Calypso AO Tertiary Setup Procedure

Prepared by:
Bruce Truax
388 Wedgewood Road
Southington, CT 06489
860-276-0450
fax 860-620-9026
btruax@home.com

Introduction

Coordinate System Setup

Closing the Loop and Tuning

Introduction

The purpose of this document is to describe the procedure for setting up and tuning the Calypso Adpative tertiary system.

This procedure is divided into two sections. The first section describes how to set the proper relation between the coordinate systems of the detector and the tertiary mirror. This portion of the procedure should only be needed during initial setup. Once the coordinate systems are properly oriented, they should remain correct unless the adaptive system is changed to the other rotator or if the adaptive trident detector system is removed and replaced in the wrong orientation.

The second section of the procedure describes how to tune the system. This procedure will be used every time we turn on the system until we have some experience and historical data at which time we will add an adaptive tuning system into the software.

Section 1 - Coordinate System Setup

Purpose

The detector for the tertiary is located on the HRCam and rotates relative to the telescope with the camera to maintain the image orientation relative to the sky. The detector monitors the motion of a guide star, which is placed on the pickoff mirror in the lower right quadrant of the image. As the telescope moves around the sky, the relative orientation of the detector coordinate system changes which respect to the actuators on the active tertiary. The digital servo software is provided with the relative angle between the coordinate system of the tertiary and the coordinate system of the detector by the TOI. This angle is called ROT_EL_ANGLE and is the difference between the angle of the NA1 rotator and the elevation axis plus an offset. The problem during initial setup is that we do not know the offset angle or the sign of this angle. There are 8 possible offset/sign combinations for this value as shown in the table below.

ROT - EL + 0

ROT - EL + 90

ROT - EL + 180

ROT - EL + 270

EL - ROT + 0

EL - ROT + 90

EL - ROT + 180

EL - ROT + 270

Table 1 - Angle Offset Combinations

Because of the orientation used during lab testing the offsets of 0 and 180 are most likely. There are 4 versions of the tertiary software entitled tertiary.exe, tert90.exe, tert180.exe and tert270.exe which are loaded on the tertiary controller. These correspond to the first 4 cases. To test the second 4 cases I recommend that the sign of the ROT - EL angle be changed in the TOI.

Setup

Connect and setup electronics
  1. Connect the round black connector on the Primary Mirror side of the HRCam body. This connector provides power to the avalanche photodiode detectors.
  2. Turn on the instrument power at the on the panels on the side of the telescope (the right hand panels when looking at the right side of the fork. WARNING: These two steps should only be done when the ambient light is at very low levels. High light levels can damage the detectors!
  3. The next step is to connect a PC to the Virtual System Console (VSC) port of the Ziatech computer used to control the tertiary servo. There are two serial ports on the tertiary controller. One is used for communications between the instrument PC and the controller (Connected to COM 5 on the auxiliary COM board in the PC) and the other is used for the VSC (sometimes, but not often, connected to COM1 on the instrument PC). The serial line for the VSC is probably only connected to the Ziatech with the other end left loose. Connect this other end with a null modem adapter to COM1 of the portable PC.
  4. Turn on the Instrument power on the main power control panel.
  5. When the Instrument PC is done booting, start the Instrument Controller software, there is an "Instrument" ICON on the desktop.
  6. Insert the Virtual System Console boot disk in the portable PC
  7. Boot the portable PC and the press <cntrl><alt><space> simultaneously. This will switch the screen so that it now becomes the console for the tertiary controller.
  8. Turn on the tertiary controller. When it completes the boot process there should be a message on the portable PC showing the drive mapping. And the prompt P> should appear. The P drive is the prom drive in the Ziatech. The A: drive on the portable is mapped to the Q: drive on the Ziatech and the C: drive on the portable is mapped to the R: drive on the Ziatech. You can copy files between the computers using standard DOS commands, just be aware that the connection is serial so a 100KB copy can take about one minute. If you need to edit a file you will have to copy the file from the Ziatech to the floppy disk in the portable and then take the disk to another computer (usually the instrument PC) where an editor is available. NOTE: you may think that you can run the VSC in a DOS window under Windows, while this may appear to work, you will notice some rather odd behavior due to the Windows multitasking system. \
  9. Edit the Tertiary.cfg file on the Ziatech so that the two analog diagnostic channels output the x and y position signals. Also make sure that the servo on flag is set to 0.
    10. diag out ch0 = 1       # 0=no ouput, 1=x position, 2=y position, 3=x error
diag out ch1 = 2       # 4=y error,  5=x pid_out,  6=y pid_out
  10. Connect the diagnostic channels of the Ziatech to Channels 1 and 2 on the oscilloscope and set the scope for x-y mode with both channels set to 5 V/div.
  11. Edit the TOI.CFG file on the SUN to turn on the connection to the instrument PC.
  12. Start the TOI and initialize the axes. Turn on the instrument rotator.
  13. Turn down the channel one and two gains and bias on the Burleigh HV power supply and urn on the power. Set the power supply display to Channel 1 and increase the bias to 50 volts. Repeat for channel 2.

