Work vehicle magnetorheological fluid joystick system that reduces unintended joystick movement

Abstract

The present disclosure relates to work vehicle magnetorheological fluid joystick systems that reduce unintended joystick motion. In an embodiment, a work vehicle magnetorheological fluid (MRF) joystick system includes a joystick device, an MRF joystick resistance mechanism, and a controller architecture. The joystick device in turn includes a base housing, a joystick movably mounted to the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The MRF joystick resistance mechanism is controllable to vary a first joystick stiffness that changes resistance to movement of the joystick relative to the base housing in at least one degree of freedom. The controller architecture is configured to: (i) detect whether an unintended joystick motion condition arises during operation of the work vehicle; and (ii) when the unintended joystick motion condition is detected, command the MRF joystick resistance mechanism to increase the first joystick stiffness in a manner that reduces sensitivity of the joystick device to unintended joystick motion.

Description

Technical Field

[0001] This disclosure relates to a magnetorheological fluid (MRF) joystick system for work vehicles, which utilizes an MRF joystick resistance mechanism to selectively increase joystick resistance in a manner that reduces unintended joystick movement. Background Technology

[0002] Joystick devices are commonly used to control various operational aspects of work vehicles employed in construction, agriculture, forestry, and mining. For example, in work vehicles equipped with boom assemblies, the operator can use one or more joysticks to control the movement of the boom assembly, and thus control the movement of tools or implements mounted on the outer end of the boom assembly. Common examples of work vehicles with such joystick-controlled boom assemblies include excavators, logging and stacking machines, timber harvesters, tractor-trailers (which may be equipped with modular front-end loaders and backhoe attachments), tractor-trailer loaders, wheel loaders, and various compact loaders. Similarly, in the case of bulldozers, graders, and other work vehicles equipped with bulldozer blades, the operator can use one or more joysticks to control the movement and positioning of the blade. In the case of graders, bulldozers, and certain loaders such as skid steer loaders, joystick devices are also commonly used to manipulate or otherwise control the directional movement of the work vehicle chassis. Given the widespread use of joystick devices in work vehicles, and considering the relatively challenging dynamic environments in which these vehicles are frequently operated, there is a continuous need for improvements to the design and functionality of work vehicle joystick systems, particularly to the extent that such improvements can enhance the safety and efficiency of work vehicle operation. Summary of the Invention

[0003] A magnetorheological fluid (MRF) joystick system for a work vehicle is disclosed. In one embodiment, the work vehicle MRF joystick system includes a joystick assembly, an MRF joystick resistance mechanism, and a controller architecture. The joystick assembly further includes a base housing, a joystick movably mounted in the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The MRF joystick resistance mechanism can be controlled to change a first joystick stiffness, the first joystick stiffness resisting movement of the joystick relative to at least one degree of freedom of the base housing. The controller architecture, coupled to the joystick position sensor and the MRF joystick resistance mechanism, is configured to: (i) detect whether an unexpected joystick movement condition occurs during operation of the work vehicle; and (ii) when an unexpected joystick movement condition is detected, command the MRF joystick resistance mechanism to increase the first joystick stiffness in a manner that reduces the sensitivity of the joystick assembly to unexpected joystick movement.

[0004] In other embodiments, the MRF joystick system for a work vehicle includes a joystick assembly, an MRF joystick resistance mechanism, and a controller architecture. The joystick assembly includes a base housing, a joystick movably mounted on the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The controller architecture is coupled to the joystick position sensor and the MRF joystick resistance mechanism, which can be controlled to change the joystick stiffness, the stiffness resisting movement of the joystick relative to at least one degree of freedom of the base housing. The controller architecture is configured to: (i) determine, at least in part, based on data provided by the joystick position sensor, whether unintended joystick movement is currently occurring; and (ii) when unintended joystick movement is determined to be occurring, command the MRF joystick resistance mechanism to increase the joystick stiffness in a manner that reduces the unintended joystick movement.

[0005] In other embodiments, the work vehicle MRF joystick system includes a joystick assembly, an MRF joystick resistance mechanism, a controller architecture, and a disturbance force sensor configured to detect disturbance forces applied to the work vehicle. The joystick assembly includes a base housing, a joystick movably mounted in the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The MRF joystick resistance mechanism can be controlled to change the joystick stiffness of the joystick assembly, the stiffness resisting movement of the joystick relative to at least one degree of freedom of the base housing. The controller architecture is coupled to the joystick position sensor, the MRF joystick resistance mechanism, and the disturbance force sensor. The controller architecture is configured to: (i) monitor disturbance forces detected by the disturbance force sensor during work vehicle operation; and (ii) when the disturbance force sensor detects a disturbance force exceeding a predetermined threshold, command the MRF joystick resistance mechanism to increase the joystick stiffness to reduce the likelihood of unexpected joystick movement caused by the detected disturbance force.

[0006] Details of one or more embodiments are set forth in the accompanying drawings and the following description. Other features and advantages will become apparent from the specification, drawings, and claims. Attached Figure Description

[0007] At least one example of this disclosure will be described below with reference to the following figures:

[0008] Figure 1 This is a schematic diagram of an example magnetorheological fluid (MRF) joystick system exemplified according to an example embodiment of the present disclosure, the system being on a work vehicle (here, an excavator) and configured to reduce or impede accidental joystick movement by selectively applying increased joystick stiffness;

[0009] Figure 2 This is an example Figure 1The figure shows a perspective view of the excavator cab, which 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.

[0010] Figure 3 and Figure 4 The diagram is a schematic cross-sectional view of an example MRF joystick system, taken and partially shown along a vertical cross-section passing through the joystick included in the joystick assembly, illustrating one possible configuration of the MRF joystick system;

[0011] Figure 5 This is a process appropriately executed by the controller architecture of the MRF joystick system to selectively increase joystick stiffness in a manner that reduces unintended joystick movement; and

[0012] Figure 6 The diagram shows another example work vehicle in which the implementation of the MRF joystick system can be beneficially integrated, illustrated in a non-exhaustive manner.

[0013] In the various figures, similar reference numerals indicate similar elements. For the sake of simplicity and clarity of illustration, descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the exemplary and non-limiting embodiments of the invention described in the following detailed description. It should be further understood that, unless otherwise stated, features or elements appearing in the figures are not necessarily drawn to scale. Detailed Implementation

[0014] Embodiments of the present disclosure are illustrated in the accompanying drawings of the figures briefly described above. Those skilled in the art will anticipate various modifications to the exemplary embodiments without departing from the scope of the invention as set forth in the appended claims. As appears herein, the term "work vehicle" includes all parts of a work vehicle or work machine. Thus, in an implementation in which a boom assembly terminating at the implement is attached to the chassis of the work vehicle, the term "work vehicle" includes both the chassis and the boom assembly, and also includes the implement or tool mounted at the end of the boom assembly.

[0015] Overview

[0016] As previously indicated, joysticks are often integrated into work vehicles to provide an intuitive, universal operator interface for controlling various work vehicle functions. However, joysticks are prone to unintended movement in the presence of high-intensity disturbances applied to the work vehicle, propagating to the operator's console, and ultimately to one or more joysticks located on the operator's console. Such disturbances can take the form of, for example, continuous high-intensity (high amplitude or frequency) vibrations or, more briefly, high-intensity impacts. In particular, high-intensity vibrations can occur during work vehicle operation for various reasons. High-intensity vibrations can occur when the work vehicle travels on highly uneven surfaces and hardened materials, depending on the work vehicle's suspension characteristics, underframe (wheeled, rubber-tracked, or metal-tracked), and similar factors. High-intensity vibrations also frequently occur during the use of certain tools or implements attached to the work vehicle, such as hydraulic hammers mounted to excavators (or other work vehicles) via boom assemblies. An imbalance in rotating components contained within a given work vehicle can also generate a level of baseline vibration, which can develop and worsen over time. Such baseline vibration can severely interfere with other vibration sources present during work vehicle operation, producing high-intensity vibrations capable of causing unintended movement (e.g., accidental or unintentional movement) of one or more joysticks located within the operator's console of the work vehicle. For example, when an operator gripping a joystick attempts to control a function commanded by the joystick while operating the work vehicle in such a high-vibration environment, the operator may inadvertently apply repetitive vibratory movements to the joystick (hereinafter referred to as "operator-induced oscillation" or "OIO" of the joystick).

[0017] More transient, high-amplitude disturbances can also occur during the operation of a work vehicle due to impact forces applied to certain areas, for example. These impact forces can occur when a part of the work vehicle (such as the bucket, grapples, or other implements attached to the boom assembly) repeatedly strikes a hard surface that impedes movement during the performance of a specific work task. These impact forces can generate shock forces that travel through the structure of the work vehicle or propagate to the operator and one or more joysticks located within the operator's workbench. If severe enough, this propagated disturbance can cause one or more joysticks within the operator's workbench to move unintentionally. Large, transient disturbances can also occur due to sudden changes in the speed, direction, or orientation of the work vehicle, resulting in a difference between the operator's body's inertial vector and the work vehicle's inertial vector. This can cause displacement of the operator's body relative to the joysticks, thus increasing the likelihood that the operator may unintentionally move the joysticks unintentionally.

[0018] In certain situations, unexpected joystick movement can occur during operation of a work vehicle even when the joystick is not currently being gripped or otherwise contacted by the operator. This type of unexpected joystick movement can occur when the disturbance causes the joystick to shift or move from a specific position (where the joystick is expected to remain) such that the joystick moves even when the operator is not in contact with it (or with minimal contact). As a specific example, in the case of a friction-retaining joystick intended to remain at any operator-selected position without operator force, unexpected joystick movement can occur due to vibration or other disturbance forces causing the joystick to gradually move or lift relative to the operator-selected position without operator force. Similarly, in the case of a self-centering joystick device with a stop feature, unexpected joystick movement can occur if the disturbance displaces the joystick relative to the operator-selected stop position without (or with minimal) operator contact.

