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The Brennan self-balancing monorail [video]
- Animats 3y agoThere's a model railroader who builds these things.[1] They balance and corner fine. With one rail, the models can't take power from the rails. They run on AA batteries. There's also a drivable 2-wheeled gyro-balanced car from the late 1960s.[2] These things work, but wobble too much. With active control, though... [1] https://www.youtube.com/watch?v=ifroNPpK9jQ&list=PLE006F2D7330BBE12 https://www.youtube.com/watch?v=ifroNPpK9jQ&list=PLE006F2D73... [2] https://www.youtube.com/watch?v=TTCVn4EByfI https://www.youtube.com/watch?v=TTCVn4EByfI
- jacquesm 3y agoThat second one is just gorgeous. That guy has every reason to look as smug as he does!
- JKCalhoun 3y agoYeah, not a stretch to imagine someone could make a Star Wars Landspeeder version.
- Animats 3y agoIt really is gorgeous. It's really a new build; the original had been abandoned and then hacked into being a no-gyro 3-wheeler. There are some parts from the original in the new one.
- jacquesm 3y agoI once met a guy in Sault Ste. Marie that was rebuilding a Fox Moth from nothing more than the original manufacturers plate. Piece by piece, and every now and then someone would remember where a part of the original plane had ended up and then they'd go and collect it and make it like new again. Endless patience. He'd been at it for many years, his only wish was to either fly it or see it fly while he was still alive, the plane is now done and it is on display but it hasn't flown afaik. I'm really happy someone took the trouble to rebuild this machine and to preserve it for the future, so much has been lost. Especially stuff made of steel. Edit: here's the plane: https://bushplane.com/exhibits/bushplane-collection/dehavilland-foxmoth/ https://bushplane.com/exhibits/bushplane-collection/dehavill... When I last saw it in 2006 it was still mostly a frame and large collection of parts, it's amazing to see it in one piece, apparently they were going to fly it in 2019 but I can't find anything of that.
- dsego 3y agoAnd here I thought that the gyro motorcycle that appeared a decade ago was a novel invention. https://youtu.be/jICGl9jmulc https://youtu.be/jICGl9jmulc
- Doxin 3y ago> With one rail, the models can't take power from the rails. That immediately has me thinking about what sort of zany pantograph mechanism you'd need to get overhead power working. You might be able to get away with a really wide pantograph that has the right curve.
- Levitating 3y agoWait, this isn't a Tom Scott video?
- franky47 3y agoThat's what I was expecting too.
- toxik 3y agoDidn’t he quit?
- Ballas 3y agoHe didn't quit making videos entirely, he only "quit" releasing them to a set schedule.
- tgsovlerkhgsel 3y ago... but hasn't released a single video since then, yet.
- Fervicus 3y agoQuite remarkable. Too ahead of its time? Wonder why it never got revisited
- modeless 3y agoSeems like the requirement for gyroscopes in every car would be a deal breaker.
- neom 3y agoCould you make a gyro car? Akin to a locomotive? I don't exactly know how it would work but I was thinking we have locomotives so we don't need to put engines in every car. The thing I'm thinking about is that the gyro is kinda both a measurement device in a way, and also the system that actuates. Could these systems be separated, simplified, and scaled-down? I don't know, I'm not an engineer, just thinking aloud. :)
- jerf 3y agoWith the technology of the time I do not believe there is a solution. Modern technology might be able to turn the car couplings into something that can actively manage their tilt relative to each other, thus allowing them to propagate the balance beyond a single gyro car, but there's a lot of PID-controller-type [1] math that would go into determining if this was even possible with real, physical objects trying to control things the size and mass of train cars in a train track environment. The computations are probably not that difficult in 2024 but trying to actually deliver the correct forces in a timely manner may be difficult if not impossible. There aren't always solutions, or practical solutions, to the PID equations in the real world. Plus, I'm sitting here imagining the size of the electric motors we're trying to torque the cars against each other with and it's hard not to say that we're better off just having two tracks and putting those motors on the wheel themselves. (Which then collapses to having a locomotive setup like we have now.) In the "power/control/price" triangle we're basically forced to take the max on power and control, so these are going to be ferociously expensive if they can be built at all. And there's some bad failure cases that I just don't know that you can mitigate. Having 30 minutes after power loss to evacuate passengers is generally going to be enough, but cargo can't be evacuated on that timeline. And that's not the only failure case. A seized gyro is going to be catastrophic and even a single one could take the whole train down, even with that PID control system (which is going to be a stretch even without also having to build in buffers for failed gyros). The fact that a 2-track-train can just sit there for extended periods of time with no power is one of those advantages you don't even think about until you try to take it away. Guy was a genius though. It's basically an analog computer that keeps itself upright that you can ride. The final design is amazing with its judo-esque approach to using physics against itself. But I don't think it can be scaled up much beyond "neat tourist attraction". I'd ride one as a tourist attraction, though. [1]: https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%E2%80%93derivative_controller https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%...
