Page 42: of Marine Technology Magazine (November 2023)

CASE STUDY ROV DVL TECH

Tethys Robotics’ underwater drone in

Lake Zurich during a harbor inspection.

All image courtesy Nortek

Tethys Robotic’s new ROV

Leverages Nortek DVL Tech new Remotely Operated Vehicle (ROV) from Swit- pulse along a minimum of three acoustic beams, each pointing zerland’s Tethys Robotics is using a Nortek DVL to in a different direction. complete its navigation solution. Jonas Wüst, CEO

A at Tethys Robotics, set out to meet these challenges

Bottom Tracking Near a Moving of working ef? ciently, safely underwater following a student

Riverbed or Sea Floor research project at Eidgenössische Technische Hochschule During Tethys Robotics’ ? rst discussions with Nortek, the

Zürich (ETH Zurich), a public university in Switzerland. DVL500 Compact had just been released. This is a 500 kHz

Tethys Robotics’ goal was to build an autonomous under- DVL in a small form factor – a good match for the requirements water robot capable of being deployed in rough water with of the small ROV the team at Tethys Robotics was working on.

currents of up to 2 m/s. It would need to be capable of high- By combining the convenient size of the higher-frequency accuracy positioning and inspection of its immediate environ- DVL1000 with the superior bottom-tracking range of tradition- ment in near-zero visibility. This required a very accurate un- ally larger 500 kHz systems, the DVL500 Compact provides derwater navigation solution. developers of small robotic systems with a reliable, high-per- formance solution for aiding underwater navigation and control.

“The bene? t of the DVL500 Compact for Tethys Robotics

Control in Swirling Currents

If this can be achieved it provides immense advantages to was the good penetration of the DVL’s signals through the operators, as they can focus on controlling the robot relative to bottom, river or lakebed,” said Nortek’s Cristobal Molina, the the stationary physical surroundings, without having to worry Senior Sales Engineer working on the project.

about trying to control it against swirling currents.

To meet these positioning and navigation needs for their Autonomous Mapping in

ROV, Wüst and his team equipped their small ROV with a

Strong Currents and Poor Visibility

Nortek DVL that meets their speci? c requirements for achiev- Their work with the underwater robot has attracted a lot of at- ing bottom tracking and current measurements in the most dif- tention. “Tethys Robotics is an invaluable partner for developing ? cult conditions, securing navigational accuracy. underwater robots with unique capabilities, such as for autono-

The DVL, or Doppler Velocity Log, is an acoustic sensor that mous mapping of submerged infrastructures in strong currents estimates velocity in water relative to the bottom, using a long and poor visibility,” said Kai Holtmann, Deputy Head of the 42 November/December 2023

MTR #8 (34-47).indd 42 11/28/2023 10:01:25 AM