U.S. patent application number 11/509995 was filed with the patent office on 2008-02-28 for excavator 3d integrated laser and radio positioning guidance system.
This patent application is currently assigned to TRIMBLE NAVIGATION LTD.. Invention is credited to Mark E. Nichols.
Application Number | 20080047170 11/509995 |
Document ID | / |
Family ID | 39112027 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080047170 |
Kind Code |
A1 |
Nichols; Mark E. |
February 28, 2008 |
Excavator 3D integrated laser and radio positioning guidance
system
Abstract
An excavator 3D integrated laser and radio positioning guidance
system (Ex_3D_ILRPGS) comprising: a mobile radio positioning system
receiver configured to obtain 2D horizontal coordinates of the
excavator, a bucket-to-machine-body positioning system configured
to obtain coordinates of the boom, the stick and the bucket of the
excavator, a laser detector configured to receive at least one
laser beam and configured to provide a local vertical coordinate
with a substantially high accuracy, and an on-board navigational
system configured to receive and to integrate the 2D horizontal
coordinates of the excavator obtained by the mobile radio
positioning system receiver, the coordinates of the boom, the stick
and the bucket of the excavator obtained by the
bucket-to-machine-body positioning system, and the local vertical
coordinate obtained by the laser detector, and configured to guide
the cutting edge of the bucket of the excavator with substantially
high vertical accuracy.
Inventors: |
Nichols; Mark E.;
(Christchurch, NZ) |
Correspondence
Address: |
THE LAW OFFICES OF BORIS G. TANKHILEVICH
Suite A, 536 N. Civic Drive
Walnut Creek
CA
94597
US
|
Assignee: |
TRIMBLE NAVIGATION LTD.
|
Family ID: |
39112027 |
Appl. No.: |
11/509995 |
Filed: |
August 24, 2006 |
Current U.S.
Class: |
37/348 ;
342/357.28; 342/357.34; 342/357.47; 342/357.52 |
Current CPC
Class: |
G01S 1/70 20130101; G01S
19/45 20130101; G08C 21/00 20130101; G01S 19/51 20130101; E02F
9/264 20130101; G01S 19/14 20130101; G01S 19/10 20130101; E02F
3/435 20130101 |
Class at
Publication: |
37/348 |
International
Class: |
E02F 5/02 20060101
E02F005/02 |
Claims
1. An excavator 3D integrated laser and radio positioning guidance
system (Ex.sub.--3D_ILRPGS); wherein an excavator further
comprises: a frame comprising a cab member horizontally pivoted
about a tread member; a boom pivotally mounted at a proximal end to
said cab by a first pivot means; a stick pivotally mounted at a
proximal end to a distal end of said boom by a second pivot means;
and a bucket pivotally mounted at a proximal end to a distal end of
said stick by a third pivot means; wherein a distal end of said
bucket defines a cutting edge which is used to excavate dirt in
response to movement of said bucket towards said frame; said
Ex.sub.--3D_ILRPGS comprising: a mobile radio positioning system
receiver configured to obtain 2D horizontal coordinates of said
excavator; a bucket-to-machine-body positioning system configured
to obtain position coordinates of said boom, said stick and said
bucket of said excavator; a laser detector configured to receive at
least one laser beam and configured to provide a local vertical
coordinate with a substantially high accuracy; and an on-board
navigational system configured to receive and to integrate said 2D
horizontal coordinates of said excavator obtained by said mobile
radio positioning system receiver, said position coordinates of
said boom, said stick and said bucket of said excavator obtained by
said bucket-to-machine-body positioning system, and said local
vertical coordinate obtained by said laser detector, and configured
to guide said cutting edge of said bucket of said excavator with
substantially high vertical accuracy.
2. The system of claim 1, wherein said mobile radio positioning
system receiver is selected from the group consisting of: {an
autonomous satellite receiver; a Virtual Reference Station
(VRS)-based differential satellite positioning system receiver; a
Wide Area Augmentation Service (WAAS)-based differential satellite
positioning system receiver; a Real Time Kinematic (RTK)-based
satellite positioning system receiver; an Omni STAR-High
Performance (HP)-based differential satellite positioning system
receiver; and a pseudolite receiver}; and wherein said satellite
receiver is selected from the group consisting of: {a Global
Positioning System (GPS) receiver; a GLONASS receiver, a Global
Navigation Satellite System (GNSS) receiver; and a combined
GPS-GLONASS receiver}.
3. The system of claim 1, wherein said bucket-to-machine-body
positioning system is selected from the group consisting of: {a
tilt sensor; an in-cylinder measurement sensor; a potentiometer;
and a cable encoder}.
4. The system of claim 1, wherein said laser detector further
comprises: a single slope planar laser detector configured to
receive a single flat plane laser beam from a single flat plane
laser transmitter.
5. The system of claim 1, wherein said laser detector further
comprises: a single slope planar laser detector configured to
receive a single sloping plane laser beam from a single sloping
plane laser transmitter.
6. The system of claim 1, wherein said laser detector further
comprises: a dual slope planar laser detector configured to receive
a dual slope plane laser beam from a dual slope plane laser
transmitter.
7. The system of claim 1, wherein said laser detector further
comprises: a single sloping fan laser detector configured to
receive a single sloping fan laser beam from a single sloping fan
laser transmitter, wherein said on-board navigational system is
configured to compute the difference in height between said fan
laser transmitter and said fan laser detector to increase the
vertical accuracy of said Ex.sub.--3D_ILRPGS system.
8. The system of claim 1, wherein said laser detector further
comprises: a fan laser detector configured to receive at least two
fan laser beams from a fan laser transmitter; wherein said on-board
navigational system is configured to compute the difference in
height between said fan laser transmitter and said fan laser
detector to increase the vertical accuracy of said
Ex.sub.--3D_ILRPGS system.
9. The system of claim 1 further comprising: an on-board display
system configured to display the movement of said bucket of said
excavator, wherein a vertical coordinate of a cutting edge of said
bucket is displayed with accuracy substantially similar to a
vertical accuracy of said laser beam.
10. The system of claim 9, wherein said on-board navigational
system further comprises: an on-board computer configured to
calculate the difference between an actual position of said cutting
edge of said bucket and a design surface, and wherein said on-board
display system is configured to display said actual position of
said cutting edge of said bucket relative to said design
surface.
11. The system of claim 1, wherein said on-board navigational
system further comprises: an on-board computer configured to
calculate the difference between an actual position of said cutting
edge of said bucket and a design surface, and configured to control
said position of said cutting edge of said bucket by controlling
hydraulics valves configured to operate said cutting edge of said
bucket.
12. The system of claim 1 further comprising: a remotely located
control station configured to remotely operate said excavator; and
a communication link configured to link said remotely located
control station and said on-board navigational system of said
Ex.sub.--3D_ILRPGS system; wherein said on-board navigational
system is configured to transmit an excavator real time positioning
data to said remotely located control station via said
communication link, and wherein said on-board navigational system
is configured to receive at least one control signal from said
remotely located control station via said communication link; and
wherein said wireless communication link is selected from the group
consisting of: {a cellular link; a radio; a private radio band; a
SiteNet 900 private radio network; a wireless Internet; a satellite
wireless communication link; and an optical wireless link}.
13. The system of claim 11, wherein said remotely located control
station further comprises: a display configured to display said
remotely controlled excavator.
14. A method of operating an excavator with substantially high
vertical accuracy by using an Ex.sub.--3D_ILRPGS system; wherein
said excavator further comprises: a frame comprising a cab member
horizontally pivoted about a tread member; a boom pivotally mounted
at a proximal end to said cab by a first pivot means; a stick
pivotally mounted at a proximal end to a distal end of said boom by
a second pivot means; and a bucket pivotally mounted at a proximal
end to a distal end of said stick by a third pivot means; wherein a
distal end of said bucket defines a cutting edge which is used to
excavate dirt in response to movement of said bucket towards said
frame; said Ex.sub.--3D_ILRPGS system comprising: a mobile radio
positioning system receiver, a bucket-to-machine-body positioning
system, a laser detector, and an on-board navigational system; said
method comprising: (A) obtaining 2D horizontal coordinates of said
excavator by using said mobile radio positioning system receiver;
(B) obtaining position coordinates of said boom, said stick and
said bucket of said excavator by utilizing said
bucket-to-machine-body positioning system; (C) obtaining a local
vertical coordinate with a substantially high accuracy by using
said laser detector configured to receive at least one laser beam
from a laser transmitter; (D) receiving and integrating said 2D
horizontal coordinates of said excavator obtained by said mobile
radio positioning system receiver, said position coordinates of
said boom, said stick and said bucket of said excavator obtained by
said bucket-to-machine-body positioning system, and said local
vertical coordinate obtained by said laser detector by using said
on-board navigational system; and (E) guiding said cutting edge of
said bucket of said excavator with substantially high vertical
accuracy by using said on-board navigational system.
15. The method of claim 14, wherein said step (A) of obtaining 2D
horizontal coordinates of said excavator by using said mobile radio
positioning system receiver further comprises: (A1) selecting said
mobile radio positioning system receiver from the group consisting
of: {an autonomous satellite receiver; a Virtual Reference Station
(VRS)-based differential satellite positioning system receiver; a
Wide Area Augmentation Service (WAAS)-based differential satellite
positioning system receiver; a Real Time Kinematic (RTK)-based
satellite positioning system receiver; an Omni STAR-High
Performance (HP)-based differential satellite positioning system
receiver; and a pseudolite receiver}; and (A2) selecting said
satellite receiver from the group consisting of: {a Global
Positioning System (GPS) receiver; a GLONASS receiver, a Global
Navigation Satellite System (GNSS) receiver; and a combined
GPS-GLONASS receiver}.
