CN113586629A

CN113586629A - Work vehicle magnetorheological fluid joystick system with adjustable joystick return position

Info

Publication number: CN113586629A
Application number: CN202110354328.3A
Authority: CN
Inventors: B·S·格雷厄姆; A·R·范德格里夫特
Original assignee: Deere and Co
Current assignee: Deere and Co
Priority date: 2020-05-01
Filing date: 2021-04-01
Publication date: 2021-11-02
Also published as: DE102021203860A1

Abstract

The present disclosure relates to a work vehicle magnetorheological fluid joystick system with an adjustable joystick return position. Specifically, a work vehicle magnetorheological fluid (MRF) joystick system includes a joystick device. The joystick device, in turn, includes a base housing and a joystick rotatable relative to the base housing and biased toward a joystick return position. The MRF joystick resistance mechanism may be controlled to vary the MRF resistance resisting movement of the joystick relative to the base housing. While coupling a controller architecture to the MRF joystick resistance mechanism. The controller is configured to: (i) operator adjustment to enable a work vehicle operator to selectively initiate the joystick return position; and (ii) when operator adjustment of the joystick return position is initiated, issuing a command to the MRF joystick resistance mechanism to maintain MRF resistance at a predetermined level until operator adjustment of the joystick return position is terminated.

Description

Work vehicle magnetorheological fluid joystick system with adjustable joystick return position

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 work vehicle (work vehicle) magnetorheological fluid (MRF) joystick systems including at least one joystick biased toward a joystick (joy) return position, which may be adjusted to an operator preference.

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 mounted to an external terminal of the boom assembly. Common examples of work vehicles having such boom assemblies controlled via a joystick include: excavators (excavator), feller bunkers (feeder), skidders (skid), tractors (on which modular front end loader (loader) and backhoe (backhoe) attachments may 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 often used to steer or otherwise control 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 includes the joystick device having a base housing and a joystick rotatable relative to the base housing and biased toward a joystick return position. The MRF joystick resistance mechanism can be controlled to vary the MRF resistance resisting movement of the joystick relative to the base housing. The controller architecture is coupled to the MRF joystick resistance mechanism and configured to: (i) operator adjustment to enable a work vehicle operator to selectively initiate the joystick return position; and (ii) when operator adjustment of the joystick return position is initiated, issuing a command to the MRF joystick resistance mechanism to maintain the MRF resistance at a predetermined level until operator adjustment of the joystick return position is terminated.

In other embodiments, the work vehicle MRF joystick system includes the joystick device having a base housing and a joystick rotatable relative to the base housing and biased toward a joystick return position. The work vehicle MRF joystick system further includes an MRF joystick resistance mechanism controllable to vary an MRF resistance resisting movement of the joystick relative to the base housing; a Joystick Return Position (JRP) lock mechanism, the JRP lock mechanism being external to the base housing; and a controller architecture coupled to the MRF joystick resistance mechanism and the JRP locking mechanism. The JRP locking mechanism is movable between a locked state preventing adjustment of the joystick return position and an unlocked state permitting adjustment of the joystick return position. The controller architecture is configured to: (i) issuing a command to the MRF joystick resistance mechanism to generate a maximum MRF resistance that substantially prevents movement of the joystick relative to the base housing when an operator adjustment of the joystick return position is received; and (ii) when operator adjustment of the joystick return position is terminated, issuing a command to the MRF joystick resistance mechanism to remove the maximum MRF resistance.

In other implementations, the work vehicle MRF joystick system includes: a joystick device, an MRF joystick resistance mechanism, and a JRP locking mechanism. The joystick device further includes: a base shell; a lever rotatable relative to the base housing; a spring contained in the base housing and exerting a resilient biasing force on the lever urging the lever toward a lever return position; and an adjustable spring support having a first end mounted to the base housing and having a second end supporting the spring. The MRF joystick resistance mechanism can be controlled to vary the MRF resistance resisting movement of the joystick relative to the base housing. The JRP locking mechanism is at least partially contained in the base housing and coupled to the adjustable spring support. The JRP locking mechanism is movable between: a locked state preventing position adjustment of the adjustable spring support, and an unlocked state permitting position adjustment of the adjustable spring support.

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) and having an adjustable joystick return position as illustrated in accordance with an example embodiment of the present disclosure;

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 schematic view of the MRF joystick device shown in FIGS. 3 and 4 in an example implementation, wherein the joystick device includes a JRP locking mechanism external to a base housing of the joystick device;

FIG. 6 is a simplified cross-sectional schematic view of the MRF lever device shown in FIG. 5, illustrating an example hydraulic cylinder and shut-off valve that may be included in an embodiment of the JRP locking mechanism;

FIG. 7 is a diagram illustrating, in a non-exhaustive manner, additional example work vehicles in which embodiments of the MRF joystick systems shown in FIGS. 1-6 may be advantageously integrated;

FIGS. 8 and 9 are schematic diagrams of example MRF joystick devices similar to those shown in FIGS. 3 and 4, respectively, in alternative implementations, in which a JRP locking mechanism is integrated into a base housing of the joystick device; and

fig. 10 and 11 are top-view schematics illustrating a manner in which the position at which a particular MRF resistance effect (e.g., MRF motion stop) and/or detent (detent)) is generated during operation of an example MRF joystick device (fig. 8 and 9) may be modified in conjunction with operator adjustment of the joystick return position.

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 illustrative 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.

SUMMARY

Embodiments of a work vehicle magnetorheological fluid (MRF) joystick system include at least one joystick biased toward a joystick return position, which may be adjusted to operator preference. The MRF joystick system also includes a processing subsystem or "controller architecture" coupled to the MRF joystick resistance mechanism; i.e. a mechanism, device or damper that contains a magnetorheological fluid and is capable of modifying the rheology (viscosity) of the fluid by changes in Electromagnetic (EM) field strength to provide controlled adjustment of the resistance to joystick movement in one or more degrees of freedom (DOF). This resistance is referred to hereinafter as "MRF resistance," and the degree to which the MRF resistance opposes joystick motion in a particular direction or combination of directions is referred to as "joystick stiffness. Through the use of such MRF techniques, embodiments of MRF joystick devices may generate various haptic resistance effects that may be felt by the work vehicle operator, including selective application of stops, and continuous changes in MRF resistance that inhibit joystick movement in one or more directions. Furthermore, in some cases, a maximum MRF resistance may be generated to attempt to prevent certain joystick movements, or to limit the range of joystick movement (ROM) to a particular mode or range of movement. Regardless of the particular MRF effect or control scheme employed during operation of the MRF joystick system of a work vehicle, embodiments of the present disclosure utilize the unique MRF capabilities of one or more joystick devices included in the MRF joystick system to provide an intuitive manual drive process that adjusts the joystick return position of a given joystick device to operator preferences.

In addition to the above-mentioned components, embodiments of the work vehicle MRF joystick system further include at least one Joystick Return Position (JRP) lock mechanism that is movable between a locked state and an unlocked state. In the locked state, the JRP locking mechanism prevents operator adjustment of the lever return position for a given MRF lever device. Conversely, in the unlocked state, the JRP locking mechanism enables operator adjustment of the lever return position of the lever device. The JRP locking mechanism may take a variety of forms to provide this functionality, for example, depending on whether the JRP locking mechanism is integrated into the main case or "base case" of the joystick device, or otherwise externally positioned relative to the base case of the joystick device. When integrated into the base housing, the JRP locking mechanism may support one or more mechanical springs (or other biasing components) that are also contained within the base housing and coupled to the lower portion of the lever. Collectively, the springs exert a cumulative biasing force urging the lever to rotate toward the operator-adjustable lever return position. In one implementation, the JRP locking mechanism may include a hydraulic cylinder and a shut-off valve that may be controlled by a controller architecture to selectively permit or prevent fluid flow between the hydraulic chambers of the cylinder. The hydraulic cylinder, in turn, includes a cylinder body and a piston that is free to translate relative to the cylinder body when fluid flow between the cylinder chambers is permitted. Collectively, the hydraulic cylinders and springs may be referred to as "cylinder-spring pairs". While potentially including any practical number of cylinder-spring pairs, a given MRF joystick device will typically include one to four cylinder-spring pairs, depending on the envelope of the joystick device, the number of DOF the joystick may move, and other factors.

In the above example, the work vehicle operator may be permitted to adjust the joystick return position of the MRF joystick device using the following process steps. First, the operator provides some form of input (as received by the controller architecture of the MRF joystick) to initiate the JRP adjustment process. In response to the operator input, the controller architecture unlocks the JRP locking mechanism to permit operator adjustment of the joystick return position; for example, when the JRP locking mechanism includes at least one hydraulic cylinder and a corresponding shut-off valve, the controller architecture may command the shut-off valve to open or otherwise temporarily permit fluid flow between the cylinder chambers. This allows the pistons of the various cylinders to translate freely while the operator grasps the joystick handle and rotates the joystick to the desired joystick return position. As the operator turns the joystick in this manner, the springs included in each cylinder-spring pair deflect to exert a force on their support pistons, which then translate to a new position to null the spring force and return the springs to an undeflected state. After adjusting the joystick to the operator adjusted joystick return position, the operator then inputs additional inputs to terminate the JRP adjustment process. Receiving the input, the controller architecture commands the JRP locking mechanism to relock; for example, by commanding the shut-off valve to close again or otherwise prevent fluid flow between the cylinder chambers. As a result, the cylinder pistons are prevented from their current translational position. Supported by the piston, the biasing spring now biases the joystick towards the most recently adjusted joystick return position during use of the MRF joystick device.

