U.S. patent application number 10/400949 was filed with the patent office on 2003-10-02 for methods and apparatus for precision agriculture operations utilizing real time kinematic global positioning system systems.
Invention is credited to Keller, Russell J., Lange, Arthur F., Nichols, Mark E..
Application Number | 20030187560 10/400949 |
Document ID | / |
Family ID | 22366445 |
Filed Date | 2003-10-02 |
United States Patent
Application |
20030187560 |
Kind Code |
A1 |
Keller, Russell J. ; et
al. |
October 2, 2003 |
Methods and apparatus for precision agriculture operations
utilizing real time kinematic global positioning system systems
Abstract
Real time kinematic (RTK) global positioning system (GPS)
technology is integrated with precision farming methodologies to
provide highly accurate seeding, cultivating, planting and/or
harvesting operations. RTK GPS systems are used to control fully or
semi-autonomous vehicles in these operations and may allow for
precision planting of seeds (e.g., from a seeder equipped with an
RTK GPS receiver and related equipment) and/or precision weed
removal (e.g., using a vehicle fitted with weed eradication
mechanisms such as augers and/or herbicide sprayers). Crop specific
fertilizer/pesticide application is also enabled through the use of
centimeter-level accurate positioning techniques.
Inventors: |
Keller, Russell J.;
(Sunnyvale, CA) ; Nichols, Mark E.; (Sunnyvale,
CA) ; Lange, Arthur F.; (Sunnyvale, CA) |
Correspondence
Address: |
BLAKELY SOKOLOFF TAYLOR & ZAFMAN
12400 WILSHIRE BOULEVARD, SEVENTH FLOOR
LOS ANGELES
CA
90025
US
|
Family ID: |
22366445 |
Appl. No.: |
10/400949 |
Filed: |
March 26, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10400949 |
Mar 26, 2003 |
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09721372 |
Nov 22, 2000 |
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6553299 |
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09721372 |
Nov 22, 2000 |
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09116312 |
Jul 15, 1998 |
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6199000 |
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Current U.S.
Class: |
701/50 ; 172/2;
701/469 |
Current CPC
Class: |
Y02A 40/12 20180101;
Y10S 111/904 20130101; A01C 21/005 20130101; Y02A 40/10 20180101;
A01B 79/005 20130101; A01B 39/18 20130101 |
Class at
Publication: |
701/50 ; 701/213;
172/2 |
International
Class: |
G06F 019/00 |
Claims
What is claimed is:
1. A vehicle, comprising: a precise positioning apparatus
configured to provide real-time precise positioning information
regarding the location of the vehicle; and a sensor-controller
apparatus configured to detect a target at least in part according
to the location of the vehicle.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to improvements in precision
farming methodologies through the use of highly accurate
positioning information systems.
BACKGROUND
[0002] In modern agricultural industries, accuracy is essential.
Accurate record keeping, automated mapping, and precision farming
techniques have all become crucial factors in the challenge to
improve overall crops yields and comply with the ever increasing
number of environmental regulations. The accurate application of
herbicides, pesticides and fertilizers is an essential component of
modem precision farming methodologies. Whether such applications
are performed by aerial or terrestrial techniques, advanced tools
that provide highly accurate navigation and guidance information
for operators have become a requirement.
[0003] The transfer of global positioning system (GPS) technologies
to civilian industry has greatly assisted in meeting the challenges
presented by today's precision agricultural needs. Using GPS
systems, accurate and highly reliable satellite-based positioning
information, which typically achieves meter-level accuracy by
utilizing differential GPS (DGPS) position corrections transmitted
from fixed base stations, is provided to operators, for example
though moving map displays. Such information allows for navigation
and guidance of farm implements and systems utilizing DGPS
technology have been used to assist in the aerial and terrestrial
application of fertilizers, herbicides and pesticides, etc.
However, such systems have generally been limited in their
capabilities.
[0004] Moreover, even though these limited precision agricultural
methodologies have become popular with the commercialization of GPS
systems, to date such methodologies have not included the use of
real time kinematic (RTK) GPS equipment which allows for
centimeter-level accuracy.
SUMMARY OF INVENTION
[0005] In one embodiment, an apparatus which includes a
sensor-controller arrangement configured to identify a target
according to a sensor input and a position input is provided. The
apparatus may be self-propelled (in which case it may include its
own propulsion unit) or it may be arranged for towing, for example,
by a tractor. In either case, the target may be plant growth (e.g.,
weeds, crops, etc.).
[0006] Preferably, the position input is provided by a global
positioning system (GPS) receiver, for example, a real time
kinematic (RTK) GPS receiver. The sensor input may be provided by a
chlorophyll detector, a video camera and/or an infra-red
detector.
[0007] The apparatus may also include a plant eradication
mechanism, for example a herbicide sprayer and/or an auger. Where
self-propelled, the apparatus may include a collision avoidance
sensor (e.g., an ultrasonic or infra-red detector) coupled to the
sensor-controller arrangement.
[0008] In general, the sensor-controller arrangement includes a
decision-making unit coupled to receive the sensor input and the
position input. The decision-making unit (e.g., a general purpose
or special purpose microprocessor) is configured to use these
inputs, along with reference position information, to classify the
target (e.g., as a weed, a crop plant or otherwise). The reference
position information may be obtained from a digitized map of an
area of operation for the apparatus, for example, which may be
stored in memory accessible by the decision-making unit.
Preferably, the digitized map will include information defining
desired plant growth regions so as to aid in classifying the target
as desired plant growth (e.g., crops) or otherwise (e.g.,
weeds).
[0009] When undesired plant growth is detected, the sprayer
apparatus may be used, for example with control signals from the
sensor-controller arrangement, to apply a herbicide thereto.
Alternatively, or in addition thereto, the auger may be used, again
under the control of the sensor-controller arrangement, to uproot
the undesired plant growth. In some cases, the sprayer apparatus
may be configured to dispense a fertilizer and/or a pesticide in
addition to (or instead of) the herbicide. Thus, while eliminating
undesired plant growth, the apparatus may also be used to fertilize
desired plant growth and/or apply pesticides to selected areas to
control pests.
[0010] In a further embodiment, a vehicle which includes a precise
positioning apparatus, for example a real-time kinematic global
positioning system receiver, configured to provide real-time
precise positioning information regarding the location of the
vehicle; and a sensor-controller apparatus configured to detect a
target, at least in part, according to the location of the vehicle
is provided. A propulsion unit may be included and such a
propulsion unit may be configured to transport the vehicle under
the control of the sensor-controller apparatus. Collision avoidance
sensors may be coupled to the sensor-controller apparatus to
provide for obstacle detection and/or avoidance. In general, the
sensor-controller apparatus includes a sensor package configured to
detect a characteristic of the target (e.g., chlorophyll, for the
case where the target is undesired plant growth) and a
decision-making apparatus coupled thereto. The decision-making
apparatus is configured to combine inputs from the sensor package,
the precise positioning apparatus and a digital map of an operating
area in which the vehicle operates to produce a decision output. An
actuator within the vehicle is configured to respond to the
decision output of the decision-making apparatus. In one particular
embodiment, the actuator comprises weed removal means which may
include a herbicide deploying mechanisms and/or an auger. In
another particular embodiment, the actuator comprises lane marker
depositing means which may be used to place lane markers on a
roadway.
[0011] In still further embodiments, seeding methodologies are
provided. In one particular example, a first seeding line may be
predefined or may be defined by user during seeding operations. A
second seeding line is then computed using positioning data
obtained while following the first seeding line and a swathing
offset corresponding to the width of a seeding pattern. The second
seeding line may be updated according to one or more deviations
from its computed path.
[0012] The deviations may correspond to operator inputted
corrections which allow for obstacle avoidance, etc. The updating
generally occurs as users follow the second seeding line as defined
by the positioning data and the swathing offset and then deviate
from the second seeding line to accommodate one or more terrain
features. New GPS data is collected during these steps of following
and deviating from the second seeding line (as computed) and new
positions are computed from the new GPS data. Finally, the updated
second seeding line is redefined using the new positions computed
from the new GPS data and a further seeding line may then be
defined using the updated second seeding line information and the
swathing offset.