16. The method of claim 14, wherein said mobile radio positioning
system receiver further comprises a satellite receiver and a
pseudolite receiver; wherein said satellite receiver is configured
to obtain a first horizontal coordinate of said excavator; and
wherein said pseudolite receiver is configured to obtain a second
horizontal coordinate of said excavator; and wherein said step (A)
of obtaining 2D horizontal coordinates of said excavator by using
said mobile radio positioning system receiver further comprises:
(A3) selecting said mobile radio positioning system receiver from
the group consisting of: {an autonomous satellite receiver; a
Virtual Reference Station (VRS)-based differential satellite
positioning system receiver; a Wide Area Augmentation Service
(WAAS)-based differential satellite positioning system receiver; a
Real Time Kinematic (RTK)-based satellite positioning system
receiver; and an Omni STAR-High Performance (HP)-based differential
satellite positioning system receiver}; and (A4) selecting said
satellite receiver from the group consisting of: {a Global
Positioning System (GPS) receiver; a GLONASS receiver, a Global
Navigation Satellite System (GNSS) receiver; and a combined
GPS-GLONASS receiver}.
17. The method of claim 14, wherein said step (B) further
comprises: (B1) selecting said bucket-to-machine-body positioning
system from the group consisting of: {a tilt sensor; an in-cylinder
measurement sensor; a potentiometer; and a cable encoder}.
18. The method of claim 14, wherein said step (C) of obtaining said
local vertical coordinate with said substantially high accuracy
further comprises: (C1) receiving a single slope plane laser beam
from a single slope plane laser transmitter by using a single slope
planar laser detector.
19. The method of claim 14, wherein said step (C) of obtaining said
local vertical coordinate with said substantially high accuracy
further comprises: (C2) receiving a dual slope plane laser beam
from a dual slope plane laser transmitter by using a dual slope
planar laser detector.
20. The method of claim 14, wherein said step (C) of obtaining said
local vertical coordinate with said substantially high accuracy
further comprises: (C3) receiving a single sloping fan laser beam
from a single sloping fan laser transmitter by using a single
sloping fan laser detector.
21. The method of claim 14, wherein said step (C) of obtaining said
local vertical coordinate with said substantially high accuracy
further comprises: (C4) receiving at least two fan laser beams from
a fan laser transmitter by using a fan laser detector; wherein said
on-board navigational system is configured to compute the
difference in height between said fan laser transmitter and said
fan laser detector to increase the vertical accuracy of said
Ex.sub.--3D_ILRPGS system.
22. The method of claim 14, wherein said step (D) further
comprises: (D1) using an on-board computer to calculate the
difference between an actual position of said cutting edge of said
bucket and a design surface.
23. The method of claim 14, wherein said step (E) of guiding said
cutting edge of said bucket of said excavator with substantially
high vertical accuracy further comprises: (E1) using said on-board
navigational system to control said position of said cutting edge
of said bucket by controlling hydraulics valves configured to
operate said cutting edge of said bucket.
24. The method of claim 14, wherein said step (E) of guiding said
cutting edge of said bucket of said excavator with substantially
high vertical accuracy further comprises: (E2) using a remotely
located control station to remotely operate said excavator.
25. The method of claim 14, wherein said step (E) of guiding said
cutting edge of said bucket of said excavator with substantially
high vertical accuracy further comprises: (E3) using a
communication link to link said remotely located control station
and said on-board navigational system of said Ex.sub.--3D_ILRPGS
system; (E4) transmitting an excavator real time positioning data
to said remotely located control station via said communication
link; and (E5) receiving at least one control signal from said
remotely located control station via said communication link.
26. The method of claim 25, wherein said step (E3) further
comprises: (E3, 1) selecting said wireless communication link from
the group consisting of: {a cellular link; a radio; a private radio
band; a SiteNet 900 private radio network; a wireless Internet; a
satellite wireless communication link; and an optical wireless
link}.
27. The method of claim 14 further comprising: (F) displaying the
movement of said bucket of said excavator by using an on-board
display system, wherein a vertical coordinate of a cutting edge of
said bucket is displayed with accuracy substantially similar to a
vertical accuracy of said laser beam.
28. The method of claim 14 further comprising: (H) displaying the
movement of the bucket of the excavator by using a control station
display system, wherein a vertical coordinate of a cutting edge of
said bucket is displayed with accuracy substantially similar to a
vertical accuracy of said laser beam.
29. A method of operating an excavator with improved vertical
accuracy by using an Ex.sub.--3D_ILRPGS system; wherein said
excavator further comprises: a frame comprising a cab member
horizontally pivoted about a tread member; a boom pivotally mounted
at a proximal end to said cab by a first pivot means; a stick
pivotally mounted at a proximal end to a distal end of said boom by
a second pivot means; and a bucket pivotally mounted at a proximal
end to a distal end of said stick by a third pivot means; wherein a
distal end of said bucket defines a cutting edge which is used to
excavate dirt in response to movement of said bucket towards said
frame; said Ex.sub.--3D_ILRPGS system comprising: a mobile radio
positioning system receiver, a bucket-to-machine-body positioning
system, a laser detector, and an on-board navigational system;
wherein 3D coordinates of said excavator are obtained by using said
mobile radio positioning system receiver; and wherein a local
vertical coordinate is obtained with a substantially high accuracy
by using said laser detector configured to receive at least one
laser beam from a laser transmitter; said method comprising: (A)
obtaining 3D coordinates of said excavator by using said mobile
radio positioning system receiver; (B) obtaining position
coordinates of said boom, said stick and said bucket of said
excavator by utilizing said bucket-to-machine-body positioning
system; (C) obtaining a local vertical coordinate with a
substantially high accuracy by using said laser detector configured
to receive at least one laser beam from a laser transmitter; (D)
receiving and integrating said 3D coordinates of said excavator
obtained by said mobile radio positioning system receiver, said
coordinates of said boom, said stick and said bucket of said
excavator obtained by said bucket-to-machine-body positioning
system, and said local vertical coordinate obtained by said laser
detector by using an on-board navigational system in order to
improve vertical accuracy of said mobile radio positioning system
receiver; and (E) guiding said cutting edge of said bucket of said
excavator with improved vertical accuracy by using said on-board
navigational system.
30. The method of claim 29, wherein said mobile radio positioning
system receiver further comprises a satellite receiver and a
pseudolite receiver; wherein said satellite receiver is configured
to obtain at least one coordinate of said excavator; and wherein
said pseudolite receiver is configured to obtain at least one
coordinate of said excavator; and wherein said mobile radio
positioning system receiver is configured to obtain 3D coordinates
of said excavator; and wherein said step (A) of obtaining 3D
coordinates of said excavator by using said mobile radio
positioning system receiver further comprises: (A1) selecting said
mobile radio positioning system receiver from the group consisting
of: {an autonomous satellite receiver; a Virtual Reference Station
(VRS)-based differential satellite positioning system receiver; a
Wide Area Augmentation Service (WAAS)-based differential satellite
positioning system receiver; a Real Time Kinematic (RTK)-based
satellite positioning system receiver; and an Omni STAR-High
Performance (HP)-based differential satellite positioning system
receiver}; and (A2) selecting said satellite receiver from the
group consisting of: {a Global Positioning System (GPS) receiver; a
GLONASS receiver, a Global Navigation Satellite System (GNSS)
receiver; and a combined GPS-GLONASS receiver}.
31. A method of operating an excavator with improved vertical
accuracy by using an Ex.sub.--3D_ILRPGS system and by assigning
weight functions to different measurements; wherein said excavator
further comprises: a frame comprising a cab member horizontally
pivoted about a tread member; a boom pivotally mounted at a
proximal end to said cab by a first pivot means; a stick pivotally
mounted at a proximal end to a distal end of said boom by a second
pivot means; and a bucket pivotally mounted at a proximal end to a
distal end of said stick by a third pivot means; wherein a distal
end of said bucket defines a cutting edge which is used to excavate
dirt in response to movement of said bucket towards said frame;
said Ex.sub.--3D_ILRPGS system comprising: a mobile radio
positioning system receiver, a bucket-to-machine-body positioning
system, a laser detector, and an on-board navigational system; said
method comprising: (A) obtaining a set of 3D coordinates
measurements of said excavator by making a plurality of
measurements by using said mobile radio positioning system
receiver; (B) obtaining position coordinates of said boom, said
stick and said bucket of said excavator by utilizing said
bucket-to-machine-body positioning system; (C) obtaining a set of
local vertical coordinate measurements with a substantially high
accuracy by making a plurality measurements by using said laser
detector configured to receive at least one laser beam from a laser
transmitter; (D) selecting a weight function configured to assign a
3D weight function to said set of 3D measurements obtained by using
said mobile radio positioning system receiver, and configured to
assign a vertical weight function to said set of local vertical
coordinate measurements obtained by using said laser detector; (E)
integrating said set of 3D coordinates measurements of said
excavator with said 3D weight function, and said set of the local
vertical coordinate measurements with said vertical weight function
by using said on-board navigational system in order to improve
vertical accuracy of said mobile radio positioning system receiver;
and (F) guiding said cutting edge of said bucket of said excavator
with improved vertical accuracy by using said on-board navigational
system.
Description
TECHNICAL FIELD
[0001] The current invention relates to position tracking and
machine control systems, and, more specifically, to a combination
of laser systems and radio positioning systems configured to
complement each other in order to optimize the tracking and machine
control capabilities of prior art systems.
BACKGROUND ART
[0002] In recent times there have been advances in the area of
radio ranging or pseudolite machine control systems. However, the
radio ranging or pseudolite machine control systems have limited,
up to centimeter accuracy.
