All-Analog DIY Segway Project 141
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."
Re:The Land Before CPUs (Score:5, Interesting)
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:My thoughts exactly (Score:4, Interesting)
Re:My thoughts exactly (Score:5, Interesting)
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 (Score:5, Interesting)
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.