WORK VEHICLE MAGNETORHEOLOGICAL FLUID JOYSTICK SYSTEMS PROVIDING MACHINE STATE FEEDBACK

Embodiments of a work vehicle magnetorheological fluid (MRF) joystick system include a joystick device, an MRF joystick resistance mechanism, a controller architecture, and a work vehicle sensor configured to provide sensor data indicative of an operational parameter pertaining to work vehicle. The MRF joystick resistance mechanism is controllable to vary an MRF resistance force resisting movement of a joystick included in the joystick device relative to a base housing thereof. The controller architecture is configured to: (i) monitor for variations in the operational parameter utilizing the sensor data; and (ii) provide tactile feedback through the joystick device indicative of the operational parameter by selectively commanding the MRF joystick resistance mechanism to adjust the MRF resistance force impeding joystick movement based, at least in part, on variations in the operational parameter.

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Description
CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to U.S. provisional application Ser. No. 63/019,083, filed with the United Stated Patent and Trademark Office on May 1, 2020.

STATEMENT OF FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

FIELD OF THE DISCLOSURE

This disclosure relates to magnetorheological fluid (MRF) joystick systems, which selectively vary joystick resistances to provide feedback indicative of monitored operational parameters or machine states of work vehicles.

BACKGROUND OF THE DISCLOSURE

Joystick devices are commonly utilized to control various operational aspects of work vehicles employed within the construction, agriculture, forestry, and mining industries. For example, in the case of a work vehicle equipped with a boom assembly, an operator may utilize one or more joystick devices to control boom assembly movement and, therefore, movement of a tool or implement mounted to an outer terminal end of the boom assembly. Common examples of work vehicles having such joystick-controlled boom assemblies include excavators, feller bunchers, skidders, tractors (on which modular front end loader and backhoe attachments may be installed), tractor loaders, wheel loaders, and various compact loaders. Similarly, in the case of dozers, motor graders, and other work vehicles equipped with earth-moving blades, an operator may utilize with one or more joysticks to control blade movement and positioning. Joystick devices are also commonly utilized to steer or otherwise control the directional movement of the work vehicle chassis in the case of motor graders, dozers, and certain loaders, such as skid steer loaders. Given the prevalence of joystick devices within work vehicles, taken in combination with the relatively challenging, dynamic environments in which work vehicles often operate, a continued demand exists for advancements in the design and function of work vehicle joystick systems, particularly to the extent that such advancements can improve the safety and efficiency of work vehicle operation.

SUMMARY OF THE DISCLOSURE

A work vehicle magnetorheological fluid (MRF) joystick system is disclosed for usage onboard a work vehicle. In embodiments, the work vehicle MRF joystick system includes a joystick device, an MRF joystick resistance mechanism, a controller architecture, and a work vehicle sensor configured to provide sensor data indicative of an operational parameter pertaining to the work vehicle. The joystick device includes, in turn, a base housing, a joystick movably mounted to the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The MRF joystick resistance mechanism is controllable to vary an MRF resistance force inhibiting or resisting movement of the joystick relative to the base housing in at least one degree of freedom (DOF). The controller architecture is coupled to the joystick position sensor, to the work vehicle sensor, and to the MRF joystick resistance mechanism. The controller architecture is configured to: (i) monitor for variations in the operational parameter utilizing the sensor data; and (ii) provide tactile feedback through the joystick device indicative of the operational parameter by selectively commanding the MRF joystick resistance mechanism to adjust the MRF resistance force based, at least in part, on variations in the operational parameter.

In further embodiments, the work vehicle MRF joystick system includes a joystick device, an MRF joystick resistance mechanism, and a controller architecture. Once again, the joystick device includes a base housing, a joystick movably mounted to the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The MRF joystick resistance mechanism is controllable to vary an MRF resistance force resisting movement of the joystick relative to the base housing in at least one DOF. The controller architecture, coupled to the joystick position sensor and to the MRF joystick resistance mechanism, is configured to: (i) monitor a current ground speed of the work vehicle; and (ii) selectively command the MRF joystick resistance mechanism to adjust the MRF resistance force based, at least in part, on the current ground speed of the work vehicle.

In still further embodiments, the MRF joystick system is utilized onboard a work vehicle equipped with a boom-mounted implement. The MRF joystick system includes a joystick device, an MRF joystick resistance mechanism, and a controller architecture. The joystick device includes, in turn, a base housing, a joystick movably mounted to the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The MRF joystick resistance mechanism is controllable to vary an MRF resistance force resisting movement of the joystick relative to the base housing in at least one DOF. Coupled to the joystick position sensor and to the MRF joystick resistance mechanism, the controller architecture is configured to: (i) estimate a variable load resisting movement of the boom-mounted implement in at least one direction, and (ii) selectively command the MRF joystick resistance mechanism to increase the MRF resistance force as the variable load increases.

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

BRIEF DESCRIPTION OF THE DRAWINGS

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

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

FIG. 2 is a perspective view from within the excavator cabin shown in FIG. 1 illustrating two joystick devices, which may be included in the example MRF joystick system and utilized by an operator to control movement of the excavator boom assembly;

FIGS. 3 and 4 are cross-sectional schematics of the example MRF joystick system, as partially shown and taken along perpendicular section planes through a joystick included in a joystick device, illustrating one possible construction of the MRF joystick system;

FIG. 5 is a process suitably carried-out by the controller architecture of the MRF joystick system to vary joystick stiffness in a manner providing machine state feedback; and

FIG. 6 is a graphic illustrating, in a non-exhaustive manner, additional example work vehicles into which embodiments of the MRF joystick system may be beneficially integrated.

Like reference symbols in the various drawings indicate like elements. For simplicity and clarity of illustration, descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the example and non-limiting embodiments of the invention described in the subsequent Detailed Description. It should further be understood that features or elements appearing in the accompanying figures are not necessarily drawn to scale unless otherwise stated.

DETAILED DESCRIPTION

Embodiments of the present disclosure are shown in the accompanying figures of the drawings described briefly above. Various modifications to the example embodiments may be contemplated by one of skill in the art without departing from the scope of the present invention, as set-forth the appended claims. As appearing herein, the term “work vehicle” includes all parts of a work vehicle or work machine. Thus, in implementations in which a boom assembly terminating in an implement is attached to the chassis of a work vehicle, the term “work vehicle” encompasses both the chassis and the boom assembly, as well as the implement or tool mounted to the terminal end of the boom assembly.

Overview

The following describes work vehicle joystick systems incorporating magnetorheological fluid (MRF) devices or subsystems, which provide tactile feedback indicative of monitored operational parameters or “machine states” of work vehicles. During work vehicle operation, the below-described work vehicle MRF joystick system receives sensor data indicative of at least one monitored parameter of a given work vehicle; and selectively vary an MRF resistance force impeding joystick movement in at least one degree of freedom (DOF) based, at least in part, on joystick position and variations in the monitored parameter. In so doing, the work vehicle MRF joystick system provides work vehicle operators with tactile feedback indicative of the current state or magnitude of the monitored operational parameter or machine state. As the tactile feedback is provided through the joystick device itself, this information is conveyed to the operator in a highly intuitive, rapid manner and without requiring the operator to avert visual attention from the work task at hand. Further, in at least some embodiments, the tactile feedback provided through the below-described joystick devices may help guide or influence operator control inputs to promote smooth or non-abrupt work vehicle operation, to increase uniformity between operator expectations and work vehicle performance, and to provide similar benefits. Overall operator satisfaction levels and work vehicle efficiency may be improved as a result.

Embodiments of the work vehicle MRF joystick system include a processing sub-system or “controller architecture,” which is coupled to an MRF damper or an MRF joystick resistance mechanism; that is, a mechanism or device containing a magnetorheological fluid and capable of modifying the rheology (viscosity) of the fluid through variations in the strength of an electromagnetic (EM) field to provide controlled adjustments to the resistive force impeding joystick motion in at least one DOF. This resistive force is referred to below as an “MRF resistance force,” while the degree to which an MRF resistance force impedes joystick motion in a particular direction or combination of directions is referred to as the “joystick stiffness.” The MRF joystick resistance mechanism may be commanded by the controller architecture to apply various different resistive effects selectively impeding joystick rotation or other joystick motion in any given direction, over any given range of travel of the joystick, and through the application of varying magnitudes of resistive force. For example, embodiments of the MRF joystick system may progressively increase joystick stiffness in proportion to changes in certain monitored parameters; e.g., in embodiment, and as discussed in detail below, the controller architecture may command the MRF joystick resistance mechanism to increase the MRF resistance force (and, therefore, joystick stiffness) as a monitored parameter, such as a material load, a hydraulic pressure, or work vehicle ground speed, increases in magnitude. Additionally or alternatively, embodiments of the MRF joystick system may generate other MRF-applied effects, such as detent or pulsating effects, briefly impeding joystick motion as a monitored parameter surpasses predetermined thresholds. Further, embodiments of the MRF joystick control system may be capable of increasing joystick stiffness in a single DOF or, instead, of independently increasing joystick stiffness in multiple DOFs. For example, in implementations which a joystick is rotatable about two perpendicular axes, the MRF joystick resistance mechanism may be capable of independently vary joystick stiffnesses about the two rotational axes of the joystick.

The work vehicle MRF joystick system provides a high level of flexibility, both from design and customization standpoints. Regarding design flexibility, the MRF joystick system can be configured to vary joystick stiffness in response to a wide range of monitored parameters pertaining to work vehicles of varying types employed in construction, agriculture, mining, and forestry industries. A non-exhaustive list of such monitored parameters includes work vehicle ground speed (particularly in the case of joystick-steered work vehicles), the proximity of movable work vehicle components (e.g., boom assembly joints or hydraulic cylinders) to motion stops, and various loads placed on a work vehicle. In the latter regard, embodiments of the MRF joystick system may monitor, and selectively vary the MRF joystick resistance force based upon, material loads carried by the work vehicle, such as the fill load of a bucket attached to a boom assembly. Similarly, in embodiments, the MRF resistance force and joystick stiffness in at least one DOF may be varied based on hydraulic pressures included within electrohydraulic (EH) actuation system utilized to animate movable implements, such as moveable blades (in the case of, for example dozers and motor graders) and implements attached to boom assemblies (in the case of, for example, excavators, feller bunchers, tractors equipped with front end loader (FEL) attachments, wheel loaders, backhoes, and excavators). In still other embodiments, the MRF resistance force and joystick stiffness may be varied as a function of other loads placed on a work vehicle, such as the load placed on the primary engine of a work vehicle. In such embodiments, the controller architecture may progressively increase the MRF resistance force inhibiting joystick movement as the monitored parameter increases, provide tactile cues (e.g., an MRF-applied feel detent or pulsating effect) when a monitored parameter surpasses a preset threshold, and/or otherwise manipulate the MRF resistance force to provide tactile feedback indicative of the monitored parameter.

