U.S. patent application number 13/780446 was filed with the patent office on 2014-08-28 for load estimator for scraper.
This patent application is currently assigned to CATERPILLAR INC.. The applicant listed for this patent is CATERPILLAR INC.. Invention is credited to Jeffrey E. Buettner, Robert K. Cannon, Jason S. Knowles, Michael R. Whitchurch.
Application Number | 20140237868 13/780446 |
Document ID | / |
Family ID | 51386677 |
Filed Date | 2014-08-28 |
United States Patent
Application |
20140237868 |
Kind Code |
A1 |
Whitchurch; Michael R. ; et
al. |
August 28, 2014 |
LOAD ESTIMATOR FOR SCRAPER
Abstract
A load estimator is disclosed for use with a scraper. The load
estimator may have a first sensor configured to generate a first
signal indicative of a performance parameter of the scraper, a
second sensor configured to generate a second signal indicative of
a hydraulic pressure associated with a bowl of the scraper, and a
controller in communication with the first and second sensors. The
controller may be configured to classify a current segment of an
ongoing work cycle based on the first signal. The controller may
also be configured to selectively estimate a load of material
contained with the bowl of the scraper based on the second signal
only when the current segment is classified as a segment where the
load can be reliably estimated.
Inventors: |
Whitchurch; Michael R.;
(Forsyth, IL) ; Buettner; Jeffrey E.; (East
Peoria, IL) ; Knowles; Jason S.; (Morton, IL)
; Cannon; Robert K.; (Peoria, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CATERPILLAR INC. |
Peoria |
IL |
US |
|
|
Assignee: |
CATERPILLAR INC.
Peoria
IL
|
Family ID: |
51386677 |
Appl. No.: |
13/780446 |
Filed: |
February 28, 2013 |
Current U.S.
Class: |
37/413 ;
701/33.4; 701/34.4 |
Current CPC
Class: |
E02F 3/6481 20130101;
E02F 9/264 20130101; E02F 3/651 20130101; G01G 19/10 20130101; G01G
19/083 20130101 |
Class at
Publication: |
37/413 ;
701/34.4; 701/33.4 |
International
Class: |
E02F 3/65 20060101
E02F003/65; E02F 3/64 20060101 E02F003/64 |
Claims
1. A load estimator for a scraper, comprising: a first sensor
configured to generate a first signal indicative of a performance
parameter of the scraper; a second sensor configured to generate a
second signal indicative of a hydraulic pressure associated with a
bowl of the scraper; and a controller in communication with the
first and second sensors, the controller being configured to:
classify a current segment of an ongoing work cycle based on the
first signal; and selectively estimate a load of material contained
with the bowl of the scraper based on the second signal only when
the current segment is classified as a segment where the load can
be reliably estimated.
2. The load estimator of claim 1, wherein the performance parameter
is associated with at least one of an ejector condition, a
transmission gear, a ground speed or location, a cushion hitch
status, an apron cylinder condition, an elevator condition, and a
bowl actuator position.
3. The load estimator of claim 1, wherein the second signal is
indicative of one or more hydraulic pressures within a cylinder
configured to raise and lower the bowl.
4. The load estimator of claim 1, wherein the controller is
configured to: classify the current segment as one of dig segment,
a carry segment, a dump segment, and a return segment; and
selectively estimate the load of material contained with the bowl
of the scraper based on the second signal only when the current
segment is classified as the carry segment.
5. The load estimator of claim 5, wherein the controller is further
configured to selectively implement a load estimation calibration
procedure only when the current segment is classified as the return
segment.
6. The load estimator of claim 1, wherein the controller is further
configured to: estimate the load of material multiple times during
a single segment of a same excavation cycle; and generate an
average value for the load of material based on the load estimated
during the multiple times.
7. The load estimator of claim 1, further including a communication
device located onboard the scraper, wherein the controller is
further configured to transmit the estimated load offboard the
scraper via the communication device.