[0019] At least some of the aforementioned problems can be addressed to a certain extent by giving the joystick mechanism relatively high stiffness; that is, relatively high resistance that impedes rotation or other movement of the joystick relative to its base housing. Similarly, in the case of a self-centering joystick including a stop feature, the joystick mechanism can be designed to apply a large force (“stop holding force”) to hold the joystick in the operator-selected stop position when the operator moves the joystick to a given stop position. However, such a solution is not ideal and may make the joystick difficult to move during normal use, which is undesirable. As another more common solution, by physically counteracting the interfering forces that cause unintended joystick movement: for example, by trying to prepare for impact forces or by loosening the operator’s grip on the joystick when operating in high-vibration environments, the operator may be able to minimize unintended joystick movement. Although simple and straightforward, this solution is impractical and largely ineffective. Requiring the operator of the work vehicle to manually compensate for unintended joystick movement causes psychological and physical fatigue, especially when the operator frequently drives the work vehicle for long periods in harsh operating environments. Furthermore, in practice, it is difficult (if not impossible) for operators to reliably repeat and compensate for unexpected joystick movements caused by disturbance forces. Finally, as another possible solution in the context of electronic joystick devices, control logic could be introduced to reduce joystick sensitivity and / or attempt to identify and ignore unexpected input movements applied to the joystick device. However, such a solution is suboptimal and comes with various drawbacks, including introducing undesirable complexity into the control logic and increasing the risk of ignoring precise, purposeful joystick movements as unintentional or accidental. Additionally, when attempting to physically compensate for unexpected joystick movements in the presence of disturbance forces generated during operation of the work vehicle, this control logic scheme offers little reduction in the physical strain applied to the work vehicle operator.

[0020] Therefore, there is a persistent industrial demand for a work vehicle joystick system capable of mitigating unintended joystick movements caused by disturbances encountered during work vehicle operation. To meet this demand, a unique work vehicle joystick system incorporating a magnetorheological fluid (MRF) control subsystem or device is described below, which reduces unintended joystick movements by strategically and selectively applying increased joystick stiffness. Implementations of the work vehicle MRF joystick system include a processing subsystem or “controller architecture” coupled to an MRF joystick resistance mechanism (i.e., a mechanism or device containing a magnetorheological fluid and capable of altering the rheological properties (viscosity) of the fluid by changing the electromagnetic (EM) field strength in a manner that affects joystick stiffness). During operation of the work vehicle MRF joystick system, the controller architecture continuously monitors conditions for unintended joystick movements; that is, conditions marked by currently detected persistent unintended joystick movements or alternatively, conditions that may undesirably lead to unintended joystick movements in the near future. When such unexpected joystick movement is detected, the controller architecture commands the MRF joystick resistance mechanism to apply a controlled increase in one or more stiffnesses of the joystick to reduce the joystick's sensitivity to unexpected joystick movement.

[0021] Implementations of MRF joystick devices can selectively increase joystick stiffness using reactive, active, or combinations thereof control schemes. As used herein, the term "reactive" control scheme refers to a controlled increase in joystick stiffness in response to an unexpected joystick movement currently detected and in progress by one or more sensors. In contrast, the term "active" control scheme refers to a controlled increase in joystick stiffness in response to a highly predictable, undesirable joystick movement occurring immediately or in the near future. Thus, when an active control scheme is employed in one example, the MRF joystick system can rapidly increase joystick stiffness in response to the detection of a disturbance force at a location remote from the MRF joystick device, causing the resulting disturbance force to propagate to the joystick device. Such disturbance forces can be detected using various disturbance force sensors on the work vehicle; the term "disturbance force sensor" as used throughout this document encompasses any sensor that provides data indicating vibrational forces, impact forces, or sudden changes in inertia, or other such disturbance forces applied to the work vehicle that may be sufficient to cause an unexpected joystick movement. Such interference force sensors may take the form of, for example, microelectromechanical systems (MEMS) gyroscopes, accelerometers, and magnetometers that may be packaged as one or more inertial measurement units (IMUs) integrated into various locations on the work vehicle; for example, such IMUs may be attached to the chassis of the work vehicle, and, if the work vehicle is equipped with a boom assembly, they may be integrated into various locations on the boom assembly.

[0022] When selectively increasing joystick stiffness according to a reactive control scheme, the controller architecture can utilize one or more joystick position sensors integrated into the MRF joystick device to monitor repetitive, unintended joystick movements. Consider, for example, an implementation where the controller architecture selectively increases joystick stiffness to suppress detected OIO displacement of a joystick included in a given joystick device. When joystick movement is sensed, the controller architecture can initially determine whether the currently sensed joystick movement is actually a result of the joystick's OIO displacement. The controller architecture can perform this analysis by considering the magnitude and repetitive nature of the joystick movement; perhaps by comparing the pattern of joystick movement with pre-established OIO displacement patterns stored in memory. In some implementations, the controller architecture can also consider whether any disturbance force sensors on the work vehicle are currently reporting vibrational forces corresponding to the currently detected joystick displacement. When such unintended joystick movement is identified, the controller architecture can command the MRF joystick resistance mechanism to increase the joystick stiffness by a controlled amount to suppress (reduce or eliminate) the OIO joystick movement. The controller architecture can then continuously monitor whether the stiffness increase applied by the MRF results in the desired suppression of the joystick's OIO movement. If the OIO joystick movement is not sufficiently suppressed, the controller architecture can continuously and gradually increase the joystick stiffness in a continuous or stepwise manner until the OIO joystick movement stops completely, until the OIO joystick movement is reduced to an acceptable level (which can be determined by an operator-adjustable tolerance setting), or until the joystick stiffness upper limit threshold is reached.

[0023] When the joystick stiffness is altered according to an active control scheme, the MRF joystick system can selectively increase the joystick stiffness in response to one or more conditions that produce an unwanted, high-probability accidental joystick movement. Such an active stiffness control scheme can be executed within a highly compressed timeframe (e.g., approximately milliseconds) when an impact or shock force is detected, for example, at an area of ​​the work vehicle (e.g., at the end of the boom assembly attached to the work vehicle). In this case, the MRF joystick system responds rapidly to the detection of such an impact force by increasing the MRF joystick stiffness before (or at least substantially simultaneously with) the transmission of the impact force to the operator's workbench of the work vehicle, and subsequently to the operator and joystick within it. Similarly, if a disturbing force sufficient to cause a sudden, violent displacement of the operator's body is detected (e.g., due to a significant change in the speed, direction of travel, or orientation of the work vehicle), the controller architecture can command the MRF joystick resistance mechanism to rapidly increase the joystick stiffness in a manner that avoids joystick movements unintentionally applied to the joystick when the operator sways or otherwise displaces relative to the joystick in question. In other situations, the controller architecture can apply this active stiffness control scheme within a slightly shortened but still recent timeframe (e.g., when the probability of accidental joystick movement becomes undesirably high due to the temporary operating state or conditions of the work vehicle). Examples of such operating states where an increase in joystick stiffness can be triggered to reduce the probability of accidental joystick movement include the work vehicle traveling at a high speed, the work vehicle traveling over terrain that causes vibrations, or attaching a tool or implement (e.g., a hydraulic hammer) to a work vehicle known to generate disturbing forces during use.

[0024] In embodiments where the joystick is movable relative to the base housing in multiple degrees of freedom (DOF), the MRF joystick control system can be implemented to increase joystick stiffness by a single DOF, or alternatively, to increase joystick stiffness independently by multiple DOFs. For example, in an implementation where the joystick is rotatable about two vertical axes, the MRF resistance mechanism can be able to independently increase the joystick stiffness (i.e., the force that prevents the joystick from rotating) about the two axes of rotation of the joystick. Thus, in this case, the controller architecture can command the MRF joystick control system to independently vary the first joystick stiffness and the second joystick stiffness, respectively, to resist rotation of the joystick about the first axis and the second axis, which is best suited to suppress the occurrence of unintended joystick movement (given the directionality of such unintended joystick movement) or best suited to reduce the likelihood of future unintended joystick movement (given the characteristics of detected conditions that drive an increase in joystick stiffness, such as those applied to the work vehicle and propagating toward one or more joystick devices).

[0025] In one implementation, a method of selectively increasing joystick stiffness to reduce unintended joystick movement can be applied consistently across the joystick's range of motion (ROM) with one or more DOFs; for example, for a joystick rotatable about two vertical axes, increased joystick stiffness can be applied to resist consistent rotation of the joystick across its ROM about one or both axes. In other cases, the controller architecture can apply increased joystick stiffness to reduce the likelihood of unintended joystick movement, such that the increased MRF stiffness force resisting joystick movement depends on the joystick position. For example, in the latter approach, the controller architecture can cause the stiffness force applied by the MRF to increase or decrease as the joystick further shifts relative to a neutral, original, or centered position. Similarly, this method can be used to increase the stiffness applied by the MRF to resist movement relative to certain discrete stop positions encountered by the joystick as it moves through its ROM. In this scenario, the controller architecture may, in response to any or all of the aforementioned active triggers (e.g., detecting an impact or shock force propagating toward the operator's workbench of the work vehicle or using a tool associated with an impact force), command the MRF resistance mechanism to temporarily increase the stop holding force, thereby holding the joystick in a given stop position. Similarly, the controller architecture may, in response to detecting regular vibration or jitter (e.g., in a high-vibration environment), command the MRF resistance mechanism to increase the stop holding force, and the controller architecture may gradually increase the stop holding force in a stepwise or continuous manner, proportional to the intensity of the vibration force measured by the disturbance force sensor on the work vehicle.

[0026] In this manner, the implementation of the MRF joystick system produces a selective increase in joystick stiffness applied by the MRF to reduce (if not eliminate) unintended joystick movements that would otherwise occur during operation of the work vehicle. By doing so, the implementation of the MRF joystick system minimizes operator fatigue and enhances the operator experience by reducing the frequency and severity of unintended joystick movements. Simultaneously, this reduction in unintended joystick movements minimizes component wear, improves the efficiency of the work vehicle, and, in other ways, facilitates precise and consistent control of the work vehicle's functions in response to operator-controlled joystick commands. Furthermore, using MRF technology to selectively increase joystick stiffness offers various benefits over other mechanisms capable of providing controlled increases in joystick stiffness (e.g., actuated friction mechanisms). One such benefit is that the magnetorheological fluid responds rapidly to changes in the intensity of the EM field in which it can be immersed. Since the intensity of the EM field can also be changed rapidly, a highly responsive MRF joystick resistance mechanism can be designed to provide a response time of approximately, for example, a few milliseconds, to changes in joystick stiffness. The highly responsive nature of the MRF joystick resistance mechanism allows the joystick stiffness to increase rapidly in response to the detection of disturbance forces such as impact forces, as briefly discussed above and described more fully below. Furthermore, implementations of the MRF joystick resistance mechanism can generate MRF stiffness forces over a continuous range, thereby enabling the MRF joystick device to gradually increase joystick stiffness (in a stepwise or continuous manner) in certain situations; for example, to gradually drive the sensed OIO joystick movement to zero or in response to increased vibration intensity in a high-vibration environment.

