System and method of automated multipass slope control using an initial reference

Abstract

A system and method are provided for operating a work machine (e.g., grader, scraper) which travels across and works a ground surface via a work implement moveable relative to a machine frame. An initial three dimensional (3D) position is determined for a point of interest (POI) associated with the work implement, for example using a GNSS receiver associated with the work implement. A target profile for the ground surface is determined in the 3D coordinate system. During a working operation which includes travel of the work machine via multiple headings across the work area, current headings and positions are continuously monitored in the 3D coordinate system for the POI relative to the initial position, and control signals are generated to at least one actuator for automatically controlling the current position of the POI relative to a corresponding position of the target profile within the 3D coordinate system.

Description

FIELD OF THE DISCLOSURE

[0001] The present disclosure relates generally to work machines having grade control systems and tools that automatically work the ground surface to a reference slope / elevation, and more particularly to techniques for automatic control relative to an initial reference and without for example requiring conventional benching with each grading pass.BACKGROUND

[0002] Work machines within the scope of the present disclosure may for example include crawler dozers, excavators, motor graders, scrapers, backhoes, loaders, forestry machines, front shovel machines, and others. These work machines may typically be self-propelled using wheeled or tracked ground engaging units supporting a frame and / or undercarriage from the ground surface. Work machines as disclosed herein may include for example a work implement, which often includes one or more components such as a blade and an assembly for supporting and positioning the blade relative to the work machine frame, that is used to modify the terrain based on control signals from and / or in coordination with movement of the work machine.

[0003] In the particular context of grade control applications, such systems may be generally split into two broad categories. Two-dimensional grade control is where the work machine is expected to cut a surface in one direction. The two dimensions controlled by the grade control system are the depth of cut and the slope of cut. Three-dimensional grade control is used when the grade control system needs to cut a compound slope or in situations where lateral positioning of the work machine is important.

[0004] For many conventional applications, three-dimensional grade control may be undesirable due to the cost and complexity involved. It may be desirable, however, to provide in a cost-effective manner a certain degree of three-dimensional grading functionality in applications being performed by work machines such as compact machines which are typically configured for two-dimensional grade control.

[0005] One of the conventional challenges in two-dimensional grading applications is how to maintain a common elevation as the ground engaging units of the work machine are moved. When using a laser plane, the grade control system may determine the depth of the desired surface from the laser plane. A sensor such as a conventional laser receiver senses the laser and corrects for any change in vertical reference due to track motion. When the laser plane is sloped, the work machine is able to cut a sloped surface. However, this requires the work machine to be oriented either in parallel or perpendicular with respect to the slope of the laser plane. If the work machine is misaligned, the slope it cuts will not be parallel to the laser plane, since the grade control system does not know how to orient its internal slope command relative to the elevation of the laser plane and can only adjust the depth of cut.

[0006] Conventional slope control solutions for bladed products can also be difficult to operate due to a lack of understanding among many operators regarding how the systems work. Operators expect, for example, to grade to a target surface mainfall, cross-slope and elevation from a known benchmark. This may involve an initial setup for these three parameters, moving the work implement to a known elevation, and pressing a button to benchmark the current implement position relative to the machine platform, typically for each grading pass. However, errors are typical in practice when it comes to understanding and actually implementing a reset at the start of each pass to maintain the desired plane / grade. This lack of understanding may be overcome with training or by adding additional technology to the machine to make operation more intuitive, but either of these options may be relatively unattractive due to the added time, cost, etc.BRIEF SUMMARY

[0007] The current disclosure provides an enhancement to conventional systems, at least in part by introducing slope control enhancements where, e.g., the user will “bench / measure in” a starting position and the machine will control the blade to the correct grade (e.g., elevation) over the entire work area, without re-benching. This may be implemented through the use of a differential positioning system, such as for example a Global Navigational Satellite System (GNSS) receiver associated with the blade, to select a starting position and track the location of the work machine relative to that point in a multi-dimensional coordinate system (e.g., utilizing northing, easting and elevation).

[0008] Advantages of the above-referenced enhancements may include extremely simple set up for the user, without any localization, base stations, or external equipment. Solutions according to the present disclosure may accordingly be implemented in the three-dimensional (3D) setup of designs from the operator cab of a work machine for simple pads, mass hauling operations, as a lower cost option for compact machines, more flexible two-dimensional (2D) enhancements, and the like.

[0009] In one particular and exemplary embodiment, a method is disclosed herein for operating a work machine comprising a plurality of ground-engaging units supporting a machine frame and driven to cause the work machine to travel across a ground surface. The work machine further comprises a work implement supported by and moveable relative to the machine frame and configured to controllably work the ground surface. As part of the method, an initial position is determined in a three dimensional coordinate system for a point of interest associated with the work implement. A point of interest associated with the work implement may typically refer to a cutting edge, cutting vector, or some point associated therewith, such as for example on one end of the cutting edge or cutting vector, but may be any of various alternative points associated with the work implement as may be relevant for a given work application or work machine configuration.

[0010] A target profile for the ground surface associated with a work area is further determined in the three dimensional coordinate system. During an operating mode corresponding to a working operation and involving travel of the work machine via a plurality of headings across the work area, the method further includes continuously monitoring a current heading and a current position in the three dimensional coordinate system for the point of interest relative to the initial position, and generating control signals to at least one actuator for automatically controlling the current position of the point of interest relative to a corresponding position of the target profile within the three dimensional coordinate system.

