Systems and methods for control of excavators and other power machines

Abstract

A power machine (100, 200, 400, 500) can include a lift arm assembly (502) that includes a hydraulic actuator (520), a hydraulic pump (504), an electric motor (506) configured to power rotation of the hydraulic pump (504), and a control system (508). The hydraulic pump (504) can be in hydraulic communication with the hydraulic actuator (520) to power movement of the lift arm assembly. The control system (508) can include one or more processor devices configured to selectively control operation of the hydraulic actuator in a flow control mode and a power control mode. In a flow control mode, the electric motor (506) can be controlled based on a target flow rate for flow of hydraulic fluid from the hydraulic pump to the hydraulic actuator. In a power control mode, the electric motor (506) can be controlled based one or more of on a target power consumption for the electric motor or a threshold motor speed.

Description

SYSTEMS AND METHODS FOR CONTROL OF EXCAVATORS AND OTHER POWER MACHINESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. provisional patent application no. 63 / 595,579, filed November 2, 2023, the entirety of which is incorporated herein by reference.BACKGROUND

[0002] This disclosure is directed toward power machines. More particularly, this disclosure is directed to excavators and control systems for excavators and workgroups thereof.

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

[0004] Excavators are a known type of power machine that generally have an undercarriage and a house that selectively rotates on the undercarriage. A lift arm, to which an implement can be attached, is operably coupled to the house and moveable under power with respect to the house. Excavators are also typically self-propelled vehicles. Typical excavators include one or more operator input devices (e.g., joysticks or pedals) that are physically moved by an operator to directly adjust hydraulic fluid flow through a particular component of the excavator (e.g., a control valve for an actuator for a lift arm) thereby adjusting the movement of a particular component (e.g., the lift arm). For example, a joystick can be physically coupled to a hydraulic valve through mechanical cables or linkages between the joystick and the hydraulic valve, or through hydraulic signals that are controlled by the joystick (i.e., the use of what is commonly known as pilot operated joysticks). Thus, for example, movement of the joystick can directly change the hydraulic valve position and thereby cause movement of an actuator and a component that is coupled to the actuator.

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

[0006] Some embodiments of the invention provide a power machine. The power machine can include a lift arm assembly, a hydraulic pump, an electric motor, and a control system. The lift arm assembly can include a hydraulic actuator. The hydraulic pump can be in hydraulic communication with the hydraulic actuator and configured to power movement of the lift arm assembly. The electric motor is configured to power rotation of the hydraulic pump. The control system includes one or more processor devices that is configured to selectively control operation of the hydraulic actuator. When in a flow control mode, the electric motor is controlled based on a target flow rate for flow of hydraulic fluid from the hydraulic pump to the hydraulic actuator. When in a power control mode, the electric motor is controlled based on a target power consumption for the electric motor.

[0007] In some examples, a power machine can include a lift arm assembly, a hydraulic pump, and a control system. The lift arm assembly can include a hydraulic actuator. The hydraulic pump can be in hydraulic communication with the hydraulic actuator and configured to power movement of the lift arm assembly. The electric motor can be arranged to power the rotation of the hydraulic pump. The control system can include a first pressure sensor, a second pressure sensor, and one or more processor devices. The first pressure sensor can be arranged to a sense a pump pressure. The second pressure sensor can be arranged to sense a load pressure. The one or more processor devices can be configured to control the electric motor based on a difference between the sensed pump pressure and the sensed load pressure in response to a requested movement of the lift arm assembly.

[0008] In some examples, a method of controlling operation of a work element of a power machine can include selectively controlling operation of an electric motor with one or more processor devices. The controlling operation of the electric motor can be in a flow control mode or a power control mode and the electric motor is arranged to power rotation of a hydraulic pump. The hydraulic pump is arranged to power a hydraulic actuator to move the work element. When in the flow control mode, the electric motor is controlled based on a target pressure differential between (i) a pump pressure that corresponds to an outlet from the hydraulic pump and (ii) a load pressure corresponding to a sensed load pressure of amain control valve. While in the power control mode, the electric motor is controlled based on a target power consumption for the electric motor.

[0009] In some examples, a power machine can include a lift arm assembly that includes a hydraulic actuator, a hydraulic pump in hydraulic communication with the hydraulic actuator and configured to power movement of the lift arm assembly, and an electric motor configured to power rotation of the hydraulic pump. A control system can include one or more processor devices configured to selectively control the electric motor for movement of the hydraulic actuator. A first target motor speed can be determined for a flow control mode, based on a target flow rate for flow of hydraulic fluid from the hydraulic pump to the hydraulic actuator. A second target motor speed can be determined for a power control mode, based on one or more of a target power consumption for the electric motor or a threshold motor speed. The electric motor can be controlled based on the smaller of the first and second target motor speeds.

[0010] In some examples, a power machine can include a lift arm assembly, a hydraulic pump, an electric motor, and a control system. The lift arm assembly includes a hydraulic actuator. The hydraulic pump in communication with the hydraulic actuator and can be configured to power movement of the lift arm assembly. The electric motor can be configured to power rotation of the hydraulic pump. The control system includes one or more processor devices that can be configured to selectively control the electric motor for operation of the hydraulic actuator. In a flow control mode, the one or more processors can control the electric motor based on a target flow rate for flow of hydraulic fluid from the hydraulic pump to the hydraulic actuator. In a power control mode, the one or more processors can control the electric motor based on one or more of a target power consumption for the electric motor or a threshold motor speed.

[0011] In some examples, while controlling operation of the electric motor in the flow control mode, the control system can determine a first power consumption of the electric motor and transition to controlling operation of the electric motor in the power control mode in response to determining that the first power consumption exceeds a first threshold power consumption.

[0012] In some examples, while controlling operation of the electric motor in the power control mode, the control system can determine a second power consumption of the electric motor and transition to controlling operation of the electric motor in the flow control mode in response to determining that the first power consumption does not exceed a second threshold power consumption.

[0013] In some examples, the control system can be configured to selectively control operation of the hydraulic actuator by determining a first target motor speed for the flow control mode, determining a second target motor speed for the power control mode and controlling the electric motor based on the smaller of the first and second target motor speeds, and optionally or preferably the first target motor speed for the flow control mode can be determined based on the target flow rate for flow of hydraulic fluid from the hydraulic pump to the hydraulic actuator or the second target motor speed for the power control mode can be determined based on one or more of the target power consumption for the electric motor or the threshold motor speed.

[0014] In some examples, the first target motor speed can be determined based on the target flow rate and a difference between the pump pressure and a load pressure associated with the hydraulic actuator, and the second target motor speed can be determined based on a pump pressure for the hydraulic pump.

[0015] In some examples, the flow control mode, the target flow rate can be based on an operator input that commands operation of the hydraulic actuator.

[0016] In some examples, in the flow control mode, the one or more processor devices can control the electric motor based on the target flow rate and a difference between a pump pressure and a load pressure associated with the hydraulic actuator.

[0017] In some examples, in the flow control mode, the one or more processor devices can control the electric motor to reduce motor speed in response to determining that the difference between the pump and load pressures exceeds a threshold pressure drop.

[0018] In some examples, the control system can further include a control valve, a first pressure sensor, and a second pressure sensor. The control valve can be configured to control flow from the hydraulic pump to the hydraulic actuator. The first pressure sensor can be configured to sense a fluid pressure corresponding to an inlet to the control valve for flow from the hydraulic pump. The third pressure sensor can be configured sense a fluid pressure corresponding to an outlet from the control valve to the hydraulic actuator. The one or more processor devices can be configured to determine the pump pressure based on signals from the first pressure sensor and determine the load pressure based on signals from the second pressure sensor, and optionally or preferably, the first and second pressure sensors can be integrated into the control valve.

[0019] In some examples, the lift arm assembly can be an excavator lift arm assembly including a boom and an arm pivotally supported by the boom. The hydraulic actuator canbe configured to move the boom relative to a frame of the power machine or to move the arm relative to the boom.

[0020] In some examples, the hydraulic pump can be a constant displacement pump.

[0021] In some examples, a method of controlling operation of a work element of a power machine can include selectively controlling operation of an electric motor, with one or more processor devices, in a flow control mode or a power control mode, the electric motor being arranged to power rotation of a hydraulic pump, the hydraulic pump being arranged to power a hydraulic actuator to move the work element. In the power control mode, the electric motor can be controlled based on a target power consumption for the electric motor. In the flow control mode, the electric motor is controlled based on a target pressure differential between (i) a pump pressure corresponding to an outlet from the hydraulic pump and (ii) a load pressure corresponding to the hydraulic actuator.

[0022] In some examples, the method can further include determining a present pressure differential between the pump pressure and the load pressure based on (i) data from a first pressure sensor configured to sense a fluid pressure upstream of or at an inlet to a control valve and (ii) data from a second pressure sensor configured to sense a fluid pressure downstream of or at an outlet from the control valve. In the flow control mode, controlling the motor based on the target pressure differential includes controlling the electric motor based on a comparison between the present pressure differential and the target pressure differential.

[0023] In some examples, in the power control mode, controlling the electric motor based on the target power consumption can include controlling the electric motor based on data from the either of the first pressure sensor or the second pressure sensor.

[0024] In some examples, selectively controlling operation of the electric motor in the flow control mode or the power control mode can include determining a first target motor speed for the flow control mode, determining a second target motor speed for the power control mode, and controlling the electric motor based on the smaller of the first and second target motor speeds.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following drawings are provided to help illustrate various features of nonlimiting examples of the disclosure and are not intended to limit the scope of the disclosure or exclude alternative implementations.

[0026] FIG. 1 is a block diagram illustrating functional systems of a representative power machine on which embodiments of the present disclosure can be practiced.

[0027] FIG. 2 is a front left perspective view of a representative power machine in the form of an excavator on which the disclosed embodiments can be practiced.

[0028] FIG. 3 is a rear right perspective view of the excavator of FIG. 2.

[0029] FIG. 4 is a schematic illustration of a control system for a power machine.

[0030] FIG. 5 is a block diagram illustrating an example configuration of operational systems of a power machine, according to examples of the disclosed technology.

[0031] FIG. 5 A is a top plan, partly schematic view of an example control valve for the systems of FIG. 5.

[0032] FIGS. 6 through 8 are schematic illustrations of example control methods for hydraulic operations of the power machine of FIG. 5, according to examples of the disclosed technology.

[0033] FIG. 9 is a diagram showing example traces of pressure differential, commanded motor speed, and actual motor speed during operation of the power machine of FIG. 5 or the methods of FIGS. 6 through 8.

[0034] FIG. 10 is a diagram of example power control relationships for use with the methods of FIGS. 6 through 8.

[0035] FIG. 11 is a diagram of further example power control relationships for use with the methods of FIGS. 6 through 8, including different power control modes.

[0036] FIGS. 12 through 18 are diagrams of further example traces of speed and pressure parameters during operation of the power machine of FIG. 5 or the methods of FIGS. 6 through 8.DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE

[0037] The concepts disclosed in this discussion are described and illustrated by referring to exemplary embodiments. These concepts, however, are not limited in their application to the details of construction and the arrangement of components in the illustrative embodiments and are capable of being practiced or being carried out in various other ways.

[0038] In typical excavators (and other power machines) operators can control the operation of hydraulic components by adjusting a master control valve for the relevant hydraulic flow system. However, such systems generally do not include corresponding control of pump- or engine-speed relative to operation of hydraulic components (e.g.,hydraulic actuators for lift arm assemblies or other workgroup actuators). In other words, operators may control flow through a valve to cause particular movements of workgroup or other actuators, but may not generally apply corresponding control of engine speed or pump speed. Rather, for example, the hydraulic pump may simply rotate with (and powered by) the engine, and engine speed may be separately controlled according to various approaches unrelated to pump operation (e.g., with engine speed control to maintain a constant optimal speed).

[0039] In particular, as described above, typical excavators can include one or more operator input devices that are directly physically coupled (e.g., mechanically or hydraulically coupled) to the hydraulic system of the excavator. For example, each of several operator input devices can be physically coupled to one or more hydraulic valves for controlling operation of one or more actuators (e.g., a boom cylinder, an arm cylinder, a bucket cylinder, an auxiliary cylinder, a tractive assembly, etc.). Thus, physical movement of the operator input device can directly adjust the position of the one or more hydraulic valves to result in a movement (e.g., extension, retraction, etc.) of the one or more actuators.

