Tractive torque control for side-hilling

Abstract

A power machine (100) includes a power source (222), a first tractive element, a second tractive element and a tractive drive system (326) coupled to the power source (222). The tractive drive system (326) includes at least one drive motor configured to drive the first and the second tractive elements, a tractive drive control (327) and at least one sensor configured to sense six degrees of movement of the power machine (100). The tractive drive control (327) is configured to use sensor data from the at least one sensor to determine that the power machine (100) is located on a slope and automatically counteracts gravitational forces by applying a torque that causes the first tractive element to rotate at a different speed from the second tractive element.

Description

Attorney Docket No. B2024-0021-W01TRACTIVE TORQUE CONTROL FOR SIDE-HILLINGCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States provisional application no. 63 / 682, 151, filed 12 August 2024, which is hereby incorporated by reference in its entirety as though fully set forth herein.BACKGROUND

[0002] This disclosure is directed toward power machines. More particularly, this disclosure is directed to tractive torque control when a vehicle is side-hilling.

[0003] Power machines, for the purposes of this disclosure, include any type of machine that generates power to accomplish a particular task or a variety of tasks. One type of power machine is a work vehicle. Work vehicles, such as loaders, are generally self-propelled vehicles that have a work device, such as a lift arm (although some work vehicles can have other work devices) that can be manipulated to perform a work function. Work vehicles include loaders, excavators, utility vehicles, tractors, and trenchers, to name a few examples.

[0004] When a power machine side-hills with the intent of straight trajectory, the force of gravity acting on the power machine may induce a yaw that draws the power machine downhill. To correct for this yaw, an operator may need to provide a steering input to maintain the side-hill, straight trajectory.

[0005] The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.SUMMARY

[0006] A power machine includes a power source, a first tractive element, a second tractive element and a tractive drive system coupled to the power source. The tractive drive system includes at least one drive motor configured to drive the first and the second tractive elements, a tractive drive control and at least one sensor configured to sense six degrees of movement of the power machine. The tractive drive control is configured to use sensor data from the at least one sensor to determine that the power machine is located on a slope with the first tractive element being located downhill relative to the second tractive element. In response to determining that the power machine is located on the slope, the tractive drive control is further configured to automatically counteractAttorney Docket No. B2024-0021-W01 gravitational forces by applying a torque that rotates the first tractive element at a different speed from the second tractive element.

[0007] A power machine includes a power source, a front frame member having at least a first tractive element and a second tractive element, a rear frame member having at least a first tractive element and a second tractive element, and a tractive drive system coupled to the power source. The tractive drive system includes a plurality of electric drive motors each configured to drive a corresponding first or second tractive element of the front frame member or a corresponding first or second tractive element of the rear frame member, at least one sensor configured to sense six degrees of movement of the power machine and a tractive drive control coupled to the sensor. Based on sensed data from the sensor, the tractive drive control is configured to counteract the effects of gravity of the power machine while on a slope by commanding control signals to each of the plurality of electric drive motors to independently actuate each of the first and second tractive elements on the front and rear frame members.

[0008] A method of counteracting the effects of gravity on a power machine located on a slope is provided. The method includes providing power to a plurality of electric drive motors each configured to drive a corresponding first or second tractive element of the front frame member or a corresponding first or second tractive element of the rear frame member. Six degrees of movement of the power machine are sensed to determine that the first tractive element on the front frame member is located downhill from the second tractive element on the front frame member and the first tractive element on the rear frame member is located downhill from the second tractive element on the rear frame member. Control signals are commanded to each of a plurality of electric drive motors to drive a corresponding first tractive element or second tractive element of the front frame member or a corresponding first tractive element or second tractive element of the rear frame member based on the sensed data from the sensor to independently rotate each of the first and second tractive elements on the front frame member and first and second tractive elements on the rear frame member.

[0009] This Summary and the Abstract are provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary and the Abstract are not intended to identify key features or essential features of the claimed subject matter, nor are they intended to be used as an aid in determining the scope of the claimed subject matter.Attorney Docket No. B2024-0021-W01DRAWINGS

[0010] FIG. 1 is a block diagram illustrating functional systems of a representative power machine on which embodiments of the present disclosure may be advantageously practiced.

[0011] FIG. 2 is a perspective view showing generally a front perspective view of a power machine in the form of an articulated loader on which embodiments disclosed in this specification may be advantageously practiced.

[0012] FIG. 3 is a perspective view showing generally a back perspective view of the articulated loader shown in FIG. 2.

[0013] FIG. 4 is a front view of the articulated loader shown in FIGS. 2 and 3 side-hilling on a straight trajectory.

[0014] FIG. 5 is a back view of the articulated loader side-hilling on the same straight trajectory as illustrated in FIG. 4.

[0015] FIG. 6 is a block diagram illustrating components of a power system of a power machine such as the power system in the articulated loader illustrated in FIGS. 2-5.

[0016] FIG. 7 is a block diagram of related components useful in understanding tractive torque control in a power machine during side-hilling to prevent dropping downhill according to an embodiment.

[0017] FIG. 8 illustrates a diagrammatic top view of the articulated loader illustrated in FIGS. 2- 5.

[0018] FIG. 9 illustrates a diagrammatic top view of another power machine according to an embodiment.

[0019] FIG. 10 illustrates a diagrammatic top view of yet another power machine according to an embodiment.DESCRIPTION

[0020] The concepts disclosed in this discussion are described and illustrated by referring to exemplary embodiments. These concepts, however, are not limited in their application to the details of construction and the arrangement of components in the illustrative embodiments and are capable of being practiced or being conducted in various other ways. The terminology in this document is used for the purpose of description and should not be regarded as limiting. WordsAttorney Docket No. B2024-0021-W01 such as “including,” “comprising,” and “having” and variations thereof as used herein are meant to encompass the items listed thereafter, equivalents thereof, as well as additional items.

