Playing with model trains and calling it graph theory

Re:Playing with model trains and calling it graph theory by jpmattia on Friday May 03, 2019 @05:37PM (#19822523)

While we're on the subject of ancient history, Prof Jim Roberge's course on feedback systems (6.302) famously included a final lecture incorporating his love of model trains.

The goal of the lecture was that the train should have a constant speed despite hills introduced into the track. In order to measure the speed of the train, he noticed that there was a small glitch that would occur as the motor's armature switched polarity, and so a time measurement of the glitches was proportional to the speed of the engine.

[I took the course in 85 and still remember it, so he left something of an impression. A couple of generations learned analog feedback from this course. RIP Prof Roberge.]

Edit: By some lesser miracle, his lectures are on youtube. The train lecture was last.

https://www.youtube.com/playlist?list=PLUl4u3cNGP62in17jH_Di...

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Re:Playing with model trains and calling it graph theory by dekhn on Friday May 03, 2019 @06:16PM (#19822755)

Thanks, that's pretty cool. When I was a kid I could never get my model train to go very fast. It wasn't until about 30 years later that I learned enough EE to understand the problem. Eventually I learned enough to build a self-balancing robot using PID control but I'm always amazed at college students who can do this stuff easily.

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