阅读说明：本技术 自走式作业车辆和用于考虑底盘运动的铲刀稳定的控制方法 (Self-propelled working vehicle and control method for blade stabilization taking into account chassis movement ) 是由 托德·F·维尔德 丹尼尔·M·卡森 于 2021-04-30 设计创作，主要内容包括：本文公开了用于相对于作业车辆控制作业器具(例如,前置铲刀)以在地表面中产生期望轮廓的系统和方法。安装在底盘上的一个或多个传感器检测底盘相对于地面的实际俯仰速度和实际俯仰角度。另外的一个或多个传感器检测铲刀相对于底盘的实际升降位置。例如通过自动平地控制系统,通过手动启动的一个或多个触发器,和/或通过检测值的基于时间的侧倾平均值来确定待由铲刀产生的关于地表面的期望轮廓。根据实际俯仰速度、底盘相对于地面的实际俯仰角度以及作业器具相对于底盘的实际升降位置中的每一者,自动控制所述器具的与关于地表面的期望轮廓相对应的位置。(Systems and methods for controlling a work implement (e.g., a front blade) relative to a work vehicle to produce a desired contour in a ground surface are disclosed herein. One or more sensors mounted on the chassis detect the actual pitch velocity and actual pitch angle of the chassis relative to the ground. The other sensor or sensors detect the actual elevation position of the blade relative to the chassis. The desired profile about the ground surface to be generated by the blade is determined, for example, by an automatic grading control system, by one or more triggers that are manually activated, and/or by a time-based roll average of the sensed values. Automatically controlling a position of the implement corresponding to a desired profile about the ground surface as a function of each of the actual pitch rate, the actual pitch angle of the chassis relative to the ground, and the actual lift position of the work implement relative to the chassis.)

1. A method (300) of controlling a blade (142) relative to a chassis (140) of a self-propelled work vehicle (100) to produce a desired profile in a ground surface, the method comprising:

detecting, by a first set of one or more chassis-mounted sensors (142), an actual pitch velocity of the chassis and an actual pitch angle of the chassis relative to the ground;

detecting an actual raised and lowered position of the blade relative to the chassis by a second set of one or more sensors (162);

determining a desired profile about the ground surface to be produced by the blade; and

automatically controlling a position of the blade corresponding to the desired profile about the ground surface as a function of each of the actual pitch rate of the chassis, the actual pitch angle of the chassis relative to the ground, and the actual lift position of the work implement relative to the chassis.

2. The method of claim 1, wherein the step of determining a desired profile about the ground surface to be produced by the blade comprises:

setting a first target value corresponding to a pitch angle of the chassis relative to the ground, an

Setting a second target value corresponding to a lifting position of the blade with respect to the chassis.

3. The method of claim 2, further comprising:

determining an error value corresponding to at least a difference between the detected actual pitch angle, the actual heave position and the respective first and second target values, and

further automatically controlling the position of the blade based on the determined error value.

4. The method of claim 3, further comprising displaying indicia on a display unit (166) associated with an operator of the work vehicle, the indicia corresponding to one or more of the determined error values.

5. The method of any of claims 2 to 4, wherein the first and second target values are set to correspond to inputs received from a user through a user interface engaged with an automatic level ground control system.

6. The method of claim 5, wherein the step of determining a desired profile about the ground surface to be produced by the blade further comprises:

dynamically setting a third target value corresponding to a pitch rate of the chassis.

7. The method of any of claims 2 to 4, further comprising:

selectively enabling a first mode of operation in which at least the lift position is controlled based on a control signal responsive to a manually input command,

setting the first and second target values to correspond to respective actual values detected for a pitch angle of the chassis relative to the ground and the raised and lowered position of the blade relative to the chassis when the first mode of operation is ended upon termination of the manual input command, and

initiating a second mode of operation to automatically control a position of the blade corresponding to the desired profile about the ground surface as a function of each of an actual pitch rate of the chassis, an actual pitch angle of the chassis relative to the ground, and an actual lift position of the work implement relative to the chassis.

8. The method of any of claims 2 to 4, wherein actual values detected for the elevation angle of the chassis relative to the ground and the elevation position of the blade relative to the chassis are provided as inputs to a filtering stage, wherein the first and second target values are dynamically set to correspond to respective outputs from the filtering stage.

9. The method of any of claims 1-8, further comprising displaying indicia on a display unit (166) associated with an operator of the work vehicle, the indicia corresponding to one or more of:

an actual pitch velocity of the chassis;

an actual pitch angle of the chassis relative to the ground;

an actual raised and lowered position of the work implement relative to the chassis;

a desired profile for the ground surface; and

a control signal associated with a controlled position of the blade.

10. The method of claim 1, wherein the step of determining a desired profile about the ground surface to be produced by the blade comprises: setting one or more target values corresponding to the respective characteristic at each of the one or more locations associated with the blade.

11. The method of claim 10, further comprising:

generating a predicted value for the respective characteristic at each of the one or more locations as a function of at least each of an actual pitch velocity of the chassis, an actual pitch angle of the chassis relative to the ground, and an actual lift position of the work implement relative to the chassis.

12. The method of claim 11, further comprising:

determining an error value corresponding to at least a calculated difference between the predicted value and the target value of the respective characteristic.

13. The method of claim 12, further comprising:

further automatically controlling the position of the blade based on the determined error value.

14. The method of any of claims 12 or 13, further comprising:

displaying a marker on a display unit (166) associated with an operator of the work vehicle, the marker corresponding to one or more determined error values.

15. A self-propelled work vehicle (100) comprising:

a chassis (140), the chassis (140) being supported by a plurality of ground engaging units (116, 118);

a blade (142), the blade (142) being connected to a front portion of the chassis in a working direction by a positioning unit (200), the positioning unit (200) being configured to at least raise or lower the blade relative to the chassis;

a first set of one or more sensors (144), the first set of one or more sensors (144) being fixed relative to the chassis, and the first set of one or more sensors (144) being configured to generate output signals corresponding to an actual pitch velocity of the chassis and an actual pitch angle of the chassis relative to the ground;

a second set of one or more sensors (162), the second set of one or more sensors (162) connected to the positioning unit and the second set of one or more sensors (162) configured to generate output signals corresponding to an actual elevation position of the blade relative to the chassis; and

a controller (138), the controller (138) being functionally linked to the first set of sensors, the second set of sensors and the positioning unit, and the controller (138) being further configured for performing the steps of the method according to any of the claims 1 to 14.

