Many of us have become familiar with the distinctive sound of multirotor toys, a sound frequently punctuated by sharp sounds of crashes. We’d then have to pick it up and repair any damage before flying fun can resume. This is fine for a toy, but autonomous fliers will need to shake it off and get back to work without human intervention. [Zha et al.] of UC Berkeley’s HiPeRLab have invented a resilient design to do so.
We’ve seen increased durability from flexible frames, but that left the propellers largely exposed. Protective bumpers and cages are not new, either, but this icosahedron (twenty sided) tensegrity structure is far more durable than the norm. Tests verified it can survive impact with a concrete wall at speed of 6.5 meters per second. Tensegrity is a lot of fun to play with, letting us build intuition-defying structures and here tensegrity elements dissipate impact energy, preventing damage to fragile components like propellers and electronics.
But surviving an impact and falling to the ground in one piece is not enough. For independent operation, it needs to be able to get itself back in the air. Fortunately the brains of this quadcopter has been taught the geometry of an icosahedron. Starting from the face it landed on, it can autonomously devise a plan to flip itself upright by applying bursts of power to select propeller motors. Rotating itself face by face, working its way to an upright orientation for takeoff, at which point it is back in business.
We have a long way to go before autonomous drone robots can operate safely and reliably. Right now the easy answer is to fly slowly, but that also drastically cuts into efficiency and effectiveness. Having flying robots that are resilient against flying mistakes at speed, and can also recover from those mistakes, will be very useful in exploration of aerial autonomy.
[IROS 2020 Presentation video (duration 14:16) requires free registration, available until at least Nov. 25th 2020. One-minute summary embedded below]
Survive crashes and gets back in the air on its own? Sweet!
The paper on arxiv.org (under V. experimental results) includes a link to a 1min. youtube video:
https://youtu.be/9v3vB4RaOew
That was supposed to be embedded after the break, but apparently I accidentally deleted it sometime during editing.
I’ve put it back in, thank you for pointing it out!
Nice.
Next it will be saving power by rolling down hills…
That icosahedron (with inscribed rectangles) is also a baby toy! It’s Manhattan Baby “Skwish“,
One problem will be aerodynamics. Wires and strings generate a huge amount of drag compared to streamlined braces; a tensegrity shell will have a noticable negative effect on speed and battery life, especially if the drone is flown near top speed. The shell will also make crosswind handling worse, regardless of drone speed.
If it can reorient itself on the ground why can’t it do it in the air, better to keep flying than crash every time you bump into something.
Most of them can do that already, but it doesn’t always work. So you’d still need a recovery plan as backup, hence this paper.
Similar idea from a few years ago, though it was a 6DOF multirotor instead of a traditional quad https://m.youtube.com/watch?v=KTGGI3016OA
https://m.youtube.com/watch?feature=youtu.be&t=192&v=Wt8pXwj-qZc
Is this autonomous? There is a person holding a flight controller, but it’s not clear if it’s under full time manual control or if the human is backup to take over from autonomous algorithm as needed.