U.S. patent application number 16/916800 was filed with the patent office on 2021-11-04 for work vehicle magnetorheological fluid joystick systems providing machine state feedback.
The applicant listed for this patent is Deere & Company. Invention is credited to Mark E. Breutzman, Aaron R. Kenkel, Matthew Sbai, Jeffrey M. Stenoish, Todd F. Velde.
Application Number | 20210340724 16/916800 |
Document ID | / |
Family ID | 1000004960606 |
Filed Date | 2021-11-04 |
United States Patent
Application |
20210340724 |
Kind Code |
A1 |
Kenkel; Aaron R. ; et
al. |
November 4, 2021 |
WORK VEHICLE MAGNETORHEOLOGICAL FLUID JOYSTICK SYSTEMS PROVIDING
MACHINE STATE FEEDBACK
Abstract
Embodiments of a work vehicle magnetorheological fluid (MRF)
joystick system include a joystick device, an MRF joystick
resistance mechanism, a controller architecture, and a work vehicle
sensor configured to provide sensor data indicative of an
operational parameter pertaining to work vehicle. The MRF joystick
resistance mechanism is controllable to vary an MRF resistance
force resisting movement of a joystick included in the joystick
device relative to a base housing thereof. The controller
architecture is configured to: (i) monitor for variations in the
operational parameter utilizing the sensor data; and (ii) provide
tactile feedback through the joystick device indicative of the
operational parameter by selectively commanding the MRF joystick
resistance mechanism to adjust the MRF resistance force impeding
joystick movement based, at least in part, on variations in the
operational parameter.
Inventors: |
Kenkel; Aaron R.; (East
Dubuque, IL) ; Velde; Todd F.; (Dubuque, IA) ;
Breutzman; Mark E.; (Potosi, WI) ; Stenoish; Jeffrey
M.; (Asbury, IA) ; Sbai; Matthew; (Dubuque,
IA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Deere & Company |
Moline |
IL |
US |
|
|
Family ID: |
1000004960606 |
Appl. No.: |
16/916800 |
Filed: |
June 30, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
63019083 |
May 1, 2020 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E02F 9/2029 20130101;
E02F 9/24 20130101; G05G 5/03 20130101; G05G 1/015 20130101; G05G
2505/00 20130101; G05G 1/04 20130101; E02F 9/2004 20130101 |
International
Class: |
E02F 9/20 20060101
E02F009/20; G05G 1/04 20060101 G05G001/04; G05G 1/015 20060101
G05G001/015; G05G 5/03 20060101 G05G005/03; E02F 9/24 20060101
E02F009/24 |
Claims
1. A work vehicle magnetorheological fluid (MRF) joystick system
utilized onboard a work vehicle, the work vehicle MRF joystick
system comprising: a joystick device, comprising: a base housing; a
joystick movably mounted to the base housing; and a joystick
position sensor configured to monitor movement of the joystick
relative to the base housing; an MRF joystick resistance mechanism
controllable to vary an MRF resistance force impeding joystick
movement relative to the base housing in at least one degree of
freedom; a work vehicle sensor configured to provide sensor data
indicative of an operational parameter pertaining to work vehicle;
and a controller architecture coupled to the joystick position
sensor, to the MRF joystick resistance mechanism, and to the work
vehicle sensor, the controller architecture configured to: monitor
for variations in the operational parameter utilizing the sensor
data; and provide tactile feedback through the joystick device
indicative of the operational parameter by selectively commanding
the MRF joystick resistance mechanism to adjust the MRF resistance
force based, at least in part, on variations in the operational
parameter.
2. The work vehicle MRF joystick system of claim 1, wherein the
operational parameter comprises a hydraulic load placed on the work
vehicle; and wherein the controller architecture is configured to
command the MRF joystick resistance mechanism to increase the MRF
resistance force as the hydraulic load increases.
3. The work vehicle MRF joystick system of claim 1, wherein the
work vehicle comprises an electrohydraulic (EH) actuation system
and an implement movable utilizing the EH actuation system; wherein
the operational parameter comprises a circuit pressure of the EH
actuation system; and wherein the work vehicle sensor comprises a
pressure sensor configured to monitor the circuit pressure.
4. The work vehicle MRF joystick system of claim 1, wherein the
work vehicle comprises a load-carrying component; wherein the
operational parameter comprises a material weight borne by
load-carrying component; and wherein the controller architecture is
configured to command the MRF joystick resistance mechanism to
increase the MRF resistance force as the material weight
increases.
5. The work vehicle MRF joystick system of claim 4, wherein the
load-carrying component of the work vehicle comprises a
boom-mounted implement; and wherein the controller architecture is
configured to increase the MRF resistance force in a manner
impeding joystick movements raising the boom-mounted implement.
6. The work vehicle MRF joystick system of claim 4, wherein the
load-carrying component comprises a receptacle of the work vehicle;
and wherein the operational parameter comprises a payload weight
held by the receptacle.
7. The work vehicle MRF joystick system of claim 1, wherein the
work vehicle comprises a bucket; wherein the work vehicle sensor is
configured to monitor a current fill weight of the bucket; and
wherein the controller architecture is configured to: establish a
target tipoff weight to which the bucket is desirably filled; and
selectively vary the MRF resistance force based of a differential
between the target tipoff weight and the current fill weight of the
bucket.
8. The work vehicle MRF joystick system of claim 1, wherein the
operational parameter comprises a ground speed of the work vehicle;
and wherein the controller architecture is configured to command
the MRF joystick resistance mechanism to increase the MRF
resistance force as the ground speed of the work vehicle
increases.
9. The work vehicle MRF joystick system of claim 8, wherein the MRF
resistance force impedes joystick movement controlling at least one
of work vehicle heading and work vehicle ground speed.
10. The work vehicle MRF joystick system of claim 1, wherein the
work vehicle comprises a movable component having motion stop
point; wherein the operational parameter comprises displacement of
the movable component relative to the motion stop point; and
wherein the controller architecture is configured to command the
MRF joystick resistance mechanism to selectively increase the MRF
resistance force as the movable component approaches the motion
stop point.
11. The work vehicle MRF joystick system of claim 10, wherein the
movable component comprises a hydraulic cylinder having a stroke
limit or an articulable joint of a boom assembly.
12. The work vehicle MRF joystick system of claim 1, wherein the
work vehicle comprises an electrohydraulic (EH) actuation system
containing a pilot valve; and wherein the controller architecture
is configured to command the MRF joystick resistance mechanism to
selectively vary the MRF resistance force in a manner providing
tactile feedback indicating when the pilot valve initially
opens.
13. The work vehicle MRF joystick system of claim 1, wherein the
joystick device is utilized to control movement of the work
vehicle; wherein the operational parameter comprises a current
motion state of the work vehicle; and wherein the controller
architecture is configured to: determine when motion of the
joystick in an operator input direction at a detected rate will
result in an undesirably abrupt change in the current motion state
of the work vehicle; and when determining when motion of the
joystick in an operator input direction at a detected rate will
result in an undesirably abrupt change in the current motion state
of the work vehicle, command the MRF joystick resistance mechanism
to increase the MRF resistance force to impede continued movement
of the joystick in the operator input direction.
14. The work vehicle MRF joystick system of claim 13, wherein the
joystick device is utilized to control at least one of a ground
speed of the work vehicle and a heading of the work vehicle.
15. The work vehicle MRF joystick system of claim 13, wherein the
work vehicle comprises boom assembly attached to a chassis of the
work vehicle; and wherein the joystick device is utilized to
control movement of the boom assembly.
16. A work vehicle magnetorheological fluid (MRF) joystick system
utilized onboard a work vehicle, the work vehicle MRF joystick
system comprising: a joystick device, comprising: a base housing; a
joystick movably mounted to the base housing; and a joystick
position sensor configured to monitor movement of the joystick
relative to the base housing; an MRF joystick resistance mechanism
controllable to vary an MRF resistance force impeding joystick
movement relative to the base housing in at least one degree of
freedom; and a controller architecture coupled to the joystick
position sensor and to the MRF joystick resistance mechanism, the
controller architecture configured to: monitor a current ground
speed of the work vehicle; and selectively command the MRF joystick
resistance mechanism to adjust the MRF resistance force based, at
least in part, on the current ground speed of the work vehicle.
17. The work vehicle MRF joystick system of claim 16, wherein the
controller architecture is configured to command the MRF joystick
resistance mechanism to progressively increase the MRF resistance
force impeding joystick rotation about a first axis as the current
ground speed of the work vehicle increases.
18. The work vehicle MRF joystick system of claim 17, wherein the
joystick device is controllable is steer the work vehicle by
rotation of the joystick about the first axis.
19. A work vehicle magnetorheological fluid (MRF) joystick system
utilized onboard a work vehicle having a boom-mounted implement,
the work vehicle MRF joystick system comprising: a joystick device,
comprising: a base housing; a joystick movably mounted to the base
housing; and a joystick position sensor configured to monitor
movement of the joystick relative to the base housing; an MRF
joystick resistance mechanism controllable to vary an MRF
resistance force impeding joystick movement relative to the base
housing in at least one degree of freedom; and a controller
architecture coupled to the joystick position sensor and to the MRF
joystick resistance mechanism, the controller architecture
configured to: estimate a variable load resisting movement of the
boom-mounted implement in at least one direction; and selectively
command the MRF joystick resistance mechanism to increase the MRF
resistance force as the variable load increases.
20. The work vehicle MRF joystick system of claim 19, wherein the
variable load comprises a material weight carried by the
boom-mounted implement; and wherein the controller architecture is
configured to command the MRF joystick resistance mechanism to
increase the MRF resistance force in a manner impeding joystick
motions raising the boom-mounted implement.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority to U.S. provisional
application Ser. No. 63/019,083, filed with the United Stated
Patent and Trademark Office on May 1, 2020.
STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
FIELD OF THE DISCLOSURE
[0003] This disclosure relates to magnetorheological fluid (MRF)
joystick systems, which selectively vary joystick resistances to
provide feedback indicative of monitored operational parameters or
machine states of work vehicles.
BACKGROUND OF THE DISCLOSURE
[0004] Joystick devices are commonly utilized to control various
operational aspects of work vehicles employed within the
construction, agriculture, forestry, and mining industries. For
example, in the case of a work vehicle equipped with a boom
assembly, an operator may utilize one or more joystick devices to
control boom assembly movement and, therefore, movement of a tool
or implement mounted to an outer terminal end of the boom assembly.
Common examples of work vehicles having such joystick-controlled
boom assemblies include excavators, feller bunchers, skidders,
tractors (on which modular front end loader and backhoe attachments
may be installed), tractor loaders, wheel loaders, and various
compact loaders. Similarly, in the case of dozers, motor graders,
and other work vehicles equipped with earth-moving blades, an
operator may utilize with one or more joysticks to control blade
movement and positioning. Joystick devices are also commonly
utilized to steer or otherwise control the directional movement of
the work vehicle chassis in the case of motor graders, dozers, and
certain loaders, such as skid steer loaders. Given the prevalence
of joystick devices within work vehicles, taken in combination with
the relatively challenging, dynamic environments in which work
vehicles often operate, a continued demand exists for advancements
in the design and function of work vehicle joystick systems,
particularly to the extent that such advancements can improve the
safety and efficiency of work vehicle operation.
SUMMARY OF THE DISCLOSURE
[0005] A work vehicle magnetorheological fluid (MRF) joystick
system is disclosed for usage onboard a work vehicle. In
embodiments, the work vehicle MRF joystick system includes a
joystick device, an MRF joystick resistance mechanism, a controller
architecture, and a work vehicle sensor configured to provide
sensor data indicative of an operational parameter pertaining to
the work vehicle. The joystick device includes, in turn, a base
housing, a joystick movably mounted to the base housing, and a
joystick position sensor configured to monitor movement of the
joystick relative to the base housing. The MRF joystick resistance
mechanism is controllable to vary an MRF resistance force
inhibiting or resisting movement of the joystick relative to the
base housing in at least one degree of freedom (DOF). The
controller architecture is coupled to the joystick position sensor,
to the work vehicle sensor, and to the MRF joystick resistance
mechanism. The controller architecture is configured to: (i)
monitor for variations in the operational parameter utilizing the
sensor data; and (ii) provide tactile feedback through the joystick
device indicative of the operational parameter by selectively
commanding the MRF joystick resistance mechanism to adjust the MRF
resistance force based, at least in part, on variations in the
operational parameter.