[0011] In one exemplary aspect according to the above-referenced method embodiment, respective positions and movement of the point of interest may be determined via at least signals from a remote source to a receiver associated with the work implement. The receiver may for example be associated with a differential global positioning system (GPS) or a global navigation satellite system (GNSS).

[0012] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, respective positions and movement may be determined for each of a first point of interest and a second point of interest associated with the work implement, wherein a cutting edge vector may be defined in association with the first and second points of interest.

[0013] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, a current position and orientation of the cutting edge vector may be controlled relative to the target profile.

[0014] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, the respective positions and movement for the first point of interest may be determined via at least signals received by a first receiver associated with the work implement and the respective positions and movement for the second point of interest may be determined via at least signals received by a second receiver associated with the work implement.

[0015] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, the respective positions and movement for the first point of interest may be determined via at least signals received by the receiver associated with the work implement and the respective positions and movement for the second point of interest may be determined via at least signals from an inertial measurement sensor associated with the work implement.

[0016] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, respective positions and movement of the point of interest may be determined via signals from a remote source to a receiver associated with the machine frame of the work machine and signals from at least an inertial measurement sensor associated with the work implement, wherein a current position of the point of interest relative to the machine frame may be determined in a first three dimensional coordinate system associated with the work machine and converted to a current position of the point of interest in a second three dimensional coordinate system associated with the target profile.

[0017] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, respective positions and movement may be determined for each of a first point of interest and a second point of interest associated with the work implement, wherein a cutting edge vector is defined in association with the first and second points of interest.

[0018] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, a current position and orientation of the cutting edge vector may be controlled relative to the target profile.

[0019] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, the target profile associated with the work area may be retrieved from data storage via a vector based digital geographic data file.

[0020] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, the target profile may be determined at least in part via user input received from a user interface in association with the working operation.

[0021] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, upon determining the initial position and the target profile, output signals may be generated to a display unit for generating indicia guiding manual control of the work implement with respect to the target profile, wherein automatic control of the current position of the point of interest may be enabled when the current position of the point of interest is within a defined proximity with respect to the target profile.

[0022] In another exemplary aspect according to the above-referenced method embodiment and optionally one or more of the aspects thereof, a common measuring-in location may be defined which is usable by a plurality of work machines to get on the same basic planes.

[0023] In another embodiment as disclosed herein, a work machine comprises a machine frame, a plurality of ground-engaging units supporting the machine frame and driven to cause the work machine to travel across a ground surface, and a work implement supported by and moveable relative to the machine frame and configured to controllably work the ground surface. One or more processors are 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.

[0024] 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

[0025] FIG. 1 is a perspective view of a work machine incorporating or otherwise implementing an embodiment of a system and method as disclosed herein.

[0026] FIG. 2 is a block diagram representing an exemplary control system according to an embodiment of the present disclosure.

[0027] FIG. 3 is a block diagram of an exemplary tool / implement control unit according to the embodiment of the work machine of FIG. 1 and the control system of FIG. 2.

[0028] FIG. 4 is a schematic diagram representing an example of an initial (actual) surface profile and a target surface profile associated with a work operation.

[0029] FIG. 5 is flowchart representing an exemplary embodiment of a method as disclosed herein.DETAILED DESCRIPTION

[0030] FIG. 1 is a perspective view of a work machine 100. In the illustrated embodiment, the work machine 100 is a crawler dozer, but may be any work machine with a ground-engaging blade or equivalent work implement 142 such as a compact track loader, motor grader, scraper, skid steer, excavator, to name but a few examples. The work machine may be operated to engage the ground and grade, cut, and / or move material to achieve simple or complex features on the ground. While operating, the work machine may experience movement in three directions and rotation in three directions. A direction for the work machine may also be referred to with regard to a longitudinal direction 102, a latitudinal or lateral direction 106, and a vertical direction 110. Rotation for work machine 100 may be referred to as roll 104 or the roll direction, pitch 108 or the pitch direction, and yaw 112 or the yaw direction or heading.

[0031] An operator's cab 136 may be located on the main frame 140. The operator's cab and the work implement 142 may both be mounted on the main frame so that the operator's cab faces in the working direction of the working implement. A control station including a user interface (214, see FIG. 2) may be located in the operator's cab. As used herein, directions with regard to work machine 100 may be referred to from the perspective of an operator seated within the operator cab: the left of work machine is to the left of such an operator, the right of work machine is to the right of such an operator, the front or fore of work machine is the direction such an operator faces, the rear or aft of work machine is behind such an operator, the top of work machine is above such an operator, and the bottom of work machine is below such an operator.

[0032] With further reference to FIG. 2, a “user interface”214 as used herein may include or otherwise broadly take the form of a display unit 216 and / or other outputs from the system such as indicator lights, audible alerts, and the like. The user interface may further or alternatively include various controls or user inputs (e.g., a steering wheel, joysticks, levers, buttons) for operating the work machine 100, including operation of the engine 134, hydraulic cylinders 150, 152, 154, and the like. Such an onboard user interface may be coupled to a vehicle control system via for example a CAN bus arrangement or other equivalent forms of electrical and / or electro-mechanical signal transmission. Another form of user interface (not shown) may take the form of a display unit that is generated on a remote (i.e., not onboard) user computing device 242 based on signals received via for example a cloud network 240, which may display outputs such as status indications and / or otherwise enable user interaction such as the providing of inputs to the system. In the context of a remote user interface, data transmission between for example the work machine control system and the 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 100 may be further coordinated or otherwise interact with a remote server or other computing device for the performance of operations in a system as disclosed herein.

