SIESTA for Virgo locking experience

1. SIESTA for Virgo locking experience L. Barsotti University of Pisa – INFN Pisa on behalf of the Virgo Locking Group Simulation Workshop Cascina, March 16th 2004

2. Outlines • Commissioning of the first 3–km cavity • Recombined mode • Full Virgo • Other activities in parallel

3. North Cavity Optical Scheme PR, WI, WE mirrors misaligned WE WI T=8% NI NE 6 W BS B7 T=12% T=50 ppm PR B5 B1p

4. Commissioning of the North Cavity • Feedback characterization: • optical gain • open loop transfer function • Analysis of the lock algorithm efficiency • linearized error signal • no linearized error signal • Comparison with real data (C1, C2 runs) • Real suspensions, real actuators, real photodiodes, computational delays included in the simulation

5. PR NI NE BS B7 B1p T=8% |Gain| Hz frequency North Cavity Control Scheme Lock Acquisition • Linearized error signal:

6. Optical Gain: • Measured • Simulated

7. zCorr zErr M noise G Transfer Function Open Loop Gain simulated measured Phase

8. Lock Algorithm Efficiency C1 run data : Several lock events collected locking and delocking the cavity linearized error signal • Lock almost always acquired at the first trial

9. Constraints on the velocity according to the theory: 8mm/s: maximum velocity for the lock acquisition success Failed locking attempt v ~ 12.5mm/s • Gain due to the linearization: a ~ 10 Lock Algorithm Efficiency

10. With velocity lower than 10 mm/s lock at the first attempt • With velocity higher than 10 mm/s lock at the second attempt Lock Algorithm Efficiency • Sweep at 12 mm/s : Lock event Lock failed

11. Failed locking attempts Lock Algorithm Efficiency not linearized error signal C1 data Simulation

12. Algorithms running in the global control Photodiodes signals Control signals SIESTA link to real time control SIESTA

13. Algorithms running in the global control Photodiodes signals Control signals SIESTA link to real time control VIRGO

14. B8 WE WI PR NI NE BS B7 T=8% B5 B2 B1 Recombined Optical Scheme PR mirror misaligned

15. Recombined mode • 2 Steps locking strategy: • sensing matrix • procedure to find experimentally the algorithm parameters from simple optical systems • 3 Steps locking strategy • sensitivity curve • comparison with real data • Linear locking

16. B8 • west cavity and michelson controlled at the sime time • north cavity controlled with B5 B7 B2 B5 B1 Reconbined 2 Steps Control Scheme

17. Michelson and West cavity controlled with the symmetric (B2_quad) and the antysimmetric signal (B1p_quad) • Sensing matrix • Theorical optical matrix: • Optical matrix measured by Siesta:

18. Locking simulation – North cavity Locking

19. Locking simulation – Mich & West Powers Lengths Triggers Corrections

20. B8_demod West arm North arm B7_demod B5 B2 B1p_demod Recombined 3Steps Control Scheme • switch from B1p to B1 after the lock acquisition

21. Lock acquisition -simulation “Simple” simulation: real suspensions and actuators

22. Lock acquisition -simulation

23. First lock acquisition 27th February Locking event At 3.25 am

24. Sensitivity - simulation Improvement: real photodiodes(electronic noise, shot noise)

25. Sensitivity Simulated Measured

26. d2_quad d2_phase d1p_quad MICH CARM DARM Switch to the linear locking state • Optical matrix: • Inverse optical matrix:

27. West arm North arm B2_quad B1p_quad ⊗ B2_phase Linear Locking Control Scheme

28. Linear lock of the recombined Simulation

29. Full Virgo Optical Scheme B8 WE WI PR NI NE BS B7 B5 B2 B1

30. Lock acquisition of full Virgo • Multi–states approach (LIGO scheme) • Dynamical inversion of the optical matrix

31. Lock acquisition of full Virgo

32. Something more… • Modal simulation • Longitudinal local control optimization • Spikes removal

33. 0.113 Modal simulation • High order modes (n + m ≤ 5 ) • compromise with the computational time 1 sec @ 20 kHz ⇒ 45 sec • misalignment of 2 mrad in qy of the curve mirror • Check with other codes in progress

34. Something more… • Modal simulation • Longitudinal local control optimization • Spikes removal

35. Optimization of the z damping loop – I • measured zCorr zMirror mm • Damping time ~ 10 sec t~10 sec Open loop transfer function Unity gain @ 0.65 Hz Hz

36. Optimization of the z damping loop – II • simulated zCorr zMirror V m t~2 sec Open loop transfer function Critical damping @ 1.45 Hz Hz

37. zCorr zMirror V mm t~ 2 sec Guadagno open loop Hz Optimization of the z damping loop – III • measured after the optimization Critical damping @ 1.45 Hz

38. Something more… • Modal simulation • Longitudinal local control optimization • Spikes removal

39. Spikes removal

40. Spikes removal Rearrange the algo: Error signal  derivative  window  integrator window

41. marionetta Transfer function betweeen force on steering filter and z movement of the mirror Control from the marionetta z reference mass mirror Control from the reference mass Other activity:Hierarchical control • preliminary results wwwcascina.virgo.infn.it/collmeetings/presentations/Mar2004/Fiori_11Mar04_MarioLockSim.ppt

42. Conclusions • Siesta: fundamental tool for locking studies • Link to the real time control system • Work in parallel with other groups to improve the simulation (suspensions, alignment) • Noise analysis