WORK MACHINE AND METHOD FOR CONTROLLING PROPULSION THEREOF WITH PARALLEL PROCESSING OF USER INTERFACE INPUTS

Description

FIELD OF THE DISCLOSURE

The present disclosure relates generally to work machines having ground-engaging traction units and user interface units such as for example foot pedals, and more particularly to systems and methods for propulsion control of the traction units based on parallel processing of the inputs from such user interface units.

BACKGROUND

Work machines of this type may for example include excavator machines, among others having traction units, such as potentially skid steer loaders and the like. Propulsion and steering controls for conventional excavators are typically provided via foot pedals that independently control the left and right traction units of the machine undercarriage. These foot pedals typically have levers mechanically attached to them to allow hand control of tracking functions. These controls can be uncomfortable to operate, particularly when controlling movement of the work machine across a substantial distance, where the operator must maintain continuous engagement with both pedals.

Conventional solutions to ease operation during heavy travel operations vary, with one method being to implement a “single pedal” travel system, whereby an auxiliary pedal placed to the side of the normal travel pedals can be configured to operate both tracks simultaneously to drive the machine in a straight direction. This type of system is often implemented utilizing valves to shuttle pilot pressures to the auxiliary control valve for travel control, which effectively disables the primary pedals. Because of this, course correction can be challenging. To modify the direction of machine travel (i.e. “course correct”), the operator needs to stop travelling straight and use the primary pedals to adjust machine direction.

BRIEF SUMMARY

The current disclosure provides an enhancement to conventional systems, at least in part by introducing a novel work machine, control system, and method for utilizing a single pedal travel system for enhanced operator comfort during “straight travel” processes, while also allowing for course correction in parallel with the single pedal travel mode and without requiring the operator to stop travel.

In one particular and exemplary embodiment, a method of controlling a plurality of independent traction units on a work machine includes receiving electronic signals comprising: first signals representing user engagement of a first user interface unit for commanding a traction unit on a first side of the work machine; second signals representing user engagement of a second user interface unit for commanding a traction unit on a second side of the work machine; and third signals representing user engagement of a third user interface unit for commanding each of the traction units on the first and second sides of the work machine. The first and third signals are combined to generate a first travel command value, and the second and third signals are combined to generate a second travel command value. Control signals are generated to one or more actuators for controlling the traction unit on the first side of the work machine based on the first travel command value, and controlling the traction unit on the second side of the work machine based on the second travel command value.

In one exemplary and optional aspect according to the above-referenced method embodiment, values corresponding to each of the first, second, and third signals may be normalized to a common unit structure. The common unit structure may for example comprise percentage (%) values, wherein user engagement of a user interface unit for commanding a respective one or more of the traction units in a fore direction generates a positive value between 0% and 100%, and user engagement of a user interface unit for commanding a respective one or more of the traction units in an aft direction generates a negative value between-100% and 0%.

In another exemplary and optional aspect according to the above-referenced method embodiment, for first and second travel command values less than 100%, the control signals may be generated for controlling the respective traction units based thereon. For first and second travel command values greater than 100%, the respective travel command values may be normalized back to a range of +/−100%, wherein the control signals are generated for controlling the respective traction units based thereon.

In another exemplary and optional aspect according to the above-referenced method embodiment, the first and second travel command values may be normalized back to a range of +/−100% by respectively dividing each command value by a maximum of the first and second command travel command values.

In another embodiment as disclosed herein, a work machine may include a plurality of traction units configured to independently operate in fore or aft directions for propelling the work machine across a ground surface, and a plurality of user interface units. A first user interface unit is configured upon user engagement thereof to generate first signals for commanding a traction unit on a first side of the work machine. A second user interface unit is configured upon user engagement thereof to generate second signals for commanding a traction unit on a second side of the work machine. A third user interface unit is configured upon user engagement thereof to generate third signals for commanding each of the traction units on the first and second sides of the work machine. A data processing and control system is further configured to direct the performance of steps according to the above-referenced method embodiment and optionally one or more of the exemplary aspects thereof.

Numerous objects, features, and advantages of the embodiments set forth herein will be readily apparent to those skilled in the art upon reading of the following disclosure when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view representing an excavator as an exemplary self-propelled work machine according to an embodiment of the present disclosure.

FIG. 2 is a perspective view representing a control pedal array as exemplary work interface tools according to an embodiment of the present disclosure.

