WO2025264593A1 - Tire pressure monitoring for tractive operations - Google Patents

Abstract

The disclosed technology provides systems and methods for power machines, including electrically powered and other mowers. A control system 260 can receive pressure data for ground-engaging elements 242 and a travel command corresponding to a tractive operation with the ground-engaging elements 242. In response to receiving the travel command and determining that the pressure data satisfies the first pressure criterion, the tractive operation can be controlled based on the travel command and the pressure data.

Description

TIRE PRESSURE MONITORING FOR TRACTIVE OPERATIONS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States provisional application no. 63/660,617, filed 17 June 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 related to power machines for mowing operations, including zero-radius turn mowers, that are configured to operate in whole or in part under electrical power. 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 are generally self-propelled vehicles that have a work device that can be operated to perform a work function. For example, mowers can include a mower deck with one or more rotatable blades that can be operated to cut grass, brush, or other material as the mower travels over terrain. Other work vehicles include loaders (including mini-loaders), excavators, utility vehicles, tractors (including compact tractors), and trenchers, to name a few examples.

[0003] Conventional power machines can include hydraulic or mechanical systems that are configured to transmit power from a power source (e.g., an internal combustion engine) to perform various work or tractive functions. For example, a power source can be configured to provide tractive power for moving a power machine along a support surface, as well as powering various work implements (e.g., to rotate a blade). Still, other power machines can include an electrical power source (e.g., a battery, a capacitor, etc.) configured to provide electrical power to perform work or tractive functions, for example, by driving an electric motor or operating an electrical actuator.

[0004] 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

[0005] Examples of the presently disclosed technology can provide improvements for power machines, including mower and other power machines that operate with pressurized tractive elements (e.g., pneumatic tires). [0006] According to some aspects of the disclosure, a method of controlling a power machine is provided. Pressure data for a first tire and a second tire of first and second tractive elements can be received. A travel command corresponding to a tractive operation with the first tractive element and the second tractive element can be received. Whether the pressure data satisfies a first pressure criterion relative to the first tire and the second tire can be determined. In response to receiving the travel command and determining that the pressure data satisfies the first pressure criterion, the tractive operation can be controlled based on the travel command and the pressure data.

[0007] According to some aspects of the disclosure, a power machine can include a frame, a power source supported by the frame, a first tractive element including a first tire supported on a first side of the frame and configured to rotate under power from the power source, and a second tractive element including a second tire supported on a second side of the frame opposite the first side of the frame and configured to rotate under power from the power source. One or more pressure sensors can be configured to determine pressure data for the first and second tires. A control system can be configured to: receive the pressure data for the first and second tires; receive a travel command corresponding to a tractive operation with the first and second tractive elements; and command rotation of one or more of the first or second tractive elements for the tractive operation based on the travel command and the pressure data.

[0008] This Summary and the Abstract are provided to introduce a selection of concepts in a simplified form that are further described below. 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.

DRAWINGS

[0009] FIG. 1 is a block diagram illustrating functional systems of an example power machine according to an example of the disclosed technology.

[0010] FIG. 2 is a perspective view of an example implementation of the power machine of FIG. 1. in the form of a zero-radius turn mower.

[0011] FIG. 3 is a flowchart illustrating a method of controlling a pow er machine, according to an example of the disclosed technology, including the mower of FIG. 2. DESCRIPTION

[0012] 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 carried out in various other ways. The terminology' in this document is used for the purpose of description and should not be regarded as limiting. Words 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.

[0013] In some examples, power machines can include pressurized tractive elements (e.g., pneumatic tires) that can engage the ground or other support surface for tractive operations. For example, tires can be rotated by corresponding hydrostatic or electric motors to cause the power machines to travel forward or backwards over terrain, including with straight-line or turning travel according to corresponding input commands (e.g., as received from on-board operator interfaces).

[0014] In this regard, changes in pressure of tractive elements can result in changes in the performance of a power machine during tractive operations. For example, increase or decrease of tire pressure can change the characteristics with which the tires engage with the ground (e.g., contact area, rolling resistance, etc.). Further, for tires of the same nominal diameter, pressure changes that result in non-zero pressure differential between a first tire and a second tire can cause different ground-engaging characteristics of the first tire as compared to the second tire. In some cases, this difference in diameter can be detrimental to execution of intended tractive operations. For example, in a skid steer power machine, an elevated pressure in a right tire as compared to a left tire (or vice versa) can result in a larger actual diameter of the right tire as compared to the left tire (or vice versa). Correspondingly, in conventional systems, providing a given rotational speed to both tires can result in the right tire exhibiting a larger groundengaging speed than the left tire (or vice versa). More specifically, both wheels may exhibit the same rotations-per-minute but the tire with higher internal pressure may have a larger diameter and therefore travel a further linear distance. For commanded straight-line travel, for example, this discrepancy in ground-engaging speed can result in turning travel for the power machine, rather than the intended straight-line travel. Similarly, commanded differences in rotational speed for turning operations may not result in the intended turning performance. For example, the power machine may over- or under-steer relative to an operator command. depending on the direction of the intended turn and the relative pressurization of the tires. Where rotational speeds of the wheels are not directly controlled by the system (or otherwise an input to a control feedback loop), the less inflated tire may have a larger contact patch and experience larger rolling resistance. As a result, the performance of the tractive elements may be reduced (e.g.. acceleration, velocity for a given operator commanded input).

