Vehicle guidance From horses to GPS

Vehicle guidanceFrom horses to GPS

Jorge Heraud and Arthur LangeTrimble Navigation Ltd.

June 2009

The greatest challenge

This generation of engineers and scientists will need to solve the toughest of problems ever encountered– Energy shortage, Food shortage, Fresh water shortage, Global

Warming

“Today more than ever before, Science holds the key to our survival as a planet and our security and prosperity as a Nation” Barack Obama, Dec 20, 2008

I will show you, how previous generations rose to tough technical challenges

For today

History of automatic steering Modern automatic steering Why GPS guidance so widely used

History of manual guidance as seen through patents

1870 - row marker for single-row horse powered plowing

1876 - Two-row corn planterwith row marking

1953 – Cabled double row marker1963 – Cabled folding row marker

1921 – Looking through the tractor1951 – Front mounted visual aid

1951 – Double hood mounted visual aid1990 – Windshield and hood visual aid

1976 – Visual aid for implement guidance

1970 – Electronically marking system

1987 – Paper tissue marking system

Tissue paper roll goes here

History of automatic guidance as seen through patents

1885 – "Furrow pilot”

1914 – Improved furrow follower

1949 – Movable furrow follower

1941 – Spiral guidance

1970 – Safety stopping mechanism

1976 – Automatic system to steer harvesters

1976 – Crop feelers using strain gauges

1996 – Rocking sensors boundary detection 1998 – Ultrasonic sensor boundary detection

Modern Automatic Steering systems

GPS based systems are now the norm for automatic steering

Manual GPS started around 1995 Automatic GPS started in 1997

– Hydraulic, steer-by-wire, CAN, electric motor

Why is GPS guidance so widely used

GPS guidance doesn’t accumulate errors

Prior pass guidance

Visual aides, row markers, foam markers

Fixed pass guidance

GPS, strings when planting orchards

Skips

Overlaps

Re-start

Savings of 10%+ on skips and overlaps– Just drive to get the savings

Operate at faster speeds, at night Reduced fatigue, convenience All field patterns All terrains Facilitates / enables new practices

– Strip till, band spraying, drip tape, strip- intercropping

Reduces need for additional on farm labor – Performance not skill dependent– “Grandpa is planting again”

Convenient embodied technology with a quick payback

GPS guidance enables precision Ag

Automatic section control

HeadlandReaction time

Overlap area

Automatic section control minimizes overlap and slow down

Man

ual s

huto

ff

Overlap cut down by 75%

Autom

atic

3 se

ctio

n sh

utof

f

Overlap eliminated

Autom

atic

shu

toff

r

ow le

vel

Automatic section control

Field NOT Using Air clutches

Field Using Air Clutches

Ag Journey

Ag Journey

Ag Journey

Ag Journey

Ag Journey

Ag Journey

Automated GuidanceImplement GuidanceVariable RateOverlap SwitchingData Transfer

12.0%3.0% 7.3%4.6%

?

12.0%Total Savings

Value Proposition

15.0%22.3%26.9%>26.9%

Engineers working on Automatic Guidance and Engineers working on Automatic Guidance and Precision Agriculture have increased Precision Agriculture have increased

productivity by 26.9% in the last 14 yearsproductivity by 26.9% in the last 14 years

The Ag Engineering community is ready for the next The Ag Engineering community is ready for the next challengechallenge

GPS and GNSS review

GPS

2. Satellitestransmit ranging signals & orbit info

3. Position, velocity, & time computed from range measurementsand data message

1. Atomic standards in satellites (4 needed) Each SV transmits signals and data that are received by the rover (user equipment). This allows the rover to measure the distance to each SV. These are the ‘Pseudoranges’

In 3-=dimensions, it takes 4 Pseudoranges to calculate the position since time at the rover is also a variable.

A GPS receiver measures Position, Time, and Velocity. The velocity measurement is independent of the position measurement and is based on the Doppler.

Increasing GPS accuracy

Base station - a high performance GPS receiver placed in a fixed location whose position is accurately known.

The GPS measured position is compared sec by sec against the known position, and an error calculated.

This error is assumed to be the same error at the rover, and is sent to the rover as a ‘differential correction’.

