CN113589877A

CN113589877A - Work vehicle magnetorheological fluid joystick system providing machine state feedback

Info

Publication number: CN113589877A
Application number: CN202110326521.6A
Authority: CN
Inventors: A·R·肯克尔; T·F·威尔德; M·E·布鲁茨曼; J·M·司藤奥伊施; M·西巴伊
Original assignee: Deere and Co
Current assignee: Deere and Co
Priority date: 2020-05-01
Filing date: 2021-03-26
Publication date: 2021-11-02
Also published as: DE102021203250A1

Abstract

The present disclosure relates to work vehicle magnetorheological fluid joystick systems that provide machine state feedback. Specifically, an embodiment of a work vehicle magnetorheological fluid (MRF) joystick system comprises: the 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 operating parameter related to the work vehicle. The MRF joystick resistance mechanism can be controlled to vary the MRF resistance that resists movement of a joystick included in a joystick device relative to a base housing of the joystick device. The controller architecture is configured to operate as follows: (i) monitoring changes in the operating parameter using the sensor data; and (ii) provide tactile feedback indicative of the operating parameter through the joystick device by selectively commanding the MRF joystick resistance mechanism to adjust the MRF resistance that resists joystick movement based at least in part on the change in the operating parameter.

Description

Work vehicle magnetorheological fluid joystick system providing machine state feedback

Cross Reference to Related Applications

This application claims priority from U.S. provisional application No. 63/019,083 filed on united states patent and trademark office on day 1, month 5, 2020.

Technical Field

The present disclosure relates to magnetorheological fluid (MRF) joystick systems that selectively vary joystick resistance to provide feedback indicative of a monitored operating parameter or machine state of a work vehicle.

Background

Joystick devices are commonly used to control various operational aspects of work vehicles employed within the construction, agricultural, forestry, and mining industries. For example, in the case of a work vehicle equipped with a boom (boom) assembly, an operator may utilize one or more joystick devices to control boom assembly movement, and thus, movement of a tool or implement (implement) mounted to an external terminal of the boom assembly. Common examples of work vehicles having such a boom assembly controlled via a joystick include: excavators (excavator), feller buncher (filler buncher), skidders (skider), tractors (on which modular front end loader (loader) and backhoe (backhoe) attachments can be mounted), tractor loaders, wheel loaders, and various compact loaders. Similarly, in the case of bulldozers (dozers), motor graders (motor graders), and other work vehicles equipped with earth-moving blades (earth-moving blades), an operator may utilize one or more joysticks to control the movement and positioning of the blade. In the case of motor graders, dozers, and certain loaders such as skid steer loaders, joystick devices are also commonly used to steer or otherwise control the directional movement of the work vehicle chassis. In view of the popularity of joystick devices within work vehicles, coupled with the relatively challenging dynamic environment in which work vehicles often operate, there is a continuing need to improve the design and functionality of work vehicle joystick systems, particularly to the extent that such advances may improve the safety and efficiency of work vehicle operations.

Disclosure of Invention

A work vehicle magnetorheological fluid (MRF) joystick system for use on a work vehicle is disclosed. In an embodiment, the work vehicle MRF joystick system comprises: the 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 operating parameter related to the work vehicle. The joystick device further includes: 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 can be controlled to vary the MRF resistance that inhibits or resists 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, the work vehicle sensor, and the MRF joystick resistance mechanism. The controller architecture is configured to: (i) monitoring changes in the operating parameter using the sensor data; and (ii) provide tactile feedback indicative of the operating parameter through the joystick device by selectively commanding the MRF joystick resistance mechanism to adjust the MRF resistance based at least in part on the change in the operating parameter.

In other embodiments, the work vehicle MRF joystick system includes: a joystick device, an MRF joystick resistance mechanism, and a controller architecture. Again, the joystick device comprises: 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 can be controlled to vary the MRF resistance that resists movement of the joystick relative to the base housing in at least one DOF. The controller architecture (coupled to the joystick position sensor and the MRF joystick resistance mechanism) is configured to operate as follows: (i) monitoring a current ground speed (ground speed) of the work vehicle; and (ii) selectively command the MRF joystick resistance mechanism to adjust the MRF resistance based at least in part on the current ground speed of the work vehicle.

In still other embodiments, the MRF joystick system is utilized on 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 further includes: 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 can be controlled to vary the MRF resistance that resists movement of the joystick relative to the base housing in at least one DOF. A controller architecture coupled to the joystick position sensor and the MRF joystick drag mechanism is configured to: (i) estimating a variable load resisting movement of a boom-mounted implement in at least one direction; and (ii) selectively issuing a command to the MRF joystick resistance mechanism to increase the MRF resistance with increasing variable load.

The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.

Drawings

At least one example of the disclosure will be described hereinafter in connection with the following figures:

FIG. 1 is a schematic illustration of an example magnetorheological fluid (MRF) joystick system on a work vehicle (here, an excavator) as illustrated in accordance with an example embodiment of the present disclosure, and configured to provide machine state feedback through changes in joystick stiffness;

FIG. 2 is a perspective view from within the excavator cab shown in FIG. 1 illustrating two joystick devices that may be included in the example MRF joystick system and used by an operator to control movement of an excavator motor arm assembly;

fig. 3 and 4 are cross-sectional schematic views of an example MRF joystick system, as partially shown and taken along a vertical section through a joystick included in the joystick device, illustrating one possible configuration of the MRF joystick system;

FIG. 5 is a process suitably performed by the controller architecture of the MRF joystick system to change the stiffness of the joystick in a manner that provides machine state feedback; and

FIG. 6 is a diagram illustrating, in a non-exhaustive manner, additional example work vehicles that may advantageously integrate embodiments of MRF joystick systems.

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 exemplary and non-limiting embodiments of the invention described in the following detailed description. It should also be understood that the features or elements shown in the figures are not necessarily drawn to scale unless otherwise indicated.

Detailed Description

Embodiments of the present disclosure are illustrated in the figures that are briefly described above. Various modifications to the example embodiments may be devised by those skilled in the art without departing from the scope of the present invention as set forth in the appended claims. As presented herein, the term "work vehicle" includes all portions of a work vehicle or work machine. Thus, in implementations where a terminating (terminating) boom-assembly 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 implements or tools mounted to the termination of the boom-assembly.

SUMMARY

Described below are work vehicle joystick systems that incorporate a magnetorheological fluid (MRF) device or subsystem that provides tactile feedback (tactfeedback) indicative of a monitored operating parameter or "machine state" of the work vehicle. During operation of the work vehicle, the work vehicle MRF joystick system described below receives sensor data indicative of at least one monitored parameter of a given work vehicle; and selectively varying the MRF resistance resisting joystick movement in at least one degree of freedom (DOF) based at least in part on changes in the joystick position and the monitored parameter. In doing so, the work vehicle MRF joystick system provides tactile feedback to the work vehicle operator indicating the current state or magnitude of the monitored operating parameter or machine state. Because the tactile feedback is provided by the joystick device itself, this information is conveyed to the operator in a highly intuitive, quick manner without the operator having to divert visual attention from the task of working at hand. Further, in at least some embodiments, the tactile feedback provided by the joystick devices described below may help guide or influence operator control inputs to promote smooth or uninterrupted work vehicle operation, increase consistency between operator expectations and work vehicle performance, and provide similar benefits. As a result, overall operator satisfaction and work vehicle efficiency may be improved.

Embodiments of a work vehicle MRF joystick system include a processing subsystem or "controller architecture" coupled to an MRF damper or MRF joystick resistance mechanism; i.e., a mechanism or device that contains a magnetorheological fluid and is capable of modifying the rheology (viscosity) of the fluid by changes in the Electromagnetic (EM) field strength to provide controlled adjustment of the resistance to joystick movement along at least one DOF. This resistance is referred to hereinafter as "MRF resistance," and the extent to which the MRF resistance opposes joystick movement in a particular direction or combination of directions is referred to as "joystick stiffness. Various different resistive effects that selectively impede joystick rotation or other joystick movement may be applied by the controller architecture to the MRF joystick resistance mechanism, in any given direction, over any given range of travel of the joystick, and by applying a variable amount of resistance. For example, embodiments of the MRF joystick system may gradually increase the joystick stiffness in proportion to changes in certain monitored parameters; for example, in an embodiment, and as discussed in detail below, the controller architecture may issue commands to the MRF joystick resistance mechanism to increase the MRF resistance (and thus the joystick stiffness) as the magnitude of a monitored parameter (such as material load, hydraulic pressure, or work vehicle ground speed) increases. Additionally or alternatively, embodiments of the MRF joystick system may generate other MRF-applied effects (MRF-applied effects), such as a detent (dwell) or pulsing (pulsing) effect that momentarily impedes joystick motion as the monitored parameter exceeds a predetermined threshold. Furthermore, embodiments of the MRF joystick control system can increase the joystick stiffness along a single DOF, or alternatively can independently increase the joystick stiffness along multiple DOFs. For example, in implementations where the joystick is rotatable about two perpendicular axes, the MRF joystick resistance mechanism can independently vary the stiffness of the joystick about the two axes of rotation of the joystick.

Work vehicle MRF joystick systems provide a high degree of flexibility from a design and customization (customization) perspective. With regard to design flexibility, MRF joystick systems may be configured to vary joystick stiffness in response to a wide range of monitored parameters relating to different types of work vehicles employed in construction, agriculture, mining, and forestry. A non-exhaustive list of such monitored parameters includes: work vehicle ground speed (particularly in the case of a joystick-operated work vehicle), proximity (proximity) of a movable work vehicle component (e.g., a boom-assembly joint or a hydraulic cylinder) to a motion stop, and various loads placed on the work vehicle. In the latter regard, embodiments of the MRF joystick system may monitor a material load carried by the work vehicle (such as a fill load of a bucket attached to a boom assembly) and selectively vary the MRF joystick resistance based on the material load. Similarly, in embodiments, the MRF resistance and joystick stiffness along at least one DOF may be varied based on hydraulic forces included in an electro-hydraulic (EH) actuation system for maneuvering a movable implement such as a movable blade (in the case of, for example, dozers and motor graders) and an implement attached to a boom assembly (in the case of, for example, excavators, feller bunchers, tractors equipped with Front End Loader (FEL) attachments, wheel loaders, backhoes (backhoes), and excavators). In still other embodiments, the MRF resistance and joystick stiffness may vary depending on other loads placed on the work vehicle, such as the load placed on the main engine of the work vehicle. In such embodiments, the controller architecture may gradually increase the MRF resistance that inhibits joystick movement as the monitored parameter increases, provide a tactile cue (e.g., via application of a tactile detent or pulsing effect of the MRF) when the monitored parameter exceeds a preset threshold, and/or otherwise manipulate the MRF resistance to provide tactile feedback indicative of the monitored parameter.