[0040] While this type of conventional configuration can offer some advantages, directly physically coupled inputs can also introduce disadvantages. For example, precise or complex control of hydraulic operations may be difficult when controlled solely through mechanical or hydraulic-pilot operation of a hydraulic control valve. Accordingly, it may be useful to implement electronic power and control for some hydraulic operations.

[0041] Correspondingly, some embodiments according to this disclosure can implement electronic control for hydraulic operations to improve system performance and ease of operation. In particular, some embodiments of the disclosure can provide an electrically powered power machine (e.g., battery powered excavator) that includes an electric motor arranged to power a hydraulic system. More specifically, the electric motor can be used to power a hydraulic pump, which in turn can provide a corresponding hydraulic flow to a control valve for a set of workgroup (or other) actuators.

[0042] With this arrangement, the electric motor can be controlled according to various feedback loops to provide improved operation of various hydraulic actuators of the hydraulic system (e.g., improved responsiveness to operator commands for lift arm movements or other workgroup tasks, or improved avoidance of stall during heavy loading of particular actuators). In some cases, a rotational speed of the electric motor - and thereby a rotational speed of the hydraulic pump - can be controlled based on relevant (e.g., sensed)loading conditions of the workgroup. For example, loading conditions for a workgroup can be determined based on pressure measurements for a hydraulic system of the workgroup (e.g., using pressure sensors to determine a pressure at the relevant pump and at the relevant actuator), and then a speed of the electric motor can be controlled accordingly (e.g., independently of an operator input from a hydraulic input, mechanical input, or electrohydraulic input). In some particular examples, a constant displacement gear pump, or other constant displacement pump (e.g., constant displacement piston pump), can be powered by an electric motor so that motor speed is directly correlated to flow rate through the pump. The speed of the electric motor can then be controlled based on loading conditions of one or more actuators for an excavator lift arm assembly (e.g., a boom actuator), to actively adjust pump speed in accordance with present operating conditions. In other examples, however, other approaches are also possible, including for systems with other types of pumps or relative to other hydraulically powered systems of a power machine (e.g., other workgroup systems, other tractive systems, or hydraulic systems of other types of power machines)

[0043] In some cases, a control system can be configured to selectively control an electric motor in different modes, depending on loading conditions at a workgroup or other part of a hydraulic system. For example, some control systems according to the disclosed technology can selectively operate in a flow control mode to prioritize providing a target flow rate, or in a power control mode to prioritize appropriate power consumption, depending on present operating conditions. In other words, in response to particular operating conditions or operator commands, a control system can selectively apply different criteria for control of an electric motor, to selectively target: (a) providing hydraulic flow to match operator demand or (b) ensuring that the electric motor operates without excessive power demand (e.g., to prevent stall conditions when operator commands correspond to excessive loading of a workgroup actuator). Thus, for example, a control system may in some cases control motor speed to intentionally reduce flow relative to an operator command or other indicator of flow demand, so that power consumed by the motor for the hydraulic operations is appropriately limited.

[0044] In some cases, control of an electric motor to operate a hydraulic pump can be based on a loading condition of a workgroup component. In particular motor speed can be determined in some cases based on a loading condition of a relevant actuator that is powered by the pump (e.g., a boom actuator or other actuator of an excavator lift arm assembly). Thus, in some cases, a current signal to the electric motor (i.e., as correspondsto the power draw by the motor) can be controlled based on the hydraulic pressure of a relevant hydraulic actuator.

[0045] In particular, in some implementations of a flow control mode, a controller (e.g., using load sensing software) can determine a load pressure or a load pressure differential between a first (pump) pressure at an outlet of a workgroup pump (or inlet of a master control valve) and a second (load) pressure at an outlet of the master control valve (or inlet of a relevant hydraulic actuator). As actuators of a workgroup are subjected to loading, the controller can then control motor speed based on the load pressure or load pressure differential, to selectively provide a desired flow rate or to avoid spikes above a power threshold (e.g., to prevent stall). In some cases, a motor speed can be controlled based on load pressure in combination with a torque signal from an inverter of the motor (e.g., a current signal corresponding to torque), with torque and pressure being correlated by known factors). However, some inverters may somewhat aggressively filter such a torque signal, which may complicate the use of that signal in the noted approach.

[0046] Further in this regard, decreases in load pressure differential can generally correspond to conditions of insufficient flow, and the electric motor speed can thus be increased in response to decreasing pressure (or pressure differential) to provide additional flow through the associated pump. For example, in response to a user command for a lift arm movement, flow demand for an actuator of the lift arm may increase relative to a present flow rate. Correspondingly, a pressure differential between pump pressure and a load pressure at the lift arm actuator may decrease. In some implementations of the disclosed technology, electric motor speed can thus be controlled to increase in response to a sensed reduction in pressure differential, to cause the pump to approach a desired (increased) flow rate. Conversely, an increase in load pressure or pressure differential can generally correspond to conditions of excess flow. Thus, the electric motor speed can be decreased in response to increasing load pressure or pressure differential to provide less flow. For example, continuing discussion from above, as flow demand for the lift arm movement decreases relative to a present flow rate, the load pressure differential between the pump pressure and the load pressure at the lift arm actuator may correspondingly increase. Electric motor speed can thus be controlled to decrease, in response to a sensed increased in pressure differential, to operate the pump in accordance with the decreased flow demand.

[0047] In a power control mode, a controller can generally adjust pump speed - via control of the electric motor - to ensure that loading from hydraulic operations does notrequire excessive power (e.g., does not require power draw at the motor that exceeds a threshold rate). Thus, a target motor speed under a power control mode may in some cases vary from a target motor speed under a flow control mode (e.g., to match flow demand in response to pressure changes, as discussed above). In some approaches in particular, an operating (e.g., outlet) pressure of the hydraulic pump, or a pump torque, can be measured during hydraulic operations, as an indicator of the power required for operation of the pump. Electric motor speed can then be controlled accordingly to prevent operation at motor speeds that would require excessive power at the motor (e.g., would require power in excess of a power consumption threshold, or tend to cause the motor to stall due to operation in lower-torque states).

[0048] Thus, for example, a controller can adaptively control an electric motor relative to an operator command corresponding to a flow corresponding that would cause excess power consumption by the electric motor relative to a threshold or other criterion, or would (similarly) result in a motor speed that is above a relevant threshold motor speed (e.g., a threshold that varies based on pump pressure or other operating condition) and may thus result in loss of torque or increased risk of stall. Correspondingly, for example, electric motor speed can be limited under power control mode to prioritize continued operation over provision of a maximum desired flow.

[0049] In some examples, a control system operating in a power control mode can provide lower pump flow rates, via lower operating speeds of an electric motor, than would be required to match the flow demand corresponding to a present operator command. In some cases, such lower motor speeds can be determined directly based on a target power consumption (e.g., based on relationships between speed and pump pressure, as further detailed below). In some cases, such lower motor speeds can be determined in other ways, including based on a target maximum motor speed threshold that sets a control ceiling on motor speed. Such a motor speed threshold, for example, may in turn be predetermined (or calculated in real time) based on a relationship between speed and pressure, or other operational characteristics of the relevant system (e.g., and may accordingly vary depending on a current operating state of a power machine). In some examples, a relatively low maximum motor speed threshold can be predetermined as a motor speed that corresponds to a particular maximum power consumption for a given pressure, or to another relevant performance characteristic.

[0050] In particular, some control systems can be configured to control motor speed in a flow control mode as a default, and to selectively transition to control of motor speed ina power control mode based on the occurrence of particular conditions. For example, a control system can be configured to determine a first motor speed corresponding to flow control (e.g., a motor speed required to provide 100% of user-demanded flow or 100% of a maximum rated flow). The control system can also determine a second motor speed corresponding to power control (e.g., a motor speed that would provide a maximum rated power). The control system can then compare the first and second motor speeds to determine an actual target motor speed, and provide signals to control the motor accordingly. For example, to prioritize avoidance of stall, some control systems can selectively control a motor to operate at (or below) the lower of (i) a first motor speed corresponding to a flow control mode and (ii) a second motor speed corresponding to a power control mode. In other approaches, however, other transition criteria may also (or alternatively) apply.

[0051] These concepts can be practiced on various power machines, as will be described below. A representative power machine on which the embodiments can be practiced is illustrated in diagram form in FIG. 1 and one example of such a power machine is illustrated in FIGS. 2-3 and described below before any embodiments are disclosed. For the sake of brevity, only one power machine is discussed. However, as mentioned above, the embodiments below can be practiced on any of a number of power machines, including power machines of different types from the representative power machine shown in FIGS. 2-3. Power machines, for the purposes of this discussion, include a frame, at least one work element, and a power source that can provide power to the work element to accomplish a work task. One type of power machine is a self-propelled work vehicle. Self-propelled work vehicles are a class of power machines that include a frame, work element, and a power source that can provide power to the work element. At least one of the work elements is a motive system for moving the power machine under power.

[0052] Referring now to FIG. 1, a block diagram illustrates the basic systems of a power machine 100 upon which the embodiments discussed below can be advantageously incorporated and can be any of several distinct types of power machines. The block diagram of FIG. 1 identifies various systems on power machine 100 and the relationship between various components and systems. As mentioned above, at the most basic level, power machines for the purposes of this discussion include a frame, a power source, and a work element. The power machine 100 has a frame 110, a power source 120, and a work element 130. Because power machine 100 shown in FIG. 1 is a self-propelled work vehicle, it also has tractive elements 140, which are themselves work elements provided to move the powermachine over a support surface and an operator station 150 that provides an operating position for controlling the work elements of the power machine. A control system 160 is provided to interact with the other systems to perform various work tasks at least in part in response to control signals provided by an operator.

[0053] Certain work vehicles have work elements that can perform a dedicated task. For example, some work vehicles have a lift arm to which an implement such as a bucket is attached such as by a pinning arrangement. The work element, e.g., the lift arm, can be manipulated to position the implement for performing the task. The implement, in some instances can be positioned relative to the work element, such as by rotating a bucket relative to a lift arm, to further position the implement. Under normal operation of such a work vehicle, the bucket is intended to be attached and under use. Such work vehicles may be able to accept other implements by disassembling the implement / work element combination and reassembling another implement in place of the original bucket. Other work vehicles, however, are intended to be used with a wide variety of implements and have an implement interface such as implement interface 170 shown in FIG. 1. At its most basic, implement interface 170 is a connection mechanism between the frame 110 or a work element 130 and an implement, which can be as simple as a connection point for attaching an implement directly to the frame 110 or a work element 130 or more complex, as discussed below.

[0054] On some power machines, implement interface 170 can include an implement carrier, which is a physical structure movably attached to a work element. The implement carrier has engagement features and locking features to accept and secure any of several implements to the work element. One characteristic of such an implement carrier is that once an implement is attached to it, it is fixed to the implement (i.e. not movable with respect to the implement) and when the implement carrier is moved with respect to the work element, the implement moves with the implement carrier. The term implement carrier is not merely a pivotal connection point, but rather a dedicated device specifically intended to accept and be secured to various different implements. The implement carrier itself is mountable to a work element 130 such as a lift arm or the frame 110. Implement interface 170 can also include one or more power sources for providing power to one or more work elements on an implement. Some power machines can have a plurality of work elements with implement interfaces, each of which may, but need not, have an implement carrier for receiving implements. Some other power machines can have a work element with a plurality of implement interfaces so that a single work element can accept a pluralityof implements simultaneously. Each of these implement interfaces can, but need not, have an implement carrier.

[0055] Frame 110 includes a physical structure that can support various other components that are attached thereto or positioned thereon. The frame 110 can include any number of individual components. Some power machines have frames that are rigid. That is, no part of the frame is movable with respect to another part of the frame. Other power machines have at least one portion that can move with respect to another portion of the frame. For example, excavators can have an upper frame portion that rotates about a swivel with respect to a lower frame portion. Other work vehicles have articulated frames such that one portion of the frame pivots with respect to another portion for accomplishing steering functions. In exemplary embodiments, at least a portion of the power source is located in the upper frame or machine portion that rotates relative to the lower frame portion or undercarriage. The power source provides power to components of the undercarriage portion through the swivel.

