Work vehicle magnetorheological fluid joystick system with adjustable joystick return position

Abstract

This disclosure relates to a magnetorheological fluid (MRF) joystick system for work vehicles with an adjustable joystick return position. Specifically, the work vehicle MRF joystick system includes a joystick assembly. The joystick assembly further includes a base housing and a joystick rotatable relative to the base housing and biased toward a joystick return position. The MRF joystick resistance mechanism is controllable to change the MRF resistance that impedes movement of the joystick relative to the base housing. A controller architecture is simultaneously coupled to the MRF joystick resistance mechanism. The controller is configured to: (i) allow the work vehicle operator to selectively initiate operator adjustment of the joystick return position; and (ii) when operator adjustment of the joystick return position is initiated, command the MRF joystick resistance mechanism to maintain the MRF resistance at a predetermined level until operator adjustment of the joystick return position is terminated.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 019,083, filed with the U.S. Patent and Trademark Office on May 1, 2020. Technical Field

[0003] This disclosure relates to a work vehicle magnetorheological fluid (MRF) joystick system including at least one joystick biased toward a return position (which can be adjusted to operator preference). Background Technology

[0004] Joysticks are commonly used to control various operational aspects of work vehicles employed in construction, agriculture, forestry, and mining. For example, in the case of work vehicles equipped with a boom assembly, the operator can use one or more joysticks to control the movement of the boom assembly, and thus the movement of tools or implements mounted to the external end of the boom assembly. Common examples of work vehicles with such joystick-controlled boom assemblies include: excavators, feller bunchers, skidders, tractors (on which modular front-end loaders and backhoe attachments can be mounted), tractor loaders, wheel loaders, and various compact loaders. Similarly, in the case of bulldozers, motor graders, and other work vehicles equipped with earth-moving blades, the operator can use one or more joysticks to control the movement and positioning of the blade. In the case of motorized graders, bulldozers, and certain loaders such as skid steer loaders, joystick devices are often also used to operate or otherwise control the directional movement of the work vehicle chassis. Given the prevalence of joystick devices in work vehicles, and considering the relatively challenging dynamic environments in which these vehicles often operate, there is a continuous need to improve the design and functionality of work vehicle joystick systems, particularly to the extent that such advancements enhance the safety and efficiency of work vehicle operation. Summary of the Invention

[0005] A magnetorheological fluid (MRF) joystick system for use on a work vehicle is disclosed. In one embodiment, the work vehicle MRF joystick system includes a joystick device having a base housing and a joystick rotatable relative to the base housing and biased toward a joystick return position. The MRF joystick resistance mechanism can be controlled to change the MRF resistance that impedes movement of the joystick relative to the base housing. A controller architecture is coupled to the MRF joystick resistance mechanism and configured to: (i) allow the work vehicle operator to selectively initiate operator adjustment of the joystick return position; and (ii) when operator adjustment of the joystick return position is initiated, command the MRF joystick resistance mechanism to maintain the MRF resistance at a predetermined level until operator adjustment of the joystick return position is terminated.

[0006] In other embodiments, the work vehicle MRF joystick system includes a joystick assembly having a base housing and a joystick rotatable relative to the base housing and biased toward a joystick return position. The work vehicle MRF joystick system also includes an MRF joystick resistance mechanism controllable to change the MRF resistance that impedes movement of the joystick relative to the base housing; a joystick return position (JRP) locking mechanism located outside the base housing; and a controller architecture coupled to the MRF joystick resistance mechanism and the JRP locking mechanism. The JRP locking mechanism is movable between a locked state preventing adjustment of the joystick return position and an unlocked state allowing adjustment of the joystick return position. The controller architecture is configured to: (i) command the MRF joystick resistance mechanism to generate maximum MRF resistance substantially preventing movement of the joystick relative to the base housing when an operator adjustment to the joystick return position is received; and (ii) command the MRF joystick resistance mechanism to remove the maximum MRF resistance when the operator adjustment to the joystick return position is terminated.

[0007] In other implementations, the MRF joystick system for the work vehicle includes: a joystick assembly, an MRF joystick resistance mechanism, and a JRP locking mechanism. The joystick assembly further includes: a base housing; a joystick rotatable relative to the base housing; a spring contained within the base housing and applying an elastic biasing force to the joystick to its return position; and an adjustable spring support having a first end mounted to the base housing and a second end supporting the spring. The MRF joystick resistance mechanism can be controlled to change the MRF resistance that impedes movement of the joystick relative to the base housing. The JRP locking mechanism is at least partially contained within the base housing and coupled to the adjustable spring support. The JRP locking mechanism is movable between a locked state preventing position adjustment of the adjustable spring support and an unlocked state allowing position adjustment of the adjustable spring support.

[0008] 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 this description, the drawings, and the claims. Attached Figure Description

[0009] At least one example of this disclosure will be described below in conjunction with the following figures:

[0010] Figure 1 This is a schematic diagram of an example magnetorheological fluid (MRF) joystick system on a work vehicle (here, an excavator) and having an adjustable joystick return position, as illustrated in an example embodiment of this disclosure;

[0011] Figure 2 From Figure 1 The perspective view from inside the excavator cab shown illustrates two joystick devices that can be included in the example MRF joystick system and used by the operator to control the movement of the excavator boom assembly.

[0012] Figure 3 and Figure 4 This is a schematic cross-sectional view of an example MRF joystick system, partially shown and taken along a vertical section through the joystick included in the joystick device, illustrating one possible configuration of the MRF joystick system;

[0013] Figure 5 In the example implementation Figure 3 and Figure 4 The schematic diagram of the MRF joystick device shown includes a JRP locking mechanism outside the base housing of the joystick device;

[0014] Figure 6 yes Figure 5The simplified cross-sectional schematic diagram of the MRF joystick device shown illustrates an example hydraulic cylinder and shut-off valve that can be included in an implementation of the JRP locking mechanism;

[0015] Figure 7 It demonstrates, in a non-exhaustive manner, that advantageous integration can be achieved. Figures 1 to 6 Additional example diagram of a work vehicle illustrating an implementation of the MRF joystick system;

[0016] Figure 8 and Figure 9 The alternative implementations are similar to Figure 3 and Figure 4 The schematic diagram of the example MRF joystick shown illustrates that the JRP locking mechanism is integrated into the base housing of the joystick; and

[0017] Figure 10 and Figure 11 This is a top view illustrating one method in which the operation of the example MRF joystick device can be modified by combining operator adjustment with the joystick return position. Figure 8 and Figure 9 During this period, specific MRF resistance effects (e.g., MRF motion stop and / or detent) are generated at certain locations.

[0018] The same reference numerals in the various figures indicate the same elements. For simplicity and clarity, descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the exemplary and non-limiting embodiments of the invention described in the following detailed description. It should also be understood that, unless otherwise stated, features or elements appearing in the figures are not necessarily drawn to scale. Detailed Implementation

[0019] Embodiments of the present disclosure are illustrated in the accompanying drawings, which are briefly described above. Various modifications to the exemplary embodiments will be conceived by those skilled in the art without departing from the scope of the invention as set forth in the appended claims.

[0020] Overview

[0021] An implementation of a magnetorheological fluid (MRF) joystick system for a work vehicle includes at least one joystick biased toward its return position (which can be adjusted to operator preference). The MRF joystick system also includes a processing subsystem or “controller architecture” coupled to an MRF joystick resistance mechanism; that is, a mechanism, device, or damper that incorporates a magnetorheological fluid and is capable of modifying the fluid’s rheology (viscosity) through variations in the intensity of an electromagnetic field to provide controlled adjustment of the resistance to the resistance that impedes joystick movement along one or more degrees of freedom (DOF). This resistance is referred to below as “MRF resistance,” and the degree to which MRF resistance impedes joystick movement along a particular direction or combination of directions is referred to as “joystick stiffness.” Through the use of this MRF technology, implementations of MRF joystick devices can generate various tactile resistance effects that can be perceived by the work vehicle operator, including selective application of stop and continuous variation in MRF resistance that inhibits joystick movement along one or more directions. Furthermore, in certain situations, maximum MRF resistance can be generated to attempt to prevent certain joystick movements or limit the joystick's range of motion (ROM) to a specific pattern or range of movement. Regardless of the specific MRF effect or control scheme employed during operation of the work vehicle's MRF joystick system, embodiments of this disclosure utilize the unique MRF capabilities of one or more joystick devices included in the MRF joystick system to provide an intuitive, manual drive process for adjusting the joystick return position of a given joystick device to the operator's preference.

[0022] In addition to the components mentioned above, embodiments of the MRF joystick system for work vehicles also include at least one joystick return position (JRP) locking mechanism that is movable between a locked state and an unlocked state. In the locked state, the JRP locking mechanism prevents operator adjustment of the joystick return position for a given MRF joystick. Conversely, in the unlocked state, the JRP locking mechanism enables operator adjustment of the joystick return position. The JRP locking mechanism can provide this functionality in various forms, for example, depending on whether it is integrated into the main casing or "base housing" of the joystick, or conversely, placed externally relative to the base housing. When integrated into the base housing, the JRP locking mechanism can support one or more mechanical springs (or other biasing components) also contained within the base housing and coupled to the lower part of the joystick. Collectively, the springs apply a cumulative biasing force to cause the joystick to rotate toward an operator-adjustable joystick return position. In one implementation, the JRP locking mechanism may include a hydraulic cylinder and a shut-off valve, which can be controlled by a controller architecture to selectively allow or prevent fluid flow between the hydraulic chambers of the cylinder. The hydraulic cylinder further includes a cylinder body and a piston, which can translate freely relative to the cylinder body when fluid flow between the chambers is allowed. Commonly, the hydraulic cylinder and spring may be referred to as a "cylinder-spring pair." While potentially including any actual number of cylinder-spring pairs, a given MRF joystick assembly typically includes one to four cylinder-spring pairs, depending on the encapsulation of the joystick assembly, the number of degrees of freedom (DOF) the joystick can move, and other factors.

[0023] In the example above, the operator of the work vehicle can be permitted to adjust the return position of the MRF joystick using the following processing steps. First, the operator provides some form of input (such as received by the controller architecture of the MRF joystick) to initiate the JRP adjustment process. In response to this operator input, the controller architecture unlocks the JRP locking mechanism to allow operator adjustment of the joystick return position; for example, when the JRP locking mechanism includes at least one hydraulic cylinder and a corresponding shut-off valve, the controller architecture can command the shut-off valve to open or otherwise temporarily allow fluid flow between the cylinder chambers. This allows the pistons of each cylinder to translate freely while the operator grasps the joystick handle and rotates the joystick to the desired return position. As the operator rotates the joystick in this manner, the springs included in each cylinder-spring pair deflect to apply force to their supporting pistons, causing the pistons to translate to a new position to zero the spring force and return the springs to the undeflected state. After adjusting the joystick to the operator-adjusted return position, the operator then inputs additional input to terminate the JRP adjustment process. Upon receiving this input, the controller architecture commands the JRP locking mechanism to relock; for example, by commanding the shut-off valve to close again or otherwise preventing fluid flow between the cylinder chambers. As a result, the hydraulic cylinder pistons are stopped in their current translational positions. Supported by the pistons, the bias spring now biases the lever towards the most recently adjusted return position during use of the MRF joystick.

[0024] In implementations of the MRF joystick system for work vehicles, after each JRP adjustment process terminates, the controller architecture can store the JRP setting data in a computer-readable memory. The controller architecture can then recall this JRP setting data at appropriate times to identify a selected joystick position where a specific position-dependent MRF effect is generated, such as an MRF stop encountered when the joystick rotates relative to the base housing about one or more axes. Furthermore, in implementations where the JRP locking mechanism is located inside the base housing, movement of the joystick return position from its default, unmodified, or "true center" setting may cause some asymmetry in the joystick's range of motion (ROM). This ROM asymmetry may be relatively small and therefore not compensated for in implementations of the MRF joystick system. However, in other cases, the MRF joystick system can perform certain actions to correct this symmetry, for example, by intentionally shortening the joystick ROM along one or more selected directions. For example, in some implementations of the MRF joystick system for work vehicles, when the joystick rotates in the opposite direction about a given axis from the operator-adjusted joystick return position, the controller architecture can generate an MRF motion stop at an appropriate location to balance the joystick's ROM, as follows: Figure 10 and Figure 11 Further discussion is needed.