In embodiments of the work vehicle MRF joystick system, the controller architecture may store the JRP setting data in the computer readable memory after each termination of the JRP adjustment process. The controller architecture may then call this JRP setting data at the appropriate time to identify the following selected joystick positions: at this selected lever position, a particular position-dependent MRF effect is generated, such as an MRF stop encountered when the lever is rotated about one or more axes relative to the base housing. Furthermore, in embodiments where the JRP locking mechanism is located inside the base housing, movement of the joystick return position from its default, unmodified, or "true center" setting may result in some asymmetry in the range of motion (ROM) of the joystick. Such ROM asymmetries may be relatively small and therefore not compensated for in embodiments of MRF joystick systems. However, in other cases, the MRF joystick system may perform certain actions to correct for this symmetry, such as by intentionally shortening the joystick ROM in one or more selected directions. For example, in certain embodiments of a work vehicle MRF joystick system, when the joystick is rotated in the opposite direction about a given axis starting from an operator adjusted joystick return position, the controller architecture may generate an MRF motion stop at an appropriate position to equalize the ROM of the joystick, as discussed further below in conjunction with fig. 10 and 11.

In other implementations of a work vehicle MRF joystick system, the JRP locking mechanism may be external to the base housing of the MRF joystick device. In such a case, the base housing may be coupled to an adjacent (e.g., surrounding) support structure that is positioned adjacent to an operator's station or seat of the work vehicle; for example, in at least some instances, the support structure may be integrated into or otherwise coupled to a console or armrest of the work vehicle. In an embodiment, a multi-DOF (e.g., universal joint) coupling may be provided between the base housing and the support structure to enable the MRF joystick device to rotate about two perpendicular axes relative to the support structure within a limited angle ROM. The JRP locking mechanism may be mounted between the base housing and the support structure and may take any form suitable for preventing such relative movement between the base housing and the support structure when the JRP locking mechanism is locked. In some cases, the JRP locking mechanism may be a manually actuated locking device, such as one or more set screws (set screws), a clamp device, or the like, that may be turned or otherwise physically manipulated by an operator to selectively lock and unlock the JRP locking mechanism. This provides a structurally robust, cost-effective locking interface, with potentially reduced operator ease in trade-off. In more complex embodiments, the JRP locking mechanism may be an actuated rotary or linear device that can be remotely locked and unlocked through a controller architecture. For example, in an embodiment, a JRP locking mechanism may comprise: one or more hydraulic cylinders mechanically connected between the base shell and the support structure; and one or more valves (e.g., MRF or non-MRF shut-off valves) controllable by the controller architecture to selectively permit or prevent fluid flow between the chambers of the hydraulic cylinder.

In implementations where the JRP locking mechanism is external to the base housing, the following process may be performed by the controller architecture of the MRF joystick system to enable JRP adjustment by the work vehicle operator. First, the controller architecture may receive an operator input command requesting entry into the JRP adjustment mode. In response to the input command, the controller architecture causes the MRF joystick resistance mechanism to apply a maximum or peak MRF resistance that prevents joystick rotation relative to the base housing. In implementations where the JRP locking mechanism is non-manual, the controller architecture may also unlock the JRP locking mechanism in conjunction with commanding the MRF joystick resistance mechanism to generate the maximum MRF resistance. This combination of actions permits the operator to rotate the joystick handle being held and rotate the joystick to the desired joystick return position while the base housing rotates in conjunction with the joystick relative to the support structure. When an input is subsequently received indicating that the operator wishes to end or terminate the JRP adjustment process, the controller architecture controls the MRF joystick resistance mechanism to remove the maximum MRF resistance. If applicable, the controller architecture also commands the JRP locking mechanism to return to a locked state, again preventing rotation of the base housing relative to the support structure. In this way, the joystick return position is adjusted by a change in the angular orientation of the MRF joystick device relative to the support structure itself. The operator may then return to normal use of the MRF joystick device, with the joystick now biased to the operator adjusted joystick return position.

When the JRP locking mechanism is inside the base housing, the MRF joystick device may be given a relatively compact, structurally robust design. Additionally, for example, when the JRP locking mechanism includes one or more hydraulic cylinders that conduct magnetorheological fluid, integrating the JRP locking mechanism into the base housing may enable the JRP locking mechanism to share certain components (e.g., a common MRF valve or valve set) with the MRF lever resistance mechanism. In comparison, greater design flexibility may be provided when the JRP locking mechanism is external to the base housing, and ROM symmetry (and the desired MRF detent positioning, if applicable) may be maintained independent of (decoupled from) JRP adjustment to the MRF lever arrangement. Thus, different advantages are associated with both configurations. Regardless of whether the JRP locking mechanism is internal or external to the base housing, the work vehicle MRF joystick system utilizes the unique MRF capability of a given joystick device to provide an intuitive manual drive process to adjust the joystick return position of the joystick device to operator preferences. Thus, a work vehicle operator may easily select and reselect a desired joystick return position to maximize operator comfort and reduce ergonomic stress that may otherwise occur during prolonged joystick interaction.

A first example embodiment of a work vehicle MRF joystick system that permits operator adjustment of the joystick return position and includes a JRP locking mechanism external to the base housing of the MRF joystick device is described below in conjunction with fig. 1-6. 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, both of which include joysticks rotatable about two perpendicular axes, and are used to control movement of an excavating boom assembly and a tool or implement 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, 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 that include various joystick-controlled functions, additional examples of which are discussed below in connection with fig. 7. A second example embodiment of the MRF joystick system that permits operator JRP adjustment while incorporating a JRP locking mechanism inside the base housing of the MRF joystick device is further discussed below in conjunction with fig. 8-11.

Example MRF joystick System including at least one joystick device with an Adjustable joystick Return position

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 in 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-set 24, including other buckets, 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 "boom 34"), an outboard or distal boom 36 (hereinafter referred to as "dipper stick (dipper) 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 position adjacent (to the right of) the cab 32). Extension and retraction of the dipper handle cylinder 40 rotates the dipper 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 outer assembly 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 described below is capable of controlling movement of the boom-assembly 24 via commands sent to selected ones of the actuators 46 that perform the joystick-controlled functions of the excavator 20, the particular configuration or architecture of the EH actuation system 44 set forth herein is largely immaterial to the 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 set up 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 such will 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 (home) or joystick return position of the joystick (described below), as well as to fine tune the desired feel perceived by the operator in relation to the joystick 60 when interacting with 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. The MRF joystick resistance mechanism 56 may be controlled by the controller architecture 50 of the work vehicle MRF joystick system 22 to adjust the MRF resistance, and thus the joystick stiffness, against joystick movement relative to the base housing 62 in at least one DOF. In this regard, 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 provide a range of effects or modifications to the joystick behavior by selectively increasing the strength of the EM field in which the magnetorheological fluid contained in the mechanism 56 is at least partially immersed. For example, in an embodiment, the controller architecture 50 may issue commands to the MRF joystick resistance mechanism to generate localized regions of increased resistance (referred to herein as "MRF stops") encountered as the joystick is moved to a particular position. When applied, the MRF stop may be generated to apply an MRF resistance sufficient to overcome the biasing or "centripetal" force exerted on the lever, in which case the MRF stop may be referred to specifically as a "hold stop". In other cases, the MRF stop may be generated with a lower MRF resistance that is perceptible to the work vehicle operator manipulating the joystick, but this is not sufficient to prevent the joystick from returning to the joystick return position only under the influence of the centripetal force of the joystick. This latter type of MRF stop is referred to herein as a "feel stop". 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 MRF joystick system 22 also includes a JRP lock mechanism 70 associated with the MRF joystick device 52 and movable between a locked state and an unlocked state. In the locked state, the JRP locking mechanism 70 prevents operator adjustment of the lever return position of the MRF lever device 52. In the unlocked state, the JRP locking mechanism 70 permits the current operator of the excavator 20 to adjust the joystick return position. The JRP locking mechanism 70 may include any number, type, and arrangement of devices that provide this function. In certain embodiments, the JRP locking mechanism 70 may be external to the base housing 62 of the MRF lever device 52, as discussed in connection with fig. 5 and 6. Alternatively, in other cases, the JRP locking mechanism 70 may be internal to (integrated into) the base housing 62 of the MRF lever device 52, as discussed in conjunction with fig. 8 and 9. In some cases, the JRP locking mechanism 70 may comprise one or more operator-actuated purely mechanical devices, particularly when the JRP locking mechanism 70 is external to the base housing 62 of the MRF joystick device 52. More generally, however, the JRP locking mechanism 70 includes one or more actuated components that are remotely controlled by the controller architecture 50 during the JRP adjustment process. At this latter point, in the schematic diagram of fig. 1, arrows 72 represent data connections (wired or wireless) from the controller architecture 50 to the JRP locking mechanism 70 and to the MRF joystick resistance mechanism 56. Similarly, arrows 74 represent one or more data connections (wired or wireless) from the position sensor 66 and possibly also from other components of the MRF joystick device 52 (e.g., external buttons, dials, or other operator inputs) to the controller architecture 50.

Embodiments of the MRF joystick system 22 may also include any number of other non-joystick assemblies 76 in addition to those previously described. The additional non-joystick assembly 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. For example, the non-joystick sensor 82 may include a sensor or data source that detects and monitors vehicle motion, such as a Global Navigation Satellite System (GNSS) module (such as a Global Positioning System) module) that monitors the position and motion state of the shovel.

