Power machinery and method of operating a power machinery

Abstract

A power machine may include a frame, a lift arm, and one or more electrical devices for controlling one or more working elements. The electrical devices may be controlled to improve positional accuracy for the working elements during working operations, to improve power management and customer experience (e.g., to provide a smoother ride during driving operations), and to provide float functionality for the working elements.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 301,462, filed on January 20, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure is directed to power machines. More particularly, the present disclosure is directed to power machines that operate in whole or in part under electric power. For the purposes of this disclosure, power machines include any type of machine that generates power for the purpose of completing a specific task or tasks. One type of power machine is a work vehicle. A work vehicle, such as a loader, is typically a self-propelled vehicle having a work device, such as a lift arm (although some work vehicles may 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. Background Art

[0004] Conventional power machines may include hydraulic systems and related components configured to use output from a power source (e.g., an internal combustion engine) to perform various work functions. More specifically, a hydraulic motor may be configured to power movement of the power machine, and a hydraulic actuator (e.g., a hydraulic cylinder) may be used to move a lift arm structure attached to the power machine, to tilt or otherwise move an implement connected to the lift arm structure, or to perform other operations.

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

[0006] Some examples of the present disclosure provide a power machine for movably operating an implement or performing other operations. The power machine may include a main frame supporting an operator station and a lift arm structure.

[0007] Some examples provide a power machine comprising: a main frame; an electrical power source supported by the main frame; a drive system configured to be powered by the electrical power source to provide traction to move the main frame over terrain; and a lift arm structure supported by the main frame. The lift arm structure may include a lift arm, an implement carrier supported by the lift arm, and one or more electric actuators configured to be powered by the electrical power source to do one or more of: move the lift arm relative to the main frame or move the implement carrier relative to the lift arm. The control system may include one or more control devices, which are configured to: receive operator input for moving at least one of the one or more electric actuators in a first predetermined direction during a starting mode of the power machine; based on the received operator input, command the at least one electric actuator to move in the first predetermined direction until at least one of the following is reached: the at least one electric actuator reaches a predetermined reference position, or the control system no longer receives the operator input; and in response to the at least one electric actuator reaching the predetermined reference position, determine the actual position of the at least one electric actuator based on the predetermined reference position.

[0008] In some examples, receiving additional operator input can cause the control system to command the at least one electric actuator to perform additional movement. The one or more control devices can be configured to determine an actual position of the at least one electric actuator corresponding to the additional movement based on the sensed movement relative to the predetermined reference position.

[0009] In some examples, commanding the at least one electric actuator to perform the movement in the first predetermined direction may include commanding the movement at less than or equal to a predetermined speed, which may be slower than a rated operating speed of the at least one electric actuator.

[0010] In some examples, commanding the at least one electric actuator to perform the movement in the first predetermined direction may include commanding the movement at less than or equal to the predetermined speed regardless of a requested speed indicated by the operator input that exceeds the predetermined speed.

[0011] In some examples, the control system may include a resolver in communication with the at least one electric actuator to track relative movement of the at least one electric actuator, wherein one or more control devices may be configured to determine the actual position further based on the tracking of the relative movement of the at least one electric actuator by the resolver.

[0012] In some examples, the received operator input may correspond to a lift arm command, and the first predetermined direction may correspond to a lowering of the lift arm.

[0013] In some examples, the received operator input may correspond to an implement carrier command, and the first predetermined direction may correspond to a retraction of the implement carrier.

[0014] In some examples, the one or more control devices can be configured to command the at least one electric actuator to move in the first predetermined direction after determining that the physical state condition of the power machine can be met and further based on determining that the physical state condition of the power machine can be met.

[0015] Some examples provide a method of operating a power machine. Operator input for moving at least one electric actuator of the power machine may be received. A component of the operator input corresponding to a homing direction may be determined. Based on the power machine being in a startup mode, and upon determining that the component is non-zero, the at least one electric actuator may be commanded to move in the homing direction at a homing speed while the component remains non-zero until the at least one electric actuator reaches a predetermined reference position; and subsequent commanded movement of the at least one electric actuator may be tracked based on relative movement from the predetermined reference position.

[0016] In some examples, based on the power machine being in the starting mode and upon determining that the component is zero, the at least one electric actuator can be commanded to move in a direction corresponding to the operator input, and the movement of the at least one electric actuator can be tracked based on relative movement from a predicted reference position.

[0017] In some examples, a parking position of the at least one electric actuator may be determined during a shutdown of the power machine prior to the power machine being in the startup mode. During the startup mode, determining the predicted reference position may be based on the determined parking position.

[0018] Some examples provide a power machine having a main frame, an electrical power source supported by the main frame, and a lift arm structure supported by the main frame. The lift arm structure may include a lift arm, an implement carrier supported by the lift arm, and one or more electric actuators configured to raise and lower the lift arm relative to the main frame. A control system may include one or more control devices configured to operate the lift arm structure in a floating mode, whereby the one or more electric actuators permit the lift arm structure to move relative to the main frame in response to an external force.

[0019] In some examples, operating the lift arm structure in the float mode may include the one or more control devices selectively powering the one or more electrical actuators to resist, but not stop, the movement of the lift arm structure in response to the external force.

[0020] In some examples, the external force includes gravity.

[0021] In some examples, selectively energizing the one or more electric actuators to resist but not stop the movement of the lift arm may include controlling the one or more electric actuators to prevent the lift arm from moving at a speed exceeding a threshold speed by the external force.

[0022] In some examples, selectively powering the one or more electric actuators to resist but not stop the movement of the lift arm may include providing zero operating power to the one or more electric actuators when a current speed of the lift arm may be zero.

[0023] Some examples provide a method for controlling a lift arm of a power machine using an electronic control system. A float mode may be determined to be an active operating mode for the power machine. Based on the float mode being the active operating mode, operation of one or more electric actuators to raise and lower the lift arm of the power machine may be controlled such that: a current speed of the lift arm remains below a threshold float speed for operation of the lift arm; and the one or more electric actuators are not powered to actively move the lift arm.

[0024] Some examples include controlling operation of the one or more electric actuators such that the one or more electric actuators may not be provided with power to maintain the position of the lift arm based on the float mode being the active operating mode.

[0025] Some examples include, based on the float mode being the active operating mode, controlling operation of the one or more electric actuators such that the one or more electric actuators may be powered to maintain the position of the lift arm against gravity.

[0026] Some examples include: based on the floating mode being the active operating mode, controlling the operation of the one or more electric actuators so that the one or more electric actuators may not be provided with power to maintain the position of the lifting arm against a net external force exceeding the gravity in the direction of gravity.

[0027] In some examples, the float mode may be determined as the active operating mode based on the electronic control system receiving a user input corresponding to a mode selection.

[0028] Some examples provide a power machine comprising a main frame, an electric power source supported by the main frame, and a drive system. The drive system may include: one or more drive motors powered by the electric power source and operably coupled to a traction element to provide traction power for traveling over terrain; and a suspension system that secures the traction element to the main frame. A control system may include one or more control devices configured to control a drive speed of the one or more drive motors according to a first mode to perform precision operation, and to control the drive speed of the one or more drive motors according to a second mode to compensate for travel-induced oscillations on the suspension system. In the second mode, the control system may control the drive speed with an integral gain that is substantially reduced as compared to the first mode.

[0029] In some examples, in the second mode, the control system may control the drive speed by implementing proportional control without an integral control term.

[0030] In some examples, in the second mode, the control system may control the drive speed with a proportional-integral-derivative (PID) control loop that may include an effectively zero integral gain.

[0031] In some examples, the control system can be configured to implement the PID control loop with an effective non-zero integral gain in the first mode.

[0032] In some examples, the control system may be configured to implement the PID control loop with zero integral gain in the first mode.

[0033] In some examples, the control system may be configured to selectively operate in either the first mode or the second mode in response to an operator input indicating a selection of the first mode or the second mode.

[0034] In some examples, the control system may be configured to selectively operate in either the first mode or the second mode based on monitoring operation of one or more actuators of the power machine.

[0035] In some examples, the traction elements may be track-type traction elements.

[0036] Some examples provide a method for controlling a drive operation of a power machine. A selection of a first drive mode or a second drive mode may be received. The power machine may be operated according to the selected first drive mode or second drive mode. In the first drive mode, speed control of one or more electric drive motors of the power machine may be implemented using a proportional-integral-derivative (PID) control loop. In the second drive mode, speed control of the one or more electric drive motors may be implemented using a proportional control loop.

[0037] In some examples, the first drive mode may be a precision control drive mode.

[0038] In some examples, the second drive mode may be a hydraulic simulation drive mode.

[0039] In some examples, the second drive mode may not include a proportional-integral-derivative control loop.

[0040] In some examples, the proportional control loop may correspond to the PID control loop of the first drive mode implemented with an effective zero integral gain.

[0041] Some examples provide a method for controlling a drive operation of a power machine. A selection of a precision control drive mode or a hydraulic simulation drive mode may be received. One or more drive motors, which may be powered by an electric power source and operably coupled to a traction element, may be electronically controlled to provide traction power for traveling over terrain. In response to receiving the selection of the precision control drive mode, the one or more drive motors may be electronically controlled with an effective non-zero integral gain. In response to receiving the selection of the hydraulic simulation drive mode, the one or more drive motors may be electronically controlled with an effective zero integral gain.