[0021] Disclosed embodiments include a tractive drive system for a power machine. In one embodiment, the drive system includes independent electric motors which drive or actuate each wheel. However, in an instance where the power machine is side-hilling on a slope along a straight trajectory, and with a matched velocity control provided to all four wheel motors, the power machine may experience the effects of gravity, which can induce a yaw rotation on the power machine about, for example, a vertical axis, causing the power machine to be pulled down the hill.

[0022] To counteract the effects of gravity, the disclosed embodiments command different torques or speeds of the downhill and uphill wheels based on sensor data from an at least one inertial mass unit (IMU) sensor or gyroscope sensor that senses motion in six degrees of movement including rotation about each axis (roll, pitch and yaw) and translation along each axis (x, y and z). As a result, the loader will automatically maintain a straight trajectory while side-hilling.

[0023] These concepts can be practiced on various power machines, as will be described below. A representative power machine on which the embodiments can be practiced is illustrated in diagram form in FIG. 1 and one example of such a power machine is illustrated in FIGS. 2-3 and described below before any embodiments are disclosed. For the sake of brevity, only one power machine is discussed. However, as mentioned above, the embodiments below can be practiced on any of a number of power machines, including power machines of different types from the representative power machine shown in FIGS. 2-3. Power machines, for the purposes of this discussion, include a frame, at least one work element, and a power source that can provide power to the work element to accomplish a work task. One type of power machine is a self-propelled work vehicle. Self-propelled work vehicles are a class of power machines that include a frame, work element, and a power source that can provide power to the work element. At least one of the work elements is a motive system for moving the power machine under power.

[0024] FIG. l is a block diagram illustrating the basic systems of a power machine 100 upon which the embodiments discussed below can be advantageously incorporated and can be any of a number of different types of power machines. The block diagram of FIG. 1 identifies various systems on power machine 100 and the relationship between various components and systems. As mentioned above, at the most basic level, power machines for the purposes of this discussion include a frame, a power source, and a work element. The power machine 100 has a frame 110, a power sourceAttorney Docket No. B2024-0021-W01120, and a work element 130. Because power machine 100 shown in FIG. 1 is a self-propelled work vehicle, it also has tractive elements 140, which are themselves work elements provided to move the power machine over a support surface and an operator station 150 that provides an operating position for controlling the work elements of the power machine. A control system 160 is provided to interact with the other systems to perform various work tasks at least in part in response to control signals provided by an operator.

[0025] Certain work vehicles have work elements that can perform a dedicated task. For example, some work vehicles have a lift arm to which an implement such as a bucket is attached such as by a pinning arrangement. The work element, i.e., the lift arm can be manipulated to position the implement to perform the task. In some instances, the implement can be positioned relative to the work element, such as by rotating a bucket relative to a lift arm, to further position the implement. Under normal operation of such a work vehicle, the bucket is intended to be attached and under use. Such work vehicles may be able to accept other implements by disassembling the implement / work element combination and reassembling another implement in place of the original bucket. Other work vehicles, however, are intended to be used with a wide variety of implements and have an implement interface such as implement interface 170 shown in FIG. 1. At its most basic, implement interface 170 is a connection mechanism between the frame 110 or a work element 130 and an implement, which can be as simple as a connection point for attaching an implement directly to the frame 110 or a work element 130 or more complex, as discussed below.

[0026] On some power machines, implement interface 170 can include an implement carrier, which is a physical structure movably attached to a work element. The implement carrier has engagement features and locking features to accept and secure any of a number of different implements to the work element. One characteristic of such an implement carrier is that once an implement is attached to it, the implement carrier is fixed to the implement (i.e. not movable with respect to the implement) and when the implement carrier is moved with respect to the work element, the implement moves with the implement carrier. The term implement carrier as used herein is not merely a pivotal connection point, but rather a dedicated device specifically intended to accept and be secured to various different implements. The implement carrier itself is mountable to a work element 130 such as a lift arm or the frame 110. Implement interface 170 can also include one or more power sources for providing power to one or more work elements on an implement. Some power machines can have a plurality of work element with implement interfaces, each ofAttorney Docket No. B2024-0021-W01 which may, but need not, have an implement carrier for receiving implements. Some other power machines can have a work element with a plurality of implement interfaces so that a single work element can accept a plurality of implements simultaneously. Each of these implement interfaces can, but need not, have an implement carrier.

[0027] Frame 110 includes a physical structure that can support various other components that are attached thereto or positioned thereon. Frame 110 can include any number of individual components. Some power machines have frames that are rigid. That is, no part of the frame is movable with respect to another part of the frame. Other power machines have at least one portion that can move with respect to another portion of the frame. For example, excavators can have an upper frame portion that rotates with respect to a lower frame portion. Other work vehicles have articulated frames such that one portion of the frame pivots with respect to another portion for accomplishing steering functions.

[0028] Frame 110 supports the power source 120, which can provide power to one or more work elements 130 including the one or more tractive elements 140, as well as, in some instances, providing power for use by an attached implement via implement interface 170. Power from the power source 120 can be provided directly to any of the work elements 130, tractive elements 140, and implement interfaces 170. Alternatively, power from the power source 120 can be provided to a control system 160, which in turn selectively provides power to the elements that are capable of using it to perform a work function. Power sources for power machines may include an engine, such as an internal combustion engine, and a power conversion system, such as a mechanical transmission or a hydraulic system that is capable of converting the output from an engine into a form of power that is usable by a work element, or other types of power sources including electrical sources provided by, for example, batteries, or a combination of power sources, known generally as hybrid power sources.

[0029] FIG. 1 shows a single work element designated as work element 130, but various power machines can have any number of work elements. Work elements are typically attached to the frame of the power machine and movable with respect to the frame when performing a work task. In addition, tractive elements 140 are a special case of work element in that their work function is generally to move the power machine 100 over a support surface. Tractive elements 140 are shown separate from the work element 130 because many power machines have additional work elements besides tractive elements, although that is not always the case. Power machines can have anyAttorney Docket No. B2024-0021-W01 number of tractive elements, some or all of which can receive power from the power source 120 to propel the power machine 100. Tractive elements can be, for example, wheels attached to an axle, track assemblies, and the like. Tractive elements can be mounted to the frame such that movement of the tractive element is limited to rotation about an axle (so that steering is accomplished by a skidding action) or, alternatively, pivotally mounted to the frame to accomplish steering by pivoting the tractive element with respect to the frame.