As further 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 a work vehicle MRF joystick system, such as the example 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 the operator station 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 and other data for supporting the operation of MRF joystick system 22; for example, the JRP setting data described below, as well as data relating to any MRF effects (e.g., the position at which the MRF stops) that are desirably generated during operation of the joystick device.

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, MRF joystick systems 22 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, which may 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 tracks of the tracked undercarriage 30.

Different control schemes may be utilized to translate movement of the joystick 60 included in the joystick devices 51, 54 into corresponding movement of the excavator motor arm 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 tracked 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 tracked undercarriage 30), movement of the left joystick 60 in a forward direction (arrow 98) lowers the lift arm 34, and movement of the left joystick 60 in a rearward (aft or return) direction (arrow 100) raises the lift arm 34. Also, for the case of the backhoe control mode, movement of the right joystick 60 to the left (arrow 102) causes the bucket 26 to roll inward, movement of the right joystick 60 to the right (arrow 104) causes the bucket 26 to spread (uncurl) or "open", movement of the right joystick 60 in a forward direction (arrow 106) causes the dipper handle 36 to rotate outward, and movement of the right joystick 60 in a rearward direction (arrow 108) causes the dipper 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 a number of 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 diameter of the central opening is 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 permits 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 permit 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 return or biasing spring 124; note here that this arrangement is simplified for illustrative purposes, and a more complex spring-biased 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 lever return position shown in fig. 3, the biasing 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, after rotation to the position shown in fig. 4, the lever 60 will return to the neutral or home position shown in fig. 3 (referred to herein as the "lever return position") under the influence of the biasing spring 124 should the work vehicle operator subsequently release the lever handle 110. Further discussion of the manner in which joystick 60 may be biased toward the joystick return position (which may be adjusted to operator preferences) is provided below in connection with fig. 5-11.

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 the lower lever extension 120 and a partially illustrated static attachment point or base structural feature 130 of the base housing 62. Similarly, a second MRF cylinder 128 (fig. 4) is mechanically engaged between the lower joystick extension 120 and the stationary attachment point 132 of the base housing 62, 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. Due to this structural configuration, the MRF cylinder 126 (FIG. 3) may 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) may be controlled to selectively resist rotation of the joystick 60 about the Y-axis of the coordinate legend 118. Additionally, both MRF cylinders 126, 128 may be commonly controlled to selectively resist rotation of the joystick 60 about any axis falling between the X and Y axes and extending within the X-Y plane. In other embodiments, 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 is only rotatable about a single axis, a single MRF cylinder or a pair of opposing 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 stroke (stroke) of the cylinders 126, 128 (if desired) to track, for example, the position of the joystick, in lieu of the

joystick sensors

182, 184 described below.

The MRF cylinders 126, 128 each include a cylinder block 134 to which a piston 138, 140 is slidably mounted. Each cylinder 134 contains a cylindrical cavity or bore 136 in which 136 is mounted a head 138 of one of the pistons 138, 140 for translational movement along a longitudinal axis or centerline of the cylinder 134. Around the periphery of this chamber 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 (anti-inflammatory) 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. The piston rod 140 extends through an end cap 142 fixed over the open end of the cylinder 134 (again, engaging any number of seals) to attach to the lower lever extension 120 at a 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, opposite ends of the MRF cylinders 126, 128 are mounted to respective stationary 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 line 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 permitted 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 inhibits 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 generally be able to control 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, which are 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 wound around a 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. Thus, this structural arrangement may enable the controller architecture 50 to command or control the MRF joystick resistance mechanism 56 to vary the strength of the EM field generated by the EM coils 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 above-mentioned conduit or

flow line connections

178, 180. The length of the

flowline connections

178, 180, for example, may ensure a flexible pipe with sufficient slack 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 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 resistive effects (e.g., tactile detent or pulsing 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. Further, 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 that inhibits 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 assemblies may include, where appropriate: operator inputs, and corresponding electrical connections provided on the joystick 60 or base housing 62, the AFF motor, and pressure and/or flow rate sensors included in the flow circuit of the MRF joystick resistance mechanism 56 to best suit a particular application or use.

As previously emphasized, the above-described embodiment of the MRF joystick device 52 is provided by way of non-limiting example only. In alternative implementations, the 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 inhibit movement of the joystick relative to the base housing in at least one DOF, in further embodiments, the MRF joystick resistance mechanism 56 also differs relative to the examples shown in fig. 3 and 4. In further implementation, an EM induction coil 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 this implementation, magnetorheological fluid flow between the variable volume chambers within a given MRF cylinder 126, 128 can be permitted via one or more orifices provided through the piston head 138 by providing an annulus (annular) or slightly smaller annular gap around the piston head 138 and the inner surface of the cylinder 134, or by providing a flow passage through the cylinder 134 or the sleeve itself. Advantageously, this 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 design of the MRF joystick device may permit 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), and the EM coil is placed around the lower portion of the joystick and surrounds the body of magnetorheological fluid. In such embodiments, the spherical base 112 may be provided with ribs, grooves or similar topological features to facilitate displacement of the magnetorheological fluid in conjunction with the lever rotation, wherein energizing the EM coil increases the viscosity of the magnetorheological fluid to impede fluid flow through the restricted flow passages provided around the spherical base 112, or may be due to the magnetorheological fluid turning in conjunction with the lever 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 that selectively produce variable MRF resistance or joystick stiffness that inhibits (resists or prevents) unintended joystick movement provides a number of advantages. As a major advantage, in terms of the rheology of the magnetorheological fluid, and ultimately in terms of the stiffness of the joystick applied via the MRF inhibiting 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 high responsivity and can achieve the desired variation 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 intensities 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.

Turning now to fig. 5, a schematic diagram of a joystick bearing assembly 190 including an example MRF joystick device 52 is shown in a simplified top view. In addition to the MRF joystick system 52, the joystick support assembly 190 also includes a support structure 192. The support structure 192 is disposed adjacent to the base housing 62 of the MRF joystick device 52 and may partially surround the base housing. The support structure 192 may be any structure or structural component suitable for mounting the MRF joystick device 52 at a desired location within a work vehicle; for example, in the cab 32 of the excavator 20 in this example. In some embodiments, the support structure 192 may be integrated into or otherwise attached to an armrest, console, or similar interior region of the work vehicle that is positioned adjacent to and conveniently accessible to the operator's seat. The base housing 62 of the joystick device 52 is coupled to the support structure 192 via

couplings

194, 196, the coupling 192 permitting limited rotation of the base housing 62 relative to the support structure 192 in at least one DOF. In this particular example, the

couplings

194, 196 take the form of universal joint couplings that permit the base housing 62 to rotate relative to the support structure 192 about two perpendicular axes over a limited angular range. The

universal couplings

194, 196 include: a first pin joint pair 194, the first pin joint 194 aligning the permissive shell 62 for limited rotation relative to the support structure 192 about the Y-axis of the coordinate legend 118; and a second pin joint pair 196, the second pin joint 196 aligned for limited rotation of the base housing 62 about the X-axis of the coordinate legend 118.

The JRP locking mechanism 198 is located between the base housing 62 of the MRF joystick device 52 and the surrounding support structure 192; for example, the JRP locking mechanism 198 may be disposed at a height below or beneath the base housing 62 of the MRF lever device 52, as schematically indicated in fig. 5. The JPR locking mechanism 198 is movable between a locked state (in which the JRP locking mechanism 198 typically resides) and an unlocked state. In the locked state, the JRP locking mechanism 198 prevents adjustment of the lever return position by rotationally fixing the base housing 62 to the support structure 192. Conversely, in the unlocked state, the JRP locking mechanism 198 enables rotational movement between the base housing 62 and the support structure 192 of the MRF joystick device to the extent permitted by the universal

joint couplings

194, 196. This permits operator adjustment of the joystick return position by modifying the angular orientation of the base housing 62 relative to the support structure 192, as discussed below.

In certain embodiments, the JRP locking mechanism 198 may include one or more manually actuated locking devices that may be manipulated by an operator to transition the JRP locking mechanism between a locked state and an unlocked state. Examples of such manual locking mechanisms include: set screws, clamping devices, spring-loaded plungers that may engage into dimples (divot) or other grooves provided on the exterior of the base housing 62, and the like. In other embodiments, the JRP locking mechanism 198 includes one or more actuated devices that may be controlled by the controller architecture 50 to transition the JRP locking mechanism 198 between a locked state and an unlocked state. For example, in certain embodiments, the JRP locking mechanism 198 may include one or more rotary or linear devices, such as a miniature clutch pack integrated into the

gimbal couplings

194, 196, which may be remotely engaged and disengaged by the controller architecture 50. In other implementations, the JRP locking mechanism 198 may comprise one or more linear devices mounted between the base housing 62 and the support structure 192 such that rotation of the base housing 62 may occur exclusively in conjunction with extension and retraction of the linear devices. For example, at this latter point, the JRP locking mechanism 198 may include one or more hydraulic cylinders that may be free to translate when fluid flow between the chambers of the cylinders is permitted. One or more shut-off valves may also be interconnected with the cylinders and operatively coupled to the controller architecture 50. Collectively, such hydraulic cylinders and shut-off valves are referred to herein as "lockable piston devices", two such lockable cylinder devices 200, 202 potentially disposed below the base housing 62 being schematically identified in fig. 5.