[0056] Frame 110 supports the power source 120, which can provide power to one or more work elements 130 including the one or more tractive elements 140, as well as, in some instances, providing power for use by an attached implement via implement interface 170. Power from the power source 120 can be provided directly to any of the work elements 130, tractive elements 140, and implement interfaces 170. Alternatively, power from the power source 120 can be provided to a control system 160, which in turn selectively provides power to the elements that are capable of using it to perform a work function. Power sources for power machines typically include an engine such as an internal combustion engine and a power conversion system such as a mechanical transmission or a hydraulic system that can convert the output from an engine into a form of power that is usable by a work element. Other types of power sources can be incorporated into power machines, including electrical sources or a combination of power sources, known generally as hybrid power sources.

[0057] FIG. 1 shows a single work element designated as work element 130, but various power machines can have any number of work elements. Work elements are typically attached to the frame of the power machine and movable with respect to the frame when performing a work task. In addition, tractive elements 140 are a special case of work element in that their work function is generally to move the power machine 100 over a support surface. Tractive elements 140 are shown separate from the work element 130 because many power machines have additional work elements besides tractive elements,although that is not always the case. Power machines can have any number of tractive elements, some or all of which can receive power from the power source 120 to propel the power machine 100. Tractive elements can be, for example, wheels attached to an axle, track assemblies, and the like. Tractive elements can be rigidly mounted to the frame such that movement of the tractive element is limited to rotation about an axle, or steerably mounted to the frame to accomplish steering by pivoting the tractive element with respect to the frame. In contrast to tractive elements and actuators, workgroup actuators and elements are configured to provide powered movement of one or more components of a power machine for work operations (i.e., other than for travel of the power machine over terrain). Correspondingly, “workgroup function” refers to one or more functions that relate to movement of one or more components of a power machine other than for travel of the power machine over terrain.

[0058] Power machine 100 includes an operator station 150, which provides a position from which an operator can control operation of the power machine. In some power machines, the operator station 150 is defined by an enclosed or partially enclosed cab. Some power machines on which the disclosed embodiments may be practiced may not have a cab or an operator compartment of the type described above. For example, a walk behind loader may not have a cab or an operator compartment, but rather an operating position that serves as an operator station from which the power machine is properly operated. More broadly, power machines other than work vehicles may have operator stations that are not necessarily similar to the operating positions and operator compartments referenced above. Further, some power machines such as power machine 100 and others, whether they have operator compartments or operator positions, may be capable of being operated remotely (i.e. from a remotely located operator station) instead of or in addition to an operator station adjacent or on the power machine. This can include applications where at least some of the operator-controlled functions of the power machine can be operated from an operating position associated with an implement that is coupled to the power machine. Alternatively, with some power machines, a remote-control device can be provided (i.e. remote from both of the power machine and any implement to which is it coupled) that can control at least some of the operator-controlled functions on the power machine.

[0059] FIGS. 2-3 illustrate an excavator 200, which is one particular example of a power machine of the type illustrated in FIG. 1, on which the disclosed embodiments can be employed. Unless specifically noted otherwise, embodiments disclosed below can be practiced on a variety of power machines, with the excavator 200 being only one of thosepower machines. Excavator 200 is described below for illustrative purposes. Not every excavator or power machine on which the illustrative embodiments can be practiced need have all the features or be limited to the features that excavator 200 has. Excavator 200 has a frame 210 that supports and encloses a power system 220 (represented in FIGS. 2-3 as a block, as the actual power system is enclosed within the frame 210). The power system 220 includes an engine that provides a power output to a hydraulic system. The hydraulic system acts as a power conversion system that includes one or more hydraulic pumps for selectively providing pressurized hydraulic fluid to actuators that are operably coupled to work elements in response to signals provided by operator input devices. The hydraulic system also includes a control valve system that selectively provides pressurized hydraulic fluid to actuators in response to signals provided by operator input devices. The excavator 200 includes a plurality of work elements in the form of a first lift arm structure 230 and a second lift arm structure 330 (not all excavators have a second lift arm structure). In addition, excavator 200, being a work vehicle, includes a pair of tractive elements in the form of left and right track assemblies 240A and 240B, which are disposed on opposing sides of the frame 210.

[0060] An operator compartment or other station 250 is defined in part by a cab 252, which is mounted on the frame 210. The cab 252 shown on excavator 200 is an enclosed structure, but other operator compartments need not be enclosed. For example, some excavators have a canopy that provides a roof but is not enclosed A control system, shown as block 260, is provided for controlling the various work elements. Control system 260 includes operator input devices, which interact with the power system 220 to selectively provide power signals to actuators to control work functions on the excavator 200. In some embodiments, the operator input devices include at least two two-axis operator input devices to which operator functions can be mapped.

[0061] Frame 210 includes an upper frame portion or house 211 that is pivotally mounted on a lower frame portion or undercarriage 212 via a swivel joint. The swivel joint includes a bearing, a ring gear, and a slew motor with a pinion gear (not pictured) that engages the ring gear to swivel the machine. The slew motor receives a power signal from the control system 260 to rotate the house 211 with respect to the undercarriage 212. House 211 is capable of unlimited rotation about a swivel axis 214 under power with respect to the undercarriage 212 in response to manipulation of an input device by an operator. Hydraulic conduits are fed through the swivel joint via a hydraulic swivel to providepressurized hydraulic fluid to the tractive elements and one or more work elements such as lift arm 330 that are operably coupled to the undercarriage 212.

[0062] The first lift arm structure 230 is mounted to the house 211 via a swing mount 215. (Some excavators do not have a swing mount of the type described here.) The first lift arm structure 230 is a boom-arm lift arm of the type that is generally employed on excavators although certain features of this lift arm structure may be unique to the lift arm illustrated in FIGS. 2-3. The swing mount 215 includes a frame portion 215 A and a lift arm portion 215B that is rotationally mounted to the frame portion 215 A at a mounting frame pivot 231 A. A swing actuator 233 A is coupled to the house 211 and the lift arm portion 215B of the mount. Actuation of the swing actuator 233A causes the lift arm structure 230 to pivot or swing about an axis that extends longitudinally through the mounting frame pivot 231 A.

[0063] The first lift arm structure 230 includes a first portion 232, known generally as a boom, and a second portion 234, known as an arm or a dipper. The boom 232 is pivotally attached on a first end 232A to mount 215 at boom pivot mount 23 IB. A boom actuator 233B is attached to the mount 215 and the boom 232. Actuation of the boom actuator 233B causes the boom 232 to pivot about the boom pivot mount 23 IB, which effectively causes a second end 232B of the boom to be raised and lowered with respect to the house 211. A first end 234A of the arm 234 is pivotally attached to the second end 232B of the boom 232 at an arm mount pivot 231C. An arm actuator 233C is attached to the boom 232 and the arm 234. Actuation of the arm actuator 233C causes the arm to pivot about the arm mount pivot 231C. Each of the swing actuator 233 A, the boom actuator 233B, and the arm actuator 233C can be independently controlled in response to control signals from operator input devices.

[0064] An exemplary implement interface 270 is provided at a second end 234B of the arm 234. The implement interface 270 includes an implement carrier 272 that can accept and securing a variety of different implements to the lift arm 230. Such implements have a machine interface that is configured to be engaged with the implement carrier 272. The implement carrier 272 is pivotally mounted to the second end 234B of the arm 234. An implement carrier actuator 233D is operably coupled to the arm 234 and a linkage assembly 276. The linkage assembly includes a first link 276 A and a second link 276B. The first link 276A is pivotally mounted to the arm 234 and the implement carrier actuator 233D. The second link 276B is pivotally mounted to the implement carrier 272 and the first link 276A.The linkage assembly 276 is provided to allow the implement carrier 272 to pivot about the arm 234 when the implement carrier actuator 233D is actuated.

[0065] The implement interface 270 also includes an implement power source (not shown in FIGS. 2-3) available for connection to an implement on the lift arm structure 230. The implement power source includes pressurized hydraulic fluid port to which an implement can be coupled. The pressurized hydraulic fluid port selectively provides pressurized hydraulic fluid for powering one or more functions or actuators on an implement. The implement power source can also include an electrical power source for powering electrical actuators and / or an electronic controller on an implement. The electrical power source can also include electrical conduits that are in communication with a data bus on the excavator 200 to allow communication between a controller on an implement and electronic devices on the excavator 200. It should be noted that the specific implement power source on excavator 200 does not include an electrical power source. However, in some configurations, the specific implement power source or other power sources of an excavator or other power machine can include an electrically powered actuator, for example, when the excavator is an electrically powered work vehicle that includes an electrical power storage device (e.g., a battery). Correspondingly, control of actuators in some cases may not necessarily require control of hydraulic flow (e.g., may be accomplished via electronic control of an electronic actuator by a control device).

[0066] The lower frame 212 supports and has attached to it a pair of tractive elements 240, identified in FIGS. 2-3 as left track drive assembly 240 A and right track drive assembly 240B. Each of the tractive elements 240 has a track frame 242 that is coupled to the lower frame 212. The track frame 242 supports and is surrounded by an endless track 244, which rotates under power to propel the excavator 200 over a support surface. Various elements are coupled to or otherwise supported by the track 242 for engaging and supporting the track 244 and cause it to rotate about the track frame. For example, a sprocket 246 is supported by the track frame 242 and engages the endless track 244 to cause the endless track to rotate about the track frame. An idler 245 is held against the track 244 by a tensioner (not shown) to maintain proper tension on the track. The track frame 242 also supports a plurality of rollers 248, which engage the track and, through the track, the support surface to support and distribute the weight of the excavator 200. An upper track guide 249 is provided for providing tension on track 244 and preventing the track from rubbing on track frame 242.

[0067] A second, or lower, lift arm 330 is pivotally attached to the lower frame 212. A lower lift arm actuator 332 is pivotally coupled to the lower frame 212 at a first end 332A and to the lower lift arm 330 at a second end 332B. The lower lift arm 330 is configured to carry a lower implement 334, which in one embodiment is a blade as is shown in FIGS. 2- 3. The lower implement 334 can be rigidly fixed to the lower lift arm 330 such that it is integral to the lift arm. Alternatively, the lower implement can be pivotally attached to the lower lift arm via an implement interface, which in some embodiments can include an implement carrier of the type described above. Lower lift arms with implement interfaces can accept and secure various different types of implements thereto. Actuation of the lower lift arm actuator 332, in response to operator input, causes the lower lift arm 330 to pivot with respect to the lower frame 212, thereby raising and lowering the lower implement 334.

[0068] Upper frame portion 211 supports cab 252, which defines, at least in part, operator compartment or station 250. A seat 254 is provided within cab 252 in which an operator can be seated while operating the excavator. While sitting in the seat 254, an operator will have access to a plurality of operator input devices 256 that the operator can manipulate to control various work functions, such as manipulating the lift arm 230, the lower lift arm 330, or the tractive elements 240, pivoting the house 211, the tractive elements 240, and so forth.

[0069] Excavator 200 provides a variety of different operator input devices 256 to control various functions. For example, hydraulic joysticks are provided to control the lift arm 230 and swiveling of the house 211 of the excavator. Foot pedals with attached levers are provided for controlling travel and lift arm swing. Electrical switches are located on the joysticks for controlling the providing of power to an implement attached to the implement carrier 272. Other types of operator inputs that can be used in excavator 200 and other excavators and power machines include, but are not limited to, switches, buttons, knobs, levers, variable sliders, and the like. The specific control examples provided above are exemplary in nature and not intended to describe the input devices for all excavators and what they control.

[0070] Display devices are provided in the cab to give indications of information relatable to the operation of the power machines in a form that can be sensed by an operator, such as, for example audible and / or visual indications. Audible indications can be made in the form of buzzers, bells, and the like or via verbal communication. Visual indications can be made in the form of graphs, lights, icons, gauges, alphanumeric characters, and the like. Displays can provide dedicated indications, such as warning lights or gauges, or dynamicto provide programmable information, including programmable display devices such as monitors of various sizes and capabilities. Display devices can provide diagnostic information, troubleshooting information, instructional information, and various other types of information that assists an operator with operation of the power machine or an implement coupled to the power machine. Other information that may be useful for an operator can also be provided.