[0003] For example, Trimble introduced a family of machine control
systems including the GCS300 with a single elevation control, the
GCS400 having a dual elevation control, the GCS500 with a cross
slope control, the GCS600 having a cross slope and elevation
control, and finally, the GCS900 that provides a full 3D control up
to centimeter accuracy. In another example, Trimble also introduced
the SiteVision HEX machine control systems. Trimble's version 5.0
SiteVision System comprises a 3D machine guidance and control
system for use on dozers, scrapers, motor graders, compactors, and
excavators. The SiteVision HEX machine control systems use GPS
technology. A GPS receiver installed on the dozer or grader
continually computes the exact position of GPS antennas installed
on each end of the machine's blade. An on-board computer determines
the exact position of each blade tip and compares the positions to
design elevation. It then computes the cut or fills to grade. This
information is displayed on the in-cab screen, and the cut/fill
data is passed to the SiteVision light bars, which guide the
operator up or down for grade and right or left of a defined
alignment.
[0004] In recent times there have been also advances in rotating
laser systems including plane lasers and fan laser systems. Plane
lasers provide a reference plane of light. Fan lasers provide one
or more planes of light that are rotated about an axis, from which
a difference in elevation can be derived. The common technique for
deriving the difference in elevation is by determining the
difference in time between detection of two or more fan beams.
These systems, such as the Trimble Laser Station and Topcon Laser
Zone systems provide accurate, up to millimeters differences in
elevation. For excavators during a digging operation the critical
accuracy is a vertical accuracy.
[0005] What is needed is to combine the radio-ranging systems with
the laser-based systems to provide excavators with up to
millimeters vertical accuracy.
DISCLOSURE OF THE INVENTION
[0006] The present invention provides systems and methods for 3-D
integrated laser and radio positioning and guidance of an
excavator. The excavator comprises: a frame comprising a cab member
horizontally pivoted about a tread member, a boom pivotally mounted
at a proximal end to the cab by a first pivot means, a stick
pivotally mounted at a proximal end to a distal end of the boom by
a second pivot means, and a bucket pivotally mounted at a proximal
end to a distal end of the stick by a third pivot means. A distal
end of the bucket defines a cutting edge which is used to excavate
dirt in response to movement of the bucket towards the frame.
[0007] One aspect of the present invention is directed to an
excavator 3D integrated laser and radio positioning guidance system
(Ex.sub.--3D_ILRPGS).
[0008] In one embodiment, the excavator 3D integrated laser and
radio positioning guidance system (Ex.sub.--3D_ILRPGS) of the
present invention comprises: a mobile radio positioning system
receiver configured to obtain 2D horizontal coordinates of the
excavator; a bucket-to-machine-body positioning system configured
to determine the position coordinates of the boom, the stick and
the bucket of the excavator relative to the machine body; a laser
detector configured to receive at least one laser beam and
configured to provide a local vertical coordinate with a
substantially high accuracy; and an on-board navigational system
configured to receive and to integrate the 2D horizontal
coordinates of the excavator obtained by the mobile radio
positioning system receiver, the position coordinates of the boom,
the stick and the bucket of the excavator obtained by the
bucket-to-machine-body positioning system, and the local vertical
coordinate obtained by the laser detector, and configured to guide
the cutting edge of the bucket of the excavator with substantially
high vertical accuracy.
[0009] In one embodiment of the present invention, the mobile radio
positioning system receiver is selected from the group consisting
of: {an autonomous satellite receiver; a Virtual Reference Station
(VRS)-based differential satellite positioning system receiver; a
Wide Area Augmentation Service (WAAS)-based differential satellite
positioning system receiver; a Real Time Kinematic (RTK)-based
satellite positioning system receiver; an Omni STAR-High
Performance (HP)-based differential satellite positioning system
receiver; and a pseudolite receiver}.
[0010] In one embodiment of the present invention, the satellite
receiver is selected from the group consisting of: {a Global
Positioning System (GPS) receiver; a GLONASS receiver, a Global
Navigation Satellite System (GNSS) receiver; and a combined
GPS-GLONASS receiver}.
[0011] In one embodiment of the present invention, the
bucket-to-machine-body positioning system is selected from the
group consisting of: {an angle (tilt) sensor; an in-cylinder
measurement sensor; a potentiometer sensor; and a cable
encoder}.
[0012] In one embodiment of the present invention, the laser
detector further comprises: a single slope planar laser detector
configured to receive a single slope plane laser beam from a single
slope plane laser transmitter.
[0013] In another embodiment of the present invention, the laser
detector further comprises: a dual slope planar laser detector
configured to receive a dual slope plane laser beam from a dual
slope plane laser transmitter.
[0014] In an additional embodiment of the present invention, the
laser detector further comprises: a single sloping fan laser
detector configured to receive a single sloping fan laser beam from
a single sloping fan laser transmitter.
[0015] Yet, in one more embodiment of the present invention, the
laser detector further comprises: a fan laser detector configured
to receive at least two fan laser beams from a fan laser
transmitter. In this embodiment of the present invention, the
on-board navigational system is configured to compute the
difference in height between the fan laser transmitter and the fan
laser detector to increase the vertical accuracy of the
Ex.sub.--3D_ILRPGS system.
[0016] In one embodiment of the present invention, the on-board
navigational system further comprises: an on-board computer
configured to calculate the difference between an actual position
of the cutting edge of the bucket and a design surface, and
configured to control the position of the cutting edge of the
bucket by controlling hydraulics valves configured to operate the
cutting edge of the bucket.
[0017] In one embodiment, the excavator 3D integrated laser and
radio positioning guidance system (Ex.sub.--3D_ILRPGS) of the
present invention further comprises: an on-board display system
configured to display the movement of the bucket of the excavator,
wherein a vertical coordinate of the cutting edge of the bucket is
displayed with an accuracy substantially similar to a vertical
accuracy of the laser beam.
[0018] In one embodiment, the excavator 3D integrated laser and
radio positioning guidance system (Ex.sub.--3D_ILRPGS) of the
present invention further comprises: a remotely located control
station configured to remotely operate the excavator, and a
communication link configured to link the remotely located control
station and the on-board navigational system of the
Ex.sub.--3D_ILRPGS system. In this embodiment of the present
invention, the on-board navigational system is configured to
transmit an excavator real time positioning data to the remotely
located control station via the communication link, and the
on-board navigational system is configured to receive at least one
control signal from the remotely located control station via the
communication link. The wireless communication link is selected
from the group consisting of: {a cellular link; a radio; a private
radio band; a SiteNet 900 private radio network; a wireless
Internet; a satellite wireless communication link; and an optical
wireless link}.
[0019] In this embodiment of the present invention, the remotely
located control station further comprises: a display configured to
display movements of the bucket of the remotely controlled
excavator.
[0020] Another aspect of the present invention is directed to a
method of operating an excavator with substantially high vertical
accuracy by using an Ex.sub.--3D_ILRPGS system.
[0021] In one embodiment, the method of the present invention
comprises: (A) obtaining 2D horizontal coordinates of the excavator
by using the mobile radio positioning system receiver; (B)
determining the position coordinates of the boom, the stick and the
bucket of the excavator relative to the machine body by using the
bucket-to-machine-body positioning system; (C) obtaining a local
vertical coordinate with a substantially high accuracy by using the
laser detector configured to receive at least one laser beam from a
laser transmitter; (D) receiving and integrating the 2D horizontal
coordinates of the excavator obtained by the mobile radio
positioning system receiver, the position coordinates of the boom,
the stick and the bucket of the excavator obtained by the
bucket-to-machine-body positioning system, and the local vertical
coordinate obtained by the laser detector by using the on-board
navigational system; and (E) guiding the cutting edge of the bucket
of the excavator with substantially high vertical accuracy by using
the on-board navigational system.
[0022] In one embodiment of the present invention, the step (A)
further comprises: (A1) selecting the mobile radio positioning
system receiver from the group consisting of: {an autonomous
satellite receiver; a Virtual Reference Station (VRS)-based
differential satellite positioning system receiver; a Wide Area
Augmentation Service (WAAS)-based differential satellite
positioning system; receiver a Real Time Kinematic (RTK)-based
satellite positioning system receiver; an Omni STAR-High
Performance (HP)-based differential satellite positioning system
receiver; and a pseudolite receiver}. In this embodiment of the
present invention, the step (A) further comprises: (A2) selecting
the satellite receiver from the group consisting of: {a Global
Positioning System (GPS) receiver; a GLONASS receiver, a Global
Navigation Satellite System (GNSS) receiver; and a combined
GPS-GLONASS receiver}.
[0023] In one embodiment of the present invention, wherein the
mobile radio positioning system receiver further comprises a
satellite receiver and a pseudolite receiver; the step (A) further
comprises: obtaining a first horizontal coordinate of the excavator
by using the satellite receiver, and obtaining a second horizontal
coordinate of the excavator by using the pseudolite receiver.
[0024] In one embodiment of the present invention, the step (B)
further comprises: (B1) selecting at least one position sensor from
the group consisting of: {a tilt sensor; an in-cylinder measurement
sensor; a potentiometer; and a cable encoder}.
[0025] In one embodiment of the present invention, the step (C)
further comprises: (C1) receiving a single slope plane laser beam
from a single slope plane laser transmitter by using a single slope
planar laser detector. In another embodiment of the present
invention, the step (C) further comprises: (C2) receiving a dual
slope plane laser beam from a dual slope plane laser transmitter by
using a dual slope planar laser detector. In one more embodiment of
the present invention, the step (C) further comprises: (C3)
receiving a single sloping fan laser beam from a single sloping fan
laser transmitter by using a single sloping fan laser detector.
Yet, in an additional embodiment of the present invention, the step
(C) further comprises: (C4) receiving at least two fan laser beams
from a fan laser transmitter by using a fan laser detector; wherein
the on-board navigational system is configured to compute the
difference in height between the fan laser transmitter and the fan
laser detector to increase the vertical accuracy of the
Ex.sub.--3D_ILRPGS system.
