U.S. patent application number 14/496685 was filed with the patent office on 2015-01-08 for anti-bounce control system for a machine.
This patent application is currently assigned to Caterpillar Inc.. The applicant listed for this patent is Caterpillar Inc.. Invention is credited to Sam M. Kherat, Owen Kolstad, Phillip Newberry, Michael Subrt, Yongliang Zhu.
Application Number | 20150008006 14/496685 |
Document ID | / |
Family ID | 49511681 |
Filed Date | 2015-01-08 |
United States Patent
Application |
20150008006 |
Kind Code |
A1 |
Zhu; Yongliang ; et
al. |
January 8, 2015 |
ANTI-BOUNCE CONTROL SYSTEM FOR A MACHINE
Abstract
A system for automated control of a motor grader includes a
first sensor to indicate bounce of the motor grader and a speed
sensor to indicate the ground speed. A controller determines a
maximum amplitude of the bounce of the motor grader and controls
the ground speed of the motor grader at least in part based upon
the maximum amplitude of the bounce. A method is also provided.
Inventors: |
Zhu; Yongliang; (Dunlap,
IL) ; Newberry; Phillip; (Taylorville, IL) ;
Kolstad; Owen; (Peoria, IL) ; Subrt; Michael;
(Chillicothe, IL) ; Kherat; Sam M.; (Peoria,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Caterpillar Inc. |
Peoria |
IL |
US |
|
|
Assignee: |
Caterpillar Inc.
Peoria
IL
|
Family ID: |
49511681 |
Appl. No.: |
14/496685 |
Filed: |
September 25, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13465875 |
May 7, 2012 |
8869908 |
|
|
14496685 |
|
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Current U.S.
Class: |
172/3 ; 172/4.5;
701/50 |
Current CPC
Class: |
E02F 3/841 20130101;
E02F 9/2025 20130101; E02F 9/265 20130101 |
Class at
Publication: |
172/3 ; 701/50;
172/4.5 |
International
Class: |
E02F 3/84 20060101
E02F003/84; E02F 9/20 20060101 E02F009/20 |
Claims
1. A system for automated control of movement of a motor grader,
the motor grader including a prime mover and a ground engaging
blade, comprising: a first sensor disposed on the motor grader
configured to provide a bounce signal indicative of a measured
bounce of the motor grader; a speed sensor disposed on the motor
grader configured to provide a speed signal indicative of a ground
speed of the motor grader; and a controller configured to: receive
the bounce signal from the first sensor; determine a maximum
amplitude of the measured bounce of the motor grader based upon the
bounce signal; and generate a command signal to apply a brake at
least in part based upon the maximum amplitude of the measured
bounce, the brake reducing the ground speed of the motor
grader.
2. The system of claim 1, wherein the controller is further
configured to determine the maximum amplitude of the measured
bounce in a first direction and within a first frequency range.
3. The system of claim 2, wherein the controller is further
configured to determine the maximum amplitude of the measured
bounce in a second direction and within a second frequency
range.
4. The system of claim 3, wherein the first frequency range is
different from the second frequency range.
5. The system of claim 3, wherein the controller is further
configured to determined the maximum amplitude of the measured
bounce in a third direction and within a third frequency range.
6. The system of claim 1, wherein the command signal reduces the
speed of the prime mover.
7. A controller implemented method of adjusting movement of a motor
grader, the motor grader having a prime mover, a ground engaging
blade, a first sensor configured to provide a bounce signal
indicative of a measured bounce of the motor grader, and a speed
sensor disposed on the motor grader configured to provide a speed
signal indicative of a ground speed of the motor grader,
comprising: receiving the bounce signal from the first sensor;
determining a maximum amplitude of the measured bounce of the motor
grader based upon the bounce signal; and generating a command
signal within the controller to apply a brake at least in part
based upon the maximum amplitude of the measured bounce, the brake
reducing the ground speed of the motor grader.
8. The controller implemented method of claim 7, further including
determining the maximum amplitude of the measured bounce in a first
direction and within a first frequency range.
9. The controller implemented method of claim 8, further including
determining the maximum amplitude of the measured bounce in a
second direction and within a second frequency range.
10. The controller implemented method of claim 7, further including
reducing the speed of the prime mover.
11. A motor grader comprising: a prime mover; a ground engaging
blade; a first sensor disposed on the motor grader configured to
provide a bounce signal indicative of a measured bounce of the
motor grader; a speed sensor disposed on the motor grader
configured to provide a speed signal indicative of a ground speed
of the motor grader; and a controller configured to: receive the
bounce signal from the first sensor; determine a maximum amplitude
of the measured bounce of the motor grader based upon the bounce
signal; and generate a command signal to apply a brake at least in
part based upon the maximum amplitude of the measured bounce, the
brake reducing the ground speed of the motor grader.