In further embodiments, the work vehicle MRF joystick system may vary the MRF resistance force to emulate legacy mechanical control schemes in which a joystick is mechanically linked to an actuated component of the work vehicle, such as a pilot valve included in an EH actuation system. For example, in certain implementations, the controller architecture may utilize sensor data to monitor the pressure conditions or valve positions of an EH actuation system and generate certain resistance effects (e.g., a brief pulse of resistance or feel detent) simulating the tactile feedback inherently provided by legacy systems in which a mechanical connection is provided between an actuated component, such as a pilot valve, and a joystick device. This, in turn, may provide an operator with familiar tactile cues regarding the operational status of the EH system (e.g., when pilot valve lift-off or cracking occurs) in the context of an EH control scheme as opposed to a purely mechanical joystick control scheme. Stated differently, the controller architecture may command the MRF joystick resistance mechanism to selectively vary the MRF resistance force in a manner providing tactile feedback indicating when the pilot valve initially opens during usage of the EH actuation system.

In still other embodiments, the MRF joystick system may vary the MRF resistance force impeding joystick motion as a function of a current monitored machine parameter, such as a current steering angle or ground speed, relative to an operator input command received via a joystick device. As a more specific example, embodiments of the MRF joystick system may progressively increase the MRF resistance force or joystick stiffness to should an operator attempt to rotate (or otherwise move) a joystick in a manner that, if allowed to continue unimpeded, would result in an abrupt change in work vehicle motion. Examples of such work vehicle motions (any or all of which may be controlled utilizing a joystick in embodiments) include work vehicle heading or steering angle, work vehicle ground speed, and movement of a boom-mounted implement. Such an approach of increasing the MRF resistance force inhibiting joystick motion when joystick inputs would result in abrupt work vehicle motions is referred to herein as “trajectory shaping,” as discussed more fully below. Trajectory shaping by selective variations in joystick stiffness may encourage operator joystick movements bringing about relatively seamless or smooth transitions in work vehicle motions. Additionally, such an approach allows operator intent to be confirmed, in passive sense, when an operator exerts sufficient force on the joystick to overcome the increased MRF resistance force to, for example, abruptly change the steering angle or ground speed of the work vehicle.

As indicated above, embodiments of the work vehicle MRF joystick system can also provide a relatively high degree of customization flexibility by, for example, enabling the below-described MRF resistance effects to be tailored to operator preference. In this regard, an operator may be permitted to adjust the intensity of the MRF resistance effect to preference in embodiments; or, perhaps, to selectively activate or deactivate a given MRF resistance effect altogether. In other instances, the MRF joystick system may permit an operator to program the MRF resistance effects by, for example, selecting the particular monitored parameter or parameters upon joystick stiffness is varied. Such personalization or customization settings may be stored in memory and associated with a particular operator in embodiments. Upon work vehicle startup, or at another appropriate juncture during work vehicle operation, the MRF customization settings may then be recalled based upon the identity of the current operator (e.g., as determined by entry of an operator-specific pin when first logging into the work vehicle or as otherwise ascertained) and then applied as appropriate.

An example embodiment of a work vehicle MRF joystick system will now be described in conjunction with FIGS. 1-5. In the below-described example embodiment, the MRF joystick system is principally discussed in the context of a particular type of work vehicle, namely, an excavator. Additionally, in the following example, the MRF joystick system includes two joystick devices, which each have a joystick rotatable about two perpendicular axes and which are utilized to control movement of the excavator boom assembly and the implement or tool (e.g., bucket, grapple, or hydraulic hammer) attached thereto. The following example notwithstanding, the MRF joystick system may include a greater or lesser number of joysticks in further embodiments, with each joystick device movable in any number of DOFs and along any suitable motion pattern or range; e.g., in alternative implementations, a given joystick device may be rotatable about a single axis or, perhaps, movable along a limited (e.g., H-shaped) track or motion pattern. Moreover, the below-described MRF joystick system can be deployed on wide range of work vehicles including joystick-controlled functions, additional examples of which are discussed below in connection with FIG. 6.

Example MRF Joystick System Providing Machine State Feedback

Referring initially to FIG. 1, an example work vehicle (here, an excavator 20) equipped with a work vehicle MRF joystick system 22 is presented. In addition to the MRF joystick system 22, the excavator 20 includes a boom assembly 24 terminating in a tool or implement, such a bucket 26. Various other implements can be interchanged with the bucket 26 and attached to the terminal end of the boom assembly 24 including, for example, other buckets, grapples, and hydraulic hammers. The excavator 20 features a body or chassis 28, a tracked undercarriage 30 supporting the chassis 28, and a cabin 32 located at forward portion of the chassis 28 and enclosing an operator station. The excavator boom assembly 24 extends from the chassis 28 and contains, as principal structural components, an inner or proximal boom 34 (hereafter, “the hoist boom 34”), an outer or distal boom 36 (hereafter, “the dipperstick 36”), and a number of hydraulic cylinders 38, 40, 42. The hydraulic cylinders 38, 40, 42 include, in turn, two hoist cylinders 38, a dipperstick cylinder 40, and a bucket cylinder 42. Extension and retraction of the hoist cylinders 38 rotates the hoist boom 34 about a first pivot joint at which the hoist boom 34 is joined to the excavator chassis 28, here at location adjacent (to the right of) the cabin 32. Extension and retraction of the dipperstick cylinder 40 rotates the dipperstick 36 about a second pivot joint at which the dipperstick 36 is joined to the hoist boom 34. Finally, extension and retraction of the bucket cylinder 42 rotates or “curls” the excavator bucket 26 about a third pivot joint at which the bucket 26 is joined to the dipperstick 36.

The hydraulic cylinders 38, 40, 42 are included in an electrohydraulic (EH) actuation system 44, which is encompassed by a box 46 entitled “actuators for joystick-controlled functions” in FIG. 1. Movements of the excavator boom assembly 24 are controlled utilizing at least one joystick located within the excavator cabin 32 and included in the MRF joystick system 22. Specifically, an operator may utilize the joystick or joysticks included in the MRF joystick system 22 to control the extension and retraction of the hydraulic cylinders 38, 40, 42, as well as to control the swing action of the boom assembly 24 via rotation of the excavator chassis 28 relative to the tracked undercarriage 30. The depicted EH actuation system 44 also contains various other non-illustrated hydraulic components, which may include flow lines (e.g., flexible hoses), check or relief valves, pumps, a, fittings, filters, and the like. Additionally, the EH actuation system 44 contains electronic valve actuators and flow control valves, such as spool-type multi-way valves, which can be modulated to regulate the flow of pressurized hydraulic fluid to and from the hydraulic cylinders 38, 40, 42. This stated, the particular construction or architecture of the EH actuation system 44 is largely inconsequential to embodiments of the present disclosure, providing that the below-described controller architecture 50 is capable of controlling movement of the boom assembly 24 via commands transmitted to selected ones of the actuators 46 effectuating the joystick controlled functions of the excavator 20.

As schematically illustrated in an upper left portion of FIG. 1, the work vehicle MRF joystick system 22 contains one or more MRF joystick devices 52, 54. As appearing herein, the term “MRF joystick device” refers to an operator input device including at least one joystick or control lever, the movement of which can be impeded by a variable resistance force or “stiffness force” applied utilizing an MRF joystick resistance mechanism of the type described herein. While one such MRF joystick device 52 is schematically shown in FIG. 1 for clarity, the MRF joystick system 22 can include any practical number of joystick devices, as indicated by symbol 58. In the case of the example excavator 20, the MRF joystick system 22 will typically include two joystick devices; e.g., joystick devices 52, 54 described below in connection with FIG. 2. The manner in which two such joystick devices 52, 54 may be utilized to control movement of the excavator boom assembly 24 is further discussed below. First, however, a general discussion of the joystick device 52, as schematically illustrated in FIG. 1, is provided to establish a general framework in which embodiments of the present disclosure may be better understood.

As schematically illustrated in FIG. 1, the MRF joystick device 52 includes a joystick 60 mounted to a lower support structure or base housing 62. The joystick 60 is movable relative to the base housing 62 in at least one DOF and may be rotatable relative to the base housing 62 about one or more axes. In the depicted embodiment, and as indicated by arrows 64, the joystick 60 of the MRF joystick device 52 is rotatable relative to the base housing 62 about two perpendicular axes and will be described below as such. The MRF joystick device 52 includes one or more joystick position sensors 66 for monitoring the current position and movement of the joystick 60 relative to the base housing 62. Various other components 68 may also be included in the MRF joystick device 52 including buttons, dials, switches, or other manual input features, which may be located on the joystick 60 itself, located on the base housing 62, or a combination thereof. Spring elements (gas or mechanical), magnets, or fluid dampers may be incorporated into the joystick device 52 to provide a desired rate of return to a home position of the joystick, as well as to fine-tune the desired feel of the joystick 60 perceived by an operator when interacting with the MRF joystick device 52. Such mechanisms are referred to herein as “joystick bias mechanisms” and may be contained within in the MRF joystick device 52 when having a self-centering design. In more complex components, various other components (e.g., potentially including one or more artificial force feedback (AFF) motors) can also be incorporated into the MRF joystick device 52. In other implementations, such components may be omitted from the MRF joystick device 52.

An MRF joystick resistance mechanism 56 is at least partially integrated into the base housing 62 of the MRF joystick device 52. The MRF joystick resistance mechanism 56 (and the other MRF joystick resistance mechanisms mentioned in this document) may also alternatively be referred to as an “MRF damper,” as an “MRF brake device,” or as simply an “MRF device” or “MRF mechanism.” The MRF joystick resistance mechanism 56 can be controlled to adjust the MRF resistance force and, therefore, joystick stiffness resisting joystick motion relative to the base housing 62 in at least one DOF. During operation of the MRF joystick system 22, the controller architecture 50 may selectively command the MRF joystick resistance mechanism 56 to increase the joystick stiffness impeding joystick rotation about a particular axis or combination of axes. As discussed more fully below, the controller architecture 50 may command the MRF joystick resistance mechanism 56 to increase joystick stiffness, when appropriate to perform any one of a number of enhanced joystick functionalities, by increasing the strength of an EM field in which a magnetorheological fluid contained in the MRF joystick resistance mechanism 56 is at least partially immersed. A generalized example of one manner in which the MRF joystick resistance mechanism 56 may be realized is described below in connection with FIGS. 3 and 4.

