I built a drone with only one motor [video]

Underactuated robotics are so cool. In the hobby BattleBots community, there is a design where the whole robot only has a single motor, but it's able to move in any direction and damage the opponent, all just by controlling the single motor's speed.

Most robots have at least three motors, two drive sides and a weapon motor. The trick to getting away with one is integrating an impactor into the chassis of your bot, using the single wheel to spin up to ~3k RPM, then by tracking the rotation angle of the bot as it spins, you speed up a little while the wheel is pointing where you want to go, and slow it down a little when it's pointing the other direction.

This is well worth the entire watch. It feels like what would any hacker do in trying to figure out how to make something they want to exist. Also very well presented and good pace.

Inspires me to try and start doing some robotics.

This is from the same guy (Joshua Bird) that built the 4 axis 3d printer (and special algo for it too) https://www.youtube.com/watch?v=VEgwnhLHy3g

A really neat concept. It uses a special hinge design, a magnetic encoder and torque modulation to control the lift of the rotor as it spins. Completely negates the need for a conventional helicopter's swash plate.

The single motor does have the pretty major downside that it spins the moment it's in the air. I suspect a 2 motor drone with a tail motor would be a lot more practical. But I really like how mechanically simple the rotor hinge design is - it pushes all the complexity into the control algorithm.

The Picocolissimo also uses only one motor: https://www.youtube.com/watch?v=UE47bcCxT_I

Side note, I used those same moteus controllers for a decidedly less energetic use case (two axis gimbal for RF satellite tracking) and found them to be super high quality and the lead developer always super helpful. Been a few years but def worth a look if you want to get into motor control.

Serious question - how do you even learn all of the skills to do something like this? Where would you start?

Reminded me of the Manhack: https://half-life.fandom.com/wiki/Manhack

Yeah that's probably the coolest thing I've seen all month. How could you not like this?

It's a pretty cool concept, however, fails to mention coaxial rotor design that has a single motor and has much simpler control systems. I am also curious on how this affects frame vibration.

This is a newer trend in mechanical design that leverages more complex control software to overcome mechanical issues. A good example is https://turntide.com/

Slap a MEMS gyroscope on that bad boy. https://www.vectornav.com/resources/inertial-navigation-prim...

Amazing work this is really innovative and it could be applied to a larger drones provided that the margin of error is reduced.

How will this new tech affect the current drone war between Russia and Ukraine?

Smaller, cheaper, more numerous offensive drones?

It's incredible that changes in velocity still work to adjust the angle of the blades even at the insane speeds they're moving at. I would never have thought that was possible.

I have to wonder why this guy didn't give his drone a leash while testing so it couldn't go flying off. It's the first thing that popped into my head, so I'm sure it's something he thought of as well and didn't use for a good reason. Maybe a string would get caught in the blades?

I am torn about drone tech now.

I used to be super stoked about it.

But watching drones kill civilians kind of ruined it. [0]

Then again ... they do put a dent in superpowers powers apparently so ... like I said ... I am torn.

[0] https://www.bbc.com/news/videos/czdmrm6y7r0o

There's also been a few people building monocopters with a fixed, non tilting motor and prop, and four servo motor actuated fins at the bottom that can be used for thrust vectoring and to counter rotational forces.

https://www.youtube.com/watch?v=u2cETOyuJ20