12. The motor grader of claim 11, wherein the controller is further
configured to determine the maximum amplitude of the measured
bounce in a first direction and within a first frequency range.
13. The motor grader of claim 12, wherein the controller is further
configured to determine the maximum amplitude of the measured
bounce in a second direction and within a second frequency
range.
14. The system of claim 1, wherein the controller is further
configured to receive an operator-generated prime mover command
signal from an operator and the command signal generated by the
controller temporarily overrides the operator-generated prime mover
command signal.
15. The system of claim 14, wherein the controller temporarily
overrides the operator-generated prime mover command signal while
the measured bounce exceeds a predetermined value.
16. The controller implemented method of claim 7, further including
receiving an operator-generated prime mover command signal from an
operator and temporarily overriding the operator-generated prime
mover command signal with the command signal generated by the
controller.
17. The controller implemented method of claim 16, wherein the
operator-generated prime mover command signal is temporarily
overridden while the measured bounce exceeds a predetermined
value.
18. The motor grader of claim 11, wherein the controller is further
configured to receive an operator-generated prime mover command
signal from an operator and the command signal generated by the
controller temporarily overrides the operator-generated prime mover
command signal.
19. The motor grader of claim 18, wherein the controller
temporarily overrides the operator-generated prime mover command
signal while the measured bounce exceeds a predetermined value.
20. The system of claim 1, wherein the brake is one of a service
brake and a parking brake.
Description
[0001] This is a continuation of application Ser. No. 13/465,875,
filed May 7, 2012, the disclosure of which is incorporated by
reference.
TECHNICAL FIELD
[0002] This disclosure relates generally to controlling a machine
and, more particularly, to a control system for reducing harmonic
vibrations of the machine.
BACKGROUND
[0003] Certain machines such as motor graders have a natural
frequency that may negatively affect their operation due to
resonance at such natural frequency. The natural frequency of a
motor grader is a function of numerous physical characteristics of
the machine such as its weight distribution, the distance between
the rear wheels and the moldboard, and the tire characteristics. In
addition, the operating conditions encountered by the motor grader
may also affect the natural frequency. Excitation at the natural
frequency may result in harmonic vibrations within the motor grader
commonly referred to as "bounce."
[0004] Harmonic vibrations or bounce typically occur when the motor
grader is operated within a particular range of speeds and with a
light load on the blade or moldboard. The movement caused by the
bouncing condition may interrupt the contact between a work surface
and the moldboard which may result in an uneven finish or scallop
on the work surface. Such an uneven finish may require reworking of
the work surface or the application of additional material for
proper finishing.
[0005] Motor graders may experience three different types of
harmonic vibrations or bounce: pitching, side-to-side or
"duck-walk," and vertical vibrations or bounce. Each of these types
of harmonic vibrations or bounce conditions may negatively impact a
grading operation. Harmonic vertical movement or bounce generally
occurs at a frequency between 1.5 and 3 Hz.
[0006] U.S. Patent Publication No. 2010/0051298 A1 discloses a
system for detecting and dissipating hydraulic spikes in pressure
caused when implements of a machine bounce. The pressure spikes are
dissipated by generating random or canceling pulses within the
hydraulic system.
[0007] The foregoing background discussion is intended solely to
aid the reader. It is not intended to limit the innovations
described herein, nor to limit or expand the prior art discussed.
Thus, the foregoing discussion should not be taken to indicate that
any particular element of a prior system is unsuitable for use with
the innovations described herein, nor is it intended to indicate
that any element is essential in implementing the innovations
described herein. The implementations and application of the
innovations described herein are defined by the appended
claims.
SUMMARY
[0008] The disclosure describes, in one aspect, a system for
automated control of movement of a motor grader having a prime
mover and a ground engaging blade. A first sensor is disposed on
the motor grader and is configured to provide a bounce signal
indicative of a measured bounce of the motor grader. A speed sensor
is disposed on the motor grader and is configured to provide a
speed signal indicative of a ground speed of the motor grader. A
controller is configured to receive the bounce signal from the
first sensor and determine a maximum amplitude of the measured
bounce of the motor grader based upon the bounce signal. The
controller is further configured to generate a command signal to
control the ground speed of the motor grader at least in part based
upon the maximum amplitude of the measured bounce and transmit the
command signal to change the speed of the motor grader.
