U.S. patent application number 16/581996 was filed with the patent office on 2021-03-25 for work implement linkage system having automated features for a work vehicle.
The applicant listed for this patent is DEERE & COMPANY. Invention is credited to Aaron R. Kenkel, Doug M. Lehmann.
Application Number | 20210087777 16/581996 |
Document ID | / |
Family ID | 1000004393109 |
Filed Date | 2021-03-25 |
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United States Patent
Application |
20210087777 |
Kind Code |
A1 |
Kenkel; Aaron R. ; et
al. |
March 25, 2021 |
WORK IMPLEMENT LINKAGE SYSTEM HAVING AUTOMATED FEATURES FOR A WORK
VEHICLE
Abstract
A work vehicle including a boom, a work implement, and a linkage
sensor system having automated features to move the boom and the
work implement. The work vehicle includes a frame, a boom actuator
for the boom, a boom sensor to identify a boom position with
respect to the frame, an implement actuator, and an implement
sensor to identify a work implement position with respect to the
boom. A controller receives boom position signals from the boom
sensor and work implement signals from the implement sensor. The
controller transmits a boom adjustment signal based on the boom
position modified by boom sensor calibration values and transmits
an implement adjustment signal based on the implement position
modified by implement sensor calibration values. The implement
sensor calibration values are determined during a calibration
process when moving the boom from a lowest position to a highest
position.
Inventors: |
Kenkel; Aaron R.; (East
Dubuque, IL) ; Lehmann; Doug M.; (Durango,
IA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DEERE & COMPANY |
Moline |
IL |
US |
|
|
Family ID: |
1000004393109 |
Appl. No.: |
16/581996 |
Filed: |
September 25, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E02F 3/32 20130101; E02F
9/2203 20130101; E02F 3/434 20130101; E02F 3/437 20130101; E02F
9/2041 20130101 |
International
Class: |
E02F 3/43 20060101
E02F003/43; E02F 3/32 20060101 E02F003/32; E02F 9/20 20060101
E02F009/20; E02F 9/22 20060101 E02F009/22 |
Claims
1. A method of moving a work implement and a boom operatively
connected a work vehicle supported by a surface, the work vehicle
including a work implement sensor to determine a position of the
work implement, and a boom sensor to determine a position of the
boom, the method comprising: calibrating the work implement sensor;
calibrating the boom sensor; raising the boom from a lowered
position to a raised position; determining, with the boom sensor, a
lowered position of the boom at the lowered position; determining,
with the boom sensor, a raised position of the boom at the raised
position; identifying a plurality of work implement positions while
moving the boom from the lowered position to the raised position;
identifying a plurality of error values based on the identified
plurality of work implement positions; and moving the boom based on
the plurality of error values during a work operation.
2. The method of claim 1 wherein raising the boom step includes
raising the boom from a fully lowered position to a fully raised
position.
3. The method of claim 2 wherein the raising the boom step further
comprises raising the boom from the lowered position to the fully
raised position while leaving the work implement stationary with
respect to the boom.
4. The method of claim 3 wherein the calibrating the work implement
sensor includes: moving the work implement to a fully tilted
position in a first direction; identifying the position of the work
implement in the fully tilted position in the first direction.
5. The method of claim 4 wherein the calibrating the work implement
sensor includes: moving the work implement to a fully tilted
position in a second direction; and identifying the position of the
work implement in the fully tilted position in the second
direction.
6. The method of claim 5 wherein the raising the boom step includes
fully lowering the boom to the fully lowered position and setting
the work implement to a level ground position.
7. The method of claim 6 wherein the identifying the plurality of
boom positions includes identifying each of the plurality of boom
positions at regularly spaced boom positions between the fully
lowered position and the fully raised position.
8. The method of claim 7 wherein the regularly spaced boom
positions are spaced about every ten percent of a distance between
the fully lowered position and the fully raised position.
9. The method of claim 1 wherein the moving the boom based on the
plurality of error values includes moving the boom in response to a
return to dig operation.
10. The method of claim 9 further comprising displaying on a user
interface a return to dig actuator accessible by a user.
11. A work vehicle comprising: a frame, a boom actuator including a
boom arm, the boom actuator operatively connected to the frame, a
work implement operatively connected to the boom arm; a boom sensor
located at the boom actuator to identify a boom arm position of the
boom arm with respect to the frame; an implement sensor located at
the work implement actuator to identify a work implement position
of the work implement with respect to the boom arm; a boom control
device to provide a boom control signal; an implement control
device to provide an implement control signal; a control module
supported by the frame and operatively connected to the boom
sensor, the work implement sensor, the boom actuator, the work
implement actuator, the boom control device, and the implement
control device, wherein the control module receives boom position
signals from the boom sensor and work implement signals from the
implement sensor, and transmits to the boom actuator a boom
adjustment signal based on the boom position modified by a boom
sensor calibration value and transmits to the implement actuator an
implement adjustment signal based on the implement position
modified by an implement sensor calibration value.