[0015] Examples of the disclosed technology can address these and other issues by selectively modifying tractive operations based on pressure data for corresponding tractive elements. In particular, in some implementations, a control system can detect pressure data relative to a first and second tractive element of a power machine (e.g., a zero-radius turn mower or other skid steer power machine) and then selectively adjust a commanded rotational speed (or other command input to the tractive drive) for one or both of the tires based on the pressure data.

[0016] In this regard, commands for tractive elements can include direct commands of rotational speed or can include indirect commands for rotational speed or other rotational parameters. Relative to direct commands, for example, some implementations can provide current signals or other commands that cause an electric drive motor or other powered tractive device to rotate at a desired rotational speed. Such a command can thus cause a tire that is powered by the electric drive motor (or other device) to rotate at a particular rotational speed (e.g.. the commanded speed or a different speed, as may result from an intervening gearbox or other known speed adjustment device). Relative to indirect commands, for example, some implementations can provide an electronic or hydraulic signal to adjust a displacement of a hydrostatic motor or hydrostatic pump (e.g., via movement of a swash plate), with corresponding adjustments to rotational speed of the motor or pump. Such a command can thus also cause a corresponding tire to rotate at a particular rotational speed.

[0017] For example, sensor data during operation of a power machine may indicate that a pressure of a first ground-engaging element (e.g., right-side) tire is larger than a pressure of a second (e.g., left-side) tire, as may correspond to the first tire exhibiting a larger actual diameter than the second tire. Correspondingly, upon receiving a travel command that corresponds to a particular rotational speed (or speeds) at the first and second tires, a rotational speed actually commanded for the first tire (e.g., at a first drive motor) may be actively reduced relative the particular rotational speed for the first tire that corresponds to the travel command (i.e., relative to a speed that would normally correspond to the tractive operation indicated by the travel command). Or, similarly, a rotational speed commanded for the second tire may be increased relative to the particular rotational speed for the second tire that corresponds to the travel command. As noted above, such a modification in speed can be achieved via a direct command for a modified rotational speed (e.g., of an electric motor) or via an indirect command for a modified rotational speed (e.g., a command for a corresponding adjustment of a swash plate of a hydrostatic pump or motor).

[0018] Thus, for example, if an operator commands a straight-line travel corresponding to a default of equal rotational speed for both tires, tractive actuators for the tires (e g., electric motors or hydrostatic pumps/motors, etc.) can be controlled to provide a different rotational speed for one tire as compared to the other tire to achieve the operator desired straight-line travel. Similarly, if an operator commands turning travel corresponding to a particular difference in rotational speeds for the tires, tractive actuators for the tires can be controlled to provide a modified difference in rotational speeds for the tires which achieves the operator commanded turning radius/travel.

[0019] Although examples herein focus particularly on mowers - e.g.. zero-radius turn mowers with pneumatic tires - implementations of the disclosed technology can be practiced on a variety of power machines with a variety of ground-engaging elements. In this regard, FIG. 1 is a block diagram that illustrates the basic systems of a power machine 100, which can be any of a number of different types of power machines and upon which the embodiments discussed below can be advantageously incorporated. The block diagram of FIG. 1 identifies various systems on power machine 100 and the relationship between various components and systems. In particular, the power machine 100 has a frame 110, a power source 120, a workgroup work element 130 and tractive work elements 140. The workgroup work element 130 can be operated to perform work tasks (e.g., mowing, digging, cutting, grading, etc.) and the tractive work elements 140 can be operated move the power machine over a support surface. In the illustrated example, the power machine 100 also includes an operator station 150 that provides an operating position for controlling the work elements of the power machine. In some examples, however, no operator station may be included.

[0020] A control system 160 is provided to interact with other systems of the power machine 100 to perform various tasks, including in response to control signals provided by an operator. For example, the control system 160 can be an integrated or distributed architecture of one or more controllers (e.g., one or more processor devices and one or more memories) that are collectively configured to receive operator input or other input signals (e.g.. sensor data) and to output commands accordingly for power machine operations (e.g., workgroup operations, tractive operations, etc.). [0021] Some power machines have work elements that can perform a dedicated task. For example, some power machines include a mower deck that can be attached to a main frame of the work vehicles in various ways (e.g., with a fixed mount, as an implement attached to a lift arm, etc.). Cutting elements of the mower deck can be controlled as needed. For example, the control system 160 can control the speed of one or more rotating blades, or a position of the mower deck relative to the frame, or the mower deck can be otherwise manipulated to perform mowing or other tasks.

[0022] Some power machines can include other dedicated work elements, including cutting or drilling implements, buckets, grading blades, and others as variously known in the art. In some cases, work elements can be interchanged on a particular power machine (e.g., as attachable implements that can be supported by a lift arm, or otherwise). In this regard, for example, the power machine 100 as illustrated includes an implement interface 170, which provides a connection between the frame 110 or the work element 130 and an attachable implement. In some cases, the implement interface 170 can be a direct connection to secure an implement directly to the frame 110 or to the work element 130 (e.g., can be a pinned connection directly to a lift arm). In some cases, the implement interface 170 can include a linkage or other support structure, or can be formed as an implement carrier (e.g.. which may be configured to secure and support various implements, and may itself be controllably movable relative to the frame 1 10 or the work element 130). In some examples, the implement interface 170 can be a pinned or other connection that secures a mower deck to a movable support structure, so that the mower deck can be supported at selected heights relative to the frame 110 (and the ground).

