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AdV-COM (AdV commissioning (1st part) )
ruggi - 14:42 Tuesday 24 March 2020 (48793) Print this report
PR marionette reallocation: driving balancing and engagement test

This morning the longitudinal driving of PR marionette has been balanced, then the noise injection has been repeated.

Fig 1, 2, 3: PR marionette angular motion transmitted by the longitudinal noise, before and after the balancing.

An attempt to engage the reallocation has been performed at low noise 1, at the first relock after the maintenance (fig 1). The ITF survived for 20 seconds, then an oscillation at 12 Hz growed. It could be the roll resonance of the payload (to be checked). Moreover, the behaviour at 0.75 Hz was not good: this should be a problem of stability at the crossing frequency.

The blending filters have to be improved, and some commissioning time is needed in order to test accurately the performance.

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ruggi - 12:19 Wednesday 25 March 2020 (48803) Print this report

Profiting of an unlock, the blending filters of PR MAR reallocation have been updated, and a test has been performed in the final minutes of the lock acquisition. In fig 1 we can see that the reallocation has been active for 200 s, giving the expected result: most of the low frequency correction has been moved to the marionette, which has a factor 2.7 more actuation gain. In this configuration, the saturation would be very far even in the worst weather conditions.

The impact on longitudinal accuracy is null (maybe a small improvement - fig 2).

Still a small refinement of TY balancing is needed, while TX looks fine (fig 3, fig 4). The new coefficient has been determined from the data, and it will be tested the next time.

There is still an impact on TZ (fig 5), but that d.o.f. is not so relevant for ITF stability. However a further refinement can be studied.

The EQ MODE configuration can be updated, including PR marionette reallocation: it is just missing a G name in the DSP and a line of code in metatron. For the future, it could be a good idea using the marionette in the standard mode.

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