[0030] Power machine 100 includes an operator station 150 that includes an operating position from which an operator can control operation of the power machine. In some power machines, the operator station 150 is defined by an enclosed or partially enclosed cab. Some power machines on which the disclosed embodiments may be practiced may not have a cab or an operator compartment of the type described above. For example, a walk behind loader may not have a cab or an operator compartment, but rather an operating position that serves as an operator station from which the power machine is properly operated. More broadly, power machines other than work vehicles may have operator stations that are not necessarily similar to the operating positions and operator compartments referenced above. Further, some power machines such as power machine 100 and others, whether they have operator compartments, operator positions or neither, may be capable of being operated remotely (i.e. from a remotely located operator station) instead of or in addition to an operator station adjacent or on the power machine. This can include applications where at least some of the operator-controlled functions of the power machine can be operated from an operating position associated with an implement that is coupled to the power machine. Alternatively, with some power machines, a remote-control device can be provided (i.e. remote from both the power machine and any implement to which is it coupled) that is capable of controlling at least some of the operator-controlled functions on the power machine.

[0031] FIGS. 2-3 illustrate a loader 200, which is one particular example of a power machine of the type illustrated in FIG. 1 where the embodiments discussed below can be advantageously employed. Loader 200 is an articulated loader with a front mounted lift arm assembly 230, which in this example is a telescopic lift arm. Loader 200 is one particular example of the power machine 100 illustrated broadly in FIG. 1 and discussed above. To that end, features of loader 200 described below include reference numbers that are generally similar to those used in FIG. 1. For example, loader 200 is described as having a frame 210, just as power machine 100 has a frame 110. The description herein of loader 200 with references to FIGS. 2-3 provides an illustration of theAttorney Docket No. B2024-0021-W01 environment in which the embodiments discussed below can be employed, and this description should not be considered limiting especially as to the description of features of loader 200 that are not essential to the disclosed embodiments. Such features may or may not be included in power machines other than loader 200 upon which the embodiments disclosed below may be advantageously practiced. Unless specifically noted otherwise, embodiments disclosed below can be practiced on a variety of power machines, with the loader 200 being only one of those power machines. For example, some or all of the concepts discussed below can be practiced on many other types of work vehicles such as various other loaders, excavators, trenchers, and dozers, to name but a few examples.

[0032] Loader 200 includes frame 210 that supports a power system 220 that can generate or otherwise provide power for operating various functions on the power machine. For example, power system 220 may provide electrical power for operating various functions on the power machine. Frame 210 also supports a work element in the form of lift arm assembly 230 that is powered by the power system 220 and that can perform various work tasks. As loader 200 is a work vehicle, frame 210 also supports a traction system 240, which is also powered by power system 220 and can propel the power machine over a support surface. The lift arm assembly 230 in turn supports an implement interface 270 that includes an implement carrier 272 that can receive and secure various implements to the loader 200 for performing various work tasks and power couplers 274 (shown diagrammatically), to which an implement can be coupled for selectively providing power to an implement that might be connected to the loader. Power couplers 274 can provide sources of hydraulic or electric power or both. The loader 200 includes a cab 250 that defines an operator station 255 from which an operator can manipulate various control devices to cause the power machine to perform various work functions. Cab 250 includes a canopy 252 that provides a roof for the operator compartment and is configured to have an entry 254 (for example, the left side as illustrated in FIG. 3) on one side of the seat to allow for an operator to enter and exit the cab. Although cab 250 as shown does not include any windows or doors, a door or windows can be provided.

[0033] The operator station 255 includes an operator seat 258 and the various operation input devices 260, including control levers that an operator can manipulate to control various machine functions. Operator input devices can include a steering wheel, buttons, switches, levers, sliders, pedals and the like that can be stand-alone devices such as hand operated levers or foot pedals orAttorney Docket No. B2024-0021-W01 incorporated into hand grips or display panels, including programmable input devices. Actuation of operator input devices can generate signals in the form of electrical signals, hydraulic signals, and / or mechanical signals. Signals generated in response to operator input devices are provided to various components on the power machine for controlling various functions on the power machine. Among the functions that are controlled via operator input devices on power machine 100 include control of the tractive system 240, the lift arm assembly 230, the implement carrier 272, and providing signals to any implement that may be operably coupled to the implement.

[0034] Loaders can include human-machine interfaces including display devices that are provided in the cab 250 to give indications of information relatable to the operation of the power machines in a form that can be sensed by an operator, such as, for example audible and / or visual indications. Audible indications can be made in the form of buzzers, bells, and the like or via verbal communication. Visual indications can be made in the form of graphs, lights, icons, gauges, alphanumeric characters, and the like. Displays can be dedicated to provide dedicated indications, such as warning lights or gauges, or dynamic to provide programmable information, including programmable display devices such as monitors of various sizes and capabilities. Display devices can provide diagnostic information, troubleshooting information, instructional information, and various other types of information that assist an operator with operation of the power machine or an implement coupled to the power machine. Other information that may be useful for an operator can also be provided. Other power machines, such walk behind loaders may not have a cab nor an operator compartment, nor a seat. The operator position on such loaders is generally defined relative to a position where an operator is best suited to manipulate operator input devices.