Technical Field

The present disclosure relates generally to self-propelled vehicles, such as work machines in the construction and/or agricultural industries, that include a front-mounted implement for working on terrain. More particularly, the present disclosure relates to systems and methods configured to control the position of a front-mounted work implement to counteract movement of a vehicle chassis.

Background

Work vehicles discussed herein may include, for example, dozers, compact track loaders, excavation machinery, skid steer loaders, and other self-propelled machines that modify the terrain or equivalent work environment in some manner. Work vehicles having ground engaging blades may be used to shape and level ground surfaces. The undercarriage of such work vehicles may be supported from the ground surface by wheeled or tracked ground engaging units, which may encounter high and low points on the ground as the work vehicle moves, further causing the work vehicle to pitch forward (downward) or backward (upward). This pitch may be transferred to the ground engaging blade, causing the ground engaging blade to move up and down relative to the ground, which may move the blade away from the designated or desired level ground or plane. This effect may be magnified for work vehicles having ground-engaging blades in front of the tires or tracks of the work vehicle, as the work vehicle may pitch forward or backward when encountering vertical changes due to early work vehicle pitching caused by the ground-engaging blades. If the operator is unable to correct this effect, an undesirable (e.g., "washboard" type) contour may form on the floor surface, or the creation of a smooth or flat surface may be inhibited on the floor surface.

Conventional systems for controlling the position of a ground-engaging blade are known, but typically rely at least in part on sensors disposed on the blade itself to provide inputs for developing a control logic system. This arrangement may damage the sensor and may further provide a control loop that inherently reacts to changes in the position of the blade. It would be desirable to implement an improved control system that relies on sensors in a safer environment and is also inherently proactive or predictive in the undesirable changes in blade position that may occur during normal operation.

Disclosure of Invention

The present disclosure provides enhancements to conventional systems, at least in part, by introducing a novel arrangement of sensors and control logic systems to enhance operator lift commands and improve stability of the work vehicle when level ground.

In certain illustrative embodiments disclosed herein, a method for controlling a blade relative to a chassis of a self-propelled work vehicle to create a desired contour in a ground surface is disclosed. A first set of one or more chassis-mounted sensors is implemented to detect an actual pitch velocity of the chassis and an actual pitch angle of the chassis relative to the ground, and a second set of one or more sensors is implemented to detect an actual elevation position of the blade relative to the chassis. A desired profile about the ground surface to be produced by the blade is determined, and a position of the blade corresponding to the desired profile about the ground surface is automatically controlled as a function of each of an actual pitch speed of the chassis, an actual pitch angle of the chassis relative to the ground, and an actual lift position of the work implement relative to the chassis.

In one exemplary aspect of the above embodiment, the step of determining the desired profile about the ground surface to be produced by the blade may be carried out by setting a first target value corresponding to a pitch angle of the chassis relative to the ground, and setting a second target value corresponding to a heave position of the blade relative to the chassis.

In another exemplary aspect of the above embodiment, error values may be determined that are relatively unique to at least the differences between the detected actual pitch angle, actual heave position, and the respective first and second target values. The position of the blade may be further automatically controlled based on the determined error value.

In another exemplary aspect of the above embodiment, indicia may be displayed on a display unit associated with an operator of the work vehicle, the indicia corresponding to one or more of the determined error values.

In another exemplary aspect of the above embodiment and aspects discussed in connection therewith, the first target value and the second target value may be set to correspond to input received from a user through a user interface engaged with the automatic level controlling system.

In particular, in embodiments in which an automatic grading control system is implemented, the step of determining a desired profile about the ground surface to be produced by the blade may further comprise: a third target value corresponding to the pitch rate of the chassis is dynamically set.

In another exemplary aspect of the above embodiment and aspects discussed in connection therewith, a first mode of operation in which at least the elevation position is controlled based on a control signal responsive to a manually input command may be selectively initiated, for example, in the absence of an automatic grading control system. Upon termination of the first mode of operation upon termination of the manual input command, the first and second target values may be set to correspond to respective actual values detected for the pitch angle of the chassis relative to the ground and the heave position of the blade relative to the chassis, and the second mode of operation may be initiated to automatically control the position of the blade corresponding to the desired profile about the ground surface in dependence on the actual pitch velocity of the chassis, the actual pitch angle of the chassis relative to the ground, and the actual heave position of the work implement relative to the chassis.

In another exemplary aspect of the above embodiment and the discussion related thereto, again, for example in the absence of an automatic grading control system, actual values detected for the elevation angle of the chassis relative to the ground and the elevation position of the blade relative to the chassis are provided as inputs to a filtering stage, wherein the first and second target values are dynamically set to correspond to respective outputs from the low pass filtering stage. Low pass filters may typically be used in the filtering stage, including for example but not explicitly limited to moving average filters.

In another exemplary aspect of the above embodiment, indicia may be displayed on a display unit associated with an operator of the work vehicle, the indicia corresponding to one or more of: the actual pitch velocity of the chassis; actual pitch angle of the chassis relative to the ground; an actual elevation position of the work implement relative to the chassis; a desired profile for the ground surface; and a control signal associated with the controlled position of the blade.

In another exemplary aspect of the above embodiment, the step of determining a desired profile about the ground surface to be produced by the blade includes: one or more target values corresponding to the respective characteristic at each of the one or more locations associated with the blade are set.

In another exemplary aspect of the above embodiment, particularly with respect to the immediately preceding aspect, a predicted value may be generated for the respective characteristic at each of the one or more positions as a function of at least each of an actual pitch velocity of the chassis, an actual pitch angle of the chassis relative to the ground, and an actual lift position of the work implement relative to the chassis.

In another exemplary aspect of the above embodiment, particularly with respect to the immediately preceding aspect, an error value corresponding to at least a calculated difference between the predicted value and the target value of the respective characteristic may be determined.

In another exemplary aspect of the above embodiment, particularly with respect to the immediately preceding aspect, the position of the blade may be further automatically controlled in accordance with the determined error value.

In another exemplary aspect of the above embodiment, particularly with respect to the immediately preceding two aspects, a marker may be displayed on a display unit associated with an operator of the work vehicle, the marker corresponding to one or more determined error values.