[0026] In one embodiment of the present invention, the step (D)
further comprises: (D1) using an on-board computer to calculate the
difference between an actual position of the cutting edge of the
bucket and a design surface.
[0027] In one embodiment of the present invention, the step (E)
further comprises: (E1) using the on-board navigational system to
control the position of the cutting edge of the bucket by
controlling hydraulics valves configured to operate the cutting
edge of the bucket. In another embodiment of the present invention,
the step (E) further comprises: (E2) using a remotely located
control station to remotely operate the excavator. In one more
embodiment of the present invention, the step (E) further
comprises: (E3) using a communication link to connect the remotely
located control station and the on-board navigational system of the
Ex.sub.--3D_ILRPGS system; (E4) transmitting an excavator real time
positioning data to the remotely located control station via the
communication link; and (E5) receiving at least one control signal
from the remotely located control station via the communication
link. In this embodiment of the present invention, the step (E3)
further comprises: (E3, 1) selecting the wireless communication
link from the group consisting of: {a cellular link; a radio; a
private radio band; a SiteNet 900 private radio network; a wireless
Internet; a satellite wireless communication link; and an optical
wireless link}.
[0028] In one embodiment, wherein the excavator further includes an
on-board display system, the method of the present invention
further comprises: (F) displaying the movement of the bucket of the
excavator by using an on-board display system, wherein a vertical
coordinate of a cutting edge of the bucket is displayed with
accuracy substantially similar to a vertical accuracy of the laser
beam.
[0029] In one embodiment, wherein the remotely located control
station further includes a display system, the method of the
present invention further comprises: (H) displaying the movement of
the bucket of the excavator by using the control station display
system, wherein a vertical coordinate of a cutting edge of the
bucket is displayed with an accuracy substantially similar to a
vertical accuracy of the laser beam.
[0030] One more aspect of the present invention is directed to a
method of operating an excavator with improved vertical accuracy by
using the Ex.sub.--3D_ILRPGS system, wherein 3D coordinates of the
excavator are obtained by using a mobile radio positioning system
receiver; and wherein a local vertical coordinate is obtained with
a substantially high accuracy by using a laser detector configured
to receive at least one laser beam from a laser transmitter.
[0031] In one embodiment, the method of the present invention
comprises: (A) obtaining 3D coordinates of the excavator by using
the mobile radio positioning system receiver; (B) determining the
position coordinates of the boom, the stick and the bucket of the
excavator relative to the machine body by using the
bucket-to-machine-body positioning system; (C) obtaining a local
vertical coordinate with a substantially high accuracy by using the
laser detector configured to receive at least one laser beam from a
laser transmitter; (D) receiving and integrating 3D coordinates of
the excavator obtained by the mobile radio positioning system
receiver, the position coordinates of the boom, the stick and the
bucket of the excavator relative to the machine body obtained by
the bucket-to-machine-body positioning system, and the local
vertical coordinate obtained by the laser detector by using an
on-board navigational system in order to improve vertical accuracy
of the mobile radio positioning system receiver; and (E) guiding
the cutting edge of the bucket of the excavator with improved
vertical accuracy by using the on-board navigational system.
[0032] Yet, one more aspect of the present invention is directed to
a method of operating an excavator with improved vertical accuracy
by using the Ex.sub.--3D_ILRPGS system and by assigning weight
functions to different measurements.
[0033] In one embodiment of the present invention, the method
comprises: (A) obtaining a set of 3D coordinates measurements of
the excavator by making a plurality measurements by using the
mobile radio positioning system receiver; (B) obtaining position
coordinates of the boom, the stick and the bucket of the excavator
by utilizing the bucket-to-machine-body positioning system; (C)
obtaining a set of local vertical coordinate measurements with a
substantially high accuracy by making a plurality measurements by
using the laser detector configured to receive at least one laser
beam from a laser transmitter; (D) selecting a weight function
configured to assign a 3D weight function to the set of 3D
measurements obtained by using the mobile radio positioning system
receiver, and configured to assign a vertical weight function to
the set of local vertical coordinate measurements obtained by using
the laser detector; (E) integrating the set of 3D coordinates
measurements of the excavator with 3D weight function, and the set
of the local vertical coordinate measurements with the vertical
weight function by using the on-board navigational system in order
to improve vertical accuracy of the mobile radio positioning system
receiver; and (F) guiding the cutting edge of the bucket of the
excavator with improved vertical accuracy by using the on-board
navigational system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The accompanying drawings, which are incorporated in and
form a part of this specification, illustrate embodiments of the
invention and, together with the description, serve to explain the
principles of the invention.
[0035] FIG. 1 depicts the excavator 3D integrated laser and radio
positioning guidance system (Ex.sub.--3D_ILRPGS) that utilizes a
plane laser transmitter for the purposes of the present
invention.
[0036] FIG. 2 illustrates the excavator 3D integrated laser and
radio positioning guidance system (Ex.sub.--3D_ILRPGS) that
utilizes a fan laser transmitter for the purposes of the present
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0037] Reference now be made in detail to the preferred embodiments
of the invention, examples of which are illustrated in the
accompanying drawings. While the invention will be described in
conjunction with the preferred embodiments, it will be understood
that they are not intended to limit the invention to these
embodiments. On the contrary, the invention is intended to cover
alternatives, modifications and equivalents, which may be included
within the spirit and scope of the invention as defined by the
appended claims. Furthermore, in the following detailed description
of the present invention, numerous specific-details are set forth
in order to provide a thorough understanding of the present
invention. However, it will be obvious to one of ordinary skill in
the art that the present invention may be practiced without these
specific details. In other instances, well known methods,
procedures, components, and circuits have not been described in
detail as not to unnecessarily obscure aspects of the present
invention.
[0038] Some portions of the detailed descriptions which follow are
presented in terms of a mobile radio positioning system receiver, a
laser-based positioning system, and an on-board navigational
system. These descriptions and representations are the means used
by those skilled in the navigational system arts to most
effectively convey the substance of their work to others skilled in
the art.
[0039] In one embodiment of the present invention, FIG. 1
illustrates an excavator 3D integrated laser and radio positioning
guidance system (Ex.sub.--3D_ILRPGS) 10. A typical excavator 14 (of
FIG. 1) comprises: a frame 33 comprising a cab member 32
horizontally pivoted about a tread member 34, a boom 36 pivotally
mounted at a proximal end to the cab 32 by a first pivot means 42,
a stick 38 pivotally mounted at a proximal end to a distal end of
the boom 36 by a second pivot means 44, and a bucket 40 pivotally
mounted at a proximal end to a distal end of the stick 38 by a
third pivot means 46. A distal end of the bucket 40 defines a
cutting edge 30 which is used to excavate dirt in response to
movement of the bucket 40 towards the frame 33.
[0040] In one embodiment of the present invention, the excavator 3D
integrated laser and radio positioning guidance system
(Ex.sub.--3D_ILRPGS) 10 further comprises: the mobile radio
positioning system receiver 12 configured to obtain 2D horizontal
coordinates of the excavator 14, and the bucket-to-machine-body
positioning system 16 configured to determine the position of the
bucket cutting edge 30 relative to the machine body 33.
[0041] Referring still to FIG. 1, in one embodiment of the present
invention, the excavator 3D integrated laser and radio positioning
guidance system (Ex.sub.--3D_ILRPGS) 10 further comprises: a laser
detector 24 configured to receive at least one laser beam 26 and
configured to provide a local vertical coordinate with a
substantially high accuracy, and an on-board navigational system 28
configured to receive and to integrate the 2D horizontal
coordinates of the excavator obtained by the mobile radio
positioning system receiver 12, the coordinates of the boom 36, the
stick 38 and the bucket 40 of the excavator 14 obtained by the
bucket-to-machine-body positioning system 16, and the local
vertical coordinate obtained by the laser detector 24, and
configured to guide the cutting edge of the bucket 30 of the
excavator 14 with substantially high vertical accuracy.
[0042] In one embodiment of the present invention, the satellite
receiver (not shown) is selected from the group consisting of: {a
Global Positioning System (GPS) receiver; a GLONASS receiver, a
Global Navigation Satellite System (GNSS) receiver; and a combined
GPS-GLONASS receiver}.
[0043] The Global Positioning System (GPS) is a system of satellite
signal transmitters that transmits information from which an
observer's present location and/or the time of observation can be
determined. The GPS system is fully described in the document
ICD-GPS-200: GPS Interface Control Document, ARINC Research, 1997,
GPS Joint Program Office, which is incorporated by reference
herein.
[0044] Another satellite-based navigation system is called the
Global Orbiting Navigational System (GLONASS), which can operate as
an alternative or supplemental system. The GLONASS system was
placed in orbit by the former Soviet Union and now maintained by
the Russian Republic.
[0045] As disclosed in the European Commission "White Paper on
European transport policy for 2010", the European Union will
develop an independent satellite navigation system GALILEO as a
part of a global navigation satellite infrastructure (GNSS).
[0046] Reference to a radio positioning system (RADPS) herein
refers to a Global Positioning System (GPS), to a Global Orbiting
Navigation System (GLONASS), to GALILEO System, and to any other
compatible Global Navigational Satellite System (GNSS)
satellite-based system that provides information by which an
observer's position and the time of observation can be determined,
all of which meet the requirements of the present invention, and to
a ground based radio positioning system such as a system comprising
of one or more pseudolite transmitters.
[0047] After the RADPS receiver determines the coordinates of i-th
satellite by demodulating the transmitted ephemeris parameters, the
RADPS receiver can obtain the solution of the set of the
simultaneous equations for its unknown coordinates (x.sub.0,
y.sub.0, z.sub.0) and for unknown time bias error (cb). The RADPS
receiver can also determine velocity of a moving platform.
