Owner's manual


NAV440UserManual
7430‐0131‐01Rev.F
Page24
DigitalIMU440dataisoutputovertheRS‐422ataselectablefixedrate(100,50,25,20,10,5or2Hz)oras
requestedusingthe
GP(GetPacket)command.
ThedigitalIMU440dataisavailableinoneofseveralmeasurementpacketformatsincludingScaledSensorData(S1
Packet)andDelta‐Theta,Delta‐V(S2Packet).IntheScaledSensorData(S1Packet)dataisoutputinscaled
engineeringunits.IntheDelta‐Theta,Delta‐Vformat(S2Packet)scaledsensordataisintegratedwithrespectto
thetimeofthelastoutputpacketandthedataisreportedinunitsofaccumulated(i.e.,delta)degreesand
meters/second.Fordetailsaboutfullpackets,referto
Chapter9.Communicatingwiththe440andChapter10.
ProgrammingGuidelines.
NOTE:
TheDelta‐Theta,Delta‐Vpacketisonlyrecommendedforuseincontinuousoutputmodeat5Hzorgreater.
Polledrequestsforthispacketwillproducevaluesaccumulatedsincethelastpollrequest;theyaresubjectto
overflow(datatypewraparound).
IMU440AdvancedSettings
TheIMU440advancedsettingsaredescribedin below.AlloftheadvancedsettingsareaccessiblethruNAV‐
VIEW2.2undertheConfigurationMenuUnitConfigurationsettings.ForinformationaboutusingNAV‐VIEW2.2,
referto
Table5
Chapter7.Configuringthe440SerieswithNAV‐VIEW2.2.
Table5IMU440FunctionAdvancedSettings
Setting DefaultValue Comments
BaudRate 38,400 9600,19200,57600alsoavailable
PacketType S1 S2alsoavailable
PacketRate 100Hz
Thissetstherateatwhichtheselected
PacketTypepacketsareoutput.If
polledmodeisdesired,thenselectQuiet.IfQuietisselected,theunitwill
onlysendmeasurementpacketsinresponsetoGPcommands.
Orientation
See
Figure4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
OrientationFieldonpage84for
thetwentyfourpossibleorientationsettings.Thedefaultsettingpointsthe
connectorAFT.
AnalogFilter
Clocks1,2,3
25Hz
Thelowpassfiltersaresettoadefaultof25Hzfortheaccelerometers,and
25Hzfortheangularratesensors.Thereisonefiltersettingforallthree
angularratesensors.Therearetwosettingsfortheaccelerometers,onefor
theXandYaxes,andaseparatesettingfortheZaxis.Inmanyinstallations,
theZ‐axisvibrationlevelismuchhigherthanintheXandYaxes;insuch
casesitcanprovehelpfultofiltertheZ‐axisatalowercutoffthantheXandY
axes.Formoreinformation,
AnalogFilterClocksbelow.
AnalogFilterClocks
Typically,thereisnoreasontochangethelow‐passfiltersettingsontheIMU440orother440SeriesInertial
Systems.However,whena440Seriesunitisinstalledinanenvironmentwithalotofvibration,itcanbehelpfulto
reducethevibration‐basedsignalenergyandnoisepriortofurtherprocessingonthesignal.InstallingtheIMU440
inthetargetenvironmentandreviewingthedatawithNAV‐VIEW2.Xcanbehelpfultodetermineifchangingthe
filtersettingsisneeded.Althoughthefiltersettingscanbehelpfulinreducingvibrationbasednoiseinthesignal,
cethebandwidthofthesignal,i.e.canwashoutthesignalscontainingthe
clocksettingsareshownindefaultIMU440coordinatesystem.
lowfiltersettings(e.g.,1Hz)alsoredu
dynamicsofatarget.Theanalogfilter
Treatthefiltersettingswithcaution.