As presented herein, the term "hydraulic fluid" is defined to encompass both non-magnetorheological fluids and magnetorheological fluids that flow between the variable volume chambers of the hydraulic cylinder (and similar hydraulic devices) during operation of the MRF joystick system. Similarly, the term "hydraulic cylinder" is utilized herein with reference to a device (regardless of form factor) that includes one or more hydraulic chambers and a translating member (piston), the linear movement of which drives hydraulic fluid into or out of the cylinder chamber, or is driven by hydraulic fluid flowing into or out of the cylinder chamber. Finally, as noted above, the term "valve" refers to a valve that can be controlled to regulate the flow of hydraulic fluid (whether magnetorheological or non-magnetorheological in nature) through a valve body or flow passage of the valve. In embodiments where the valve controls the MRF flowing through the valve body by a change in a magnetic field that affects the properties (viscosity) of the magnetorheological fluid, the valve may be particularly referred to as an "MRF valve". For ease of reference, such an MRF valve may still be said to "move" to a particular position (e.g., a stop position) when controlled to adjust the MRF flow in a desired manner, with the understanding (as previously described) that the MRF valve may lack a movable valve member in a strict sense. Finally, as presented herein, the term "shut-off valve" refers to a valve that is capable of selectively preventing, or at least substantially impeding, the flow of hydraulic fluid through the valve body.

Fig. 6 further schematically illustrates the joystick bearing assembly 190 and MRF joystick device 52 in a cross-sectional view taken along a section plane parallel to the X-Y plane of the coordinate legend 118 and extending through the joystick 60. Referring collectively to fig. 5 and 6, the JRP locking mechanism 198 includes a first lockable cylinder device 200 and a second lockable cylinder device 202. The first lockable cylinder arrangement 200 is shown in more detail in the schematic diagram of fig. 6. Although the second lockable cylinder device 202 is not shown in fig. 6, in the illustrated example, the lockable cylinder devices 200, 202 are substantially identical; therefore, the following description applies equally to the second lockable cylinder arrangement 202. Each lockable cylinder device 200, 202 includes a

hydraulic cylinder

204, 206 and an associated shut-off valve 208. A shut-off valve 208 is fluidly interconnected with the

hydraulic cylinders

204, 206 associated with the shut-off valve via a plurality of flow lines 210; and the electronic components of the shut-off valve 208 (the actuator in the case of a non-MRF valve, the EM coil in the case of an MRF valve) are further coupled to the controller architecture 50, or to a power source controlled by the controller architecture 50, via one or more electrical connections 212. For purposes of the following description, each cylinder device section of the lockable cylinder devices 202, 204 is described as being fluidly interconnected with a separate shut-off valve 208; however, in other embodiments, lockable cylinder devices 200, 202 may share a common shut-off valve that may be moved to a shut-off position to simultaneously prevent fluid flow between the chambers of

hydraulic cylinders

204, 206 to lock cylinder piston 206 in a desired translational position.

The

hydraulic cylinders

204, 206 each include a cylinder 204 and a piston 206 that is translatable relative to the cylinder 204. As included in the first lockable cylinder arrangement 200, and as best shown in fig. 6, the first lockable cylinder arrangement 200 is mounted between a lower portion of the base housing 62 and a floor of the support structure 192. Specifically, the

hydraulic cylinders

204, 206 are received within a cavity 214 of the support structure 190, with the lower end portion of the cylinder 204 being mounted to the support structure 192 by a first ball joint coupling 216, and the outer end of the piston 206 being joined to the base housing 62 by a second ball joint coupling 218. In other implementations, different mounting interfaces may be utilized provided that the

hydraulic cylinders

204, 206 are capable of tilting or otherwise moving to accommodate changes in the angular orientation of the base housing 62 of the MRF joystick device 52 relative to the support structure 192. In this regard, and as previously discussed, when the JRP locking mechanism 198 is in the unlocked state, the universal

joint couplings

194, 196 permit rotation of the base housing 62 about the X and Y axes of the coordinate legend 118. The universal

joint couplings

194, 196 may also be positioned such that adjustment of the angular orientation of the base housing 62 relative to the support structure 192 is about a center point or origin that is substantially coincident with the center point or origin of the joystick rotation (the origin of the coordinate legend 118 in FIG. 6); however, this need not be the case in all embodiments. Likewise, similar mounting schemes may be provided for the

hydraulic cylinders

204, 206 included in the other lockable cylinder device 202 shown in fig. 5.

The controller architecture 50 of the MRF joystick system 22 (fig. 1) may control the shut-off valves 208 to selectively permit or prevent fluid flow between the hydraulic chambers of the

hydraulic cylinders

204, 206 included in the respective lockable cylinder devices 200, 202. When regulating the flow of non-magnetorheological hydraulic fluid, each of the sections of the shutoff valve 208 may be a non-MRF valve, such as a solenoid-actuated spool or stopper valve. Alternatively, in implementations where the magnetorheological fluid is directed through the valve 208 as it flows between the chambers of the

hydraulic cylinders

204, 206, the shut-off valve 208 may be an MRF valve (e.g., similar or substantially the same as the MRF valve 56 described above in connection with fig. 3 and 4). In implementations where the shut-off valve 208 is an MRF valve, the shut-off valve 208 may be combined with the MRF valve 56 described above into a single unit or valve block for design simplicity in certain situations. In other embodiments, the shut-off valve 208 may be a separate MRF valve; or replaced with a non-MRF shut-off valve containing a valve member that is moved between an open position and a closed position by an actuator under the command of the controller architecture 50. Further, while in the present example the JRP locking mechanism 198 is implemented using lockable cylinder devices 202, 204, it should be appreciated that in other embodiments, the lockable cylinder devices 202, 204 may be replaced with other types of linear devices that can be selectively locked in a given translational position by the controller architecture 50.

During normal or standard use of the MRF joystick device 52, the controller architecture 50 commands the shut-off valve 208 to move to a shut-off position, or otherwise prevents fluid flow between the chambers of the

hydraulic cylinders

204, 206. This prevents translation of the piston 206 included in the

hydraulic cylinders

204, 206, which in turn inhibits rotation of the base housing 62 relative to the surrounding support structure 192. To subsequently place the JRP locking mechanism 198 in its unlocked state, the controller architecture 50 commands the shut-off valve 208 to open (or otherwise permit fluid flow between the chambers of the hydraulic cylinders 204, 206), thereby freeing the pistons 206 of the

hydraulic cylinders

204, 206 for translation in conjunction with rotation of the base housing 62 relative to the support structure 192. Thus, when the JRP locking mechanism 198 is unlocked by the controller architecture 50, operator adjustment of the angular orientation of the base housing 62 of the MRF joystick device 52 relative to the support structure 192 is enabled, at least to the extent permitted by the universal

joint couplings

194, 196. In at least some embodiments, the controller architecture 50 facilitates operator adjustment of the angular position or orientation of the base housing 62 relative to the support structure 192 by issuing commands to the MRF joystick resistance mechanism 56 to apply MRF resistance at a level sufficient to prevent movement of the joystick 60 relative to the base housing 62; the MRF resistance so applied is referred to herein as the "maximum" or "peak" MRF resistance. The application of this maximum MRF resistance effectively locks or secures the joystick 60 to the base housing 62, which enables an operator to easily adjust the angular orientation of the base housing 62 relative to the support structure 192 by simply grasping and manipulating the handle of the joystick 60 as desired.

As identified by a legend (key)220 appearing in the upper portion of fig. 5, the current joystick return position of the MRF joystick device 52 is represented by a first slash mark 222. In the case where the MRF joystick device 52 is a joystick 60 that is rotatable about two perpendicular axes relative to the base housing 62, the joystick return position is the angular position or orientation toward which the joystick 60 is biased to return. As best shown in fig. 6, in the illustrated example, the base housing 62 of the MRF joystick device 52 is not tilted or angled relative to the support structure 192. This can be understood by comparing the angular orientation of the coordinate legend 118 (here, representing the reference frame of the joystick) with a second coordinate legend 224, which second coordinate legend 224 appears in the lower part of fig. 6 and represents the reference frame of the support structure 192. In the illustrated example where the joystick return position of the MRF joystick device 52 is in the default unadjusted or "true center" position, the Z-axes in the coordinate

legends

118, 224 are extending in parallel; for example, upward in the illustrated orientation, and may be such that the Z-axis of the coordinate legend 118 (and correspondingly, the joystick handle 110) extends substantially in an upright direction. When the base housing 62 is rotated to a new angular position relative to the support structure 192, the Z-axis of the joystick coordinate legend 118 will be at an angular offset from the Z-axis of the support structure coordinate legend 224. Likewise, the joystick return position will change in conjunction with a change in the angular orientation of the base housing 62 (coordinate legend 118) relative to the support structure 192 (coordinate legend 224).

