MSC recent activities Commissioning Cascina 2 Apr 2007
EM-MSC Recent/present Quite state recovery (duty cycle) Disturbance Re-jection (duty cycle, sensitivity) > xDamp, cleaner coarse signals to improve control accuracy: meas and offline OK, to be fully implemented (1 standalone shift) > saturation at the WE site (gain tuning): OK > Tall towers, GIPC (global IP control): tested under various conditions, in line. Ready further improvement for anti- seism sensor blending for NI,WI. > Short tower optimization: off-line work to prepare the optimization works OK, some tests done, to be completed (2 shifts, standalone+ITF check) Noise budget (sensitivity) ===>>> Hierarchical control: 1 st step: improvement of NE,WE actual Ma/Mi blending 2 nd step: BS marionette reallocation (today/tomorrow).
EM-MSC GIPC (Global Inverted Pendulum Control) benefits: wind disturbance rejection, lock acquisition, duty-cycle. Once the ITF is locked, the mirror position, provided by the Global Control, can be used instead of LVDTs, referred to the ground. Features: - automatic engagement (soft!) - anti-wind blending in NE-WE-BS-PR - anti- seism in NI-WI GC (reconstructed z) LVDT Splitted anti- seism /anti- seism
EM-MSC Example1: NE_GIPC,WE_GIPC only NE “follows” NIWE “follows” WI step9
EM-MSC Example 2: NE_ GIPC, WE_ GIPC only step9
EM-MSC Example 3: NE_ GIPC, WE_ GIPC, BS_ GIPC, PR_ GIPC step9
EM-MSC Example3: NE_GIPC,WE_GIPC only Thanks to GIPC benefit to Automatic Alignment step9 Short suspension (i.e.beam) improvement necessary ?
EM-MSC Example,environmental: central Bld, GIPC shock absorption
EM-MSC > synthesis: net improvement of recent activity Much more seism and similar peak at 130 mHz In this example: - red data (now) show up similar peak at 130 mHz but much larger seism. In spite of this: => the force reallocated to the marionette is smaller !
EM-MSC > noise budget: actuation noise & reallocation -Suitable resistors are used to reduce coil-drivers noise (ln/HP to accomplish sensitivity/locking) -a trade-off with DAC noise using emphasis/de-emphasis was found. Still some work: BS requires marionette reallocation. WE,NE have a seism peak that should be reduced by further force reallocation to the marionette. Too large correction directly on the mirror Low frequency component that can be moved upwards (marionette)
EM-MSC > conclusions Operation: Continuous attention on operation issues related to operation Strategy disturbance rejection: - A large effort was spent on ID sensing optimization and on “soft operation” - Tools to emulate crucial environmental situations have been developed - Marionette reallocation in 4 suspensions - GIPC in-line To be done before (possibly before the MegaRun): -further technical noise reduction (locking reallocation improvs being done) -improvement of short suspension performance (InjB,MC,OutB, possibly)