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Arecibo Telescope Servo Drive System

Arecibo Telescope Servo Drive System. Ideas For Computer Upgrade. (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

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Arecibo Telescope Servo Drive System

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  1. Arecibo Telescope Servo Drive System Ideas For Computer Upgrade

  2. (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! 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 Computer Upgrade Concept I

  3. 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 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 Computer Upgrade Concept II

  4. 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 Interface to host computer remains on Ethernet protocol … could be kept … or extended/modified according to present experience … or completely changed Computer Upgrade Concept III

  5. 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 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 Possibilities for Servo Computer

  6. Vertex Antennentechnik’s standard controller for high accuracy antennas and telescopes since 2001 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 Several more installations in progress Vertex Antenna Control Unit 8100

  7. ALMA Prototype at VLA site, New Mexico

  8. ESA 35m Deep Space Antenna, Australia

  9. 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 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 Vertex Antenna Control Unit 8100

  10. Vertex Antenna Control Unit 8100 6HU-Version of ACU 8100 4HU-Versionof ACU 8100

  11. New Antenna Control Unit 8100 (6 HU)

  12. Sample Local User Interface

  13. Limited scope of upgrade computer replacement only “budget-friendly” solution Re-Use of components drive cabinet, PLC and servo amplifiers encoders motors 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 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.) 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 Advantages of Suggested Approach

  14. 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…) Adaptation to new host computer(s) Extended operating modes Drive cabinet or servo amplifiers only Motors ? Possibilities for Future Upgrades

  15. Fully Digital Drive System • Position and velocity loops closed in servo computer • Servo computer provides torque command to each motor via local bus • In low level control the servo amplifiers receive analog commands • Configuration of servo amplifiers is controlled by PLC via digital inputs to amplifiers • Existing drive motors could be kept • Servo amplifiers (or entire drive cabinet) needs to be replaced • 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

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