[0027] Now, will be combined Figures 1 to 5 This section describes an example implementation of an MRF joystick system for a work vehicle. In the example implementations below, the MRF joystick system is discussed primarily within the context of a specific type of work vehicle, namely an excavator. Furthermore, in the following examples, the MRF joystick system includes two joystick devices, each having a joystick rotatable about two vertical axes and used to control the movement of the excavator's boom assembly and attached implements (e.g., bucket, grab, or hydraulic hammer). Despite the following examples, in other implementations, the MRF joystick system may include more or fewer joysticks, wherein each joystick device is movable at any number of DOFs and along any suitable motion pattern; for example, in alternative implementations, a given joystick device may be rotatable about a single axis, or perhaps movable along a restricted (e.g., H-shaped) track or motion pattern. Moreover, the MRF joystick system described below can be deployed on a wide variety of work vehicles including joystick-controlled functions, as discussed below. Figure 6 Let's discuss other examples.

[0028] Example MRF joystick system that reduces unintended joystick movement

[0029] First refer to Figure 1 An example work vehicle (here, excavator 20) equipped with a work vehicle MRF joystick system 22 is presented. In addition to the MRF joystick system 22, the excavator 20 includes a boom assembly 24 terminating at a tool or implement such as a bucket 26. Various other implements are interchangeable with the bucket 26 and attached to the end of the boom assembly 24; these implements include, for example, other buckets, grapples, and hydraulic hammers. The excavator 20 is primarily composed of 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 work platform. The excavator boom assembly 24 extends from the chassis 28 and includes an internal or proximal boom 34 (hereinafter, "lifting boom 34"), an external or distal boom 36 (hereinafter, "stick 36"), and multiple hydraulic cylinders 38, 40, and 42 as main structural components. The hydraulic cylinders 38, 40, and 42 further include two lifting cylinders 38, a stick cylinder 40, and a bucket cylinder 42. The extension and retraction of the lifting cylinders 38 cause the lifting boom 34 to rotate about a first pivot joint. At the head, the boom 34 engages with the excavator chassis 28, specifically at a position adjacent to the cab 32 (on the right side). The extension and retraction of the stick cylinder 40 causes the stick 36 to rotate about a second pivot joint, at which the stick 36 engages with the boom 34. Finally, the extension and retraction of the bucket cylinder 42 causes the excavator bucket 26 to rotate or "curl" about a third pivot joint, at which the bucket 26 engages with the stick 36.

[0030] Hydraulic cylinders 38, 40, and 42 are included in an electro-hydraulic (EH) actuation system 44, which is powered by... Figure 1The section titled "Actuator for Joystick-Controlled Functions" is enclosed in box 46. The movement of the excavator boom assembly 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, while simultaneously controlling the swinging motion of the boom assembly 24 via rotation of the excavator chassis 28 relative to the tracked undercarriage 30. The depicted EH actuation system 44 also includes various other hydraulic components not illustrated, which may include flow lines (e.g., flexible hoses), check valves or relief valves, pumps, fittings, filters, etc. Additionally, the EH actuation system 44 includes electronic valve actuators adjustable to regulate the flow rate of pressurized hydraulic fluid into and out of the hydraulic cylinders 38, 40, 42, and flow control valves such as spool valves. Therefore, the specific construction or structure of the EH actuation system 44 is largely insignificant to the embodiments of this disclosure, provided that the controller architecture 50 described below can control the movement of the boom assembly 24 via commands transmitted to the selected actuator 46, which performs the joystick control function of the excavator 20.

[0031] like Figure 1 As illustrated schematically in the upper left, the work vehicle MRF joystick system 22 includes one or more MRF joystick devices 52, 54. As used herein, the term "MRF joystick device" refers to an operator input device comprising at least one joystick or control lever, the movement of which is resisted by a variable resistance or "stiffness force" applied using an MRF control resistance mechanism of the type described herein. Although for clarity... Figure 1 The diagram schematically illustrates one such MRF joystick device 52, 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 joystick devices 52 and 54 are described. The following further discusses how two such control joystick 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 illustrated schematically, is provided to establish a general framework for a better understanding of the embodiments of this disclosure.

[0032] like Figure 1As schematically illustrated, the MRF joystick device 52 includes a joystick 60 mounted on a lower support structure or base housing 62. The joystick 60 is movable relative to the base housing 62 at least at a distance of at least one DOF and is rotatable relative to the base housing 62 about one or more axes. In the depicted embodiment, and as indicated by arrow 64, the joystick 60 of the MRF joystick device 52 is rotatable relative to the base housing 62 about two vertical axes, as will be described below. The MRF joystick device 52 includes one or more joystick position sensors 66 for monitoring the current position and movement of the joystick 60 relative to the base housing 62. The MRF joystick device 52 may also include various other components 68, including buttons, dials, switches, or other manual input features that may be located on the joystick 60 itself, on the base housing 62, or combinations thereof. Spring elements (gas or mechanical), magnets, or fluid dampers may be incorporated into the joystick assembly 52 to provide the desired rate of return to the joystick's original position, while fine-tuning the desired feel of the joystick 60 perceived by the operator when interacting with the MRF joystick assembly 52. ​​In more complex implementations, various other components (e.g., potentially including one or more personal force feedback (AFF) motors) may also be incorporated into the MRF joystick assembly 52. ​​In other implementations, such components may be omitted from the MRF joystick assembly 52.

[0033] 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 is controllable to adjust the MRF resistance, and thus the joystick stiffness, thereby resisting movement of the joystick relative to the base housing 62 at at least one DOF. 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 preventing rotation of the joystick 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 increase the joystick stiffness as appropriate by increasing the strength of the EM field (in which the magnetorheological fluid contained in the mechanism 56 is at least partially immersed) to reduce unintended joystick movement (actual or anticipated). The following, in conjunction with... Figure 3 and Figure 4 A common example of a way to implement the MRF joystick resistance mechanism 56 is described.

[0034] In determining whether to guarantee that the increase in joystick stiffness applied by the MRF reduces unintended joystick movements (whether actual or anticipated), the controller architecture 50 may consider data input from any number and type of data sources. Such data sources may include disturbance force sensors 70 on the excavator 20. Disturbance force sensors 70 may include any number and type of sensors for measuring vibrational forces, impact forces, or sudden changes in inertia of the excavator 20, or other such disturbance forces applied to the work vehicle. Often, disturbance force sensors 70 will include multiple inertial sensors 72 (such as MEMS gyroscopes, accelerometers, and possibly magnetometers packaged as IMUs) attached to various locations on the excavator 20; for example, the IMUs may be attached to one or more locations (different joysticks) on the excavator chassis 28 and the excavator boom assembly 24.

[0035] In one embodiment, the interference force sensor 70 also includes multiple vehicle motion data sources 74. The vehicle motion data sources 74 may include any sensor or data source that provides information relating to changes in the position, speed, direction of travel, or orientation of the excavator 20. Again, such changes may be detected and measured using MEMS gyroscopes, accelerometers, and possibly IMUs incorporating magnetometers. In one embodiment, inclinometers or similar sensors may be used to monitor the orientation of some parts of the excavator chassis 28 or boom assembly 24 relative to gravity. The vehicle motion data source 74 may also include a Global Navigation Satellite System (GNSS) module, such as a Global Positioning System (GPS) module, for monitoring the excavator's position and motion status. In one embodiment, the vehicle motion data source 74 may also include sensors (from which the rotation rate of the undercarriage tracks can be calculated), an electronic compass for monitoring the direction of travel, and other such sensors. In some cases, GPS or other GNSS data, along with map data stored in memory 48, may be used to determine whether the excavator 20 (or other work vehicle) is operating in an environment where it is likely to encounter significant interference forces. Finally, the vehicle motion data source 74 may include various sensors for monitoring the movement and position of the boom assembly 24 and the bucket 26, including MEMS devices integrated into the boom assembly 24 (as described above), sensors for measuring angular displacement at the pin joints of the boom assembly, sensors for measuring the strokes of the hydraulic cylinders 38, 40, 42, etc.

[0036] In addition to the components described previously, embodiments of the MRF joystick system 22 may also include any number of other non-joystick components 76. Such additional non-joystick components 76 may include an operator interface 78 (distinct from the MRF joystick 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 input devices external to the MRF joystick 52. Such input devices included in the operator input 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 capable of visually presenting visual alarms and other information. The display device 80 may also generate a GUI for receiving operator input, or may include other input elements (e.g., buttons or switches) for receiving operator input, which may be associated with the controller architecture 50 when the following processes are performed. In some cases, the display device 80 may also have touch input capability.

[0037] Finally, the MRF joystick system 22 may include various other non-joystick sensors 82 that provide data input to the controller architecture 50 for performing the following processes. For example, the non-joystick sensors 82 may include sensors that automatically determine the type of implement currently attached to the excavator 20 (or other work vehicle), and in at least some implementations, the controller architecture 50 takes this information into account when determining whether to increase joystick stiffness to reduce unintended joystick movement; for example, such sensors 82 may determine the specific type of implement currently attached to the excavator 20 by visually analyzing a camera feed capturing the implement, sensing a tag (e.g., an RFID tag), reading other identification information present on the implement, or utilizing any other technology. In other cases, the operator may simply input information to select the type of implement currently attached to the boom assembly 24 by interacting, for example, with a GUI generated on the display device 80. In other cases, such other non-joystick sensors 82 may include sensors or cameras capable of determining whether the operator is gripping or otherwise contacting the joystick 60. In other embodiments, such a sensor may not be included in the MRF joystick system 22.

[0038] As in Figure 1As further illustrated schematically, 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 various 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 example MRF joystick system 22). Therefore, controller architecture 50 may include or be associated with any practical 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 and other controllers located within the operator's workbench surrounded by cab 32, wherein the local controller communicates with other controllers on excavator 20 as needed. Controller architecture 50 may also include or cooperate with any number of firmware and software programs or computer-readable instructions designed to perform or cooperate with the various processing tasks, calculations, and control functions described herein. Such computer-readable instructions can be stored in non-volatile sectors of memory 48 associated with (accessible to) controller architecture 50. Although in Figure 1 While generally exemplified as a single block, memory 48 may contain 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. In embodiments, memory 48 may be integrated into the controller architecture 50 as, for example, a system-in-a-chip, a system-on-a-chip, or another type of microelectronic package or module.