[0071] The description of power machine 100 and excavator 200 above is provided for illustrative purposes, to provide illustrative environments on which the embodiments discussed below can be practiced. While the embodiments discussed can be practiced on a power machine such as is generally described by the power machine 100 shown in the block diagram of FIG. 1 and more particularly on an excavator such as excavator 200, unless otherwise noted, the concepts discussed below are not intended to be limited in their application to the environments specifically described above.

[0072] In some embodiments, sensors of other known types can be arranged to measure parameters relating to a current orientation of a workgroup or other system of a power machine, including to measure angular orientations of various components of a lift arm. For example, as shown in FIG. 3, the excavator 200 can include angle sensors 235, 237, 239 each of which can determine the relative orientation of specific components of the work group of the excavator 200. For example, the angle sensor 235 can be coupled to the swing mount 215 at the boom pivot mount 23 IB and can sense the angle between the swing mount 215 and the boom 232 (e.g., relative to a line parallel to the end 232A of the boom 232). As another example, the angle sensor 237 can be coupled to the boom 232 at the arm mount pivot 231C and can sense the angle between the boom 232 (e.g., relative to a line parallel to the end 232B of the boom 232) and the arm 234 (e.g., relative to a line parallel to the end 234A of the arm 234). As yet another example, the angle sensor 239 can be coupled to the arm 234 at an implement interface pivot mount 23 ID and can sense the angle between the arm 234 (e.g., relative to a line parallel to the end 234B of the arm 234) and the implement carrier 272 (e.g., relative to a line parallel to a cutting angle of a bucket (not shown) secured to the implement carrier 272).

[0073] Referring also to FIG. 2, the excavator 200 can also include angle sensors 241, 243. The angle sensor 241 can be coupled to the swing mount 215 at the mounting frame pivot 231 A and can sense the angle between the frame portion 215 A and the swing mount 215 to sense a boom offset angle for the excavator 200 (i.e., to indicate rotation of the lift arm 230 about an offset axis that is parallel to the axis 214 relative to the house 211). Theangle sensor 243, which is obstructed from view in FIGS. 2 and 3, can be coupled to the undercarriage 212 (or the house 211) and can sense the angle between the house 211 and the undercarriage 212. In some cases, this angle can be considered the slew angle for the excavator 200 (i.e., the rotational position of the excavator about axis 214, relative to a neutral location).

[0074] As further discussed below, signals from the angle sensors 235, 237, 239, 241, 243 can be processed in known ways to determine a current orientation of the implement carrier 272 or other components relative to a reference frame (e.g., a fixed frame defined by undercarriage 212. In some cases, orientation of a particular component can be determined from the perspective of the excavator 200 in isolation. In some cases, orientation of a particular component can be determined relative to a surrounding environment. For example, based on a known position of the excavator 200 in an environment, and known dimensions of the undercarriage 212, the track drive assemblies 240A, 240B, and other excavator components, signals from the angle sensors 235, 237, 239, 241, 243 can be analyzed to specify a position of any part of the lift arm 230 relative to the environment.

[0075] In different embodiments, the angle sensors 235, 237, 239, 241, 243 can be implemented in different ways. For example, each angle sensor 235, 237, 239, 241, 243, can be a hall-effect sensor, a torque sensor, an accelerometer, a rotary encoder, etc. Further, in some cases, non-rotational sensors can be used. For example, data from linear displacement or other position sensors (not shown) on various actuators for the lift arm 230 can be used in combination with known dimensions of the excavator 200 to specify relevant triangular identities for the lift arm 230 and thereby also indicate the angular orientation of particular components and the relative (or absolute) orientation of any particular part of the lift arm 230. Regardless of the specific sensor configuration, however, various known kinematic approaches can be used to determine a current orientation of any particular lift arm (or other) component based on measurements from the angle sensors 235, 237, 239, 241, 243 (or others, including sensors (not shown) for the lower lift arm 330) and known geometries of relevant one or more relevant components (e.g., the boom 232, the arm 234, the implement interface 270, an implement coupled to the implement interface 270, the frame portion 215A, the house 211, a distance between the sensors 241, 243, etc.).

[0076] FIG. 4 shows a schematic illustration of a control system 400 for an excavator (or other power machine), as can be implemented as a specific example of the control system 160 (see FIG. 1), or a portion thereof. The control system 400 can include one ormore operator input devices 402, a hydraulic (or other actuation) system 403, and a control device 408. The operator input devices 402 can be implemented in different ways, including as one or more joysticks, one or more pedals, or other known types of devices for receiving input from operators for control of components of a power machine.

[0077] In one embodiment, as shown in FIG. 4, the operator input devices 402 can include joysticks 404, 406. Each joystick 404, 406 can be located within a cab of the excavator (e.g., the cab 252 of FIG. 3), and each can be pivoted about at least two axes to adjust a current respective position of the joystick 404, 406. Each joystick 404, 406 can include a respective orientation sensor 412, 414, which can sense the current orientation of each joystick 404, 406 relative to a pivot point of the respective joystick 404, 406. For example, the orientation sensor 412 can sense the orientation of the joystick 404 relative to a neutral position (or pivot point) of the joystick 404, while the orientation sensor 414 can sense the orientation of the joystick relative to a neutral position (or pivot point) of the joystick 406. The orientation sensors 412, 414 can each be in communication with the control device 408 and can each be implemented in a variety of known ways. For accelerometer, a magnetometer (e.g., one or more Hall-effect sensors), an inertial measurement unit (“IMU”), etc. Thus, regardless of the configuration, the control device 408 can be configured to receive a signal from each orientation sensor 412, 414 (or the joysticks 404, 406, generally), to indicate a current orientation of each joystick 404, 406.

[0078] As further detailed below, the orientation of the joysticks 404, 406 can generally correspond to operator inputs for particular power machine operations, which can then be converted to commands for actuators by the control device 408. For example, in some embodiments, the spatial orientation of either of the joysticks 404, 406 can correspond to a particular type and intensity of commanded movement. For example, a region of all possible positions for a two-axis joystick can be segmented into one or more regions (e.g., four quadrants arranged around an origin), which can correspond to a particular task for the excavator. In particular, when the control device receives, from the corresponding orientation sensor, that the joystick is within a particular region, then the control device can implement the task associated with the particular region (e.g., driving forward). In addition, movement of the joystick towards or away a neutral position of the joystick while the joystick is positioned within the particular region can adjust a property related to the task associated with the particular region. For example, further movement of the joystick away from the neutral position can correspond to a commanded increase in speed of a relevant movement, while further movement of the joystick towards the neutral position cancorrespond to a commanded decrease in speed, including when the task associated with the particular region is driving forward. As further detailed below, in some cases, the control system 400 can allow customization of which particular operation is associated with which orientation(s) of the joysticks 404, 406 or other operator input device(s), as well as the characteristics (e.g., speed, maximum or minimum values, etc.) of the commanded operation.

[0079] In some embodiments, operator input devices 402 can include one or more actuatable buttons or other operator input devices that can have one or more corresponding positions. Some of these operator input devices can be integrated into handles for joysticks 404, 406. For example, an actuatable button can be a single pole switch (e.g., a trigger, a rocker switch, etc.) that has two corresponding positions, with a first position indicating the trigger being off, and with a second position indicating the trigger being on. As another example, an actuatable button can be a double pole double throw switch having two actuated positions. As yet another example, an actuatable button can be a push-button having two positions (e.g., on - actuated, and off - not actuated). As another example, an actuatable button can be a double push button. In some cases, an operator input device can include other operator input devices including a roller sensor, a toggle sensor, a joystick, etc., each of which can have more than three positions, including a plurality of intermediate positions. Thus, generally, an operator input device can provide commands for power machine operations via bulk movement of the operator input device (e.g., movement of the joysticks 404, 406) or via actuation of buttons on any of the operator input devices 402 (e.g., movement of switches, push-buttons, rollers, etc.). (As used herein, “button” is intended also to include virtual icons or other virtual interfaces that can receive input similar to mechanical buttons).

[0080] Regardless of the configuration, the actuatable buttons (or other input mechanisms) integrated into the handle of either joystick 404, 406 can be in communication with the control device 408. In this way, the control device 408 can receive an indication that a particular actuatable button (or other mechanism) has been, or has not been, actuated. Similar to the orientation of the joysticks 404, 406, some or all of the actuatable buttons can be mapped to corresponding actuators or functions of the excavator. In some cases, as also generally noted above, buttons on the joysticks 404, 406 can correspond to operation of particular actuators. In some cases, buttons on the joysticks 404, 406 can correspond to adjustments to the control system 400 itself. For example, in some cases, actuatable buttons integrated into the handle associated with the joystick 404 can adjust an operational modeor control mode of a power machine, including to specifically indicate particular control modes, cycle through a sequence of control modes, or adjust parameters of a particular control mode. In some cases, as described in more detail below, a particular control mode can correspond to a particular control -function mapping of the operator input devices 402, or components thereof, to particular commands (e.g., commands for particular actuators, commands to adjust system response or other operational parameters, etc.). In some cases, each control mode for the control system 400 can correspond to a different mapping of functionality to the one or more input devices 402, so that the one or more input devices 402 can control a power machine differently, depending on the currently selected mode.

[0081] In some embodiments, the operator input devices 402 can include pedals 416, 418 each having a respective position sensor 420, 422 that can sense the direction of movement of the corresponding pedal (e.g., forwards or backwards) and the amount of movement of the pedal from a neutral position. In some cases, the position sensors 420, 422 can be implemented in a similar manner as the previously described orientation sensors. For example, each position sensor 420, 422 can be a hall-effect sensor, an optical sensor, etc. In some embodiments, and similarly to the joysticks 404, 406, the pedals 416, 418 can be programmable and assigned different functions for each direction. For example, the pedal 416 moving forwards from a neutral orientation can be assigned with a first function, while the pedal 416 moving backwards from the neutral orientation can be assigned with a second function different from the first function. Further, as with other input devices discussed herein different control -function mapping for the pedals 416, 418 can be assigned for different control modes.

[0082] As shown in FIG. 4, the operator input devices 402 are physically decoupled from the hydraulic system 403. Thus, adjustment of the orientation (or actuation of a mechanical button of an operator input device) of the operator input devices 402 does not directly adjust the operation of the hydraulic system 403 or of the actuators of the hydraulic system 403. Rather, operator inputs are received by the control device 408, modified as appropriate, and then transmitted to the hydraulic system 403 to control movement of an actuator. In this regard, for example, the hydraulic system 403 can include actuators 424, 426, 428 that have respective actuatable valves 430, 432, 434 to control operation of the actuators 424, 426, 428. Each of the valves 430, 432, 434 can be in communication with the control device 408 and can be in fluid communication with the respective actuator 424, 426, 428. Thus, the control device 408 can adjust a position of each actuatable valve 430, 432, 434 (e.g., by providing electrical signals to each actuatable valve 430, 432, 434), andthereby control hydraulic flow to the respective actuators 424, 426, 428 to control movement of the actuators 424, 426, 428 (e.g., to extend the actuator, to retract the actuator, to rotate the actuator, etc.). In other embodiments, however, other known devices can be used to control operation of other known actuators, based on signals from the control device 408 that are, in turn, based on signals from the operator input devices 402. In some embodiments, the actuatable valves 430, 432, 434 are control valves that control a spool valve, which in turn provides hydraulic flow to the respective actuators 424, 426, 428. While three actuators are shown for illustrative purposes, in various embodiments the total number of actuators may be more than three actuators.

