All-Analog DIY Segway Project

An anonymous reader writes "One of the zany hacker-makers here at MIT just finished this DIY Segway project (video). Difference from the others: it's all analog. The controller is built without a microprocessor or even digital logic. It does use a gyroscope like the real Segway. The functionality looks fairly basic, but the fact that the controller works at all is amazing. The guy has a ton of other projects on his site too. Definitely worth a read for people who enjoy building things."

Comments

and here we have a hacker

[chronoss2010]

a real one that invents and makes stuff...imagine that , quick arrest the terrorist(/sarcasm)

SEGFAULT

[PatPending]

Best. Name. Ever. for this

Re:SEGFAULT

[camperslo]

The ultimate SEGFAULT was a sad one, the CEO of Segway dying from running his off a cliff by his home.

http://www.huffingtonpost.com/2010/09/27/jimi-heselden-segway-boss_n_739983.html

Controllers were analog before they were digital.

[RoverDaddy]

Digital controllers -emulate- analog behavior (at least many of them do). There's a pantload of research and science behind analog control.

The Land Before CPUs

[Glendale2x]

Why is this amazing "that the controller works at all"? There was a time before microprocessors, you know, and they did fun things like travel in space without them.

Re:The Land Before CPUs

[Burdell]

The computers that flew were digital, but the computers that tested them were analog. My father worked on the Saturn V guidance system, and they built one of the earliest "hardware in the loop" simulation setups to test the software and flight-certify the computers that flew. Digital computers of the day were not fast enough to simulate the inputs and monitor the outputs in real time, so the simulation was built with analog computers.

Re:The Land Before CPUs

[skywatcher2501]

Talking about spaceflight, the Russians only recently replaced the analogue Soyuz control system with a fully digital one.

Females?!

[lul_wat]

They are all at MIT?! I'd have studied harder in highschool if they'd only told us.

Re:Females?!

[Colonel Korn]

They are all at MIT?! I'd have studied harder in highschool if they'd only told us.

The MIT recruiting video sent to my high school might have convinced you.

A pair of serious undergrads, one male and one female, are working in a lab. The glassware is very impressive and filled with bubbling food coloring or whatnot. The lights are low to draw attention to the Science. Then the two look at each other knowingly, sweep the contents of a benchtop onto the floor and start making out atop it to the wail of an electric guitar.

403 Forbidden

[noidentity]

I guess the webserver also is running on an all-analog server, which is now in a "halt and catch fire" state.

Re:403 Forbidden

[PatPending]

Likely due to a SEGFAULT.

My thoughts exactly

[betterunixthanunix]

Why is it amazing that an analog control system works?

Re:My thoughts exactly

[0100010001010011]

Kids these days couldn't imagine trying to implement a PID controller without a microprocessor. It does make it easy to watch what is going on.

Watching large governors work is pretty cool. No electronics to speak of. Just a properly tuned set of weights and some geometry.

Re:My thoughts exactly

[seanadams.com]

It's not amazing but it's certainly harder. Probably higher part count, more electrical noise to deal with, harder to debug, harder to implement delays and state machines, more wiring etc. It's just impractical for most purposes.

Re:My thoughts exactly

[Jarik C-Bol]

Actually, they are pretty awesome even at a small scale. I took a small engines class once, where we each where given a lawn mower engine to tear down and rebuild. Lawn mowers have governors in them (dinky little plastic ones usually) butI swear, we spent several hours playing with them once we got down that far into the engines.

Re:My thoughts exactly

[robot256]

Analog is not precise enough (people think).

Speaking as a controls engineer, they have obviously not done much digital controls. You have to worry about things like sampling rate, aliasing, round-off error, and digital noise introduced into the (inescapably) analog parts of the circuit. For a simple system, a properly-designed analog controller is much easier to implement, and has advantages like "infinite" sampling rate, graceful failure modes, white (gaussian) noise as opposed to odd frequencies introduced by sampling and clock frequencies, and no programming bugs or crashes.

Analog controllers for simple linear systems (like telescope mirrors) are in virtually every spacecraft ever launched for precisely those reasons. Only recently has the push for miniaturization driven some simple systems into digital FPGA controllers.

Re:My thoughts exactly

[udippel]

And I have mod points, but don't give you any. 'Troll' is awfully harsh, I agree. I'd rather give you some 'un-informed'.
The higher part count is surely on the side of the digital controller. Just look at the diagrams offered: analog means direct processing of signals, no A/D. Just some op-amps, pwm, done.
Harder to debug? Nonsense. You debug with a voltmeter instead of a logic analyzer.
You are right with respect to advanced controlling, though, like counting, timing, delays. But none is needed here, some filters are just enough, and filters are implemented easier with some RCs around an op-amp. Also, you need a bridge. A bridge is much more simple if build in an analog manner. So your 'just impractical' is a good reason to not give you any mod points. It might be your opinion, and you sure may have one, but to me, an EE with some experience in developing controllers, it doesn't hold water in the case of a gyroscope.

Re:I would like to join the chorus

[Jane Q. Public]

Heisenberg and Planck might disagree with you on that.