8. The load estimator of claim 7, wherein the controller is further
configured to link an identification of the scraper and an operator
identification to the estimated load.
9. The load estimator of claim 1, further including a display
located within an operator station of the scraper, wherein the
controller is further configured to cause a representation of the
estimated load to be shown on the display.
10. The load estimator of claim 9, wherein the controller is
further configured to: track completion of cycles by the scraper
based on the first signal; tabulate a running total of material
moved by the scraper based on the completion of cycles and the load
estimated during each cycle; and cause a representation of the
running total to be shown on the display.
11. A method of estimating a load for a scraper, comprising:
sensing a performance parameter of the scraper; sensing a hydraulic
pressure associated with a bowl of the scraper; classifying a
current segment of an ongoing work cycle based on the performance
parameter; and selectively estimating a load of material contained
within the bowl of the scraper based on the hydraulic pressure only
when the current segment is classified as a segment where the load
can be reliably estimated.
12. The method of claim 11, wherein sensing a performance parameter
includes sensing a performance parameter associated with at least
one of an ejector condition, a transmission gear, a ground speed, a
cushion hitch status, an apron cylinder condition, an elevator
condition, and a bowl actuator position.
13. The method of claim 11, wherein sensing a hydraulic pressure
includes sensing one or more hydraulic pressures within a cylinder
configured to raise and lower the bowl.
14. The method of claim 11, wherein: classifying the current
segment of the ongoing work cycle includes classifying the current
segment as one of a dig segment, a carry segment, a dump segment,
and a return segment; and selectively estimating the load of
material contained within the bowl of the scraper includes
selectively estimating the load of material only when the current
segment is classified as the carry segment.
15. The method of claim 14, further including selectively
implementing a load estimation calibration procedure only when the
current segment is classified as the return segment.
16. The method of claim 11, wherein selectively estimating the load
of material includes: estimating the load of material multiple
times during a single segment of a same excavation cycle; and
generating an average value for the load of material based on the
load estimated during the multiple times.
17. The method of claim 11, further including: linking an
identification of the scraper and an operator identification to the
estimated load; and communicating the estimated load offboard the
scraper.
18. The method of claim 11, further including displaying a
representation of the estimated load within an operator station of
the scraper.
19. The method of claim 18, further including: tracking completion
of cycles by the scraper based on the performance parameter;
tabulating a running total of material moved by the scraper based
on the completion of cycles and the load estimated during each
cycle; and displaying a representation of the running total within
the operator station.
20. A scraper, comprising: a tractor having a transmission; a bowl
having a blade at a front end; an ejector located at a back end of
the bowl; an apron connected at a leading end of the bowl; at least
a first sensor associated with at least one of the transmission,
the ejector, and the apron, the at least a first sensor configured
to generate at least a first signal indicative of a gear ratio of
the transmission, a condition of the bowl, a condition of the
ejector, and a condition of the apron; a cylinder configured to
raise and lower the blade into a work surface; a pressure sensor
configured to sense a pressure of the cylinder and generate a
corresponding second signal; and a controller in communication with
the at least a first sensor and the pressure sensor, the controller
being configured to: classify a current segment of an ongoing work
cycle as one of a dig segment, a carry segment, a dump segment, and
a return segment based on the at least a first signal; and
selectively estimate a load of material contained with the bowl of
the scraper based on the second signal only when the current
segment is classified as the carry segment.
Description
TECHNICAL FIELD
[0001] The present disclosure relates to a load estimator and, more
particularly, to a load estimator for a scraper.
BACKGROUND
[0002] A scraper is a mobile construction machine used for
transporting material over short distances. The scraper generally
consists of a tractor that tows a vertically movable hopper known
as a bowl over a ground surface. A horizontal blade is connected to
a leading lower edge of the bowl such that, when the tractor tows
the bowl forward and the bowl is lowered, the horizontal blade cuts
into the ground surface and fills the bowl with excavated material.