[0033] The control system 200 as represented in FIG. 2 includes a controller 210. The controller 210 may be part of the machine control system of the working machine, or it may be a separate control module. Accordingly, the controller 210 may generate control signals for controlling the operation of various actuators throughout the work machine 100, which may for example be hydraulic motors, hydraulic piston-cylinder units, electric actuators, or the like. The various actuators may for example be associated with a propulsion / steering control unit 230, a work tool / implement control unit 232, and the like. Electronic control signals from the controller may for example be received by electro-hydraulic control valves associated with respective actuators, wherein 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.

[0034] The controller 210 may include or be functionally linked to the user interface 214 and optionally be mounted in the operators cab 136 at a control panel.

[0035] The controller 210 is configured to receive input signals from some or all of various sensors 144, 164 associated with the work machine 100, which in the present disclosure at least includes a first set of one or more sensors 144 affixed to the main frame 140 of the work machine 100 and configured to provide a signal indicative of the movement and orientation of the main frame, and a second set of one or more sensors 164 configured to provide at least a signal indicative of a work implement (blade) position. Various of the sensors 144, 164 may typically be discrete in nature, but signals representative of more than one input parameter relevant to the respective positions and / or orientations of the machine frame and / or work implement may be provided from the same sensor, and a sensor system 144, 164 as disclosed herein may further include or otherwise refer to signals provided from the machine control system.

[0036] In alternative embodiments, the first sensor 144 may not be affixed directly to the main frame 140, but may instead be connected to the main frame through intermediate components or structures, such as rubberized mounts. In these alternative embodiments, the sensor 144 is not directly affixed to the main frame but is still connected to the main frame at a fixed relative position so as to experience the same motion as the main frame.

[0037] The sensor 144 is configured to provide a signal indicative of the inclination of the main frame 140 relative to the direction of gravity, an angular measurement in the direction of pitch 108. This signal may be referred to as a main frame pitch angle signal. The sensor 144 may also be configured to provide a signal or signals indicative of other positions or velocities of the main frame, including its angular position, velocity, or acceleration in a direction such as the direction of roll 104, pitch 108, yaw 112, or its linear acceleration in a longitudinal 102, latitudinal 106, and / or vertical 110 direction. The sensor 144 may be configured to directly measure inclination, measure angular velocity and integrate to arrive at inclination, or measure inclination and derive to arrive at angular velocity.

[0038] The sensor 144 may typically, e.g., be comprised of an inertial measurement unit (IMU) mounted on the main frame 140 and configured to provide at least a main frame pitch angle signal and an angular velocity signal to the controller 210 as inputs for the control method as further disclosed below. Such an IMU may for example be in the form of a three-axis gyroscopic unit configured to detect changes in orientation of the sensor, and thus of the main frame to which it is fixed, relative to an initial orientation.

[0039] The second sensor 164 or set of one or more sensors 164 may include a GNSS receiver fixed relative to the work implement 142, the main frame 140, and / or the implement control unit 232, which can detect the absolute position and orientation of the work implement within an external and three-dimensional coordinate system by way of communications with one or more satellites 166, and can detect changes in such position and orientation. In some embodiments, the second set of sensors 164 may include a camera based system which can observe surrounding structural features via image processing, and can respond to the orientation of the working machine relative to those surrounding structural features. In some embodiments, a GNSS receiver may be affixed directly to the work implement 142 (blade), wherein the spatial position and orientation of one or more points of interest on the work implement are determined directly in a three-dimensional coordinate system. In other embodiments, a GNSS receiver may be affixed to the main frame 140, wherein kinematics, image classification, or the like are utilized to determine the spatial position and orientation of one or more points of interest on the work implement, at least in part by converting a calculated position in a coordinate system local to the work machine to a calculated position in a global coordinate system independent of the work machine.

[0040] The controller 210 in an embodiment (not shown) may include or may be associated with a processor 222, a computer readable medium 224, a communication unit 226, data storage 228 such as for example a database network, and the aforementioned user interface 214 or control panel having a display unit 216. An input / output device, such as a keyboard, joystick or other user interface tool, may be provided so that a human operator may input instructions to the controller. It is understood that 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.

[0041] Various operations, steps or algorithms as described in connection with the controller 210 can be embodied directly in hardware, in a computer program product such as a software module executed by a processor, 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 known in the art. An exemplary computer-readable medium 224 can be coupled to the processor 222 such that the processor can read information from, and write information to, the memory / storage medium. In the alternative, the medium can be integral to the processor. The processor and the medium can reside in an application specific integrated circuit (ASIC). The ASIC can reside in a user terminal. In the alternative, the processor and the medium can reside as discrete components in a user terminal.

[0042] The term “processor”222 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 DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0043] The communication unit 226 may support or provide communications between the controller 210 and external systems or devices, for example via cloud network 240, and / or support or provide communication interface with respect to internal components of the work machine 100. The communications unit may include wireless communication system components (e.g., via cellular modem, WiFi, Bluetooth or the like) and / or may include one or more wired communications terminals such as universal serial bus ports.

[0044] Data storage 228 as discussed herein may, unless otherwise stated, 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.