[0035] Various power machines that can include and / or interact with the embodiments discussed below can have various different frame components that support various work elements. The elements of frame 210 discussed herein are provided for illustrative purposes and should not be considered to be the only type of frame that a power machine on which the embodiments can be practiced can employ. As mentioned above, loader 200 is an articulated loader and as such has two frame members that are pivotally coupled together at an articulation joint. For the purposes of this document, frame 210 refers to the entire frame of the loader. Frame 210 of loader 200 includes a front frame member 212 and a rear frame member 214. The front and rear frame members 212, 214 are coupled together at an articulation joint 216 (FIG. 3). Actuators (not shown) are provided to rotate the front and rear frame members 212, 214 relative to each other about a vertical axis 217Attorney Docket No. B2024-0021-W01(FIG. 3) to accomplish a turn. As illustrated in FIG. 2, loader 200 has six degrees of movement. These include vertical up and down translation along vertical axis 217, back and forth translation along a longitudinal axis 215, side-to-side translation along a lateral axis 219, rotational roll 221 about longitudinal axis 215, rotational yaw 223 about vertical axis 217 and rotational pitch 225 about lateral axis 219.

[0036] The front frame member 212 supports and is operably coupled to the lift arm 230 at joint 216. A lift arm actuator (not shown, positioned beneath the lift arm 230) is coupled to the front frame member 212 and the lift arm 230 and is operable to raise and lower the lift arm under power. The front frame member 212 also supports at least two front tractive elements or wheels 242A and 242B. Front tractive elements or wheels 242A and 242B are mounted to rigid axles (the axles do not pivot with respect to the front frame member 212). The cab 250 is also supported by the front frame member 212 so that when the front frame member 212 articulates with respect to the rear frame member 214, the cab 250 moves with the front frame member 212 so that it will swing out to either side relative to the rear frame member 214, depending on which way the loader 200 is being steered.

[0037] The rear frame member 214 supports various components of the power system 220. In exemplary embodiments, the power system is an electric or hybrid electric power system. In addition, one or more hydraulic pumps may be coupled to an engine or an electric motor and supported by the rear frame member 214. In such embodiments, the hydraulic pumps are part of a power conversion system to convert power from the power system 220 into a form that can be used by actuators (such as cylinders) on the loader 200. However, some disclosed embodiments utilize only electric actuators and motors, and therefore do not require a hydraulic system. Power system 220 is discussed in more detail below. In addition, at least two rear tractive elements or wheels 242C and 242D are mounted to rigid axles that are in turn mounted to the rear frame member 214. When the loader 200 is pointed in a straight direction (i.e., the front frame portion 212 is aligned with the rear frame portion 214) a portion of the cab is positioned over the rear frame portion 214.

[0038] The lift arm assembly 230 shown in FIGS. 2-3 is one example of many different types of lift arm assemblies that can be attached to a power machine such as loader 200 or other power machines on which embodiments of the present discussion can be practiced. The lift arm assembly 230 is a radial lift arm assembly, in that the lift arm is mounted to the frame 210 at one end of theAttorney Docket No. B2024-0021-W01 lift arm assembly and pivots about the mounting joint 216 as it is raised and lowered. The lift arm assembly 230 may be a telescoping lift arm. The lift arm assembly includes a boom 232 that is pivotally mounted to the front frame member 212 at joint 216. A telescoping member 234 may be slidably inserted into boom 232 and telescoping cylinder (not shown) is coupled to the boom and the telescoping member and is operable to extend and retract the telescoping member under power. The telescoping member 234 is shown in FIGS. 2 and 3 in a fully retracted position. The implement interface 270 including implement carrier 272 and power couplers 274 are operably coupled to the telescoping member 234. An implement carrier mounting structure 276 is mounted to the telescoping member. The implement carrier 272 and the power couplers 274 are mounted to the positioning structure. A tilt actuator 278 is pivotally mounted to both the implement carrier mounting structure 276 and the implement carrier 272 and is operable to rotate the implement carrier with respect to the implement carrier mounting structure under power. Among the operator controls 260 in the operator compartment 255 are operator controls to allow an operator to control the lift, telescoping, and tilt functions of the lift arm assembly 230.

[0039] Other lift arm assemblies can have different geometries and can be coupled to the frame of a loader in various ways to provide lift paths that differ from the radial path of lift arm assembly 230. For example, some lift paths on other loaders provide a radial lift path. Others have multiple lift arms coupled together to operate as a lift arm assembly. Still other lift arm assemblies do not have a telescoping member. Others have multiple segments. Unless specifically stated otherwise, none of the inventive concepts set forth in this discussion are limited by the type or number of lift arm assemblies that are coupled to a particular power machine.

[0040] FIG. 4 is a front view and FIG. 5 is a back view of an exemplary articulated loader 200 shown in FIGS. 2 and 3 side-hilling, or moving orthogonally, on an incline 227 in a straight trajectory, or in a forward or backward translation along longitudinal axis 215. In FIGS. 4 and 5, first front and first rear (left) tractive elements or wheels 242A and 242C are located downhill on slope 227 and second front and second rear (right) tractive elements or wheels 242B and 242D are located uphill on slope 227. In addition, with slope 227, gravity induces yaw 223 about vertical axis 217. If the exemplary articulated loader 200 is not traveling orthogonal to slope 227, for example, and instead is moving uphill or downhill and at an angle across slope 227, gravity may induce a combination of yaw 223 about vertical axis 217, roll 221 (see FIG. 2) about longitudinal axis 215 and pitch 225 about lateral axis 219.Attorney Docket No. B2024-0021-W01

