ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 1

Intro to Precision AgricultureIntro to Precision Agriculture

Students will be able to define/describe:Students will be able to define/describe:Precision Agriculture, GIS, GPS, DGPS, VRT, Remote Sensing, Precision Agriculture, GIS, GPS, DGPS, VRT, Remote Sensing, Pixel, Spatial Resolution, MultiPixel, Spatial Resolution, Multi--spectral, Data, Information, spectral, Data, Information, Knowledge, WisdomKnowledge, Wisdom

Students will be able to draw diagrams to describe the followingStudents will be able to draw diagrams to describe the followingtechnologies:technologies:

Yield MonitorYield MonitorVariable Rate PlantingVariable Rate PlantingVariable Rate Chemical ApplicationVariable Rate Chemical ApplicationRealReal--Time Differential GPSTime Differential GPS

Precision AgriculturePrecision Agriculture

AKA:AKA:Precision FarmingPrecision FarmingFarming by the InchFarming by the InchSiteSite--specific farming/agriculture/applicationspecific farming/agriculture/applicationPrescription FarmingPrescription FarmingSpatiallySpatially--Variable Crop ProductionVariable Crop Production

ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 2

SiteSite--Specific ProcessSpecific Process

VRT: Fertilizing

Site-Specific Scouting and Sampling

Yield Monitoring

Spraying

Seeding

TechnologiesTechnologies

Global Position System Global Position System –– GPS GPS –– Latitude and LongitudeLatitude and LongitudeYield MonitorYield MonitorGeographical Information Systems Geographical Information Systems –– GISGISDecision Support Systems Decision Support Systems –– DSSDSSSiteSite--Specific Sampling of Soil PropertiesSpecific Sampling of Soil PropertiesVariableVariable--Rate Application of Fertilizers and PesticidesRate Application of Fertilizers and Pesticides

The enabling technology for precision agricultureis position sensing, namely GPS.

ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 3

Global Position System: Global Position System: OverviewOverview

US DoD - GPS

US DoD - GPS US DoD - GPS

US DoD - GPS

US DoD - GPS US DoD - GPS

Latitude and Longitude CoordinatesLatitude and Longitude Coordinates

ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 4

Ag Mall, Lafayette, IndianaAg Mall, Lafayette, IndianaDecimal DegreesDecimal Degrees

Latitude: Latitude: 40.42233854Longitude: Longitude: -86.91510721

Degrees, Minutes, Seconds: DMSLatitude: 40° 25’ 20.4”Longitude: -86° 54’ 54.4”

Note the minus (-) sign indicates Longitudes which are West of the Prime Meridian.

GPS InformationGPS InformationABE local:http://danpatch.ecn.purdue.edu/~asm322/GPS/GPS.html

Trimble Tutorial: http://www.trimble.com/gps/US Army Tutorial: http://tsc.wes.army.mil/gps/gps.htmSmithsonian NASM Tutorial:http://www.nasm.si.edu/exhibitions/gps/index.htm

ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 5

GPS Precision GPS Precision -- UncertaintyUncertainty

GPS ReceiverGPS ReceiverNumber of satellites which can be receivedNumber of satellites which can be receivedAccuracy of clocksAccuracy of clocks

Satellite GeometrySatellite GeometryAtmospheric ConditionsAtmospheric ConditionsDifferential Correction SourceDifferential Correction Source

None None -- ~50 feet~50 feetWAAS (Wide Area Augmented Service) WAAS (Wide Area Augmented Service) –– ~10 feet~10 feetCoast Guard Beacon Coast Guard Beacon -- ~3 feet (distance to station ~3 feet (distance to station and weather)and weather)Satellite Subscription Satellite Subscription -- ~ 3 feet~ 3 feet

GPS Precision GPS Precision -- Uncertainty ReportingUncertainty Reporting

CEPCEP –– Circular Error Probability Circular Error Probability –– 50% are inside circle 50% are inside circle of this radius for stated time period of this radius for stated time period Trimble Ag 132 DGPS receiver Trimble Ag 132 DGPS receiver –– CEP of 1 meter for CEP of 1 meter for

24 hours24 hours

Pass to PassPass to Pass –– measured over a short time periodmeasured over a short time periodTrimble Ag 132 DGPS receiver Trimble Ag 132 DGPS receiver –– Pass to Pass Pass to Pass

uncertainty of less than 12 inches.uncertainty of less than 12 inches.

ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 6

GPS HardwareGPS Hardware

GPS ApplicationsGPS Applications

Position Logging:Position Logging:Boundaries Boundaries –– fields, crop areas, areas of interestfields, crop areas, areas of interestPoints Points –– locations of obstacles, sites of interestlocations of obstacles, sites of interestPaths Paths –– location of fence, watercourse, etc.location of fence, watercourse, etc.

GuidanceGuidanceNavigate to point for siteNavigate to point for site--specific samplingspecific samplingSwathSwath--width guidance, e.g. lightwidth guidance, e.g. light--barsbars

Controlled Steering Controlled Steering –– automatic, selfautomatic, self--guided vehiclesguided vehicles

ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 7

Position LoggingPosition Logging

FarmworksSiteMate

BlueTooth Airlink

Guidance to a Guidance to a Predetermined Predetermined

PointPoint

ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 8

Guidance: SwathGuidance: Swath--WidthWidth

AgleaderAgleader PF3000 + GPS + PF3000 + GPS + LightbarLightbar

LightbarLightbar (Trimble)(Trimble)

ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 9

Guidance: Guidance: Swath WidthSwath Width

120SETALeft Display Right Display

Cross Track Distance LED's

Steering Angle LED's

Turning Direction

Bearing

1Spray On

R 2.5Crosstrack Distance Swath Number

Guidance: Guidance: SwathSwath--WidthWidth

Pass to Pass Accuracy:~6 to 18”(10 minutes)

ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 10

Controlled Controlled Steering: Steering: AutoTracAutoTrac

Advertised Accuracies:~10 inches~1 inch with RTK

Base Station within ~10 miles

Hydraulic Control Valve on Power Steering

Controlled Steering: AutoControlled Steering: Auto--GuideGuide

ASM 222 Introduction to GPS 11/23/2004

Gaines E. Miles 11

Global Global Position Position SystemSystem

Communications Satellite

Questions ????Questions ????