In the present embodiment where the JRP locking mechanism 198 is external to the base housing 62 of the MRF joystick device 52, the following process may be performed by the controller architecture 50 to enable JRP adjustments by the work vehicle operator. First, as indicated by arrow 223 (fig. 5), the controller architecture 50 receives an operator input to initiate adjustment of the joystick return position of the MRF joystick device 52. Such operator input may be received via manual actuation of a physical input (such as a button or switch) provided on the MRF joystick device 52. As an arbitrary example, in one possible approach, an operator of the work vehicle may press and hold a button located on or near the MRF joystick device 52 (e.g., on an upper portion of the joystick handle 110 or on an upper surface of the base housing 62), thereby enabling operator adjustment of the joystick return position of the MRF joystick device 52. The operator may then release the button (or press the button a second time) to terminate or complete the JRP adjustment process, if desired. In other implementations, the work vehicle operator may provide input to initiate the JRP adjustment process in another manner, such as by interacting with a GUI generated on the display device 80 to select an on-screen option, thereby enabling adjustment of the joystick return position to operator preferences. Such a GUI may also permit other MRF related aspects of the MRF joystick device 52 to be adjusted to operator preferences, such as the force that generates the MRF stop described below.

In response to receiving an operator input to initiate the JRP adjustment process, the controller architecture 50 issues a command to the MRF joystick resistance mechanism 56 to apply a maximum or peak MRF resistance at a level sufficient to prevent (or at least substantially stop) joystick rotation relative to the base housing 62. In embodiments where the JRP locking mechanism 198 is non-manual in nature, the controller architecture 50 also issues a command to the JRP locking mechanism 198 to unlock in conjunction with the MRF joystick resistance mechanism 56 generating the maximum MRF resistance. In the present example, and as described above, the controller architecture 50 unlocks the JRP locking mechanism 198 by commanding the shut-off valve 208 to move to an open position, or otherwise temporarily permitting fluid flow between opposing hydraulic chambers of the

cylinders

204, 206. Specifically, when the shut-off valve 208 is a non-MRF valve, the controller architecture 50 commands the associated valve actuator to move the valve member to the closed position, thereby blocking hydraulic fluid flow between the valve body and the cylinder chamber. When the shut-off valve 208 instead takes the form of an MRF valve, the controller architecture 50 adjusts the power supplied to the EM coil within the valve 208 to reduce the strength of the EM field (or to terminate generation of the EM field altogether) to permit the magnetorheological fluid to flow through the valve body with relatively little flow resistance. With fluid flow now permitted between the opposing chambers of the

hydraulic cylinders

204, 206, the pistons 206 of the

cylinders

204, 206 may freely translate in conjunction with the angular displacement of the base housing 62 relative to the support structure 192. A work vehicle operator grasping the handle 110 of the joystick 60 may thus rotate the joystick 60, and thus the base housing 62, to any desired angular position or orientation relative to the support structure 192 permitted by the universal

joint couplings

194, 196. As the angular orientation of the base housing 62 is adjusted or modified in this manner, this results in a corresponding adjustment to the joystick return position of the MRF joystick device 52.

After rotating the joystick handle 110 to the operator adjusted joystick return position, the operator provides an input to the controller architecture 50 to terminate the JRP adjustment process. Upon receiving this operator input, the controller architecture 50 commands the JRP locking mechanism 198 to return to the locked state, thereby preventing further rotation of the base housing 62 relative to the support structure 192. In the illustrated example, the controller architecture 50 relocks the JRP locking mechanism 198 by returning the shut-off valve 208 to a closed or shut-off position (when the shut-off valve 208 is a non-MRF valve), or by causing the EM coil in the shut-off valve 208 to again generate an electromagnetic field of sufficient strength to substantially prevent fluid from flowing through the valve body (when the shut-off valve 208 is implemented as an MRF valve). Once again in the locked state, the JRP locking mechanism 198 inhibits rotation of the base housing 62 relative to the support structure 192, thereby fixing the base housing 62, and thus the lever return position, in the most recently selected angular orientation. Simultaneously with or shortly after returning the JRP locking mechanism 198 to the locked state, the controller architecture 50 also issues a command to the MRF joystick resistance mechanism 56 to stop generating the maximum MRF resistance. Thus, the work vehicle operator is permitted to again rotate the operating lever 60 relative to the base housing 62 about the X-axis and Y-axis of the coordinate legend 118 while the base housing 62 remains secured to the support structure 192. Normal use of the MRF joystick device 52 may be resumed and the joystick 60 is now biased toward the most recently selected joystick return position.

In certain embodiments, the controller architecture 50 of the MRF joystick system 22 may store JRP setting data 225 (fig. 5) within the computer readable memory 48 after the JRP adjustment process. The JRP setting data 225 may identify an operator adjusted joystick return position, which may be stored as coordinates, as an angular offset from an unmodified joystick return position, or in another manner. Additionally, in certain embodiments, the controller architecture 50 may store data in the memory 48 that associates unique operator identification data with various JRP settings. This, in turn, may allow MRF joystick system 22 to automatically assign a stored joystick position setting to a given MRF joystick device (e.g., MRF joystick device 52) when a particular work vehicle operator is identified (e.g., after the operator logs in with a unique pin code). The foregoing statements apply to embodiments in which the MRF joystick device 22 has force feedback capability or is otherwise capable of independently moving the joystick between different JRP settings. In other implementations, the controller architecture 50 may not store such JRP setting data 225 in the computer-readable memory 48 for such autoregulation purposes. However, in an alternative embodiment where the JRP locking mechanism is internal to the base housing 62 of the MRF joystick device 42, the JRP setting data may still be usefully stored in the computer readable memory 48, as discussed below in connection with fig. 8-11.

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

Thus, the foregoing has described an MRF joystick system that includes one or more joysticks biased toward a joystick return position (which may be adjusted to operator preferences). While the foregoing description has focused primarily on a particular type of work vehicle (excavator) that includes particular work vehicle functions (boom-arm movements) controlled via a joystick, embodiments of the MRF joystick system are suitable for integration into a wide range of work vehicles that include a joystick device for controlling the changed work vehicle functions. Referring now to fig. 7, the upper left portion of fig. 7 illustrates an example work vehicle, the middle portion illustrates an example MRF joystick arrangement, the right portion illustrates controlled work vehicle functions, and the lower portion of fig. 7 illustrates other example work vehicles potentially equipped with MRF joystick arrangements. Specifically, three additional examples of such work vehicles are set forth in the upper portion of fig. 7 and include a wheel loader 226, a Skid Steer Loader (SSL)228, and a motor grader 230. First with respect to the wheel loader 226, the wheel loader 226 may be equipped with an example MRF joystick device 232 disposed within a cab 234 of the wheel loader 226. As indicated in FIG. 7, MRF joystick device 232 may be used to control the movement of FEL 236, which is terminated to bucket 238. In comparison, two MRF joystick devices 240 may be placed in the cab 242 of the example SSL 228 and used to control not only the movement of the FEL 244 and its bucket 246, but also to further control the movement of the chassis 248 of the SSL 228 in a known manner. Finally, motor grader 230 also includes two MRF joystick devices 240 disposed within a cab 252 of motor grader 230. The MRF joystick device 250 may be used to control movement of the motor grader chassis 254 (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), and movement of the blade 256 of the grader (e.g., by rotation and angular adjustment of the blade-circle assembly 258, and adjustment of the side-shift angle of the blade 256).

Any or all of the example wheel loader 226, SSL 228, and motor grader 230 may be equipped with a work vehicle MRF joystick system of the type described herein, i.e., an MRF joystick system that includes at least one joystick device having a joystick biased toward a joystick return position, an MRF joystick resistance mechanism, a JRP lock mechanism, and a controller architecture coupled to the MRF joystick resistance mechanism and the JRP lock mechanism. In addition, the controller architecture may selectively enable operator adjustment of the return position of the joystick. To enable operator JRP adjustment, the controller architecture may issue a command to unlock the JRP locking mechanism (if applicable) while also issuing a command to the MRF lever resistance mechanism to apply MRF resistance at a predetermined level until the JRP adjustment process is complete. In embodiments where the JRP locking mechanism 70 is external to the base housing 62 to prevent (or at least substantially inhibit) rotation of the joystick 60 relative to the base housing 62 during the JRP adjustment process, the controller architecture 50 may command the MRF joystick resistance mechanism 56 to generate the maximum MRF resistance. In contrast, in embodiments where the JRP locking mechanism is located inside the base housing, the controller architecture 50 may instead command the MRF joystick resistance mechanism 56 to apply a smaller (e.g., minimum or zero) MRF resistance during the JRP adjustment process, as discussed further below in connection with fig. 9-11. The lower portion of fig. 7 illustrates a further example of a work vehicle usefully equipped with an embodiment of the MRF joystick system, and includes a FEL-equipped tractor 260, a feller stacker 262, a skidder 264, a combine 266, and a bulldozer 268.

Example MRF joystick System including JRP locking mechanism inside base housing of MRF joystick device

Next, proceeding to fig. 8 and 9, a simplified cross-sectional view of a MRF joystick device 270 is shown, as depicted in accordance with another example embodiment of the present disclosure. In many respects, the MRF lever device 270 is similar to the MRF lever device 52 shown in fig. 1-6, and the cross-sections of fig. 8 and 9 generally correspond to the cross-sections of fig. 3 and 4, respectively. The reference numerals have been reversed as appropriate and, to avoid redundancy, the common components shared by the MRF joystick device 270 (fig. 8 and 9) and the MRF joystick device 52 (fig. 3 and 4) described above have not been discussed in detail again. As with the MRF joystick device 52 (fig. 3 and 4) previously described, the MRF joystick system 270 includes a JRP lock mechanism 272 that is movable between a locked state and an unlocked state. However, in the case of the MRF joystick device 270, the JRP locking mechanism 272 is integrated into (disposed within) the base housing 62 of the joystick device 270. Two biasing members 284 are also provided within the base housing 62 of the MRF joystick device 270 and cooperate to bias the joystick 60 toward the joystick return position. In this example, the biasing member 284 takes the form of a mechanical (e.g., wire-like) spring, and is therefore hereinafter referred to as "biasing spring 284". However, in other embodiments, the biasing member 284 may take other forms adapted to apply a biasing force that urges the lever 60 to rotate toward the lever return position as the lever 60 is moved from the lever return position. Examples of other types of biasing components suitable for use within the MRF joystick device 270 include: gas springs, mechanical springs, and magnetic components.