In other embodiments, the work vehicle MRF joystick system may vary the MRF resistance to mimic a conventional mechanical control scheme in which the joystick is mechanically linked to an actuated component of the work vehicle (such as a pilot valve included in the EH actuation system). For example, in certain implementations, the controller architecture may utilize sensor data to monitor pressure conditions or valve positions of the EH drive system and generate certain resistive effects (e.g., short resistance pulses or sensory stops) to simulate the tactile feedback inherently provided by conventional systems in which a mechanical connection is provided between an actuated component, such as a pilot valve, and a joystick device. In other words, the controller architecture may issue commands to the MRF joystick resistance mechanism to selectively vary the MRF resistance in a manner that provides tactile feedback indicating when the pilot valve is initially open during use of the EH actuation system.

In still other embodiments, the MRF joystick system may vary the MRF resistance resisting joystick movement according to a currently monitored machine parameter (such as a current steering angle or ground speed) corresponding to an operator input command received via the joystick device. As a more specific example, embodiments of the MRF joystick system may gradually increase the MRF resistance or joystick stiffness in the following manner to allow the operator to attempt to turn (or otherwise move) the joystick: if continued unobstructed operation is permitted, abrupt changes in work vehicle motion may result. Examples of such work vehicle motions (in embodiments, any or all of which may be controlled with a joystick) include a direction of travel or steering angle of the work vehicle, work vehicle ground speed, and boom-mounted implement movement. This method of increasing the MRF resistance to joystick movement when joystick inputs result in sudden work vehicle movement is referred to herein as "track shaping," as discussed more fully below. Trajectory shaping through selective changes in joystick stiffness may encourage operator joystick movement to achieve relatively seamless or smooth transitions in work vehicle motion. Additionally, this approach may allow for confirmation of operator intent in a passive sense when the operator applies sufficient force to the joystick to overcome the increased MRF resistance, for example, to abruptly change the steering angle or ground speed of the work vehicle.

As indicated above, embodiments of the work vehicle MRF joystick system may also provide a relatively high degree of customization flexibility, for example, by enabling the MRF resistance effects described below to be tailored to operator preferences. In this regard, in embodiments, the operator may be allowed to adjust the strength of the MRF resistance effect to a preference; a given MRF resistance effect may also be selectively fully enabled or disabled. In other cases, the MRF joystick system may allow the operator to program the MRF resistance effect, for example, by selecting one or more particular monitored parameters when changing the stiffness of the joystick. In an embodiment, such personalized or customized settings may be stored in memory and associated with a particular operator. At work vehicle start-up, or at another appropriate time during work vehicle operation, the MRF customization settings may then be recalled based on the identity of the current operator (e.g., as determined by entering an operator-specific pin code when logging into the work vehicle for the first time, or otherwise ascertained), and then applied as appropriate.

An example embodiment of a work vehicle MRF joystick system will now be described in conjunction with fig. 1-5. In the example embodiments described below, the MRF joystick system is discussed primarily in the context of a particular type of work vehicle (i.e., excavator). Additionally, in the following example, the MRF joystick system includes two joystick devices, each having a joystick rotatable about two perpendicular axes, and used to control movement of an excavator boom assembly and an implement or tool (e.g., a bucket, grapple, or hydraulic hammer) attached to the boom assembly. In further embodiments, the MRF joystick system may include a greater or lesser number of joysticks, and each joystick device may be moved in any number of DOF and along any suitable motion pattern or range, notwithstanding the following examples; for example, in alternative implementations, a given joystick device may rotate about a single axis, or may move along a defined (e.g., H-shaped) trajectory or motion pattern. Further, the MRF joystick system described below may be deployed on a 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

Referring initially to fig. 1, an example work vehicle (here, 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 that terminates (or terminates) at an implement or implement, such as a bucket 26. Various other implements may be interchanged with bucket 26 and attached to the terminal end of boom assembly 24, including other buckets, grapples (grapples), and hydraulic hammers, for example. The excavator 20 has a body or chassis 28, a tracked undercarriage 30 supporting the chassis 28, and a cab 32 located at the front of the chassis 28 and surrounding an operator's station. The excavator boom assembly 24 extends from the chassis 28 and includes, as major structural components, an inboard or proximal boom 34 (hereinafter referred to as a "boom" 34), an outboard or distal boom 36 (hereinafter referred to as a "dipper handle" 36), and a plurality of

hydraulic cylinders

38, 40, 42.

Hydraulic cylinders

38, 40, 42 in turn comprise: two lift cylinders 38, a dipper handle cylinder 40, and a dipper cylinder 42. Extension and retraction of the lift cylinder 38 rotates the lift arm 34 about a first pivot joint where the lift arm 34 is coupled to the excavator chassis 28 (here, a location adjacent (to the right of) the cab 32). Extension and retraction of the dipper handle cylinder 40 rotates the dipper handle 36 about a second pivot joint where the dipper handle 36 is coupled to the boom 34. Finally, extension and retraction of the bucket cylinder 42 rotates or "curls" the excavator bucket 26 about a third pivot joint where the bucket 26 is engaged to the dipper handle 36.

The

hydraulic cylinders

38, 40, 42 are included in an electro-hydraulic (EH) actuation system 44, which is surrounded in FIG. 1 by a frame 46 entitled "actuators for joystick-controlled functions". Movement of the excavator external components 24 is controlled with at least one joystick located within the excavator cab 32 and included in the MRF joystick system 22. Specifically, an operator may control extension and retraction of

hydraulic cylinders

38, 40, 42 using one or more joysticks included in MRF joystick system 22, and control the swing action of boom assembly 24 via rotation of excavator chassis 28 relative to tracked undercarriage 30. The depicted EH actuation system 44 also includes various other hydraulic components not illustrated, which may include flow lines (e.g., flexible hoses), check valves or relief valves, pumps, fittings, filters, and the like. Additionally, the EH actuation system 44 includes an electronic valve actuator and a flow control valve (such as a spool-type multiplex valve) that may be modulated to regulate the flow of pressurized hydraulic fluid into and out of the

hydraulic cylinders

38, 40, 42. Given that the controller architecture 50 as described below is capable of controlling movement of the boom-assembly 24 via commands sent to selected ones of the actuators 46 that implement the joystick-controlled functions of the excavator 20, the particular configuration or architecture of the EH actuation system 44 set forth herein is largely unimportant to embodiments of the present disclosure.

As schematically illustrated in the upper left portion of fig. 1, work vehicle MRF joystick system 22 includes one or more

MRF joystick devices

52, 54. As presented herein, the term "MRF joystick device" refers to an operator input device comprising at least one joystick or control stick, the movement of which may be resisted by a variable resistance or "stiffness force" applied using an MRF joystick resistance mechanism of the type described herein. While one such MRF joystick device 52 is schematically illustrated in fig. 1 for clarity, the MRF joystick system 22 may include any practical number of joystick devices, as indicated by the symbol 58. In the case of the example excavator 20, the MRF joystick system 22 will typically include two joystick devices; such as the

joystick devices

52, 54 described below in connection with fig. 2. The manner in which two

such joystick devices

52, 54 may be used to control the movement of the excavator arm assembly 24 is discussed further below. However, a general discussion of the joystick device 52 as schematically illustrated in fig. 1 is first provided to establish a general framework that may better understand embodiments of the present disclosure.

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 is rotatable relative to the base housing 62 about one or more axes. In the depicted embodiment, and as indicated by arrow 64, the lever 60 of the MRF lever device 52 is rotatable about two perpendicular axes relative to the base housing 62, and as will also be described below. 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, on the base housing 62, or a combination of the two. Spring members (gas or mechanical springs), magnets, or fluid dampers may be incorporated into the joystick device 52 to provide a desired return rate for the home position of the joystick and to fine tune the desired feel of the joystick 60 perceived by the operator when interacting with the MRF joystick device 52. Such a mechanism is referred to herein as a "joystick biasing mechanism" and may be incorporated within MRF joystick device 52 when having a self-centering design. In more complex assemblies, various other assemblies (e.g., potentially including one or more manual force feedback (AFF) motors) may also be incorporated into the MRF joystick device 52. In other implementations, such components may be omitted from the MRF joystick device 52.

The MRF joystick resistance mechanism 56 is at least partially integrated into the base housing 62 of the MRF joystick device 52. MRF joystick resistance mechanism 56 (as well as the other MRF joystick resistance mechanisms mentioned herein) may alternatively be referred to as an "MRF damper" (damper), "MRF brake (break) device," or simply as an "MRF device" or "MRF mechanism. The MRF joystick resistance mechanism 56 can be controlled to adjust the MRF resistance, and thus the joystick stiffness, to resist movement of the joystick 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 issue commands to the MRF joystick resistance mechanism 56 to increase the joystick stiffness to resist joystick rotation about a particular axis or combination of axes. As discussed more fully below, the controller architecture 50 may issue commands to the MRF joystick resistance mechanism 56 to increase the joystick stiffness, as appropriate to perform any of a number of enhanced joystick functions, by increasing the strength of the EM field in which the 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 implemented is described below in conjunction with fig. 3 and 4.

The excavator 20 is also equipped with any number of on-board sensors 70. Such sensors 70 may include sensors included in an obstacle detection system, which in embodiments may be integrated into the excavator 20. The non-joystick input sensors 70 may also include any number and any type of boom-assembly sensors 72, such as boom-assembly tracking sensors adapted to track the position and movement of the excavator boom-assembly 24. In an embodiment, such sensors may include rotary or linearly displaceable transducers integrated into excavator boom assembly 24. For example, in one possible implementation, a rotational position sensor may be integrated into the pivot joint of boom-assembly 24; and the angular displacement readings captured by the rotational position sensor, in combination with the known dimensions of boom-assembly 24 (as recalled from memory 48), may be used to track the attitude and position of boom-assembly 24 (including bucket 26) in three-dimensional space. In other cases, the extension and retraction of

hydraulic cylinders

38, 40, 42 may be measured (e.g., using linear variable displacement sensors) and used to calculate the current pose and position of the excavator arm assembly 24. In addition to or in lieu of the aforementioned sensor readings (such as inertia-based sensor readings), the controller architecture 50 may also take into account other sensor inputs; for example, sensor inputs such as those captured by inertial sensors (such as MEMS gyroscopes, accelerometers, and possibly magnetometers packaged as IMUs) are fixed to the shovel 20 at different locations. For example, the IMU may be secured to one or more locations (different links) of the excavator chassis 28 and the excavator arm assembly 24. A vision system capable of tracking the excavator implement or performing other functions related to the operation of excavator 20 may also be included in on-board sensors 70 when useful in performing the functions described below.

