I plotted the status of the tiedowns for
11:30 to 13:00 hours on 03dec13:
Plot 1 shows 11:30 to 13:00
- Each color is a different tiedown (black:td12, red:td4,
- Top: tiedown positions.
- You can see td4 (red) moving around 12.2 and 12.3 hours
- 2nd: velocity feedback .
- This is the output of the dac,signal conditioning board
(at the relay between the dac output and the motor).
- The jumps 0 to 2000 are interference in the readback
- there is lots of activity at 12.1 and 12.5 for td
- The purple line is the commanded velocity for td4
- 3rd: motor amplifier speed monitor.
- read back from the motor
- At 12.1 and 12.5 td 4 was actually moving (so the feed
back for td 4 was not all interference)
- 4th: state of each td
- 0 off, 1 enabled (ready to move), 2 powered (waiting for
- bottom: motor torques
- td 4 red motor was working very hard during these
Plot 2 is a blowup
of td status from :12.04 (12:02:24) to 12.07 (12:04:12) (.ps)
- Each + is a time step of 1 second.
- The velocity feedback is jumping back and forth (at up to
a second rate)
- The purple commanded velocity is small and smooth so the
little star is not commanding the dac to do this.
- The amplified speed and torque are following the velocity
feedback so the velocity feedback in not interference in the
- The velocity feed back was jumping up to once a second
- This only occurred twice during the day on 03dec13.
- The motor speed and torques were following this (so it
wasn't interference in the velocity feedback readback).
- The little star commanded velocity was ok
- The problem is either:
- The velocity command was modified when sent little start
to dac (bus problem?)
- The dac is bad
- The signal conditioning board is bad.
- We should replace the signal conditioning and dac board ..
and test these in the lab..
- The problem is intermittent so we need a diagnostic that
can run for hours at a time.