Instruction Manual

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Page30
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GNAV540UserManual
7430‐0808‐01Rev.B
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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.
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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
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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.
a
r
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