[0048] Referring still to FIG. 1, in one embodiment of the present
invention, the mobile radio positioning system receiver 12 is
selected from the group consisting of: {an autonomous satellite
receiver; a Virtual Reference Station (VRS)-based differential
satellite positioning system receiver; a Wide Area Augmentation
Service (WAAS)-based differential satellite positioning system
receiver; a Real Time Kinematic (RTK)-based satellite positioning
system receiver; an Omni STAR-High Performance (HP)-based
differential satellite positioning system receiver; and a
pseudolite receiver}.
[0049] In one embodiment, the mobile radio positioning system
receiver 12 (of FIG. 1) comprises a differential GPS receiver. In
differential position determination, many of the errors in the
RADPS signals that compromise the accuracy of absolute position
determination are similar in magnitude for stations that are
physically close. The effect of these errors on the accuracy of
differential position determination is therefore substantially
reduced by a process of partial error cancellation. Thus, the
differential positioning method is far more accurate than the
absolute positioning method, provided that the distances between
these stations are substantially less than the distances from these
stations to the satellites, which is the usual case. Differential
positioning can be used to provide location coordinates and
distances that are accurate to within a few centimeters in absolute
terms. The differential GPS receiver can include: (a) a real time
code differential GPS; (b) a post-processing differential GPS; (c)
a real-time kinematic (RTK) differential GPS that includes a code
and carrier RTK differential GPS receiver.
[0050] The differential GPS receiver can obtain the differential
corrections from different sources. Referring still to FIG. 1, in
one embodiment of the present invention, the differential GPS
receiver 12 can obtain the differential corrections from a Base
Station (not shown).
[0051] The fixed Base Station (BS) placed at a known location
determines the range and range-rate measurement errors in each
received GPS signal and communicates these measurement errors as
corrections to be applied by local users. The Base Station (BS) has
its own imprecise clock with the clock bias CBBASE. As a result,
the local users are able to obtain more accurate navigation results
relative to the Base Station location and the Base Station clock.
With proper equipment, a relative accuracy of 5 meters should be
possible at distances of a few hundred kilometers from the Base
Station.
[0052] Referring still to FIG. 1, in one embodiment of the present
invention, the mobile radio positioning system receiver 12 can be
implemented by using a TRIMBLE Ag GPS-132 receiver that obtains the
differential corrections from the U. S. Cost Guard service free in
300 kHz band broadcast by using the wireless communication device
(not shown) and the wireless communication link (not shown). In
this embodiment, the mobile radio positioning system receiver 12
should be placed within (2-300) miles from the U.S. Cost Guard Base
Station. The accuracy of this differential GPS method is about 50
cm.
[0053] Referring still to FIG. 1, in one embodiment of the present
invention, the differential corrections can be obtained from the
Wide Area Augmentation System (WAAS). The WAAS system includes a
network of Base Stations that uses satellites (initially
geostationary satellites-GEOs) to broadcast GPS integrity and
correction data to GPS users. The WAAS provides a ranging signal
that augments the GPS, which is the WAAS ranging signal is designed
to minimize the standard GPS receiver hardware modifications. The
WAAS ranging signal utilizes the GPS frequency and GPS-type of
modulation, including only a Coarse/Acquisition (C/A) PRN code. In
addition, the code phase timing is synchronized to GPS time to
provide a ranging capability. To obtain the position solution, the
WAAS satellite can be used as any other GPS satellite in satellite
selection algorithm. The WAAS provides the differential corrections
free of charge to a WAAS-compatible user. The accuracy of this
method is better than 1 meter.
[0054] Referring still to FIG. 1, in one embodiment of the present
invention, the mobile radio positioning system receiver 12
comprising a real time kinematic (RTK) differential GPS receiver
can be used to obtain the position locations with less than 2 cm
accuracy. RTK is a process where GPS signal corrections are
transmitted in real time from a reference receiver at a known
location to one or more remote rover receivers. The use of an RTK
capable GPS system can compensate for atmospheric delay, orbital
errors and other variables in GPS geometry, increasing positioning
accuracy up to within a centimeter. Used by engineers,
topographers, surveyors and other professionals, RTK is a technique
employed in applications where precision is paramount. RTK is used,
not only as a precision positioning instrument, but also as a core
for navigation systems or automatic machine guidance, in
applications such as civil engineering and dredging. It provides
advantages over other traditional positioning and tracking methods,
increasing productivity and accuracy. Using the code phase of GPS
signals, as well as the carrier phase, which delivers the most
accurate GPS information, RTK provides differential corrections to
produce the most precise GPS positioning. The RTK process begins
with a preliminary ambiguity resolution. This is a crucial aspect
of any kinematic system, particularly in real-time where the
velocity of a rover receiver should not degrade either the
achievable performance or the system's overall reliability. Please,
see U.S. Pat. No. 5,602,741.
[0055] Referring still to FIG. 1, in one embodiment of the present
invention, the mobile radio positioning system receiver 12
comprising a differential GPS receiver can obtain the differential
corrections from the Virtual Base Station (VBS) (not shown)by using
the wireless communication device (not shown) and the wireless
communication link (not shown).
[0056] Indeed, the Virtual Base Station (VBS) is configured to
deliver a network-created correction data to a multiplicity of
rovers via a concatenated communications link consisting of a
single cellular connection, and a radio transmission or
broadcasting system. The location of the radio transmitting system
can be co-located with a GPS Base Station designated as the
position of the local Virtual Reference Station. This GPS Base
Station determines its position using GPS, and transmits its
location to the VRS Base Station via a cellular link between the
local GPS Base Station and the VRS Base Station. It enables the VRS
Base Station to generate differential corrections as if such
differential corrections were actually being generated at the real
GPS Base Station location. An article "Long-Range RTK Positioning
Using Virtual Reference Stations," by Ulrich Vollath, Alois Deking,
Herbert Landau, and Christian Pagels, describing VRS in more
details, is incorporated herein as a reference in its entirety, and
can be accessed at the following URL:
http://trl.trimble.com/dscgi/ds.py/Get/File-93152/KIS2001-Paper-LongRange-
.pdf.
[0057] Referring still to FIG. 1, in one embodiment of the present
invention, the mobile radio positioning system receiver 12 can be
implemented by using the Trimble.RTM. AgGPS.RTM. EZ-Guide.RTM. 252
system that combines the EZ-Guide Plus light bar guidance system
with the AgGPS 252 multi-function receiver. The EZ-Guide 252 light
bar guidance system would enable an excavator operator to choose
the required level of GPS accuracy to manually steer an excavator.
To achieve better than 2-inch accuracy one can use the Omni STAR
High Performance (HP) satellite services.
[0058] The Omni STAR-HP (High Performance) solution is a dual
frequency GPS augmentation service that provides robust and
reliable high performance GPS positioning. By using dual frequency
GPS observations, Omni STAR-HP can measure the true ionospheric
error at the reference station and user location, substantially
eliminating this effect in positioning accuracy. Using these
iono-free measurements with other information contained in the GPS
receiver carrier phase data, the OmniSTAR-HP solution is able to
create a wide area positioning solution of unmatched accuracy and
performance in selected areas. Published accuracies are 0.2 meter
horizontal (Hz) and 0.3 meter vertical (Z).
[0059] Referring still to FIG. 1, in one embodiment of the present
invention, the mobile radio positioning system receiver 12 can be
implemented by using a pseudolite. The pseudolite comprises a
ground based radio positioning system working in any radio
frequency including but not limited to the GPS frequencies and the
ISM (industrial scientific medical) unlicensed operation band,
including 900 MHZ, 2.4 GHz, or 5.8 GHz bands ISM bands, or in a
radio location band such as the (9.5-10) GHz band. Pseudolites can
be used for enhancing the GPS by providing increased accuracy,
integrity, and availability. The complete description of the
pseudolite transmitters in GPS band can be found in `Global
Positioning System: Theory and Applications; Volume II", edited by
Bradford W. Parkinson and James J. Spilker Jr., and published in
Volume 164 in "PROGRESS IN ASTRONAUTICS AND AERONAUTICS", by
American Institute of Aeronautic and Astronautics, Inc., in 1966.
For the purposes of the present invention, the pseudolite
manufactured by Locata (Canberra, Australia) and Novariant (Menlo
Park, Calif.) can be used.
[0060] Referring still to FIG. 1, in one embodiment of the present
invention, the mobile radio positioning system receiver 12 mobile
radio positioning system can be implemented by using a combination
of a satellite receiver (not shown) configured to receive the
satellite signals from a plurality of visible satellites, and a
pseudolite receiver (not shown) configured to receive the
pseudolite signals from a plurality of available pseudolites in
order to obtain the position coordinates of the excavator 14.
Pseudolites as radio positioning systems can be configured to
operate in ISM band. Thus, in this embodiment, the user can own
both ends of the ISM communication system, including 900 MHZ, 2.4
GHz, or 5.8 GHz bands. The ISM technologies are manufactured by
Trimble Navigation Limited, Sunnyvale, Calif. Metricom, Los Gatos,
Calif. and by Utilicom, Santa Barbara, Calif.
[0061] The following discussion is focused on a GPS receiver,
though the same approach can be used for a GLONASS receiver, for a
GPS/GLONASS combined receiver, GALILEO receiver, or any other RADPS
receiver.
[0062] Referring still to FIG. 1, in one embodiment of the present
invention, the bucket-to-machine-body positioning system 16 is
configured to determine the position of the bucket cutting edge 30
relative to the machine body 33. This can be done using a plurality
of different methods.