[0009] In another aspect, the disclosure describes a controller
implemented method of adjusting movement of a motor grader having a
prime mover, a ground engaging blade, a first sensor configured to
provide a bounce signal indicative of a measured bounce of the
motor grader, and a speed sensor disposed on the motor grader
configured to provide a speed signal indicative of a ground speed
of the motor grader. The method includes receiving the bounce
signal from the first sensor and determining a maximum amplitude of
the measured bounce of the motor grader based upon the bounce
signal. The method further includes generating a command signal
within the controller to control the ground speed of the motor
grader at least in part based upon the maximum amplitude of the
measured bounce and transmitting the command signal from the
controller to change the speed of the motor grader.
[0010] In still another aspect, the disclosure describes a motor
grader including a prime mover, a ground engaging blade, a first
sensor is disposed on the motor grader and is configured to provide
a bounce signal indicative of a measured bounce of the motor
grader, and a speed sensor is disposed on the motor grader and is
configured to provide a speed signal indicative of a ground speed
of the motor grader. A controller is configured to receive the
bounce signal from the first sensor and determine a maximum
amplitude of the measured bounce of the motor grader based upon the
bounce signal. The controller is further configured to generate a
command signal to control the ground speed of the motor grader at
least in part based upon the maximum amplitude of the measured
bounce and to transmit the command signal to change the speed of
the motor grader.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a side elevational view of a motor grader
constructed in accordance with the disclosure;
[0012] FIG. 2 is a block diagram of an anti-bounce control system
in accordance with the disclosure;
[0013] FIG. 3 is a flowchart illustrating an anti-bounce control
process in accordance with the disclosure;
[0014] FIG. 4 is an exemplary graph of a simulation of vertical
bounce of a motor grader;
[0015] FIG. 5 is an exemplary graph depicting a simulation of gas
pedal displacement corresponding to the vertical bounce depicted in
FIG. 5;
[0016] FIG. 6 is an enlarged view of the portion identified at 6 in
FIG. 4;
[0017] FIG. 7 is an enlarged view of the portion identified at 7 in
FIG. 5;
[0018] FIG. 8 is an exemplary graph, similar to FIG. 6, depicting
simulated vertical bounce of a motor grader incorporating the
anti-bounce control system in accordance with the disclosure;
and
[0019] FIG. 9 is an exemplary graph, similar to FIG. 7, depicting a
simulation of a gas pedal displacement command from an operator as
well as a command generated by the anti-bounce control system when
overriding the operator command.
DETAILED DESCRIPTION
[0020] FIG. 1 is a diagrammatic illustration of machine such as a
motor grader 10 that may be used in accordance with an embodiment
of the disclosure. The motor grader 10 includes a frame 11 and a
prime mover such as an engine 12. A set of front wheels 13 may be
operatively connected to the frame 11 generally adjacent a front
end of the motor grader 10 and two sets of rear wheels 14 may be
operatively connected to the frame 11 generally adjacent a rear end
of the motor grader. In an alternate embodiment, only a single set
of rear wheels 14 may be provided. One or both sets of rear wheels
14 may be powered by a power transfer mechanism (not shown)
operatively connected to the engine 12. The power transfer
mechanism may be any desired type of drive system including a
hydrostatic propulsion system, an electric drive system or a
mechanical drive system. An operator cab 15 may be mounted on the
frame 11 and includes various controls, sensors and other
mechanisms used by an operator.
[0021] A blade or moldboard 20 extends downward from the frame 11.
The moldboard 20 may be mounted on a blade tilt adjustment
mechanism 21 that is supported by a rotatable circle assembly 22
operatively connected to the blade tilt adjustment mechanism 21. A
variety of hydraulic cylinders or other mechanisms may be provided
for controlling the position of the moldboard 20. For example,
circle assembly 22 may be supported by a pair of blade lift
actuators 23 (with only one visible in FIG. 1). Adjustment of the
blade lift actuators 23 allows the height of rotatable circle
assembly 22, and hence the height of moldboard 20, to be adjusted.
Blade lift actuators 23 may be moved independently or in
combination with each other. A center shift cylinder 24 may be
provided to shift the circle assembly 22 from side-to-side. A blade
tip cylinder 25 may be provided to control the angle between an
edge of the moldboard 20 and the ground. One or more side shift
cylinders (not shown) may be provided to control lateral movement
of the moldboard 20 relative to the circle assembly 22. The circle
assembly 22 may include a mechanism such as gear teeth to allow
rotation of the moldboard 20. Other manners of positioning and
controlling the moldboard 20 may be utilized if desired.