[0006] In further embodiments, the work vehicle MRF joystick system
includes a joystick device, an MRF joystick resistance mechanism,
and a controller architecture. Once again, the joystick device
includes a base housing, a joystick movably mounted to the base
housing, and a joystick position sensor configured to monitor
movement of the joystick relative to the base housing. The MRF
joystick resistance mechanism is controllable to vary an MRF
resistance force resisting movement of the joystick relative to the
base housing in at least one DOF. The controller architecture,
coupled to the joystick position sensor and to the MRF joystick
resistance mechanism, is configured to: (i) monitor a current
ground speed of the work vehicle; and (ii) selectively command the
MRF joystick resistance mechanism to adjust the MRF resistance
force based, at least in part, on the current ground speed of the
work vehicle.
[0007] In still further embodiments, the MRF joystick system is
utilized onboard a work vehicle equipped with a boom-mounted
implement. The MRF joystick system includes a joystick device, an
MRF joystick resistance mechanism, and a controller architecture.
The joystick device includes, in turn, a base housing, a joystick
movably mounted to the base housing, and a joystick position sensor
configured to monitor movement of the joystick relative to the base
housing. The MRF joystick resistance mechanism is controllable to
vary an MRF resistance force resisting movement of the joystick
relative to the base housing in at least one DOF. Coupled to the
joystick position sensor and to the MRF joystick resistance
mechanism, the controller architecture is configured to: (i)
estimate a variable load resisting movement of the boom-mounted
implement in at least one direction, and (ii) selectively command
the MRF joystick resistance mechanism to increase the MRF
resistance force as the variable load increases.
[0008] The details of one or more embodiments are set-forth in the
accompanying drawings and the description below. Other features and
advantages will become apparent from the description, the drawings,
and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] At least one example of the present disclosure will
hereinafter be described in conjunction with the following
figures:
[0010] FIG. 1 is a schematic of an example magnetorheological fluid
(MRF) joystick system onboard a work vehicle (here, an excavator)
and configured to provide machine state feedback through variations
in joystick stiffness, as illustrated in accordance with an example
embodiment of the present disclosure;
[0011] FIG. 2 is a perspective view from within the excavator cabin
shown in FIG. 1 illustrating two joystick devices, which may be
included in the example MRF joystick system and utilized by an
operator to control movement of the excavator boom assembly;
[0012] FIGS. 3 and 4 are cross-sectional schematics of the example
MRF joystick system, as partially shown and taken along
perpendicular section planes through a joystick included in a
joystick device, illustrating one possible construction of the MRF
joystick system;
[0013] FIG. 5 is a process suitably carried-out by the controller
architecture of the MRF joystick system to vary joystick stiffness
in a manner providing machine state feedback; and
[0014] FIG. 6 is a graphic illustrating, in a non-exhaustive
manner, additional example work vehicles into which embodiments of
the MRF joystick system may be beneficially integrated.
[0015] Like reference symbols in the various drawings indicate like
elements. For simplicity and clarity of illustration, descriptions
and details of well-known features and techniques may be omitted to
avoid unnecessarily obscuring the example and non-limiting
embodiments of the invention described in the subsequent Detailed
Description. It should further be understood that features or
elements appearing in the accompanying figures are not necessarily
drawn to scale unless otherwise stated.
DETAILED DESCRIPTION
[0016] Embodiments of the present disclosure are shown in the
accompanying figures of the drawings described briefly above.
Various modifications to the example embodiments may be
contemplated by one of skill in the art without departing from the
scope of the present invention, as set-forth the appended claims.
As appearing herein, the term "work vehicle" includes all parts of
a work vehicle or work machine. Thus, in implementations in which a
boom assembly terminating in an implement is attached to the
chassis of a work vehicle, the term "work vehicle" encompasses both
the chassis and the boom assembly, as well as the implement or tool
mounted to the terminal end of the boom assembly.
Overview
[0017] The following describes work vehicle joystick systems
incorporating magnetorheological fluid (MRF) devices or subsystems,
which provide tactile feedback indicative of monitored operational
parameters or "machine states" of work vehicles. During work
vehicle operation, the below-described work vehicle MRF joystick
system receives sensor data indicative of at least one monitored
parameter of a given work vehicle; and selectively vary an MRF
resistance force impeding joystick movement in at least one degree
of freedom (DOF) based, at least in part, on joystick position and
variations in the monitored parameter. In so doing, the work
vehicle MRF joystick system provides work vehicle operators with
tactile feedback indicative of the current state or magnitude of
the monitored operational parameter or machine state. As the
tactile feedback is provided through the joystick device itself,
this information is conveyed to the operator in a highly intuitive,
rapid manner and without requiring the operator to avert visual
attention from the work task at hand. Further, in at least some
embodiments, the tactile feedback provided through the
below-described joystick devices may help guide or influence
operator control inputs to promote smooth or non-abrupt work
vehicle operation, to increase uniformity between operator
expectations and work vehicle performance, and to provide similar
benefits. Overall operator satisfaction levels and work vehicle
efficiency may be improved as a result.
[0018] Embodiments of the work vehicle MRF joystick system include
a processing sub-system or "controller architecture," which is
coupled to an MRF damper or an MRF joystick resistance mechanism;
that is, a mechanism or device containing a magnetorheological
fluid and capable of modifying the rheology (viscosity) of the
fluid through variations in the strength of an electromagnetic (EM)
field to provide controlled adjustments to the resistive force
impeding joystick motion in at least one DOF. This resistive force
is referred to below as an "MRF resistance force," while the degree
to which an MRF resistance force impedes joystick motion in a
particular direction or combination of directions is referred to as
the "joystick stiffness." The MRF joystick resistance mechanism may
be commanded by the controller architecture to apply various
different resistive effects selectively impeding joystick rotation
or other joystick motion in any given direction, over any given
range of travel of the joystick, and through the application of
varying magnitudes of resistive force. For example, embodiments of
the MRF joystick system may progressively increase joystick
stiffness in proportion to changes in certain monitored parameters;
e.g., in embodiment, and as discussed in detail below, the
controller architecture may command the MRF joystick resistance
mechanism to increase the MRF resistance force (and, therefore,
joystick stiffness) as a monitored parameter, such as a material
load, a hydraulic pressure, or work vehicle ground speed, increases
in magnitude. Additionally or alternatively, embodiments of the MRF
joystick system may generate other MRF-applied effects, such as
detent or pulsating effects, briefly impeding joystick motion as a
monitored parameter surpasses predetermined thresholds. Further,
embodiments of the MRF joystick control system may be capable of
increasing joystick stiffness in a single DOF or, instead, of
independently increasing joystick stiffness in multiple DOFs. For
example, in implementations which a joystick is rotatable about two
perpendicular axes, the MRF joystick resistance mechanism may be
capable of independently vary joystick stiffnesses about the two
rotational axes of the joystick.
[0019] The work vehicle MRF joystick system provides a high level
of flexibility, both from design and customization standpoints.
Regarding design flexibility, the MRF joystick system can be
configured to vary joystick stiffness in response to a wide range
of monitored parameters pertaining to work vehicles of varying
types employed in construction, agriculture, mining, and forestry
industries. A non-exhaustive list of such monitored parameters
includes work vehicle ground speed (particularly in the case of
joystick-steered work vehicles), the proximity of movable work
vehicle components (e.g., boom assembly joints or hydraulic
cylinders) to motion stops, and various loads placed on a work
vehicle. In the latter regard, embodiments of the MRF joystick
system may monitor, and selectively vary the MRF joystick
resistance force based upon, material loads carried by the work
vehicle, such as the fill load of a bucket attached to a boom
assembly. Similarly, in embodiments, the MRF resistance force and
joystick stiffness in at least one DOF may be varied based on
hydraulic pressures included within electrohydraulic (EH) actuation
system utilized to animate movable implements, such as moveable
blades (in the case of, for example dozers and motor graders) and
implements attached to boom assemblies (in the case of, for
example, excavators, feller bunchers, tractors equipped with front
end loader (FEL) attachments, wheel loaders, backhoes, and
excavators). In still other embodiments, the MRF resistance force
and joystick stiffness may be varied as a function of other loads
placed on a work vehicle, such as the load placed on the primary
engine of a work vehicle. In such embodiments, the controller
architecture may progressively increase the MRF resistance force
inhibiting joystick movement as the monitored parameter increases,
provide tactile cues (e.g., an MRF-applied feel detent or pulsating
effect) when a monitored parameter surpasses a preset threshold,
and/or otherwise manipulate the MRF resistance force to provide
tactile feedback indicative of the monitored parameter.
[0020] In further embodiments, the work vehicle MRF joystick system
may vary the MRF resistance force to emulate legacy mechanical
control schemes in which a joystick is mechanically linked to an
actuated component of the work vehicle, such as a pilot valve
included in an EH actuation system. For example, in certain
implementations, the controller architecture may utilize sensor
data to monitor the pressure conditions or valve positions of an EH
actuation system and generate certain resistance effects (e.g., a
brief pulse of resistance or feel detent) simulating the tactile
feedback inherently provided by legacy systems in which a
mechanical connection is provided between an actuated component,
such as a pilot valve, and a joystick device. This, in turn, may
provide an operator with familiar tactile cues regarding the
operational status of the EH system (e.g., when pilot valve
lift-off or cracking occurs) in the context of an EH control scheme
as opposed to a purely mechanical joystick control scheme. Stated
differently, the controller architecture may command the MRF
joystick resistance mechanism to selectively vary the MRF
resistance force in a manner providing tactile feedback indicating
when the pilot valve initially opens during usage of the EH
actuation system.
[0021] In still other embodiments, the MRF joystick system may vary
the MRF resistance force impeding joystick motion as a function of
a current monitored machine parameter, such as a current steering
angle or ground speed, relative to an operator input command
received via a joystick device. As a more specific example,
embodiments of the MRF joystick system may progressively increase
the MRF resistance force or joystick stiffness to should an
operator attempt to rotate (or otherwise move) a joystick in a
manner that, if allowed to continue unimpeded, would result in an
abrupt change in work vehicle motion. Examples of such work vehicle
motions (any or all of which may be controlled utilizing a joystick
in embodiments) include work vehicle heading or steering angle,
work vehicle ground speed, and movement of a boom-mounted
implement. Such an approach of increasing the MRF resistance force
inhibiting joystick motion when joystick inputs would result in
abrupt work vehicle motions is referred to herein as "trajectory
shaping," as discussed more fully below. Trajectory shaping by
selective variations in joystick stiffness may encourage operator
joystick movements bringing about relatively seamless or smooth
transitions in work vehicle motions. Additionally, such an approach
allows operator intent to be confirmed, in passive sense, when an
operator exerts sufficient force on the joystick to overcome the
increased MRF resistance force to, for example, abruptly change the
steering angle or ground speed of the work vehicle.
[0022] As indicated above, embodiments of the work vehicle MRF
joystick system can also provide a relatively high degree of
customization flexibility by, for example, enabling the
below-described MRF resistance effects to be tailored to operator
preference. In this regard, an operator may be permitted to adjust
the intensity of the MRF resistance effect to preference in
embodiments; or, perhaps, to selectively activate or deactivate a
given MRF resistance effect altogether. In other instances, the MRF
joystick system may permit an operator to program the MRF
resistance effects by, for example, selecting the particular
monitored parameter or parameters upon joystick stiffness is
varied. Such personalization or customization settings may be
stored in memory and associated with a particular operator in
embodiments. Upon work vehicle startup, or at another appropriate
juncture during work vehicle operation, the MRF customization
settings may then be recalled based upon the identity of the
current operator (e.g., as determined by entry of an
operator-specific pin when first logging into the work vehicle or
as otherwise ascertained) and then applied as appropriate.
