Note: Descriptions are shown in the official language in which they were submitted.
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18184-WO
ELECTRONIC PARALLEL LIFT AND RETURN TO CARRY OR FLOAT ON A
BACKHOE LOADER
Field of the Invention
The invention relates to a system for sensing and automatically controlling
the
orientation of a work tool
Background of the Invention
A variety of work machines can be equipped with tools for performing a work
function. Examples of such machines include a wide variety of loaders,
excavators,
telehandlers, and aerial lifts. A work vehicle such as backhoe loader may be
equipped with a backhoe tool, such as a backhoe bucket or other structure, for
excavating and material handling functions as well as a loader tool such as a
loader
bucket.
In the backhoe portion of the backhoe loader, a swing frame pivotally attaches
to the vehicle frame at a rear portion of the vehicle, a backhoe boom
pivotally
attaches to the swing frame, a dipperstick pivotally attaches to the backhoe
boom,
and the backhoe tool pivotally attaches to the dipperstick about a backhoe
tool pivot.
A vehicle operator controls the orientation of the backhoe bucket relative to
the
dipperstick by a backhoe tool actuator. The operator also controls the
rotational
position of the boom relative to the vehicle frame, and the dipperstick
relative to the
boom, by corresponding actuators. The aforementioned actuators are typically
comprised of one or more double acting hydraulic cylinders and a corresponding
hydraulic circuit.
In the loader portion of the backhoe loader the loader boom is pivotally
attached to the vehicle frame at a front portion of the backhoe loader and a
loader
tool, such as a loader bucket, is pivotally attached to the loader boom at a
loader
bucket pivot. Typically, the bucket is operatively attached to a linkage which
is also
connected to the vehicle frame or the boom. Work operation with a loader
bucket
entails similar problems to those encountered in work operations with the
backhoe
bucket.
During a work operation with a loader tool, such as lifting, lowering or
dumping material, it is desirable to maintain an initial orientation relative
to the frame
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of the vehicle to prevent premature dumping of material, or to obtain a
constant =
loader tool angle. In conventional backhoe loaders, the operator is required
to
continually manipulate a loader tool command input device to adjust the loader
tool
orientation as the loader boom is moved during the work operation to maintain
the
initial loader tool orientation relative to the vehicle frame. The continual
adjustment
of the loader tool orientation, combined with the simultaneous manipulation of
a
loader boom command input device, requires a degree of operator attention and
manual effort that can diminish overall work efficiency and increase operator
fatigue.
A number of mechanisms and systems have been used to automatically
control the orientation of work tools such as loader buckets. Various examples
of
electronic sensing and control systems are disclosed in US Patents 4,923,326,
4,844,685, 5,356,260, 6,233,511, and 6,609,315. Control systems of the prior
art
typically utilize position sensors attached at various locations on the work
vehicle to
sense and control tool orientation relative to the vehicle frame.
Additionally, the US
Patent 6,609,315 makes use of an angular velocity sensor attached to the tool
to
sense and maintain a fixed work tool orientation relative to an initial tool
orientation,
independent of vehicle frame orientation. Also, US Patent 7,222,444, makes use
of
a tilt sensor that, when attached to an object, such as the tool, detects the
object's
inclination with respect to the earth
Summary of the Invention
An object of the present invention is to provide an improved system for
controlling the orientation of a tool for a work vehicle.
The illustrated invention comprises a backhoe loader which includes a
backhoe assembly, and a loader assembly. The backhoe assembly includes a
swing frame pivotally attached to the frame of the backhoe loader, a backhoe
boom
of the truly attached to the swing frame, a backhoe boom actuator for
controllably
pivoting the boom relative to the swing frame, a dipperstick pivotally
attached to the
boom, a dipperstick actuator for controllably pivoting the dipperstick
relative to the
boom, a backhoe to definitely attest to the dipperstick, and a backhoe to
actuator for
controllably moving the backhoe tool about its pivot.
The loader assembly includes a loader boom pivotally attached to the vehicle
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frame, a loader boom actuator for controllably pivoting the loader boom
relative to
the vehicle frame, a loader tool pivotally attached to the loader boom, and a
loader
tool actuator for controllably pivoting the loader tool relative. to the
loader boom. The
loader also includes a loader tool command device to effect operation of the
loader
tool actuator and a mode switch to enable and disable features of the
invention. The
invention addresses the loader portion of the backhoe loader.
In the invention, the vehicle has at least one of a first mode and a second
mode, each mode being enabled by a mode switch. In the first mode a controller
allows the loader tool to respond to boom manipulation in a conventional
manner,
i.e., the angle of the loader tool is adjusted on a strictly mechanical basis
in
accordance with the mechanical interplay between the boom, a loader tool
linkage
and the loader tool. In the second mode, which is a parallel lift mode a
controller
causes the angle of the tool to be adjusted in accordance with an electronic
program
throughout an angular movement of the boom regardless of any particular
mechanical relationship between the tool linkage, the boom and the loader
tool. In
the second mode, the invention uses at least one sensor to detect an angle of
a
loader tool with respect to a datum such as, for example, the vehicle frame
and
maintain that angle throughout a boom rotation with respect to the datum
unless
parallel lift is deactivated during boom travel or the boom reaches an angle
in which
another function takes precedence. The controller maintains the tool
orientation by
commanding the tool actuator to adjust the tool position as a function of the
boom
angle with respect to the vehicle frame. The initial tool angle is set and
stored at the
time parallel lift is activated and updated each time the tool angle is
changed via the
manipulation of a tool command input device such as, for example, a joystick
as long
as parallel lift is enabled. When parallel lift is deactivated, i.e.,
disabled, the vehicle
returns to the first mode and no new angles are set or updated until parallel
lift is re-
enabled.
