From Eq. (12), we can know that |Fh(jx)| is inverse proportion
to x2. It suggests that compound pendulum system
has strong suppression to ultra-high frequency
ground tilt vibration. The smaller gh is, the more significant
the suppression is. The dependence of gh on the geometric
parameters l1, w2 and w3 can be obtained by substituting
B, D and E into Eq. (12).
Considering ultra-low frequency horizontal vibration,
namely x 1, Eq. (7) can be expressed as