[0025] In other implementations of the MRF joystick system for work vehicles, the JRP locking mechanism may be located outside the base housing of the MRF joystick device. In this case, the base housing may be engaged with an adjacent (e.g., surrounding) support structure positioned adjacent to the operator's console or seat of the work vehicle; for example, in at least some cases, the support structure may be integrated into or otherwise engaged with the work vehicle's console or armrest. In embodiments, a multi-DOF (e.g., universal joint) coupling may be provided between the base housing and the support structure to allow the MRF joystick device to rotate relative to the support structure about two vertical axes within a limited angular ROM. The JRP locking mechanism may be mounted between the base housing and the support structure and may take any form suitable for preventing such relative movement between the base housing and the support structure when the JRP locking mechanism is locked. In some cases, the JRP locking mechanism may be a manually actuated locking device, such as one or more set screws, clamping devices, or similar devices, which may be rotated or otherwise physically manipulated by the operator to selectively lock and unlock the JRP locking mechanism. This provides a structurally robust and cost-effective locking interface, but with a trade-off, it potentially reduces ease of use for the operator. In more complex implementations, the JRP locking mechanism can be an actuated rotary or linear device that can be remotely locked and unlocked via a controller architecture. For example, in one implementation, the JRP locking mechanism may include: one or more hydraulic cylinders mechanically connected between the base housing and the support structure; and one or more valves (e.g., MRF shut-off valves or non-MRF shut-off valves) that can be controlled via a controller architecture to selectively allow or prevent fluid flow between the chambers of the hydraulic cylinders.

[0026] In an implementation where the JRP locking mechanism is located outside the base housing, the following process can be performed by the controller architecture of the MRF joystick system to enable the vehicle operator to adjust the JRP. First, the controller architecture receives an operator input command requesting entry into the JRP adjustment mode. In response to this input command, the controller architecture causes the MRF joystick resistance mechanism to apply maximum or peak MRF resistance to prevent rotation of the joystick relative to the base housing. In a non-manual implementation of the JRP locking mechanism, the controller architecture can also combine this with a command to the MRF joystick resistance mechanism to generate maximum MRF resistance to unlock the JRP locking mechanism. This combination of actions allows the operator to turn the joystick handle and rotate the joystick to the desired return position, while the base housing rotates relative to the support structure along with the joystick. When a subsequent input instructing the operator to end or terminate the JRP adjustment process is received, the controller architecture controls the MRF joystick resistance mechanism to remove the maximum MRF resistance. If applicable, the controller architecture also commands the JRP locking mechanism to return to the locked state, again preventing rotation of the base housing relative to the support structure. In this way, the joystick return position is adjusted by changing the angular orientation of the MRF joystick device relative to the support structure itself. The operator can then return to normal use of the MRF joystick, now biased to the operator-adjusted joystick return position.

[0027] When the JRP locking mechanism is internal to the housing, the MRF joystick can be designed to be relatively compact and structurally robust. Additionally, integrating the JRP locking mechanism into the housing, for example, when it includes one or more hydraulic cylinders conducting magnetorheological fluid, allows it to share certain components with the MRF joystick resistance mechanism (e.g., a common MRF valve or valve assembly). Conversely, having the JRP locking mechanism external to the housing provides greater design flexibility and allows for the maintenance of ROM symmetry (and desired MRF stop positioning, if applicable) independently of JRP adjustments to the MRF joystick. Thus, both configurations offer distinct advantages. Regardless of whether the JRP locking mechanism is internal or external to the housing, the work vehicle MRF joystick system utilizes the unique MRF capabilities of a given joystick to provide an intuitive, manual actuation process for adjusting the joystick's return position to the operator's preference. Therefore, the operator of the work vehicle can easily select and reselect the ideal joystick return position to maximize operator comfort and reduce ergonomic stress that could otherwise occur during long joystick interactions.

[0028] Below, in conjunction with Figures 1 to 6This describes a first example embodiment of a work vehicle MRF joystick system, which allows operator adjustment of the joystick return position and includes a JRP locking mechanism located outside the base housing of the MRF joystick device. In the example embodiments described below, the MRF joystick system is primarily discussed in the context of a specific type of work vehicle (i.e., an excavator). Furthermore, in the examples below, the MRF joystick system includes two joystick devices, each including a joystick rotatable about two vertical axes, for controlling the movement of the excavator boom assembly and tools or implements attached to it. Although the examples are given below, in further embodiments, the MRF joystick system may include more or fewer joysticks, and each joystick device may be capable of any number of DOFs and move along any suitable motion pattern; for example, in an alternative implementation, a given joystick device may be rotatable about a single axis or move along a defined (e.g., H-shaped) trajectory or motion pattern. Moreover, the MRF joystick system described below can be deployed on a wide range of work vehicles including various joystick-controlled functions, as described below. Figure 7 Additional examples of the aforementioned work vehicles are discussed below. Figures 8 to 11 The second example implementation of the MRF joystick system is further discussed, which, while including a JRP locking mechanism located inside the base housing of the MRF joystick device, also allows operator JRP adjustment.

[0029] Example MRF joystick system including at least one joystick device with an adjustable joystick return position

[0030] Initial reference Figure 1An example work vehicle (excavator 20 in this case) equipped with a work vehicle MRF joystick system 22 is presented. In addition to the MRF joystick system 22, the excavator 20 includes a boom assembly 24 that is attached to a tool or implement (such as bucket 26). Various other implements can be interchanged with bucket 26 and attached to the end of the boom assembly 24, including other buckets, grapples, and hydraulic hammers. The excavator 20 has a body or chassis 28, a tracked underframe 30 supporting the chassis 28, and a cab 32 located at the front of the chassis 28 and surrounding the operator's cab. The excavator boom assembly 24 extends from the chassis 28 and includes an inner or proximal boom 34 (hereinafter referred to as "lifting boom 34"), an outer or distal boom 36 (hereinafter referred to as "dipperstick 36"), and multiple hydraulic cylinders 38, 40, and 42 as major structural components. Hydraulic cylinders 38, 40, and 42 further include: two lifting cylinders 38, a bucket handle cylinder 40, and a bucket cylinder 42. The extension and retraction of the lifting cylinders 38 rotate the boom 34 about a first pivot joint, at which the boom 34 engages with the excavator chassis 28 (here, adjacent to the right side of the cab 32). The extension and retraction of the bucket handle cylinder 40 rotate the bucket handle 36 about a second pivot joint, at which the bucket handle 36 engages with the boom 34. Finally, the 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 engages with the bucket handle 36.

[0031] Hydraulic cylinders 38, 40, and 42 are included in an electrohydraulic (EH) actuation system 44, which... Figure 1The section is enclosed by a box 46 entitled "Actuator with Function Controlled by Joystick". The movement of the excavator's external components 24 is controlled using at least one joystick located within the excavator cab 32 and included in the MRF joystick system 22. Specifically, the operator can use one or more joysticks included in the MRF joystick system 22 to control the extension and retraction of hydraulic cylinders 38, 40, 42, and to control the slewing of the boom assembly 24 via the rotation of the excavator chassis 28 relative to the tracked undercarriage 30. The depicted EH actuation system 44 also includes various other unillustrated hydraulic components, which may include flow lines (e.g., flexible hoses), check valves or safety valves, pumps, fittings, filters, etc. Additionally, the EH actuation system 44 includes an electronic valve actuator and a flow control valve (such as a spool valve) that can be modulated to adjust the flow rate of pressurized hydraulic fluid into and out of hydraulic cylinders 38, 40, 42. If the controller architecture 50 described below can control the movement of the boom assembly 24 via commands sent to a selected actuator in the actuator 46 (which performs the joystick control function of the excavator 20), then the specific construction or architecture of the EH actuation system 44 stated herein is largely irrelevant to the implementation of this disclosure.

[0032] As in Figure 1 Schematably illustrated in the upper left portion, the work vehicle MRF joystick system 22 includes one or more MRF joystick devices 52, 54. As appears herein, the term "MRF joystick device" refers to an operator input device comprising at least one joystick or control lever, the movement of which can be resisted by a variable resistance or "stiffness force" applied using an MRF joystick resistance mechanism of the type described herein. Although for clarity, in Figure 1 One such MRF joystick device 52 is schematically shown, but the MRF joystick system 22 may include any actual 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; for example, in conjunction with the following... Figure 2 The control lever devices 52 and 54 are described. The following further discusses how two such control lever devices 52 and 54 can be used to control the movement of the excavator boom assembly 24. However, firstly, a method for... Figure 1 The general discussion of the joystick device 52, which is schematically illustrated, is intended to establish a general framework for a better understanding of the embodiments of this disclosure.

[0033] like Figure 1The MRF joystick device 52 is schematically illustrated as including a joystick 60 mounted to a lower support structure or base housing 62. The joystick 60 is movable relative to the base housing 62 along at least one DOF and rotatable relative to the base housing 62 about one or more axes. In the depicted embodiment, and as indicated by arrow 64, the joystick 60 of the MRF joystick device 52 is rotatable relative to the base housing 62 about two vertical axes, as will also be described below. The MRF joystick device 52 includes one or more joystick position sensors 66 for monitoring the current position and movement of the joystick 60 relative to the base housing 62. The MRF joystick device 52 may also include various other components 68, including buttons, dials, switches, or other manual input features, which may be located on the joystick 60 itself, on the base housing 62, or a combination of both. Spring components (gas springs or mechanical springs), magnets, or fluid dampers can be incorporated into the joystick assembly 52 to provide the desired return rate (described below) for the joystick home or return position, as well as the desired feel of the joystick 60 as perceived by the operator when interacting with the MRF joystick assembly 52.

[0034] The MRF joystick resistance mechanism 56 is at least partially integrated into the base housing 62 of the MRF joystick device 52. The MRF joystick resistance mechanism 56 can be controlled by the controller architecture 50 of the work vehicle MRF joystick system 22 to adjust the MRF resistance, and thus the joystick stiffness resisting joystick movement relative to the base housing 62 along at least one DOF. In this respect, during operation of the MRF joystick system 22, the controller architecture 50 can selectively command the MRF joystick resistance mechanism 56 to increase the joystick stiffness, thereby impeding joystick rotation about a specific axis or combination of axes. As discussed more fully below, the controller architecture 50 can command the MRF joystick resistance mechanism 56 to provide a range of effects or modifications to joystick behavior by selectively increasing the intensity of the EM field in which the magnetorheological fluid contained in the mechanism 56 is at least partially immersed. For example, in one implementation, controller architecture 50 may command the MRF joystick resistance mechanism to generate a localized region of increased resistance encountered as the joystick moves to a specific position (referred to herein as an "MRF stop"). Upon application, the MRF stop may be generated to apply sufficient MRF resistance to overcome the biasing or "centripetal" force applied to the joystick; in this case, the MRF stop may be specifically referred to as a "hold deten." In other cases, the MRF stop may be generated with lower MRF resistance, perceptible to the operator of the work vehicle manipulating the joystick, but insufficient to prevent the joystick from returning to its return position solely under the influence of the joystick's centripetal force. This latter type of MRF stop is referred to herein as a "feel detent." The following is in conjunction with... Figure 3 and Figure 4 This describes a generalized example of one way to implement the MRF joystick resistance mechanism 56.

[0035] The MRF joystick system 22 also includes a JRP locking mechanism 70, which is associated with the MRF joystick device 52 and movable between a locked and unlocked state. In the locked state, the JRP locking mechanism 70 prevents operator adjustment of the joystick return position of the MRF joystick device 52. In the unlocked state, the JRP locking mechanism 70 allows the current operator of the excavator 20 to adjust the joystick return position. The JRP locking mechanism 70 may include any number, type, and arrangement of devices providing this functionality. In some embodiments, the JRP locking mechanism 70 may be located outside the base housing 62 of the MRF joystick device 52, such as in conjunction with… Figure 5 and Figure 6The above is discussed. Alternatively, in other cases, the JRP locking mechanism 70 may be located inside the base housing 62 of the MRF joystick device 52 (integrated into the base housing), such as in combination with... Figure 8 and Figure 9 The discussion focuses on the following: In some cases, the JRP locking mechanism 70 may comprise one or more operator-actuated purely mechanical devices, particularly when the JRP locking mechanism 70 is located outside the base housing 62 of the MRF joystick device 52. However, more typically, the JRP locking mechanism 70 includes one or more actuated components that are remotely controlled by the controller architecture 50 during the JRP adjustment process. On this latter point, in... Figure 1 In the schematic diagram, arrow 72 indicates a data connection (wired or wireless) from controller architecture 50 to JRP locking mechanism 70 and to MRF joystick resistance mechanism 56. Similarly, arrow 74 indicates one or more data connections (wired or wireless) from position sensor 66 and possibly other components of MRF joystick device 52 (e.g., external buttons, dials, or other operator inputs) to controller architecture 50.