In at least some implementations of the work vehicle MRF joystick system 22, one or more load measuring sensors, such as weight or strain based sensors (e.g., load cells), may also be included in the non-joystick sensor input 70 in embodiments, such load measuring sensors may be used to directly measure the load carried by the bucket 26 (often referred to as a "load mover" or "load carrier") at any given time during excavator work In one case, the load measuring sensor included in sensor 70 may take the form of a payload weighing cell capable of weighing or estimating (approximately weighing) the weight of material carried within the hopper or tank of the work vehicle at any particular time.

In an embodiment, work vehicle sensors 70 may also include a plurality of vehicle motion data sources 74. The vehicle motion data sources 74 may include: any sensor or data source that provides information related to changes in the position, speed, direction of travel, or orientation of excavator 20. Again, a MEMS gyroscope, accelerometer and possibly a magnetometer packaged as an IMU may be used to detect and measure such changes. In an embodiment, an inclinometer or similar sensor may be employed to monitor the orientation of a portion of the excavator chassis 28 or boom assembly 24 with respect to gravity. The vehicle motion data source 74 may also include a Global Navigation Satellite System (GNSS) module, such as a Global Positioning System (GPS) module, that monitors the position and motion state of the excavator. In an embodiment, the vehicle motion data source 74 may also include a sensor from which the rate of rotation of the chassis rail can be calculated, an electronic compass that monitors the direction of travel, and other such sensors. Vehicle motion data source 74 may also include various sensors that monitor the motion and position of boom-assembly 24 and bucket 26, including MEMS devices (as previously mentioned) integrated into boom-assembly 24, transducers that measure the angular displacement at the pin joint of boom-assembly, transducers that measure the travel of

hydraulic cylinders

38, 40, 42, and so forth.

Embodiments of the MRF joystick system 22 may also include any number of other non-joystick assemblies 76 in addition to those previously described. Such additional non-joystick assemblies 76 may include: an operator interface 78 (as opposed to the MRF joystick device 52), a display device 80 located in the excavator cab 32, and various other types of non-joystick sensors 82. In particular, the operator interface 78 may include any number and type of non-joystick input devices for receiving operator inputs, 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 may also include a cursor-type input device, such as a trackball or joystick, for interacting with a Graphical User Interface (GUI) generated on the display device 80. Display device 80 may be disposed within cab 32 and may take 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 that receives operator inputs, or may include other inputs (e.g., buttons or switches) that receive operator inputs that may be associated with the controller architecture 50 when performing the processes described below. In some cases, the display device 80 may also have touch input capabilities.

Finally, the MRF joystick system 22 may include various other non-joystick sensors 82 that provide data inputs to the controller architecture 50 utilized in performing the processing described below. For example, in at least some embodiments, the non-joystick sensor 82 may include: sensors that automatically determine the type of implement currently attached to excavator 20 (or other work vehicle), such information about the implement type being considered by controller architecture 50 in determining when to increase joystick stiffness to perform certain enhanced joystick functions described herein; for example, such sensors 82 may determine the particular implement type currently attached to 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 signal (camera feed) of a camera implement, or using any other technique. In other cases, the operator may simply input information selecting the type of implement currently attached to boom-assembly 24, such as by interacting with a GUI generated on display 80. In still other cases, such other non-joystick sensors 82 may include sensors or cameras capable of determining when an operator is holding the joystick 60 or otherwise contacting the joystick 60. In other embodiments, such sensors may not be included in the MRF joystick system 22.

As further schematically depicted in fig. 1, a controller architecture 50 is associated with the memory 48 and may communicate with the various illustrated components over any number of wired data connections, wireless data connections, or any combination thereof; for example, as generally illustrated, the controller architecture 50 may receive data from the various components over a centralized vehicle or Controller Area Network (CAN) bus 84. As presented herein, the term "controller architecture" is utilized in a non-limiting sense to generally refer to the processing subsystems of such a work vehicle MRF joystick system, such as the exemplary MRF joystick system 22. Thus, the controller architecture 50 may encompass or may be associated with any practical number of processors, individual controllers, computer-readable memory, power supplies, storage devices, interface cards, and other standardized components. In many cases, the controller architecture 50 may include a local controller directly associated with the joystick interface, as well as other controllers disposed within an operator console enclosed by the cab 32, and the local controller communicates with other controllers on 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 perform various processing tasks, calculations, and control functions described herein. Such computer readable instructions may be stored in a non-volatile sector of memory 48 associated with (accessible to) controller architecture 50. Although illustrated generally as a single block in fig. 1, memory 48 may encompass any number and type of storage media suitable for storing computer-readable code or instructions, as well as other data for supporting the operation of MRF joystick system 22. In an embodiment, the memory 48 may be integrated into the controller architecture 50, such as, for example, a system-level package, a system-on-a-chip, or another type of microelectronic package or module.

Discussing the joystick configuration or layout of excavator 20 in more detail, the number of joystick devices included in MRF joystick system 22, as well as the structural aspects and functionality of such joysticks, will vary from one implementation to another. As previously mentioned, although only a single joystick device 52 is schematically illustrated in fig. 1, the MRF joystick system 22 will typically have two

joystick devices

52, 54 that support control of the excavator arm assembly. Further illustrating this, fig. 2 provides a perspective view from within the excavator cab 32 and depicts two

MRF joystick devices

52, 54 suitably included in an embodiment of the MRF joystick system 22. As can be seen, the

MRF joystick devices

52, 54 are disposed on opposite sides of the operator's seat 86 so that the operator can simultaneously manipulate the left MRF joystick device 52 and the right joystick device 54 with relative ease using both hands. Continuing with the reference numerals introduced above in connection with fig. 1, each

lever device

52, 54 includes a lever 60, the lever 60 being 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 (boot)88, the flexible cover or boot 88 being engaged between the 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 may also be provided on the base housing 62 as other manual inputs (e.g., buttons, dials, and/or switches) not illustrated. Other salient features of the excavator 20 shown in fig. 2 include the aforementioned display device 80 and pedal/

lever mechanisms

90, 92, which pedal/

lever mechanisms

90, 92 control the respective movement of the left and right rails of the tracked undercarriage 30.

Different control schemes may be utilized to translate movement of joystick 60 included in joystick devices 51, 54 into corresponding movement of excavator boom assembly 24. In many cases, excavator 20 will support boom assembly control in either of (and typically allow for switching between) a "backhoe control" or "SAE control" mode and an "international standards organization" or "ISO" control mode. For the case of the backhoe control mode, movement of the left joystick 60 to the left of the operator (arrow 94) causes the excavator motor arm assembly 24 to swing in a left direction (corresponding to counterclockwise rotation of the chassis 28 relative to the track undercarriage 30), movement of the left joystick 60 to the right of the operator (arrow 96) causes the excavator motor arm assembly 24 to swing in a right direction corresponding to clockwise rotation of the chassis 28 relative to the track undercarriage 30), movement of the left joystick 60 in a forward direction (arrow 98) lowers the lift arms 34, and movement of the left joystick 60 in a rearward (aft or reward) direction (arrow 100) raises the lift arms 34. And, for the case of the backhoe control mode, movement of right joystick 60 to the left (arrow 102) causes bucket 26 to roll inward, movement of right joystick 60 to the right (arrow 104) causes bucket 26 to spread (uncorl) or "open", movement of right joystick 60 in a forward direction (arrow 106) causes handle 36 to rotate outward, and movement of right joystick 60 in a rearward (aft or return) direction (arrow 108) causes handle 36 to rotate inward. In comparison, for the case of the ISO control mode, the stick motions for the swing command and the bucket roll command remain unchanged, while the stick maps of the boom and the dipper stick are reversed (reversed). Thus, in the ISO control mode, forward and rearward movement of the left operating lever 60 controls dipper stick rotation in the manner described above, while forward and rearward movement of the right operating lever 60 controls movement (raising and lowering) of the boom 34 in the manner described above.

Referring now to fig. 3 and 4, an exemplary configuration of the MRF joystick device 52 and MRF joystick resistance mechanism 56 is shown in two simplified cross-sectional schematic views. Although these figures illustrate a single MRF joystick device (i.e., MRF joystick device 52), the following description applies equally to another 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 many different joystick designs incorporating or functionally cooperating with an MRF joystick resistance mechanism are possible. Given that meaningful changes in the rheological properties (viscosity) of a magnetorheological fluid occur in conjunction with controlled changes in the EM field strength (as described below), the particular composition of the magnetorheological fluid is largely immaterial to the embodiments of the present disclosure. For the sake of completeness, however, it is noted that a magnetorheological fluid composition well suited for use in embodiments of the present disclosure includes magnetically permeable (e.g., carbonyl iron) particles dispersed in a carrier fluid consisting essentially of oil or alcohol (e.g., ethylene glycol) by weight. Such magnetically permeable particles may have an average diameter in the micrometer range (or other maximum cross-sectional dimension if the particles have a non-spherical (e.g., oblong) shape); for example, in one embodiment, spherical magnetically permeable particles having an average diameter between 1 micron and 10 microns are used. Various other additives, such as dispersants or diluents, may also be included in the magnetorheological fluid to fine-tune its properties.

Referring now to the example joystick configuration shown in fig. 3 and 4, and again as appropriate continuing with the previously introduced reference numbers, 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 this figure), and a generally spherical lower base 112 (hereinafter, referred to as "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 generally parallel to each other to form an upper portion of the base housing 62. A vertically aligned central opening is provided through the

housing walls

114, 116 and the respective diameters of the central openings are sized to be smaller than the diameter of the generally spherical base 112. The spacing or vertical offset between the

walls

114, 116 is also selected such that the generally spherical base 112 is captured entirely between the vertically spaced

housing walls

114, 116 to form a ball and socket joint. This allows the joystick 60 to rotate relative to the base housing 62 about two perpendicular axes corresponding to the X-axis and Y-axis of the coordinate legend 118 appearing in fig. 3 and 4; while generally preventing translational movement of joystick 60 along the X-axis, Y-axis, and Z-axis of coordinate legend 118. In other embodiments, various other mechanical arrangements may be employed to mount the joystick to the base housing while allowing the joystick to rotate about two perpendicular axes (such as a gimbal arrangement). In a less complex embodiment, a pivot or pin joint may be provided to allow the lever 60 to rotate about a single axis relative to the base housing 62.