12. The work vehicle of claim 11 further comprising a user
interface including a return to dig actuator, wherein actuation of
the return to dig actuator adjusts a position of the work implement
with respect to the boom arm based on the boom sensor calibration
value and the implement sensor calibration value.
13. The work vehicle of claim 12 wherein the control module
includes a processer and a memory, wherein the memory has a
plurality of program instructions and a storage table to store
error values based on a model of boom actuator kinematics and a
model of implement actuator kinematics, that in response to
execution by the processor causes the control module to determine
the error values by: identifying a fixed position of the work
implement with respect to the boom arm, wherein the fixed position
of the work implement is determined by a position of the implement
actuator; identifying, with the boom sensor, a position of the boom
arm with respect to the frame at a plurality of positions between a
fully lowered boom position and a fully raised boom position while
maintaining the position of the work implement with respect to the
frame; comparing the identified plurality of positions with the
model of the boom actuator kinematics to arrive at the plurality of
error values.
14. The work vehicle of claim 13 wherein the user interface
includes the boom control, the implement control, and a user input
button operatively connected to the control module, wherein the
user input button when selected by the user identifies and stores
in the memory a lowest position of the boom and a highest position
of the boom.
15. The work implement of claim 14 wherein the processor causes the
control module to display a user prompt to instruct the operator to
move the work implement to the fixed position when the boom is
fully lowered.
16. The work implement of claim 15 wherein the return to dig
actuator adjusts the position of the work implement using the
plurality of error values.
17. The work implement of claim 16 wherein the user interface
includes an identify work implement user input to identify the type
of work implement attached to the work vehicle.
18. A method of positioning a work implement and a boom operatively
connected a work vehicle, the work vehicle including a work
implement sensor to determine a positon of the work implement, and
a boom sensor to determine a position of the boom, the method
comprising: calibrating the work implement sensor and the boom
sensor; identifying an initial work implement position at a lowest
boom position with the work implement sensor; identifying a
plurality of boom positions while moving the boom from a lowest
position to a highest position with the boom sensor; identifying a
plurality of work implement positions with the work implement
sensor at each of the plurality of boom positions while moving the
boom from the lowest position to the highest position and while
maintaining a position of the work implement with respect to the
boom at the initial work implement position; comparing each of the
identified plurality work implement positons with the initial work
implement position to arrive at a plurality of work implement error
values; and positioning the work implement with the boom based on
the work implement error values during a work operation.
19. The method of claim 18 wherein the calibrating the work
implement sensor and boom sensor includes: i) identifying a first
boom position at the lowest position with the boom sensor; ii)
identifying a second boom position at the highest position with the
boom sensor; iii) identifying a first work implement position at a
first extreme position; and iv) identifying a second work implement
position at a second extreme position opposite the first extreme
position.
20. The method of claim 19 wherein the positioning the work
implement includes positioning the work implement in a response to
a return to dig operation.
Description
FIELD OF THE DISCLOSURE
[0001] The present invention generally relates to a work vehicle
having a work implement, and more particularly to a system and
method of automated features for the work implement and a linkage
coupled to the work implement.
BACKGROUND
[0002] Work vehicles, such as a four wheel drive loader, a tractor,
or a self-propelled combine-harvester, include a prime mover which
generates power to perform work. Other work vehicles having prime
movers include construction vehicles, forestry vehicles, lawn
maintenance vehicles, as well as on-road vehicles such as those
used to plow snow, spread salt, or vehicles with towing
capability.
[0003] In the case of a four wheel drive loader, for instance, the
prime mover is often a diesel engine that generates power from a
supply of diesel fuel. The diesel engine drives a transmission
which moves a ground engaging traction device, such as wheels or
treads, to propel the loader, in some situations, across unimproved
ground for use in construction. Such loaders include a hydraulic
machine either powered by the engine or powered by a generator
driven by the engine. The hydraulic machine is used, for instance,
to raise or lower a work implement, such as a bucket or a fork.
[0004] Many, if not all, of these work vehicles, include a linkage
attached to the work implement that is moved by the linkage from
one position to another position. The linkage is moved either by an
operator manipulating a user input device, such as a toggle or a
switch, or automatically by a control system located on the work
vehicle. In some of these work vehicles, the linkage is moved
automatically to move the work implement to one or more
predetermined positions. Such predetermined positions are typically
positions that are constantly repeated during a work operation. By
automatically moving the work implement to the predetermined
position, machine operations are improved and operator fatigue is
reduced. In some cases, however, due to manufacturing variations in
the structure of the linkages and associated hardware, the
predetermined positions can vary from machine to machine or can
vary over time in a particular machine. When variations occur, the
work operations become less efficient and any advantage provide by
automated positioning of the linkage and/or the work implement is
lost. What is needed therefore is a positioning system to move the
linkage and the attached work implement from one position to a next
position that maintains consistent and accurate placement of the
linkage and/or work implement.
