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Underwater robot

Hunting down Canadian interceptor aircrafts in Lake Ontario

The Dedave underwater vehicle developed by researchers of Fraunhofer institutes uses embedded CAN networks. Recently, it was used to search for historic aircrafts.

The “Raise the Arrow” team behind the autonomous underwater vehicle (Photo: Fraunhofer)

The autonomous underwater vehicle developed is a deep-diving robot. Its first chance to prove itself in action was the searching for historic test models of a Canadian interceptor aircraft in Lake Ontario. The mission has been a success, with two of the confirmed eight aircraft models already tracked down. Designed for deep-water diving, the underwater robot is capable of diving down to depths of 6000 m to explore the seabed for sources of oil or minerals. The 3,5-m light-weight construction was developed by researchers at the Fraunhofer Institute of Optronics, System Technologies and Image Exploitation IOSB in Ilmenau and Karlsruhe. The vehicle is ready for large-scale industrial production, and has been licensed by the Canadian maritime technology company Kraken Robotics, who have renamed it Thunderfish Alpha. Since the end of July, the underwater robot – which looks something like a space shuttle – has been helping the company hunt down the Avro Canada CF-105 interceptor in the waters of Lake Ontario. In September, Thunderfish Alpha got its first hit, locating the first and shortly after even a second model of the Arrow jet – a huge success, since people have been looking for wreckage of the supersonic aircraft for 50 years.

Replica of the Avro Canada CF-105 Arrow (Photo: Ken Mist, CCSA)

Sonar images generated in real-time

“We program in the route beforehand, and then Thunderfish Alpha autonomously scans the desired area of the lake bed using high-tech sonar equipment,” said Helge Renkewitz, a researcher at Fraunhofer AST, a branch of Fraunhofer IOSB in Ilmenau (Germany). The scientist and his colleagues were on location for the search. Based on acoustic echoes, the diving robot generates sonar images in real-time, which were analyzed by the experts directly after the dive. Image data can be transferred wirelessly, and give precise indications of potential item locations.

Up to the end of September, the team was on the hunt. “During this period, Thunderfish detected 400 objects, 100 were already examined. Two of them proved to be the lost Arrow models that are scheduled for salvage before the end of the year,” said Renkewitz. Meanwhile, the search has had to be put on hold because of the weather; it is to be continued from June to September 2018. All in all, the underwater robot has to scan a surface area of 64 km2.

First searching success with the Fraunhofer technology (Photo: Fraunhofer)

The vehicle is powered by eight batteries, each weighing 15 kg. A release mechanism allows exchanging them in a few minutes. A single-battery charge is enough for 20 h of exploration, and the software for the battery management system was developed in house at the Fraunhofer Institute for Silicon Technology ISIT in Itzehoe (Germany). The robot also carries navigation sensors, two sonar modules, propulsion and steering units, communication modules, the software management system, and data storage devices. For the internal communication of electronic devices a CAN network is used. It connects all control units and the electric motors. It offers certain advantages: for one, minimizing the amount of cables and connections minimizes malfunctions. What’s more, attaching new modules, sensors or test devices to the CAN network is a quick process. “The modularity of our autonomous underwater vehicles (AUV) was one of the reasons Kraken chose Dedave,” said Renkewitz.

Five-year collaboration agreement with Canadian partner

As part of a five-year research agreement with Kraken Robotics, Fraunhofer IOSB will be consulting for the company and helping it develop new versions of the AUV. As the software has not been licensed out, developing it will remain Fraunhofer’s exclusive responsibility. The licensing agreement stipulates that Kraken gains exclusive rights only once the AUV surpasses a weight of 750 kg. That is to say, if Fraunhofer designs new variants with other sensors that result in a lesser weight, then Fraunhofer is free to offer those modified vehicles to other customers as well.

Avro Canada CF-105 Arrow
The Avro Canada CF-105 Arrow is a delta-winged supersonic interceptor aircraft developed in Canada in the late 1950s. While the aircraft was under development, numerous tests were conducted from the shore of Lake Ontario. These included attaching the models to carrier rockets and accelerating them to supersonic speeds. The jet propulsion engines and prototypes dating from this testing period are still scattered over a large portion of Lake Ontario to this day. There has been a huge public interest about this legendary fighter plane since its abrupt ending in the late 1950’ies.


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Fraunhofer IOSB