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.
Well not just battlebots, real life 6th gen fighters now all lack the vertical stabilizer so they have to rely on very sensitive real-time software control of the elevator/spoilerons to do banks and yaws. Not sure if it counts as under-actuated but they are tremendously difficult to steer without computer control.
Generally these aircraft still have three+ actuators, they just replace the rudder with differential spoiler or split elevons. Three actuators, three axes. Same number, so it's not 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).
I'm not super familiar with heavy equipment like dozers and such, but some of them may also have a single motor to pressurize hydraulic fluid and valves to articulate the various pistons. So may be able to make the argument there too
That is common and you can't run two different cylinders at the same time. Depends on how the pump and valves are plumbed of course. Sometimes you can run more than one but you split power.
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.
Only to figure out that the vibration in his drone was due to vibration and it was easily fixed by swapping to rotors that he should've used in the first place. Oh well! Live and learn.
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.
Perhaps there are specific applications where the payload spinning could be an advantage, imaging/scanning perhaps (which in the video is going to be in the next iteration for the builder).
I’m sure glad we are making immense progress towards the dystopian hell where massive swarms of mini drones are hunting down obsolete and marked for termination flesh bots, aka humans.
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.
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/
If I understand correctly, those are single rotor but NOT single motor. This is a single motor design, which is why it's neat. There are no additional control servos/motors.
I wanted to learn more about photography, I started asking an LLM and it helped me immensively. Definitely not the same realm but if you wanna pick up new skills, LLMs have tons of beginner friendly ways to explain things!
For optics through photography (not CCD operation or post processing which are vast subjects themselves) I highly recommend View Camera Technique 7th Edition and Scientific America Image, Object and Illusion as general audience applicable introductions.
Now with LLMs? Super easy. Just ask for step by step instructions to build a standard drone. You will learn about micro controllers, physics, pcbs, 3d printing etc.
If you have some time available definitely worth it.
A good engineering course would cover most (if not all) of the skills necessary to do this. This is notable because the person is young and wielding a broad slice of the discipline with maturity.
gyroscopes drift over time, that's why typically you need a kalman filter to combine the strengths of various sensors, magnetometers, where available, are bad at resolution, but don't drift.
I strongly doubt adding a ton of extra weight in aerodynamic surfaces, and drag, and complex mechanical parts, to avoid a few motors/servos is worth it in that context.
Every gram of weight you remove is another gram of explosive you can add. Also consider the difference in supply lines for aerodynamic surfaces and mechanic parts and motors and servos. If you have four hundred servos, you can make one hundred quadcopters, or four hundred of these things. If you only have one hundred control boards powerful enough to control the single motor design though, you can still only make one hundred. (Tho the quadcopter can lift 4x the weight)
What's interesting is that the Ukrainians are building drones near their front lines because if they build them too far away and ship them in, the game has evolved and those drones are already yesterday's news.
A fixed wing drone only needs one motor, the control is easier, and the physics are more favorable for carrying high ordnance. I'm skeptical that this is going to change much.
It's cool in that it can hover and do quadcopter type flight with only a single motor, and it's that second part that is interesting, because a fixed wing can also do a prop hang, but it can't do quadrotor-like flight from there.
It's usefulness is likely to be in other areas -- mainly applications where that flight mode is important.
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.
Neat. I wonder if you could use the air it generates by having directional ports louvers that open and allow the air to flow for more control.
Would need 2 more servo, left/right port louvers.
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?
Likewise. Even companies like Saildrone where ~100% of the marketing before 2025 was about mapping the oceans and autonomous storm monitoring with their bright orange craft are now releasing videos with missile launching pods attached to navy gray versions: https://www.saildrone.com/news/us-navy-rimpac-lockheed-marti...
Do you want superpowers to be able to wage wars, foreign or domestically, with hordes of non-human combatants that can't refuse orders or defect on moral grounds?
To be fair, a lot of it is moving to drones killing drones.
My prediction is that future wars will actually involve increasingly fewer humans and will be more about tech+manufacturing vs. tech+manufacturing. And of course insurgents + lowcost tech vs. increasingly nonlethal hightech.
This would allow wars to continue without as much of the growing political backlash.
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.
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.
Inspires me to try and start doing some robotics.
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...
https://www.youtube.com/watch?v=d80oXSCcHTk
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/
If you have some time available definitely worth it.
Smaller, cheaper, more numerous offensive drones?
What's interesting is that the Ukrainians are building drones near their front lines because if they build them too far away and ship them in, the game has evolved and those drones are already yesterday's news.
It's cool in that it can hover and do quadcopter type flight with only a single motor, and it's that second part that is interesting, because a fixed wing can also do a prop hang, but it can't do quadrotor-like flight from there.
It's usefulness is likely to be in other areas -- mainly applications where that flight mode is important.
[0] https://youtube.com/watch?v=aEPf0QHVuMM
https://www.youtube.com/watch?v=u2cETOyuJ20
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 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
My prediction is that future wars will actually involve increasingly fewer humans and will be more about tech+manufacturing vs. tech+manufacturing. And of course insurgents + lowcost tech vs. increasingly nonlethal hightech.
This would allow wars to continue without as much of the growing political backlash.