In another embodiment disclosed herein, a self-propelled work vehicle is provided with a chassis supported by a plurality of ground engaging units and a blade connected to a front portion of the chassis in a work direction by a positioning unit configured to at least raise or lower a work implement relative to the chassis. The first set of one or more sensors is fixed relative to the chassis and is configured to generate output signals corresponding to an actual pitch velocity of the chassis and an actual pitch angle of the chassis relative to the ground. The second set of one or more sensors is connected to the positioning unit and configured to generate an output signal corresponding to an actual elevation position of the blade relative to the chassis. The controller is functionally linked to the first set of sensors, the second set of sensors and the positioning unit and is further configured in association therewith for performing steps in accordance with the above-described methods and exemplary aspects.

In other alternative embodiments, the various steps may be performed in part by implementing a remote computing device and communication network that are functionally linked to the autonomous work vehicle. The remote computing device may include a server system and/or a mobile computing device (e.g., a phone or tablet computer) carried by an operator of the autonomous work vehicle.

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

Drawings

Fig. 1 is a perspective view of a tracked work vehicle incorporating embodiments of the self-propelled work vehicle and methods disclosed herein.

FIG. 2 is a block diagram of an exemplary blade positioning unit according to an embodiment of the tracked work vehicle of FIG. 1.

Fig. 3 is a side view of the track type work vehicle of fig. 1 engaging an obstacle on the ground.

Fig. 4 is a block diagram representing an exemplary control system and method of operation of a self-propelled work vehicle as disclosed herein.

Detailed Description

Referring now to fig. 1-4, various embodiments of a work vehicle and method of operation may now be described. In general, the following embodiments may utilize various sensor inputs to, for example, enhance operator lift commands to a work implement such as a ground engaging blade to improve stability of grading operations by counteracting uncontrolled motion in a work vehicle chassis with controlled blade positioning.

Stated otherwise, whereas work vehicle chassis may undergo regular position changes during operation, for reasons described further below, and further wherein these position changes cannot be prevented or satisfactorily corrected by adjusting the ground engaging units supporting the chassis, the present disclosure provides supplemental and non-conventional adjustments in the case of ground engaging blade positions, which effectively control grading operations at the point of impact.

Fig. 1 is a perspective view of work vehicle 100. In the illustrated embodiment, work vehicle 100 is a track type dozer, but may be any work vehicle having a ground engaging blade 142 or work implement 142, such as a compact track loader, a motor grader, a power shovel, a skid steer unit, and a tractor, to name a few. The work vehicle may be operated to engage the ground and level, cut, and/or move material to achieve simple or complex characteristics on the ground. In operation, the work vehicle may experience movement in three directions and rotation in three directions. The direction of the work vehicle may also be referred to in terms of a longitudinal direction 102, a latitudinal or transverse direction 106, and a vertical direction 110. The rotation of work vehicle 100 may be referred to as roll 104 or roll direction, pitch 108 or pitch direction, and roll 112 or roll direction or heading direction.

The cab 136 may be located on a chassis 140. Both the cab and the work implement 142 may be mounted on the chassis such that the cab faces in the direction of operation of the work implement. A control station including a user interface (not shown) may be located in the cab. As used herein, the direction about work vehicle 100 may be defined from the perspective of an operator sitting within the cab: the left side of the work vehicle refers to the left side of the operator, the right side of the work vehicle refers to the right side of the operator, the front or front of the work vehicle refers to the direction in which the operator is facing, the rear or rear of the work vehicle is behind the operator, the top of the work vehicle is above the operator, and the bottom of the work vehicle is below the operator.

The term "user interface" as used herein may broadly take the form of the display unit 166 and/or other output devices from the system, such as indicator lights, audible alarms, and the like. The user interface may further or alternatively include various controls or user input devices (e.g., steering wheel, joysticks, levers, buttons) for operating the work vehicle 100, including operation of engines, hydraulic cylinders, and the like. Such an onboard user interface may be connected to the vehicle control system by means of, for example, a CAN bus arrangement or other equivalent forms of electrical and/or electromechanical signal transmission. Another form of user interface (not shown) may take the form of a display generated on a remote (i.e., off-board) computing device that can display output (such as status indications) and/or otherwise enable user interaction (such as providing input to the system). In the case of a remote user interface, for example, data transmission between the vehicle control system and the user interface may take the form of a wireless communication system and associated components as is conventionally known in the art.

The illustrated work vehicle 100 also includes a control system that includes a controller 138. The controller may be part of a machine control system of the work machine, or may be a separate control module. Thus, the controller may generate control signals for controlling the operation of various actuators throughout the work vehicle 100, such as hydraulic motors, hydraulic piston-cylinder units, electric actuators, and the like. The electronic control signals from the controller may be received, for example, by electro-hydraulic control valves associated with the respective actuators, wherein the electro-hydraulic control valves control the flow of hydraulic fluid to and from the respective hydraulic actuators in response to the control signals from the controller to control actuation of the respective hydraulic actuators.

The controller 138 may include or be functionally linked to a user interface and optionally mounted at a control panel in the cab 136.

Controller 138 is configured to receive input signals from some or all of the various sensors associated with work vehicle 100, which in this disclosure include at least: a first set of one or more sensors 144 fixed to the chassis 140 of the work vehicle 100 and configured to provide signals indicative of the motion and direction of the chassis, and a second set of one or more sensors 162 associated with the blade positioning unit 200 and configured to provide at least signals indicative of the blade elevation position. In alternative embodiments, the first sensor 144 may not be directly fixed to the chassis, but may be connected to the chassis through an intermediate component or structure (e.g., a rubberized base). In these alternative embodiments, the sensor 144 is not directly fixed to the chassis, but is still connected to the chassis at a fixed relative position so as to undergo the same motion as the chassis.

The sensor 144 is configured to provide a signal indicative of the inclination of the chassis 140 with respect to the direction of gravity, an angular measurement along the pitch direction 108. This signal may be referred to as the chassis pitch angle signal. The sensor 144 may also be configured to provide one or more signals indicative of other positions or velocities of the chassis, including its angular position, velocity, or acceleration in directions such as roll 104, pitch 108, roll 112, or including its linear acceleration in the longitudinal 102, latitudinal 106, and/or vertical 110 directions. The sensor 144 may be configured to directly measure inclination, measure angular velocity and integrate to obtain inclination, or measure inclination and derive to obtain angular velocity.