FIG. 3 is an overhead view representing fore/aft motion of tracks for an excavator according to an embodiment of the present disclosure.

FIG. 4 is a block diagram representing an exemplary control system according to an embodiment of the present disclosure.

FIG. 5 is a flowchart representing an exemplary embodiment of a method as disclosed herein.

DETAILED DESCRIPTION

Referring now to FIGS. 1-5, various embodiments may now be described with respect to a system and method for operating a self-propelled work machine in what may be referred to herein as a “single pedal” travel mode, specifically improving upon otherwise similar conventional techniques by offering the ability for course correction while otherwise travelling in a substantially straight direction. An electro-hydraulic control system may for example be utilized, whereby all of the pedals are electronic and can have their signals processed in parallel to offer enhanced controllability during a desired travel mode.

FIG. 1 depicts a representative self-propelled work machine 120 in the form of, for example, a tracked excavator machine. Although an excavator is primarily described herein as an example of the work machine 120, other types of work machines within the scope of the present disclosure may in various embodiments include a loader, a bulldozer, a motor grader, or another construction, agricultural, or utility vehicle, for example.

The work machine 120 includes an undercarriage 122 including first and second traction units 124. Traction units as described herein are in the form of tracks, but in alternative embodiments within the scope of the present disclosure may include wheels, for example. Only one of the traction units is shown in FIG. 1. The other traction unit is parallel to the illustrated traction unit. Each of the traction units 124 may typically include a front idler, a drive sprocket, and a track chain extending around the front idler and the drive sprocket. A travel motor for each traction device drives its respective drive sprocket. The traction units can be driven at the same velocity to move the undercarriage forward (e.g., in a forward direction indicated by an arrow 126) or backward (e.g., in a direction opposite the arrow 126) with respect to underlying terrain 128 (e.g., ground or other material supporting the undercarriage). The traction units can also be driven at different velocities to enable the undercarriage to turn with respect to the terrain at an angle with respect to the forward direction represented by the arrow 126.

A main frame 130 is supported from the undercarriage 122 by a swing bearing 132 such that the main frame is pivotable about a main frame pivot axis 134 relative to the undercarriage. The pivot axis is substantially vertical when the underlying ground terrain 128 engaged by the traction units 124 is substantially horizontal. (In the discussion herein, “horizontal” and “vertical” are referenced to a plane defined by the traction units.) A swing motor (not shown) is configured to pivot the main frame on the swing bearing about the pivot axis relative to the undercarriage.

In the illustrated embodiment wherein the work machine 120 is an excavator, a work implement 140 extends from the main frame 130. In FIG. 1, the work implement is configured as a boom assembly. The work implement includes conventional components in the form of a boom 142, an arm 144, and a working tool 146. The working tool includes a point-of-interest (POI) 148, which engages portions of terrain (or other materials) to be moved or removed.

The boom 142 is pivotally connected to the main frame by a boom-to-frame linkage joint 150, which provides a horizontal pivot axis for the boom. The arm is pivotally connected to the boom at an arm-to-boom linkage joint 152. In the illustrated embodiment, the working tool 146 is an excavator shovel, which is pivotally connected to the arm 144 at a working tool-to-arm linkage joint 154, which is positioned near a free end of the arm. In the illustrated embodiment, a first end of a dogbone connector 160 is pivotally connected to the arm at a dogbone-to-arm linkage joint 162, which is displaced from the free end of the arm. A second end of the dogbone connector is pivotally connected to a tool link 164. In the context of the illustrated (excavator) work machine 120, the tool link is a bucket link.

The boom 142 is caused to move pivotally with respect to the main frame 130 by a boom actuator 170. The boom actuator can be a hydraulic motor. In the illustrated embodiment, the boom actuator is a hydraulic piston-cylinder unit that is selectively provided with pressurized hydraulic fluid to move the piston within the cylinder to extend or extract the piston. The pressurized hydraulic fluid is provided by a hydraulic system (not shown) and is controlled by manual controls, automatic controls, or a combination of manual and automatic controls. In a similar manner, the arm 144 is caused to pivot with respect to the boom by an arm actuator 172. The working tool (bucket) 146 is caused to pivot with respect to the arm by a working tool actuator 174 acting on the working tool via the dogbone connector 160, the dogbone-to-arm linkage joint 162, and the tool link 164.