[0039] A more detailed discussion of the joystick configuration or layout of the excavator 20, the number of joystick devices included in the MRF joystick system 22, and the structural aspects and functions of such joysticks will vary depending on the implementation. As previously mentioned, although in Figure 1 Only a single joystick 52 is shown schematically, but the MRF joystick system 22 will typically have two joysticks 52, 54 supporting control of the excavator boom assembly. This is further illustrated. Figure 2 A perspective view from inside the excavator cab 32 is provided, depicting two MRF joystick devices 52, 54 suitably included in an embodiment of the MRF joystick system 22. It can be seen that 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 with the above combination... Figure 1The reference numerals introduced in the drawings indicate that each joystick device 52, 54 includes a joystick 60 mounted on a lower support structure or base housing 62 for rotation about two vertical axes relative to the base housing 62. Each joystick device 52, 54 also includes a flexible cover or protective cover 88 engaged between the lower portion of the joystick 60 and its corresponding base housing 62. Additional joystick inputs in the form of thumb-accessible buttons are also provided on each joystick 60, and it is possible to provide additional joystick inputs as other, unillustrated, manual inputs (e.g., buttons, dials, and / or switches) provided on the base housing 62. Figure 2 Other notable features of the excavator 20 shown include the previously mentioned display device 80 and pedal / control lever mechanisms 90, 92 for controlling the corresponding movement of the left and right tracks of the tracked undercarriage 30.

[0040] Different control schemes can be used to convert the movement of the joystick 60 included in the joystick devices 52 and 54 into corresponding movement of the excavator boom assembly 24. In many cases, the excavator 20 will support boom assembly control in any of the following modes: "backhoe control" and "SAE control" and "International Organization for Standardization" or "ISO" control (and often allows switching between them). In reverse shovel control mode, moving the left joystick 60 to the operator's left (arrow 94) causes the excavator boom assembly 24 to swing 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 swing to the right (corresponding to the chassis 28 rotating clockwise relative to the tracked underframe 30), moving the left joystick 60 forward (arrow 98) causes the boom 34 to lower, and moving the left joystick 60 backward or rearward (arrow 100) causes the boom 34 to rise. Additionally, in the reverse shovel control mode, moving the right joystick 60 to the left (arrow 102) causes the bucket 26 to curl inward, moving it to the right (arrow 104) causes the bucket to release or "open," moving it forward (arrow 106) causes the stick 26 to rotate outward, and moving it backward (arrow 108) causes the stick 26 to rotate inward. In contrast, in the ISO control mode, the joystick movements for the swing command and bucket curl command remain unchanged, while the joystick mappings for the boom and stick are reversed. Therefore, in ISO control mode, forward and backward movement of the left joystick 60 controls the rotation of the stick in the previously described manner, while forward and backward movement of the right joystick 60 controls the movement (raising and lowering) of the boom 34 in the aforementioned manner.

[0041] Turn now Figure 3 and Figure 4Example configurations of the MRF joystick device 52 and the MRF joystick resistance mechanism 56 are illustrated by two simplified cross-sectional schematic diagrams. While these figures show a single MRF joystick device (i.e., MRF joystick device 52), the following description is equally applicable to other MRF joystick devices 54 included in the example MRF joystick system 22. The following description is provided only by way of non-limiting example; note that numerous different joystick designs are possible that incorporate or functionally cooperate with the MRF joystick resistance mechanism. The specific composition of the magnetorheological fluid is also largely inconsequential to embodiments of this disclosure, provided that the rheological properties (viscosity) of the magnetorheological fluid undergo meaningful variations in combination with controlled variations in the EM field strength, as described below. However, for completeness, it is noted that a magnetorheological fluid composition very suitable for use in embodiments of this disclosure comprises magnetically permeable (e.g., iron carbonyl) particles dispersed in a carrier fluid, which is primarily composed of oil or alcohol (e.g., ethylene glycol) by weight. 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, may also be included in the magnetorheological fluid to fine-tune its properties.

[0042] Now refer to Figure 3 and Figure 4 The example joystick configuration shown herein, and again appropriately using previously introduced reference numerals, describes an MRF joystick device 52 comprising a joystick 60 having at least two distinct portions or structural regions: an upper handle portion 110 (shown only in simplified lower portion in the figures) and a lower, generally spherical base portion 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 extend substantially parallel to each other to form the upper portion of the base housing 62. Vertically aligned central openings are provided through the housing walls 114, 116, wherein the corresponding diameter of the 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 further selected such that the body of the generally spherical base 112 is 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 the joystick 60 from translating along the X, Y, and Z axes of the coordinate system 118. In other embodiments, various other mechanical arrangements (such as a gimbal arrangement) can be used to mount the joystick to the base housing, while allowing the joystick to rotate about two vertical axes. In a less complex embodiment, a pivot or pin joint can be provided to allow the joystick 60 to rotate about a single axis relative to the base housing 62.

[0043] The joystick 60 of the MRF joystick device 52 also includes a pin or lower joystick extension 120 extending from the generally spherical base 112 in the direction opposite 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 spring 124; it should be noted that this arrangement is simplified for illustrative purposes, and in actual implementations of the MRF joystick device 52, a more complex spring return arrangement (or other joystick biasing mechanism, if present) will typically be used. When the joystick 60 is removed from the base housing 62... Figure 3 When the neutral or original position is shifted as shown in the figure, the return spring 124, as shown in the figure, Figure 4 The deflection shown in the figure causes the joystick 60 to return to its original position. Figure 3 Therefore, as an example, when rotating to... Figure 4 After the position shown, if the operator of the work vehicle subsequently releases the control lever handle 110, the control lever 60 will return to its original position under the action of the return spring 124. Figure 3 The neutral or original position is shown in the diagram. In other embodiments, the MRF joystick device 52 may not be self-centering; instead, it may take the form of a friction-holding joystick that remains in a specific position without the operator applying force to remove the joystick from that position.

[0044] Example MRF joystick resistance mechanism 56 includes respectively in Figure 3 and Figure 4 The first MRF cylinder 126 and the second MRF cylinder 128 are shown in the figure. The first MRF cylinder 126 ( Figure 3 The mechanical engagement is between the static attachment point or basic structural feature 130 shown in the portion of the lower control lever extension 120 and the base housing 62. Similarly, the second MRF cylinder 128 ( Figure 4 The MRF cylinder 128 is mechanically engaged between the lower lever extension 120 and the static attachment point 132 of the base housing 62, wherein 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 It 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 4The lever 60 can be controlled to selectively resist rotation about the Y-axis of coordinate diagram 118. Additionally, 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 utilized, including more or fewer MRF cylinders; for example, in implementations where selective resistance to rotation of the lever 60 about only the X-axis or only the Y-axis is desired, or in implementations where the lever 60 rotates only 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 other implementations, any number of additional components can be included in or associated with MRF cylinders 126 and 128. Such additional components may include sensors for monitoring the stroke of cylinders 126 and 128 (if desired) to, for example, track the lever position, instead of the lever sensors 182 and 184 described below.

[0045] 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 into which the head 138 of one of the pistons 138 and 140 is mounted to translate along the longitudinal axis or centerline of the cylinder body 134. The head 138 of each piston is fitted with one or more dynamic seals (e.g., O-rings) around its outer periphery to sealably engage the inner surface of the cylinder body 134, thereby dividing the bore 136 into two opposing variable-volume hydraulic chambers. Pistons 138 and 140 also each include an elongated piston rod 140 extending from the piston head 138 toward a lower lever extension 120 of the lever 60. The piston rod 140 extends through an end cap 142 (which also engages any number of seals) attached to the open end of the cylinder body 134 to attach to the lower lever extension 120 at lever attachment point 144. In the illustrated 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 corresponding static attachment points 130, 132 via ball joints 145. Finally, hydraulic ports 146, 148 are also provided in the opposite ends of each MRF cylinder 126, 128 to allow magnetorheological fluid to flow in and out in conjunction with the translational movement or stroke of the pistons 138, 140 along the respective longitudinal axes of the MRF cylinders 126, 128.

[0046] MRF cylinders 126 and 128 are fluidly interconnected with their corresponding MRF valves 150 and 152 via flow line connections 178 and 180, respectively. Similar to MRF cylinders 126 and 128, MRF valves 150 and 152 are represented as identical in the illustrated example, but may differ in other implementations. Although referred to as "valves" in common terminology (especially considering that the function of MRF valves 150 and 152 is to control the flow of magnetorheological fluid), it will be observed that in this example, MRF valves 150 and 152 lack valve elements and other moving mechanical parts. As a beneficial inference, MRF valves 150 and 152 provide fail-safe operation because, in the unlikely event of an MRF valve failure, magnetorheological fluid is still permitted to pass through MRF valves 150 and 152 with relatively minimal resistance. Therefore, if any 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 that limits or inhibits joystick movement will be impaired; however, the joystick 60 will remain rotatable about the X and Y axes in a manner similar to conventional non-MRF joystick systems, and the MRF joystick device 52 will typically remain capable of controlling the excavator boom assembly 24.

[0047] In the depicted embodiment, MRF valves 150 and 152 each include a valve housing 154, which contains end caps 156 attached to opposite ends of an elongated cylinder 158. A generally annular or tubular flow channel 160 extends around the cylinder 158 between two fluid ports 162 and 164, which are configured to pass through opposite end caps 156. The annular flow channel 160 is surrounded by a plurality of EM sensor coils 166 (hereinafter referred to as "EM coils 166") (extending through the EM coils 166), which are wound around a paramagnetic retainer 168 and clamp a plurality of axially or longitudinally spaced ferrite rings 170. A tubular shroud 172 surrounds the assembly, and multiple leads are provided through the shroud 172 to facilitate electrical interconnection with the housed EM coils 166. Two such leads, along with corresponding electrical connections to a power supply and control source 177, are connected to the EM coils 166. Figure 3 and Figure 4The diagram is schematically represented by lines 174 and 176. As indicated by arrow 179, the controller architecture 50 is operatively coupled to a power supply and control source 177, enabling the controller architecture 50 to control source 177 to change the current supplied to the EM coil 166 or the voltage applied across the EM coil 166 during operation of the MRF joystick system 22. Therefore, this 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 166), 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.