After the bowl is loaded to capacity, the bowl is raised away from
the ground surface and closed at the leading edge by a vertical
blade known as an apron. The scraper then transports its load to a
dump area where the apron is raised and an ejector located at a
back end of the bowl pushes the load forward out of the bowl. The
cycle is then repeated until a desired amount of material has been
moved.
[0003] During operation of the scraper, it can be important to keep
track of the amount of material moved by the scraper. For example,
the amount of material moved by the scraper (i.e., the weight of
the material, also known as the payload weight or the load) during
each excavation cycle may be used in determining productivity of
the scraper or of a particular scraper operator. In another
example, the payload of the scraper may aid in determining
completion of a project, billing of a particular customer, and/or
scheduling of the scraper. Historically, the amount of material
moved by a scraper was determined based directly on measured
pressures of hydraulic rams or cylinders associated with the
scraper's bowl. Unfortunately, this method of estimating loading of
the scraper was prone to error, as the pressures can fluctuate
significantly during different operations of the scraper. For
example, during loading when the horizontal blade is engaged with
the ground surface, fluid pressures within the hydraulic cylinders
can be much higher than when the blade is away from the ground
surface, even though the payload of the scraper may not have
changed.
[0004] One attempt to improve payload estimation of a scraper is
disclosed in U.S. Pat. No. 3,154,160 of Rockwell et al. that issued
on Oct. 27, 1962 ("the '160 patent"). Specifically, the '160 patent
discloses a device for indicating to an operator the weight of a
load carried by a wheeled scraper. The load indicating device is
responsive to hydraulic pressure in a load carrying ram of the
scraper. The load indicating device is operative only when front
and rear units of the scraper are pivoted to their raised travel
positions and a valve for controlling the ram is in a neutral or
hold position. With this configuration, false readings may be
prevented by inhibiting load measuring during engagement of the
scraper with a ground surface.
[0005] While the load indicating device of the '160 patent may help
to improve payload estimating in some situations, the device may
still be less than optimal. Specifically, there may be situations
where the front and rear units are not fully raised before travel
of the scraper and, in these situations, the load indicating device
may be inhibited from estimating the load. Further, the '160 patent
describes no way to calibrate the load indicating device, without
which measurement accuracy may degrade over time. In addition, the
load indicating device is a purely mechanical device and provides
no display flexibility, recording functionality, accumulation
tabulation functionality, or communication ability.
[0006] The present disclosure is directed to overcoming one or more
of the problems set forth above and/or other problems of the prior
art.
SUMMARY
[0007] In one aspect, the present disclosure is directed to a load
estimator for a scraper. The load estimator may include a first
sensor configured to generate a first signal indicative of a
performance parameter of the scraper, a second sensor configured to
generate a second signal indicative of a hydraulic pressure
associated with a bowl of the scraper, and a controller in
communication with the first and second sensors. The controller may
be configured to classify a current segment of an ongoing work
cycle based on the first signal. The controller may also be
configured to selectively estimate a load of material contained
with the bowl of the scraper based on the second signal only when
the current segment is a segment wherein the load can be reliably
estimated.
[0008] In another aspect, the present disclosure is directed to a
method of estimating a load for a scraper. The method may include
sensing a performance parameter of the scraper and sensing a
hydraulic pressure associated with a bowl of the scraper. The
method may also include classifying a current segment of an ongoing
work cycle based on the performance parameter, and selectively
estimating a load of material contained within the bowl of the
scraper based on the hydraulic pressure only when the current
segment is classified as a segment where the load can be reliably
estimated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a pictorial illustration of an exemplary disclosed
machine;
[0010] FIG. 2 is a diagrammatic illustration of an exemplary
disclosed load estimator that may be used with the machine of FIG.
1; and
[0011] FIG. 3 is a flowchart depicting an exemplary disclosed
method of estimating payload for the machine of FIG. 1.
DETAILED DESCRIPTION
[0012] FIG. 1 illustrates an exemplary earth-moving machine 10.
