U.S. patent application number 09/349562 was filed with the patent office on 2001-08-30 for method and apparatus ofr position determining.
This patent application is currently assigned to CLAAS SELBSTFAHRENDE ERNTEMASCHINEN GMBH. Invention is credited to QUINCKE, GUNNAR.
Application Number | 20010018638 09/349562 |
Document ID | / |
Family ID | 7873562 |
Filed Date | 2001-08-30 |
United States Patent
Application |
20010018638 |
Kind Code |
A1 |
QUINCKE, GUNNAR |
August 30, 2001 |
METHOD AND APPARATUS OFR POSITION DETERMINING
Abstract
The invention describes a device and a method for finding an
actual or a virtual reference point on mobile equipment or
implement. In agricultural technology the control and mapping of
working processes as a function of the instantaneous position of
the equipment on the field is gaining more and more importance.
With increasing precision of the navigation systems, further
possible applications are opening up. As a result of the higher
precision of satellite navigation systems, the changes in
inclination and direction of the equipment also have an effect on
the measured position of the equipment. This effect is of the order
of magnitude of the precision of modern-day navigation equipment
and is therefore also taken into consideration in position finding
according to the invention. For this the inclinations and direction
of the machine referred to a predefined neutral position are
determined and also calculated when finding any reference position.
With the aid of the invention the exact position values of the
navigation antenna can be converted to a reference point, which is
important for the working process. This reference point can for
example represent the position of the cutterbar edge or current
product edge of a fertilizer spreader. In an advantageous
embodiment, when determining the position of the reference point,
further working parameters such as speeds or positions of
implements are taken into consideration or the position of the
reference point is regulated with the aid of dynamic parameters
such as for example the speed of travel.
Inventors: |
QUINCKE, GUNNAR; (SOEST,
DE) |
Correspondence
Address: |
ROBERT E MUIR
HUSCH & EPPENBERGER LLC
401 MAIN STREET
SUITE 1400
PEORIA
IL
61602
|
Assignee: |
CLAAS SELBSTFAHRENDE ERNTEMASCHINEN
GMBH
|
Family ID: |
7873562 |
Appl. No.: |
09/349562 |
Filed: |
July 8, 1999 |
Current U.S.
Class: |
701/468 |
Current CPC
Class: |
A01B 79/005
20130101 |
Class at
Publication: |
701/213 |
International
Class: |
G01C 021/26 |
Claims
I claim:
1. In a unit of equipment having a satellite reception unit capable
of receiving global positioning system transmissions and means for
determining a precise position thereof, the improvement comprising:
(a) means including at least one sensor associated with the
equipment and having the capability to determine three-dimensional
distance from the satellite reception unit to a spaced reference
point; and (b) a processing unit for calculating the position of
the spaced reference point using the position of the satellite
reception unit and the distance information from the sensor.
2. A unit of equipment according to claim 1, wherein the processing
unit determines a transformation matrix, and with this
transformation matrix determines a position vector of the reference
point from the known position vector of the satellite reception
unit.
3. A unit of equipment according to claim 1, wherein the sensor is
a direction sensor whereby the alignment of the equipment in the
horizontal plane of a terrestrial reference system is found.
4. A unit of equipment according to claim 1 wherein the sensor is
an inclination sensor whereby the longitudinal inclination of the
equipment is found relative to a vertical direction of a
terrestrial reference system.
5. A unit of equipment according to claim 1 wherein the sensor is
an inclination sensor whereby the transverse inclination of the
equipment relative is found relative to a vertical direction of a
terrestrial reference system.
6. A unit of equipment according to claim 1 wherein the sensor is a
sensor that determines the alignment of the equipment in the
horizontal plane of a terrestrial reference system as well as the
longitudinal inclination of the equipment relative to the vertical
direction of a terrestrial reference system.
7. A unit of equipment according to claim 1 wherein a reference
line consisting of at least two reference points can be found.
8. A unit of equipment according to claim 1 wherein a reference
area consisting of at least three reference points can be
found.
9. A unit of equipment according to claim 1 wherein a reference
volume consisting of at least four reference points can be
found.
10. A unit of equipment according to claim 1 wherein at least one
working parameter of an implement attached to the equipment is
taken into consideration by the processing unit, whereby the
position of the reference point relative to the satellite reception
unit can be calculated as a function of the working parameter.
11. A unit of equipment according to claim 1, including means for
determining the speed of travel of the unit, and wherein the
processing unit takes into consideration speed of travel of the
equipment when finding a virtual reference point, whereby the
position of the virtual reference point relative to the satellite
reception unit can be regulated dynamically as a function of the
speed of travel.