[0013] In another alternative embodiment, a seeder which includes a
vehicle fitted with an RTK GPS receiver configured to receive GPS
data and RTK GPS correction information and to compute position
information therefrom is provided. The seeder may include a
processor configured to receive the position information and to
compute seeding line information therefrom. The processor may be
part of the GPS receiver or it may be a separate unit. The
processor is also configured to update the seeding line information
in response to seeding line deviation information. The seeding line
deviation information may come, for example, from operator inputted
corrections to accommodate various terrain features. The seeder may
also include a display device configured to receive and display the
seeding information. The display device may include a moving map
display and/or a light bar display, either or both of which allow
an operator to follow a computed seeding line path.
[0014] Other features and advantages of various embodiments of the
present invention will be evident from the detailed description
which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Exemplary embodiments of the present invention are
illustrated by way of example, and not limitation, in the Figures
of the accompanying drawings in which:
[0016] FIG. 1 illustrates a geographic information system data
structure as may be used by various embodiments of the present
invention;
[0017] FIG. 2A illustrates a crop seeding operation which may be
performed in accordance with an exemplary embodiment of the present
invention;
[0018] FIG. 2B illustrates a seeding apparatus configured in
accordance with the methods and apparatus of the present
invention;
[0019] FIG. 3 illustrates functional components of a seeder
configured in accordance with one embodiment of the present
invention;
[0020] FIG. 4 illustrates actuator components of a seeder
configured in accordance with a further embodiment of the present
invention;
[0021] FIG. 5 illustrates yet another embodiment of a seeder
apparatus;
[0022] FIG. 6 illustrates various operator controls and components
for a seeder configured in accordance with an embodiment of the
present invention;
[0023] FIG. 7 is a flow diagram illustrating one exemplary manner
of performing crop seeding according to one embodiment of the
present invention;
[0024] FIG. 8 illustrates exemplary seeding operations on sloping
terrain;
[0025] FIG. 9A illustrates micro crop rotation methodologies which
are possible using seeding operations performed in accordance with
an embodiment of the present invention;
[0026] FIG. 9B illustrates an autonomous vehicle operating in
accordance with one embodiment of the present invention;
[0027] FIGS. 10A-10C illustrates the autonomous vehicle shown in
FIG. 9 in more detail;
[0028] FIGS. 11a-11f illustrate a weed destruction operation
performed in accordance with one embodiment of the present
invention;
[0029] FIG. 12 is a block diagram representing one embodiment of an
autonomous vehicle control system;
[0030] FIG. 13 illustrates an optional override feature for use
with the autonomous vehicle control system of FIG. 12;
[0031] FIG. 14 is a flow diagram illustrating a method of removing
weeds in accordance with one embodiment of the present
invention;
[0032] FIG. 15 illustrates a lane marker apparatus configured in
accordance with a further embodiment of the present invention;
[0033] FIG. 16 illustrates the lane marker apparatus of FIG. 15 in
more detail;
[0034] FIG. 17 illustrates a process of applying lane markers in
accordance with one embodiment of the present invention;
[0035] FIG. 18 illustrates a semi-autonomous vehicle configured in
accordance with yet another embodiment of the present invention;
and
[0036] FIG. 19 is a side view of the semi-autonomous vehicle shown
in FIG. 18.
DETAILED DESCRIPTION
[0037] The precision agriculture systems and methodologies
described below may find application in crop spraying operations,
harvesting operations, ploughing operations, planting/seeding
operations, mining operations, mineral prospecting, or other
applications where real-time correction information is provided to
allow highly accurate positioning determinations to be made.
Moreover, although the various methods and apparatus will be
described with particular reference to GPS satellites, it should be
appreciated that the teachings are equally applicable to systems
which utilize pseudolites or a combination of satellites and
pseudolites. Pseudolites are ground- or near ground-based
transmitters which broadcast a pseudorandom (PRN) code (similar to
a GPS signal) modulated on an L-band (or other frequency) carrier
signal, generally synchronized with GPS time. Each transmitter may
be assigned a unique PRN code so as to permit identification by a
remote receiver. Pseudolites are useful in situations where GPS
signals from an orbiting satellite might be unavailable, such as
tunnels, mines, buildings or other enclosed areas or in areas of
significant foliage. The term "satellite", as used herein, is
intended to include pseudolites or equivalents of pseudolites, and
the term GPS signals, as used herein, is intended to include
GPS-like signals from pseudolites or equivalents of
pseudolites.
[0038] It should be further appreciated that the methods and
apparatus of the present invention are equally applicable for use
with the GLONASS and other satellite-based positioning systems. The
GLONASS system differs from the GPS system in that the emissions
from different satellites are differentiated from one another by
utilizing slightly different carrier frequencies, rather than
utilizing different pseudorandom codes. As used herein and in the
claims which follow, the term GPS should be read as indicating the
United States Global Positioning System as well as the GLONASS
system and other satellite- and/or pseudolite-based positioning
systems.
[0039] In addition, the precision agriculture methodologies and
accompanying methods and apparatus described herein may be
supplemented with non-satellite based guidance systems, such as
inertial navigation systems, distance and gyro compass and/or other
heading and/or attitude indicator systems (e.g.,
accelerometer-based yaw, pitch and/or roll sensors), laser range
finding and bearing indicator systems, etc. The use of such systems
to assist in terrestrial navigation is well known in the art and
will not be described further so as not to unnecessarily obscure
the following discussion. It should be recognized that such systems
could supplement (at least to some degree) the GPS-based systems
described in detail below and would be particularly useful, for
example, in situations where satellite-based positioning signals
are unavailable (e.g., under foliage, behind hills or buildings, in
valleys, mines, etc.).
[0040] In part, the various methods and apparatus described below
may make use of or assist in the construction of a geographic
information system (GIS). A GIS is a system of hardware, software
and geographic data designed to support the capture, management,
manipulation, analysis, modeling and display of spatially
referenced data for solving complex planning and management
problems. One purpose of a GIS can be to find or assist in finding
solutions to problems by using both geographic and tabular data. To
illustrate, shown in FIG. 1 is an exemplary GIS 2 (which may exist
as a data structure stored on/in any suitable computer-readable
medium, for example, volatile or non-volatile memory, magnetic
tape, other magnetic media, electro-optical recording media, or any
other suitable media) which includes information relating to
various soil types and/or conditions, ownership (e.g., property
boundaries), roads, streams, elevations, fields, and other field
and/or crop data, all of which may be overlaid on a base map 5 of
an agricultural field of interest. It should be appreciated that
GIS 2 may reside on or be accessible via a server that is capable
of being accessed by a number of clients (e.g., via one or more
computer networks and/or the internet). The information provided by
GIS 2 in the course of various precision farming operations may be
utilized by one or more RTK GPS systems. In this way, a user will
have information regarding the application of the various chemicals
(e.g., herbicides, pesticides and/or fertilizers) at points of
interest on the field, the planting of crops at precise locations
(e.g., with respect to irrigation sources and/or for highly
accurate (e.g., centimeter-level) crop rotation within a field),
etc. This may assist farmers and others who rely on this
information (or on information which can be extrapolated therefrom,
e.g., expected crop yields) in various precision agricultural
operations as will be discussed in detail below. Alternatively or
in addition, the information provided by GIS 2 may be uploaded to
higher level GIS data structures for use in strategic planning
operations regarding large areas of crop growth.
[0041] FIG. 2A illustrates a planting or seeding operation which
may be performed in accordance with the methods described herein in
an agricultural field 10 or other area of interest. As used herein,
the terms seeding and/or planting are meant to describe any
deposition of plant material, including seeds, seedlings, bulbs,
etc. in soil or other mediums. Similarly, the term seed as used
herein is meant to describe or refer to seeds, bulbs, seedlings
and/or other plant material. The seeding operation is shown to
illustrate one use of an RTK GPS receiver in the development of a
digital map of the agricultural field 10. The map defined through
this operation may become the base map 5 or other overlay of GIS 2
and/or may become a control feature for a machine guidance and/or
control system to be discussed in further detail below.
