Vehicle guidance From horses to GPS
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Vehicle guidance From horses to GPS Jorge Heraud and Arthur Lange Trimble Navigation Ltd. June 2009
description
Vehicle guidance From horses to GPS. Jorge Heraud and Arthur Lange Trimble Navigation Ltd. June 2009. The greatest challenge. This generation of engineers and scientists will need to solve the toughest of problems ever encountered - PowerPoint PPT Presentation
Transcript of 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