The invention provides for other functions for controlling the loader tool
such
as, for example, return to carry, return to dig and anti-spill which is
designed to keep
a loader bucket from spilling its contents on the hood or cab of the vehicle.
Brief Description of the Drawings
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Figure 1 is a side view of a backhoe loader;
Figure 2 is a detailed view of a loader portion of the backhoe loader;
Figure 3 is a schematic, diagram illustrating an exemplary embodiment of the
components of the invention with respect to a control system for the loader
tool;
Figure 4a illustrates how the angle of the loader tool changes as the boom
rotates in an upward direction;
Figure 4b illustrates more graphically how the angle of the loader tool with
respect to the boom changes in Figure 4a;
Figure 5a illustrates how the angle of the loader tool changes as the boom
rotates in an downward direction;
Figure 5b is a schematic diagram illustrating how the angle of the loader tool
changes as the boom rotates in an downward direction;
Figure 6 graphically illustrates how the loader tool responds to one example
joystick override command while parallel lift is enabled;
Figure 7 illustrates how the angle of the loader to changes as the boom
moves toward al and toward a2 while parallel lift is enabled;
Figure 9 illustrates a flow chart outlining the initiation and operation of
return
to carry;
Figure 10 illustrates a flow chart outlining the initiation and operation of
boom height kickout;
Figure 11 illustrates a flow chart outlining the initiation and operation of
return to dig;
Figure 12 illustrates the operation of the anti-spill function;
Figure 13 illustrates a monitor used for anti-spill settings;
Figure 14 illustrates a backhoe loader chair 14 showing the position of the
monitor in Figure 13; and
Figure 15 illustrates a schematic of an alternate embodiment of the
components of the invention.
Description of the Preferred Embodiment
Figure 1 illustrates an exemplary work vehicle, i.e., a backhoe loader 10 in
which the invention may be utilized. The backhoe loader 10 has a frame 12, to
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which are attached ground engaging wheels 11 for supporting and propelling the
vehicle 10. Attached to the front of the vehicle is a loader assembly 30, and
attached to the rear of the vehicle 10 is a backhoe assembly 40. Both the
loader
assembly 30 and backhoe assembly 40 perform a variety of material handling
functions. An operator controls the functions of the vehicle 10 from an
operator's
station 20.
This particular loader assembly 30 comprises a loader boom 31, a linkage 40
and a tool such as, for example, a loader bucket 36. The loader boom 31 has a
first
end 31 a pivotally attached to the frame 12 at a horizontal loader boom pivot
12a, and
a second end 31c to which the loader bucket 36 pivotally attaches at loader
bucket
pivot 36a.
The linkage 40, illustrated in Figure 2, includes a boom link 41 and a bucket
link 42. The boom link 41 is pivotally attached to the boom 31 at a first boom
link
pivot 41a and pivotally attached to a loader bucket hydraulic cylinder 32 at a
second
boom link pivot 41 b. The bucket link 42 is pivotally attached to the loader
bucket
hydraulic cylinder 32 at a first bucket link pivot 42a and pivotally attached
to the
bucket 36 at a second bucket link pivot 42b. In this particular case, the
second
boom link pivot 41b and the first bucket link pivot 42a are the same, i.e.,
they are
both pivot 41 a. As the loader bucket hydraulic cylinder extends and retracts,
an
angle 0 between the boom link 41 and the bucket link 42 increases and
decreases
respectively.
Figure 3 illustrates a schematic representing an exemplary embodiment of the
invention. In Figure 3, a loader boom actuator 50, having a loader boom
hydraulic
cylinder 33 extending between the vehicle frame 12 and the loader boom 31,
controllably moves the loader boom 31 about the loader boom pivot 12a. The
loader
boom hydraulic cylinder 33 is pivotally attached to the frame 12 at a first
loader boom
hydraulic cylinder pivot 33a and pivotally attached to the loader boom 31 at a
second
loader boom hydraulic cylinder pivot 33b. In the illustrated embodiment, the
loader
boom actuator 50 comprises a boom electro-hydraulic circuit 51 hydraulically
coupled to the loader boom hydraulic cylinder 33. A controller 100 supplies
and
controls the flow of hydraulic fluid to and from the loader boom hydraulic
cylinder 33
via the loader boom electro-hydraulic circuit 51. The controller 100 may take
many
forms from a hard wired or mechanical device to a programmable computer. In
this
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embodiment of the invention, the controller 100 comprises a programmable on-
board
electronic computer.
A loader bucket actuator 60, having a loader bucket hydraulic cylinder 32
extending between the loader boom 31 and the loader bucket 36, controllably
moves
the loader bucket 36 about the loader bucket pivot 36a. In the illustrated
embodiment, the loader bucket actuator 60 comprises a bucket electro-hydraulic
circuit 61 hydraulically coupled to the loader bucket hydraulic cylinder 32.