Although contained within the base housing 62 in the illustrated embodiment, the JRP locking mechanism 272 of the MRF joystick device 270 is similar in several respects to the external JRP locking mechanism described above in connection with fig. 5 and 6. JRP locking mechanism 272 includes two

hydraulic cylinders

274, 276 and one or more shut-off valves 278 fluidly interconnected with

hydraulic cylinders

274, 276 via flow line connections 280. In this particular example, the stop valves 278 are illustrated generally as MRF valves, each having a configuration similar to the MRF valve 56 that is also contained in the base housing 62 and is used to selectively apply MRF resistance that inhibits movement of the joystick. An electrical connection 282 is provided from the power supply 177 to the shut-off valve 278 and the controller architecture 50 adjusts the supply of power to the shut-off valve 278 by modification of the current or voltage applied to the EM coil within the valve 278 to provide the desired flow control function. Again, in alternative embodiments, shut-off valve 278 may be readily implemented as a non-MRF valve that includes a valve member, such as a plug, spool, or plate, that is positioned with a solenoid or other electrical actuator by controller architecture 50. The

hydraulic cylinders

274, 276 of the MRF joystick device 270 are also similar to the

hydraulic cylinders

204, 206 included in the MRF joystick device 52, as described above in connection with fig. 6; however, in this example, the

hydraulic cylinders

274, 276 are increasingly compact and are integrated into the base housing 62 of the MRF joystick device 270. Additionally, in the example of fig. 8 and 9, the

hydraulic cylinders

274, 276 effectively serve as adjustable spring seats that set the lever return position of the MRF lever device 270 by a change in the position of a biasing spring 284 acting on the lever 60, as discussed further below.

As mentioned above, in the illustrated example, the JRP locking mechanism 272 includes two

hydraulic cylinders

274, 276 and two biasing springs 284. In other embodiments, the JRP locking mechanism 272 may include a greater or lesser number of hydraulic cylinders and biasing springs, depending on the joystick device design and the manner in which the joystick may be moved relative to the base housing 62; for example, in implementations where the joystick 60 may be rotated about a single axis or otherwise moved in a single DOF, the JRP locking mechanism 272 may include a single spring-cylinder pair, perhaps two spring-cylinder pairs disposed on opposite sides of the joystick 60. Both

cylinders

274, 276 in turn include a cylinder 274 and a translating piston 276, the end of which is slidably disposed within a bore (bore) of the cylinder 274. The outer end (outer terminal) end of each cylinder 274 (the rightmost end of the cylinder 274 in the orientation shown in fig. 8 and 9) is mounted to an internal base structural feature 286 of the base housing 62. This mounting is accomplished with a movable coupling, such as a ball joint 288, permitting the

cylinders

274, 276 to tilt or swivel (swivel) in conjunction with operator rotation of the joystick 60 and deflection of the biasing spring 284. The opposite ends of

hydraulic cylinders

274, 276, and in particular the outer end (rod) end of each piston 276, serve as spring seats that support at least one of biasing springs 284. The piston 276 may terminate in a spring retainer or spring seat 290 that secures the biasing spring 284 to the outer end of the piston. As shown, the opposite end of biasing spring 284 is engaged to the lower portion of lever 60 and is specifically secured to lower lever extension 120.

By virtue of the structural configuration described above, each biasing spring 284 may be compressed or extended to apply a biasing force that urges the lever 60 back toward the lever return position. With respect to the biasing spring 284 shown in FIG. 8, in particular, the biasing spring stretches and compresses in conjunction with the rotation of the joystick about the X-axis of the coordinate legend 118. Starting from the joystick return position shown in fig. 8, rotation of the joystick handle 110 in the leftward direction will cause the lower joystick extension 120 to move in the rightward direction, thereby urging the biasing spring 284 against the spring seat 290. Under this compression, biasing spring 284 exerts a pushing force on the lower portion or extension 120 of lever 60 to urge lever 60 back toward the lever return position. Conversely, rotation of the joystick handle 110 in the right direction will cause the lower joystick extension 120 to move in the left direction, thereby stretching the biasing spring 284. Thus, in this condition, the biasing spring 284 exerts a pulling force on the lower extension 120 of the lever 60 to again urge the lever 60 back toward the lever return position. In a similar manner, the biasing spring 284 shown in FIG. 9 extends and retracts in conjunction with the rotation of the joystick about the Y-axis of the coordinate legend 118 to further bias the joystick 60 toward the joystick return position. Then, in essence, the lever return position is the angular position at which the net spring force exerted on the lever 60 becomes balanced; and in the illustrated example is where each of the biasing springs 284 typically reside in a non-deflected state and exert little or no spring force on the lower lever extension 120. Thus, the translational movement of the piston end 276 and the spring seat 290 adjusts the angular position of the lever 60 at which the biasing spring 284 resides in its undeflected state, and thus adjusts the lever return position toward which the biasing spring 284 urges the lever 60 to rotate.

Operator adjustment of the joystick return position of the MRF joystick device 270 may be accomplished as follows. First, the operator provides some form of input (as received through the controller architecture 50) to initiate the JRP adjustment process. As mentioned above in connection with the MRF joystick device 52, operator input may be provided through physical interaction with manual inputs provided on the joystick 60 or on the base housing 62; or alternatively via operator interaction with a GUI generated on the screen of the display device 80. In response to such operator input, the controller architecture 50 unlocks the JRP locking mechanism 272 to permit operator adjustment of the joystick return position. In the embodiment of fig. 8 and 9, the controller architecture 50 unlocks the JRP locking mechanism 272 by issuing a command to the shut-off valve 278 to temporarily permit fluid flow between the opposing chambers of the

cylinders

274, 276, as previously described. This enables the piston 276 and spring seat 290 of each

cylinder

274, 276 to translate autonomously in conjunction with operator-induced rotation of the joystick 60. Thus, a work vehicle operator may grasp the joystick handle 110 and rotate the joystick 60 to any selected joystick return position permitted within the physical limits of the MRF joystick device 270. As the operator moves the lever 60 in this manner, the biasing spring 284 deflects to exert a force on the piston 276 associated with the biasing spring and then translates the piston to a new position, thereby zeroing out the spring force generated by the operator movement of the lever 60 during JRP adjustment.

After adjusting the joystick 60 to the desired joystick return position, the operator then inputs additional inputs into the MRF joystick system 270 to terminate the JRP adjustment process. Upon receiving this input, the controller architecture 50 issues a command to the JRP locking mechanism 272 to revert to the locked state in which the JRP locking mechanism 272 normally resides during use of the MRF joystick device 270. In this example, the controller architecture 50 issues a command to the shut-off valve 278 to again close or otherwise prevent fluid flow between the chambers of the cylinders contained in the MRF joystick device 270; for example, when the shut-off valve 278 is an MRF valve, as shown, the controller architecture 50 energizes the EM coil contained in the MRF valve 278 sufficiently to prevent, or at least significantly impede, the flow of magnetorheological fluid through the valve 278. The piston 276 and corresponding spring seat 290 are thus fixed in their current translational positions, thereby placing the biasing spring 284 to reside in a substantially undeflected state at the new operator-adjusted joystick return position. Supported in this manner by the piston 276, the biasing spring 284 within the MRF lever device 270 now biases the lever 60 of the MRF lever device 270 to the operator-adjusted lever return position. The operator may then return to normal use of the MRF joystick device 270 until the JRP adjustment process is again initiated.

In the manner described above, work vehicle MRF joystick system 22 enables operator adjustment of the joystick return position for a given MRF joystick device (here, MRF joystick device 270) using a highly intuitive manual drive procedure during which the operator rotates the joystick (e.g., joystick 60) to a desired joystick return position. By enabling the operator to physically move the joystick handle 110 to the desired JRP position, an intuitive JRP position adjustment process is established during which the operator can typically relax the operator's arms and wrists to gradually move the joystick to the JRP position that best suits the unique physiology of the operator. In addition, such manually driven adjustment procedures typically enable elimination of linear or rotary actuators in achieving the desired JRP position adjustment. As a result, the overall cost and complexity of the MRF joystick system may be reduced.

In embodiments where the JRP locking mechanism is located outside of the base housing, including in the example embodiments shown in fig. 8 and 9, it may be desirable to adjust the position that generates some MRF effect when the operator-adjusted joystick return position is displaced from a default or unmodified joystick return position. For example, when a hold or a tactile MRF stop is desirably generated during joystick operation, it may be desirable to adjust the position at which the MRF stop is generated in conjunction with operator adjustment of the joystick return position. Additionally or alternatively, MRF motion stops may be generated at certain positions to compensate for asymmetries in the joystick ROM that would otherwise result from displacement of the joystick return position relative to a default, unmodified, or "true center" position. Further description in this regard will now be provided in connection with fig. 10 and 11; it is also noted that in other embodiments, such position adjustment may not be possible in the position where the MRF effect is generated, particularly in many cases the angular deviation between the operator-adjusted joystick return position and the default joystick return position is typically relatively small.