[0023] In some example, the frame 110 can be rigid (e.g., formed from a single member, a w eldment, or other unified structure). In some examples, at least one portion of the frame 110 may be movable relative to another. For example, excavators can have an upper frame portion that rotates with respect to a lower frame portion, and some power machines can include articulated frames that are pivotable about one or more vertical (or other) axes. Articulated frames, for example, can be used to implement steering operations, provide improved following of terrain, or otherwise.

[0024] The frame 110 supports the power source 120, which can provide power to the work element 130 or the tractive elements 140. In some cases, the power source 120 can provide power for use by an implement attached at the implement interface 170. In some examples, power from the power source 120 can be provided directly to the work element 130, the tractive elements 140, or implement interfaces 170 (e.g., via direct mechanical or electrical connection). In some examples, power from the power source can be provided indirectly to the work element 130, the tractive elements 140, or the implement interfaces 170 (e.g., may be transferred via hydraulic operations, or a combination of electrical and hydraulic operations). In some examples, the control system 160 can control routing of power from the power source 120 to other systems (e.g., via a system of electronic, hydraulic, electro-hydraulic, or other control devices, including as generally known in the art).

[0025] In some examples, the power source 120 can include an engine (e.g., an internal combustion engine). In some examples, the power source 120 can include an electrical power source (e.g., a battery, a capacitor, a fuel cell. etc.). In some examples, hybrid power sources can be provided (e.g., with a combination of an engine and an electrical power source). In some examples, a power conversion system can be provided to convert power from the power source 120 into other forms useable by the work element 130, the tractive elements 140, or an implement at the implement interface 170. For example, a hydraulic system can be used to convert rotational output from the power source 120 into hydraulic power (e.g., to power hydrostatic or other operations). Similarly, an electrical system can be used to convert electrical output from the power source 120 into non-electrical power (e.g., rotational mechanical pow er, or hydraulic power via a coupled hydraulic system).

[0026] For simplicity of presentation, FIG. 1 shows simple the work element 130, but various examples can include various numbers of work elements. In some examples, as also discussed above, work elements can include mow er decks or other similar equipment. In some examples, work elements can include lift arm assemblies or other similar systems. The tractive elements 140 are a special case of work elements and may be provided in various number and configuration. In some examples, tractive elements can be arranged and controllable for independent operation and can be steerable in some cases. In some examples, one or more tractive elements on a first side of the power machine 100 may be separately controllable from one or more tractive elements on a second side of the power machine 100 (e.g., controllable for rotation in opposite directions for “skid steer” operation). Tractive elements can be. for example, wheels attached to an axle, track assemblies, or other assemblies of known configurations to convey tractive power from the frame 110 to a supporting surface.

[0027] In some examples, the tractive elements 140 can be rigidly mounted to the frame 110 so as to be limited to rotation about one or more corresponding axles. In some examples, the tractive elements 140 can be pivotally mounted to the frame 110. In some power machines, including zero-radius turn mowers, one or more caster wheels or similar devices can be used in combination with rigidly mounted tractive elements, with the rigidly mounted tractive elements provide tractive power and allowing the power machine to be steered via implementation of different ground-engaging speeds at tractive elements on opposing sides of the power machine. Such an arrangement is referred to herein as a zero-radius turn configuration and can in particular be implemented on mowers, as further discussed below.

[0028] In some power machines, the operator station 150 is defined by an enclosed or partially enclosed cab. In some examples, the operation station 150 can include a standing or other platform (e.g., without overhead enclosure). In some example, the operator station 150 can be a remote station (e.g., as provided by a remote control device not attached to the frame 110). In some examples, the operator station 150 can be supported by the frame 110 by accessible by operators that are not (e.g., by an operator walking behind the power machine 100).

[0029] FIG. 2 illustrates a mower 200, which is one particular example of the power machine 100 FIG. 1. Correspondingly, features of the mower 200 described include reference numbers that are generally similar to those used in FIG. 1 and discussion above of similarly named or numbered components also applies to the mower 200, unless otherwise indicated. For example, the mower 200 includes a frame 210, just as power machine 100 has the frame 110.

[0030] The mower 200 is shown as a zero-radius turn riding mower, but it could also be a differently configured riding mower, or a walk-behind or push-type mower. In particular, a zero-radius turn mower can be capable of executing a turn with a turn radius of zero (i.e., the mower can be capable of rotating about a vertical axis through the machine to execute up to a 360 degree turn). However, some turns may be performed with a non-zero turn radius and some similarly configured mowers (or other power machines) may not be capable of fully zero-radius turns.

[0031] In the illustrated configuration of the mower 200, the frame 210 supports a power system 220 that can generate or otherwise provide power for operating various functions on the power machine. The frame 210 also supports a work element in the form of a mower deck 230 that is powered by the power system 220 and that can perform various work tasks (e.g.. cutting at different blade speeds or deck heights). The frame 210 also supports atractive system 240, which is also powered by a power system 220 and can propel the power machine over a support surface. In particular, in the illustrated example, the tractive system 240 includes powered wheels with tires 242A. 242B, as further discussed below, as well as un-powered casters 242C, 242D, which are capable of rotation about a vertical or substantially vertical axis to assist with steering of the mow er. The casters 242C, 242D can rotate in response to uneven application of power to the tires 242A, 242B (in terms of magnitude or direction) or other factors, to allow the mow er to turn w ithout skidding without the casters 242C, 242D necessarily being actively controlled.