Machine 10 may be a wheeled tractor scraper configured to load
material at a first location, transport the material from the first
location to a second location, and unload the material at the
second location. Although commonly referred to as a "wheeled"
tractor scraper, it is contemplated that machine 10 may be
propelled by way of wheels, continuous tracks, and/or belts, as
desired. Machine 10 may include a tractor 12 operatively connected
to a bowl portion 14 and configured to tow bowl portion 14 across a
ground surface 16.
[0013] Tractor 12 may include multiple components that interact to
power and control operations of bowl portion 14. Specifically,
tractor 12 may include a frame 18, a front axle assembly 20, a
power source 22, an articulated hitch assembly 24, and an operator
station 26. Frame 18 may be connected to front axle assembly 20 and
configured to support power source 22. Power source 22 may include,
for example, a combustion engine 28 that drives front axle assembly
20 via a transmission 30 and/or provides electrical and hydraulic
power to bowl portion 14. Transmission 30 may embody an electric
transmission, a hydraulic transmission, a mechanical transmission,
or a hybrid transmission having a reverse gear ratio and one or
more selectable forward gear ratios. Articulated hitch assembly 24
may connect tractor 12 to bowl portion 14, while allowing some
relative movement between tractor 12 and bowl portion 14 in both
vertical and horizontal directions. Operator station 26 may
facilitate control of tractor 12 and bowl portion 14.
[0014] Articulated hitch assembly 24 may include a curved main beam
32 having a front end 34 and a back end 36. Front end 34 of beam 32
may be connected through a vertical hinge joint 38 and a horizontal
hinge joint 40 to frame 18 such that beam 32 may pivot both in the
horizontal direction and in the vertical direction relative to
frame 18. A cushion actuator 42, for example a hydraulic cylinder,
may be associated with horizontal hinge joint 40 to provide for
selective isolation of operator station 26 from vertical movements
of bowl portion 14. Cushion actuator 42, together with horizontal
hinge joint 40, may form what is known as a cushion hitch 45.
Cushion hitch 45 may be hydraulically locked during some modes of
operations such that beam 32 is inhibited from moving in the
vertical direction relative to frame 18, and unlocked during other
modes of operations to allow beam 32 and bowl portion 14 to float
in the vertical direction relative to frame 18.
[0015] Back end 36 of beam 32 may be connected to bowl portion 14
via a pair of arms 46 located at opposing sides of beam 32 (only
one side shown in FIG. 1). Each arm 46 may include a first end 48
and a second end 50. First end 48 may be pivotally connected to
back end 36 of beam 32 via a first pin 52, while second end 50 may
be connected to bowl portion 14 via a second pin 54. A pair of bowl
actuators 56, for example hydraulic cylinders, may be connected
between beam 32 at back end 36 and bowl portion 14, and configured
to selectively raise bowl portion 14 away from ground surface 16
and lower bowl portion 14 toward ground surface 16 by retractions
and extensions thereof, respectively.
[0016] Operator station 26 may include one or more interface
devices 58 located proximal an operator seat and configured to
generate control signals and/or present displays associated with
operation of machine 10. In one example, interface device 58 may be
used to display information regarding operation of machine 10, for
example payload information, as will be described in more detail
below.
[0017] Bowl portion 14 may include a bowl 60 connected to and
supported by a rear axle assembly 62. During extension and
retraction of bowl actuators 56, bowl 60 may be caused to pivot in
the vertical direction about rear axle assembly 62 such that a
leading or front end 64 of bowl 60 may be raised and lowered
relative to ground surface 16. In some embodiments, an additional
power source 66 may be contained within bowl portion 14 and
supported by rear axle assembly 62. In these embodiments, power
source 66 may be operated to drive rear axle assembly 62 and
thereby push machine 10 across ground surface 16.
[0018] Bowl 60 may be a tool embodied as a generally hollow
enclosure having an opening 68 at front end 64. A horizontal blade
70 may be located at front end 64 and positioned to selectively
engage ground surface 16 as front end 64 is lowered by the
extension of bowl actuators 56. In this configuration, an extension
length of bowl actuators 56 may affect a depth of blade 70 into
ground surface 16 and, in conjunction with a travel speed of
machine 10, a rate of material removal from ground surface 16.