[0042] In some examples, in response to the selection of the precision drive mode, the one or more drive motors may be controlled with a first control loop having an effective non-zero integral gain, and in response to the selection of the hydraulic simulation drive mode, the one or more drive motors may be controlled with the first control loop having an effective zero integral gain.

[0043] In some examples, in response to the selection of the hydraulic simulated drive mode, the one or more drive motors may be controlled with the first control loop having zero integral gain.

[0044] In some examples, in response to receiving the selection of the hydraulic simulation drive mode, the one or more drive motors may be controlled with zero integral gain.

[0045] In some examples, in response to receiving the selection of the hydraulic simulated drive mode, the one or more drive motors may be controlled with a proportional-integral-derivative (PID) control loop having the effective zero integral gain.

[0046] In some examples, receiving the selection may include receiving user input indicating the commanded drive mode.

[0047] In some examples, receiving the selection may include automatically identifying the selection based on identifying commanded or actual movement of a non-traction actuator of the power machine.

[0048] The present invention summary and abstract are provided to introduce selected concepts in a simplified form, which are further described in the detailed description below. The present invention summary and 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a block diagram illustrating the functional systems of a representative power machine in which examples of the present disclosure may be advantageously practiced.

[0050] Figure 2 is a perspective view generally illustrating the front of a power machine upon which the examples disclosed herein may be advantageously practiced.

[0051] Figure 3 It is generally shown Figure 2 A perspective view of the rear of the power machine is shown in FIG.

[0052] Figure 4 For example, Figure 2 and Figure 3 A block diagram of the components of the loader's power system.

[0053] Figure 5 is a side elevation view showing certain components of a power machine in the form of an electric compact track loader according to an example of the present disclosure.

[0054] Figures 6 to 8 is a flow chart illustrating a method for controlling one or more actuators of an electric power machine according to an example of the present disclosure. DETAILED DESCRIPTION

[0055] The concepts disclosed in this discussion are described and illustrated with reference to exemplary arrangements. However, these concepts are not limited in their application to the details of construction and the arrangement of components in the illustrative embodiments and can be practiced or implemented in a variety of other ways. The terminology in this document is used for descriptive purposes and should not be considered limiting. As used herein, words such as "including," "comprising," and "having," and variations thereof, are meant to encompass the items listed thereafter, their equivalents, and additional items.

[0056] While the power machines disclosed herein may be embodied in many different forms, several specific embodiments are discussed herein with the understanding that the embodiments described in this disclosure are merely to be considered as examples of the principles described herein and that the disclosed technology is not intended to be limited to the illustrated examples.

[0057] Some of the following discussions describe improved components and configurations for power machines, including components and configurations that use electric (e.g., as opposed to hydraulic) power to operate certain power machine components or otherwise implement certain power machine functionality. In some examples, electric components can be mounted to a power machine frame to selectively move working elements of the power machine, including lift arms or implement carriers. In some examples, electric components can provide motive force for a power machine, including providing motive force for a tracked power machine (e.g., a compact track loader).

[0058] Accordingly, some examples may provide improvements to conventional power machines, including those that use hydraulic components for certain operations and other machines with conventionally controlled electric actuators. For example, under conventional methods, accurately tracking the position of electronically controlled working elements may require the inclusion of complex or expensive position sensors or calibration operations, which may not be compatible in the context of loaders or other work vehicles. In this regard, some examples of the present disclosure may include systems and methods for controlling the homing operation of a lift arm or other working element, including calibrating the lift arm position during a start-up operation with a homing movement based on specific operator input.

[0059] As another example, some configurations can improve ride control for power machines, with corresponding improvements in operator comfort and battery life. During drive operation of a power machine, conventional control of drive motor speed can sometimes result in relatively large or otherwise undesirable oscillations in the power demand and the physical structure of the power machine. For example, relatively fine control of the motor speed of a power machine having a torsional (or other) suspension system can result in relatively large oscillatory movements of the suspension system and corresponding large changes in power delivery from the power source (e.g., rapid swings between fully discharged power and fully charged power). Some examples of the present disclosure may include systems and methods for selectively eliminating integral control from a control loop for drive speed control to reduce these types of oscillations and thereby help reduce wear on power system components and improve operator comfort.

[0060] As another example, some configurations can provide a floating operation for an electric lift arm. For example, when the power machine is operating in a floating mode, the electric actuator used to raise and lower the lift arm can be controlled to allow the lift arm to move under an external force (e.g., gravity or ground contact), but not actively move the lift arm (i.e., not cause the lift arm to move in a direction corresponding to the direction of power to the associated actuator). In some examples, the electric lift actuator can be controlled to provide a back force to ensure that the lift arm does not move at an excessively high speed during a floating operation (e.g., under the force of gravity on a loaded bucket) so that power is not provided to maintain the lift arm in its current position and so as not to actively move the lift arm.

[0061] As will be described below, these concepts can be implemented on a variety of power machines. Figure 1 Representative power machines on which the examples may be practiced are illustrated diagrammatically in the Figures 2 to 3 An example of such a power machine is illustrated in FIG and described below before any examples are disclosed. For the sake of brevity, only one power machine is illustrated and discussed as a representative power machine. However, as mentioned above, the examples below can be practiced on any of a plurality of power machines, including with Figures 2 to 3 Representative power machines are shown in Figure 1. For the purposes of this discussion, a power machine includes a frame, at least one working element, and a power source that can power the working element to complete a work task. One type of power machine is a self-propelled work vehicle. A self-propelled work vehicle is a type of power machine that includes a frame, working elements, and a power source that can power the working elements. At least one of the working elements is a prime mover system for moving the power machine under power.

[0062] Figure 1is a block diagram illustrating the basic systems of a power machine 100 , which may be any of a number of different types of power machines upon which the examples discussed below may be advantageously incorporated. Figure 1 The block diagram of FIG1 identifies the various systems on the power machine 100 and the relationships between the various components and systems. As mentioned above, at the most basic level, a power machine for the purposes of this discussion includes a frame, a power source, and working elements. The power machine 100 has a frame 110, a power source 120, and working elements 130. Because Figure 1 The power machine 100 shown in FIG is a self-propelled work vehicle, and therefore also has a tractive element 140, which is itself a working element configured to move the power machine over a supporting surface, and an operator station 150, which provides an operating location for controlling the working element of the power machine. A control system 160 is provided for interacting with other systems to perform various work tasks, at least in part in response to control signals provided by an operator.

[0063] Certain work vehicles have work elements that can perform specialized tasks. For example, some work vehicles have a lift arm to which an implement (e.g., a bucket) is attached, for example, by a pinned arrangement. The work element (i.e., 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, for example, by rotating the bucket relative to the lift arm, to further position the implement. Under normal operation of such a work vehicle, the bucket is intended to be attached and in use. Such a work vehicle may be able to accommodate other implements by disassembling the implement / work element combination and reassembling another implement in place of the original bucket. However, other work vehicles are intended for use with a wide variety of implements and have implement interfaces, for example, Figure 1 At its most basic, the implement interface 170 is a connection mechanism between the frame 110 or work element 130 and the implement, which can be as simple as a connection point for attaching the implement directly to the frame 110 or work element 130 or more complex, as discussed below.

[0064] On some power machines, the implement interface 170 may include an implement carrier, a physical structure that is removably attached to the work element. The implement carrier has engagement and locking features to receive and secure any of a variety of different implements to the work element. A characteristic of such an implement carrier is that once an implement is attached to it, it is fixed to the implement (i.e., cannot move relative to the implement), and when the implement carrier moves relative to the work element, the implement moves with the implement carrier. The term implement carrier, as used herein, is not merely a pivot connection point, but is specifically intended to refer to a dedicated device that receives and secures a variety of different implements. The implement carrier itself may be mounted to the work element 130, such as a lift arm or frame 110. The implement interface 170 may also include one or more power sources for providing power to one or more work elements on the implement. Some power machines may have multiple work elements with implement interfaces, each of which may, but need not, have an implement carrier for receiving an implement. Some other power machines may have a working element with multiple implement interfaces, so that a single working element can simultaneously receive multiple implements. Each of these implement interfaces may, but need not, have an implement carrier.

[0065] Frame 110 comprises a physical structure that can support various other components attached to or positioned thereon. Frame 110 can include any number of individual components. Some power machines have a rigid frame. That is, no part of the frame can move relative to another part of the frame. Other power machines have at least one part that can move relative to another part of the frame. For example, an excavator may have an upper frame portion that rotates relative to a lower frame portion. Other work vehicles have an articulated frame, allowing one part of the frame to pivot relative to another part to perform a steering function.

[0066] Frame 110 supports a power source 120 that is configured to provide power to one or more working elements 130, including one or more traction elements 140, and, in some instances, to provide power for use by an attached implement via an implement interface 170. Power from power source 120 can be provided directly to any of the working elements 130, traction elements 140, and implement interface 170. Alternatively, power from power source 120 can be provided to a control system 160, which in turn selectively provides power to elements that can use it to perform working functions. Power sources for power machines typically include an engine (e.g., an internal combustion engine) and a power conversion system (e.g., a mechanical transmission or a hydraulic system) that is configured to convert output from the engine into a form of power that can be used by the working elements. Other types of power sources can be incorporated into a power machine, including a combination of electrical or power sources, often referred to as hybrid power sources.