12. A unit of equipment according to claim 1, wherein individual
reference points are capable of being controlled by the operator of
the equipment.
13. A unit of equipment according to claim 1, wherein individual
reference points are capable of being controlled automatically by
the working process.
14. In agricultural equipment having a satellite reception unit for
position finding in the three-dimensional terrestrial reference
system, and a processing unit which from the data received by the
satellite reception unit determines the absolute position of at
least one reference point which is spatially separate from the
location of the satellite reception unit, the spatial distance
between the satellite reception unit and the reference point being
known in value, the improvement comprising: at least one sensor for
finding the position of the equipment i.e., alignment and
orientation of the equipment in the horizontal plane of the
terrestrial reference system and/or the longitudinal or transverse
inclination of the equipment relative to the vertical direction of
the reference system, in a memory of the processing unit for a
given marked position of the equipment--preferably longitudinal
direction of the equipment in the N-S direction with the front
facing north and without longitudinal or transverse inclination of
the equipment--at least one equipment-specific base conversion
quantity (X.sub.P0-X.sub.A0; Y.sub.P0-Y.sub.A0; Z.sub.P0-Z.sub.A0;
.phi..sub.0; .alpha..sub.0; .beta..sub.0; d.sub.1, d.sub.2;
d.sub.3) can be stored, --the sensor(s) detecting at least one
deviation (.phi., .alpha., .beta.) of the position from the aligned
neutral position, and the processing unit with the aid of this
deviation (.phi., .alpha., .beta.) and taking into account at least
one equipment-specific base conversion quantity (.phi..sub.0;
.alpha..sub.0; .beta..sub.0; d.sub.1, d.sub.2; d.sub.3) in each
case determining the current conversion quantity for finding the
coordinates (X.sub.A, Y.sub.A, Z.sub.A) of the reference point
which is spatially at a distance from the satellite reception unit,
from the known position coordinates (X.sub.P, Y.sub.P, Z.sub.P) of
the satellite reception unit.
15. A method for position finding in the three-dimensional
terrestrial reference system comprising: (a) determining the
absolute position in the three-dimensional terrestrial reference
system using a satellite reception unit; (b) determining the
distance between the satellite reception unit and a reference point
spatially separate from the location of the satellite reception
unit using at least one sensor; (c) storing equipment-specific base
conversion quantities in memory accessible by the processing unit;
and (d) determining the absolute position of the reference point
with a processing unit and the data received by the satellite
reception unit.
16. A method for position finding in the three-dimensional
terrestrial reference system according to claim 15 further
including determining a transformation matrix from the
equipment-specific conversion quantities, whereby it can determine
the position vector of the reference point from the known position
vector of the satellite reception unit.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates generally to mobile equipment, and
more particularly to such equipment having a satellite reception
unit and method for position finding.
[0002] The use of satellite navigation systems, for example, the
global positioning system (GPS), is already known with agricultural
equipment or with implements for drawing up crop registers and
ground height profiles as well as monitoring fertilizer dispensing.
In this case meanwhile satellite navigation systems such as
differential global positioning (DGPS) are available with suitably
efficient evaluation units which achieve accuracy of position
finding, i.e., finding the position of a GPS antenna, to within a
centimeter.
[0003] Thus, for example, from DE 196 47 523 is known an
agricultural equipment with a satellite navigation system. The
equipment described therein has a cultivation tool, it being
proposed therein to find the position of a reference point on the
cultivation tool instead of, for example, the position of the
center of the equipment. There is a problem here, however, if the
satellite reception unit (GPS antenna) for particular reasons
cannot be mounted on the reference point of the cultivation tool.
Lack of mechanical mounting facilities, shading of signals by the
equipment itself, or the risk of damage or heavy wear are possible
reasons for the fact that the GPS antenna cannot be mounted
directly in the location whose position is actually to be found. In
these cases the reference point whose position is to be found is at
a distance spatially from the GPS antenna whose position is
actually found by the satellite navigation system. This makes
coordinate conversion necessary; i.e., from the coordinates found
by satellite navigation of the GPS antenna which is, for example,
located on top of the equipment, the coordinates of the reference
point on the cultivation tool, which might be lower than the
antenna, must be deduced by conversion. In the event that the
cultivation tool is rigidly connected to the equipment, from DE 196
47 523 is obtained the instruction for finding the height
coordinate of the reference point; subtract the difference in
height between the mounting point of the GPS antenna and the
reference point of the height-coordinate of the mounting point of
the GPS antenna determined by satellite navigation for conversion.