Similarly, a pressure of fluid within bowl actuators 56 may reflect
a force generated by a load contained within bowl 60.
[0019] In one embodiment, bowl portion 14 may also include an apron
72 configured to close off opening 68 of bowl 60. Apron 72 may
embody a tool member that is pivotally connected to bowl 60 at a
first end 74 and free to move at a second end 76 in a fore/aft
machine direction relative to bowl 60. An apron actuator 78 may be
connected to a front side of apron 72 (i.e., to an outside of apron
72 relative to bowl 60) and configured to selectively pull apron 72
forward to pivot from a closed position to an open position, and
push apron 72 backward to pivot from the open position to the
closed position. In one embodiment, apron actuator 78 may include
an arm 80 pivotally connected at a first end 82 to beam 32, a rod
84 pivotally connected between a second end 86 of arm 80 and the
front side of apron 72, and a hydraulic cylinder 88 connected
between beam 32 and arm 80. An extension of hydraulic cylinder 88
may function to push second end 86 of arm 80 up away from beam 32,
while a retraction of hydraulic cylinder 88 may function to pull
second end 86 down toward beam 32. The upward movement of second
end 86 of arm 80 may pull rod 84 up and cause apron 72 to pivot
forward away from bowl 60 and expose opening 68. The downward
movement of second end 86 may push rod 84 down and cause apron 72
to pivot backward toward bowl 60 and close off opening 68. It
should be noted that, in other embodiments, machine 10 may be
equipped with an elevator (not shown) instead of apron 72. In these
embodiments, the elevator may function to move material entering
opening 68 of bowl 60 rearward and upward away from opening 68.
[0020] Bowl portion 14 may be provided with an ejector 90
configured to selectively push material accumulated within bowl 60
out through opening 68 when apron 72 has been pulled up by
hydraulic cylinder 88. Ejector 90 may include an ejector plate 92,
and an ejector cylinder 94 connected between ejector plate 92 and a
frame member (not shown) of bowl portion 14. Ejector plate 92 may
be moved by ejector cylinder 94 from a full retract position at a
back end 95 of bowl 60 (shown in FIG. 1) toward a full dump
position at front end 64 of bowl 60. When ejector plate 92 is away
from the full dump position, material may be loaded into bowl 60
via opening 68 and/or transported within bowl 60. When ejector
plate 92 is moved toward the full dump position, material
accumulated within bowl 60 may be pushed out of opening 68. Ejector
cylinder 94 may be selectively provided with and drained of
pressurized fluid to cause ejector cylinder 94 to retract and
extend, thereby moving ejector plate 92.
[0021] As shown in FIG. 2, bowl actuators 56 may be equipped with
one or more pressure sensors 96 configured to sense hydraulic
pressures of fluid within one or more different chambers of bowl
actuators 56 (e.g., a pressure sensor 96 disposed within or
otherwise fluidly connected to each pressure chamber of bowl
actuators 56) and to generate corresponding signals. The signals
generated by pressure sensors 96 may be indicative of forces acting
on bowl 60. When bowl 60 is engaged with ground surface 16, the
forces may be generated by bowl actuators 56 pushing blade 70 into
ground surface 16 and ground surface 16 resisting the motion. When
bowl 60 is away from ground surface 16 (i.e., not engaged with
ground surface 16), the forces may be generated by a weight of
material captured within bowl 60 (i.e., the payload of machine 10).
Values of the signals generated by pressure sensors 96 may be
directed to a controller 98.
