Magnetorheological fluid joystick system for work vehicles capable of operating in modified centripetal mode

Abstract

The present disclosure relates to a work vehicle magnetorheological fluid joystick system that can operate in a modified centripetal mode. The work vehicle magnetorheological fluid (MRF) joystick system includes: a joystick device, an MRF joystick resistance mechanism, and a controller architecture. The joystick device further includes: a base housing, a joystick movably mounted to the base housing, and a joystick biasing mechanism, which is connected to the joystick and applies a centripetal force to urge the joystick to return to the neutral position when the joystick is moved away from the neutral position. The controller architecture is capable of operating in a modified centripetal mode, wherein the controller architecture: (i) determines when the joystick begins to return toward the neutral position due to the centripetal force applied to the joystick by the joystick biasing mechanism; and (ii) when so determined, issues a command to the MRF joystick resistance mechanism to modify the rate at which the joystick returns to the neutral position by changing the MRF resistance applied to the joystick.

Description

Technical Field

[0001] The present disclosure relates to a work vehicle magnetorheological fluid (MRF) joystick system operable in a modified centering mode; i.e., a mode in which a resistance applied via the MRF is utilized to vary the rate at which a centripetal joystick returns to a centered position after being displaced from the position. Background Art

[0002] Joystick devices are commonly used to control various operational aspects of work vehicles employed in the construction, agriculture, forestry, and mining industries. For example, in the case of a work vehicle equipped with a boom assembly, an operator may utilize one or more joystick devices to control the movement of the boom assembly and, thereby, the movement of a tool or implement mounted to an external terminal end of the boom assembly. Common examples of work vehicles having such joystick-controlled boom assemblies include excavators, feller bunchers, skidders, tractors (to which modular front-end loaders and backhoe attachments may be mounted), tractor loaders, wheel loaders, and various compact loaders. Similarly, in the case of dozers, motor graders, and other work vehicles equipped with an earth-moving blade, an operator may utilize one or more joysticks to control the movement and positioning of the blade. In the case of motor graders, bulldozers, and certain loaders such as skidsteer loaders, joystick devices are also commonly used to steer or otherwise control the directional movement of the work vehicle chassis. Given the prevalence of joystick devices in work vehicles, coupled with the relatively challenging dynamic environments 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 advancements can enhance the safety and efficiency of work vehicle operation. Summary of the Invention

[0003] 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 a joystick arrangement, an MRF joystick resistance mechanism, and a controller architecture coupled to the MRF joystick resistance mechanism. The joystick arrangement further includes a base housing, a joystick mounted to the base housing and movable relative to the base housing via a neutral position, and a joystick biasing mechanism coupled to the joystick and applying a centering force to urge the joystick toward a neutral position when the joystick is moved from the neutral position. The MRF joystick resistance mechanism is controllable to vary an MRF resistance that resists movement of the joystick relative to the base housing along at least one degree of freedom. The controller architecture is capable of operating in a modified centripetal mode, wherein the controller architecture: (i) determines when the joystick begins to return toward a neutral position due to a centripetal force applied to the joystick by a joystick biasing mechanism; and (ii) in response to determining that the joystick begins to return toward a neutral position due to the centripetal force, issues a command to the MRF joystick resistance mechanism to modify the rate at which the joystick returns to the neutral position by changing the MRF resistance applied to the joystick.

[0004] In another embodiment, an MRF joystick system is deployed on a work vehicle equipped with a boom assembly terminated at an implement, the work vehicle MRF joystick system includes a joystick arrangement, an MRF joystick resistance mechanism, and a controller architecture coupled to the MRF joystick resistance mechanism. The joystick arrangement further includes a base housing, a joystick mounted to the base housing and movable relative to the base housing via a neutral position, and a joystick biasing mechanism coupled to the joystick and applying a centripetal force to urge the joystick back toward the neutral position when the joystick is moved from the neutral position. The MRF joystick resistance mechanism is controllable to vary an MRF resistance that resists movement of the joystick relative to the base housing. The controller architecture is configured to determine when a first implement automatic positioning function of the work vehicle has been enabled due to movement of the joystick. Upon determining that the first automatic implement positioning function of the work vehicle has been enabled, the controller architecture further (i) issues a command to the boom assembly to move the implement from a current position to a preset position, and (ii) controls the MRF joystick resistance mechanism to adjust the MRF resistance and vary the rate at which the joystick returns to a neutral position as the implement moves from the current position to the preset position.

[0005] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] At least one example of the present disclosure will be described below with reference to the following drawings:

[0007] Figure 1 is a schematic diagram of an example magnetorheological fluid (MRF) joystick system on a work vehicle (here, a wheel loader) as illustrated according to an example embodiment of the present disclosure, and the MRF joystick system can operate in at least one modified centripetal mode (such as an auto-positioning mirror mode);

[0008] Figure 2 yes Figure 1 A perspective view of a wheel loader is shown illustrating how a front end loader (FEL) bucket of an example wheel loader may be automatically raised to an upper preset position in response to joystick activation of an automatic implement positioning or "kickout" function;

[0009] Figure 3 It is from Figure 1 A perspective view from within the cab of a wheel loader is shown illustrating a joystick arrangement suitably included in an example MRF joystick system and used by an operator to control movement of a FEL in an embodiment;

[0010] Figure 4 is a schematic diagram illustrating the range of motion of an example MRF joystick arrangement and a detent feature to or past which an operator may rotate the joystick to activate the automatic implement positioning function in an embodiment;

[0011] Figure 5 and Figure 6 is a schematic cross-sectional view of an example MRF joystick system, as partially shown and taken along a vertical section through a joystick included in the joystick arrangement, illustrating one possible configuration of the MRF joystick system;

[0012] Figure 7 is a graph illustrating an example timing sequence that illustrates how the MRF joystick system can control the rate at which the joystick returns to neutral to correspond to (e.g., substantially proportional to) the rate at which the FEL bucket moves to a preset position when performing an automatic implement positioning (kickback) function; and

[0013] Figure 8 are diagrams of additional example work vehicles illustrating, by way of non-exhaustive illustration, embodiments in which the MRF joystick system may be advantageously integrated.

[0014] Like reference numerals in the various figures indicate like elements. For simplicity and clarity of illustration, descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the exemplary and non-limiting embodiments of the invention described in the subsequent detailed description. It should also be understood that unless otherwise stated, features or elements appearing in the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0015] Embodiments of the present disclosure are illustrated in the accompanying drawings briefly described above. Various modifications to the exemplary 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.

[0016] As it appears herein, the term "work vehicle" includes all portions of a work vehicle or work machine. Thus, in implementations where a front end loader (FEL) assembly or other boom assembly terminating in an implement is attached to the chassis of the work vehicle, the term "work vehicle" encompasses both the chassis and the boom assembly, as well as the implement or tool mounted to the terminal end of the boom assembly. Additionally, the term "centered position" refers to the home or neutral position to which a centripetal joystick is biased. Thus, it is not necessary in any case to place the center position at the exact geometric center of the joystick's range of motion; for example, in certain embodiments, it may be possible that a joystick of an MRF joystick arrangement can be moved from the center position in a first direction with a range of travel that is greater than the range of travel achievable by the joystick when moved from the center position in a second, opposite direction.

[0017] Overview

[0018] As briefly discussed above, joystick devices are often integrated into various types of work vehicles to provide an intuitive, universal operator interface for controlling a wide range of work vehicle functions. When a biasing device or mechanism that applies a biasing force (herein, a "centering force") to urge the joystick toward a center (neutral) position is included, the joystick device is often referred to as "self-centering." Self-centering joystick devices often include a joystick biasing mechanism in the form of one or more mechanical (e.g., wire-formed or machined) springs, but other joystick biasing mechanisms (including gas springs and magnets) may also be utilized. Relative to non-self-centering joystick devices (such as friction-retained joystick devices), self-centering joystick devices tend to provide the operator with an enhanced interactive experience or "feel," while also giving the operator an intuitive sense of the joystick displacement relative to the center (neutral) position of the joystick at any given moment. This, in turn, can improve operator satisfaction and the effectiveness of performing tasks controlled by the joystick. However, self-centering joystick devices are not without limitations. For example, where certain automated vehicle functions can be enabled by predefined joystick movements, a discrepancy may arise between the joystick movement and the position of the automated movement relative to the work vehicle function triggered by the joystick movement, as discussed further below. Additionally, self-centrifugal joystick devices typically provide a return-to-center (RTC) rate determined solely by the centripetal force and any friction losses within the joystick device itself. Consequently, self-centrifugal joystick devices typically cannot provide controlled variations in the RTC rate to, for example, better accommodate operator preferences, changes in the work vehicle's operating mode, or changes in other conditions associated with the work vehicle's operation.

[0019] As alluded to above, electronic joysticks, such as electrohydraulic (EH) joysticks, can be designed to enable certain work vehicle functions via movement of the joystick. One such function that is well suited for being enabled by certain predefined movements of the joystick, in accordance with embodiments of the present disclosure, is an implement automatic positioning or "kickout" function. When enabled, this implement automatic positioning function automates the movement of the implement (typically by controlling the movement of the FEL assembly or other boom assembly to which the implement is mounted) to transition the implement from its current position to a preset position. This implement automatic positioning function may be useful in the context of various types of work vehicles equipped with movable implements, such as excavators, feller bunchers, and tractors equipped with backhoes or FEL attachments. However, for purposes of explanation, the following description focuses primarily on the example of a loader equipped with a bucket or similar implement (e.g., a skid steer loader or a wheel loader). In the context of such a loader, two implement automatic positioning functions are usefully provided: a first implement automatic positioning function that automatically raises the FEL bucket (or other implement) to an upper preset position, and a second implement automatic positioning function that automatically lowers the FEL bucket to a lower preset position.

[0020] In embodiments of the present disclosure, and continuing with reference to the example loader, an operator can trigger any of these automatic implement positioning or "kickback" functions through predefined joystick movements. As a specific example, the operator can trigger or enable the automatic implement positioning function that raises the FEL bucket to an upper preset position by moving the joystick to or past a first stop feature encountered when the joystick is rotated in a rearward direction away from its neutral position. Conversely, the operator can, when desired, enable the automatic implement positioning function that lowers the FEL bucket to a lower preset position by moving the joystick to or past a second stop feature encountered when the joystick is rotated in a forward direction away from its neutral position. After rotating the joystick to or past one of the stop positions to trigger the corresponding automatic implement positioning function, the operator can then release the centripetal joystick, which then returns to its neutral position under the influence of the centripetal force applied to the joystick by a joystick biasing mechanism incorporated into the joystick arrangement.

