I've played with the ISI-ETMX to reduce the excess motion seen in pitch and longitudinal at the suspension point by the ISC group (see Sheila's log).

I've tried different configurations (see plot attached). In all these configurations, HEPI is controlled in position.

I was able to get some improvement, especially in longitudinal. The key was to blend with the T240s to avoid the extra sensor noise coming from the L4Cs at low frequency. We could blend lower, using Ryan's blends (blend frequency at 40mHz). I've been having some troubles with them, but I'll try that again tomorrow.

Even if HEPI-ITMX is not controlled, I've tried the same thing and ended up with the same kind of results. I'll do a more complete post about that later.