Conceptually, the development of a digital map may occur through
any of a number of means. For example, the map could be established
using satellite, aircraft or other overhead imagery wherein a
detailed representation of a portion of the surface of the earth,
or other planetary body for that matter, is photographed at high
resolution. The photographs may then be digitized to produce the
map.
[0042] Alternatively, the area could be transited by a fully or
semi-autonomous vehicle, similar to that described below, and
position data recorded using an RTK GPS apparatus and a suitable
feature collection system such as the Aspen GIS data capture system
available from Trimble Navigation, Ltd. of Sunnyvale, Calif. Still
further, a combination of these methods may be used to produce the
digital map. However produced, the map should be of sufficient
resolution so that the precise location of a vehicle within the
area defined by the map can be determined to a few centimeters with
reference to the map. Currently available RTK GPS receivers, for
example as produced by Trimble Navigation, Ltd., are capable of
such operations.
[0043] For the operation shown in FIG. 2, a tractor or other
vehicle 100 is used to tow a seeder 102 across field 10. Seeder 102
is fitted with an RTK GPS receiver 104 which receives transmissions
from GPS satellites 106 and an RTK reference station (not shown).
Also on-board seeder 102 (although not shown in detail) is a
monitoring apparatus which records the position of seeds 20 as they
are planted by seeder 102. In other words, using precise
positioning information provided by the RTK GPS receiver 104 and an
input provided by seeder 102, the monitoring apparatus records the
location at which each seed is deposited by seeder 102 in field
10.
[0044] As tractor 100 proceeds across field 10, for example to
plant various rows of seeds or crops, a digital map is established
wherein the location of each seed planted in field 10 is stored.
Such a map or other data structure which provides similar
information may be produced on-the-fly as seeding operations are
taking place. Alternatively, the map may make use of a previously
developed map (e.g., one or more maps of GIS 2 produced from
earlier seeding operations, etc., or from satellite imagery). In
such a case, the previously stored map may be updated to reflect
the position of the newly planted seeds. Indeed, in one embodiment
GIS 2 is used to determine the proper location for the planting of
the seeds/crops.
[0045] In such an embodiment, relevant information stored in GIS 2,
for example the location of irrigation systems and/or the previous
planting locations of other crops, may be used to determine the
location at which the new crops/seeds should be planted. This
information is provided to seeder 102 (e.g., in the form of radio
telemetry data, stored data, etc.) and is used to control the
seeding operation. As seeder 102 (e.g., using a conventional
general purpose programmable microprocessor executing suitable
software or a dedicated system located thereon) recognizes that a
planting point is reached (e.g., as the seeder 102 passes over a
position in field 10 where it has been determined that a seed/crop
should be planted), an onboard control system activates a seed
planting mechanism to deposit the seed (e.g., through an air nozzle
or other planting means). The determination as to when to make this
planting is made according to a comparison of the seeder's present
position as provided by RTK GPS receiver 104 and the seeding
information from GIS 2. For example, the GIS information may
accessible through an index which is determined according to the
seeder's current position (i.e., a position-dependent data
structure). Thus, given the seeder's current location, a look-up
table or other data structure can be accessed to determine whether
a seed should be planted or not.
[0046] In cases where the seeding operation is used to establish
the digital map, the seeding data need not be recorded locally at
seeder 102. Instead, the data may be transmitted from seeder 102 to
some remote recording facility (e.g., a farmhouse or other central
or remote workstation location) at which the data may be recorded
on suitable media. The overall goal, at the end of the seeding
operation, is to have a digital map which includes the precise
position (e.g., to within a few centimeters) of the location of
each seed or other item planted. As indicated, mapping with the
GPS-RTK technology is one means of obtaining the desired degree of
accuracy.
[0047] An alternative seeding method which makes use of multiple
seeding units is illustrated in FIG. 2B. In this embodiment,
tractor 100 tows an implement 108 which includes multiple seeder
units 109. Each seeder unit (or a number of the seeder units) 109
is fitted with one RTK GPS receiver 104 (or each or some of the
seeder units may be fitted with an antenna and each of the antennas
multiplexed with a single or a number of RTK GPS receivers). By
utilizing multiple antennas and/or RTK GPS receivers in this
fashion, the attitude of implement 108, as well as its heading,
speed and location, may be determined. Indeed, attitude in any of
the yaw, pitch or roll axes may be determined. In other
embodiments, roll, pitch and/or yaw sensors which make use of
accelerometers or other similar devices may be employed in lieu of
or in addition to the multiple antenna and/or receivers. Using the
attitude information, along with the location and other
position/speed information, one may determine (with
centimeter-level accuracy) the positions 20 at which seeds are
planted from each of the seeder units 109. Each of the seeder units
may be configured as described below.
[0048] More particularly, the attitude of implement 108 may be
computed by comparing the position solutions produced by each of
the RTK GPS receivers 104. For example, if the position solutions
indicate that some of the seeder units 109 are ahead of others (as
measured in the direction of travel of implement 108), this would
indicate a rotation of implement 108 about its yaw axis. If seeder
units 109 at one end of implement 108 were above or below seeder
units 109 at the other end of implement 108, this would indicate
rotation of implement 108 about its roll axis. For the linear
arrangement of seeder units 109 shown in FIG. 2B significant pitch
would not be expected, however, such could be measured in other
embodiments (e.g., where seeder units 109 were staggered about a
center-line of implement 108 along its length or where seeder units
109 were arranged in a two-dimensional array, etc.). Also, hogging
and/or sagging of seeder units 109 in the middle portion along the
length of implement 108 could also be measured. Each of these
measurements may provide increased accuracy in determining the
resulting seeding pattern.
[0049] FIG. 3 is a functional illustration of a seeding apparatus
which may be used to plant seeds and/or crops, etc. at precise
locations according to information from GIS 2 in further detail.
Seeder 110 is generally provided as a vehicle fitted with a GPS
receiver 112 configured to receive GPS data and GPS correction
information (i.e., RTK GPS information) and to compute position
information therefrom. A processor 114 (which may be part of the
GPS receiver or a separate unit) or other decision-making unit is
configured to receive the position information from GPS receiver
112 and seeding information from a seeding information data
structure 113 (e.g., as may be stored in memory). Seeding
information data structure 113 may be GIS 2 or a portion thereof
and may be stored locally at seeder 110 as discussed above
(although it need not be, e.g., where the seeding information is
relayed via radio or other link). Further, if the seeding
information is stored locally at seeder 102, it need not be in the
form of the complete GIS 2. Instead, it may merely be organized as
a data structure which includes the positions at which seeds/crops
are to be planted (e.g., a conventional look-up table arrangement).
Further, the processor 114 may be configured to update the GIS
seeding information with more accurate actual planting
locations.
[0050] Seeder 110 also includes a seeding operation control system
115. In response to control signals from processor 114, the seeding
operation control system 115 deposits seeds/crops, etc. FIG. 4
illustrates one exemplary embodiment of seeding operation control
system 115 in more detail. In response to a control signal from
processor 114 (or receiver 112 where no separate processor 114 is
used), actuator 116 operates nozzle (air or water) 118 to deposit
one or more seeds 119 in field 10. A supply of seeds 119 will be
available onboard seeder 110 and nozzle 118 is configured to eject
seed 119 with sufficient velocity to become planted in field 10
(e.g., in a small furrow tilled by a preceding blade or similar
instrument) in response to a signal from actuator 116. This may be
an electrical and/or mechanical signal. Actuator 116 may return a
seeding signal to processor 114 to indicate that a seed has been
planted, thus allowing processor 114 to update seeding information
data structure 113 as appropriate.
[0051] Also shown in FIG. 4 is optional ultrasonic sensor 120.
Ultrasonic sensor 120 may be positioned ahead of nozzle 118 in the
direction of travel of seeder 110. As seeder 110 passes over field
10, ultrasonic sensor 120 may provide processor 114 with ground
profile information (i.e., height above ground). In this way,
processor 114 can time the release of seed 119 appropriately, for
example to compensate for undulating terrain. In this way, seed 119
can be planted as closely as possible to the desired location
therefor as specified in seeding information data structure
113.