[0048] The fluid ports 162 and 164 of MRF valves 150 and 152 are respectively fluidly connected to ports 146 and 148 of the corresponding MRF cylinders 126 and 128 via the aforementioned conduits 178 and 180. Conduits 178 and 180 can be, for example, flexible tubing sections with sufficient slack to accommodate any movement of the MRF cylinders 126 and 128 resulting from the rotation of the lever 60. In this regard, consider... Figure 4 Example scenario. In this example, the operator moves 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, the MRF cylinder 128 rotates about the ball joint 145, tilting slightly upwards as shown. Furthermore, along with this operator-controlled joystick movement, the pistons 138 and 140 contained in the MRF cylinder 128 retract, causing the piston head 138 to... Figure 4 The pistons 138 and 140 move to the left (towards attachment point 132). This translational movement forces magnetorheological fluid through the MRF valve 152 to accommodate the decrease in volume of the chamber to the left of the piston head 138 and the corresponding increase in volume of the chamber to the right of the piston head 138. Therefore, at any moment during this operator-controlled joystick rotation, the controller architecture 50 can change the current supplied to the EM coil 166 or the voltage across the EM coil 166 to alter the force resisting the flow of magnetorheological fluid through the MRF valve 152, thereby achieving the desired MRF resistance to further movement of the pistons 138 and 140.

[0049] Given the responsiveness of the MRF joystick resistance mechanism 56, the controller architecture 50 can control the resistance mechanism 56 to apply such MRF resistance only briefly, thereby increasing the strength of the MRF resistance in a predetermined manner (e.g., gradually or stepwise) as the piston displacement increases, or providing various other resistance effects (e.g., tactile stops or pulsating effects), as discussed in detail below. The controller architecture 50 can also control the MRF joystick resistance mechanism 56 to selectively provide such resistance effects in conjunction with the rotation of the pistons 138, 140 included in the MRF valves 150 and the joystick 60 about the X-axis of coordinate diagram 118. Furthermore, the MRF joystick resistance mechanism 56 can be able to independently change the EM field strength generated by the EM coil 166 within the MRF valves 150, 152, so that the MRF resistance can be independently controlled to suppress rotation of the joystick about the X and Y axes of coordinate diagram 118.

[0050] The MRF joystick device 52 may also include one or more joystick position sensors 182, 184 (e.g., optical or non-optical sensors or transducers) to monitor the position or movement of the joystick 60 relative to the base housing 62. Specifically, in the illustrated example, 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 for monitoring the rotation of 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 other embodiments, the MRF joystick device 52 may include various other components not illustrated, including the MRF joystick resistance mechanism 56. Such components may, as appropriate, include operator input devices and corresponding electrical connections disposed on the joystick 60 or the base housing 62, an AFF motor, and pressure and / or flow sensors included in the flow loop of the MRF joystick resistance mechanism 56, to best suit a particular application or use.

[0051] As previously emphasized, the above-described embodiment of the MRF joystick device 52 is provided only as a non-limiting example. In alternative implementations, the construction of the joystick 60 may differ in various aspects. Relative to Figure 3 and Figure 4The example shown may differ from other embodiments of the MRF joystick resistance mechanism 56, provided that the MRF joystick resistance mechanism 56 is controllable by the controller architecture 50 to selectively apply resistance (by altering the rheological properties of the magnetorheological fluid) to suppress joystick movement relative to the base at at least one DOF. In other implementations, an EM sensor coil similar to or the same as the EM coil 166 may be directly integrated into the MRF cylinders 126, 128 to provide the desired controllable MRF resistance effect. In this implementation, flow of magnetorheological fluid is permitted between the variable-volume chambers within a given MRF cylinder 126, 128 by providing one or more orifices through which the piston head 138 passes, by providing an annular or slightly annular gap around the inner surface of the piston head 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 joystick resistance mechanism. In contrast, the use of MRF valves 150, 152 ( Figure 3 and Figure 4 One or more external MRF valves can facilitate cost-effective manufacturing and enable the use of commercially available modular components in at least some cases.

[0052] In other implementations, the MRF joystick device is designed to allow the magnetorheological fluid to encapsulate and act directly on the lower portion of the joystick 60 itself (e.g., in the case of the joystick 60, the peripheral base 112), such that the EM coil is positioned around and surrounds the body of the magnetorheological fluid around the lower portion of the joystick. In this embodiment, the spherical base 112 may be provided with ribs, grooves, or similar structural 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 the restricted flow channel provided around the spherical base 112, or possibly due to a sharp turn of the magnetorheological fluid in conjunction with joystick rotation. Various other designs are also possible in other embodiments of the MRF joystick system 22.

[0053] Regardless of the specific design of the MRF joystick resistance mechanism 56, using MRF technology to selectively generate joystick stiffness or variable MRF resistance that suppresses (resists or prevents) unintended joystick movement offers several advantages. A primary advantage is the high responsiveness of the MRF joystick resistance mechanism 56 (and generally, MRF joystick resistance mechanisms) and the desired changes in EM field strength, magnetorheological properties of the fluid, and the joystick stiffness upon which the MRF is ultimately applied, to suppress joystick movement over a highly shortened time period (e.g., approximately 1 millisecond in some cases). Correspondingly, the MRF joystick resistance mechanism 56 allows the MRF resistance to be eliminated (or at least significantly reduced) at an equal rate by rapidly decreasing the current flowing through the EM coil and allowing the rheological properties (e.g., fluid viscosity) of the magnetorheological fluid to return to their normal, unstimulated state. The controller architecture 50 can also control the MRF joystick resistance mechanism 56 to generate, within certain limits, a continuous series of MRF resistance intensities by utilizing corresponding changes in the strength 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- or oil-based carrier fluid, as previously described. Finally, as another advantage, the aforementioned 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 navigating around a first axis (e.g., Figure 3 and Figure 4 The joystick rotates about the X-axis of coordinate diagram 118, while also selectively generating a second resistance or joystick stiffness independently 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, so that the first resistance and the second resistance have different magnitudes as desired.

[0054] In the next round Figure 5 Before the discussion, an example process 190 is presented, which is appropriately executed by the controller architecture 50 of the work vehicle's MRF joystick system 22 to reduce unintended joystick movement by strategically applying an increase in joystick stiffness via the MRF. Process 190 (hereinafter referred to as "Unintended Joystick Movement Prohibition Process 190") comprises several process steps 192, 194, 196, 198, 200, 202, 204, and 206, each of which is described below in sequence. Depending on the specific manner in which the Unintended Joystick Movement Prohibition Process 190 is implemented, Figure 5 The steps illustrated in the examples may require a single procedure or multiple sub-procedures. Furthermore, only non-restricted examples are provided. Figure 5The steps illustrated in the example and described below. In an alternative embodiment of the unexpected joystick movement prohibition process 190, additional process steps may be performed, certain steps may be omitted, and / or the illustrated process steps may be performed in an alternative order.

[0055] exist Figure 5 The example illustrates two control scheme paths: an active control scheme path (hereinafter referred to as "active paths 194, 198, 202") and a reactive control scheme path (hereinafter referred to as "reactive paths 196, 200, 204"). In an implementation, the controller architecture 50 of the MRF joystick system 22 may execute one or both of these control scheme paths during an unexpected joystick movement prohibition process 190 performed according to computer-readable instructions stored in memory 48. Furthermore, as indicated in boxes 210, 212, 214, the corresponding steps included in active paths 194, 198, 202 and in reactive paths 196, 200, 204 may be grouped into general steps or "step boxes" performed during the unexpected joystick movement prohibition process 190. For example, as Figure 5 As indicated in step block 210, steps 194 and 196 can be broadly described as steps of collecting relevant data or information (i.e., data considered by the controller architecture 50 during the execution of the remainder of the unintended joystick movement prohibition process 190). As indicated in step block 212, steps 198 and 200 can be broadly described as steps or queries to evaluate whether the controller architecture 50 has currently detected an unintended joystick movement condition based on the data collected in step block 210. The answer to this query presented in step block 212 determines whether the controller architecture 50 returns to step block 210 and collects (real-time) data again or alternatively proceeds to the final step block 212. Finally, as Figure 5 As indicated in step block 214, steps 202 and 204 can be broadly described as: determining an appropriate increase in joystick stiffness applied by the MRF under a given set of conditions, wherein such increase in stiffness may involve applying two different increases in stiffness to the joystick device when the joystick of the device is rotatable about a vertical axis or otherwise movable in multiple DOFs. The determined increase in joystick stiffness is then achieved by a corresponding command transmitted from the controller architecture 50 to the MRF joystick resistance mechanism 56 to achieve a desired change in the viscosity of the magnetorheological fluid, as described below and throughout this document.

[0056] In response to the occurrence of a predetermined triggering event, the unexpected joystick movement prohibition process 190 begins in step 192. Such a triggering event could be, for example, the activation of a work vehicle on which an MRF joystick system is deployed (e.g., Figure 1The excavator 20 shown in the diagram may receive an operational input that explicitly initiates the unexpected joystick movement prohibition process 190; for example, an operator input that selects an increased joystick stiffness mode from an operator customization menu generated on the display device 80. In other cases, the unexpected joystick movement prohibition process 190 may be initiated when the controller architecture 50 detects one or more conditions associated with an increased likelihood of disruptive forces during an upcoming operation of the excavator 20 (or other work vehicle discussed). A non-exhaustive list of such conditions includes: a specific implement (e.g., a hydraulic hammer) attached to the end of the boom assembly 24, determined based on operator input or data received from any implement automatic detection sensor (if present); the work vehicle traveling at a higher speed (more relevant in the context of work vehicles with a higher speed range, such as sprayers, loaders, and graders); or the work vehicle being located in a work area characterized by terrain or surface types that are likely to exacerbate vibrations during the work vehicle's travel (or historically tend to generate disruptive forces).

[0057] After initiating the unexpected joystick movement prohibition process 190, the controller architecture 50 may follow any or both of the active paths 194, 198, 200 and reactive paths 196, 200, 202, as previously mentioned. First, regarding active paths 194, 198, 200, the controller architecture 50 collects relevant data inputs that are subsequently weighted to determine whether a disturbance force sufficient to cause unexpected joystick movement is likely to occur in the near future (step 194). Such data inputs may include information related to the occurrence and characteristics (e.g., magnitude and directionality) of a disturbance force sensed and applied to the excavator 20 (or other work vehicle) at a location remote from the MRF joystick devices 52, 54. Such disturbance forces may include the impact force measured by the inertial sensor 72 when, for example, the excavator bucket 26 strikes a hard, motion-resistant surface such as a wall of a freestanding structure or hardened terrain during the performance of a specific work task. In other cases, during step 194, data on any abrupt changes in inertia reported by vehicle motion data source 74 that indicate the excavator 20, including changes in vehicle speed (e.g., due to rapid acceleration or deceleration), direction of travel (e.g., due to sharp turns), or orientation (e.g., due to significant changes in the topology of the ground or material traversed by the work vehicle), may be collected. Similarly, abrupt changes in speed and direction of travel may be more relevant when the MRF joystick system is deployed on a work vehicle capable of high-speed travel.

