1. Arecibo Telescope Servo & Drive System - 1 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Arecibo Telescope Servo Drive System Ideas For Computer Upgrade

2. Arecibo Telescope Servo & Drive System - 2 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH

3. Arecibo Telescope Servo & Drive System - 3 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Computer Upgrade Concept I u (Existing) PLC  hardware can be re-used to a large extent  hardware (except CP581) is still will be available for many years  CP581 will be removed  PLC function will be limited to safety functions and low level operation  interface to servo computer via serial interface (new card) – not time critical! u New Servo Computer  Local User Interface (replaces existing LCU)  tasks: encoder readout operating mode control M&C Interface to host position loops  output to DCS: analog velocity commands

4. Arecibo Telescope Servo & Drive System - 4 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Computer Upgrade Concept II u Drive Control  motors to be re-used  servo amplifiers to be re-used  complete DCS to be re-used  additional setpoint from servo computer: DCS boards can handle additional setpoint analog signal must be wired from backplane SUB-D connector to board connector PLC software must control selection relay u Encoders  presently read by PLC  new (possibility 1) only computer reads encoders position dependent PLC interlocks cannot be kept  or (possibility 2) install SSI doublers both computer and PLC read encoders position dependent PLC interlocks can be kept

5. Arecibo Telescope Servo & Drive System - 5 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Computer Upgrade Concept III u OCU in main control room  also to be replaced  new OCU could be … a desktop PC with keyboard and mouse, running on Windows a rack mounted touch screen panel PC a notebook PC  logs into servo computer via Ethernet  existing serial link no more required u Interface to host computer  remains on Ethernet  protocol … could be kept … or extended/modified according to present experience … or completely changed

6. Arecibo Telescope Servo & Drive System - 6 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH

7. Arecibo Telescope Servo & Drive System - 7 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Possibilities for Servo Computer u PC in-expensive easy replacement / upgrade  interface boards to encoders etc. to be found  existing application software to be adapted to hardware and software platform  reliability for operation unknown  becomes obsolete very fast  spare part availability u Industrial Servo Computer proven reliability all interface hardware available interface modules comply to more stringent specifications spare part availability application software available to a large extent prepared for future upgrades  more expensive than PC  software and drivers written for a particular hardware configuration

8. Arecibo Telescope Servo & Drive System - 8 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Vertex Antenna Control Unit 8100 u Vertex Antennentechnik’s standard controller for high accuracy antennas and telescopes since 2001 u Installed at  ESA 35m Deep Space Antenna (servo accuracy ~2 mdeg) Australia: in operation Spain: presently being built  various (fast) ESA 15m antennas (~20 mdeg)  ALMA Radio Telescope (~0.15 mdeg)  APEX Radio Telescope (~0.15 mdeg)  AMIBA Hexapod Telescope (~3 mdeg)  CNR 32m Radio Telescopes at Noto and Medicina (~1 mdeg)  Eumetsat Polar Station, Svalbard (~20 mdeg)  various other stations u Several more installations in progress

9. Arecibo Telescope Servo & Drive System - 9 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH

10. Arecibo Telescope Servo & Drive System - 10 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH

11. Arecibo Telescope Servo & Drive System - 11 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Vertex Antenna Control Unit 8100 u Concept:  CompactPCI bus  VxWorks 5.5 RTOS  P III 1.3 GHz CPU with 2 Ethernet interfaces  10.4” Color Touch Screen as local user interface (separate PC running on Embedded XP)  multiple user interfaces feasible  several types of interfaces to host / encoders / drive cabinet available u Tasks:  drive control fully digital Az/El drive control or position loop only with analog velocity command output  position readout from encoders  operating modes  interlocks on software level  local control of all functions  pointing error correction (option)  communication to interlock system PLC  Interfaces to host computer

12. Arecibo Telescope Servo & Drive System - 12 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH

13. Arecibo Telescope Servo & Drive System - 13 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Vertex Antenna Control Unit 8100 6HU-Version of ACU 8100 4HU-Version of ACU 8100

14. Arecibo Telescope Servo & Drive System - 14 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH New Antenna Control Unit 8100 (6 HU)

15. Arecibo Telescope Servo & Drive System - 15 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Sample Local User Interface

16. Arecibo Telescope Servo & Drive System - 16 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Advantages of Suggested Approach u Limited scope of upgrade  computer replacement only  “budget-friendly” solution u Re-Use of components  drive cabinet, PLC and servo amplifiers  encoders  motors u Low risk  the working interlock system and low level control will be re-used  return to existing system can easily be achieved  use of well proven components  limited software effort u Limited software effort  PLC software can be re-used to large extent various functions not used any more  Servo computer software functionality already existing only adaptations required for Arecibo (interfaces, specific interlocks etc.) u Limited telescope downtime  Estimated total downtime approx. 2-3 weeks  With a little more effort, it would even be possible to return to operation every night

17. Arecibo Telescope Servo & Drive System - 17 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Possibilities for Future Upgrades u Fully Digital Drive System very flexible control loop structure improved performance much easier to be tuned than analog DCS insensitive to EMI etc. less components …less failures  … more software  measurement of commands to servo amplifiers is difficult and requires analyzers or test outputs in the computer (even more software…) u Adaptation to new host computer(s) u Extended operating modes u Drive cabinet or servo amplifiers only u Motors ?

18. Arecibo Telescope Servo & Drive System - 18 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH

19. Arecibo Telescope Servo & Drive System - 19 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH Fully Digital Drive System u Position and velocity loops closed in servo computer u Servo computer provides torque command to each motor via local bus u In low level control the servo amplifiers receive analog commands u Configuration of servo amplifiers is controlled by PLC via digital inputs to amplifiers u Existing drive motors could be kept u Servo amplifiers (or entire drive cabinet) needs to be replaced u Analog DCS could  … be kept for low level control  … be removed, leading to a much simpler but “less comfortable” drive concept in low level control

20. Arecibo Telescope Servo & Drive System - 20 - Technical Meeting May 2004 VERTEX ANTENNENTECHNIK GmbH