AutoTune
updated 2/20/98 What is AutoTune?
AutoTune is the electronic replacement of the manual tuning process for the RefleX System . The manual technique involved adjusting 4
potentiometers for each axis while monitoring an oscilloscope. The new AutoTune process is faster and can tune the RefleX System more accurately, using EEPOTs - Electrically Erasable Potentiometers, decreasing
scale subinterpolation errors to below 1 micron. How does it work?
AutoTune monitors all 4 signals from each encoder and adjusts 8 EEPOTs per axis to bring the system into a tuned state. In order for AutoTune to
function, all 3 axes must be moving at all times. How do I get there?
- Press the service utilities button.
- Enter in password. This is the last 5 digits of the machine serial number reversed. Press the Done key.
- Press the AutoTune button.
Tuning: 1.) The first screen will ask you to place the machine in the home position.
- Unlock axes.
- Place machine in the home position. This is the upper, left, front corner.
- Press the Done softkey.
2.) Immediately begin moving the machine to the lower, right, back corner. You should move at a rate so that it will take you about 20 seconds to move diagonally across the machine volume. Do not
stop the machine at any time, as this will cause AutoTune to fail. All 3 axes must be moving at all times. If the AutoTune process has not been completed by the time you reach the lower, right, back corner,
return towards the home position. 3.) As the tuning proceeds, AutoTune will step through the tuning stages show on the screen. The steps are as follows:
- Initializing AutoTune.
- Adjusting Individual Signals.
- Adjusting Combined Signals.
Fine Tuning
4.) If AutoTune passes, a screen containing a smiley face and a message saying "AutoTune Passed" will appear.
- Press the done button to save the new EEPOT settings. (Cancel will abort the tuning procedure and revert all EEPOT values to their previous settings.)
- Check the tune via the Align utility. Change to "After AutoTune Mode". Verify that bar graphs are between the dotted lines. See the Align utility for more information.
- Check the tune again via the Lissajous utility. Verify that all three axes create round plot centered arount the center of the graph, extending outwards to the 4 tic marks. See the Lissajous utility
for more information.
Double check the tune by going to measurement screen and move all 3 axes. If the machine is in tune, you will observe the RefleX
counters moving. If the machine is out of tune, a error screen such as X rate error will appear.
5.) If AutoTune fails, see below possible causes and remedies.What causes AutoTune to fail:
The following are reasons why AutoTune will fail: (in order of decreasing probability)
- The operator stopped moving an axis during AutoTune.
- An encoder cable is not plugged in securely.
- The encoder is not aligned correctly.
- A hardware error has occurred in the controller.
- The 450V high voltage cable has sagged onto the adapter board.
- The scales have not been cleaned properly.
- The encoder or scale is defective.
- The encoder cable has a broken wire.
Interpreting AutoTune Failure Screen: If AutoTune can not bring the machine into tune, an error screen will be
displayed. Starting with version 1.05, new hardware error codes have been implemented. 0 = All passed!
-1 = Step timed out. -2 = The pot saturated low.
-3 = The pot saturated high. Any other positive number represents how far AutoTune came from getting that
particular step to within specifications. By presenting the information in this manor, when trying to remedy a proble, only the axis which has failed needs
service attention. Fixing an AutoTune failure: 1.) If an AutoTune has failed, try the AutoTune process again. It is quite possible that you stopped moving during
the proceedure thus causing the process to fail.
2.) If AutoTune is still failing, go back and check your signal levels again with the Align utility. If, while the machine is moving, the signal levels are
above the dotted line, then try AutoTuning again. Otherwise, determine why signal level is so low (ie degraded encoder, misaligned encoder, etc)
3.) If AutoTune is still failing and the failure occurs (ie non
zero integers) in the "Combined Offsets" and "Fine Tuning" step and the "Fine Tuning" result is -3, this is usually caused by a signal not getting to the RefleX system.
4.) If only 1 axis is failing, perform the following proceedure.
- Look at AutoTune Results Screen. Which axis is failing (numbers other than 0). Which other two axes are good (All numbers zero). For example say the X & Z axes are passing, Y axis is
failing.
- Swap the bad axis cable with a known good axis. (ex. We'll swap X & Y) Note: You do not have to turn the controller off to do this.
- Run AutoTune again
- Now in which axis is AutoTune failing?
If the failure is still in the same axis, the RefleX box has a hardware failure. If the failure
has moved to a different axis, then there is a problem in the encoder system. See possibilities listed above in the "What causes AutoTune to fail" section.
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