[0083] As generally discussed above, in different embodiments, power machine actuators can be implemented in different ways. For example, one or more of the actuators 424, 426, 428 can be a swing actuator (e.g., similar to the swing actuator 233A of FIG. 2), a boom actuator (e.g., similar to the boom actuator 233B of FIG. 2), an arm actuator (e.g., similar to the arm actuator 233C of FIG. 2), an implement carrier actuator (e.g., the similar to implement carrier actuator 233D), an auxiliary actuator (e.g., an actuator for a lifting clamp), a slew motor (or in other words a slew actuator) for a swivel joint (e.g., the slew motor that rotates upper frame portion 211 relative to the undercarriage 212), a drive assembly for a tractive element (e.g., the track drive assembly 240A), or otherwise. Thus, generally, each of the actuators 424, 426, 428 can be a linear actuator (e.g., that extends and retracts), a rotational actuator, or other actuators of known types.

[0084] The actuatable valves 430, 432, 434 can also be implemented in different ways. For example, each actuatable valve 430, 432, 434 can be an electrically controlled valve including a solenoid valve, a pilot solenoid valve, etc. In this way, when a control device 408 electrically powers the electrically controlled valve (e.g., according to a command output value), the valve position changes to adjust the flow of hydraulic fluid through the electrically controlled valve thereby adjusting the hydraulic flow to a respective actuator. In other implementations, however, other known valve types or other known mechanisms for control of actuators can be used.

[0085] While three actuators 424, 426, 428 are illustrated in FIG. 4, in other configurations the control system 400 can have other numbers of actuators (e.g., one, two, four, five, etc.). In addition, while each of the actuators 424, 426, 428 are illustrated as having, or being in fluid communication with, a respective actuatable valve 430, 432, 434 other configurations are possible. For example, one actuatable valve can be in fluid communication with multiple actuators, or multiple actuatable valves can be in fluidcommunication with one actuator. In this way, adjusting the valve position of one actuatable valve can sometimes control movement of the multiple actuators, and adjusting the valve position of multiple actuatable valves can sometimes control movement of a single actuator.

[0086] Generally, the control device 408 can be implemented in a variety of different ways. For example, the control device 408 can be implemented as known types of processor devices, (e.g., microcontrollers, field-programmable gate arrays, programmable logic controllers, logic gates, etc.), including as general or special purpose computers. In addition, the control device 408 can also include other computing components, such as memory, inputs, other output devices, etc. (not shown). In this regard, the control device 408 can be configured to implement some or all of the steps of the processes described herein, as appropriate, which can be retrieved from memory. In some embodiments, the control device 408 can include multiple control devices (or modules) that can be integrated into a single component or arranged as multiple separate components. In some embodiments, the control device 408 can be part of a larger control system (e.g., the control system 160 of FIG. 1) and can accordingly include or be in electronic communication with a variety of control modules, including hub controllers, engine controllers, drive controllers, and so on.

[0087] Referring now to FIG. 5, a block diagram illustrates various components of a representative power machine 500 and the relationships / communication therebetween according to examples of the disclosed technology. The illustrated components and associated systems can be advantageously incorporated into various types of power machines. In particular, in the illustrated configuration, the power machine 500 includes a lift arm assembly 502 (or other hydraulically-powered assembly), a hydraulic pump 504, an electric motor 506, a control system 508, a control valve 510, a first pressure sensor 512, and a second pressure sensor 514. Alternatively, in some embodiments, a single pressure sensor (e.g., the second pressure sensor 514 as a single first pressure sensor) can be used in conjunction with a torque signal to achieve similar function of the first and second pressure sensors 512, 514. For example, similar function can be performed by a pressure sensor that determines the load pressure and an inverter that provides torque signals.

[0088] Referring back to FIG. 2, the power machine 500 of the present disclosure can be an example of the excavator 200 (or another excavator) and the lift arm assembly 502 may correspondingly be one of various excavator lift arm assemblies (e.g., the first lift armstructure 230 including the boom 232 and the arm 234, pivotally supported by the boom 232).

[0089] In some examples, the lift arm assembly 502 can include a hydraulic actuator 520 that is configured to move a boom relative to a frame of the power machine or to move an arm relative to the boom. For example, the hydraulic actuator 520 can be an example of the boom actuator 233B. In some examples, including as shown, multiple actuators can be included in the lift arm assembly 502 (e.g., corresponding to the boom, arm, and implement carrier actuators 233B, 233C, 233D of the excavator 200).

[0090] Further, in some examples, control systems as discussed herein can be implemented for actuators not included in a lift arm assembly. Accordingly discussion herein of the hydraulic actuator 520 of the lift arm assembly 502 should be understood to generally apply to a wide variety of other actuators in a wide range of power machine systems (e.g., tractive or workgroup hydraulic systems of excavators of other configurations, or of loaders or other types of power machines).

[0091] As shown in FIG. 5, rotation of the hydraulic pump 504 is powered by the electric motor 506, which is correspondingly operatively coupled to the pump 504. Thus, flow from the hydraulic pump 504 can be controlled by controlling a rotational speed of the electric motor 506. In some embodiments, the hydraulic pump 504 can be a constant displacement gear pump, although other configurations are possible.

[0092] Flow of hydraulic fluid from the pump 504 for various power machine operations can be controlled by the control valve 510. In some examples, the control valve can be a main control valve (MCV), including MCVs with one or more integrated valve assemblies according a variety of known configurations. Generally, a spool of the control valve 510 is configured to be movable between different positions, to control flow from the hydraulic pump 504 to the hydraulic actuator 520 and thereby control movement of the hydraulic actuator 520 for lift arm (or other) operations.

[0093] The first pressure sensor 512 is configured to sense a fluid pressure corresponding to an inlet 522 to the control valve 510 (e.g., as sensed upstream of or at the inlet 522). The second pressure sensor 514 is configured to sense a fluid pressure corresponding to an outlet 524 from the control valve 510 (e.g., a load, or load sense port of the control valve 510) to a relevant actuator (e.g., as sensed downstream of or at the outlet). Thus, as further discussed below, a control device 526 can be configured to control operations of the motor 506 based on measured pressure(s) of the system (e.g., in response to electrical signals that are received at the control device 526, from the sensors 512, 514,to indicate particular measured pressures). In some examples, the first pressure sensor 512 and second pressure sensor 514 can be integrated into the control valve 510. For example, the first and second pressure sensors 512, 514, respectively, can be placed in mechanical engagement with or in fluid communication with existing pump pressure port 522A and existing load sense pressure port 524A of the control valve 510, as illustrated in the example configuration of FIG. 5 A. In some examples, pressure sensors can be otherwise oriented, including with one or more sensors installed individually or as part of an integrated pressure measurement assembly. In some examples, a single differential pressure sensor can be integrated into or attached to the MCV to measure the relevant pressure differential directly.

[0094] In some examples, a single pressure sensor can measure load pressure for a single actuator of for multiple actuators acting in parallel (e.g., multiple boom actuators on a lift arm). In some examples, load pressure can be measured for multiple actuators that can be controlled independently (e.g., boom actuators and arm actuators, or other actuators configured for independent movement of or on a lift arm assembly). Thus, in some cases, a first pressure sensor can measure load pressures along multiple flow paths out of the control valve 510. For example, as shown with respect to the dotted line flow path in FIG. 5, the first pressure sensor 514 can be a sensor arrangement configured to measure a corresponding pressure for each of multiple flow paths from outlets of the control valve 510 to inlets of lift arm actuators.

[0095] As generally noted above, the hydraulic actuator 520 of the lift arm assembly 502 is in hydraulic communication with the hydraulic pump 504 and the control valve 510. The hydraulic pump 504 is thus arranged to power the hydraulic actuator 520 (or other actuators) to move a work element of the lift arm assembly 502 (or execute another powered operation) in response to operational commands. In particular, control of the control valve 510 based on operator input can power movement of the lift arm assembly 502 by distributing hydraulic fluid from the pump 504 to the hydraulic actuator 520 (or other actuator) with a variable effective orifice size through the control valve 510. Correspondingly, via commanded movements of the control valve 510, for a given output of the pump 504, an operator can controllably provide a desired flow rate for operation of one or more particular actuators.

[0096] The control system 508 also generally includes one or more processor devices that are configured to selectively control operations with the hydraulic actuator 520 or various other actuators (e.g., based on hardwired operational instructions, software installed on a general purpose computer or dedicated controller, etc.). In this regard, the controlsystem 508 may include an electronic control device 526 (e.g., programmable controller) that is configured to receive an operator input from an operator input device 528 (e.g., joystick or hydraulic joystick), and input signals from one or more sensors or other devices (e.g., the pressure sensors 512, 514). The electronic control device 526 can also be configured according to generally known approaches to provide output signals to control operation of other components. Thus, for example, the control system 508 may also include an inverter 530 that receives motor commands (e.g., speed commands) from the control device 526 and provides corresponding current signals to the electric motor 506 to control the rotational speed of the electric motor 506 (and, thereby, the rotational speed of the pump 504).

[0097] With this arrangement, an operator may provide an operator input through the operator input device 528 (e.g., a joystick) to command movement of the lift arm assembly 502. The operator input can be received at the control device 526, and a corresponding movement of the control valve 510 determined motor speed can be determined. A corresponding signal can then be provided by the control device 526 to move the control valve 510, as applicable, to permit a particular metered hydraulic flow to a particular actuator (e.g., the actuator 520 of the lift arm assembly 502). In this regard, a variety of known approaches can be implemented to determine particular control signals for the control valve 510 based on particular input commands from an operator.

[0098] In addition to providing control of the control valve 510, the control device 526 can determine a particular corresponding motor speed (e.g., based on signals from the pressure sensors 512, 514, as further discussed below), and then signal the inverter 530 accordingly. The inverter 530 can then correspondingly control the rotational speed of the motor 506 (e.g., according to various generally known motor control approaches) and, thereby, control the rotational speed of the pump 504. In other words, in some examples, the control device 526 can operate to vary not only a position of the control valve 510 but also a speed of the pump 504 for flow through the control valve 510 (via control of a speed of the motor 506). Thus, a total flow from the pump 504 can be controlled via control of the motor 506, and the flow from the pump 504 can then be controllably metered with the control valve 510 to control movement of a particular actuator (e.g., the actuator 520 of the lift arm assembly 502).

[0099] As also noted above, the pump 504 can in some cases be a constant displacement pump (e.g., gear pump). Accordingly, a flow rate from the pump 504 can be directly and proportionally controlled based on the controlled rotational speed of the electric motor 506.However, motor speed control for control of hydraulic operations, as discussed herein, can also be implemented for variable displacement pumps of various known types.

[0100] Referring to FIG. 6, an example method 600 is provided for control of hydraulic operations to selectively prioritize flow rate or power consumption. In some examples, the method 600 can be implemented with the control system 508 or the power machine 500, generally, as shown in FIG. 5. Accordingly, discussion below may refer to components of the power machine 500 for convenience and clarity. In other examples, however, the method 600 can be implemented with other control systems or power machines.

[0101] In general, the method 600 can include, at block 605, selectively controlling operation of the electric motor 506 (e.g., via speed commands provided to the inverter 530, and corresponding current signals to the motor 506). In particular examples, as further discussed below, operations at block 605 can include selecting between control of the motor 506 in a flow control mode (e.g., at block 610), and control of the motor 506 in a power control mode (e.g., at block 620). For example, at block 610, the electric motor 506 can be controlled based on a target flow rate for flow of hydraulic fluid from the hydraulic pump 504 to the hydraulic actuator 520 (e.g., corresponding to an operator input that commands a particular operation powered by the pump 504). Alternatively, at block 620, the electric motor 506 can be controlled based on a target (e.g. target maximum or ceiling) power consumption or related quantity for the electric motor 506 (e.g., a predetermined threshold maximum motor speed corresponding to a particular pump pressure).

[0102] In some embodiments, the speed of the electric motor 506 can be controlled at block 605 based on a target motor speed determined for a selected control mode (e.g., the flow control mode at block 610, or the power control mode at block 620). Correspondingly, as shown in FIG. 6, controlling the electric motor 506 under a flow control mode, at block 610, can include, at block 630, determining a first target motor speed for flow control. Similarly, controlling the electric motor 506 under a power control mode, at block 620, can include, at block 640, determining a second target motor speed for power control. In this regard, for example, the first target motor speed may indicate a motor speed required to provide sufficient flow for an operator-commanded operation, whereas the second target motor speed may indicate a motor speed beyond which the motor would draw excessive power from the relevant power source (e.g., battery pack). As further discussed below, particular target motor speeds for particular modes can be determined based on predetermined flow or power criteria (e.g., in look-up tables that associate particular motorspeeds with particular operating conditions or operator commands), or in various other ways.

