Self-propelled work vehicle and control method for blade stabilization taking chassis motion into account

Abstract

Systems and methods for controlling a work implement (e.g., a front-mounted blade) relative to a work vehicle to produce a desired profile in a ground surface are disclosed herein. One or more sensors mounted on a chassis detect an actual pitch speed and an actual pitch angle of the chassis relative to the ground. Another one or more sensors detect an actual lift position of the blade relative to the chassis. A desired profile with respect to the ground surface to be produced by the blade is determined, for example, by an automatic grading control system, by one or more triggers initiated manually, and / or by a time-based lateral average of detected values. A position of the work implement corresponding to the desired profile with respect to the ground surface is automatically controlled in accordance with each of the actual pitch speed, the actual pitch angle of the chassis relative to the ground, and the actual lift position of the work implement relative to the chassis.

Description

Technical Field

[0001] This disclosure generally relates to self-propelled vehicles, such as work machinery in the construction and / or agricultural industries, which include a front-mounted tool for working on terrain. More specifically, this disclosure relates to systems and methods configured to control the position of the front-mounted work tool to counteract movement of the vehicle chassis. Background Technology

[0002] The work vehicles discussed in this article may include, for example, bulldozers, compact track loaders, excavators, skid steer loaders, and other self-propelled machinery that modifies terrain or equivalent working environments in some way. Work vehicles with ground-joining blades can be used to shape and level ground surfaces. The underframe of such a work vehicle may be supported from the ground surface by a wheeled or tracked ground-joining unit. As the work vehicle moves, the ground-joining unit may encounter unevenness in the ground, further causing the work vehicle to pitch forward (downward) or backward (upward). This pitch can be transmitted to the ground-joining blade, causing the ground-joining blade to move up and down relative to the ground, which can move the blade away from a designated or desired flat or level surface. For work vehicles with ground-joining blades in front of the work vehicle's tires or tracks, this effect may be amplified because the work vehicle may pitch forward or backward when encountering vertical changes caused by the ground-joining blade due to the earlier pitch of the work vehicle. If the operator is unable to correct this effect, it may create undesirable (e.g., "washboard") contours on the ground surface, or it may inhibit the formation of smooth or flat surfaces on the ground.

[0003] Conventional systems for controlling the position of a ground engagement blade are known, but they typically rely, at least in part, on sensors mounted on the blade itself to provide input for developing the control logic system. This arrangement can expose the sensors to damage and may further introduce control loops that inherently react to changes in blade position. An improved control system is desired that relies on sensors in a safer environment and is inherently forward-looking or predictive of undesirable changes in blade position that may occur during normal operation. Summary of the Invention

[0004] This disclosure provides enhancements to conventional systems, at least in part, by introducing a novel arrangement of sensors and a control logic system to improve operator lifting commands and enhance the stability of work vehicles on level ground.

[0005] In certain illustrative embodiments disclosed herein, a method is disclosed for controlling a blade relative to the chassis of a self-propelled work vehicle to produce a desired profile on the ground surface. A first set of one or more sensors mounted on the chassis is implemented to detect the actual pitch speed of the chassis and the actual pitch angle of the chassis relative to the ground, and a second set of one or more sensors is implemented to detect the actual lifting position of the blade relative to the chassis. The desired profile to be produced by the blade with respect to the ground surface is determined, and the position of the blade corresponding to the desired profile with respect to the ground surface is automatically controlled based on each of the actual pitch speed of the chassis, the actual pitch angle of the chassis relative to the ground, and the actual lifting position of the work implement relative to the chassis.

[0006] In one exemplary aspect of the above embodiments, the step of determining the desired profile of the ground surface to be generated by the shovel can be implemented by setting a first target value corresponding to the pitch angle of the chassis relative to the ground and a second target value corresponding to the lifting position of the shovel relative to the chassis.

[0007] In another exemplary aspect of the above embodiments, an error value can be determined that corresponds at least to the difference between the detected actual pitch angle, the actual lifting position, and the corresponding first and second target values. The position of the blade can then be automatically controlled based on the determined error value.

