LHC Collimators Motor Drive control & Position Readout and survey

1. LHC Collimators Motor Drive control &Position Readout and survey AB/ATB/LPE 8/11/2006

2. OUTLINE • Collimators’ requirements • Motor movements • Position Readout and Survey • PXI and Alternatives • Motor Drive Control • Position Readout • Conclusions

3. The Collimator Control Architecture

4. OUTLINE • Collimators’ requirements • Motor movements • Position Readout and Survey • PXI and Alternatives • Motor Drive Control • Position Readout • Conclusions

5. Collimators’ requirements • Motor Drive Control • The jaws of the collimators are moved by stepping motors, to ensure repeatability of the movement within the uncertainty defined by the mechanical play. • Mechanical play has been measured to be below 30 µm on all the collimators received so far. • Cumulated error due to mech. play to be compensated by either re-alignment to position sensor reading or by step-counter reset on home position (mechanical end-stop)

6. Collimators’ requirements • Motor Drive Control • Each jaw is moved by two motors. • The two jaw supporting shafts are rigidly connected to the jaw. • Skew movements are executed by (slightly) deforming the structure of the jaw. • It is recommendable (for a number of reasons) to synchronize as much as possible the two axes. • Qualitatively we verified a very different vibration regime from no synchronisation (> msec: lot of noise) to good synchronisation (~0.1 msec: no noise at all) • 1st requirement: synchronisation of two motors of the same jaw better than 1 msec

7. Collimators’ requirements • Motor Drive Control • Jaws’ positions need to be controlled at 20 µm level (if possible) • At 2 mm/sec, 20 µm  10 msec. • Synchronisation across the different collimators is implemented by CSS, that sends triggers to each MDC (no CERN timing card required in low-level). • Local or external accurate clock is required to keep the jaws synchronised in between two triggers.

8. Provided by CSS and daisy chained on different LLFE (jitter < 1 µsec) Determined by platform chosen. Trigger delay Determined by local clock Stop jitter Start jitter Profile duration Collimators’ requirements • Motor Drive Control Trigger delay: <1ms Start jitter: <1ms Stop jitter: <10ms Profile duration: ~15÷30 minutes

9. Collimators’ requirements • Motor Drive Control: additional feature • Movement during phases of acceleration will be driven through functions sent by the CSS • The MDC will have to be able to execute profiles of movement with a duration up to 30 minutes (max delay between two successive triggers sent to CSS). • The MDC shall be able to download a new profile from the CSS while still executing another profile

10. Collimators’ requirements

11. Collimators’ requirements • Motor Drive Control : Summary • Synchronisation within same jaw: <1 msec • Synchronisation from jaw to jaw, all along the movement function: < 10 msec • The MDC shall be able to download a new profile from the CSS while still executing another profile

12. OUTLINE • Collimators’ requirements • Motor movements • Position Readout and Survey • PXI and Alternatives • Motor Drive Control • Position Readout • Conclusions

13. Collimators’ requirements • Position Readout and Survey • It is required to read and transmit the position of each position sensor (LVDT) at a rate of 50 Hz (minimum) or 100 Hz (wish). • The function of position sensors is SAFETY. The PRS will raise an interlock in case the collimator position goes too far for example during automatic Beam based alignment. • Position to be compared with Limit Function managed through MCS • That gives 10 ms to read the signals, clean them from noise, calculate the position, compare it with the limit function and raise the interlock.

14. Collimators’ requirements • Acquisition speed: • At 250 kS/sec (16 bits), and 1000 point acquired, reading 1 channel takes 4 msec. • Each PRS has a minimum of 28 channels to read (for LVDTs). • Simultaneous sampling (no MUX) is therefore mandatory to keep 100 Hz (or even 50)!!!

15. Collimators’ requirements • Position Readout and Survey • Summary • ~250 kS/sec (16 bits) • Simultaneous sampling

16. OUTLINE • Collimators’ requirements • Motor movements • Position Readout and Survey • PXI and Alternatives • Motor Drive Control • Position Readout • Conclusions

17. PXI and Alternatives • PXI • OPEN Industrial standard governed by a consortium of ~70 companies, lead by National Instruments but including bigs like Keithley, Rohde & Schwarz, Agilent. • Countless applications in Industry, Scientific institutions (NASA, ESA, ESO…), Military (control of helicopters), and for control of Nuclear plants. • Used at CERN for Magnet testing (SM18), no use (to my knowledge) for accelerator controls

18. PXI and Alternatives • PXI

19. PXI and Alternatives • PXI • Triggering with 1 ns skew • Internal clock (10 MHz) stability down to 45 ppb • High data rate: 132 MB/s, we need less than 1 • High reliability backplane connectors (Compact PCI). • Compatibility with new PCI Express standard (giving up to 6 GB/s data rate and high frequency clocks > 20 MHz).

