Truck & Off-Highway Engineering - August 2022 - 19

AUTONOMOUS FEATURE
Positioning to centimeter-level improves agriculture
Precision-navigation approaches that emphasize backward compatibility help
farms reap more value from autonomous operations.
by James Fennelly
P
recision navigation, which is essential to autonomous machines,
is knowing a moving vehicle's absolute and relative
position in 3D space accurately, reliably and repeatably. The
cost for precision navigation with position information down
to the centimeter level has become a far less significant barrier to
broad deployment. This price drop has come with enhanced, not diluted,
performance.
One reason for the cost decrease has to do with the sheer volume
of Global Navigation Satellite System (GNSS) receivers on the market.
GNSS encompasses the satellite-based GPS used in North
America as well as other global positioning systems such as GPS,
Galileo, Glonass, BeiDou, NAVIC (former IRNSS) and QZSS.
Because there are no lane markings, signs or HD map access in a
wheat field to guide a tractor, farmers often need to rely upon GNSS
satellite-provided guidance. However, traditional GNSS only provides
meter-level accuracy. This is where the use of Real Time Kinematics
(RTK) to enhance the accuracy of GNSS to the centimeter level comes
into play. Benefits from applying RTK to GNSS navigation include minimizing
seed waste through precise spacing between rows and even
TRUCK & OFF-HIGHWAY ENGINEERING
between seeds in the same row, more controlled fertilizer
application to prevent both over- and under-fertilization,
as well as minimizing equipment crop damage
during growing season operations and harvesting.
High-performance MEMS IMUs
RTK improves GNSS accuracy in a two-step process.
First, an RTK technique is used to measure the GNSS
carrier signal and so obtain precise time information.
Next, to further improve accuracy, RTK corrects the
measurement using data from a network of fixed
base stations.
Inertial navigation systems (INS) use GNSS and RTK
data to guide autonomous and semi-autonomous vehicles.
The main subsystem of an INS is an inertial measurement
unit (IMU), which measures acceleration and
rotational rate. It calculates velocity, relative position
Continued on page 22
August 2022 19
ACEINNA

Truck & Off-Highway Engineering - August 2022

Table of Contents for the Digital Edition of Truck & Off-Highway Engineering - August 2022

Truck & Off-Highway Engineering - August 2022 - Intro
Truck & Off-Highway Engineering - August 2022 - Sponsor
Truck & Off-Highway Engineering - August 2022 - CVRA
Truck & Off-Highway Engineering - August 2022 - CVRB
Truck & Off-Highway Engineering - August 2022 - CVR1
Truck & Off-Highway Engineering - August 2022 - CVR2
Truck & Off-Highway Engineering - August 2022 - 1
Truck & Off-Highway Engineering - August 2022 - 2
Truck & Off-Highway Engineering - August 2022 - 3
Truck & Off-Highway Engineering - August 2022 - 4
Truck & Off-Highway Engineering - August 2022 - 5
Truck & Off-Highway Engineering - August 2022 - 6
Truck & Off-Highway Engineering - August 2022 - 7
Truck & Off-Highway Engineering - August 2022 - 8
Truck & Off-Highway Engineering - August 2022 - 9
Truck & Off-Highway Engineering - August 2022 - 10
Truck & Off-Highway Engineering - August 2022 - 11
Truck & Off-Highway Engineering - August 2022 - 12
Truck & Off-Highway Engineering - August 2022 - 13
Truck & Off-Highway Engineering - August 2022 - 14
Truck & Off-Highway Engineering - August 2022 - 15
Truck & Off-Highway Engineering - August 2022 - 16
Truck & Off-Highway Engineering - August 2022 - 17
Truck & Off-Highway Engineering - August 2022 - 18
Truck & Off-Highway Engineering - August 2022 - 19
Truck & Off-Highway Engineering - August 2022 - 20
Truck & Off-Highway Engineering - August 2022 - 21
Truck & Off-Highway Engineering - August 2022 - 22
Truck & Off-Highway Engineering - August 2022 - 23
Truck & Off-Highway Engineering - August 2022 - 24
Truck & Off-Highway Engineering - August 2022 - 25
Truck & Off-Highway Engineering - August 2022 - 26
Truck & Off-Highway Engineering - August 2022 - 27
Truck & Off-Highway Engineering - August 2022 - 28
Truck & Off-Highway Engineering - August 2022 - 29
Truck & Off-Highway Engineering - August 2022 - 30
Truck & Off-Highway Engineering - August 2022 - 31
Truck & Off-Highway Engineering - August 2022 - 32
Truck & Off-Highway Engineering - August 2022 - 33
Truck & Off-Highway Engineering - August 2022 - 34
Truck & Off-Highway Engineering - August 2022 - CVR3
Truck & Off-Highway Engineering - August 2022 - CVR4
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