Hi @siddons this looks really nice! I think homing the stage to 12 microns is definitely sufficient for most of the things you’d want it for - ensuring you’re roughly in the centre of the travel range, or figuring out an automatic compensation for the non-planar motion of the XY stage. This ticks a lot of the boxes for me, but one feature I’d be keen to see is knowing, without having to search, which direction you need to move in to find “home”. Is that something that’s possible with a Hall effect sensor? So far I’d assumed it would only work with an optical sensor (using a flag that blocks the beam when you’re below home, and treating the dark-bright transition as the home position).
There was a previous implementation with microswitches in the foot, but we hit an annoying problem, which was that either we needed to put it high enough that it limited the travel, or it became too slow to reach the bottom of the travel and “home” the system. I wonder if this would be a nice replacement for that - because you could have the “home” position close to one end of the travel (which means you usually know which way to move to hit it) but without introducing a mechanical limit.
I think for what I’d like to use endstops for, knowing which direction to move in is fairly important - but I’d be keen to hear from others what kind of solution would work best.