The
controller 100 controls the bucket electro-hydraulic circuit 61 which supplies
and
controls the flow of hydraulic fluid to the loader bucket hydraulic cylinder
32. Note
that the boom electro-hydraulic circuit 51 and the bucket hydraulic circuit 61
are
conventionally configured and may have significant commonality; they may, in
fact,
be the same circuit.
The operator commands movement of the loader assembly 30 by
manipulating a loader bucket command input device such as, for example a
joystick
21 and a loader boom command input device such as, for example the joystick
21.
The joystick 21 is adapted to generate a loader bucket command signal 28 in
proportion to a degree of manipulation by the operator and proportional to a
flow rate
of fluid to the bucket hydraulic cylinder 32 which is indirectly proportional
to an
angular speed of a desired loader bucket movement. The controller 100, in
communication with the loader bucket command input device 21 and loader bucket
actuator 60, receives the loader bucket command signal 28 and responds by
generating a controller bucket command signal 102 proportional to the bucket
command signal 28, which is received by the loader bucket electro-hydraulic
circuit
61. The loader bucket electro-hydraulic circuit 61 responds to the controller
bucket
command signal 102 by directing hydraulic fluid to and from the loader bucket
hydraulic cylinder 32, causing the hydraulic cylinder 32 to extend and retract
and curl
and dump the loader bucket 36 accordingly.
The joystick 21 is adapted to generate a loader boom command signal 29 in
proportion to a degree of manipulation in a first direction of the joystick 21
by the
operator, the boom command signal 29 being proportional to a flow rate of
fluid to
the hydraulic boom cylinder 33 and indirectly proportional to a speed of a
desired
loader boom movement. The controller 100, in communication with the joystick
21
and loader boom cylinder 33, receives the loader boom command signal 29 and
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responds by generating a controller boom command signal 103 proportional to
the
loader boom command signal 29, which is received by the boom electro-hydraulic
circuit 51. The boom electro-hydraulic circuit 51 responds to the controller
boom
command signal 103 by directing hydraulic fluid to and from the loader boom
hydraulic cylinder 33 at a rate proportional to the controller boom command
signal
103, causing the hydraulic cylinder 33 to move the loader boom 31 about the
pivot
12a accordingly.
PARALLEL LIFT AND INITIAL ANGULAR SETTING OF THE LOADER TOOL
During a work operation with the loader bucket 36, such as lifting, lowering
or
transporting material, it is, at times, desirable to maintain an initial
loader bucket
orientation relative to the vehicle to reduce premature dumping of material as
well as
increase general operator convenience. In a conventional backhoe, to maintain
the
initial loader bucket orientation, with respect to the frame 12, as the loader
boom 31
is lifted or lowered relative to the frame 12, the operator is required to
continually
manipulate the loader bucket command input device 21 to adjust the loader
bucket
orientation. The continual adjustment of the orientation of the loader bucket
36
requires a degree of attention and manual effort from the operator that
diminishes
overall work efficiency and increases operator fatigue.
The exemplary control system of the invention, illustrated in Figure 3, is
adapted to automatically maintain an initial or a set loader bucket
orientation or tilt
angle with respect to a datum, such as, for example, the vehicle frame 12, as
an
angle of the boom 31 changes. This embodiment of the invention makes use of at
least a loader boom angle sensor 54 proximal to the first boom pivot 12a and a
boom
link angle sensor 55 proximal to the first boom link pivot 41 a, both angle
sensors 54,
55 being in communication with the controller 100. The loader boom angle
sensor
54 is adapted to sense an angle of the boom relative to the frame 12, i.e., a
boom to
frame angle BmA and to generate a corresponding loader boom angle signal 54a.
The bucket link angle sensor 55 is adapted to sense an angle of the bucket
link 42
relative to the loader boom 31 and to generate a corresponding bucket link
angle
signal 55a. The controller 100 is adapted to receive the loader boom command
signal 29, the loader boom angle signal 54a, the bucket command signal 28, and
the
bucket link angle signal 55a and to generate a controller bucket command
signal 102
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in response, causing the loader bucket actuator 60 to move the loader bucket
36 to
maintain a desired loader bucket angle with respect to the frame 12 and,
consequently, with respect to the boom 31.
Where the object of the invention is a parallel lift function to maintain an
initial
loader bucket angle, relative to the frame 12, the desired loader bucket angle
is
maintained unless maintenance of this angle interferes with other automatic
functions such as, for example, return to dig, return to carry and anti-spill
(to be
described later) of higher precedence. Additionally, the controller 100 is
adapted to
allow a manual override of engaged parallel lift when the operator commands
movement of the loader bucket 36, via a manipulation of the joystick 21 in a
second
direction, i.e., upon the controller 100 receiving the loader bucket command
signal
28 while the parallel lift function is engaged, and establishing a new initial
loader
bucket orientation at the sensed orientation of the loader bucket 36 after the
loader
bucket command signal 28 terminates.