The excavator 20 is further equipped with any number of onboard sensors 70. Such sensors 70 may include sensors contained in an obstacle detection system, which may be integrated into the excavator 20 in embodiments. The non-joystick input sensors 70 may further include any number and type of boom assembly sensors 72, such as boom assembly tracking sensors suitable for tracking the position and movement of the excavator boom assembly 24. Such sensors can include rotary or linear variable displacement transducers integrated into excavator boom assembly 24 in embodiments. For example, in one possible implementation, rotary position sensors may be integrated into the pivot joints of the boom assembly 24; and the angular displacement readings captured by the rotary position sensors, taken in conjunction with known dimensions of the boom assembly 24 (as recalled from the memory 48), may be utilized to track the posture and position of the boom assembly 24 (including the bucket 26) in three dimensional space. In other instances, the extension and reaction of the hydraulic cylinders 38, 40, 42 may be measured (e.g., utilizing linear variable displacement transducers) and utilized to calculate the current posture and positioning of the excavator boom assembly 24. Other sensor inputs can also be considered by the controller architecture 50 in addition or lieu of the aforementioned sensor readings, such as inertia-based sensor readings; e.g., as captured by inertia sensors, such as MEMS gyroscopes, accelerometers, and possibly magnetometers packaged as IMUs, which are affixed to the excavator 20 at various locations. For example, IMUs can be affixed to the excavator chassis 28 and one or more locations (different linkages) of the excavator boom assembly 24. Vision systems capable of tracking of the excavation implement or performing other functions related to the operation of the excavator 20 may also be included in the onboard board sensors 70 when useful in performing the functions described below.

One or more load measurement sensors, such as weight- or strain-based sensors (e.g., load cells), may further be included in the non joystick sensor inputs 70 in at least some implementations of the work vehicle MRF joystick system 22. In embodiments, such load measurement sensors may be utilized to directly measure the load carried by the bucket 26 (generally, a “load-moving implement” or “load-carrying implement”) at any given time during excavator operation. The load measurement sensors can also measure other parameters (e.g., one or more hydraulic pressures within the EH actuation system 44) indicative of the load carried by the boom assembly 24 in embodiments. In other realizations, the MRF joystick system 22 may be integrated into a work vehicle having a bed or tank for transporting a material, such as the bed of an articulated dump truck. In this latter case, the load measurement sensors included in the sensors 70 may assume the form of payload weighing sensors capable of weighing or approximating the weight of material carried within the bed or tank of the work vehicle at any particular juncture in time.

In embodiments, the work vehicle sensors 70 may further include a number of vehicle motion data sources 74. The vehicle motion data sources 74 can include any sensors or data sources providing information pertaining to changes in the position, speed, heading, or orientation of the excavator 20. Again, MEMS gyroscopes, accelerometers, and possibly magnetometers packaged IMUs can be utilized to detect and measure such changes. Inclinometers or similar sensors may be employed to monitor the orientation of the excavator chassis 28 or portions of the boom assembly 24 relative to gravity in embodiments. The vehicle motion data sources 74 may further include Global Navigation Satellite System (GNSS) modules, such as Global Positioning System (GPS) modules, for monitoring excavator position and motion states. In embodiments, the vehicle motion data sources 74 may also include sensors from which the rotational rate of the undercarriage tracks may be calculated, electronic compasses for monitoring heading, and other such sensors. The vehicle motion data sources 74 can also include various sensors for monitoring the motion and position of the boom assembly 24 and the bucket 26, including MEMS devices integrated into the boom assembly 24 (as previously noted), transducers for measuring angular displacements at the pin joints of the boom assembly, transducers for measuring the stroke of the hydraulic cylinders 38, 40, 42, and the like.

Embodiments of the MRF joystick system 22 may further include any number of other non-joystick components 76 in addition to those previously described. Such additional non-joystick components 76 may include an operator interface 78 (distinct from the MRF joystick device 52), a display device 80 located in the excavator cabin 32, and various other types of non-joystick sensors 82. The operator interface 78, in particular, can include any number and type of non joystick input devices for receiving operator input, such as buttons, switches, knobs, and similar manual inputs external to the MRF joystick device 52. Such input devices included in the operator interface 78 can also include cursor-type input devices, such as a trackball or joystick, for interacting with a graphical user interface (GUI) generated on the display device 80. The display device 80 may be located within the cabin 32 and may assume the form of any image-generating device on which visual alerts and other information may be visually presented. The display device 80 may also generate a GUI for receiving operator input or may include other inputs (e.g., buttons or switches) for receiving operator input, which may be pertinent to the controller architecture 50 when performing the below-described processes. In certain instances, the display device 80 may also have touch input capabilities.

Finally, the MRF joystick system 22 can include various other non-joystick sensors 82, which provide the controller architecture 50 with data inputs utilized in carrying-out the below-described processes. For example, the non-joystick sensors 82 can include sensors for automatically determining the type of implement currently attached to the excavator 20 (or other work vehicle) in at least some implementations when this information is considered by the controller architecture 50 in determining when to increase joystick stiffness to perform certain enhanced joystick functions described herein; e.g., such sensors 82 may determine a particular implement type currently attached to the excavator 20 by sensing a tag (e.g., a radio frequency identification tag) or reading other identifying information present on the implement, by visual analysis of a camera feed capturing the implement, or utilizing any other technique. In other instances, an operator may simply enter information selecting the implement type currently attached to the boom assembly 24 by, for example, interacting with a GUI generated on the display device 80. In still other instances, such other non-joystick sensors 82 may include sensors or cameras capable of determining when an operator grasps or other contacts the joystick 60. In other embodiments, such sensors may not be contained in the MRF joystick system 22.

As further schematically depicted in FIG. 1, the controller architecture 50 is associated with a memory 48 and may communicate with the various illustrated components over any number of wired data connections, wireless data connections, or any combination thereof; e.g., as generically illustrated, the controller architecture 50 may receive data from various components over a centralized vehicle or a controller area network (CAN) bus 84. The term “controller architecture,” as appearing herein, is utilized in a non-limiting sense to generally refer to the processing subsystem of a work vehicle MRF joystick system, such as the example MRF joystick system 22. Accordingly, the controller architecture 50 can encompass or may be associated with any practical number of processors, individual controllers, computer-readable memories, power supplies, storage devices, interface cards, and other standardized components. In many instances, the controller architecture 50 may include a local controller directly associated with the joystick interface and other controllers located within the operator station enclosed by the cabin 32, with the local controller communicating with other controllers onboard the excavator 20 as needed. The controller architecture 50 may also include or cooperate with any number of firmware and software programs or computer-readable instructions designed to carry-out the various process tasks, calculations, and control functions described herein. Such computer-readable instructions may be stored within a non-volatile sector of the memory 48 associated with (accessible to) the controller architecture 50. While generically illustrated in FIG. 1 as a single block, the memory 48 can encompass any number and type of storage media suitable for storing computer-readable code or instructions, as well as other data utilized to support the operation of the MRF joystick system 22. The memory 48 may be integrated into the controller architecture 50 in embodiments as, for example, a system-in-package, a system-on-a-chip, or another type of microelectronic package or module.

Discussing the joystick configuration or layout of the excavator 20 in greater detail, the number of joystick devices included in the MRF joystick system 22, and the structural aspects and function of such joysticks, will vary amongst embodiments. As previously mentioned, although only a single joystick device 52 is schematically shown in FIG. 1, the MRF joystick system 22 will typically two joystick devices 52, 54 supporting excavator boom assembly control. Further illustrating this point, FIG. 2 provides a perspective view from within the excavator cabin 32 and depicting two MRF joystick devices 52, 54 suitably included in embodiments of the MRF joystick system 22. As can be seen, the MRF joystick devices 52, 54 are positioned on opposing sides of an operator seat 86 such that an operator, using both hands, can concurrently manipulate the left MRF joystick device 52 and the right joystick device 54 with relative ease. Carrying forward the reference numerals introduced above in connection with FIG. 1, each joystick device 52, 54 includes a joystick 60 mounted to a lower support structure or base housing 62 for rotation relative to the base housing 62 about two perpendicular axes. The joystick devices 52, 54 also each include a flexible cover or boot 88 joined between a lower portion of the joysticks 60 and their respective base housings 62. Additional joystick inputs are also provided on each joystick 60 in the form of thumb-accessible buttons and, perhaps, as other non-illustrated manual inputs (e.g., buttons, dials, and or switches) provided on the base housings 62. Other notable features of the excavator 20 shown in FIG. 2 include the previously-mentioned display device 80 and pedal/control lever mechanisms 90, 92 for controlling the respective movement of the right and left tracks of the tracked undercarriage 30.

Different control schemes can be utilized to translate movement of the joysticks 60 included in the joystick devices 52, 54 to corresponding movement of the excavator boom assembly 24. In many instances, the excavator 20 will support boom assembly control in either (and often allow switching between) a “backhoe control” or “SAE control” pattern and an “International Standard Organization” or “ISO” control pattern. In the case of the backhoe control pattern, movement of the left joystick 60 to the operator's left (arrow 94) swings the excavator boom assembly 24 in a leftward direction (corresponding to counter-clockwise rotation of the chassis 28 relative to the tracked undercarriage 30), movement of the left joystick 60 to the operator's right (arrow 96) swings the boom assembly 24 in a rightward direction (corresponding to clockwise rotation of the chassis 28 relative to the tracked undercarriage 30), movement of the left joystick 60 in a forward direction (arrow 98) lowers the hoist boom 34, and movement of the left joystick 60 in an aft or rearward direction (arrow 100) raises the hoist boom 34. Also, in the case of the backhoe control pattern, movement of the right joystick 60 to the left (arrow 102) curls the bucket 26 inwardly, movement of the right joystick 60 to the right (arrow 104) uncurls or “opens” the bucket 26, movement of the right joystick 60 in a forward direction (arrow 106) rotates the dipperstick 36 outwardly, and movement of the right joystick 60 in an aft or rearward direction (arrow 108) rotates the dipperstick 36 inwardly. Comparatively, in the case of an ISO control pattern, the joystick motions for the swing commands and the bucket curl commands are unchanged, while the joystick mappings of the hoist boom and dipperstick are reversed. Thus, in the ISO control pattern, forward and aft movement of the left joystick 60 controls the dipperstick rotation in the previously described manner, while forward and aft movement of the right joystick 60 controls motion (raising and lowering) of the hoist boom 34 in the manner described above.

Turning now to FIGS. 3 and 4, an example construction of the MRF joystick device 52 and the MRF joystick resistance mechanism 56 is represented by two simplified cross-sectional schematics. While these drawing figures illustrate a single MRF joystick device (i.e., the MRF joystick device 52), the following description is equally applicable to the other MRF joystick device 54 included in the example MRF joystick system 22. The following description is provided by way of non-limiting example only, noting that numerous different joystick designs incorporating or functionally cooperating with MRF joystick resistance mechanisms are possible. The particular composition of the magnetorheological fluid largely is also inconsequential to embodiments of the present disclosure, providing that meaningful variations in the rheological properties (viscosity) of the magnetorheological fluid occur in conjunction with controlled variations in EM field strength, as described below. For completeness, however, is noted that one magnetorheological fluid composition well-suited for usage in embodiments of the present disclosure contains magnetically-permeable (e.g., carbonyl iron) particles dispersed in a carrier fluid, which is predominately composed of an oil or an alcohol (e.g., glycol) by weight. Such magnetically-permeable particles may have an average diameter (or other maximum cross-sectional dimension if the particles possess a non-spherical (e.g., oblong) shape) in the micron range; e.g., in one embodiment, spherical magnetically-permeable particles are used having an average diameter between one and ten microns. Various other additives, such as dispersants or thinners, may also be included in the magnetorheological fluid to fine-tune the properties thereof.