[0021] As just described, enabling the selective activation of this automatic implement positioning or "rebound" function through predefined joystick movements can be extremely useful in situations where the operator is required to repeatedly raise and lower the FEL bucket (or other implement) while performing certain work tasks using a loader or other work vehicle. As a more specific example, joystick movement activation of the automatic implement positioning function can be particularly useful when using a loader to fill the dump truck's bed with material collected from a pile (such as dirt or gravel). In this case, the operator can initially set the upper preset position at a height directly above the upper edge or sidewall of the dump truck's bed. After controlling the loader to fill the FEL bucket with material, the operator simply pulls the joystick in a rearward direction, past the encountered stop feature, to activate or trigger the automatic implement positioning function, thereby raising the FEL bucket to the upper preset position. The operator can then release the joystick, causing it to quickly return or "rebound" to the neutral position. At the same time, or shortly thereafter, the operator can maneuver the loader to position the now-raised FEL bucket over the dump truck's bed, then open the FEL bucket to unload the bucket's material load into the dump truck's bed. Next, the operator can direct the loader to remove the FEL bucket from over the dump truck's bed and turn the joystick to activate the automatic implement positioning feature, which lowers the FEL bucket to the lower preset position. This prepares the loader to collect another bucket's worth of material, allowing the operator to repeat the above process steps as needed to efficiently fill the dump truck's bed to the desired capacity. This significantly increases operator convenience by reducing the manual interaction required with the joystick assembly to complete work tasks. Furthermore, thanks to the automatic implement positioning feature, implement movement between the upper and lower preset positions is highly consistent and efficient.

[0022] While benefiting from the reasons outlined above, the automatic implement positioning or "kickback" function provided by the self-centering joystick movement is still associated with certain drawbacks, such as a degree of confusion or concern that can arise for operators unfamiliar with the automatic positioning function. For example, this confusion can arise when an operator inadvertently triggers the automatic implement positioning function and releases the self-centering joystick, which then rapidly returns to a neutral position due to the centripetal force applied to the joystick assembly. As the joystick returns to the neutral position due to the centripetal force, using the loader example again, the FEL assembly continues to move the FEL bucket to the appropriate preset position. Therefore, when the automatic implement positioning function is executed, the relationship between the joystick movement and the FEL assembly movement is temporarily interrupted or severed. Consequently, operators unfamiliar with the automatic implement positioning function may experience discomfort due to the sudden disconnect between the joystick movement and the FEL assembly movement. This is understandable and desirable to avoid whenever possible.

[0023] A magnetorheological fluid (MRF) joystick system for a work vehicle is described below, operable in a modified centripetal mode. This centripetal mode involves controlling or adjusting the rate at which a centripetal joystick returns to a neutral position using an MRF joystick resistance mechanism. When operating in the modified centripetal mode, embodiments of the MRF joystick system utilize MRF technology to modify the return-to-center (RTC) rate of the centripetal joystick relative to the rate at which the joystick would normally return to a neutral position (neutral position) due to a centripetal force applied by a joystick biasing mechanism (e.g., one or more springs, magnets, etc.) integrated into the joystick assembly. In embodiments, the MRF joystick system can modify the RTC rate of the joystick based on the current operating mode of the work vehicle, the current load of the work vehicle, the current speed of the work vehicle, or another sensed parameter associated with the work vehicle. Additionally or alternatively, embodiments of the work vehicle MRF joystick system may enable the operator to modify the rate at which the joystick returns to neutral, according to operator preference settings.Other modified centripetal modes are also possible, as will become apparent from the following description.

[0024] A modified centripetal mode, which is particularly useful in the context of loaders and other work vehicles that are endowed with an implement auto-positioning function triggered by joystick movement, is hereinafter referred to as "auto-positioning mirror mode." The MRF joystick system can enter this auto-positioning mirror mode in conjunction with enabling the implement auto-positioning function through movement of the MRF joystick device. Subsequently, when operating in auto-positioning mirror mode, the MRF joystick system can change the RTC rate of the joystick to correspond to (e.g., approximately proportional to) the rate at which the implement (such as an FEL bucket) moves to a preset position following the enabling of a given implement auto-positioning or kickback function. In doing so, the MRF joystick system maintains an improved correlation between joystick movement and implement movement during execution of the implement auto-positioning function. This, in turn, enables closer coordination of machine performance with the operator's expectations. Further benefits can be achieved through the use of MRF technology itself, as compared to the use of other mechanisms (such as actuated friction or brake mechanisms), which can also selectively resist joystick movement as the joystick returns to the neutral position after being displaced from the neutral position. Such benefits can include: highly shortened response time; minimal friction losses in the absence of resistance applied by the MRF; and reliable, substantially noiseless operation; as well as other benefits as further discussed below. In addition, embodiments of the MRF joystick resistance mechanism described below can generate a continuous range of resistance within a resistance range in a relatively precise manner and based on commands or control signals issued by a processing subsystem or "controller architecture" of the MRF joystick system, as further described herein. This, in turn, can enable the detent features of the MRF joystick device to be selectively added, removed, repositioned, and adjusted in force (e.g., to meet operator preferences) during operation of the work vehicle MRF joystick system.

[0025] Now, combine Figures 1 to 7to describe example embodiments of an MRF joystick system for a work vehicle. In the example embodiments described below, the MRF joystick system is primarily discussed in the context of a particular type of work vehicle, namely a wheel loader equipped with a FEL bucket. Additionally, in the examples below, the MRF joystick system includes a single joystick device comprising a joystick capable of rotating about two perpendicular axes. Despite the following examples, in further embodiments, the MRF joystick system may include a greater number of joystick devices (e.g., two or more joystick devices), and each joystick device may move with any number of degrees of freedom (DOF) and along any suitable motion pattern; 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 or plus-shaped) trajectory or motion pattern. Furthermore, the MRF joystick system described below may be deployed on a wide range of work vehicles that include joystick-controlled functionality and are employed in agriculture, construction, mining, and forestry, as discussed below in conjunction with Figure 8 Additional examples of the work vehicles are discussed.

[0026] Example MRF joystick system operable in modified centripetal mode

[0027] Initial Return Figure 1 and Figure 2 , which presents an example work vehicle (here, a wheel loader 20) equipped with a work vehicle MRF joystick system 22. In addition to the MRF joystick system 22, the wheel loader 20 also includes a FEL assembly 24 terminating in a tool or implement (such as a FEL bucket 26). In embodiments, various other implements (such as other types of FEL buckets) can be interchangeable with the FEL bucket 26. The following description is equally applicable to other types of work vehicles equipped with boom-mounted implements, including excavators, feller bunchers, and tractors equipped with FEL attachments or backhoe attachments, regardless of the specific tool or implement mounted to the terminal end of the boom assembly. The wheel loader 20 has a main body or chassis 28, a cab 30 located at the front of the main chassis 28 and surrounding an operator's station, and ground-engaging wheels 32 supporting the main chassis 28. In this particular example, the wheel loader 20 has an articulated body such that a front portion or frame 34 of the loader 20 can be pivoted relative to the main chassis 28 about an axis 36 ( Figure 1 )Rotate.

[0028] The FEL assembly 24 of the wheel loader 20 includes twin booms or lift arms 38 that extend from the main chassis 28 in a forward direction to the rear side of the FEL bucket 26. At one end, each lift arm 38 is coupled to the front frame 34 of the wheel loader via a first pin or pivot joint 40. At the longitudinally opposite end, each lift arm 38 is coupled to the FEL bucket 26 via a second pin or pivot joint 42. Figure 2 As best shown in FIG. , two lift arm cylinders 44 are also mounted between the front frame 34 and the lift arms 38 of the wheel loader 20. Extension of the lift arm cylinders 44 thus causes the lift arms 38 to rotate about the pivot joint 40 and the FEL bucket 26 to move upward. The wheel loader 20 also includes a bucket cylinder 46 mechanically coupled between the front frame 34 and a linkage 48. The central portion of the linkage 48 is again rotationally or pivotally mounted between the lift arms 38, while the ends of the linkage are pivotally coupled to the FEL bucket 26 opposite the bucket cylinders 46. The linkage 48 may be a four-bar linkage, a Z-linkage, or a similar linkage suitable for converting translation of the bucket cylinders 46 into rotation (curling or uncurling) of the FEL bucket 26.

[0029] The hydraulic cylinders 44, 46 are included in an electro-hydraulic (EH) actuation system which is Figure 1 The movement of the FEL assembly is controlled by a joystick located in the loader cab 30 and included in the MRF joystick system 22. Specifically, and as shown in FIG. Figure 1 As schematically illustrated in the upper left portion of FIG, an operator can utilize an MRF joystick 54 included in the MRF joystick system 22 to control the extension and retraction of the hydraulic cylinders 44 and 46. The depicted EH actuation system 50 also includes various other hydraulic components, not illustrated, which may include flow lines (e.g., flexible hoses), check or safety valves, pumps, fittings, filters, etc. Additionally, the EH actuation system 50 includes an electrovalve actuator and a flow control valve (such as a spool-type multi-way valve) that can be modulated to adjust the flow of pressurized hydraulic fluid into and out of the hydraulic cylinders 44 and 46. The specific configuration or architecture of the EH actuation system 50 set forth herein is largely unimportant to embodiments of the present disclosure, provided that the controller architecture described below is capable of controlling the movement of the FEL assembly 24 via commands sent to selected ones of the actuators 47 that implement joystick-controlled functions of the wheel loader 20.