[0052] As shown in FIG. 5, seeder 110 may be configured as a boom
122 which allows delivery of seeds to a variety of locations during
a single pass through field 10. The seeds may be stored in a tank
assembly 124 and delivered through nozzles 126 which are present in
boom assembly 122. Various controls in the cab of tractor 128 which
tows seeder 110 allow an operator to control seeder 110 and its
related equipment.
[0053] Boom 122 may be fitted with one or more GPS antennas 130
which receive GPS data from one or more GPS satellites 106. GPS
receiver 112 is capable of interpreting the GPS data received
through antennas 130 so as to provide position/guidance
information. GPS antennas 130 are mounted on seeder 110 so as to
have a clear view of the sky. This will ensure that antennas 130
are capable of capturing signals from GPS satellites 106. Multiple
antennas (e.g., two or more) may also be used to determine attitude
in one or more dimensions, as may be desirable. Methods for
determining attitude using multiple antennas are disclosed in U.S.
Pat. Nos. 5,268,695 and 5,296,861, each of which are incorporated
by reference herein in their entireties. Signals from antennas 130
are provided to GPS receiver 112 which may be mounted inside seeder
110 or at another convenient location such as on/in tractor 128.
Boom 122 attitude is easily determined in the vertical plane of the
boom. Additional antennas can be mounted at the center of boom 122
or on tractor 128 to aid in determining heading, as discussed in
the above-referenced patents.
[0054] Receiver 112 may also receive RTK GPS information through
antenna 132 from an RTK base station (not shown). GPS receiver 112
uses the GPS data provided through antennas 130 from the GPS
satellites 106 and the RTK GPS information received through antenna
132 to compute position information for seeder 110. The position
information corresponds to the terrestrial location of seeder 110
at the time the GPS data is collected. Such position computations
may occur periodically, for example, several times each second.
Using RTK GPS correction techniques common in the art,
centimeter-level position accuracy may be obtained.
[0055] Now referring to FIG. 6, some of the operator controls
mentioned above are shown in further detail. The position
information computed by GPS receiver 112 may be processed and
provided to a display device 140. Display device 140 may include a
moving map display 142 which allows an operator to determine the
precise location of seeder 110 with respect to the boundaries of
field 10. As illustrated, field 10 has some irregular boundaries
and the intersection of cross-hairs 144 and 146 define the position
of seeder 110 within field 10. The process for generating such
moving map display information is well known in the art and need
not be described further. Also included on display device 140 may
be a compass rose or heading indicator 148. Heading indicator 148
generally indicates the direction that seeder 110 is traveling.
Through the use of moving map display 142 and heading indicator
148, an operator is provided with simple and effective information
to control seeding operations within field 10.
[0056] In addition to the above, a multi-function light bar 150 may
be included within tractor 122. The multi-function light bar 150
receives guidance information from GPS receiver 112 or processor
114 and provides clear and immediate guidance information/commands
to an operator of tractor 122 through a row of light emitting
diodes (LEDs). These LEDs are used to alert an operator when seeder
110 has deviated from a computed seeding path (e.g., which may be
derived from the desired seeding pattern stored as part of GIS 2 or
may be derived from user manipulation of other data stored in GIS
2). The sensitively of light bar 150 (i.e., the deviation required
before an LED will be illuminated to indicate that seeder 110 is
straying from the computed path) may be operator configured for
various types of seeding operations and field conditions. In
addition, the light bar 150 may have a text screen (not shown) to
display user selected information such as the tractor speed, etc.
In other embodiments, multi-function light bar 150 may be replaced
by a liquid crystal or other display device configured to provide
similar course guidance and/or correction information.
[0057] During seeding operations, LED 152 will be lit when seeder
110 is following a computed seeding path as described below. As
seeder 110 deviates from the computed seeding path, offset
indicator LEDs 154, 156, etc. will be lit to indicate the degree
(or distance) of deviation from the computed path. Note that LEDs
154, 156, etc. will be lit if seeder 110 deviates to the right of
the computed path and corresponding LEDs on the other side of LED
152 will be lit if seeder 110 deviates to the left of the computed
path. Alternatively, LEDs 154, 156, etc. may be lit to indicate
that seeder 110 should be steered to the right to get back to a
computed seeding line path, etc. The times at which the LEDs will
be lit may be user configured. For example, LED 154 may be lit when
seeder 110 has deviated by two to three feet from the computed
seeding path. Then, if seeder 110 continues to deviate, for example
to five feet from the computed seeding line path, LED 156 may be
lit. In other situations, LED 154 may not be lit until a five foot
deviation has been recognized. In this way, the user is provided
with information which allows him or her to correct the path of
seeder 110 back to that of the computed seeding path.
[0058] Operator corrections and steering controls are input through
steering wheel 160. The tractor 122 may be configured with a
steering input option which allows steering commands to be
transmitted from a steering apparatus 162 to GPS receiver 112 or
processor 114. Steering apparatus 162 provides information
regarding the steering inputs through steering wheel 160 so that
GPS receiver 112/processor 114 can be provided with real-time
update information (e.g., the above-described deviations). Using
the various steering commands provided through steering input
apparatus 162, GPS receiver 112/processor 114 can provide
appropriate display information to display device 140 and light bar
150. In other embodiments, other heading sensors such as a gyro
compass or flux-rate gyro compass may provide the update
information to GPS receiver 122. For the case where no steering
information is used, the tractor 122 may rely on updated position
information derived from GPS data received from the GPS satellites
to compute and provide the display information.
[0059] FIG. 7 illustrates a general computation scheme which may be
utilized by GPS receiver 112 (or processor 114) in accordance with
the present invention. Seeding process 170 starts at step 172 when
an operator begins the pass through filed 10. From step 172 the
process moves to step 174 where an operator defines the seeding
line. This may be done as seeder 110 is driven across field 10
using GPS receiver 112 to collect and store position information or
by down loading a previously computed seeding map (e.g., which may
be part of GIS 2). In one embodiment, the operator defines the
first seeding line by driving across field 10 (or at least over
that portion of field 10 that is to be seeded), for example
following a fence line, a crop boundary line or a natural contour
in the land, at step 176. This process finishes at step 178 when
the first seeding line path has been completed. During this
process, GPS data is collected at a variety of geographic locations
at step 180. Then, at step 182, the GPS data collection ends when
the first seeding line has been completed.
[0060] Data collection during the definition of the first seeding
line may occur as seeder 110 is driven across field 10, with GPS
data being collected at a number of points. The distance between
these GPS data collection points is variable and will typically
correspond to sub-meter, even centimeter, distances. The GPS data
collected at each point is processed along with the RTK GPS
information and a series of terrestrial positions are computed.
These positions (when linked together, e.g., by a straight or
curved line approximation) will define the first seeding line--that
is, the path followed by seeder 110 as it maneuvered across field
10. In this way, GPS receiver 112, or processor 114, computes a
first seeding line which corresponds to the actual path traveled by
seeder 110.
[0061] If additional seeds are to be planted, a decision made at
step 184, GPS receiver 112 (or processor 114) may compute a new
seeding line (or swath) to be followed, based on the GPS data
collected while seeder 110 traversed across the first seeding path
(step 186). An offset due to, for example, the effective seeding
width (W) of boom assembly 122 is also taken into account so that
portions of field 10 are not seeded a second time. The computed new
seeding line may be used to generate guidance information for the
operator of seeder 110. For example, as the operator turns seeder
110 around to follow a return path across field 10 (step 188), the
actual position of seeder 110 (as determined by new GPS position
information received by GPS receiver 112) is compared with its
expected position (i.e., the second seeding line information
computed as described above). If the actual position agrees with
the expected position, the operator is so advised, for example by
the illumination of LED 152 in light bar 150. This continues as
seeder 110 is driven back across field 10 with new GPS data being
constantly collected and the actual position of seeder 110 being
constantly checked against its expected position. As deviations
from the expected positions are noted, display information is
provided to the operator to allow guidance corrections as discussed
above (step 190).