Referring now to the example joystick construction shown in FIGS. 3 and 4, and again carrying forward the previously-introduced reference numerals as appropriate, the MRF joystick device 52 includes a joystick 60 having at least two distinct portions or structural regions: an upper handle 110 (only a simplified, lower portion of which is shown in the drawing figures) and a lower, generally spherical base portion 112 (hereafter, the “generally spherical base 112”). The generally spherical base 112 of the joystick 60 is captured between two walls 114, 116 of the base housing 62, which may extend substantially parallel to one another to form an upper portion of the base housing 62. Vertically-aligned central openings are provided through the housing walls 114, 116, with the respective diameters of the central openings dimensioned to be less than the diameter of the generally spherical base 112. The spacing or vertical offset between the walls 114, 116 is further selected such that the bulk of generally spherical base 112 is captured between the vertically-spaced housing walls 114, 116 to form a ball-and-socket type joint. This permits rotation of the joystick 60 relative to the base housing 62 about two perpendicular axes, which correspond to the X- and Y-axes of a coordinate legend 118 appearing in FIGS. 3 and 4; while generally preventing translational movement of the joystick 60 along the X-, Y-, and Z-axes of the coordinate legend 118. In further embodiments, various other mechanical arrangements can be employed to mount a joystick to a base housing, while allowing rotation of the joystick about two perpendicular axis, such as a gimbal arrangement. In less complex embodiments, a pivot or pin joint may be provided to permit rotation of the joystick 60 relative to the base housing 62 about a single axis.

The joystick 60 of the MRF joystick device 52 further includes a stinger or lower joystick extension 120, which projects from the generally spherical base 112 in a direction opposite the joystick handle 110. The lower joystick extension 120 is coupled to a static attachment point of the base housing 62 by a single centering or return spring 124 in the illustrated schematic; here noting that such an arrangement is simplified for the purposes of illustration and more complex spring return arrangements (or other joystick biasing mechanisms, if present) will typically be employed in actual embodiments of the MRF joystick device 52. When the joystick 60 is displaced from the neutral or home position shown in FIG. 3, the return spring 124 deflects as shown in FIG. 4 to urge return of the joystick 60 to the home position (FIG. 3). Consequently, as an example, after rotation into the position shown in FIG. 4, the joystick 60 will return to the neutral or home position shown in FIG. 3 under the influence of the return spring 124 should the work vehicle operator subsequently release the joystick handle 110. In other embodiments, the MRF joystick device 52 may not be self-centering and may, instead, assume the form a friction-hold joystick remaining at a particular position absent an operator-applied force moving the joystick from the position.

The example MRF joystick resistance mechanism 56 includes a first and second MRF cylinders 126, 128 shown in FIGS. 3 and 4, respectively. The first MRF cylinder 126 (FIG. 3) is mechanically joined between the lower joystick extension 120 and a partially-shown, static attachment point or infrastructure feature 130 of the base housing 62. Similarly, the second MRF cylinder 128 (FIG. 4) is mechanically joined between the lower joystick extension 120 and a static attachment point 132 of the base housing 62, with the MRF cylinder 128 rotated relative to the MRF cylinder 126 by approximately 90 degrees about the Z-axis of the coordinate legend 118. Due to this structural configuration, the MRF cylinder 126 (FIG. 3) is controllable to selectively resist rotation of the joystick 60 about the X-axis of coordinate legend 118, while the MRF cylinder 128 (FIG. 4) is controllable to selectively resist rotation of the joystick 60 about the Y-axis of coordinate legend 118. Additionally, both MRF cylinders 126, 128 can be jointly controlled to selectively resist rotation of the joystick 60 about any axis falling between the X- and Y-axes and extending within the X-Y plane. In other embodiments, a different MRF cylinder configuration may be utilized and include a greater or lesser number of MRF cylinders; e.g., in implementations in which it is desirable to selectively resist rotation of joystick 60 about only the X-axis or only the Y-axis, or in implementations in which joystick 60 is only rotatable about a single axis, a single MRF cylinder or a pair of antagonistic cylinders may be employed. Finally, although not shown in the simplified schematics, any number of additional components can be included in or associated with the MRF cylinders 126, 128 in further implementations. Such additional components may include sensors for monitoring the stroke of the cylinders 126, 128 if desirably known to, for example, track joystick position in lieu of the below-described joystick sensors 182, 184.

The MRF cylinders 126, 128 each include a cylinder body 134 to which a piston 138, 140 is slidably mounted. Each cylinder body 134 contains a cylindrical cavity or bore 136 in which a head 138 of one of the pistons 138, 140 is mounted for translational movement along the longitudinal axis or centerline of the cylinder body 134. About its outer periphery, each piston head 138 is fitted with one or more dynamic seals (e.g., O-rings) to sealingly engaging the interior surfaces of the cylinder body 134, thereby separating the bore 136 into two antagonistic variable-volume hydraulic chambers. The pistons 138, 140 also each include an elongated piston rod 140, which projects from the piston head 138 toward the lower joystick extension 120 of the joystick 60. The piston rod 140 extends through an end cap 142 affixed over the open end of the cylinder body 134 (again, engaging any number of seals) for attachment to the lower joystick extension 120 at a joystick attachment point 144. In the illustrated example, the joystick attachment points 144 assume the form of pin or pivot joints; however, in other embodiments, more complex joints (e.g., spherical joints) may be employed to form this mechanical coupling. Opposite the joystick attachment points 144, the opposing end of the MRF cylinders 126, 128 are mounted to the respective static attachment points 130, 132 via spherical joints 145. Finally, hydraulic ports 146, 148 are further provided in opposing end portions of each MRF cylinder 126, 128 to allow the inflow and outflow of magnetorheological fluid in conjunction with translational movement or stroking of the pistons 138, 140 along the respective longitudinal axes of the MRF cylinders 126, 128.

The MRF cylinders 126, 128 are fluidly interconnected with corresponding MRF values 150, 152, respectively, via flow line connections 178, 180. As is the case with the MRF cylinders 126, 128, the MRF valves 150, 152 are presented as identical in the illustrated example, but may vary in further implementations. Although referred to as “valves” by common terminology (considering, in particular, that the MRF valves 150, 152 function to control magnetorheological fluid flow), it will be observed that the MRF valves 150, 152 lack valve elements and other moving mechanical parts in the instant example. As a beneficial corollary, the MRF valves 150, 152 provide fail safe operation in that, in the unlikely event of MRF valve failure, magnetorheological fluid flow is still permitted through the MRF valves 150, 152 with relatively little resistance. Consequently, should either or both of the MRF valves 150, 152 fail for any reason, the ability of MRF joystick resistance mechanism 56 to apply resistance forces restricting or impeding joystick motion may be compromised; however, the joystick 60 will remain freely rotatable about the X- and Y-axes in a manner similar to a traditional, non-MRF joystick system, and the MRF joystick device 52 will remain capable of controlling the excavator boom assembly 24 as typical.

In the depicted embodiment, the MRF valves 150, 152 each include a valve housing 154, which contains end caps 156 affixed over opposing ends of an elongated cylinder core 158. A generally annular or tubular flow passage 160 extends around the cylinder core 158 and between two fluid ports 162, 164, which are provided through the opposing end caps 156. The annular flow passage 160 is surrounded by (extends through) a number of EM inductor coils 166 (hereafter, “EM coils 166”), which are wound around paramagnetic holders 168 and interspersed with a number of axially- or longitudinally-spaced ferrite rings 170. A tubular shroud 172 surrounds this assembly, while a number of leads are provided through the shroud 172 to facilitate electrical interconnection with the housed EM coils 166. Two such leads, and the corresponding electrical connections to a power supply and control source 177, are schematically represented in FIGS. 3 and 4 by lines 174, 176. As indicated by arrows 179, the controller architecture 50 is operably coupled to the power supply and control source 177 in a manner enabling the controller architecture 50 to control the source 177 to vary the current supplied to or the voltage applied across the EM coils 166 during operation of the MRF joystick system 22. This structural arrangement thus allows the controller architecture 50 to command or control the MRF joystick resistance mechanism 56 to vary the strength of an EM field generated by the EM coils 166. The annular flow passage 160 extends through the EM coils 166 (and may be substantially co-axial therewith) such that the magnetorheological fluid passes through the center the EM field when as the magnetorheological fluid is conducted through the MRF valves 150, 152.

The fluid ports 162, 164 of the MRF valves 150, 152 are fluidly connected to the ports 146, 148 of the corresponding the MRF cylinders 126, 128 by the above-mentioned conduits 178, 180, respectively. The conduits 178, 180 may be, for example, lengths of flexible tubing having sufficient slack to accommodate any movement of the MRF cylinders 126, 128 occurring in conjunction with rotation of the joystick 60. Consider, in this regard, the example scenario of FIG. 4. In this example, an operator has moved the joystick handle 110 in an operator input direction (indicated by arrow 185) such that the joystick 60 rotates about the Y-axis of coordinate legend 118 in a clockwise direction. In combination with this joystick motion, the MRF cylinder 128 rotates about the spherical joint 145 to tilt slightly upward as shown. Also, along with this operator-controlled joystick motion, the piston 138, 140 contained in the MRF cylinder 128 retracts such that the piston head 138 moves to the left in FIG. 4 (toward the attachment point 132). The translation movement of the piston 138, 140 forces magnetorheological fluid flow through the MRF valve 152 to accommodate the volumetric decrease of the chamber on the left of the piston head 138 and the corresponding volumetric increase of the chamber to the right of the piston head 138. Consequently, at any point during such an operator-controlled joystick rotation, the controller architecture 50 can vary the current supplied to or the voltage across the EM coils 166 to vary the force resisting magnetorheological fluid flow through the MRF valve 152 and thereby achieve a desired MRF resistance force resisting further stroking of the piston 138, 140.

Given the responsiveness of MRF joystick resistance mechanism 56, the controller architecture 50 can control the MRF joystick resistance mechanism 56 to only briefly apply such an MRF resistance force, to increase the strength of the MRF resistance force in a predefined manner (e.g., in a gradual or stepped manner) with increasing piston displacement, or to provide various other resistance effects (e.g., a tactile detent or pulsating effect), as discussed in detail below. The controller architecture 50 can likewise control the MRF joystick resistance mechanism 56 to selectively provided such resistance effects as the piston 138, 140 included in the MRF valve 150 strokes in conjunction with rotation of the joystick 60 about the X-axis of coordinate legend 118. Moreover, the MRF joystick resistance mechanism 56 may be capable of independently varying the EM field strength generated by the EM coils 166 within the MRF valves 150, 152 to allow independent control of the MRF resistance forces impeding joystick rotation about the X- and Y-axes of coordinate legend 118.

