Getting the Value from Guidance Systems, Light Bars, and GPS Marvin Stone Biosystems and Agricultural Engineering

GPS – How it works Constellation of more than 24 satellites –Known positions (at any time) –Each continuously transmits time and position data Two frequencies (L MHz and L MHz) –Each orbits twice per day Ground receiver (Your GPS receiver) –Calculates Position and Time Times signal and calculates distance to each satellite received Triangulates Latitude and Longitude Calculates time

Components of a “GPS” system GPS Assisted Guidance System

Components of a “GPS” system GPS Assisted Guidance System with Mapping

Components of a “GPS” system GPS Based Yield Monitor with Mapping

Components of a “GPS” system GPS Based Yield Variable Rate Planter

Components of a “GPS” system GPS Based Automatic Steering System

Components of an auto-steering system User Interface GPS Receiver and Antenna Electronic Control Unit Steering Servo Device Wiring harness

MidTech system configuration Midwest Technologies IL

Differential GPS Differential GPS is required for guidance –Without differential corrections, precision is ± 100 ft. –With corrections ±3 ft, ±4”, ±0.3” Method: –Nearby ground station at known position uses GPS to determine errors in distance to satellites –Errors are sent to roving GPS units Issues –Where do you get the correction signals? Coast Guard Omnistar Deere other

Differential GPS communications pathways

Differential correction sources SourceCostURL Terrestrial differential correction USCG BeaconFreeusers.erols.com/dlwilson/gpswaas.htmusers.erols.com/dlwilson/gpswaas.htm User provided?Self SBAS (Satellite based Augmentation System) Omnistar$800/yrwww.omnistar.com/faq.htmlwww.omnistar.com/faq.html OmnistarHP$1500/yrwww.omnistar.com/faq.htmlwww.omnistar.com/faq.html Deere Starfire1$500/yrStarFireGlobalHighAccuracySystem.pdfStarFireGlobalHighAccuracySystem.pdf Deere Starfire2$800/yrStarFireGlobalHighAccuracySystem.pdfStarFireGlobalHighAccuracySystem.pdf WAASFreeusers.erols.com/dlwilson/gpswaas.htmusers.erols.com/dlwilson/gpswaas.htm

Coast Guard Beacon Coverage

Deere Starfire™ SBAS John Deere’s StarFire System: WADGPS for Precision Agriculture Tenny Sharpe, Ron Hatch, NavCom Technology Inc.; Dr. Fred Nelson, John Deere & Co.

Agriculture GPS Type Comparison PerformanceLowMiddleHighVery High TechnologyLow cost DGPS DGPSTwo Frequency DGPS Real Time Kinematic RTK GPS Price $100 to 600$600 to $3,000$1,500 to 10000$25,000 to $42,000 Differential Source WAASWAAS + C.G. Beacon + SBAS WAAS + C. G. Beacon + HP SBAS User Base Station HP SBAS Static Accuracy 5’-12’1’-3’4”-10”1” ApplicationScoutingMapping / Guidance Elevation mapping, Precision row operations

GPS Technology vs. Precision (New Holland IntelliSteer ™ ) 1. DGPS –Differential correction signal provided by free WAAS service. –Typical accuracy: +/- 10 inches 2. DGPS VBS (Virtual Base Station) –Differential correction signal provided by OmniSTAR subscription. –Typical accuracy: +/- 10 inches 3. DGPS HP (High Performance) –Differential correction signal provided by OmniSTAR™ subscription. –Typical accuracy: +/- 4 inches 4. RTK (Real Time Kinematics) –Differential correction signal provided by base station. –Typical accuracy: +/- 1 inch

Equipment on the market M. Sullivan, Ohio State Univ.

GPS Receiver Types Low cost GPS –Example: Handheld GPS –Receiver Channels – 12 –Position update rate 1 per 5 sec. –Likely to provide WAAS differential –Precision probably not better than ~ 5’ –Data output may or may not have NMEA 0183 output Mapping quality GPS (Simple DGPS) –Example: Trimble AgGPS 132 –Receiver channels – 12 –US GPS/EGNOS capability –Position update 10 per second –WAAS, C. G. Beacon, Omnistar/Racal SBAS –Precision better than 3 ft –Data Output, NMEA CAN

GPS Receiver types High Precision differential GPS –Example Deere Starfire-2 –Receiver channels 20 GPS, 2 SBAS both L1, L2 freq. –US GPS/EGNOS capability –Position update 5 to 50 per second –WAAS, Deere SBAS –Precision better pass to pass 4” –Data Output, NMEA CAN –Slope compensation

GPS Receiver types RTK GPS –Example: Trimble Ag GPS 252 –Receiver channels – 24 –US GPS/EGNOS capability –Position update to 10 per second –WAAS, OmnistarHP, RTK –Pass to pass accuracy 0.3” to 2” –Data Output, NMEA 2000 ISO CAN Requires user provided base station –2 x $ $3000 lightbar + radio link –Within 6 mi. radius line-of-site

Using Automatic Steering Easy to use – 15 min to learn –Enter field and move to start position. –Press “Start” or “A” –Drive the first pass –Press “Continue” or “B” –Turn to the next pass, System will lock on –Release the steering wheel or press “Resume”

Operating modes

Additional features Headland Indicator Return to Point Snap to Path Tilt Sensors

Return on investment Optimize Machine Efficiency (more acres with fewer hours) –Operate at faster field speeds –Reduce overlap Reduce per acre fuel consumption Reduce overlap on implements and sprayers Extend Machine Operating Time –Efficient night operation –Run in dust and fog Reduce Operator Fatigue –More comfortable working hours –More time to supervize machine functions Increase Yield –Manage compaction with planned traffic patterns –Place fertilizer and herbicides and pesticides more accurately

Automatic Steering may result in different farming practices Controlled compaction Tramlines Night operations Higher speeds Midwest Technologies IL

Calculated returns Manual guidance allows a 13 percent increase in field speed while DGPS and RTK auto guidance allow a 20 percent increase. (Deboer and Watson, Purdue 1984) Net revenues above variable and technology costs by $28 to $30 per acre (Watson, Purdue, 1983). Impact of automatic guidance on an 1,800-acre corn/soybean farm (Lowenberg-DeBoer, Purdue 1984). –Reduced field time by 17%, enabling the farm to expand while using the same machinery and increase returns by $7.36 per acre. –If soils suffered moderate yield loss from compaction, the controlled-traffic capabilities of a high-accuracy guidance system could increase returns by $18.84 per acre.

Issues in selecting a GPS based guidance system Do’s –Assure system fits your vehicle(s) –Meets current and near term accuracy requirement –Is adequately portable for the need –Satisfies you on a test drive –Understand the differential correction requirements Subscription (SBAS) Hardware (RTK) –Compatible with other PF equipment you plan on using

ResourcesResources Review of auto-steering systems – Beelines link – Trimble link – Successful Farming (Richenburger) –