We've had 3 SRM trips in the last week during the LOCK_SRY inital alignment state in the ALIGN_IFO node. I've made two changes to help with this:
- During locking of this state, we use AS_C for our triggers, but AS_A as our error signal for SRCL. So if OM1 or OM2 are misaligned, then we could be trying to move off of a bad signal. We have the AS_Centering series of states that will center AS_A using OM1 and OM2. I've added this in the path for automated inital alignment after SR2 alignment and before SRY locking. In theory this should help, but when trying to test it out today by heavily misaligning OM2, I wasn't able to get it catch on a wrong mode. Even though I couldn't reproduce it this way, this state is fast enough that I'll leave it in for now to see how it works. If anyone is running a manual initial alignment, they can choose to do this step or not.
- The other reason it was locking on the wrong mode is that the triggering thresholds were maybe set too low. Back in mid April I moved the triggering of this state from POP_A to AS_C (alog77113), and back then I just trended and made a good guess of the threshold values. I've bumped them up a bit to help avoid catching on the wrong mode and we'll see if this works over the next week or so.