[0041] FIG. 6 is a block diagram illustrating components of a power system of a power machine such as the power system in the articulated loader illustrated in FIGS. 2-5. Broadly speaking, power system 220 includes one or more power sources 222 that can generate and / or store power for operating various machine functions. On loader 200, the power system 220 may include an internal combustion engine, electric generators, rechargeable batteries, various other power sources or any combination of power sources that can provide power for given power machine components. The power system 220 may also include a power conversion system 224, which is operably coupled to the power source 222. Power conversion system 224 in various power machines can include various components, including mechanical and / or electric transmissions, hydraulic systems, and the like. For example, power conversion system 224 may include a hydrostatic drive pump and an implement pump driven by power sources 222. The power conversion system 224 can also, or alternatively, include electrical power conversion or regulating circuitry. Power conversion system 224 may, in turn, be coupled to a tractive drive system 326, which can perform a tractive function on the power machine, may be coupled to articulation angle actuator(s) 270 and may be coupled to work actuator circuit 238. Tractive drive system 326, articulation angle actuator(s) 270 and work actuator circuit 238 may alternatively be coupled directly to power source 222 depending on the type of power source. For example, if the power source 222 is electric and includes electric generators or rechargeable batteries and tractive drive system 326 is an all-electric drive system, then tractive drive system 326 may be directly coupled to power source 222. If, for example, power source 222 is electric and includes electric generators or rechargeable batteries and articulation angle actuator 270 is a linear actuator, then articulation angle actuator 270 may be directly coupled to power source 222. If, for example, power source 222 is electric and includes electric generators or rechargeable batteries and work actuator circuit 238 is coupled to a work actuator 239 that is a linear actuator, then work actuator circuit 238 may be directly coupled to power source 222. However, if tractive drive system 326, articulation angle actuator 270 or work actuator 239 include other types of actuators, such as hydraulic actuators, tractive drive system 326, articulation angle actuator 270 and work actuator 239 can receive power from power conversion system 224. The power source 222 or the power conversion system 224 of power machine 200 provides power to tractive drive system 326.

[0042] Tractive drive system 326 includes a tractive drive control 327 coupled to drive motors 226A, 226B, 226C and 226D and may be coupled to an articulation sensor 375. Tractive driveAttorney Docket No. B2024-0021-W01 control 327 may include electronic controls providing electric control signals to operate drive motors 226A-D for speed and direction and torque. Although not shown, each of the four drive motors 226A-D may be coupled to the each of the tractive elements or wheels 242A-D, respectively. Under this embodiment, each drive motor 226A, 226B, 226C and 226D may be an electric motor that receives a power signal from power source 222 and independently drives or actuates each corresponding tractive element or wheel 242A, 242B, 242C and 242D. Still further, articulation sensor 375 may be configured to measure the angle between front frame member 212 and rear frame member 214 to aid tractive drive control 327 in managing wheel speeds of each tractive element 242A, 242B, 242C and 242D using drive motors 226A, 226B, 226C and 226D. Articulation sensor 375 may be linear, rotational, or can be generally described as a trajectory sensor if the power machine includes steering axles.

[0043] Work actuator 239 may be representative of a plurality of actuators, including the lift actuator, tilt actuator, telescoping actuator, and the like. The work actuator circuit 238 may include valves and other devices to selectively provide pressurized hydraulic fluid to the various work actuators represented by block 239 in FIG. 4 when power conversion system 224 includes hydraulic pumps. In addition, the work actuator circuit 238 may be configured to provide pressurized hydraulic fluid to work actuators on an attached implement.

[0044] The description of power machine 100 and loader 200 above is provided for illustrative purposes and to provide illustrative environments on which the embodiments discussed below can be practiced. While the embodiments discussed can be practiced on a power machine such as is generally described by the power machine 100 shown in the block diagram of FIG. 1 and more particularly on a loader such as articulated loader 200, unless otherwise noted or recited, the concepts discussed below are not intended to be limited in their application to the environments specifically described above.

[0045] FIG. 7 is a block diagram of related components useful in understanding tractive torque control in power machine 200 during side-hilling to prevent dropping downhill due to gravity force according to an embodiment. Steering inputs 360 of the power machine 200, which can be a subset of operator input devices 260 discussed with reference to FIGS. 2-3, provide steering input signals to a steering control unit 365. For example, steering inputs 360 may include a steering wheel, joystick controls, lap bars, control levers or other steering control devices. Steering control unit 365 can be a suitably configured electronic control unit, a mechanical control device or otherAttorney Docket No. B2024-0021-W01 device configured to control articulation angle actuator(s) 270 coupled to articulation joint 216, and is responsive to steering input signals from steering inputs 360, to control an angle of articulation of articulation joint 216 between front frame member 212 and rear frame member 214 when a steering or turn operation of the power machine 200 is underway. As illustrated in FIG. 7, front frame member 212 includes first or left tractive element 242A and second or right tractive element 242B and rear frame member 214 includes first or left tractive element 242C and second or right tractive element 242D.

[0046] Tractive drive system 326 includes a tractive drive control 327 coupled to power source 222 and / or power conversion system 224 (illustrated in FIG. 6). Power machine 200 further includes one or more inertial measurement unit (IMU) sensor(s) or gyroscope sensor(s) 375 coupled to tractive drive control 327. IMU sensor(s) 375 are configured to sense six degrees of movement (yaw 223, vertical translation along axis 217, roll 221, longitudinal translation along axis 215, pitch 225 and lateral translation along axis 219), and in some embodiments an acceleration, of loader 200. In combination with sensor data from IMU sensor(s) 375, tractive drive control 327 determines whether loader 200 is on a slope and the position of the loader 200 with respect to the slope.

[0047] Based on the positional determination that loader 200 is on a slope, tractive drive control 327 is configured to automatically provide varying and independent input to drive motors 226A- 226D when loader 200 is side-hilling with zero articulation. The varying and independent input depends upon which tractive elements are located downhill and which tractive elements are located uphill. In particular, tractive drive control 327 may apply independent torque control to each tractive element to independently rotate each of the tractive elements on front frame member 212 and each of the tractive elements on rear frame member 214 to prevent loader 200 from sliding down or being drawn down the slope by gravity. In order to control the relationship between the four drive motors 226A-226D while on a slope, tractive drive control 327 is configured to provide unique torque control signals to each of first drive motor 226A, second drive motor 226B, third drive motor 226C and fourth drive motor 226D. In response to these unique and independent torque control signals, the output speed of each wheel 242A, 242B, 244A and 244B is also unique and independent.

