Environmental Description in the Design of Fish Farms at Exposed Locations

Kristiansen, David; Aksnes, Vegard; Su, Bitao; Lader, Pål; Bjelland, Hans Vanhauwaert

doi:10.1115/omae2017-61531

Cited by 2 publications

(3 citation statements)

References 13 publications

(18 reference statements)

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“…This is motivated by greater water flows, which are beneficial in terms of waste dispersal and water quality, as well as the lack of available sheltered locations. Conditions such as current speeds of 0.6 ms −1 and significant wave heights of 3.5 m have been reported in these new aquaculture locations [10]. As aquaculture net pens are flexible structures, they are deformed by current-induced drag forces [11].…”

Section: Introductionmentioning

confidence: 85%

“…A DVL This section proposes a method for approximating the geometry of a local region of the net pen in front of the ROV based upon the DVL measurements. It is assumed that the net pen can be approximated as a linear plane given by the equation f (x, y, z) = −x + by + cz + d = 0 (10) expressed in {d}, where f can be calculated from the four DVL beams. Furthermore, this section shows how one can calculate the ROV yaw angle and distance relative to the approximated net pen.…”

Section: Net Pen Geometry Approximation By the Use Ofmentioning

confidence: 99%

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Autonomous ROV Inspections of Aquaculture Net Pens Using DVL

Amundsen¹,

Caharija²,

Pettersen³

2021

IEEE J. Oceanic Eng.

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This paper presents a method for guiding a remotely operated vehicle (ROV) to autonomously traverse an aquaculture net pen. The method is based on measurements from a Doppler velocity log (DVL) and uses the measured length of the DVL beam vectors to approximate the geometry of a local region of the net pen in front of the ROV. The ROV position and orientation relative to this net pen approximation are used as inputs to a nonlinear guidance law. The guidance law is based upon the line-of-sight (LOS) guidance law. By utilizing that an ROV is fully-actuated in the horizontal plane, the crosstrack error is minimized independently of the ROV heading. A Lyapunov analysis of the closed-loop system with this guidance law shows that the ROV is able to follow a continuous path in the presence of a constant irrotational ocean current. Finally, results from simulations and experiments demonstrating the performance of the net pen approximation and control system are presented.

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Section: Introductionmentioning

confidence: 85%

Section: Net Pen Geometry Approximation By the Use Ofmentioning

confidence: 99%

Autonomous ROV Inspections of Aquaculture Net Pens Using DVL

Amundsen¹,

Caharija²,

Pettersen³

2021

IEEE J. Oceanic Eng.

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“…Realistic estimates of the environmental load levels at a given site and structural condition rely on adequate descriptions of the marine environment, including the exposure to wind, waves and current , see e.g. Bore and Amdahl (2017) and Kristiansen et al (2017).…”

Section: Introductionmentioning

confidence: 99%

Ship collision analysis with a floating offshore fish farm

Zhang¹,

Amdahl²,

Kristiansen³

2019

Trends in the Analysis and Design of Marine Structures

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Due to limited nearshore areas and great impact to local ecosystems, the aquaculture industry is moving the fish farms from nearshore to more exposed sea regions where waves and current are stronger. Like other offshore installations operating at sea, fish cages are also exposed to the risk of collisions from attendant or visiting vessels. This paper evaluates the structural strength of a fish farm concept subjected to supply vessel collisions by the use of nonlinear finite element simulations. The fish cage is made of ring-stiffened columns and supporting braces. A 7500-ton supply vessel is used as the striking vessel. Several collision scenarios with both coupled and decoupled methods are simulated on representative impact locations. The results are discussed with respect to the impact resistance, energy and structural damage.

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Environmental Description in the Design of Fish Farms at Exposed Locations

Cited by 2 publications

References 13 publications

Autonomous ROV Inspections of Aquaculture Net Pens Using DVL

Autonomous ROV Inspections of Aquaculture Net Pens Using DVL

Ship collision analysis with a floating offshore fish farm

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