[0063] In one embodiment of the present invention, the
bucket-to-machine-body positioning system 16 is configured to
determine the position of the bucket cutting edge 30 relative to
the machine body 33 by using the tilt (angle) sensor 18 attached to
the boom 36, the tilt (angle) sensor 20 attached to the stick 38,
and the tilt (angle) sensor 22 attached to the bucket 40.
[0064] A tilt sensor manufactured by SignalQuest, Inc., located in
Lebanon, N.H., 03766, USA, can be used for the purposes of the
present invention. SignalQuest, Inc. manufactures embedded
micro-sensors. For instance, the SQ-SEN-001P series sensors produce
continuous on-off contact closures when in motion. When at rest, it
will either settle in an open or closed state. It is sensitive to
both tilt (static acceleration) and vibration (dynamic
acceleration). The sensor can be easily used to produce a series of
CMOS or TTL level logic pulses using a single resistor to limit
current. This signal can be used to interrupt (wake up) a
microcontroller or can be counted to estimate the amount and
duration of activity. The sensor is fully passive, requires no
signal conditioning, and can be easily used in a microcontroller
interrupt circuit that draws 0.25 uA of continuous current. Another
sensor manufactured by SignalQuest, Inc. is the SQ-SI-360DA
Solid-State MEMS Inclinometer. SQ-SI-360DA Solid-State MEMS
Inclinometer provides both an analog voltage output and digital
serial output corresponding directly to a full-scale range of
360.epsilon.c of pitch angle or +80.epsilon.c of pitch and roll
angle.
[0065] In one embodiment of the present invention, the
bucket-to-machine-body positioning system 16 is configured to
determine the position of the bucket cutting edge 30 relative to
the machine body 33 by using cable encoders (not shown) that
measure the extension of the hydraulic rams. Trimble Navigation LTD
manufactures CE21 that uses cable encoders.
[0066] A cable encoder for the purposes of the present invention
can be implemented by using an optical incremental encoder. Optical
incremental encoder is a linear/angular position sensor that uses
light and optics to sense motion. Optical encoders can provide
position information at high speeds. Most rotary optical encoders
consist of a glass disk with equally spaced markings, a light
source mounted on one side of the disk, and a photo detector
mounted on the other side. The components of rotary optical
encoders are typically packaged in a rugged enclosed housing
protecting the light path and electronics from dust and other
materials frequently present in hostile industrial environments.
When the disk rotates, the markings on the disk temporarily obscure
the passage of light causing the encoder to output a pulse. The
number of pulses generated by the encoder per revolution dictates
the resolution of the encoder. The resolution of encoders (their
PPR, pulses per revolution), typically ranges from a few PPR to as
high as a few hundred thousand PPR. Because the markings on the
disk are uniformly distributed, encoders always generate a pulse in
response to a known incremental move in position. Subsequently, the
position of an object can be measured by connecting the output of
an encoder to a counter that increments or decrements every time
the encoder generates a pulse. The value of the counter indicates
the position of the object quantized to the resolution of the
encoder. That is, if an encoder generates 10 pulses per revolution,
the resolution of the position measurement can be no better than
1/10 th of a revolution.
[0067] To detect the direction of motion and increase the effective
resolution of the encoder, a second photo detector is added and a
mask is inserted between the glass disk and the photo detectors
(not illustrated). The two photo detectors and the mask are
arranged so that two sine waves (which are out of phase by
90.degree.) are generated as the encoder shaft is rotated. These
quadrature signals as they are called are either sent out of the
encoder directly as analog sine wave signals or squared using
comparators to produce digital outputs. To increase the resolution
of the encoder, a method called interpolation is applied to either
or both the sine wave or square wave outputs. Interpolation
typically results in an increased encoder resolution of 2 to 25
times the fundamental resolution of the glass disk. Direction is
derived by simply looking at the timing of the quadrature signals
from the encoder.
[0068] A variation on the standard rotary encoder is the hollow
shaft encoder. Hollow shaft encoders are self contained encoders
without a shaft. Instead of coupling to a shaft to measure
position, hollow shaft encoders simply mount over the shaft to be
measured. Subsequently, hollow shaft encoders eliminate the
resonance associated with couplings and simplify the difficulties
of alignment. Linear optical encoders sense linear motion. Linear
encoders replace the rotating disk with a stationary scale marked
at equally spaced intervals. The scale of a linear encoder can be
constructed from glass, metal or tape (metal, plastic . . . ). The
markings on the scale are read with a moving head assembly that
contains the light source and photo detectors. The resolution of a
linear encoder is specified in units of distance and is dictated by
the distance between markings. Linear encoders are available in
lengths from several centimeters to hundreds of meters and
resolutions as low as a micron (or less).
[0069] The laser optical encoder is another type of motion sensor.
Although these devices use a different measurement approach
internally, they offer the same functionality as standard encoders.
Of the variety of motion sensors available, encoders provide the
best accuracy and speed for a reasonable price and are readily
available from numerous manufacturers.
[0070] In one embodiment of the present invention, the
bucket-to-machine-body positioning system 16 is configured to
determine the position of the bucket cutting edge 30 relative to
the machine body 33 by using the position sensing cylinders
(in-cylinder measurement) where the length of the cylinder is
determined by using methods like time of flight or other methods to
measure the distance from one end of the cylinder to the other.
[0071] In one embodiment of the present invention, the
bucket-to-machine-body positioning system 16 is configured to
determine the position of the bucket cutting edge 30 relative to
the machine body 33 by using a potentiometer which is a type of
bridge circuit for measuring voltages. The original potentiometers
are divided into four main classes: the constant resistance
potentiometer, the constant current potentiometer, the microvolt
potentiometer and the thermocouple potentiometer.
[0072] There are also systems in development that use a mix, for
example a potentiometer on the boom, a tilt sensor on the stick
(with integrated laser detector) and a position sensing cylinder on
the bucket. Manufacturers of "bucket to machine body" sub systems
include Mikrofyn, Prolec, Axiomatic and Trimble.
[0073] Referring still to FIG. 1, in one embodiment of the present
invention, the laser detector 24 further comprises: a single slope
planar laser detector configured to receive a single slope plane
laser beam 26 from a single slope plane laser transmitter 50. A
similar single slope plane laser transmitter product such as the
GL700 is manufactured by Trimble.
[0074] More specifically, according to the U.S. Pat. No. 6,433,866,
the laser transmitter 50 (of FIG. 1) includes a rotating laser
system (not shown). In a rotating laser system a laser source spins
(mechanically, or optically) in the horizontal plane (or Z-plane).
The rotating laser emits a laser beam that provides an accurate
reference plane with millimeter accuracy. However, to detect and
get benefit of the rotating laser beam, the potential user has to
be located within vertical range, and be equipped with laser
detector (or laser receiver) capable of receiving the rotating
laser beam. In the mechanical embodiment, the motor physically
rotates the laser and accordingly the laser beam. In the optical
embodiment, the mirror rotates in such a way that the physically
non-rotating laser emits the rotating laser beam.
[0075] In another embodiment of the present invention, referring
still to FIG. 1, the laser detector 24 further comprises: a dual
slope planar laser detector configured to receive a dual slope
plane laser beam (not shown) from a dual slope plane laser
transmitter 50.
[0076] In one embodiment of the present invention, FIG. 2
illustrates excavator 3D integrated laser and radio positioning
guidance system (Ex.sub.--3D_ILRPGS) 70 that utilizes a fan laser
transmitter 72. In this embodiment of the present invention, the
laser detector 78 further comprises a single sloping fan laser
detector configured to receive a single sloping fan laser beam 76
(or 74) from the single sloping fan laser transmitter 72. The
detailed description of such fan laser transmitter 72 is given in
the copending published US patent application US-2006-0012777
entitled "COMBINATION LASER SYSTEM AND GLOBAL NAVIGATION SATELLITE
SYSTEM" that is incorporated by reference herein in its entirety.
The copending US patent application US-2006-0012777 is assigned to
the assignee of the present patent application.
[0077] Referring still to FIG. 2, in one embodiment of the present
invention, the laser detector 78 further comprises a fan laser
detector configured to receive at least two fan laser beams (74 and
76) from the fan laser transmitter 72. In this embodiment of the
present invention, the on-board navigational system 80 is
configured to compute the difference in height between the fan
laser transmitter 72 and the fan laser detector 78 to increase the
vertical accuracy of the Ex.sub.--3D_ILRPGS system. Trimble
Navigation Ltd. manufactures 3D Laser Station 72 that generates two
rotating fan-shaped laser beams 74 and 76 (of FIG. 2).
[0078] In one embodiment of the present invention, the on-board
navigational system (28 of FIG. 1, or 80 of FIG. 2) further
comprises an on-board computer (not shown) configured to calculate
the difference between an actual position of the cutting edge of
the bucket (30 of FIG. 1, or 82 of FIG. 2) and a design surface
(not shown), and configured to control the position of the cutting
edge of the bucket by controlling hydraulics valves (47 of FIG. 1
or 84 of FIG. 2) configured to operate the cutting edge of bucket
(30 of FIG. 1, or 82 of FIG. 2).
[0079] In one embodiment, the excavator 3D integrated laser and
radio positioning guidance system (Ex.sub.--3D_ILRPGS) of the
present invention further comprises: an on-board display system (29
of FIG. 1, or 86 of FIG. 2) configured to display the movement of
the bucket (40 of FIG. 1, or 83 of FIG. 2) of the excavator. A
vertical coordinate of the cutting edge of the bucket (30 of FIG.
1, or 82 of FIG. 2) is displayed with accuracy substantially
similar to a vertical accuracy of the laser beam (26 of FIG. 1, or
74, 76 of FIG. 2).