SUMMARY
[0005] In one embodiment, there is provided a method of moving a
work implement and a boom operatively connected a work vehicle
supported by a surface, the work vehicle including a work implement
sensor to determine a position of the work implement, and a boom
sensor to determine the position of the boom. The method includes:
calibrating the work implement sensor; calibrating the boom sensor;
raising the boom from a lowered position to a raised position;
determining, with the boom sensor, a lowered position of the boom
at the lowered position; determining, with the boom sensor, a
raised position of the boom at the raised position; identifying a
plurality of work implement positions while moving the boom from
the lowered position to the raised position; identifying a
plurality of error values based on the identified plurality of work
implement positions; and moving the boom based on the plurality of
error values during a work operation.
[0006] In another embodiment, there is provided a work vehicle
including a frame, a boom actuator including a boom arm, the boom
actuator operatively connected to the frame, and a work implement
operatively connected to the boom arm. A boom sensor is located at
the boom actuator to identify a boom arm position of the boom arm
with respect to the frame. An implement sensor is located at the
work implement actuator to identify a work implement position of
the work implement with respect to the boom arm. A boom control
device provides a boom control signal and an implement control
device provides an implement control signal. A control module is
supported by the frame and is operatively connected to the boom
sensor, the work implement sensor, the boom actuator, and the work
implement actuator, wherein the control module receives boom
position signals from the boom sensor and work implement signals
from the implement sensor, and transmits to the boom actuator a
boom adjustment signal based on the boom position modified by a
boom sensor calibration value and transmits to the implement
actuator an implement adjustment signal based on the implement
position modified by an implement sensor calibration value.
[0007] In a further embodiment, there is provided a method of
positioning a work implement and a boom operatively connected a
work vehicle wherein the work vehicle includes a work implement
sensor to determine a positon of the work implement and a boom
sensor to determine the position of the boom. The method includes:
calibrating the work implement sensor and the boom sensor;
identifying an initial work implement position at a lowest boom
position with the work implement sensor; identifying a plurality of
boom positions while moving the boom from a lowest position to a
highest position with the boom sensor; identifying a plurality of
work implement positions with the work implement sensor at each of
the plurality of boom positions while moving the boom from the
lowest position to the highest position and while maintaining a
position of the work implement with respect to the boom at the
initial work implement position; comparing each of the identified
plurality work implement positons with the initial work implement
position to arrive at a plurality of work implement error values;
and positioning the work implement with the boom based on the work
implement error values during a work operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The above-mentioned aspects of the present invention and the
manner of obtaining them will become more apparent and the
invention itself will be better understood by reference to the
following description of the embodiments of the invention, taken in
conjunction with the accompanying drawings, wherein:
[0009] FIG. 1 is a side elevational view of work vehicle with a
work implement in a first position;
[0010] FIG. 2 is a side elevational view of work vehicle with a
work implement in a second position;
[0011] FIG. 3 is a side elevational view of work vehicle with a
work implement in a third position;
[0012] FIG. 4 is a block diagram of a control system of the work
vehicle; and
[0013] FIG. 5 is a block diagram of a process to determine position
errors in a boom/work implement linkage.
DETAILED DESCRIPTION
[0014] For the purposes of promoting an understanding of the
principles of the novel invention, reference will now be made to
the embodiments described herein and illustrated in the drawings
and specific language will be used to describe the same. It will
nevertheless be understood that no limitation of the scope of the
novel invention is thereby intended, such alterations and further
modifications in the illustrated devices and methods, and such
further applications of the principles of the novel invention as
illustrated herein being contemplated as would normally occur to
one skilled in the art to which the novel invention relates.
[0015] FIG. 1 is a side elevational view of a work vehicle 10. The
work vehicle 10 is a four wheel drive (4WD) loader having: a cab
12; a rear body portion 14 with rear wheels 16; a front body
portion 20 with front wheels 22, a work implement such as a bucket
24, a linkage 26 for adjusting a position of the bucket 24, a
hydraulic cylinder 28, and a hydraulic cylinder 30 (See FIGS. 2 and
3) to power the linkage 26. The bucket 24 is rotatably coupled to a
boom arm 31 at a pivot location 32. A second boom arm,
substantially similar to the boom arm 31, is not shown but is
operatively connected to the bucket 24 at an opposite side of the
bucket 24 as would be understood by one skilled in the art. The
cylinder 30 and the boom arm 31 provide a boom actuator that raises
and lowers the implement with respect to the frame of the
vehicle.
[0016] An articulation joint 33 enables angular adjustment of the
rear body portion 14 with the front body portion 20. Hydraulic
cylinders 34, 35, and 36 enable angular changes between the rear
and front body portions 14 and 20 under hydraulic power derived
from conventional hydraulic pumps (not shown).
[0017] An accelerator pedal 38 and a user interface 40 are located
within the cab for use by an operator of the vehicle 10. The
accelerator pedal 38 enables the operator to adjust the speed of
the vehicle. In other embodiments, a hand lever provides this
function.