Fig. 10 and 11 schematically illustrate example ways in which the positioning of certain MRF resistance effects may be modified in conjunction with adjustment of the joystick resistance position. Referring initially to fig. 10, a schematic diagram 292 illustrates a default joystick ROM 294 of an example MRF joystick device (e.g., joystick device 270 shown in fig. 8 and 9) when the joystick return position resides in a default or unadjusted position (as indicated at reference 296). A legend 298 identifies different cross-hatched patterns of the default joystick ROM 294 and the default joystick return position 296, as well as example default positioning of the two MRF stops 300, 302. From the default joystick return position 296, the operator may rotate the joystick in any given

direction

304, 306, 308, 310 about the X-axis or Y-axis of the coordinate legend 118. When the joystick is rotated in the direction 306 (to the operator's right) to the detent position 300, the controller architecture 50 issues a command to the MRF joystick resistance mechanism 56 to generate an increased MRF resistance that inhibits further rotation of the joystick in the right direction 304 to generate the desired MRF detent effect. Similarly, when the joystick is rotated in the direction 308 (to the left of the operator) to the detent position 300, the controller architecture 50 issues a command to the MRF joystick resistance mechanism 56 to generate an increased MRF resistance that inhibits further rotation of the joystick to generate the desired MRF detent effect. Due to the physical limitations of the MRF joystick device itself, the joystick typically cannot be rotated beyond the outer periphery 312 of the default joystick ROM 294.

Turning to fig. 11, an example scenario (diagram 317) is shown following an operational adjustment of the joystick return position from the default position (reference 296) to the most recently selected joystick return position 314. As shown in the legend 316, the controller architecture 50 of the MRF joystick system may perform either or both functions to modify the operation of the MRF joystick in accordance with operator adjustments to the joystick return position. First, the controller architecture 50 may generate an MRF motion stop to strategically limit the joystick ROM, as indicated by the circled graphic 318 in fig. 11 (hereinafter referred to as "modified ROM 318"). When the joystick is rotated in the right direction 306 from the modified joystick return position (marker 314), the controller architecture 50 may issue a command to the MRF joystick resistance mechanism 56 to generate the MRF joystick stop 318 at an end position corresponding to the outer periphery 322 of the modified ROM 318. This equates the ROM or stroke of the joystick when rotated from the modified joystick return position in the right direction 306 about the X axis of the coordinate legend 118 to the joystick stroke when rotated from the modified joystick return position in the left direction 310 about the X axis of the coordinate legend 118. Without generating the MRF movement stop 318, the joystick may be rotated in the right direction 306 to the outer periphery 312 of the default ROM, resulting in a longer joystick stroke in the right direction 306 than in the left direction 310. Thus, by generating the MRF joystick stop 318 encountered when the joystick is rotated in the right direction 306, symmetry of joystick rotation about the X-axis of the coordinate legend 118 is maintained as opposed to the operator adjusted joystick return position (label 314).

In a similar regard, when the joystick is rotated in a downward direction 308 (toward the operator) from the modified joystick return position (marker 314) about the Y-axis of the coordinate legend 118, the controller architecture 50 may generate a second MRF motion stop 320 at an appropriate position to further balance the angle ROM of the joystick about that axis. Without generating the MRF motion stop 320, the operator may potentially rotate the joystick in the downward direction 308 to the outer periphery 312 of the default ROM, again resulting in rotational asymmetry relative to the modified joystick return position (marker 314). The symmetry of the joystick ROM as the joystick is rotated about the Y-axis of the coordinate legend 118 is restored by creating an MRF joystick stop 318 that prevents over-travel of the joystick as the joystick is rotated in the downward direction 308. Similar MRF motion stops may also be generated along the following portions of the outer periphery 322 of the modified or constrained joystick ROM 318: this portion is not aligned with the outer perimeter 312 of the default joystick ROM 294. In this manner, the controller architecture 50 utilizes the MRF capability of the MRF joystick device to impose an artificial limit on the joystick travel to maintain the symmetry of the joystick ROM in a direction opposite the displacement of the modified joystick return position (reference 314) relative to the default joystick return position (reference 296). The joystick ROM remains constrained by the physical limitations of the MRF joystick device in the direction corresponding to the displacement of the modified joystick return position (marker 314) relative to the default joystick return position (marker 296). In other embodiments, such MRF motion stops 319, 320 may not be generated.

Likewise, in at least some implementations, the position at the MRF stops 300, 302 may be adjusted in conjunction with operator adjustment of the joystick return position (reference 314). As the joystick return position shifts in a particular manner (in the up and left directions in the example of fig. 11) as a result of operator adjustment, the position at the MRF stops 300, 302 may shift in a corresponding manner. Additionally, the position at which the MRF stops 300, 302 are generated can be adjusted to accommodate any truncation of the joystick ROM when rotated about a particular axis that desirably applies one or more MRF motion stops. To determine a suitably modified position that generates such MRF effect after operator adjustment of the joystick return position, the controller architecture 50 tracks the joystick movement during the operator JRP adjustment procedure described above, and stores the position of the operator-adjusted joystick return position at the end of the JRP adjustment procedure; for example, the operator adjusted joystick return position may be stored as coordinates, or as an angular offset from a default joystick return position. The controller architecture 50 then considers the modified position of the joystick return position (marker 314) along with the relevant data (e.g., data indicative of a default ROM of the joystick, such as a default angular range over which the joystick may be rotated about a given axis from the default joystick return position (marker 296)) to determine the appropriate position to generate any MRF stops (e.g., MRF stops 300, 302) and any MRF motion stops (e.g., MRF motion stops 319, 320) as desired.

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 for use on a work vehicle is provided. The work vehicle MRF joystick system includes a joystick device having a base housing and a joystick rotatable relative to the base housing and biased toward a joystick return position. The MRF joystick resistance mechanism may be controlled to vary the MRF resistance resisting movement of the joystick relative to the base housing. The controller architecture is coupled to the MRF joystick resistance mechanism and configured to: (i) selectively initiating, by a work vehicle operator, an operator adjustment of the joystick return position; and (ii) when operator adjustment of the joystick return position is initiated, issuing a command to the MRF joystick resistance mechanism to maintain the MRF resistance at a predetermined level until operator adjustment of the joystick return position is terminated.

2. The work vehicle MRF joystick system of example 1, further comprising a JRP lock mechanism movable between: an unlocked state in which the JRP locking mechanism permits adjustment of the joystick return position; and a locked state in which the JRP locking mechanism prevents adjustment of the lever return position.

3. The work vehicle MRF joystick system of example 2, wherein the JRP locking mechanism is external to the base housing; while the controller architecture is configured to maintain the MRF resistance substantially at a maximum level until termination of the operator adjustment of the joystick return position.

4. The work vehicle MRF joystick system of example 2, wherein the JRP locking mechanism is internal to the base housing; while the controller architecture is configured to maintain the MRF resistance at a minimum level until operator adjustment of the joystick return position is terminated.

5. The work vehicle MRF joystick system of example 2, wherein the controller architecture is coupled to the JRP locking mechanism and is further configured to: (i) commanding the JRP locking mechanism to move to the unlocked state upon receiving an operator adjustment of the joystick return position; and (ii) upon termination of operator adjustment of the joystick return position, returning the JRP locking mechanism to the locked state.

6. The work vehicle MRF joystick system of example 2, further comprising a support structure adjacent the base housing, and a coupler joining the base housing to the support structure. The JRP locking mechanism is coupled between the support structure and the base shell. The coupler enables the base shell to rotate in at least one degree of freedom relative to the support structure when the JRP locking mechanism is in the unlocked state.

7. The work vehicle MRF joystick system of example 2, wherein the JRP locking mechanism includes a hydraulic cylinder having opposing hydraulic chambers. Fluidly coupling a shutoff valve between the opposing hydraulic chambers and operatively coupled to the controller architecture. The shut-off valve is controllable to selectively prevent fluid flow between the opposing hydraulic chambers to lock the hydraulic cylinder in a translational position.

8. The work vehicle MRF joystick system of example 7, wherein the hydraulic cylinder is mechanically coupled between the base housing and a lower portion of the joystick.

9. The work vehicle MRF joystick system of example 7, further comprising a support structure to which the base housing is movably mounted. The hydraulic cylinder is mechanically coupled between the base shell and a support structure.

10. The work vehicle MRF joystick system of example 7, wherein the stop valve comprises an MRF valve selectively energized by the controller architecture to substantially prevent MRF fluid flow through the MRF valve when the JRP locking mechanism is in the locked state.

11. The work vehicle MRF joystick system of example 1, further comprising a computer readable memory coupled to the controller architecture. The controller architecture is configured to store, in the computer-readable memory, JRP setting data following adjustment of the joystick return position by the work vehicle operator, wherein the JRP setting data describes an operator-adjusted joystick return position of the joystick device.

12. The work vehicle MRF joystick system of example 11, wherein the controller architecture is further configured to: (i) selectively generating an MRF resistance effect at a predetermined position encountered when rotating the joystick about an axis of rotation, the MRF resistance effect taking the form of an MRF stop and an MRF motion stop; and (ii) adjust the predetermined position that generates the MRF resistance effect when the operator adjustment of the joystick return position deviates from a default joystick return position.