[0058] In an implementation, step 194 may also consider data indicating conditions associated with an increased likelihood of unintended joystick movement. Such data may include information identifying the type of implement or tool currently attached to (or actively used by) the work vehicle, a type that may warrant increased joystick stiffness if it tends to generate disruptive forces during use. For example, in the case of excavator 20, data indicating whether a hydraulic hammer is attached to boom assembly 24 may be collected during step 194, whether using an automatic detection method (if a suitable sensor 82 is integrated into excavator 20) or by receiving operator input specifying the currently attached implement type. Additionally or alternatively, during step 194, controller architecture 50 may collect data indicating whether the work vehicle has entered a particular working environment or is operating in a manner associated with an increased likelihood of disruptive forces (e.g., at a higher speed). Such data may be reported to controller architecture 50 by vehicle motion data source 74 in the manner previously described. Various other relevant data inputs may also be collected during step 194. For example, in cases where the operator provides an input indicating that a disturbance may occur in the near future, or in cases where the operator is permitted to activate the joystick stiffening mode and does so, the controller architecture 50 may collect such data inputs considered during step 198 of the active path 194, 198, 201 of the unintended joystick movement prohibition process 190, as described below.

[0059] Next, in step 198 of the unexpected joystick movement prohibition process 190, the controller architecture 50 determines, based on data collected during step 194, whether there is a high probability of undesirable unexpected joystick movement. For example, when an impact or shock force is detected during step 194, the controller architecture 50 may determine whether the magnitude of such impact force exceeds a predetermined threshold, which may specify a tolerance threshold (essentially a high-pass filter) that allows the occurrence of low-level vibrations that could potentially cause operationally meaningful unexpected joystick movement. Furthermore, in some embodiments, the controller architecture 50 may also consider vector data indicating the location of the principal direction along with the propagating impact force and / or the detected impact force to estimate dissipation before propagation to the MRF joystick devices 52, 54. Similarly, in the case of changes in inertia caused by sudden acceleration, deceleration, turning, or change of direction of the work vehicle, the controller architecture 50 may consider the magnitude of such changes in inertia (and possible vector data) to determine whether such forces present a high risk of undesirable unexpected joystick movement. If, based on such data input, it is determined that the probability of unintended joystick movement has objectively increased, then controller architecture 50 proceeds to step 202 of the unintended joystick movement prohibition process 190. Otherwise, controller architecture 50 returns to step 194 of the active paths 194, 198, 202 (or step 196 of the reactive paths 196, 200, 204 if reactive paths 196, 200, 204 are implemented), and continues to monitor real-time sensor inputs and other data regarding conditions for unintended joystick movement. In some cases, and as previously indicated, the operator may be permitted to activate a joystick stiffening mode through, for example, interaction with a GUI generated on display device 80. In this case, when such a joystick stiffening mode is available and activated by the operator of the work vehicle, controller architecture 50 may automatically proceed to step 202 of the active control paths 194, 198, 202.

[0060] In step 202, given the characteristics of the unexpected joystick movement condition detected in step 198, controller architecture 50 determines or establishes a joystick stiffness increase suitable for minimizing the possibility of unexpected joystick movement. Controller architecture 50 then commands MRF drag mechanism 56 to apply the determined stiffness increase. In some embodiments, controller architecture 50 may command MRF drag mechanism 56 to increase joystick stiffness by an amount substantially proportional to the magnitude of the disturbance force detected during step 194. In this case, controller architecture 50 may command MRF joystick drag mechanism 56 to provide a lower stiffness increase when the detected disturbance force is small, provided that the magnitude of the disturbance force rises above the aforementioned predetermined threshold or high-pass filter. In contrast, when the detected disturbance force has a larger magnitude or higher amplitude, controller architecture 50 may command MRF joystick drag mechanism 56 to provide a greater stiffness increase. In either case, controller architecture 50 functions usefully in a rapid manner to command MRF joystick drag mechanism 56 to increase joystick stiffness before or substantially simultaneously with the propagation of the impact force to joystick devices 52, 54. In doing so, the MRF joystick system 22 effectively prepares the joystick devices 52, 54 to resist unexpected joystick movements just before (or substantially simultaneously with) the transmission of impact or disturbance forces to the operator's workbench, the operator, and the joystick devices 52, 54.

[0061] In an implementation, the controller architecture 50 can also take into account the directionality of any disruptive forces when determining one or more increases in joystick stiffness applied by the appropriate MRF during step 204 of the unintended joystick movement prohibition process 190. For example, if the disruptive force propagates substantially in the fore-and-aft direction relative to the chassis 28 of the work vehicle (e.g., this might be the case when the bucket 26 is repeatedly slammed down onto the ground using the boom assembly 24), the controller architecture 50 can command the MRF resistance mechanism 56 to provide a larger increase in stiffness against rotation of the joystick 60 about a first axis of rotation (corresponding to...). Figure 2 Arrows 98, 100, 106, and 108 in the diagram provide resistance to the joystick 60 rotating around the second axis of rotation (corresponding to...). Figure 2The rotational stiffness of the joystick (arrows 94, 96, 102, 104) is increased slightly (if any stiffness is increased). In other cases, controller architecture 50 may not provide this independent adjustment of joystick stiffness about different axes of rotation. Additionally, as mentioned above, controller architecture 50 may determine an appropriate increase in joystick stiffness based in part on the joystick position reported by position sensor 66; for example, in the case of a self-centering joystick with a stop feature, controller architecture 50 may increase joystick stiffness to effectively increase the stop holding force and reduce the likelihood of the joystick disengaging from the stop position while it is currently residing in such a stop position. After step 202, controller architecture 50 proceeds to step 206 and determines whether to perform an unexpected joystick movement prohibition process 190, as described below.

[0062] Turning now to the description of the reactive paths 196, 200, 204 for the unexpected joystick movement prohibition process 190, which, in embodiments, may also be executed in conjunction with or without the aforementioned active paths 194, 198, 202. When executed, reactive paths 196, 200, 204 begin at step 196, during which the controller architecture 50 collects data input indicating any currently occurring joystick movement. Such data includes joystick movement data measured by the joystick position sensor 66 integrated into the MRF joystick devices 52, 54. Additionally, in some cases, data measuring the vibrational forces currently applied to the excavator 20 reported by the inertial sensor 72 may be considered during step 196. Any data indicating whether the operator is currently gripping one or both of the joysticks 60 included in the MRF joysticks 52, 54 can also be such; for example, as indicated by visual analysis from capacitive touch sensors integrated into the MRF joysticks 52, 54 or from one or more cameras located in the cab of the work vehicle and having a field of view of the joysticks 52, 54.

[0063] In step 200, controller architecture 50 evaluates the data collected during step 196 to determine whether the joystick movement sensed by joystick position sensor 66 was intentionally caused by the operator of excavator 20. For example, in one implementation, controller architecture 50 may identify whether the joystick movement sensed by joystick position sensor 66 is actually an OIO of one or both of the joysticks 60 included in the MRF joystick devices 52, 54 and therefore unintentionally caused by the operator of the work vehicle. The controller architecture can provide this determination by considering the regularity, direction, and magnitude of the detected joystick movement (e.g., by comparing the pattern of joystick movement with representative OIO displacement patterns or waveforms stored in memory 48). Controller architecture 50 may also evaluate any data indicating the magnitude of vibration currently transmitted to excavator chassis 28 to determine whether an OIO of the joystick 60 is currently occurring. As a supplement to or alternative to OIO joystick movement, controller architecture 50 may consider other forms of unintended joystick movement during step 196. For example, in some implementations, the controller architecture 50 may consider whether there has been unintended slippage of one or both of the joysticks 60 relative to their stop positions. This can be indicated by the displacement of a joystick 60 relative to its stop position given without operator contact, and can be determined using any of the aforementioned sensors 82 capable of monitoring physical contact between the operator and the joystick 60. This displacement can be indicated by data input by the operator into the MRF joystick system 22 using the operator interface 78, which reports problems with stop slippage. Similarly, in implementations where the joystick device has a friction-holding configuration and unintended joystick movement (in the form of joystick drift) can occur due to disturbance forces applied to the work vehicle, a similar method can be used to evaluate the slippage of one or more joysticks under consideration.

[0064] Proceeding to step 204 of the unintended joystick movement inhibition process 190, the controller architecture 50 then commands the MRF joystick resistance mechanism 56 to increase the joystick stiffness by a controlled amount to attempt to reduce or eliminate the ongoing unintended joystick movement. In one embodiment, the controller architecture 50 may initially apply a low or medium level increase in joystick stiffness to determine whether such an increase in joystick stiffness is sufficient to suppress the detected unintended joystick movement. In other cases, the initially applied increase in joystick stiffness may be variable, wherein the controller architecture 50 determines the magnitude of the joystick stiffness increase based on the severity of the currently detected unintended joystick movement. Additionally, as previously described, in embodiments of the MRF joystick resistance mechanism 56, the controller architecture 50 may be able to apply multiple different stiffness increases to a given joystick (e.g., a first joystick stiffness increase resisting rotation of the joystick about a first axis and a second joystick stiffness increase resisting rotation of the joystick about a second axis perpendicular to the first axis). Finally, during step 204, in the case of a self-centering joystick device with a stop position, when joystick slippage relative to the stop position has previously occurred, the controller architecture 50 commands the MRF resistance mechanism 56 to increase the stop holding force to hold one or more joysticks 60 in the stop position (when the joystick is residing in the stop position). Similarly, in the case of a friction-holding joystick device, when joystick drift is determined to have occurred without operator contact with the joystick, the controller architecture 50 may command the MRF joystick resistance mechanism 56 to increase the joystick stiffness by one or more DOFs.

[0065] If, in step 204, unintended joystick movement continues despite the previously applied increase in stiffness, the controller architecture 50 may command the MRF joystick resistance mechanism 56 to increase the MRF stiffness force against joystick movement at least at DOF. The controller architecture 50 may command the MRF joystick resistance mechanism to increase the applied joystick stiffness gradually (continuously or incrementally) until the detected unintended joystick movement stops, until such joystick movement reaches an acceptable level, or until the maximum desired MRF stiffness force is reached. Therefore, in the case of a sensed joystick 0IO, the controller architecture 50 may repeatedly estimate the amplitude of the operator-induced swing and then gradually increase the first joystick stiffness until the amplitude of the operator-induced swing of the joystick decreases below a predetermined acceptable threshold. In the case of stop slippage, the controller architecture 50 may command the MRF resistance mechanism 56 to increase the stop holding force to a predetermined level; and if repeated displacement of the joystick relative to the stop position is detected without operator contact, the stop holding force may be further increased as needed. Therefore, during multiple iterations of the unexpected joystick movement prohibition process 190, the controller architecture 50 can continuously and gradually increase the stop holding force until the operator of the work vehicle no longer detects or reports stop slippage. After achieving any or all of the above joystick stiffness increases, the controller architecture 50 proceeds to step 206 of the unexpected joystick movement prohibition process 190 and determines whether the current iteration of process 190 should terminate, as described below.