For example, the sensor 144 may generally consist of an Inertial Measurement Unit (IMU) mounted on the chassis and configured to provide at least a chassis pitch angle signal and an angular velocity signal to the controller 138 as inputs for a control method as further disclosed below. Such an IMU may for example be in the form of a three-axis gyroscope unit configured to detect changes in orientation of the sensor relative to its initial orientation, and thereby detect changes in orientation of the main frame to which the sensor is fixed. In other embodiments, the one or more sensors may include a plurality of GPS sensing units fixed relative to the chassis and/or blade positioning unit that may detect absolute positions and orientations of the work vehicle within an external reference frame and may detect changes in such positions and orientations, and/or a camera-based system that may observe surrounding structural characteristics through image processing and may respond to the orientation of the work machine relative to those surrounding structural characteristics.

The controller 138 in an embodiment (not shown) may include or may be associated with a processor, a computer-readable medium, a communication unit, a data store such as a database network, and the user interface or control panel described above with the display 166. Input/output devices such as a keyboard, joystick or other user interface means may be provided so that an operator may input commands to the controller. It should be understood that the controller described herein may be a single controller having all of the described functionality, or it may comprise multiple controllers in which the described functionality is distributed.

The various operations, steps or algorithms described in connection with the controller 138 may be embodied directly in hardware, in a computer program product (e.g., a software module executed by a processor), or in a combination of the two. The computer program product may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, or any other form of computer-readable medium known in the art. An exemplary computer readable medium can be connected to the processor such that the processor can read information from, and write information to, the memory/storage medium. In the alternative, the medium may be integral to the processor. The processor and the medium may reside in an Application Specific Integrated Circuit (ASIC). The ASIC may reside in a user terminal. In the alternative, the processor and the medium may reside as discrete components in a user terminal.

The term "processor" as used herein may refer to at least general or special purpose processing devices and/or logic systems, including, but not limited to, microprocessors, microcontrollers, state machines, etc., as will be appreciated by those skilled in the art. A processor may 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.

The communication unit may support or provide communication between controller 138 and external systems or devices, and/or support or provide a communication interface with internal components of work vehicle 100. The communication unit may include wireless communication system components (e.g., via a cellular modem, WiFi, bluetooth, etc.) and/or may include one or more wired communication terminals (e.g., universal serial bus ports).

Unless otherwise specified, the data stores discussed herein may generally include hardware, such as volatile or non-volatile storage, drives, memory, or other storage media, as well as one or more databases residing on the hardware.

Work vehicle 100 is supported on the ground by undercarriage 114. Undercarriage 114 includes ground engaging units 116, 118, which in this example are formed by left track 116 and right track 118 and provide traction for work vehicle 100. Each track may include: a link plate with a track tooth submerged in the ground to increase traction; and interconnecting members that allow the track to rotate about front idler 120, track roller 122, rear sprocket 124, and top idler 126. Such interconnecting components may include links, pins, bushings, and guides, to name a few. Front idler wheels 120, track rollers 122, and rear sprockets 124 on the left and right sides of work vehicle 100 provide support for work vehicle 100 on the ground. Front idler 120, track roller 122, rear sprocket 124, and top idler 126 are all pivotally connected to the rest of work vehicle 100 and rotatably connected to their respective tracks for rotation with those tracks. The track frame 128 provides structural support or strength to these components and to the rest of the undercarriage 114. In an alternative embodiment, the ground engaging units 116, 118 may include wheels, for example, on the left and right sides of the work vehicle.

Front idler 120 is located longitudinally forward of left track 116 and right track 118 and provides a rotating surface for the tracks to rotate about and a support point to transmit forces between work vehicle 100 and the ground. As the left and right tracks transition between a vertically lower portion and a vertically upper portion parallel to the ground, the left and right tracks rotate about the front idler wheels, and thus, approximately half of the outer diameter of each front idler wheel engages the respective left or right track. This engagement may be through a sprocket and pin arrangement, where pins contained in the left and right tracks engage through recesses on the front idler to transmit force. This engagement also results in the vertical height of the left and right tracks being only slightly greater than the outer diameter of each front idler at the longitudinally forward portion of the tracks. The forward engagement point 130 of the tracks may be approximated as a point on each track that is vertically below the center of the front idler, which is the forward point at which the track engages the ground. When a work vehicle travels in a forward direction and encounters a ground characteristic, the left and right tracks may first encounter the ground characteristic at the forward engagement point. If the elevation of the ground characteristic is higher than the elevation of the surrounding ground (i.e., an upward ground characteristic), the work vehicle may begin to pitch backwards (which may also be referred to as pitching upwards) when the forward engagement point reaches the ground characteristic. If the elevation of the ground characteristic is lower than the elevation of the surrounding ground (i.e., the downward ground characteristic), the work vehicle may continue to travel forward without pitching until the center of gravity of the work vehicle is vertically above the edge of the downward ground characteristic. At this point, the work vehicle may pitch forward (which may also be referred to as pitching down) until the forward engagement point contacts the ground. In this embodiment, the front idler is not powered and is therefore freely driven by the left and right tracks. In alternative embodiments, the front idler may be powered, for example, by an electric or hydraulic motor, or may have a brake mechanism included that is configured to resist rotation and thereby slow the left and right tracks.

Track rollers 122 are located between front idler 120 and rear sprocket 124 in the longitudinal direction along the lower left and lower right sides of work vehicle 100. Each track roller may be rotationally connected to either the left track 116 or the right track 118 by engagement between an upper surface of the track and a lower surface of the track roller. This configuration may allow the track roller to provide support to the work vehicle, and may particularly allow force to be transmitted in a vertical direction between the work vehicle and the ground. This configuration also resists upward deflection of the left and right tracks as they traverse the upward ground feature having a longitudinal length less than the distance between the front idler and the rear sprocket.

Rear sprockets 124 can be positioned longitudinally rearward of each of the left and right tracks 116, 118 and, similar to the front idlers 120, provide a rotating surface for the tracks to rotate about and provide a point of support to transmit forces between the work vehicle 100 and the ground. When the left and right tracks transition between their vertically lower and upper portions parallel to the ground, the left and right tracks rotate about the rear sprockets, and thus, approximately half of the outer diameter of each rear sprocket engages the respective left or right track. This engagement may be through a sprocket and pin arrangement where pins contained in the left and right tracks are engaged by recesses in the rear sprocket to transmit force. This engagement also results in the vertical height of the track being only slightly greater than the outer diameter of each rear sprocket at the longitudinal back or rear of the respective track. The last engagement point 132 of the tracks may be approximately the point on each track that is vertically below the center of the rear sprocket, which is the last point where the tracks engage the ground. When the work vehicle encounters a ground characteristic while traveling in a reverse or rearward direction, the tracks may first encounter the ground characteristic at their respective last engagement points. If the elevation of the ground feature is higher than the elevation of the surrounding ground, the work vehicle may begin to pitch forward when the last joint reaches the ground feature. If the elevation of the ground feature is lower than the elevation of the surrounding ground, the work vehicle may continue to tilt rearward without tilting until the center of gravity of the work vehicle is vertically above the edge of the downward ground feature. At this point, the work vehicle may pitch backwards until the last joint contacts the ground.