[0018] The user interface 40 includes a steering wheel 42, a
plurality of operator selectable buttons configured to enable the
operator to control the operation and function of the vehicle 10,
and any accessories or implements being driven by the powertrain of
the vehicle, including the bucket 24. The user interface 40 in one
embodiment, includes a user interface screen having a plurality of
user selectable buttons to select from a plurality of commands or
menus, each of which is selectable through a touch screen having a
display. In another embodiment, the user interface includes a
plurality of mechanical push buttons as well as a touch screen. In
another embodiment, the user interface includes a display screen
and only mechanical push buttons.
[0019] As illustrated in FIG. 1, the linkage 26 is in a fully
lowered position with respect to ground 27. In this position, the
bucket 24 is set to a level position with the ground 27 such that a
plane defined by a bottom portion of the bucket is substantially
flush with the ground and is substantially horizontal. For the
purposes of this disclosure, the position of the linkage 26 and
bucket 24 in FIG. 1 is considered to be a fully lowered position.
The linkage 26, under some conditions, is capable of being lowered
further than the illustrated position of FIG. 1 if the surface of
the ground beneath the bucket 24 is lower than the surface of the
wheels upon which the vehicle is located.
[0020] One end of the arm 31 is operatively connected to the bucket
24 at the pivot location 32 and another end of the arm 31 is
operatively connected to a pivot location 50 of a frame structure
52. As seen in FIGS. 2 and 3, one end of the cylinder 30 is
operatively connected to the boom arm 31 and another end of the
cylinder 30 is operatively connected to the frame 52. Extension and
retraction of the cylinder 30 adjusts the positon of the arm 31
with respect to the frame 52 to raise and to lower the bucket 24.
Using the boom arm 31, the bucket 24 is moved from the fully
lowered position of FIG. 1 to a partially raised position of FIG.
2, and to a fully raised position of FIG. 3. The fully raised
position of FIG. 3 is determined by one or more of mechanical stops
of between the boom arm 31, the cylinder 30, and the frame 52.
[0021] The bucket 24 is adjustable with respect to the boom arm 31
by activation of the cylinder 28 having one end coupled to a
portion of the vehicle 10, as is understood by one skilled in the
art, and at another end thereof operatively connected to an
implement link 54. The implement link 54 is rotatably coupled to an
end of the cylinder 28 at a pivot location 56. Another end of the
implement link 54 is rotatably coupled to a portion of the bucket
24 at a pivot location. An intermediate portion 60 of the link 54
is rotatably coupled to a flange 62 fixedly connected to the arm
31. Extension and retraction of the cylinder 28 rotates the bucket
24 about the pivot location 32. The cylinder 28 and the link 54
provide an implement actuator to move the bucket 24 with respect to
the boom arm 31.
[0022] A sensor 64 is located at or near the pivot 50 to determine
an angle of rotation of the arm 31 with respect to the frame 52. In
one embodiment, the sensor 64 is operatively connected to the arm
31 by a four bar linkage as is understood by one skilled in the
art. In another embodiment, the sensor 64 is located at the pivot
50. As the cylinder 30 extends and retracts, the arm 31 is raised
and lowered with respect to ground 27. A second sensor 66 is
located at or near the pivot axis of the link 54 with respect to
the flange 62. As the cylinder 28 extends and retracts, the bucket
24 rotates about the pivot axis 32. An output of the sensor 64 is
used to determine a height of the bucket 24 with respect to ground
and an output of the second sensor 66 is used to determine the
inclination of the bucket 24 with respect to the arm 31.
[0023] FIG. 4 illustrates a block diagram of an implement control
system 100 to adjust a linkage system for positioning the boom arm
31 and the implement 24, with respect to the vehicle 10 based on
either manual position commands, automatic position commands, or a
combination of manual and automatic position commands. The
implement control system 100 includes a controller 102, such as an
electronic control unit (ECU), which is connected to a controller
area network (CAN) bus (not shown), but represented in FIG. 4 as
double arrow lines indicating a communication link over the bus to
and from the controller 102 and to the various devices and
components of the vehicle 10. The CAN bus is configured to transmit
electrical control signals for the control of various devices
connected to the bus as well as to transmit status signals that
identify the status of the connected devices.
[0024] The controller 102, in different embodiments, includes a
computer, computer system, or other programmable devices. In other
embodiments, the controller 102 includes one or more processors 104
(e.g. microprocessors), and an associated memory 106, which can be
internal to the processor or external to the processor. The memory
106 includes, in different embodiments, random access memory (RAM)
devices comprising the memory storage of the controller 102, as
well as any other types of memory, e.g., cache memories,
non-volatile or backup memories, programmable memories, or flash
memories, and read-only memories. In addition, the memory includes
in other embodiments a memory storage physically located elsewhere
from the processing devices and can include any cache memory in a
processing device, as well as any storage capacity used as a
virtual memory, e.g., as stored on a mass storage device or another
computer coupled to the controller 102. The mass storage device can
include a cache or other dataspace which can include databases.
