‘Printed’ ROV puts design within easy reach
ArcheoRov, the first 3D printed ROV
At less than 60cm long ArcheoRov seems too small to be holding the key to revolutionising the sector. And though its ability to ‘swim’ like a fish is novel, its groundbreaking advantage isn’t obvious to a cursory glance: it’s the first to be 3D printed.
As Emanuele Rocco of Witlab, in Italy explained, it’s not the speed of its physical response but “the acceleration of the design that’s really impressive”. This customised ROV only took a bare 10 weeks from concept to delivery.
Constructed in Witlab, Rovereto with the Arc Team from the Austrian University of Innsbruck (and a contribution from Rovereto science students), ArcheoRov is rather different to many others as it has been designed to swim, rather than stay in one spot.
Dr Rocco explained that the ROV’s most significant characteristic is it can orient its body up or down to get the best view from one of its two cameras, whether this is on a horizontal or vertical surface and “it just can tip itself on end and sink or rise in seconds” he added. This makes it ideally suited to sweeping visual surveys, making it much more tailored for the job than more standard ROVs designed for general use and static sampling.
Secondly is its size, the archaeologists are interested in hard to reach sites: stone-age relics preserved in mountain lakes “means the ROV needs to be small and light enough to put in a backpack”, explained Dr Rocco.
The two batteries sit inside in sealed, pressure resistant units and are frankly a little oversized for the ROV as it stands, but Dr Rocco said this is “a matter of pragmatism” as the archaeologists may, in future, want to fit different cameras or larger, stronger lights depending on mission. The all important manoeuvrability is given by three, 130W T100 electric thrusters: two at the front facing forward and one downward facing thruster at the rear, each yielding 2.36kg of push. This is enough to tow the wifi communication buoy along that provides the data link to the surface... "and even me when I got tired”, said Mr Rocco.
The design process didn’t begin with the usual tranche of calculations but with something much more fun: the team started with a handful of ideas, then printed up initial candidates on one of Witlab’s rapid prototyping machines.
There’s no doubt it is rapid: plastic 3D printing fuses together layers of nylon powder or filament, directed by 3D CAD data. As it’s built up layer by layer, the result can be a very complex structure incorporating voids and channels that would otherwise take weeks of work to create. It also helps designers that Witlab has a complete fast prototyping suite plus milling machines able to handle soft metals plus electronic prototyping tools.
As it stands, 3D printing of something like the ArcheoRov requires just a few days of waiting.
Having constructed the plastic outline, it was then a case of simply attaching the motors – powering them from a source outside the tank - and seeing what configuration gave the kind of response the teams were looking for.
“We tried three prototypes on the way,” Dr Rocco said, taking less than a month to arrive at the final design. After this, another six weeks were spent on refining it and kitting it out: this version will be able to go down a little over 100m (the next one will be able to reach 350m depths).
Finally the technology has had its first outing in Madrone Alpine Lake, Trentino, at 2,400m altitude.
However, the most salient point is the design remains ‘open source' so anyone can access it and build a ROV themselves, given a CAD package and a link to a 3D printer such as the one Witlab provides. On the same note, ArcheoRov is using the Robot Operating System (ROS) a set of open source software libraries and tools. “This is important because by doing so we are enabling the developer community to easily add their custom software extensions or even make ArcheoROV semiautonomous,” he added.
Therefore Dr Rocco believes we are about to herald in an entirely new phase “where professionals will be experimenting, assembling a ROV or drones in exactly the way they’d like for their purposes, whether that’s marine biology, pollution monitoring, even accident searches”.
He concluded: “Now it’s quick and cheap, people can design their own ROV.”
By Stevie Knight