[0067] Figure 1 A single working element, designated as working element 130, is shown, but various power machines may have any number of working elements. A working element is typically attached to the frame of the power machine and is movable relative to the frame when performing a working task. For example, the power machine may be a lawn mower having a mower deck or other mower component as a working element, which is movable relative to the mower frame. Furthermore, traction elements 140 are a special case of working elements, as their working function is typically to move the power machine 100 over a supporting surface. Traction elements 140 are shown separate from working element 130, as many power machines have additional working elements in addition to the traction element, although this is not always the case. A power machine may have any number of traction elements, some or all of which may receive power from power source 120 to propel the power machine 100. Traction elements may be, for example, track assemblies, wheels attached to axles, and the like. The tractive elements may be mounted to the frame such that movement of the tractive elements is limited to rotation about the axle (such that steering is accomplished by a sliding motion), or alternatively, pivotally mounted to the frame such that steering is accomplished by pivoting the tractive elements relative to the frame.

[0068] Power machine 100 includes an operator station 150, which includes an operating position from which an operator can control the operation of the power machine. In some power machines, operator station 150 is defined by an enclosed or partially enclosed cab. Some power machines on which the disclosed examples may be practiced may not have a cab or operator compartment of the type described above. For example, a walk-behind loader may not have a cab or operator compartment, but instead have an operating position that serves as an operator station, from which the power machine is operated. More generally, power machines that are not work vehicles may have an operator station that is not necessarily similar to the operating position and operator compartment referenced above. Furthermore, some power machines (e.g., power machine 100 and others), whether or not they have an operator compartment or operator position, may be capable of being operated remotely (i.e., from a remotely located operator station) in place of or in addition to an operator station adjacent to or on the power machine. This may include applications in which at least some of the operator-controlled functions of the power machine can be operated from an operating position associated with an implement coupled to the power machine. Alternatively, in the case of some power machines, a remote control device may be provided (ie, remote from both the power machine and any implement coupled thereto) that is capable of controlling at least some of the operator-controlled functions on the power machine.

[0069] Figures 2 to 3 The loader 200 is shown in the figure. Figure 1 A specific example of a powered machine of the type illustrated in FIG, wherein the examples discussed below may be advantageously employed, is shown. Loader 200 is a skid-steer loader, which is a loader having tractive elements (in this case, four wheels) mounted to the loader's frame via rigid axles. Here, the phrase "rigid axles" refers to the fact that skid-steer loader 200 does not have any tractive elements that can rotate or steer to help the loader complete turns. Instead, a skid-steer loader has a drive system that independently powers one or more tractive elements on each side of the loader, such that by providing different tractive signals to each side, the machine will tend to skid above a supporting surface. These varying signals may even include: powering the tractive element(s) on one side of the loader to move the loader in a forward direction; and powering the tractive element(s) on the other side of the loader to move the loader in a reverse direction, such that the loader will rotate about a radius centered within the loader's own footprint. The term "skid steer" has traditionally referred to a loader with a skid steer as described above, in which wheels serve as traction elements. However, it should be noted that many track loaders also accomplish turns via skid steer and are technically skid steer loaders, even though they lack wheels. For the purposes of this discussion, unless otherwise noted, the term skid steer should not be considered to limit the scope of the discussion to those loaders in which wheels serve as traction elements. Accordingly, although some of the exemplary power machines discussed herein are presented as skid steer power machines, some of the examples disclosed herein can be implemented on a variety of other power machines. For example, some configurations can be implemented on compact loaders or compact excavators that do not accomplish turns via skid steer.

[0070] Loader 200 is in Figure 1 For that purpose, the features of the loader 200 described below include the following: Figure 1The reference numerals used in the drawings are generally similar to those used in the drawings. For example, loader 200 is described as having a frame 210, just as power machine 100 has a frame 110. Skid steer loader 200 is described herein to provide a reference for understanding an environment in which the examples described below, relating to track assemblies and mounting elements for mounting the track assemblies to power machines, can be practiced. Loader 200 should not be considered limiting, particularly with respect to descriptions of features that may be described herein for loader 200 that are not essential to the disclosed examples and, therefore, may or may not be included in power machines other than loader 200. The examples disclosed below can advantageously be practiced on loader 200. Unless otherwise specifically noted, the examples disclosed below can be practiced on a variety of power machines, with loader 200 being just one of those. For example, some or all of the concepts discussed below can be practiced on many other types of work vehicles (e.g., various other loaders, excavators, trenchers, and bulldozers, to name a few).

[0071] Loader 200 includes a frame 210 that supports a power system 220, which is capable of generating or otherwise providing power for operating various functions on the power machine. Power system 220 is shown in block diagram form, but is located within frame 210. Frame 210 also supports a working element in the form of a lift arm assembly 230, which is powered by power system 220 and capable of performing various work tasks. When loader 200 is a work vehicle, frame 210 also supports a traction system 240, also powered by power system 220 and capable of propelling the power machine over a supporting surface. Lift arm assembly 230, in turn, supports an implement interface 270, which includes an implement carrier 272 that can receive and secure various implements to loader 200 for performing various work tasks, and a power coupling 274 to which an implement can be coupled for selectively providing power to the implement that may be connected to the loader. The power coupling 274 can provide a source of hydraulic power or an electrical power source, or both. The loader 200 includes a cab 250 defining an operator station 255 from which an operator can manipulate various controls 260 to cause the power machine to perform various work functions. The cab 250 can be pivoted rearward about an axis extending through the mounting 254 to provide access to power system components as needed for maintenance and repair.

[0072] The operator station 255 includes an operator seat 258 and a plurality of operator input devices, including a control lever 260 that the operator can manipulate to control various machine functions. The operator input devices may include buttons, switches, control levers, sliders, pedals, and the like, which may be stand-alone devices (e.g., manually operated control levers or foot pedals) or incorporated into a handle or display panel (including programmable input devices). Actuation of the operator input devices may generate signals in the form of electrical, hydraulic, and / or mechanical signals. Signals generated in response to the operator input devices are provided to various components on the power machine for controlling various functions on the power machine. Among the functions controlled via the operator input devices on the power machine 200 are control of the traction element 219, the lift arm assembly 230, the implement carrier 272, and providing signals to any implement that may be operably coupled to the implement.

[0073] The loader may include a human-machine interface, including a display device disposed in the cab 250 to provide information relevant to the operation of the power machine in a form perceivable by the operator (e.g., for example, audible and / or visual indications). Audible indications may take the form of buzzers, bells, and the like, or via verbal communication. Visual indications may take the form of graphics, lights, icons, meters, alphanumeric characters, and the like. The display may provide dedicated indications, such as warning lights or meters, or dynamically provide programmable information, including programmable display devices, such as monitors of various sizes and capabilities. The display device may provide diagnostic information, troubleshooting information, instructional information, and various other types of information to assist the operator in operating the power machine or implements coupled to the power machine. Other information that may be useful to the operator may also be provided. Other power machines (e.g., walk-behind loaders) may lack a cab, an operator compartment, or a seat. The operator position on such loaders is typically defined relative to the position where the operator is best suited to manipulate the operator input devices.

[0074] Various power machines, including and / or interacting with the examples discussed below, may have a variety of different frame components that support various working elements. The elements of frame 210 discussed herein are provided for illustrative purposes, and frame 210 is not the only type of frame that may be employed by power machines on which the examples may be practiced. The frame 210 of the loader 200 includes a chassis or lower portion 211 of the frame and a main frame or upper portion 212 of the frame supported by the chassis. In some examples, the main frame 212 of the loader 200 is attached to the chassis 211, for example, using fasteners or by welding the chassis to the main frame. Alternatively, the main frame and chassis may be integrally formed. The main frame 212 includes a pair of upright portions 214A and 214B located on either side of the main frame and toward the rear of the main frame. The upright portions 214A and 214B support a lift arm assembly 230, and the lift arm assembly 230 is pivotally attached to the upright portions 214A and 214B. Lift arm assembly 230 is illustratively pinned to each of upright portions 214A and 214B. For the purposes of this discussion, the combination of upright portions 214A and 214B, along with the mounting features on lift arm assembly 230 and mounting hardware (including the pins used to pin lift arm assembly to main frame 212), is collectively referred to as joints 216A and 216B (one located on each upright portion 214). Joints 216A and 216B are aligned along axis 218, enabling the lift arm assembly to pivot about axis 218 relative to frame 210, as discussed below. Other power machines may not include upright portions on either side of the frame, or may not have a lift arm assembly that can be mounted to upright portions on either side of the frame and toward the rear of the frame. For example, some power machines may have a single arm mounted to a single side of the power machine, or to the front or rear end of the power machine. Other machines may have multiple working elements, including multiple lift arms, each of which is mounted to the machine in its own configuration. The frame 210 also supports a pair of traction elements in the form of wheels 219A-D on either side of the loader 200 .