[0022] Controller 98, together with pressure sensor 96 and other
components of machine 10, may form a load estimator 102 configured
to detect performance parameters of machine 10 and the forces
acting on bowl 60, and responsively estimate the weight of material
loaded into bowl 60 of machine 10 (i.e., the payload of machine
10). The performance parameters detected by load estimator 102 can
include any type of parameter associated with any one or more
components of machine 10 that are described above. In the disclosed
embodiment, these components include transmission 30, cushion hitch
45, apron 72, and ejector 90. It is contemplated, however, that
other components may additionally or alternatively be used in
determining the payload of machine 10, if desired, for example the
elevator described above (not shown). Controller 98 may communicate
directly with some or all of these components and/or indirectly
with these components, for example via one or more sensors 100, to
detect the performance parameters. The performance parameters may
include, among other things, a travel speed and/or location (e.g.,
GPS location or location relative to designated dig and dump
locations) of machine 10, a selected gear ratio of transmission 30,
a condition of cushion hitch 45 (e.g., locked or unlocked status,
position, pressure, etc.), a condition of apron 72 (e.g., opened,
closed, position, pressure, etc.), a condition of ejector 90 (e.g.,
retracted, extended, position, pressure, etc.), a condition of the
elevator (e.g., position and/or pressure), and/or a condition of
bowl actuators 56 (e.g., position and/or pressure). As will be
described in more detail below, controller 98, based on the
signal(s) from sensor(s) 100, may classify a current segment of an
ongoing excavation cycle being performed by machine 10 as one of a
plurality of known segments. In the disclosed embodiment, the known
segments include a dig segment (e.g., a segment during which bowl
60 is being loaded with material), a carry segment (e.g., a segment
during which bowl 60 is full of material, bowl 60 is not engaged
with ground surface 16, and machine 10 is traveling), a dump
segment (e.g., a segment during which bowl 60 is actively being
emptied of material), and a return segment (e.g., a segment during
which bowl 60 is empty of material, bowl 60 is not engaged with
ground surface 16, and machine 10 is traveling). It is contemplated
that other classifications may also or alternatively be utilized,
if desired. And based on the classification and the signal from
sensor(s) 96, controller 98 may be configured to selectively
estimate the load carried by bowl 60.
[0023] Controller 98 may include any components or combination of
components for monitoring, recording, storing, indexing,
processing, conditioning, and/or communicating operational aspects
of machine 10 described above. These components may include, for
example, a memory, one or more data storage devices, a central
processing unit, or any other components that may be used to run an
application. Furthermore, although aspects of the present
disclosure may be described generally as being stored in memory,
one skilled in the art will appreciate that these aspects can be
stored on or read from types of computer program products or
computer-readable media, such as computer chips and secondary
storage devices, including hard disks, floppy disks, optical media,
CD-ROM, or other forms of RAM or ROM. Controller 98 may execute
sequences of computer program instructions stored on the computer
readable media to perform a method of load estimating that will be
explained below.
[0024] In some embodiments, controller 98 may communicate
information relating to performance of machine 10 and/or an
operator of machine 10 to an offboard entity. Communication between
controller 98 and the offboard entity may be facilitated via a
communication device 104 located onboard each machine 10 (e.g.,
within operator station 26). This information may include, for
example, the load estimated to be carried by machine 10, a linked
identity of machine 10, a linked identity of the operator of
machine 10, a machine location, a cycle count for machine 10, and
other similar pieces of information. Data messages associated with
load estimator 102 may be sent and received via a direct data link
and/or a wireless communication link, as desired. The direct data
link may include an Ethernet connection, a connected area network
(CAN), or another data link known in the art. The wireless
communications may include satellite, cellular, infrared, and any
other type of wireless communications that enable communication
device 104 to exchange information between controller 98 and the
offboard entity.
[0025] FIG. 3 illustrates an exemplary method stored as
instructions on the computer readable medium that are executable by
controller 98 to perform load estimating for machine 10. FIG. 3
will be discussed in more detail in the following section to
further illustrate the disclosed concepts.
INDUSTRIAL APPLICABILITY
[0026] The disclosed load estimator may be applicable to any type
of scraper that is configured to dig, transport, and dump material
in a known repeatable excavation cycle. The disclosed load
estimator may provide for accurate and reliable estimating of
payloads in an autonomous manner. Operation of load estimator 102
will now be explained with respect to FIG. 3.