In this embodiment, each rear sprocket 124 may be powered by a rotationally connected hydraulic motor to drive the left and right tracks 116, 118 to control propulsion and traction of the work vehicle 100. Each of the left and right hydraulic motors may receive pressurized hydraulic fluid from the hydrostatic pump, the flow direction and displacement of which control the rotational direction and rotational speed of the left and right hydraulic motors. Each hydrostatic pump may be driven by an engine 134 (or equivalent power source) of the work vehicle and may be controlled by an operator in a cab 136 to issue commands that may be received by a controller 138 and transmitted to the left and right hydrostatic pumps. In alternative embodiments, each rear sprocket may be driven by a rotationally connected electric motor or mechanical system that transmits power from the engine.

Top idler 126 is located above track roller 122 along the left and right sides of work vehicle 100 and between front idler 120 and rear sprocket 124 in the longitudinal direction. Similar to the track rollers, each top idler may be rotationally connected to either the left track 116 or the right track 118 by engagement between a lower surface of the track and an upper surface of the top idler. This configuration may allow the top idler to support the track over the longitudinal span between the front idler and the rear sprocket and prevent an upper portion of the track parallel to the ground between the front idler and the rear sprocket from deflecting downward.

Undercarriage 114 is secured to a chassis 140 of work vehicle 100 and provides support and traction for chassis 140. The chassis is a frame that provides structural support and rigidity to the work vehicle, allowing forces to be transmitted between the blade 142 and the left and right tracks 116, 118. In this embodiment, the chassis is a weldment consisting of a plurality of formed and joined together steel members, but in alternate embodiments it may be composed of any of a different number of materials or constructions.

Blade 142 is a work implement that can be engaged with the ground or material to, for example, move material from one location to another and create characteristics on the ground, including flat areas, flat terrain, hills, roads, or more complex shape characteristics. In this embodiment, the blade of work vehicle 100 may be referred to as a six-way blade, a six-way adjustable blade, or a power angle lean (PAT) blade. The blade may be hydraulically actuated to move vertically up or down (hereinafter, blade "heave"), roll left or right (hereinafter, blade "tilt"), and swing left or right (hereinafter, blade "ramp"). Alternative embodiments may utilize blades with fewer degrees of freedom for hydraulic control, such as a four-way blade that may not be skewed or actuated in the swing direction 112.

The blade 142 is movably connected to the chassis 140 of the work vehicle 100 by a linkage mechanism 146 that supports and actuates the blade and is configured to allow the blade to be raised and lowered (i.e., raised or lowered in the vertical direction 110) relative to the chassis. The linkage may include a plurality of structural members to transmit forces between the blade and the rest of the work vehicle, and may provide attachment points for hydraulic cylinders that may actuate the blade in the up-down, tilt, and tilt directions. As mentioned herein, and as further described below with respect to fig. 2, the "blade positioning unit" 200 may include, for example, linkages, hydraulic cylinders, and additional and/or equivalent structures associated with actuating the blade in the elevation, tilt, and tilt directions.

The link mechanism 146 includes a C-shaped frame 148, i.e., a structural member having a C-shape that opens toward the rear of the work vehicle 100, located rearward of the blade 142. Each rear end of the c-frame is pivotally connected to the chassis 140 of the work vehicle 100, for example by a pin-and-bush joint, allowing the front of the c-frame to be raised or lowered relative to the work vehicle about a pivotal connection at the rear of the c-frame. The front portion of the c-frame is located approximately at the lateral center of the work vehicle and is connected to the blade by a ball joint. This allows the blade to have three degrees of freedom in its orientation relative to the c-frame (heave-pitch-roll) while still transmitting the rearward force on the blade to the rest of the work vehicle.

As described above, a second set of one or more sensors 162 is provided, the second set of one or more sensors 162 being associated with the blade positioning unit 200. The blade 142 may be raised (i.e., raised or lowered) relative to the work vehicle 100 via actuation 150 of a lift cylinder, which lift cylinder 150 may raise and lower the c-frame 148. For each lift cylinder, the rod end is pivotally connected to the upwardly projecting clevis of the c-frame, while the head end is pivotally connected to the remainder of the work vehicle just below and forward of cab 136. The configuration of the linkage mechanism 146 and the positioning of the pivotal connections for the head and rod ends of the lift cylinder cause extension of the lift cylinder to lower the blade and retraction of the lift cylinder to raise the blade. In alternative embodiments, the blade may be raised or lowered by a different mechanism, or the lift cylinder may be configured differently, such as a configuration in which extension of the lift cylinder raises the blade and retraction of the lift cylinder lowers the blade. In a particular embodiment, at least one sensor of the second set of sensors 162 is preferably positioned in association with the lift cylinder, for example, to generate an output signal corresponding to extension of the lift cylinder.

Similar to the first set of sensors 144, the second set of sensors 162 may be configured to measure angular position (inclination or orientation), velocity or acceleration, or linear acceleration. Sensor 162 (or, in other words, another sensor of second set of sensors 162) may provide a blade inclination signal indicative of an angle of the blade relative to gravity. In an alternative embodiment, the sensor 162 (or in other words, another sensor of the second set of sensors 162) may be configured to: instead, the angle of the linkage 146, e.g., the angle between the linkage 146 and the chassis 140, is measured to determine the position of the blade. In other alternative embodiments, sensor 162 may be configured to measure the position of the blade by measuring a different angle, such as the angle between the linkage and the blade, or the linear displacement of a cylinder attached to the linkage or the blade.

The blade 142 may be tilted relative to the work vehicle 100 by actuation of the tilt cylinder 152, which may also be referred to as moving the blade in the roll direction 104. The rod end of the tilt cylinder is pivotally connected to the clevis on its back and left side above the ball joint between the blade and the c-frame, and the head end is pivotally connected to the upwardly projecting portion of the linkage 146. The positioning of the pivot connection to the head and rod ends of the tilt cylinder causes the extension of the tilt cylinder to tilt the blade to the left (or counterclockwise as viewed from the operator cab 136) and causes the retraction of the tilt cylinder to tilt the blade to the right (or clockwise as viewed from the operator cab 136). In alternative embodiments, the blade may be tilted by a different mechanism (e.g., an electric or hydraulic motor), or the tilt cylinder may be configured in a different manner, such as a configuration in which the tilt cylinder is mounted in a vertical direction and located on the left or right side of the blade, or a configuration having two tilt cylinders.