[0048] As shown in the example illustrated in FIGS. 4 and 5, when articulated loader 200 is sidehilling on slope 227, sensor data from IMU(s) 375 is indicative of which tractive elements areAttorney Docket No. B2024-0021-W01 downhill and uphill and tractive drive control 327 receives this information and outputs a torque control command to drive motors 226A and 226C to rotate downhill tractive elements 242A and 242C at a certain speed and outputs a torque control command to drive motors 226B and 226D to rotate uphill tractive elements 242B and 242D at a different speed. For example, tractive drive control 327 may apply a torque on drive motors 226A and 226C that is greater than an application of torque on drive motors 226B and 226D to therefore cause downhill tractive elements 242A and 242C to spin at a speed that is greater than the speed of uphill tractive elements 242B and 242D to counteract the effects of gravity on loader 200. In another example, tractive drive control 327 may reduce a torque being applied on drive motors 226B and 226D that is less than an application of torque on drive motors 226A and 226C to therefore cause uphill tractive elements 242B and 242D to spin at a speed that is less than the speed of downhill tractive elements 242A and 242C. In FIGS. 4 and 5, a first torque may be applied to drive motor 226A to rotate tractive element 242A at a first speed, the first torque may be applied to drive motor 226C to rotate tractive element 242C at the first speed, a second torque may be applied to drive motor 226B to rotate tractive element 242B at a second speed and the second torque may be applied to drive motor 226D to rotate tractive element 242D at the second speed. Under this embodiment, the first torque is greater than the second torque and the first speed is greater than the second speed. In another embodiment, different torques may be applied to each of the different motors, which results in different speeds of each of the tractive elements. For example, four independent torques, and four resulting independent tractive element speeds may be needed if loader 200 is moving at an angle across the slope.

[0049] FIG. 8 is a diagrammatic top view of exemplary power machine or articulated loader 200 illustrated in FIGS. 2-5. As illustrated, power source 222, which may be a battery or battery pack, is located on and supported by rear frame member 214. Rear frame member 214 also includes first or left rear tractive element 242C and second or right rear tractive element 242D and at least one rear electric drive motor, with FIG. 8 illustrating a first or left rear electric drive motor 382 configured to propel tractive element 242C and a second or right rear electric drive motor 383 configured to propel tractive element 242D. Under one embodiment, each motor 382 and 383 may be packaged together with an inverter. In other embodiments, an inverter 365 may be located proximate to power source or battery pack 222. Front frame member 212 includes a first or left front tractive element 242A and a second or right front tractive element 242B, at least one front electric drive motor, with FIG. 8 illustrating a first or left front electric drive motor 386 configuredAttorney Docket No. B2024-0021-W01 to propel tractive element 242A and a second or right front electric drive motor 387 configured to propel tractive element 242B. Under one embodiment, each motor 386 and 387 may be packaged together with an inverter. In other embodiments, inverter 365 may be located proximate to power source or battery pack 222. In one embodiment, IMU(s) 375 may be built into inverter 365 as illustrated in FIG. 8. In another embodiment, IMU(s) 375 may be located in other locations in power machine or loader 200. In alternative specific embodiments, IMU(s) may be placed on both the front and rear frame members or just the front frame member. Regardless of location, tractive drive control 327 (FIG. 7) determines that power machine or loader 200 is located on slope 227 based on sensor data from IMU(s) 375 and determines which tractive elements are located uphill and which tractive elements are located downhill.

[0050] Upon determining that power machine or loader 200 is located on slope 227 and which tractive elements are uphill, and which tractive elements are downhill, tractive drive control 327 automatically controls torque being applied to each motor 382, 383, 386 and 387 independently to counteract the effects of gravity. Tractive drive control 327 receives reports from each motor regarding its current speed in rotations per minute. To change each motor’s speed based on sensed data from IMUs 375, tractive drive control 327 sends each motor a torque input that commands each motor to rotate its respective tractive element slower or faster. For example, if first or left front tractive element 242A and first or left tractive element 242C are downhill on a slope relative to second or right front tractive element 242B and second or right rear tractive element 242D, then tractive drive control 327 may increase torque input on left front motor 386 and left rear motor 382 to spin motors 386 and 382 and therefore tractive elements 242A and 242C faster and decrease torque input on right front motor 387 and right rear motor 383 to spin motors 387 and 383 and therefore tractive elements 242B and 242D slower. If second or right front tractive element 242B and second or right rear tractive element 242D are downhill on a slope relative to first or left front tractive element 242A and first or left rear tractive element 242C, the tractive drive control 327 may increase torque input on right front motor 387 and right rear motor 383 to spin motors 387 and 383 and therefore tractive elements 242B and 242D faster and decrease torque input on left front motor 386 and left rear motor 382 to spin motors 386 and 382 and therefore tractive elements 242A and 242B slower. Such commands will automatically occur to counter the pull of gravity on power machine 200 without the operator having to provide steering inputs 360 (FIG. 7).Attorney Docket No. B2024-0021-W01

[0051] FIG. 9 is a diagrammatic top view of another embodiment of an exemplary power machine 400. As illustrated, power source 422, which may be a battery or battery pack, is located on and supported by a frame. In FIG. 9, first or left front element 442A and second or right front element 442B may be caster wheels or other type of wheels that are not a component of tractive drive system 326. In this embodiment, elements 442A and 442B are non-powered wheels that are designed to aid in mobility of power machine 400. First or left rear tractive element 442C and second or right rear tractive element 442D are powered by at least one rear electric drive motor with FIG. 9 illustrating a left rear electric drive motor 482 configured to propel tractive element 442C and a right rear electric drive motor 483 configured to propel tractive element 442D. Under one embodiment, each motor 482 and 483 may be packaged together with an inverter. In other embodiments, an inverter 465 may be located proximate to power source or battery pack 422. In one embodiment, IMU(s) 475 may be built into inverter 465 as illustrated in FIG. 9. In another embodiment, IMU(s) 475 may be located in other locations in power machine 400 such as integrated into the tractive drive control 327. Regardless of location, a tractive drive control, such as tractive drive control 327 (FIG. 7), determines that power machine 400 is located on a slope based on sensor data from IMU(s) 475.