    14. Testing

  14. Start the start the tertiary software by running one of the programs (tertiary.exe for 0 degree offset, tert90.exe for 90 degree offset, tert180.exe for 180 degree offset or tert270.exe for 270 degree offset). Note that the servo will not be running.
  15. Point the telescope at a star of 6th magnitude or dimmer. I recommend the binary companion to Polaris since the axes do not have to move much to track this star and so it should remain stationary even if there are servo and pointing model errors. Note: you might want to do a quick check of the seeing, If the seeing is worse than 1 arc second the star position will be so unstable that this procedure will be difficult.
  16. Move the telescope to position the selected star on the pickoff mirror.
  17. From the TOI turn on the adaptive system.
  18. The tertiary VSC display should show counts in the 100-1000 range for one, if not all of the detectors. Using the TOI offset adjustments, try centering the star on the pickoff mirror until there are counts on all three detectors.
  19. Once a good signal is obtained, the scope display should show a jittery spot. This is the position of the star.
  20. At this point one person needs to go up to the telescope and adjust the bias on the HVPS. Channel 1 is the x-axis and channel 2 is the y axis. Starting with Channel 1, slowly turn the bias potentiometer up and down. Note the direction of motion. If the spot moves in either the horizontal or vertical direction then the sign of the angle is probably correct. If the motion is at some other angle, then change the sign in the TOI and try again. NOTE: this may not be the case if the ROT_EL_ANGLE displayed on the tertiary screen is close to 0, 90, 180 or 270! In this case you should look at another star).
  21. Once the motion is oriented along one of the two primary axes you need to determine if the offset is correct. When adjusting the channel 1 bias, if the star motion is horizontal on the scope then you are close. Now note the value of the output voltage displayed on the VSC screen for the x axis. As the bias voltage goes positive, the correction voltage should go negative. If this is the case the offset angle is correct. If this is not the case, exit the tertiary software by pressing the escape key and try the tert180.exe file.
  22. If the motion of the star is along the y axis then switch to the tert90.exe file and see if the correction voltage goes negative when the bias goes positive. If so, you are done, if not try tert270.exe
  23. At this point the output voltage for the x axis should be the mirror image of the change in the bias voltage. The y axis should naturally follow. but we should check it just to make sure. Repeat the test with the channel 2 bias adjustment and watch the y axis output voltage. It should also be the opposite sense from the bias voltage change. If this is not the case then we have to change the sign of the y axis correction in the software. Contact Bruce Truax for this change.
  24. At this point it is worthwhile to make the same check on a couple of additional stars in the sky, although you may want to move on to closing the loop. If so, see the next section.
  25. Once you are confident that you have the correct orientation, rename the executable tertiary.exe

    26. Section 2 - Closing the Loop and Tuning

    Before you try closing the loop make sure that the setup procedure has been completed or you will be wasting your time. The purpose of this section is to describe how to turn on the system, acquire a star and then tune the servo for the current conditions. Please note that the first 13 steps are the same as above and are repeated here for clarity. Once we have some experience with the operation of the adaptive system, we plan to add all of these adjustments to the software so that the process is more automatic.