[0030] As just mentioned, the work vehicle MRF joystick system 22 includes at least one MRF joystick device 52. As it appears herein, the term "MRF joystick device" refers to an operator input device that includes at least one joystick or control lever that can resist movement by applying a variable resistance using an MRF joystick resistance mechanism of the type described herein. Figure 1 As schematically illustrated in FIG, the MRF joystick assembly 52 includes a joystick 54 mounted to a lower support structure or base housing 56. The joystick 54 is movable relative to the base housing 56 along at least one DOF and is capable of rotating relative to the base housing 56 about one or more axes. In the depicted embodiment, and as indicated by the arrows, the joystick 54 of the MRF joystick assembly 52 is capable of rotating relative to the base housing 56 about two perpendicular axes, and will also be described below. The MRF joystick assembly 52 includes one or more joystick position sensors 60 that are used to monitor the current position and movement of the joystick 54 relative to the base housing 56. Various other components 62 may also be included in the MRF joystick assembly 52, including buttons, dials, switches, or other manual input features, which may be located on the joystick 54 itself, on the base housing 56, or a combination of the two. A spring member (gas spring or mechanical spring), magnet, or fluid damper may be incorporated into the joystick assembly 52 to provide a desired rate of return to the joystick's center position (neutral or home position) and to fine-tune the desired feel of the joystick 54 perceived by the operator when interacting with the MRF joystick assembly 52. ​​The one or more members incorporated into the MRF joystick assembly 52 and exerting a biasing force (referred to herein as a "centripetal force") on the joystick 54 to urge the joystick 54 toward the center position are generally referred to herein as a "joystick biasing mechanism."

[0031] Continue to refer to Figure 1The MRF joystick resistance mechanism 64 is at least partially integrated into the base housing 56 of the MRF joystick assembly 52 or otherwise coupled to the joystick 54. The MRF joystick resistance mechanism 64 can be controlled to adjust the MRF resistance, and therefore the joystick stiffness, to resist movement of the joystick relative to the base housing 56 along at least one degree of freedom (DOF). During operation of the MRF joystick system 22, the controller architecture 66, described below, can selectively issue commands to the MRF joystick resistance mechanism 64 to increase the joystick stiffness or MRF resistance to resist rotation of the joystick about a particular axis or combination of axes. In this regard, when the MRF joystick system 22 is operating in a modified centripetal mode, the controller architecture 66 can issue commands to the MRF joystick resistance mechanism 64 to vary the MRF resistance applied to the joystick 54 to modify the rate at which the joystick returns to a neutral position, as discussed more fully below. This controlled variation of the MRF resistance is achieved by adjusting the strength of the EM field in which the magnetorheological fluid (such as contained in the MRF joystick resistance mechanism 64) is at least partially immersed. Figure 5 and Figure 6 A generalized example of one manner in which the MRF joystick resistance mechanism 64 may be implemented is described below.

[0032] Embodiments of the MRF joystick system 22 also include a controller architecture 66, memory 68 associated with the controller architecture 66, and any number of other non-joystick components 70. Such additional non-joystick components 70 may include an operator interface 72 (distinct from the MRF joystick assembly 52), a display device 74 located in the loader cab 30, and various other non-joystick sensors 76. Specifically, the operator interface 72 may include any number and type of non-joystick input devices for receiving input from an operator of the wheel loader 20, such as buttons, switches, knobs, and similar manual inputs external to the MRF joystick assembly 52. ​​Such input devices included in the operator interface 72 may also include cursor-type input devices, such as a trackball or joystick, for interacting with a graphical user interface (GUI) displayed on the display device 74. The display device 74 may be located within the cab 30 and may take the form of any image-generating device on which visual alerts and other information may be visually presented. The display device 74 may also generate a GUI for receiving operator input, or may include other inputs (e.g., buttons or switches) for receiving operator input that may be associated with the controller architecture 66 when performing the processes described below. In some cases, the display device 74 may have touch input capabilities.

[0033] Finally, the MRF joystick system 22 may include various other non-joystick sensors 76 that provide data inputs to the controller architecture 66 that are utilized in executing the processes described below. For example, in at least some embodiments, the non-joystick sensors 76 may include sensors that automatically determine the type of implement currently attached to the wheel loader 20 (or other work vehicle). This information about the implement type is considered by the controller architecture 66 in determining when to enable the modified centripetal mode. For example, such sensors 76 may determine the specific type of implement currently attached to the wheel loader 20 by sensing a tag (e.g., a radio frequency identification tag) or reading other identifying information present on the implement, by visually analyzing a camera feed capturing the implement, or by utilizing any other technique. Additionally or alternatively, the non-joystick sensors 76 may include sensors for measuring parameters indicative of load at any given point in time, such as the hydraulic pressure within the flow circuit of the EH actuation system 50 or the load carried by the FEL bucket 26. The non-joystick sensors 76 may further provide other data to the controller architecture 66, such as data indicating the current orientation or speed of the wheel loader 20, as determined using, for example, a global positioning system (GPS) module; using a micro-electromechanical system (MEMS) gyroscope, accelerometer, or magnetometer affixed to one or more locations on the wheel loader 20; by measuring the rotational rate of the wheels 32; or in any other manner.

[0034] As in Figure 1As further schematically depicted in FIG, the controller architecture 66 can communicate with the various illustrated components via any number of wired data connections, wireless data connections, or any combination thereof; for example, as generally illustrated, the controller architecture 66 can receive data from the various components via a centralized vehicle or controller area network (CAN) bus 78. As used herein, the term "controller architecture" is utilized in a non-limiting sense to generally refer to the processing subsystem of a work vehicle MRF joystick system, such as the example MRF joystick system 22. Thus, the controller architecture 66 can encompass or 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 66 can include a local controller directly associated with the joystick interface, as well as other controllers located within the operator's station enclosed by the loader cab 30, with the local controller communicating with other controllers on the wheel loader 20 as needed. The controller architecture 66 may also include or cooperate with any number of firmware and software programs or computer-readable instructions designed to perform the various processing tasks, calculations, and control functions described herein. Such computer-readable instructions may be stored in a non-volatile sector of the memory 68 associated with (and accessible to) the controller architecture 66.

[0035] Although Figure 1 6 is generally illustrated as a single box, but the memory 68 of the work vehicle MRF joystick system 22 can encompass any number and type of storage media suitable for storing computer readable code or instructions and other data for supporting the operation of the MRF joystick system 22. In an embodiment, the memory 68 can be integrated into the controller architecture 66, for example, such as a system-in-package, a system-on-chip, or another type of microelectronic package or module. In an embodiment, the memory 68 can also store certain information useful in implementing the modified centripetal mode. As schematically indicated, this can include data 80 defining one or more preset positions of the FEL bucket 26, such as the upper preset position and the lower preset position described below. Additionally or alternatively, the memory 68 can store personalized settings 82 (e.g., the operator's preferred return rate of the joystick 54) when utilizing the MRF joystick system 22 to tune the rate of joystick return to a preference, as further discussed below.

[0036] Now, go to Figure 3, shows a perspective view from inside the loader cab 30, wherein the exterior of the MRF joystick assembly 52 can be seen in greater detail; in particular, the upper portion of the joystick 54. In this example, the MRF joystick assembly 52 is positioned to the right of a steering wheel 84, which is used to steer the wheel loader 20 and can be located directly in front of the operator's seat (not shown). Figure 1 Referring to the reference numerals introduced herein, the MRF joystick assembly 52 includes a joystick 54 mounted to a lower support structure or base housing 56 for rotation about two vertical axes relative to the base housing 56 via a center or neutral position. The joystick assembly 52 also includes a flexible cover or boot 86 connected between a lower portion of the joystick 54 and the fixed base housing 56. Additional joystick inputs are also provided on the joystick 54 in the form of thumb-accessible buttons, as well as other unillustrated manual inputs (e.g., buttons, dials, and / or switches) provided on the base housing 56.

[0037] Different control schemes can be used to convert the movement of the joystick 54 into corresponding movement of the FEL assembly 24. In one common (backhoe) control scheme, the joystick 54 is moved in the rearward direction (corresponding to Figure 3 88 in the figure causes the lift arm cylinder 44 to extend, the front end of the lift arm 38 to rotate upward, and the FEL bucket 26 to be raised. Conversely, movement of the joystick 54 in the forward direction (corresponding to arrow 90) causes the lift arm cylinder 44 to retract, the front end of the lift arm 38 to rotate downward, and the FEL bucket 26 to be lowered. Movement of the joystick to the right (corresponding to arrow 92) causes the bucket cylinder 46 to extend and the FEL bucket to roll inward or "close," while movement of the joystick to the left (corresponding to arrow 94) causes the bucket cylinder 46 to retract and the FEL bucket 26 to extend or "open." Figure 4 Also continuing with joystick arrows 88, 90, 92, 94, the Figure 4 is a schematic diagram illustrating the ROM 96 of an example joystick 54 and certain detent features 98, 100 that may be further encountered during joystick rotation and used to enable the automatic implement positioning function of the wheel loader 20. Specifically, in the illustrated example, the joystick 54 is rotated from Figure 3 and Figure 4 Rotating the joystick 54 in the forward direction from the neutral position shown in FIG. 1 to or past the stop feature 98 triggers the implement automatic positioning or "kickback" function that raises the FEL bucket 26 to the upper preset position. Conversely, rotating the joystick 54 in the rearward direction from the neutral position to or past the stop feature 100 triggers the implement automatic positioning or "kickback" function that lowers the FEL bucket 26 to the lower preset position.

[0038] When the wheel loader 20 is directed to perform certain work tasks such as a filling task during which the FEL bucket 26 is repeatedly moved between two heights; for example, a lower position for collecting bucket loads of material from a pile and an upper position for unloading bucket loads of material into a container. To further illustrate this, Figure 2 The dump truck 108 is depicted being filled with a bucket material load 111, which is delivered to the bucket of the dump truck 108 via the wheel loader 20. Prior to commencing this task, the operator may initially set the upper preset position by interacting with the MRF joystick device 52 and the operator interface 72; for example, the operator may control the MRF joystick device 52 to raise the FEL bucket 26 to a desired position, and then provide additional operator input (e.g., by selecting a button located on the joystick 54 or elsewhere, or by interacting with a GUI generated on the display device 74) to set the current bucket position to the upper preset position (again, stored as part of the preset position data 80 in the memory 68). In the absence of such operator input, the upper preset position may default to the fully raised position of the FEL bucket 26. A similar process may be followed to set the lower preset position of the FEL bucket 26, or the lower preset position of the FEL bucket 26 may be automatically set at or near the ground.