[0062] During the next seeding line, the operator follows the
guidance information computed by GPS receiver 112/processor 114 and
displayed on moving map display 142 and heading indicator 148 and
also on light bar 150. During this time, the operator may input
corrections for obstacle avoidance or terrain features using
steering wheel 160 or another steering control. Ultimately, the
operator will finish the second seeding line at step 192.
[0063] While following the guidance information provided by GPS
receiver 112, new GPS data is collected at step 194. The new GPS
data will be used to provide guidance information as described
above and will also form the basis for computing any subsequent
seeding line as was the case where the GPS data collected while
following first seeding line was used to compute the second seeding
line. GPS data collection for the second seeding line ends at step
126. Notice that the subsequent seeding line is computed based on
the actual path traveled by seeder 110 and not just the expected
path computed after the first seeding line was completed. Thus, any
deviations of seeder 110 from the computed second seeding line,
which were required due to the presence of rocks, trees, etc., will
be reflected in the new GPS data and the subsequent seeding line
will take into account these corrections.
[0064] If a subsequent seeding line is to be planted, a decision
made at step 198, guidance information for that seeding line is
computed at step 200, with offset information being applied as
before. These processes continue until the seeding operations for
field 10 are completed at step 202 at which time process 170 quits
at step 204. Notice that a decision process at step 202 allows an
operator to indicate that a current set of seeding lines have been
completed but that the complete set of operations for the field
have not been completed. This situation may arise, for example,
where different crops are situated in the same field or where a new
crop is being planted. In such cases, the operator may indicate
that a new set of seeding lines (corresponding to the new
conditions) should be initiated, beginning at step 172. In some
cases, process 170 may be configured so that only deviations
greater than a specified distance from an intended track are
recognized. That is, only significant deviations from a computed
seeding line guidance path (e.g., the second seeding line discussed
above) will be used as decision points for displaying guidance
correction information to the user.
[0065] Up to this point it has been assumed that the field in which
the seeder 110 operates is relatively flat. However, in those
situations where seeder 110 will operate over sloping terrain,
certain corrections must be accounted for. In particular, it will
be appreciated that when seeder 110 is operating on a hillside or
other sloping terrain, the boom assembly 122 will have an
effectively shorter horizontal seeding (or swath) width (W) than it
would have when seeder 110 operates on essentially flat terrain.
Indeed, the effective horizontal seeding width of the boom assembly
122 may be approximately equal to the physical length of the boom
assembly multiplied by the cosine of the angle of the slope of the
terrain (assuming the seeding nozzles do not direct seeds
significantly beyond the ends of the boom assembly 122). That
is,
effective horizontal swath width=physical swath
width.multidot.cos.O slashed.,
[0066] where .O slashed.=slope of the terrain.
[0067] This situation is illustrated in FIG. 8 which shows a first
seeding path 250 over a hillside 252. During seeding operations,
seeder. 110 traveled along the first seeding line 250 and reached a
position 254 defined by coordinates x.sub.1, y.sub.1, z.sub.1. Now
on the return path, seeder 110 needs to be guided to a position 256
which is offset from position 254 by the effective seeding swath
distance. Position 256 is defined by coordinates x.sub.2, y.sub.2,
z.sub.2 and, assuming that y.sub.1y.sub.2, then
x.sub.2swath
distance.multidot.cos[tan.sup.-1((z2-z1)/(x2-x1))].
[0068] GPS receiver 112/processor 114 will have computed x.sub.1
and z.sub.1 while seeder 110 was traveling along form line 250.
Further, positions x.sub.2 and z.sub.2 will be computed from GPS
data received while seeder 110 is traveling along the second form
line 260. It will be appreciated that by the time seeder 110
reaches position 256 and computes x.sub.2 and z.sub.2, seeder 110
may have actually passed position 256. Thus, the guidance
information may be late. However, because GPS receiver 112 computes
new positioning data several times each second, the distance
traveled by seeder 110 will be insignificant. In addition, guidance
smoothing and predictive filters (e.g., Kalman filters) can be
employed to reduce the effects of this lag time between the receipt
of new GPS data and the calculation of guidance information.
[0069] In alternative embodiments, where seeder 110 is equipped
with GPS antennas 130 at either end of boom assembly 122 GPS
receiver 112 may compute the elevations of each end of the boom
assembly 112, and thereby derive the slope of the terrain (i.e.,
the angle .O slashed.). This information could then be used to
compute the effective horizontal swath width as described above,
eliminating the need for guidance and predictive filters as may be
required in a single antenna situation. This concept may be
expanded to equip seeder 110 with three antennas, two on boom
assembly 122 and one positioned (for example) on the cab of tractor
128, to allow the computation of three elevation parameters. This
may be useful for undulating terrain where not only horizontal
slope (i.e., roll), but also longitudinal slope (i.e., pitch) must
be accounted for.
[0070] A further embodiment may equip seeder 110 as described in
U.S. Pat. No. 5,268,695 to Dentinger et al. (the "'695 patent"),
assigned to the Assignee of the present invention. The '695 patent
describes methods and apparatus for differential phase measurement
through antenna multiplexing and the entire disclosure is
incorporated herein by reference. In one embodiment, multiple GPS
antennas are connected to a GPS receiver so that a carrier signal
received by the antennas is time multiplexed through a single
hardware path to the receiver where a reference oscillator is used
to compare the phase of the signal from each antenna to the phase
of a reference signal. One of the antennas is designated as the
reference antenna and the carrier signal received by the reference
antenna is used to phase lock the reference signal generated by the
reference oscillator. The phase of the same carrier signal received
by the other antennas is periodically compared to the phase of the
reference signal and each comparison results in a single phase
angle measurement for the respective antennas compared to the
reference antenna. The computed phase angle measurements allow for
the calculation of the angle of inclination of a plane in which the
multiple antennas are situated. Thus, using such a system, the
angle of inclination of the boom assembly 122 could be computed
and, hence, the effective horizontal swath distance derived.
[0071] As part of the above-described seeding operations, the use
of RTK GPS technology as described herein may provide means for
micro crop rotation. Micro crop rotation, as the term implies,
refers to the rotation of the position of crop plant position
within a small area of field. In one particular embodiment, as
shown in FIG. 9A, the digital map may be subdivided into a number
of crop rotation zones 265. Within each crop rotation zone 265, one
plant 268 is planted per planting period (e.g., semi-annually,
annually, etc.) and the position of the plant 268 within the crop
rotation zone 265 is varied from planting period to planting
period. FIG. 9A illustrates an exemplary rotation scheme for five
planting periods.
[0072] By shifting the actual position at which the plants 268 are
planted witin the crop rotation zones 265, the methodologies
described herein help to ensure that these plants will grow in
fertile soil. The crop rotation scheme is carried out at the
centimeter-accurate level and adjoining crop rotation zones 265 may
have different rotation patterns to improve plant separations and
allow the crops to grow unmolested by one another. Micro crop
rotation at this level also helps to reduce the fallow time
required to leave a field dormant.
[0073] FIG. 9B now illustrates how the digital map 270 created
during the above-described planting operations (or otherwise
available from GIS 2 or a similar data structure) may be used by a
vehicle 300 to locate and destroy undesired plant growth (e.g.,
weeds) within field 10. Digital map 270 is illustrated as a virtual
representation of field 10 and it should be appreciated that this
illustration represents data that may be stored in a memory or
other computer readable medium. The digital map 270 may also
provide guidance information for the fully autonomous vehicle
described below by providing a preprogrammed route or pattern
(e.g., stored in memory on-board the vehicle). This route or
pattern may be a series of GPS coordinates with sufficient accuracy
to perform the tasks discussed below. Digital map 270 may also
include a plurality of plant areas 272. Each plant area 272 is a
representation of where a seed 119 was planted by seeder 110 during
the seeding operations. Each plant area 272 may be appropriately
sized to take into account the expected dimensions of the type of
plant or crop planted within field 10. In other words, plant area
272 represents more than just the precise position at which a
corresponding seed 119 was deposited. Instead, plant area 272
preferably represents an area over which expected plant or crop
growth may be found (e.g., for the particular time at which the
weeding operations are taking place, or just in general).