[0075] Figures 2 to 3The lift arm assembly 230 shown in FIG is one example of many different types of lift arm assemblies that can be attached to a power machine, such as the loader 200 or other power machine on which the examples of this discussion may be practiced. The lift arm assembly 230 is a so-called vertical lift arm, meaning that the lift arm assembly 230 is movable relative to the frame 210 along a lift path 237 that forms a generally vertical path (i.e., the lift arm assembly can be raised and lowered) under the control of the loader 200. Other lift arm assemblies may have different geometries and may be coupled to the loader's frame in various ways to provide lift paths that differ from the radial path of the lift arm assembly 230. For example, some lift paths on other loaders provide radial lift paths. Other lift arm assemblies may have extendable or telescoping portions. Other power machines may have multiple lift arm assemblies attached to their frames, each lift arm assembly being independent of the other lift arm assemblies. Unless otherwise specifically stated, the inventive concepts described in this discussion are not limited by the type or number of lift arm assemblies coupled to a particular power machine.

[0076] The lift arm assembly 230 has a pair of lift arms 234 disposed on opposite sides of the frame 210. The first end 232A of each of the lift arms 234 is pivotally coupled to the power machine at a joint 216 and when in a position such as Figure 2 , the second end 232B of each of the lift arms is positioned forward of the frame 210. The joint 216 is positioned toward the rear of the loader 200 so that the lift arms extend along the sides of the frame 210. A lift path 237 is defined by the path of travel of the second end 232B of the lift arms 234 as the lift arm assembly 230 moves between a minimum height and a maximum height.

[0077] Each lift arm 234 has a first portion 234A that is pivotally coupled to the frame 210 at one of the joints 216, and a second portion 234B that extends from its connection with the first portion 234A to the second end 232B of the lift arm assembly 230. The lift arms 234 are each coupled to a cross member 236 attached to the first portion 234A. The cross member 236 provides increased structural stability to the lift arm assembly 230. On the loader 200, a pair of actuators 238, each configured as a hydraulic cylinder that receives pressurized fluid from the power system 220, are pivotally coupled to both the frame 210 and the lift arms 234 at pivotable joints 238A and 238B, respectively, located on either side of the loader 200. The actuators 238 are sometimes referred to individually and collectively as lift cylinders. Actuation (i.e., extension and retraction) of actuator 238 causes lift arm assembly 230 to pivot about joint 216 and thereby raise and lower along a fixed path illustrated by arrow 237. Each of a pair of control links 217 is pivotally mounted to frame 210 and one of lift arms 232 on either side of frame 210. Control links 217 help define the fixed lift path of lift arm assembly 230.

[0078] Some lift arms, most notably those on excavators, but possibly also those on loaders, may have a section that is controllable to pivot relative to another section, rather than Figure 2 The lift arm assemblies 230 shown in FIG. 2 may be moved in concert (i.e., along a predetermined path) as in the lift arm assembly 230 shown in FIG. Some power machines have a lift arm assembly with a single lift arm, such as is known in excavators or even some loaders and other power machines. Other power machines may have multiple lift arm assemblies that are each independent of one another.

[0079] An implement interface 270 is provided proximate the second end 232B of the lift arm assembly 234. The implement interface 270 includes an implement carrier 272 that is capable of receiving and securing a variety of different implements to the lift arm 230. Such implements have a complementary mechanical interface configured to engage with the implement carrier 272. The implement carrier 272 is pivotally mounted at the second end 232B of the arm 234. An implement carrier actuator 235 operably couples the lift arm assembly 230 and the implement carrier 272 and is operable to rotate the implement carrier relative to the lift arm assembly. The implement carrier actuator 235 is illustratively a hydraulic cylinder and is commonly referred to as a tilt cylinder.

[0080] By enabling the implement carrier to be attached to a variety of different implements, changing from one implement to another can be accomplished relatively easily. For example, a machine with an implement carrier can provide an actuator between the implement carrier and the lift arm assembly so that removing or attaching the implement does not involve removing or attaching the actuator from the implement or removing or attaching the implement from the lift arm assembly. The implement carrier 272 provides a mounting structure for easily attaching the implement to the lift arm (or other part of the power machine), which a lift arm assembly without an implement carrier does not have.

[0081] Some power machines may have an implement or implement-like structure attached to it, for example, by being pinned to a lift arm, with the tilt actuator also being directly coupled to the implement or implement-like structure. A common example of such an implement that is rotatably pinned to the lift arm is a bucket, with one or more tilt cylinders attached to a bracket that is directly secured to the bucket, for example, by welding or with fasteners. Such power machines do not have an implement carrier, but rather have a direct connection between the lift arm and the implement.

[0082] The implement interface 270 also includes an implement power source 274 that can be connected to an implement on the lift arm assembly 230. The implement power source 274 includes a pressurized hydraulic fluid port to which the implement can be removably coupled. The pressurized hydraulic fluid port selectively provides pressurized hydraulic fluid for powering one or more functions or actuators on the implement. The implement power source can also include an electrical power source for powering electrical actuators and / or electronic controllers on the implement. The implement power source 274 also illustratively includes electrical conduits that communicate with a data bus on the excavator 200 to allow communication between the controller on the implement and the electronics on the loader 200.

[0083] The frame 210 supports and generally surrounds the power system 220 so that the various components of the power system 220 are Figures 2 to 3 The arrangement of the drive pump, motor, and axle in power machine 200 is merely one example of how these components may be arranged. As discussed above, power machine 200 is a skid-steer loader, and therefore, the tractive elements on each side of the power machine are controlled together via the output of a single hydraulic pump, either by a single drive motor as in power machine 200, or by individual drive motors. Various other configurations and combinations of hydraulic drive pumps and motors may be employed, which may be advantageous.

[0084] The above description of the power machine 100 and the loader 200 is provided for illustrative purposes to provide an illustrative environment on which the examples discussed below may be practiced. Figure 1The concepts discussed below are practiced on power machines generally described herein (and more specifically, on loaders such as track loader 200 ) as shown in the block diagram of FIG. 1 , but unless otherwise indicated or described, the concepts discussed below are not intended to limit their application to the environment specifically described above.

[0085] Figure 4 A schematic diagram of a block diagram of a power machine 400 is shown, which may be any of a variety of different types of power machines (e.g., a wheeled or tracked skid steer loader), including any of the types generally discussed above. To accomplish various work and drive operations, the power machine 400 may include a power source 402, a control device 404, and electric actuators 406, 408. Either or both of the electric actuators 406, 408 may be variously configured as one or more drive actuators or one or more work group actuators, and may provide Figure 4 . For example, as discussed further below, some power machines may include left and right drive actuators, each including a respective electric drive motor configured to provide power to an associated tractive element (e.g., an endless track assembly), as well as various extendable (or other) working actuators (e.g., one or more extendable lift arm actuators, one or more extendable tilt actuators, etc.). In some cases, and also as Figure 4 As shown in FIG, one or more brakes 410 , 412 may be configured to stop movement of an associated one or more of the actuators 406 , 408 based on a control signal from the control device 404 .

[0086] In the illustrated example, power machine 400 may be an electric power machine, and therefore, power source 402 may include an electrical power source, such as, for example, a battery pack including one or more battery cells (e.g., lithium-ion batteries). In some examples, power source 402 may include other electrical storage devices (e.g., capacitors) and other power sources. Additionally, power machine 400 may, but need not, include an internal combustion engine that provides electrical power to power source 402 via a generator (e.g., to charge one or more batteries of the electrical power source).

[0087] Typically, the control device 404 can be implemented in a variety of different ways and can include one or more types or instances of known electronic controllers. For example, the control device 404 can be implemented as a processor device of a known type (e.g., a microcontroller, a field programmable gate array, a programmable logic controller, a logic gate, etc.), including as part of one or more general or special-purpose computers. In addition, the control device 404 may also include other computing components or be in operable communication with other computing components, and the other computing components include memory, input devices, output devices, etc. (not shown). In this regard, the control device 404 can be configured to implement some or all of the operations of the processes described herein, which operations can be retrieved from memory or otherwise interact with memory as appropriate. In some examples, the control device 404 may include multiple control devices (or modules) that can be integrated into a single component or arranged as multiple separate components. In some examples, the control device 404 can be a larger control system (e.g., Figure 1 160) and therefore may include or be in electronic communication with various control modules, including a hub controller, an engine controller, a drive controller, and the like.

[0088] In various examples, different types of actuators can be configured to operate under power from the power source 402, including electric actuators configured as rotary actuators, linear actuators, and combinations thereof. Figure 4 In the example shown in FIG, the actuator 406 is a drive actuator and includes an electric motor 416 configured to provide power to one or more traction elements ( Figure 4 As noted above, some power machines may include multiple drive actuators, including drive actuators such as may be arranged for skid steering operations.