[0036] In addition to those previously described, embodiments of the MRF joystick system 22 may also include any number of other non-joystick components 76. These additional non-joystick components 76 may include: an operator interface 78 (different from the MRF joystick device 52), a display device 80 located in the excavator cab 32, and various other types of non-joystick sensors 82. Specifically, the operator interface 78 may 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 may also include cursor-type input devices such as trackballs or joysticks for interacting with a graphical user interface (GUI) generated on the display device 80. The display device 80 may be located within the cab 32 and may take the form of any image-generating device on which visual alarms and other information can be visually presented. 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 relevant to controller architecture 50 when performing the processes described below. In some cases, display device 80 may also have touch input capability. Finally, MRF joystick system 22 may include various other non-joystick sensors 82. For example, non-joystick sensors 82 may include sensors or data sources for detecting and monitoring vehicle motion, such as Global Navigation Satellite System (GNSS) modules (e.g., Global Positioning System (GPS) modules) that monitor the excavator's position and motion status.

[0037] As in Figure 1As further described herein, controller architecture 50 is associated with memory 48 and can communicate with various illustrated components via any number of wired data connections, wireless data connections, or any combination thereof; for example, as generally illustrated, controller architecture 50 can receive data from the components via a centralized vehicle or controller area network (CAN) bus 84. As appears herein, the term "controller architecture" is used 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. Therefore, controller architecture 50 may encompass or be associated with any actual number of processors, individual controllers, computer-readable storage, power supplies, storage devices, interface cards, and other standardized components. In many cases, controller architecture 50 may include a local controller directly associated with the joystick interface, as well as other controllers housed within an operator's console surrounded by cab 32, and the local controller may communicate with other controllers on excavator 20 as needed. Controller architecture 50 may also include any number of firmware and software programs or computer-readable instructions designed to perform various processing tasks, calculations, and control functions described herein, or may cooperate with firmware and software programs or computer-readable instructions. Such computer-readable instructions may be stored in non-volatile sectors of memory 48 associated with (accessible by) controller architecture 50. Although in Figure 1 While generally exemplified as a single frame, memory 48 may encompass any amount and type of storage medium suitable for storing computer-readable code or instructions, as well as other data for supporting the operation of the MRF joystick system 22; for example, JRP setting data described below, and data relating to any MRF effects (e.g., the position of the MRF stop) that may be desired to occur during operation of the joystick device.

[0038] A more detailed discussion of the joystick configuration or layout of the excavator 20 will be given, noting that the number of joystick devices included in the MRF joystick system 22, as well as the structural aspects and functions of such joysticks, will differ between implementations. As previously mentioned, although in Figure 1 Only a single joystick 52 is shown schematically, but the MRF joystick system 22 typically has two joysticks 52, 54 supporting control of the excavator boom assembly. This is further illustrated. Figure 2A perspective view from inside the excavator cab 32 is provided, depicting two MRF joystick devices 52, 54 suitably included in the embodiment of the MRF joystick system 22. As can be seen, the MRF joystick devices 52, 54 are positioned on opposite sides of the operator's seat 86, allowing the operator to relatively easily operate the left MRF joystick device 52 and the right joystick device 54 simultaneously using both hands. Continuing from the above... Figure 1 By reference numerals, 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 vertical axes. Joystick devices 52, 54 also each include a flexible cover or boot 88 engaged between the lower portion of the joystick 60 and their respective base housing 62. Additional joystick inputs are also provided on each joystick 60 in the form of thumb-accessible buttons, which may be provided on the base housing 62 as other unillustrated manual inputs (e.g., buttons, dials, and / or switches). Figure 2 Other notable features of the excavator 20 shown include the previously mentioned display device 80 and pedal / control lever mechanisms 90, 92, which control the corresponding movement of the left and right tracks of the tracked undercarriage 30.

[0039] Different control schemes can be used to translate the movement of the joystick 60 included in the joystick devices 51 and 54 into corresponding movement of the excavator boom assembly 24. In many cases, the excavator 20 will support boom assembly control in either "backhoe control" or "SAE control" mode and "International Organization for Standardization" or "ISO" control mode (and usually allows switching between these modes). In the backhoe control mode, moving the left joystick 60 to the operator's left (arrow 94) causes the excavator boom assembly 24 to rotate to the left (corresponding to the chassis 28 rotating counterclockwise relative to the tracked underframe 30), moving the left joystick 60 to the operator's right (arrow 96) causes the boom assembly 24 to rotate to the right (corresponding to the chassis 28 rotating clockwise relative to the tracked underframe 30), moving the left joystick 60 forward (arrow 98) lowers the boom 34, and moving the left joystick 60 backward (arrow 100) raises the boom 34. Furthermore, in the backhoe control mode, moving the right joystick 60 to the left (arrow 102) causes the bucket 26 to roll inward, moving the right joystick 60 to the right (arrow 104) causes the bucket 26 to uncurl or "open," moving the right joystick 60 forward (arrow 106) causes the bucket handle 36 to rotate outward, and moving the right joystick 60 backward (arrow 108) causes the bucket handle 36 to rotate inward. In contrast, in the ISO control mode, the joystick movements for the swing command and the bucket roll command remain unchanged, while the joystick mappings for the boom and bucket handle are reversed. Therefore, in ISO control mode, moving the left joystick 60 forward and backward controls the bucket handle rotation as described above, while moving the right joystick 60 forward and backward controls the boom 34 movement (raising and lowering) as described above.

[0040] Now, referring to Figure 3 and Figure 4The following figures illustrate an example configuration of the MRF joystick device 52 and the MRF joystick resistance mechanism 56 using two simplified cross-sectional schematic diagrams. While these figures illustrate a single MRF joystick device (i.e., MRF joystick device 52), the following description also applies to another MRF joystick device 54 included in the example MRF joystick system 22. The following description is provided only by way of non-limiting example; note that multiple different joystick designs incorporating or functionally cooperating with the MRF joystick resistance mechanism are possible. If a meaningful change in the rheological properties (viscosity) of the magnetorheological fluid occurs in conjunction with a controlled change in the EM field strength (described below), then the specific composition of the magnetorheological fluid is largely irrelevant to embodiments of this disclosure. However, for completeness, note that a magnetorheological fluid composition perfectly suited for use in embodiments of this disclosure comprises magnetically permeable (e.g., iron carbonyl) particles dispersed in a carrier fluid that is primarily composed by weight of oil or alcohol (e.g., ethylene glycol). These magnetically conductive particles can have an average diameter in the micrometer range (or other maximum cross-sectional dimensions if the particles have a non-spherical (e.g., rectangular) shape); for example, in one embodiment, spherical magnetically conductive particles with an average diameter between 1 micrometer and 10 micrometers are used. Various other additives (such as dispersants or diluents) can also be included in the magnetorheological fluid to fine-tune its properties.

[0041] Now, referring to Figure 3 and Figure 4 The example joystick configuration shown, and again continuing with 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 this upper handle is shown in the figure), and a generally spherical lower base 112 (hereinafter referred to as "generally spherical base 112"). The generally spherical base 112 of the joystick 60 is captured between two walls 114, 116 of a base housing 62, which may extend generally parallel to each other to form the upper portion of the base housing 62. A vertically aligned central opening is provided through the housing walls 114, 116, and the corresponding diameter of this central opening is determined to be smaller than the diameter of the generally spherical base 112. The spacing or vertical offset between the walls 114, 116 is also selected such that the generally spherical base 112 is entirely captured between the vertically spaced housing walls 114, 116 to form a ball-and-socket joint. This allows the joystick 60 to rotate relative to the base housing 62 about two vertical axes, which correspond to... Figure 3 and Figure 4The coordinate system 118 shows the X and Y axes; it also generally prevents translational movement of the joystick 60 along the X, Y, and Z axes of the coordinate system 118. In other embodiments, various other mechanical arrangements can be used to mount the joystick to the base housing, while allowing the joystick to rotate about two vertical axes (such as a universal joint arrangement). In a less complex embodiment, a pivot or pin joint can be provided to allow the joystick 60 to rotate relative to the base housing 62 about a single axis.

[0042] The joystick 60 of the MRF joystick device 52 also includes a stinger or lower joystick extension 120 projecting from a generally spherical base 112 in the opposite direction to the joystick handle 110. In the illustrated schematic, the lower joystick extension 120 is connected to a static attachment point of the base housing 62 via a single return or bias spring 124; note that this arrangement is simplified for illustrative purposes, and in actual implementations of the MRF joystick device 52, a more complex spring bias arrangement (or other joystick biasing mechanism, if any) will typically be used. When the joystick 60 is... Figure 3 When the joystick returns to its original position as shown, such as Figure 4 As shown, the bias spring 124 deflects to cause the control lever 60 to return to its original position. Figure 3 Return. Thus, as an example, when rotating to Figure 4 After the indicated position, if the operator of the work vehicle subsequently releases the control lever 110, the control lever 60 will move under the influence of the bias spring 124. Figure 3 The joystick returns to the neutral position or the original position (referred to as the "joystick return position" in this text). Below, in conjunction with... Figures 5 to 11 Further discussion is provided on how the joystick 60 can be biased toward the joystick return position (which can be adjusted to operator preference).

[0043] Example MRF joystick resistance mechanism 56 includes, respectively, as follows: Figure 3 and Figure 4 The first MRF cylinder 126 and the second MRF cylinder 128 are shown. The first MRF cylinder 126 ( Figure 3 It is mechanically engaged between the lower control lever extension 120 and the partially shown static attachment point or basic structural feature 130 of the base housing 62. Similarly, the second MRF cylinder 128 ( Figure 4 The MRF cylinder 128 is mechanically engaged between the lower control lever extension 120 and the static attachment point 132 of the base housing 62, and the MRF cylinder 128 rotates approximately 90 degrees relative to the MRF cylinder 126 about the Z-axis of coordinate diagram 118. Due to this structural configuration, the MRF cylinder 126 ( Figure 3) can be controlled to selectively resist rotation of the joystick 60 about the X-axis of coordinate diagram 118, while the MRF cylinder 128 ( Figure 4 The lever 60 can be controlled to selectively resist rotation about the Y-axis of coordinate diagram 118. Additionally, both MRF cylinders 126 and 128 can be jointly controlled to selectively resist rotation about any axis falling between the X and Y axes and extending in the XY plane. In other embodiments, different MRF cylinder configurations can be used, and more or fewer MRF cylinders can be included; for example, in implementations where it is desirable to selectively resist rotation of the lever 60 only about the X-axis or only about the Y-axis, or in implementations where the lever 60 can only rotate about a single axis, a single MRF cylinder or a pair of opposing cylinders can be used. Finally, although not shown in the simplified schematic, in further implementations, any number of additional groups or components can be included in the MRF cylinders 126 and 128, or they can be associated with any number of additional components. Such additional components can include sensors that monitor the stroke (if desired) of the cylinders 126 and 128 to, for example, track the position of the lever, instead of the lever sensors 182 and 184 described below.

[0044] MRF cylinders 126 and 128 each include a cylinder body 134 to which pistons 138 and 140 are slidably mounted. Each cylinder body 134 includes a cylindrical cavity or bore 136 in which the end 138 of one of the pistons 138 and 140 is mounted for translational movement along the longitudinal axis or centerline of the cylinder body 134. Around the outer periphery of the cavity or bore, each piston end 138 is fitted with one or more dynamic seals (e.g., O-rings) to sealably engage the inner surface of the cylinder body 134, thereby dividing the bore 136 into two antagonistic variable-volume hydraulic chambers. Pistons 138 and 140 also each include an elongated piston rod 140 that protrudes from the piston end 138 toward the lower control lever extension 120 of the control lever 60. The piston rod 140 extends through an end cap 142 (again, engaging any number of seals) fixed above the open end of the cylinder body 134 to attach to the lower lever extension 120 at lever attachment point 144. In the exemplary example, lever attachment point 144 takes the form of a pin or pivot joint; however, in other embodiments, more complex joints (e.g., ball joints) may be used to form this mechanical connection. Opposite to lever attachment point 144, the opposite ends of the MRF cylinders 126, 128 are mounted to the corresponding stationary attachment points 130, 132 via ball joints 145. Finally, hydraulic ports 146, 148 are also provided at opposite ends of the respective MRF cylinder bodies 126, 128 to allow the inflow and outflow of magnetorheological fluid to be combined with translational movement or stroke variation of the pistons 138, 140 along the respective longitudinal axes of the MRF cylinders 126, 128.