In the event that the cultivation tool is not rigidly connected to
the equipment, but, for example, mounted on it with adjustable
height, from DE 196 47 523 is obtained the instruction to provide a
sensor which measures the change in height of the cultivation tool
relative to the equipment and lets this measured change in height
enter into the coordinate finding described above as a
correction.
[0004] Furthermore, however, there is a general problem of position
finding if the location (reference point) whose position is to be
found does not coincide with the mounting point of the GPS antenna,
but there is a distance between the two. And of course there is an
uncertainty which stems from the fact that basically all points on
the surface of a sphere with a radius of that distance, at the
center of which is located the mounting point of the GPS antenna,
are considered as the possible positions of the reference point. As
the distance between the reference point and the GPS antenna in the
case of agricultural equipment can perfectly well be several
meters, the result is a correspondingly high uncertainty in
position finding of the reference point, which is in itself highly
unsatisfactory in view of more and more accurate navigation
systems.
[0005] Of course the direction of travel and the orientation of the
equipment can be determined by iteration while traveling from the
position coordinates of the GPS antenna succeeding each other in
time, but this method is inaccurate and fails in the case of
equipment that is stationary or when starting from a standstill.
Furthermore, the direction of travel does not tally with the
longitudinal direction of the equipment in some applications (for
example, in crab steering or on a slope).
[0006] Only if one were to make restrictions on freedom of
movement--for instance, only travel in a N-S and/or E-W direction
or only travel in the horizontal plane--could this uncertainty be
avoided. This is, however, not possible with agricultural equipment
and implements hitched to them.
[0007] It is an object of the present invention to reliably allow
accurate finding of a reference point which is spatially remote
from the mounting point of the navigation antenna.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention there is provided a
satellite antenna attached to an item of equipment and capable of
receiving global positioning system transmissions, at least one
sensor with the capability to determine three-dimensional distance
from the satellite antenna to a reference point, and a processing
unit capable of calculating the location of the reference point
using the location of the satellite antenna and the distance
information from the sensor.
[0009] In accordance with another aspect of the present invention
is a method for position finding in the three-dimensional
terrestrial reference system. The absolute position of a satellite
reception unit is determined, and then at least one sensor is used
to determine the distance between the satellite reception unit and
a reference point spatially separated from it. Equipment-specific
base conversion quantities in memory accessible to the processing
unit are then used to determine with a processing unit and the data
received by the satellite reception unit the absolute position of
the reference point.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Reference is now made more particularly to the drawings
which illustrate the best presently known mode of carrying out the
invention and wherein similar reference characters indicate the
same parts throughout the views.
[0011] FIG. 1 is a view, partly diagrammatic and partly a side
view, of a combine harvester having a GPS antenna on its top and a
mounted cutterbar at the front on which the reference point is
located.
[0012] FIG. 2 is a schematic top view of the horizontal plane with
a combine harvester, aligned in the neutral position with the
longitudinal direction to the north.
[0013] FIG. 3 is as FIG. 2, but the combine harvester is turned
relative to the aligned position on the horizontal plane.
[0014] FIG. 4 is a schematic side view with the combine harvester
in the yz-plane in an aligned neutral position.
[0015] FIG. 5 is as FIG. 4, but the combine harvester is turned
relative to the aligned position in the yz-plane.
[0016] FIG. 6 is a schematic side view with the combine harvester
in the xz-plane in an aligned neutral position.
[0017] FIG. 7 is as FIG. 6, but the combine harvester is turned
relative to the marked position in the xz-plane.
[0018] FIG. 8 is a schematic top view of a combine harvester with a
virtual working area located in front of the cutterbar.
[0019] FIG. 9 is a side view of a combine harvester with a virtual
reference point located in front of the cutterbar.
[0020] FIG. 10 is as in FIG. 9, with the reference point located
further in front of the cutterbar.
[0021] FIG. 11 is a schematic top view of a tractor with a
fertilizer spreader mounted by the three-point hitch and two
virtual reference points.
[0022] FIG. 12 is a block diagram with the evaluation unit and the
various sensors.
DETAILED DESCRIPTION
[0023] A piece of agricultural equipment 20 comprises at least one
sensor S, S1, S2, S3 for finding the position of the equipment.
Here, "position" means the alignment of the equipment and the
orientation in the horizontal plane of the terrestrial reference
system (x, y, z). Alignment means the angle (.phi.) which the
longitudinal direction of the equipment forms, for example, with
the N-S direction (y-coordinate of the terrestrial reference
system). Orientation means the direction in which, for example, the
front of the equipment points. But the position of the equipment
also means the longitudinal (.alpha.) or transverse (.beta.)
inclination of the equipment relative to the vertical direction
(Z-coordinate) of the reference system. The coordinates of a GPS
antenna 22 are referred to as (X.sub.A, Y.sub.A, Z.sub.A); the
coordinates of a reference point 24 as (X.sub.p, Y.sub.p,
Z.sub.p).