The work implement 140 extends from the main frame 130 along a working direction (represented by arrow 176) of the work implement. In FIG. 1, the working direction is referenced to the main frame. Although illustrated as parallel to the forward direction (arrow 126) of the undercarriage 122, the working direction can be at an angle to the forward direction depending on the rotational position of the main frame with respect to the undercarriage. The working direction can also be described as a working direction of the boom 142.

As described herein, control of the work implement 140 relates to controlling the positioning of any one or more of the associated components (e.g., the boom 142, the arm 144, and the working tool 146) to control the movement of the point-of-interest 148 of the working tool with respect to material to be manipulated (e.g., the material to be moved or removed).

The actuators 170, 172, 174 of the work implement 140 can be selectively actuated to pivotally move the boom 142 with respect to the respective boom-to-frame linkage joint 150, to pivotally move the arm 144 with respect to the arm-to-boom linkage joint 152, and/or to pivotally move the working tool 146 with respect to the working tool-to-arm linkage joint 154. By coordinating the movements of the boom, the arm, and the working tool of the work implement, the point-of-interest of the working tool engages and acts upon the material to be manipulated along a selected trajectory and at a target velocity. The selected trajectory can be curved as shown (e.g., by pivoting the working tool about the working tool-to-arm linkage joint or by pivoting the arm about the arm-to-boom linkage joint). The selected trajectory can also be linear by coordinating the pivoting of the boom, the arm, and the working tool using inverse kinematic techniques or other suitable techniques (e.g., open loop modeling) to determine the respective pivotal velocities of the three components of the work implement 140.

In the illustrated embodiment, an operator's cab 192 is located on the main frame 130. In the illustrated embodiment, the operator's cab and the work implement 140 are both mounted on the main frame so that the operator's cab faces in the working direction (arrow 176) of the work implement. In the illustrated embodiment, a control station 194 is located in the operator's cab.

The main frame 130 also supports an engine 196 for powering the work machine 120. The engine can be a diesel internal combustion engine or another source of power. In the illustrated embodiment, the engine drives at least one hydraulic pump (not shown) to provide hydraulic power to the various operating systems of the work machine.

As schematically illustrated in FIGS. 2 and 3, user interface units provided within the operator's cab may include a left foot pedal 202, a right foot pedal 204, and an auxiliary foot pedal 206, each associated with further elements which generate signals representing user engagement and manipulation of the respective pedal. Although not illustrated, at least the left foot pedal 202 and the right foot pedal 204 may be associated with levers mechanically attached thereto to at least partially allow for hand control of the respective functions. The operator may use at least the left and right foot pedals 202, 204 to control the travel speed of the traction units 124A, 124B by moving at least the left and right foot pedals 202, 204 by a desired distance.

For a given operation, the operator may designate a desired speed for the engine and a desired speed for the traction unit motors via one or more speed inputs, and then the operator may fine-tune or adjust the travel speed of the work machine 120 using at least the left and right foot pedals 202, 204. The operator may also use foot pedals to control the travel direction of the traction units by moving foot pedals in a desired direction, such as either forward or backward, for example. The operator may command forward movement of the work machine by pressing a desired foot pedal forward (e.g., by applying pressure with the ball of the operator's foot), and may command rearward movement of the work machine by pressing a desired foot pedal backward (e.g., by applying pressure with the heel of the operator's foot).

Typically, the left foot pedal 202 generates signals representative of a desired fore or aft propulsion control for the left traction unit 124A, and the right foot pedal 204 generates signals representative of a desired fore or aft propulsion control for the right traction unit 124B. The auxiliary foot pedal 206 can often be configured to control various functions on the work machine 120, one example being a “single pedal travel” function which utilizes the signal generated by the auxiliary pedal 206 to drive both the left traction unit 124A and the right traction unit 124B of the work machine 120 equally, thereby at least theoretically providing a straight trajectory of motion either a forward or reverse direction.

As schematically illustrated in FIG. 4, the self-propelled work machine 120 includes or is associated with a control system 200 that includes a controller 210. The controller may be part of the machine control system of the work machine 120, or it may be a separate control module. The controller is optionally mounted in the operator's cab 192 at the control station 194. The machine controller can include a control panel with a display unit 216, and may be configured to receive input signals from the various user interface units (e.g., pedals 202, 204, 206 as described above).