[0045] MRF cylinders 126 and 128 are fluidly interconnected with corresponding MRF valves 150 and 152 via flow line connections 178 and 180, respectively. As with MRF cylinders 126 and 128, MRF valves 150 and 152 are presented identically in the illustrated example, but may be modified in further implementations. Although referred to as "valve" in general terms (particularly considering that the function of MRF valves 150 and 152 is to control the flow of magnetorheological fluid), it will be observed that in the current example, MRF valves 150 and 152 lack valve components and other moving mechanical parts. As a beneficial inference, MRF valves 150 and 152 provide fail-safe operation, as they still allow magnetorheological fluid to pass through them with relatively low resistance in the unlikely event of MRF valve failure. Therefore, if any one or both of the MRF valves 150 and 152 fail for any reason, the ability of the MRF joystick resistance mechanism 56 to apply resistance to limit or inhibit joystick movement may be impaired; however, the joystick 60 will be able to rotate freely about the X and Y axes in a manner similar to conventional non-MRF joystick systems, and the MRF joystick device 52 will generally still be able to control the excavator boom assembly 24.

[0046] In the depicted embodiment, MRF valves 150 and 152 both include a valve housing 154 containing end caps 156 fixed to opposite ends of an elongated cylinder core 158. A generally annular or tubular flow channel 160 extends around the cylinder core 158 and between two fluid ports 162 and 164, which are provided by opposite end caps 156. The annular flow channel 160 is surrounded by a plurality of EM induction coils 166 (extending through these EM induction coils) (hereinafter referred to as "EM coils 166"), which are wound around a paramagnetic holder 168 and have a plurality of axially or longitudinally spaced ferrite rings 170 distributed therefrom. A tubular cover 172 surrounds the assembly and through which a plurality of leads are provided for electrical interconnection with the housed EM coils 166. Figure 3 and Figure 4Lines 174 and 176 schematically represent two such leads and corresponding electrical connections to the power and control source 177. As indicated by arrow 179, the controller architecture 50 is operationally coupled to the power and control source 177 in such a way that it can control the source 177 to change the current supplied to the EM coil 166 or the voltage applied across the EM coil during operation of the MRF joystick system 22. Therefore, this structural arrangement allows the controller architecture 50 to command or control the MRF joystick resistance mechanism 56 to change the intensity of the EM field generated by the EM coil 166. An annular flow channel 160 extends through the EM coil 166 (and may be substantially coaxial with the EM coil) such that when the magnetorheological fluid is guided through the MRF valves 150 and 152, the magnetorheological fluid passes through the center of the EM field.

[0047] The fluid ports 162 and 164 of MRF valves 150 and 152 are fluidly connected to ports 146 and 148 of the corresponding MRF cylinders 126 and 128 via the aforementioned conduits or flow lines 178 and 180, respectively. The length of these flow line connections 178 and 180 is, for example, a flexible tube with sufficient slack to accommodate any movement of the MRF cylinders 126 and 128 caused by the rotation of the lever 60. In this regard, consider... Figure 4 Example scenario. In this example, the operator has moved the joystick handle 110 in the operator input direction (indicated by arrow 185), causing the joystick 60 to rotate clockwise about the Y-axis of coordinate diagram 118. In conjunction with this joystick movement, as shown, the MRF cylinder 128 rotates about the ball joint 145 to tilt slightly upwards. Furthermore, along with this operator-controlled joystick movement, the pistons 138 and 140 contained in the MRF cylinder 128 retract, causing the piston end 138 to... Figure 4 The pistons 138 and 140 move to the left (towards attachment point 132). This translational movement of pistons 138 and 140 drives magnetorheological fluid through the MRF valve 152 to accommodate a decrease in volume in the chamber to the left of piston end 138 and a corresponding increase in volume in the chamber to the right of piston end 138. Thus, at any time during this operator-controlled joystick rotation, the controller architecture 50 can change the current supplied to the EM coil 166 or the voltage applied across the EM coil 166 to alter the force resisting the magnetorheological fluid flowing through the MRF valve 152, thereby obtaining the desired MRF resistance to further changes in the stroke of pistons 138 and 140.

[0048] Given the responsiveness of the MRF joystick resistance mechanism 56, the controller architecture 50 can control the resistance mechanism 56 to apply this MRF resistance only briefly, thereby increasing the intensity of the MRF resistance in a predetermined manner (e.g., gradually or progressively), while increasing the piston displacement, or providing various other resistance effects (e.g., tactile stopping or pulsating effects), as discussed in detail below. The controller architecture 50 can also control the MRF joystick resistance mechanism 56 to selectively provide resistance effects such as stroke changes in conjunction with the rotation of the joystick 60 about the X-axis of coordinate diagram 118 by the pistons 138, 140 in the MRF valve 150. Furthermore, the MRF joystick resistance mechanism 56 can independently change the EM field strength generated by the EM coil 166 within the MRF valves 150, 152, to allow independent control of the MRF resistance that inhibits the rotation of the joystick about the X and Y axes of coordinate diagram 118.

[0049] The MRF joystick device 52 may also include one or more joystick position sensors 182, 184 (e.g., optical or non-optical sensors or transformers) 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 for monitoring the rotation of the joystick 60 about the X-axis of coordinate diagram 118. Figure 3 ); and a second joystick position sensor 184 that monitors the rotation of the joystick 60 about the Y-axis of coordinate diagram 118. Figure 4 The data connections between the joystick position sensors 182 and 184 and the controller architecture 50 are represented by lines 186 and 188, respectively. In a further implementation, the MRF joystick device 52 may include various other components not illustrated, such as the MRF joystick resistance mechanism 56. Where appropriate, such components may include: an operator input section and a corresponding electrical connection section disposed on the joystick 60 or the base housing 62, an AFF motor, and a pressure sensor and / or flow rate sensor included in the flow loop of the MRF joystick resistance mechanism 56 to best suit a particular application or use.

[0050] As previously emphasized, the above-described embodiment of the MRF joystick device 52 has been provided only as a non-limiting example. In alternative implementations, the construction of the joystick 60 may differ in various aspects. If the MRF joystick resistance mechanism 56 can be controlled by the controller architecture 50 to selectively apply resistance (through rheological changes in the magnetorheological fluid) to suppress movement of the joystick relative to the base shell along at least one DOF, then in a further embodiment, the MRF joystick resistance mechanism 56 also relative to... Figure 3 and Figure 4The example shown differs from the one illustrated. In a further practical application, an EM induction coil similar to or identical to EM coil 166 can be directly integrated into the MRF cylinders 126, 128 to provide the desired controllable MRF resistance effect. In this practical application, magnetorheological fluid flow can be permitted between the variable-volume chambers within a given MRF cylinder 126, 128 via one or more orifices provided through the piston end 138, either by providing an annulus or a slightly smaller annular gap around the inner surface of the piston end 138 and the cylinder body 134, or by providing a flow channel through the cylinder body 134 or the sleeve itself. Advantageously, this configuration allows for a relatively compact integrated design of the MRF lever resistance mechanism. In contrast, in at least some cases, one or more external MRF valves (such as MRF valves 150, 152) are used. Figure 3 and Figure 4 The use of )) can facilitate cost-effective manufacturing and allow the use of commercially available modular components.

[0051] In other implementations, the MRF joystick device can be designed to allow magnetorheological fluid to envelop and act directly on the lower portion of the joystick 60 itself (such as a spherical base 112 in the case of the joystick 60), with an EM coil positioned around the lower portion of the joystick and surrounding the magnetorheological fluid body. In this embodiment, the spherical base 112 may be provided with ribs, grooves, or similar topological features to facilitate displacement of the magnetorheological fluid in conjunction with joystick rotation, wherein energizing the EM coil increases the viscosity of the magnetorheological fluid, thereby impeding fluid flow through a restricted flow path provided around the spherical base 112, or perhaps due to the direction of the magnetorheological fluid in conjunction with the joystick rotation. Various other designs are also possible in further embodiments of the MRF joystick system 22.

[0052] Regardless of the specific design of the MRF joystick resistance mechanism 56, MRF technology, which uses variable MRF resistance or joystick stiffness to selectively generate suppression (resistance or prevention) of unintended joystick movement, offers several advantages. A primary advantage is the high responsiveness of the MRF joystick resistance mechanism 56 (and typically the MRF joystick resistance mechanism) in terms of the rheology of the magnetorheological fluid, and ultimately in terms of suppressing joystick movement within a highly shortened timeframe (e.g., in some cases, approximately 1 millisecond) of the joystick stiffness applied by the MRF, allowing desired variations in the EM field strength to be achieved. Accordingly, the MRF joystick resistance mechanism 56 can enable the removal (or at least a significant reduction) of the MRF resistance with equal speed by rapidly decreasing the current flowing through the EM coil and allowing the rheology of the magnetorheological fluid (e.g., fluid viscosity) to return to its normal, unstimulated state. The controller architecture 50 can also control the MRF joystick resistance mechanism 56 to generate MRF resistance, so as to have a continuous range of intensity or density within limits by utilizing the corresponding changes in the intensity of the EM field generated by the EM coil 166. Advantageously, the MRF joystick resistance mechanism 56 can provide reliable, substantially noiseless operation over extended periods. Additionally, the magnetorheological fluid can be formulated to be inherently non-toxic, 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 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 or joystick stiffness, thereby preventing the joystick from circumferentially rotating around a first axis (e.g., Figure 3 and Figure 4 The joystick rotates about the X-axis of coordinate diagram 118, while selectively generating a second resistance or joystick stiffness independent of the first resistance (joystick stiffness), thereby preventing the joystick from rotating about the second axis (e.g., the Y-axis of coordinate diagram 118); that is, making the first resistance and the second resistance have different values ​​as needed.

[0053] Now, turn to Figure 5A simplified top view illustrates a schematic diagram of a joystick support assembly 190 including an example MRF joystick device 52. In addition to the MRF joystick system 52, the joystick support assembly 190 includes a support structure 192. This support structure 192 is disposed adjacent to and may partially surround the base housing 62 of the MRF joystick device 52. The support structure 192 can be any structure or structural component suitable for mounting the MRF joystick device 52 at a desired location within a work vehicle; for example, within the cab 32 of the excavator 20 in this example. In some embodiments, the support structure 192 may be integrated into or otherwise attached to a handrail, console, or similar interior area of ​​the work vehicle that is adjacent to the operator's seat and easily accessible to the operator. The base housing 62 of the joystick device 52 is engaged to the support structure 192 via couplings 194, 196, which allow limited rotation of the base housing 62 relative to the support structure 192 along at least one DOF. In this particular example, connectors 194 and 196 take the form of universal joints, which allow the base housing 62 to rotate relative to the support structure 192 about two vertical axes within a limited angular range. Universal joints 194 and 196 include: a first pin joint pair 194 that allows the base housing 62 to rotate about the Y-axis of coordinate diagram 118 relative to the support structure 192 with a limited range; and a second pin joint pair 196 that allows the base housing 62 to rotate about the X-axis of coordinate diagram 118 with a limited range.

[0054] The JRP locking mechanism 198 is located between the base shell 62 of the MRF joystick device 52 and the surrounding support structure 192; for example, the JRP locking mechanism 198 can be placed at a certain height below or under the base shell 62 of the MRF joystick device 52, such as... Figure 5 The JRP locking mechanism 198 is movable between a locked state (in which the JRP locking mechanism 198 typically resides) and an unlocked state. In the locked state, the JRP locking mechanism 198 prevents adjustment of the joystick return position by rotatably securing the base housing 62 to the support structure 192. Conversely, in the unlocked state, the JRP locking mechanism 198 allows rotational movement between the base housing 62 and the support structure 192 of the MRF joystick assembly to the extent permitted by the universal joints 194, 196. This allows for operator adjustment of the joystick return position by modifying the angular orientation of the base housing 62 relative to the support structure 192, as discussed below.