[0024] Preferably a mechanical gyro compass or a laser gyro known
to one skilled in the art is used as the sensor for finding the
alignment (.phi.) of the equipment 20 in the horizontal plane.
Preferably perpendicular pendulums with electrical signal
generators which are also known to one skilled in the art are used
as the sensors for the longitudinal (.alpha.) or transverse
(.beta.) inclination. One skilled in the art can also make use of a
single sensor which is capable of detecting the various deviations
(.phi., .alpha., .beta.).
[0025] Further, according to the embodiment of the invention,
equipment-specific base conversion quantities (X.sub.P0-X.sub.A0;
Y.sub.P0-Y.sub.A0; Z.sub.P0-Z.sub.A0; .phi..sub.0; .alpha..sub.0;
.beta..sub.0; d.sub.1, d.sub.2; d.sub.3) are provided which reflect
the geometrical ratios of the arrangement of the reference point
and GPS antenna 22 on the equipment 20 for a given, aligned
position of the equipment. The aligned position of the equipment
selected is preferably the one in which the longitudinal direction
of the equipment is aligned in a N-S direction with the front
facing north and in which there is no longitudinal or transverse
inclination of the equipment, i.e., for the particular position it
is assumed that the equipment is standing on a level field not
sloping in any direction. These base conversion quantities are, so
to speak, part of an equipment specification. In detail they
are
[0026] (X.sub.P0-X.sub.A0) the difference between the x-coordinates
of reference point and location of the GPS antenna 22,
[0027] (Y.sub.P0-Y.sub.A0) the corresponding difference between the
y-coordinates,
[0028] (Z.sub.P0-Z.sub.A0) the corresponding difference between the
z-coordinates,
[0029] d.sub.1 the projection of the distance (D; distance from the
location of the GPS antenna 22 to the reference point 24) onto the
horizontal plane (x,y) of the reference system,
[0030] d.sub.2 the projection of the distance (D; distance from the
location of the GPS antenna to the reference point) onto the
y,z-plane of the reference system,
[0031] d.sub.3 the projection of the distance (D; distance from the
location of the GPS antenna 22 to the reference point 24) onto the
horizontal x,z-plane of the reference system,
[0032] .phi..sub.0 the angle between d.sub.1 and the N-S direction
(x-direction),
[0033] .alpha..sub.0 the angle between d.sub.2 and the vertical of
the reference system (z-direction),
[0034] .beta..sub.0 the angle between d.sub.3 and the vertical of
the reference system (z-direction).
[0035] As an illustration, the agricultural equipment 20 with an
imaginary, fixed, Cartesian coordinate system referred to the
equipment can be defined. The axes of this coordinate system are
referred to as (bx, by, bz). The origin of coordinates (zero point)
of this coordinate system is placed at the location of the GPS
antenna 22. Here it is critical that this coordinate system is
rigidly connected to the equipment, i.e., all horizontal and
vertical changes of location as well as all turning and tilting of
the equipment apply to this coordinate system.
[0036] In the aligned position:
[0037] the coordinate axis (bx) of this coordinate system is
parallel to the W-E direction (x-coordinate axis of terrestrial
reference system),
[0038] the coordinate axis (by) of this coordinate system is
parallel to the N-S direction (y-coordinate axis of terrestrial
reference system),
[0039] the coordinate axis (bz) of this coordinate system is
parallel to the vertical (z-coordinate axis of terrestrial
reference system).
[0040] The equipment-specific base conversion quantities
(X.sub.P0-X.sub.A0; Y.sub.P0-Y.sub.A0; Z.sub.P0-Z.sub.A0;
.phi..sub.0; .alpha..sub.0; .beta..sub.0; d.sub.1, d.sub.2;
d.sub.3) is stored in a memory of a processing unit AWE or in
another memory to which the processing unit has access. The
processing unit may be any type of commercially available processor
capable of making the necessary calculations and storing the result
in memory.