[0008] In another exemplary aspect of the above embodiments, a mark corresponding to one or more determined error values ​​may be displayed on a display unit associated with the operator of the work vehicle.

[0009] In another exemplary aspect of the above embodiments and in the related discussion, the first target value and the second target value may be set to correspond to input received from the user through a user interface coupled with the automatic leveling control system.

[0010] In particular, in embodiments in which an automatic leveling control system is implemented, the step of determining the desired profile of the ground surface to be generated by the blade may further include: dynamically setting a third target value corresponding to the pitch speed of the chassis.

[0011] In another exemplary aspect of the above embodiments and in the related discussion, for example, in the absence of an automatic leveling control system, a first operating mode can be selectively activated, in which at least the lifting position is controlled based on a control signal in response to a manually input command. When the first operating mode ends upon termination of the manually input command, a first target value and a second target value can be set to correspond to the corresponding actual values ​​detected for the chassis pitch angle relative to the ground and the lifting position of the blade relative to the chassis. A second operating mode can be activated to automatically control the position of the blade corresponding to a desired profile of the ground surface based on the actual pitch speed of the chassis, the actual pitch angle of the chassis relative to the ground, and the actual lifting position of the work implement relative to the chassis.

[0012] In another exemplary aspect of the above embodiments and in the related discussion, again for example in the absence of an automatic leveling control system, the actual values ​​detected for the pitch angle of the chassis relative to the ground and the lifting position of the blade relative to the chassis are provided as inputs to the filtering stage, wherein a first target value and a second target value are dynamically set to correspond to the respective outputs from the low-pass filtering stage. Low-pass filters can typically be used in the filtering stage, including, for example, but not explicitly limited to, moving average filters.

[0013] In another exemplary aspect of the above embodiments, a mark may be displayed on a display unit associated with the operator of the work vehicle, the mark corresponding to one or more of the following: the actual pitch speed of the chassis; the actual pitch angle of the chassis relative to the ground; the actual lifting position of the work implement relative to the chassis; the desired profile of the ground surface; and a control signal associated with the controlled position of the blade.

[0014] In another exemplary aspect of the above embodiments, the step of determining the desired profile of the ground surface to be produced by the shovel includes: setting one or more target values ​​corresponding to a corresponding characteristic at each of one or more locations associated with the shovel.

[0015] In another exemplary aspect of the above embodiments, particularly with regard to the immediately preceding aspect, predicted values ​​can be generated for the corresponding characteristics at each of the one or more locations based on at least one of the chassis's actual pitch speed, the chassis's actual pitch angle relative to the ground, and the work implement's actual lifting position relative to the chassis.

[0016] In another exemplary aspect of the above embodiments, particularly with respect to the immediately preceding aspect, an error value can be determined that corresponds at least to the calculated difference between the predicted value and the target value of the corresponding characteristic.

[0017] In another exemplary aspect of the above embodiments, particularly with respect to the immediately preceding aspect, the position of the blade can be further automatically controlled based on the determined error value.

[0018] In another exemplary aspect of the above embodiments, particularly with respect to the two preceding aspects, a mark may be displayed on a display unit associated with the operator of the work vehicle, the mark corresponding to one or more determined error values.

[0019] In another embodiment disclosed herein, the self-propelled work vehicle includes a chassis and a blade supported by a plurality of ground engagement units. The blade is connected to the front of the chassis in the working direction via a positioning unit configured to at least raise or lower the work implement relative to the chassis. One or more sensors of a first group are fixed relative to the chassis and configured to generate output signals corresponding to the actual pitch speed of the chassis and the actual pitch angle of the chassis relative to the ground. One or more sensors of a second group are connected to the positioning unit and configured to generate output signals corresponding to the actual lifting position of the blade relative to the chassis. A controller is functionally linked to the sensors of the first group, the sensors of the second group, and the positioning unit, and is further configured thereto to perform the steps according to the methods and exemplary aspects described above.

[0020] In other alternative embodiments, the steps may be performed in part by implementing a remote computing device and communication network functionally linked to the self-propelled work vehicle. The remote computing device may include a server system and / or a mobile computing device (e.g., a telephone or tablet) carried by the operator of the self-propelled work vehicle.

