Virgo Logbook

in the afternoon, after work on the bench, I tried to move the bench into the correct position with the microsprings. vertically the bench was pretty well aligned but horizontally not; ty was off by about 2.2 mrad. I could not zero Ty, z, and x simultaneously because I needed the microspring for horizontal 2 to go more backward. At software position 0, it will automatically move to the other side. The best I can do is either have Ty and x correct, but then z offset is around 0 instead of the required -165 micrometer, or get z correct but then Ty is 300 microrad off (negative). It took a long time to find a position in which the loop did close; typically it trips when going over 10 V or so so it tripped while the pid loop was still ramping, on actuator 2. I found a setting that the loop just barely closes.

We need to manually rebalance the EIB horizontally. I hope I can do that from remote, with local help, but I will discuss this later. It involves either manually rotating the microspring for horizontal 2 (if it is not at the end switch) or moving cables around so that the torque in Ty from the cables is changed.