Memory storage, in other embodiments, is located in the "cloud",
where the memory is located at a distant location which provides
the stored information wirelessly to the controller 102. When
referring to the controller 102 and the memory 106 in this
disclosure other types of controllers and other types of memory are
contemplated.
[0025] The controller 102 executes or otherwise relies upon
computer software applications, components, programs, objects,
modules, or data structures, etc. Software routines resident in the
included memory of the controller 102, or other memory, are
executed in response to the signals received from sensors as well
as signals received from other controllers or ECUs such as an
engine ECU and a transmission ECU. The controller 102, in one or
more embodiments, also relies on one or more computer software
applications that are located in the "cloud", where the cloud
generally refers to a network having stored data and/or computer
software programs accessed through the internet. The executed
software includes one or more specific applications, components,
programs, objects, modules or sequences of instructions typically
referred to as "program code". The program code includes one or
more instructions located in memory and other storage devices which
execute the instructions which are resident in memory, which are
responsive to other instructions generated by the system, or which
are provided a user interface operated by the user.
[0026] Moreover, while the invention is described in the context of
controllers, those skilled in the art will appreciate that the
various embodiments of the invention are capable of being
distributed as a program product in a variety of forms, and that
the invention applies equally regardless of the particular type of
computer readable media used to actually carry out the
distribution. Examples of computer readable media include but are
not limited to physical, recordable type media such as volatile and
non-volatile memory devices, floppy and other removable disks, hard
disk drives, optical disks (e.g., CD-ROM's, DVD's, etc.), among
others, and transmission type media such as digital and analog
communication links.
[0027] In addition, it should be appreciated that the process or
processes described herein are implementable in various program
code and should not be limited to specific types of program code or
specific organizations of such program code. Additionally, in view
of the typically endless number of manners in which computer
programs may be organized into routines, procedures, methods,
modules, objects, and the like, as well as the various manners in
which program functionality may be allocated among various software
layers that are resident within a controller or computer if used,
(e.g., operating systems, libraries, APIs, applications, applets,
etc.), it should be appreciated that the invention is not limited
to a specific organization.
[0028] The vehicle 10 includes a plurality of sensors, each of
which in different embodiments, identifies vehicle device status
and transmits sensor information to the controller 102, which the
controller 102 executes to adjust the position the boom arm 31 and
the implement 24. When moving the boom arm 31, the controller 102
adjusts the position of the cylinder(s) 30. The controller 102
adjusts the position of the cylinder(s) 30 to move the implement 24
with respect to the boom 31.
[0029] The controller 102 generates commands to adjust the position
of the arm 31 based on sensor information received from the arm
sensor 64 and adjusts the position of the implement 24 based on
sensor information based on the implement sensor 66.
[0030] The controller 102 is further operatively connected to the
operator user interface 40 that includes a display 110, a boom
control 112, an implement control 114, and a return to dig feature
control 116. The boom control 112 is a user controlled actuation
device, such as a toggle, for moving the boom 31. The implement
control 114 is a user controlled actuation device for moving the
implement 24, such as another toggle. The return to dig 116 is an
actuation device, such as pushbutton, which when activated is used
to move the bucket 24 and the arm 31 to a return to dig position
such as that illustrated in FIG. 1. The display 110 provides a
display screen to display vehicle status information including a
real time identification of the height of the boom and the
inclination of the implement. The display 110 further includes user
input buttons of one or more different types including touch screen
buttons, contact buttons, or physically manipulated buttons. In one
or more embodiments, operator user interface includes an identify
implement user input 111 that displays a number of different types
of implements capable of being used by the vehicle 10. In some
embodiments, the results of the calibration routine depend on the
type of work implement being used. For instance in one example, the
determined calibration values for the calibration routine of a
bucket are different than the calibration values for the
calibration routing of a fork. The identify work implement user
input is used to identify which type of work implement is being
used such that different calibration values are determined for
different types of work implements. In some embodiments, the
kinematic model being used in the calibration routine depends on
the type of work implement being used. Consequently, selection of
the type of work implement instructs the control module 102 as to
which kinematic model is to be used.
[0031] The memory 106 is organized as addressable memory such that
sensor information is stored as data for both the boom and
implements at addressable memory 108. The data stored in memory 108
includes positional data of the boom 31 as it moves from a lowest
position to a highest position. The data stored in memory 108
further includes actual positional data of the implement 24 as it
moves between a fully extended position to a fully retracted
position. The memory 106 further includes kinematic data in memory
110 for the entire kinematic chain of both driven and driving
components that include the boom 31 and the implement 24. The
kinematic data is based on a kinematic model of the boom 31 and its
actuation apparatus and the implement 24 and it actuation
apparatus. The kinematic data utilizes a mathematical formulation
that takes into account the structures of the actuation devices and
lever arms being used to move boom 31 and the implement 24 as
designed, in contrast to the actual positional data stored in
memory 108 resulting from operation of the vehicle. The kinematic
data is based on design parameters for the physical actuation
devices and lever arms. Because physical devices are subject to
manufacturing tolerances, the kinematic data does not always
directly correspond to the sensed data. The difference between the
sensed data and the kinematic data, also known as error data, is
stored at memory 112. As used herein "kinematic" refers to
theoretical distances/angles of the linkage.