The MRF joystick device 52 may further contain one or more joystick position sensors 182, 184 (e.g., optical or non-optical sensors or transformers) for monitoring the position or movement of the joystick 60 relative to the base housing 62. In the illustrated example, specifically, the MRF joystick device 52 includes a first joystick position sensor 182 (FIG. 3) for monitoring rotation of the joystick 60 about the X-axis of coordinate legend 118, and a second joystick position sensor 184 (FIG. 4) for monitoring rotation of the joystick 60 about the Y-axis of coordinate legend 118. The data connections between the joystick position sensors 182, 184 and the controller architecture 50 are represented by lines 186, 188, respectively. In further implementations, the MRF joystick device 52 can include various other non-illustrated components, as can the MRF joystick resistance mechanism 56. Such components can include operator inputs and corresponding electrical connections provided on the joystick 60 or the base housing 62, AFF motors, and pressure and/or flow rate sensors included in the flow circuit of the MRF joystick resistance mechanism 56, as appropriate, to best suit a particular application or usage.

As previously emphasized, the above-described embodiment of the MRF joystick device 52 is provided by way of non-limiting example only. In alternative implementations, the construction of the joystick 60 can differ in various respects. So too may the MRF joystick resistance mechanism 56 differ in further embodiments relative to the example shown in FIGS. 3 and 4, providing that the MRF joystick resistance mechanism 56 is controllable by the controller architecture 50 to selectively apply a resistance force (through changes in the rheology of a magnetorheological fluid) impeding movement of a joystick relative to a base housing in at least one DOF. In further realizations, EM inductor coils similar or identical to the EM coils 166 may be directly integrated into the MRF cylinders 126, 128 to provide the desired controllable MRF resistance effect. In such realizations, magnetorheological fluid flow between the variable volume chambers within a given MRF cylinder 126, 128 may be permitted via the provision of one or more orifices through the piston head 138, by providing an annulus or slight annular gap around the piston head 138 and the interior surfaces of the cylinder body 134, or by providing flow passages through the cylinder body 134 or sleeve itself. Advantageously, such a configuration may impart the MRF joystick resistance mechanism with a relatively compact, integrated design. Comparatively, the usage of one or more external MRF valves, such as the MRF valves 150, 152 (FIGS. 3 and 4), may facilitate cost-effective manufacture and allow the usage of commercially-available modular components in at least some instances.

In still other implementations, the design of the MRF joystick device may permit the magnetorheological fluid to envelop and act directly upon a lower portion of the joystick 60 itself, such as the spherical base 112 in the case of the joystick 60, with EM coils positioned around the lower portion of the joystick and surrounding the magnetological fluid body. In such embodiments, the spherical base 112 may be provided with ribs, grooves, or similar topological features to promote displacement of the magnetorheological fluid in conjunction with joystick rotation, with energization of the EM coils increasing the viscosity of the magnetorheological fluid to impede fluid flow through restricted flow passages provided about the spherical base 112 or, perhaps, due to sheering of the magnetorheological fluid in conjunction with joystick rotation. Various other designs are also possible in further embodiments of the MRF joystick system 22.

Regardless of the particular design of the MRF joystick resistance mechanism 56, the usage of MRF technology to selectively generate a variable MRF resistance force or joystick stiffness impeding (resisting or preventing) targeted joystick motions provides several advantages. As a primary advantage, the MRF joystick resistance mechanism 56 (and MRF joystick resistance mechanism generally) are highly responsive and can effectuate desired changes in EM field strength, in the rheology of the magnetorheological fluid, and ultimately in the MRF-applied joystick stiffness impeding joystick motions in highly abbreviated time periods; e.g., time periods on the order of 1 millisecond in certain instances. Correspondingly, the MRF joystick resistance mechanism 56 may enable the MRF resistance force to be removed (or at least greatly reduced) with an equal rapidity by quickly reducing current flow through the EM coils and allowing the rheology of the magnetorheological fluid (e.g., fluid viscosity) to revert to its normal, unstimulated state. The controller architecture 50 can further control the MRF joystick resistance mechanism 56 to generate the MRF resistance force to have a continuous range of strengths or intensities, within limits, through corresponding changes in the strength of the EM field generated utilizing the EM coils 166. Beneficially, the MRF joystick resistance mechanism 56 can provide reliable, essentially noiseless operation over extended time periods. Additionally, the magnetorheological fluid can be formulated to be non-toxic in nature, such as when the magnetorheological fluid contains carbonyl iron-based particles dispersed in an alcohol-based or oil-based carrier fluid, as previously described. Finally, as a still further advantage, the above-described configuration of the MRF joystick resistance mechanism 56 allows the MRF joystick system 22 to selectively generate a first resistance force or joystick stiffness deterring joystick rotation about a first axis (e.g., the X-axis of coordinate legend 118 in FIGS. 3 and 4), while further selectively generating a second resistance force or joystick stiffness deterring joystick rotation about a second axis (e.g., the Y-axis of coordinate legend 118) independently of the first resistance force (joystick stiffness); that is, such that the first and second resistance forces have different magnitudes, as desired.

Advancing next to FIG. 5, presented is an example process 190 suitably carried-out by the controller architecture 50 of the above-described MRF joystick system 22 to vary one or more MRF resistance forces selectively impeding joystick motion in a manner providing machine state feedback pertaining to a work vehicle, such as the example excavator 20 described above in connection with FIGS. 1 and 2. The illustrated example process 190 (hereafter, the “MRF machine state feedback process 190”) includes a number of process STEPS 192, 194, 196, 198, 200, 202, 204, 206, each of which is described, in turn, below. Depending upon the particular manner in which the MRF machine state feedback process 190 is implemented, each step generically illustrated in FIG. 5 may entail a single process or multiple sub-processes. Further, the steps illustrated in FIG. 5 and described below are provided by way of non-limiting example only. In alternative embodiments of the MRF machine state feedback process 190, additional process steps may be performed, certain steps may be omitted, and/or the illustrated process steps may be performed in alternative sequences.

The MRF machine state feedback process 190 commences at STEP 192 in response to the occurrence of a predetermined trigger event. In embodiments, the trigger event can be startup of a work vehicle (e.g., the excavator 20 shown in FIGS. 1 and 2) or, instead, entry of operator input requesting activation of a particular joystick feedback mode. For example, in embodiments, an operator may interact with a GUI generated on the display device 80 to active a desired feedback mode as a user-selectable option, possibly selected from a list of user-selectable options. In such embodiments, such a GUI may also permit the operator to adjust the intensity or other aspects of the MRF resistance force to preference, to select the monitored parameter correlated to variations in joystick stiffness, and/or to selectively deactivate such MRF-applied variations in joystick stiffness, as previously discussed. In further implementations of the process 190, the MRF machine state feedback process 190 may commence in response to a different trigger event, such as detection of a pertinent mode of operation on behalf of the work vehicle; e.g., in embodiments in which the MRF resistance force is varied in response to changes in work vehicle ground speed or to achieve trajectory shaping, as further discussed below, the MRF machine state feedback process 190 may commence when the work vehicle is piloted utilizing one or more MRF joystick devices or, perhaps, when the ground speed of the work vehicle surpasses a predetermined threshold. Similarly, in embodiments in which the MRF resistance force is varied in response to changes in a monitored load, the process 190 may commence when a monitored load of the work vehicle surpasses a preset minimum threshold value.

Following commencement of the MRF machine state feedback process 190, the controller architecture 50 progresses to STEP 194 and collects the pertinent data inputs subsequently utilized to determine the appropriate variations in the MRF resistance force or forces resisting joystick motion in one or more DOFs. The particular data inputs gathered during STEP 194 will vary in relation to the parameter or parameters correlated to the variable joystick stiffness, as discussed more fully below in connection with STEPS 204, 206 of the MRF machine state feedback process 190. Generally, iterations of the process 190 may be performed at a relatively rapid rate such that the data inputs collected during STEP 194 may reflect real-time or near real-time data provided by one or more sensors onboard the work vehicle, such as any of the sensors 70 of the above-described example excavator 20. Stored data may also be recalled from memory (e.g., the memory 48 shown in FIG. 1) by the controller architecture 50, as needed, to determine the appropriate MRF resistance force correlated to the monitored parameter or sensor data. For example, in embodiments, multi-dimensional lookup tables, characteristics or formulae, or a similar data structures may be recalled from the memory 48 and utilized to determine the appropriate MRF resistance force adjustments based upon the real-time data received from one or more sensors included within the onboard sensors 70. So too may any operator preference settings, such as desired MRF resistance force intensity settings, be recalled from the memory 48 and considered during STEPS 204, 206 of the process 190.

Next, at STEP 196 of the MRF machine state feedback process 190, the controller architecture 50 receives data indicative of the current joystick movement and position of the MRF joystick device (or devices) under consideration. In the case of the example excavator 20, the controller architecture 50 receives data from the joystick position sensors 182, 184 contained in the MRF joystick devices 52, 54 regarding the movement of the respective joysticks 60 included in the devices 52, 54. Such data enables the controller architecture 50 to rapidly increase or decrease the MRF resistance force inhibiting joystick movement (e.g., joystick rotation about a particular axis) in correlation to the current joystick position and movement characteristics. This, in turn, enables the MRF resistance force to progressively increase, to progressively decrease, to be quickly applied, or to be quickly removed, as needed, to generate the desired MRF resistance effects.

Progressing to STEP 202 of the MRF machine state feedback process 190, the controller architecture 50 determines whether joystick position or the monitored machine state correlated to joystick stiffness has changed in a manner warranting variations in the currently-applied MRF resistance force and, therefore, the joystick stiffness resisting joystick motion in a particular direction. If this is the case, the controller architecture 50 progresses to STEP 204 of the MRF machine state feedback process 190, as further described below. Otherwise, the controller architecture 50 advances to STEP 200 and determines whether the current iteration of the MRF machine state feedback process 190 should terminate; e.g., due to work vehicle shutdown, due to continued inactivity of the joystick-controlled function for a predetermined time period, or due to removal of the condition or trigger event in response to which the process 190 initially commenced. If determining that the MRF machine state feedback process 190 should terminate at STEP 200, the controller architecture 50 progresses to STEP 202 of the process 190, the MRF machine state feedback process 190 terminates accordingly. If instead determining that the process 190 should continue, the controller architecture 50 returns to STEP 194 and the above-described process steps repeat.

