Vlad, Naoki

Yesterday I observed PI MODE24 ring up a large number of occasions. This was caused because the PI Guardian was falsely perceiving that the amplitude of PI was rising, inferred that the phase was "bad" and changed the phase to an actually bad phase.

In the time it took to finally find the "good" phase again, the amplitude rang up, and the saving grace was actually the hard-coded limit on the PLL outputs (which I am re-implementing to be soft-coded), which meant that while the PI phase was slewing from bad to terrible and back to good, the actuation was not exponentially increasing.
I have increased the RMS threshold for which the guardian will infer that the mode is "going up" from 3->4.

Another issue is that the first time this triggers for any mode, it reads out the RMS in the last 5 seconds and considers whether that is larger than the last time it makes that check. But the these "last times" had an initialisation value of 0: so it would always change the phase (to a now "bad" one).
The fix for this we think is to initialise these thresholds to the triggering thresholds for each of the modes being damped. This will at least prevent the guaranteed change on the first trigger.