[0039] Ideally, when setting the upper preset position of the FEL bucket 26 before filling the dump truck 108, as shown in FIG. Figure 2 As shown, the operator adjusts the upper preset position according to the horizontal line 106 indicating the ideal upper preset position of the FEL bucket 26 so that the FEL bucket 26 reaches a height above the upper edge or side wall 109 of the dump truck bed. Subsequently, at an appropriate time during the work task (for example, after collecting the material into the FEL bucket 26), the operator can use the MRF joystick device 52 to trigger the automatic positioning function of the machine to move the FEL bucket 26 to the upper preset position. Thereafter, when the FEL bucket 26 is in the state of automatically raising to the upper preset position ( Figure 2), or shortly after the FEL bucket 26 is raised to the upper preset position, the operator can begin directing the wheel loader 20 to position the FEL bucket 26 directly above the dump truck 108's bucket. The operator can then use the MRF joystick device 52 to open or tilt the FEL bucket 26 downward to discharge the collected material 111 into the dump truck bucket. Later, the operator can control the wheel loader 20 to remove the FEL bucket 26 from above the dump truck bucket and simultaneously return the FEL bucket 26 to the lowered "scoop" position, or by triggering the automatic implement positioning function that automatically moves the FEL bucket to the lower preset position, as previously described.

[0040] When an operator unfamiliar with the aforementioned automatic implement positioning functions inadvertently triggers any of the aforementioned functions while interacting with the MRF joystick assembly 52, temporary confusion may occur. A primary cause of this confusion is that the correlation between the joystick movement and the FEL assembly movement is disrupted during the execution of a given automatic implement positioning function. This disruption is evident when the operator moves the joystick 54 to or past one of the detent features 98, 100, releases the joystick 54 (or applies minimal force to the joystick), and the joystick 54 rapidly returns to a center (neutral) position due to the centripetal force applied to the joystick 54 by the joystick biasing mechanism within the MRF joystick assembly 52. To better preserve the relationship between joystick motion and FEL assembly movement during the implement auto-positioning function, thereby reducing the potential for operator confusion in such scenarios, embodiments of the example work vehicle MRF joystick system 22 can be operated in a unique modified centripetal mode in which the resistance applied by the MRF is applied to the joystick 54 in a manner that generally corresponds to (e.g., is approximately proportional to) the rate at which the FEL bucket 26 moves toward a preset position during the execution of the implement auto-positioning function. This type of modified centripetal mode is referred to herein as an "auto-positioning mirror mode" and is described below in conjunction with Figure 7 Furthermore, in addition to or in lieu of this automatic positioning mirror mode, other modified centripetal modes potentially implemented using the work vehicle MRF joystick system 22 are discussed below and may be selectively implemented. However, first, in conjunction with Figure 5 and Figure 6 A description of one possible configuration of the MRF joystick assembly 52 and the MRF joystick resistance mechanism 64 is provided.

[0041] Proceed to Figure 5 and Figure 6, two simplified cross-sectional schematic diagrams illustrate example configurations of an MRF joystick assembly 52 and an MRF joystick resistance mechanism 64. The following description is provided by way of non-limiting example only, noting that many different joystick designs are possible that incorporate or functionally cooperate with the MRF joystick resistance mechanism. The specific composition of the magnetorheological fluid is largely unimportant to the embodiments of the present disclosure, provided that meaningful changes in the rheological properties (viscosity) of the magnetorheological fluid occur in conjunction with controlled changes in EM field strength (as described below). However, for the sake of completeness, it is noted that one magnetorheological fluid composition that is entirely suitable for use in embodiments of the present disclosure comprises magnetically conductive (e.g., carbonyl iron) particles dispersed in a carrier fluid that is primarily composed, by weight, of oil or alcohol (e.g., ethylene glycol). Such magnetically conductive particles can have an average diameter in the micrometer range (or other maximum cross-sectional dimensions if the particles have a non-spherical (e.g., rectangular) shape); for example, in one embodiment, spherical magnetically conductive particles having an average diameter between 1 and 10 micrometers are used. Various other additives, such as dispersants or diluents, may also be included in the magnetorheological fluid to fine-tune its properties.

[0042] Now, refer to Figure 5 and Figure 6 , and again continuing previously introduced reference numerals as appropriate, the MRF joystick device 52 includes a joystick 54 having at least two distinct portions or structural regions: an upper handle 110 (only a simplified lower portion of the upper handle is shown in this figure), and a generally spherical lower base 112 (hereinafter referred to as the "generally spherical base 112"). The generally spherical base 112 of the joystick 54 is captured between two walls 114, 116 of the base shell 56, which may extend generally parallel to each other to form the upper portion of the base shell 56. A vertically aligned central opening is provided through the shell 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 so that the generally spherical base 112 is captured as a whole between the vertically spaced housing walls 114, 116 to form a ball-and-socket type joint. This allows the joystick 54 to rotate relative to the base housing 56 about two vertical axes corresponding to the vertical axes at Figure 5 and Figure 6118 ; while generally preventing translational movement of the joystick 54 along the X-axis, Y-axis, and Z-axis of the coordinate legend 118. In other embodiments, various other mechanical arrangements can be used to mount the joystick to the base housing while allowing the joystick to rotate about two perpendicular axes (such as a universal joint arrangement). In less complex embodiments, a pivot or pin joint can be provided to allow the joystick 54 to rotate about a single axis relative to the base housing 56.

[0043] The joystick 54 of the MRF joystick assembly 52 also includes a stinger or lower joystick extension 120 that projects from the generally spherical base 112 in a direction opposite the joystick grip 110. In the illustrated schematic, the lower joystick extension 120 is coupled to a stationary attachment point on the base housing 56 via a single return spring 124; it is noted that this arrangement is simplified for illustrative purposes, and that actual implementations of the MRF joystick assembly 52 will typically employ a more complex spring return arrangement (or other joystick biasing mechanism, if any). Figure 5 When the middle position (neutral position or home position) shown is shifted, as Figure 6 As shown, the return spring 124 is biased to urge the operating lever 54 to the middle position ( Figure 5 ) returns, so that, as an example, when turning to Figure 6 After the position shown, if the operator of the work vehicle subsequently releases the joystick handle 110, the joystick 54 will return to the position shown under the influence of the return spring 124. Figure 5 In other implementations, the MRF joystick assembly 52 may include different types of joystick biasing mechanisms (such as one or more gas springs, permanent magnets, or electromagnets) that cooperate to provide the desired centripetal force to urge the joystick 54 back to the neutral position when deflected from the neutral position.

[0044] The example MRF joystick resistance mechanism 64 includes Figure 5 and Figure 6 The first MRF cylinder 126 and the second MRF cylinder 128 are shown in FIG. The first MRF cylinder 126 ( Figure 5 ) is mechanically engaged between the lower joystick extension 120 and a partially shown static attachment point or base structural feature 130 of the base shell 56. Similarly, the second MRF cylinder 128 ( Figure 6 ) is mechanically engaged between the lower joystick extension 120 and the static attachment point 132 of the base shell 56, and the MRF cylinder 128 is rotated approximately 90 degrees about the Z axis of the coordinate diagram 118 relative to the MRF cylinder 126. Due to this structural configuration, the MRF cylinder 126 ( Figure 5) can be controlled to selectively resist rotation of the joystick 54 about the X-axis of the coordinate diagram 118, while the MRF cylinder 128 ( Figure 6 ) can be controlled to selectively resist rotation of the joystick 54 about the Y axis of the coordinate diagram 118. In addition, the two MRF cylinders 126, 128 can be controlled together to selectively resist rotation of the joystick 54 about any axis that falls between the X axis and the Y axis and extends in the XY plane. In other embodiments, different MRF cylinder configurations can be utilized and include a greater or fewer number of MRF cylinders; for example, in implementations where it is desired to selectively resist rotation of the joystick 54 only about the X axis or only about the Y axis, or in implementations where the joystick 54 can only rotate about a single axis, a single MRF cylinder or a pair of antagonistic cylinders can be employed. Finally, although not shown in the simplified schematic, in further implementations, the MRF cylinders 126, 128 can include any number of additional groups or can be associated with any number of additional components. Such additional components can include: sensors that monitor the travel of the cylinders 126, 128 (if desired) to, for example, track the joystick position, in place of the joystick sensors 182, 184 described below.

[0045] The MRF cylinders 126, 128 include a cylinder body 134 to which pistons 138, 140 are slidably mounted. Each cylinder body 134 contains a cylindrical cavity or bore 136 in which a head 138 of one of the pistons 138, 140 is mounted for translational movement along the longitudinal axis or centerline of the cylinder body 134. Around the periphery of the cavity or bore, each piston head 138 is fitted with one or more dynamic seals (e.g., O-rings) to sealingly engage the inner surface of the cylinder body 134, thereby dividing the bore 136 into two antagonistic variable-volume hydraulic chambers. The pistons 138, 140 also each include an elongated piston rod 140 that projects from the piston head 138 toward the lower joystick extension 120 of the joystick 54. The piston rod 140 extends through an end cap 142 secured above the open end of the cylinder body 134 (again, engaging any number of seals) to attach to the lower joystick extension 120 at a joystick 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 this mechanical coupling. Opposite the joystick attachment point 144, the opposite ends of the MRF cylinders 126, 128 are mounted to respective static attachment points 130, 132 via ball joints 145. Finally, hydraulic ports 146, 148 are also provided at opposite ends of each MRF cylinder 126, 128 to allow for the inflow and outflow of magnetorheological fluid in conjunction with the translational movement or stroking of the pistons 138, 140 along the respective longitudinal axes of the MRF cylinders 126, 128.

[0046] The MRF cylinders 126, 128 are fluidly interconnected with corresponding MRF valves 150, 152 via flow line connections 172, 180, respectively. As with the MRF cylinders 126, 128, in the illustrated example, the MRF valves 150, 152 are presented as being identical, but may be varied in further implementations. Although referred to in generic terms as "valves" (particularly, considering that the function of the MRF valves 150, 152 is 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 helpful corollary, the MRF valves 150, 152 provide fail-safe operation because, in the unlikely event of an MRF valve failure, magnetorheological fluid is still permitted to pass through the MRF valves 150, 152 with relatively little resistance. Thus, if either or both of the MRF valves 150, 152 fail for any reason, the ability of the MRF joystick resistance mechanism 64 to apply resistance to limit or inhibit joystick movement may be impaired; however, the joystick 54 will be able to freely rotate about the X-axis and Y-axis in a manner similar to a conventional non-MRF joystick system, and the MRF joystick device 52 will generally still be able to control the FEL assembly 24.