[0074] Each plant area 272 is located in an associated crop
rotation zone 265 and may be based on the actual location at which
a plant was planted, taking into account any expected plant
growth.
[0075] The task of vehicle 300 is to make use of digital map 270 in
determining whether any undesired plant growth (e.g., weeds) has
sprouted in field 10. By knowing the position of desired plant
growth, i.e., the plant areas 272, vehicle 300 may locate and
detect other plant growth which is not within a plant area 272. For
example, vehicle 300 may be fitted with a sensor package 302 which
is capable of identifying plant growth or other targets of
interest. Sensor package 302 may comprise a chlorophyll detector
such as those used by the WEED-IT selective weed control system
developed by Kamps de Wild B. V., Zevenaar, The Netherlands. Other
sensors which may identify weeds and other plant growth based on
their reflective characteristics (e.g., video cameras and/or
infra-red detectors) may be substituted for the chlorophyll
detectors or, indeed, used in conjunction with the chlorophyll
detectors. See, e.g., D. C. Slaughter et al., "Computer Vision
Guidance System for Precision Cultivation", Paper No. 97-1079, 1992
ASAE Annual International Meeting. Aug. 10-14, 1997, the complete
disclosure of which is incorporated herein by reference.
[0076] When chlorophyll (or another plant characteristic targeted
by sensor 302) is detected, it is a good indication that a plant,
or plant-like material, has been found. Sensor 302 is positioned on
vehicle 300 such that its location relative to GPS antenna 304 is
known. Thus, when a target is detected by sensor 302, the position
of the target can be determined based on precise positioning
information provided by an onboard RTK GPS receiver coupled to
antenna 304. Exemplary RTK GPS receivers which may find application
in the present scheme include the Ag 122/132 receivers, available
from Trimble Navigation, Ltd. of Sunnyvale, Calif. In some cases,
the RTK GPS receiver may be located within the same housing as
antenna 304. The onboard RTK GPS receiver also receives RTK data
from an RTK reference station via antenna 306 in the conventional
fashion. As vehicle 300 operates within field 10, sensor 302 can
thus locate various plants and vehicle 300 can determine the
positions thereof with respect to known plant locations from
digital map 270. It is expected that the detection of unwanted
vegetation will be accomplished in a region nearby where desired
plant growth is known/expected to exist. In most cases, the
chlorophyll detector sensitivity will require that the detector be
close enough to the undesired plant growth that an on-board plant
eradication mechanism (e.g., an auger and/or herbicide sprayer) can
automatically perform eradication operations in the region directly
in front of the sensor so as to eliminate the undesired plant
growth without disturbing the desired plant growth.
[0077] In some cases, machine vision-related technology may be used
to assist in deploying the plant eradication mechanism. For
example, vehicle 300 may include a video camera as part of sensor
package 302. The video camera may be used to capture an image of
the region in front of vehicle 302. The image may thus include a
representation of the undesired plant growth detected by the
chlorophyll detector and the auger or other plant eradication
mechanism may be deployed so as to be directed at the centroid of
that representation. Such systems may be similar to "pick and
place" equipment commonly used in the manufacture of electronic
components and/or the planting of some crops. For example, robot
machinery which makes use of video capture technology such as that
described above is often used to place small parts, such as
integrated circuits and the like, on printed circuit boards prior
to soldering. Camera depth of field and the video pattern
recogniation software could be adjusted so as to only recognize
weeds of a certain size, etc.
[0078] In addition to allowing for precise targeting of the plant
eradication mechanism, in such a system the image obtained by the
video camera may also be used to compare the representation of the
undesired plant growth to a library of stored representations in
order to classify or otherwise identify the undesired plant growth.
The ability to determine which variety of weed, for example, is
growing in a certain area may allow users of vehicle 300 to better
choose which herbicide or other eradication means to deploy.
[0079] FIGS. 10A-10C illustrate vehicle 300 in further detail. In
general vehicle 300 includes a housing 340 and a propulsion unit
350 coupled thereto. One example of an autonomous vehicles which
utilize similar technology (although without the novel features of
the present vehicle 300) is the Nomad robotic system developed by
NASA's Intelligent Mechanism Group at the Ames Research Center and
the Robotics Institute at Carnegie Mellon University. A complete
description of the technical features of the Nomad robotic vehicle
may be fount at http://img.arc.nasa.gov/Nomad/ and related links.
Housing 340 may include the RTK GPS receiver, or other precise
positioning apparatus, which, in general, may be part of a guidance
computer 360. Guidance computer 360 receives inputs from sensor
package 302 which, as indicated above, may be configured to detect
plant growth. Together, guidance computer 360 and sensor package
302 make up a sensor-controller apparatus which is configured to
detect a target, at least in part, according to the location of
vehicle 300 (i.e., as determined by the RTK GPS receiver). Guidance
computer 360 may also provide guidance commands to drive motors 364
which, in general, will be part of propulsion unit 250. In this
way, the guidance computer 360 can provide navigation or other
guidance commands to the drive motors 364 to control the movement
of vehicle 300.
[0080] Drive motors 364 may be powered in any of a number of ways.
For example, drive motors 364 may be gasoline powered, in which
case a gasoline (or other fuel) tank will be required on board
vehicle 300. Preferably, however, vehicle 300 will be configured to
operate for extended periods in one or more fields. Thus, the drive
motors 364 are preferably operated using batteries 366 which are
charged using solar cells 368, fitted within housing 310. Drive
motors 364 receive guidance commands (e.g., forward, reverse,
speed) from guidance computer 360 and motor control unit 369. Motor
control unit 369 provides an interface between guidance computer
360 and drive motors 364 and may convert digital and/or analog
signals from guidance computer 360 to voltage and/or current
signals to operate drive motors 364. Such control of DC motors
(which are preferably used for drive motors 364) is well known to
those of ordinary skill in the art.
[0081] Also included onboard vehicle 300 may be sonar collision
avoidance sensors 370. The sonar collision avoidance sensors 270
may provide inputs to guidance computer 260 to prevent guidance
computer 360 from piloting vehicle 300 into an obstacle. In
general, the sonar collision avoidance sensors 370 will provide a
indication to guidance computer 360 of how close an obstacle may
be. The use such collision avoidance systems is well known in the
art. See e.g., Raymond C. Daigh "High Reliability Navigation for
Autonomous Vehicles," Trimble Users Conference Proceedings pp.
133-143, 1996, which is incorporated herein by reference. Other
collision avoidance sensors (e.g., infra-red sensors) may be used
in place of or in addition to the sonar sensors.
[0082] The guidance computer 360 may also be configured with a
transmitter apparatus to broadcast emergency or other messages, for
example in the case where vehicle 300 becomes disabled or
encounters problems with its operations. Preferably, as part of
such messages, the position of vehicle 300 (as reported by the
precise positioning means) is transmitted so as to allow for easy
location of vehicle 300 by human operators, etc. Further, vehicle
300 may include within housing 340 one or more actuators 385. In
this particular case, actuators 385 drive one or more augers 390
which may be used to remove weeds. In addition, a herbicide tank
and associated spraying nozzles (not shown) may be included.
[0083] FIGS. 11a-11f illustrate exemplary operations of vehicle 300
within field 10. To begin, in FIG. 11a, vehicle 300 will have
already been provided with digital map 270. Preferably, digital map
270 is stored (e.g., in volatile or non-volatile memory accessible
by guidance computer 360) on-board vehicle 300. However, in some
cases, digital map 270 may be stored at another location and may be
accessed by vehicle 300 (i.e., guidance computer 360) via a radio
(or other) link (e.g., using antenna 306). Also, guidance computer
360 will be programmed to conduct operations within field 10, for
example, by traversing each row of plants or crops within the field
10. Notice that vehicle 300 is provided with sufficient ground
clearance to avoid the growing plants or crops 420. For the case
where the plants or crops 420 are relatively tall, vehicle 300 may
be configured to operate in trenches or other paths beside the rows
of growing plants and crops. Also, vehicle 300 is shown with
optional treads 380, making this embodiment of vehicle 300 a
"tracked vehicle". The use of treads 380 provides stability and
"all weather" capability. However, other configurations are
possible, for example, conventional tires or even solid wheels or
rollers.
