A couple years ago, we wrote about the Dual-rotor embedded multilink Robot with the Ability of multi-deGree-of-freedom aerial transformatiON—Dragon, of course. It’s one of the wildest drones we’ve ever seen, consisting of four pairs of gimbaled, ducted fans, with each pair linked together through a two-axis actuated joint, making it physically flexible in flight to a crazy degree.
Dragon is one of those robots with literally more degrees of freedom than it knows what to do with—in the sense that the hardware is all there. But the trick is getting it to use that hardware to do things that are actually useful in a reliable way. In 2018, Dragon was just learning how to transform itself to fit through small spaces, but now it’s able to adapt its entire structure to manipulate and grasp objects.
While we’ve seen a bunch of different flavors of drones with arms stapled to them, making the structure of the drone itself into the manipulator is a much more elegant solution.
In a couple of recent papers (in the International Journal of Robotics Research and IEEE Robotics and Automation Letters), Moju Zhao and colleagues from the University of Tokyo present some substantially updated capabilities for Dragon. It’s much more stable now, although as you can see in the video, Zhao seems to not be totally sure how resilient it is:
Impressive, right? And here it is turning some real industrial valves. Note that the force for the valve turning comes from propeller thrust, not the actuators:
It’s a little strange to watch this thing, honestly, because it’s behaving much like an under-development mobile manipulator. And I guess it is, technically, a mobile manipulator, just not in a form factor that we’re used to associating with that term, since it’s continuously airborne. But it’s easy to imagine all of the ways that Dragon could mobile-manipulate the heck out of things that a ground-based manipulator simply could not, and while we’ve seen a bunch of different flavors of drones with arms stapled to them for this very reason, making the structure of the drone itself into the manipulator is a much more elegant solution.
Or rather a potentially elegant solution, since Dragon is obviously still very much a research project. It weighs a hefty 7.6 kilograms, and while its payload is a respectable 3.4 kg, the maximum flight time of 3 minutes is definitely a constraint that will need to be solved before the drone makes it very far out of the lab environment. To be fair, though, this isn’t the focus of the research at the moment—it’s much more about expanding Dragon’s capabilities, which is a control problem. With the bananas amount of degrees of freedom that the system has, it’s theoretically capable of doing any number of things, but getting it to actually do those things in a reliable and predictable manner is quite the challenge.
As if that all wasn’t enough of a challenge, Zhao tells us that they are considering giving Dragon the ability to walk on the ground to extend its battery life. I can’t quite picture what that’s going to be like, but if it makes Dragon into even more of a dragon, I’m here for it.