[0052] In one experimental embodiment, a side-hilling protocol in accordance with the various embodiments presented herein may be manually activated by an operator or otherwise automatically activated based upon a determination that the power machine is operating on a slope greater than some threshold slope. In yet more specific experimental embodiments, slope alone may not be sufficient to positively indicate that a power machine is (or is likely to) slip downhill. For example, surface conditions of the slope may greatly impact whether the power machine will experience a yaw which overcomes the frictional co-efficient of the tractive elements. In such a specific experimental embodiment, a controller may require the detection of a slope above a threshold in addition to a sensed yaw above a threshold (indicative of active downhill slip) before activating a side-hilling protocol in accordance with the various embodiments present herein. A side-hilling protocol may be disabled where a sensed articulation angle suggests an operator requested down-hill trajectory.

[0053] Upon determining that power machine 400 is located on a slope and which tractive elements are uphill and which tractive elements are downhill, the tractive drive control automatically controls torque being applied to each motor 482 and 483 independently to counteractAttorney Docket No. B2024-0021-W01 the effects of gravity. The tractive drive control receives reports from each motor regarding its current speed in rotations per minute. To change each motor’s speed based on sensed data from IMUs 475, the tractive drive control sends each motor a torque input to command each motor to rotate its respective tractive element slower or faster. For example, if first or left rear tractive element 442C is downhill on a slope relative to second or right rear tractive element 442D, then the tractive drive control may increase torque input on drive motor 482 to spin tractive element 442C faster and may decrease torque input on drive motor 483 to spin tractive element 442D slower. If first or right rear tractive element 442D is downhill on a slope relative to second or left rear tractive element 442C, the tractive drive control may increase torque input on drive motor 483 to spin tractive element 442D faster and may decrease torque input on drive motor 482 to spin tractive element 442C slower. Such commands will automatically counter the pull of gravity on power machine 400 without the operator having to provide steering inputs.

[0054] FIG. 10 is a diagrammatic top view of yet another embodiment of an exemplary power machine 500. As illustrated, power source 522, which may be a battery or battery pack, is located on and supported by a frame. In FIG. 10, first or left front element 542A and second or right front element 542B are powered by at least one front electric drive motor with FIG. 10 illustrating a single drive motor 586 configured to propel tractive elements 542A and 542B, to which a mechanism 588 is coupled to motor 586 and may separately control the rotation of tractive elements 542A and 542B. First or left rear tractive element 542C and second or right rear tractive element 542D are powered by at least one rear electric drive motor with FIG. 10 illustrating a single electric drive motor 582 configured to propel tractive elements 542C and 542D, to which a mechanism 584 is coupled to motor 582 and may separately control the rotation of tractive elements 542C and 542D. For example, mechanisms 584 and 588 may be a differential, specialized brake system or hydraulic pump / motor loop. Under one embodiment, each motor 582 and 586 may be packaged together with an inverter. In other embodiments, an inverter 565 may be located proximate to power source or battery pack 522. In one embodiment, IMU(s) 575 may be built into inverter 565 as illustrated in FIG. 10. In another embodiment, IMU(s) 575 may be located in other locations in power machine 500. Regardless of location, a tractive drive control, such as tractive drive control 327 (FIG. 7), determines that power machine 500 is located on a slope based on sensor data from IMU(s) 575.Attorney Docket No. B2024-0021-W01

[0055] Upon determining that power machine 500 is located on a slope and which tractive elements are uphill and which tractive elements are downhill, the tractive drive control automatically controls torque being applied to each of motor 582 and 586 independently to counteract the effects of gravity. The tractive drive control receives reports from each motor regarding its current speed in rotations per minute. To change each motor’s speed based on sensed data from IMUs 575, the tractive drive control sends motors 582 and 586 and their corresponding mechanisms 584 and 588 a torque input to command each motor to rotate its tractive elements slower or faster. For example, if first or left rear tractive element 542C and first or left front tractive element 542A are downhill on a slope relative to second or right rear tractive element 542D and second or right front tractive element 542B, then the tractive drive control may command drive motor 582 and together with its corresponding mechanism 584 to rotate tractive element 542C faster and to rotate tractive element 542D slower and may command drive motor 586 and together with its corresponding mechanism 588 to rotate tractive element 542A faster and rotate tractive element 542B slower. If second or right rear tractive element 542D and second or right front tractive element 542B are downhill on a slope relative to first or left rear tractive element 542C and first or left front tractive element 542A, then tractive drive control may command drive motor 582 and together with its corresponding mechanism 584 to rotate tractive element 542D faster and rotate tractive element 542C slower and may command drive motor 586 and together with its corresponding mechanism 588 to rotate tractive element 542B faster and rotate tractive element 542A slower. Such commands will automatically occur to counter the pull of gravity on power machine 500 without the operator having to provide steering inputs.

[0056] Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail to the disclosed embodiments without departing from the spirit and scope of the concepts discussed herein.

Claims

Attorney Docket No. B2024-0021-W01WHAT IS CLAIMED IS:

1. A power machine comprising: a power source; a first tractive element; a second tractive element; a tractive drive system is coupled to the power source and includes at least one drive motor configured to drive the first and the second tractive elements, a tractive drive control and at least one sensor configured to sense six degrees of movement of the power machine; and wherein the tractive drive control is configured to use sensor data from the at least one sensor to determine that the power machine is located on a slope with the first tractive element being located downhill relative to the second tractive element; and wherein in response to determining that the power machine is located on the slope the tractive drive control is further configured to automatically counteract gravitational forces by applying a torque that rotates the first tractive element at a different speed from the second tractive element.

2. The power machine of claim 1, wherein the application of the torque comprises applying a first torque to rotate the first tractive element and applying a second torque to rotate the second tractive element, wherein the first torque is greater than the second torque.