[0084] As vehicle 300 operates in field 10, it receives GPS
information from satellites 106 and RTK data (via antenna 306) from
an RTK reference station (not shown). This allows the RTK GPS
receiver onboard vehicle 300 (e.g., which may be part of guidance
computer 360) to determine the precise position of vehicle 300
(e.g., to within a few centimeters). For those situations where
vehicle 300 will be operating in areas which do not provide clear
views of the sky (and, thus, may be subject to GPS outages) vehicle
300 may be filled with a dead reckoning system similar to that
described by Daigh. However configured, vehicle 300 uses the
precise positioning information provided by the onboard RTK GPS
receiver and/or the dead reckoning system to determine its
position. That position may then be used to determine whether a
weed (or other undesired plant growth) has been located as
follows.
[0085] In FIG. 11b, vehicle 300 has reached a position in field 10
such that sensor 302 has detected the presence of a plant 402. This
may be accomplished using a chlorophyll detector or other sensor
means (e.g., infra-red and/or video analyzers). Having thus
detected a plant 402, vehicle 300 must determine whether it is
desired plant growth or undesired plant growth. To make this
determination, vehicle 300 (e.g., guidance computer 360) access
digital map 110 and compares its current position (as determined by
the onboard precise positioning means) to the plant areas 272
defined in digital map 110. If this comparison indicates that
vehicle 300 is within a plant area 272 (i.e., that sensor 302 has
detected plant growth within a plant area 272), the detected plant
402 is classified as desired plant growth. Thus, a "no weed"
decision is reached. On the other hand, if the position comparison
determines that the detected plant 402 is not within a plant area
272, then the plant 402 is classified as undesired plant growth
(i.e., a "weed" decision is made). As shown, the size and
configuration of plant areas 272 are configurable depending on the
type of crop planted and the period of time (e.g., immediately
after seeding, during the growing season, close to harvest, etc.)
when vehicle 300 is operating.
[0086] If a "no weed" decision is reached, vehicle 300 proceeds
with its operations in field 10. Preferably, the weed/no weed
decisions are made on-the-fly, so that vehicle 300 need not pause
each time it detects a plant. It is expected that vehicle 300 will
travel slowly enough within field 10 that this on-the-fly
computation will be possible.
[0087] If a "weed" decision is reached, however, vehicle 300
invokes its weed removal routine. As shown in FIG. 11c, vehicle 300
positions itself over the weed 402 so that one of the onboard
augers 390 is above weed 402. This position calculation is
relatively straight forward as vehicle 300 is capable of
determining its position (i.e., the position of antenna 304) to
within a few centimeters and the location of auger 390 within
housing 340 is at a known offset. Thus, when a weed decision is
made, guidance computer 260 provides the appropriate commands to
drive motors 364 (e.g., via motor control unit 369) to move vehicle
300 to a position such that auger 390 is located appropriately, for
example directly above weed 402. Note, machine vision techniques
and systems may be used to assist in these operations as discussed
above.
[0088] Once vehicle 300 is properly positioned above weed 402,
auger 390 is engaged and, as shown in FIG. 11d, is used to dig up
or otherwise destroy weed 402. At or about the same time, a weed
herbicide may be deployed (e.g., from onboard nozzles if vehicle
300 is so configured). Auger 390 may be appropriately sized so as
to be capable of removing expected size weeds from field 10. In
general, it is expected that a working end of a few inches will be
sufficient for auger 390. Of course, other size augers 390 may be
included.
[0089] Once weed 402 has been destroyed (e.g., after a specified
time for auger 390 to operate), auger 390 is retracted, as shown in
FIG. 11e. Once so retracted, vehicle 300 moves on and continues
operations in field 10. FIG. 11f shows vehicle 300 engaged in
further weed removal operations at a later point in field 10.
[0090] FIG. 12 illustrates the functional components of vehicle
300. As shown, a decision making apparatus 460, for example a
processor which is part of guidance computer 360, receives inputs
from an onboard RTK GPS receiver 440, sensor package 450, and
digital map 270. RTK GPS receiver 440 provides a precise position
input, which may be augmented with a dead reckoning input from a
dead reckoning system 470 as discussed above. Sensor package 450
provides an indication of plant growth (e.g., chlorophyll) as an
input. Digital map 270 provides an indication of the plant areas
272 as discussed above. The various inputs are combined to
determine whether or not a detected target is desired plant growth
or undesired plant growth (i.e., a weed). The result of the
decision is output as a decision result 480.
[0091] As shown in FIG. 13, the decision result 480 may be applied
directly to an actuator (e.g., an auger 390 and/or herbicide
sprayer) or may be overridden in the event of some abort condition.
In general, the decision result will be a digital output, for
example a logic 1 for a "weed" decision and a logic 0 for a "no
weed" decision. This digital value will need to be translated to
mechanical action by the actuator using conventional digital
control system techniques. For example, the drive motors 364 may be
decoupled from the propulsion unit 350 and used to drive the auger
390 via a belt drive, direct drive or other drive system. In other
cases, auger 390 may have its own drive motor arrangement, powered
from battery 366. In such a case, the decision result may be
applied to that drive motor arrangement to control the action of
auger 390.
[0092] As shown, there may be times when some other information 484
indicates that, even though a weed has been detected, the action of
auger 390 should be aborted. For example, if the charge of battery
366 is very low, vehicle 300 may decide to delay weed destroying
operations (e.g., via override stage 486) until sufficient charge
is available to operate auger 390. In such cases, vehicle 300 may
cease operations to charge battery 366 or vehicle 200 may simply
store the location of weeds it has detected in digital map 270 for
later action/removal. Otherwise, the actuator command 490 may be
provided to actuator 385.
[0093] FIGS. 14a and 14b illustrate an alternative method of
operating vehicle 300. At step 500, the position of vehicle 300 is
determined based upon the information provided by RTK GPS receiver
440 and/or dead reckoning system 470. At step 502, as vehicle 300
is operating in field 10 the current position of vehicle 300 is
compared to digital map 270 to determine whether vehicle 300 is in
a plant area 272 or not. At step 504, if vehicle 300 is located
within a plant area 272 the above process repeats. Once vehicle 300
is outside a plant area 272, at step 506 data from sensor 302 is
obtained. A check is made to determine whether sensor 302 has
detected chlorophyll at step 508. If not, the above procedure is
repeated until chlorophyll has been detected. At step 510, if
chlorophyll has been detected it is recognized that the plant
growth is undesired plant growth and a weeder routine is involved.
Of course, many other methods of operating vehicle 300 are
possible. For example, the process of determining the position of
vehicle 300 may execute in parallel with the determination of
whether sensor 302 has detected plant growth. These routines may
then provide outputs to a decision making routine which determines
whether any detected plant growth is desired or undesired, based on
the position of vehicle 300.
[0094] FIG. 14b illustrates weeder routine 600 in further detailed.
As indicated above, an optional override procedure at step 602 can
be implemented. If no override conditions exist, at step 604 the
augers 390 or other actuators are activated and the weed is
destroyed.
[0095] FIGS. 15-17 illustrate an alternative embodiment of the
present invention. In this case, an autonomous vehicle 800 is
configured to deposit lane markers 802 on a roadway 804, e.g.,
where old lane markers have been displaced. Vehicle 800 is
configured much like vehicle 300 in that it includes a decision
making apparatus (e.g., a guidance computer) that pilots vehicle
800 within roadway 804. The decision making apparatus receives
inputs from an onboard RTK GPS receiver, to keep track of its
position and to compare that position to a digital map which may be
stored onboard or accessed from a remote location via a radio or
other link. Also provided within vehicle 800 are sensors, which may
be used to detect the presence (or absence) of lane markers 820,
and collision avoidance sensors to provide against unknown
obstacles. It is also preferable that vehicle 800 is fitted with
high visibility markers such as lights 806 and/or acoustic warning
devices 808. This allows other users of roadway 804 to be aware of
the presence of vehicle 800.