[0027] As shown in FIG. 3, the method may begin by controller 98
measuring one or more pressures of hydraulic fluid associated with
bowl 60 (e.g., the pressures within opposing chambers of bowl
actuators 56 and/or cushion actuator 42--Step 300). The pressures
may be measured by way of pressure sensors 96. These pressures may
then be used by controller 98 to selectively calculate a force
acting on the corresponding actuator(s) and the payload of machine
10 (Step 305). Calculation of this force may be accomplished
utilizing well-known equations based on the sensed pressures and
known effective hydraulic areas within the corresponding
actuator(s). In the disclosed embodiment, the payload may be
determined utilizing a lookup chart, algorithm, and/or equation
stored in the memory of controller 98 that directly relates the
force (or alternatively the pressure) to a weight value of the
load.
[0028] Controller 98 may then receive and/or detect any number of
different performance parameters of machine 10 (Step 310). As
described above, these performance parameters may include, among
other things, a travel speed and/or location, a selected gear
ratio, a cushion hitch condition, an apron condition, an ejector
condition, an elevator condition, a bowl actuator condition, or
another condition known in the art. The parameter(s) may be
received directly from the corresponding component or detected via
one or more sensors 100 associated with the component. Although
shown as the third step in the flowchart of FIG. 3, it is
contemplated that step 310 may be completed before steps 300 and/or
305, simultaneous with steps 300 and/or 305, and/or continuously
throughout operation of machine 10, as desired.
[0029] Controller 98 may be configured to classify a current
operation of machine 10 as one of a plurality of known segments of
a repeatable and ongoing excavation cycle (Step 315). As described
above, exemplary known segments generally include the dig segment,
the carry segment, the dump segment, and the return segment.
Controller 98 may classify the current operation based on any one
or more of the performance parameters received/detected in step 310
described above.
[0030] For example, when ejector 90 is at a full dump position (all
the way forward in bowl 60), bowl 60 of machine 10 may most likely
be empty and dumping may have already occurred. Accordingly, when
ejector 90 is detected as being at the full dump position,
controller 98 may classify the current operation as the return
segment of the excavation cycle, during which machine 10 is
traveling back to a dig location after having dumped its load. In
contrast, when ejector 90 is away from the full dump position
(i.e., at the full retract position all the way rearward in bowl
60), machine 10 could be loaded and controller 98 may classify the
current operation as the carry segment of the excavation cycle,
during which machine 10 is traveling away from the dig location
after having acquired its load.
[0031] In another example, when cushion hitch 45 is detected as
being in the locked mode of operation, machine 10 could still be
digging. In this situation, controller 98 may classify the current
operation as the dig segment. However, when cushion hitch 45 is in
the float mode of operation, machine 10 is likely to have completed
or be in the process of completing the carry segment of the
excavation cycle and controller 98 may classify the current
operation accordingly.
[0032] In yet another example, when transmission 30 is in a
high-speed gear, machine 10 may be traveling or has traveled above
a minimum speed to move from a dig location to a dump location. In
this situation, controller 98 may be configured to classify the
current operation as one of the carry or return segments. In some
embodiments, controller 98 may classify the current operation based
on any combination of these and/or other performance
parameters.
[0033] After classifying the current operation, controller 98 may
determine if the classified operation is a particular segment of
the excavation cycle (e.g., the carry segment, where the load can
be reliably estimated) and respond accordingly (Step 320). For
example, when controller 98 determines that the current operation
is not classified as the carry segment (Step 320: NO), control may
return to step 300. However, when the current operation is
classified as the carry segment (Step 320:YES), control may proceed
to step 325, where the payload signal (i.e., the calculation of the
instantaneous payload of machine 10) may be processed (e.g.,
filtered and averaged relative to other calculations performed
during the same segment of the same excavation cycle). This
processing may help to improve accuracy in the payload value.
