I tried the heater guardian today with a gain of 0.003 and a set point of 25 degrees seeing as it seems to have reached equilibrium around this value with no loop running and 1W input overnight. It looks like it overshot initially and is turning around and coming back to the set point of 25 degrees C now. Thermistor 1 is the loop sensor but I have marked the turning point on thermistor 2 in the attached picture. We still have some range on the PZT actuator (JAC-PZT_DRIVER_VOLTS is low rate channel from Beckhoff voltage driver and JAC-PZT_DRV_OUT_DQ is front-end PZT feedback channel for fast feedback) and the temperature actuator (JAC-HEATER_POWER_SET). I will get the operator to switch it off when they leave so we don't cause any pressure spikes overnight.
I did another test today with the same gain but the set point at 25.1 degrees C (the temperature of the thermistor 1 when I switched it on). It still overshot so we might want to test with a lower gain but it stopped the JAC from unlocking due to the PZT running out of range.
Attached is the trends from today (vertical cursor when i switched on the controller, horizontal showing the setpoint on the thermistor).
Summary: let's test tomorrow with a smaller gain.