In the illustrated embodiment, the present invention also utilizes a parallel
lift
command switch 110 in communication with the controller 100. The parallel lift
command switch 110 is adapted to generate a parallel lift enable signal 111
corresponding to a first manipulation of the parallel lift command switch 110
by the
operator to enable operation of the parallel lift function for the loader
bucket 36 and
to generate a parallel lift disable signal 112 corresponding to a second
manipulation
of the parallel lift command switch 110. With respect to the parallel lift
function, the
controller 100 is adapted to ignore the loader bucket angle signal 56 until
the
controller 100 receives the parallel lift enable signal 111 from the parallel
lift
command switch 110. The parallel lift enable signal 111 places the controller
100 in
a first mode where parallel lift is enabled or activated. The parallel lift
disable signal
112 places the controller 100 in a second mode where parallel lift is disabled
or
deactivated. The controller 100 is also adapted to generate controller bucket
command signals 102 and controller boom command signals 103 to manipulate the
bucket 36 and the boom 31 in response to return to carry commands, returned to
dig
commands, and anti-spill commands which will be explained in some of the
remaining portions of this document.
In operation, upon receiving a parallel lift enable signal 111, the controller
100
enters the second mode and uses a loader boom angle signal 54a and a bucket
link
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angle signal 55a to determine an initial angle of the bucket 36 with respect
to the
frame 12, i.e., the bucket to frame angle. Of course, any calculation of the
bucket
angle must account for the geometry of the bucket. Thus, in this embodiment,
the
angle of the bucket 36 with respect to the frame 12 is calculated as a = BmA +
BtA,
where a equals the bucket to frame angle, BmA equals the boom to frame angle
and
BtA equals the angle of the bucket 36 with respect to the boom 31, i.e., the
bucket to
boom angle. The controller calculates the BtA by using the bucket link angle
signal
55a to determine the angle of a back of the bucket 36 and subtracting OA, an
offset
angle, from the result, the offset angle being a corrective angle introduced
to take the
shape of the bucket 36 into account when determining an angle of an open face
of
the bucket 36. In this particular case the shape of the bucket 36 affords a
difference
between an angle of a face of the bucket 36 as represented by plane 36a and a
back
portion of the bucket pivotally connected to the boom 31 and the bucket link
42b as
represented by plane 36b. Thus, a is the angle of the face of the bucket,
i.e., the
angle of plane 36a, with respect to the datum plane 12d, a going to 00 as the
angular
orientation of plane 36a approaches that of the datum plane 12d. In summary,
the
controller 100 uses the bucket link angle signal 55a to determine the angle of
plane
36b with respect to the boom 31, i.e., boom plane 31 d and the offset value is
subtracted from that result to determine the angle of the BtA. The controller
100
uses the boom angle signal 54a to determine the BmA. Once the controller 100
determines the BmA and BtA the controller 100 can determine a by adding BmA
and
Bta. These and other determinations and/or calculations, throughout this
embodiment, may be accomplished via a variety of conventional methods
including:
lookup tables, numerically derived equations, analytically derived equations
taking
the lengths of the boom link 54 and the bucket link 55 into account, etc.
As the boom rises, a is maintained by adjusting the BtA in a motion
resembling dumping, as illustrated in Figures 4A and 4B, as the BtA changes
from
BtA1 to BtA2. Thus, such adjustments shall be called "dumping" adjustments. As
the
boom lowers, a is maintained by adjusting BtA in a motion resembling curling,
as
illustrated in Figures 5A and 5B, as the BtA changes from BtA2 to BtA1. Thus,
such
adjustments shall be called "curling" adjustments.
HYBRID CONTROL OF ADJUSTMENTS
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As the boom 31 rises or lowers, the controller makes BtA adjustments by
generating controller bucket command signals 102, i.e., bucket commands, to
extend
or retract the loader bucket hydraulic cylinder 32 as required by predictive
and
corrective control procedures. The predictive control procedures allow for
quicker
response times for the loader bucket 36. The corrective control procedures
increase
the accuracy of the response in approximating parallel lift.
In the predictive control procedures, the controller 100 calculates the BtA
adjustments using only the loader boom command signal 29, the loader boom
angle
signal 54a and the geometries of the linkage 30, the bucket 36 and the boom
31.
This allows for quick bucket adjustments, via bucket command signals 28, when
the
boom rises or lowers as the calculations merely depend upon geometry and the
predicted rate of change in the BmA using the controller boom command signals
103
to predict the rate of change of the BmA, the flow rate to the loader boom
hydraulic
cylinder being proportional to the controller boom command signals 103. Of
course,
the controller 100 could, in other embodiments, also predict the rate of
change in the
BmA by determining the measured rate of change using the loader boom angle
signals 54a over time. However, whichever method is used, the predictive
procedure is an open loop procedure that could possibly introduce cumulative
error
as the calculations do not take actual BtA, i.e., feedback, into
consideration.
The corrective procedure is a closed loop procedure in which possible error is
reduced when the controller 100 uses the bucket link signal 55a to calculate
an
actual angle of the bucket 36 and act upon a difference between a predicted
BtA and
the actual BtA when the difference is equal to or greater than a threshold
value such
as, for example, 00 or 30 . The correction is made by adjusting the controller
bucket
command signal 102, taking the controller boom command signal 103, the boom
angle signal 54a and the bucket link angle signal 55a into account, in an
effort to
reduce the difference to zero. In this embodiment, if the BtA is
undercorrected
beyond effective adjustment at the current flow rate for the boom 31, the
controller
100 reduces the controller boom command signals 103 to zero until BtA changes
such that a is correctly adjusted. Conversely, if the BtA is overcorrected,
the
controller reduces the controller bucket command 102 to zero until, taking BmA
command into account, the BmA changes such that the BtA is correctly adjusted.