[0041] According to the embodiment of the invention the sensor or
sensors S, S1, S2, S3 each detect a deviation (.phi., .alpha.,
.beta.) of the equipment position from the aligned position which
is described in detail above. The processing unit AWE then
determines with the aid of these deviations (.phi., .alpha.,
.beta.) and by taking into account the equipment-specific base
conversion quantities (.phi..sub.0; .alpha..sub.0; .beta..sub.0;
d.sub.1, d.sub.2; d.sub.3) in each case the current conversion
quantity for finding the coordinates (X.sub.A, Y.sub.A, Z.sub.A) of
the reference point. The reference point 24 is a distance from the
satellite reception unit (i.e. GPS antenna 22) located at position
coordinates (X.sub.P, Y.sub.P, Z.sub.P).
[0042] The absolute position for the location of the GPS antenna 22
is found by a computing algorithm known in the art, which processes
the transmitted data of GPS satellites. This is known to one
skilled in the art and can be done with sufficient precision. The
satellite reception unit (GPS antenna 22) can already include a
processing unit (not shown) which from the GPS transmitted data
already determines position data for the location of the GPS
antenna, from which the position of the reference point is then
found in this processing unit or in a separate processing unit AWE.
It is also within the scope of the invention, however, if only one
processing unit which does not belong directly to the satellite
reception unit is provided, the GPS transmitted data for position
finding of the location of the GPS antenna also being transmitted
to this processing unit.
[0043] In a preferred embodiment of the invention, a transformation
matrix is calculated from the conversion quantities respectively
found according to the invention, and with this transformation
matrix the position vector (X.sub.P, Y.sub.P, Z.sub.P) of the
reference point to be found is determined from the known position
vector (X.sub.A, Y.sub.A, Z.sub.A) of the GPS antenna 22.
[0044] The relevance of the present embodiment will be illustrated
by the concrete example of a combine harvester 20 which is moving
in a S-N direction up a slope inclined by 15%
(.alpha.=8.5.degree.). The equipment-specific base conversions
referred to the aligned position (as described above) of the
combine harvester are a GPS antenna 22 on the top of the combine
harvester at a height of 4 m above the ground, reference point 24
on a cutterbar 26, this being 1 m above the ground, i.e.
.DELTA.Z0=-3 m, also .DELTA.X0=-3.5 m and .DELTA.Y0=-5 m.
[0045] Without taking the inclination of the slope into account
according to the invention, for example according to DE 196 47 523
only the changing position of the GPS antenna 22 would be measured
and for position finding of the reference point .DELTA.Z0=3 m would
always be subtracted from the changing z-coordinate of the GPS
antenna and also .DELTA.Y0=5 m would always be added to the
changing y-coordinate of the GPS antenna. This does not, however,
match the reality; in actual fact the differences are dependent on
the inclination of the slope. In this case for accurately finding
the reference point a difference of .DELTA.Z=2.23 m would have to
be subtracted from the z-coordinate of the GPS antenna and a
difference of .DELTA.Y=5.39 m would have to be subtracted from the
y-coordinate of the GPS antenna. Hence, position finding according
to the state of the art differs by 77 cm for the z-coordinate and
by 39 cm for the y-coordinate from the actual value. These
deviations are greater than the inaccuracy of satellite navigation
itself.
[0046] A detailed deduction of these quantities is given below with
reference to the drawings.
[0047] The embodiment of the invention allows accurate position
finding of a reference point 24 which is spatially at a distance
from the GPS antenna 22, this being for the most varied positions
of an agricultural equipment 20 or implement in the terrestrial
reference system. Thus crop registers and ground height profiles
can be drawn up much more accurately.
[0048] The embodiment of the invention also provides a particular
improvement for automatic steering systems, so that, for example,
the combine harvester 20 can automatically be steered along a
virtual corn edge. The virtual corn edge is derived from previously
recorded reference position data and compared with the measured
current reference position of the edge of the cutterbar 26. From
the deviations of equipment direction and the distance from the
reference point 24, an adjusting signal for the automatic steering
system is determined.
[0049] The embodiment of the invention brings a further advantage
for the control of distributing equipment which is suitable for
dispensing agents, for example sprays or fertilizers, on fields. By
means of a virtual position, automatic working width regulation can
be constructed very easily. The position data of the cutting
boundaries or cutting regions which are not to be supplied with
agents are now prepared according to the working process before
dispensing the agents and transmitted to the implement control
system. If the reference point 24 is placed at the location of the
outermost dispensing position, the working width can be reduced
accordingly if the reference point oversteps the stored cutting
boundaries and be adapted dynamically to the path of the cutting
boundaries. By recording the reference points, a virtual
cultivation edge at which equipment can be automatically steered
along with the aid of the current working width the next time it
moves along can be recorded here, too. If further reference points
are placed, for example in the direction of working, at the
beginning or end of the dispensing region, switching the implement
on or off can be carried out easily.