[0022] Motor grader 10 may be equipped with a plurality of sensors
that provide data indicative (directly or indirectly) of the
performance or conditions of various aspects of the machine. An
operator presence sensor 30 may be provided to sense whether an
operator is seated within the operator cab 15. A parking brake
sensor 31 may be provided to sense whether the parking brake is
engaged. A transmission output speed sensor 32 may be provided for
sensing the output speed from a transmission (not shown). A wheel
speed sensor 33 may be provided for sensing the speed of the rear
wheels 14 and thus indicate the ground speed of the motor grader
10.
[0023] One or more bounce sensors may be provided for sensing the
bounce or movement of the motor grader 10. In one embodiment, a
first sensor such as an accelerometer 34 may be provided on motor
grader 10. The first sensor may be used to provide an acceleration
signal indicative of measured acceleration of the motor grader 10
relative to a gravity reference. In one example, the first sensor
may provide measurements in six degrees of freedom (i.e., fore-aft,
lateral, and vertical directions as well as pitch, roll and yaw).
In an alternate embodiment, the first sensor may be a three-axis
accelerometer providing an acceleration signal indicative of
measured acceleration of the motor grader along fore-aft, lateral
and vertical directions. In another alternate embodiment, the first
sensor may be a single-axis accelerometer providing the measurement
of the mixed acceleration of the motor grader along fore-aft,
lateral and vertical directions. By monitoring the acceleration at
the first sensor, movements of the motor grader 10 may be detected
that are indicative of motor grader bounce. In some circumstances,
it may be desirable to place the first sensor generally adjacent
the rear wheels 14. Still further, it may be desirable to position
the first sensor generally adjacent operator cab 15 so that
movement sensed by the first sensor somewhat matches movement
sensed by the operator.
[0024] In another alternate configuration, the first sensor may
include one or more hydraulic pressure sensors 35 associated with
some or all of the hydraulic cylinders that are used to control the
moldboard 20, the blade tilt adjustment mechanism 21 and the circle
assembly 22. By monitoring the pressure and pressure changes in the
cylinders, specific pressure characteristics may be monitored that
are indicative of motor grader bounce. Other types of sensors are
also contemplated.
[0025] A control system 40 may be provided to control the operation
of the motor grader 10 including the anti-bounce control aspects or
functionality of the machine. The control system 40, as shown
generally by an arrow in FIG. 1 indicating association with the
motor grader 10, may include an electronic control module such as
controller 41. The controller 41 may receive operator input command
signals and control the operation of the various systems of the
motor grader 10. The controller 41 is shown in FIG. 1 residing in
the operator cab 15 but may be mounted at any convenient location
on motor grader 10. The control system 40 may include one or more
input devices (not shown) to control the motor grader 10 and one or
more sensors, including the operator presence sensor 30, the
parking brake sensor 31, the transmission output speed sensor 32,
the wheel speed sensor 33, and the first sensor, to provide data
and other input signals representative of various operating
parameters of the motor grader 10.
[0026] The controller 41 may be an electronic controller that
operates in a logical fashion to perform operations, execute
control algorithms, store and retrieve data and other desired
operations. The controller 41 may include or access memory,
secondary storage devices, processors, and any other components for
running an application. The memory and secondary storage devices
may be in the form of read-only memory (ROM) or random access
memory (RAM) or integrated circuitry that is accessible by the
controller. Various other circuits may be associated with the
controller such as power supply circuitry, signal conditioning
circuitry, driver circuitry, and other types of circuitry.
[0027] The controller 41 may be a single controller or may include
more than one controller disposed to control various functions
and/or features of the motor grader 10. The term "controller" is
meant to be used in its broadest sense to include one or more
controllers and/or microprocessors that may be associated with the
motor grader 10 and that may cooperate in controlling various
functions and operations of the machine. The functionality of the
controller 41 may be implemented in hardware and/or software
without regard to the functionality. The controller 41 may rely on
one or more data maps relating to the operating conditions of the
motor grader 10 that may be stored in the memory of controller.
Each of these maps may include a collection of data in the form of
tables, graphs, and/or equations. The controller 41 may use the
data maps to maximize the efficiency of the motor grader 10.
[0028] The control system 40 may include an anti-bounce control
system or functionality for assisting in controlling certain types
of harmonic movement of the motor grader 10 known as bounce. In
doing so, the controller 41 may be configured to receive as input
values the amplitudes of movement of the motor grader 10 at certain
frequencies at which bounce is likely to occur. Threshold values of
the amplitude of the motor grader movement at each of specified or
predetermined frequencies may be stored as a portion of the data
maps to assist in determining the existence of a bounce condition.
Maps of responses to motor grader bounce exceeding the threshold
value may be established and stored within the controller 41. Such
maps may utilize various factors including the speed of the motor
grader 10, the extent to which the amplitude of the bounce exceeds
the threshold value, and the frequency of the bounce condition.