[0080] In one embodiment, the excavator 3D integrated laser and
radio positioning guidance system (Ex.sub.--3D_ILRPGS) of the
present invention further comprises: a remotely located control
station (60 of FIG. 1, or 88 of FIG. 2) configured to remotely
operate the excavator, and a communication link (62 of FIG. 1, or
90 of FIG. 2) configured to link the remotely located control
station and the on-board navigational system of the
Ex.sub.--3D_ILRPGS system. In this embodiment of the present
invention, the on-board navigational system is configured to
transmit an excavator real time positioning data to the remotely
located control station via the communication link, and the
on-board navigational system is configured to receive at least one
control signal from the remotely located control station via the
communication link. The wireless communication link (62 of FIG. 1,
or 90 of FIG. 2) is selected from the group consisting of: {a
cellular link; a radio; a private radio band; a SiteNet 900 private
radio network; a wireless Internet; a satellite wireless
communication link; and an optical wireless link}.
[0081] In one embodiment of the present invention, referring still
to FIG. 1, the remotely located control station 60 further
comprises a display 64 configured to display movements of the
bucket 40 of the remotely controlled excavator. Similarly, as shown
in FIG. 2, the remotely located control station 88 further
comprises a display 92 configured to display movements of the
bucket 83 of the remotely controlled excavator.
[0082] In one embodiment of the present invention, the wireless
communication link (62 of FIG. 1, or 90 of FIG. 2) can be
implemented by using the Trimble SiteNet.TM. 900 private radio
network. The Trimble SiteNet.TM. 900 private radio network is a
rugged, multi-network, 900 MHz radio modem designed specifically
for the construction and mining industries. It is used to establish
robust, wireless data broadcast networks for real-time,
high-precision GPS applications. This versatile Trimble radio
operates in the frequency range of 902-928 MHz, broadcasting,
repeating, and receiving real-time data used by Trimble GPS
receivers. Under optimal conditions, the SiteNet 900 radio
broadcasts data up to 10 km (6.2 miles) line-of-sight and coverage
can be enhanced by using a network of multi-repeaters. Using the
SiteNet 900 radio as a repeater, enables one to provide coverage in
previously inaccessible or obstructed locations. The SiteNet 900
radio is so versatile, that one can easily change its operating
mode to suit any network configuration. This reduces costs and
maximizes uptime. Additionally, SiteNet 900 is license free in the
U.S.A. and Canada, which makes it extremely portable. One can move
it from project to project without licensing hassles and
restrictions. The SiteNet 900 radio is designed to operate reliably
in demanding RF environments where many other products and
technologies cannot. Optimized for GPS with increased sensitivity
and jamming immunity, the SiteNet 900 radio also has error
correction, and a high-speed data rate, ensuring maximum
performance. The SiteNet 900 radio is especially suited for use
with Trimble's SiteVision.TM. GPS grade control system, and is
ideal for all GPS machine control applications where reliability is
important. The machine-rugged unit has been designed and built
especially for harsh construction and mining environments. Fully
sealed against dust, rain, splash, and spray, the SiteNet 900 radio
remains reliable in all weather. The radio's ruggedness and
reliability minimizes downtime, lowering ownership costs. Trimble's
SiteNet 900 radio can be used with any Trimble GPS receiver,
including: MS750, MS850, MS860, and 5700, receivers.
[0083] In one embodiment of the present invention, the wireless
communication link (62 of FIG. 1, or 90 of FIG. 2) can be
implemented by using a 1.8 GHz band that supports the personal
communications services (PCS). The PCS uses the international
standard DCS-1800. Yet, in one more embodiment, the wireless
communication link can include a real time circuit switched
wireless communication link. For instance, the wireless
communication link employing a real time circuit switched wireless
communication link can include the Iridium satellite system
produced by Motorola, Schaumburg, Ill.
[0084] In one additional embodiment, the wireless communication
link (62 of FIG. 1, or 90 of FIG. 2) can be implemented by using a
system of Low Earth Orbiting Satellites (LEOS), a system of Medium
Earth Orbiting Satellites (MEOS), or a system of Geostationary
Earth Orbiting Satellites (GEOS) which can be used to store and to
forward digital packet data. For instance, the LEOS systems in
(20-30) GHz range are manufactured by Cellular Communications
located in Redmond, Wash., and the LEOS systems in (1.6-2.5) GHz
range are produced by Loral/Qualcomm located in San Diego,
Calif.
[0085] The wireless communication link (62 of FIG. 1, or 90 of FIG.
2) for the purposes of the present invention can be implemented by
using a cellular telephone communication means, a paging signal
receiving means, wireless messaging services, wireless application
services, a wireless WAN/LAN station, or an Earth-satellite-Earth
communication module that uses at least one satellite to relay a
radio wave signal. The wireless communication link can also include
the cellular telephone communication means that can include an
Advanced Mobile Phone System (AMPS) with a modem. The modem can
comprise a DSP (digital signal processor) modem in 800 MHZ range,
or a cellular digital packet data (CDPD) modem in 800 MHZ range.
The cellular digital communication means includes a means of
modulation of digital data over a radio link using a time division
multiple access (TDMA) system employing format IS-54, a code
division multiple access (CDMA) system employing format IS-95, or a
frequency division multiple access (FDMA). The TDMA system used in
Europe is called groupe special mobile (GSM) in French.
[0086] In one embodiment of the present invention, a cellular
telephone communication means can be used to get a wireless access
to the Internet in order, for example, to broadcast the real time
coordinates of the self-surveying laser transmitter position on a
special web-site.
[0087] The wireless communication device (63 of FIG. 1, or 94 of
FIG. 2) for the purposes of the present invention can be
implemented by using any of devices that can be configured to
provide: {a cellular link; a radio link; a private radio band link;
a SiteNet 900 private radio network link; a link to the wireless
Internet; and a satellite wireless communication link}. A person
skillful in the art can easily identify all these devices. Please,
see the discussion above.
[0088] In one embodiment of the present invention, the wireless
communication device (63 of FIG. 1, or 94 of FIG. 2) is configured
to respond to specific requests from a mobile equipment (not shown)
transmitted over the wireless communication link (62 of FIG. 1, or
90 of FIG. 2).
[0089] Another aspect of the present invention is directed to a
method of operating an excavator with substantially high vertical
accuracy. The method of the present invention can be performed by
using the excavator 3D integrated laser and radio positioning
guidance system (Ex.sub.--3D_ILRPGS) 10 of FIG. 1 that is
configured to receive a laser bean from the plane laser 50, or by
using the excavator 3D integrated laser and radio positioning
guidance system (Ex.sub.--3D_ILRPGS) 70 of FIG. 2 that is
configured to receive receives at least one fan laser bean from the
fan laser 72.
[0090] In one embodiment, the method of the present invention
comprises (not shown): (A) obtaining 2D horizontal coordinates of
the excavator by using the mobile radio positioning system receiver
(12 of FIG. 1, or 96 of FIG. 2); (B) obtaining position coordinates
of the boom, the stick and the bucket of the excavator by utilizing
the bucket-to-machine-body positioning system (16 of FIG. 1, or 98
of FIG. 2); (C) obtaining a local vertical coordinate with a
substantially high accuracy by using the laser detector (24 of FIG.
1, or 78 of FIG. 2) configured to receive at least one laser beam
from the laser transmitter (50 of FIG. 1, or 72 of FIG. 2); (D)
receiving and integrating the 2D horizontal coordinates of the
excavator obtained by the mobile radio positioning system receiver,
the position coordinates of the boom, the stick and the bucket of
the excavator obtained by the bucket-to-machine-body positioning
system, and the local vertical coordinate obtained by the laser
detector by using the on-board navigational system (28 of FIG. 1,
or 80 of FIG. 2); and (E) guiding the cutting edge (30 of FIG. 1,
or 82 of FIG. 2) of the bucket of the excavator with substantially
high vertical accuracy by using the on-board navigational system
(28 of FIG. 1, or 80 of FIG. 2).
[0091] In one embodiment of the present invention, the step (A)
further comprises (not shown, please see discussion above): (Al)
selecting the mobile radio positioning system receiver (12 of FIG.
1, or 96 of FIG. 2) from the group consisting of: {an autonomous
satellite receiver; a Virtual Reference Station (VRS)-based
differential satellite positioning system receiver; a Wide Area
Augmentation Service (WAAS)-based differential satellite
positioning system receiver; a Real Time Kinematic (RTK)-based
satellite positioning system receiver; an Omni STAR-High
Performance (HP)-based differential satellite positioning system
receiver; and a pseudolite receiver}. In this embodiment of the
present invention, the step (A) further comprises (not shown,
please see discussion above): (A2) selecting the satellite receiver
(12 of FIG. 1, or 96 of FIG. 2) from the group consisting of: {a
Global Positioning System (GPS) receiver; a GLONASS receiver, a
Global Navigation Satellite System (GNSS) receiver; and a combined
GPS-GLONASS receiver}.
[0092] In one embodiment of the present invention, wherein the
mobile radio positioning system receiver (12 of FIG. 1, or 96 of
FIG. 2) further comprises a satellite receiver and a pseudolite
receiver; the step (A) further comprises: obtaining a first
horizontal coordinate of the excavator by using the satellite
receiver, and obtaining a second horizontal coordinate of the
excavator by using the pseudolite receiver.
[0093] In one embodiment of the present invention, the step (B)
further comprises: (B1) selecting the bucket-to-machine-body
positioning system (16 of FIG. 1, or 98 of FIG. 2) from the group
consisting of: {a tilt sensor; an in-cylinder measurement sensor;
and a cable encoder}. Please, see discussion above.
[0094] In one embodiment of the present invention, more
specifically, the step (C) of obtaining the local vertical
coordinate with substantially high accuracy further comprises: (C1)
receiving the single slope plane laser beam (26 of FIG. 1) from the
single slope plane laser transmitter (50 of FIG. 1) by using the
single slope planar laser detector (24 of FIG. 1).
