How do you make a drone that can navigate through a forest? By putting it in a cage, then letting it bump into whatever it wants.
Some UAVs may soon land on powerlines, deliver cars, and save lives, but flying through the unpredictable wreckage of a disaster area has been, until now, too dangerous for your average hexacopter.
An article in the Journal of Field Robotics describes the first tests of the GimBall, a drone that appears pretty indestructable, even during flight. The drone is designed to literally collide with objects and continue moving. To make this possible, the team trades obstacle-detecting sensors for a spherical rigid frame that can roll on and around obstacles while in flight, protect against debris, and propel it along the ground. It looks like this:
Image: Journal of Field Robotics
The drone was also tested in a series of pre-programmed autonomous flights in a fairly thick forest. The algorithm ordered GimBall to fly up to an altitude of a meter, then to head north until the “end of [the] experimental area.” As you can see in the video above, its a terrifyingly efficient bushwacker, even with its roll-cage being made with polygons that are too wide to protect against thin branches.
The engineers originally debuted the tech last year, but have a few plans for GimBall V2: They plan to tighten up the roll cage’s openings, adding thin force sensors to the cage itself, and further optimize the mathematical collision program to enable GimBall to efficiently drive on the ground or ride along an uneven surface. All of these are changes are inching towards a drone that can stay in the air, no matter what.
It’s a design that’s already making its way into commercial drones, on a rudimentary level, at least. Parrot’s new mini drone features a roll cage—the drone can travel on the ground and bump off walls with no problem. It’s not nearly as sophisticated, however, as the GimBall, so let’s take a look at its inner workings.
The team, led by Adrien Briod and Przemyslaw Kornatowski, of Switzerland’s Ecole Polytechnique Federale de Lausanne, had to design a frame with geometry that could keep the drone stable, airborne, and controllable when ricocheting or powering through something.
Briod’s team uses an internal frame that’s made from a type of free-rotating camera-stand, called a Gimbal System—hence the name. On the inside of the drone’s Gimbal System’s there’s a propeller, stabilization system, and camera, and on the outside, there’s a roll cage. The whole thing works because, when it hits something, the outside frame rotates and absorbs shock, while only minimally affecting the orientation of its propeller. When a collision happens, the propeller only rocks enough to slightly impact its flight path.
Image: Journal of Field Robotics
As you can see, the GimBall is fine with bouncing off stuff and continuing about its day. One of the main concerns with drones these days is their propensity to crash—there’s lots of value in one that manages not to do that.