[0032] On a material loading vehicle (such as the 4WD Loader),
automated linkage control functions are often implemented. One such
feature, known commonly as the "Return to Dig" feature, utilizes
position sensors on the loader linkage to automatically return the
front-end attachment to a position defined by the operator or by
the manufacturer. Unless the position of the cylinder driving the
front-end equipment is known (via in-cylinder position sensing), a
system of at least two sensors, such as the boom sensor 64 and the
implement sensor 66, is typically used to determine the position of
the front end implement. A model of the linkage kinematics is used
along with those two sensors to determine the position of all
linkage elements. Any inaccuracy in these two or more sensors,
however, potentially adds up the inaccuracies (also known as
errors) and often results in a substantial error when directing the
angular position of the front-end implement. Depending on
tolerances for the various components that are built into the
linkage systems and sensing system, minimizing the error by
manufacturing methods to meet the customer requirements for the
automated function may not be sufficient. For instance, to achieve
accurate position of the boom and the work implement extremely
tight manufacturing tolerances are required, but are not
practically achievable due to the number of linkages and sensors
requiring tight tolerances. In other situations, such tolerances,
while achievable, are cost prohibitive. Consequently, minimizing
the error in the hardware structures may not be possible or
practicable.
[0033] The present disclosure includes a system having a
calibration routine and a process to determine existing errors in a
boom/implement system. The routine, however, is not limited to one
type of implement, such as a bucket, and is also is used but not
limited to other implements, such as a fork. By determining errors,
any automated function control is compensated for by the determined
errors that enables the boom and the implement to be positioned
more accurately. On a loader linkage, for instance, the front-end
equipment angular position error, in different embodiments, is a
function of the boom height. Various boom positions generate
different error stack-ups, where the errors add up in the two or
more sensors used to calculate the front-end attachment position.
To overcome the errors present in the loader linkage, the present
system and process in one or more embodiments provides an error
calibration routine to calculate a table of errors as a function of
the boom position.
[0034] FIG. 5 illustrates a block diagram of a process 200 to
determine angular position errors in a boom/work implement linkage
and to use the determined errors to position the boom and/or work
implement throughout the range of motion in either an automatic
function or in manual control. The block diagram 200 discloses a
process that calculates an error in the front-end equipment (work
implement) position, wherein the calculation is based on or is a
function of boom height. The calibration of the work implement
position is made after a position sensor calibration routine. By
calibrating the position sensors first, the determination of an
error in the front-end equipment is made more precise. During a
typical position sensor calibration routine, the boom is actuated
between its fully lowered position and its fully raised position.
The data taken at the two ends of travel are interpolated between
the two end positions in order to determine a real-time position of
the boom as it moves from one end of the range of motion to the
other end of the range of motion. A similar calibration routine is
performed for the front-end attachment. With these calibration
points being identified, the positions of the boom and the
front-end attachment are determinable in real-time.
[0035] The process of FIG. 5 begins at a start position 202 which
begins after the operator turns on the work vehicle 10. Once the
vehicle is running, the operator raises the boom 31 to a highest
position such that the boom 31 is full raised at block 204. (See
FIG. 3) In one embodiment, the display 110 of the user interface 40
displays a process start button, which is actuated by the operator
to begin the routine. Once actuated, the display provides a series
of steps to be completed by the operator. At a first step 204, the
display instructs the operator to fully raise the boom 31 using one
of the operator controls, such as the toggle. Once the boom is
fully raised, the operator makes a selection from the user
interface to indicate that the boom is in the fully raised
position. In another embodiment, the controller 102 determines the
fully raised position of the boom. Once the fully raised position
has been identified, the controller 102 stores this position as a
fully raised calibration point in the memory 106 including a sensor
value generated by the sensor 64. Once stored, the display
instructs the operator to fully lower the boom 31 using one of the
operator controls at block 206. Once the boom is fully lowered, the
operator makes a selection from the user interface to indicate that
the boom is in the fully lowered position. (See FIG. 1) In another
embodiment, the controller 102 determines the position of the boom
at its lowest position. In other embodiments, the order of raising
then lowering is reversed.
[0036] Once the fully lowered position has been identified, the
controller 102 stores this position as a fully lowered calibration
point in the memory 106 including a sensor value generated by the
sensor 64. To fully lower the boom, the operator under most
conditions tilts the work implement 24 toward the cab 12 to enable
the boom to be fully lowered.