[0089] Also like Figure 4As shown in the example of FIG4 , the actuator 408 is a work group actuator and, therefore, includes an electric motor 420 configured to provide rotational power for operating one or more non-driven work elements (e.g., a lift arm, an implement, etc.). In some cases, the motor 420 can be configured to power the movement of an extender 422 (e.g., a leadscrew, a ball screw, another similar threaded assembly, or other known components for providing rotationally powered non-rotational movement). The extender 422 can convert the rotational power of the motor 420 into translational movement of the extender 422 to provide translational power to the work element of the power machine 400. For example, the motor 420 can rotate in a first direction to drive extension of the extender 422, and when the motor rotates in a second rotational direction opposite the first rotational direction, can rotate in the second direction to drive retraction of the extender 422. In this manner, and depending on how the electric actuator 406 is coupled to components of the power machine 400, extension (and retraction) of the electric actuator 406 can, for example, raise (or lower) a lift arm of the power machine 400, change the posture of an implement (e.g., a bucket) of the power machine 400, etc.

[0090] Thus, generally, each motor 416, 420 can be controlled to implement specific functionality of the power machine 400. As generally noted above, in some cases, multiple drive actuators or different configurations of work group actuators (e.g., multiple instances of actuators 406, 408 as shown) can be included to provide different functionality for a particular power machine. For example, in some configurations, the power machine 400 may include: an electric actuator that is a first lift actuator on a first lateral side of the power machine 400; an electric actuator that is a second lift actuator on a second lateral side of the power machine 400; an electric actuator that is a first tilt actuator on a first lateral side of the implement interface of the power machine 400; an electric actuator that is a second tilt actuator on a second lateral side of the implement interface of the power machine 400; an electric actuator that is a first drive actuator of a first drive system for powering the first lateral side of the power machine 400 (or otherwise powering one or more traction elements); and an electric actuator that is a second drive actuator of a second drive system for powering the second lateral side of the power machine 400 (or otherwise powering one or more traction elements).

[0091] As also noted above, in some examples, the brakes 410, 412 can be coupled to (e.g., included in) corresponding electric actuators 406, 408. In this regard, a variety of known braking systems can be used. For example, one or more brakes can be mechanical brakes comprising mechanical stops that can be moved into engagement to block movement of the associated extender or associated motor in one or more directions, and can be moved out of engagement to allow movement of the associated extender or motor. In some cases, the mechanical brake can include an arm that contacts the linear screw of the extender to prevent further movement of the linear screw. In some examples, one or more electric brakes (i.e., a brake assembly comprising one or more electric actuators for applying a braking force) can be provided.

[0092] like Figure 4 As shown in FIG, a power source 402 can be electrically connected to a control device 404, electric actuators 406, 408, and brakes 410, 412 (as appropriate), as well as one or more auxiliary loads 414. Thus, the power source 402 can provide power to each motor 416, 420 to drive movement (e.g., extension and retraction) of a corresponding extender 418, 422, to the control device 404, to each brake 410, 412 (as appropriate), to each of the auxiliary load(s) 414, and so on. Furthermore, the power source can provide power to auxiliary loads 414 for various auxiliary functionalities (i.e., loads not associated with providing traction or work group power). For example, the auxiliary loads can include a climate control system (e.g., including a heater, air conditioning system, fan, etc.), an audio system (e.g., speakers, radio, etc.), and so on. In some cases, the auxiliary loads 414 can be treated with lower priority according to certain power management modes.

[0093] like Figure 4As shown in FIG, a control device 404 can be in electrical communication with a power source 402, actuators 406, 408, brakes 410, 412 (optionally), and auxiliary load(s) 414, and can adjust (e.g., limit) the power delivered from the power source 402 to each of these electrical loads (or others) or the power consumed by each of these electrical loads (or others). For example, the control device 404 can adjust (e.g., reduce) the power delivered to each of these electrical loads by adjusting (e.g., reducing) the current that can be consumed by at least some of these electrical loads. In some cases, the control device 404 can adjust the current delivered to the electrical load by adjusting a drive signal delivered to a current source (e.g., a voltage-controlled current source), which can be electrically connected to the electrical load (e.g., integrated within a power electronics driver board (e.g., a motor drive)) to deliver current to the electrical load. For example, the current source may include one or more field effect transistors, and the drive signal may be a voltage applied to the one or more field effect transistors to adjust the current delivered and thereby adjust the power delivered to the electrical load (e.g., a motor).

[0094] In some examples, similar to each of the electrical loads of power machine 400, the electrical power source of power source 402 may include (or may be otherwise electrically connected to) a current source (e.g., a power electronics board) that adjusts (e.g., and may limit) the amount of power delivered to the electrical loads of power machine 400. In such cases, control device 404 may adjust the drive signal to the electrical power source to adjust the total amount of current, and therefore the amount of power delivered to the electrical loads of power machine 400. For example, control device 404 may adjust the output from electrical power source 402 to regulate the torque, position, direction, and speed of one or more motors powered by power source 402.

[0095] In some examples, control device 404 can be configured to determine the current (i.e., current in time) power usage of one or more actuators or other electrical loads, or the current power delivery from the power source. In some cases, the current power usage or delivery can be measured instantaneously. In some cases, the current power usage or delivery can be measured as the average power delivery over a recent time interval (e.g., the previous 2 seconds). Thus, for example, control device 404 can determine the current power usage of each electrical load of power machine 400, or can determine the current power delivery of the electrical power source from power source 402.

[0096] In some cases, each electrical load and power source 402 of the power machine may include or may be otherwise electrically connected to a current sensor to determine the current supplied to (or provided by) the particular electrical component, and may also determine the voltage supplied to (or provided by) the particular electrical component (e.g., based on a voltage sensor or a fixed voltage provided by power source 402). In this manner, control device 404 may receive information about the current voltage and current delivered to each individual electrical load, or about the current voltage and current supplied by the power sources of power machine 400 in total, for example, and may thereby determine the current power usage of the associated (e.g., all) electrical loads and power sources of power machine 400.

[0097] In some examples, the control device 404 may determine the current power usage of the power source of the power machine 400 by adding the current power usage of each associated electrical load of the power machine 400 (e.g., as determined by multiplying the current and voltage of the loads). Alternatively, for example, the power may be determined by multiplying the torque and speed of one or more associated motors. In some cases, it may be advantageous to use any of these known methods. In other cases, the control device 404 may determine the current power usage of the power source of the power machine 400 simply by determining the power delivered by the power source. For example, the control device 404 may receive a current value of the current delivered by the power source 402 and may then determine the total current power usage of the power source based on the voltage of the power source 402. In some cases, the control device 404 may assume a substantially constant voltage for the power source and may then determine the current power usage of the power source by using the constant voltage and the current current value.

[0098] In some examples, power source 402 may include or be electrically connected to a sensor to sense the current remaining energy of the power source. In some cases, for example, a voltage sensor may sense the voltage of the power source, which may indicate the current remaining energy remaining in the power source (e.g., because the voltage of the power source may be related to the current remaining energy in the power source). Any suitable means for sensing the remaining energy of the power source may be used, including taking into account how much current is supplied by the energy storage device over time.

[0099] In some examples, the power machine 400 may include one or more sensors that can sense various aspects of the power machine 400. For example, the power machine 400 may include a torque sensor for one or more electric actuators to sense the current torque of the one or more electric actuators. In some cases, the torque sensor may be the same as the current sensor electrically connected to the electric actuator (e.g., because current is related to torque). As another example, the power machine 400 may include a position sensor for one or more extenders or other components of one or more electric actuators (as the case may be), including, for example, a sensor that can sense the current extension of the extender of the electric actuator (e.g., relative to the housing of the electric actuator). In some cases, this may be a Hall effect sensor, a rotary encoder for a motor (e.g., which can be used to determine the extension of an actuator having an extender), an optical sensor, etc. In some cases, the power machine 400 may include a rotary transformer (not shown) that is configured to track the relative movement of one or more actuators (e.g., in a manner similar to Figure 5 548 is positioned to track the movement of actuator 518). As yet another example, power machine 400 can include angle sensors for one or more pivotable joints (e.g., of a lift arm) to determine the current orientation of the lift arm (and any implement coupled thereto). As yet another example, power machine 400 can include a velocity sensor or an acceleration sensor (e.g., an accelerometer) to determine the current velocity or current acceleration, respectively, of the entire power machine 400 or a component thereof. As yet another example, power machine 400 can include an inclinometer (e.g., an accelerometer) that can sense the current attitude of the main frame of power machine 400 relative to gravity.

[0100] Figure 5 A side isometric view of an electric power machine 500 is shown with the lift arm in the fully lowered position, which may be an embodiment of power machine 200, power machine 400, etc. Figure 5As shown in FIG, a power machine 500 may include a main frame 502, a lift arm 504 coupled to the main frame via a follower link 506, a driver link 508 pivotally coupled to the lift arm 504 and the main frame 502, an operator enclosure 510 (e.g., a cab, as shown), an implement interface 514 coupled to the end of the lift arm 504, an implement 516 (e.g., a bucket as shown) coupled to the implement interface 514, an electric lift actuator 518, an electric tilt actuator 522, an electric power source 526, a drive system 528 (e.g., including an electric drive motor), a traction device 532 (e.g., an endless track as shown), and a climate control system 536 (e.g., as generally representative of the entire auxiliary electrical load). In some examples, a suspension system 540 (e.g., a torsional suspension system) may be included to provide improved ride control and overall ride smoothness. As generally noted above, in some cases, similar (e.g., substantially identical) other components may be symmetrically (or otherwise) disposed on opposite lateral sides of the power machine 500, including another electric lift actuator, another electric tilt actuator, etc. Additionally, various examples may employ various lift arm geometries, including having lift arm structures that do not include driver or follower linkages.