[0096] As shown in FIG. 16, a digital map 810 may be created as
vehicle 800 lays down lane marker 820, e.g., as roadway 804 is
being developed or repaired. This digital map 810 defines the
expected location of lane markers 820 for later operations of
vehicle 800. Vehicle 800 is equipped with actuator 812 which is
designed to affix lane markers 820 to roadway 804 at positions
determined by roadway designers and provided to vehicle 800.
[0097] Later, as shown in FIG. 17, vehicle 800 may operate along
roadway 804, looking for missing lane markers 820. Using a sensor
814, vehicle 800 can determine when a lane marker 820 is missing by
comparing its present position (e.g., provided by an onboard RTK
GPS receiver) to digital map 810. When digital map 810 indicates,
based on the current position of vehicle 800, that a lane marker
820 should be present, and sensor 814 indicates that no such lane
marker is in place, vehicle 800 may operate actuator 812 to deposit
a new lane marker 822 at the position where a lane marker should
have been located.
[0098] FIGS. 18 and 19 illustrate a semi-autonomous variant of the
vehicle described above. The semi-autonomous vehicle (which may be
referred to as an implement) 900 may be towed behind a tractor 902
or other vehicle which may provide the steering, guidance and power
for vehicle 900. Semi-autonomous vehicle 900 includes a
sensor-controller arrangement 904 similar to that discussed above
and configured to identify a target (i.e., plant growth) according
to a sensor input and a position input. In some cases,
sensor-controller arrangement 904 may be included on tractor 902
while in other cases it forms an integral part of vehicle 900.
[0099] As before, the position input is provided by one or more
global positioning system (GPS) receivers, for example, real time
kinematic (RTK) GPS receivers 906. For the illustrated embodiment,
a single RTK GPS receiver 906 is used, but the receiver 906
collects inputs from a number of GPS antennas 908. The use of
multiple antennas 908 allows vehicle 900 to detect any yaw in its
boom 910 and modify its plant eradication operations accordingly.
The sensor input may be provided by chlorophyll detectors 912,
video cameras 914 and/or infra-red detectors 916. Multiple clusters
917 of these sensors 912, 914 and/or 196 may be deployed along boom
910.
[0100] Vehicle 900 also includes a plant eradication mechanism 918,
for example a sprayer arrangement 920 which includes sprayer
nozzles 922 for dispensing a herbicide, a fertilizer and/or a
pesticide. Associated tanks or bins 924 for carrying the herbicide,
fertilizer and/or pesticide are included, and each tank 924 feeds
its associated nozzles via a control valve 926 which may be under
the control of the sensor-controller arrangement 904. Thus, in
response to control signals from sensor-controller apparatus 904
which open or close the valves 926, herbicide, fertilizer and/or
pesticide may be deployed as desired.
[0101] As indicated, vehicle 900 includes a boom 910 which supports
multiple sensor clusters 917 and multiple sprayer arrangements 920.
This allows vehicle 900 to perform plant
eradication/fertilization/pest control operations over a wide area
for each pass through a field or other cultivated area 928 made by
tractor 902. In other cases, a single sprayer arrangement 920 may
be used. Preferably, an auger is not used in this embodiment so
that the semi-autonomous vehicle 900 need not stop to destroy any
weeds, etc. Instead, the vehicle 900 is towed by tractor 902 at a
known or measured speed such that the time for deploying herbicide,
fertilizer and/or pesticide can be calculated by a decision-making
apparatus included within sensor-controller arrangement 904. For
example, if the sprayer arrangement 920 is positioned a distance D
behind the sensors (i.e., chlorophyll detector 912, video camera
914 and/or infra-red detector 916) and the vehicle 900 is being
towed at a speed S, then the time to deploy the herbicide,
fertilizer and/or pesticide will be approximately T=D/S, with
provision for any delay required for the actual weed/plant sensing
operation and the opening/closing of the sprayer nozzles 920 (i.e.,
their associated control valves 926). Note, in the above example, D
more properly represents the point at which the sensors are focused
or otherwise pointed, rather than just their physical location
onboard vehicle 900.
[0102] Thus, the sensor-controller arrangement 904 includes a
decision-making unit coupled to receive the sensor input and the
position input. The decision-making unit (e.g., a general purpose
or special purpose microprocessor, not shown in detail) is
configured to use these inputs, along with reference position
information, to classify the target (e.g., as a weed or otherwise).
The reference position information may be obtained from a digitized
map of the field (as discussed above), for example, which may be
stored in memory accessible by the decision-making unit.
Preferably, the digitized map will include information defining
desired plant growth regions 930 so as to aid in classifying the
target as desired plant growth or otherwise.
[0103] When undesired plant growth is detected, the sprayer
apparatus 920 may be used, for example with control signals from
the sensor-controller arrangement 904, to apply a herbicide
thereto. Alternatively, or in addition thereto, the sprayer
apparatus 920 may be used to dispense a fertilizer and/or a
pesticide in addition to (or instead of) the herbicide. Thus, while
eliminating undesired plant growth, the apparatus may also be used
to fertilize desired plant growth and apply pesticides to selected
areas to control pests.
[0104] As is apparent then, the vehicle control system may used
with a vehicle useful for locating and destroying undesired plant
growth (e.g., weeds) in a cultivated area or with another purpose,
and the vehicle itself may be fully autonomous (e.g., having its
own propulsion system) or semi-autonomous (e.g., where it is towed
by a tractor or similar means). In one embodiment, it has been
shown that the vehicle may include a precise positioning apparatus,
for example an RTK GPS receiver with or without an augmenting dead
reckoning system, configured to provide real-time precise
positioning information regarding the location of the vehicle. The
vehicle may further include a sensor-controller apparatus
configured to detect a target (e.g., a weed), at least in part,
according to the location of the vehicle. A propulsion unit is used
to transport the vehicle and may be part of the vehicle itself
(e.g., under the control of the sensor-controller apparatus) or an
external unit (e.g., a tractor or other vehicle). Collision
avoidance sensors may be provided for obstacle detection and/or
avoidance.
[0105] Whether used with the fully autonomous vehicle or the
semi-autonomous vehicle, the sensor-controller apparatus may
include a sensor package configured to detect a characteristic of
the target (e.g., chlorophyll or infra-red/visible spectrum
reflectivity for the case where the target is undesired plant
growth) and a decision-making apparatus coupled thereto. The
decision-making apparatus is configured to combine inputs from the
sensor package, the precise positioning apparatus and a stored map
of an area in which the vehicle operates to produce a decision
output. An actuator within the vehicle is configured to response to
the decision output of the decision-making apparatus. In one
particular embodiment it was shown that the actuator comprises weed
removal means which may include a herbicide deploying mechanism; a
rotating, string-based weed remover/cutter and/or an auger. In
another particular embodiment the actuator comprises lane marker
depositing means which may be used to place lane markers on a
roadway.
[0106] Thus, a vehicle control system has been described. Although
discussed with reference to certain specific embodiments, these
exemplary configurations merely illustrate a few of the possible
implementations of the present invention and should not limit the
generality thereof. Instead, it should be recognized that other
operations are possible and, indeed, are contemplated within the
spirit and scope of the present invention. For example, using the
techniques discussed herein, weeding, cultivating and/or planting
operations may be performed by a fully autonomous vehicle or,
indeed, a semi-autonomous vehicle. Using either configuration, a
fertilization application could be made to an identified crop plant
only, excluding any undesired plant growth or plant growth of a
desired, but different, type. Further, target applications of
specific herbicides and/or pesticides could be carried out. Thus,
the present invention allows for any delivery of a product or
service to a precise location, based on a sensor input and a
position input. Thus, the present invention should only be measured
in terms of the claims which follow.
* * * * *
References