[0103] Continuing with regard to FIG. 6, the electric motor 506 can be controlled, at block 650, based on the target motor speed of the operative mode (e.g., according to operation at block 610 or 620). For example, some implementations can selectively transition between flow control or power control by commanding the electric motor 506 to the lower of the target motor speeds (e.g., from blocks 630, 640) for a particular operating condition or operator command. Thus, for example, the control system 508 can control the electric motor 506 so that the pump 504 generally provides sufficient flow to implement operator commands, while also preventing operation at motor speeds that would cause the electric motor 506 to exceed a power demand threshold of the power machine 500. Correspondingly, during some operations, data monitoring and calculations for flow control mode (e.g., at block 610) and for power control mode (e.g., at block 620) can proceed in parallel, or otherwise concurrently. Beneficially, such an approach can allow real-time comparison of target motor speeds for both control modes and corresponding adjustments to motor commands, as needed (e.g., to temporarily prioritize power over flow, or vice versa).

[0104] In some cases, the electric motor can be controlled (e.g., at block 650) based on a motor speed determined by the control device 408 (e.g., at blocks 630, 640) and the motor speed can be determined (e.g., at blocks 630, 640) based on loading of relevant hydraulic components. In some cases, as further detailed below, target motor speeds can be determined (e.g., at blocks 630, 640) based on sensed pressure for the operative hydraulic system. For example, as also noted above, pressure sensors can be arranged on a power machine to determine a pump pressure (e.g., at an output of the pump) and a load pressure (e.g., at an input to a relevant hydraulic cylinder). In other words, the pump pressure can correspond to a pressure measured at the outlet of the hydraulic pump (or inlet of an MCV) and the load pressure can correspond to a pressure measured at the inlet of the hydraulic actuator (or outlet of an MCV). By determining the difference in pressure at two locations, an estimate of the required flow can be determined (e.g., by the control system 508, based on predetermined correlations between pressure drop and flow demand) and a target motor speed for flow control can be determined accordingly (e.g., at block 630). Further, similar pressure measurements can provide an indication of pump loading, and can thus similarly inform determination of a target motor speed for power control (e.g., at block 640).

[0105] In this regard, as shown in FIG. 7, selectively controlling operation of the electric motor 506 in a flow control mode (e.g., at block 610) can include sensing one or more pressures of the hydraulic system, at block 720. In particular, some examples can include determining pump pressure using a first pressure sensor (at block 720A) and determining load pressure using a second pressure sensor (at block 720B). For example, signals from pressure sensors 512, 514 (see FIG. 5) can indicate to the control device 526 particular measured pump and load pressures, respectively, corresponding to the outlet from the hydraulic pump (and inlet to the control valve 510) and the inlet to the hydraulic actuator 520 (and outlet from the control valve 510).

[0106] During operation in the flow control mode (e.g., at block 610), the electric motor 506 can then be controlled based on a target pressure differential between the pump pressure and the load pressure. For example, measured pump and load pressures (e.g., from blocks 720 A, 720B) can be compared at block 730 to determine a present pressure differential. A target motor speed can then be determined, at block 740, based on a target pressure differential (e.g., a fixed or variable target corresponding to a particular MCV) and the present pressure differential (e.g., from block 730). For example, predetermined correlations between pressure differential and motor speed (or speed change) can be stored in a look-up table or encoded in correlative equations and then a particular target motor speed can be retrieved for a particular pressure differential, as needed. At block 790, the electric motor can then generally be controlled based on the target motor speed (e.g., using known approaches for control signals to and by the inverter 530).

[0107] In the flow control mode (e.g., at block 710), as also discussed above, the target motor speed can generally be an increased motor speed (relative to present speed) if the present pressure differential is below a target pressure differential (e.g., as may correspond to insufficient present flow). Similarly, the target motor speed can generally be a decreased motor speed (relative to present speed) if the present pressure differential is above a target pressure differential (e.g., as may correspond to excess present flow).

[0108] As needed in view of operating conditions, and as also discussed above, the control system can in some cases selectively operate in a power control mode (e.g., at block 620) rather than in a flow control mode (e.g., at block 610) to prioritize power management over flow management. For example, transition to a power control mode can help to avoid stall when the hydraulic pump 504 is operating at a high speed with reduced torquer characteristics and high loading on a relevant hydraulic actuator. In this regard, continuedoperation with lower flow than commanded by an operator may be generally preferable than ceased operation due to excessive power demand.

[0109] In this regard, in the power control mode, at block 760, a target power consumption can be determined. For example, a maximum power consumption for the electric motor 506 can be determined based on the rated power of the motor or other system parameter (e.g., total available system power, etc.). In some cases, as further detailed below, a power consumption target can be determined at block 760 based on operator input. In some examples, a power consumption target can also (or alternatively) be determined based on temperature, e.g., with lower limits on total power consumption when temperatures are high. In any case, motor speed can then be controlled accordingly, to ensure that the motor 506 does not consume excessive power (e.g., does not consume power beyond a predetermined or variable threshold).

[0110] As also noted above, in some cases, target power consumption can be determined at block 760 based on operator input. For example, an operator may engage an operator input device to request additional power beyond a default level, and a target power consumption as determined at block 760 can be adjusted accordingly. For example, an operator may provide an input to request a temporary increase in maximum allowable power consumption by a hydraulic system, to complete an operation with particularly heavy loading (e.g., cutting through a harder soil layer, or removing a rock or other object from a trench). In some cases, a temporary increase in maximum allowable power consumption, as determined at block 760, can be implemented for a predetermined duration or with a predetermined relative or absolute amount of power increase.

[0111] In some examples, adjustments to target power consumption can be determined automatically. For example, target power consumption can be initially determined based on a default rated power for a motor (or hydraulic system, generally), and then can be adjusted based on present or anticipated system-wide power usage, present or anticipated power capacity. In some cases, target power consumption for a particular motor, hydraulic system, or operating condition can be predetermined and stored as a look-up table or executable calculation).

[0112] In some examples, as also discussed above, a power consumption may not necessarily be expressly determined. For example, operation in the power control mode (at block 620) can instead (or additionally) include determining a target speed based on a predetermined table of maximum motor speed thresholds, which may be correlated to pump pressure (e.g., measured at block 770, as further discussed below) or other operationalfactors. Such speed thresholds, for example, may help to ensure that the electric motor 506 does not consume too much power, but may not necessarily be determined or selected based on a power consumption that is calculated (or measured) in real time.

[0113] In some examples, as also shown in FIG. 7, selectively controlling operation of the electric motor 506 in a power control mode (e.g., at block 620) can further include sensing or otherwise determining one or more pressures of the hydraulic system, at block 770. In particular, some examples can include determining pump pressure using the first pressure sensor (e.g., as a common operation with block 720A). Once the pump pressure is determined, a target motor speed can then be determined, at block 780, based on the pump pressure. For example, using known operational relationships for hydraulic machinery, a pump speed can be determined that corresponds to operation with the target power consumption (e.g., from block 760) at the measured pump pressure (e.g., from block 770). The target motor speed can then be set accordingly (e.g., to equal the determined pump speed). Thus, at block 790 , the electric motor 506 can sometimes be controlled based on a pressure (e.g., a pump pressure as measured by the first pressure sensor 512) and a target power consumption (e.g., a predetermined or variable maximum power consumption).

[0114] As also noted above, it may be useful to selectively transition between control under a flow control mode (e.g., at block 610) and control under a power control mode (e.g., at block 620). Generally, in this regard, it may be useful to compare power consumption according to flow control mode and power control mode, and actively control operations accordingly (e.g., to ensure that operation in flow control mode would not require excessive power). In this regard, power consumption can be measured or otherwise determined in a variety of ways, including based on pressure or flow data received from a hydraulic system or based on electrical current or other operational data for the corresponding electric motor.

[0115] In some cases, power consumption for different control modes can be compared indirectly, via comparison of corresponding target motor speeds. For example, as shown in FIG. 8, controlling an electric motor based on a target speed of a control mode (e.g., at block 650, see also FIG. 6) can include comparing target motor speeds for the flow control and power control modes (e.g., from blocks 630, 640) and selecting between the speeds based on the comparison. In particular, after target motor speeds are determined for the two control modes (e.g., at blocks 630, 640), which of the motor speeds is smaller can be determined, at block 840. The electric motor can then be controlled, at block 850, based on the determined smaller speed (e.g., to prevent operation at a flow control speed that wouldrequire excessive power). Thus, for example, through continually updated calculation and comparison of target speeds for flow control and power control, some implementations can control motor speed to generally provide full commanded flow (as possible), while also ensuring that motor speed is not commanded to a speed that would result in excess power consumption.

[0116] As also discussed above, particular motor speeds for powering hydraulic operations can be determined in some cases based on a pressure differential between pump and load pressures. In this regard, again, decreases in motor speed can be commanded in response to increases of pressure differential relative to a reference value, and increases in motor speed can be commanded in response to decreases of pressure differential relative to a reference value (e.g., control setpoint). In this regard, FIG. 9 illustrates an example relationship between measured pressure differential 910 (e.g., as sensed with the sensors 512, 514), commanded motor speed 920 (e.g., of the motor 506), and actual motor speed 930 to an actuator (e.g., as correlates directly to pump speed of the pump 504 and, correspondingly, flow to the control valve 510). In particular, it can be seen that increases of the pressure differential 910 relative to a reference pressure 940 can generally correspond to decreases in the commanded motor speed 920, which in turn can cause (with some amount of lag) a decrease in the hydraulic flow as shown by the motor speed 930. Similarly, decreases of the pressure differential 910 relative to the reference pressure 940 can generally correspond to increases in the commanded motor speed 920, which in turn can cause (with some amount of lag) an increase in the hydraulic flow as shown by the motor speed 930. Thus, for example, when the pressure differential 910 falls below a set point due to insufficient hydraulic flow relative to demand for an operator-commanded movement, the commanded motor speed 920 can be increased, and the flow thereby increased accordingly. Similarly, when the pressure differential 910 exceeds the set point due to excess hydraulic flow relative to demand for an operator-commanded movement, the commanded motor speed 920 can be decreased, the flow thereby decreased accordingly.

[0117] Regarding the graphs presented in the various figures, unless otherwise indicated, the horizontal axis represents time, so that the graphs represent changes in various parameters over corresponding durations. The vertical axes encompass different related metrics, including pressure differential, motor speed, or others. The values depicted in the graphs are illustrative examples and are accordingly presented to demonstrate trends and relationships of variables over time (internally and relative to other variables) rather than highlight absolute measurements.

[0118] Relatedly, in different implementations, different response curves or other flow control relationships for motor speed relative to pressure differential (or other factors) can be used (or present), including with variation depending on the characteristics of a particular power machine, hydraulic system, or workgroup assembly, a particular present operating condition for a relevant power machine, or other various factors. In this regard, in some examples, a control scheme (e.g., as implemented through software) can change during operation and different set points can alter the response of a power machine accordingly.

[0119] For example, at low pressure drops (e.g., at or near the pressure 940 as illustrated in FIG. 9), relatively low percentage speed reductions can be applied relative to a maximum or other reference speed (e.g., in a range of about 20% or less). In contrast, at high pressure drops (e.g., exceeding the pressure 940), relatively high percentage speed reductions can be used (e.g., in a range of 20% or more). As such, a power machine operating with a higher pressure drop relative to a setpoint may operate somewhat slowly and generally more smoothly, while a power machine operating with a lower pressure drop relative to a setpoint may operate at somewhat faster speed. However, although this generally presented approach may be particularly beneficial in some cases, other approaches can be used in other implementations.

