GPS Applications for Precision Agriculture

1
GPS Applications for Precision Agriculture

• by
• Randy Price
• Precision Farming Technologies Engineer and
  Specialist
• K-State Extension and Research
• Kansas State University

2
Overview

• Discuss Current GPS Systems in Agriculture
• Where things are going
• Height Modernization Uses in Agriculture
• Questions?

3
Largest Users of GPS Systems in Ag. - Guidance
Systems

• Automatically (or through visual cues) steers a
  tractor through a series of GPS points or down an
  A-B Line.
• Reduces driver fatigue.
• Allows for straighter rows.

• Reduces overlap and skips.
• Can skip a wet spot in field during
  planting/cultivating, work other side of field,
  then go back and plant or cultivate area that
  was skipped.

4
Different Types of Guidance Systems

• Manual Guidance
• Light Bars, PDAs
• Auto-Steer Systems (performs the steering
  function for you)

Computer and Operator Interface
Hydraulic Valve Block
GPS Antennae
5
Accuracies Available to Farmers

• WAAS
• OmniSTAR
• Similar to WAAS, but with carrier phase (L2)
  information.

• RTK
• L1 and L2 with Base Station.

6
Pass-to-Pass Accuracies of Each System

• WAAS 6 to 12 inches 5 ft. deviations
  year-to-year.
• OmniSTAR 2 to 5 inches
• XP - /- 8 inch year-to-year accuracy
• HP - /- 4 inch year-to-year accuracy
• RTK 1 inch or less and year-to-year

7
Portable Removable Units

• All-in-one
• Less Wires
• Easy Installation
• Movable
• Available in
• WAAS
• OmniSTAR
• RTK
• Low Cost 3000 to 6000

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Built-in Units
9
High-End Displays
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John Deere System - StarFire

• Similar to others
• SF1 WAAS
• SF2 OmniSTAR
• RTK

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Ways to Get RTK Correction

• Dealer or Farmer Owned Base Station
• 30 to 15 miles radius
• Portable Base Station
• 2 to 6 mile radius

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Single Frequency (Non-RTK) Portable Base Station

• Outback Guidance Baseline
• L1 Only

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Many Other Systems
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WAAS Coverage of Kansas
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Light Bar / WAAS Guidance System - Light Bar
Steering Only

• Set overlap correctly to manufacturers
  recommendations!

16
Pass-to-Pass Accuracy with Time
17
WAAS System - Long Term Offset from Original A-B
Line
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Five Different RTK Systems
(Source Adumchuk - University of Nebraska)?
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Pass-to-Pass Accuracy in Multiple Research Papers
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Pass-to-Pass Accuracy at Drawbar
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Cost of Guidance Systems
22
Prices Going Down New Products

• EzGuide 250 Lightbar
• 1500.00
• Leica MojoRTK System
• RTK and Base Station for 12,980

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Where GPS is Going

• Accuracies have been seen as quite good (by
  Farmers standards)
• Boom Control
• Turns off the boom sections as they pass over
  areas already sprayed
• Seed Control
• Turns off every 1 or 2 planter boxes when needed

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Example of Planter Auto Shut-Off
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Uses of GPS Height Modernization

• Government
• Watershed Mapping and Flood Plain Determination
• BMPs (best management practices)
• Atrazine Measurement (Herbicide for Killing
  Weeds)
• Sediment Loads
• Individual Farmer
• Not as much
• Relative heights usually good enough, but bench
  mark may be used to help determine sloped land
  and land type easier

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Effects of Crop Growth

• Rainfall
• Soil Texture
• Texture affected by land type, slope, topography

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Topography

• Topography has a significant impact on soil
  formation. It determines the runoff of water and
  the micro-climate which in turn affects
  vegetation.
• Water moving across the surface strips parent
  material away and deposits in low areas.

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Other Sensors Seeing Success

• NTech Greenseeker
• Tractor Mounted
• Hand-held Units
• Sees the Same thing as Remote Sensing Units
• Real-time

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Kansas Wheat Field 3 to 7 Slope
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Nitrate Calibration Plots
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Flood Plain Soil

• Ponding of water / soil texture may explain
  differences in vegetative index in this map

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The Future

• No-till becoming more widely used.
• Farmers doing much more spraying and at higher
  frequencies (more trips across the fields).
• High cost of inputs (fertilizer and herbicide)
  causing farmers to re-think spraying strategies
  and move towards variable rate applications.
• Land levelling could become more important as
  inputs become higher / crops worth more.
• Farmers will probably tend to use data that is
  easy to get first for developing prescription
  maps
• Soil Texture
• Topography
• Relative (RTK measurement)
• Tilt sensors
• Preloaded map, etc.
• Greenseeker
• Etc.