[0045] Returning to FIG. 1 for illustrative purposes, the work machine 100 is supported on the ground by an undercarriage 114. The undercarriage 114 includes ground engaging units 116, 118, which in the present example are formed by a left track 116 and a right track 118, and provide tractive force for the work machine 100. Each track may be comprised of shoes with grousers that sink into the ground to increase traction, and interconnecting components that allow the tracks to rotate about front idlers 120, track rollers 122, rear sprockets 124 and top idlers 126. In alternative embodiments, the ground engaging units 116, 118 may comprise, e.g., wheels on the left and right sides of the work machine.

[0046] The undercarriage 114 is affixed to, and provides support and tractive effort for, the main frame 140 of the work machine 100. The main frame is the frame which provides structural support and rigidity to the work machine, allowing for the transfer of force between the blade 142 and the left track 116 and right track 118. In this embodiment, the main frame is a weldment comprised of multiple formed and joined steel members, but in alternative embodiments it may be comprised of any number of different materials or configurations.

[0047] The blade 142 is a work implement which may engage the ground or material, for example to move material from one location to another and to create features on the ground, including flat areas, grades, hills, roads, or more complexly shaped features. In this embodiment, the blade of the work machine 100 may be referred to as a six-way blade, six-way adjustable blade, or power-angle-tilt (PAT) blade. The blade may be hydraulically actuated to move vertically up or down (hereinafter, blade “lift”), roll left or right (hereinafter, blade “tilt”), and yaw left or right (hereinafter, blade “angle”). Alternative embodiments may utilize a blade with fewer hydraulically controlled degrees of freedom, such as a 4-way blade that may not be angled, or actuated in the direction of yaw 112.

[0048] The blade 142 is movably connected to the main frame 140 of the work machine 100 through a linkage 146 which supports and actuates the blade and is configured to allow the blade to be lifted (i.e., raised or lowered in the vertical direction 110) relative to the main frame. The linkage may include multiple structural members to carry forces between the blade and the remainder of the work machine, and may provide attachment points for hydraulic cylinders which may actuate the blade in the lift, tilt, and angle directions. An implement control unit 232 as referred to herein, and as further described below with respect to FIG. 3, may for example comprise the linkage, along with the hydraulic cylinders, and additional and / or equivalent structures associated with actuation of the blade in the lift, tilt, and angle directions.

[0049] The linkage 146 includes a c-frame 148, a structural member with a C-shape positioned rearward of the blade 142, with the C-shape open toward the rear of the work machine 100. Each rearward end of the c-frame is pivotally connected to the main frame 140 of the work machine 100, such as through a pin-bushing joint, allowing the front of the c-frame to be raised or lowered relative to the work machine about the pivotal connections at the rear of the c-frame. The front portion of the c-frame, which is approximately positioned at the lateral center of the work machine, connects to the blade through a ball-socket joint. This allows the blade three degrees of freedom in its orientation relative to the c-frame (lift-tilt-angle) while still transferring rearward forces on the blade to the remainder of the work machine.

[0050] The work implement 142 may be adjusted in position (i.e., raised or lowered) relative to the work machine 100 by the actuation of lift cylinders 150, which may raise and lower the c-frame 148. For each of the lift cylinders, the rod end is pivotally connected to an upward projecting clevis of the c-frame and the head end is pivotally connected to the remainder of the work machine just below and forward of the operator cab 136. The configuration of the linkage 146 and the positioning of the pivotal connections for the head end and rod end of the lift cylinders results in the extension of the lift cylinders lowering the blade and the retraction of the lift cylinders raising the blade. In alternative embodiments, the blade may be raised or lowered by a different mechanism, or the lift cylinders may be configured differently, such as a configuration in which extension of the lift cylinders raises the blade and retraction of the lift cylinders lowers the blade. In a particular embodiment, at least one of the second set of sensors 164 may be located in association with the lift cylinders, for example to generate an output signal corresponding to an extension of the lift cylinders.

[0051] The blade 142 may be tilted relative to the work machine 100 by the actuation of a tilt cylinder 152, which may also be referred to as moving the blade in the direction of roll 104. The rod end of the tilt cylinder is pivotally connected to a clevis positioned on the back and left sides of the blade above the ball-socket joint between the blade and the c-frame and the head end is pivotally connected to an upward projecting portion of the linkage 146. The positioning of the pivotal connections for the head end and the rod end of the tilt cylinder result in extension of the tilt cylinder tilting the blade to the left (or counterclockwise when viewed from the operator cab 136) and retraction of the tilt cylinder tilting the blade to the right (or clockwise when viewed from the operator cab. In alternative embodiments, the blade may be tilted by a different mechanism (e.g., an electrical or hydraulic motor) or the tilt cylinder may be configured differently, such as a configuration in which it is mounted vertically and positioned on the left or right side of the blade, or a configuration with two tilt cylinders.

[0052] The blade 142 may be angled relative to the work machine 100 by the actuation of angle cylinders 154, which may also be referred to as moving the blade in the direction of yaw 112. For each of the angle cylinders, the rod end is pivotally connected to a clevis of the blade while the head end is pivotally connected to a clevis of the c-frame 148. One of the angle cylinders is positioned on the left side of the work machine, left of the ball-socket joint between the blade and the c-frame, and the other of the angle cylinders is positioned on the right side of the work machine, right of the ball-socket joint between the blade and the c-frame. This positioning results in the extension of the left of the angle cylinders and the retraction of the right of the angle cylinders angling the blade rightward, or yawing the blade clockwise when viewed from above, and the retraction of left of the angle cylinders and the extension of the right of the angle cylinders angling the blade leftward, or yawing the blade counterclockwise when viewed from above. In alternative embodiments, the blade may be angled by a different mechanism or the angle cylinders may be configured differently.