[0055] In some embodiments, the JRP locking mechanism 198 may include one or more manually actuated locking devices that can be operated by an operator to switch the JRP locking mechanism between a locked and unlocked state. Examples of such manually actuated locking mechanisms include: retaining screws, clamping devices, spring-loaded plungers (which may engage in a divot or other recess provided on the exterior of the base housing 62), and similar devices. In other embodiments, the JRP locking mechanism 198 includes one or more actuated devices that can be controlled by the controller architecture 50 to switch the JRP locking mechanism 198 between a locked and unlocked state. For example, in some embodiments, the JRP locking mechanism 198 may include one or more rotary or linear devices, such as miniature clutch assemblies integrated into universal joint connectors 194, 196, which can be remotely engaged and disengaged by the controller architecture 50. In other implementations, the JRP locking mechanism 198 may include one or more linear devices mounted between the base housing 62 and the support structure 192, such that rotation of the base housing 62 can occur exclusively in conjunction with the extension and retraction of the linear devices. For example, in this latter case, the JRP locking mechanism 198 may include one or more hydraulic cylinders that are freely translatable when fluid flow is permitted between the cylinder chambers. One or more shut-off valves may also be interconnected with the cylinders and operationally coupled to the controller architecture 50. Commonly, such hydraulic cylinders and shut-off valves are referred to herein as "lockable piston devices". Figure 5 Two such lockable cylinder devices 200 and 202 are schematically identified below the base housing 62.

[0056] As used herein, the term "hydraulic fluid" is defined to encompass both non-magnetorheological and magnetorheological fluids that flow between variable-volume chambers of a hydraulic cylinder (and similar hydraulic devices) during operation of an MRF joystick system. Similarly, the term "hydraulic cylinder" is used herein with reference to a device comprising one or more hydraulic chambers and a translating member (piston) (regardless of form factor), the linear movement of which drives hydraulic fluid into or out of the chamber, or is driven by hydraulic fluid flowing into or out of the chamber. Finally, as noted above, the term "valve" refers to a hydraulic fluid (whether magnetorheological or non-magnetorheological in nature) that can be controlled to regulate the flow of hydraulic fluid through the valve body or passageway. In embodiments of an MRF where the valve controls the flow through the valve body by varying the magnetic field that affects the properties (viscosity) of the magnetorheological fluid, the valve may specifically be referred to as an "MRF valve". For ease of reference, this MRF valve, when controlled to adjust the MRF flow in a desired manner, can still be referred to as "moved" to a specific position (e.g., a shut-off position). For the purposes of understanding (as previously stated), an MRF valve may, strictly speaking, lack movable valve components. Finally, as appears herein, the term "shut-off valve" refers to a valve capable of selectively preventing or at least significantly impeding the flow of hydraulic fluid through its body.

[0057] Figure 6 The joystick support assembly 190 and the MRF joystick device 52 are further illustrated schematically in cross-sectional view, which is taken along a section parallel to the XY plane of coordinate legend 118 and extending through the joystick 60. (Common Reference) Figure 5 and Figure 6 The JRP locking mechanism 198 includes a first lockable cylinder device 200 and a second lockable cylinder device 202. Figure 6 The first lockable cylinder device 200 is shown in more detail in the schematic diagram. Although in Figure 6The second lockable cylinder device 202 is not shown, but in the illustrated example, the lockable cylinder devices 200 and 202 are substantially the same; therefore, the following description also applies to the second lockable cylinder device 202. Each lockable cylinder device 200 and 202 includes hydraulic cylinders 204 and 206 and an associated shut-off valve 208. The shut-off valve 208 is fluidly interconnected with the hydraulic cylinders 204 and 206 associated with it via a plurality of flow lines 210; and the electronic components of the shut-off valve 208 (actuator in the case of a non-MRF valve, EM coil in the case of an MRF valve) are further connected to the controller architecture 50 via one or more electrical connections 212, or to a power supply controlled by the controller architecture 50. For the purposes of the following description, each cylinder assembly section in the lockable cylinder assemblies 202, 204 is described as being fluidly interconnected with a separate shut-off valve 208; however, in other embodiments, the lockable cylinder assemblies 200, 202 may share a common shut-off valve that can be moved to a shut-off position to simultaneously prevent fluid flow between the chambers of the hydraulic cylinders 204, 206, thereby locking the cylinder piston 206 in the desired translational position.

[0058] Hydraulic cylinders 204 and 206 both include a cylinder body 204 and a piston 206 that can translate relative to the cylinder body 204. Similar to those included in the first lockable cylinder device 200, and as... Figure 6 The first lockable cylinder assembly 200 is clearly shown mounted between the lower part of the base housing 62 and the base plate of the support structure 192. Specifically, hydraulic cylinders 204 and 206 are housed within the cavity 214 of the support structure 190, with the lower end of cylinder 204 mounted to the support structure 192 via a first ball joint connector 216, and the outer end of piston 206 engaged to the base housing 62 via a second ball joint connector 218. In other implementations, different mounting interfaces can be used if hydraulic cylinders 204 and 206 can tilt or otherwise move to accommodate changes in the angular orientation of the base housing 62 of the MRF joystick assembly 52 relative to the support structure 192. In this respect, and as previously discussed, when the JRP locking mechanism 198 is in the unlocked state, universal joints 194 and 196 allow the base housing 62 to rotate about the X and Y axes of coordinate diagram 118. Alternatively, the universal joint couplings 194 and 196 can be positioned such that the angular orientation of the base housing 62 relative to the support structure 192 is adjusted around the center point or origin of rotation with the control lever. Figure 6 The coordinates are approximately aligned with the center point or origin of the coordinate system (as shown in Figure 118); however, this is not necessary in all embodiments. Similarly, it can be... Figure 5 The hydraulic cylinders 204 and 206 included in the other lockable cylinder device 202 shown provide a similar installation scheme.

[0059] MRF joystick system 22 ( Figure 1 The controller architecture 50 can control the shut-off valve 208 to selectively allow or prevent fluid flow between the hydraulic chambers of the hydraulic cylinders 204, 206 included in the respective lockable cylinder devices 200, 202. When adjusting the flow of non-magnetorheological hydraulic fluid, each shut-off valve section 208 can be a non-MRF valve, such as a solenoid-driven spool valve or stopper valve. Alternatively, in an implementation where the magnetorheological fluid is guided through valve 208 as it flows between the chambers of hydraulic cylinders 204, 206, the shut-off valve 208 can be an MRF valve (e.g., in conjunction with the above). Figure 3 and Figure 4 (The described MRF valve 56 is similar or substantially the same). In implementations where the shut-off valve 208 is an MRF valve, for design simplification in certain cases, the shut-off valve 208 may be combined with the aforementioned MRF valve 56 as a single unit or valve assembly. In other embodiments, the shut-off valve 208 may be a separate MRF valve; or it may be replaced by a non-MRF shut-off valve containing valve components that is moved between an open and closed position by an actuator under the command of the controller architecture 50. Furthermore, although in this example the JRP locking mechanism 198 is implemented using lockable cylinder devices 202, 204, it should be appreciated that in other embodiments, other types of linear devices capable of being selectively locked in a given translational position by the controller architecture 50 may be used instead of lockable cylinder devices 202, 204.

[0060] During normal or standard use of the MRF joystick 52, the controller architecture 50 commands the shut-off valve 208 to move to the shut-off position, or otherwise prevents fluid flow between the chambers of the hydraulic cylinders 204, 206. This prevents translation of the piston 206 included in the hydraulic cylinders 204, 206, thereby also preventing rotation of the base housing 62 relative to the surrounding support structure 192. In order to subsequently place the JRP locking mechanism 198 in its unlocked state, the controller architecture 50 commands the shut-off valve 208 to open (or otherwise allow fluid flow between the chambers of the hydraulic cylinders 204, 206), thereby freeing the piston 206 of the hydraulic cylinders 204, 206 to translate in conjunction with the rotation of the base housing 62 relative to the support structure 192. Thus, when the JRP locking mechanism 198 is unlocked by the controller architecture 50, operator adjustment of the angular orientation of the base housing 62 of the MRF joystick 52 relative to the support structure 192 is possible at least to the extent permitted by the universal joints 194, 196. In at least some embodiments, the controller architecture 50 commands the MRF joystick resistance mechanism 56 to apply MRF resistance at a level sufficient to prevent movement of the joystick 60 relative to the base housing 62, thereby facilitating operator adjustment of the angular position or orientation of the base housing 62 relative to the support structure 192; the MRF resistance thus applied is referred herein to as “maximum” or “peak” MRF resistance. The application of this maximum MRF resistance effectively locks or secures the joystick 60 to the base housing 62, allowing the operator to easily adjust the angular orientation of the base housing 62 relative to the support structure 192 as needed by simply grasping and manipulating the handle of the joystick 60.

[0061] As by Figure 5 As indicated by key 220 in the upper part of the diagram, the current joystick return position of the MRF joystick device 52 is represented by the first diagonal mark 222. When the MRF joystick device 52 is such that the joystick 60 can rotate relative to the base housing 62 about two vertical axes, the joystick return position is the angle or orientation in which the joystick 60 is biased toward its return. For example... Figure 6 As most clearly shown in the illustrated example, the base housing 62 of the MRF joystick device 52 is not tilted or angled relative to the support structure 192. This can be understood by comparing the angular orientation of coordinate diagram 118 (here, representing the joystick's reference frame) with that of the second coordinate diagram 224, which appears in... Figure 6The lower part represents the reference frame of the support structure 192. In an illustrative example where the joystick return position of the MRF joystick device 52 is in the default unadjusted or "true center" position, the Z-axis in coordinate diagrams 118 and 224 extends parallel; for example, upward along the illustrated orientation, and may be such that the Z-axis of coordinate diagram 118 (and correspondingly, the joystick handle 110) extends substantially vertically. When the base housing 62 is rotated relative to the support structure 192 to a new angular position, the Z-axis of joystick coordinate diagram 118 will differ from the Z-axis of support structure coordinate diagram 224 by a certain angular deviation. Similarly, the joystick return position will change in conjunction with the change in the angular orientation of the base housing 62 (coordinate diagram 118) relative to the support structure 192 (coordinate diagram 224).

[0062] In the current embodiment where the JRP locking mechanism 198 is located outside the base housing 62 of the MRF joystick device 52, the following process can be performed via the controller architecture 50 to enable the work vehicle operator to make JRP adjustments. First, as shown by arrow 223 ( Figure 5 The controller architecture 50 receives operator input to initiate adjustment of the joystick return position of the MRF joystick device 52. This operator input can be received via manual actuation of a physical input (such as a button or switch) located on the MRF joystick device 52. As an arbitrary example, in one possible approach, the operator of the work vehicle can press and hold a button located on or near the MRF joystick device 52 (e.g., on the upper part of the joystick handle 110 or on the upper surface of the housing 62) to enable operator adjustment of the joystick return position of the MRF joystick device 52. The operator can then release the button (or press it a second time) to terminate or complete the JRP adjustment process if needed. In other implementations, the work vehicle operator can provide input to initiate the JRP adjustment process in another manner, such as by interacting with a GUI generated on the display device 80 to select on-screen options, thereby enabling adjustment of the joystick return position to the operator's preference. This GUI can also allow other MRF-related aspects of the MRF joystick 52 to be adjusted to operator preferences, such as generating the force required for the following MRF stop.

[0063] In response to receiving operator input initiating the JRP regulation process, controller architecture 50 commands MRF joystick resistance mechanism 56 to apply maximum or peak MRF resistance at a level sufficient to prevent (or at least substantially inhibit) rotation of the joystick relative to base housing 62. In embodiments where JRP locking mechanism 198 is essentially non-manual, controller architecture 50 also commands JRP locking mechanism 198 to unlock by combining maximum MRF resistance generated by MRF joystick resistance mechanism 56. In this example, and as described above, controller architecture 50 unlocks JRP locking mechanism 198 by commanding shut-off valve 208 to move to the open position, or otherwise temporarily permitting fluid flow between the opposing hydraulic chambers of cylinders 204, 206. Specifically, when shut-off valve 208 is a non-MRF valve, controller architecture 50 commands the associated valve actuator to move valve components to the closed position, thereby preventing hydraulic fluid flow between the valve body and the cylinder chambers. When the shut-off valve 208 is instead an MRF valve, the controller architecture 50 adjusts the power supplied to the EM coil within the valve 208 to reduce the intensity of the EM field (or completely terminate the generation of the EM field), allowing the magnetorheological fluid to flow through the valve body with relatively low flow resistance. With fluid flow now permitted between the opposing chambers of the hydraulic cylinders 204, 206, the piston 206 of cylinders 204, 206 can translate freely in conjunction with the angular displacement of the base housing 62 relative to the support structure 192. The vehicle operator holding the handle 110 of the control lever 60 can thus rotate the control lever 60 and therefore the base housing 62 to any desired angular position or orientation relative to the support structure 192 permitted by the universal joints 194, 196. Adjusting or modifying the angular orientation of the base housing 62 in this way results in a corresponding adjustment of the return position of the control lever of the MRF control lever assembly 52.