13. The work vehicle MRF joystick system of example 12, wherein the MRF resistance effect takes the form of an MRF motion stop. The controller architecture is configured to generate the MRF motion stops at: substantially equalizing the first ROM of the joystick with the second ROM of the joystick at the location. The first ROM is measured as the joystick is rotated in a first direction about the axis of rotation from the operator adjusted joystick return position; while the second ROM is measured as the joystick is rotated about the axis of rotation in a second direction from the operator adjusted joystick return position, the second direction being opposite the first direction.

14. In other embodiments, the work vehicle MRF joystick system includes a joystick device having a base housing and a joystick rotatable relative to the base housing and biased toward a joystick return position. The work vehicle MRF joystick system further comprises: a MRF joystick resistance mechanism controllable to vary a MRF resistance resisting movement of the joystick relative to the base housing; a JRP locking mechanism external to the base housing; and a controller architecture coupled to the MRF joystick resistance mechanism and the JRP locking mechanism. The JRP locking mechanism is movable between a locked state preventing adjustment of the lever return position and an unlocked state permitting adjustment of the lever return position. The controller architecture is configured to: (i) issuing a command to the MRF joystick resistance mechanism to generate a maximum MRF resistance that substantially prevents movement of the joystick relative to the base housing when an operator adjustment of the joystick return position is received; and (ii) when operator adjustment of the joystick return position is terminated, issuing a command to the MRF joystick resistance mechanism to remove the maximum MRF resistance.

15. The work vehicle MRF joystick system of example 14, wherein the controller architecture is coupled to the JRP locking mechanism and is further configured to: (i) commanding the JRP locking mechanism to move to the unlocked state upon receiving an operator adjustment of the joystick return position; and (ii) upon termination of operator adjustment of the joystick return position, returning the JRP locking mechanism to the locked state.

Conclusion

The foregoing has provided a work vehicle MRF joystick system that includes at least one joystick biased to return to a joystick return position (which may be adjusted to operator preferences). Embodiments of the MRF joystick system enable the joystick return position to be adjusted using an intuitive manual drive procedure in which an operator moves the joystick to a desired joystick return position through physical manipulation of the joystick handle. This manually driven JRP adjustment process not only provides an intuitive mechanism by which the work vehicle operator can adjust the return position of the joystick to best suit the operator's unique physiology, but may also allow for elimination of (or reduced reliance on) actuators that might otherwise be employed to provide actuator driven adjustment of the joystick return position. Embodiments of the MRF joystick system utilize the unique MRF capability of the MRF joystick (or joysticks) included in the joystick system to enable such manually driven JRP adjustment methods; for example, by setting the MRF resistance at a predetermined level (e.g., a minimum or zero level in embodiments where the JRP locking mechanism is inside the base housing, or a maximum level in embodiments where the JRP locking mechanism is outside the base housing) until operator adjustment of the joystick return position is terminated.

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. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. 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 recognize numerous alternatives, modifications, and variations to the described examples. Accordingly, various embodiments and implementations other than the ones 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); and

a lever (60), the lever (60) being rotatable relative to the base housing (62) and biased toward a lever return position;

an MRF joystick resistance mechanism (56), the MRF joystick resistance mechanism (56) controllable to vary an MRF resistance resisting movement of the joystick relative to the base housing (62);

a controller architecture (50), the controller architecture (50) coupled to the MRF joystick resistance mechanism (56), the controller architecture (50) configured to:

operator adjustment to enable a work vehicle operator to selectively initiate the joystick return position; and

when operator adjustment of the joystick return position is initiated, a command is issued to the MRF joystick resistance mechanism (56) to maintain the MRF resistance at a predetermined level until operator adjustment of the joystick return position is terminated.

2. The work vehicle MRF joystick system (22) as set forth in claim 1, said work vehicle MRF joystick system (22) further comprising a joystick return position lock mechanism (70), JRP lock mechanism (70), said JRP lock mechanism (70) being movable between:

an unlocked state in which the JRP locking mechanism (70) permits adjustment of the joystick return position; and

a locked state in which the JRP lock mechanism (70) prevents adjustment of the lever return position.

3. The work vehicle MRF joystick system (22) as set forth in claim 2, wherein said JRP locking mechanism (70) is external to said base housing (62); and is

Wherein the controller architecture (50) is configured to maintain the MRF resistance substantially at a maximum level until termination of an operator adjustment of the joystick return position.

4. The work vehicle MRF joystick system (22) as set forth in claim 2, wherein said JRP locking mechanism (70) is internal to said base housing (62); and is

Wherein the controller architecture (50) is configured to maintain the MRF resistance at a minimum level until termination of the operator adjustment of the joystick return position.

5. The work vehicle MRF joystick system (22) according to claim 2, wherein the controller architecture (50) is coupled to the JRP locking mechanism (70) and is further configured to:

commanding the JRP locking mechanism (70) to move to the unlocked state upon receiving an operator adjustment of a joystick return position; and

upon termination of operator adjustment of the joystick return position, returning the JRP locking mechanism (70) to the locked state.

6. The work vehicle MRF joystick system (22) as set forth in claim 2, said work vehicle MRF joystick system (22) further including:

a support structure (192), the support structure (192) adjacent to the base shell (62), the JRP locking mechanism (70) coupled between the support structure (192) and the base shell (62); and

a coupler (194, 196), the coupler (194, 196) engaging the base shell (62) to the support structure (192) while enabling rotation of the base shell (62) relative to the support structure (192) in at least one degree of freedom when the JRP locking mechanism (70) is in the unlocked state.

7. The work vehicle MRF joystick system (22) as set forth in claim 2, wherein said JRP locking mechanism (70) includes:

a hydraulic cylinder (204, 206, 274, 276), the hydraulic cylinder (204, 206, 274, 276) having opposing hydraulic chambers; and

a shutoff valve (208, 278), the shutoff valve (208, 278) fluidly coupled between the opposing hydraulic chambers and operatively coupled to the controller architecture (50), the shutoff valve (208, 278) controllable to selectively prevent fluid flow between the opposing hydraulic chambers to lock the hydraulic cylinder (204, 206, 274, 276) in a translational position.

8. The work vehicle MRF joystick system (22) as set forth in claim 7, wherein said hydraulic cylinder (204, 206, 274, 276) is mechanically coupled between said base housing (62) and a lower portion of said joystick (60).

9. The work vehicle MRF joystick system (22) as set forth in claim 7, further comprising a support structure (192), said base housing (62) movably mounted to said support structure (192), said hydraulic cylinder (204, 206, 274, 276) mechanically coupled between said base housing (62) and support structure (192).

10. The work vehicle MRF joystick system (22) as set forth in claim 7, wherein said stop valve (208, 278) comprises an MRF valve selectively energized by said controller architecture (50) to substantially prevent MRF fluid flow therethrough when said JRP locking mechanism (70) is in said locked state.

11. The work vehicle MRF joystick system (22) as set forth in claim 1, said work vehicle MRF joystick system (22) further comprising a computer readable memory (48), said computer readable memory (48) coupled to said controller architecture (50);

wherein the controller architecture (50) is configured to store, in the computer readable memory (48), JRP setting data (225) following adjustment of the joystick return position by the work vehicle operator, the JRP setting data (225) describing an operator adjusted joystick return position of the joystick device (52, 54).

12. The work vehicle MRF joystick system (22) according to claim 11, wherein the controller architecture (50) is further configured to:

selectively generating an MRF resistance effect at a predetermined position encountered when rotating the joystick about an axis of rotation, the MRF resistance effect comprising one of an MRF stop (302 ) and an MRF movement stop (319, 320); and

adjusting the predetermined position at which the MRF resistance effect is generated when the operator adjustment of the joystick return position deviates from a default joystick return position.

13. The work vehicle MRF joystick system (22) as set forth in claim 12, wherein the MRF resistance effect includes an MRF movement stop; and is

Wherein the controller architecture (50) is configured to generate the MRF motion stops (319, 320) at: substantially equalizing a first range of motion of the joystick, a first ROM, and a second ROM of the joystick at the location;

wherein the first ROM is measured when the joystick is rotated about the axis of rotation in a first direction from the operator-adjusted joystick return position; and is

Wherein the second ROM is measured when the joystick is rotated about the axis of rotation in a second direction from the operator-adjusted joystick return position, the second direction being opposite the first direction.

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

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

a base shell (62); and

a joystick return position lock mechanism (70), or JRP lock mechanism (70), the JRP lock mechanism (70) being external to the base housing (62), the JRP lock mechanism (70) being movable between: a locked state preventing adjustment of the lever return position, and an unlocked state permitting adjustment of the lever return position; and

a controller architecture (50), the controller architecture (50) coupled to the MRF joystick resistance mechanism (56) and the JRP locking mechanism (70), the controller architecture (50) configured to:

issuing a command to the MRF joystick resistance mechanism (56) to generate a maximum MRF resistance that substantially prevents movement of the joystick (60) relative to the base housing (62) when operator adjustment of the joystick return position is received; and

when operator adjustment of the joystick return position is terminated, a command is issued to the MRF joystick resistance mechanism (56) to remove the maximum MRF resistance.

15. The work vehicle MRF joystick system (22) according to claim 14, wherein the controller architecture (50) is coupled to the JRP locking mechanism (70) and is further configured to:

commanding the JRP locking mechanism (70) to move to the unlocked state upon receiving an operator input initiating adjustment of the joystick return position; and

returning the JRP locking mechanism (70) to the locked state when a work vehicle operator completes adjustment of the lever return position.