undefined | Better HN

0 pointsdeepspace6y ago0 comments

I used to be a control systems engineer in a previous life, working with ultra high precision position control systems, where PID just does not cut it.

Best approach I found was high-sample-rate LQE / LQR control - the LQE part is a Kalman filter, which is a piece of cake now, but was very hard to achieve with available hardware 25 years ago.

The biggest enemy of simplicity was nonlinearities, and much of the 'art' of precision digital control system designs was in knowing how to linearize them through software tricks and/or adapt the algorithm to provide piecewise linear control.

0 comments

1 comments · 1 top-level

Gibbon16y ago

I worked on but didn't design the control algorithm for a zone controller where each of the five zones interacted with each other because they were part of a six foot tall quartz tube. There was compensation for the heating elements being nonlinear. And because the thermal mass was basically nothing radiation losses dominated it's behavior. Some of the control variables were squared then scaled. And zero overshoot was allowed for the hottest zone. And because it was a batch process it had to heat up quick.

I had to re-tune one after they replaced the quartz chamber.

Blah.

j / k navigate · click thread line to collapse