The joystick 60 of the MRF joystick device 52 also includes a stab (stinger) or lower joystick extension 120 that projects from the generally spherical base 112 in a direction opposite the joystick handle 110. In the illustrated schematic, the lower lever extension 120 is coupled to the stationary attachment point of the base housing 62 by a single radial or return spring 124; note here that this arrangement is simplified for illustrative purposes, and a more complex spring return arrangement (or other lever biasing mechanism, if any) would typically be employed in a practical implementation of the MRF lever apparatus 52. When the lever 60 is displaced from the neutral position (neutral) or home position (home position) shown in fig. 3, the return spring 124 is biased to urge the lever 60 back toward the home position (fig. 3) as shown in fig. 4. Thus, by way of example, if the work vehicle operator subsequently releases the lever handle 110 after rotating to the position shown in FIG. 4, the lever 60 will return to the neutral or home position shown in FIG. 3 under the influence of the return spring 124. In other embodiments, the MRF joystick device 52 may not be self-centering, but instead may be in the form of a frictionally held joystick that is held in a particular position without the force applied by the operator to move the joystick from that position.

The example MRF joystick resistance mechanism 56 includes a first MRF cylinder 126 and a second MRF cylinder 128 as shown in fig. 3 and 4, respectively. A first MRF cylinder 126 (fig. 3) is mechanically engaged between a partially illustrated static attachment point or base structural feature 130 of the base housing 62 and the lower lever extension 120. Similarly, a second MRF cylinder 128 (FIG. 4) is mechanically engaged between the static attachment point 132 of the base housing 62 and the lower control rod extension 120, and the MRF cylinder 128 is rotated approximately 90 degrees relative to the MRF cylinder 126 about the Z-axis of the coordinate legend 118. With this structural arrangement, the MRF cylinder 126 (FIG. 3) can be controlled to selectively resist rotation of the joystick 60 about the X-axis of the coordinate legend 118, while the MRF cylinder 128 (FIG. 4) can be controlled to selectively resist rotation of the joystick 60 about the Y-axis of the coordinate legend 118. Additionally, the two MRF cylinders 126, 128 may be commonly controlled to selectively resist rotation of the joystick 60 about any axis that falls between the X and Y axes and extends within the X-Y plane. In other embodiments, different configurations of MRF cylinders may be utilized and include a greater or lesser number of MRF cylinders; for example, in implementations where it is desired to selectively resist rotation of the joystick 60 about only the X-axis or only the Y-axis, or in implementations where the joystick 60 can only rotate about a single axis, a single MRF cylinder or a pair of antagonistic (antagonistic) cylinders may be employed. Finally, although not shown in the simplified schematic, in further implementations, any number of additional groups may be included in or associated with the MRF cylinders 126, 128. Such additional components may include sensors that monitor the travel of the cylinders 126, 128 (if desired) to track, for example, the position of the joystick, in place of the

joystick sensors

182, 184 described below.

The MRF cylinders 126, 128 each include a cylinder block 134, with

pistons

138, 140 slidably mounted to the cylinder block 134. Each cylinder 134 includes a cylindrical cavity or bore 136 in which a head 138 of one of the

pistons

138, 140 is mounted for translational movement along a longitudinal axis or centerline of the cylinder 134. Around the periphery of the cavity or bore, each piston head 138 is fitted with one or more dynamic seals (e.g., O-rings) to sealingly engage the inner surface of the cylinder 134, thereby dividing the bore 136 into two opposing variable volume hydraulic chambers. The

pistons

138, 140 also each include an elongated piston rod 140, with the piston rod 140 projecting from the piston head 138 toward the lower lever extension 120 of the lever 60. Piston rod 140 extends through an end cap 142 fixed over the open end of cylinder 134 (again, engaging any number of seals) to attach to lower lever extension 120 at lever attachment point 144. In the illustrated example, the joystick attachment point 144 takes the form of a pin or pivot joint; however, in other embodiments, more complex joints (e.g., ball joints) may be employed to form such mechanical couplings. Opposite the joystick attachment point 144, the opposite ends of the MRF cylinders 126, 128 are mounted to the respective static attachment points 130, 132 via ball joints 145. Finally,

hydraulic ports

146, 148 are also provided in opposite ends of each MRF cylinder 126, 128 to allow for the inflow and outflow of magnetorheological fluid in combination with the translational movement or stroke change of the

pistons

138, 140 along the respective longitudinal axes of the MRF cylinders 126, 128.

MRF cylinders 126, 128 are fluidly interconnected with corresponding MRF valves (values) 150, 152 via

flow conduit connections

178, 180, respectively. As with the MRF cylinders 126, 128, the

MRF valves

150, 152 are shown as identical in the illustrated example, but may be varied in further implementations. Although referred to as a "valve" in general terms (particularly in view of the

MRF valves

150, 152 function to control the flow of magnetorheological fluid), it will be observed that in the present example, the

MRF valves

150, 152 lack valve components and other moving mechanical parts. As a beneficial corollary, the

MRF valves

150, 152 provide fail-safe operation, as magnetorheological fluid is still allowed to pass through the

MRF valves

150, 152 with relatively little resistance in the unlikely event of failure of the MRF valves. Thus, if either or both of the

MRF valves

150, 152 fail for any reason, the ability of the MRF joystick resistance mechanism 56 to apply a resistance that limits or resists joystick movement may be compromised; however, the joystick 60 will be free to rotate about the X and Y axes in a manner similar to conventional non-MRF joystick systems, and the MRF joystick device 52 will still be generally capable of controlling the excavator boom assembly 24.

In the depicted embodiment,

MRF valves

150, 152 each include a valve housing 154, the valve housing 154 including end caps 156 secured to opposite ends of an elongated core 158. A generally annular or tubular flow passage 160 extends around the core 158 and between two

fluid ports

162, 164 provided through the opposing end caps 156. The annular flow channel 160 is surrounded by (extending through) a plurality of EM induction coils 166 (hereinafter referred to as "EM coils 166") that are wrapped around paramagnetic (holder) 168 and interspersed with a plurality of axially or longitudinally spaced ferrite rings 170. A tubular housing 172 surrounds the assembly while a number of leads are provided through the tubular housing 172 to facilitate electrical interconnection with the housed EM coil 166. Two such leads, and corresponding electrical connections to the power and control source 177, are schematically represented in fig. 3 and 4 by

lines

174, 176. As indicated by arrow 179, the controller architecture 50 is operatively coupled to the power and control source 177 in the following manner: controller architecture 50 is enabled to control source 177 to vary the current supplied to or the voltage applied across EM coil 166 during operation of MRF joystick system 22. Accordingly, this structural arrangement may enable the controller architecture 50 to command or control the MRF joystick drag mechanism 56 to vary the strength of the EM field generated by the EM coil 166. The annular flow passage 160 extends through the EM coil 166 (and may be substantially coaxial with the EM coil) such that the magnetorheological fluid passes through the center of the EM field as the magnetorheological fluid is directed through the

MRF valves

150, 152.

The

fluid ports

162, 164 of the

MRF valves

150, 152 are fluidly connected to the

ports

146, 148 of the corresponding MRF cylinders 126, 128, respectively, by the

conduits

178, 180 mentioned above. The length of the

conduits

178, 180 may, for example, be flexible tubing sufficient to slack enough to accommodate any movement of the MRF cylinders 126, 128 that occurs in conjunction with rotation of the joystick 60. In this regard, consider the example scenario of FIG. 4. In this example, the operator has moved the joystick handle 110 in the operator input direction (indicated by arrow 185) such that the joystick 60 rotates in a clockwise direction about the Y-axis of the coordinate legend 118. In conjunction with this joystick movement, the MRF cylinder 128 rotates about the ball joint 145 as shown to tilt slightly upward. Also, in conjunction with this operator controlled joystick movement, the

pistons

138, 140 contained in the MRF cylinder 128, when retracted, cause the piston tip 138 to move to the left in fig. 4 (toward the attachment point 132). The translational movement of the

pistons

138, 140 urges the magnetorheological fluid to flow through the MRF valve 152 to accommodate a decrease in volume of the chamber to the left of the piston head 138 and a corresponding increase in volume of the chamber to the right of the piston head 138. Thus, at any time during such operator-controlled joystick rotation, the controller architecture 50 may vary the current supplied to the EM coil 166 or the voltage applied across the EM coil 166 to vary the force against the magnetorheological fluid flowing through the MRF valve 152 to achieve the desired MRF resistance against further stroke changes of the

pistons

138, 140.

Given the responsiveness of the MRF joystick resistance mechanism 56, the controller architecture 50 may control the MRF joystick resistance mechanism 56 to apply such MRF resistance only briefly, thereby increasing the strength of the MRF resistance in a predetermined manner (e.g., in a gradual or stepwise manner), while increasing the displacement of the piston, or providing various other resistance effects (e.g., tactile detent or pulsation effects), as discussed in detail below. The controller architecture 50 may also control the MRF joystick resistance mechanism 56 to selectively provide a resistive effect such as: the

pistons

138, 140 included in the MRF valve 150 perform stroke changes in conjunction with rotation of the joystick 60 about the X-axis of the coordinate legend 118. In addition, the MRF joystick resistance mechanism 56 is 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 resisting rotation of the joystick about the X and Y axes of the coordinate legend 118.

The MRF joystick device 52 may also include one or more joystick position sensors 182, 184 (e.g., optical or non-optical sensors or transformers) that monitor the position or movement of the joystick 60 relative to the base housing 62. In the example shown, in particular, the MRF joystick device 52 comprises: a first joystick position sensor 182 (FIG. 3) that monitors rotation of the joystick 60 about the X-axis of the coordinate legend 118; and a second joystick position sensor 184 (fig. 4) that monitors rotation of the joystick 60 about the Y-axis of the 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 may include various other non-illustrated components, such as may include an MRF joystick resistance mechanism 56. Such components may include operator inputs and corresponding electrical connections provided on the joystick 60 or 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 use.