Although not illustrated, the controller 210 may receive input signals from other user interface units (e.g., a keyboard, a joystick, or the like) associated with other machine functions, such as for example control of work implements. Also not expressly shown in FIG. 4, the controller 210 may receive signals from the machine control system, signals from machine location determining sensors such as a global navigation satellite system (GNSS) receiver, ground speed sensors, steering sensors, or the like, and/or work implement position sensors such as for example rotary pin encoders mounted at pivot pins to detect the relative rotational positions of the respective components, linear encoders mounted on hydraulic cylinders to detect the respective extensions thereof, and the like.

Additional sensors may be provided and configured to produce signals representing a position, state, or velocity of respective actuators, for example including hydraulic piston-cylinder units associated with respective work machine components.

The controller 210 can be configured to produce outputs to the display unit 216 for displaying information to the human operator. In addition, or in the alternative, the machine controller can be configured to generate control signals for controlling the operation of respective actuators, or generate signals for indirect control via intermediate devices, associated with a left traction unit control system 220, a right traction unit control system 222, and the like. The machine controller 210 can generate control signals for controlling the operation of various actuators, such as hydraulic motors or hydraulic piston-cylinder units. The control signals from the controller can be received by electro-hydraulic control valves associated with the actuators such that the electro-hydraulic control valves control the flow of hydraulic fluid to and from the respective hydraulic actuators to control the actuation thereof in response to the control signal from the controller.

The controller 210 may include, or be associated with, a processor 250, a computer readable medium 252, a communication unit 254, data storage 256 such as for example a database network, and the aforementioned display 216.

The controller described herein may be a single controller having all of the described functionality, or it may include multiple controllers wherein the described functionality is distributed among the multiple controllers. The data storage may generally encompass hardware such as volatile or non-volatile storage devices, drives, memory, or other storage media, as well as one or more databases residing thereon.

Not specifically represented in FIG. 4, the controller 210 of the work machine 120 may in some embodiments further receive inputs from and generate outputs to remote devices associated with a user via a respective user interface, for example a display unit with touchscreen interface. Data transmission between, for example, a machine control system and a remote user interface may take the form of a wireless communications system and associated components as are conventionally known in the art. In certain embodiments, a remote user interface and vehicle control systems for respective work machines may be further coordinated or otherwise interact with a remote server or other computing device for the performance of certain operations in a system as disclosed herein.

Various “computer-implemented” operations, steps or algorithms as described in connection with the controller 210 or in connection with alternative but equivalent computing devices or systems can be embodied directly in hardware, in a computer program product such as a software module executed by the processor 250, or in a combination of the two. The computer program product can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, or any other form of computer-readable medium 252 known in the art. An exemplary computer-readable medium 252 can be coupled to the processor 250 such that the processor 250 can read information from, and write information to, the memory/storage medium 252. In the alternative, the computer-readable medium 252 can be integral to the processor 250. The processor 250 and the computer-readable medium 252 can reside in an application specific integrated circuit (ASIC). The ASIC can reside in a user terminal. In the alternative, the processor 250 and the medium 252 can reside as discrete components in a user terminal.

The term “processor” as used herein may refer to at least general-purpose or specific-purpose processing devices and/or logic as may be understood by one of skill in the art, including but not limited to a microprocessor, a microcontroller, a state machine, and the like. A processor can also be implemented as a combination of computing devices (e.g., a combination of a digital signal processor (DSP) and a microprocessor), a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The communication unit 254 can support or provide communications between the machine controller 210 and external systems or devices, and/or support or provide communication interface with respect to internal components of the self-propelled work machine 120. The communications unit 254 can include wireless communication system components (e.g., via cellular modem, Wi-Fi® systems, Bluetooth® systems, or the like) and/or may include one or more wired communications terminals such as universal serial bus ports.

Referring next to FIG. 5, and still using an excavator as an example of the work machine 120 for illustrative purposes, an exemplary embodiment of a method of operation 300 may now be described. Unless otherwise expressly noted, various steps of the method may be performed at the level of a local work machine controller 210, at the level of a computing device associated with an operator of a work machine or other user, and/or at the level of one or more remote servers communicatively linked thereto. While the illustrated embodiment may include a specific arrangement of steps, inputs, outputs, and the like, it may be understood that certain steps may be combined, performed in a different order, or even omitted altogether in other embodiments within the scope of the present disclosure, unless otherwise specifically noted herein.