[0064] After the joystick handle 110 is turned to the operator-adjusted joystick return position, the operator provides input to the controller architecture 50 to terminate the JRP adjustment process. Upon receiving this operator input, the controller architecture 50 commands the JRP locking mechanism 198 to return to the locked state, thereby preventing further rotation of the base housing 62 relative to the support structure 192. In an exemplary example, the controller architecture 50 relocks the JRP locking mechanism 198 by returning the shut-off valve 208 to the closed or shut-off position (when the shut-off valve 208 is a non-MRF valve), or by causing the EM coil in the shut-off valve 208 to generate an electromagnetic field of sufficient strength to substantially prevent fluid flow through the valve body (when the shut-off valve 208 is implemented as an MRF valve). Once locked again, the JRP locking mechanism 198 prevents rotation of the base housing 62 relative to the support structure 192, thereby fixing the base housing 62 and thus the joystick return position at the most recently selected angular orientation. Simultaneously or shortly thereafter, as the JRP locking mechanism 198 returns to the locked state, the controller architecture 50 also commands the MRF joystick resistance mechanism 56 to stop generating maximum MRF resistance. This allows the work vehicle operator to once again rotate the joystick 60 relative to the base housing 62 about the X and Y axes of coordinate diagram 118, while the base housing 62 remains fixed to the support structure 192. Normal use of the MRF joystick device 52 can then be restored, and the joystick 60 is now biased toward the most recently selected joystick return position.

[0065] In some implementations, the controller architecture 50 of the MRF joystick system 22 can transfer the JRP setting data 225 after the JRP adjustment process. Figure 5The JRP setting data 225 is stored in computer-readable storage 48. The JRP setting data 225 can identify the joystick return position adjusted by the operator, which can be stored as coordinates, as an angular deviation from the unmodified joystick return position, or in another manner. Additionally, in some embodiments, the controller architecture 50 can store data in storage 48 that associates unique operator identification data with various JRP settings. This, in turn, allows the MRF joystick system 22 to automatically assign the stored joystick position setting to a given MRF joystick device (e.g., MRF joystick device 52) when a specific work vehicle operator is identified (e.g., after the operator logs in using a unique PIN). The foregoing applies to embodiments where the MRF joystick device 22 has force feedback capability or is otherwise independently movable between different JRP settings. In other implementations, for the purpose of such automatic adjustment, the controller architecture 50 may not store this JRP setting data 225 in computer-readable storage 48. However, in an alternative embodiment where the JRP locking mechanism is located inside the base housing 62 of the MRF joystick device 42, the JRP setting data can still be usefully stored in the computer-readable storage 48, as follows: Figures 8 to 11 The subject of discussion.

[0066] Additional examples of work vehicles advantageously equipped with the MRF joystick system

[0067] Therefore, the foregoing has described an MRF joystick system including one or more joysticks biased toward the joystick return position (which can be adjusted to operator preference). While the preceding description has primarily focused on a specific type of work vehicle (excavator) including specific joystick-controlled work vehicle functions (boom assembly movement), implementations of the MRF joystick system are adaptable to integration into a wide range of work vehicles that include joystick devices for controlling changes in work vehicle functions. Referring now... Figure 7 , Figure 7 The upper left side illustrates an example work vehicle, the middle section illustrates an example MRF control lever device, and the right side illustrates the functions of the controlled work vehicle. Figure 7 The lower section illustrates other example work vehicles that may be equipped with MRF joysticks. Specifically, in Figure 7 The upper part illustrates three additional examples of such work vehicles, including a wheel loader 226, a skid steer loader (SSL) 228, and a motorized grader 230. First, regarding the wheel loader 226, the wheel loader 226 can be equipped with an example MRF joystick device 232 housed within the cab 234 of the wheel loader 226. (As in...) Figure 7As indicated, the MRF joystick 232 can be used to control the movement of the FEL 236 terminated at the bucket 238. Comparatively, two MRF joysticks 240 can be placed in the cab 242 of the example SSL 228 and used not only to control the movement of the FEL 244 and its bucket 246, but also, in a known manner, to further control the movement of the chassis 248 of the SSL 228. Finally, the motorized grader 230 also includes two MRF joysticks 240 placed in the cab 252 of the motorized grader 230. The MRF joystick 250 can be used to control the movement of the motorized grader chassis 254 (by controlling a first drive that drives the rear wheels of the motorized grader and possibly a second (e.g., hydrostatic) drive that drives the front wheels), and the movement of the grader's blade 256 (e.g., by rotation and angle adjustment of the blade-circle assembly 258, and adjustment of the lateral angle of the blade 256).

[0068] Any or all of the example wheel loaders 226, SSL 228, and motorized graders 230 may be equipped with a work vehicle MRF joystick system of the type described herein, i.e., an MRF joystick system including at least one joystick device with a joystick biased toward the joystick return position, an MRF joystick resistance mechanism, a JRP locking mechanism, and a controller architecture coupled to the MRF joystick resistance mechanism and the JRP locking mechanism. Furthermore, the controller architecture may selectively enable operator adjustment of the joystick return position. To enable operator JRP adjustment, the controller architecture may command the JRP locking mechanism to unlock (if applicable) while simultaneously commanding the MRF joystick resistance mechanism to apply MRF resistance at a predetermined level until the JRP adjustment process is complete. In embodiments where the JRP locking mechanism 70 is located outside the base housing 62 to prevent (or at least largely prevent) rotation of the joystick 60 relative to the base housing 62 during the JRP adjustment process, the controller architecture 50 may command the MRF joystick resistance mechanism 56 to generate maximum MRF resistance. In contrast, in an embodiment where the JRP locking mechanism is located inside the base housing, the controller architecture 50 may instead command the MRF joystick resistance mechanism 56 to apply a smaller (e.g., minimum or zero) MRF resistance during the JRP adjustment process, as further combined below. Figures 9 to 11 The subject of discussion. Figure 7 The lower part illustrates further examples of work vehicles equipped with an implementation of the MRF joystick system, including a tractor 260 equipped with an FEL, a logging stacker 262, a timber harvester 264, a combine harvester 266, and a bulldozer 268.

[0069] An example MRF joystick system including a JRP locking mechanism located inside the base housing of the MRF joystick device.

[0070] Next, proceed to Figure 8 and Figure 9 A simplified cross-sectional view of the MRF joystick device 270 is shown, as depicted according to another exemplary embodiment of this disclosure. In many respects, the MRF joystick device 270 is similar to... Figures 1 to 6 The MRF joystick device 52 shown, and Figure 8 and Figure 9 The cross sections generally correspond to Figure 3 and Figure 4 The cross-section. The labels have been carried over as appropriate, and to avoid length, the details of the MRF joystick device 270 have not been discussed again. Figure 8 and Figure 9 ) and the aforementioned MRF joystick device 52 ( Figure 3 and Figure 4 Common components shared by all. Like the aforementioned MRF joystick device 52 ( Figure 3 and Figure 4 Similar to the MRF joystick system 270, the JRP locking mechanism 272 is movable between a locked and unlocked state. However, in the case of the MRF joystick device 270, the JRP locking mechanism 272 is integrated into the base housing 62 of the joystick device 270 (placed within the base housing). Two biasing members 284 are also disposed within the base housing 62 of the MRF joystick device 270 and cooperate to bias the joystick 60 toward the joystick return position. In this example, the biasing members 284 take the form of a mechanical (e.g., wireform) spring, and are therefore referred to hereafter as "bias spring 284". However, in other embodiments, the biasing members 284 may take other forms adapted to apply a biasing force that causes the joystick 60 to rotate toward the joystick return position as the joystick 60 moves from the joystick return position. Examples of other types of biasing members suitable for use in the MRF joystick device 270 include gas springs, mechanical springs, and magnetic components.

[0071] Although contained within the housing 62 in the illustrated embodiment, the JRP locking mechanism 272 of the MRF joystick device 270 is similar to the above in several aspects. Figure 5 and Figure 6The described external JRP locking mechanism 272 includes two hydraulic cylinders 274, 276 and one or more shut-off valves 278 fluidly interconnected with the hydraulic cylinders 274, 276 via flow line connections 280. In this particular example, the shut-off valves 278 are generally exemplified as MRF valves, each having a configuration similar to that of an MRF valve 56 also contained in the housing 62 and used to selectively apply MRF resistance to inhibit joystick movement. An electrical connection 282 is provided from the power source 177 to the shut-off valves 278, and the controller architecture 50 adjusts the power supply to the shut-off valves 278 by modifying the current or voltage applied to the EM coil within the valves 278, thereby providing the desired flow control functionality. Again, in an alternative embodiment, the shut-off valves 278 can be readily implemented as non-MRF valves, comprising valve components, such as plugs, slides, or plates, positioned by the controller architecture 50 using solenoids or other electro-actuators. The hydraulic cylinders 274 and 276 of the MRF joystick device 270 are similar to the hydraulic cylinders 204 and 206 included in the MRF joystick device 52, as described above. Figure 6 As described; however, in this example, hydraulic cylinders 274 and 276 are increasingly compact and integrated into the base housing 62 of the MRF joystick device 270. Additionally, in Figure 8 and Figure 9 In the example, hydraulic cylinders 274 and 276 are effectively used as adjustable spring seats that set the return position of the MRF joystick device 270 by changing the position of the bias spring 284 acting on the joystick 60, as discussed further below.

[0072] As mentioned above, in the illustrated example, the JRP locking mechanism 272 includes two hydraulic cylinders 274 and 276 and two bias springs 284. In other embodiments, depending on the joystick device design and the manner in which the joystick can move relative to the base housing 62, the JRP locking mechanism 272 may include more or fewer hydraulic cylinders and bias springs; for example, in an implementation where the joystick 60 can rotate about a single axis or otherwise move along a single DOF, the JRP locking mechanism 272 may include a single spring-cylinder pair, or perhaps two spring-cylinder pairs positioned on opposite sides of the joystick 60. Hydraulic cylinders 274 and 276 each include a cylinder body 274 and a translational piston 276, the end of which is slidably disposed within the cylinder bore of the cylinder body 274. The outer terminal of each cylinder body 274 (the rightmost end of the cylinder body 274 along...) Figure 8 and Figure 9The orientation shown is mounted to the internal structural feature 286 of the base housing 62. This mounting is achieved using a movable coupling (such as a ball joint 288), allowing cylinders 274, 276 to tilt or swivel in conjunction with operator rotation of the lever 60 and deflection of bias springs 284. Opposite ends of hydraulic cylinders 274, 276, and specifically the outer ends (rod ends) of each piston 276, serve as spring seats supporting at least one of the bias springs 284. Pistons 276 may terminate in spring retainers or spring seats 290, which secure the bias springs 284 to the outer ends of the pistons. As shown, the opposite ends of the bias springs 284 are engaged to the lower portion of the lever 60, and specifically secured to the lower lever extension 120.

[0073] Based on the aforementioned structural design, each bias spring 284 can be compressed or stretched to apply a biasing force that causes the lever 60 to return to the lever return position. Regarding Figure 8 The bias spring 284 shown, in particular, is stretched and compressed in conjunction with the rotation of the control lever about the X-axis of coordinate diagram 118. From Figure 8 Starting from the joystick return position, rotating the joystick handle 110 to the left causes the lower joystick extension 120 to move to the right, thereby pressing the bias spring 284 against the spring seat 290. Under this compression, the bias spring 284 applies a thrust to the lower part or extension 120 of the joystick 60, causing the joystick 60 to return to the joystick return position. Conversely, rotating the joystick handle 110 to the right causes the lower joystick extension 120 to move to the left, thereby stretching the bias spring 284. Therefore, in this case, the bias spring 284 applies a pull to the lower extension 120 of the joystick 60, again causing the joystick 60 to return to the joystick return position. Similarly, Figure 9 The bias spring 284 shown, in conjunction with the rotational extension and retraction of the lever about the Y-axis of coordinate diagram 118, further biases the lever 60 toward the lever return position. Essentially, the lever return position is the angular position where the net spring force applied to the lever 60 becomes balanced; and in the illustrated example, it is the position where the individual bias springs of bias spring 284 are normally in a non-deflected state and little or no spring force is applied to the lower lever extension 120. Therefore, the translational movement of the piston end 276 and the spring seat 290 adjusts the angular position of the lever 60, where the bias spring 284 is in its non-deflected state, and thus adjusts the bias spring 284 to cause the lever 60 to return toward the rotated lever return position.