20. PXI and Alternatives • PXI : Generic configuration • 2 x 8 slot chassis for 1 (few cases), 2 (90% of the installation) or 3 collimators (point 3). • 3 collimators x chassis is going to be very challenging because of the reduced space in the available racks. Even if investment cost would be lower, maintenance would be a nightmare. • PXI n. 1 : Motor Drive Controls: • Motor control, resolvers, end stroke switches, interlocks, trigger • PXI n. 2: Position Readout and Survey • LVDTs, Interlocks, trigger.

21. PXI and Alternatives • PXI : Motor Drive control • Based on FPGA. • 1 FPGA x collimator (Motor and resolver). Very practical to port the configuration among 1, 2 or 3 collimators per chassis. • FPGA provides speed (reacts and executes commands within 80 µsec) and reliability. Should we need further functionalities in the future we just reprogram it.

22. PXI and Alternatives • PXI : Position readout and Survey • Generation of sinusoids at different frequency. • Probably based on FPGA (if not, standard DAQ, which absorbs more CPU resources) • LVDT reading • ADC, algorithm and comparison to limit function in the CPU.

23. PXI and Alternatives • PXI : CPU • Based on 2 GHz INTEL Core DUO T2500 Dual core processor • 2 Gbytes RAM • 1 Gbyte Solid State disk (instead of hard disk) • Possibility of remote software reboot. • OS: Pharlap • Language: Labview RT

24. PXI and Alternatives

25. PXI and Alternatives • MTBF

26. PXI and Alternatives • PXI : FESA • No solution available to run it on Pharlap. • With the help of Clara Gaspar (PH) and the support of National Instruments we succeeded to compile DIM under Pharlap and LynxOs. • DIM Server runs on PXI, Client on LynxOs. • IT/CO supports DIM for the experiments. • National Instruments agreed to support DIM under Pharlap (or any future OS) for 20 years. • NI solution (“shared variable”) to publish data under Linux to be available in March 2007. If fast enough we can get rid of DIM. FESA Gateway (and CSS) will have to run under Linux.

27. PXI MDC or PRS (Labview RT) DIM Server PXI and Alternatives • PXI : FESA • Latency: ~6 ms PC Gateway: Linux or LynxOS CSS DIM Client FESA Server

28. PXI MDC or PRS (Labview RT) Shared Variable Server PXI and Alternatives • PXI : FESA • Latency : ? (to be measured in March) PC Gateway: Linux CSS Shared Variable client FESA Server

29. PC Gateway: Linux or LynxOs CSS FESA Client PXI MDC or PRS (Labview RT) FESA Server PXI and Alternatives • VME : FESA • Latency : ~ 6 ms

30. PXI and Alternatives • VME: • Motor controller: • Delta-τau (USA): up to 16 axes • Analog Input: • ICS (USA): 32 channels, 24 bits at 100kS/S simultaneous sampling. • Proof of principle done (it works). • It’s more expensive, less flexible (we cannot re-program the motor controller if needed) • Slower ( no 100 Hz). • Implies manpower from CO (Drivers).

31. PXI and Alternatives

32. PXI and Alternatives

33. PXI and Alternatives • Eur/CHF: 1.56  Total = 72’805 CHF x 2 coll. • Phase 1 = 54 systems: 3.93 MCHF • Problem 14U !!!!

34. PXI and Alternatives • PXI : • For 54 systems (2 PXI x 2 Collimators) cost is ~2.5 MCHF (~41000 CHF x 2 coll.) • Cost is therefore 63% of VME • This price includes also cables, Patch panels and optocoupled fan-outs (not included in VME slides)

35. Collimators’ requirements • PXI : Drawbacks

36. PXI and Alternatives

37. Conclusions • Specificity of the LL control system is a direct consequence of tight specifications (high accuracy, high speed, synchronisation). • PXI flexible, cheap and reliable • No known experience in accelerator operation. • Known problems identified and solved. SPS test confirmed robustness of the system • VME alternative solution exist, but 40% more expensive.