[0050] The invention can also be used advantageously on
agricultural equipment combinations (e.g. FIG. 11) such as a
tractor 30 with an implement such as, for example, a hitched drawn
fertilizer spreader 32 or a sprayer which can be uncoupled from the
satellite reception antenna in direction or inclination. Then
additional own inclination or direction sensors are mounted on the
implements, determining the alignment of the implement
advantageously at the point of coupling to the tractor. The basic
distance (D) between the virtual reference point and the reception
antenna 22 is then composed of individual partial distances which
are specific to the respective implement and the traction machine
and can be calculated advantageously via a predefined coupling
point between traction machine and implement.
[0051] FIG. 1 shows the combine harvester 20 with hitched cutterbar
26. The GPS antenna 22 is located on the top of the combine
harvester at a height above the ground of about 4 m. The reference
point is placed on the outside of the cutterbar at a height of 1 m
above the ground. This side view shows the combine harvester in the
yz-plane of the terrestrial coordinate system. Also shown is the
imaginary coordinate system rigidly connected to the combine
harvester (bx, by, bz). The distance between the location of the
GPS antenna and the reference point is marked with the reference
symbol (D). In this side view, however, only the projection
(d.sub.2) of the distance line (D) onto the yz-plane can be
shown.
[0052] In FIGS. 2, 4, 6 the combine harvester 20 is shown in each
case in an aligned neutral position in the associated plane. The
views are schematic and not to scale.
[0053] FIG. 2 shows the top view of a combine harvester 20 in an
aligned neutral position. The GPS antenna 22 is located on the top
of the combine harvester. For illustration four GPS satellites are
also shown, from which the GPS antenna can receive satellite
navigation signals. The position shown is selected so that the
longitudinal direction of the equipment is parallel to the N-S
direction (y-coordinate) and the cutterbar is facing north. Of
course a different position can be selected within the scope of the
invention. The choice of this position for easy determination of
the equipment-specific base conversion quantities is merely a
convenience. The aligned position should be chosen, however, taking
into account conventions of the satellite navigation system used,
in such a way that determination of the base conversion quantities
is as easy as possible. The base conversion quantities are referred
to as "equipment-specific" because, when the aligned position is
once fixed by convention, they can be determined unambiguously by
the location of the GPS antenna 22 on the equipment 20 and the
desired position of the reference point 24 for this
"equipment-specific" configuration. The base conversion quantities
can be determined by measurement and/or mathematical
calculations.
[0054] In the example shown in FIG. 2 the difference
(X.sub.P0-X.sub.A0) between the x-coordinate of the reference point
24 and the x-coordinate of the GPS antenna 22 is equal to 3.5 m;
the difference (Y.sub.P0-Y.sub.A0) between the y-coordinate of the
reference point and the y-coordinate of the GPS antenna is equal to
5 m.
[0055] d.sub.1 is the projection of the distance line (D) between
GPS antenna and reference point onto the horizontal plane (x,y).
The same also applies to d.sub.2 and d.sub.3 in relation to the
respective planes.
D={square root}{square root over
((3,5.sup.2+5.sup.2+3.sup.2)m.sup.2)}=6, 8 m
d.sub.1={square root}{square root over
((3,5.sup.2+5.sup.2)m.sup.2)}=6, 1 m
[0056] .phi..sub.0 denotes the angle between d.sub.1 and the N-S
direction/longitudinal direction of the equipment 20.
[0057] .phi..sub.0 is found from:
tan (.phi..sub.0)=tan (3.5/5)=>.phi..sub.0=35.degree..
[0058] .phi..sub.0 and d.sub.1 can, like .alpha..sub.0,
.beta..sub.0, d.sub.2 and d.sub.3, be used as equipment-specific
base conversion quantities.
[0059] FIG. 4 shows the side view (yz-plane) of the combine
harvester 20 in the aligned position. The GPS antenna 22 is located
on the roof of the combine harvester at a height of 4 m, and the
reference point 24 on the cutterbar 26 at a height of 1 m. The
difference (Y.sub.P0-Y.sub.A0) between the y-coordinate of the
reference point and the y-coordinate of the GPS antenna, as can
already be seen from FIG. 2, is equal to 5 m; the difference
(Z.sub.P0-Z.sub.A0) between the z-coordinate of the reference point
and the z-coordinate of the GPS antenna is equal to -3 m.
d.sub.2={square root}{square root over
((3.sup.2+5.sup.2)m.sup.2)}=5, 83 m
[0060] .alpha..sub.0 denotes the angle between d.sub.2 and the
vertical/z-direction.