[0047] In the depicted embodiment, the MRF valves 150, 152 each include a valve housing 154 containing end caps 156 secured to opposite ends of an elongated cylinder core 158. A generally annular or tubular flow passage 160 extends about the cylinder core 158 and between two fluid ports 162, 164 disposed through the opposing end caps 156. The annular flow passage 160 is surrounded by (and extends through) a plurality of EM induction coils 166 (hereinafter referred to as "EM coils 166") that are wound about a paramagnetic holder 168 and interspersed with a plurality of axially or longitudinally spaced ferrite rings 170. A tubular shroud 172 surrounds the assembly, with a plurality of leads disposed therethrough for electrical interconnection with the housed EM coils 166. Figure 5 and Figure 6Two such leads are schematically represented by lines 174, 176, along with corresponding electrical connections to a power and control source 177. As indicated by arrow 179, the controller architecture 66 is operably coupled to the power and control source 177 in a manner that enables the controller architecture 66 to control the source 177 to vary the current supplied to, or the voltage applied across, the EM coil 166 during operation of the MRF joystick system 22. Thus, this structural arrangement enables the controller architecture 66 to command or control the MRF joystick resistance mechanism 64 to vary the strength of the EM field generated by the EM coil 166. The annular flow channel 160 extends through the EM coil 166 (and may be substantially coaxial therewith) such that, when the magnetorheological fluid is directed through the MRF valves 150, 152, the magnetorheological fluid passes through the center of the EM field.

[0048] 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, through the aforementioned conduits 178, 180. The length of the conduits 178, 180 can be, for example, a flexible tube that ensures sufficient slack to accommodate any movement of the MRF cylinders 126, 128 in conjunction with the rotation of the joystick 54. In this regard, consider Figure 6 In this example, the operator has moved the joystick handle 110 in the operator input direction (indicated by arrow 185), causing the joystick 54 to rotate in a clockwise direction about the Y axis of the coordinate diagram 118. In conjunction with this joystick movement, the MRF cylinder 128 rotates about the ball joint 145 to tilt slightly upward as shown. Furthermore, in conjunction with this operator-controlled joystick movement, the pistons 138, 140 contained in the MRF cylinder 128 retract, causing the piston head 138 to move toward Figure 6 132). The translational movement of the pistons 138, 140 forces the magnetorheological fluid to flow through the MRF valve 152 to accommodate the volume reduction of the chamber to the left of the piston head 138 and the corresponding volume increase of the chamber to the right of the piston head 138. Thus, at any time during such operator-controlled joystick rotation, the controller architecture 66 can change the current supplied to the EM coil 166 or the voltage applied across the EM coil 166 to change the force resisting the magnetorheological fluid flowing through the MRF valve 152 to achieve the desired MRF resistance to further travel changes of the pistons 138, 140.

[0049] Given the responsiveness of the MRF joystick resistance mechanism 64, the controller architecture 66 can control the resistance mechanism 64 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 piston displacement, or providing various other resistance effects (e.g., a tactile detent or pulsating effect), as discussed in detail below. The controller architecture 66 can also control the MRF joystick resistance mechanism 64 to selectively provide resistance effects such as stroke changes of the pistons 138, 140 included in the MRF valve 150 in conjunction with rotation of the joystick 54 about the X-axis of the coordinate diagram 118. Furthermore, the MRF joystick resistance mechanism 64 can independently vary 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 joystick rotation about the X-axis and Y-axis of the coordinate diagram 118.

[0050] 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 54 relative to the base housing 56. In the illustrated example, the MRF joystick device 52 includes: a first joystick position sensor 182 ( Figure 5 and the joystick 54 about the Y-axis rotation of the coordinate diagram 118 monitors the second joystick position sensor 184 ( Figure 6 ). The data connections between the joystick position sensors 182, 184 and the controller architecture 66 are represented by lines 186, 188, respectively. In further implementations, the MRF joystick device 52 may include various other components not illustrated, such as the MRF joystick resistance mechanism 64. Such components may include, as appropriate, operator inputs and corresponding electrical connections provided on the joystick 54 or base housing 56, an AFF motor, and a pressure sensor and / or flow rate sensor included in the flow circuit of the MRF joystick resistance mechanism 64 to best suit a particular application or use.

[0051] As previously emphasized, the above-described embodiments of the MRF joystick device 52 are provided by way of non-limiting example only. In alternative implementations, the configuration of the joystick 54 may vary in various aspects. Given that the MRF joystick resistance mechanism 64 is controllable by the controller architecture 66 to selectively apply resistance (via changes in the rheological properties of the magnetorheological fluid) to inhibit movement of the joystick relative to the base housing along at least one DOF, in further embodiments, the MRF joystick resistance mechanism 64 is also provided relative to the base housing. Figure 5 and Figure 6 . In a further implementation, an EM induction coil similar to or the same as the EM coil 166 may be integrated directly into the MRF cylinders 126, 128 to provide the desired controllable MRF resistance effect. In such an implementation, magnetorheological fluid flow between variable volume chambers within a given MRF cylinder 126, 128 may be permitted via one or more orifices provided through the piston head 138 by providing an annulus or slightly smaller annular gap around the inner surface of the piston head 138 and the cylinder body 134, or by providing a flow passage through the cylinder body 134 or the sleeve itself. Advantageously, such a configuration may provide a relatively compact integrated design for the MRF joystick resistance mechanism. In comparison, in at least some cases, the use of one or more external MRF valves (such as MRF valves 150, 152 ( Figure 5 and Figure 6 )) can facilitate cost-effective manufacturing and allow the use of commercially available modular components.

[0052] In still other implementations, the design of the MRF joystick device can allow the magnetorheological fluid to wrap around and act directly on the lower portion of the joystick 54 itself (such as the spherical base 112 in the case of the joystick 54), and the EM coils can be placed around the lower portion of the joystick and surround the body of magnetorheological fluid. In such an embodiment, the spherical base 112 can be provided with ribs, grooves, or similar topological features to promote displacement of the magnetorheological fluid in conjunction with joystick rotation, where applying power to the EM coil increases the viscosity of the magnetorheological fluid, thereby hindering fluid flow through the restricted flow path provided around the spherical base 112, or can also be due to the magnetorheological fluid being diverted in conjunction with joystick rotation. Various other designs are also possible in further embodiments of the MRF joystick system 22.

[0053] Regardless of the specific design of the MRF joystick resistance mechanism 64, the use of MRF technology to selectively generate variable MRF resistance, or joystick stiffness, that inhibits (resists or prevents) unintended joystick movement offers several advantages. Primarily, the MRF joystick resistance mechanism 64 (and MRF joystick resistance mechanisms generally) is highly responsive to the rheological properties of the magnetorheological fluid, and ultimately the MRF-applied joystick stiffness, in inhibiting joystick movement within a highly shortened time period (e.g., in some cases, a period of approximately 1 millisecond), and can achieve desired changes in EM field strength. Accordingly, the MRF joystick resistance mechanism 64 enables the MRF resistance to be removed (or at least significantly reduced) with equal rapidity by rapidly reducing the current flowing through the EM coil and allowing the rheological properties of the magnetorheological fluid (e.g., fluid viscosity) to return to the magnetorheological fluid's normal, unstimulated state. The controller architecture 66 can also control the MRF joystick resistance mechanism 64 to generate the MRF resistance so as to have a continuous range of strengths or intensities within limits by corresponding variations in the strength of the EM field generated by the EM coil 166. Advantageously, the MRF joystick resistance mechanism 64 can provide reliable, substantially noiseless operation for extended periods of time. Additionally, the magnetorheological fluid can be formulated to be inherently non-toxic, such as when the magnetorheological fluid comprises carbonyl iron-based 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 64 can enable the MRF joystick system 22 to selectively generate a first resistance or joystick stiffness to inhibit movement of the joystick about a first axis (e.g., Figure 5 and Figure 6 The device can selectively generate a second resistance or joystick stiffness that is independent of the first resistance (joystick stiffness) to prevent the joystick from rotating about a second axis (e.g., the Y axis of the coordinate diagram 118); that is, the first resistance and the second resistance can have different values ​​as needed.

[0054] According to an embodiment of the present disclosure, the controller architecture 66 of the work vehicle MRF joystick system 22 can utilize the MRF joystick resistance mechanism 64 to control the RTC rate of the MRF joystick assembly 52 by selectively applying an MRF-applied resistance to the joystick 54 that is coupled to a joystick biasing mechanism (e.g., a lever biasing mechanism) contained within the joystick assembly 52. Figure 5 and Figure 6The controller architecture 66 can also control the MRF joystick resistance mechanism 64 to exert other effects; for example, when the joystick position corresponds to a predetermined stop position (as determined based on the joystick position reported by the joystick position sensor 60), a stopping effect is produced by temporarily increasing the MRF resistance that resists the movement of the joystick. Figure 3 and Figure 4 In the example described, when the operating lever 54 is turned to the position indicated by the stop symbols 98, 100 ( Figure 4 ), the controller architecture 66 can issue a command to the MRF joystick resistance mechanism 64 to temporarily increase the MRF-applied resistance to joystick rotation about axes parallel to arrows 92, 94. This effectively produces the desired stopping effect without otherwise utilizing additional mechanical components or features to provide the stopping effect; however, the possibility that such a stopping feature can be provided without applying MRF-applied resistance in alternative implementations is not excluded.

[0055] In embodiments, using the MRF joystick resistance mechanism 64 to generate detent features for enabling the automatic implement movement function (or more broadly, any work vehicle function that is triggered by a detent) can provide a high level of customization, if desired. For example, in embodiments, a work vehicle operator can interact with the operator interface 72 to adjust the degree or level of resistance encountered when moving through the detent features 98, 100; adjust the positioning of the detent features 98, 100 encountered along the range of joystick travel in directions 88, 90; and / or selectively turn off (deactivate) one or both of the detent features 98, 100, if desired. Similarly, the operator can interact with the operator interface 72 to activate other detents along other axes of rotation (e.g., detents encountered when rotating the joystick 54 in direction 92 or in direction 94), and can also assign such detent features to different work vehicle functions. When the operator adjusts various aspects of the detent feature according to preferences, the operator preferences can be stored in the memory 68 as part of the personalized settings data 82, which can be recalled and implemented upon identification of a registered operator of the wheel loader 20; for example, based on a PIN or other information entered via the operator interface 72 that uniquely identifies the registered operator upon logging into the loader operating system. Thus, the controller architecture 66 can also automatically adjust such detent feature-related parameters or selectively activate the detents in relation to any parameters monitored by sensors of the wheel loader 20 or a particular operating mode of the loader 20, as discussed further below.

