Technology
Endurance test for AWI robot "Tramper" in the deep sea
AWI researchers use the “Tramper” robot for the first time on the deep-sea floor on their latest expedition on board the research vessel Sonne
[16. September 2015]
During their latest expedition on board the research vessel Sonne (So 242-2), researchers and engineers from the Alfred Wegener Institute (AWI) successfully used the autonomous AWI robot, Tramper, for the first time on a deep-sea mission. The continuous-track vehicle’s first demo missions took place at a depth of about 4150 metres in an area of the subtropical Southeast Pacific around 850 km off the coast of Peru.
Tramper was developed by AWI deep-sea researchers as part of the Helmholtz Alliance Robotic Exploration of Extreme Conditions (ROBEX) and will be used in future in the FRAM project as an autonomous robotic platform for oxygen measurements in the Arctic deep-sea - particularly at the AWI deep-sea observatory HAUSGARTEN there.
The AWI crawler can remain at the sea floor for periods of a year and take weekly measurements of oxygen profiles in the seabed. “This new technology allows us for the first time to take deep-sea measurements throughout the entire year, and to use this data to determine seasonal variations,” explains AWI researcher Frank Wenzhöfer.
“The scope of the task meant that during development we were faced with the challenge of finding technical solutions that allow the crawler to function autonomously throughout its deep-sea mission, and at the same time it has to be able to move around the deep-sea floor without any problems,” says AWI engineer Johannes Lemburg, who built the deep-sea robot together with colleagues from the AWI and ROBEX Alliance partners.
During its planned year-long mission, Tramper will repeatedly travel a short distance – autonomously and without remote control – to the measuring point, where it will take photographs and oxygen-profile measurements. It will then sleep for a week before waking up and going through the whole process again. This means that the crawler doesn’t have to travel at high speeds or cover long distances, but instead needs to operate using as little energy as possible. “Tramper travels at a maximum speed of 13 metres per minute, but even at this speed unwanted clouds of sediment dust can be created,” adds Johannes Lemburg.
The crawler will be positioned on the sea floor with the help of a video-controlled launcher system, which has also been newly developed. The final “letting go” is done by means of an electrically controlled quick-release catch. This avoids having to use the conventional acoustic release mechanism, which takes several seconds.
Tramper is fitted with foam blocks suitable for deep-sea use to provide buoyancy. As a result, in water the robot weighs just 20 kilograms instead of the 653 kilograms it weighs on land. The robot is based on the crawler “Wally”, which was built at Jacobs University in Bremen. While Wally only has one camera and is cable-connected, Tramper also has to carry a battery, a ballast weight, an actuator, locating equipment and the oxygen-measuring device. “At the end of its mission, the team on board the research vessel can acoustically locate and release the crawler: when it receives a signal, it jettisons its ballast weight and independently rises up through the water column,” explains Johannes Lemburg.
Back at the surface, Tramper can be located via the Argos satellite system, its exact position is determined by means of a UHF transmitter, and it can then be recovered by the research vessel.
Researchers were able to record the first demo missions 4146 metres down on the sea floor with the aid of the ROV Kiel 6000 from Geomar, Helmholtz Centre for Ocean Research. “Recordings like this are rare, as there isn’t usually another ROV nearby during such missions. Thanks to the calm sea, the ship’s excellent positioning and the Kiel6000 team’s great work, this time we were able to make these almost unique film recordings showing how the robot behaves an a real deep-sea environment with obstacles,” comments Frank Wenzhöfer.
The team on board the SONNE will now give the crawler its first scientific task: measuring oxygen profiles in the sea floor in a manganese nodule field.
More information on Tramper’s mission and the research expedition So 242-2 is available at oceanblogs.org