Owner's manual

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Page26
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NAV440UserManual
7430‐0131‐01Rev.F
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InadditiontothescaledsensorpacketsdescribedintheIMU440section,theVG440hasadditionalmeasurement
outputpacketsincludingthedefault
A2AnglePacketwhichoutputstherollangle,pitchangle,anddigitalIMU440
data.
N0andN1packetsarealsoavailableforusewithanexternalGPSreceiver.RefertoChapter9.Communicating
withthe440
andChapter10.Guidelinesforfullpacketdescriptions.
VG440AdvancedSettings
Inadditiontotheconfigurablebaudrate,packetrate,axisorientation,andsensorlow‐passfiltersettings,VG440
providesadditionaladvancedsettingsthatareselectablefortailoringtheunittoaspecificapplicationrequirements.
hesettingsarelistedin below.
T

Table6
Table6VG440AdvancedSettings
Setting DefaultValue Comments
BaudRate 38,400baud 9600,19200,57600alsoavailable
PacketType A2 S1,S2,N0,N1alsoavailable
PacketRate 25Hz ThissettingsetstherateatwhichselectedPacketType,packetsareoutput.
Ifpolledmodeisdesired,thenselect
Quiet.IfQuietisselected,theunitwillonly
sendmeasurementpacketsinresponsetoGPcommands.
Orientation
See
Figure4on
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configuring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
ywith
pitch.Asaresult,theroll,pitch,andyawoutputswilldriftroughlylinearl
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 e
ratesensorbiaspriortoenteringthefreegyroscopemode.Exitingthefre
scopemode(OFF),causesoneofthefollowingbehaviorstooccur:
•
gyro
Iftheunithasbeeninfreelyintegratemodeforlessthansixtyseconds,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.