Rover adds error to its measured position to obtain the corrected position Error data is sent to

rover with radio

Autonomous GPS = 2 metersDifferential GPS = 0.5 metersRTK (5 SVs) = 0.02 meters

Four or more satellites viewed by two receivers

GPS Operational GPS Satellites Current Satellites:

– 25 IIA/IIRs: 10 Final Clock* 2 will be decommissioned Spring 09

– 6 IIR-Ms: (L2C) Launch planned Mar 09, Aug 09 (with L5 enabled)

Future Satellites– GPS Block IIF (L5)

IIF-1 launch Oct 2009

– GPS III Launch 2014 24 satellites by ~2021

GPS Modernization Benefits

GPS IIR-M L2C (1227 MHz)– Improved L2 signal measurement – slight improvement to

IONO measurements GPS IIF L5 (1185 MHz)

– Improved RTK Acquisition– Improved DGPS accuracy

Higher chipping (10^7) Better ionosphere modeling

– Increased Power Level Improved operation under canopy Better SNRs

GPS III– L1C designed for interoperability with other systems

(Galileo, for example)

GPS Accuracy and Solar Cycle

RTK Performance with low and high Ionosphere disturbance

RTK Performance

0

2

4

6

8

10

12

14

16

18

20

0 5 10 15 20 25 30 35 40 45 50

Distance from Reference Station (Km)

2-D

Po

sit

ion

Ac

cu

rac

y (

cm

)

E-W vs. N-S Accuracy

Global Navigation Satellite System (GNSS)

GPS– Space Based Augmentation Systems (SBAS)

WAAS, EGNOS, MSAS, GAGAN, GRAS, CDGPS OmniSTAR, Starfire

GLONASS (Russia) QZSS (Japan) Compass (China) Galileo (EU)

Augmentation Systems for increased accuracy

Space Based Augmentation Systems (SBAS)– WAAS - Wide Area Augmentation System (US)– EGNOS - European Geo Stationary Navigation Overlay

System (EU)– MSAS - MTSAT Satellite-Based Augmentation System

(Japan) – GAGAN (GPS Aided GEO Augmented Navigation) India– GRAS (Ground Regional Augmentation) AUS– Canadian DGPS – OmniSTAR XP/HP– StarFire

Augmentation Systems for increased accuracy

Ground Based Augmentation Systems – NDGPS MF Beacons (sub-meter)– HA-NDGPS MF Beacons (4 sites are now

transmitting) 10-20 cm service (similar to OmniSTAR XP/HP)

– RTK Base Stations – local radio transmitters

– RTK VRS Networks – internet and cell phones Trimble Terrasat CORS (Continuously Operating Reference

Station)

U.S. GPS Augmentation Update Wide Area Augmentation System (WAAS)

– Expanding monitor stations into Canada and Mexico– Two SVs at 135 and 138 for North America– WAAS satellites provide L1 and L5 ranging– WAAS provides DGPS corrections including IONO

modeling

Nationwide Differential GPS (NDGPS) – DOT’s Research and Innovative Technology

Administration, funding of NDGPS is still a concern

European Geostationary Navigation Overlay Service (EGNOS)

Status– AOR-E (120) and IOR-W (126)

Initial Operations

– ARTEMIS (124) Testing

Recommended reading– EGNOS for Professionals web site WWW.ESA.INT

Benefits of Additional GNSS Availability

– More Satellites mean better availability in difficult environments (Land Leveling in the Mississippi Delta)

– Some system upgrades will have stronger signals

Reliability– More Satellites mean no outages even with

individual satellite failures

GLONASS – the Russian GPS

Currently (January 13, 2009) 16 Operational SVs

Goal is to have a full constellation of 24 SVs by 2010

GLONASS and RTK

Using GLONASS SVs with RTK will help– Initialization

Less than 5 GPS SVs - having some GLONASS SVs available will aid RTK initialization

– Positioning Less than 4 GPS SVs – having some GLONASS

SVs will aid positioning

– Improved VDOP Adding any GLONASS SVs will help to reduce

VDOP

Compass (Beidou)

4 geostationary (now in place) and 30 medium orbit (MEO) satellites for global coverage

MEO launches starting early 2009 Goal mid-2010 to have 10 SVs The Chinese Government has announced free 10

meter accuracy access to all, however, the ICD has not been published.

There is a high probability that Compass will become operational before Galileo

Galileo – EU GPS

Milestones– First SV launched 2005– Operational target 2013

Fee for service will compete with “Free GPS” Galileo will not be a factor in the Ag market for at

least 3 or 4 years Expect to see lots of “Galileo marketing” activity

for the next few years L1C to interoperate with GPS III SVs

Questions?

Art_Lange@Trimble.com

Jorge_Heraud@Trimble.com

WWW.Trimble.com