[0032] A deck support assembly 232 supports the deck 230 relative to the frame 210 and can be configured for selective adjustment to provide different cutting heights, angles, etc. for the deck 230, as well as for selective removal of the deck 230 or installation of additional or alternative work elements (e.g., other mow er decks, ducts, and other material handling devices for cut plant material, etc.). The deck 230 can include one or more rotatable blades (not shown), which can be controlled (e.g., collectively or individually) to cut grass or other material, and which can be powered by hydraulic, electronic, or mechanical connections to the power system 220.

[0033] As a riding lawn mower, the mower 200 includes an operator station 255 supported on the frame 210. from which an operator can manipulate various control devices to cause the mower 200 to perform various work functions. In the illustrated example, in particular, the operator station 250 includes an operator seat 258, as w ell as the various operation input devices 262 in communication with a control system 260 (e.g., a hydraulic control system, or an electronic control system including an electronic hub controller and other distributed controllers that are electronically in communication with the hub controller). The input devices 262 generally allow an operator to control tractive and workgroup operations, so that the mower 200 can be directed to move over terrain and selectively cut grass or other plants along the terrain (or otherwise executed desired work operations).

[0034] In some case, the input devices 262 can allow for tractive control of the mower 200. For example, the input devices 262 can include left- and right-side control levers 264, 266 (e.g., “lap bars”, as shown) that can be independently moved by an operator to direct, respectively, rotation of left- and right-side drive actuators 226 A, 226B for independent commanded rotation of left- and right-side tractive elements (e.g., the tires 242A, 242B, as shown). In some cases, the levers 264. 266 can directly control delivery of hydraulic or other power. In some cases, the levers 264, 266 can indirectly control power delivery, including by adjusting a pilot flow for a powered hydraulic system of the mower 200 or by providing electronic signals that direct control of hydraulic, electronic, or other power delivery systems by way of one or more intervening hydraulic or electronic controllers included in the control system 260.

[0035] In some examples, other configurations are possible for operator input devices, including configurations with different types of control levers that an operator can manipulate to control various machine functions. In some configurations, the operator input devices 262 can include a joystick (e.g., only a single electronic joystick for tractive operations), a steering wheel, buttons, switches, levers, sliders, pedals and the like, which can be stand-alone devices (e.g., hand operated levers or foot pedals), or can be incorporated into hand grips or display panels. In some cases, one or more of the input devices can include programmable input devices.

[0036] As generally noted above, actuation of operator input devices can generate signals in the form of electrical signals, hydraulic signals, mechanical signals, or a combination thereof. 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. Functions that can be controlled via operator input devices on the mower 200 can include operational functions of the tractive system 240, the mower deck 230, other implements (not shown) including various other attachments (not shown), or a combination thereof.

[0037] In some cases, the control system 260 can be configured to operate without input from operator input devices 262 for one or more operations. For example, the control system 260 can be configured for automatic or autonomous control of certain operations of the mower 200 or can include wireless communication capabilities so as to receive control commands or other relevant data from remotely located (i.e., not mechanically tethered) and other systems, as described in greater detail below. Correspondingly, unless otherwise indicated, discussion herein of operator commands or inputs can indicate commands or inputs from an automatic or autonomous system in some cases.

[0038] Mowers can sometimes include other human-machine interfaces, including display devices (not shown) that are provided in the operator station 255 to give indications of information relatable to the operation of the power machines in a form that can be sensed by an operator (e.g., audial or visual indications). Audial indications can include buzzers, bells, and the like or verbal communication. Visual indications can include graphs, lights, displays of color(s). icons, gauges, alphanumeric characters, and the like. Displays can be dedicated to providing dedicated indications, including warning lights or gauges, or can dynamically provide information (e.g., via programmable display devices such as monitors of various sizes and capabilities). Thus, display devices can generally provide diagnostic information, troubleshooting information, instructional information, and various other A pes of information that assists an operator with operation of the pow er machine or an implement coupled to the powder machine. [0039] The power system 220 generally includes one or more power sources that can generate or otherwise provide power for operating various machine functions. For example, the power system 220 can include an internal combustion engine, an electric generator, rechargeable or replaceable batteries, capacitors, fuel cells, or various other power sources or combinations thereof. The power source(s) of the power system 220 can be operatively coupled to one or more actuators that can thus be powered for tractive, workgroup, or other operations.

[0040] In particular, in the illustrated example, the power source(s) of the power system 220 can be operatively coupled to tractive actuators 226A, 226B that can power rotational movement of the tires 242A, 242B, respectively. In a hydraulically powered example, the tractive actuators 226A, 226B can be hydrostatic motors that are hydraulically coupled to corresponding hydrostatic drive pumps (not shown) that are powered by the power source(s) of the power system 220. In an electrically powered example, the tractive actuators 226 A, 226B can be electric motors that are electrically coupled to corresponding motor drives (not shown) that are powered by the power source(s) of the power system 220. The control system 260 may correspondingly be configured to control operation of the tractive actuators 226A, 226B based on operator input (e.g., via control of corresponding hydrostatic drive pumps or motor drives, or as otherwise generally known in the art). In some examples, additional actuators can be included and can be similarly controllable (e.g., an implement pump or motor to power operation of the mower deck 230, etc ).