Other embodiments could allow the controller 100 to correct the BtA in the
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angular direction in the event of overcorrection.
MANUAL OVERRIDE OF PARALLEL LIFT VIA JOYSTICK MANIPULATION
If the loader bucket 36 is manually commanded, via the joystick 21, to dump
or curl while the parallel lift function is engaged, the parallel lift
function continues to
adjust the angle of the loader bucket 36 in a manner approximating parallel
lift.
However, as indicated in Figure 6, the BtA is further adjusted in the
direction of and
in proportion to the manual command using the BtA due to parallel lift as a
new zero
point for BtA change rate. Naturally, the maximum rate of change for BtA is
the
same as the maximum rate of change for BtA with parallel lift disabled. In
Figure 6,
the absolute value of 2000 represents a maximum command rate for the bucket
and
the absolute value of 1000 represents the parallel lift command rate. In this
particular case, the controller 100 sets the values of 1000 and -1000 for
parallel lift
curl and parallel lift dump, respectively. As can be readily observed in
Figure 6, the
controller 100 will, for this function, generate controller bucket command
signals 102
proportional to the degree of manipulation of the joystick 21 between the
absolute
values of 1000 and the absolute values of 2000, using the absolute value of
1000 as
the zero point, i.e., the target for controller bucket command signal 102 with
no
manipulation of the bucket command input device 21 and the absolute value of
2000
as the maximum, i.e., the target for the controller bucket command signal 102
with
the maximum degree of manipulation of the joystick 21. Of course the absolute
value of 1000 is referenced here merely for illustrative purposes. In reality
the value
used as a point of reference is dynamic, and changes as the boom command
signal
29 changes or as the actual rate of change in the BmA changes.
This arrangement allows for greater control of the bucket 36 as the change in
rate of the BtA with respect to the parallel lift function is proportional to
the degree of
manipulation of the bucket command input device 21.
RETURN TO CARRY, RETURN TO DIG AND BOOM HEIGHT KICKOUT
During the operation of the loader portion 30 of a backhoe loader 10 it is
oftentimes convenient for the operator to establish automatic functions such
as, for
example, return to carry (RTC), return to dig (RTD, and boom height kickout
(BHK).
The invention provides for these functions.
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RETURN TO CARRY
Return to carry, i.e., RTC is a function that enables an operator to command
the vehicle 10 to automatically locate the boom 31 at a first predetermined
BmA such
as, for example, a1 in Figure 7. The first predetermined BmA is set when the
operator commands the boom 31 to move to a1 and, by means of a button 58,
records a1 in the system, i.e., the controller 100, as a predetermined BmA for
RTC.
To execute RTC, the operator pushes the electronic joystick 21 to a first
detent position 21a, illustrated in Figure 8, in which a detent is felt which
is,
generally, at the end of travel for the joystick 21. The joystick 21 then
generates a
first detent command signal 28a. The controller 100 receives the first detest
command signal 28a then, if the BmA is greater than cr1, the controller 100
generates controller boom command signals 102 to move the boom 31 in the
direction of a1. If the joystick 21 is released to return to the neutral
position 21 a, to
which it is biased, prior to the boom achieving and angle of a1 the controller
100 will
continue to generate controller boom command signals 102 to move the boom 31
toward a1 until the boom 31 achieves the angle a1. When the boom angle signal
54a indicates that the boom has achieved a1, the controller 100 stops
generating the
controller boom command signals 102 resulting from the first detent signal 28.
Figure 9 illustrates the initiation and operation of RTC in a more detailed
and
visual manner. As illustrated in Figure 9, the RTC function can begin only
when the
operator pushes the electronic joystick 21 to the first detent position 21a at
step 200,
at which point it generates the first detent command signal 29a. The
controller 100
compares BmA to a1 at step 210 and initiates RTC at step 220 if BmA is greater
than a1. The controller 100 then initiates a return to carry command mode and
generates controller boom command signals 103 at step 220 to move the boom 31
in
the direction of a1. The controller 100 then checks to see whether the
joystick 21
has returned to and moved out of the neutral position 21 c in the direction of
21 a or
21 b at step 230. If the answer is yes, the controller 100 resumes
manualcontrol. If
the answer is no, the controller 100 then checks to see if the relationship al
< BmA <_
a1 + 100 is true at step 240. In this embodiment the 100 in the relationship
is a
cushion start angle. The cushion start angle could be set at any value. If the
equation is not true then the controller boom command signals 103 are sent to
the
boom electrohydraulic circuit 51 at step 245. If the equation is true, then,
at step
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250, the controller boom command signals 103 are lowered as a function of X,
where
X is the distance of the boom 31 from the target at a1. In this particular
embodiment,
the boom command equals Xo.75 + Offset, where Offset represents a minimum
command at the end of any automatic function of the loader portion 30. The
controller 100 then checks to see if the equation, BmA = a1, is true at step
260. If
the equation is not true, then the controller 100 sends the lowered command
signal
to the boom electrohydraulic circuit 51 at step 255. if the equation is true,
the
controller 100 resumes the manual command mode at step 270.