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Automated Tractors

• Auto-turn around and guidance
• John Deere ITEC Pro
• Implement Steering
• Trimble
• GPS on Implement down to 1 inch.
• AutoFarm AFTracker

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The End

• (Questions?)?

35

• Things to look at
• Land leveling in flood prone areas
• How much does this help versus cost
• Disadvatnages?
• Etc.
• Cell towers for RTK correction (and internet)

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To Replace Base Station

• Need the Following
• Must be close (for errors to be lowest)?
• Fast repeat time
• Sprayers travelling at 15-20 MPH need a GPS with
  an output rate or 5 to 20 Hz (real-time).
• Different Options
• Cellular
• Internet, etc.
• Some Type of Standardized Transmitted Signal
• Similar to Coast Guard Beacon

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Topography in Turn Determines Texture to Some
Degree
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Effect of topography and texture

• Contribution of texture is significant even after
  accounting for topography effect

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Texture Triangle
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Other Uses of RTK

• Variable Rate Spraying
• Farmers are looking for those easy to find data
• Currently
• GPS location
• Next
• Greenseeker / Remote Sensing
• Elevation / Topography
• Texture / Soils Maps
• Organic Matter

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Payback Period

• Estimate 30 off without guidance, better than
  15 with WAAS alone.
• Typically, 2.5 yrs needed to pay off lower-end
  system (depending upon type of system purchased
  and number of uses per year).
• Ag Economics at Kansas State University
• http//www.agmanager.info/farmmgt/machinery/defaul
  t.aspDecision-Making20Tools

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Sensors Necessary as Better Accuracy is Desired

• Tilt sensor
• probably the best sensor you can add on
• IMU (Inertial Mass Unit)
• Next best sensor
• Helps short term loss of GPS signal.

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Website

• www.bae.ksu.edu/precag
• Email rrprice_at_ksu.edu
• Call 785-532-2929

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Possible Future Noise

• We are in a minimum of energy disruption caused
  by sun spots, etc.
• This will continue to get worse to a maximum at
  2012.
• Some worry for WAAS

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Air Clutch on Planter System
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Plant Height May Be Needed
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Example of Automatic Planter Shut-Off
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On/Off Seeder Controls
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New Equipment

• Leica MojoRTK Agricultural Guidance System
• RTK and base station for 12,980
• Still need hydraulic actuator box for auto-steer

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Parts of System

• Guidance unit in a radio type mount housing
• Built into a radio unit
• Mounts up in the cab where the radio was located
• Includes AM/FM radio
• RTK accuracy (2 inch)?
• Portable Base Station
• Virtual Wrench
• Remote service capability via
• digital data cell network
• 12,980 price tag
• Note Still need a steering kit!!!

51
Wireless Data Downloading

• Go Wireless with Farm Sync
• Downloads data when equipment close enough to
  wireless router in house or building.
• Download multiple cpmputers from different
  equipment.
• Extended antennaes avaivble
• 1000 ft. extra

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Steering Wheels Actuator

• Major Improvements with the Trimble Ez-guide
  System
• Faster line acquisition
• EZ-Guide 500 /- 2 inch accuracy
• Older EZ-Guide Plus /- 6 inch accuracy

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Air Compressor
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WAAS Update New Satellites

• WAAS Satellites 122 and 134 taken out of service
  July 31st!
• These were the main Satellites for WAAS
  reception.
• Upgraded with 135 and 138 (newer, higher
  transmitting power, etc.).
• Older GPS units may need software updating!!!

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Patterns

• A-B Line
• A (based on degrees direction)?
• Adaptive Curve
• Headlands
• Pivot
• Etc.

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Built-in Units

• Multiple Components Needed
• Display Computer (moveable)?
• Guidance Computer (not moveable)?
• Other Sensors to Increase Accuracy
• Tilt, Steering Angle, etc.
• Typically 15,000 or more (when all components
  combined together)

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Where is GPS Going?

• WAAS most sold in the U.S.
• Mainly because free and accuracies good enough
  for many farming operations
• Omnistar
• Usually just an upgrade in price from WAAS with
  an antennae and sibscription.
• RTK least sold
• Mainly larger farm with more money
• Farmers needing strip tillage, etc.