The blade 142 may be tilted relative to the work vehicle 100 by actuation of the tilt cylinder 154, which may also be referred to as moving the blade in the swing direction 112. For each tilt cylinder, the rod end is pivotally connected to the clevis of the blade and the head end is pivotally connected to the clevis of the c-frame 148. One of the tilt cylinders is located on the left side of the work vehicle and to the left of the ball joint between the blade and the c-frame, and the other of the tilt cylinders is located on the right side of the work vehicle and to the right of the ball joint between the blade and the c-frame. This positioning causes the extension of the left end of the diagonal cylinder and the retraction of the right end of the diagonal cylinder to diagonally move the blade to the right or swing the blade clockwise as viewed from above, and causes the retraction of the left end of the diagonal cylinder and the extension of the right end of the diagonal cylinder to diagonally move the blade to the left or swing the blade counterclockwise as viewed from above. In alternative embodiments, the blade may be canted by a different mechanism, or the canted cylinder may be configured differently.

Due to the geometry of the linkage mechanism 146 in this embodiment, the blade 142 is not raised or lowered on an ideal vertical line with respect to the work vehicle 100. Rather, as the blade is raised and lowered, a point on the blade will follow a curve. This means that the vertical component of blade speed is not exactly proportional to the linear speed at which the lift cylinder 150 is extended or retracted, and may vary even when the linear speed of the lift cylinder is constant. This also means that the lift cylinder has a mechanical advantage which varies depending on the position of the linkage. Given a kinematic model of the blade and linkage (e.g., a formula or table providing a relationship between the position and/or motion of the blade and portions of the linkage) and the state of the blade and linkage (e.g., a sensor that senses one or more positions, angles, or orientations of the blade or linkage, such as sensor 162), the controller 138 may compensate for this non-linearity, at least with respect to blade lift. If only specific kinematic relationships need to be of interest (e.g., only those that affect blade raising and lowering), or only limited compensation accuracy is required, an incomplete or simplified kinematic model may be used. The controller may utilize this compensated and desired speed, such as a command to raise the blade at a particular vertical speed, to issue a command that may achieve a flow rate into the lift cylinder, resulting in the blade being raised at the particular vertical speed regardless of the current position of the linkage. For example, the controller may issue a command to vary the flow rate into the lift cylinder to achieve a substantially constant vertical speed of the blade.

Similarly, due to the positioning of the tilt cylinder 152 and the tilt cylinder 154 and the configuration of their connections to the blade 142, the angular velocity and angle at which the blade is tilted is not exactly proportional to the linear velocity of the tilt cylinder and the tilt cylinder, respectively, and may vary even though the linear velocities of the tilt cylinder and the tilt cylinder, respectively, are constant. This also means that both the tilting cylinder and the tilting cylinder have a mechanical advantage which varies depending on the position of the blade. Much like the lift cylinders, given the kinematic model of the blade and linkage and the state of the blade and linkage, the controller can compensate for this nonlinearity based on at least the blade tilt and angle. If only specific kinematic relationships need to be of interest (e.g., only those that affect blade tilt and angle), or only limited compensation accuracy is required, an incomplete or simplified kinematic model may be used. The controller may utilize this compensated and desired angular velocity (e.g., a command to tilt or tilt the blade at a particular angular velocity) to issue a command that may change the flow rate into the tilt cylinder or tilt cylinder, thereby causing the blade to tilt or tilt at the particular angular velocity regardless of the current position of the blade or linkage.

In alternative embodiments, the blade may be connected to the rest of work vehicle 100 in a manner that tends to cause the blade lift velocity (in vertical direction 110), tilt angular velocity (in roll direction 104), or tilt angular velocity (in swing direction 112) to be proportional to the linear velocity of lift cylinder 150, tilt cylinder 152, or tilt cylinder 154, respectively. This may be achieved by the specific design of the linkage mechanism 146 and the positioning of the pivotal connections of the lift cylinder, tilt cylinder and tilt cylinder. In such alternative embodiments, the controller may not need to compensate for the non-linear response of the blade to the actuation of the lift, tilt, and tilt cylinders, or may reduce the need for compensation.

Each of the lift cylinder 150, tilt cylinder 152, and tilt cylinder 154 is a double acting hydraulic cylinder. One end of each cylinder may be referred to as a head end, and an end of each cylinder opposite the head end may be referred to as a rod end. Each of the head and rod ends may be fixedly connected to the other component or, as in this embodiment, pivotably connected to the other component, such as through a pin-bushing or pin-bearing coupling, to name just two pivotal connections. As double acting hydraulic cylinders, each cylinder may exert a force in either an extension or retraction direction. Directing pressurized hydraulic fluid into the head chamber of the cylinder will tend to exert a force in the extension direction, while directing pressurized hydraulic fluid into the rod chamber of the cylinder will tend to exert a force in the retraction direction. The head chamber and the rod chamber may both be located within the cylinder of the hydraulic cylinder and may both be part of a larger cavity separated by a movable piston connected to the rod of the hydraulic cylinder. The volume of each of the head and rod chambers varies with the movement of the piston, which in turn causes the extension or retraction of the hydraulic cylinder.

Fig. 2 is an illustrative schematic diagram of a blade positioning unit 200, the blade positioning unit 200 including, for example, hydraulic and electrical components for controlling the position of the blade 142. Each of the lift cylinder 150, tilt cylinder 152, and tilt cylinder 154 may be hydraulically connected to a hydraulic control valve 156, which hydraulic control valve 156 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 rotatably connected to the engine 134 and directs such fluid to the lift cylinders, tilt cylinders, and other hydraulic circuits or functions of the work vehicle. The hydraulic control valve may meter out such fluid or control the flow rate of hydraulic fluid to each hydraulic circuit to which it is connected. In an alternative embodiment, the hydraulic control valve may not meter out such fluid, but may only selectively provide a flow path to these functions, with metering being performed by another component (e.g., a variable displacement hydraulic pump) or not at all. The hydraulic control valve may meter out this fluid through a plurality of spool valves, the position of which controls the flow of hydraulic fluid and other hydraulic logic. The spool valve may be actuated by a solenoid, a pilot valve (e.g., pressurized hydraulic fluid acting on the spool valve), a pressure upstream or downstream of the spool valve, or some combination of these and other elements.