[0023] An example embodiment of a work vehicle MRF joystick system
will now be described in conjunction with FIGS. 1-5. In the
below-described example embodiment, the MRF joystick system is
principally discussed in the context of a particular type of work
vehicle, namely, an excavator. Additionally, in the following
example, the MRF joystick system includes two joystick devices,
which each have a joystick rotatable about two perpendicular axes
and which are utilized to control movement of the excavator boom
assembly and the implement or tool (e.g., bucket, grapple, or
hydraulic hammer) attached thereto. The following example
notwithstanding, the MRF joystick system may include a greater or
lesser number of joysticks in further embodiments, with each
joystick device movable in any number of DOFs and along any
suitable motion pattern or range; e.g., in alternative
implementations, a given joystick device may be rotatable about a
single axis or, perhaps, movable along a limited (e.g., H-shaped)
track or motion pattern. Moreover, the below-described MRF joystick
system can be deployed on wide range of work vehicles including
joystick-controlled functions, additional examples of which are
discussed below in connection with FIG. 6.
Example MRF Joystick System Providing Machine State Feedback
[0024] Referring initially to FIG. 1, an example work vehicle
(here, an excavator 20) equipped with a work vehicle MRF joystick
system 22 is presented. In addition to the MRF joystick system 22,
the excavator 20 includes a boom assembly 24 terminating in a tool
or implement, such a bucket 26. Various other implements can be
interchanged with the bucket 26 and attached to the terminal end of
the boom assembly 24 including, for example, other buckets,
grapples, and hydraulic hammers. The excavator 20 features a body
or chassis 28, a tracked undercarriage 30 supporting the chassis
28, and a cabin 32 located at forward portion of the chassis 28 and
enclosing an operator station. The excavator boom assembly 24
extends from the chassis 28 and contains, as principal structural
components, an inner or proximal boom 34 (hereafter, "the hoist
boom 34"), an outer or distal boom 36 (hereafter, "the dipperstick
36"), and a number of hydraulic cylinders 38, 40, 42. The hydraulic
cylinders 38, 40, 42 include, in turn, two hoist cylinders 38, a
dipperstick cylinder 40, and a bucket cylinder 42. Extension and
retraction of the hoist cylinders 38 rotates the hoist boom 34
about a first pivot joint at which the hoist boom 34 is joined to
the excavator chassis 28, here at location adjacent (to the right
of) the cabin 32. Extension and retraction of the dipperstick
cylinder 40 rotates the dipperstick 36 about a second pivot joint
at which the dipperstick 36 is joined to the hoist boom 34.
Finally, extension and retraction of the bucket cylinder 42 rotates
or "curls" the excavator bucket 26 about a third pivot joint at
which the bucket 26 is joined to the dipperstick 36.
[0025] The hydraulic cylinders 38, 40, 42 are included in an
electrohydraulic (EH) actuation system 44, which is encompassed by
a box 46 entitled "actuators for joystick-controlled functions" in
FIG. 1. Movements of the excavator boom assembly 24 are controlled
utilizing at least one joystick located within the excavator cabin
32 and included in the MRF joystick system 22. Specifically, an
operator may utilize the joystick or joysticks included in the MRF
joystick system 22 to control the extension and retraction of the
hydraulic cylinders 38, 40, 42, as well as to control the swing
action of the boom assembly 24 via rotation of the excavator
chassis 28 relative to the tracked undercarriage 30. The depicted
EH actuation system 44 also contains various other non-illustrated
hydraulic components, which may include flow lines (e.g., flexible
hoses), check or relief valves, pumps, a, fittings, filters, and
the like. Additionally, the EH actuation system 44 contains
electronic valve actuators and flow control valves, such as
spool-type multi-way valves, which can be modulated to regulate the
flow of pressurized hydraulic fluid to and from the hydraulic
cylinders 38, 40, 42. This stated, the particular construction or
architecture of the EH actuation system 44 is largely
inconsequential to embodiments of the present disclosure, providing
that the below-described controller architecture 50 is capable of
controlling movement of the boom assembly 24 via commands
transmitted to selected ones of the actuators 46 effectuating the
joystick controlled functions of the excavator 20.
[0026] As schematically illustrated in an upper left portion of
FIG. 1, the work vehicle MRF joystick system 22 contains one or
more MRF joystick devices 52, 54. As appearing herein, the term
"MRF joystick device" refers to an operator input device including
at least one joystick or control lever, the movement of which can
be impeded by a variable resistance force or "stiffness force"
applied utilizing an MRF joystick resistance mechanism of the type
described herein. While one such MRF joystick device 52 is
schematically shown in FIG. 1 for clarity, the MRF joystick system
22 can include any practical number of joystick devices, as
indicated by symbol 58. In the case of the example excavator 20,
the MRF joystick system 22 will typically include two joystick
devices; e.g., joystick devices 52, 54 described below in
connection with FIG. 2. The manner in which two such joystick
devices 52, 54 may be utilized to control movement of the excavator
boom assembly 24 is further discussed below. First, however, a
general discussion of the joystick device 52, as schematically
illustrated in FIG. 1, is provided to establish a general framework
in which embodiments of the present disclosure may be better
understood.
[0027] As schematically illustrated in FIG. 1, the MRF joystick
device 52 includes a joystick 60 mounted to a lower support
structure or base housing 62. The joystick 60 is movable relative
to the base housing 62 in at least one DOF and may be rotatable
relative to the base housing 62 about one or more axes. In the
depicted embodiment, and as indicated by arrows 64, the joystick 60
of the MRF joystick device 52 is rotatable relative to the base
housing 62 about two perpendicular axes and will be described below
as such. The MRF joystick device 52 includes one or more joystick
position sensors 66 for monitoring the current position and
movement of the joystick 60 relative to the base housing 62.
Various other components 68 may also be included in the MRF
joystick device 52 including buttons, dials, switches, or other
manual input features, which may be located on the joystick 60
itself, located on the base housing 62, or a combination thereof.
Spring elements (gas or mechanical), magnets, or fluid dampers may
be incorporated into the joystick device 52 to provide a desired
rate of return to a home position of the joystick, as well as to
fine-tune the desired feel of the joystick 60 perceived by an
operator when interacting with the MRF joystick device 52. Such
mechanisms are referred to herein as "joystick bias mechanisms" and
may be contained within in the MRF joystick device 52 when having a
self-centering design. In more complex components, various other
components (e.g., potentially including one or more artificial
force feedback (AFF) motors) can also be incorporated into the MRF
joystick device 52. In other implementations, such components may
be omitted from the MRF joystick device 52.
[0028] An MRF joystick resistance mechanism 56 is at least
partially integrated into the base housing 62 of the MRF joystick
device 52. The MRF joystick resistance mechanism 56 (and the other
MRF joystick resistance mechanisms mentioned in this document) may
also alternatively be referred to as an "MRF damper," as an "MRF
brake device," or as simply an "MRF device" or "MRF mechanism." The
MRF joystick resistance mechanism 56 can be controlled to adjust
the MRF resistance force and, therefore, joystick stiffness
resisting joystick motion relative to the base housing 62 in at
least one DOF. During operation of the MRF joystick system 22, the
controller architecture 50 may selectively command the MRF joystick
resistance mechanism 56 to increase the joystick stiffness impeding
joystick rotation about a particular axis or combination of axes.
As discussed more fully below, the controller architecture 50 may
command the MRF joystick resistance mechanism 56 to increase
joystick stiffness, when appropriate to perform any one of a number
of enhanced joystick functionalities, by increasing the strength of
an EM field in which a magnetorheological fluid contained in the
MRF joystick resistance mechanism 56 is at least partially
immersed. A generalized example of one manner in which the MRF
joystick resistance mechanism 56 may be realized is described below
in connection with FIGS. 3 and 4.
[0029] The excavator 20 is further equipped with any number of
onboard sensors 70. Such sensors 70 may include sensors contained
in an obstacle detection system, which may be integrated into the
excavator 20 in embodiments. The non-joystick input sensors 70 may
further include any number and type of boom assembly sensors 72,
such as boom assembly tracking sensors suitable for tracking the
position and movement of the excavator boom assembly 24. Such
sensors can include rotary or linear variable displacement
transducers integrated into excavator boom assembly 24 in
embodiments. For example, in one possible implementation, rotary
position sensors may be integrated into the pivot joints of the
boom assembly 24; and the angular displacement readings captured by
the rotary position sensors, taken in conjunction with known
dimensions of the boom assembly 24 (as recalled from the memory
48), may be utilized to track the posture and position of the boom
assembly 24 (including the bucket 26) in three dimensional space.
In other instances, the extension and reaction of the hydraulic
cylinders 38, 40, 42 may be measured (e.g., utilizing linear
variable displacement transducers) and utilized to calculate the
current posture and positioning of the excavator boom assembly 24.
Other sensor inputs can also be considered by the controller
architecture 50 in addition or lieu of the aforementioned sensor
readings, such as inertia-based sensor readings; e.g., as captured
by inertia sensors, such as MEMS gyroscopes, accelerometers, and
possibly magnetometers packaged as IMUs, which are affixed to the
excavator 20 at various locations. For example, IMUs can be affixed
to the excavator chassis 28 and one or more locations (different
linkages) of the excavator boom assembly 24. Vision systems capable
of tracking of the excavation implement or performing other
functions related to the operation of the excavator 20 may also be
included in the onboard board sensors 70 when useful in performing
the functions described below.
[0030] One or more load measurement sensors, such as weight- or
strain-based sensors (e.g., load cells), may further be included in
the non joystick sensor inputs 70 in at least some implementations
of the work vehicle MRF joystick system 22. In embodiments, such
load measurement sensors may be utilized to directly measure the
load carried by the bucket 26 (generally, a "load-moving implement"
or "load-carrying implement") at any given time during excavator
operation. The load measurement sensors can also measure other
parameters (e.g., one or more hydraulic pressures within the EH
actuation system 44) indicative of the load carried by the boom
assembly 24 in embodiments. In other realizations, the MRF joystick
system 22 may be integrated into a work vehicle having a bed or
tank for transporting a material, such as the bed of an articulated
dump truck. In this latter case, the load measurement sensors
included in the sensors 70 may assume the form of payload weighing
sensors capable of weighing or approximating the weight of material
carried within the bed or tank of the work vehicle at any
particular juncture in time.
[0031] In embodiments, the work vehicle sensors 70 may further
include a number of vehicle motion data sources 74. The vehicle
motion data sources 74 can include any sensors or data sources
providing information pertaining to changes in the position, speed,
heading, or orientation of the excavator 20. Again, MEMS
gyroscopes, accelerometers, and possibly magnetometers packaged
IMUs can be utilized to detect and measure such changes.
Inclinometers or similar sensors may be employed to monitor the
orientation of the excavator chassis 28 or portions of the boom
assembly 24 relative to gravity in embodiments. The vehicle motion
data sources 74 may further include Global Navigation Satellite
System (GNSS) modules, such as Global Positioning System (GPS)
modules, for monitoring excavator position and motion states. In
embodiments, the vehicle motion data sources 74 may also include
sensors from which the rotational rate of the undercarriage tracks
may be calculated, electronic compasses for monitoring heading, and
other such sensors. The vehicle motion data sources 74 can also
include various sensors for monitoring the motion and position of
the boom assembly 24 and the bucket 26, including MEMS devices
integrated into the boom assembly 24 (as previously noted),
transducers for measuring angular displacements at the pin joints
of the boom assembly, transducers for measuring the stroke of the
hydraulic cylinders 38, 40, 42, and the like.