[0034] Controller 98 may then determine if the carry segment has
been completed (Step 330). This determination may be made in many
different ways. In the disclosed embodiment, controller 98 may
determine that the carry segment has been completed by determining
that the dump segment has been initiated. In other embodiments,
however, controller 98 may conclude that the carry segment has been
completed based on a travel speed, a bowl actuator position, an
apron condition, an elevator condition, or in another manner known
in the art. Control may cycle through steps 300-330 until
controller 98 determines that the carry segment has been
completed.
[0035] When controller 98 determines that the carry segment has
been completed (Step 330:YES), the filtered and averaged payload
signal may then be reported (Step 335). This reporting may include,
among other things, display of a representation of the payload
signal within operator station 26 via interface device 58. This
representation may take any form known in the art (e.g., a
numerical value, a percent of a desired load, a picture, a bar
graph, etc.), and may provide information to the operator regarding
a current load being transported by machine 10, a highest load
transported within a particular time period (e.g., during a shift
or a lifetime of machine 10), and/or a running total of material
weight transported within the particular period of time. Controller
98 may tabulate the running total by tracking completion of cycles
during the time period and adding the load estimation for each
cycle. The operator of machine 10 may then use the information
displayed on interface device 58 to improve operation throughout
the time period, to diagnose problems with machine 10, to bill a
particular customer, to track progress in completion of an assigned
task, and/or for other purposes.
[0036] In some embodiments, controller 98 may also be configured to
transmit the payload signal to an offboard entity for further
processing. For example, the information may be transmitted via
communication device 104 to a worksite manager located remotely
from machine 10. The worksite manager may then use the information
for similar purposes described above.
[0037] After reporting of the machine payload value, controller 98
may continue to monitor machine operation and determine when the
ensuing dump segment has been completed (Step 340). Control may
cycle through step 340 until the dump segment has been completed.
Once controller 98 determines that the dump segment has been
completed, controller 98 may then selectively implement calibration
of load estimator 102 (Step 345). It is contemplated that the
calibration procedure may be implemented after completion of every
dump segment, after a certain amount of time has elapsed, after a
particular amount of material has been moved, after completion of a
desired number of excavation cycles, or according to another
strategy known in the art.
[0038] The calibration procedure may be implemented after
completion of the dump segment (e.g., during the return segment)
because bowl 60 should be relatively empty at that point in time
and because the motion of bowl actuators 56 should be relatively
stable. For example, bowl 60 should not engage ground surface 16
during the return segment and bowl actuators 56 should be
stationary. Thus, the pressures of hydraulic fluid within bowl
actuators 56 should accurately reflect a known empty weight of bowl
60 (and other components normally supported by bowl actuators 56).
Accordingly, the pressures measured during the return segment of
the excavation cycle should be relatively consistent throughout
time, and controller 98 may be configured to determine adjustment
factors based on any changes in the pressures detected between
different return segments. These adjustment factors may then be
applied to future payload estimations to help ensure accuracy of
the process.
[0039] Because load estimator 102 may implement payload estimations
during only a particular segment of the excavation cycle of machine
10, accuracy in the estimations may be high. Further, because load
estimator 102 may use many different criteria for classifying the
current segment, there may be more opportunity to estimate the
payload of machine 10 without incurring error in the process.
Further, because load estimator 102 may be capable of calibration
during every excavation cycle, accuracy may be ensured throughout
the useful life of machine 10. Finally, the ability to display
different aspects of machine payload within operator station 26 and
or at a remote offboard location may improve use of the information
and productivity of machine 10.
[0040] It will be apparent to those skilled in the art that various
modifications and variations can be made to the disclosed load
estimator. Other embodiments will be apparent to those skilled in
the art from consideration of the specification and practice of the
disclosed load estimator. For example, it is contemplated that
fluid pressures associated with cushion hitch 45 could additionally
or alternatively be used to determine the payload of machine 10, if
desired. It is intended that the specification and examples be
considered as exemplary only, with a true scope being indicated by
the following claims and their equivalents.
* * * * *