[0066] After steps 202 and / or 204, controller architecture 50 proceeds to step 206 and determines whether the current iteration of the unexpected joystick movement prohibition process 190 should terminate: for example, due to the work vehicle stopping or due to condition elimination or a triggering event of process 190. If it is determined in step 206 that the unexpected joystick movement prohibition process 190 should terminate, controller architecture 50 proceeds to step 208 of process 190, and process 190 terminates accordingly. If it is alternatively determined that the unexpected joystick movement prohibition process 190 should continue, controller architecture 50 returns to step 194 of the active paths 194, 198, 202 and / or returns to step 196 of the reactive control paths 196, 200, 204 and repeats the steps of the above process. Additionally, before returning to steps 194 and / or 196, controller architecture 50 may also determine in step 207 whether any currently applied joystick stiffness increase should be reduced or removed. For example, in step 207, controller architecture 50 may determine that any currently applied increase in joystick stiffness should be revoked due to the cessation of an unexpected joystick movement condition that previously propelled an increase in joystick stiffness. Similarly, in an implementation where controller architecture 50 commands an increase in MRF joystick stiffness to reduce or eliminate currently occurring unexpected joystick movement (e.g., joystick OIO), controller architecture 50 may determine whether a predetermined time period (e.g., several seconds) has elapsed if no unexpected joystick movement is detected; and if so, revoking or reducing any previously applied increase in joystick stiffness. In this way, controller architecture 50 can selectively apply such an increase in joystick stiffness as needed to counteract or buffer unexpected joystick movement. Alternatively, the stiffness of one or more joystick devices may be kept at a low level to provide the operator with an optimized joystick interaction experience that reduces operator fatigue and increases operator satisfaction.

[0067] Additional examples of work vehicles equipped with MRF joystick systems

[0068] Therefore, the above describes an example of an MRF joystick system configured to selectively constrain joystick movement to reduce unintended joystick movement by intelligently applying joystick stiffness variations achieved through MRF. While the above description focuses primarily on a specific type of work vehicle (excavator) including specific joystick-controlled work vehicle functions (boom assembly movement), the implementation of the MRF joystick system described herein is suitable for integration into a wide variety of work vehicles containing joystick devices susceptible to unintended joystick movement. Three further examples of such work vehicles are described below. Figure 6The upper part describes and includes a wheel loader 216, a skid steer loader (SSL) 218, and a grader 220. Firstly, regarding the wheel loader 216, the wheel loader 216 may be equipped with an example MRF joystick device 222 located within the cab 224 of the wheel loader 216. For example... Figure 6 As indicated in the document, the MRF joystick 222 can be used to control the movement of the FEL 226, which terminates at the bucket 228; the FEL 226 and the front loader are generally considered to be of the "boom assembly" type in the context of this document. In contrast, two MRF joysticks 230 may be located in the cab 232 of the example SSL 218, and are used not only to control the movement of the FEL 234 and its bucket 236, but also to control the movement of the chassis 238 of the SSL 218 in a well-known manner. Finally, the grader 220 also includes two MRF joysticks 240 located in the cab 242 of the grader 220. The MRF joysticks 240 can be used to control the movement of the grader chassis 244 (by controlling a first transmission driving the rear wheels of the grader and, possibly, a second (e.g., hydrostatic) transmission driving the front wheels), and also, for example, to control the movement of the grader's bucket 246 by rotation and angle adjustment of the cutter turntable assembly 248 and lateral offset angle adjustment of the cutter 246.

[0069] In the examples mentioned above, the controllable MRF joystick device reduces unintended joystick movement by intelligently applying joystick stiffness variations via the MRF. In this regard, any or all of the examples wheel loader 216, SSL 218, and grader 220 may be equipped with a work vehicle MRF joystick system comprising at least one joystick device, an MRF joystick resistance mechanism, and a controller architecture. Furthermore, as described above, the controller architecture can be configured to detect whether unintended joystick movement conditions occur during the operation of the work vehicle in question, whether such unintended joystick movement conditions are characterized by currently existing unintended joystick movement (e.g., joystick OIO) or by the undesirable high probability of unintended joystick movement occurring in the recent timeframe: for example, due to sensed impact forces applied to tools or other parts of the work vehicle on which the boom assembly is mounted, sudden changes in the inertia of the work vehicle, operation of the work vehicle under conditions associated with disturbing forces, attachment or use of implements or tools that tend to generate disturbing forces, or any of the other conditions described throughout this document. Finally, in Figure 6 The bottom section illustrates other examples of work vehicles usefully equipped with embodiments of the MRF joystick system described herein, and these examples include a tractor 250 equipped with a FEL, a logging and stacking combine harvester 252, a timber harvester 254, a combine harvester 256, and a bulldozer 258.

[0070] Enumeration examples of vehicle MRF joystick systems

[0071] For ease of reference, the following examples of MRF joystick systems for work vehicles are also provided and numbered.

[0072] 1. In one embodiment, a magnetorheological fluid (MRF) joystick system for a work vehicle includes a joystick assembly, an MRF joystick resistance mechanism, and a controller architecture. The joystick assembly further includes a base housing, a joystick movably mounted on the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The MRF joystick resistance mechanism is controllable to change a first joystick stiffness, the first joystick stiffness resisting movement of the joystick relative to the base housing with at least one degree of freedom. The controller architecture, coupled to the joystick position sensor and the MRF joystick resistance mechanism, is configured to: (i) detect whether an unexpected joystick movement condition occurs during operation of the work vehicle; and (ii) when an unexpected joystick movement condition is detected, command the MRF joystick resistance mechanism to increase the first joystick stiffness in a manner that reduces the sensitivity of the joystick assembly to unexpected joystick movement.

[0073] 2. The work vehicle MRF joystick system according to Example 1, wherein the controller architecture is configured to detect whether an unexpected joystick movement condition occurs during operation of the work vehicle by determining whether the joystick movement sensed by the joystick position sensor is intentionally caused by the operator of the work vehicle.

[0074] 3. The work vehicle MRF joystick system according to Example 2, wherein the controller architecture is further configured to: (i) identify whether the joystick movement sensed by the joystick position sensor includes swing of the joystick caused by the operator; and (ii) when the joystick movement includes swing of the joystick caused by the operator of the work vehicle, determine that the joystick movement is unintentionally caused by the operator.

[0075] 4. The MRF joystick system for work vehicles according to Example 3, wherein the controller architecture is further configured to: (i) estimate the amplitude of the swing caused by the operator when it is identified that the joystick movement includes an operator-induced swing of the joystick; and (ii) gradually increase the stiffness of the first joystick until the amplitude of the operator-induced swing of the joystick is reduced to below a predetermined acceptable threshold.

[0076] 5. The work vehicle MRF joystick system according to Example 1 further includes an interference force sensor attached to a location on the work vehicle remote from the joystick and connected to a controller architecture. The controller architecture is configured to detect an unexpected joystick movement condition during operation of the work vehicle when the interference force sensor detects an interference force exceeding a predetermined threshold.

[0077] 6. The MRF joystick system for the work vehicle according to Example 5, wherein the controller architecture is further configured to command the MRF joystick resistance mechanism to increase the stiffness of the first joystick by an amount substantially proportional to the magnitude of the disturbance force detected by the disturbance force sensor.

[0078] 7. The work vehicle MRF joystick system according to Example 1 further includes an interference force sensor attached to the work vehicle and connected to a controller architecture. The controller architecture is also configured to: (i) monitor the impact force detected by the interference force sensor; and (ii) when the interference force sensor detects an impact force exceeding a predetermined threshold, command the MRF joystick resistance mechanism to increase the first joystick stiffness before or substantially simultaneously with the impact force propagating to the joystick device.

[0079] 8. The MRF joystick system for the work vehicle according to Example 7, wherein an interference force sensor is integrated into the boom assembly attached to the chassis of the work vehicle. The controller architecture is configured to monitor the impact force detected by the interference force sensor during use of the boom assembly.

[0080] 9. The work vehicle MRF joystick system according to Example 1 further includes a vehicle motion data source coupled to the controller architecture. The controller architecture is configured to detect unexpected joystick movement conditions by utilizing data from the vehicle motion data source to detect abrupt changes in the speed, direction of travel, or orientation of the work vehicle.

[0081] 10. The work vehicle MRF joystick system according to Example 1, wherein the controller architecture is configured to detect whether an unexpected joystick movement condition occurs, at least in part based on the specific type of implement used by the work vehicle.

[0082] 11. The MRF joystick system for a work vehicle according to Example 1, wherein the joystick assembly includes a stop position with a stop holding force. The controller architecture is configured to command the MRF joystick resistance mechanism to increase the stop holding force of the stop position upon detecting an unexpected joystick movement condition.

[0083] 12. The MRF joystick system for a work vehicle according to Example 1, wherein the joystick device is rotatable relative to the base housing about a first axis and a second axis perpendicular to the first axis. The first joystick stiffness is the force resisting rotation of the joystick device about at least the first axis.

[0084] 13. The MRF joystick system for a work vehicle according to Example 12, wherein the MRF joystick resistance mechanism can also be controlled to change the stiffness of a second joystick, the second joystick stiffness resisting rotation of the joystick about a second axis. The controller architecture is configured to selectively command the MRF joystick resistance mechanism to change the stiffness of the first joystick independently of the second joystick stiffness.

[0085] 14. The work vehicle MRF joystick system according to Example 1 further includes an operator interface coupled to a controller architecture. The controller architecture is configured to detect, at least in part, whether an unexpected joystick movement condition has occurred based on operator input input via the operator interface, indicating a potential increase in disturbance force during an upcoming operation of the work vehicle.