Other operating conditions and characteristics of the motor grader
10 may also be related in the data maps.
[0029] During the operation of the motor grader 10, as described in
more detail below, the anti-bounce control functionality of control
system 40 may modify the operating conditions of the motor grader
to eliminate or reduce motor grader bounce. In one example, once
the controller 41 determines that a bounce condition exists, it may
override the gas pedal control command directed by the operator so
as to reduce the engine speed and thus reduce the speed of the
motor grader 10. Once the bounce condition has been sufficiently
eliminated or reduced, the anti-bounce control functionality of the
control system 40 is disengaged and no longer affects the operation
of the engine 12 so that the engine speed is returned to that
directed by the operator.
[0030] As depicted in FIG. 2, the controller 41 receives
information from various sensors and systems of the motor grader 10
and processes this information. Controller 41 may receive, at a
node 43, a bounce signal or signals from a bounce sensor indicative
of the bounce of the motor grader 10. The bounce sensor may be the
first sensor such as an accelerometer 34 or hydraulic pressure
sensors 35 on the hydraulic cylinders associated with the moldboard
20. At node 44, the controller 41 may receive a signal as to which
gear has been selected by the operator for operating the motor
grader 10. Such signal may be generated by another aspect of the
control system that controls the operation of the transmission of
the motor grader 10. At node 45, the controller 41 may receive a
signal as to whether an operator is seated within the operator cab
15. The operator presence signal may be provided by operator
presence sensor 30.
[0031] The controller 41 may receive a signal at node 46 as to
whether the parking brake is engaged. The parking brake signal may
be provided by a parking brake sensor 31. At node 47, the
controller 41 may receive a signal as to the status of certain
diagnostics of the anti-bounce control system. At node 48, the
controller 41 may receive a signal indicative of the wheel speed of
the front or rear wheels 14. The wheel speed signal may be provided
by the wheel speed sensor 33. At node 49, the controller 41 may
receive a signal as to the status of the various sensors that
provide information to the anti-bounce control system. At node 50,
the controller 41 may receive a signal from a user switch 36 as to
whether the operator has engaged or disengaged the anti-bounce
control system.
[0032] In one embodiment, the controller 41 may generate various
output signals based upon the operation of the anti-bounce control
system. At node 51, the controller 41 may provide a command signal
such as an engine speed control command to control operation of the
engine speed. The controller 41 made provide a signal at node 52 to
communicate to other aspects of the control system 40 the status of
the anti-bounce control system.
[0033] At node 53, the controller 41 may provide a signal to an
indicator light (not shown) indicating whether the anti-bounce
control functionality is in operation. For example, if the motor
grader 10 is not in a bounce condition, the light may be off. If
the motor grader 10 is experiencing bounce and the anti-bounce
control functionality is operating, the light may be illuminated.
If the motor grader 10 is in a bounce condition but the anti-bounce
control functionality is not operating, the light may be flashing.
Examples of when the motor grader 10 may be in a bounce condition
but the anti-bounce control functionality is not operating include
when the operator has turned off the anti-bounce control
functionality or when other systems of the motor grader 10 that
control the engine speed have a higher priority and take precedence
over the anti-bounce control functionality.
[0034] Motor grader 10 may be equipped with a user interface 36 to
activate and deactivate the anti-bounce control system of the
control system 40. This user interface could be a switch or touch
screen. If the user interface 36 is not activated, motor grader 10
will operate in accordance with the operator's commands regardless
of the operating conditions encountered by the motor grader.
[0035] If the user interface 36 is activated, the control system 40
will operate in accordance with the flow chart of FIG. 3. The
controller 41 may initially perform various diagnostic and system
checks at stage 60 to determine that the anti-bounce control system
and components of the motor grader 10 are operating properly. If
any aspects of the system or components of motor grader 10 are not
operating properly, controller will not activate the anti-bounce
control functionality and the motor grader 10 will operate in
accordance with the operator's commands even if bounce conditions
are encountered.
[0036] At stage 61, the controller 41 determines whether certain
threshold conditions of the anti-bounce control system have been
met. For example, the anti-bounce control functionality may only be
operative under certain operating conditions of the motor grader
10. One required operating condition may be that the transmission
output speed must be within a predetermined range. An additional
operating condition may be that the transmission is operating in
certain predetermined gears. For example, bounce typically occurs
and needs to be controlled to reduce the damage to the ground by
the blade when the motor grader 10 is traveling between
approximately 6-9 miles per hour. Accordingly, for a motor grader
10 having a transmission (not shown) with eight forward gears, the
anti-bounce control functionality may only be operative when the
transmission is in either the third or fourth gear. Operation in
either the first or second gear may be too slow to create a bounce
condition. Operation at the fifth gear and above may be too fast
for the operator to conduct high quality grading work. As a result,
it is unlikely that high quality grading work will be impacted if
bounce conditions occur at such higher speed.