[0074] The operator adjustment of the joystick return position of the MRF joystick device 270 can be accomplished as follows. First, the operator provides some form of input (such as that received via the controller architecture 50) to initiate the JRP adjustment process. As mentioned above in conjunction with the MRF joystick device 52, operator input can be provided through physical interaction with a manual input set on the joystick 60 or the housing 62; or alternatively, it can be done via operator interaction with a GUI generated on the screen of the display device 80. In response to this operator input, the controller architecture 50 unlocks the JRP locking mechanism 272 to allow operator adjustment of the joystick return position. Figure 8 and Figure 9 In this implementation, as previously described, the controller architecture 50 unlocks the JRP locking mechanism 272 by commanding the shut-off valve 278 to temporarily allow fluid flow between the opposing chambers of cylinders 274, 276. This allows the pistons 276 of each cylinder 274, 276 and the spring seats 290 to translate freely in conjunction with operator-induced rotation of the joystick 60. Thus, the work vehicle operator can grasp the joystick handle 110 and rotate the joystick 60 to any chosen joystick return position permitted within the physical limitations of the MRF joystick assembly 270. As the operator moves the joystick 60 in this manner, the bias spring 284 deflects to apply force to the piston 276 associated with it, then translates the piston to the new position, thereby reducing the spring force generated by operator movement of the joystick 60 during JRP adjustment to zero.

[0075] After adjusting the joystick 60 to the desired joystick return position, the operator then inputs an additional input into the MRF joystick system 270 to terminate the JRP adjustment process. Upon receiving this input, the controller architecture 50 commands the JRP locking mechanism 272 to return to the locked state that the JRP locking mechanism 272 normally resides in during the use of the MRF joystick device 270. In this example, the controller architecture 50 commands the shut-off valve 278 to close again or otherwise prevent fluid flow between the chambers of the cylinder contained in the MRF joystick device 270; for example, when the shut-off valve 278 is an MRF valve, as shown, the controller architecture 50 fully energizes the EM coil contained in the MRF valve 278 to prevent or at least significantly impede the flow of magnetorheological fluid through the valve 278. The piston 276 and the corresponding spring seat 290 are thus fixed in their current translational position, thereby positioning the bias spring 284 to reside in the new operator-adjusted joystick return position in a substantially undeflected state. Supported in this manner by piston 276, the bias spring 284 within the MRF joystick 270 now biases the joystick 60 of the MRF joystick 270 to the joystick return position adjusted by the operator. The operator can then return the MRF joystick 270 to normal use until the JRP adjustment process is restarted.

[0076] As described above, the MRF joystick system 22 for work vehicles enables operator adjustment of the joystick return position of a given MRF joystick device (here, MRF joystick device 270) using a highly intuitive manual drive process. During this manual drive process, the operator rotates the joystick (e.g., joystick 60) to the desired joystick return position. An intuitive JRP position adjustment process is established by allowing the operator to physically move the joystick handle 110 to the desired JRP position, during which the operator can typically relax their arms and wrists to allow the joystick to gradually move to a JRP position best suited to the operator's unique physiology. Furthermore, this manual drive adjustment process typically eliminates the need for linear or rotary actuators in achieving the desired JRP position. As a result, the overall cost and complexity of the MRF joystick system can be reduced.

[0077] In embodiments where the JRP locking mechanism is located outside the base shell, including... Figure 8 and Figure 9In the example implementation shown, when the operator-adjusted joystick return position shifts from the default or unmodified joystick return position, it may be desirable to adjust the position generating certain MRF effects. For example, when a grip or tactile MRF stop is desired to be generated during joystick operation, it may be desirable to adjust the position generating the MRF stop in conjunction with the operator adjustment of the joystick return position. Alternatively, MRF motion stops may be generated at certain positions to compensate for asymmetries in the joystick ROM that would otherwise be caused by the displacement of the joystick return position relative to the default, unmodified, or "true center" position. Now, in conjunction with Figure 10 and Figure 11 Further description is provided in this regard; it is noted that in other implementations, such position adjustment may not be possible in the location where the MRF effect is generated, especially in many cases where the angular deviation between the operator-adjusted joystick return position and the default joystick return position is typically relatively small.

[0078] Figure 10 and Figure 11 This schematically illustrates an example of how adjusting the joystick resistance position can modify the positioning of certain MRF resistance effects. (Initial reference) Figure 10 Figure 292 illustrates an example MRF joystick device (e.g., when the joystick return position is held in the default or unadjusted position (as shown by reference numeral 296)). Figure 8 and Figure 9 The joystick device 270 shown has a default joystick ROM 294. Figure 298 identifies different cross-shading patterns of the default joystick ROM 294 and the default joystick return position 296, as well as example default positions of the two MRF stops 300, 302. From the default joystick return position 296, the operator can rotate the joystick about the X-axis or Y-axis of coordinate figure 118 in any given direction 304, 306, 308, 310. When the joystick is rotated in direction 306 (to the operator's right) to the stop position 300, the controller architecture 50 commands the MRF joystick resistance mechanism 56 to generate increased MRF resistance to inhibit further rotation of the joystick in the rightward direction 304, thereby producing the desired MRF stop effect. Similarly, when the joystick is rotated in direction 308 (to the operator's left) to the stop position 300, the controller architecture 50 commands the MRF joystick resistance mechanism 56 to generate increased MRF resistance to inhibit further rotation of the joystick, thus producing the desired MRF stop effect. Due to the physical limitations of the MRF joystick device itself, the joystick typically cannot rotate beyond the outer periphery 312 of the default joystick ROM 294.

[0079] Transfer to Figure 11 Figure 316 illustrates an example scenario following an operational adjustment of the joystick return position from the default position (label 296) to the most recently selected joystick return position 314 (label 317). As shown in Figure 316, the controller architecture 50 of the MRF joystick system can perform either or both of two functions to modify the operation of the MRF joystick based on the operator's adjustment of the joystick return position. First, the controller architecture 50 can generate an MRF motion stop to limit the joystick ROM, such as... Figure 11 The modified ROM is indicated by a circled graphic 318 (hereinafter referred to as "Modified ROM 318"). When the joystick is rotated to the right 306 from the Modified Joystick Return Position (marked 314), the controller architecture 50 can issue a command to the MRF joystick resistance mechanism 56 to engage with the Modified ROM. An MRF joystick stop 318 is generated at the termination position corresponding to the outer periphery 322 of 318. This makes the ROM or travel of the joystick when rotating from the modified joystick return position along the right direction 306 about the X-axis of coordinate diagram 118 equal to the joystick travel when rotating from the modified joystick return position along the left direction 310 about the X-axis of coordinate diagram 118. Without generating the MRF motion stop 318, the joystick can rotate along the right direction 306 to the outer periphery 312 of the default ROM, resulting in a longer joystick travel along the right direction 306 than along the left direction 310. Therefore, by generating the MRF joystick stop 318 encountered when rotating the joystick along the right direction 306, the symmetry of the joystick rotation about the X-axis of coordinate diagram 118 relative to the operator-adjusted joystick return position (marked 314) is maintained.

[0080] In a similar respect, when the joystick rotates downwards 308 (towards the operator) about the Y-axis of coordinate diagram 118 from the modified joystick return position (marked 314), the controller architecture 50 can generate a second MRF motion stop 320 in place to further balance the angular ROM of the joystick about this axis. Without generating the MRF motion stop 320, the operator might potentially rotate the joystick downwards 308 to the outer periphery 312 of the default ROM, again resulting in rotational asymmetry relative to the modified joystick return position (marked 314). By generating the MRF joystick stop 318, which prevents overtravel of the joystick when rotated downwards 308, the symmetry of the joystick ROM when rotating the joystick about the Y-axis of coordinate diagram 118 is restored. A similar MRF motion stop can also be generated along the following portion of the outer periphery 322 of the modified or restricted joystick ROM 318: this portion is not aligned with the outer periphery 312 of the default joystick ROM 294. In this manner, controller architecture 50 utilizes the MRF capability of the MRF joystick device to impose artificial limitations on the joystick travel, maintaining the symmetry of the joystick ROM in the direction opposite to the displacement of the modified joystick return position (marked 314) relative to the default joystick return position (marked 296). In the direction corresponding to the displacement of the modified joystick return position (marked 314) relative to the default joystick return position (marked 296), the joystick ROM remains physically constrained by the MRF joystick device. In other embodiments, such MRF motion stops 319, 320 may not be generated.

[0081] Similarly, in at least some implementations, the position of the MRF stops 300 and 302 can be adjusted in conjunction with operator adjustment of the joystick return position (marked 314). As the joystick return position shifts in a specific manner due to operator adjustment (in... Figure 11In the example, along the upward and leftward directions, the positions of MRF stops 300 and 302 can be shifted accordingly. Additionally, when rotating about a specific axis on which one or more MRF motion stops are applied as desired, the positions generating MRF stops 300 and 302 can be adjusted to accommodate any truncation of the joystick ROM. To determine the appropriately modified position that generates this MRF effect after operator adjustment of the joystick return position, the controller architecture 50 tracks joystick movement during the aforementioned operator JRP adjustment process and stores the position of the operator-adjusted joystick return position at the end of the JRP adjustment process; for example, the operator-adjusted joystick return position can be stored as coordinates or as an angular deviation from the default joystick return position. Then, the controller architecture 50 considers the position of the modified joystick return position (marked 314) along with relevant data (e.g., data indicating the default ROM of the joystick, such as the default angular range from which the joystick can be rotated about a given axis from the default joystick return position (marked 296)) to determine the appropriate positions for generating any MRF stops (e.g., MRF stops 300, 302) and any MRF motion stops (e.g., MRF motion stops 319, 320) as needed.

[0082] Examples of MRF joystick systems for work vehicles

[0083] For ease of reference, the following examples of MRF joystick systems for work vehicles are also provided and numbered.

[0084] 1. In one embodiment, a work vehicle MRF joystick system for use on a work vehicle is provided. The work vehicle MRF joystick system includes a joystick assembly having a base housing and a joystick, the joystick being rotatable relative to the base housing and biased toward a joystick return position. An MRF joystick resistance mechanism is controllable to change the MRF resistance that impedes movement of the joystick relative to the base housing. A controller architecture is coupled to the MRF joystick resistance mechanism and configured to: (i) selectively initiate operator adjustment of the joystick return position by a work vehicle operator; and (ii) when operator adjustment of the joystick return position is initiated, command the MRF joystick resistance mechanism to maintain the MRF resistance at a predetermined level until operator adjustment of the joystick return position is terminated.

[0085] 2. The MRF joystick system for a work vehicle according to Example 1 further includes a JRP locking mechanism movable between the following states: an unlocked state, in which the JRP locking mechanism allows adjustment of the joystick's return position; and a locked state, in which the JRP locking mechanism prevents adjustment of the joystick's return position.

[0086] 3. The work vehicle MRF joystick system according to Example 2, wherein the JRP locking mechanism is external to the base housing; and the controller architecture is configured to maintain the MRF resistance substantially at its maximum level until operator adjustment of the joystick to the return position is terminated.

[0087] 4. The work vehicle MRF joystick system according to Example 2, wherein the JRP locking mechanism is inside the base housing; and the controller architecture is configured to maintain the MRF resistance at a minimum level until operator adjustment of the joystick to the return position is terminated.

[0088] 5. The MRF joystick system for the work vehicle according to Example 2, wherein the controller architecture is coupled to the JRP locking mechanism and is further configured to: (i) command the JRP locking mechanism to move to the unlocked state upon receiving an operator adjustment to the joystick return position; and (ii) cause the JRP locking mechanism to return to the locked state upon terminating the operator adjustment to the joystick return position.

[0089] 6. The work vehicle MRF joystick system according to Example 2 further includes a support structure adjacent to the base housing, and a connector that engages the base housing to the support structure. The JRP locking mechanism is connected between the support structure and the base housing. When the JRP locking mechanism is in the unlocked state, the connector allows the base housing to rotate relative to the support structure in at least one degree of freedom.