[0032] Embodiments of the MRF joystick system 22 may further
include any number of other non-joystick components 76 in addition
to those previously described. Such additional non-joystick
components 76 may include an operator interface 78 (distinct from
the MRF joystick device 52), a display device 80 located in the
excavator cabin 32, and various other types of non-joystick sensors
82. The operator interface 78, in particular, can include any
number and type of non joystick input devices for receiving
operator input, such as buttons, switches, knobs, and similar
manual inputs external to the MRF joystick device 52. Such input
devices included in the operator interface 78 can also include
cursor-type input devices, such as a trackball or joystick, for
interacting with a graphical user interface (GUI) generated on the
display device 80. The display device 80 may be located within the
cabin 32 and may assume the form of any image-generating device on
which visual alerts and other information may be visually
presented. The display device 80 may also generate a GUI for
receiving operator input or may include other inputs (e.g., buttons
or switches) for receiving operator input, which may be pertinent
to the controller architecture 50 when performing the
below-described processes. In certain instances, the display device
80 may also have touch input capabilities.
[0033] Finally, the MRF joystick system 22 can include various
other non-joystick sensors 82, which provide the controller
architecture 50 with data inputs utilized in carrying-out the
below-described processes. For example, the non-joystick sensors 82
can include sensors for automatically determining the type of
implement currently attached to the excavator 20 (or other work
vehicle) in at least some implementations when this information is
considered by the controller architecture 50 in determining when to
increase joystick stiffness to perform certain enhanced joystick
functions described herein; e.g., such sensors 82 may determine a
particular implement type currently attached to the excavator 20 by
sensing a tag (e.g., a radio frequency identification tag) or
reading other identifying information present on the implement, by
visual analysis of a camera feed capturing the implement, or
utilizing any other technique. In other instances, an operator may
simply enter information selecting the implement type currently
attached to the boom assembly 24 by, for example, interacting with
a GUI generated on the display device 80. In still other instances,
such other non-joystick sensors 82 may include sensors or cameras
capable of determining when an operator grasps or other contacts
the joystick 60. In other embodiments, such sensors may not be
contained in the MRF joystick system 22.
[0034] As further schematically depicted in FIG. 1, the controller
architecture 50 is associated with a memory 48 and may communicate
with the various illustrated components over any number of wired
data connections, wireless data connections, or any combination
thereof; e.g., as generically illustrated, the controller
architecture 50 may receive data from various components over a
centralized vehicle or a controller area network (CAN) bus 84. The
term "controller architecture," as appearing herein, is utilized in
a non-limiting sense to generally refer to the processing subsystem
of a work vehicle MRF joystick system, such as the example MRF
joystick system 22. Accordingly, the controller architecture 50 can
encompass or may be associated with any practical number of
processors, individual controllers, computer-readable memories,
power supplies, storage devices, interface cards, and other
standardized components. In many instances, the controller
architecture 50 may include a local controller directly associated
with the joystick interface and other controllers located within
the operator station enclosed by the cabin 32, with the local
controller communicating with other controllers onboard the
excavator 20 as needed. The controller architecture 50 may also
include or cooperate with any number of firmware and software
programs or computer-readable instructions designed to carry-out
the various process tasks, calculations, and control functions
described herein. Such computer-readable instructions may be stored
within a non-volatile sector of the memory 48 associated with
(accessible to) the controller architecture 50. While generically
illustrated in FIG. 1 as a single block, the memory 48 can
encompass any number and type of storage media suitable for storing
computer-readable code or instructions, as well as other data
utilized to support the operation of the MRF joystick system 22.
The memory 48 may be integrated into the controller architecture 50
in embodiments as, for example, a system-in-package, a
system-on-a-chip, or another type of microelectronic package or
module.
[0035] Discussing the joystick configuration or layout of the
excavator 20 in greater detail, the number of joystick devices
included in the MRF joystick system 22, and the structural aspects
and function of such joysticks, will vary amongst embodiments. As
previously mentioned, although only a single joystick device 52 is
schematically shown in FIG. 1, the MRF joystick system 22 will
typically two joystick devices 52, 54 supporting excavator boom
assembly control. Further illustrating this point, FIG. 2 provides
a perspective view from within the excavator cabin 32 and depicting
two MRF joystick devices 52, 54 suitably included in embodiments of
the MRF joystick system 22. As can be seen, the MRF joystick
devices 52, 54 are positioned on opposing sides of an operator seat
86 such that an operator, using both hands, can concurrently
manipulate the left MRF joystick device 52 and the right joystick
device 54 with relative ease. Carrying forward the reference
numerals introduced above in connection with FIG. 1, each joystick
device 52, 54 includes a joystick 60 mounted to a lower support
structure or base housing 62 for rotation relative to the base
housing 62 about two perpendicular axes. The joystick devices 52,
54 also each include a flexible cover or boot 88 joined between a
lower portion of the joysticks 60 and their respective base
housings 62. Additional joystick inputs are also provided on each
joystick 60 in the form of thumb-accessible buttons and, perhaps,
as other non-illustrated manual inputs (e.g., buttons, dials, and
or switches) provided on the base housings 62. Other notable
features of the excavator 20 shown in FIG. 2 include the
previously-mentioned display device 80 and pedal/control lever
mechanisms 90, 92 for controlling the respective movement of the
right and left tracks of the tracked undercarriage 30.
[0036] Different control schemes can be utilized to translate
movement of the joysticks 60 included in the joystick devices 52,
54 to corresponding movement of the excavator boom assembly 24. In
many instances, the excavator 20 will support boom assembly control
in either (and often allow switching between) a "backhoe control"
or "SAE control" pattern and an "International Standard
Organization" or "ISO" control pattern. In the case of the backhoe
control pattern, movement of the left joystick 60 to the operator's
left (arrow 94) swings the excavator boom assembly 24 in a leftward
direction (corresponding to counter-clockwise rotation of the
chassis 28 relative to the tracked undercarriage 30), movement of
the left joystick 60 to the operator's right (arrow 96) swings the
boom assembly 24 in a rightward direction (corresponding to
clockwise rotation of the chassis 28 relative to the tracked
undercarriage 30), movement of the left joystick 60 in a forward
direction (arrow 98) lowers the hoist boom 34, and movement of the
left joystick 60 in an aft or rearward direction (arrow 100) raises
the hoist boom 34. Also, in the case of the backhoe control
pattern, movement of the right joystick 60 to the left (arrow 102)
curls the bucket 26 inwardly, movement of the right joystick 60 to
the right (arrow 104) uncurls or "opens" the bucket 26, movement of
the right joystick 60 in a forward direction (arrow 106) rotates
the dipperstick 36 outwardly, and movement of the right joystick 60
in an aft or rearward direction (arrow 108) rotates the dipperstick
36 inwardly. Comparatively, in the case of an ISO control pattern,
the joystick motions for the swing commands and the bucket curl
commands are unchanged, while the joystick mappings of the hoist
boom and dipperstick are reversed. Thus, in the ISO control
pattern, forward and aft movement of the left joystick 60 controls
the dipperstick rotation in the previously described manner, while
forward and aft movement of the right joystick 60 controls motion
(raising and lowering) of the hoist boom 34 in the manner described
above.
[0037] Turning now to FIGS. 3 and 4, an example construction of the
MRF joystick device 52 and the MRF joystick resistance mechanism 56
is represented by two simplified cross-sectional schematics. While
these drawing figures illustrate a single MRF joystick device
(i.e., the MRF joystick device 52), the following description is
equally applicable to the other MRF joystick device 54 included in
the example MRF joystick system 22. The following description is
provided by way of non-limiting example only, noting that numerous
different joystick designs incorporating or functionally
cooperating with MRF joystick resistance mechanisms are possible.
The particular composition of the magnetorheological fluid largely
is also inconsequential to embodiments of the present disclosure,
providing that meaningful variations in the rheological properties
(viscosity) of the magnetorheological fluid occur in conjunction
with controlled variations in EM field strength, as described
below. For completeness, however, is noted that one
magnetorheological fluid composition well-suited for usage in
embodiments of the present disclosure contains
magnetically-permeable (e.g., carbonyl iron) particles dispersed in
a carrier fluid, which is predominately composed of an oil or an
alcohol (e.g., glycol) by weight. Such magnetically-permeable
particles may have an average diameter (or other maximum
cross-sectional dimension if the particles possess a non-spherical
(e.g., oblong) shape) in the micron range; e.g., in one embodiment,
spherical magnetically-permeable particles are used having an
average diameter between one and ten microns. Various other
additives, such as dispersants or thinners, may also be included in
the magnetorheological fluid to fine-tune the properties
thereof.
[0038] Referring now to the example joystick construction shown in
FIGS. 3 and 4, and again carrying forward the previously-introduced
reference numerals as appropriate, the MRF joystick device 52
includes a joystick 60 having at least two distinct portions or
structural regions: an upper handle 110 (only a simplified, lower
portion of which is shown in the drawing figures) and a lower,
generally spherical base portion 112 (hereafter, the "generally
spherical base 112"). The generally spherical base 112 of the
joystick 60 is captured between two walls 114, 116 of the base
housing 62, which may extend substantially parallel to one another
to form an upper portion of the base housing 62. Vertically-aligned
central openings are provided through the housing walls 114, 116,
with the respective diameters of the central openings dimensioned
to be less than the diameter of the generally spherical base 112.
The spacing or vertical offset between the walls 114, 116 is
further selected such that the bulk of generally spherical base 112
is captured between the vertically-spaced housing walls 114, 116 to
form a ball-and-socket type joint. This permits rotation of the
joystick 60 relative to the base housing 62 about two perpendicular
axes, which correspond to the X- and Y-axes of a coordinate legend
118 appearing in FIGS. 3 and 4; while generally preventing
translational movement of the joystick 60 along the X-, Y-, and
Z-axes of the coordinate legend 118. In further embodiments,
various other mechanical arrangements can be employed to mount a
joystick to a base housing, while allowing rotation of the joystick
about two perpendicular axis, such as a gimbal arrangement. In less
complex embodiments, a pivot or pin joint may be provided to permit
rotation of the joystick 60 relative to the base housing 62 about a
single axis.
[0039] The joystick 60 of the MRF joystick device 52 further
includes a stinger or lower joystick extension 120, which projects
from the generally spherical base 112 in a direction opposite the
joystick handle 110. The lower joystick extension 120 is coupled to
a static attachment point of the base housing 62 by a single
centering or return spring 124 in the illustrated schematic; here
noting that such an arrangement is simplified for the purposes of
illustration and more complex spring return arrangements (or other
joystick biasing mechanisms, if present) will typically be employed
in actual embodiments of the MRF joystick device 52. When the
joystick 60 is displaced from the neutral or home position shown in
FIG. 3, the return spring 124 deflects as shown in FIG. 4 to urge
return of the joystick 60 to the home position (FIG. 3).
Consequently, as an example, after rotation into the position shown
in FIG. 4, the joystick 60 will return to the neutral or home
position shown in FIG. 3 under the influence of the return spring
124 should the work vehicle operator subsequently release the
joystick handle 110. In other embodiments, the MRF joystick device
52 may not be self-centering and may, instead, assume the form a
friction-hold joystick remaining at a particular position absent an
operator-applied force moving the joystick from the position.
[0040] The example MRF joystick resistance mechanism 56 includes a
first and second MRF cylinders 126, 128 shown in FIGS. 3 and 4,
respectively. The first MRF cylinder 126 (FIG. 3) is mechanically
joined between the lower joystick extension 120 and a
partially-shown, static attachment point or infrastructure feature
130 of the base housing 62. Similarly, the second MRF cylinder 128
(FIG. 4) is mechanically joined between the lower joystick
extension 120 and a static attachment point 132 of the base housing
62, with the MRF cylinder 128 rotated relative to the MRF cylinder
126 by approximately 90 degrees about the Z-axis of the coordinate
legend 118. Due to this structural configuration, the MRF cylinder
126 (FIG. 3) is controllable to selectively resist rotation of the
joystick 60 about the X-axis of coordinate legend 118, while the
MRF cylinder 128 (FIG. 4) is controllable to selectively resist
rotation of the joystick 60 about the Y-axis of coordinate legend
118. Additionally, both MRF cylinders 126, 128 can be jointly
controlled to selectively resist rotation of the joystick 60 about
any axis falling between the X- and Y-axes and extending within the
X-Y plane. In other embodiments, a different MRF cylinder
configuration may be utilized and include a greater or lesser
number of MRF cylinders; e.g., in implementations in which it is
desirable to selectively resist rotation of joystick 60 about only
the X-axis or only the Y-axis, or in implementations in which
joystick 60 is only rotatable about a single axis, a single MRF
cylinder or a pair of antagonistic cylinders may be employed.