[0056] One modified centripetal mode usefully implemented by the controller architecture 66 in conjunction with the activation of the implement auto-positioning or backflush function is the "auto-positioning mirror mode" mentioned above. The controller architecture 66 may automatically enter this auto-positioning mirror mode when the operator activates the implement auto-positioning or "backflush" function via a predetermined movement of the joystick 54. Now, in conjunction with Figure 7 The embodiment of the automatic positioning mirror mode is described. Here, the automatic positioning mirror mode is performed in an example scenario in which the operator rotates the joystick 54 to or through the rear stop feature 100 ( Figure 4 ) to enable raising the FEL bucket 26 to the upper preset position ( Figure 2 ). While the following examples are provided, it is emphasized that the auto-positioning mirror mode can be applied in conjunction with the activation of any implement auto-positioning function (i.e., any function that automatically moves an implement or tool of a work vehicle through three-dimensional space to a preset position) that is triggered by movement of the self-centripetal MRF joystick device. Thus, the auto-positioning mirror mode can also be applied by the controller architecture 66 in conjunction with the activation of the implement auto-positioning function that moves the FEL bucket 26 to the lower preset position, as previously described.

[0057] Go to Figure 7 , shows an example movement timing diagram 190 that indicates one way in which the MRF joystick system 22 can change the RTC rate of the joystick 54 to better correspond to the movement of the implement (here, the FEL bucket 26) during an automatic movement to the upper preset position in response to the operator's activation of the implement automatic positioning function. In this example, the movement of the joystick 54 in the rearward direction from the center position (neutral position) is plotted along the left vertical axis of the movement timing diagram 190, the movement of the FEL bucket 26 from the fully lowered position is plotted along the right vertical axis, and the passage of time is plotted along the horizontal axis. As the distance from the horizontal axis increases, as measured along the left vertical axis, the joystick 54 further moves in the rearward direction away from the center position (neutral position) of the joystick. In comparison, increasing distance from the horizontal axis of the movement timing diagram 190 as taken along the right vertical axis corresponds to movement of the FEL bucket 26 in an upward direction away from the ground bucket position and toward the fully raised bucket position. Finally, movement to the right along the horizontal axis from the origin (lower left corner) of the movement timing diagram 190 corresponds to the passage of time, with time points t0 to t4 marking the times when key events occur, as discussed further below.

[0058] In the movement timing diagram 190, a first characteristic or curve 192 represents an example of how the operator may move the joystick 54 when: (i) initially moving the joystick 54 to activate or trigger the automatic implement positioning function that raises the FEL bucket 26 to the upper preset position; and (ii) subsequently releasing the joystick 54, which then returns to the center position under the influence of centripetal force. In this example, at time t0, the joystick 54 is in the center joystick position (neutral position). The operator has previously set the upper preset position to a height slightly lower than the fully raised bucket position, as indicated by the horizontal bars 194, 196 marked in the upper right corner of the movement timing diagram 190. To initiate the illustrated joystick movement sequence, the operator first rotates the joystick 54 of the MRF joystick assembly 52 in a manner that triggers the automatic implement positioning function that provides automated control of the FEL assembly 24 to raise the FEL bucket 26 to the upper preset position. The operator does this by rotating the joystick 54 in a rearward direction to or through a stop feature applied by the MRF, the position of which is determined by Figure 7 The horizontal bar 198 in the mark (the stopper corresponds to Figure 4 The joystick motion occurs during the time frame t0 to t1 and is represented by segment 200 of the joystick motion curve 192. The operator then releases the joystick 54 (or applies minimal force on the joystick) in the example control scenario, as indicated by marker 202. In certain embodiments, the controller architecture 66 can control the MRF joystick resistance mechanism 64 to apply sufficient MRF resistance to the joystick 54 to achieve a desired effect when the operator is in contact with the detent feature 100 ( Figure 4 ) produces a hold detent (rather than a feel detent) at a position corresponding to ), in which case the joystick 54 may remain at the detent feature 100 or slightly beyond the detent feature 100 after the operator releases it for a short duration. Figure 7 This is indicated by a segment 204 of the joystick motion profile 192 spanning time frames t1 to t2. The implement automatic positioning function may be enabled after time point t2, as described below. In other embodiments, this brief joystick hold may not be provided, in which case segment 204 of the joystick motion profile 192 may be eliminated.

[0059] At time point t2, the automatic implement positioning function of the wheel loader 20 is enabled in response to the aforementioned joystick movement. The second characteristic or curve 206 (referenced to the right vertical axis of the movement timing diagram 190) represents the resulting movement of the FEL assembly 24 in the following example scenario: in this example scenario, the FEL bucket 26 is in the fully lowered position at time point t2. Leaving aside the discussion of the joystick movement after time point t2, the controller architecture 66 (or another control system on the wheel loader 20) now sends appropriate commands to the EH actuation system 50 to raise the FEL bucket 26 to the upper preset position (as previously set by the operator and defined by the preset position data 80 stored in the memory 68). In an embodiment, the controller architecture 66 can simply issue a command to the EH actuation system 50 (more specifically, the valve actuator that controls the exchange of hydraulic fluid with the lift arm cylinder 44) to raise the FEL bucket 26 to the upper preset position at a substantially constant rate. Alternatively, as Figure 7 As indicated in FIG, the controller architecture 66 can issue commands to the EH actuation system 50 to initially raise the FEL bucket 26 at a relatively rapid rate (corresponding to segment 208 of the bucket movement curve 206), and then at a slower rate (corresponding to segment 210 of the curve 206), thereby providing a gradual ramp-down of the FEL bucket's motion when transitioning to the upper preset position. In other words, the implement (here, the FEL bucket 26) is automatically controlled to decelerate as the implement approaches the first preset position during execution of the implement automatic positioning function. This transition between motion rates occurs at time t3. This approach provides smooth FEL bucket motion and, in essence, a gentle stopping sequence to minimize the generation of impact forces when stopping the FEL bucket's motion upon reaching the upper preset position.

[0060] Returning to time point t2 in the movement timing diagram 190, dashed line 212 generally indicates the manner in which the joystick 54 rapidly returns to the center (neutral position) under the influence of centripetal force after the operator releases (marked 202) and the detent holding force of the MRF joystick resistance mechanism 64 is removed (if applied). Without the continued application of a certain level of MRF-generated resistance, the joystick 54 will rapidly return to the center (neutral position) under the influence of centripetal force. Therefore, the joystick 54 will completely stop in the center (neutral position) before time point t4, when the FEL bucket 26 has completed its travel to the upper preset position. To avoid rapid rebound of the joystick 54, the controller architecture 66 can operate in an automatic positioning mirror mode. During this automatic positioning mirror mode, the controller architecture 66, in conjunction with the activation of the machine automatic positioning function, varies the MRF resistance applied to the joystick 54 to control the RTC rate of the joystick 54 as it returns to the center (neutral position). Thus, when operating in the automatic positioning mirror mode (and other modified centripetal modes described below), the controller architecture 66 can utilize the positing sensor 60 to determine when the joystick 54 initially begins to return toward the neutral position under the influence of the centripetal force. Subsequently, in response to determining that the joystick 54 has begun to return toward the neutral position due to the centripetal force, the controller architecture 66 controls or issues commands to the MRF joystick resistance mechanism 64 to modify the rate at which the joystick 54 returns to the neutral position by varying the MRF resistance applied to the joystick 54.

[0061] In an embodiment, the controller architecture 66 may issue a command to the MRF joystick resistance mechanism 64 to adjust the RTC rate of the joystick 54 to generally approximate (or otherwise approximately match (i.e., be approximately proportional to)) the rate of movement of the FEL bucket 26 (or other implement attached to the terminal end of the FEL assembly 24). Thus, the controller architecture 66 may adjust the MRF-applied resistance force applied to the joystick 54 and opposing the centripetal force to achieve a moderate RTC rate (as indicated by line segment 214 of the joystick motion curve 192) within time frames t2 to t3 corresponding to the relatively rapid movement of the FEL bucket 26. Subsequently, at time point t3, the controller architecture 66 may control the MRF joystick resistance mechanism 64 to further slow the RTC rate of the joystick 54 during segment 210 of the implement movement curve 206 in a manner that generally corresponds to the deceleration of the FEL bucket 26 within time frames t3 to t4. This is Figure 7This is indicated by the last segment 216 of the joystick motion curve 192, which extends from time point t3 to time point t4 and ends with the joystick 54 returning to the center (neutral) position. Furthermore, both the joystick 54 and the FEL bucket 26 complete their respective movements at the same time point and within a concurrent or substantially equal duration.

[0062] In the manner described above, the RTC rate of the joystick 54 is controlled by the controller architecture 66, and more generally, by the MRF joystick system 22, to generally correspond to or mirror the implement movement when the implement (here, the FEL bucket 26) is automatically moved to a preset position, depending on the execution of the implement auto-positioning or recoil function. This better maintains the relationship between joystick movement and implement movement during the implement auto-positioning function, improving the operator experience and also reducing confusion that may otherwise occur if the operator is unfamiliar with this work vehicle function. When operating in the aforementioned auto-positioning mirroring mode in any suitable manner, the controller architecture 66 can determine the appropriate commands to send to the MRF joystick resistance mechanism 64 to achieve the desired RTC. For example, in certain embodiments, the controller architecture 66 can recall a predefined joystick movement profile from memory 68, based on, for example, the specific type of implement auto-positioning function and the current vertical position of the FEL bucket 26 (or other boom assembly implement) when the implement auto-positioning function is triggered. In other cases, the controller architecture 66 may utilize boom assembly tracking sensors (included in the sensors 76) to track the movement of the FEL bucket 26 (or other component implement) while monitoring the joystick position using the joystick position sensor 60 and iteratively adjust the resistance applied via the MRF on a rapid (real-time) basis to ensure that the RTC rate of the joystick 54 substantially corresponds to the rate of movement of the FEL bucket 26 when performing the implement auto-positioning function. In still other cases, the controller architecture 66 may also consider one or more pressures within the actuation system 50 (as measured using pressure sensors within the sensors 76) in determining the appropriate manner in which to send commands to the MRF joystick resistance mechanism 64 to achieve the desired RTC rate when operating in the auto-positioning mirror mode.

