Azimuth motion failures dec09,jan10


     There was a series of azimuth motion failures on 07dec09 and again on 31jan10. A motion failure can be caused by encoder showing that the system moved opposite to the direction requested. It can also occur if requested motion does not occur after a specified time interval (assuming the system is active).


    Aeronomy had been running for a few days and had been getting the motion failures. The moved the azimuth from 168 to 168+90 degrees at slew speed for the entire time. The errors occurred when:
The plots show the azimuth motion near az=168 degrees (.ps) (.pdf ):


    The speed monitor output is used by the PI loop to control the azimuth. All 8 of the amp velocities are summed to get the final control command. Looking at one of the amplifiers, it's speed monitor output had a large dc offset (when the azimuth was stationary). After replacing the amplifier the az motion failure problem went away (at least till jan10).
  processing: x101/091207/


    The az motion failure occurred 3 times in the early morning. The first time was during an astronomy. The last 2 times was the aeronomy azimuth swings.
    The plots show the azimuth information during the failures (.ps) (.pdf):