[Tanaka, Ushiba, Komori]

Today, we tried a hierarchical control scheme for the yaw modes.
We measured the transfer function from the input of DHARD yaw to each TM oplev signal with the newly designed filter, as shown in the figure.
Assuming that the optical gain is flat, this is regarded as the estimated openloop transfer function.

We designed this filter to achieve a similar response for each suspension, in particular by inserting additional gains in the TM lock filters to match the high-frequency response.
The crossover frequency between the MN and TM is approximately 0.8 Hz, and the overall unity gain frequency is 2 Hz.

We found significant coupling from the pitch mode into DSOFT Y.
Therefore, we will apply this new filter after further decoupling of the pitch and yaw degrees of freedom.