fabrice.matichard@LIGO.ORG - posted 17:52, Wednesday 21 July 2010 - last comment - 09:52, Thursday 22 July 2010(93)
HAM-ISI Unit 1, Lower zero moment point
The attached document shows the transfer functions used to compute the LZMP. The number we have are good: 0.24 mm and 0.30 mm in the X and Y directions respectively. However, we need a better coherence on the cross couplings in order to confirm these numbers. We are doing another measurement with much more averages (a 6 hours drive in each X direction).
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We have redone a low frequency measurement (0.01 hz to 0.1 Hz) with much more averages (222) in order to estimate with more accuracy the lower zero moment point offset (distance between the actuators and zero moment point of the rods). The data is stored in: 100721_LZMP_0p01to0p1Hz_M2M_test2_tfretrieve.mat The script used to take data is : TFcollect_100721_LZMP_0p01to0p1Hz_30avg.m This script does contain 220 averages contrary to what his name says. The result are presented on the plot attached. The offset estimation is lower than it was: Last measurement gives: X offset = 0.24 mm Y offset = 0.30 mm versus X offset = 0.14 mm Y offset = 0.16 mm as presented in yesterday entree base on a measurement using only 30 averages. The numbers we get are very good, and maybe surprisingly low (that's less than .01" offset). However, they are consistently low so that we can conclude that we are good.
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