[0101] In some cases, power source 526 can be implemented in a manner similar to the previously described power sources (e.g., power source 402). Thus, power source 526 can include a battery pack comprising one or more batteries. Generally, power source 526 can supply power to some or all of the electrical loads of power machine 500. For example, power source 526 can provide power to electric lift actuator 518, electric tilt actuator 522, drive system 528, climate control system 536, and the like.

[0102] The power machine 500 may also include a control device 546 that may optionally communicate with the power source 526 and some (or all) of the electrical loads of the power machine 500. For example, the control device 546 may communicate with the electric lift actuator 518, the electric tilt actuator 522, the drive system 528, the climate control system 536, etc. In this manner, the control device 546 may control the operation of these components or related other systems to adjust how power is routed to each of these electrical loads (e.g., depending on criteria defined by a particular power management mode) and, correspondingly, how power is consumed from the power source 526 during a given operating function or time interval.

[0103] As noted above, some examples may include a control system or method for calibrating the position of a lift arm during startup operations of a power machine. For example, when the power machine 500 is started from a powered-off state, the control device 546 may not necessarily know the current position of the lift arm 504 (e.g., as indicated by the current extension distance of the lift actuator 518). Accordingly, to ensure reliable operation of the lift arm 504, it may be useful to identify a reference (or "home") position of the lift arm 504 that corresponds to a reference position (e.g., extension length) of the lift actuator 518.

[0104] In some examples, it may be advantageous to delay execution of the home operation until appropriate operator input is received. Accordingly, for example, if the lift arm 504 is to be lowered to a lower mechanical stop corresponding to the home position of the lift arm 504 and lift actuator 518, the control device 546 may delay actually commanding the lift arm 504 to be lowered until the operator has actively commanded the lowering movement.

[0105] In some examples, the control device 546 can sometimes control the speed of the homing movement of the work element regardless of the movement speed commanded by the corresponding operator input. For example, during the start-up mode and before the lift arm 504 has been homed, the control device 547 can command a lowering movement to home the lift arm 504 based on receiving the operator input for a lowering movement, but can control the lift arm 504 to move at or below the homing speed even if the operator command requests a faster movement.

[0106] In some examples, the home position can be at a fully lowered position (i.e., a position in which the lift arm engages a stop on the machine's frame) such that the lift arm can physically not move any further in the lowering direction. In other examples, the home position can correspond to a position in which the lift arm passes at least one position sensor (e.g., a switch) that can sense when the lift arm is in a particular position. In various examples, the power machine can have more than one such limit switch (or other limit sensor), each individually identifiable and each capable of operating as a home position.

[0107] For the purposes of this discussion, startup mode can be an initial period of time when an operator has initiated use of the machine, for example, by turning on a key or other similar action. Alternatively, or in addition, startup mode can be a period of time during which an operator takes specific action to initiate or unlock working elements on the machine (including the drive system and lift arm controls) to cause the machine to move to a fully enabled state in which, for example, lift arm and drive system functions can be operated. Accordingly, during startup mode, operator-controlled or other powered operation can be prevented for specific actuators, for specific functionality, or for traction elements or other specific powered machine subsystems.

[0108] In some examples, once the home position of the lift arm has been established for a particular activation mode, subsequent operation of the lift arm can be controlled to a commanded position based on the known (e.g., fixed or otherwise previously determined) home position and sensed movement away from the home position. For example, once the home (e.g., fully lowered) position has been established for the lift arm 504, subsequent control of the lift arm 504 can include tracking the actual position (e.g., extension length) of the lift actuator 518 based on the determined home position and relative movement of the lift actuator 518 sensed by the rotary transformer 548.

[0109] In some examples, it may be possible to bypass one or more of the homing operations noted above, or to use historical information to approximate the current actuator orientation(s) before the homing operation has been completed (e.g., before the associated actuator has reached the home position). For example, the last position of the lift arm 504, as sensed by the resolver 548, can be stored when the power machine 500 is shut down, and then compared to the current position sensed by the resolver 548 during a subsequent startup mode. If the stored position and the current position are consistent, operational control of the lift arm 504 can sometimes continue without re-establishing the home position (e.g., via control based on the previously stored home position). Accordingly, in some cases, the shutdown sequence of the power machine can include a delay imposed between an operator-requested power outage and the actual termination of power to the associated control device (e.g., device 546 or a dedicated motor controller) to allow the current resolver position to be properly received and stored.

[0110] In some examples, other conditions may also be applied, including allowing a homing operation to be delayed in some cases until certain physical conditions of the power machine are achieved. For example, a homing operation that requires the lift arm to move (e.g., lower) relative to the main frame of the power machine may be prevented until a door of the power machine is fully closed or other physical condition of the power machine is met (e.g., the cab door is closed, the seat belt or other safety or restraint system is engaged, a valid access code has been entered, or other authorization conditions have been met). In some examples, a homing operation may be interrupted, including when the operator input that initiated the homing operation is deactivated. This may allow the operator to abort the homing operation for any reason if the operator desires to do so.

[0111] In some examples, determining a reference position during the start-up mode can be implemented for actuators other than the lift actuator for lifting the arm. For example, a similar homing operation as discussed above with respect to the lift actuator 518 can be implemented with respect to the tilt actuator 522 (e.g., where the fully retracted position of the implement interface 514 corresponds to the homing position of the tilt actuator 522). Therefore, the above discussion should be understood to also apply to homing operations with respect to the tilt actuator 522 or other actuators, with appropriate variations corresponding to the different positions and functional roles of the associated actuator(s).

[0112] Also refer to Figure 6 Some embodiments may include a method 600 for starting operations of a power machine, which in some cases may implement some or all of the homing functionality discussed above. In the illustrated example, at block 610, the method 600 may include operating the power machine in a starting mode, such as may correspond to a predetermined sequence of operations to transition the power machine from a de-energized state to a fully operational energized state or a fully enabled state.

[0113] When in the start-up mode, the method 600 may include receiving an operator input corresponding to an operator-requested movement of at least one electric actuator (e.g., one of the actuators 518, 522) to move a corresponding working element of the power machine at block 615. Upon receiving the operator input, the method 600 may include determining, at block 620, whether the operator input includes a non-zero component of the operator input corresponding to a home direction. For example, the method 600 may include determining whether the operator input for the lift actuator 518 corresponds to a non-zero lowering command (e.g., toward a fully lowered home position) or whether the operator input for the tilt actuator 522 corresponds to a non-zero command in a reeling direction (e.g., toward a fully reeled home position).

[0114] In some embodiments, the operator command may not correspond to a non-zero command in the reference direction. In such cases, the method 600 may sometimes include moving the associated actuator in the requested direction (e.g., raising the lift arm 504) in accordance with any associated constraints of the start-up mode (e.g., with respect to certain actuators having limited maximum speeds or reduced functionality). In some cases (e.g., alternatively), the method 600 may include not moving the associated actuator at all in accordance with a corresponding zero movement constraint of the start-up mode. For example, the method 600 may include preventing movement of the associated actuator, except as required by a homing operation, until the homing position has been reached (e.g., reached due to a subsequent operator movement received at block 615, determined at block 620 as commanded movement in the homing direction).

[0115] In some cases, under method 600, moving the actuator in a direction other than the home direction may include tracking the movement of the actuator based on the relative movement from the predicted position. For example, even if the home position has not yet been reached, the estimated starting position of the lift actuator 518 (e.g., as represented by a stored value from a previous shutdown sequence) can be used along with the relative movement as determined by the resolver 548 to track (e.g., estimate) the movement of the lift arm 504. Similar tracking based on sensed (or commanded) movement and a stored starting (or other) position can also be similarly implemented using different types of sensors or actuators.

[0116] While the power machine continues to operate in the start-up mode and the operator input continues to correspond to non-zero movement of the associated actuator in the associated home direction, method 600 may include, at block 630, commanding the associated actuator to move toward the home position. In some cases, the operation at block 630 may include commanding the actuator to move at or below a threshold home speed, which may be less than the actuator's maximum possible operating speed or maximum rated operating speed. For example, regardless of the commanded speed for lowering the lift arm 504 or reeling the implement interface 514, method 600 may include limiting the lowering speed or reeling speed, respectively, to at or below the associated threshold speed during the home movement (or, more generally, for movement before the home position has been reached). In some cases, such a threshold for the home (or pre-home) movement may be a deceleration threshold that is slower than the rated operating speed of the associated actuator (e.g., the maximum permissible speed for the actuator during normal towing or working operations). In some cases, method 600 may be implemented with different speed thresholds for different actuators, or for movement in different directions (e.g., having a lower speed threshold for movement away from the home direction than for movement toward the home direction, or vice versa).

[0117] Once the home position has been reached, method 600 may include tracking subsequent movement of the actuator based on the home position at block 640. For example, once the home position of the lift arm 504 has been reached, subsequent operation of the lift arm 504 may be controlled based on the home position (e.g., as indicated by a reference extension length of the lift actuator 518) and the tracked movement relative to the home position as indicated by the signal from the rotary transformer 548. If the home position is not reached due to a non-zero signal being removed before the home position is reached, a subsequent non-zero signal from an operator input may re-establish the home process. In some examples, the operator may be allowed to abort or bypass the home process.