[0021] Many objects, features, and advantages of the embodiments set forth herein will be apparent to those skilled in the art when the following disclosure is read in conjunction with the accompanying drawings. Attached Figure Description

[0022] Figure 1 This is a perspective view of a tracked work vehicle that incorporates embodiments of the self-propelled work vehicle and method disclosed herein.

[0023] Figure 2 It is based on Figure 1 A block diagram of an exemplary blade positioning unit in an embodiment of a tracked work vehicle.

[0024] Figure 3 yes Figure 1 A side view of a tracked work vehicle engaging with an obstacle on the ground.

[0025] Figure 4This is a block diagram illustrating an exemplary control system and operating method for a self-propelled work vehicle as disclosed herein. Detailed Implementation

[0026] Now for reference Figures 1 to 4 Various embodiments of the work vehicle and operating method can now be described. Generally, the following embodiments utilize various sensor inputs to, for example, enhance the operator's lifting commands to work implements such as ground-jointing blades, thereby improving the stability of leveling operations by using controlled blade positioning to counteract uncontrolled movement in the work vehicle chassis.

[0027] It is further noted that the chassis of the work vehicle may undergo regular positional changes during operation, for reasons further described below, and in addition, where adjusting the ground engagement unit supporting the chassis cannot prevent or satisfactorily correct these positional changes, this disclosure provides supplementary and unconventional adjustments in the case of the position of the ground engagement blade, which effectively controls level ground operation at the point of impact.

[0028] Figure 1 This is a perspective view of the work vehicle 100. In the illustrated embodiment, the work vehicle 100 is a tracked bulldozer, but can be any work vehicle with a ground engagement blade 142 or work implement 142, such as a compact tracked loader, automatic grader, bulldozer, skid-steer, and tractor, to name just a few. The work vehicle can be operated to engage the ground and level, cut, and / or move materials to achieve simple or complex characteristics on the ground. During operation, the work vehicle can experience movement in three directions and rotation in three directions. The orientation of the work vehicle can also be referred to as the longitudinal direction 102, the latitude or lateral direction 106, and the vertical direction 110. The rotation of the work vehicle 100 can be referred to as tilt 104 or tilt direction, pitch 108 or pitch direction, and yaw 112 or yaw direction or forward direction.

[0029] The cab 136 may be located on the chassis 140. Both the cab and the work implement 142 may be mounted on the chassis such that the cab faces the working direction of the work implement. A control station, including a user interface (not shown), may be located in the cab. As used herein, the orientation of the work vehicle 100 can be defined from the perspective of an operator seated in the cab: the left side of the work vehicle refers to the operator's left side, the right side of the work vehicle refers to the operator's right side, the front or front of the work vehicle refers to the direction 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.

[0030] As used herein, the term "user interface" can broadly take the form of display unit 166 and / or other output devices from the system, such as indicator lights, audible alarms, etc. The user interface may further or alternatively include various controls or user input devices (e.g., steering wheel, joystick, lever, buttons) for operating the work vehicle 100, including operation of the engine, hydraulic cylinders, etc. Such an onboard user interface can be connected to the vehicle control system via, for example, a CAN bus device or other equivalent forms of electrical signal transmission and / or electromechanical signal transmission. Another form of the user interface (not shown) can take the form of a display generated on a remote (i.e., offboard) computing device, which can display outputs (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, data transmission between, for example, the vehicle control system and the user interface can take the form of wireless communication systems and associated components as conventionally known in the art.

[0031] The illustrated work vehicle 100 also includes a control system comprising a controller 138. This controller may be part of the machine control system of the work machinery or may be a separate control module. Therefore, the controller can 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, etc. Electronic control signals from the controller may be received, for example, by an electro-hydraulic control valve associated with a corresponding actuator, wherein the electro-hydraulic control valve, in response to the control signals from the controller, controls the flow of hydraulic fluid to and from the corresponding hydraulic actuator to control actuation of that corresponding hydraulic actuator.