According to the embodiment shown in fig. 1, the spool valve of the hydraulic control valve 156 is switched by a pilot valve whose pressure is at least partially controlled by an electro-hydraulic pilot valve 160 in communication with the controller 138. The electrohydraulic pilot valve is located within an interior area of the work vehicle and receives pressurized hydraulic fluid from a hydraulic pressure source and selectively directs such fluid to a pilot line that is hydraulically connected to the hydraulic control valve. In this embodiment, the hydraulic control valve and the electro-hydraulic pilot valve are separate components, but in an alternative embodiment, 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 an alternative embodiment, a pressure reducing valve may be used to reduce the pressure of the pressurized hydraulic fluid provided by the hydraulic pump to a set pressure, such as 600 pounds per square inch, for use with an electrically powered hydraulic pilot valve. In the embodiment shown in fig. 2, each valve within the electrohydraulic pilot valve is depressurized from receiving hydraulic fluid through a solenoid actuated spool valve that exhausts the hydraulic fluid to a hydraulic storage tank. In this embodiment, the controller actuates each solenoid by sending a specific current (e.g., 600mA) to the solenoid. In this manner, the controller may actuate the blade 142 by issuing an electrical command signal to an electrohydraulic pilot valve that, in turn, provides a hydraulic signal (pilot signal) to a hydraulic control valve that switches spool valves to direct hydraulic flow from a hydraulic pump to actuate the lift cylinder 150, tilt cylinder 152, and tilt cylinder 154. In this embodiment, the controller communicates directly with the electro-hydraulic pilot valve via an electrical signal sent through the wiring harness and communicates indirectly with the hydraulic control valve through the electro-hydraulic pilot valve.

In alternative embodiments, the controller 138 may send commands to actuate the blade 142 in a number of different ways. As one example, the controller may communicate with the valve controller over 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 electro-hydraulic pilot valve 160 based on those messages. As another example, the controller may actuate the blade 142 by actuating an input device in the cab 136. For example, an operator may use a joystick to issue commands to actuate the blade, and the joystick may generate a hydraulic signal (pilot signal) that is communicated to the hydraulic control valve 156 to cause actuation of the blade. In such a configuration, the controller may be in communication with an electrical device (e.g., solenoid, motor) that may actuate a joystick in the cab. In this manner, the controller may actuate the blade by actuating these electrical devices, rather than transmitting a signal to the electrohydraulic pilot valve.

Fig. 3 is a left side view of work vehicle 100 as the work vehicle travels over ground characteristics 190, which ground characteristics 190 are, in this example, ground characteristics having a higher altitude than the surrounding ground (e.g., upward ground characteristics). When work vehicle 100 is traveling over a ground surface characteristic, forward engagement point 130 is the first point on left track 116 and right track 118 that is substantially engaged with the ground surface characteristic. When the work vehicle engages the ground characteristics at the forward engagement point, the work vehicle begins to pitch up or back as the front portion of the work vehicle rises in the ground characteristics relative to the rear portion of the work vehicle. When pitching up or back, the work vehicle will tend to pitch around the last joint 132. During this pitch process, chassis-mounted sensors 144 may send signals indicative of the angle of chassis 140 relative to the direction of gravity (i.e., the orientation in pitch direction 108) and signals indicative of the angular velocity of chassis 140 in pitch direction 108. These signals will indicate the pitch and speed of the tilt and pitch up in a first direction, as opposed to the pitch and speed of the tilt and pitch down in a second direction. In this embodiment, the signal from the sensor 144 to the controller 138 may indicate a range of values for which values in one half of the range indicate pitch angle and angular velocity in a first direction and values in the other half of the range indicate pitch angle and angular velocity in a second direction.

Similarly, the sensor 162 associated with the blade positioning unit 200 may send a blade tilt signal indicative of the tilt angle of the blade 142 relative to the direction of gravity (i.e., the orientation in the tilt direction 108) and a blade tilt signal indicative of the angular velocity of the blade 142 in the tilt direction 108. These signals will indicate the pitch and speed of the tilt and pitch up in a first direction, as opposed to the pitch and speed of the tilt and pitch down in a second direction. In this embodiment, the blade tilt signal and the blade pitch signal from the sensor 162 to the controller 138 may indicate values in a range for which values in one half of the range indicate pitch angle and angular velocity in a first direction and values in the other half of the range indicate pitch angle and angular velocity in a second direction.

As work vehicle 100 continues to travel on ground surface characteristic 190, forward engagement point 130 will cease to engage the ground surface and, instead, will overhang the ground surface by a distance determined in part by the height of the ground surface characteristic relative to the surrounding ground surface and the position of the work vehicle on the ground surface characteristic. At this point, although the ground characteristic is an upward ground characteristic, it has the effect of a downward ground characteristic at a lower altitude than the surrounding ground. Specifically, the area just behind the ground characteristic is below the ground characteristic. When the center of gravity of the work vehicle crosses the top of the ground feature, the work vehicle will pitch forward and eventually the engagement point will leave the ground, while the forward engagement point will drop until it comes into contact with the ground.

During travel of work vehicle 100 on ground characteristics 190, blade 142 will rise and fall relative to the ground due to the pitch of the work vehicle. When the work vehicle pitches backwards, the blade will rise as the c-frame 148 pitches backwards with the work vehicle, and when the work vehicle tilts forwards, the blade will fall as the c-frame pitches forwards with the work vehicle. If the operator of the work vehicle is unable to correct the ground characteristics by commanding the blade to raise or lower in a manner that counteracts the effect of the ground characteristics on the blade height, the work vehicle will produce vertical variations on the ground, such as hills and valleys, without producing a smooth surface. When the work vehicle is traveling over this newly created hill and valley, the blade will again rise and fall as the work vehicle pitches backwards and forwards, creating further vertical changes. This series of hills and valleys may be referred to as a "washboard" pattern. In addition to creating this pattern, the pitch of the work vehicle will also interrupt efforts to remain uniformly flat. The operator of the work vehicle may target a particular level ground (e.g., 2%) and if traveling up and down the level ground, the pitch of the work vehicle will create a portion that is actually level ground steeper or shallower than the target level ground.