[0118] In some cases, the functionality discussed above (e.g., as implemented in method 600 rather than at block 610) can advantageously be implemented outside of the context of a startup mode, or within startup mode but outside of the context of a machine being started from a normal power-off state. For example, in some cases, a homing operation as generally discussed above can be implemented after an operator has engaged a "release," "lift down," or other similar interface (e.g., a corresponding mechanical or virtual button) to automatically reposition a lift arm or other working element (e.g., not under power), or can be implemented after an operator has engaged an emergency stop of a powered machine.

[0119] As also noted above, some examples may include control systems or methods to compensate for travel-induced oscillations in a suspension system or to compensate for travel-induced fluctuations in the power demand of an electrical power source (e.g., as may involve oscillations in the suspension or also due to a vehicle without suspension), which may otherwise result in substantial component wear (e.g., capacitor burnout) and other problems. In particular, it has been discovered that selective operation under a control loop with a reduced (e.g., zero or effectively zero) integral control term for drive speed can provide substantial improvements in overall power management. In other words, in some examples, rather than using proportional-integral-derivative (PID) control to precisely control the drive speed of a drive actuator of a power machine, the control system may selectively control the drive speed with proportional rather than integral control (i.e., with a control loop without an integral term (e.g., no integral block or operation)), also referred to herein as a hydraulic simulation mode. Thus, for example, as implemented for the power machine 500, some examples of the disclosed technology can substantially reduce oscillations in the suspension system 540 and corresponding oscillations in the power flow of the electric power source 526 (e.g., ranging from full power delivery to maximum recharge) as compared to conventional control approaches. In some examples, for operation in the hydraulic simulation mode, the integral gain of the control loop used for the normal operating mode can be substantially reduced (i.e., reduced by more than 85%). In some examples, the integral gain for speed control in the hydraulic simulation mode can be effectively zero (i.e., have zero integral gain or no integral gain, or have an integral gain of less than 0.005). In some cases, as also noted below, the effectively zero integral gain in the hydraulic simulation mode can result in some steady-state errors, which in turn can cause the electric actuator (like the hydraulic actuator) to tend to drift slightly with respect to the load.

[0120] In some examples, the control system can be configured to selectively operate in different control modes based on the needs of a particular operation. For example, in some embodiments, an operator input can indicate whether to operate in a precise drive mode with PID control (and non-zero integral gain) or in a hydraulic simulation (or other similar) mode that can allow for more stable or efficient operation, although with some loss of precision due to the lack of integral control. It has been found that in many operations of power machines such as the power machines 100 and 200 described above, precise control of the travel speed of the power machine may not be required or even desired. For example, too precise control may result in fluctuating power demands as mentioned above. To offset the potential losses or other inefficiencies of such fluctuations, the so-called hydraulic simulation mode provides a drive response that is similar to the operation of a hydrostatic drive motor, with the added benefit of reducing power consumption and potential damage to the electronic components that provide power to the drive motor. On the other hand, in certain situations where precise operation is required, PID control can provide a more accurate travel speed. Thus, depending on the needs of the current (or currently commanded) operation, control may be selectively implemented in a hydraulic simulation mode with correspondingly reduced power fluctuations or in a default (or other) power mode with non-zero integral control and correspondingly improved accuracy.

[0121] Specifically, reference Figure 7 , some embodiments may include a method 700 for driving the operation of a power machine, which in some cases may implement some or all of the functionality discussed above. In the illustrated example, at block 710, the method 700 may include determining whether the power machine is operating in a particular drive mode (e.g., a precision drive mode, as shown). In some cases, as generally noted above, the method 700 may correspondingly include receiving an operator input indicating a selection of a mode (e.g., an explicit selection of a mode, or a lack of a change from a default mode) at block 712, and determining whether a particular mode is active based at least in part on the selection at block 710. In other cases, other parameters may additionally or alternatively influence the determination of a particular drive mode at block 710, including by monitoring the power consumption or other activity of various actuators. For example, some embodiments may automatically identify a particular mode of current or future operation based on identifying patterns in commanded or actual movement of non-traction or other actuators (e.g., movement of a lift or tilt actuator corresponding to a particular work operation, or no movement of a lift or tilt actuator combined with non-zero traction power consumption).

[0122] continue Figure 7For example, if the precision drive mode is active, method 700 may include, at block 720, controlling the drive speed with a PID control loop having a non-zero integral gain, such as may provide relatively precise control of travel speed and, therefore, may be particularly well-suited for operations requiring relatively fine speed control. In contrast, if the precision drive mode is not active (e.g., if the hydraulic simulation mode is active), method 700 may include, at block 730, controlling the drive speed without an integral control term (e.g., having proportional rather than integral control, or otherwise having zero integral gain). As noted above, operation at block 730 may therefore result in improved power management of the power source and other components of the power machine, as well as improved operator comfort and other benefits associated with smoother travel over terrain. Accordingly, depending on which drive mode is active (e.g., as selected by user input at block 712), the control system can selectively provide drive control with greater overall precision for improved performance of a particular traction operation, or drive control with reduced power fluctuations, including, for example, to reduce overall wear on the battery from high-amplitude power cycling. Thus, method 700 can provide selective control of drive operations for a power machine to match the needs of a particular work operation (e.g., to effectively balance control precision, power management, and operator comfort).

[0123] In some examples, an alternative implementation of non-integral control can correspond to operation of the power machine in a hydraulic simulation mode, in which certain actuators of the power machine are controlled to respond similarly to conventional hydraulic actuators. For example, in some hydraulic simulation modes, eliminating integral control of drive speed may cause the power machine to drift slightly along inclined terrain due to unavoidable hydraulic leakage, as does the hydraulic machine. In some examples, an alternative implementation of non-integral control can include continuing the implementation of the current control loop, but with a modified (e.g., zeroed) gain for the integral term.

[0124] As also noted above, some examples may include control systems or methods for improving the overall functionality of the lift arm and other working elements, including by allowing selective operation of specific working elements in a float mode. For example, when the float mode is active for the power machine 500, the lift actuator 518 may be controlled so as to permit movement of the lift arm 504 by an external force (e.g., gravity or contact with the ground), with the lift actuator 518 being powered as needed to slow, but not stop, such movement. Thus, for example, efficient float movement of the lift arm 504 may be achieved with minimal power loss due to unnecessary operation of the actuator 518.

[0125] Specifically, reference Figure 8 , some embodiments may include a method 800 for floating operation of a work element (e.g., a lift arm). In the illustrated example, at block 810, method 800 may include determining whether the power machine is operating in a float mode (e.g., a float mode for a lift arm as shown). In some cases, as generally noted above, method 800 may correspondingly include receiving operator input indicating a selection of a mode (e.g., an explicit selection of a float mode, or a lack of a change from a default float mode) at block 812, and determining whether a particular float mode is active based at least in part on the selection at block 810.

[0126] continue Figure 8 For example, if the float mode is active, the method 800 may include controlling the lift (or other) actuator according to the active float mode at block 820. Generally, as noted above, operating the lift arm in the float mode may include controlling the lift actuator so that the external force can move the lift arm within a set of applicable constraints. For example, if Figure 8 As illustrated in FIG. 8 (see curved bracket), controlling the lift actuator according to the float mode at block 820 may include controlling the lift actuator at block 822 such that the lift arm's movement speed remains below a threshold speed (e.g., such as corresponding to a threshold extension or retraction speed of the lift actuator). For example, based on the sensed movement speed of the lift arm in the float mode exceeding or approaching a threshold, method 800 may include providing a current to the electric lift actuator that partially opposes, but does not stop, movement. As another example, the method may provide a small amount of current to partially oppose gravity, regardless of the presence of any sensor sensing the lift arm's movement speed (e.g., so that the weight of the lift arm alone does not cause the lift arm to move toward the ground). In such a scenario, for example, while the actuator may be powered to maintain position against gravity, the actuator may generally not be powered to maintain position against additional external forces (in the direction of gravity) that exceed gravity. Similarly, in response to an external force that further opposes gravity (e.g., an upward contact force on the lift arm), the power provided to the actuator to maintain position against gravity may be reduced.

[0127] In some cases, controlling the lift actuator according to the float mode at block 820 may include controlling the lift actuator to not maintain the position of the lift arm at block 824. For example, if zero movement of the lift arm (e.g., lift arm 504) is detected, zero current may be provided to the associated lift arm actuator (e.g., actuator 518) such that the actuator does not provide any active force to maintain the lift arm in position. In this case, the lift arm may be free to move under the influence of gravity or contact with an external (e.g., ground) surface, in some cases without any control provided by the actuator.

