Chapter 5 Robust Performance Tailoring with Tuning - SSL - MIT

25 cm
Y
Z
120
(a) Configuration
45
X
X
Variance [N 2 ]
PSD [N 2 /Hz]
0.04
0.02
10 −2
10 −4
10 −6
10 −8
0
10 −10
10 0
RWA DIST Fx[N]
RWA DIST FY[N]
RWA DIST Fz[N]
RWA DIST Tx[Nm]
RWA DIST Ty[Nm]
RWA DIST Tz[Nm]
10 1
Frequency [Hz]
(b) Power Spectral Densities
Figure 6-3: RWA disturbance model.
series between the RWA disturbances and the plant as shown in Figure 6-1. The
isolator transfer functions are:
Giso =
(2πfiso) 2
s 2 +2ζiso(2πfiso)s +(2πfiso) 2
10 2
(6.3)
where Giso is the transfer function from the input to the isolated disturbance, fiso is
the corner frequency of the isolator (Hz), and ζiso is the isolator damping ratio. The
damping ratio for both isolators is assumed to be 0.1 and the frequencies of the first
and second stages are set to 3 Hz and 8 Hz, respectively. The transfer functions for
both stages are shown in Figure 6-4.
6.1.3 Plant
The plant is a finite element model of a baseline design of the TPF structurally-
connected interferometer concept consisting of four collecting apertures, a supporting
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