[0037] Additional required operating conditions may include the
presence of an operator in the operator's seat and the
disengagement of the parking brake. Still further, the wheel speed
sensor 33 may provide a speed signal indicative of the ground speed
of the motor grader 10. The speed signal may be monitored and the
anti-bounce control system may function only if the wheel speed is
below a predetermined threshold. For example, the controller 41 may
be configured so that the anti-bounce control functionality is
inoperative when the wheel speed is above approximately 10.5 miles
per hour. At relatively high speeds (such as those above 10.5 miles
per hour), the motor grader 10 is unlikely to be performing grading
operations and is unlikely to encounter bounce conditions that
negatively impact contact between the work surface and the
moldboard 20.
[0038] The system may be configured so that the anti-bounce control
functionality will be inoperative if any of the threshold
conditions are not met. In other circumstances, the anti-bounce
control functionality may be limited or otherwise adjusted
depending on which threshold conditions have not been met.
[0039] If the system threshold conditions have been met at stage
61, the controller 41 receives at stage 62 bounce signals from the
first or bounce sensors (such as an accelerometer 34 or hydraulic
pressure sensors 35) that are indicative of movement of the motor
grader 10. It should be noted that the natural frequency of each
motor grader 10 is a function of numerous characteristics including
weight and weight distribution, machine dimensions, and the tire
characteristics. This bounce at the natural frequency could be
triggered by various operating conditions encountered by the motor
grader 10 (such as soil conditions and profile, blade movement, and
gear and speed changes). Accordingly, when analyzing movement of
the motor grader 10 for bounce, the controller 41 analyzes, at
stage 63, the amplitude of movement of the motor grader 10 within
certain frequency ranges.
[0040] In an example of vertical bounce of a motor grader 10, the
controller 41 may analyze vertical movement of the motor grader 10
within a frequency range of between approximately 1.5 and 3 Hz.
When performing such analysis, the controller 41 may analyze at
stage 64 the amplitude of vertical movement at each frequency
within the range and determine the maximum amplitude of movement as
well as the frequency of such maximum movement.
[0041] In examples of both pitch and side-to-side bounce, the
frequency range analyzed by the controller 41 may overlap with or
be different from the frequency range of the vertical bounce. For
each type of movement, the controller 41 may analyze at stage 64
the amplitude of the particular movement at each frequency within
the range and determine the maximum amplitude of the movement as
well as the frequency of such maximum movement.
[0042] At stage 65, the controller determines whether the maximum
amplitude of movement exceeds a predetermined threshold. In one
example, this may be carried out by comparing the maximum amplitude
to data maps within the controller 41 corresponding to the specific
frequency. If the maximum amplitude does not exceed the
predetermined threshold, the anti-bounce control functionality is
not activated and the motor grader 10 will operate in accordance
with the operator's commands as any bounce conditions encountered
are insufficient to warrant the anti-bounce control system
overriding the operator commands.
[0043] If the maximum amplitude does exceed the predetermined
threshold, the controller 41 may determine at stage 66 whether any
other subsystems within control system 40 have priority over the
anti-bounce control functionality. If the anti-bounce control
functionality is being overriden, the motor grader 10 will operate
without the anti-bounce control functionality. The controller may,
at stage 67, generate a signal indicating that the motor grader 10
is operating in a bounce condition but the anti-bounce control
functionality has been overriden. This may be indicated by a
flashing indicator light within the operator cab 15.
[0044] If the anti-bounce control functionality is not being
overriden at stage 66, the controller may, at stage 68, determine
the appropriate action to eliminate the bounce condition and
generate an appropriate command signal. In one example, the
controller 41 may generate a command signal to reduce the speed of
the engine 12 to slow down the motor grader 10. In another example,
the command signal from the controller 41 may apply the service
brakes of the motor grader 10. Other manners of reducing the speed
of the motor grader 10 may be used. In some circumstances, it may
be possible to terminate the bounce condition by increasing the
speed of the motor grader 10. In such an example, the command
signal from the controller 41 may increase the speed of the engine
12. The command signal generated by the controller may be based
upon the operating conditions of the motor grader 10 as well as the
amplitude and frequency of the bounce. For example, the controller
41 may reduce the engine speed substantially more quickly for a
bounce condition that is substantially greater than the threshold
condition as compared to a bounce condition that slightly exceeds
the threshold condition.
