Moog Crossbow NAV440 Series - Manual (Page 32)

Page 32
NAV440 User Manual
7430‐0131‐01 Rev. F
Setting Def ue ault Val Comments
Orientation See Figure 4on
page 22. To configure the axis orientation, select the desired measurement for each axis:
NAV‐VIEW 2.2 will show the corresponding image of the unit, so it easy to
visualize the mode of operation. Refer to Orientation Field on page 84 for the
twenty four possible orientation settings. The default setting points the
connector AFT.
Freely
Integrate
OFF The Freely Integrate setting allows a user to turn the unit into a free gyroscope. In
free gyroscope mode, the roll, pitch and yaw are computed exclusively from
angular rate with no Kalman filter based corrections of roll, pitch, and yaw. When
turned on, there is no coupling of acceleration based signals into the roll and
pitch or magnetometer based signal to the yaw. As a result, the roll, pitch, and
yaw outputs will drift roughly linearly with time due to sensor bias. For best
performance, the Freely Integrate mode should be used after the algorithm has
initialized. This allows the Kalman Filter to estimate the roll and pitch rate
sens
gyro or bias prior to entering the free gyroscope mode. Upon exiting the free
scope mode (OFF), one of two behaviors will occur
ƒ If the unit has been in freely integrate mode for less than sixty seconds, the
algorithm will resume operation at normal gain settings
ƒ If the unit has been in freely integrate mode for greater than sixty seconds,
. the algorithm will force a reset and reinitialize with high gains automatically
Use GPS ON The Use GPS setting allows users to turn on and off the GPS feedback. The
default setting is ON. When Use GPS is turned OFF, the units behavior will revert
to AHRS440.
Stationary
Yaw Lock OFF This setting defaults to OFF; it is recommended to be OFF for NAV Function. The
stationary yaw lock is only recommended for consideration when the unit is
operating with GPS (Use GPS = ON) and WITHOUT magnetometer feedback
UseMags ( = OFF). Stationary yaw lock may be appropriate if the user platform is
a ground vehicle.
Use Mags ON The Use Mags setting allows users to turn on and off the magnetometer feedback
for yaw/heading stabilization. The default setting is ON.. When Use Mags is
turned ON, the unit uses the magnetic field sensor readings to stabilize the drift
, and it s in yaw laves the yaw to the compass reading provided from the magnetic
field sensor readings.
When UseMags is turned OFF, the heading (yaw) angle measurement of the unit
will be slaved to the GPS heading if GPS is available, otherwise the heading will
ff the drift feely. The reason for this setting is to give the user an ability to turn o
magnetometer stabilization when severe magnetic distortion may be occurring.
This setting is desirable when the user vehicle temporarily moves in close
proximity to a large ferrous object. When the UseMags switch is turned from OFF
to ON, the unit will reinitialize the yaw/heading angle with the compass reading
provided from the magnetic field sensor readings.