As previously indicated, the controller architecture 50 advances to STEP 204 when determining that joystick position or the monitored machine state correlated to MRF joystick stiffness has changed based upon the data inputs collected during STEPS 194, 196 of the MRF machine state feedback process 190. During STEP 204, the controller architecture 50 determines the appropriate manner in which to vary the MRF resistance force to achieve a desired joystick stiffness indicative of the monitored machine state or parameter. The controller architecture 50 then advances to STEP 206 and applies the newly-determined MRF resistance force by transmitting appropriate commands to the MRF joystick resistance mechanism 56 to vary the rheology (viscosity) of the MRF fluid body (or bodies) in a manner achieving the desired resistance effect. As discussed throughout this document, such effects are correlated to joystick position and, thus, may be temporarily applied to generate detent effects or pulsating effects; the MRF resistance force may be progressively increased or otherwise varied to substantially match increases in a monitored parameter (e.g., a ground speed, a component position, a load, or a hydraulic pressure of the work vehicle); or the MRF resistance force may be lessened or removed when appropriate based upon joystick movement and the state of the monitored parameter. After application of the determined adjustments to the MRF resistance force inhibiting joystick motion in at least one DOF, the controller architecture 50 then progresses to STEP 200 and determines whether the current iteration of the MRF machine state feedback process 190 should terminate, as previously discussed. In this manner, the controller architecture 50 may repeatedly perform iterations of the process 190 to actively vary the MRF resistance force impeding or resisting joystick motion in at least one DOF, such as joystick rotation about one or more axes, to provide a work vehicle operator with tactile feedback indicative of a monitored parameter pertaining to work vehicle as the operator interacts with a MRF joystick device, such as MRF joystick device 52 discussed above in connection with FIGS. 1-4.

Discussing now STEP 204 of the MRF machine state feedback process 190 in greater detail, several example machine state parameters 208, 210, 212, 214, 215 are identified for which the MRF joystick system 22 may provide tactile feedback via selectively variations in the MRF stiffness force or forces resisting joystick movement. The illustrated machine state parameters 208, 210, 212, 214, 215 are provided by way of non-limiting example only and are each described, in turn, below. Initially addressing the parameter entitled “work vehicle load” (parameter 208, FIG. 5), embodiments of the work vehicle MRF joystick system 22 may vary the MRF force resistance inhibiting joystick movement as a function of any particular load, which is placed on the work vehicle and which is monitored (directly or indirectly) utilizing one or more sensors onboard the work vehicle. In embodiments in which a work vehicle is equipped with a movable implement, such as a movable blade or a boom-mounted implement, the controller architecture 50 may estimate a load force resisting movement of the implement in at least one direction and increase the joystick stiffness (through continuous or stepwise increases in the MRF resistance force) as the variable load placed on the work increases.

In embodiments, the monitored work vehicle load may be any variable force resisting movement of a component of the work vehicle in some manner. For example, the monitored load may be the mass or weight of a material weight borne by load-carrying component of the work vehicle; the term “load-carrying component” encompassing buckets, grapples, bale spears, feller heads, lifts, and other such tools or implements commonly attached to work vehicles and utilized to transport materials or objects from one location to another. Such load forces resisting movement of a movable implement may also forces encountered during excavation operations as, for example, hardened regions of earth or other difficult-to-displace regions are encountered by a tool (e.g., a trencher, a hydraulic hammer, or a bucket). In each of these scenarios, the controller architecture 50 may estimate the load resisting implement movement in any given direction or combination of directions and then command the MRF joystick resistance mechanism 56 to vary the MRF resistance force accordingly; e.g., such that the MRF resistance force inhibiting joystick movement increases in conjunction with increases in the force resisting implement movement in a given direction. Similarly, in embodiments in which the work vehicle comprises a load-carrying receptacle, such as a bucket, tank, or bed, the MRF joystick system may increase the MRF resistance force with as the weight of the material held within the load-carrying receptacle (herein, the “fill weight”) increases. Such increases the MRF resistance force may be implemented in a stepwise fashion or, instead, in a substantially continual fashion (over a given resistance range) such that, for example, the MRF resistance force progressively increases in substantial portion to increases in the monitored load. In other implementations, different MRF-applied tactile cues (e.g., feel detents) may be generated when a load placed on the work vehicle surpasses or becomes equivalent to a predetermined threshold, such as in the case of the below-described tipoff assist function.

The above-described variations in the MRF resistance force can be axis-specific or direction-specific in embodiments in which the MRF joystick device is capable of rotational about perpendicular axes, such as in the case of the joystick device 52 shown in FIGS. 1-4. Consider, for example, an example in which the MRF resistance force or joystick stiffness is varied in proportion to the fill load contained in the bucket of a wheel loader, such as the wheel loader 216 discussed below in connection with FIG. 6. In this example, the controller architecture 50 may selectively increase the MRF resistance force in response to joystick rotations (as detected during STEP 196 of the process 190) moving the joystick in forward and aft directions to lower and raise the FEL bucket, respectively, while leaving joystick rotations about the opposing axis (moving the joystick handle to the left and right) curling and uncurling the bucket unhindered. Similarly, in embodiments, only joystick motions raising the FEL bucket may be impeded by an increased MRF resistance force as the estimated bucket load increases to impart an operator with an intuitive sense of the relatively heavy load carried by the bucket. Axis-specific or direction-specific variations in MRF resistance force can also be applied based upon the work vehicle function controlled by the work vehicle. For example, in the case of a work vehicle equipped with a hinged boom assembly, such as the excavator 20 shown in FIGS. 1-2, calculations may be carried-out by the controller architecture 50 utilizing the current estimated position and posture of the hinged boom assembly to estimate the load placed on the boom assembly-mounted implement (e.g., the bucket 26) at a given moment of time, based upon the boom assembly posture relative to the direction gravity; e.g., as monitored utilizing a MEMS gyroscope, an inclinometer, or a similar sensor onboard the work vehicle. Consequently, in such instances, the controller architecture 50 may generate MRF resistance forces to selectively impede joystick movements raising the bucket 26 load against gravity, while providing little to no MRF resistance force impediment to joystick inputs moving the bucket in a plane orthogonal to the direction of gravity (e.g., by swinging the boom assembly 24) and providing little to no impediment (or perhaps further reducing any MRF resistance force) to actions moving the bucket downwardly in the direction of gravity.

In embodiments in which the work vehicle includes an EH actuation system, the MRF joystick system may increase the MRF resistance force in conjunction with variations in a circuit pressure within the EH actuation system. For example, with respect to the example excavator 20 discussed above in connection with FIGS. 1 and 2, the controller architecture 50 may monitor at least one pressure (or a pressure differential) within a flow circuit of the EH actuation system 44 and increase an MRF resistance force inhibiting joystick motion in at least one DOF in conjunction with increasing circuit pressures. In this regard, the controller architecture 50 may independently vary the MRF resistance force impeding joystick motions controlling different hydraulic cylinders based on, for example, the estimated pressure or load of the cylinders utilized to control the boom assembly; e.g., the cylinders 38, 40, 42 shown in FIG. 1 utilized to animate the excavator boom assembly 24. For example, as the pressure supplied to the hydraulic hoist cylinders 38 increases, so too may the controller architecture 50 increase the MRF resistance force inhibiting joystick motions causing further pressure increases of the hydraulic fluid supplied to the cylinders 38; e.g., joystick motion causing further extension of the cylinders 38 raising the hoist boom 34 in instances in which the bucket 26 is heavily loaded or, conversely, joystick motion causing retraction of the cylinders 38 lowering the hoist boom 34 in instances in which the end effector (e.g., a hydraulic hammer) attached to the terminal end of the boom assembly 24 is pressed downwardly against a surface or material with increasingly greater force.

In further implementations, the MRF joystick system 22 may vary the MRF resistance force impeding joystick movement in at least one direction as a function of another type of load placed on the work vehicle, such as a current load placed on the primary (e.g., internal combustion) engine of a work vehicle engine. Additionally, while the previous description principally focuses on altering the MRF resistance force based upon variations on monitored work vehicle loads considered in isolation or an independent sense, further embodiments of the MRF joystick system 22 may adjust the MRF resistance force based upon changes in load (or another monitored work vehicle parameter mentioned herein) relative to another parameter or threshold value. For example, in certain embodiments, the controller architecture 50 may compare a monitored load to a predetermined threshold value (e.g., a particular minimum load value stored in the memory 48) and implement the above-described MRF resistance force modifications only after a currently monitored load surpasses the threshold value. A similar approach may be utilized to assist operators in piloting a work vehicle to bring a load, such as the fill weight of a bucket, to a desired value, as in the case of a tipoff assist or control function described in the following paragraph.

Embodiments of the MRF joystick system 22 may monitor a current fill weight of an end effector or load-carrying implement and vary the MRF resistance force based of a differential between a target tipoff weight and the current fill weight of the implement, task. In this regard, certain work vehicle, such as wheel loaders, excavators, and similar work vehicle equipped with fillable buckets, may be provided with a tipoff control function, which assists an operator in utilizing the work vehicle to fill a receptacle (e.g., a bed of a dump truck) with a desired quantity of material. In this case, the MRF joystick system may estimate the amount of material (e.g., by weight) utilizing any of the methods described herein (e.g., using a strain gauge, a load sensor, or any number of pressure sensors) and then utilize this information in determining the manner in which to apply variances in the MRF joystick stiffness, thereby communicating to the operator that an appropriate amount of material is within the bucket to satisfy the established weight target of the dump truck (or other receptacle). With respect to the example excavator 20, in particular, the controller architecture 50 may first establish a target tipoff weight to which the bucket 26 is desirably filled; e.g., by recalling from memory 48 a default setting or a setting entered into the excavator computer via operator interface 78. The controller architecture 50 may then selectively vary the MRF resistance force based of a differential between the target tipoff weight and the current fill weight of the bucket 26, as previously described. Such an MRF joystick response may be generated when first filling the bucket 26 (e.g., by increasing joystick stiffness, by providing a detent effect, or by providing pulsating effect) when a target bucket load is achieved. In other instances, the MRF joystick system may provide similar tactile cues assisting an operator with dumping-out an appropriate amount of material to satisfy the target bucket load if the bucket 26 is inadvertently over-filled by the operator when piloting the work vehicle.

With continued reference to STEP 204 of the example MRF machine state feedback process 190 (FIG. 5), the controller architecture 50 may further vary the MRF resistance force and, therefore, joystick stiffness based upon work vehicle ground speed in certain instances (parameter 210). In one possible approach, the controller architecture 50 may selectively increase the MRF resistance force impeding joystick motion in directions utilized to control vehicle steering at higher vehicle speeds, with such an increase potentially performed gradually (continually) or in a stepwise fashion with any number of discrete resistance increase intervals. Such ground-speed depend increases in joystick stiffness may be applicable to the example excavator 20 when operable in a travel mode in which the heading and, perhaps, the ground speed of the excavator 20 can be controlled utilizing the above-described joystick devices 52, 54 (FIG. 2). Further, the MRF resistance force may be increased about the rotational axis corresponding to steering of the excavator 20 in embodiments; and, perhaps, also the rotational axis corresponding to acceleration and deceleration of the excavator 20 (in which case such progressive increases in the MRF resistance force may be provided only in the direction of joystick rotation causing the excavator to accelerate). Such an approach is also usefully applied (and, perhaps, may be even more beneficial) in the case of work vehicles capable of traveling at higher ground speeds and/or in the case of work vehicles exclusively propelled in response to joystick controls, such as the example SSL 218 described below in connection with FIG. 6. Generally, increasing MRF joystick resistance at higher vehicle speeds may advantageously improve the precision with which an operator may steer the work vehicle and provide a better indicator of operator intent as an operator need overcome a greater force to move the joystick in an intended manner (thus reducing the likelihood of inadvertent joystick motions due to oscillations or other effects in the presence of high vibratory forces often occurring during work vehicle travel).