[0090] 7. The MRF joystick system for the work vehicle according to Example 2, wherein the JRP locking mechanism includes a hydraulic cylinder having opposing hydraulic chambers. A shut-off valve is fluidly connected between the opposing hydraulic chambers and operatively coupled to the controller architecture. The shut-off valve can be controlled to selectively prevent fluid flow between the opposing hydraulic chambers to lock the hydraulic cylinder in a translational position.

[0091] 8. The MRF joystick system for a work vehicle according to Example 7, wherein the hydraulic cylinder is mechanically connected between the base housing and the lower part of the joystick.

[0092] 9. The work vehicle MRF joystick system according to Example 7 further includes a support structure to which the base housing is movably mounted. The hydraulic cylinder is mechanically connected between the base housing and the support structure.

[0093] 10. The work vehicle MRF joystick system according to Example 7, wherein the shut-off valve includes an MRF valve that is selectively energized by the controller architecture to substantially prevent MRF fluid from flowing through the MRF valve when the JRP locking mechanism is in the locked state.

[0094] 11. The work vehicle MRF joystick system according to Example 1, the work vehicle MRF joystick system further includes a computer-readable storage device coupled to the controller architecture. The controller architecture is configured to store JRP setting data in the computer-readable storage device after the work vehicle operator adjusts the joystick return position, wherein the JRP setting data describes the operator-adjusted joystick return position of the joystick device.

[0095] 12. The work vehicle MRF joystick system according to Example 11, wherein the controller architecture is further configured to: (i) selectively generate an MRF resistance effect at a predetermined position encountered when the joystick is rotated about a rotation axis, the MRF resistance effect taking the form of an MRF stop and an MRF movement stop; and (ii) adjust the predetermined position for generating the MRF resistance effect when the operator adjustment of the joystick return position deviates from the default joystick return position.

[0096] 13. The MRF joystick system for a work vehicle according to Example 12, wherein the MRF resistance effect takes the form of an MRF motion stop. The controller architecture is configured to generate the MRF motion stop at a location where a first ROM and a second ROM of the joystick are substantially balanced. The first ROM is measured when the joystick rotates about the axis of rotation in a first direction from the operator-adjusted joystick return position; simultaneously, the second ROM is measured when the joystick rotates about the axis of rotation in a second direction opposite to the first direction.

[0097] 14. In some other embodiments, the work vehicle MRF joystick system includes a joystick assembly having a base housing and a joystick rotatable relative to the base housing and biased toward a joystick return position. The work vehicle MRF joystick system further includes: an MRF joystick resistance mechanism controllable to change the MRF resistance that impedes movement of the joystick relative to the base housing; a JRP locking mechanism external to the base housing; and a controller architecture coupled to the MRF joystick resistance mechanism and the JRP locking mechanism. The JRP locking mechanism is movable between a locked state preventing adjustment of the joystick return position and an unlocked state allowing adjustment of the joystick return position. The controller architecture is configured to: (i) when receiving an operator adjustment to return the joystick to the position, command the MRF joystick resistance mechanism to generate a maximum MRF resistance that substantially prevents movement of the joystick relative to the base housing; and (ii) when terminating the operator adjustment to return the joystick to the position, command the MRF joystick resistance mechanism to remove the maximum MRF resistance.

[0098] 15. The work vehicle MRF joystick system according to Example 14, wherein the controller architecture is coupled to the JRP locking mechanism and is further configured to: (i) command the JRP locking mechanism to move to the unlocked state upon receiving an operator adjustment of the joystick return position; and (ii) cause the JRP locking mechanism to return to the locked state upon terminating the operator adjustment of the joystick return position.

[0099] in conclusion

[0100] The foregoing has provided a work vehicle MRF joystick system including at least one joystick biased to return to the joystick return position (adjustable to operator preference). Implementations of the MRF joystick system enable adjustment of the joystick return position using an intuitive manual actuation process, in which the operator moves the joystick to the desired return position by physically manipulating the joystick handle. This manually actuated JRP adjustment process not only provides an intuitive mechanism by which the work vehicle operator can adjust the joystick return position to optimally suit their unique physiology, but also allows for the elimination (or reduction of reliance on) actuators that would otherwise be employed to provide actuator-driven adjustment of the joystick return position. The implementation of the MRF joystick system utilizes the unique MRF capability of the MRF joystick (or multiple joysticks) included in the joystick system to enable this manually driven JRP adjustment method; for example, by setting the MRF resistance at a predetermined level (e.g., minimum or zero level in an implementation where the JRP locking mechanism is inside the base housing, or maximum level in an implementation where the JRP locking mechanism is outside the base housing) until the operator terminates the adjustment of the joystick to the return position.

[0101] As used herein, unless the context clearly indicates otherwise, the singular form of the description is intended to include the plural form. It should also be understood that the term “comprise and / or comprising” as used herein specifies the presence of a defined feature, element, step, operation, element, and / or component, rather than excluding the presence or addition of one or more other features, elements, steps, operations, elements, components, and / or combinations thereof.

[0102] The description of this disclosure has been presented for purposes of illustration and description, but is not intended to be exclusive or to limit the disclosure to its disclosed form. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of this disclosure. The embodiments expressly referenced herein were chosen and described in order to best explain the principles of this disclosure and its practical application, and to enable those skilled in the art to understand this disclosure and recognize many alternatives, modifications, and variations to the described examples. Therefore, various other embodiments and implementations besides those expressly described are within the scope of the appended claims.

Claims

1. A magnetorheological fluid joystick system (22) for use on a work vehicle (20), the work vehicle magnetorheological fluid joystick system (22) comprising: The joystick devices (52, 54) include: Base shell (62); and A joystick (60) is rotatable relative to the base housing (62) and deflected toward the joystick return position; A magnetorheological fluid joystick resistance mechanism (56) is provided, which can be controlled to change the magnetorheological fluid resistance that hinders the movement of the joystick relative to the base shell (62). Controller architecture (50), which is connected to the magnetorheological fluid joystick resistance mechanism (56), is configured to: Operator adjustment that allows the vehicle operator to selectively activate the return position of the control lever; and When the operator adjustment of the joystick return position is initiated, a command is issued to the magnetorheological fluid joystick resistance mechanism (56) to maintain the magnetorheological fluid resistance at a predetermined level until the operator adjustment of the joystick return position is terminated.

2. The magnetorheological fluid joystick system (22) for a work vehicle according to claim 1, further comprising a joystick return position locking mechanism (70), the joystick return position locking mechanism (70) being movable between the following states: In the unlocked state, the joystick return position locking mechanism (70) allows adjustment of the joystick return position; and In the locked state, the joystick return position locking mechanism (70) prevents adjustment of the joystick return position.

3. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 2, wherein, The joystick return position locking mechanism (70) is located outside the base housing (62); and The controller architecture (50) is configured to maintain the magnetorheological fluid resistance at substantially the maximum level until operator adjustment of the joystick to the return position is terminated.

4. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 2, wherein, The joystick return position locking mechanism (70) is inside the base shell (62); and The controller architecture (50) is configured to maintain the magnetorheological fluid resistance at a minimum level until operator adjustment of the joystick to the return position is terminated.

5. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 2, wherein, The controller architecture (50) is coupled to the joystick return position locking mechanism (70) and is also configured to: Upon receiving an operator adjustment to return the joystick to the control position, the joystick return position locking mechanism (70) is commanded to move to the unlocked state; as well as When the operator terminates the joystick return position adjustment, the joystick return position locking mechanism (70) returns to the locked state.

6. The magnetorheological fluid control joystick system (22) for a work vehicle according to claim 2, wherein the magnetorheological fluid control joystick system (22) for a work vehicle further comprises: A support structure (192) is adjacent to the base shell (62), and the joystick return position locking mechanism (70) is connected between the support structure (192) and the base shell (62); as well as The connectors (194, 196) engage the base shell (62) to the support structure (192) while allowing the base shell (62) to rotate relative to the support structure (192) along at least one degree of freedom when the joystick return position locking mechanism (70) is in the unlocked state.

7. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 2, wherein, The joystick return position locking mechanism (70) includes: Hydraulic cylinders (204, 206, 274, 276), each having opposing hydraulic chambers; and Shut-off valves (208, 278) are fluidly connected between the opposing hydraulic chambers and operatively connected to the controller architecture (50). The shut-off valves (208, 278) can be controlled to selectively prevent fluid flow between the opposing hydraulic chambers to lock the hydraulic cylinders (204, 206, 274, 276) in a translational position.

8. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 7, wherein, The hydraulic cylinders (204, 206, 274, 276) are mechanically connected between the base housing (62) and the lower part of the control lever (60).

9. The work vehicle magnetorheological fluid control joystick system (22) according to claim 7, the work vehicle magnetorheological fluid control joystick system (22) further includes a support structure (192), the base shell (62) is movably mounted to the support structure (192), and the hydraulic cylinders (204, 206, 274, 276) are mechanically connected between the base shell (62) and the support structure (192).

10. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 7, wherein, The shut-off valves (208, 278) include magnetorheological fluid valves, which are selectively energized by the controller architecture (50) to substantially prevent magnetorheological fluid from flowing through the valves when the joystick return position locking mechanism (70) is in the locked state.

11. The work vehicle magnetorheological fluid joystick system (22) according to claim 1, wherein the work vehicle magnetorheological fluid joystick system (22) further comprises a computer-readable storage device (48) connected to the controller architecture (50). in, The controller architecture (50) is configured to store joystick return position setting data (225) in the computer-readable storage (48) after the joystick return position is adjusted by the operator of the work vehicle. The joystick return position setting data (225) describes the joystick return position of the joystick device (52, 54) adjusted by the operator.

12. The magnetorheological fluid control joystick system (22) for a work vehicle according to claim 11, wherein, The controller architecture (50) is also configured to: At a predetermined position encountered when the control lever is rotated about the rotation axis, a magnetorheological fluid resistance effect is selectively generated, the magnetorheological fluid resistance effect including one of magnetorheological fluid stop (302, 302) and magnetorheological fluid motion stop (319, 320); as well as When the operator adjusts the joystick return position to a position that deviates from the default joystick return position, the predetermined position for generating the magnetorheological fluid resistance effect is adjusted.

13. The magnetorheological fluid control joystick system (22) for a work vehicle according to claim 12, wherein, The magnetorheological fluid drag effect includes magnetorheological fluid motion cessation; and The controller architecture (50) is configured to generate the magnetorheological fluid motion stop (319, 320) at the following locations: at which the first range of motion of the joystick is substantially equal to the second range of motion of the joystick; Wherein, the first range of motion is measured as the joystick is rotated about the axis of rotation in a first direction from the operator-adjusted return position; and The second range of motion is measured when the joystick is rotated about the axis of rotation in a second direction from the return position of the joystick adjusted by the operator, and the second direction is opposite to the first direction.

14. A magnetorheological fluid joystick system (22) for use on a work vehicle, the work vehicle magnetorheological fluid joystick system (22) comprising: The joystick devices (52, 54) include: Base shell (62); and A joystick (60) is rotatable relative to the base housing (62) and deflected toward the joystick return position; A magnetorheological fluid joystick resistance mechanism (56) is provided, which can be controlled to change the magnetorheological fluid resistance that hinders the movement of the joystick relative to the base shell (62). A joystick return position locking mechanism (70) is located outside the base housing (62). The joystick return position locking mechanism (70) is movable between: a locked state preventing adjustment of the joystick return position, and an unlocked state allowing adjustment of the joystick return position; and... Controller architecture (50), which is connected to the magnetorheological fluid joystick resistance mechanism (56) and the joystick return position locking mechanism (70), is configured to: When an operator adjustment to return the joystick to its original position is received, a command is issued to the magnetorheological joystick resistance mechanism (56) to generate maximum magnetorheological resistance that substantially prevents movement of the joystick (60) relative to the base shell (62); and When the operator terminates the return position adjustment of the joystick, a command is issued to the magnetorheological joystick resistance mechanism (56) to remove the maximum magnetorheological resistance.

15. The magnetorheological fluid control joystick system (22) for a work vehicle according to claim 14, wherein, The controller architecture (50) is coupled to the joystick return position locking mechanism (70) and is also configured to: Upon receiving operator input to initiate adjustment of the joystick return position, the joystick return position locking mechanism (70) is commanded to move to the unlocked state; as well as When the operator of the work vehicle completes the adjustment of the return position of the control stick, the control stick return position locking mechanism (70) returns to the locked state.

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