BOOM HEIGHT KICKOUT
Boom height kickout is a function that enables an operator to command the
vehicle 10 to automatically locate the boom 31 at a second predetermined BmA
such
as, for example, a2 in Figure 6. The second predetermined BmA is set when the
operator commands the boom 31 to move to a2 and, by means of a button 58,
records a2 in the system, i.e., the controller, as a predetermined BmA for
boom
height kickout.
To execute boom height kickout, the operator pulls the electronic joystick 21,
illustrated in Figure 8, to a second detent position 21 b in which a detent is
felt which
is, generally, at the end of travel for the joystick 21. The joystick 21 then
generates a
second detent command signal 28b. The controller 100 receives the second
detent
command signal 28b then, if the BmA is less than a2, the controller 100
generates
controller boom command signals 10 to move the boom 31 in the direction of a2.
If
the joystick 21 is released to return to the neutral position 21c, to which it
is biased,
prior to the boom achieving and angle of a2 the controller 100 will continue
to
generate controller boom command signals 102 to move the boom 31 toward a2
until the boom 31 achieves the angle a1. When the boom angle signal 54a
indicates
that the boom has achieved a1, the controller 100 stops generating the
controller
boom command signals 102 resulting from the second detent command signal 28b.
Figure 10 illustrates the initiation and operation of the boom height kickout
function in a more detailed and visual manner. As illustrated in Figure 7, the
boom
height kickout function can begin only when the operator pulls the electronic
joystick
21 to the second detent position 21 b at step 300, at which point it generates
the
second detent command signal 28b. The controller 100 compares BmA to a2 at
step 310 and initiates boom height kickout at step 320 if BmA is less than a1.
The
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controller 100 then initiates a boom height kickout command mode and in which
it
generates controller boom command signals 102 at step 320 to move the boom 31
in
the direction of a2. The controller 100 then checks too see if the joystick 21
has
returned to neutral 21 c and moved out of neutral in the direction of 21 a or
21 b at
step 330. If the answer is yes, the controller 100 resumes the manual command
mode at step 335. If the answer is no, the controller 100 then checks to see
if the
relationship a2 > BmA _> a2 - 100 is true at step 340. If the relationship is
not true
then the controller boom command signals 103 are sent to the boom
electrohydraulic
circuit 51 at step 335 and the process starts again at step 330. If the
equation is
true, then, at step 350, the controller boom command signals 103 are lowered
as a
function of X, where X is the distance of the boom 31 from the target at a1 at
step
350. In this particular embodiment, the boom command equals X .75 - Offset,
where
Offset represents a minimum command at the end of any automatic function of
the
loader portion 30. The controller 100 then checks to see if the equation, BmA
= Q2,
is true at step 360. If the equation is not true, then the controller 100
sends the
lowered command signal to the boom electrohydraulic circuit 51 at step 365 and
starts the process over at step 330. If the equation is true, the controller
100
resumes the manual command mode at step 370.
In this embodiment the 10 in the above relationship is a cushion start angle.
The cushion start angle could be set at any value.
If the joystick is moved to the first detent position when the boom is at or
below the return to carry position, the controller 100 executes a float
function where
the cylinders 32, 33 are free to extend and retract under the influence of
gravity
allowing the boom to fall to the lowest point allowed by the ground and for
the boom
and bucket to follow the contours of the ground as the vehicle moves over the
ground. The controller 100 may execute the float function by conventional
means.
RETURN TO DIG
Return to dig is a function that enables an operator to command the vehicle
to automatically locate the bucket 36 at a return to dig Bta, 131, and a
return to dig
angle a,td suitable for digging. R1 and artd are set when the operator
commands the
bucket 36 to move to 131 and, by means of a button 58, records 131 in the
system, i.e.,
the controller 100, as a predetermined return to dig BtA and a predetermined
bucket
to frame angle artd for return to dig. Return to dig is, generally, used to
place the
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bucket 36 in and angular position favored for digging or scooping up material.
When
the controller 100 executes return to dig it suspends parallel lift if it is
active. When
the bucket 36 reaches the return to dig BtA, parallel lift is resumed if the
controller
100 detects that it is still active and maintains arts. In this manner, the
controller 100
will maintain the bucket orientation at artd until the parallel lift function
is completed.
To execute return to dig, the operator moves the electronic joystick 21,
illustrated in Figure 8, to a third detent position 21d in which a detent is
felt which is,
generally, at the end of travel for the joystick 21. The joystick 21 then
generates a
third detent command signal 28c. The controller 100 receives the third detent
command signal 28c then, if the BtA is greater than (31, the controller 100
generates
controller bucket command signals 103 to move the bucket 36 in the direction
of 01
via dumping. If BtA is less than 01, the controller generates controller
bucket
command signals to move the bucket 36 in the direction of 131 via curling. If
the
joystick 21 is released to return to the neutral position 21c, to which it is
biased, prior
to the bucket 36 achieving an angle of R1 the controller 100 will continue to
generate
controller bucket command signals 103 to move the bucket 36 toward f31 until
the
bucket 36 achieves the angle 131. When the bucket angle signal 55a indicates
that
the bucket has achieved (31, the controller 100 stops generating the
controller bucket
command signals 103 resulting from the third detent command signal 28c.
