The enhanced Folaga: a hybrid AUV with modular payloads

Caffaz, A.; Caiti, Andrea; Calabrò, Vincenzo; Casalino, Giuseppe; Guerrini, Piero; Maguer, Alain; Potter, John R.; Tay, Harold; Turetta, Alessio

doi:10.1049/pbce077e_ch14

Cited by 16 publications

(7 citation statements)

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“…The eFOLAGA (enhanced FOLAGA) was jointly designed by the Interuniversity Research Center on Integrated Systems for Maritime Environment in Genova, Italy, Graaltech s.r.l., Genova, Italy, the National University of Singapore, Singapore, and CMRE, La Spezia, Italy, to operate at three different levels [11]- [13]:…”

Section: The Autonomous Platformmentioning

confidence: 99%

Glider-based seabed characterization using natural-made ambient noise

Nielsen

Siderius

Muzi

2015

OCEANS 2015 - Genova

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Seabed characteristics (geoacoustic properties and scattering strength) are critical parameters for sonar performance predictions. However, this bottom information is considered very difficult and expensive to achieve in the scientific community. In this report, an efficient method for inferring the seabed properties is presented; it relies on a previous methodology using long moored or drifting hydrophone arrays. Results from sea trials demonstrate the feasibility of using the technique by deploying a hybrid autonomous underwater vehicle hosting a unique hydrophone array consisting of a five-element vertical line array and a four-element tetrahedral array. Seabed reflection and layering properties are estimated from sea surface generated ambient noise acquired during two trials in different shallowwater areas. Results from numerical modeling, data analysis and experimental measurements are presented with emphasis on comparing the seabed characterization at different locations with different bottom properties. The results obtained from both experiments demonstrate the potential of using autonomous underwater vehicles for seabed characterization and surface vessel tracking.

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Section: The Autonomous Platformmentioning

confidence: 99%

Glider-based seabed characterization using natural-made ambient noise

Nielsen

Siderius

Muzi

2015

OCEANS 2015 - Genova

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“…This modeling technique for vehicles having a variable position of the CoG has been also used in Caiti and Calabro`1 5 for a hybrid AUV; see also Caffaz et al 16 for further details. In Table 1, we show the numerical parameters used in this work.…”

Section: Underwater Glider Modelmentioning

confidence: 99%

Switching control of an underwater glider with independently controllable wings

Caiti

Calabrò²,

Geluardi

et al. 2013

Proceedings of the Institution of Mechanical Engineers, Part M:

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The dynamic, control-oriented model of an underwater glider with independently controllable wings is presented. The onboard vehicle's actuators are a ballast tank and two hydrodynamic wings. A control strategy is proposed to improve the vehicle's maneuverability. In particular, a switching control law, together with a backstepping feedback scheme, is designed to limit the energy-inefficient actions of the ballast tank and hence to enforce efficient maneuvers. The case study considered here is an underwater vehicle with hydrodynamic wings behind its main hull. This unusual structure is motivated by the recently introduced concept of the underwater wave glider, which is a vehicle capable of both surface and underwater navigation. The proposed control strategy is validated via numerical simulations, in which the simulated vehicle has to perform three-dimensional path-following maneuvers

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“…20,[52][53][54][55][56] Recently, the development of Autonomous Underwater Vehicles (AUVs) has reached a stage where they have become a viable technology for a number of applications ranging from military, 57 to commercial, 58,59 to research sectors. 60 Combining ambient-noise-based bottom survey with the versatility 61 and simplicity of AUVs would produce an attractive, cost-effective bottom-survey system. Due to the nature and size of these vehicles, hydrophone arrays mounted on these systems need to be very compact, and the application of short arrays to bottom characterization has received some interest.…”

Section: Marine Ambient-noise Processingmentioning

confidence: 99%

“…The GLASS volumetric array -Side and front view.The goal of the project is to transition Harrison and Simons' technique, so far implemented only using moored or drifting arrays, to an autonomous vehicle equipped with a compact array. A new type of hybrid AUV named eFOLAGA61 is being jointly developed by the University of Genova (Genova, Italy), the CMRE and the manufacturer GraalTech s.r.l (Genova, Italy). The vehicle is equipped with jet pumps and blade propellers, which has the advantage, over ordinary gliders, of more flexible maneuver features, including e.g.…”

mentioning

confidence: 99%

Advances in Autonomous-Underwater-Vehicle Based Passive Bottom-Loss Estimation by Processing of Marine Ambient Noise

Muzi¹

2000

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Accurate modeling of acoustic propagation in the ocean waveguide is important to SONAR-performance prediction, and requires, particularly in shallow water environments, characterizing the bottom reflection loss with a precision that databank-based modeling cannot achieve. Recent advances in the technology of autonomous underwater vehicles (AUV) make it possible to envision a survey system for seabed characterization composed of a short array mounted on a small AUV. The bottom power reflection coefficient (and the related reflection loss) can be estimated passively by beamforming the naturally occurring marine ambient-noise acoustic field recorded by a vertical line array of hydrophones. However, the reduced array lengths required by small AUV deployment can hinder the process, due to the inherently poor angular resolution. In this dissertation, original data-processing techniques are presented which, by introducing into the processing chain knowledge derived from physics, can improve the performance of short arrays in this particular task. Particularly, the analysis of a model of the ambient-noise spatial coherence function leads to the development of a new proof of the result at the basis of the bottom reflection-loss estimation technique. The proof highlights some shortcomings inherent in the beamforming operation so far used in this technique. A different algorithm is then proposed, which removes the problem achieving improved performance. Furthermore, another technique is presented that uses data from higher frequencies to estimate the noise spatial coherence function at a lower ii frequency, for sensor spacing values beyond the physical length of the array. By "synthesizing" a longer array, the angular resolution of the bottom-loss estimate can be improved, often making use of data at frequencies above the array design frequency, otherwise not utilized for beamforming. The proposed algorithms are demonstrated both in simulation and on real data acquired during several experimental campaigns.

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The enhanced Folaga: a hybrid AUV with modular payloads

Cited by 16 publications

References 0 publications

Glider-based seabed characterization using natural-made ambient noise

Glider-based seabed characterization using natural-made ambient noise

Switching control of an underwater glider with independently controllable wings

Advances in Autonomous-Underwater-Vehicle Based Passive Bottom-Loss Estimation by Processing of Marine Ambient Noise

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