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I'll bite. What espresso machine? Temperature control and temperature profiling is actually quite bad on most machines. It's actually mostly that people don't e
by jzelinskie 5y ago
I'll bite. What espresso machine? Temperature control and temperature profiling is actually quite bad on most machines. It's actually mostly that people don't even have a good way to measure temperature at the grouphead to really know if their coffee is improving or if they've just improved their temps at the boiler.
- lmilcin 5y agoI built this for Rancilio Silvia (see explanation of the model in another answer in this thread). I chose Silvia mainly because it doesn't have its own electronics, it is all 230V AC wiring, thermostats, switches, etc. I made myself a precise thermometer with PT 1000 probe inside coffee puck and I learned the temperature can vary as much as 10-15 degrees. I first used PID but was not satisfied with long settling time, because when water is right temperature at the boiler it still needs to pass through huge hunk of metal that will determine to large extend the end temperature of brew water. So I built a bit more complex algorithm with the aim of first getting the water a little hotter in the boiler (while grouphead is still cold) and then slowly adjusting setting for the boiler as the grouphead heats up. But there were still problems, for example pumping cold water into the boiler threw everything into chaos. Then the problem that you get temperature readouts with delays and offsets. That's when I decided to just build a more complete model of the system that does not only take current but also past states of the system into account.