As previously emphasized, the above-described embodiments of the MRF joystick device 52 are provided by way of non-limiting example only. In alternative implementations, the configuration of the joystick 60 may differ in various respects. Provided that the MRF joystick resistance mechanism 56 is controllable by the controller architecture 50 to selectively apply a resistance (through a change in rheology of the magnetorheological fluid) to impede movement of the joystick relative to the base housing along at least one DOF, in a further embodiment, the MRF joystick resistance mechanism 56 is also different relative to the examples shown in fig. 3 and 4. In further implementation aspects, EM induction coils similar or identical to EM coil 166 may be integrated directly into MRF cylinders 126, 128 to provide the desired controllable MRF resistance effect. In such a realisation, magnetorheological fluid flow between the variable volume chambers within a given MRF cylinder 126, 128 may be permitted via one or more apertures provided through the piston head 138, by providing an annulus (annulus) or slightly smaller annular gap around the piston head 138 and the inner surface of the cylinder body 134, or by providing a flow passage through the cylinder body 134 or the sleeve itself. Advantageously, such a configuration may give the MRF joystick resistance mechanism a relatively compact integrated design. In comparison, in at least some instances, the use of one or more external MRF valves, such as MRF valves 150, 152 (fig. 3 and 4), can facilitate cost-effective manufacturing and allow the use of commercially available modular components.

In still other implementations, the MRF joystick device design may allow the magnetorheological fluid to wrap around (envelop) and act directly on the lower portion of the joystick 60 itself (such as the spherical base 112 in the case of the joystick 60), with the EM coil disposed around the lower portion of the joystick and surrounding the body of magnetorheological fluid. In such embodiments, the spherical base 112 may be provided with ribs (ribs), grooves (groovees) or similar topological features to facilitate displacement of the magnetorheological fluid in conjunction with joystick rotation, wherein energizing the EM coil increases the viscosity of the magnetorheological fluid, thereby impeding fluid flow through restricted flow passages provided around the spherical base 112, or may also be due to the rotation of the magnetorheological fluid in conjunction with joystick rotation. In further embodiments of the MRF joystick system 22, various other designs are also possible.

Regardless of the particular design of the MRF joystick resistance mechanism 56, the use of MRF techniques provides a number of advantages with joystick stiffnesses that selectively produce variable MRF resistance, or impede (resist or prevent) the intended joystick movement. As a major advantage, in terms of the rheology of the magnetorheological fluid, and ultimately in terms of the joystick stiffness via the applied MRF impeding the motion of the joystick for a highly shortened period (e.g., in some cases, a period of about 1 millisecond); the MRF joystick resistance mechanism 56 (and typically the MRF joystick resistance mechanism) has a very high responsiveness and can achieve the desired change in EM field strength. Accordingly, the MRF joystick resistance mechanism 56 may enable MRF resistance to be removed (or at least greatly reduced) with equal rapidity by rapidly reducing the current flowing through the EM coil and allowing the rheology (e.g., fluid viscosity) of the magnetorheological fluid to return to its normal, non-irritating state. The controller architecture 50 may also control the MRF joystick resistance mechanism 56 to generate MRF resistance to have a continuous range of intensity or intensity (intensity) within limits by utilizing corresponding changes in the intensity of the EM field generated by the EM coil 166. Advantageously, the MRF joystick resistance mechanism 56 may provide reliable, substantially noise-free operation over extended periods of time. Additionally, the magnetorheological fluid may be formulated to be non-toxic in nature, such as when the magnetorheological fluid comprises iron carbonyl particles dispersed in an alcohol-based or oil-based carrier fluid, as previously described. Finally, as a further advantage, the above-described configuration of the MRF joystick resistance mechanism 56 may enable the MRF joystick system 22 to selectively generate a first resistance or joystick stiffness to inhibit rotation of the joystick about a first axis (e.g., the X-axis of the coordinate legend 118 in fig. 3 and 4), while also selectively generating a second resistance or joystick stiffness independent of the first resistance (joystick stiffness) to inhibit rotation of the joystick about a second axis (e.g., the Y-axis of the coordinate legend 118); that is, the first resistance and the second resistance are made to have different magnitudes as needed.

Moving next to fig. 5, an example process 190 suitably performed by the controller architecture 50 of the MRF joystick system 22 described above is presented, which example process 190 varies one or more MRF resistances to selectively resist joystick movement in a manner that provides machine state feedback regarding a work vehicle, such as the example excavator 20 described above in connection with fig. 1 and 2. The illustrated example process 190 (hereinafter referred to as the "MRF machine state feedback process 190") includes a plurality of process steps 192, 194, 196, 198, 200, 202, 204, 206, each of which is described in turn below. Each of the steps illustrated generally in fig. 5 may require a single process or multiple sub-processes, depending on the particular manner in which the MRF machine state feedback process 190 is implemented. Furthermore, 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 an alternative order.

In response to the occurrence of a predetermined triggering event, the MRF machine state feedback process 190 begins at step 192. In an embodiment, the triggering event may be a start of a work vehicle (e.g., excavator 20 shown in fig. 1 and 2) or, alternatively, an operator input requesting activation of a particular joystick feedback mode may be entered. For example, in an embodiment, the operator may interact with a GUI generated on the display device 80 to enable a desired feedback mode as a user selectable option, which may be selected from a list of user selectable options. In such embodiments, such a GUI may also allow the operator to adjust the strength or other aspects of MRF resistance to preferences, select monitored parameters related to changes in joystick stiffness, and/or selectively disable MRF applied changes in joystick stiffness, as previously discussed. In further implementations of process 190, the MRF machine state feedback process 190 may begin in response to different triggering events, such as detection of a relevant operating mode on behalf of the work vehicle; for example, in embodiments where the MRF resistance changes in response to changes in work vehicle ground speed or implementation of trajectory shaping (as discussed further below), the MRF machine state feedback process 190 may begin when the work vehicle is being driven with one or more MRF joystick devices, or may also be when the ground speed of the work vehicle exceeds a predetermined threshold. Similarly, in embodiments where the MRF resistance changes in response to changes in the monitored load, process 190 may begin when the monitored load of the work vehicle exceeds a preset minimum threshold.

After the MRF machine state feedback process 190 begins, the controller architecture 50 proceeds to step 194 and collects pertinent data inputs that are then used to determine the appropriate change in one or more MRF resistances against joystick movement in one or more DOF. The particular data input collected during step 194 will vary for one or more parameters associated with the variable joystick stiffness, as discussed more fully below in connection with

steps

204, 206 of the MRF machine state feedback process 190. In general, iterations of process 190 may be performed at a relatively fast rate such that the data input collected during step 194 may reflect real-time or near real-time data provided by one or more sensors on the work vehicle, such as any of the sensors 70 of the example excavator 20 described above. The stored data may also be recalled from memory (e.g., memory 48 shown in fig. 1) as needed by the controller architecture 50 to determine the appropriate MRF resistance associated with the monitored parameter or sensor data. For example, in an embodiment, a multi-dimensional look-up table, characteristic or formula, or similar data structure may be recalled from memory 48 and used to determine an appropriate MRF resistance adjustment based on real-time data received from one or more sensors included within on-board sensor 70. Thus, any operator preference settings (such as desired MRF resistance strength settings) may also be recalled from memory 48 and considered during

steps

204, 206 of process 190.

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(s) under consideration. In the case of the example excavator 20, the controller architecture 50 receives data relating to the movement of the respective joystick 60 included in the

MRF joystick devices

52, 54 from the

joystick position sensors

182, 184 included in the

devices

52, 54. Such data enables the controller architecture 50 to rapidly increase or decrease the MRF resistance that inhibits joystick movement (e.g., joystick rotation about a particular axis) associated with the current joystick position and movement characteristics. This in turn enables the MRF resistance to be gradually increased, gradually decreased, quickly applied, or quickly removed as needed to produce the desired anti-MRF effect.

Proceeding to step 202 of the MRF machine state feedback process 190, the controller architecture 50 determines whether the joystick position or monitored machine state related to the joystick stiffness has changed in a manner that warrants a change in the currently applied MRF resistance and thus the joystick stiffness against joystick movement in a particular direction. If this is the case, the controller architecture 50 proceeds to step 204 of the MRF machine state feedback process 190, as described further below. Otherwise, the controller architecture 50 proceeds to step 200 and determines whether the current iteration of the MRF machine state feedback process 190 should terminate; for example, due to a work vehicle shutdown, due to continued inactivity of a joystick-controlled function for a predetermined period of time, or due to removal of a condition or trigger event in response to the initial start of process 190. If it is determined that the MRF machine state feedback process 190 should terminate at step 200, the controller architecture 50 proceeds to step 202 of process 190 and the MRF machine state feedback process 190 terminates accordingly. If instead it is determined that the process 190 should continue, the controller architecture 50 returns to step 194 and repeats the process steps described above.

As indicated previously, when it is determined that the joystick position or the monitored machine state related to the MRF joystick stiffness has changed based on the data input collected during

steps

194, 196 of the MRF machine state feedback process 190, the controller architecture 50 proceeds to step 204. During step 204, the controller architecture 50 determines an appropriate manner of varying the MRF resistance to achieve the desired stick stiffness indicative of the monitored machine state or parameter. The controller architecture 50 then proceeds to step 206 and applies the most recently determined MRF resistance by sending appropriate commands to the MRF joystick resistance mechanism 56 to alter the rheology (viscosity) of the MRF fluid body (or bodies) in a manner that achieves the desired resistance effect. As discussed throughout, these effects are related to the joystick position and therefore can be temporarily applied to generate a stopping effect or a pulsing effect; the MRF resistance may be gradually increased or otherwise changed to approximately match the increase in the monitored parameter (e.g., ground speed of the work vehicle, component position, load, or hydraulic pressure); or reducing or removing MRF resistance when appropriate based on the joystick movement and the state of the monitored parameter. After applying the determined adjustment to the MRF resistance to inhibit joystick movement along at least one DOF, the controller architecture 50 then proceeds 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 change the MRF resistance that resists or resists joystick movement along at least one DOF (such as joystick rotation about one or more axes) to provide tactile feedback indicative of monitored parameters related to the work vehicle to a work vehicle operator as the operator interacts with an MRF joystick device (such as the MRF joystick device 52 discussed above in connection with fig. 1-4).