3. The power machine of claim 2, wherein the first and second tractive elements comprise a first front tractive element, a second front tractive element, a first rear tractive element and a second rear tractive element and the at least one drive motor of the tractive drive system comprises a first drive motor configured to drive the first front tractive element, a second drive motor configured to drive the second front tractive element, a third drive motor configured to drive the first rear tractive element and a fourth drive motor configured to drive the second rear tractive element, wherein the first front tractive element is located downhill relative to the second front tractive element and the first rear tractive element is located downhill relative to the second rear tractive element.Attorney Docket No. B2024-0021-W014. The power machine of claim 3, wherein the tractive drive control is configured to apply the first torque to the first drive motor to rotate the first front tractive element at a first speed, is configured to apply the second torque to the second drive motor to rotate the second front tractive element at a second speed that is less than the first speed of the first front tractive element, is configured to apply the first torque to the third drive motor to rotate the first rear tractive element at the first speed and is configured to apply the second torque to the fourth drive motor to rotate the second rear tractive element at the second speed that is less than the first speed of the first rear tractive element.

5. The power machine of claim 1, wherein the first and second tractive elements comprise a first front tractive element, a second front tractive element, a first rear tractive element and a second rear tractive element and the at least one drive motor of the tractive drive system comprises a first drive motor and corresponding mechanism that drives the first and second front tractive elements and a second drive motor and corresponding mechanism that drives the first and second rear tractive elements, wherein the first front tractive element is located downhill relative to the second front tractive element and the first rear tractive element is located downhill relative to the second rear tractive element.

6. The power machine of claim 5, wherein the application of torque on the first drive motor in cooperation with the corresponding mechanism rotates the first front tractive element at a speed that is greater than the second front tractive element and wherein the application of torque on the second drive motor in cooperation with the corresponding mechanism rotates the first rear tractive element at a speed that is greater than the second rear tractive element.

7. The power machine of claim 1, wherein the first and second tractive elements comprise a first rear tractive element and a second rear tractive element and the at least one drive motor of the tractive drive system comprises a first drive motor configured to drive the first rear tractive element and a second drive motor configured to drive the second rear tractive element, wherein the first rear tractive element is located downhill relative to the second rear tractive element.Attorney Docket No. B2024-0021-W018. The power machine of claim 7, wherein the tractive drive control is configured to apply a first torque to the first drive motor to rotate the first rear tractive element at a first speed and configured to apply a second torque to the second drive motor to rotate the second rear tractive element at a second speed that is less than the first speed of the first front tractive element.

9. The power machine of claim 1, wherein the at least one sensor comprises at least one inertial mass unit (IMU) sensor.

10. A power machine comprising: a power source; a front frame member having at least a first tractive element and a second tractive element; a rear frame member having at least a first tractive element and a second tractive element; and a tractive drive system coupled to the power source and including a plurality of electric drive motors each configured to drive a corresponding first or second tractive element of the front frame member or a corresponding first or second tractive element of the rear frame member, at least one sensor configured to sense six degrees of movement of the power machine and a tractive drive control coupled to the sensor, wherein based on sensed data from the sensor the tractive drive control is configured to counteract the effects of gravity on the power machine while on a slope by commanding control signals to each of the plurality of electric drive motors to independently actuate each of the first and second tractive elements on the front and rear frame members.

11. The power machine of claim 10, wherein when the tractive drive control determines that the first tractive element of the front frame member is located downhill of the second tractive element of the front frame member, then a command is sent to the first electric drive motor that is coupled to the first tractive element of the front frame member to apply a first torque to the first electric drive motor that is different from a second torque being applied to the second electric drive motor that is coupled to the second tractive member of the front frame member.Attorney Docket No. B2024-0021-W0112. The power machine of claim 11 , wherein the command sent to the first electric drive motor that is coupled to the first tractive element of the front frame member comprises a command to apply a first torque to the first electric drive motor that is greater than a second torque being applied to the second electric drive motor that is coupled to the second tractive member of the front frame member.

13. The power machine of claim 11, wherein when the tractive drive control determines that the first tractive element of the rear frame member is located downhill of the second tractive element of the rear frame member, then a command is sent to apply a first torque to the third electric drive motor that is coupled to the first tractive element of the rear frame member and a command is sent to apply a second torque to the fourth electric drive motor that is different from the first torque.

14. The power machine of claim 13, wherein the first torque is greater than the second torque.

15. A method of counteracting effects of gravity on a power machine located on a slope, the method comprising: providing power to a plurality of electric drive motors each configured to drive a corresponding first or second tractive element of the front frame member or a corresponding first or second tractive element of the rear frame member; sensing six degrees of movement of the power machine to determine that the first tractive element on the front frame member is located downhill from the second tractive element on the front frame member and the first tractive element on the rear frame member is located downhill from the second tractive element on the rear frame member; and commanding control signals to each of a plurality of electric drive motors to drive a corresponding first tractive element or second tractive element of the front frame member or a corresponding first tractive element or second tractive element of the rear frame member based on the sensed data from the sensor to independently rotate each of the first and second tractive elements on the front frame member and first and second tractive elements on the rear frame member.Attorney Docket No. B2024-0021-W0116. The method of claim 15, wherein commanding control signals to independently rotate each of the first and second tractive elements on the front frame member and first and second tractive elements on the rear frame member comprises sending a command to apply a first torque on the first electric drive motor that is coupled to the first tractive element on the front frame member that is different from a second torque being applied on the second electric drive motor that is coupled to the second tractive member of the front frame member.

17. The power machine of claim 16, wherein the first torque is greater than the second torque.

18. The power machine of claim 15, wherein commanding control signals to independently rotate each of the first and second tractive elements on the front frame member and first and second tractive elements on the rear frame member comprises sending a command to apply a first torque on the third electric drive motor that is coupled to the first tractive element of the rear frame member that is different from a second torque being applied to the fourth drive motor that is coupled to second tractive element of the rear frame member.

19. The power machine of claim 18, wherein the first torque is greater than the second torque.

20. The method of claim 15, wherein sensing six degrees of movement of the power machine comprises using a gyroscope sensor coupled to a tractive drive control.

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