[0041] In the illustrated example, the mow er 200 also includes a pressure monitoring system, which can generally include one or more pressure sensors 268 configured to sense pressure data for the tires 242A, 242B and communicate the pressure data to the control system 260 (e.g., to a hub controller of the control system 260). Generally, such sensors can detect pressure directly or indirectly and can correspondingly be configured as pressure transducers, as strain gauges, or in various other configurations as known in the art for detecting pressure in a tire or other tractive element. In some cases, the sensors 268 can be configured to measure pressure directly, e.g., with a particular measured pressure corresponding to a particular current or voltage output of the relevant sensor. In some cases, the sensors 268 can be configured to measure pressure indirectly, e.g., with a particular current or voltage output of the relevant sensor corresponding to anon-pressure value that correlates to pressure. In different examples, the sensors 268 can be integrated into the tires 242A, 242B. can be external to the tires, or can be implemented in various combinations thereof. For example, some sensors can be mounted on an outer diameter of a wheel assembly. [0042] In some examples, one or more of the sensors 268 can be configured to independently measure pressure of each of the tires 242A, 242B. Correspondingly, the control system 260 may in some cases receive a first pressure data signal corresponding to pressure in the tire 242A and a second pressure data signal corresponding to pressure in the tire 242B. In some examples, one or more of the sensors 268 can be configured to measure a pressure difference between the tires 242A, 242B. Correspondingly, the control system 260 may in some cases receive a pressure data signal that corresponds to a pressure difference between the tires 242A, 242B (e.g., without receiving individual pressure data for each of the tires 242A, 242B respectively). In some cases, pressure-compensated control (e.g., as further detailed below) can be implemented based on a pressure differential that is calculated in response to receiving individual pressure data for each of the tires 242 A, 242B.

[0043] As noted above, in conventional arrangements, a difference in pressures between the tires 242A, 242B may sometimes result in tractive performance that does not actually correspond to a travel command from an operator. For example, a straight-line travel command may result in non-straight travel if a pressure difference results in different actual diameters of the tires 242A, 242B and the actuators 226A, 226B are nonetheless commanded to provide the same rotational speed.

[0044] In this regard, for example, the control system 260 can be configured to selectively modify actual commands for rotation of the actuators 226A, 226B based on a received travel command (e.g., from the levers 264, 266) and based on pressure data (e.g., received from one or more of the sensors 268). For example, upon detecting that pressure in the tire 242A is higher than the pressure in the tire 242B. the control system 260 may reduce a rotational speed commanded for the actuator 226A as compared to an unmodified rotational speed that would otherwise correspond to a particular operator command for a tractive operation with the tire 242A, absent the noted adjustment (e.g., via corresponding modifications to a motor drive signal or adjustment of a displacement of a relevant hydrostatic pump or motor). Or the control system 260 may increase a rotational speed commanded for the actuator 226B as compared to a rotational speed that would otherwise correspond to a particular operator command for a tractive operations with the tire 242B, absent the noted adjustment (e.g., via corresponding modifications to a motor drive signal or adjustment of a displacement of a relevant hydrostatic pump or motor). Thus, for example, although the increased (relative) pressure in the tire 242A may result in a larger diameter of the tire 242A than the tire 242B, the mower 200 may still travel as expected relative to the particular operator command (e.g., may maintain straight-line travel as commanded by the operator, or may turn with a turn radius that corresponds to the operator command). Further, in some cases, similar adjustments can be made relative to automatic or autonomous operation (e.g., to automatically adjust rotational speeds of the tires 242A, 242B during automatic operations to maintain straight-line travel while traversing a slope or other varied-elevation terrain).

[0045] In some implementations, the operations generally presented above may thus result in the one or more of the actuators 226A, 226B being controlled to rotate a different speed than a speed that corresponds to a similar tractive operation absent pressure compensation. For example, whereas an operator command for straight-line travel may generally correspond to operation of the actuators 226A, 226B at the same speed, pressure-compensated operation for straight-line travel may result in operation of the actuators 226 A, 226B at different speeds.

[0046] In some examples, implementation of pressure-compensated tractive operations maybe selectively activated based on operator input. For example, a button or other input device included in the input devices 262 can be actuated by an operator to turn on a pressure compensation mode, and modification of travel commands to compensate for pressure differences between the tires 242A, 242B can then proceed accordingly. In some examples, a pressure compensation mode can be implemented as a default, or can be implemented automatically based on various conditions (e.g.. upon detecting that a pressure difference between the tires 242A, 242B exceeds a particular threshold).

[0047] In some examples, pressure-compensated tractive control as generally presented above can be executed as a computer-implemented method (e.g., can be stored as a set of instructions in a memory or other non-transitory computer readable media that can cause a processor device to control tractive operations accordingly). In this regard, for example, FIG. 3 illustrates an example computer-implemented method 300, with various blocks implementable by one or more electronic controllers.

[0048] At block 310, the method 300 can include receiving pressure data. For example, as generally discussed above, pressure data can be received for a first tire and a second tire, including as pressure data for the individual tires, or as a pressure differential. In particular, use of pressure differential can allow for pressure-compensated tractive control that is independent of tire model or loading, although other approaches are also possible.

[0049] At block 320, the method 300 can include receiving a travel command. For example, one or more travel commands can be received from an operator input device or an automatic/autonomous control system. Generally, the travel command(s) can correspond to a particular tractive operation with the first tire and the second tire, variously including straight- line or turning travel at various speeds (e.g., including one or more skid steer turning operations, with the tires rotating in different directions).