Now, discussing 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 selective variation of one or more MRF stiffness forces against joystick movement. The illustrated

machine state parameters

208, 210, 212, 214, 215 are provided by way of non-limiting example only and are all described in turn below. With initial focus on the parameter entitled "work vehicle load" (parameter 208 in fig. 5), embodiments of work vehicle MRF joystick system 22 may vary the MRF resistance that inhibits joystick movement according to any particular load placed on the work vehicle and monitored (directly or indirectly) with one or more sensors on the work vehicle. In embodiments where the work vehicle is equipped with a movable implement (such as a movable shovel or a boom-mounted implement), the controller architecture 50 may estimate a load force that resists movement of the implement in at least one direction and increase the joystick stiffness (through a continuous or step-wise increase in MRF resistance) as the variable load placed on the work vehicle increases.

In embodiments, the monitored work vehicle load may be any variable force that resists movement of a component of the work vehicle in some manner. For example, the monitored load may be the mass or weight of the weight of material borne by the load carrying components of the work vehicle; the term "load carrying assembly" encompasses buckets, grapples, balers (bale springs), feller tips, lifts, and other such tools or implements commonly attached to a work vehicle and used to transport material or objects from one location to another. Such load forces resisting movement of the movable implement may also be forces encountered during excavation work, such as, for example, an implement (e.g., a trencher, hydraulic hammer, or bucket) encountering hardened sections or difficult to displace areas. In various of these scenarios, the controller architecture 50 may estimate the load against implement movement in any given direction or combination of directions, and then issue commands to the MRF joystick resistance mechanism 56 to change the MRF resistance accordingly; for example, the MRF resistance to stick movement is made to increase in combination with an increase in force resisting implement movement in a given direction. Similarly, in embodiments where the work vehicle includes a load carrying reservoir (receptacle), such as a bucket, tank, or hopper, the MRF joystick system may increase the MRF resistance as the weight of the material held within the load carrying reservoir (referred to herein as the "fill weight") increases. This increase in MRF resistance may be achieved in a stepwise manner or, alternatively, in a substantially continuous manner (within a given resistance range), such that, for example, the MRF resistance gradually increases in substantial proportion to the increase in monitored load. In other implementations, a different tactile cue (e.g., a tactile stop) of the applied MRF may be generated when the load placed on the work vehicle exceeds or becomes equal to a predetermined threshold, such as in the case of the dump (tipoff) assist function described below.

In embodiments where the MRF joystick device is rotatable about a vertical axis (such as in the case of the joystick device 52 shown in fig. 1-4), the above-described variation in MRF resistance may be axis-specific or direction-specific. For example, consider the following example: the MRF resistance or stick stiffness varies in proportion to the fill load contained in the bucket of a wheel loader, such as wheel loader 216 discussed below in connection with fig. 6. In this example, the controller architecture 50 may selectively increase MRF resistance in response to joystick rotation (as detected during step 196 of process 190) moving the joystick in the forward and rearward directions to lower and raise the FEL bucket, respectively, while maintaining unimpeded curl and stretch of the bucket in joystick rotation about the opposite axis (joystick handle moving left and right). Similarly, in an embodiment, only the joystick movement that raises the FEL bucket may be impeded by increased MRF resistance as the estimated bucket load increases, giving the operator an intuitive feel of the relatively heavy load carried by the bucket. The axis-specific or direction-specific variation of the MRF resistance may also be applied based on work vehicle functions controlled by the work vehicle. For example, in the case of an articulated boom-equipped work vehicle, such as excavator 20 shown in fig. 1-2, calculations may be performed by controller architecture 50 using the current estimated position and attitude of the articulated boom assembly to estimate the load placed on a boom-mounted implement (e.g., bucket 26) at a given time based on the boom assembly attitude for directional gravity (e.g., as monitored using a MEMS gyroscope, inclinometer, or similar sensor on the work vehicle). Thus, in such a case, the controller architecture 50 may generate MRF resistance to selectively impede stick movement of the load lifting the bucket 26 against (against) gravity, while providing little or no MRF resistance obstruction for stick input moving the bucket in a plane orthogonal to the direction of gravity (e.g., by pivoting the arm assembly 24 back), and little or no obstruction for the action of moving the bucket downward in the direction of gravity (or any MRF resistance may be further reduced).

In embodiments where the work vehicle includes an EH actuation system, the MRF joystick system may increase MRF resistance in conjunction with changes in circuit pressure within the EH actuation system. For example, referring to the example excavator 20 discussed above in connection with fig. 1 and 2, the controller architecture 50 may monitor at least one pressure (or pressure differential) within the flow circuits of the EH actuation system 44 and increase the MRF resistance inhibiting joystick movement along at least one DOF in conjunction with the increased circuit pressure. In this regard, the controller architecture 50 may independently vary the MRF resistance resisting movement of a joystick controlling a boom assembly of an excavator, for example, based on estimated pressures or loads of various hydraulic cylinders used to control the boom assembly (e.g., the

cylinders

38, 40, 42 used to move the boom assembly 24 of the excavator shown in FIG. 1). For example, as the pressure supplied to the hydraulic lift cylinder 38 increases, the controller architecture 50 may thus also increase the MRF resistance that inhibits joystick movement, resulting in a further pressure increase of the hydraulic fluid supplied to the cylinder 38; for example, in the event that the bucket 26 is heavily loaded, the joystick movement causes the cylinder 38 that raises the lift arm 34 to extend further; or conversely, in the event that an end effector (e.g., a hydraulic hammer) attached to the terminal end of the boom assembly 24 is pressed down against a surface or material with increasing force, the joystick movement causes the cylinder 38 of the lower lift arm 34 to retract.

In further implementations, the MRF joystick system 22 may vary the MRF resistance resisting joystick movement in at least one direction based on another type of load placed on the work vehicle, such as the current load placed on the main engine (e.g., internal combustion engine) of the work vehicle engine. Additionally, while the previous description focused primarily on varying MRF resistance based on changes in monitored work vehicle load in isolation or in an independent sense, further embodiments of MRF joystick system 22 may adjust MRF resistance based on changes in load (or another monitored work vehicle parameter referred to herein) corresponding to another parameter or threshold. For example, in certain embodiments, the controller architecture 50 may compare the monitored load to a predetermined threshold value (e.g., a certain minimum load value stored in the memory 48) and implement the MRF resistance modification described above only after the currently monitored load exceeds the threshold value. A similar method may be used to assist an operator in driving 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 dump assist or control function described in the following paragraphs.

Embodiments of MRF joystick system 22 may monitor the current fill weight of the end effector or load carrying implement and vary the MRF resistance based on the difference between the target dump weight (target tipoff weight) and the current fill weight of the implement task. In this regard, certain work vehicles (such as wheel loaders, excavators, and the like equipped with fillable buckets) may be provided with a dump control function that may assist an operator with filling a desired amount of material into a sump (e.g., the bucket of a dump truck) with the work vehicle. In such a case, the MRF joystick system may utilize any of the methods described herein (e.g., using strain gauges, load sensors, or any number of pressure sensors) to estimate the amount of material (e.g., by weight), and then utilize this information to determine the manner in which the change in MRF joystick stiffness is to be applied, thereby communicating to the operator that an appropriate amount of material is within the bucket to meet the set weight target of the dump truck (or other receptacle). Referring to the example excavator 20, in particular, the controller architecture 50 may first set a target dump weight to which the bucket 26 is desirably filled; for example, by recalling default settings from memory 48 or settings entered into the excavator computer via operator interface 78. The controller architecture 50 then selectively varies the MRF resistance based on the difference between the target dump weight and the current fill weight of the bucket 26, as previously described. Such an MRF lever response may be generated when the bucket 26 is first filled (e.g., by increasing the lever stiffness, by providing a stop effect, or by providing a pulsation effect) when the target bucket load is achieved. In other cases, if the bucket 26 is inadvertently overfilled by the operator while driving the work vehicle, the MRF joystick system may provide a similar tactile cue to assist the operator in discharging the appropriate amount of material to meet the target bucket load.

With continued reference to step 204 of the MRF machine state feedback process 190 (fig. 5), in some cases, the controller architecture 50 may also vary the MRF resistance and thus the stiffness of the joystick based on the work vehicle ground speed (parameter 210). In one possible approach, the controller architecture 50 may selectively increase the MRF resistance to resist joystick movement in the direction used to control vehicle steering at higher vehicle speeds, and such increase is potentially performed gradually (continuously) or in a step-wise manner with any number of discrete resistance increase intervals. Such ground speed related increases in joystick stiffness may be applicable to the example excavator 20 when operable in a travel mode in which the direction of travel of the excavator 20, and also the ground speed, may be controlled using the joystick devices 52, 54 (fig. 2) described above. Furthermore, in embodiments, MRF resistance may be increased about an axis of rotation corresponding to the steering of the excavator 20; it is also possible to increase the MRF resistance about an axis of rotation corresponding to acceleration and deceleration of the excavator 20 (in which case such gradual increase in MRF resistance may be provided only in the direction of joystick rotation that causes acceleration of the excavator). Such an approach may also be usefully applied (and perhaps more beneficial) in the case of work vehicles capable of traveling at higher ground speeds and/or in the case of work vehicles that are propelled specifically in response to joystick control, such as the example SSL218 described below in connection with fig. 6. Generally, increasing the MRF joystick resistance at higher vehicle speeds may advantageously improve the accuracy with which an operator may steer the work vehicle and provide a better indication of operator intent because the operator needs to move the joystick in a desired manner against more force (thereby reducing the likelihood of inadvertent joystick movement due to oscillations or other effects in the presence of high vibrational forces that often occur during travel of the work vehicle).