[0128] In some cases, controlling the lift actuator according to the float mode at block 820 may include controlling the lift actuator at block 826 to provide non-actively powered movement of the lift arm, but the controller may provide some non-zero level of current to provide some upward force to partially counteract gravity. For example, while the lift actuator may be controlled to prevent high-speed movement of the lift arm due to application of an external load (e.g., gravity or ground contact) in the float mode (e.g., as discussed above), the lift actuator may also be controlled to actively actuate the lift actuator to resist the external load. In some cases, such active actuation may resist but not stop movement under the external load, but may not actively move the lift arm (i.e., not cause movement or supplement movement caused by the net external load). This may, for example, reduce the pressure applied by the lift arm to the ground or other external surface in the float mode.

[0129] Thus, the disclosed examples of power machines and components thereof can provide improvements over conventional designs. For example, some examples can provide improved calibration of a lift arm or other working element during startup operations, can help reduce power surges and associated negative effects, can also improve operator comfort during drive operations, and can provide improved functionality for powered working elements in float mode. Additional benefits will also be apparent to those skilled in the art in view of the overall disclosure.

[0130] Unless otherwise specified or limited, the terms "about" and "approximately" as used herein with respect to a reference value refer to a variation of ±15% or less relative to the reference value, including the endpoints of the range. Similarly, the term "substantially" as used herein with respect to a reference value refers to a variation of ±5% or less relative to the reference value, including the endpoints of the range.

[0131] Also as used herein, unless otherwise limited or defined, "or" indicates a non-exclusive list of components or operations that can exist in any combination, rather than an exclusive list of components that can exist only as alternatives to each other. For example, a list of "A, B, or C" indicates the following options: 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 an exclusive term such as "any," "one of," "only one of," or "exactly one of." For example, a list of "one of A, B, or C" indicates the following options: 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 related variations thereof) and including "or" to separate the listed elements indicates the option 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 the following options: 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 "plurality" (and variations thereof) and including "or" to separate the listed elements indicates the option of multiple instances of any or all of the listed elements. For example, the phrases "plurality of A, B, or C" and "two or more of A, B, or C" indicate the following options: A and B; B and C; A and C; and A, B, and C.

[0132] In some examples, aspects of the disclosed technology, including computerized implementations of methods according to the disclosed technology, can be implemented as systems, methods, apparatus, or articles 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 special-purpose processor chip; a single-core or multi-core chip; a microprocessor; a field programmable gate array; any combination of control units, arithmetic logic units, and processor registers, etc.), a computer (e.g., a processor device operably connected to a memory), or another electronically operated controller to implement the aspects detailed herein. Thus, for example, a configuration of the disclosed technology can be implemented as a set of instructions tangibly embodied on a non-transitory computer-readable medium such that a processor device can execute the instructions based on reading the instructions from the computer-readable medium. Some examples of the disclosed technology can include (or utilize) a control device consistent with the discussion below, such as an automation device, a special-purpose or general-purpose computer including various computer hardware, software, firmware, and the like. As specific examples, the control device may include a processor, a microcontroller, a field programmable gate array, a programmable logic controller, logic gates, and the like, as well as other typical components known in the art for implementing appropriate functionality (e.g., memory, communication systems, power sources, user interfaces and other inputs, etc.). In some examples, the control device may 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., engine controllers, implement controllers, drive controllers, etc.), including as part of a hub-and-spoke architecture or otherwise.

[0133] As used herein, the term "article of manufacture" is intended to encompass a computer program accessible from any computer-readable device, carrier (e.g., a non-transitory signal), or medium (e.g., a non-transitory medium). For example, computer-readable media can include, but are not limited to, magnetic storage devices (e.g., hard disks, floppy disks, magnetic strips, etc.), optical disks (e.g., compact disks (CDs), digital versatile disks (DVDs), etc.), smart cards, and flash memory devices (e.g., cards, sticks, etc.). Additionally, it should be understood that a carrier wave can be employed to carry computer-readable electronic data, such as that 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.

[0134] Certain operations of methods according to the disclosed technology or systems performing those methods may be schematically represented in the accompanying drawings or otherwise discussed herein. Unless otherwise specified or limited, specific operations represented in a particular spatial order in the accompanying drawings may not necessarily require that those operations be performed in a particular sequence corresponding to the particular spatial order. Correspondingly, certain operations represented in the accompanying drawings or otherwise disclosed herein may be performed in an order different from the order explicitly illustrated or described, as appropriate for the specific examples of the disclosed technology. In addition, in some examples, certain operations may be performed in parallel, including by dedicated parallel processing devices or separate computing devices configured to interoperate as part of a larger system.

[0135] As used herein in the context of computer implementations, unless otherwise specified or limited, the terms "component," "system," "module," "block," and the like are intended to encompass a portion or all of a computer-related system including hardware, software, a combination of hardware and software, or software in execution. For example, a component can be, but is not limited to, a processor device, a process executed (or executable) by a processor device, an object, an executable file, an execution thread, a computer program, or a computer. By way of illustration, both an application running on a computer and the computer can be components. One or more components (or systems, modules, etc.) can reside within an executing process or thread, can be located on one computer, can be distributed between two or more computers or other processor devices, or can be included within another component (or system, module, etc.).

[0136] Although the presently disclosed technology has been described with reference to preferred examples, workers skilled in the art will recognize that changes may be made in form and detail to the disclosed examples without departing from the spirit and scope of the concepts discussed herein.

Claims

1. A power machine comprising: Main frame; an electric power source, the electric power source being supported by the main frame; a drive system comprising: one or more drive motors powered by the electrical power source and operatively coupled to a traction element to provide traction power for traveling over terrain; and a suspension system securing the traction element to the main frame; and A control system comprising one or more control devices configured to control the drive speed of the one or more drive motors according to a first mode to perform precision operation, and to control the drive speed of the one or more drive motors according to a second mode to compensate for travel-induced oscillations on the suspension system, wherein, in the second mode, the control system controls the drive speed with a substantially reduced integral gain compared to the first mode.

2. The power machine according to claim 1, wherein: In the second mode, the control system controls the driving speed by implementing proportional control without an integral control term.

3. The power machine according to claim 1, wherein: In the second mode, the control system controls the drive speed using a proportional-integral-derivative (PID) control loop including an effectively zero integral gain.

4. The power machine according to claim 3, wherein: The control system is configured to implement the PID control loop with an effective non-zero integral gain in the first mode.

5. The power machine according to claim 4, wherein: The control system is configured to implement the PID control loop with zero integral gain in the first mode.

6. The power machine according to claim 1, wherein: The control system is configured to selectively operate in either the first mode or the second mode in response to an operator input indicating a selected one of the first mode or the second mode.

7. The power machine according to claim 1, wherein: The control system is configured to selectively operate in either the first mode or the second mode based on monitoring operation of one or more actuators of the power machine.

8. The power machine according to claim 1, wherein: The traction elements are track-type traction elements.

9. A method of controlling a drive operation of a power machine, the method comprising: receiving a selection of a first driving mode or a second driving mode; and causing the power machine to operate according to the selected first drive mode or second drive mode, wherein: In the first drive mode, speed control of one or more electric drive motors of the power machine is implemented by a proportional-integral-derivative (PID) control loop to perform precise operation; In the second drive mode, speed control of the one or more electric drive motors is implemented by a proportional control loop to compensate for travel-induced oscillations on a suspension system of the power machine; and In the second drive mode, the speed of the one or more electric drive motors is controlled with a substantially reduced integral gain compared to the first drive mode.

10. The method according to claim 9, wherein: The first driving mode is a precision control driving mode.

11. The method according to claim 9, wherein The second driving mode is a hydraulic simulation driving mode.

12. The method according to claim 9, wherein The second driving mode does not include a proportional-integral-derivative control loop.

13. The method according to claim 9, wherein: The proportional control loop corresponds to the PID control loop of the first drive mode implemented with an effective zero integral gain.

14. A method of controlling a drive operation of a power machine, the method comprising: receiving a selection of a precision control drive mode or a hydraulic simulation drive mode; and electronically controlling one or more drive motors powered by an electrical power source and operatively coupled to the traction element to provide traction power for traveling over terrain; wherein, in response to receiving a selection of the precision control drive mode, the one or more drive motors are electronically controlled with an effective non-zero integral gain to perform precision operation; and wherein, in response to receiving a selection of the hydraulically simulated drive mode, the one or more drive motors are electronically controlled with an effectively zero integral gain to compensate for travel-induced oscillations on a suspension system of the power machine.

15. The method according to claim 14, wherein The one or more drive motors are controlled by a first control loop having an effective non-zero integral gain in response to selection of the precision control drive mode, and the one or more drive motors are controlled by the first control loop having an effective zero integral gain in response to selection of the hydraulic simulation drive mode.

16. The method according to claim 15, wherein The one or more drive motors are controlled by the first control loop having zero integral gain in response to selection of the hydraulic simulated drive mode.

17. The method according to claim 14, wherein: In response to receiving the selection of the hydraulic simulated drive mode, the one or more drive motors are controlled with zero integral gain.

18. The method according to claim 14, wherein The one or more drive motors are controlled by a proportional-integral-derivative (PID) control loop having an effective zero integral gain in response to receiving the selection of the hydraulic simulated drive mode.

19. The method according to claim 14, wherein Receiving the selection includes receiving user input indicative of a commanded drive mode.

20. The method according to claim 19, wherein Receiving the selection includes automatically identifying the selection based on identifying commanded or actual movement of a non-traction actuator of the power machine.

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