[0120] A response curve for a power control mode may generally differ from a response curve for a flow control mode. In this regard, FIG. 10 shows an example relationship between motor speed and pump pressure (or pump torque, in another example) in a power control mode (e.g., with pump pressure measured at an MCV). In the power control move, as generally illustrated in FIG. 10, a maximum permitted (i.e., target) speed of the electric motor 506 can be decreased when pump pressure increases above a first pressure 1002. For example, the maximum permitted speed can be decreased continuously relative to pressure, from a maximum speed 1000 corresponding to the pressure 1002, toward a minimum speed 1004 at a second pressure 1006 (e.g., with a varying rate of reduction, as shown). As generally discussed above, for example, this can help to ensure that power consumption remains appropriately limited. Further, relatively low maximum speeds (e.g., the minimum speed 1004) may also be enforced at lower pressures (e.g., below a third pressure 1008), to provide minimum pilot pressure for the MCV and counterbalance a pilot circuit leakage at an idle state.

[0121] In some examples, different power control modes can be selectively implemented, including to provide different maximum power consumption for a particularhydraulic system or hydraulic actuator. For example, FIG. 11 shows different variations of power control mode generally similar to the example of FIG. 10, but with multiple submodes of operation. In a first mode 1210, for example, the control system 508 may start decreasing the speed of the electric motor 506 at a relatively low pump pressure and at a relatively fast rate and may exhibit a relatively low minimum motor speed (at high pressures). In a second mode 1220, the control system 508 may similarly start decreasing the speed of the electric motor at a relatively low pump pressure but may decrease speed relative to pressure at a slower rate than the first mode 1210 (e.g., over a range of relatively high pressures). In a third mode 1230, the control system 508 may start decreasing the speed of the electric motor 506 at a higher pump pressure than in the first and second modes 1210, 1220, and may generally decrease motor speed relative to pressure at a slower rate over range of pressures. Thus, operations under mode 3 may be able to provide higher levels of power than operations under modes 1 or 2, and operations under mode 2 may be able to provide higher levels of power than operations under mode 1. In this way, for example, a control system can operate to provide more or less aggressive consumption of power and provision of flow, depending on the needs of a particular operator, operation, or operating condition.

[0122] FIGS. 12A and 12B illustrate an example of the operations controlled by the control system 508 under the method 600, including with transitions over time between flow control mode and power control mode. Referring to FIG. 12 A, the relationship of the pump pressure and the load pressure with respect to the joystick input for hydraulic operations is shown overtime. In particular, as also discussed above, a joystick input of the operator may determine how fast the hydraulic fluid needs to be supplied to the hydraulic actuator 520. Correspondingly, as the joystick input increases, indicating greater commanded flow, adjustment of the control valve 510 may result in decreases in the difference between the pump pressure and the load pressure. As discussed above, the control system 508 can monitor this pressure difference and control moto speed accordingly to attempt to maintain a pre-determined pressure difference value (e.g., about 14 bar).

[0123] Referring to FIG. 12B, in particular, a target electric motor speed with respect to flow control mode and power control mode is illustrated, along with a trace of actual motor speed. As illustrated, and generally described above, a higher load as corresponds to increase in joystick command can induce a decrease in pressure in a hydraulic system and a corresponding increase in target speed under flow control (see region 1310 in FIGS. 12A and 12B). In some examples, the target speed for the electric motor to maintain the desiredflow rate may thus experience a sudden or otherwise excessive increase. In these cases, trying to control the pump to maintain flow control can accordingly result in the machine operating at excessive speeds or otherwise with reduced torque characteristics, which can increase the chance of a motor stall event. For particularly increased flow control speeds , the control system 508 can thus temporarily transition from the flow control mode to power control mode to maintain appropriate power (see, e.g., region 1320 in FIG. 12B). Such a transition may result in a temporary destabilization in flow, but the power machine 500 can generally still function without stalling out. Once the pressure recovers and stabilizes, or the determined flow control speed is otherwise sufficiently reduced (see, e.g., region 1330 in FIG. 12B), the control system 508 can revert to flow control mode. Thus, for example, where increased flow demand would require excessive power consumption via excessive motor speeds, control can be temporarily implemented under a power control mode with reduced motor speed and correspondingly reduced flow and power usage.

[0124] FIG. 13 illustrates operation of a control system as disclosed herein during transition from idle, into operation, and back to idle (or zero command). More specifically, the relevant hydraulic system transitions from a first idle phase 1410 into an operating phase 1420 and then into a second idle phase 1430 (or zero command phase). As shown, a first line 1432 indicates a target pressure (e.g., a constant pressure differential in the illustrated example), and a second line 1434 indicates actual (e.g., sensed) pressure differential. A third line 1436 indicates commanded motor speed (e.g., as requested to the inverter), and a fourth line 1438 indicates the actual (e.g., measured) speed of the electric motor 506. For the systems discussed above (e.g., as shown in FIG. 5), the fourth line 1438 can also indicate a speed of a pump coupled to the motor (e.g., can represent actual pump speed or, for systems with intervening gearing or other speed reduction / change systems, a value proportional to pump speed).

[0125] In the first idle phase 1410, no flow for hydraulic operations is requested and the motor can be operated at relatively low speeds (e.g., at a constant, low-power speed, to dump flow to tank across a pressure relief valve). As flow for hydraulic operations is requested (e.g., due to operator commands for lift arm movements), the control system then transitions from the first idle phase 1410 to the operating phase 1420.

[0126] In an initial transition portion 1420 A of the operating phase 1420, commands for hydraulic flow cause the pressure differential to drop and the control system accordingly commands an increase in motor (and pump) speed. In some examples, some delay may be present as the speed of the electric motor 506 ramps up and the pump 504 accelerates tosupply increased in flow. In some examples, there may also (or otherwise) be a delay between the motor speed requested to the inverter and the current speed of the electric motor 506.

[0127] After sufficient ramp up time, operation in a steady-state portion 1420B of the operating phase 1420 can be reached, in which the pressure differential stabilizes at an operational pressure setpoint and the control system correspondingly operates the motor at a constant motor speed (e.g., 2200 RPM). In other examples, of course, operators may provide more complex commands (e.g., with varied direction or amplitude). Accordingly, operation in the operating phase 1420 may not always stabilize over an extended period as shown.

[0128] Upon removal of commands for flow (e.g., upon the operator releasing a joystick), the system can enter another transition portion 1420C of the operating phase 1420 in which motor speed is ramped down. For example, as illustrated, opening of a relief valve due to the zeroing of operator command can result in a relatively steep spike in pressure differential, and the speed of the electric motor 506 can be decreased accordingly until reaching the low speed of the second idle phase 1430.

[0129] In some cases, operator commands may effectively change (e.g., cease) with step-change (or other steeply sloped) profiles, including for on-off / off-on transitions. However, motor control according to the disclosed technology may in some cases continue to vary motor speed more complexly after such a command change. For example, as shown in FIG. 13, after the relevant system enters transition portion 1420C (e.g., returns to zero command), flow dynamics and other factors relating to system pressure relief can result in transient pressure variation with relatively large amplitude (see, e.g., line 1434). Motor (and pump) control based on pressure, as discussed herein, can correspondingly provide varied speed commands that can help to accommodate those pressure transients (e.g., variously increasing and decreasing motor speed during a zero command state) and thereby smooth transitions form operating to idle (or between various other controlled states).

[0130] In some examples, the motor speed may include a maximum threshold, including as can be determined according to a power control mode (e.g., as detailed above). Referring to FIG. 14, for example, a maximum motor speed 1510 according to a power control mode can be determined based on a corresponding pump pressure 1520 (e.g., corresponding to a maximum power consumption by the motor, according to predetermined threshold). Although such a maximum speed 1510 may be calculated continually, however, actual motor speed may not be thus effectively limited in some cases. For example, a targetmotor speed 1530, as calculated based on pressure differential 1540, can in some cases remain lower than the maximum speed 1510 at all relevant times. Accordingly, although a power control mode may impose a maximum threshold for electric motor speed, actual speed of the electric motor (see speed trace 1550) may not necessarily be limited as a result.

[0131] FIGS. 15A and 15B illustrate transitions from a flow control mode to a power control mode while subject to load (e.g., during control of a boom actuator of an excavator for trenching or other digging operations). Referring to FIG. 15 A, as similarly described above, a maximum motor speed 1610 can be determined according to a power control mode and a motor speed 1620 to match commanded flow can be determined according to a flow control mode (e.g., as variously described above). During an initial period 1630, the flow control motor speed 1620 may be less than the maximum motor speed 1610, and the motor can thus be controlled according to the flow control motor speed 1620, as shown by motor speed 1640.

[0132] As the system is subjected to a load during a subsequent period 1650, increases in pump pressure 1660 can cause corresponding reduction in the maximum motor speed 1610 (i.e., to prevent excess power consumption), and the maximum motor speed 1610 may thus occasionally fall below the flow control motor speed 1620. Accordingly, during those times, motor speed control can transition from flow control mode to the power control mode, with the motor speed 1620 correspondingly limited based on the maximum motor speed 1610. Conversely, reduction in the pump pressure 1660 can result in increases in the maximum motor speed 1610 according to the power control mode, and motor speed control can thus transition back from the power control to the flow control mode.

[0133] Thus, in some cases, a somewhat repeated pattern of control can be implemented for trenching or other similar operations. As shown in FIG. 15B, for example, pressure peaks 1660 A, 1660B may result from operation of a lift arm actuator (e.g., boom actuator) to cut into the ground during trenching. Correspondingly, a power control mode may determine corresponding valleys 1610A, 1610B in maximum motor speed. Thus, for example, reduced-speed motor control can be implemented at repeated transient intervals 1640A, 1640B, to ensure that the commanded operation does not result in excessive power draw.

[0134] Although trenching and similar digging operations may be a notable area for improved control, similar control approaches can be applied to other operations, resulting in other patterns of commanded motor speed. For example, FIG. 16 illustrates speed and pressure traces during other power machine operations, including commanded motor speed1710, maximum motor speed 1720, pressure drop 1730 (and pressure error 1740 ), load pressure 1750, and actual motor speed 1760. As shown in FIG. 16, the commanded motor speed 1710 can be limited over a wide range of pressure conditions to provide requested flow when possible, while not exceeding a maximum motor speed 1720 determined according to a power control mode.

[0135] FIG. 17 illustrates another example of transitions between flow control and power control modes. For example, prior to transition time 1810, a motor speed command 1820 can be determined under a flow control mode (e.g., controlled based on pressure drop, as discussed above). At the transition time 1810, however, a calculated flow control speed would start to exceed a power control maximum speed 1830 (e.g., due to increased pressure at the relevant pump). Accordingly, the motor speed command 1820 can be matched to the maximum speed 1830. Continuing, at a later transition time 1840, the calculated flow control speed again falls below the maximum speed 1830 (e.g., corresponding to increased pressure drop, as discussed above). Accordingly, the motor speed command 1820 can again be determined under the flow control mode, without being limited by the maximum speed 1830.

[0136] As shown in the illustrated example, the maximum speed 1830 and the motor speed command 1820 may be identical between the transition times 1810, 1840. In some examples, however, a commanded motor speed can be somewhat above a power control limit over some amount of time. For example, a lag in speed reduction may sometimes result from the time it takes for a motor to stop accelerating and return back to a lower speed, or an operator may request a temporary increase in power consumption limits (as also discussed above). Correspondingly, a motor may temporarily consume more power than the corresponding limit (e.g., 10.5 kW versus a limit of 10 kW) but typically not so much as to stall. In this regard, in some cases, a motor can be limited under a power control mode to a power threshold that is below a rated power for the motor (e.g., with a limit of lOkW for a motor that is rated for 15 or 20 kW).

[0137] FIG. 18 illustrates the process that can be useful to prevent losing excessive flow at the main pump relief when the actuator reaches the end stroke, with lines indicating pump pressure 1910, pressure drop 1920, commanded speed 1930, and actual motor speed 1940. In this regard, to cause continuous circulation of hydraulic fluid to help warm a power machine, an actuator can be commanded to end of stroke (e.g., with a step command for a lift arm cylinder), which can result in motor commands to provide flow to the actuator. The resulting actuator movements (e.g., boom extension) may correspond, for example, to theoscillations in pressure drop during period 1950 in FIG. 18. Subsequently, as the actuator reaches an end stroke position, the pump pressure may spike (e.g., as shown at pressure peaks 1910A, 1920A). According to some approaches disclosed herein, this pressure spike can result in a decrease in flow command (e.g., in commanded motor speed 1930 during period 1960), based on decreases in maximum motor speed as determined under a flow control mode to prevent excess power consumption. In other words, when the cylinder at end stroke, no flow may be necessary and the flow control mode can correspondingly command the motor to run at minimum motor speed.