[0061] .alpha..sub.0 is found from:
tan (.alpha..sub.0)=tan (5/3).fwdarw..alpha..sub.0=59.degree..
[0062] FIG. 6 shows the side view (x,z-plane) of the combine
harvester 20 in the aligned position. The GPS antenna 22 is located
on the top of the combine harvester at a height of 4 m, and the
reference point 24 on the cutterbar 26 at a height of 1 m. The
difference (X.sub.P0-X.sub.A0) between the x-coordinate of the
reference point and the x-coordinate of the GPS antenna, as can
already be seen from FIG. 2, is equal to 3.5 m; the difference
(Z.sub.P0-Z.sub.A0) between the z-coordinate of the reference point
and the z-coordinate of the GPS antenna is equal to -3 m.
d.sub.3={square root}{square root over
((3.sup.2+3,5.sup.2)m.sup.2)}=4, 61 m
[0063] .beta..sub.0 denotes the angle between d.sub.3 and the
vertical/z-direction.
[0064] .beta..sub.0 is found from:
tan (.beta..sub.0)=tan
(3.5/3).fwdarw..beta..sub.0=49.4.degree..
[0065] During use of the combine harvester 20 the deviations
(.phi., .alpha., .beta.) are measured and according to the
embodiment of the invention using the base conversion quantities
described above in each case current conversion quantities are
determined for finding the reference point 24.
[0066] FIG. 3 shows the top view of a combine harvester 20
deviating from the aligned position on a level field. The
corresponding conversion quantities are:
.DELTA.X=d.sub.1 sin (.phi..sub.0-.phi.)
and .DELTA.Y=d.sub.1 cos (.phi..sub.0-.phi.).
[0067] FIG. 5 shows a side view of a combine harvester 20 deviating
from the aligned position, which is going up a slope in a S-N
direction. The corresponding conversion quantities are:
.DELTA.Y=d.sub.2 sin (.alpha..sub.0+.alpha.)
and .DELTA.Z=d.sub.2 cos (.alpha..sub.0+.alpha.).
[0068] A slope with a 15% incline (.alpha.=8.5.degree.) then yields
the values given at the beginning:
.DELTA.Y=5.39 m
and .DELTA.Z=2.23 m.
[0069] FIG. 7 shows a front view of a combine harvester 20
deviating from the aligned position in a S-N direction, which is
inclined along a slope in an E-W direction. The corresponding
conversion quantities are:
.DELTA.X=d.sub.3 sin (.beta..sub.0+.beta.)
and .DELTA.Z=d.sub.3 cos (.beta..sub.0+.beta.).
[0070] Below, the examples described above are shown in vector and
matrix notation, which is solved mathematically.
[0071] General coordinate transformation:
[0072] Finding the position vector (X.sub.P, Y.sub.P, Z.sub.P) of
the reference point 24 from the position vector (X.sub.A, Y.sub.A,
Z.sub.A) of the GPS antenna 22 and the transformation matrix with
the matrix elements (a.sub.ij) as well as the unit vector (1,1,1)
in the Cartesian terrestrial coordinate system: 1 [ X p Y p Z p ] =
[ X A Y A Z A ] + [ a 11 a 12 a 13 a 21 a 22 a 23 a 31 a 32 a 33 ]
[ 1 1 1 ] [ X p Y p Z p ] = [ X A + a 11 + a 12 + a 13 Y A + a 21 +
a 22 + a 23 Z A + a 31 + a 32 + a 33 ]
[0073] Coordinate transformation for the particular position (N-S
alignment, no inclination): 2 [ X p Y p Z p ] = [ X A + 3 , 5 Y A +
5 Z A - 3 ]
[0074] Traveling in the horizontal plane (cf. FIG. 3): 3 [ X p Y p
Z p ] = [ X A Y A Z A ] + [ d 1 sin ( 0 - ) 0 0 0 d 1 cos ( 0 - ) 0
0 0 - 3 ] [ 1 1 1 ] [ X p Y p Z p ] = [ X A + d 1 sin ( 0 - ) Y A +
d 1 cos ( 0 - ) Z A - 3 ]
[0075] Traveling in the N-S direction on a slope inclined in the
direction of travel (cf. FIG. 5): 4 [ X p Y p Z p ] = [ X A Y A Z A
] + [ 3 , 5 0 0 0 d 2 sin ( 0 + ) 0 0 0 - d 2 cos ( 0 + ) ] [ 1 1 1
] [ X p Y p Z p ] = [ X A + 3 , 5 Y A + d 2 sin ( 0 - ) Z A - d 2
cos ( 0 + ) ]
[0076] Traveling in the N-S direction on a slope inclined
transversely to the longitudinal direction of the equipment (cf.