[0032] The controller 138 may include a user interface or be functionally linked to a user interface, and may optionally be mounted at a control panel in the cab 136.

[0033] The controller 138 is configured to receive input signals from some or all of a variety of sensors associated with the work vehicle 100. In this disclosure, these sensors include at least one or more sensors 144 of a first group fixed to the chassis 140 of the work vehicle 100 and configured to provide signals indicating the movement and orientation of the chassis; and one or more sensors 162 of a second group associated with the blade positioning unit 200 and configured to provide signals indicating at least the blade's lifting position. In alternative embodiments, the first sensor 144 may not be directly fixed to the chassis, but may be connected to the chassis via an intermediate component or structure (e.g., a rubber-coated base). In these alternative embodiments, the sensor 144 is not directly fixed to the chassis, but remains connected to a fixed relative position on the chassis to undergo the same movement as the chassis.

[0034] Sensor 144 is configured to provide a signal indicating the tilt of chassis 140 relative to the direction of gravity, measured at an angle along pitch direction 108. This signal may be referred to as a chassis pitch angle signal. Sensor 144 may also be configured to provide one or more signals indicating other positions or velocities of the chassis, including its angular position, velocity, or acceleration in directions such as roll 104, pitch 108, yaw 112, or linear acceleration in the longitudinal 102, latitude 106, and / or vertical 110. Sensor 144 may be configured to directly measure the tilt, measure the angular velocity and integrate to obtain the tilt, or measure the tilt and differentiate to obtain the angular velocity.

[0035] For example, sensor 144 may typically comprise an inertial measurement unit (IMU) mounted on the chassis and configured to provide at least chassis pitch and angular velocity signals to controller 138 as inputs for control methods further disclosed below. Such an IMU may be, for example, in the form of a three-axis gyroscope unit configured to detect directional changes of the sensor relative to its initial orientation, and thereby detect directional changes of the main frame to which the sensor is fixed. In other embodiments, the one or more sensors may comprise a plurality of GPS sensing units and / or a camera-based system fixed relative to the chassis and / or the blade positioning unit. The GPS sensing units can detect the absolute position and orientation of the working vehicle in an external reference frame and can detect changes in such position and orientation. The camera-based system can observe surrounding structural characteristics through image processing and can respond to the orientation of the working machinery relative to those surrounding structural characteristics.

[0036] The controller 138 in the embodiment (not shown) may include a processor, a computer-readable medium, a communication unit, a data storage device such as a database network, and the aforementioned user interface or control panel having a display 166, or may be associated with a processor, a computer-readable medium, a communication unit, a data storage device such as a database network, and the aforementioned user interface or control panel having a display 166. Input / output devices such as a keyboard, joystick, or other user interface tools may be provided so that an operator can input instructions to the controller. It should be understood that the controller described herein may be a single controller having all the described functions, or it may include multiple controllers, wherein the described functions are distributed among the multiple controllers.

[0037] The various operations, steps, or algorithms described in conjunction with controller 138 can be embodied directly in hardware, in a computer program product (e.g., a software module executed by a processor), or a combination of both. The computer program product can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, 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 so that the processor can read information from and write information to the memory / storage medium. Alternatively, the medium can be integrated with the processor. The processor and medium can reside in an application-specific integrated circuit (ASIC). The ASIC can reside in a user terminal. Alternatively, the processor and medium can reside as discrete components in the user terminal.

[0038] As used herein, the term "processor" can refer to at least general-purpose or special-purpose processing devices and / or logic systems, as will be understood by those skilled in the art, including but not limited to microprocessors, microcontrollers, state machines, etc. A processor can also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor), multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0039] The communication unit may support or provide communication between the controller 138 and external systems or devices, and / or support or provide a communication interface with the internal components of the 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., a Universal Serial Bus port).

[0040] Unless otherwise stated, the data storage discussed herein may generally include hardware such as volatile or non-volatile storage devices, drives, memory or other storage media, and one or more databases residing on that hardware.