[0138] In some examples, to ensure sufficient flow for expedient warming of the hydraulic system of the power machine, a warming mode (e.g., a sub-mode of a flow control mode) may instead temporarily permit increased motor speed despite increased pump pressure (e.g., as shown in the dashed extension of motor speed 1930). Such an implementation of warming mode can be initiated based on temperature sensors, operator input (e.g., engagement with a “warm up” button or icon), or various other factors. As also discussed above, similar temporary increases in power consumption can also be implemented in other circumstances (e.g., in response to operator requests for temporary power bursts for various work operations).

[0139] While many examples described above are presented relative to buckets for an excavator, it should be understood that the disclosed systems and processes can generally be utilized for other implements as appropriate, including, for example, implements configured as mowers, forks, cutters, stamps, tree scoops, etc.

[0140] Thus, some embodiments of the disclosure can provide improved control of power machines, including via customizable or otherwise improved interoperation of operator input devices and electronically controlled actuators.

[0141] In some embodiments, aspects of the invention, including computerized implementations of methods according to the invention, can be implemented as a system, method, apparatus, or article of manufacture using standard programming or engineering techniques to produce software, firmware, hardware, or any combination thereof to control a processor device (e.g., a serial or parallel general purpose or specialized processor chip, a single- or multi-core chip, a microprocessor, a field programmable gate array, any variety of combinations of a control unit, arithmetic logic unit, and processor register, and so on), a computer (e.g., a processor device operatively coupled to a memory), or another electronically operated controller to implement aspects detailed herein. Accordingly, for example, embodiments of the invention can be implemented as a set of instructions,tangibly embodied on a non-transitory computer-readable media, such that a processor device can implement the instructions based upon reading the instructions from the computer-readable media. Some embodiments of the invention can include (or utilize) a control device such as an automation device, a special purpose or general purpose computer including various computer hardware, software, firmware, and so on, consistent with the discussion below. As specific examples, a control device can include a processor, a microcontroller, a field-programmable gate array, a programmable logic controller, logic gates etc., and other typical components that are known in the art for implementation of appropriate functionality (e.g., memory, communication systems, power sources, user interfaces and other inputs, etc.).

[0142] The term “article of manufacture” as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier (e.g., non- transitory signals), or media (e.g., non-transitory media). For example, computer-readable media can include but are not limited to magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips, and so on), optical disks (e.g., compact disk (CD), digital versatile disk (DVD), and so on), smart cards, and flash memory devices (e.g., card, stick, and so on). Additionally, it should be appreciated that a carrier wave can be employed to carry computer-readable electronic data such as those used in transmitting and receiving electronic mail or in accessing a network such as the Internet or a local area network (LAN). Those skilled in the art will recognize that many modifications may be made to these configurations without departing from the scope or spirit of the claimed subject matter.

[0143] Certain operations of methods according to the disclosed technology, or of systems executing those methods, may be represented schematically in the FIGS, or otherwise discussed herein. Unless otherwise specified or limited, representation in the FIGS, of particular operations in particular spatial order may not necessarily require those operations to be executed in a particular sequence corresponding to the particular spatial order. Correspondingly, certain operations represented in the FIGS., or otherwise disclosed herein, can be executed in different orders than are expressly illustrated or described, as appropriate for particular embodiments of the invention. Further, in some embodiments, certain operations can be executed in parallel, including by dedicated parallel processing devices, or separate computing devices configured to interoperate as part of a large system.

[0144] As used herein in the context of computer implementation, unless otherwise specified or limited, the terms “component,” “system,” “module,” “block,” and the like are intended to encompass part or all of computer-related systems that include hardware,software, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being, a processor device, a process being executed (or executable) by a processor device, an object, an executable, a thread of execution, a computer program, or a computer. By way of illustration, both an application running on a computer and the computer can be a component. One or more components (or system, module, and so on) may reside within a process or thread of execution, may be localized on one computer, may be distributed between two or more computers or other processor devices, or may be included within another component (or system, module, and so on).

[0145] The terminology in this document is used for the purpose of description and should not be regarded as limiting. Words such as “including,” “comprising,” and “having” and variations thereof as used herein are meant to encompass the items listed thereafter, equivalents thereof, as well as additional items.

[0146] Also as used herein, unless otherwise limited or defined, “or” indicates a nonexclusive list of components or operations that can be present in any variety of combinations, rather than an exclusive list of components that can be present only as alternatives to each other. For example, a list of “A, B, or C” indicates options of: A; B; C; A and B; A and C; B and C; and A, B, and C. Correspondingly, the term “or” as used herein is intended to indicate exclusive alternatives only when preceded by terms of exclusivity, such as “only one of,” or “exactly one of.” For example, a list of “only one of A, B, or C” indicates options of: A, but not B and C; B, but not A and C; and C, but not A and B. In contrast, a list preceded by “one or more” (and variations thereon) and including “or” to separate listed elements indicates options of one or more of any or all of the listed elements. For example, the phrases “one or more of A, B, or C” and “at least one of A, B, or C” indicate options of: one or more A; one or more B; one or more C; one or more A and one or more B; one or more B and one or more C; one or more A and one or more C; and one or more A, one or more B, and one or more C. Similarly, a list preceded by “a plurality of’ (and variations thereon) and including “or” to separate listed elements indicates options of one or more of each of multiple of the listed elements. For example, the phrases “a plurality of A, B, or C” and “two or more of A, B, or C” indicate options of: 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 A, one or more B, and one or more C.

[0147] Also as used herein in the context of power machines, unless otherwise defined or limited, “tractive” or “drive” designate actuators and other work elements of a powermachine that can be powered by a power source to cause movement of the power machine over terrain (e.g., wheeled or tracked ground-engaging elements, motors configured to power ground-engaging elements, and related assemblies). In contrast, “workgroup” is used to refer to actuators or other work elements of a power machine associated with powered operation of work elements that are not configured to provide powered travel over terrain (e.g., lift arm structures, attached implements, motors or other actuators to power movement of lift arm structures or attached implements, auxiliary power take-off interfaces, and related assemblies). Thus, tractive (or drive) actuators are arranged to power travel of a power machine whereas workgroup actuators are arranged to power non-travel work operations of the power machine. Correspondingly, discussion of workgroup functions refers to one or more functions provided by movement of one or more work elements of a power machine, whereas discussion of tractive (or drive) functions refer to one or more functions provided for movement of the power machine itself over terrain.

[0148] Although the presently disclosed technology has been described by referring to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the discussion.

Claims

WHAT IS CLAIMED IS:

1. A power machine (100) compri sing : a lift arm assembly (502) that includes a hydraulic actuator (520); a hydraulic pump (504) in hydraulic communication with the hydraulic actuator (520) and configured to power movement of the lift arm assembly (502); an electric motor (506) configured to power rotation of the hydraulic pump (504); and a control system (508) that includes one or more processor devices configured to selectively control the electric motor (506) for operation of the hydraulic actuator (520), by: in a flow control mode, controlling the electric motor (506) based on a target flow rate for flow of hydraulic fluid from the hydraulic pump (504) to the hydraulic actuator (520); and in a power control mode, controlling the electric motor (506) based on one or more of a target power consumption for the electric motor (506) or a threshold motor speed.

2. The power machine (100) of claim 1, wherein the control system (508) is further configured to: while controlling operation of the electric motor (506) in the flow control mode, determine a first power consumption of the electric motor (506); and transition to controlling operation of the electric motor (506) in the power control mode in response to determining that the first power consumption exceeds a first threshold power consumption.

3. The power machine (100) of claim 2, wherein the control system (508) is further configured to: while controlling operation of the electric motor (506) in the power control mode, determine a second power consumption of the electric motor (506); and transition to controlling operation of the electric motor (506) in the flow control mode in response to determining that the first power consumption does not exceed a second threshold power consumption.

4. The power machine (100) of any of the preceding claims, wherein the control system (508) is configured to selectively control operation of the hydraulic actuator (520) by: determining a first target motor speed for the flow control mode; determining a second target motor speed for the power control mode; and controlling the electric motor (506) based on the smaller of the first and second target motor speeds, and optionally or preferably wherein one or more of: the first target motor speed for the flow control mode is determined based on the target flow rate for flow of hydraulic fluid from the hydraulic pump (504) to the hydraulic actuator (520); or the second target motor speed for the power control mode is determined based on one or more of the target power consumption for the electric motor (506) or the threshold motor speed.

5. The power machine of claim 4, wherein the first target motor speed is determined based on the target flow rate and a difference between a pump pressure and a load pressure associated with the hydraulic actuator (520), and wherein the second target motor speed is determined based on the pump pressure for the hydraulic pump (504).

6. The power machine of any of the preceding claims, wherein, in the flow control mode, the target flow rate is based on an operator input that commands operation of the hydraulic actuator (520).

7. The power machine of any of the preceding claims, wherein, in the flow control mode, the one or more processor devices control the electric motor (506) based on the target flow rate and a difference between a pump pressure and a load pressure associated with the hydraulic actuator (520).

8. The power machine of claim 7, wherein, in the flow control mode, the one or more processor devices control the electric motor (506) to reduce motor speed in response to determining that the difference between the pump and load pressures exceeds a threshold pressure drop.

9. The power machine of either of claims 7 or 8, wherein the control system further comprises: a control valve (510) configured to control flow from the hydraulic pump (504) to the hydraulic actuator (520); a first pressure sensor (512) configured to sense a fluid pressure corresponding to an inlet (522) to the control valve (510) for flow from the hydraulic pump (504); and a second pressure sensor (514) configured to sense a fluid pressure corresponding to an outlet (524) from the control valve (510) to the hydraulic actuator (520); and wherein the one or more processor devices are configured to determine the pump pressure based on signals from the first pressure sensor (512) and determine the load pressure based on signals from the second pressure sensor (514), and optionally or preferably wherein the first and second pressure sensors (512, 514) are integrated into the control valve (510).

10. The power machine of any of the preceding claims, wherein the lift arm assembly (502) is an excavator lift arm assembly, including a boom (232) and an arm (234) pivotally supported by the boom (232); and wherein the hydraulic actuator (520) is configured to move the boom (232) relative to a frame (210) of the power machine (100) or to move the arm (234) relative to the boom (232).

11. The power machine of claim 1, wherein the hydraulic pump (504) is a constant displacement pump.

12. A method of controlling operation of a work element of a power machine (100), the method comprising: selectively controlling operation of an electric motor (506), with one or more processor devices, in a flow control mode or a power control mode, the electric motor (506) being arranged to power rotation of a hydraulic pump (504), the hydraulic pump (504) being arranged to power a hydraulic actuator (520) to move the work element; wherein, in the power control mode, the electric motor (506) is controlled based on a target power consumption for the electric motor (506); and wherein, in the flow control mode, the electric motor (506) is controlled based on a target pressure differential between (i) a pump pressure corresponding to an outlet (524)from the hydraulic pump (504) and (ii) a load pressure corresponding to the hydraulic actuator (520).

13. The method of claim 12, further comprising: determining a present pressure differential between the pump pressure and the load pressure based on (i) data from a first pressure sensor (512) configured to sense a fluid pressure upstream of or at an inlet (522) to a control valve (510) and (ii) data from a second pressure sensor (514) configured to sense a fluid pressure downstream of or at an outlet (524) from the control valve (510); wherein in the flow control mode, controlling the electric motor (506) based on the target pressure differential includes controlling the electric motor (506) based on a comparison between the present pressure differential and the target pressure differential.

14. The method of claim 13, wherein, in the power control mode, controlling the electric motor (506) based on the target power consumption includes controlling the electric motor (506) based on data from the either of the first pressure sensor (512) or the second pressure sensor (514).

15. The method of claim 12, wherein selectively controlling operation of the electric motor (506) in the flow control mode or the power control mode includes: determining a first target motor speed for the flow control mode; determining a second target motor speed for the power control mode; and controlling the electric motor (506) based on the smaller of the first and second target motor speeds.

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