In still further implementations of the work vehicle MRF joystick system 22, and as indicated in FIG. 5 by parameter 212, the controller architecture 50 may selectively vary the MRF resistance force and, therefore, the joystick stiffness for trajectory shaping purposes. Specifically, in such embodiments, the controller architecture 50 may vary the MRF resistance force as a function of the curve or profile followed by the work vehicle when transitioning from a current motion state (e.g., work vehicle ground speed or steering angle) to an operator-commanded motion state (e.g., a new work vehicle speed or steering angle) when immediate transition to the operator commanded state cannot be achieved or would be undesirable; e.g., would cause the work vehicle to lurch forward or to abruptly stop in the case of acceleration or deceleration, or would cause the work vehicle to drastically change heading (and potentially become unstable) at higher ground speeds. Accordingly, if the operator attempts to move the joystick in a manner that would cause such an undesirably abrupt change in a machine state (e.g., abrupt acceleration, deceleration, or turning of the work vehicle), perhaps rapidly moving the joystick from a neutral position to the end of its travel in a given direction, the MRF joystick system 22 may progressively increase the joystick stiffness as the joystick rapidly moves from the neutral toward its end of travel (as indicated by the joystick rate of change). This may provide a better indicator if the operator truly intends to command such an undesirably abrupt change in the machine's motion state (improving the relationship between operator expectation and machine behavior) and will better align actual machine performance with joystick motion. This may also be described as configuring the controller architecture 50 to (i) determine when motion of the joystick in an operator input direction at a detected rate will result in an undesirably abrupt change in the current motion state of the work vehicle; and (ii) when so determining, commanding the MRF joystick resistance mechanism to increase the MRF resistance force to impede continued movement of the joystick in the operator input direction. A similar approach can also be utilized to promote smooth movement or “trajectory shaping” of a joystick-controlled boom assembly, such as the boom assembly 24 of the example excavator 20 shown in FIGS. 1 and 2.

In still embodiments of the work vehicle MRF joystick system 22, and as indicated by the example parameter 214 at STEP 204 of the MRF machine state feedback process 190 (FIG. 4), the controller architecture 50 may monitor the movement of one or more movable components of a work vehicle relative to its range of travel; and, then, provide tactile feedback or cues via MRF resistance force variations as the moveable component approaches the end of its range of travel (herein, a “motion stop point” or a “motion stop”). Such a moveable component can be, for example, an articulable joint of a work vehicle (e.g., a pin pivot joint of a boom assembly) or a hydraulic cylinder having a stroke limit or an articulable joint of a boom assembly. To provide a more specific example, and referring once again to the excavator 20 (FIGS. 1 and 2) as the movement of a boom assembly 24 nears the end of its range of motion in a particular DOF, or as one or more of the hydraulic cylinders 38, 40, 42 nears their respective stroke range limits, the controller architecture 50 may vary the MRF resistance force inhibiting joystick rotation about an axis corresponding to movement of the component in a manner conveying to an operator (through tactile feedback) that the component is approaching a motion stop. Such feedback may be provided by progressively increasing the MRF resistance force resisting joystick motion commanding movement of the moveable component (e.g., extension or retraction of a hydraulic cylinder) toward its end of travel. Alternatively, a pulsating effect or a brief detent effect may be generated ahead of the moveable component reaching its end of travel; e.g., when a set percentage (e.g., 5%) of the stroke range of a hydraulic cylinder or cylinder pair remains as the cylinder(s) extend or retract in accordance with joystick commands. By providing such MRF-applied tactile feedback through variations in joystick stiffness, operator awareness when a particular joystick-controlled component approaches its end of travel may be enhanced. Concurrently, a soft stop effect is created to help cushion or reduce shock forces that may otherwise be generated when the work vehicle part or assembly reaches its end of travel. A similar approach may also be utilized when approaching other limits of the work vehicle, such as when the EH actuation system 44 approaches a stall condition in response to operator commands entered via one or more MRF joystick devices.

In still further embodiments, the MRF joystick system 22 may selectively vary the MRF resistance force inhibiting joystick motion in at least one DOF in a manner mimicking legacy systems familiar to operators, as indicated by parameter 215 listed in STEP 204 of the MRF machine state feedback process 190 (FIG. 4). In this regards, certain operators may be accustomed to interaction with mechanical joysticks having direct mechanical connections to the hydraulic valves (e.g., pilot valves or spools) within an EH actuation system 22 may be disconcerted by the lack of such a direct “feel” connection when utilizing an EH joystick, which converts joystick motions to electrical signals transmitted to valve solenoids or other actuators to perform such functions. Embodiments of the MRF joystick system 22 can advantageously retain the versatility and other benefits of EH control schemes, while selectively generating joystick behaviors mimicking purely mechanical system 22s. As previously alluded to, this may be accomplished by increasing the MRF resistance force, and thus increase joystick stiffness, as a function of hydraulic pressures within the EH actuation system 22. Similarly, the controller architecture 50 may control the MRF joystick resistance mechanism to simulate lift-off or cracking of a (e.g., pilot) valve with the EH actuation system 22 by, for example, initially generating a higher MRF resistance force as a joystick is first displaced in a given direction (the operator input direction) and then rapidly decreasing the MRF resistance force after movement of the joystick over a short range of travel in the operator input direction. Various other effects can likewise be generated utilizing the MRF joystick system 22 to mimic other mechanical control characteristics or otherwise provide operators with a more uniform experience when transitioning from a mechanical joystick to an EH joystick control scheme.

In the above-described manner, embodiments of the MRF joystick system 22 may provide operators with tactile feedback indicative of current machine states or parameters through selective increases in the MRF resistance force impeding joystick movement in at least one DOF. Such feedback is provided to an operator interacting with the above-described MRF joystick devices in a highly intuitive and rapid manner. Further benefits are achieved through the usage of MRF technology itself as opposed to the usage of other resistance mechanisms, such as actuated friction or brake mechanisms, also capable of selectively impeding joystick motion when returning to a centered position after displacement therefrom. Such benefits may include highly abbreviated response times; minimal frictional losses in the absence of MRF-applied resistance forces; reliable, essentially noiseless operation; and other benefits as further discussed below. Additionally, embodiments of the below-described MRF joystick resistance mechanism may be capable of generate a continuous range of resistance forces over a resistance force range in relatively precise manner and in accordance with commands or control signals issued by the controller architecture 50. While the foregoing description principally focuses on a particular type of work vehicle (an excavator) including a particular joystick-controlled work vehicle function (boom assembly movement), embodiments of the MRF joystick system 22 described herein are amenable to integration into a wide range of work vehicles, as further discussed below in connection with FIG. 6.

Additional Examples of Work Vehicles Beneficially Equipped with MRF Joystick Systems

Turning now to FIG. 6, additional examples of work vehicles into which embodiments of the MRF joystick system may be beneficially incorporated are illustrated. Specifically, and referring initially to the upper portion of this drawing figure, three such work vehicles are shown: a wheeled loader 216, a skid steer loader (SSL) 218, and a motor grader 220. Addressing first the wheeled loader 216, the wheeled loader 216 may be equipped with an example MRF joystick device 222 located within the cabin 224 of the wheeled loader 216. When provided, the MRF joystick device 222 may be utilized to control the movement of a FEL 226 terminating in a bucket 228; the FEL 226, and front end loaders generally, considered a type of “boom assembly” in the context of this document. Comparatively, two MRF joystick devices 230 may be located in the cabin 232 of the example SSL 218 and utilized to control not only the movement of the FEL 234 and its bucket 236, but further control movement of the chassis 238 of the SSL 218 in the well-known manner. Finally, the motor grader 220 likewise includes two MRF joystick devices 240 located within the cabin 242 of the motor grader 220. The MRF joystick devices 240 can be utilized to control the movement of the motor grader chassis 244 (through controlling a first transmission driving the motor grader rear wheels and perhaps a second (e.g., hydrostatic) transmission driving the forward wheels), as well as movement of the blade 246 of the motor grader; e.g., through rotation of and angular adjustments to the blade-circle assembly 248, as well as adjustments to the side shift angle of the blade 246.

In each of the above-mentioned examples, the MRF joystick devices can be controlled to provide machine state feedback through intelligent MRF-applied variations in joystick stiffness. In this regard, any or all of the example wheeled loader 216, the SSL 218, and the motor grader 220 can be equipped with a work vehicle MRF joystick system including at least one joystick device, an MRF joystick resistance mechanism, and a controller architecture. Finally, still further examples of work vehicles usefully equipped with embodiments of the MRF joystick systems described herein are illustrated in a bottom portion of FIG. 6 and include an FEL-equipped tractor 250, a feller buncher 252, a skidder 254, a combine 256, and a dozer 258. In each case, the MRF joystick devices can selectively vary the MRF resistance force impeding joystick motion in at least one DOF to provide tactile feedback indicative of a monitored parameter pertaining to work vehicle at issue. Again, such parameters can include work vehicle loads, ground speeds, and proximity of movable work vehicle component to motion stops. Variations in the MRF resistance force can also be utilized to simulate legacy systems (e.g., to provide tactile feedback indicative of pilot valve lift-off) and/or to discourage (or to ensure operator intent in inducing) joystick motions bringing about relatively abrupt changes in motion states of the work vehicles, as previously discussed.

Enumerated Examples of the Work Vehicle MRF Joystick System

The following examples of the work vehicle MRF joystick system are further provided and numbered for ease of reference.

1. In embodiments, a work vehicle MRF joystick system includes a joystick device, an MRF joystick resistance mechanism, a controller architecture, and a work vehicle sensor configured to provide sensor data indicative of an operational parameter pertaining to work vehicle. The joystick device includes, in turn, a base housing, a joystick movably mounted to the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The MRF joystick resistance mechanism is controllable to vary an MRF resistance force resisting movement of the joystick relative to the base housing in at least one degree of freedom. Coupled to the joystick position sensor, to the work vehicle sensor, and to the MRF joystick resistance mechanism, the controller architecture is configured to: (i) monitor for variations in the operational parameter utilizing the sensor data; and (ii) provide tactile feedback through the joystick device indicative of the operational parameter by selectively commanding the MRF joystick resistance mechanism to adjust the MRF resistance force impeding joystick movement based, at least in part, on variations in the operational parameter.

