Valeport sensors chosen for new micro AUV

11 December 2019

ecosub-µ5_svp_sensor_and_nose_cone.jpg (26.6 K)

Working in collaboration with ecoSUB, Valeport sensors are now being used to autonomously acquire sound velocity profiles on a new 0.5m low-cost micro AUV.

Jointly developed in the UK by Planet Ocean and the Marine Autonomous Robotics Systems (MARS) group at the National Oceanography Centre, Southampton (NOCS), ecoSUB aims to make autonomous underwater technology both accessible and affordable for science, commercial and defence applications through the use of advanced design techniques, materials, sensors, artificial intelligence (AI) and manufacturing methods.

The ecoSUBµ-5 has a 500m depth capability, 48-hour endurance and the ability to carry a range of specialist sensors. A key design specification was maintaining a cylindrical form, with no projecting control surfaces or antennae limiting launch from a surface, underwater or sonobuoy tube. This was achieved using a moving mass within the vehicle to control the pitch angle, which also enables the combined antennae and location beacons - coaxial to the main body - to be adequately exposed for surface communications and GPS positioning. When the mass is fully forward, the vehicle can stand on its nose. This also affords a steep dive capability, thus providing a unique profiling capability.

ecosub-µ5_svp_pressure_tolerant_electronics.jpg (42.0 K)

One of the many applications of micro-AUV technology is an alternative to the XBT (expendable bathythermograph), traditionally used to obtain a temperature profile of the water column and locate the thermocline and later adapted to enable calculation of the speed of sound. An ecoSUB-µ5 combined with a specially adapted Valeport SV (sound velocity) sensor is able to provide real-time, physical measurement of speed of sound, accurate depth information, and the ability to generate multiple SV profiles at several locations autonomously.

Ingenious data compression techniques enable ecoSUB to deliver a full sound velocity down cast with speed of sound, depth and lat/longitude every metre through 290m in a single Iridium Short Burst Data (SBD) message, before being deployed to a new location to repeat the process. This can be extended to 500m with up and down casts using multiple SBD messages or by adjusting the interval from <1m to >1m,  as required. Decision-makers are thus supplied with detailed 3D maps of the underwater acoustic environment over a wide area, in near real-time, in advance of the host vessel's arrival at the location.

The first five vehicles, produced in May 2018, underwent extensive sea trails before being supplied to the customer and subsequently prepared for deployment on a northern North Sea exercise around the turn of the year. This will see them being remotely piloted, using the Iridium channel and a specially designed Cbase station allowing over the horizon communications in an internet-denied environment. New missions or alterations will be uploaded on-the-fly when the vehicles surface.

Mindful of the value and sensitive nature of some of the data collected, facilities for remote data erasure have also been incorporated.

Image supplied: ecoSUB-µ5-SVP in communication mode

Image supplied: ecoSUB-µ5 SVP sensor and nose cone

Image supplied: ecoSUB-µ5 SVP pressure tolerant electronics

Valeport Ltd
St Peters Quay
Devon TQ9 5EW
T: +44 1803 869292
F: +44 1803 869293

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