[0063] In embodiments, the MRF joystick system 22 can operate in other modified centripetal modes in addition to or in lieu of the aforementioned auto-positioning mirror mode. For example, in certain circumstances, the MRF joystick system 22 can operate in the following modified centripetal mode: the controller architecture 66 issues a command to the MRF joystick resistance mechanism 64 to adjust the RTC rate of the joystick 54 based on an operator preference (e.g., as previously specified by the operator via data input using the operator interface 72). For example, in such an embodiment, the operator can interact with a GUI generated on the display device 74 or another operator input device to slow the joystick return rate. In such an embodiment, the operator can be allowed to select a slower RTC rate range. A slow return mode can also be selectively enabled or disabled, in which a controlled application of MRF joystick resistance is used to achieve a moderate joystick RTC rate that is less than the RTC rate of the joystick return under normal conditions without the MRF resistance applied by the MRF joystick resistance mechanism.

[0064] In other cases, the MRF joystick system 22 can automatically adjust the RTC rate of the joystick 54 based on the current operating parameters of the work vehicle. As a first example, in the case of a wheel loader 20, the RTC rate of the joystick 54 can be adjusted based on the current load carried by the FEL bucket 26 (as measured directly using a force sensor) or indirectly based on the hydraulic pressure within the EH actuation system 50 (using either or both of the non-joystick sensors 76). In one embodiment, the controller architecture 66 issues commands to the MRF joystick resistance mechanism 64 to increase the MRF resistance and slow the RTC rate of the joystick 54 (when shifted from the neutral position) as the load placed on the wheel loader 20 or other work vehicle increases. As a second example, in the context of a joystick-operated work vehicle, the controller architecture 66 can vary the RTC rate of one or more MRF joystick devices within the work vehicle based on the vehicle's ground speed. For example, the controller architecture 66 can issue a command to the MRF joystick resistance mechanism 64 to increase the MRF resistance and slow the RTC rate of the joystick 54 as the vehicle's ground speed increases. In still other implementations, the controller architecture 66 can adjust the RTC rate of the joystick 54 based on the work vehicle's current operating mode, the specific work vehicle function currently being performed by the work vehicle using the MRF joystick device, or the type of implement currently attached to the work vehicle. The aforementioned parameters can be determined automatically using sensors 76, as appropriate, or alternatively based on operator input into the work vehicle's systems using the operator interface 72.

[0065] Notably, in at least some embodiments (including the examples described herein), the MRF joystick resistance mechanism 64 allows for independent adjustment of the MRF resistance joystick force to resist joystick movement about different rotational axes. In at least some cases, the controller architecture 66 can issue commands to the MRF joystick resistance mechanism 64 to provide a first RCT rate when the joystick 54 is displaced from the center (neutral position) by rotating about a first axis, and a second (different) RCT rate when the joystick 54 is displaced from the center (neutral position) by rotating about a second axis perpendicular to the first axis. Returning again to the example of the wheel loader 20, and performing an implement automatic positioning function to raise the FEL bucket 26 to an upper preset position, in conjunction with modifying the joystick RTC rate along the opposite rotational axis, the controller architecture 66 may or may not modify the RTC rate of the joystick 54 when it is rotated about the first rotational axis to reel or extend the FEL bucket 26 (i.e., when the joystick 54 is moved to the left or right of the operator), as previously described. In such an embodiment, the controller architecture 66 thereby issues commands to the MRF joystick resistance mechanism 64 to modify the rate at which the joystick 54 returns to the neutral position via rotation about a first axis, while independently varying the rate at which the joystick 54 returns to the neutral position via rotation about a second axis perpendicular to the first axis.

[0066] Additional Examples of Work Vehicles Advantageously Equipped with an MRF Joystick System

[0067] Thus, the foregoing has described an example of an MRF joystick system capable of operating in a modified centripetal mode (such as an auto-positioning mirror mode), wherein the MRF joystick system varies the RTC rate of a self-centering joystick in a predetermined manner. While the foregoing description has primarily focused on a specific type of work vehicle (a wheel loader) that includes a specific joystick-controlled work vehicle function (FEL assembly movement), the embodiments of the MRF joystick system described herein are suitable for integration into a wide range of work vehicles that include joystick arrangements. Figure 8 The upper left portion of the diagram illustrates an example work vehicle, the middle portion illustrates an example MRF joystick device, and the right portion illustrates controlled vehicle functions, wherein the controlled vehicle functions include but are not limited to: boom assembly movement, boom assembly movement, steering (if travel mode is available), chassis movement, front end loader (FEL) movement, multi-DOF shovel, movement (including shovel-hover assembly rotation). Figure 8 The lower portion of FIG illustrates other example work vehicles that may be equipped with an MRF joystick device. Specifically, Figure 8The upper portion of FIG. 1 illustrates three additional examples of such work vehicles and includes an excavator 217, a skid steer loader (SSL) 218, and a motor grader 220. First, with respect to the excavator 217, the excavator 217 may be equipped with two example MRF joystick devices 222 disposed within a cab 224 of the excavator 217. Figure 8 As indicated in FIG, MRF joystick devices 222 can be used to control the movement of a boom assembly 226 that terminates in a bucket 228 or another implement (e.g., a grappler, a hydraulic hammer, or a different type of bucket). Additionally, one of these MRF joystick devices 222 can be used to control the swing of the boom assembly 226 via rotation of the excavator chassis relative to the excavator's tracked undercarriage. Where the excavator 217 is operable in a joystick travel mode, the joystick devices 222 can also steer or otherwise control the travel of the excavator 217. Comparatively, two MRF joystick devices 230 can be positioned in the cab 232 of the example SSL 218 and used to control not only the movement of the FEL 234 and its bucket 236, but also further control the movement of the chassis 238 of the SSL 218 in a known manner. Finally, the motor grader 220 also includes two MRF joystick assemblies 240 positioned within a cab 242 of the motor grader 220. The MRF joystick assemblies 240 may be used to control movement of a motor grader chassis 244 (via control of a first transmission that drives the rear wheels of the motor grader and possibly a second (e.g., hydrostatic) transmission that drives the front wheels), as well as movement of a blade 246 of the motor grader (e.g., via rotation and angular adjustment of a blade-circle assembly 248 and adjustment of the sideways angle of the blade 246).

[0068] In each of the examples mentioned above, the MRF joystick device can be controlled to modify the RTC rate of the joystick in question. In this regard, any or all of the example excavator 217, SSL 218, and motor grader 220 can be equipped with a work vehicle MRF joystick system including at least one joystick device, an MRF joystick resistance mechanism, and a controller architecture. Furthermore, as described above, the controller architecture can determine when a modified centripetal pattern is appropriately applied and then adjust the MRF-applied resistance to the centripetal force accordingly. For example, any or all of the work vehicles 217, 218, 220 can be provided with an automatic implement positioning function that is triggered by the joystick moving beyond a stop feature in a manner similar to that described above in conjunction with the wheel loader 20. Thus, in such circumstances, the controller architecture may control the MRF joystick resistance mechanism to vary the RTC rate of the joystick (or joysticks) in question to achieve a joystick return rate that generally corresponds to the automatic movement of the movable implement to a preset position during execution of the implement auto-positioning or recoil function. Similarly, any or all of the work vehicles 217, 218, 220 may include an MRF joystick system that allows the joystick return rate to be adjusted to the operator's preference and / or in response to changes in a sensed parameter of the work vehicle (e.g., load or speed). Finally, Figure 8 The lower portion of illustrative embodiments illustrates still further examples of work vehicles usefully equipped with embodiments of the MRF joystick system described herein, and includes a tractor 250 , a feller buncher 252 , a skidder 254 , a combine 256 , and a dozer 258 equipped with an FEL.

[0069] Examples of MRF joystick systems for work vehicles

[0070] For ease of reference, the following examples of work vehicle MRF joystick systems are also provided and numbered.

[0071] 1. In an embodiment, the work vehicle MRF joystick system includes: a joystick device; an MRF joystick resistance mechanism; and a controller architecture coupled to the MRF joystick resistance mechanism. The joystick arrangement further includes: a base housing; a joystick mounted to the base housing and movable relative to the base housing via a neutral position; and a joystick biasing mechanism coupled to the joystick and applying a centripetal force to urge the joystick toward the neutral position when the joystick moves away from the neutral position; the MRF joystick resistance mechanism being controllable to vary an MRF resistance that resists movement of the joystick relative to the base housing along at least one degree of freedom; and the controller architecture being operable in a modified centripetal mode, wherein the controller architecture performs the following operations: (i) determining when the joystick begins to return toward the neutral position due to the centripetal force applied to the joystick by the joystick biasing mechanism, and (ii) in response to determining that the joystick begins to return toward the neutral position due to the centripetal force, issuing a command to the MRF joystick resistance mechanism to modify the rate at which the joystick returns to the neutral position by varying the MRF resistance applied to the joystick.

[0072] 2. The work vehicle MRF joystick system of example 1, wherein the work vehicle is equipped with an implement, and the controller architecture is configured to enter the modified centripetal mode in conjunction with activation of a first implement automatic positioning function that automatically moves the implement to a first predetermined position.

[0073] 3. The work vehicle MRF joystick system of Example 2, wherein, when operating in the modified centripetal mode, the controller architecture issues a command to the MRF joystick resistance mechanism to modify the rate at which the joystick returns to the neutral position, the joystick returning to the neutral position approximately at the same time as the implement moves to the first preset position.

[0074] 4. The work vehicle MRF joystick system of Example 2, wherein, when operating in the modified centripetal mode, the controller architecture commands the MRF joystick resistance mechanism to modify the rate at which the joystick returns to the neutral position to be approximately proportional to the rate at which the implement moves from its current position to the first preset position.

[0075] 5. A work vehicle MRF joystick system according to Example 4, wherein, during execution of the implement automatic positioning function, the implement decelerates as the implement approaches the first preset position; and when operating in the modified centripetal mode, the controller architecture issues a command to the MRF joystick resistance mechanism to further increase the MRF resistance applied to the joystick substantially simultaneously with the deceleration of the implement.

[0076] 6. The work vehicle MRF joystick system of example 2, wherein the controller architecture is configured to enable the first implement automatic positioning function in response to a predetermined movement of the joystick.

[0077] 7. The work vehicle MRF joystick system of Example 6, wherein the predetermined movement of the joystick comprises the joystick rotating to or past a stop feature of the joystick arrangement.

[0078] 8. The work vehicle MRF joystick system of Example 7, wherein the controller architecture is configured to generate the stop feature by commanding the MRF joystick resistance mechanism to increase the MRF resistance when the operator moves the joystick to a predetermined position corresponding to the stop feature.

