Moog Crossbow VG700MB Series - Manual (Page 32)

VG700M User’s Manual
Page 26 Doc.# 7430-0280-01 Rev. F
8 Appendix D. Troubleshooting Tips
Is the supply voltage and connections okay?
The VG700M needs at least a 16V power supply for proper operation.
Verify that your power supply is regulated and not current limited.
Ensure that the supply does not fall below 16V or go above 32V. Make
sure that all the connections are intact.
Is the VG700M mounting orientation okay?
The Pitch angle corresponding to ±90 degree orientation are singularity
points for the algorithm and you should not let the unit sit in this
position for extended periods of time. As a result, the angles start
drifting if you stay at these singularities for a long time. The longer you
keep the unit in a singularity position, the longer it will take for the unit
to stabilize upon recovery.
Are you exceeding the range of the rate sensors, causing the
outputs to over range?
Whenever the maximum range of the rate sensors is exceeded, the
VG700M algorithm strategy is based on the philosophy that any
overrange inputs are purely short-term disturbances (<100ms) and not
commanded inputs. In this case, the strategy is to allow the angles to be
computed through the overrange
, with any errors that accumulate
during the overrange being quickly removed once the input is back
within range. All output signals continue to be available during the
overrange. If the rate sensors are overranged for a longer time, the error
accumulation will be large and may take a long time to recover.
Do you have extended maneuvers close to the maximum range
of the rate sensors?
Although the VG700M is rated to operate at 200 deg/sec, extended
maneuvers close to the range should be avoided. Prolonged rates close
to the maximum range may result in larger errors due to scale factor
errors on the rate sensors.
Do you have heavy EMI interference in the environment?
Heavy EMI interference can cause a bias shift of the rate sensors and
hence continuous drift in calculated angles. Before you install the
VG700M in the system, by closely watching the rate sensor outputs,
you can test the effect of different potential EMI contributors (strobe
lights, microwave transmitters, alternators, radio modems, controllers
etc), by actually operating them. Move the VG700M to a location
where effects of such interferences are within the acceptable accuracy.