    Connect and setup electronics

  26. Connect the round black connector on the Primary Mirror side of the HRCam body. This connector provides power to the avalanche photodiode detectors.
  27. Turn on the instrument power at the on the panels on the side of the telescope (the right hand panels when looking at the right side of the fork. WARNING: These two steps should only be done when the ambient light is at very low levels. High light levels can damage the detectors!
  28. The next step is to connect a PC to the Virtual System Console (VSC) port of the Ziatech computer used to control the tertiary servo. There are two serial ports on the tertiary controller. One is used for communications between the instrument PC and the controller (Connected to COM 5 on the auxiliary COM board in the PC) and the other is used for the VSC (sometimes, but not often, connected to COM1 on the instrument PC). The serial line for the VSC is probably only connected to the Ziatech with the other end left loose. Connect this other end with a null modem adapter to COM1 of the portable PC.
  29. Turn on the Instrument power on the main power control panel.
  30. When the Instrument PC is done booting, start the Instrument Controller software, there is an "Instrument" ICON on the desktop.
  31. Insert the Virtual System Console boot disk in the portable PC
  32. Boot the portable PC and the press <cntrl><alt><space> simultaneously. This will switch the screen so that it now becomes the console for the tertiary controller.
  33. Turn on the tertiary controller. When it completes the boot process there should be a message on the portable PC showing the drive mapping. And the prompt P> should appear. The P drive is the prom drive in the Ziatech. The A: drive on the portable is mapped to the Q: drive on the Ziatech and the C: drive on the portable is mapped to the R: drive on the Ziatech. You can copy files between the computers using standard DOS commands, just be aware that the connection is serial so a 100KB copy can take about one minute. If you need to edit a file you will have to copy the file from the Ziatech to the floppy disk in the portable and then take the disk to another computer (usually the instrument PC) where an editor is available. NOTE: you may think that you can run the VSC in a DOS window under Windows, while this may appear to work, you will notice some rather odd behavior due to the Windows multitasking system. \
  34. Edit the Tertiary.cfg file on the Ziatech so that the two analog diagnostic channels output the x and y position signals. Also make sure that the servo on flag is set to 0.
    diag out ch0 = 1 # 0=no ouput, 1=x position, 2=y position, 3=x error
    diag out ch1 = 2 # 4=y error, 5=x pid_out, 6=y pid_out
  35. Connect the diagnostic channels of the Ziatech to Channels 1 and 2 on the oscilloscope and set the scope for x-y mode with both channels set to 5 V/div.
  36. Edit the TOI.CFG file on the SUN to turn on the connection to the instrument PC.
  37. Start the TOI and initialize the axes. Turn on the instrument rotator.
  38. Turn down the channel one and two gains and bias on the Burleigh HV power supply and urn on the power. Set the power supply display to Channel 1 and increase the bias to 50 volts. Repeat for channel 2.

    39.  Tuning

  39. Start the start the tertiary software by running tertiary.exe from the VSC.
  40. Point the telescope at the object you want to observe. Out of the field, chose a star with a brightness less than 6th and greater than 13th magnitude (you can push the limits if you want but pay attention to the counts on the detectors)
  41. Move the telescope to position the selected star on the pickoff mirror.
  42. From the TOI turn on the adaptive system.
  43. The tertiary VSC display should show counts in the 10-1500 range for one, if not all of the detectors. Using the TOI offset adjustments, try centering the star on the pickoff mirror until there are counts on all three detectors.
  44. Once a good signal is obtained, the scope display should show a jittery spot. This is the position of the star.
  45. At this point one person needs to go up to the telescope and adjust the gain on the HVPS. Channel 1 is the x-axis and channel 2 is the y axis. Starting with Channel 1, slowly turn the gain potentiometer up. The person watching the oscilloscope should see the star lock in to 0 offset in the x direction. The person up at the telescope should listen carefully, if the gain goes to high, the tertiary will go into oscillation and it will start to buzz. If this happens, then turn down the gain.
  46. Once the x-axis servo is locked, turn up the gain on the y-axis until it also locks.
  47. On the VSC console, make sure that the output voltage stays between +/- 9 volts. If it approaches the limit then the star should be recentered. Before recentering it is recommended that the tertiary servo be turned off. Once the star is centered it can be turned back on and it should lock automatically.
  48. Try and take an image!