Setup and Advanced Tuning Guide Manual

2202SouthRiversideDrive,Ames,IA50010
Phone:515‐232‐5363Internet:http://www.agleader.com
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25‐Jun‐10‐RevE
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6
HowtheParaDymeSteeringControllerworks
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Imaginethreemeninaspecialtractorcab,namedSteering,HeadingandCrossTrack.Thecabonthe
tractorisspecialbecausenoneofthethreemencanseeoutsidethewindowsofthecab.Insidethecab,
eachmanhasauniquejobandendgoal:
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•Steering’sjobistosteerthetractorleftandright.
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•Heading’sjobistouseacompassandmeasurethedifferencebetweenthetractor’sheading
andtheABlineheading.HeadingalsotellsSteeringwhatcurvature(radius)tosteerthe
machine.
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•CrossTrack’sjobistouseameasuringtapeandtomeasurehowfarofflinethetractoris
fromtheABline.
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Thesethreemeninteractwitheachothertosteerthetractorinthefollowingway,keepinginmind
theycannotseetheirsteeredwheelsorwheretheyareheading.SeeFigure3‐InsidetheParaDyme
Controller
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•SteeringlistenstoHeadingandHeadinglistenstoCrossTrack,whichissuecommandsonhowfar
leftorrighttosteerthetractortokeepitontheABline.
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‐ Steering’sgoal:Tosteerthetractorinaresponsivemanner,butnotinajerkyorlazyway.
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•HeadingtellsSteeringhowtosteerthetractorleftandrightinordertominimizethedifference
betweenthetractor’sheadingandtheABLineheading.
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‐ Heading’sgoal:Tominimizethedifferenceinthetractor’sheadingandtheABLineheading.
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•CrossTrackalsotells
HeadingwhichinturnstellsSteeringhowtosteerthetractorleftandright
inordertominimizethetractor’sdistancefromtheABLine,orit’sofflinedistance.
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‐ CrossTrack’sgoal:TominimizethedistancebetweenthetractorandtheABLine.
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•LineAcquisitionModeisthemodeinwhichthesteeringcontrollerisinwhentheParaDymesystem
isdrivingthevehicletotheABLine.TheParaDymesystemcomesoutofLineAcquisitionModewhen
thevehicleCrossTrackErrorisapproximatelylessthan6inchesforapproximately2ormoreseconds.
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NOTE1:DuringLineAcquisition(whenthevehicleisacquiringtheABline),Steeringignores
CrossTrackError,soonlySteeringandHeadingareresponsibleforgettingavehicletotheAB
Line.
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