Yesterday, it was mentionned in LHO aLOG 4858 that transfer functions measured on BSC1 were different from what we expected. This morning, I ran some simulations to evaluate if the extra modes seen in the [5-8]Hz frequency band would create some difficulties in the control design.
For the test, I used the BSC6 damping and isolation filters.
The 12 main transfer functions once the ISI is damped:
https://svn.ligo.caltech.edu/svn/seismic/BSC-ISI/H1/ITMY/Data/Figures/Transfer_Functions/Simulations/Damped/
The 12 main SISO TF used for the control design (between every steps, the MIMO response is used) are given below:
https://svn.ligo.caltech.edu/svn/seismic/BSC-ISI/H1/ITMY/Data/Figures/Transfer_Functions/Simulations/Isolated/