East Bay Guide to Understanding PID Loops

So here's my take on explaining this topic.  Light on the math, and heavy on the intuitive (I hope!) understanding.

I expect to take another stab at explaining the topic again, and I'm working on plugging in a physics engine to do some real-time simulation.  It's kind of like a game, can you tune the PID loop to lock the copter into position?  (update: it seems that enough people are liking this version that it will stay around for a while.  Sometime or the other I want to learn processing.js, and I'll try an online pid program as my learning project.)

I mention Khan Academy as my inspiration for this, not to imply that it will be anywhere near as good. Anyways, let me know if if this is useful at all or where I've gotten things wrong!

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