Attached are two examples where it seems that ALS losses lock after the ESD linearization hits its saturating limit, there are several more examples like this.
With the linearization on, we measured the transfer function from drivealign L out to LL master out to be -2.3. Taking into account the gain of 0.25 in the eul2esd matrix, we would need to add a gain of -9.2 in the drivealign matrix to try locking ALS without the linearization.
I've added in lscparams use_ESD_linearization, which is set to True right now to keep things the same as they currently are. I've added an if statement for this in the ALS_DIFF guardian that will set the ETMX_L3_DRIVEALIGN gain to -9.2 if it is set to False.
The linearization used to be turned on in ISC_LOCK's PREP_FOR_LOCKING state, but TJ commented several things out of this state that were redundant with things that SDF would take care of when safe.snaps get reverted. Since we want to use a flag to determine how this is set, I've put it back into PREP_FOR_LOCKING that checks the flag in lscparams.