[0053] Due to the geometry of the linkage 146 in this embodiment, the blade 142 is not raised or lowered in a perfectly vertical line with respect to the work machine 100. Instead, a point on the blade would trace a curve as the blade is raised and lowered. This means that the vertical component of the velocity of the blade is not perfectly proportional to the linear velocity with which the lift cylinders 150 are extending or retracting, and the vertical component of the blade's velocity may vary even when the linear velocity of the lift cylinders is constant. This also means that the lift cylinders have a mechanical advantage which varies depending on the position of the linkage. Given a kinematic model of the blade and the linkage (e.g., formula(s) or table(s) providing a relationship between the position and / or movement of portions of the blade and the linkage) and the state of the blade and the linkage (e.g., sensor(s) sensing one or more positions, angles, or orientations of the blade or linkage, such as the sensor 164), at least with respect to blade lift, the controller 210 may compensate for such non-linearity. Incomplete or simplified kinematic models may be used if there is a need to only focus on particular motion relationships (e.g., only those affecting blade lift) or if only limited compensation accuracy is desired. The controller 210 may utilize this compensation and a desired velocity, for example a command to raise the blade at a particular vertical velocity, to issue a command that may achieve a flow rate into the lift cylinders that results in the blade being raised at the particular vertical velocity regardless of the current position of the linkage. For example, the controller 210 may issue commands which vary the flow rate into the lift cylinders in order to achieve a substantially constant vertical velocity of the blade.

[0054] Similarly, due to the positioning of the tilt cylinder 152 and the angle cylinders 154 and the configuration of their connection to the blade 142, the angular velocity of the blade tilt and angle is not perfectly proportional to the linear velocity of the tilt cylinder and the angle cylinders, respectively, and the angular velocity of tilt and angle may vary even when the linear velocity of the tilt cylinder and angle cylinders, respectively, is constant. This also means that the tilt cylinder and the angle cylinders each have a mechanical advantage which varies depending on the position of the blade. Much like with the lift cylinders, given a kinematic model of the blade and the linkage, and the state of the blade and the linkage, at least with respect to the blade tilt and angle, the controller 210 may compensate for such non-linearity. Incomplete or simplified kinematic models may be used if there is a need to only focus on particular motion relationships (e.g., only those affecting blade tilt and angle) or if only limited compensation accuracy is required. The controller 210 may utilize this compensation and a desired angular velocity, for example a command to tilt or angle the blade at a particular angular velocity, to issue commands that may vary the flow rate into the tilt cylinder or angle cylinders to result in the blade being tilted or angled at the particular angular velocity regardless of the current position of the blade or linkage.

[0055] In alternative embodiments, the blade 142 may be connected to the remainder of the work machine 100 in a manner which tends to make the blade lift velocity (in the vertical direction 110), tilt angular velocity (in the direction of roll 104), or angle angular velocity (in the direction of yaw 112) proportional to the linear velocity of the lift cylinders 150, tilt cylinder 152, or angle cylinders 154, respectively. This may be achieved with particular designs of the linkage 146 and positioning of the pivotal connections of the lift cylinders 150, tilt cylinder 152, and angle cylinders 154. In such alternative embodiments, the controller 210 may not need to compensate for non-linear responses of the blade 142 to the actuation of the lift cylinders 150, tilt cylinder 152, and angle cylinders 154, or the need for compensation may be reduced.

[0056] Each of the lift cylinders 150, tilt cylinder 152, and angle cylinders 154 may be a double acting hydraulic cylinder. One end of each cylinder may be referred to as a head end, and the end of each cylinder opposite the head end may be referred to as a rod end. Each of the head end and the rod end may be fixedly connected to another component or, as in this embodiment, pivotally connected to another component, such as a through a pin-bushing or pin-bearing coupling, to name but two examples of pivotal connections. As a double acting hydraulic cylinder, each may exert a force in the extending or retracting direction. Directing pressurized hydraulic fluid into a head chamber of the cylinders will tend to exert a force in the extending direction, while directing pressurized hydraulic fluid into a rod chamber of the cylinders will tend to exert a force in the retracting direction. The head chamber and the rod chamber may both be located within a barrel of the hydraulic cylinder, and may both be part of a larger cavity which is separated by a movable piston connected to a rod of the hydraulic cylinder. The volumes of each of the head chamber and the rod chamber change with movement of the piston, while movement of the piston results in extension or retraction of the hydraulic cylinder.

[0057] In an embodiment, the operator may be enabled to define a longitudinal slope (mainfall) target setting and a lateral slope (cross-slope) target setting via the user interface 214. These settings, together with an elevation target setting as further discussed below, may define a target surface profile, the target surface profile further corresponding to an amount of material to be graded away from an initial or current surface profile. It may be understood that alternative target profile parameters, whether geometric, geographical, or the like, may be utilized within the scope of the present disclosure and as may for example reasonably be applied for a given type of work machine, terrain characteristics, work cycle, environmental conditions, or the like.