[0050] At block 330, the method 300 can include determining whether the pressure data satisfies particular pressure criterion (or criteria), e.g., relative to the first tire and the second tire. For example, a first pressure criterion may be whether a pressure differential between the first tire and the second tire (e.g., an absolute value of the pressure differential) exceeds a particular zero or non-zero threshold. As another example a second pressure criterion may include whether a pressure differential between the first tire and the second tire exceeds a nonzero threshold that is larger than the threshold of the first criterion. In some cases, a default operational state may correspond to the pressure data not satisfying the first pressure criterion or the second pressure criterion, or may correspond to the pressure data satisfying a default pressure criterion different from the first or second pressure criterion (e.g., the pressure differential being zero or below a particular non-zero threshold).

[0051] At block 340, in response to receiving the travel command (e.g., at block 320) and determining that the pressure data satisfies the first pressure criterion (e.g., at block 330), a tractive operation can be controlled based on the travel command and the pressure data. For example as detailed above, a rotational speed commanded for one or more of the tires may be modified to be greater or less than a rotational speed that would otherwise correspond to the particular received travel command. In other words, if the pressure data satisfies the first pressure criterion, a corrected (pressure-compensated) rotational speed can be commanded for the one or more of the first tire or the second tire, based on the travel command and the pressure data (e.g., with the corrected speed being different than a commanded speed that would otherwise correspond to the travel command). Correspondingly, a turning command from an operator can result in a modified turning command for the relevant tractive actuator(s), or a straight-line travel command from an operator can result in a modified straight-line travel command for the relevant tractive actuator(s) (e.g., with the latter potentially corresponding to a command for different rotational speeds at left- and right-side tractive motors for straight- line travel).

[0052] In some examples, controlling tractive operations based on pressure data may include determining a corrected ground engagement factor for the one or more of the first tire or the second tire, based on the pressure data. For example, a corrected rolling resistance or corrected area of ground contact can be determined based on an individual or differential pressure, as may correspond to a pressure-driven change in diameter of one or more of the tires. Modified control of tractive operations can then be implemented accordingly.

[0053] In some cases, parameters of tire operation (e.g., ground engagement, rolling distance for a particular rotational speed, etc.) can be determined using interpolation between data points (e.g.. as saved in a look-up table). For example, pressure data may be correlated to a particular parameter in discrete intervals (e.g., intervals with a uniform size of 2 psi). Correspondingly, a tire parameter for a particular determined pressure that falls within a particular interval can be determined based on interpolation (e.g., linear interpolation) between pre-determined (e.g., look-up table) parameter values at the end points of the interval.

[0054] At block 350, in response to determining that the pressure data satisfies the second pressure criterion (e.g., at block 330), one or more remedial actions can be taken. For example, upon determining that a pressure differential between tires or an individual pressure at one or more tires exceeds a maximum threshold, operations at block 350 may include alerting an operator to an over-pressure status, stopping tractive operations of the power machine, stopping operation of the method 300 to adjust commands for tractive operations (e.g., ceasing to control tractive operations according to block 340), or stopping other operations of the power machine (e.g., operation of a mowing deck). In some cases, other remedial actions can also (or alternatively) be implemented, including derating of tractive power (e.g., to prevent travel above a particular ground-speed threshold, with corresponding pressure-compensated limits on rotational speeds of the respective tires). In some implementations, operations at blocks 340 and 350 can be implemented in series or in parallel. For example, upon determining that a pressure differential exceeds a first threshold and a second threshold, a control system can control tractive operations based on a travel command and pressure data (e.g., at block 340) and can also alert an operator or implement other remedial action (e.g., at block 350).

[0055] In some cases, control of tractive operations may proceed without modification of travel commands based on pressure. For example, at block 360, in response to receiving the travel command (e.g., at block 320) and determining that the pressure data does not satisfy the first pressure criterion (e.g., at block 330) or the second pressure criterion (e g., at block 350), a tractive operation can be controlled based on the travel command and not based on the pressure data.

[0056] In some cases, a modified actuator speed during pressure-compensated operation can be calculated in real time during operation of the relevant power machine. For example, upon detecting a particular pressure or pressure differential, a control system can calculate a corresponding effect on tire diameter and then determine a corrected (pressure-compensated) speed command accordingly. In some examples, although a pressure-compensated speed command may correlate to a particular change in tire diameter, an actual diameter or change in diameter may not necessarily be calculated by an on-board (or other) controller. For example, some implementations can include look-up tables or predetermined correlation equations that can be stored in memory. As such, for example, in response to receipt of pressure data indicating a particular pressure or pressure differential, a corrected speed for one or more tractive actuators can be determined by identifying a particular speed or speed correction on a stored table that corresponds to the particular pressure or pressure differential, or by calculating a particular speed or speed correction from a stored correlation equation based on the particular pressure or pressure differential.

[0057] Thus, improved systems and methods for tractive operations with a power machine are provided. For example, as also detailed above, a control system can be configured to evaluate pressure for one or more tractive elements (e.g., tires) and then selectively control tractive operations based on the pressure data and based on a corresponding travel command.

