Posted by hakonjdjohnsen 12 hours ago
Inspires me to try and start doing some robotics.
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.
>Not sure if it counts as under-actuated
You're referencing the fact that it's dynamically unstable, and thus needs to be stabilized with a computer. That's a different thing.
You can also have aircraft which are under-actuated yet are dynamically stable. One example is a parafoil, which achieves controlled flight using only two actuators (pull lines).
they are not humanly pilotable without computers. they are inherently unstable.
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.
https://hackaday.com/2020/06/25/building-and-flying-a-helico...
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/