[0079] 9. A work vehicle MRF joystick system according to Example 2, wherein the implement is coupled to the work vehicle via a boom assembly; the joystick is rotatable relative to the base housing in a forward direction and a rearward direction to move the boom assembly in a manner of lowering the implement and raising the implement, respectively; and further, when the first implement automatic positioning function is enabled by moving the joystick to or through a first stop feature encountered when rotating the joystick in a rearward direction away from the neutral position, the first preset position is an upper preset position.

[0080] 10. A work vehicle MRF joystick system according to Example 9, wherein the controller architecture is further configured to enter the modified centripetal mode in conjunction with the activation of a second implement automatic positioning function, which automatically moves the implement to a lower preset position; the second implement automatic positioning function is activated by moving the joystick to a second stop feature encountered when rotating the joystick in a forward direction away from the neutral position or moving through the second stop feature.

[0081] 11. A work vehicle MRF joystick system according to Example 1, wherein the work vehicle is equipped with a movable implement; when operating in the modified centripetal mode, the controller architecture issues a command to the MRF joystick resistance mechanism to modify the rate at which the joystick returns to the neutral position to correspond to the rate of movement of the movable implement.

[0082] 12. A work vehicle MRF joystick system according to Example 1, wherein the joystick is capable of rotating relative to the base housing about a first axis and a second axis, the second axis being perpendicular to the first axis; when operating in the modified centripetal mode, the controller architecture issues a command to the MRF joystick resistance mechanism to modify the rate at which the joystick returns to the neutral position via rotation about the first axis, while independently changing the rate at which the joystick returns to the neutral position via rotation about the second axis.

[0083] 13. The work vehicle MRF joystick system of Example 1 further comprising a sensor coupled to the controller architecture and configured to measure a parameter indicative of a current load of the work vehicle; when operating in the modified centripetal mode, the controller architecture commands the MRF joystick resistance mechanism to modify a rate at which the joystick returns to the neutral position based at least in part on the current load of the work vehicle.

[0084] 14. The work vehicle MRF joystick system of Example 1 further comprises a sensor coupled to the controller architecture and configured to measure a current speed of the work vehicle; when operating in the modified centripetal mode, the controller architecture commands the MRF joystick resistance mechanism to modify a rate at which the joystick returns to the neutral position based at least in part on the current speed of the work vehicle.

[0085] 15. According to the work vehicle MRF joystick system described in Example 1, the work vehicle MRF joystick system also includes a memory, which stores an operator preference setting, and the operator preference setting indicates the operator's preferred joystick return rate; when operating in the modified centripetal mode, the controller architecture issues a command to the MRF joystick resistance mechanism to modify the rate at which the joystick returns to the neutral position according to the operator preference setting.

[0086] in conclusion

[0087] Thus, the foregoing provides a work vehicle MRF joystick system capable of operating in a modified centripetal mode, which intelligently controls the rate at which the centripetal joystick returns to the neutral position after being displaced from the neutral position. Thus, embodiments of the MRF joystick system can allow the RTC rate of the joystick to be adjusted to a preference, or to dynamically adapt in response to changes in work vehicle operating parameters, operating modes, or other conditions. Additionally, in certain embodiments, the MRF joystick system can operate in an automatic positioning mirror mode, in which the MRF joystick system adjusts the RTC rate of the joystick to generally correspond to (or otherwise, be roughly proportional to) the movement of the implement as it transitions from a current position to a preset position during execution of an implement automatic positioning or "kickback" function. This advantageously improves the correlation between the joystick motion and the implement movement during execution of a given implement automatic positioning function, thereby reducing the potential for operator confusion or also enhancing the operator experience. As described above, various other benefits are obtained through embodiments of the work vehicle MRF joystick system.

[0088] As used herein, unless the context clearly indicates otherwise, descriptions in the singular are intended to include the plural. It should also be understood that the terms "comprise and / or comprising" when used herein specify the presence of specified features, elements, steps, operations, components, and / or components, but do not preclude the presence or addition of one or more other features, elements, steps, operations, elements, components, and / or combinations thereof.

[0089] The description of the present disclosure has been presented for the purpose of illustration and description, but is not intended to be exclusive or to limit the disclosure to 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 present disclosure. The embodiments explicitly referenced herein are selected and described in order to best explain the principles of the present disclosure and its practical application, and to enable those of ordinary skill in the art to understand the present disclosure and recognize many alternatives, modifications and variations to the described examples. Therefore, various embodiments and implementations other than those explicitly described are within the scope of the appended claims.

Claims

1. A work vehicle magnetorheological fluid joystick system (22), i.e., a work vehicle MRF joystick system (22), for use on a work vehicle (20) equipped with an implement (26), the work vehicle MRF joystick system (22) comprising: A joystick device (52), the joystick device (52) comprising: Basal shell (56); a joystick (54) mounted to the base housing (56) and movable relative to the base housing (56) via a neutral position; and a joystick biasing mechanism (62, 124) coupled to the joystick (54) and applying a centripetal force to urge the joystick (54) back toward the neutral position when the joystick (54) is moved away from the neutral position; an MRF joystick resistance mechanism (64) controllable to vary an MRF resistance that resists movement of the joystick (54) relative to the base housing (56) along at least one degree of freedom; and A controller architecture (66) coupled to the MRF joystick resistance mechanism (64), the controller architecture (66) being operable in a modified centripetal mode, wherein the controller architecture (66) operates as follows: determining when the joystick (54) begins to return toward the neutral position due to the centripetal force applied to the joystick (54) by the joystick biasing mechanism (62, 124); and In response to determining that the joystick (54) begins to return toward the neutral position due to the centripetal force, a command is issued to the MRF joystick resistance mechanism (64) to modify the rate at which the joystick (54) returns to the neutral position by changing the MRF resistance applied to the joystick (54); and the modified centripetal mode is entered in conjunction with activation of a first implement automatic positioning function that automatically moves the implement (26) to a first preset position.

2. The work vehicle MRF joystick system (22) according to claim 1, wherein: When operating in the modified centripetal mode, the controller architecture (66) issues commands to the MRF joystick resistance mechanism (64) to modify the rate at which the joystick (54) returns to the neutral position so that the joystick returns to the neutral position approximately at the same time as the implement (26) moves to the first preset position.

3. The work vehicle MRF joystick system (22) according to claim 1, wherein: When operating in the modified centripetal mode, the controller architecture (66) issues commands to the MRF joystick resistance mechanism (64) to modify the rate at which the joystick (54) returns to the neutral position to be approximately proportional to the rate at which the implement (26) moves from a current position to the first predetermined position.

4. The work vehicle MRF joystick system (22) according to claim 3, wherein: During execution of the first implement automatic positioning function, as the implement (26) approaches the first preset position, the implement (26) decelerates; and Wherein, when operating in the modified centripetal mode, the controller architecture (66) issues a command to the MRF joystick resistance mechanism (64) to further increase the MRF resistance applied to the joystick (54) substantially simultaneously with deceleration of the implement (26).

5. The work vehicle MRF joystick system (22) according to claim 1, wherein: The controller architecture (66) is configured to enable the first implement automatic positioning function in response to a predetermined movement of the joystick (54).

6. The work vehicle MRF joystick system (22) according to claim 5, wherein: The predetermined movement of the joystick (54) includes the joystick (54) rotating into or past a stop feature of the joystick arrangement (52).

7. The work vehicle MRF joystick system (22) according to claim 6, wherein: The controller architecture (66) is configured to generate the detent feature by commanding the MRF joystick resistance mechanism (64) to increase the MRF resistance when an operator moves the joystick (54) to a predetermined position corresponding to the detent feature.

8. The work vehicle MRF joystick system (22) according to claim 1, wherein: The implement (26) is coupled to the work vehicle via a boom assembly (24); wherein the joystick (54) is rotatable relative to the base housing (56) in a forward direction and a rearward direction to move the boom assembly (24) in a manner of lowering the implement (26) and raising the implement (26), respectively; wherein the first preset position includes an upper preset position; and The first implement automatic positioning function is enabled by moving the joystick (54) into or through a first stop feature encountered when rotating the joystick (54) in a rearward direction away from the neutral position.

9. The work vehicle MRF joystick system (22) according to claim 8, wherein: The controller architecture (66) is further configured to enter the modified centripetal mode in conjunction with activation of a second implement automatic positioning function that automatically moves the implement (26) to a lower preset position; The second implement automatic positioning function is enabled by moving the joystick (54) into or through a second stop feature encountered when the joystick (54) is rotated in a forward direction away from the neutral position.

10. The work vehicle MRF joystick system (22) according to claim 1, wherein: The work vehicle (20) is equipped with a movable implement (26); and wherein, when operating in the modified centripetal mode, the controller architecture (66) issues a command to the MRF joystick resistance mechanism (64) to modify the rate at which the joystick (54) returns to the neutral position to correspond to the rate of movement of the movable implement (26).

11. The work vehicle MRF joystick system (22) according to claim 1, wherein: The joystick (54) is rotatable relative to the base housing (56) about a first axis and a second axis, wherein the second axis is perpendicular to the first axis; wherein, when operating in the modified centripetal mode, the controller architecture (66) issues commands to the MRF joystick resistance mechanism (64) to modify the rate at which the joystick (54) returns to the neutral position via rotation about the first axis while independently varying the rate at which the joystick (54) returns to the neutral position via rotation about the second axis.

12. The work vehicle MRF joystick system (22) of claim 1, further comprising a sensor (76) coupled to the controller architecture (66), the sensor (76) being configured to measure a parameter indicative of a current load of the work vehicle (20); in, When operating in the modified centripetal mode, the controller architecture (66) issues commands to the MRF joystick resistance mechanism (64) to modify the rate at which the joystick (54) returns to the neutral position based at least in part on the current load of the work vehicle (20).

13. The work vehicle MRF joystick system (22) of claim 1, further comprising a sensor (76) coupled to the controller architecture (66), the sensor (76) being configured to measure a current speed of the work vehicle (20); in, When operating in the modified centripetal mode, the controller architecture (66) issues commands to the MRF joystick resistance mechanism (64) to modify the rate at which the joystick (54) returns to the neutral position based at least in part on the current speed of the work vehicle (20).

14. The work vehicle MRF joystick system (22) of claim 1, further comprising a memory (68) storing an operator preference setting indicating an operator preferred joystick (54) return rate; and in, When operating in the modified centripetal mode, the controller architecture (66) issues commands to the MRF joystick resistance mechanism (64) to modify the rate at which the joystick (54) returns to the neutral position according to the operator preference setting.

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