The method 300 as illustrated may for example begin in step 302 with operation of the work machine 120 generally, or in some embodiments with user selection of a particular operating mode. The method 300 in step 304 includes the reception of signals from each of the user interface units 202, 204, 206, each of which may be processed in parallel for propulsion control according to at least one operating mode of the work machine. In some embodiments, at least one of the devices such as for example the auxiliary user interface unit 206 may be utilized in some operating modes for control of auxiliary (i.e., non-propulsion related) machine functions, in addition to the at least one operating mode for which the auxiliary inputs are processed in parallel with the input signals from the left user interface unit 202 and the right user interface unit 204.

As previously noted, the auxiliary user interface unit 206 can often be configured to control various functions on the work machine 120, one example being a “single pedal travel” function to drive both the left traction unit 124A and the right traction unit 124B of the work machine equally, thereby at least theoretically providing a straight trajectory of motion either a forward or reverse direction. However, there are known issues in conventional operation of a work machine using a single pedal for travel in a “straight” direction, including the potential for the work machine to start tracking off-course. Various exemplary reasons for why a machine might start tracking off course include, without limitation: slight misalignment in the machine tracking system, causing one traction unit to operate at a slightly different speed than the other; changing terrain, whereby the track or road is not a straight line; differing traction conditions between the left and right traction units causing slight mis-tracking; machine direction not properly established at the start of tracking, etc.

Returning to the embodiment illustrated in FIG. 5, the method 300 includes a step 306 wherein the respective signals from the various user interface units 202, 204, 206 are normalized to a common unit, for example percentage (%) values, whereby operation in the “fore” direction generates a positive signal between 0% and 100%, and operation in the “aft” direction generates a negative signal between 0% and −100%.

Accordingly, a first (i.e., left) user interface unit position value 308, a second (i.e., right) user interface unit position value 310, and a third (i.e., auxiliary) user interface unit position value 312 are established in a common unit framework.

With all user interface unit (e.g., pedal) positions established in common units, the method 300 according to the embodiment represented in FIG. 5 continues in step 314 by determining a left travel command value by adding together the first user interface unit position value 308 and the third user interface unit position value 312, and further continues in step 316 by determining a right travel command value by adding together the second user interface unit position value 310 and the third user interface unit position value 312. This yields respective left travel command and right travel command values that could encompass values between-200% and +200%.

If the summed values for the left travel command value and the right travel command value maintain a magnitude that is less than 100% (i.e., “no” in response to the query of step 318), those commands can be directly applied in step 322 to the left and right travel functions on the work machine, respectively. In this case, the use of both sets of pedals simply create an additive effect with respect to the overall machine tracking function.

If the summed values for the left travel command value and the right travel command value result in a magnitude that is greater than 100% (i.e., “yes” in response to the query of step 318), the method 300 may continue in step 320 by normalizing values back to a +/−100% range. This may in an embodiment be accomplished by dividing both signals by the maximum of the two signals, for example as shown below:

Left ⁢ Travel ⁢ Command = Left ⁢ Travel ⁢ Command MAX ⁡ ( Left ⁢ Travel ⁢ Command , Right ⁢ Travel ⁢ Command ) Right ⁢ Travel ⁢ Command = Right ⁢ Travel ⁢ Command MAX ⁡ ( Left ⁢ Travel ⁢ Command , Right ⁢ Travel ⁢ Command )

This technique for scaling the signals back to a +/−100% range has the potential effect of reducing the command for one traction unit when the operator is trying to inject a signal to the opposite traction unit. One of skill in the art may appreciate that this actually has the effect of ultimately causing the machine to course correct in the direction desired by the operator, but by slowing down one traction unit instead of speeding up the other.

As used herein, the phrase “one or more of,” when used with a list of items, means that different combinations of one or more of the items may be used and only one of each item in the list may be needed. For example, “one or more of” item A, item B, and item C may include, for example, without limitation, item A or item A and item B. This example also may include item A, item B, and item C, or item Band item C.

Thus, it is seen that the apparatus and methods of the present disclosure readily achieve the ends and advantages mentioned as well as those inherent therein. While certain preferred embodiments of the disclosure have been illustrated and described for present purposes, numerous changes in the arrangement and construction of parts and steps may be made by those skilled in the art, which changes are encompassed within the scope and spirit of the present disclosure as defined by the appended claims. Each disclosed feature or embodiment may be combined with any of the other disclosed features or embodiments.