[0041] The work vehicle 100 is supported on the ground by a chassis 114. The chassis 114 includes ground engagement units 116 and 118, which in this example are formed by the left track 116 and the right track 118 and provide traction for the work vehicle 100. Each track may include: a track plate with teeth that are recessed into the ground to increase traction; and interconnecting components that allow the track to rotate about a front idler sprocket 120, track track roller 122, rear sprocket 124, and top idler sprocket 126. Such interconnecting components may include links, pins, bushings, and guides, to name just a few. The front idler sprocket 120, track track roller 122, and rear sprocket 124 on the left and right sides of the work vehicle 100 provide support for the work vehicle 100 on the ground. The front idler 120, track track roller 122, rear sprocket 124, and top idler 126 are all pivotally connected to the remainder of the work vehicle 100 and rotatably connected to their respective tracks so as to rotate with those tracks. The track frame 128 provides structural support or strength for these components and the remainder of the underframe 114. In an alternative embodiment, ground engagement units 116, 118 may include, for example, wheels on the left and right sides of the work vehicle.

[0042] The front idler pulley 120 is located longitudinally at the front of the left track 116 and the right track 118, providing a rotational surface for the track to rotate around it and providing a support point to transmit force between the working vehicle 100 and the ground. As the left and right tracks transition between a vertical lower portion and a vertical upper portion parallel to the ground, the left and right tracks rotate around the front idler pulley, so that approximately half the outer diameter of each front idler pulley engages with the corresponding left or right track. This engagement can be achieved through a sprocket and pin configuration, where pins in the left and right tracks engage via recesses on the front idler pulleys 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 pulley at the longitudinal front of the track. The forward engagement point 130 of the track can be approximated as a point on each track located vertically below the center of the front idler pulley, which is the forward point where the track engages with the ground. When the working vehicle encounters a ground feature while traveling forward, the left and right tracks may first encounter the feature at the forward engagement point. If the elevation of the ground feature is higher than the elevation of the surrounding ground (i.e., an upward ground feature), the working vehicle may begin to pitch backward (also known as pitching upward) upon reaching the ground feature at the forward engagement point. If the elevation of the ground feature is lower than the elevation of the surrounding ground (i.e., a downward ground feature), the working vehicle can continue to travel forward without pitching until its center of gravity is above the edge of the downward ground feature in the vertical direction. At this point, the working vehicle can pitch forward (also known as pitching downward) until it contacts the ground at the forward engagement point. In this embodiment, the front idler wheel is not powered and is therefore freely driven by the left and right tracks. In an alternative embodiment, the front idler wheel may be powered, for example, by an electric motor or a hydraulic motor, or may have an included braking mechanism configured to resist rotation and thereby slow down the left and right tracks.

[0043] Track rollers 122 are located longitudinally between the front idler 120 and the rear sprocket 124 along the lower left and right sides of the working vehicle 100. Each track roller is rotatably connected to the left track 116 or the right track 118 via an engagement between the upper surface of the track and the lower surface of the track roller. This configuration allows the track rollers to provide support to the working vehicle and, in particular, allows for the vertical transmission of forces between the working vehicle and the ground. This configuration also resists upward deflection of the left and right tracks when their longitudinal length is less than the distance between the front idler 120 and the rear sprocket.

[0044] The rear sprocket 124 can be positioned longitudinally rearward of each of the left track 116 and right track 118, and similar to the front idler 120, provides a rotational surface for the track to rotate about, and provides a support point to transmit force between the working vehicle 100 and the ground. As the left and right tracks transition between their vertical lower and upper portions parallel to the ground, they rotate about the rear sprocket, so that approximately half the outer diameter of each rear sprocket engages with the corresponding left or right track. This engagement can be achieved through a configuration of sprockets and pins, where pins in the left and right tracks are engaged by recesses in the rear sprockets to transmit force. This engagement also results in a vertical height of the track that is only slightly greater than the outer diameter of each rear sprocket at the longitudinal back or rear of the corresponding track. The final engagement point 132 of the track can be approximated as a point on each track located vertically below the center of the rear sprocket, which is the final point of track engagement with the ground. When a work vehicle encounters a ground feature while traveling in the opposite or rearward direction, the tracks may first meet the feature at their respective final 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 upon reaching the ground feature at its final engagement point. If the elevation of the ground feature is lower than the elevation of the surrounding ground, the work vehicle may continue to move backward without pitching until its center of gravity is above the edge of the downward-facing ground feature in the vertical direction. At this point, the work vehicle may pitch backward until its final engagement point contacts the ground.