[0037] Once the highest and lowest position values of the boom are
identified and stored, the display instructs the operator to fully
tilt the work implement 24 in a first direction using one of the
operator controls, such as the toggle. The operator, in most
instances, raises the boom 31 sufficiently from the ground to
enable complete rotational movement of the work implement 24 in
either direction. (See FIG. 2) Once the work implement is fully
tilted in the first direction at block 208, the operator identifies
the first direction position with the user interface and the value
of the sensor 64 is stored in memory as a first calibration point
for a first full tilt value. In another embodiment, the controller
102 determines the position of the work implement and stores this
value of the first direction position as a calibration point in the
memory 106 at block 210. Once stored, the display instructs the
operator to fully tilt the work implement 24 in a second direction
using the operator controls at block 210. Once the implement is
fully tilted (or rotated) in the second direction, the operator
identifies the second direction position with the user interface
and the value of the sensor 64 is identified and stored in memory
as a second calibration point. In another embodiment, the
controller 102 determines the position of the work implement and
stores this second direction position as a calibration point in the
memory 106 at block 210. In one or more other embodiments, the
steps of 204, 206, 208, and 210 are either partially or completely
automated by the controller 102. In the embodiment of FIG. 5, the
display provides a calibration input device, such as a button,
which upon selection by the operator, directs the controller 102 to
move the boom from its lowest position to its highest position and
to move the work implement from its fully tilted first position to
its fully tilted second position.
[0038] After step 210, the boom sensor 64 and implement sensor 66
are now calibrated for the end of travel positions of the boom and
the end of travel positions of the work implement. These values are
stored in the memory 106. In one or more embodiments, the sensor 64
and the sensor 66 generate an output signal having a voltage
representative of the position of the boom 31 and the work
implement 24. In one embodiment for instance, each of the sensors
64 and 66 generates a signal having a voltage range of from 0.5 to
4.5 volts. The value at 0.5 volts is at one extreme location and
the value at 4.5 volts is at the other extreme location. A halfway
point between the two voltages, about 2.5 volts, indicates a center
position of the boom 31 and of the work implement 24. Other types
of sensors are contemplated.
[0039] Following the sensor calibration for sensors 64 and 66, an
error (resulting from hardware tolerance stack-up) is determined by
moving the boom 31 from the fully lowered position to the fully
raised position, keeping the front-end attachment stationary. The
front-end attachment angle (which is calculated as a function of
the system of one or more sensors measuring linkage positions) is
held constant throughout the range of boom travel. Consequently,
any deviation of the work implement from the starting position is
considered to be attributable to an error resulting from the
sensing system and/or from the hardware. A storage table is
generated, while the boom is being raised, to store one or more
deviations from the starting position of the work implement with
the sensed position of the work implement as the boom is raised.
This deviation is identified as an error and stored as a function
of boom height. The stored error is used by an automated function
control routine to "offset" the setpoint for the front-end
attachment based on the current boom position.
[0040] To determine the errors after the calibration of sensors 64
and 66, the operator is instructed by the system with a prompt
displayed on the displayl10. The prompt instructs the operator to
fully lower the boom 31 and to set the work implement 24 level with
the ground 27 at block 212. This location is considered a "starting
position". Once lowered and the work implement is properly
positioned, the operator acknowledges that the instructed location
of the boom 31 and work implement 24 have been reached with an
operator input to the display 110. In one embodiment, the display
110 includes a user input which is selected by the operator to
confirm the proper position. Once acknowledged, the starting
position for the work implement, that is determined by the
controller based on inputs received by the sensors 64 and 66, is
calculated based on, or as a function of, the calibration points
identified after blocks 204, 206, 208, and 210. The calculated
starting position is determined and stored in memory 106 at block
214. The starting position of the work implement, in one or more
embodiments, is the angle of the implement that is set by the
cylinder 28. The stroke of the rod of the cylinder 28 is set to a
certain extension such that the cylinder rod extends from the
cylinder body to position the implement at the starting position.
In one example, the implement angle is 52 degrees at the starting
position.
[0041] Once the stroke of the cylinder is identified and stored,
the operator is instructed by the display to raise the boom 31 from
its lowered position of block 212 to a fully raised position at
block 216. As the boom 31 is raised (while the cylinder stroke
position of the cylinder 28 is held constant), the values of the
work implement sensor 66 and the values of the boom arm sensor 64
are received by the controller 102. As the boom is raised (or
lowered in another embodiment from the highest position to the
lowest position), the controller 102 stores the values received
from the implement sensor 66 and the boom arm sensor 64 at
predetermined locations of the boom arm as it moves from its lowest
position to its highest position. At each of these predetermined
positions, the sensed values of implement angle and boom angle
provided by the sensors 64 and 66 to the controller 102 are
identified and used to calculate an implement cylinder stroke value
which represents an angle of the work implement with respect to the
boom arm 31.
[0042] As the boom moves from the lowest position to the highest
position, the angle of the implement changes due to the linkage
kinematics. The value that is determined as a function of the
sensors 64 and 66 at the starting position is the work implement
cylinder stroke value or cylinder position, which does not vary as
the boom is raised or lowered. This value of cylinder position,
which also represents, the starting angle of the work implement, is
used as a baseline for determining an error value during movement
of the boom.