Finally, although not shown in the simplified schematics, any
number of additional components can be included in or associated
with the MRF cylinders 126, 128 in further implementations. Such
additional components may include sensors for monitoring the stroke
of the cylinders 126, 128 if desirably known to, for example, track
joystick position in lieu of the below-described joystick sensors
182, 184.
[0041] The MRF cylinders 126, 128 each include a cylinder body 134
to which a piston 138, 140 is slidably mounted. Each cylinder body
134 contains a cylindrical cavity or bore 136 in which a head 138
of one of the pistons 138, 140 is mounted for translational
movement along the longitudinal axis or centerline of the cylinder
body 134. About its outer periphery, each piston head 138 is fitted
with one or more dynamic seals (e.g., O-rings) to sealingly
engaging the interior surfaces of the cylinder body 134, thereby
separating the bore 136 into two antagonistic variable-volume
hydraulic chambers. The pistons 138, 140 also each include an
elongated piston rod 140, which projects from the piston head 138
toward the lower joystick extension 120 of the joystick 60. The
piston rod 140 extends through an end cap 142 affixed over the open
end of the cylinder body 134 (again, engaging any number of seals)
for attachment to the lower joystick extension 120 at a joystick
attachment point 144. In the illustrated example, the joystick
attachment points 144 assume the form of pin or pivot joints;
however, in other embodiments, more complex joints (e.g., spherical
joints) may be employed to form this mechanical coupling. Opposite
the joystick attachment points 144, the opposing end of the MRF
cylinders 126, 128 are mounted to the respective static attachment
points 130, 132 via spherical joints 145. Finally, hydraulic ports
146, 148 are further provided in opposing end portions of each MRF
cylinder 126, 128 to allow the inflow and outflow of
magnetorheological fluid in conjunction with translational movement
or stroking of the pistons 138, 140 along the respective
longitudinal axes of the MRF cylinders 126, 128.
[0042] The MRF cylinders 126, 128 are fluidly interconnected with
corresponding MRF values 150, 152, respectively, via flow line
connections 178, 180. As is the case with the MRF cylinders 126,
128, the MRF valves 150, 152 are presented as identical in the
illustrated example, but may vary in further implementations.
Although referred to as "valves" by common terminology
(considering, in particular, that the MRF valves 150, 152 function
to control magnetorheological fluid flow), it will be observed that
the MRF valves 150, 152 lack valve elements and other moving
mechanical parts in the instant example. As a beneficial corollary,
the MRF valves 150, 152 provide fail safe operation in that, in the
unlikely event of MRF valve failure, magnetorheological fluid flow
is still permitted through the MRF valves 150, 152 with relatively
little resistance. Consequently, should either or both of the MRF
valves 150, 152 fail for any reason, the ability of MRF joystick
resistance mechanism 56 to apply resistance forces restricting or
impeding joystick motion may be compromised; however, the joystick
60 will remain freely rotatable about the X- and Y-axes in a manner
similar to a traditional, non-MRF joystick system, and the MRF
joystick device 52 will remain capable of controlling the excavator
boom assembly 24 as typical.
[0043] In the depicted embodiment, the MRF valves 150, 152 each
include a valve housing 154, which contains end caps 156 affixed
over opposing ends of an elongated cylinder core 158. A generally
annular or tubular flow passage 160 extends around the cylinder
core 158 and between two fluid ports 162, 164, which are provided
through the opposing end caps 156. The annular flow passage 160 is
surrounded by (extends through) a number of EM inductor coils 166
(hereafter, "EM coils 166"), which are wound around paramagnetic
holders 168 and interspersed with a number of axially- or
longitudinally-spaced ferrite rings 170. A tubular shroud 172
surrounds this assembly, while a number of leads are provided
through the shroud 172 to facilitate electrical interconnection
with the housed EM coils 166. Two such leads, and the corresponding
electrical connections to a power supply and control source 177,
are schematically represented in FIGS. 3 and 4 by lines 174, 176.
As indicated by arrows 179, the controller architecture 50 is
operably coupled to the power supply and control source 177 in a
manner enabling the controller architecture 50 to control the
source 177 to vary the current supplied to or the voltage applied
across the EM coils 166 during operation of the MRF joystick system
22. This structural arrangement thus allows the controller
architecture 50 to command or control the MRF joystick resistance
mechanism 56 to vary the strength of an EM field generated by the
EM coils 166. The annular flow passage 160 extends through the EM
coils 166 (and may be substantially co-axial therewith) such that
the magnetorheological fluid passes through the center the EM field
when as the magnetorheological fluid is conducted through the MRF
valves 150, 152.
[0044] The fluid ports 162, 164 of the MRF valves 150, 152 are
fluidly connected to the ports 146, 148 of the corresponding the
MRF cylinders 126, 128 by the above-mentioned conduits 178, 180,
respectively. The conduits 178, 180 may be, for example, lengths of
flexible tubing having sufficient slack to accommodate any movement
of the MRF cylinders 126, 128 occurring in conjunction with
rotation of the joystick 60. Consider, in this regard, the example
scenario of FIG. 4. In this example, an operator has moved the
joystick handle 110 in an operator input direction (indicated by
arrow 185) such that the joystick 60 rotates about the Y-axis of
coordinate legend 118 in a clockwise direction. In combination with
this joystick motion, the MRF cylinder 128 rotates about the
spherical joint 145 to tilt slightly upward as shown. Also, along
with this operator-controlled joystick motion, the piston 138, 140
contained in the MRF cylinder 128 retracts such that the piston
head 138 moves to the left in FIG. 4 (toward the attachment point
132). The translation movement of the piston 138, 140 forces
magnetorheological fluid flow through the MRF valve 152 to
accommodate the volumetric decrease of the chamber on the left of
the piston head 138 and the corresponding volumetric increase of
the chamber to the right of the piston head 138. Consequently, at
any point during such an operator-controlled joystick rotation, the
controller architecture 50 can vary the current supplied to or the
voltage across the EM coils 166 to vary the force resisting
magnetorheological fluid flow through the MRF valve 152 and thereby
achieve a desired MRF resistance force resisting further stroking
of the piston 138, 140.
[0045] Given the responsiveness of MRF joystick resistance
mechanism 56, the controller architecture 50 can control the MRF
joystick resistance mechanism 56 to only briefly apply such an MRF
resistance force, to increase the strength of the MRF resistance
force in a predefined manner (e.g., in a gradual or stepped manner)
with increasing piston displacement, or to provide various other
resistance effects (e.g., a tactile detent or pulsating effect), as
discussed in detail below. The controller architecture 50 can
likewise control the MRF joystick resistance mechanism 56 to
selectively provided such resistance effects as the piston 138, 140
included in the MRF valve 150 strokes in conjunction with rotation
of the joystick 60 about the X-axis of coordinate legend 118.
Moreover, the MRF joystick resistance mechanism 56 may be capable
of independently varying the EM field strength generated by the EM
coils 166 within the MRF valves 150, 152 to allow independent
control of the MRF resistance forces impeding joystick rotation
about the X- and Y-axes of coordinate legend 118.
[0046] The MRF joystick device 52 may further contain one or more
joystick position sensors 182, 184 (e.g., optical or non-optical
sensors or transformers) for monitoring the position or movement of
the joystick 60 relative to the base housing 62. In the illustrated
example, specifically, the MRF joystick device 52 includes a first
joystick position sensor 182 (FIG. 3) for monitoring rotation of
the joystick 60 about the X-axis of coordinate legend 118, and a
second joystick position sensor 184 (FIG. 4) for monitoring
rotation of the joystick 60 about the Y-axis of coordinate legend
118. The data connections between the joystick position sensors
182, 184 and the controller architecture 50 are represented by
lines 186, 188, respectively. In further implementations, the MRF
joystick device 52 can include various other non-illustrated
components, as can the MRF joystick resistance mechanism 56. Such
components can include operator inputs and corresponding electrical
connections provided on the joystick 60 or the base housing 62, AFF
motors, and pressure and/or flow rate sensors included in the flow
circuit of the MRF joystick resistance mechanism 56, as
appropriate, to best suit a particular application or usage.
[0047] As previously emphasized, the above-described embodiment of
the MRF joystick device 52 is provided by way of non-limiting
example only. In alternative implementations, the construction of
the joystick 60 can differ in various respects. So too may the MRF
joystick resistance mechanism 56 differ in further embodiments
relative to the example shown in FIGS. 3 and 4, providing that the
MRF joystick resistance mechanism 56 is controllable by the
controller architecture 50 to selectively apply a resistance force
(through changes in the rheology of a magnetorheological fluid)
impeding movement of a joystick relative to a base housing in at
least one DOF. In further realizations, EM inductor coils similar
or identical to the EM coils 166 may be directly integrated into
the MRF cylinders 126, 128 to provide the desired controllable MRF
resistance effect. In such realizations, magnetorheological fluid
flow between the variable volume chambers within a given MRF
cylinder 126, 128 may be permitted via the provision of one or more
orifices through the piston head 138, by providing an annulus or
slight annular gap around the piston head 138 and the interior
surfaces of the cylinder body 134, or by providing flow passages
through the cylinder body 134 or sleeve itself. Advantageously,
such a configuration may impart the MRF joystick resistance
mechanism with a relatively compact, integrated design.
Comparatively, the usage of one or more external MRF valves, such
as the MRF valves 150, 152 (FIGS. 3 and 4), may facilitate
cost-effective manufacture and allow the usage of
commercially-available modular components in at least some
instances.
[0048] In still other implementations, the design of the MRF
joystick device may permit the magnetorheological fluid to envelop
and act directly upon a lower portion of the joystick 60 itself,
such as the spherical base 112 in the case of the joystick 60, with
EM coils positioned around the lower portion of the joystick and
surrounding the magnetological fluid body. In such embodiments, the
spherical base 112 may be provided with ribs, grooves, or similar
topological features to promote displacement of the
magnetorheological fluid in conjunction with joystick rotation,
with energization of the EM coils increasing the viscosity of the
magnetorheological fluid to impede fluid flow through restricted
flow passages provided about the spherical base 112 or, perhaps,
due to sheering of the magnetorheological fluid in conjunction with
joystick rotation. Various other designs are also possible in
further embodiments of the MRF joystick system 22.
[0049] Regardless of the particular design of the MRF joystick
resistance mechanism 56, the usage of MRF technology to selectively
generate a variable MRF resistance force or joystick stiffness
impeding (resisting or preventing) targeted joystick motions
provides several advantages. As a primary advantage, the MRF
joystick resistance mechanism 56 (and MRF joystick resistance
mechanism generally) are highly responsive and can effectuate
desired changes in EM field strength, in the rheology of the
magnetorheological fluid, and ultimately in the MRF-applied
joystick stiffness impeding joystick motions in highly abbreviated
time periods; e.g., time periods on the order of 1 millisecond in
certain instances. Correspondingly, the MRF joystick resistance
mechanism 56 may enable the MRF resistance force to be removed (or
at least greatly reduced) with an equal rapidity by quickly
reducing current flow through the EM coils and allowing the
rheology of the magnetorheological fluid (e.g., fluid viscosity) to
revert to its normal, unstimulated state. The controller
architecture 50 can further control the MRF joystick resistance
mechanism 56 to generate the MRF resistance force to have a
continuous range of strengths or intensities, within limits,
through corresponding changes in the strength of the EM field
generated utilizing the EM coils 166. Beneficially, the MRF
joystick resistance mechanism 56 can provide reliable, essentially
noiseless operation over extended time periods. Additionally, the
magnetorheological fluid can be formulated to be non-toxic in
nature, such as when the magnetorheological fluid contains carbonyl
iron-based particles dispersed in an alcohol-based or oil-based
carrier fluid, as previously described. Finally, as a still further
advantage, the above-described configuration of the MRF joystick
resistance mechanism 56 allows the MRF joystick system 22 to
selectively generate a first resistance force or joystick stiffness
deterring joystick rotation about a first axis (e.g., the X-axis of
coordinate legend 118 in FIGS. 3 and 4), while further selectively
generating a second resistance force or joystick stiffness
deterring joystick rotation about a second axis (e.g., the Y-axis
of coordinate legend 118) independently of the first resistance
force (joystick stiffness); that is, such that the first and second
resistance forces have different magnitudes, as desired.
