Some people aren't undergrads who took Control Engineering courses.
Yeah the title is kinda meh. Teenagers on the robotics team I mentor have figured out PID loops and calibrating them (and how funny robots are when you don’t)
I was on one of those robotics teams, and I recall this document being passed around as suggested reading on that team. It’s probably worth considering that this was written in 2000, when it was a more niche topic, and was probably itself a part of what made PID programming more accessible in the first place.
I mean, Control Theory has been part of engineering cirricula for a lot longer than that. But the internet wasn't nearly as pervasive then, and Wikipedia wouldn't be founded until the next year.
PID design was on my undergrad Chem Eng 2nd year curriculum in the 90s. I took it the year Starcraft came out, so my grade suffered a bit.
Can confirm, I broke the robot once when I accidentally had the sign flipped on the PID error term.