[0058] As used herein, unless otherwise limited or defined, “or” indicates a non-exclusive list of components or operations that can be present in any variety of combinations, rather than an exclusive list of components that can be present only as alternatives to each other. For example, a list of “A, B, or C” indicates options of: A; B; C; A and B; A and C; B and C; and A, B, and C. Correspondingly, the term “or” as used herein is intended to indicate exclusive alternatives only when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” For example, a list of “one of A, B, or C” indicates options of: A, but not B and C; B, but not A and C; and C, but not A and B. A list preceded by “one or more” (and variations thereon) and including “or” to separate listed elements indicates options of one or more of any or all of the listed elements. For example, the phrases “one or more of A, B, or C” and “at least one of A, B, or C” indicate options of: one or more A; one or more B; one or more C; one or more A and one or more B; one or more B and one or more C: one or more A and one or more C; and one or more of A, one or more of B, and one or more of C. Similarly, a list preceded by “a plurality of’ (and variations thereon) and including “or” to separate listed elements indicates options of multiple instances of any or all of the listed elements. For example, the phrases “a plurality of A. B, or C” and “two or more of A, B, or C” indicate options of: A and B; B and C; A and C; and A, B, and C. [0059] Also as used herein, unless otherwise limited or defined, “substantially parallel” indicates a direction that is within ± 12 degrees of a reference direction (e.g., within ± 6 degrees or ± 3 degrees), inclusive. Similarly, unless otherwise limited or defined, “substantially perpendicular” similarly indicates a direction that is within ± 12 degrees of perpendicular a reference direction (e.g., within ± 6 degrees or ± 3 degrees), inclusive. Correspondingly, “substantially vertical” indicates a direction that is substantially parallel to the vertical direction, as defined relative to the reference system (e.g., a local direction of gravity, by default), with a similarly derived meaning for “substantially horizontal” (relative to the horizontal direction). Discussion of directions “transverse” to a reference direction indicate directions that are not substantially parallel to the reference direction. Correspondingly, some transverse directions may be perpendicular or substantially perpendicular to the relevant reference direction.

[0060] Also as used herein, unless otherwise expressly limited or defined, the term “automatic operations” refers to operations that are at least partly dependent on electronic application of computer algorithms for decision-making without human intervention. In this regard, unless otherwise expressly limited or defined, “automatic travel” refers to travel of a power machine or other vehicle in which at least some decisions regarding steering, speed, distance, or other travel parameters are made without direct intervention by a human operator. Relatedly, the term “automated operations” (and the like), unless otherwise expressly limited or defined, refers to a subset of automatic operations for which no intervention by a human operator is required. For example, automated travel can refer to automatic travel of a power machine or other vehicle during which steering, speed, distance, or other travel parameters are determined in real time without operator input. In this regard, however, operator input may sometimes be received to start, stop, interrupt, or define parameters (e.g., top speed) for automated travel or other automated operations.

[0061] Also as used herein in the context of power machines, unless otherwise defined or limited, “tractive” or “drive” designate actuators and other work elements of a power machine that can be powered by a power source to cause movement of the power machine over terrain (e.g., wheeled or tracked ground-engaging elements, motors configured to power groundengaging elements, and related assemblies). In contrast, “workgroup” is used to refer to actuators or other work elements of a power machine associated with powered operation of work elements that are not configured to provide powered travel over terrain (e.g., lift arm structures, attached implements, motors or other actuators to power movement of lift arm structures or attached implements, auxiliary power take-off interfaces, and related assemblies). Thus, tractive (or drive) actuators are arranged to power travel of a power machine whereas workgroup actuators are arranged to power non-travel work operations of the power machine. Correspondingly, discussion of workgroup functions refers to one or more functions provided by movement of one or more workgroup elements of a power machine, whereas discussion of tractive (or drive) functions refer to one or more functions provided for movement of the power machine itself over terrain.

[0062] In some embodiments, aspects of the invention, including computerized implementations of methods according to the invention, can be implemented as a system, method, apparatus, or article of manufacture using standard programming or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a processor device (e.g., a serial or parallel general purpose or specialized processor chip, a single- or multi-core chip, a microprocessor, a field programmable gate array, any variety of combinations of a control unit, arithmetic logic unit, and processor register, and so on), a computer (e.g., a processor device operatively coupled to a memory), or another electronically or operated controller to implement aspects detailed herein. Accordingly, for example, embodiments of the invention can be implemented as a set of instructions, tangibly embodied on a non-transitory computer-readable media, such that a processor device can implement the instructions based upon reading the instructions from the computer-readable media. Some embodiments of the invention can include or utilize a control device (or controller) such as an automation device, a special purpose or general purpose computer including various computer hardware, software, firmware, and so on, consistent with the discussion below. As specific examples, a control device can include a processor, a microcontroller, a field-programmable gate array, a programmable logic controller, logic gates etc., and other typical components that are known in the art for implementation of appropriate functionality (e.g., memory, communication systems, power sources, user interfaces and other inputs, etc.). In some embodiments, a control device can include a centralized hub controller that receives, processes and (re)transmits control signals and other data to and from other distributed control devices (e.g., an engine controller, an implement controller, a drive controller, etc.), including as part of a hub-and-spoke architecture or otherwise.

[0063] The term “article of manufacture'’ as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier (e.g., non-transitory signals), or media (e.g., non-transitory media). For example, computer-readable media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips, and so on), optical disks (e.g., compact disk (CD), digital versatile disk (DVD), and so on), smart cards, and flash memory devices (e.g., card, stick, and so on). Additionally it should be appreciated that a carrier wave can be employed to carry computer-readable electronic data such as those used in transmitting and receiving electronic mail or in accessing a network such as the Internet or a local area network (LAN). Those skilled in the art will recognize that many modifications may be made to these configurations without departing from the scope or spirit of the claimed subject matter.