[0050] Advancing next to FIG. 5, presented is an example process
190 suitably carried-out by the controller architecture 50 of the
above-described MRF joystick system 22 to vary one or more MRF
resistance forces selectively impeding joystick motion in a manner
providing machine state feedback pertaining to a work vehicle, such
as the example excavator 20 described above in connection with
FIGS. 1 and 2. The illustrated example process 190 (hereafter, the
"MRF machine state feedback process 190") includes a number of
process STEPS 192, 194, 196, 198, 200, 202, 204, 206, each of which
is described, in turn, below. Depending upon the particular manner
in which the MRF machine state feedback process 190 is implemented,
each step generically illustrated in FIG. 5 may entail a single
process or multiple sub-processes. Further, the steps illustrated
in FIG. 5 and described below are provided by way of non-limiting
example only. In alternative embodiments of the MRF machine state
feedback process 190, additional process steps may be performed,
certain steps may be omitted, and/or the illustrated process steps
may be performed in alternative sequences.
[0051] The MRF machine state feedback process 190 commences at STEP
192 in response to the occurrence of a predetermined trigger event.
In embodiments, the trigger event can be startup of a work vehicle
(e.g., the excavator 20 shown in FIGS. 1 and 2) or, instead, entry
of operator input requesting activation of a particular joystick
feedback mode. For example, in embodiments, an operator may
interact with a GUI generated on the display device 80 to active a
desired feedback mode as a user-selectable option, possibly
selected from a list of user-selectable options. In such
embodiments, such a GUI may also permit the operator to adjust the
intensity or other aspects of the MRF resistance force to
preference, to select the monitored parameter correlated to
variations in joystick stiffness, and/or to selectively deactivate
such MRF-applied variations in joystick stiffness, as previously
discussed. In further implementations of the process 190, the MRF
machine state feedback process 190 may commence in response to a
different trigger event, such as detection of a pertinent mode of
operation on behalf of the work vehicle; e.g., in embodiments in
which the MRF resistance force is varied in response to changes in
work vehicle ground speed or to achieve trajectory shaping, as
further discussed below, the MRF machine state feedback process 190
may commence when the work vehicle is piloted utilizing one or more
MRF joystick devices or, perhaps, when the ground speed of the work
vehicle surpasses a predetermined threshold. Similarly, in
embodiments in which the MRF resistance force is varied in response
to changes in a monitored load, the process 190 may commence when a
monitored load of the work vehicle surpasses a preset minimum
threshold value.
[0052] Following commencement of the MRF machine state feedback
process 190, the controller architecture 50 progresses to STEP 194
and collects the pertinent data inputs subsequently utilized to
determine the appropriate variations in the MRF resistance force or
forces resisting joystick motion in one or more DOFs. The
particular data inputs gathered during STEP 194 will vary in
relation to the parameter or parameters correlated to the variable
joystick stiffness, as discussed more fully below in connection
with STEPS 204, 206 of the MRF machine state feedback process 190.
Generally, iterations of the process 190 may be performed at a
relatively rapid rate such that the data inputs collected during
STEP 194 may reflect real-time or near real-time data provided by
one or more sensors onboard the work vehicle, such as any of the
sensors 70 of the above-described example excavator 20. Stored data
may also be recalled from memory (e.g., the memory 48 shown in FIG.
1) by the controller architecture 50, as needed, to determine the
appropriate MRF resistance force correlated to the monitored
parameter or sensor data. For example, in embodiments,
multi-dimensional lookup tables, characteristics or formulae, or a
similar data structures may be recalled from the memory 48 and
utilized to determine the appropriate MRF resistance force
adjustments based upon the real-time data received from one or more
sensors included within the onboard sensors 70. So too may any
operator preference settings, such as desired MRF resistance force
intensity settings, be recalled from the memory 48 and considered
during STEPS 204, 206 of the process 190.
[0053] Next, at STEP 196 of the MRF machine state feedback process
190, the controller architecture 50 receives data indicative of the
current joystick movement and position of the MRF joystick device
(or devices) under consideration. In the case of the example
excavator 20, the controller architecture 50 receives data from the
joystick position sensors 182, 184 contained in the MRF joystick
devices 52, 54 regarding the movement of the respective joysticks
60 included in the devices 52, 54. Such data enables the controller
architecture 50 to rapidly increase or decrease the MRF resistance
force inhibiting joystick movement (e.g., joystick rotation about a
particular axis) in correlation to the current joystick position
and movement characteristics. This, in turn, enables the MRF
resistance force to progressively increase, to progressively
decrease, to be quickly applied, or to be quickly removed, as
needed, to generate the desired MRF resistance effects.
[0054] Progressing to STEP 202 of the MRF machine state feedback
process 190, the controller architecture 50 determines whether
joystick position or the monitored machine state correlated to
joystick stiffness has changed in a manner warranting variations in
the currently-applied MRF resistance force and, therefore, the
joystick stiffness resisting joystick motion in a particular
direction. If this is the case, the controller architecture 50
progresses to STEP 204 of the MRF machine state feedback process
190, as further described below. Otherwise, the controller
architecture 50 advances to STEP 200 and determines whether the
current iteration of the MRF machine state feedback process 190
should terminate; e.g., due to work vehicle shutdown, due to
continued inactivity of the joystick-controlled function for a
predetermined time period, or due to removal of the condition or
trigger event in response to which the process 190 initially
commenced. If determining that the MRF machine state feedback
process 190 should terminate at STEP 200, the controller
architecture 50 progresses to STEP 202 of the process 190, the MRF
machine state feedback process 190 terminates accordingly. If
instead determining that the process 190 should continue, the
controller architecture 50 returns to STEP 194 and the
above-described process steps repeat.
[0055] As previously indicated, the controller architecture 50
advances to STEP 204 when determining that joystick position or the
monitored machine state correlated to MRF joystick stiffness has
changed based upon the data inputs collected during STEPS 194, 196
of the MRF machine state feedback process 190. During STEP 204, the
controller architecture 50 determines the appropriate manner in
which to vary the MRF resistance force to achieve a desired
joystick stiffness indicative of the monitored machine state or
parameter. The controller architecture 50 then advances to STEP 206
and applies the newly-determined MRF resistance force by
transmitting appropriate commands to the MRF joystick resistance
mechanism 56 to vary the rheology (viscosity) of the MRF fluid body
(or bodies) in a manner achieving the desired resistance effect. As
discussed throughout this document, such effects are correlated to
joystick position and, thus, may be temporarily applied to generate
detent effects or pulsating effects; the MRF resistance force may
be progressively increased or otherwise varied to substantially
match increases in a monitored parameter (e.g., a ground speed, a
component position, a load, or a hydraulic pressure of the work
vehicle); or the MRF resistance force may be lessened or removed
when appropriate based upon joystick movement and the state of the
monitored parameter. After application of the determined
adjustments to the MRF resistance force inhibiting joystick motion
in at least one DOF, the controller architecture 50 then progresses
to STEP 200 and determines whether the current iteration of the MRF
machine state feedback process 190 should terminate, as previously
discussed. In this manner, the controller architecture 50 may
repeatedly perform iterations of the process 190 to actively vary
the MRF resistance force impeding or resisting joystick motion in
at least one DOF, such as joystick rotation about one or more axes,
to provide a work vehicle operator with tactile feedback indicative
of a monitored parameter pertaining to work vehicle as the operator
interacts with a MRF joystick device, such as MRF joystick device
52 discussed above in connection with FIGS. 1-4.
[0056] Discussing now STEP 204 of the MRF machine state feedback
process 190 in greater detail, several example machine state
parameters 208, 210, 212, 214, 215 are identified for which the MRF
joystick system 22 may provide tactile feedback via selectively
variations in the MRF stiffness force or forces resisting joystick
movement. The illustrated machine state parameters 208, 210, 212,
214, 215 are provided by way of non-limiting example only and are
each described, in turn, below. Initially addressing the parameter
entitled "work vehicle load" (parameter 208, FIG. 5), embodiments
of the work vehicle MRF joystick system 22 may vary the MRF force
resistance inhibiting joystick movement as a function of any
particular load, which is placed on the work vehicle and which is
monitored (directly or indirectly) utilizing one or more sensors
onboard the work vehicle. In embodiments in which a work vehicle is
equipped with a movable implement, such as a movable blade or a
boom-mounted implement, the controller architecture 50 may estimate
a load force resisting movement of the implement in at least one
direction and increase the joystick stiffness (through continuous
or stepwise increases in the MRF resistance force) as the variable
load placed on the work increases.
[0057] In embodiments, the monitored work vehicle load may be any
variable force resisting movement of a component of the work
vehicle in some manner. For example, the monitored load may be the
mass or weight of a material weight borne by load-carrying
component of the work vehicle; the term "load-carrying component"
encompassing buckets, grapples, bale spears, feller heads, lifts,
and other such tools or implements commonly attached to work
vehicles and utilized to transport materials or objects from one
location to another. Such load forces resisting movement of a
movable implement may also forces encountered during excavation
operations as, for example, hardened regions of earth or other
difficult-to-displace regions are encountered by a tool (e.g., a
trencher, a hydraulic hammer, or a bucket). In each of these
scenarios, the controller architecture 50 may estimate the load
resisting implement movement in any given direction or combination
of directions and then command the MRF joystick resistance
mechanism 56 to vary the MRF resistance force accordingly; e.g.,
such that the MRF resistance force inhibiting joystick movement
increases in conjunction with increases in the force resisting
implement movement in a given direction. Similarly, in embodiments
in which the work vehicle comprises a load-carrying receptacle,
such as a bucket, tank, or bed, the MRF joystick system may
increase the MRF resistance force with as the weight of the
material held within the load-carrying receptacle (herein, the
"fill weight") increases. Such increases the MRF resistance force
may be implemented in a stepwise fashion or, instead, in a
substantially continual fashion (over a given resistance range)
such that, for example, the MRF resistance force progressively
increases in substantial portion to increases in the monitored
load. In other implementations, different MRF-applied tactile cues
(e.g., feel detents) may be generated when a load placed on the
work vehicle surpasses or becomes equivalent to a predetermined
threshold, such as in the case of the below-described tipoff assist
function.
