The Brennan self-balancing monorail [video]

https://www.youtube.com/watch?v=kUYzuAJeg3M

by Fervicus • 2 years ago

146 59 2 years ago

youtube.com

Animats2• 2 years ago

There'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=PLE006F2D73...

[2] https://www.youtube.com/watch?v=TTCVn4EByfI

jacquesm2• 2 years ago

That second one is just gorgeous. That guy has every reason to look as smug as he does!

JKCalhoun2• 2 years ago

Yeah, not a stretch to imagine someone could make a Star Wars Landspeeder version.

Animats2• 2 years ago

It 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.

dsego• 2 years ago

And here I thought that the gyro motorcycle that appeared a decade ago was a novel invention. https://youtu.be/jICGl9jmulc

Doxin• 2 years 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• 2 years ago

Wait, this isn't a Tom Scott video?

franky47• 2 years ago

That's what I was expecting too.

toxik• 2 years ago

Didn’t he quit?

Ballas• 2 years ago

He didn't quit making videos entirely, he only "quit" releasing them to a set schedule.

Fervicus• 2 years ago

Quite remarkable. Too ahead of its time? Wonder why it never got revisited

modeless• 2 years ago

Seems like the requirement for gyroscopes in every car would be a deal breaker.

neom2• 2 years ago

Could 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. :)

meche123• 2 years ago

Because you have to replicate the same complicated mechanism for all the cars. Moreover, if a gyro in one of cars malfunctions the whole train is at risk.

Another problem is that the system is reactive, meaning that there is a lot of shaking and balancing that is quite unacceptable - think about drinking a cup of tea in such a wobbly train even on straight lines, while on curves it's not staying horizontal by design.

Yet another problem is that it can't share the current infrastructure without major switch changes while sharing the infrastructure the other way around is impossible.

And in the end all of this effort for trying to fix a problem that doesn't really exist, at least not in Europe where most of the rail infrastructure was already built 100 years ago.

Reason077• 2 years ago

”while on curves it's not staying horizontal by design”

Worth noting that modern tilting trains do this quite successfully (on two rails!), in order to run faster on tracks with tight curves. By “leaning in” to curves, you make the ride more comfortable, not less.

Tilting trains are used extensively on the UK’s West Coast Main Line, for example.

1letterunixname2• 2 years ago

And there's zero redundancy. If 1 of those piston seals or valves fail, the whole train is at risk for catastrophic failure.

Clever engineering without a necessary, defensible, competitive business advantage usually becomes either a hobby or an art project.

georgesimon4• 2 years ago

Yes, the part of the video that said this would work on existing infrastructure is entirely wrong.

It could be interesting with it's own infrastructure, though my first thought is that it might be better suited to tunnels, being able to maximize use of the tunnel profile.

1letterunixname2• 2 years ago

No. Watch the video.

woah• 2 years ago

What's the benefit?

joshuaheard• 2 years ago

In the video it explains it only uses half the track material since it only has one track instead of two. It can also go faster since it leans into corners and doesn't derail like two track trains.

kevin_thibedeau• 2 years ago

The double flange wheel wouldn't work with existing rail switches.

Jolter2• 2 years ago

Well, that was the most annoying commercial break ever.

rsanek• 2 years ago

https://github.com/ajayyy/SponsorBlock

philsnow• 2 years ago

yt-dlp has sponsorblock integration, just saying

btbuildem• 2 years ago

Yeah that was pretty jarring

tareqak• 2 years ago

Do e-scooters and the like self-balance in this way?

It would be cool to have self-balancing rollerblades.

Jolter2• 2 years ago

Anything 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• 2 years ago

The 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

FrustratedMonky4• 2 years ago

Incredible. Sometimes it seems like we were more advanced in the past.

phyzome4• 2 years ago

Where do you get that from? We still come up with crazy designs all the time (that are rejected in favor of robustness, compatibility, etc.)

JKCalhoun2• 2 years ago

The 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.

FrustratedMonky4• 2 years ago

There 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.

dudeinjapan• 2 years ago

It reminds me a bit of TRIZ thinking https://en.wikipedia.org/wiki/TRIZ. It's not that we were "more advanced", it's just that Brennan had a clear-headed approach to use mix of elements (gyroscopes, differential/asymmetry, pneumatics)

FrustratedMonky4• 2 years ago

yeah, these old mechanical control devices seem like a real life 'steam punk'.

samatman• 2 years ago

This is occasionally true, but that is very infrequent.

The example I like to cite is swords. Despite swords playing no role in modern combat, modern swords (the real ones, not knockoff/costume swords) are of a higher quality, fit, and finish, than anything a knight or samurai would have been able to obtain. While being dramatically cheaper, in the sense that someone would have many fewer hours to work to obtain one.

There are counterexamples of products which would have been cheaper at a given quality in the past, or readily available when they're difficult to obtain in the present. But once you rule out things made with ivory and whalebone, these are scarce indeed.

kabouseng• 2 years ago

I wonder if gyro drift would eventually cause problems?

croes• 2 years ago

What happens on a power failure?

ethagknight2• 2 years ago

The 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.

ethagknight2• 2 years ago

Some 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.

The Brennan self-balancing monorail [video]

Related Stories