[0058] FIG. 3 is an illustrative schematic of an implement control unit 232, for example including hydraulic and electrical components for controlling a position of the blade 142. Each of the lift cylinders 150, the tilt cylinder 152, and the angle cylinders 154 is hydraulically connected to a hydraulic control valve 156, which may be positioned in an interior area of the work vehicle 100. The hydraulic control valve may also be referred to as a valve assembly or manifold. The hydraulic control valve receives pressurized hydraulic fluid from a hydraulic pump 158, which may be rotationally connected to the engine 134, and directs such fluid to the lift cylinders, the tilt cylinder, the angle cylinders, and other hydraulic circuits or functions of the work vehicle. The hydraulic control valve may meter such fluid out, or control the flow rate of hydraulic fluid to each hydraulic circuit to which it is connected. In alternative embodiments, the hydraulic control valve may not meter such fluid out but may instead only selectively provide flow paths to these functions while metering is performed by another component (e.g., a variable displacement hydraulic pump) or not performed at all. The hydraulic control valve may meter such fluid out through a plurality of spools, whose positions control the flow of hydraulic fluid, and other hydraulic logic. The spools may be actuated by solenoids, pilots (e.g., pressurized hydraulic fluid acting on the spool), the pressure upstream or downstream of the spool, or some combination of these and other elements.

[0059] In accordance with the embodiment illustrated in FIG. 1, the spools of the hydraulic control valve 156 are shifted by pilots whose pressure is controlled, at least in part, by an electrohydraulic pilot valve 160 in communication with the controller 210. The electrohydraulic pilot valve is positioned within an interior area of the work machine 100 and receives pressurized hydraulic fluid from a hydraulic source and selectively directs such fluid to pilot lines hydraulically connected to the hydraulic control valve. In this embodiment the hydraulic control valve and the electrohydraulic pilot valve are separate components, but in alternative embodiments the two valves may be integrated into a single valve assembly or manifold. In this embodiment, the hydraulic source is a hydraulic pump 158. In alternative embodiments, a pressure reducing valve may be used to reduce the pressure of pressurized hydraulic fluid provided by the hydraulic pump to a set pressure, for example 600 pounds per square inch, for usage by the electrohydraulic pilot valve. In the embodiment illustrated in FIG. 3, individual valves within the electrohydraulic pilot valve reduce the pressure from the received hydraulic fluid via solenoid-actuated spools which may drain hydraulic fluid to a hydraulic reservoir. In this embodiment, the controller 210 actuates these solenoids by sending a specific current to each (e.g., 600 mA). In this way, the controller 210 may actuate the blade 142 by issuing electrical commands signals to the electrohydraulic pilot valve, which in turn provides hydraulic signals (pilots) to the hydraulic control valve, which shift spools to direct hydraulic flow from the hydraulic pump to actuate the lift cylinders 150, the tilt cylinder 152, and the angle cylinders 154. In this embodiment, the controller is in direct communication with the electrohydraulic pilot valve via electrical signals sent through a wire harness and is indirectly in communication with the hydraulic control valve via the electrohydraulic pilot valve.

[0060] In alternative embodiments, the controller 210 may send a command to actuate the blade 142 in a number of different manners. As one example, the controller may be in communication with a valve controller via a controlled area network (CAN) and may send command signals to the valve controller in the form of CAN messages. The valve controller may receive these messages from the controller and send current to specific solenoids within the electrohydraulic pilot valve 160 based on those messages. As another example, the controller may actuate the blade 142 by actuating an input in the operator cab 136. For example, an operator may use a joystick to issue commands to actuate the blade, and the joystick may generate hydraulic pressure signals, pilots, which are communicated to the hydraulic control valve 156 to cause the actuation of the blade. In such a configuration, the controller may be in communication with electrical devices (e.g., solenoids, motors) which may actuate a joystick in the operator cab. In this way, the controller may actuate the blade by actuating these electrical devices instead of communicating signals to electrohydraulic pilot valve.

[0061] Referring next to FIGS. 4 and 5, an exemplary embodiment of a method 300 may be described for operating a work machine 100, including for example controlling movements (e.g., associated with grading operations) of one or more work implements 142 for a work machine 100, wherein an initial ground surface profile 260 is to be worked to a target surface profile 250.

[0062] The illustrated method 300 may begin in step 310 with positioning of the work machine by the user with respect to a specified or otherwise relevant starting location with respect to the work area. The starting location may for example be any location selected by the user and suitable for use as a reference for subsequent tracking of the work machine throughout the working operation. Alternatively, the starting location in some embodiments may be specified as a common measuring-in location relative to the work area that may be used by any of multiple work machines performing such operations, for example to get on the same basic planes.

[0063] With the work machine in its starting location, the method 300 may continue in step 320 by identifying a corresponding reference location for the work implement in a three-dimensional coordinate system. In various embodiments, the reference location is more particularly determined in a three dimensional coordinate system for one or more points of interest associated with the work implement.

[0064] A reference location may be identified using input sensor signals 322, such as from the second set of sensors 164, for example a GNSS sensor located on the work implement 142 or otherwise on the main frame 140 or a component of the implement control unit 232 and further in combination with one or more IMUs or other movement sensors.

[0065] The reference location may further be identified in part via user input signals 324 from the user interface 214, for example to define or confirm measurements provided via the above-referenced sensor signals.

[0066] The illustrated method 300 continues in step 330 with retrieval or otherwise defining of a target ground surface profile (e.g., mainfall, cross-slope, longitudinal slope, elevation) associated with the work area and in the three dimensional coordinate system associated with the identified reference location.