In still further embodiments of work vehicle MRF joystick system 22, and as indicated by parameter 212 in fig. 5, controller architecture 50 may selectively vary the MRF resistance, and thus the joystick stiffness, for track shaping purposes. Specifically, in such embodiments, when an immediate transition to an operator-commanded state is not achievable or desired (e.g., in the case of acceleration or deceleration, which may result in the work vehicle suddenly leaning forward or stopping suddenly, or at higher ground speeds which may result in the work vehicle changing direction of travel sharply (and potentially becoming unstable)), controller architecture 50 may change the MRF resistance in accordance with the curve or profile that the work vehicle is following when transitioning from a current state of motion (e.g., work vehicle ground speed or steering angle) to the operator-commanded state of motion (e.g., new work vehicle speed or steering angle). Thus, if the operator attempts to move the joystick in a manner that would result in such an undesirable sudden change in machine state (e.g., a sudden acceleration, deceleration, or turn of the work vehicle), or quickly move the joystick from the neutral position to the end of travel of the joystick in a given direction, the MRF joystick system 22 may gradually increase the joystick stiffness (as indicated by the rate of change of the joystick) as the joystick is quickly moved from the neutral position toward the end of travel of the joystick. This may provide a better indication (improving the relationship between operator expectations and machine behavior) and may better match actual machine performance to joystick movement if the operator does intend to command such undesirable sudden changes in machine motion state. This can also be described as: controller architecture 50 is configured to (i) determine when movement of the joystick in the operator input direction at the detected rate will result in an undesirable abrupt change in the current state of motion of the work vehicle; and (ii) when so determined, issue a command to the MRF joystick resistance mechanism to increase the MRF resistance to hinder continued movement of the joystick in the operator input direction. A similar approach may also be used to facilitate smooth movement or "trajectory shaping" of a boom assembly controlled via a joystick, such as boom assembly 24 of example excavator 20 shown in fig. 1 and 2.

In still further embodiments of work vehicle MRF joystick system 22, and as indicated by example parameter 214 at step 204 of MRF machine state feedback process 190 (fig. 5), controller architecture 50 may monitor movement of one or more movable components of the work vehicle relative to a range of travel of the movable components; haptic feedback or cues are then provided via MRF resistance changes as the movable component approaches the end of its range of travel (referred to herein as a "motion stop point" or "motion stop"). Such a movable component may be, for example, an articulated joint (e.g., a pin pivot joint (pin pivot joint) of a boom assembly) of a work vehicle or an articulated joint of a hydraulic cylinder or a boom assembly having a stroke limitation. To provide a more specific example, and referring again to excavator 20 (fig. 1 and 2), as the movement of boom assembly 24 approaches the end of its range of motion along a particular DOF, or as one or more of

hydraulic cylinders

38, 40, 42 approaches their respective travel range limits, controller architecture 50 may vary the MRF resistance to joystick rotation about an axis corresponding to the movement of the assembly in the following manner: the operator is informed (by tactile feedback) that the assembly is approaching a motion stop. This feedback may be provided by gradually increasing the MRF resistance against the following joystick movements: the joystick movement commands the movable assembly to move toward the end of travel of the movable assembly (e.g., extension or retraction of a hydraulic cylinder). Alternatively, a pulsing effect or a short stopping effect may be generated before the movable assembly reaches the end of travel of the movable assembly (e.g., when a set percentage (e.g., 5%) of the range of travel of the hydraulic cylinder remains as the hydraulic cylinder or hydraulic cylinder pair extends or retracts according to the joystick command). By providing such haptic feedback of the applied MRF via changes in joystick stiffness, the awareness of the operator may be enhanced as a particular joystick-controlled component approaches the end of travel of that component. At the same time, a soft stop effect is created to help cushion or reduce the impact force that may otherwise be generated when a work vehicle part or component reaches the end of travel of the part or component. A similar approach may also be utilized when other limits of the work vehicle are approached, such as when the EH actuation system 44 approaches a stall condition (stall condition) in response to operator commands input via one or more MRF joystick devices.

In still other embodiments, the MRF joystick system 22 may selectively vary the MRF resistance that inhibits joystick movement in at least one DOF in a manner that mimics conventional systems familiar to operators, as indicated by parameters 215 listed in step 204 of the MRF machine state feedback process 190 (fig. 5). In this regard, certain operators who may be accustomed to interacting with a mechanical joystick having a direct mechanical connection to a hydraulic valve (e.g., a pilot or spool valve) within EH actuation system 22 may be disadvantaged by the lack of such a direct "tactile" connection when utilizing an EH joystick that converts joystick motion into an electrical signal that is sent to a valve solenoid (valve solenoids) or other actuators to perform such functions. Embodiments of the MRF joystick system 22 may advantageously retain the versatility and other benefits of EH control schemes while selectively generating joystick behaviors that mimic purely mechanical systems 22. As alluded to previously, this may be accomplished by increasing MRF resistance as a function of hydraulic pressure within the EH actuation system 22, thereby increasing the stiffness of the joystick. Similarly, the controller architecture 50 may control the MRF joystick resistance mechanism to simulate a lift-off or a crack (crack) with a valve (e.g., a pilot valve) of the EH actuation system 22, for example, by: the MRF resistance is initially high as the joystick is first displaced in a given direction (the operator input direction), and then quickly decreases after movement of the joystick over a shorter range of travel in the operator input direction. Utilizing the MRF joystick system 22 to mimic other mechanical control characteristics may likewise generate various other effects or otherwise provide a more consistent experience to the operator when transitioning from a mechanical joystick to an EH joystick control scheme.

In the manner described above, embodiments of the MRF joystick system 22 may provide tactile feedback to the operator indicating the current machine state or parameters by selectively increasing the MRF resistance resisting joystick movement in at least one DOF. Such feedback is provided to an operator interacting with the MRF joystick device described above in a highly intuitive and fast manner. Further benefits may be obtained by using the MRF technique itself, which is also capable of selectively impeding joystick movement when the joystick returns to a neutral position after being displaced from the neutral position, as opposed to using other resistance mechanisms, such as an actuated friction or brake (brake) mechanism. Such benefits may include: highly shortened response times; minimal frictional losses without resistance via applied MRF; reliable substantially noise-free operation; as well as other benefits as discussed further below. Additionally, the embodiments of the MRF joystick resistance mechanism described below are capable of generating a continuous range of resistances within a resistance range in a relatively precise manner and in accordance with commands or control signals issued by the controller architecture 50. While the foregoing description has primarily focused on a particular type of work vehicle (excavator) that includes particular joystick-controlled work vehicle functions (boom-assembly movement), embodiments of the MRF joystick system described herein are suitable for integration into a wide range of work vehicles, as discussed further below in connection with fig. 6.

Additional examples of work vehicles advantageously equipped with an MRF joystick system

Turning now to fig. 6, an additional example of a work vehicle is illustrated that may beneficially incorporate embodiments of the MRF joystick system. The upper left side of fig. 6 illustrates an example work vehicle, the middle illustrates an example MRF joystick apparatus, and the right side illustrates controlled vehicle functions, including but not limited to: front End Loader (FEL) movement, chassis movement, multi DOF shovel movement (including shovel-hover assembly rotation). While the lower portion of fig. 6 illustrates other example work vehicles potentially equipped with MRF joystick devices. Specifically, and with initial reference to the upper portion of fig. 6, three such work vehicles are shown: a wheel loader 216, a Skid Steer Loader (SSL)218, and a motor grader 220. First with respect to the wheel loader 216, the wheel loader 216 may be equipped with an example MRF joystick device 222 that is disposed within a cab 224 of the wheel loader 216. When provided, MRF joystick device 222 may be used to control movement of the FEL 226 terminating in a bucket 228; and in the context of this document, the FEL 226 and front-end loader are generally considered to be of the "boom-assembly" type. In comparison, two MRF joystick devices 230 may be placed in the cab 232 of the example SSL218 and used to control not only the movement of the FEL 234 and its dipper 236, but also to further control the movement of the chassis 238 of the SSL218 in a known manner. Finally, the motor grader 220 also includes two MRF joystick devices 240 disposed within a cab 242 of the motor grader 220. The MRF joystick device 240 may be used to control movement of the motor grader chassis 244 (by controlling a first transmission that drives the rear wheels of the motor grader and possibly a second (e.g., hydrostatic) transmission that drives the front wheels), as well as movement of the grader's blade 246 (e.g., by rotation and angular adjustment of the blade-circle assembly 248, and adjustment of the side-to-side angle of the blade 246).

In each of the above-mentioned examples, the MRF joystick device may be controlled to provide machine state feedback through intelligent MRF applied joystick stiffness changes. In this regard, any or all of the example wheel loader 216, SSL218, and motor grader 220 may be equipped with a work vehicle MRF joystick system that includes at least one joystick device, an MRF joystick resistance mechanism, and a controller architecture. Finally, the lower portion of fig. 6 illustrates a still further example of a work vehicle usefully equipped with an embodiment of the MRF joystick system described herein, and includes a FEL-equipped tractor 250, a feller stacker 252, a skidder 254, a combine 256, and a bulldozer 258. In various instances, the MRF joystick device may selectively vary the MRF resistance resisting joystick movement along at least one DOF to provide tactile feedback indicative of the monitored parameter relating to the work vehicle in question. Again, these parameters may include work vehicle load, ground speed, and proximity of movable work vehicle components to motion stops. The change in MRF resistance may also be used to simulate conventional systems (e.g., providing tactile feedback indicating pilot valve cocking) and/or to resist (or ensure operator intent causes) joystick movement that results in relatively abrupt changes in the motion state of the work vehicle, as previously discussed.

Enumerated examples of work vehicle MRF joystick systems

For ease of reference, the following examples of work vehicle MRF joystick systems are also provided and numbered.

1. In an embodiment, a work vehicle MRF joystick system is provided, comprising: a joystick device; the work vehicle control system includes an MRF joystick resistance mechanism, a controller architecture, and a work vehicle sensor configured to provide sensor data indicative of an operating parameter related to the work vehicle. The joystick device further 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 that resists movement of the joystick relative to the base housing in at least one degree of freedom. The controller architecture coupled to the joystick position sensor, the work vehicle sensor, and the MRF joystick resistance mechanism is configured to: (i) monitoring changes in the operating parameter using the sensor data; and (ii) provide tactile feedback indicative of the operating parameter through the joystick device by selectively commanding the MRF joystick resistance mechanism to adjust the MRF resistance that resists movement of the joystick based at least in part on the change in the operating parameter.

2. The work vehicle MRF joystick system of example 1, wherein the operating parameter is a hydraulic load exerted on the work vehicle, while the controller architecture is configured to issue commands to the MRF joystick resistance mechanism to selectively increase the MRF resistance as the hydraulic load increases.

3. The work vehicle MRF joystick system of example 1, wherein the work vehicle includes an EH actuation system and an implement movable with the EH actuation system, the operating parameter is a circuit pressure of the EH actuation system; and the work vehicle sensor comprises a pressure sensor configured to monitor the circuit pressure.