[0095] In one embodiment of the present invention, more
specifically, the step (C) of obtaining the local vertical
coordinate with substantially high accuracy further comprises: (C2)
receiving the dual slope plane laser beam (not shown) from the dual
slope plane laser transmitter (50 of FIG. 1) by using the dual
slope planar laser detector (24 of FIG. 1).
[0096] In one embodiment of the present invention, more
specifically, the step (C) of obtaining the local vertical
coordinate with substantially high accuracy further comprises: (C3)
receiving the single sloping fan laser beam (76 of FIG. 2) from the
single sloping fan laser transmitter (72 of FIG. 2) by using the
single sloping fan laser detector (78 of FIG. 2).
[0097] In one embodiment of the present invention, more
specifically, the step (C) of obtaining the local vertical
coordinate with substantially high accuracy further comprises: (C4)
receiving at least two fan laser beams (74 and 76 of FIG. 2) from
the fan laser transmitter (72 of FIG. 2) by using the fan laser
detector (78 of FIG. 2), wherein the on-board navigational system
(80 of FIG. 2) is configured to compute the difference in height
between the fan laser transmitter (72 of FIG. 2) and the fan laser
detector (78 of FIG. 2) to increase the vertical accuracy of the
Ex.sub.--3D_ILRPGS system.
[0098] In one embodiment of the present invention, the step (D) of
receiving and integrating the 2D horizontal coordinates of the
excavator obtained by the mobile radio positioning system receiver,
the position coordinates of the boom, the stick and the bucket of
the excavator obtained by the bucket-to-machine-body positioning
system, and the local vertical coordinate obtained by the laser
detector further comprises: (D1) using the on-board computer (not
shown) to calculate the difference between an actual position of
the cutting edge of the bucket (30 of FIG. 1, or 82 of FIG. 2) and
a design surface (not shown).
[0099] In one embodiment of the present invention, the step (E) of
guiding the cutting edge of the bucket of the excavator with
substantially high vertical accuracy further comprises: (El) using
the on-board navigational system (28 of FIG. 1, or 80 of FIG. 2) to
control the position of the cutting edge of the bucket by
controlling hydraulics valves configured to operate the cutting
edge of the bucket (30 of FIG. 1, or 82 of FIG. 2).
[0100] In one embodiment of the present invention, the step (E) of
guiding the cutting edge (30 of FIG. 1, or 82 of FIG. 2) of the
bucket of the excavator with substantially high vertical accuracy
further comprises: (E2) using the remotely located control station
(60 of FIG. 1, or 88 of FIG. 2) to remotely operate the excavator.
In this embodiment of the present invention, the step (E) further
comprises: (E3) using the communication link (62 of FIG. 1, or 90
of FIG. 2) to link the remotely located control station (60 of FIG.
1, or 88 of FIG. 2) and the on-board navigational system (28 of
FIG. 1, or 80 of FIG. 2) of the Ex.sub.--3D_ILRPGS system; (E4)
transmitting an excavator real time positioning data to the
remotely located control station via the communication link; and
(E5) receiving at least one control signal from the remotely
located control station via the communication link. In this
embodiment of the present invention, the step (E3) further
comprises: (E3, 1) selecting the wireless communication link from
the group consisting of: {a cellular link; a radio; a private radio
band; a SiteNet 900 private radio network; a wireless Internet; a
satellite wireless communication link; and an optical wireless
link}. Please, see the discussion above.
[0101] In one embodiment, wherein the excavator further includes
the on-board display system (29 of FIG. 1, or 86 of FIG. 2), the
method of the present invention comprises: (F) displaying the
movement of the cutting edge of the bucket (30 of FIG. 1, or 82 of
FIG. 2) by using the on-board display system (29 of FIG. 1, or 86
of FIG. 2), wherein a vertical coordinate of the cutting edge of
the bucket is displayed with an accuracy substantially similar to a
vertical accuracy of the laser beam.
[0102] In one embodiment, wherein the remotely located control
station (60 of FIG. 1, or 88 of FIG. 2) further includes the
display system (64 of FIG. 1, or 92 of FIG. 2), the method of the
present invention comprises: (H) displaying the movement of the
bucket of the excavator by using the control station display
system, wherein a vertical coordinate of the cutting edge of the
bucket is displayed with an accuracy substantially similar to a
vertical accuracy of the laser beam.
[0103] One more aspect of the present invention is directed to a
method of operating an excavator with improved vertical accuracy by
using the Ex.sub.--3D_ILRPGS system, wherein 3D coordinates of the
excavator are obtained by using a mobile radio positioning system
receiver; and wherein a local vertical coordinate is obtained with
a substantially high accuracy by using a laser detector configured
to receive at least one laser beam from a laser transmitter.
[0104] In one embodiment of the present invention, the method
comprises (not shown): (A) obtaining 3D coordinates of the
excavator by using the mobile radio positioning system receiver;
(B) obtaining position coordinates of the boom, the stick and the
bucket of the excavator by utilizing the bucket-to-machine-body
positioning system; (C) obtaining a local vertical coordinate with
a substantially high accuracy by using the laser detector
configured to receive at least one laser beam from a laser
transmitter; (D) receiving and integrating the 3D coordinates of
the excavator obtained by the mobile radio positioning system
receiver, the coordinates of the boom, the stick and the bucket of
the excavator obtained by the bucket-to-machine-body positioning
system, and the local vertical coordinate obtained by the laser
detector by using an on-board navigational system in order to
improve vertical accuracy of the mobile radio positioning system
receiver; and (E) guiding the cutting edge of the bucket of the
excavator with improved vertical accuracy by using the on-board
navigational system.
[0105] Yet, one more aspect of the present invention is directed to
a method of operating an excavator with improved vertical accuracy
by using the Ex.sub.--3D_ILRPGS system and by assigning weight
functions to different measurements.
[0106] A weight function is a mathematical device used when
performing a sum, integral, or average in order to give some
elements more of a "weight" than others. They occur frequently in
statistics and analysis, and are closely related to the concept of
a measure. Weight functions can be constructed in both discrete and
continuous settings.
[0107] In the discrete setting, a weight function w: A.fwdarw. is a
positive function defined on a discrete set A, which is typically
finite or countable. The weight function w(a):=1 corresponds to the
unweighted situation in which all elements have equal weight. One
can then apply this weight to various concepts.
If
[0108] f: A.fwdarw.
is a real-valued function, then the unweighted sum of f on A is
a .di-elect cons. A f ( a ) ; ##EQU00001##
but for a weight function
w: A.fwdarw.,
the weighted sum is
a .di-elect cons. A f ( a ) w ( a ) . ##EQU00002##
[0109] One common application of weighted sums arises in numerical
integration.
[0110] If B is a finite subset of A, one can replace the unweighted
cardinality |B| of B by the weighted cardinality
a .di-elect cons. B w ( a ) . ##EQU00003##
[0111] If A is a finite non-empty set, one can replace the
unweighted mean or average
1 A a .di-elect cons. A f ( a ) ##EQU00004##
by the weighted mean or weighted average
a .di-elect cons. A f ( a ) w ( a ) a .di-elect cons. A w ( a ) .
##EQU00005##
[0112] In this case only the relative weights are relevant.
Weighted means are commonly used in statistics to compensate for
the presence of bias.
[0113] The terminology weight function arises from mechanics: if
one has a collection of n objects on a lever, with weights
w.sub.1, . . . w.sub.n
(where weight is now interpreted in the physical sense) and
locations
x.sub.1, . . . x.sub.n,
then the lever will be in balance if the fulcrum of the lever is at
the center of mass
i = 1 n w i x i i = 1 n w i , ##EQU00006##
which is also the weighted average of the positions xi.
[0114] In one embodiment, the method of the present invention
comprises: (A) obtaining a set of 3D coordinates measurements of
the excavator by making a plurality measurements by using the
mobile radio positioning-system receiver; (B) obtaining position
coordinates of the boom, the stick and the bucket of the excavator
by utilizing the bucket-to-machine-body positioning system; (C)
obtaining a set of local vertical coordinate measurements with a
substantially high accuracy by making a plurality measurements by
using the laser detector configured to receive at least one laser
beam from a laser transmitter; (D) selecting a weight function
configured to assign a 3D weight function to a set of 3D
measurements obtained by using the mobile radio positioning system
receiver, and configured to assign a vertical weight function to a
set of local vertical coordinate measurements obtained by using the
laser detector; (E) integrating the set of 3D coordinates
measurements of the excavator with the 3D weight function, and the
set of the local vertical coordinate measurements with the vertical
weight function by using the on-board navigational system in order
to improve vertical accuracy of the mobile radio positioning system
receiver; and (F) guiding the cutting edge of the bucket of the
excavator with improved vertical accuracy by using the on-board
navigational system.
EXAMPLES
[0115] 1) Benching on a point of known height and then catching the
beam to get a known height on the beam for both flat surface and
sloping surfaces.
[0116] 2) Stopping in the beam and averaging a number of GPS
positions with reference to the beam to get an elevation on the
beam (or elevation and orientation on a sloping beam)
[0117] The foregoing descriptions of specific embodiments of the
present invention have been presented for purposes of illustration
and description. They are not intended to be exhaustive or to limit
the invention to the precise forms disclosed, and obviously many
modifications and variations are possible in light of the above
teaching. The embodiments were chosen and described in order to
best explain the principles of the invention and its practical
application, to thereby enable others skilled in the art to best
utilize the invention and various embodiments with various
modifications as are suited to the particular use contemplated. It
is intended that the scope of the invention be defined by the
claims appended hereto and their equivalents
* * * * *
References