[0045] In this embodiment, each rear sprocket 124 can be powered by a rotatably connected hydraulic motor to drive the left track 116 and the right track 118, thereby controlling the propulsion and traction of the work vehicle 100. Each of the left and right hydraulic motors can receive pressurized hydraulic fluid from a hydrostatic pump, the flow direction and displacement of which control the rotational direction and speed of the left and right hydraulic motors. Each hydrostatic pump can be driven by the work vehicle's engine 134 (or an equivalent power source) and can be controlled by an operator in the cab 136 to issue commands that can be received by the controller 138 and transmitted to the left and right hydrostatic pumps. In an alternative embodiment, each rear sprocket can be driven by a rotatably connected electric motor or a mechanical system that transmits power from the engine.

[0046] Top idler pulleys 126 are positioned longitudinally between the front idler pulley 120 and the rear sprocket 124, above track support pulleys 122, along the left and right sides of the working vehicle 100. Similar to track support pulleys, each top idler pulley is rotatably connected to either the left track 116 or the right track 118 via an engagement between the lower surface of the track and the upper surface of the top idler pulley. This configuration allows the top idler pulleys to support the track over the longitudinal span between the front idler pulley and the rear sprocket, and prevents the upper portion of the track, parallel to the ground, from deflecting downwards between the front idler pulley and the rear sprocket.

[0047] The underframe 114 is attached to and provides support and traction to the chassis 140 of the work vehicle 100. The chassis is a frame that provides structural support and rigidity to the work vehicle, thereby allowing force to be transmitted between the blade 142 and the left track 116 and right track 118. In this embodiment, the chassis is a welded assembly composed of multiple shaped and joined steel components; however, in alternative embodiments, it may be composed of any number of different materials or constructions.

[0048] The blade 142 is a working tool that can engage with the ground or material to, for example, move material from one location to another and create features on the ground, including flat areas, plains, hills, roads, or more complex shape features. In this embodiment, the blade of the work vehicle 100 may be referred to as a six-way blade, a six-way adjustable blade, or a power angle tilt (PAT) blade. The blade can be hydraulically actuated to move vertically up or down (hereinafter, blade “lifting”), tilt left or right (hereinafter, blade “tilting”), and swing left or right (hereinafter, blade “sliding”). Alternative embodiments may utilize blades with fewer degrees of freedom controlled by hydraulics, such as a four-way blade that can be non-sliding or non-actuated in the swing direction 112.

[0049] The blade 142 is movably connected to the chassis 140 of the work vehicle 100 via a linkage 146 that supports and actuates the blade and is configured to allow the blade to be raised or lowered relative to the chassis (i.e., raised or lowered in the vertical direction 110). The linkage may include multiple structural members to transmit force between the blade and the rest of the work vehicle and may provide attachment points for a hydraulic cylinder that actuates the blade in lifting, tilting, and slanting directions. As mentioned herein, and as follows regarding... Figure 2 As further described, the "blade positioning unit" 200 may include, for example, a linkage, a hydraulic cylinder, and additional and / or equivalent structures associated with actuating the blade in the lifting, tilting, and sliding directions.

[0050] The linkage mechanism 146 includes a C-shaped frame 148, i.e., a C-shaped structural member located behind the blade 142, wherein the C-shape opens toward the rear of the work vehicle 100. Each rear end of the C-shaped frame is pivotally connected to the chassis 140 of the work vehicle 100, for example, via a pin bushing joint, thereby allowing the front portion of the C-shaped frame to be raised or lowered relative to the work vehicle about a pivoting connection at the rear of the C-shaped frame. The front portion of the C-shaped frame is located approximately at the lateral center of the work vehicle and is connected to the blade via a ball joint. This allows the blade to have three degrees of freedom (lift-tilt-slide) in its orientation relative to the C-shaped frame, while still transmitting rearward forces on the blade to the rest of the work vehicle.