An exemplary embodiment of a method 300 for controlling the blade 142 relative to the chassis of the self-propelled work vehicle 100 to produce a desired profile on the ground may now be described by further illustrative reference to fig. 4.

A first exemplary step 310 of the method includes sensing an actual pitch velocity of the chassis and an actual pitch angle of the chassis relative to the ground via a first set of one or more chassis-mounted sensors 144, and further sensing an actual elevation position of the blade relative to the chassis via a second set of one or more sensors 162.

In a second exemplary step 320 of the method, information is provided to the controller 138 that corresponds to a desired profile about the ground surface to be produced by the blade. The controller determines the desired profile to be produced in a third exemplary step 330, wherein an output signal may be provided to automatically control the position of the blade in a fourth exemplary step 340. In a preferred embodiment, the output signal is a hoist command calculated for the blade positioning system 200, the hoist command consisting of three specific items. The first term is a function of pitch rate error relative to a target pitch rate, the second term is a function of pitch angle error relative to a target pitch angle, and the third term is a function of heave position error relative to a target heave position, each command term corresponding to a desired profile about the ground surface.

In an embodiment, the information corresponding to the desired profile about the ground surface to be produced by the blade may include a first target value set to correspond to a desired pitch angle of the chassis relative to the ground and a second target value set to correspond to a heave position of the blade relative to the chassis. In some embodiments, the third target value may further be set to correspond to a desired pitch angle rate of the chassis, particularly where an automatic grading control system is implemented as described further below, but in many cases the third target value may be implicitly characterized as zero. In the case where the above-described target values have been set, the controller may be configured to determine error values corresponding to at least differences between the detected actual pitch angle, the actual heave position and the respective first and second target values, and further automatically control the position of the blade in accordance with the determined error values.

According to this embodiment, a fifth step 350 of the method may include displaying indicia on a display unit 166 associated with the work vehicle (e.g., a display unit in cab 136) on a mobile computing device carried by an operator or other user or the like. The indicia may, for example, correspond to one or more determined error values (e.g., in absolute or relative form). Even in embodiments where the error value is not explicitly determined and thus displayable, additional or alternative indicia may be displayed including, for example, an actual (i.e., detected) pitch rate and/or target pitch rate of the chassis relative to the ground, an actual (i.e., detected) pitch angle and/or target pitch angle of the chassis relative to the ground, an actual (i.e., detected) heave position and/or target heave position of the blade relative to the chassis, one or more characteristics of a desired profile about the ground surface, a control signal associated with a controlled position of the blade, etc.

In one embodiment, information corresponding to a desired profile to be generated by the blade about the ground surface may be provided by or otherwise as part of the automatic grading control system. The system may include a user interface configured to enable an operator to input, select, or otherwise specify a desired grading profile (grade of the surface), where target values corresponding to blade control parameters may be automatically derived. The operator selection may take the form of a predetermined group setting, where the target value may be retrieved from memory at least initially, or the operator may select one or more baseline values, where the controller obtains or determines the control parameters corresponding to the baseline values. In some embodiments, the controller may be connected to receive an input signal corresponding to one or more characteristics of the surface of the non-level ground, wherein the one or more target values may be derived based at least in part on the input signal.

In an alternative embodiment, the information corresponding to the desired profile about the ground surface to be generated by the blade may be provided manually by the system user through, for example, a user interface configured therefor. The manual user input in such embodiments may generally include a first target value corresponding to a desired pitch angle of the chassis relative to the ground, and a second target value corresponding to a heave position of the blade relative to the chassis. The third target value corresponding to the desired pitch angle rate of the chassis may optionally also be set manually, but may be implicitly characterized as zero if not set manually.

In another alternative embodiment, the control system may be selectively operable in a first mode of operation in which at least the elevation position of the blade is controlled based on a control signal responsive to a manual input command, for example by a joystick or the like in the cab. At the end of the first mode of operation, which may occur automatically upon termination of the manual input command or upon receipt of a dedicated mode switch input signal, the first and second target values may be set to correspond to respective actual values detected for the pitch angle of the chassis relative to the ground and the elevation position of the blade relative to the chassis. At this point, a second mode of operation may be initiated to automatically control the position of the blade corresponding to the desired profile about the ground surface as a function of each of the actual pitch rate of the chassis, the actual pitch angle of the chassis relative to the ground, and the actual lift position of the work implement relative to the chassis. The initiation of the second mode of operation may be triggered automatically at the end of the first mode of operation, or may require a separate input signal from an operator or other source.

In another alternative embodiment, the actual values detected for the elevation angle of the chassis relative to the ground and the elevation position of the blade relative to the chassis are provided as inputs to a filter stage, wherein the first and second target values are dynamically set to correspond to respective outputs from the low pass filter stage. A low pass filter, which may typically be used in the filtering stage, includes, for example but by no means limited to, a moving average filter for smoothing fluctuations in the input time series data.

The control system and method 300 as disclosed herein may alternatively be configured to determine a desired profile about a ground surface to be produced by the blade from one or more target values corresponding to respective characteristics provided at each of one or more locations associated with the blade. While physical sensors according to the present disclosure are not located on the blade itself, or at least do not rely on input for actual measurements of control parameters, such embodiments may implement one or more virtual sensors 164 that are projected (projected) at respective locations associated with the blade.

For example, in steps 320 and 330, the controller may be configured to, based on the input signals received from the first set of sensors 144 and the second set of sensors 162 in step 310: a predicted value is generated for the respective characteristic at each of the one or more positions as a function of at least each of an actual pitch velocity of the chassis, an actual pitch angle of the chassis relative to the ground, and an actual lift position of the work vehicle relative to the chassis, and an error value corresponding to at least a calculated difference between the predicted value and a target value of the respective characteristic is further determined. In the event that an error value representing the difference between the target grade profile (i.e., the target location of the blade) and the actual grade profile (i.e., the measured or projected location of the blade) has been determined, the controller automatically controls the position of the blade in step 340 via control signals to the blade positioning unit 200 further based on the determined error value.

As used herein, the phrase "one or more" when used with a list of items means that a different combination of one or more of the items can be used, and only one of each item in the list may be required. For example, "one or more" of item a, item B, and item C can include, but are not limited to, for example, item a or item a and item B. The example can also include item a, item B, and item C, or item B and item C.

It will thus be seen that the apparatus and method of the present disclosure readily achieve the objects and advantages mentioned as well as those inherent therein. While certain preferred embodiments of the present disclosure have been illustrated and described for purposes of the present disclosure, 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 other disclosed feature or embodiment.