[0067] The target profile 250 may be generated in various embodiments at the outset of a work operation via user input signals 324 from the user interface 214. For example, the user may define a desired elevation and / or slope, wherein the target profile for a given work area is generated based on this input and extending directly from the reference location. The target profile, upon being generated based on the user inputs and reference location, may for example be stored in the form of a vector based digital geographic data file associated with the work area and used during a current work operation and / or selectively retrievable during later work operations. User inputs for defining the target profile may include values entered in response to prompts or into relevant portions of a data entry field, or for example based on specified user interactions such as for example the pressing of a button located on a joystick in the operator cab to define a target profile value (e.g., target elevation) based on a corresponding current value (e.g., current elevation) of the point of interest.

[0068] The target profile 250 may in accordance with step 330 be predetermined and retrieved from data storage, for example in the form of a vector based digital geographic data file associated with the work area. In various embodiments a predetermined target profile may be retrieved or otherwise obtained, and then confirmed via user input signals at the outset of the work operation and / or via scanning of the current ground surface profile.

[0069] Upon initiating an operating mode corresponding to a working operation and involving travel of the work machine via a plurality of headings across the work area, the illustrated method 300 may continue in step 340 by monitoring a current blade position, and more particularly the positions of one or more points of interest associated with the blade, relative to the target profile. In a preferred embodiment, the positions of the one or more points of interest are monitored as the work machine traverses the work area, and throughout heading changes, relative to the initial reference position and without requiring referencing (i.e., benching) at the outset of a new heading.

[0070] In an embodiment, respective positions and movement of the point of interest as the work machine traverses the work area may be determined via at least signals from a remote source, such as one or more satellites in a global network, to a receiver associated with the work implement. Depending, for example, on the location and / or configuration of the receiver and network, the receiver may directly output data corresponding to a location of a point of interest for the work implement in a three dimensional coordinate system, or may simply output signals to an external device (e.g., the above-referenced controller) for real time kinematic (RTK) or differential positioning. A receiver “associated with the work implement” may for example be positioned directly on, positioned within, or integrated with the work implement, or may be positioned externally with respect to the work implement wherein signals from the receiver are fused or otherwise processed further in view of signals from one or more other sensors to calculate the location of the point of interest.

[0071] In an embodiment, respective positions and movement may be determined as the work machine traverses the work area for each of a first point of interest and a second point of interest associated with the work implement, wherein a cutting edge vector is defined in association with the first and second points of interest.

[0072] In an embodiment, respective positions and movement for the first point of interest may be determined via at least signals received by a first receiver associated with the work implement, and respective positions and movement for the second point of interest may be determined via at least signals received by a second receiver associated with the work implement.

[0073] In an embodiment, respective positions and movement for the first point of interest may be determined via at least signals received by the receiver associated with the work implement and the respective positions and movement for the second point of interest may be determined via at least signals from an inertial measurement sensor associated with the work implement.

[0074] The illustrated method 300 may continue in step 350 by determining whether automatic control mode has been enabled or activated. For example, in various embodiments automatic control may be manually enabled or activated by user input via a user interface 214, or may be automatically enabled or activated when the current position of the point of interest is within a defined proximity with respect to the target profile. Automatic control in some embodiments may require both of a user selection and the current position of the point of interest is within the defined proximity with respect to the target profile, or some other combination of variables.

[0075] If the automatic control has not been enabled or activated (i.e., “no” in response to the query of step 350), the method 300 proceeds to step 360 wherein indicia is displayed to the operator, for example for guiding manual control of the work implement, and more particularly manual control of one or more points of interest associated with the work implement with respect to the target surface profile. The indicia may for example be displayed on a display unit 216 associated with the work machine 100, for example in the operator cab 136, on a mobile computing device 242 carried by an operator or other user, or the like. In an embodiment, audiovisual indicators may be provided, such as for example light bars or digital readouts arranged to prompt manual adjustment of the blade elevation and / or pitch to a desired starting point for activation of automatic control. The indicia may for example correspond to one or more determined error values (e.g., in absolute or relative form) between the current position and orientation of the work implement and respective desired components corresponding to the target surface profile such as pitch, elevation, etc. Even in embodiments where such error values are not expressly determined and accordingly displayable, additional or alternative indicia may be displayable, including for example an actual (i.e., detected) and / or target lift position of the blade relative to the machine frame, one or more characteristics of a desired profile with respect to the ground surface, control signals associated with a controlled position of the blade, and the like.

[0076] If the automatic control has been enabled or activated (i.e., “yes” in response to the query of step 350), the method 300 proceeds to step 370 and control signals are generated to one or more actuators associated with the relevant control units to automatically control current positions of the one or more points of interest associated with the work implement relative to corresponding positions of the target profile within the three dimensional coordinate system.

[0077] In certain embodiments, wherein for example a cutting edge vector is defined in association with first and second points of interest as described above, a current position and orientation of the cutting edge vector may be controlled relative to a corresponding vector associated with the target profile.

[0078] Controlled position of the work implement to control the position of the associated point(s) of interest may include for example extending, lifting / lowering, pivoting, and / or rotating the work implement, among other possibilities depending on the type of work machine and / or work implement. Control of the point of interest associated with the work implement as described above may include not only controlled movement of the work implement relative to the machine frame of the work machine, but also controlled movement of one or more components of the work machine itself, such as for example control signals for actuation of elements associated with an advance speed (e.g., drivetrain), steering of ground engaging units, and / or orientation of the main frame.