[0045] The controller may, at stage 69, generate a signal
indicating that the motor grader 10 is operating in a bounce
condition and that the anti-bounce control functionality is
operating. This may be indicated by energizing an indicator light
within the operator cab 15. After generating the command signal,
the command signal may be transmitted to the appropriate system at
stage 70 to reduce or eliminate the bounce condition.
[0046] It should be noted that, as described above, motor grader 10
may experience three different types of bounce conditions (i.e.,
vertical, pitch and side-to-side) and at three frequencies. In
other words, vertical bounce occurs in a first direction and at a
first frequency, bounce in a pitch direction occurs in a second
direction and at a second frequency, and side-to-side bounce occurs
in a third direction and at a third frequency. They may not occur
at identical frequencies. The data maps of controller 41 may
contain data for each type of bounce and the process set forth in
FIG. 3 repeated (simultaneously or sequentially) for each type of
bounce. In doing so, controller 41 may determine a command signal
to reduce or eliminate each type of bounce but only transmit the
command signal to reduce the largest bounce.
[0047] In an alternate configuration, the controller 41 may
determine, based upon the operating conditions and input from the
three types of bounce, that an alternate or blended solution may be
desirable to reduce or eliminate the bounce. In another alternate
configuration, the controller 41 may generate a command signal that
reduces each type of bounce without immediately eliminating any
type of bounce. In still another alternate configuration, one type
of bounce may be deemed more detrimental than another so that the
controller prioritizes the generation of command signals to reduce
or eliminate a particular type of bounce first. Such prioritization
may also be dependent upon the relative amplitudes or the degree to
which each type of bounce exceeds its respective threshold.
[0048] Referring to FIG. 4, a graph of simulated vertical machine
acceleration or bounce 75 of a motor grader 10 is depicted as a
function of time. FIG. 5 depicts a simulated gas pedal displacement
command 76 from an operator corresponding to the graph of FIG. 4
depicted as a percentage of possible gas pedal movement as a
function of time and without the anti-bounce control functionality
of control system 40. FIG. 6 is an enlarged view of the section of
the graph of FIG. 4 within the box labeled 6, and FIG. 7 is an
enlarged view of the section of the graph of FIG. 5 within the box
labeled 7.
[0049] In FIGS. 5 and 7, it may be seen that as the motor grader
begins to vertically bounce, the operator may attempt to reduce the
bounce by manually reducing the displacement of the gas pedal.
However, referring to FIGS. 6-7, it may be seen that the vertical
bounce begins to take effect slightly prior to approximately 60
seconds along the graph and the operator does not act to reduce the
gas pedal displacement at 77 until approximately 67 seconds along
the graph. The vertical bounce begins to decrease and the operator
increases the gas pedal displacement at 78 corresponding to
approximately 72 seconds along the graph. However, the vertical
bounce may not have been sufficiently reduced and/or the increase
in engine speed causes the motor grader 10 to begin to bounce again
at approximately 80 seconds along the graph. The operator then
reduces the gas pedal displacement at 79 corresponding to
approximately 87 seconds along the graph to reduce the vertical
bounce. At approximately 92 seconds along the graph, the bounce is
reduced and the operator increases the gas pedal displacement at
80. In the simulation depicted in FIG. 7, the motor grader 10
experienced vertical bounce for approximately 30 seconds as the
operator made repeated attempts to reduce the bounce.
[0050] FIGS. 8-9 depict a simulation of vertical bounce 81 of motor
grader 10 and gas pedal displacement 82, respectively, with the
anti-bounce control functionality of control system 40 operational.
As the vertical bounce begins to take effect slightly prior to
approximately 60 seconds along the graph, the anti-bounce control
functionality of control system 40 overrides the gas pedal command
from the operator and automatically reduces the gas pedal
displacement at 83.
[0051] The anti-bounce control system then maintains the reduced
gas pedal command and subsequently increases the command at 84
corresponding to approximately 63 second on the graph until the gas
pedal command returns to the operator gas pedal command at 85
corresponding to approximately 66 seconds on the graph. It may be
seen by comparing FIGS. 7 and 9 that the automated control provided
by the control system 40 reduces the gas pedal displacement earlier
than the operator and reduces the gas pedal command less abruptly,
but also reduces the gas pedal command by a greater amount. As
depicted in FIG. 8, the motor grader 10 experiences vertical bounce
for a significantly shorter time period with the anti-bounce
control system engaged. It should be noted that although the gas
pedal displacement is greater in the example depicted in FIG. 9 as
compared to FIG. 7, the rate of the reduction is less in FIG. 9 so
that the operator may perceive a smaller decrease in engine and
motor grader speed.