Figure 11 illustrates the initiation and operation of the return to carry
function
in a more detailed and visual manner. As illustrated in Figure 11, the return
to dig
function can begin only when the operator moves the electronic joystick 21 to
the
third detent position 21d at step 400, at which point it generates the third
detent
command signal 28c. The controller 100 compares BtA to (31 at step 410 and
initiates returned to carry at step 420 if BtA is not equal to (31. The
controller 100
then enters a return to dig mode and generates controller bucket command
signals
103 at step 420 to drive the bucket 36 to R1. The controller 100 then checks
too see
if the joystick 21 has returned to neutral 21 c and moved out of neutral in
the direction
of 21 d or 21 a at step 430. If the answer is yes, the controller 100 resumes
the
manual command mode at step 435. If the answer is no, the controller 100 then
checks to see if the bucket 36 is dumping at step 440. If the bucket 36 is
dumping at
step 440, i.e., the BtA is increasing, the controller 100 determines if a
first equation
BtA <_ X31 + 100 is true at step 440. If the first equation is not true then
the controller
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bucket command signals 103 are sent to the bucket electrohydraulic circuit 61
at
step 455 and the process starts over at step 430. If the first equation is
true, then, at
step 460, the controller boom command signals 103 are lowered as a function of
X,
where X is the distance of the boom 31 from the target at 61 at step 350. In
this
particular embodiment, the boom command equals X075+ Offset, where Offset
represents a minimum command at the end of any automatic function of the
loader
portion 30. The controller 100 then checks to see a second equation, BtA =
(31, is
true at step 470. If the second equation is not true, then the controller 100
sends the
lowered command signal to the bucket electrohydraulic circuit 61 at step 455
and
starts the process over at step 430. If the second equation is true, the
controller 100
resumes the manual command mode at step 480.
If, at step 440, the controller 100 determines that the bucket 36 is curling,
i.e.,
BtA is decreasing, the controller determines whether a third equation BtA >_
(31 - 100
is true at step 445. If the third equation is not true then the controller
bucket
command signals 103' are sent to the bucket electrohydraulic circuit 61 at
step 455
and the process is restarted at step 430. If the third equation is true, then,
the
process is moved to step 460 and proceeds as described above.
In this embodiment the 100 values in the above relationships are cushion start
angles. The cushion start angles could be set at any values.
if return to carry and return to dig are executed such that they are both
functioning at the same time, the controller 100 may reduce the controller
boom
command signals 103 to allow a completion of return to dig prior to a
completion of
return to carry to prevent the bucket 36 from contacting the ground at a wrong
angle.
ANTI-SPILL
Anti-spill is an automatic bucket control feature that restricts the bucket 36
from being curled past a predetermined bucket to frame position aata once a
predetermined boom to frame position BmAata is realized or exceeded. The
purpose
of this feature is to prevent the spilling of material in the bucket 36 onto
the hood 21
or the cab 20 of the vehicle 10. When anti-spill is activated the controller
100 will
override any function, including, inter alia, parallel lift and return to dig
when that
function demands a bucket to frame position a curled past the predetermined
bucket
to frame position aata and adjusts the bucket 36 in the dumping direction when
the
boom is raised beyond BmAata, i.e., within the anti-spill zone. In this
particular
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embodiment, the controller 100 generates controller bucket command signals 103
to
drive the bucket 36 to the anti-spill target angle aata., i.e., to adjust the
bucket 36 to a
position such that a = data. The controller 100 suspends this process only
when: (1)
the boom 31 is no longer moving; (2) the boom 31 is adjusted downwardly while
still
in the anti-spill zone; (3) the boom 31 is outside of the anti-spill zone; or
(4) the
operator manipulates the joystick 21 to generate a bucket command signal 29 to
dump.
BmAata and aata are separately set via menu selections using buttons 120a,
120b, 120c, 120d and the screen 118 on the monitor 120 illustrated in Figure
13.
However, anti-spill target setting may be accomplished by any appropriate and
well-
known conventional means such as, for example, separate button switches or
multi-
function button switches. Regardless of how the predetermined angles BmAata
and
aata are set, anti-spill is a feature that is activated when the vehicle 10 is
powered up.
Figure 12 illustrates the operation of the anti-spill function in a more
detailed
and visual manner. As illustrated in Figure 12, the anti-spill function begins
when the
vehicle 10 is powered up at step 500, at which point the controller 100, at
step 510,
sets BmAata and aata as minimum target angles whether these predetermined
angles
are factory settings or custom settings by the operator. The controller 100
then
determines if a first anti-spill relationship BmA <_ BmAata is true at step
520. If the first
anti-spill equation is not true, no overriding anti-spill bucket commands are
generated and the controller 100 makes another determination on the first anti-
spill
equation, at step 520, at the next sample time which is determined by a
predetermined sample rate. If the first anti-spill relationship is true, the
controller 100
determines whether a second anti-spill relationship, a:5 ata is true at step
530. If the
second anti-spill relationship is not true, no overriding anti-spill bucket
commands
are generated and the controller 100 begins the process again by determining
whether the first anti-spill equation is true at step 520. Once the controller
100
determines that the first and second anti-spill equations are true at steps
520 and
530, the controller determines whether the controller 100 boom command signal
102
is commanding a decrease in BmA, i.e., determines whether BmA is decreasing.
