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Cavity Control Influence on Damping. - Case 1: All cavity control on Pendulum 2. *. Pendulum 1. Pendulum 2. * Top to top mass transfer function. longitudinal. u 1 ,2. u 2,2. u 1 ,3. u 2,3. What you would expect – the quad is just hanging free.
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Cavity Control Influence on Damping - Case 1: All cavity control on Pendulum 2 * Pendulum 1 Pendulum 2 * Top to top mass transfer function longitudinal u1,2 u2,2 u1,3 u2,3 • What you would expect – the quad is just hanging free. • Note: both pendulums are identical in this simulation. u1,4 u2,4 Control Law 0 1 G1200774
Cavity Control Influence on Damping - Case 2: All cavity control on Pendulum 1 Pendulum 1 Pendulum 2 * * Top to top mass transfer function longitudinal u1,2 u2,2 u1,3 u2,3 • The top mass of pendulum 1 behaves like the UIM, PUM, and test mass are clamped to gnd. • This happens when the ugfs of the UIM, PUM, and test mass loops are above the quad’s resonant frequencies. u1,4 u2,4 Control Law 1 0 G1200774
Cavity Control Influence on Damping - Case 3: Cavity control split evenly between both pendulums Pendulum 1 Pendulum 2 * * Top to top mass transfer function longitudinal u1,2 u2,2 u1,3 u2,3 • The top mass response is now an average of the previous two cases -> 5 resonances to damp. • Control up to the PUM, rather than the UIM, would yield 6 resonances. • aLIGO will likely behave like this. u1,4 u2,4 Control Law 0.5 0.5 G1200774