[0079] 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.

[0080] 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.

Claims

1. A method of operating a work machine comprising a plurality of ground-engaging units supporting a machine frame and driven to cause the work machine to travel across a ground surface, the work machine further comprising a work implement supported by and moveable relative to the machine frame and configured to controllably work the ground surface, the method comprising:determining an initial position in a three dimensional coordinate system for a point of interest associated with the work implement;determining a target profile for the ground surface associated with a work area and in the three dimensional coordinate system; andduring an operating mode corresponding to a working operation and involving travel of the work machine via a plurality of headings across the work area:continuously monitoring a current heading and a current position in the three dimensional coordinate system for the point of interest relative to the initial position; andgenerating control signals to at least one actuator for automatically controlling the current position of the point of interest relative to a corresponding position of the target profile within the three dimensional coordinate system.

2. The method of claim 1, wherein respective positions and movement of the point of interest are determined via at least signals from a remote source to a receiver associated with the work implement.

3. The method of claim 2, wherein respective positions and movement are determined for each of a first point of interest and a second point of interest associated with the work implement, wherein a cutting edge vector is defined in association with the first and second points of interest.

4. The method of claim 3, wherein a current position and orientation of the cutting edge vector is controlled relative to the target profile.

5. The method of claim 3, wherein the respective positions and movement for the first point of interest are determined via at least signals received by a first receiver associated with the work implement and the respective positions and movement for the second point of interest are determined via at least signals received by a second receiver associated with the work implement.

6. The method of claim 3, wherein the respective positions and movement for the first point of interest are determined via at least signals received by the receiver associated with the work implement and the respective positions and movement for the second point of interest are determined via at least signals from an inertial measurement sensor associated with the work implement.

7. The method of claim 1, wherein respective positions and movement of the point of interest are determined via signals from a remote source to a receiver associated with the machine frame of the work machine and signals from at least an inertial measurement sensor associated with the work implement, wherein a current position of the point of interest relative to the machine frame is determined in a first three dimensional coordinate system associated with the work machine and converted to a current position of the point of interest in a second three dimensional coordinate system associated with the target profile.

8. The method of claim 7, wherein respective positions and movement are determined for each of a first point of interest and a second point of interest associated with the work implement, wherein a cutting edge vector is defined in association with the first and second points of interest.

9. The method of claim 8, wherein a current position and orientation of the cutting edge vector is controlled relative to the target profile.

10. The method of claim 1, wherein the target profile associated with the work area is retrieved from data storage via a vector based digital geographic data file.

11. The method of claim 1, wherein the target profile is determined at least in part via user input received from a user interface in association with the working operation.

12. The method of claim 1, comprising, upon determining the initial position and the target profile, generating output signals to a display unit for generating indicia guiding manual control of the work implement with respect to the target profile, wherein automatic control of the current position of the point of interest is enabled when the current position of the point of interest is within a defined proximity with respect to the target profile.

13. A work machine comprising:a machine frame;a plurality of ground-engaging units supporting the machine frame and driven to cause the work machine to travel across a ground surface;a work implement supported by and moveable relative to the machine frame and configured to controllably work the ground surface; andone or more processors configured to:determine an initial position in a three dimensional coordinate system for a point of interest associated with the work implement;determine a target profile associated with the ground surface within a work area and in the three dimensional coordinate system; andduring an operating mode corresponding to a working operation and involving travel of the work machine via a plurality of headings across the work area, to:continuously monitor a current heading and a current position in the three dimensional coordinate system for the point of interest relative to the initial position; andgenerate control signals to at least one actuator for automatically controlling the current position of the point of interest relative to a corresponding position of the target profile within the three dimensional coordinate system.

14. The work machine of claim 13, wherein respective positions and movement of the point of interest are determined via at least signals from a remote source to a receiver associated with the work implement.

15. The work machine of claim 14, wherein respective positions and movement are determined for each of a first point of interest and a second point of interest associated with the work implement, wherein a cutting edge vector is defined in association with the first and second points of interest, wherein a current position and orientation of the cutting edge vector is controlled relative to the target profile.

16. The work machine of claim 15, wherein the respective positions and movement for the first point of interest are determined via at least signals received by a first receiver associated with the work implement and the respective positions and movement for the second point of interest are determined via at least signals received by a second receiver associated with the work implement.

17. The work machine of claim 15, wherein the respective positions and movement for the first point of interest are determined via at least signals received by the receiver associated with the work implement and the respective positions and movement for the second point of interest are determined via at least signals from an inertial measurement sensor associated with the work implement.

18. The work machine of claim 13, wherein respective positions and movement of the point of interest are determined via signals from a remote source to a receiver associated with the machine frame of the work machine and signals from at least an inertial measurement sensor associated with the work implement, wherein a current position of the point of interest relative to the machine frame is determined in a first three dimensional coordinate system associated with the work machine and converted to a current position of the point of interest in a second three dimensional coordinate system associated with the target profile.

19. The work machine of claim 18, wherein respective positions and movement are determined for each of a first point of interest and a second point of interest associated with the work implement, wherein a cutting edge vector is defined in association with the first and second points of interest, and wherein a current position and orientation of the cutting edge vector is controlled relative to the target profile.

20. The work machine of claim 13, wherein the target profile is determined at least in part via user input received from a user interface in association with the working operation.

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