[0058] The above-described variations in the MRF resistance force
can be axis-specific or direction-specific in embodiments in which
the MRF joystick device is capable of rotational about
perpendicular axes, such as in the case of the joystick device 52
shown in FIGS. 1-4. Consider, for example, an example in which the
MRF resistance force or joystick stiffness is varied in proportion
to the fill load contained in the bucket of a wheel loader, such as
the wheel loader 216 discussed below in connection with FIG. 6. In
this example, the controller architecture 50 may selectively
increase the MRF resistance force in response to joystick rotations
(as detected during STEP 196 of the process 190) moving the
joystick in forward and aft directions to lower and raise the FEL
bucket, respectively, while leaving joystick rotations about the
opposing axis (moving the joystick handle to the left and right)
curling and uncurling the bucket unhindered. Similarly, in
embodiments, only joystick motions raising the FEL bucket may be
impeded by an increased MRF resistance force as the estimated
bucket load increases to impart an operator with an intuitive sense
of the relatively heavy load carried by the bucket. Axis-specific
or direction-specific variations in MRF resistance force can also
be applied based upon the work vehicle function controlled by the
work vehicle. For example, in the case of a work vehicle equipped
with a hinged boom assembly, such as the excavator 20 shown in
FIGS. 1-2, calculations may be carried-out by the controller
architecture 50 utilizing the current estimated position and
posture of the hinged boom assembly to estimate the load placed on
the boom assembly-mounted implement (e.g., the bucket 26) at a
given moment of time, based upon the boom assembly posture relative
to the direction gravity; e.g., as monitored utilizing a MEMS
gyroscope, an inclinometer, or a similar sensor onboard the work
vehicle. Consequently, in such instances, the controller
architecture 50 may generate MRF resistance forces to selectively
impede joystick movements raising the bucket 26 load against
gravity, while providing little to no MRF resistance force
impediment to joystick inputs moving the bucket in a plane
orthogonal to the direction of gravity (e.g., by swinging the boom
assembly 24) and providing little to no impediment (or perhaps
further reducing any MRF resistance force) to actions moving the
bucket downwardly in the direction of gravity.
[0059] In embodiments in which the work vehicle includes an EH
actuation system, the MRF joystick system may increase the MRF
resistance force in conjunction with variations in a circuit
pressure within the EH actuation system. For example, with respect
to the example excavator 20 discussed above in connection with
FIGS. 1 and 2, the controller architecture 50 may monitor at least
one pressure (or a pressure differential) within a flow circuit of
the EH actuation system 44 and increase an MRF resistance force
inhibiting joystick motion in at least one DOF in conjunction with
increasing circuit pressures. In this regard, the controller
architecture 50 may independently vary the MRF resistance force
impeding joystick motions controlling different hydraulic cylinders
based on, for example, the estimated pressure or load of the
cylinders utilized to control the boom assembly; e.g., the
cylinders 38, 40, 42 shown in FIG. 1 utilized to animate the
excavator boom assembly 24. For example, as the pressure supplied
to the hydraulic hoist cylinders 38 increases, so too may the
controller architecture 50 increase the MRF resistance force
inhibiting joystick motions causing further pressure increases of
the hydraulic fluid supplied to the cylinders 38; e.g., joystick
motion causing further extension of the cylinders 38 raising the
hoist boom 34 in instances in which the bucket 26 is heavily loaded
or, conversely, joystick motion causing retraction of the cylinders
38 lowering the hoist boom 34 in instances in which the end
effector (e.g., a hydraulic hammer) attached to the terminal end of
the boom assembly 24 is pressed downwardly against a surface or
material with increasingly greater force.
[0060] In further implementations, the MRF joystick system 22 may
vary the MRF resistance force impeding joystick movement in at
least one direction as a function of another type of load placed on
the work vehicle, such as a current load placed on the primary
(e.g., internal combustion) engine of a work vehicle engine.
Additionally, while the previous description principally focuses on
altering the MRF resistance force based upon variations on
monitored work vehicle loads considered in isolation or an
independent sense, further embodiments of the MRF joystick system
22 may adjust the MRF resistance force based upon changes in load
(or another monitored work vehicle parameter mentioned herein)
relative to another parameter or threshold value. For example, in
certain embodiments, the controller architecture 50 may compare a
monitored load to a predetermined threshold value (e.g., a
particular minimum load value stored in the memory 48) and
implement the above-described MRF resistance force modifications
only after a currently monitored load surpasses the threshold
value. A similar approach may be utilized to assist operators in
piloting a work vehicle to bring a load, such as the fill weight of
a bucket, to a desired value, as in the case of a tipoff assist or
control function described in the following paragraph.
[0061] Embodiments of the MRF joystick system 22 may monitor a
current fill weight of an end effector or load-carrying implement
and vary the MRF resistance force based of a differential between a
target tipoff weight and the current fill weight of the implement,
task. In this regard, certain work vehicle, such as wheel loaders,
excavators, and similar work vehicle equipped with fillable
buckets, may be provided with a tipoff control function, which
assists an operator in utilizing the work vehicle to fill a
receptacle (e.g., a bed of a dump truck) with a desired quantity of
material. In this case, the MRF joystick system may estimate the
amount of material (e.g., by weight) utilizing any of the methods
described herein (e.g., using a strain gauge, a load sensor, or any
number of pressure sensors) and then utilize this information in
determining the manner in which to apply variances in the MRF
joystick stiffness, thereby communicating to the operator that an
appropriate amount of material is within the bucket to satisfy the
established weight target of the dump truck (or other receptacle).
With respect to the example excavator 20, in particular, the
controller architecture 50 may first establish a target tipoff
weight to which the bucket 26 is desirably filled; e.g., by
recalling from memory 48 a default setting or a setting entered
into the excavator computer via operator interface 78. The
controller architecture 50 may then selectively vary the MRF
resistance force based of a differential between the target tipoff
weight and the current fill weight of the bucket 26, as previously
described. Such an MRF joystick response may be generated when
first filling the bucket 26 (e.g., by increasing joystick
stiffness, by providing a detent effect, or by providing pulsating
effect) when a target bucket load is achieved. In other instances,
the MRF joystick system may provide similar tactile cues assisting
an operator with dumping-out an appropriate amount of material to
satisfy the target bucket load if the bucket 26 is inadvertently
over-filled by the operator when piloting the work vehicle.
[0062] With continued reference to STEP 204 of the example MRF
machine state feedback process 190 (FIG. 5), the controller
architecture 50 may further vary the MRF resistance force and,
therefore, joystick stiffness based upon work vehicle ground speed
in certain instances (parameter 210). In one possible approach, the
controller architecture 50 may selectively increase the MRF
resistance force impeding joystick motion in directions utilized to
control vehicle steering at higher vehicle speeds, with such an
increase potentially performed gradually (continually) or in a
stepwise fashion with any number of discrete resistance increase
intervals. Such ground-speed depend increases in joystick stiffness
may be applicable to the example excavator 20 when operable in a
travel mode in which the heading and, perhaps, the ground speed of
the excavator 20 can be controlled utilizing the above-described
joystick devices 52, 54 (FIG. 2). Further, the MRF resistance force
may be increased about the rotational axis corresponding to
steering of the excavator 20 in embodiments; and, perhaps, also the
rotational axis corresponding to acceleration and deceleration of
the excavator 20 (in which case such progressive increases in the
MRF resistance force may be provided only in the direction of
joystick rotation causing the excavator to accelerate). Such an
approach is also usefully applied (and, perhaps, may be even more
beneficial) in the case of work vehicles capable of traveling at
higher ground speeds and/or in the case of work vehicles
exclusively propelled in response to joystick controls, such as the
example SSL 218 described below in connection with FIG. 6.
Generally, increasing MRF joystick resistance at higher vehicle
speeds may advantageously improve the precision with which an
operator may steer the work vehicle and provide a better indicator
of operator intent as an operator need overcome a greater force to
move the joystick in an intended manner (thus reducing the
likelihood of inadvertent joystick motions due to oscillations or
other effects in the presence of high vibratory forces often
occurring during work vehicle travel).
[0063] In still further implementations of the work vehicle MRF
joystick system 22, and as indicated in FIG. 5 by parameter 212,
the controller architecture 50 may selectively vary the MRF
resistance force and, therefore, the joystick stiffness for
trajectory shaping purposes. Specifically, in such embodiments, the
controller architecture 50 may vary the MRF resistance force as a
function of the curve or profile followed by the work vehicle when
transitioning from a current motion state (e.g., work vehicle
ground speed or steering angle) to an operator-commanded motion
state (e.g., a new work vehicle speed or steering angle) when
immediate transition to the operator commanded state cannot be
achieved or would be undesirable; e.g., would cause the work
vehicle to lurch forward or to abruptly stop in the case of
acceleration or deceleration, or would cause the work vehicle to
drastically change heading (and potentially become unstable) at
higher ground speeds. Accordingly, if the operator attempts to move
the joystick in a manner that would cause such an undesirably
abrupt change in a machine state (e.g., abrupt acceleration,
deceleration, or turning of the work vehicle), perhaps rapidly
moving the joystick from a neutral position to the end of its
travel in a given direction, the MRF joystick system 22 may
progressively increase the joystick stiffness as the joystick
rapidly moves from the neutral toward its end of travel (as
indicated by the joystick rate of change). This may provide a
better indicator if the operator truly intends to command such an
undesirably abrupt change in the machine's motion state (improving
the relationship between operator expectation and machine behavior)
and will better align actual machine performance with joystick
motion. This may also be described as configuring the controller
architecture 50 to (i) determine when motion of the joystick in an
operator input direction at a detected rate will result in an
undesirably abrupt change in the current motion state of the work
vehicle; and (ii) when so determining, commanding the MRF joystick
resistance mechanism to increase the MRF resistance force to impede
continued movement of the joystick in the operator input direction.
A similar approach can also be utilized to promote smooth movement
or "trajectory shaping" of a joystick-controlled boom assembly,
such as the boom assembly 24 of the example excavator 20 shown in
FIGS. 1 and 2.
[0064] In still embodiments of the work vehicle MRF joystick system
22, and as indicated by the example parameter 214 at STEP 204 of
the MRF machine state feedback process 190 (FIG. 4), the controller
architecture 50 may monitor the movement of one or more movable
components of a work vehicle relative to its range of travel; and,
then, provide tactile feedback or cues via MRF resistance force
variations as the moveable component approaches the end of its
range of travel (herein, a "motion stop point" or a "motion stop").
Such a moveable component can be, for example, an articulable joint
of a work vehicle (e.g., a pin pivot joint of a boom assembly) or a
hydraulic cylinder having a stroke limit or an articulable joint of
a boom assembly. To provide a more specific example, and referring
once again to the excavator 20 (FIGS. 1 and 2) as the movement of a
boom assembly 24 nears the end of its range of motion in a
particular DOF, or as one or more of the hydraulic cylinders 38,
40, 42 nears their respective stroke range limits, the controller
architecture 50 may vary the MRF resistance force inhibiting
joystick rotation about an axis corresponding to movement of the
component in a manner conveying to an operator (through tactile
feedback) that the component is approaching a motion stop. Such
feedback may be provided by progressively increasing the MRF
resistance force resisting joystick motion commanding movement of
the moveable component (e.g., extension or retraction of a
hydraulic cylinder) toward its end of travel. Alternatively, a
pulsating effect or a brief detent effect may be generated ahead of
the moveable component reaching its end of travel; e.g., when a set
percentage (e.g., 5%) of the stroke range of a hydraulic cylinder
or cylinder pair remains as the cylinder(s) extend or retract in
accordance with joystick commands. By providing such MRF-applied
tactile feedback through variations in joystick stiffness, operator
awareness when a particular joystick-controlled component
approaches its end of travel may be enhanced. Concurrently, a soft
stop effect is created to help cushion or reduce shock forces that
may otherwise be generated when the work vehicle part or assembly
reaches its end of travel. A similar approach may also be utilized
when approaching other limits of the work vehicle, such as when the
EH actuation system 44 approaches a stall condition in response to
operator commands entered via one or more MRF joystick devices.
[0065] In still further embodiments, the MRF joystick system 22 may
selectively vary the MRF resistance force inhibiting joystick
motion in at least one DOF in a manner mimicking legacy systems
familiar to operators, as indicated by parameter 215 listed in STEP
204 of the MRF machine state feedback process 190 (FIG. 4). In this
regards, certain operators may be accustomed to interaction with
mechanical joysticks having direct mechanical connections to the
hydraulic valves (e.g., pilot valves or spools) within an EH
actuation system 22 may be disconcerted by the lack of such a
direct "feel" connection when utilizing an EH joystick, which
converts joystick motions to electrical signals transmitted to
valve solenoids or other actuators to perform such functions.