[0064] Certain operations of methods according to the invention, or of systems executing those methods, may be represented schematically in the FIGS, or otherwise discussed herein. Unless otherwise specified or limited, representation in the FIGS, of particular operations in particular spatial order may not necessarily require those operations to be executed in a particular sequence corresponding to the particular spatial order. Correspondingly, certain operations represented in the FIGS., or otherwise disclosed herein, can be executed in different orders than are expressly illustrated or described, as appropriate for particular embodiments of the invention. Further, in some embodiments, certain operations can be executed in parallel, including by dedicated parallel processing devices, or separate computing devices configured to interoperate as part of a large system.

[0065] As used herein in the context of computer implementation, unless otherwise specified or limited, the terms “component,” “system,” “module,” “block,” and the like are intended to encompass part or all of computer-related systems that include hardware, software, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being, a processor device, a process being executed (or executable) by a processor device, an object, an executable, a thread of execution, a computer program, or a computer. By way of illustration, both an application running on a computer and the computer can be a component. One or more components (or system, module, and so on) may reside within a process or thread of execution, may be localized on one computer, may be distributed between two or more computers or other processor devices, or may be included within another component (or system, module, and so on).

[0066] In some implementations, devices or systems disclosed herein can be utilized, manufactured, installed, etc. using methods embodying aspects of the invention. Correspondingly, any description herein of particular features, capabilities, or intended purposes of a device or system is generally intended to include disclosure of a method of using such devices for the intended purposes, of a method of otherwise implementing such capabilities, of a method of manufacturing relevant components of such a device or system (or the device or system as a whole), and of a method of installing disclosed (or otherwise known) components to support such purposes or capabilities. Similarly, unless otherwise indicated or limited, discussion herein of any method of manufacturing or using for a particular device or system, including installing the device or system, is intended to inherently include disclosure, as embodiments of the invention, of the utilized features and implemented capabilities of such device or system.

[0067] 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

WHAT IS CLAIMED IS:

1. A method of controlling a power machine, the method comprising: receiving, at one or more electronic controllers, pressure data for a first tire of a first tractive element and a second tire of a second tractive element; receiving, at the one or more electronic controllers, a travel command corresponding to a tractive operation of the first and second tractive elements; and determining, with the one or more electronic controllers, if the pressure data satisfies a first pressure criterion relative to the first tire and the second tire; and in response to receiving the travel command and determining that the pressure data satisfies the first pressure criterion, controlling the tractive operation, with the one or more electronic controllers, based on the travel command and the pressure data.

2. The method of claim 1, wherein controlling the tractive operation in response to the travel command includes: if the pressure data satisfies the first pressure criterion, commanding a corrected rotational speed for the one or more of the first tire or the second tire, based on the travel command and the pressure data.

3. The method of claim 1, wherein controlling the tractive operation, if the pressure data satisfies the first pressure criterion, includes determining a corrected ground engagement factor for the one or more of the first tire or the second tire, based on the pressure data.

4. The method of claim 1, wherein the pressure data satisfies the first pressure criterion if the pressure data indicates a pressure differential between the first tire and the second tire that is one of: non-zero; or above a first non-zero pressure threshold.

5. The method of claim 1, further comprising: in response to the pressure data satisfying a second pressure criterion, one or more of: stopping operation of the power machine, or alerting an operator to a high pressure tire condition.

6. The method of claim 1, wherein the travel command includes a steering command for a turning operation of the power machine; and wherein controlling the tractive operation, if the pressure data satisfies the first pressure criterion, includes modifying the steering command based on the pressure data.

7. The method of claim 1, wherein the travel command includes a straight-line command for straight-line travel of the power machine that corresponds to a commanded rotational speed for the first tire and the second tire; and wherein controlling the tractive operation, if the pressure data satisfies the first pressure criterion, includes commanding a modified rotational speed for one or more of the first tire or the second tire, based on the pressure data.

8. The method of claim 7. wherein the commanded modified rotational speed commands the first tire to rotate at a different rotational speed than the second tire.

9. The method of claim 1, wherein the power machine is configured to execute turning operations using independently controlled rotational speeds of the first tire and the second tire.

10. The method of claim 9, wherein the power machine is a zero-radius turn mower.

11. A power machine comprising: a frame; a power source supported by the frame; a first tractive element including a first tire supported on a first side of the frame and configured to rotate under power from the power source; a second tractive element including a second tire supported on a second side of the frame opposite the first side of the frame and configured to rotate under power from the power source; one or more pressure sensors configured to determine pressure data for the first and second tires; and a control system configured to: receive the pressure data for the first and second tires; receive a travel command corresponding to a tractive operation of the first and second tractive elements; and command rotation of one or more of the first or second tractive elements for the tractive operation based on the travel command and the pressure data.

12. The power machine of claim 11, wherein commanding rotation of the one or more of the first or second tires for the tractive operation based on the travel command and the pressure data includes: determining a pressure difference between the first tire and the second tire; and modifying the travel command based on the pressure difference.

13. The power machine of claim 12, wherein the pressure difference between the first tire and the second tire corresponds to a difference in diameter between the first tire and the second tire.

14. The power machine of claim 13, wherein modifying the travel command based on the pressure difference includes determining the difference in diameter and modifying the travel command based on the difference in diameter.

15. The power machine of claim 11, wherein commanding rotation of the one or more of the first or second tires for the tractive operation is further based on receiving an operator command that activates a pressure compensation mode for the power machine.

16. The power machine of claim 11, wherein the power machine is a zero-radius turn mower, the first tire is a right-side tire, and the second tire is a left-side tire.

17. The power machine of claim 16, wherein the power source is an electrical power source.