The former shipyard RDM Rotterdam is today a big playground for companies and education. One of the research projects that students and teachers are engaged in at the Innovation Dock on the RDM Rotterdam Campus is the aquabots project of RDM Centre of Expertise (RDM CoE, part of Hogeschool Rotterdam).
And we are not talking about the toy robotic fish, which brighten up an aquarium in the shape of a shark, moonfish or seahorse. The aquabots in question in this case are small, robotic, emission-free, autonomous vessels, with a hull length of up to two metres and, most complex of all, aquabots that can operate under water.
Challenge
Wilco Braam, Senior Lecturer in Research & Innovation at the Institute EAS and director of the RDM CoE at Rotterdam University of Applied Sciences, says: "The aquabots project came out of a challenge for the students. They were challenged to develop a vessel that can cross the Maas independently. So the aquadrones ultimately had to become 'Maas-worthy'."
The challenge was composed of three steps: first, the aquadrone had to be able to sail independently in the basin (20 x 10 x 0.70 m) inside the 'Innovation Dock' on the Campus. Next, they went sailing in the so-called outdoor lab. That outdoor lab is the Dronehaven, an enclosed experimentation site for aquadrones in open water. The Dronehaven opened in 2016 as part of Rotterdam's Dokhaven. Eventually, all the tests and developments led to two Maas-worthy drones: the Final Maas and the Aftica.
Applications
Aquadrones can be used for all kinds of applications, such as water quality measurements, removing plastic debris from water, depth measurements, quayside inspections and camera inspections of ship hulls, for example. On and under water. Since June 2017, boats sailing in the covered basin on the Campus can also be controlled directly from the 20-year-old ship's bridge, located in the Innovation Dock. Peter Verheijen, the 'director of Maritime and Offshore' at the RDM CoE, proudly shows us the bridge.
"We got this old bridge from a submarine when it was no longer in service. The students here completely revitalised it themselves, including new controls and related software." Meanwhile, in the basin, several aquabots sail adrift and we get to test how agile they prove to be.
Water and pressure resistance
Making an aquadrone may seem simple, but appearances can be deceiving. After all, water is a hostile environment for robots. There is, of course, the risk of short circuits and corrosion, but water also does not allow radio waves to pass through. Communicating and navigating under water are therefore quite a challenge. The most applicable and accessible techniques for this are sonar and piezo technology.
Leon van Soest, college student in mechanical engineering, shows us the controls of an aquabot for underwater use in the basin.
"The biggest challenge in manufacturing these aquabots is the high pressure on them. Then we are talking about 10 to 11 Bar. So everything has to be extremely water- and pressure-resistant," he explains. "Aquabots are fitted with so-called thrusters on all sides," Leon continues. "These are remote-controlled propellers that ensure great manoeuvrability and stability of the drone. The thrusters also provide the dynamic positioning needed to withstand the current. Indeed, to be able to sensor well, you need to be able to control the nine dimensions of movement." One of the developments currently being worked hard on is non-contact propulsion using magnetic transmissions. Then there is one less worry when it comes to leakage points.
Aquabots is seen as a development platform for unmanned boating. The application of robots and autonomous vessels equipped with sensors is an important development for the maritime sector.
By: Walter Kooren