[0043] In one embodiment, the implement angles and boom angles
determined by the sensors are used with kinematic data provided by
a kinematic model of the boom and implement. These values are
stored in memory 110 to determine the error between the starting
position stroke value of the implement cylinder 28 (i.e. 52 degree
implement angle in this example) with a calculated value of
cylinder position using the boom and implement sensor values.
Because of machine to machine variations due to manufacturing
tolerances, the calculated value of cylinder position can and does
vary when compared to the starting cylinder position. This error is
calculated at every predetermined position and is stored as a
calibration value in the memory 112. In one embodiment, the
predetermined positions are identified at every 10% increment of
movement of the boom 31 from its lowest position to its highest
position at block 218.
[0044] As the boom is raised, the controller 102 receives a boom
position signal from the boom sensor 64. The controller 102
determines at block 220 whether the boom has been raised by a 10%
increment at block 220. If it has not been raised by 10%, the
controller 102 continues to monitor the raising of the boom at
block 218. If it has been raised by an increment of 10%, then the
controller logs and stores a cylinder position error representative
of the position of the work implement 24 at block 222. This error
value is determined based on the previously stored starting
position of the cylinder position that is subtracted from the
currently identified position of the cylinder. At block 224 the
controller 102 determines whether the boom 31 has been fully
raised. If not, monitoring of the boom position continues at block
218. If the boom has been fully raised, the calibration is
completed at block 226.
[0045] While the cylinder position error is stored for every 10%
movement of boom height in FIG. 5, in other embodiments the
cylinder position error is stored at other percentages of boom
height. For instance, in one embodiment, the cylinder position
error is stored for every 5% movement of boom height using the
determined position of the implement with respect to the boom.
Other percentages are contemplated.
[0046] In one or more embodiments, the cylinder position error,
which correlates to a front end attachment error, is dependent upon
the cylinder position at the starting position. For instance in one
example, the starting position of a bucket is 52 degrees while the
starting position of a fork is 60 degrees, each of which have a
different cylinder stroke value. As such, in one embodiment, the
calibration routine generates a two-dimensional table of errors
that is dependent upon both boom height and cylinder stroke value.
While such a calibration routine potentially provides a more
accurate determination of errors, such a calibration routine
requires additional time to complete a full calibration. By using a
single position (the starting position in this example) of the
cylinder stroke value, however, the calibration routine provides a
determination of errors sufficient to accurately locate the work
implement. In other embodiments, the calibration routine is
automatically controlled to ensure that the cylinder stroke value
does not change (by overriding the operator's ability to move it)
as well as to limit the speed of the boom (in order to ensure
calibration points are captured in a timely manner).
[0047] Once the error values are determined and stored in the
memory 112 for each incremental boom height, those error values are
used to position the work implement during a return to dig
operation commanded by the operator. The return to dig user input
116, or return to dig user actuator, located at the user interface
40, is actuated by the operator when needed. During a return to dig
operation, the controller 102 generates a boom position command, or
boom adjustment signal, for movement of the boom 31, and generates
a work implement command, or boom adjustment signal for movement of
work implement 24 using the cylinder 28. In one or more
embodiments, these position commands are based on the kinematic
model of the positioning system which is generally the same for all
work vehicles of a particular type. Each vehicle, however, can, and
often is, different from another vehicle of the same type due to
differences in manufacturing tolerances of the parts. Once the
calibration routine is completed for a particular vehicle, the
controller modifies the return to dig command for that vehicle
based on the kinematic model with the determined calibration values
112. In this way, each vehicle is individually modified or
customized to compensate for the particular structures of the parts
used in the boom assembly and the work implement assembly.
[0048] The calibration routine is not limited to a return to dig
operation, but is applicable to other functions of the work vehicle
in which the calibrated errors are used to override normal operator
commands. For instance, in one embodiment the calibrated errors are
used in an auto leveling feature that automatically controls the
level position of the work implement as the boom moves up and down.
In this embodiment for a bucket, the bucket is rolled in and out at
the boom is moved to keep the bucket level relative to the vehicle
to ground. The error compensation is used to compensate the auto
leveling feature to improve the precision of movement. Other
functions are contemplated.
[0049] While exemplary embodiments incorporating the principles of
the present invention have been disclosed hereinabove, the present
invention is not limited to the disclosed embodiments. Instead,
this application is intended to cover any variations, uses, or
adaptations of the invention using its general principles. For
instance, while the hybrid power train controller and engine
control unit are illustrated as separate devices, in other
embodiments the hybrid power train controller and energy control
device are embodied as a single device. Likewise, in other
embodiments all control functions of a vehicle including the speed
controller are embodied as a single device. Further, this
application is intended to cover such departures from the present
disclosure as come within known or customary practice in the art to
which this invention pertains.
* * * * *