4. The work vehicle MRF joystick system of example 1, wherein the work vehicle includes a load bearing assembly, the operating parameter is a weight of material borne by the load bearing assembly; and the controller architecture is configured to issue commands to the MRF joystick resistance mechanism to selectively increase the MRF resistance as the weight of the material increases.

5. The work vehicle MRF joystick system of example 4, wherein the load bearing assembly of the work vehicle includes a boom-mounted implement, with the controller architecture configured to increase the MRF resistance in a manner that impedes joystick movement that raises the boom-mounted implement.

6. The work vehicle MRF joystick system of example 4, wherein the load carrying assembly includes a sump of the work vehicle, while the operating parameter is a payload weight held by the sump.

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) establishing a target dump weight at which filling of the bucket is desired, and (ii) selectively changing the MRF resistance based on a difference between the target dump weight and the current fill weight of the bucket.

8. The work vehicle MRF joystick system of example 1, wherein the operating parameter is a ground speed of the work vehicle, while the controller architecture is configured to issue commands to the MRF joystick resistance mechanism to selectively increase the MRF resistance as the ground speed of the work vehicle increases.

9. The work vehicle MRF joystick system of example 8, wherein the MRF resistance resists joystick movement that controls at least one of work vehicle travel direction and work vehicle ground speed.

10. The work vehicle MRF joystick system of example 1, wherein the work vehicle includes a movable assembly having a motion stop point, the operating parameter is displacement of the movable assembly relative to the motion stop point, and the controller architecture is configured to issue a command to the MRF joystick resistance mechanism to selectively increase the MRF resistance as the movable assembly approaches the motion stop point.

11. The work vehicle MRF joystick system of example 10, wherein the moveable assembly includes a hydraulic cylinder with a travel limit or an articulation joint of a boom assembly.

12. The work vehicle MRF joystick system of example 1, wherein the work vehicle includes an EH actuation system including a pilot valve, with the controller architecture configured to issue commands to the MRF joystick resistance mechanism to selectively vary the MRF resistance in the following manner: providing haptic feedback indicating when the pilot valve is initially open.

13. The work vehicle MRF joystick system of example 1, wherein the joystick device is used to control movement of the work vehicle and the operating parameter is a current state of motion of the work vehicle. The controller architecture is configured to: (i) determining when movement of the joystick in the operator input direction at the detected rate will result in an undesirable abrupt change in the current state of motion of the work vehicle; and (ii) when it is determined that movement of the joystick in the operator input direction at the detected rate would result in an undesirable abrupt change in the current state of motion of the work vehicle, issuing a command to the MRF joystick resistance mechanism to increase the MRF resistance to impede continued movement of the joystick in the operator input direction.

14. The work vehicle MRF joystick system of example 13, wherein the joystick device is used to control at least one of a ground speed of the work vehicle and a direction of travel of the work vehicle.

15. The work vehicle MRF joystick system of example 13, wherein the work vehicle includes a boom assembly attached to a chassis of the work vehicle, while the joystick device is used to control movement of the boom assembly.

Conclusion

Accordingly, the foregoing provides a work vehicle MRF joystick system configured to provide machine state feedback through changes in MRF resistance. Such parameters may include, for example: various loads applied to the work vehicle, the ground speed of the work vehicle, and the proximity of the movable work vehicle components to the motion stops. Further, in some embodiments, the MRF joystick system may vary the MRF resistance resisting joystick movement in a manner that mimics conventional systems in which a mechanical linkage is provided between the joystick and an actuated component, such as a pilot valve. In still further other implementations where a joystick device is used to control movement of a work vehicle, such as ground speed, direction of travel, or boom assembly movement, the MRF joystick system may increase MRF resistance to prevent (or confirm operator intent) joystick movement that results in relatively abrupt changes in the current motion state of the work vehicle. When doing so, embodiments of the MRF joystick system intuitively provide tactile feedback, thereby enhancing an operator's awareness of key parameters or conditions of the work vehicle, to increase operator satisfaction, to increase the efficacy of performing various work tasks with the work vehicle, and to provide other benefits, such as minimizing component wear with reduced abrupt changes in work vehicle motion.

As used herein, a description in the singular is intended to include the plural unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used herein, 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.

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. Various modifications and alterations will become apparent to those skilled in the art without departing from the scope and spirit of this disclosure. The embodiments specifically referenced herein were chosen and described in order to best explain the principles of the disclosure and its practical application, and to enable others of ordinary skill in the art to understand the disclosure and various alternatives, modifications, and variations to the described examples. Accordingly, various embodiments and implementations other than those explicitly described are within the scope of the following claims.

Claims

1. A work vehicle magnetorheological fluid joystick system (22), a work vehicle MRF joystick system (22), for use on a work vehicle (20), the work vehicle MRF joystick system (22) comprising:

a joystick device (52, 54), the joystick device (52, 54) comprising:

a base shell (62);

a lever (60), the lever (60) being movably mounted to the base housing (62); and

a joystick position sensor (66), the joystick position sensor (66) configured to monitor movement of the joystick (60) relative to the base housing (62);

a MRF joystick resistance mechanism (56), the MRF joystick resistance mechanism (56) controllable to vary a MRF resistance that resists joystick movement relative to the base housing (62) in at least one degree of freedom;

a work vehicle sensor (70), the work vehicle sensor (70) configured to provide sensor data indicative of an operating parameter related to a work vehicle (20); and

a controller architecture (50), the controller architecture (50) coupled to the joystick position sensor (66), the MRF joystick resistance mechanism (56), and the work vehicle sensor (70), the controller architecture (50) configured to:

monitoring changes in the operating parameter using the sensor data; and

providing haptic feedback indicative of the operating parameter through the joystick device (52, 54) by selectively commanding the MRF joystick resistance mechanism (56) to adjust the MRF resistance based at least in part on the change in the operating parameter.

2. The work vehicle MRF joystick system (22) according to claim 1, wherein the operating parameters include a hydraulic load exerted on the work vehicle (20); and is

Wherein the controller architecture (50) is configured to issue commands to the MRF joystick resistance mechanism (56) to increase the MRF resistance as the hydraulic load increases.

3. The work vehicle MRF joystick system (22) according to claim 1, wherein the work vehicle (20) includes: an electro-hydraulic actuation system (44), or EH actuation system (44), and an implement (26) movable with the EH actuation system (44);

wherein the operating parameter comprises a circuit pressure of the EH actuation system (44); and is

Wherein the work vehicle sensor (70) comprises a pressure sensor configured to monitor the circuit pressure.

4. The work vehicle MRF joystick system (22) according to claim 1, wherein the work vehicle (20) includes a load carrying assembly (26);

wherein the operating parameter comprises a weight of material borne by the load bearing assembly (26); and is

Wherein the controller architecture (50) is configured to issue commands to the MRF joystick resistance mechanism (56) to increase the MRF resistance as the weight of the material increases.

5. The work vehicle MRF joystick system (22) according to claim 4, wherein the load carrying assembly of the work vehicle (20) includes a boom-mounted implement (26); and is

Wherein the controller architecture (50) is configured to increase the MRF resistance in a manner that resists movement of a joystick that raises the boom-mounted implement (26).

6. The work vehicle MRF joystick system (22) according to claim 4, wherein the load carrying assembly includes a sump of the work vehicle (20); and is

Wherein the operating parameter comprises a payload weight retained by the sump.

7. The work vehicle MRF joystick system (22) according to claim 1, wherein the work vehicle (20) includes a bucket (26);

wherein the work vehicle sensor (70) is configured to monitor a current fill weight of the bucket (26); and is

Wherein the controller architecture (50) is configured to:

establishing a target dump weight at which filling of the bucket (26) is desired; and

selectively varying the MRF resistance based on a difference between the target dump weight and the current fill weight of the bucket.

8. The work vehicle MRF joystick system (22) according to claim 1, wherein the operating parameters include a ground speed of the work vehicle (20); and is

Wherein the controller architecture (50) is configured to issue commands to the MRF joystick resistance mechanism (56) to increase the MRF resistance as the ground speed of the work vehicle (20) increases.

9. The work vehicle MRF joystick system (22) according to claim 8, wherein the MRF resistance resists joystick movement that controls at least one of work vehicle travel direction and work vehicle ground speed.

10. The work vehicle MRF joystick system (22) according to claim 1, wherein the work vehicle (20) includes a movable assembly (24) having a motion stop point;

wherein the operating parameter comprises a displacement of the movable assembly (24) relative to the motion stop point; and is

Wherein the controller architecture (50) is configured to issue commands to the MRF joystick resistance mechanism (56) to selectively increase the MRF resistance as the movable assembly (24) approaches the motion stop point.

11. The work vehicle MRF joystick system (22) according to claim 10, wherein the movable assembly (24) includes a hydraulic cylinder (38, 40, 42) with a travel limit or an articulation joint of a boom assembly (24).

12. The work vehicle MRF joystick system (22) according to claim 1, wherein the work vehicle (20) includes an electro-hydraulic actuation system (44), EH actuation system (44), the EH actuation system (44) including a pilot valve; and is

Wherein the controller architecture (50) is configured to issue commands to the MRF joystick resistance mechanism (56) to selectively vary the MRF resistance in the following manner: providing haptic feedback indicating when the pilot valve is initially open.

13. The work vehicle MRF joystick system (22) according to claim 1, wherein the joystick device (52, 54) is for controlling movement of the work vehicle (20);

wherein the operating parameter comprises a current state of motion of the work vehicle (20); and is

Wherein the controller architecture (50) is configured to:

determining when movement of the joystick (60) in an operator input direction at a detected rate will result in an undesirable abrupt change in the current state of motion of the work vehicle (20); and is

When it is determined when movement of the joystick (60) in the operator input direction at the detected rate would result in an undesirable abrupt change in the current state of motion of the work vehicle (20), a command is issued to the MRF joystick resistance mechanism (56) to increase the MRF resistance to impede continued movement of the joystick (60) in the operator input direction.

14. The work vehicle MRF joystick system (22) according to claim 13, wherein the joystick device (52, 54) is for controlling at least one of a ground speed of the work vehicle (20) and a direction of travel of the work vehicle (20).

15. The work vehicle MRF joystick system (22) according to claim 13, wherein the work vehicle includes a boom assembly (24), the boom assembly (24) being attached to a chassis (28) of the work vehicle (20); and is

Wherein the joystick means (52, 54) is for controlling movement of the boom assembly (24).