[0051] As described above, a second set of one or more sensors 162 is provided, which are associated with the blade positioning unit 200. The blade 142 can be raised or lowered relative to the work vehicle 100 by actuation 150 of a lifting cylinder that can raise and lower the C-frame 148. For each lifting cylinder, the rod end is pivotally connected to an upwardly projecting U-shaped clamp of the C-frame, while the head end is pivotally connected to the rest of the work vehicle located just below and in front of the cab 136. The configuration of the linkage 146 and the positioning of the pivoting connections for the head and rod ends of the lifting cylinder result in the extension of the lifting cylinder lowering the blade and the retraction of the lifting cylinder raising the blade. In alternative embodiments, the blade can be raised or lowered by different mechanisms, or the lifting cylinders can be configured differently, such as a configuration where the extension of the lifting cylinder raises the blade and the retraction of the lifting cylinder lowers the blade. In a particular embodiment, at least one of the sensors 162 in the second group is preferably positioned in association with the lifting cylinder to generate, for example, an output signal corresponding to the extension of the lifting cylinder.

[0052] Similar to the first group of sensors 144, the second group of sensors 162 can be configured to measure angular position (tilt or orientation), velocity, acceleration, or linear acceleration. Sensor 162 (or in other words, another sensor in the second group of sensors 162) can provide a blade tilt signal indicating the angle of the blade relative to gravity. In an alternative embodiment, sensor 162 (or in other words, another sensor in the second group of sensors 162) can be configured to measure the angle of the linkage 146, such as the angle between the linkage 146 and the chassis 140, to determine the blade position. In other alternative embodiments, sensor 162 can be configured to measure the blade position by measuring different angles, such as the angle between the linkage and the blade, or the linear displacement of a cylinder attached to the linkage or the blade.

[0053] The blade 142 can be tilted relative to the work vehicle 100 by actuation of the tilt cylinder 152, which can also be referred to as moving the blade in the tilt direction 104. The rod end of the tilt cylinder is pivotally connected to a U-clamp located on the back and left side above a ball joint between the blade and the C-frame, and the head end is pivotally connected to an upwardly projecting portion of the linkage mechanism 146. Positioning of the pivoting connection for 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 when viewed from the cab 136) and causes the retraction of the tilt cylinder to tilt the blade to the right (or clockwise when viewed from the cab 136). In alternative embodiments, the blade can be tilted by different mechanisms (e.g., an electric motor or a hydraulic motor), or the tilt cylinder can be configured in different ways, such as a configuration where the tilt cylinder is mounted vertically and located on the left or right side of the blade, or a configuration with two tilt cylinders.

[0054] The blade 142 can be obliquely moved relative to the work vehicle 100 by the actuation of the oblique cylinder 154, which can also be referred to as moving the blade in the swing direction 112. For each oblique cylinder, the rod end is pivotally connected to the U-clamp of the blade, while the head end is pivotally connected to the U-clamp of the C-frame 148. One oblique cylinder is located on the left side of the work vehicle, to the left of the ball joint between the blade and the C-frame, and the other oblique cylinder is located on the right side of the work vehicle, to the right of the ball joint between the blade and the C-frame. This positioning results in the blade obliquely moving to the right or swinging clockwise when viewed from above by the extension of the left end of the oblique cylinder and the retraction of the right end of the oblique cylinder, and in the blade obliquely moving to the left or swinging counterclockwise when viewed from above by the retraction of the left end of the oblique cylinder and the extension of the right end of the oblique cylinder. In alternative embodiments, the blade can be obliquely moved by different mechanisms, or the oblique cylinders can be configured differently.