FIG. 7): 5 [ X p Y p Z p ] = [ X A Y A Z A ] + [ d 3 sin ( 0 + ) 0
0 0 5 0 0 0 - d 3 cos ( 0 + ) ] [ 1 1 1 ] [ X p Y p Z p ] = [ Y A +
d 3 sin ( 0 + ) Y A + 5 Z A - d 3 cos ( 0 + ) ]
[0077] The invention is, as already mentioned above, not confined
to finding one reference point 24. On the contrary, it is quite
possible for two or more reference points to be provided. These can
be located within the equipment 20 instead of on the tool, such as
the cutterbar 26. Furthermore, it is provided that the reference
point or points as virtual reference points are located outside the
equipment and outside the attached tool.
[0078] Also according to the invention it is provided that a
reference line, reference area, or reference volume consisting of
two or more reference points can be found. FIG. 8 shows such a
virtual reference area 42 in front of the cutterbar 26.
[0079] Furthermore, it is provided that when the processing unit
AWE finds a virtual reference point 40, it takes into consideration
at least one parameter of the equipment 20, such as the speed of
travel, so that the position of the virtual reference point
relative to the satellite reception unit (GPS antenna) can be
regulated dynamically as a function of at least one parameter. This
is shown with reference to the speed of travel in FIGS. 9 and 10.
It is thus possible to travel at a higher speed in this way,
looking further ahead, so to speak.
[0080] Furthermore, it is provided that whenever the reference
point, which is ahead in the direction of travel, has reached the
end of the field (which can be determined with a stored field
register, for example) certain operations (e.g., lifting cutterbar
26, lifting and turning plow) are triggered automatically with an
adjustable time lag.
[0081] Further, it is provided that at least one position parameter
(relative angle of bending of the trailer to the tractor, relative
height of a three-point hitch, relative feeder housing angle, etc.)
of a cultivation tool mounted on the equipment is taken into
consideration by the processing unit AWE, so that the position of
the virtual reference point 40 relative to the satellite reception
unit (GPS antenna 22) can be regulated dynamically as a function of
this parameter. In FIG. 11, for example, is shown a tractor 30 with
a fertilizer spreader 32. Here it is provided that the position of
the virtual reference point is made dependent on the speed of
rotation of the spreader plates 34, 36 or the working width of the
spreader, so that the reference point 40 is in each case located at
the edge of the spreading range. In order that the theoretical
working width can be determined even more accurately, the position
parameters of the three-point hitch are also taken into
consideration when calculating the reference point.
[0082] In the case of a fertilizer spreader 32 with several
spreader plates 34, 36, if necessary, several corresponding
reference points 40 may exist; individual reference points are
capable of being deactivated and reactivated by the operator of the
equipment. This is perfectly sensible in the case shown with two
spreader plates 34, 36 if, for example, when traveling at the edge
of the field the speed of the spreader plate on the edge side is
first reduced and then shut off, in which case position finding of
the corresponding reference point then also becomes superfluous and
possibly even a nuisance. By including further parameters from the
working process such as, for example, the speed of travel or
fertilizer-specific quantities, the working width of the spreader
can be controlled in such a way that even the flight time of the
product being spread is taken into consideration as well (for
example, for selection of the correct moment to switch the
dispensing device on and off).
[0083] In summary, the method for position finding in the
three-dimensional terrestrial reference system comprises the steps
of: (a) determining the absolute position in the three-dimensional
terrestrial reference system using a satellite reception unit; (b)
determining the distance between the satellite reception unit and a
reference point spatially separate from the location of the
satellite reception unit using at least one sensor; (c) storing
equipment-specific base conversion quantities in memory accessible
by the processing unit; and (d) determining the absolute position
of the reference point with a processing unit and the data received
by the satellite reception unit. The method advantageously includes
determining a transformation matrix from the equipment-specific
conversion quantities, whereby it can determine the position vector
of the reference point from the known position vector of the
satellite reception unit.
[0084] The invention has been described here with reference to a
combine harvester 20 and a hitched fertilizer spreader 32. It is,
however, also clear to one skilled in the art that it can also be
used in other commercial equipment such as construction machinery
which works or converts a ground contour, and it is also applicable
to easily hitched implements which have their own navigation
equipment. Accordingly, the invention in its broader aspects is not
limited to the specific steps and apparatus shown and described,
but departures may be made therefrom within the scope of the
accompanying claims without departing from the principles of the
invention and without sacrificing its chief advantages.
* * * * *