show the efficacy of the system planner developed.Peer reviewe
Advancing Climate Change Research and Hydrocarbon Leak Detection : by Combining Dissolved Carbon Dioxide and Methane Measurements with ADCP Data
With the emergence of largescale, comprehensive environmental monitoring projects, there is an increased need to combine state-of-the art technologies to address complicated problems such as ocean acidifi cation and hydrocarbon leak
detection
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