Embodiments of the MRF joystick system 22 can advantageously retain
the versatility and other benefits of EH control schemes, while
selectively generating joystick behaviors mimicking purely
mechanical system 22s. As previously alluded to, this may be
accomplished by increasing the MRF resistance force, and thus
increase joystick stiffness, as a function of hydraulic pressures
within the EH actuation system 22. Similarly, the controller
architecture 50 may control the MRF joystick resistance mechanism
to simulate lift-off or cracking of a (e.g., pilot) valve with the
EH actuation system 22 by, for example, initially generating a
higher MRF resistance force as a joystick is first displaced in a
given direction (the operator input direction) and then rapidly
decreasing the MRF resistance force after movement of the joystick
over a short range of travel in the operator input direction.
Various other effects can likewise be generated utilizing the MRF
joystick system 22 to mimic other mechanical control
characteristics or otherwise provide operators with a more uniform
experience when transitioning from a mechanical joystick to an EH
joystick control scheme.
[0066] In the above-described manner, embodiments of the MRF
joystick system 22 may provide operators with tactile feedback
indicative of current machine states or parameters through
selective increases in the MRF resistance force impeding joystick
movement in at least one DOF. Such feedback is provided to an
operator interacting with the above-described MRF joystick devices
in a highly intuitive and rapid manner. Further benefits are
achieved through the usage of MRF technology itself as opposed to
the usage of other resistance mechanisms, such as actuated friction
or brake mechanisms, also capable of selectively impeding joystick
motion when returning to a centered position after displacement
therefrom. Such benefits may include highly abbreviated response
times; minimal frictional losses in the absence of MRF-applied
resistance forces; reliable, essentially noiseless operation; and
other benefits as further discussed below. Additionally,
embodiments of the below-described MRF joystick resistance
mechanism may be capable of generate a continuous range of
resistance forces over a resistance force range in relatively
precise manner and in accordance with commands or control signals
issued by the controller architecture 50. While the foregoing
description principally focuses on a particular type of work
vehicle (an excavator) including a particular joystick-controlled
work vehicle function (boom assembly movement), embodiments of the
MRF joystick system 22 described herein are amenable to integration
into a wide range of work vehicles, as further discussed below in
connection with FIG. 6.
Additional Examples of Work Vehicles Beneficially Equipped with MRF
Joystick Systems
[0067] Turning now to FIG. 6, additional examples of work vehicles
into which embodiments of the MRF joystick system may be
beneficially incorporated are illustrated. Specifically, and
referring initially to the upper portion of this drawing figure,
three such work vehicles are shown: a wheeled loader 216, a skid
steer loader (SSL) 218, and a motor grader 220. Addressing first
the wheeled loader 216, the wheeled loader 216 may be equipped with
an example MRF joystick device 222 located within the cabin 224 of
the wheeled loader 216. When provided, the MRF joystick device 222
may be utilized to control the movement of a FEL 226 terminating in
a bucket 228; the FEL 226, and front end loaders generally,
considered a type of "boom assembly" in the context of this
document. Comparatively, two MRF joystick devices 230 may be
located in the cabin 232 of the example SSL 218 and utilized to
control not only the movement of the FEL 234 and its bucket 236,
but further control movement of the chassis 238 of the SSL 218 in
the well-known manner. Finally, the motor grader 220 likewise
includes two MRF joystick devices 240 located within the cabin 242
of the motor grader 220. The MRF joystick devices 240 can be
utilized to control the movement of the motor grader chassis 244
(through controlling a first transmission driving the motor grader
rear wheels and perhaps a second (e.g., hydrostatic) transmission
driving the forward wheels), as well as movement of the blade 246
of the motor grader; e.g., through rotation of and angular
adjustments to the blade-circle assembly 248, as well as
adjustments to the side shift angle of the blade 246.
[0068] In each of the above-mentioned examples, the MRF joystick
devices can be controlled to provide machine state feedback through
intelligent MRF-applied variations in joystick stiffness. In this
regard, any or all of the example wheeled loader 216, the SSL 218,
and the motor grader 220 can be equipped with a work vehicle MRF
joystick system including at least one joystick device, an MRF
joystick resistance mechanism, and a controller architecture.
Finally, still further examples of work vehicles usefully equipped
with embodiments of the MRF joystick systems described herein are
illustrated in a bottom portion of FIG. 6 and include an
FEL-equipped tractor 250, a feller buncher 252, a skidder 254, a
combine 256, and a dozer 258. In each case, the MRF joystick
devices can selectively vary the MRF resistance force impeding
joystick motion in at least one DOF to provide tactile feedback
indicative of a monitored parameter pertaining to work vehicle at
issue. Again, such parameters can include work vehicle loads,
ground speeds, and proximity of movable work vehicle component to
motion stops. Variations in the MRF resistance force can also be
utilized to simulate legacy systems (e.g., to provide tactile
feedback indicative of pilot valve lift-off) and/or to discourage
(or to ensure operator intent in inducing) joystick motions
bringing about relatively abrupt changes in motion states of the
work vehicles, as previously discussed.
Enumerated Examples of the Work Vehicle MRF Joystick System
[0069] The following examples of the work vehicle MRF joystick
system are further provided and numbered for ease of reference.
[0070] 1. In embodiments, a work vehicle MRF joystick system
includes a joystick device, an MRF joystick resistance mechanism, a
controller architecture, and a work vehicle sensor configured to
provide sensor data indicative of an operational parameter
pertaining to work vehicle. The joystick device includes, in turn,
a base housing, a joystick movably mounted to the base housing, and
a joystick position sensor configured to monitor movement of the
joystick relative to the base housing. The MRF joystick resistance
mechanism is controllable to vary an MRF resistance force resisting
movement of the joystick relative to the base housing in at least
one degree of freedom. Coupled to the joystick position sensor, to
the work vehicle sensor, and to the MRF joystick resistance
mechanism, the controller architecture is configured to: (i)
monitor for variations in the operational parameter utilizing the
sensor data; and (ii) provide tactile feedback through the joystick
device indicative of the operational parameter by selectively
commanding the MRF joystick resistance mechanism to adjust the MRF
resistance force impeding joystick movement based, at least in
part, on variations in the operational parameter.
[0071] 2. The work vehicle MRF joystick system of example 1,
wherein the operational parameter is a hydraulic load placed on the
work vehicle, while the controller architecture is configured to
command the MRF joystick resistance mechanism to selectively
increase the MRF resistance force with as the hydraulic load
increases.
[0072] 3. The work vehicle MRF joystick system of example 1,
wherein the work vehicle includes an EH actuation system and an
implement movable utilizing the EH actuation system, the
operational parameter is a circuit pressure of the EH actuation
system, and the work vehicle sensor includes a pressure sensor
configured to monitor the circuit pressure.
[0073] 4. The work vehicle MRF joystick system of example 1,
wherein the work vehicle includes a load-carrying component, the
operational parameter is a material weight borne by load-carrying
component, and the controller architecture is configured to command
the MRF joystick resistance mechanism to selectively increase the
MRF resistance force with as the material weight increases.
[0074] 5. The work vehicle MRF joystick system of example 4,
wherein the load-carrying component of the work vehicle includes a
boom-mounted implement, while the controller architecture is
configured to increase the MRF resistance force in a manner
impeding joystick movements raising the boom-mounted implement.
[0075] 6. The work vehicle MRF joystick system of example 4,
wherein the load-carrying component includes a receptacle of the
work vehicle, while the operational parameter is a payload weight
held by the receptacle.
[0076] 7. The work vehicle MRF joystick system of example 1,
wherein the work vehicle includes a bucket, and the work vehicle
sensor is configured to monitor a current fill weight of the
bucket. The controller architecture is configured to: (i) establish
a target tipoff weight to which the bucket is desirably filled, and
(ii) selectively vary the MRF resistance force based of a
differential between the target tipoff weight and the current fill
weight of the bucket.
[0077] 8. The work vehicle MRF joystick system of example 1,
wherein the operational parameter is a ground speed of the work
vehicle, while the controller architecture is configured to command
the MRF joystick resistance mechanism to selectively increase the
MRF resistance force with as the ground speed of the work vehicle
increases.
[0078] 9. The work vehicle MRF joystick system of example 8,
wherein the MRF resistance force impedes joystick movement
controlling at least one of work vehicle heading and work vehicle
ground speed.
[0079] 10. The work vehicle MRF joystick system of example 1,
wherein the work vehicle includes a movable component having motion
stop point, the operational parameter is displacement of the
movable component relative to the motion stop point, and the
controller architecture is configured to command the MRF joystick
resistance mechanism to selectively increase the MRF resistance
force as the movable component approaches the motion stop
point.
[0080] 11. The work vehicle MRF joystick system of example 10,
wherein the movable component includes a hydraulic cylinder having
a stroke limit or an articulable joint of a boom assembly.
[0081] 12. The work vehicle MRF joystick system of example 1,
wherein the work vehicle includes an EH actuation system containing
a pilot valve, while the controller architecture is configured to
command the MRF joystick resistance mechanism to selectively vary
the MRF resistance force in a manner providing tactile feedback
indicating when the pilot valve initially opens.
[0082] 13. The work vehicle MRF joystick system of example 1,
wherein the joystick device is utilized to control movement of the
work vehicle, and the operational parameter is a current motion
state of the work vehicle. The controller architecture is
configured to: (i) determine when motion of the joystick in an
operator input direction at a detected rate will result in an
undesirably abrupt change in the current motion state of the work
vehicle; and (ii) when determining when motion of the joystick in
an operator input direction at a detected rate will result in an
undesirably abrupt change in the current motion state of the work
vehicle, command the MRF joystick resistance mechanism to increase
the MRF resistance force to impede continued movement of the
joystick in the operator input direction.
[0083] 14. The work vehicle MRF joystick system of example 13,
wherein the joystick device is utilized to control at least one of
a ground speed of the work vehicle and a heading of the work
vehicle.
[0084] 15. The work vehicle MRF joystick system of example 13,
wherein the work vehicle includes boom assembly attached to a
chassis of the work vehicle, while the joystick device is utilized
to control movement of the boom assembly.
CONCLUSION
[0085] The foregoing has thus provided work vehicle MRF joystick
systems configured to provide machine state feedback through
variations in MRF resistance force. Such parameters can include,
for example, various loads applied to the work vehicle, ground
speed of the work vehicle, and proximity of movable work vehicle
component to motion stops. Further, in some embodiments, the MRF
joystick system may vary an MRF resistance force impeding joystick
motion in a manner simulating legacy systems in which a mechanical
linkage is provided between a joystick and an actuated component,
such as a pilot valve. In still other implementations in which the
joystick device is utilized to control movement of the work
vehicle, such as ground speed, heading, or boom assembly movements,
the MRF joystick system may increase the MRF resistance force to
discourage (or to confirm operator intent) joystick motions
resulting in relatively abrupt changes in the current motion state
of the work vehicle. In so doing, embodiments of the MRF joystick
systems intuitively provide tactile feedback enhancing operator
awareness of key parameters or conditions of the work vehicle to
improve operator satisfaction levels, improve efficacy in utilizing
the work vehicle to perform various works tasks, and to provide
other benefits, such as minimizing component wear in instances in
which abrupt changes in work vehicle motion are reduced.
[0086] As used herein, the singular forms "a", "an," and "the" are
intended to include the plural forms as well, unless the context
clearly indicates otherwise. It will be further understood that the
terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
[0087] The description of the present disclosure has been presented
for purposes of illustration and description, but is not intended
to be exhaustive or limited to the disclosure in the form
disclosed. Many modifications and variations will be apparent to
those of ordinary skill in the art without departing from the scope
and spirit of the disclosure. Explicitly referenced embodiments
herein were chosen and described in order to best explain the
principles of the disclosure and their practical application, and
to enable others of ordinary skill in the art to understand the
disclosure and recognize many alternatives, modifications, and
variations on the described example(s). Accordingly, various
embodiments and implementations other than those explicitly
described are within the scope of the following claims.
* * * * *