82 Insight | UUVs The challenge, however, for Kaufmann and his fellow engineers (at the time, researchers at ETH Zurich) in inspecting lake shores or riverbeds was that currents in such shallows are very strong, and AUVs capable of withstanding such environments and capturing quality data are rare. “We had originally considered just engineering software for an existing robot that might have been otherwise mechanically suited to working in shallow, space-constrained, high-current waters to meet customer needs. Our work at university ETH Zurich had been focused on key software enabling precise, autonomous, underwater 3D mapping, but we didn’t feel there was one on the market that was designed and open to work with third-party code, such as our own code for autonomous control and navigation,” Kaufmann says. “On top of that it’s important that software and hardware work together harmoniously. Having precise localisation, integrating and analysing with machine learning the output of all the collected data, the number and orientation of thrusters on a robot, how they’re integrated or oriented, and how much energy is stored on the robot may seem like small details, but they really build up to have significant interactions on how well the software can execute tasks in the long term.” Unveiled in August 2024, the Tethys ONE weighs 35 kg in air and runs for up to four hours on battery power, integrating a wide range of payloads, including a 4D manipulator and grabber arm, an underwater metal detector, a magnetometer, and CTD and pH sensors, as well as various sonars (along with a DVL and IMU for navigation). It is capable of operating in waters as deep as 300 m and maintaining its position amid currents of up to 3.5 knots. “As well as needing highly-capable control software to withstand currents as strong as that, the body was heavily optimised in CFD to prevent it being pushed or pulled too much,” Kaufmann says. “We’ve also designed it with 10 thrusters angled about the body, as well as software for data fusion of a lot of sensors – for dense navigationand-control input data, as well as 3D mapping. Together, these feed into effective station-keeping and manoeuvring, including omnidirectional movement and attitude adjustment.” Tethys Robotics has also used the Tethys ONE to inspect hydroelectric plant facilities; its autonomous station-keeping enables it to view turbines and tunnels closely without the turbines needing to be shut off, which is a significant boon to plant operators. It is also able to autonomously inspect dam walls with its acoustic sensors to scan for cracks and generate geo-referenced 3D acoustic and photogrammetric models. Having validated its technology in the lakes and rivers of otherwise-landlocked Switzerland, and in the Baltic Sea, Tethys Robotics is looking into offshore energy markets such as wind-power fields, where currents are extremely strong and autonomy can be of great benefit to inspection work. Demonstrations and pilots are planned in early 2025. Seafloor surveys While UUVs have long been developed and deployed in deep-sea surveying applications such as hydrocarbon exploration, ROVs and conventional AUVs suffer from certain inefficiencies when it comes to the type of longterm data-gathering missions typically entrusted to automated (but wholly immobile) ocean-bottom nodes, such as those applied in ocean-floor geophysics. Kyrre Tjøm, CEO and founder of Norway-based iDROP, identified these inefficiencies in 2008, while serving as a consultant on engineering a new generation of geophysical datagathering nodes. “We brought two ROVs to place our survey nodes on the seafloor, piloting them from the vessel to retrieve nodes from a node-handling frame we’d lowered onto the seabed, and carry them to predefined installation points. It was time-consuming, labour-intensive, and the systems were placed at great risk due to the harsh conditions of the water. In fact, we ‘lost’ an ROV on the first job after an umbilical snatched on something,” Tjøm recounts. February/March 2025 | Uncrewed Systems Technology The Oceanid autonomous node is designed for highly energy-efficient swarm surveying of seafloor locations for up to 180 days at a time (Image courtesy of iDROP)
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