If
BmA is not decreasing, no overriding anti-spill bucket commands are generated
and
the controller 100 returns to step 520 to determine whether the first anti-
spill
relationship is true at the next sample time. Once the controller 100
determines that
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the first and second anti-spill relationships are true at steps 520 and 530
and that
BmA is decreasing at step 540, i.e., the boom 31 is rising, the controller
100, at step
550, generates controller bucket command signals 102 to drive the bucket 36 to
aata
and repeats the entire process again starting at step 520 at the next sample
time.
The illustration in Figure 12 demonstrates that the controller 100 will
override
any bucket commands once the conditions for the anti-spill function are met.
Thus, if
the operator is curling the bucket 36 past aata after the boom 31 enters the
anti-spill
zone, the controller 100 will generate controller bucket command signals 102
to drive
the bucket 36 to aata. Further, if the bucket 36 is being dumped via parallel
lift when
the boom enters the anti-spill zone and the bucket to frame angle a is less
than or
equal to aata, the controller 100 will override parallel lift and generate
controller
bucket command signals 102 to drive the bucket 36 to aata. Finally, if the
boom 31 is
within the anti-spill zone the and bucket to frame angle a is, for any reason,
less than
or equal to aata, the controller 100 will override parallel lift and generate
controller
bucket command signals 102 to drive the bucket 36 to aata.
In this particular embodiment, BmAata may be set only when the BmA is
between -6 and +20 and aata maybe set only when the bucket angle a miss
between +6 and +17 . Successful or unsuccessful target setting is indicated
by an
audible signal and/or a message via the monitor 120 illustrated in Figures 13
and 14.
Unsuccessful target setting may be indicated on a display in words such as,
for
example, "Out of Range" on the monitor screen 118. If no custom targets are
set by
the operator, the anti-spill function uses a the factory set targets.
ALTERNATE EMBODIMENT OF THE INVENTION
Figure 15 illustrates a schematic representing an alternate exemplary
embodiment of the invention. In Figure 15, a loader boom actuator 50, having a
loader boom hydraulic cylinder 633 extending between the vehicle frame 12 and
the
loader boom 31, controllably moves the loader boom 31 about the loader boom
pivot
12a. The loader boom hydraulic cylinder 33 is pivotally attached to the frame
12 at a
first loader boom hydraulic cylinder pivot 33a and pivotally attached to the
loader
boom 31 at a second loader boom hydraulic cylinder pivot.
A loader bucket actuator 660, having a loader bucket hydraulic cylinder 32
extending between the loader boom 631 and the loader bucket 36, controllably
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moves the loader bucket 36 about the loader bucket pivot 36a. In the
illustrated
embodiment, the loader bucket actuator 660 comprises a bucket electro-
hydraulic
circuit 661 hydraulically coupled to the loader bucket hydraulic cylinder 632.
The
controller 670 controls the bucket electro-hydraulic circuit 661 which
supplies and
controls the flow of hydraulic fluid to the loader bucket hydraulic cylinder
632. Note
that the bucket hydraulic circuit 61 are conventionally configured.
The operator commands movement of the loader assembly 30 by
manipulating a loader bucket command input device such as, for example a
joystick
621 and a loader boom command input device such as, for example the joystick
21.
The joystick 21 is adapted to generate a loader bucket command signal 628 in
proportion to a degree of manipulation by the operator and proportional to a
flow rate
of fluid to the bucket hydraulic cylinder 632 which is indirectly proportional
to an
angular speed of a desired loader bucket movement. The controller 670, in
communication with the loader bucket command input device 621 and loader
bucket
actuator 660, receives the loader bucket command signal 628 and responds by
generating a controller bucket command signal 672 proportional to the bucket
command signal 628, which is received by the loader bucket electro-hydraulic
circuit
661. The loader bucket electro-hydraulic circuit 661 responds to the
controller
bucket command signal 672 by directing hydraulic fluid to and from the loader
bucket
hydraulic cylinder 632, causing the hydraulic cylinder 632 to extend and
retract and
curl and dump the loader bucket 636 accordingly.
The joystick 621 is adapted to generate a loader boom command signal 629
in proportion to a degree of manipulation in a first direction of the joystick
621 by the
operator, the boom command signal 629 being proportional to a flow rate of
fluid to
the hydraulic boom cylinder 633 and indirectly proportional to a speed of a
desired
loader boom movement. The controller 670, in communication with the joystick
621
and loader boom cylinder 633, receives the loader boom command signal 629 and
responds by generating a controller boom command signal 673 proportional to
the
loader boom command signal 629, which is then used conventionally by a
hydraulic
circuit to adjust the length of the hydraulic boom cylinder 631.
In this embodiment the controller 670 uses angular signals from a tilt sensor
C
to determine the angle of the bucket with respect to the ground aground. to
execute the
parallel lift function.
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Having described the illustrated embodiment, it will become apparent that
various modifications can be made without departing from the scope of the
invention
as defined in the accompanying claims. One such modification would be the
addition of a tilt sensor to the frame 12 of the vehicle 10. This would allow
all
angular signals to reference the earth as well as the frame 12.