2. The work vehicle MRF joystick system of example 1, wherein the operational parameter is a hydraulic load placed on the work vehicle, while the controller architecture is configured to command the MRF joystick resistance mechanism to selectively increase the MRF resistance force with as the hydraulic load increases.

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

4. The work vehicle MRF joystick system of example 1, wherein the work vehicle includes a load-carrying component, the operational parameter is a material weight borne by load-carrying component, and the controller architecture is configured to command the MRF joystick resistance mechanism to selectively increase the MRF resistance force with as the material weight increases.

5. The work vehicle MRF joystick system of example 4, wherein the load-carrying component of the work vehicle includes a boom-mounted implement, while the controller architecture is configured to increase the MRF resistance force in a manner impeding joystick movements raising the boom-mounted implement.

6. The work vehicle MRF joystick system of example 4, wherein the load-carrying component includes a receptacle of the work vehicle, while the operational parameter is a payload weight held by the receptacle.

7. The work vehicle MRF joystick system of example 1, wherein the work vehicle includes a bucket, and the work vehicle sensor is configured to monitor a current fill weight of the bucket. The controller architecture is configured to: (i) establish a target tipoff weight to which the bucket is desirably filled, and (ii) selectively vary the MRF resistance force based of a differential between the target tipoff weight and the current fill weight of the bucket.

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

9. The work vehicle MRF joystick system of example 8, wherein the MRF resistance force impedes joystick movement controlling at least one of work vehicle heading and work vehicle ground speed.

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

11. The work vehicle MRF joystick system of example 10, wherein the movable component includes a hydraulic cylinder having a stroke limit or an articulable joint of a boom assembly.

12. The work vehicle MRF joystick system of example 1, wherein the work vehicle includes an EH actuation system containing a pilot valve, while the controller architecture is configured to command the MRF joystick resistance mechanism to selectively vary the MRF resistance force in a manner providing tactile feedback indicating when the pilot valve initially opens.

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

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

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

CONCLUSION

The foregoing has thus provided work vehicle MRF joystick systems configured to provide machine state feedback through variations in MRF resistance force. Such parameters can include, for example, various loads applied to the work vehicle, ground speed of the work vehicle, and proximity of movable work vehicle component to motion stops. Further, in some embodiments, the MRF joystick system may vary an MRF resistance force impeding joystick motion in a manner simulating legacy systems in which a mechanical linkage is provided between a joystick and an actuated component, such as a pilot valve. In still other implementations in which the joystick device is utilized to control movement of the work vehicle, such as ground speed, heading, or boom assembly movements, the MRF joystick system may increase the MRF resistance force to discourage (or to confirm operator intent) joystick motions resulting in relatively abrupt changes in the current motion state of the work vehicle. In so doing, embodiments of the MRF joystick systems intuitively provide tactile feedback enhancing operator awareness of key parameters or conditions of the work vehicle to improve operator satisfaction levels, improve efficacy in utilizing the work vehicle to perform various works tasks, and to provide other benefits, such as minimizing component wear in instances in which abrupt changes in work vehicle motion are reduced.

As used herein, the singular forms “a”, “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. Explicitly referenced embodiments herein were chosen and described in order to best explain the principles of the disclosure and their practical application, and to enable others of ordinary skill in the art to understand the disclosure and recognize many alternatives, modifications, and variations on the described example(s). Accordingly, various embodiments and implementations other than those explicitly described are within the scope of the following claims.

Claims

1. A work vehicle magnetorheological fluid (MRF) joystick system utilized onboard a work vehicle, the work vehicle MRF joystick system comprising:

a joystick device, comprising: a base housing; a joystick movably mounted to the base housing; and a joystick position sensor configured to monitor movement of the joystick relative to the base housing;
an MRF joystick resistance mechanism controllable to vary an MRF resistance force impeding joystick movement relative to the base housing in at least one degree of freedom;
a work vehicle sensor configured to provide sensor data indicative of an operational parameter pertaining to work vehicle; and
a controller architecture coupled to the joystick position sensor, to the MRF joystick resistance mechanism, and to the work vehicle sensor, the controller architecture configured to: monitor for variations in the operational parameter utilizing the sensor data; and provide tactile feedback through the joystick device indicative of the operational parameter by selectively commanding the MRF joystick resistance mechanism to adjust the MRF resistance force based, at least in part, on variations in the operational parameter.

2. The work vehicle MRF joystick system of claim 1, wherein the operational parameter comprises a hydraulic load placed on the work vehicle; and

wherein the controller architecture is configured to command the MRF joystick resistance mechanism to increase the MRF resistance force as the hydraulic load increases.

3. The work vehicle MRF joystick system of claim 1, wherein the work vehicle comprises an electrohydraulic (EH) actuation system and an implement movable utilizing the EH actuation system;

wherein the operational parameter comprises a circuit pressure of the EH actuation system; and
wherein the work vehicle sensor comprises a pressure sensor configured to monitor the circuit pressure.

4. The work vehicle MRF joystick system of claim 1, wherein the work vehicle comprises a load-carrying component;

wherein the operational parameter comprises a material weight borne by load-carrying component; and
wherein the controller architecture is configured to command the MRF joystick resistance mechanism to increase the MRF resistance force as the material weight increases.

5. The work vehicle MRF joystick system of claim 4, wherein the load-carrying component of the work vehicle comprises a boom-mounted implement; and

wherein the controller architecture is configured to increase the MRF resistance force in a manner impeding joystick movements raising the boom-mounted implement.

6. The work vehicle MRF joystick system of claim 4, wherein the load-carrying component comprises a receptacle of the work vehicle; and

wherein the operational parameter comprises a payload weight held by the receptacle.

7. The work vehicle MRF joystick system of claim 1, wherein the work vehicle comprises a bucket;

wherein the work vehicle sensor is configured to monitor a current fill weight of the bucket; and
wherein the controller architecture is configured to: establish a target tipoff weight to which the bucket is desirably filled; and selectively vary the MRF resistance force based of a differential between the target tipoff weight and the current fill weight of the bucket.

8. The work vehicle MRF joystick system of claim 1, wherein the operational parameter comprises a ground speed of the work vehicle; and

wherein the controller architecture is configured to command the MRF joystick resistance mechanism to increase the MRF resistance force as the ground speed of the work vehicle increases.

9. The work vehicle MRF joystick system of claim 8, wherein the MRF resistance force impedes joystick movement controlling at least one of work vehicle heading and work vehicle ground speed.

10. The work vehicle MRF joystick system of claim 1, wherein the work vehicle comprises a movable component having motion stop point;

wherein the operational parameter comprises displacement of the movable component relative to the motion stop point; and
wherein the controller architecture is configured to command the MRF joystick resistance mechanism to selectively increase the MRF resistance force as the movable component approaches the motion stop point.

11. The work vehicle MRF joystick system of claim 10, wherein the movable component comprises a hydraulic cylinder having a stroke limit or an articulable joint of a boom assembly.

12. The work vehicle MRF joystick system of claim 1, wherein the work vehicle comprises an electrohydraulic (EH) actuation system containing a pilot valve; and

wherein the controller architecture is configured to command the MRF joystick resistance mechanism to selectively vary the MRF resistance force in a manner providing tactile feedback indicating when the pilot valve initially opens.

13. The work vehicle MRF joystick system of claim 1, wherein the joystick device is utilized to control movement of the work vehicle;

wherein the operational parameter comprises a current motion state of the work vehicle; and
wherein the controller architecture is configured to: determine when motion of the joystick in an operator input direction at a detected rate will result in an undesirably abrupt change in the current motion state of the work vehicle; and when determining when motion of the joystick in an operator input direction at a detected rate will result in an undesirably abrupt change in the current motion state of the work vehicle, command the MRF joystick resistance mechanism to increase the MRF resistance force to impede continued movement of the joystick in the operator input direction.

14. The work vehicle MRF joystick system of claim 13, wherein the joystick device is utilized to control at least one of a ground speed of the work vehicle and a heading of the work vehicle.

15. The work vehicle MRF joystick system of claim 13, wherein the work vehicle comprises boom assembly attached to a chassis of the work vehicle; and

wherein the joystick device is utilized to control movement of the boom assembly.

16. A work vehicle magnetorheological fluid (MRF) joystick system utilized onboard a work vehicle, the work vehicle MRF joystick system comprising:

a joystick device, comprising: a base housing; a joystick movably mounted to the base housing; and a joystick position sensor configured to monitor movement of the joystick relative to the base housing;
an MRF joystick resistance mechanism controllable to vary an MRF resistance force impeding joystick movement relative to the base housing in at least one degree of freedom; and
a controller architecture coupled to the joystick position sensor and to the MRF joystick resistance mechanism, the controller architecture configured to: monitor a current ground speed of the work vehicle; and selectively command the MRF joystick resistance mechanism to adjust the MRF resistance force based, at least in part, on the current ground speed of the work vehicle.

17. The work vehicle MRF joystick system of claim 16, wherein the controller architecture is configured to command the MRF joystick resistance mechanism to progressively increase the MRF resistance force impeding joystick rotation about a first axis as the current ground speed of the work vehicle increases.

18. The work vehicle MRF joystick system of claim 17, wherein the joystick device is controllable is steer the work vehicle by rotation of the joystick about the first axis.

19. A work vehicle magnetorheological fluid (MRF) joystick system utilized onboard a work vehicle having a boom-mounted implement, the work vehicle MRF joystick system comprising:

a joystick device, comprising: a base housing; a joystick movably mounted to the base housing; and a joystick position sensor configured to monitor movement of the joystick relative to the base housing;
an MRF joystick resistance mechanism controllable to vary an MRF resistance force impeding joystick movement relative to the base housing in at least one degree of freedom; and
a controller architecture coupled to the joystick position sensor and to the MRF joystick resistance mechanism, the controller architecture configured to: estimate a variable load resisting movement of the boom-mounted implement in at least one direction; and selectively command the MRF joystick resistance mechanism to increase the MRF resistance force as the variable load increases.

20. The work vehicle MRF joystick system of claim 19, wherein the variable load comprises a material weight carried by the boom-mounted implement; and

wherein the controller architecture is configured to command the MRF joystick resistance mechanism to increase the MRF resistance force in a manner impeding joystick motions raising the boom-mounted implement.
Patent History
Publication number: 20210340724
Type: Application
Filed: Jun 30, 2020
Publication Date: Nov 4, 2021
Inventors: Aaron R. Kenkel (East Dubuque, IL), Todd F. Velde (Dubuque, IA), Mark E. Breutzman (Potosi, WI), Jeffrey M. Stenoish (Asbury, IA), Matthew Sbai (Dubuque, IA)
Application Number: 16/916,800
Classifications
International Classification: E02F 9/20 (20060101); G05G 1/04 (20060101); G05G 1/015 (20060101); G05G 5/03 (20060101); E02F 9/24 (20060101);