[0052] Although the anti-bounce control system is described above
relative to controlling bounce conditions to minimize damage to a
ground surface, in some situations, it may be desirable to utilize
the system when the moldboard 20 is not engaging the ground. For
example, a bounce condition may occur when the motor grader 10 is
traveling at relatively high speeds and the moldboard is above the
ground surface. In such case, the anti-bounce control system may be
used to reduce the bounce condition and thus increase the comfort
of the operator without affecting the ground surface.
INDUSTRIAL APPLICABILITY
[0053] The industrial applicability of the system described herein
will be readily appreciated from the foregoing discussion. The
foregoing discussion is applicable to machines such as motor
graders 10 for which harmonic vibrations or bounce may affect their
operation. Individual characteristics of the machine as well as the
operating conditions and environment affect the natural frequency
of each machine. The anti-bounce control system disclosed herein
determines the natural frequency of the motor grader 10 by
analyzing movement of the motor grader, determining the maximum
amplitude of movement and the frequency at which such movement
occurs. The controller 41 may then reduce or eliminate the bounce
by changing the speed of the motor grader 10 based upon various
factors such as the amplitude of the bounce and the natural
frequency of the motor grader as well as the operating conditions
and other factors, if desired.
[0054] In one aspect, a system is described for automated control
of movement of a motor grader 10 having a prime mover and a ground
engaging blade. A first sensor is disposed on the motor grader 10
and is configured to provide a bounce signal indicative of a
measured bounce of the motor grader. A speed sensor is disposed on
the motor grader 10 and is configured to provide a speed signal
indicative of a ground speed of the motor grader. A controller 41
is configured to receive the bounce signal from the first sensor
and determine a maximum amplitude of the measured bounce of the
motor grader 10 based upon the bounce signal. The controller 41 is
further configured to generate a command signal to control the
ground speed of the motor grader 10 at least in part based upon the
maximum amplitude of the measured bounce and to transmit the
command signal to change the speed of the motor grader.
[0055] In another aspect, the disclosure describes a controller
implemented method of adjusting movement of a motor grader 10
having a prime mover, a ground engaging blade, a first sensor
configured to provide a bounce signal indicative of a measured
bounce of the motor grader, and a speed sensor disposed on the
motor grader configured to provide a speed signal indicative of a
ground speed of the motor grader. The method includes receiving the
bounce signal from the first sensor and determining a maximum
amplitude of the measured bounce of the motor grader 10 based upon
the bounce signal. The method further includes generating a command
signal within the controller 41 to control the ground speed of the
motor grader 10 at least in part based upon the maximum amplitude
of the measured bounce and transmitting the command signal from the
controller 41 to change the speed of the motor grader.
[0056] In still another aspect, the disclosure describes a motor
grader 10 including a prime mover, a ground engaging blade, a first
sensor is disposed on the motor grader and is configured to provide
a bounce signal indicative of a measured bounce of the motor
grader, and a speed sensor is disposed on the motor grader and is
configured to provide a speed signal indicative of a ground speed
of the motor grader. A controller 41 is configured to receive the
bounce signal from the first sensor and determine a maximum
amplitude of the measured bounce of the motor grader 10 based upon
the bounce signal. The controller is further configured to generate
a command signal to control the ground speed of the motor grader at
least in part based upon the maximum amplitude of the measured
bounce and to transmit the command signal to change the speed of
the motor grader.
[0057] It will be appreciated that the foregoing description
provides examples of the disclosed system and technique. However,
it is contemplated that other implementations of the disclosure may
differ in detail from the foregoing examples. All references to the
disclosure or examples thereof are intended to reference the
particular example being discussed at that point and are not
intended to imply any limitation as to the scope of the disclosure
more generally. All language of distinction and disparagement with
respect to certain features is intended to indicate a lack of
preference for those features, but not to exclude such from the
scope of the disclosure entirely unless otherwise indicated.
[0058] Recitation of ranges of values herein are merely intended to
serve as a shorthand method of referring individually to each
separate value falling within the range, unless otherwise indicated
herein, and each separate value is incorporated into the
specification as if it were individually recited herein. All
methods described herein can be performed in any suitable order
unless otherwise indicated herein or otherwise clearly contradicted
by context.
[0059] Accordingly, this disclosure includes all modifications and
equivalents of the subject matter recited in the claims appended
hereto as permitted by applicable law. Moreover, any combination of
the above-described elements in all possible variations thereof is
encompassed by the disclosure unless otherwise indicated herein or
otherwise clearly contradicted by context.
* * * * *