- Jolter 3y agoWell, that was the most annoying commercial break ever.
- tareqak 3y agoDo e-scooters and the like self-balance in this way? It would be cool to have self-balancing rollerblades.
- Jolter 3y agoAnything with rolling wheels will have some tendency to continue straight once the wheels are spinning, but they don't help to stabilize in corners. On small wheels, the effect is very small in any case, especially since the scooter and its batteries are relatively quite heavy.
- arijun 3y agoThe gyroscopic effect of wheels has a minimal impact on the tendency of things like bicycles to remain balanced; the majority of the effect comes from the rake of the front wheel (i.e. that the point where it touches the ground is ahead of the pivot point of the front post). That gyroscopic effect of the wheel works well when the whole device is wheel (think hoop rolling), but when you start adding weight that's not spinning (like someone riding a scooter), the effect falls off. Edit: it seems that neither the gyroscopic effect nor rake are sufficient to explain bicycles' self-stability: https://en.wikipedia.org/wiki/Two-mass-skate_bicycle https://en.wikipedia.org/wiki/Two-mass-skate_bicycle
- phyzome 3y ago« the point where it touches the ground is ahead of the pivot point of the front post » The other way around -- the contact patch of the tire is behind the projection of the head tube onto the ground. I love that there are actually three different stability mechanisms. I wonder if there are others!
- mring33621 3y agosee https://2swiftboards.com/ https://2swiftboards.com/, which is an electric scooter with no handlebars. At low speeds, a high-friction headset adds stability by damping the tendency to turn and flop. At higher speeds, the reverse fork rake and spinning wheels provide stability. This is my read on it, as someone that uses a 2Swift as a commuter vehicle, but the physics-based explanation may differ.
- Donaldbendo 3y ago[flagged]
- FrustratedMonky 3y agoIncredible. Sometimes it seems like we were more advanced in the past.
- phyzome 3y agoWhere do you get that from? We still come up with crazy designs all the time (that are rejected in favor of robustness, compatibility, etc.)
- JKCalhoun 3y agoThe crazy designs from 100+ years ago though were more impressive though because of the limitations imposed from not yet having electronics, computers, software.... They had to be incredibly clever mechanically. I too was impressed from the video the way the guy iterated in clever ways to address issues that came up. And, as I say, iterated within a relatively narrow realm of options. Ads a counter-example, I watch hobbyists on YouTube these days that build and fly various R/C contraptions that would not have been do-able in the days of small gasoline engines and huge, heavy radio receivers. It's like today you can take a sheet of foam from Lowes, strap on some high efficiency brushless DC motors, double-sticky-tape on an ESC, receiver and be flying that sheet of foam by the afternoon. Too easy.
- FrustratedMonky 3y agoThere must be enough people that were similarly amazed and/or fascinated to vote it to front page. Maybe my phrasing was not to your liking. I'm sorry you've lost your sense of wonder.
- phyzome 3y agoAre you kidding? I freaking love this invention. I just don't think it's evidence for some kind of civilizational decline.
- FrustratedMonky 3y ago"civilizational decline" OH. Didn't realize that is how you took it. That was not my intent. What I really meant, is the old style 'mechanical controls' do seem very inventive compared to today, because todays world is so much 'electronic controls'. Some of these solutions from 100+ years ago, seem revolutionary now, because we have forgotten that 'method' of solutions. I am not sure current engineers could come up with some of the same "old-fashioned" solutions that worked 100 years ago. Maybe because we are so advanced now, that it is almost like "that knowledge is lost"? Could go on, it is a worry I do have about actual collapse. Lets say we lost power grid or supply chain disruption. It would be huge task for current engineers to figure out how to re-build things again, with old technology.
- kabouseng 3y agoI wonder if gyro drift would eventually cause problems?
- croes 3y agoWhat happens on a power failure?
- ethagknight 3y agoThe video says the gyros would continue spinning for 30 minutes (inertia) in the event of power failure. Enough time to get the kickstand down I guess.
- ethagknight 3y agoSome things im curious about with this concept. 1) why not mount the gyro horizontally? 2) would the addition of a very large (say 10ft diameter) primary load bearing wheels (like a bicycle) assist with stability at speed 3) video mentions a need for gyros in each car, I wonder if such a system could only require a complicated active control system in the front (and maybe rear) car, and the rest could have simpler 'passive' gyro arrangements to assist in relative stability to the active controls? 4) could modern control systems materially improve upon this? For example, an all-electric drive for the intermediate gyros off a primary power unit is pretty trivial. 5) why wouldn't they want the flywheels higher up, like mounted over the roof? quicker reaction time and more force per rotation? Thats all for now.