Moog Crossbow GNAV540 - Manual (Page 30)

Page 30
GNAV540 User Manual
7430‐0808‐01 Rev. B
Setting Defa ue ult Val Comments
Orientation See Figure 4 on
page 24. To configure the axis orientation, select the desired measurement for each axis:
NAV‐VIEW 2.2 then shows the corresponding image of the unit, making it easy to
visualize the mode of operation. Refer to Orientation Field on page 86 for the
ints the twenty four possible orientation settings. The default setting po
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, or yaw. When
turned on, there is no coupling of acceleration based signals into the roll and pitch
tch, and or magnetometer based signals to the yaw. Due to sensor bias., the roll, pi
yaw outputs will drift roughly linearly with time.
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 rat
the free
e sensor bias prior to entering the free gyroscope mode. Upon exiting
gyroscope mode (OFF), one of two behaviors will occur:
• nds, If the unit has been in freely integrate mode for less than sixty seco
the algorithm will resume operation at normal gain settings
• 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 Mags ON The
yaw
Use Mags setting enables turning on and off the magnetometer feedback for
/heading stabilization.
• The default setting is ON. When Use Mags is turned ON, the GNAV540 unit
uses the magnetic field sensor readings to stabilize the drift in yaw, and it
slaves the yaw to the compass reading provided from the magnetic field
sensor readings.
• When Use Mags is turned OFF, the heading (yaw) angle measurement of the
unit will drift and freely integrate. In effect, this setting converts the
functionality to VG. However, unlike a unit in the VG Function, this can be
done on a selectable basis and changed in real time during a mission.
This setting enables turning off the magnetometer stabilization when severe
magnetic distortion may be occurring. This setting is desirable when the system
temporarily moves in close proximity to a large ferrous object. When the Use
Mags switch is turned from OFF to ON, the unit will reinitialize the yaw/heading
ngle with the compass reading provided from the magnetic field sensor
eadings.
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