[0086] 15. In another embodiment, a work vehicle MRF joystick system includes a joystick assembly, an MRF joystick resistance mechanism, and a controller architecture. The joystick assembly includes a base housing, a joystick movably mounted on the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The controller architecture is coupled to the joystick position sensor and the MRF joystick resistance mechanism, which can be controlled to change the joystick stiffness, the joystick stiffness resisting movement of the joystick relative to the base housing with at least one degree of freedom. The controller architecture is configured to: (i) determine, at least in part, based on data provided by the joystick position sensor, whether an unintended joystick movement is currently occurring; and (ii) when it is determined that an unintended joystick movement is currently occurring, command the MRF joystick resistance mechanism to increase the joystick stiffness in a manner that reduces the unintended joystick movement.

[0087] in conclusion

[0088] Therefore, the above provides a work vehicle MRF joystick system configured to reduce unintended joystick movement by intelligently applying joystick stiffness variations via MRF. By strategically applying MRF stiffness forces to prevent unintended joystick movement, implementations of the MRF joystick system minimize operator fatigue and enhance operator experience by reducing the degree of unintended joystick movement that may result from physical counteraction or correction by the operator. Furthermore, the reduction in unintended joystick movement also reduces unintended movement of the work vehicle (or other joystick-controlled actions), minimizing component wear, improving efficiency, and otherwise facilitating precise and consistent control of the work vehicle's movement and function in response to operator commands. The highly responsive nature of the MRF joystick resistance mechanism allows the joystick stiffness to increase rapidly in response to the detection of disturbance forces (such as interference caused by a tool striking a surface) before or substantially simultaneously with the travel of such vibrations to the operator and the MRF joystick device. Furthermore, the implementation of the MRF joystick resistance mechanism can generate MRF stiffness force over a continuous range, thereby enabling the MRF joystick device to gradually increase joystick stiffness (in a stepwise or continuous manner) in certain situations; for example, to gradually drive the sensed OIO motion to zero or in response to increased vibration intensity in a high-vibration environment. As described above, various other benefits are obtained through the implementation of the work vehicle MRF joystick system.

[0089] As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or variations thereof, when used in this specification, specify the presence of the said feature, integral, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.

[0090] The description of this disclosure has been shown for illustrative and descriptive purposes, but it is not intended to be exclusive or limited to the disclosed forms. 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 explicitly referenced herein have been selected and described in order to best explain the principles of this disclosure and its practical application, and to enable others skilled in the art to understand this disclosure and identify alternative forms, modifications, and variations of the described examples. Therefore, various embodiments and implementations other than those explicitly described are also within the scope of the following 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 device (52) includes: Base housing (62); A joystick (60) is movably mounted on the base housing (62); and A joystick position sensor (66) is configured to monitor the movement of the joystick (60) relative to the base housing (62); A magnetorheological fluid joystick resistance mechanism (56) is controllable to change the stiffness of a first joystick, the stiffness of which resists movement of the joystick relative to the base housing (62) with at least one degree of freedom; and A controller architecture (50) is connected to the joystick position sensor (66) and the magnetorheological fluid joystick resistance mechanism (56), and the controller architecture (50) is configured as follows: Detect whether any unexpected joystick movement occurs during the operation of the work vehicle (20); and When an unexpected joystick movement condition is detected, the magnetorheological fluid joystick resistance mechanism (56) is commanded to increase the stiffness of the first joystick in a manner that reduces the sensitivity of the joystick device (52) to the unexpected joystick movement. The joystick device (52) includes a stop position with a stop holding force; and The controller architecture (50) is configured to command the magnetorheological fluid joystick resistance mechanism (56) to increase the stop holding force at the stop position when an unexpected joystick movement condition is detected.

2. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 1, wherein, The controller architecture (50) is configured to detect whether an unexpected joystick movement condition occurs during operation of the work vehicle by determining whether the joystick movement sensed by the joystick position sensor (66) is intentionally caused by the operator of the work vehicle (20).

3. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 2, wherein, The controller architecture (50) is also configured as follows: Identify whether the joystick movement sensed by the joystick position sensor (66) includes the swing of the joystick (60) caused by the operator; and When the joystick movement includes a swing of the joystick (60) caused by the operator of the work vehicle, it is determined that the joystick movement is unintentionally caused by the operator.

4. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 3, wherein, The controller architecture (50) is also configured as follows: When the joystick movement is identified as including an operator-induced swing of the joystick (60), the amplitude of the operator-induced swing is estimated; as well as Gradually increase the stiffness of the first joystick until the amplitude of the swing of the joystick (60) caused by the operator decreases below a predetermined acceptable threshold.

5. The magnetorheological fluid joystick system (22) for a work vehicle according to claim 1, wherein the magnetorheological fluid joystick system for a work vehicle further includes a vehicle motion data source (74) connected to the controller architecture (50); and in, The controller architecture (50) is configured to detect unexpected joystick movement conditions by using data from the vehicle motion data source (74) to detect sudden changes in the speed, direction of travel, or orientation of the work vehicle (20).

6. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 1, wherein, The controller architecture (50) is configured to detect whether an unexpected joystick movement condition occurs, at least in part based on the specific type of implements used by the work vehicle (20).

7. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 1, wherein, The joystick device (52) is rotatable relative to the base housing (62) about a first axis and a second axis perpendicular to the first axis; and The stiffness of the first joystick includes a force that resists rotation of the joystick device (52) about at least the first axis.

8. The magnetorheological fluid control joystick system (22) for the work vehicle according to claim 7, wherein, The magnetorheological fluid joystick resistance mechanism (56) can also be controlled to change the stiffness of the second joystick, which resists rotation of the joystick (60) about the second axis; and The controller architecture (50) is configured to selectively command the magnetorheological fluid joystick resistance mechanism (56) to change the stiffness of the first joystick independently of the stiffness of the second joystick.

9. The magnetorheological fluid joystick system (22) for a work vehicle according to claim 1, wherein the magnetorheological fluid joystick system for a work vehicle further includes an operator interface (78) connected to the controller architecture (50); and in, The controller architecture (50) is configured to detect, at least in part, whether an unexpected joystick movement condition occurs based on operator input input via the operator interface (78), which indicates a potential increase in disturbance force during an upcoming operation of the work vehicle (20).

10. A magnetorheological fluid joystick system (22) for use on a work vehicle (20), the work vehicle magnetorheological fluid joystick system (22) comprising: The joystick device (52) includes: Base housing (62); A joystick (60) is movably mounted on the base housing (62); and A joystick position sensor (66) is configured to monitor the movement of the joystick (60) relative to the base housing (62); A magnetorheological fluid joystick resistance mechanism (56) is controllable to change the stiffness of a first joystick, the stiffness of which resists movement of the joystick relative to the base housing (62) with at least one degree of freedom; and A controller architecture (50) is connected to the joystick position sensor (66) and the magnetorheological fluid joystick resistance mechanism (56), and the controller architecture (50) is configured as follows: Detect whether any unexpected joystick movement occurs during the operation of the work vehicle (20); and When an unexpected joystick movement condition is detected, the magnetorheological fluid joystick resistance mechanism (56) is commanded to increase the stiffness of the first joystick in a manner that reduces the sensitivity of the joystick device (52) to the unexpected joystick movement. The magnetorheological joystick system (22) for the work vehicle also includes an interference force sensor (70), which is attached to the work vehicle (20) at a location remote from the joystick device (52) and connected to the controller architecture (50); and The controller architecture (50) is configured to detect an unexpected joystick movement condition during operation of the work vehicle (20) when the interference force sensor (70) detects an interference force exceeding a predetermined threshold.

11. The magnetorheological fluid joystick system (22) for a work vehicle according to claim 10, wherein, The controller architecture (50) is also configured to command the magnetorheological joystick resistance mechanism (56) to increase the stiffness of the first joystick by an amount substantially proportional to the magnitude of the disturbance force detected by the disturbance force sensor (70).

12. A magnetorheological fluid joystick system (22) for use on a work vehicle (20), the work vehicle magnetorheological fluid joystick system (22) comprising: The joystick device (52) includes: Base housing (62); A joystick (60) is movably mounted on the base housing (62); and A joystick position sensor (66) is configured to monitor the movement of the joystick (60) relative to the base housing (62); A magnetorheological fluid joystick resistance mechanism (56) is controllable to change the stiffness of a first joystick, the stiffness of which resists movement of the joystick relative to the base housing (62) with at least one degree of freedom; and A controller architecture (50) is connected to the joystick position sensor (66) and the magnetorheological fluid joystick resistance mechanism (56), and the controller architecture (50) is configured as follows: Detect whether any unexpected joystick movement occurs during the operation of the work vehicle (20); and When an unexpected joystick movement condition is detected, the magnetorheological fluid joystick resistance mechanism (56) is commanded to increase the stiffness of the first joystick in a manner that reduces the sensitivity of the joystick device (52) to the unexpected joystick movement. The magnetorheological joystick system (22) for the work vehicle also includes an interference force sensor (70), which is attached to the work vehicle (20) and connected to the controller architecture (50); and The controller architecture (50) is further configured as follows: Monitor the impact force detected by the interference force sensor (70); and When the interference force sensor (70) detects an impact force exceeding a predetermined threshold, it commands the magnetorheological fluid joystick resistance mechanism (56) to increase the stiffness of the first joystick before or substantially simultaneously with the impact force propagating to the joystick device (52).

13. The magnetorheological fluid control joystick system (22) for a work vehicle according to claim 12, wherein, The interference force sensor (70) is integrated into the boom assembly (24) attached to the chassis (28) of the work vehicle (20); and The controller architecture (50) is configured to monitor the impact force detected by the disturbance force sensor (70) during the use of the boom assembly (24).

14. A magnetorheological fluid joystick system (22) for use on a work vehicle, the magnetorheological fluid joystick system (22) comprising: The joystick device (52) includes: Base housing (62); A joystick (60) is movably mounted on the base housing (62); and A joystick position sensor (66) is configured to monitor the movement of the joystick (60) relative to the base housing (62); A magnetorheological fluid joystick resistance mechanism (56) is available, which can be controlled to change the joystick stiffness, the joystick stiffness resisting movement of the joystick relative to the base housing (62) with at least one degree of freedom; and A controller architecture (50) is connected to the joystick position sensor (66) and the magnetorheological fluid joystick resistance mechanism (56), and the controller architecture (50) is configured as follows: The determination of whether an unexpected joystick movement is currently occurring is based at least in part on data provided by the joystick position sensor (66); and When it is determined that an unexpected joystick movement is currently occurring, the magnetorheological fluid joystick resistance mechanism (56) is commanded to increase the joystick stiffness in a manner that reduces the unexpected joystick movement; and The determination of whether the unexpected joystick movement is currently occurring is based at least in part on assessing whether the joystick has unintentionally shifted from its stop position during operation of the work vehicle.

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