[0055] Due to the geometry of the linkage 146 in this embodiment, the blade 142 does not rise or fall in an ideal vertical line with respect to the work vehicle 100. Instead, a point on the blade will follow a curve as it rises and falls. This means that the vertical component of the blade velocity is not exactly proportional to the linear velocity of the lifting cylinder 150 as it extends or retracts, and the vertical component of the blade velocity may vary even when the linear velocity of the lifting cylinder is constant. This also means that the lifting cylinder has a mechanical advantage that 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 parts of the blade and linkage) and the state of the blade and linkage (e.g., sensors sensing one or more positions, angles, or orientations of the blade or linkage, such as sensor 162), the controller 138 can compensate for this nonlinearity, at least with respect to blade lifting. If only specific kinematic relationships need to be considered (e.g., only those kinematic relationships that affect blade lifting) or if only limited compensation accuracy is required, an incomplete or simplified kinematic model can be used. The controller can utilize this compensation and desired speed, such as a command to raise the blade at a specific vertical speed, to issue a command that can achieve the flow rate into the lifting cylinder, thereby causing the blade to rise at a specific vertical speed regardless of the current position of the linkage mechanism. For example, the controller can issue a command to change the flow rate into the lifting cylinder to achieve a substantially constant vertical speed for the blade.

[0056] Similarly, due to the positioning of the tilt cylinder 152 and the slant cylinder 154 and their connection to the blade 142, the angular velocity and angle of the blade tilt are not entirely proportional to the linear velocities of the tilt cylinder and the slant cylinder, respectively. Even if the linear velocities of the tilt cylinder and the slant cylinder are constant, the angular velocity and angle of the tilt may still vary. This also means that both the tilt cylinder and the slant cylinder possess mechanical advantages that vary depending on the position of the blade. Much like the lifting cylinder, given the kinematic model of the blade and linkage mechanism and the state of the blade and linkage mechanism, the controller can compensate for this nonlinearity, at least based on the blade tilt and angle. If only specific kinematic relationships need to be considered (e.g., those that only affect the blade tilt and angle), or if only limited compensation accuracy is required, an incomplete or simplified kinematic model can be used. The controller can use this compensation and desired angular velocity (e.g., a command to tilt or scoop the blade at a specific angular velocity) to issue a command that changes the flow rate into the tilt or scoop cylinder, thereby causing the blade to tilt or scoop at a specific angular velocity, regardless of the current position of the blade or linkage mechanism.

[0057] In an alternative embodiment, the blade can be connected to the rest of the work vehicle 100 in a manner that tends to make the blade's lifting speed (in the vertical direction 110), tilt angular velocity (in the lateral tilt direction 104), or lateral angular velocity (in the swing direction 112) proportional to the linear speed of the lifting cylinder 150, tilt cylinder 152, or lateral cylinder 154, respectively. This can be achieved through the specific design of the linkage mechanism 146 and the positioning of the pivoting connections of the lifting cylinder, tilt cylinder, and lateral cylinder. In this alternative embodiment, the controller may not need to compensate for the nonlinear response of the blade to the actuation of the lifting cylinder, tilt cylinder, and lateral cylinder, or the need for compensation may be reduced.

[0058] Each of the lifting cylinder 150, tilting cylinder 152, and slant cylinder 154 is a double-acting hydraulic cylinder. One end of each cylinder may be referred to as the head end, and the opposite end of each cylinder may be referred to as the 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, for example, via a pin-bearing or pin-shearing connection, to cite only two pivotal connections as examples. As double-acting hydraulic cylinders, each cylinder can apply force in either the extension or retraction direction. Directing pressurized hydraulic fluid into the head chamber of the cylinder will tend to apply force in the extension direction, while directing pressurized hydraulic fluid into the rod chamber of the cylinder will tend to apply force in the retraction direction. Both the head chamber and the rod chamber can be located within the cylinder body and can 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 chamber and the rod chamber varies with the movement of the piston, which causes the hydraulic cylinder to extend or retract.

[0059] Figure 2This is an illustrative schematic diagram of a blade positioning unit 200, which includes, for example, hydraulic and electrical components for controlling the position of the blade 142. Each of the lifting cylinder 150, tilt cylinder 152, and swashplate cylinder 154 can be hydraulically connected to a hydraulic control valve 156, which can be positioned within 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 is rotatably connected to the engine 134, and directs this fluid to the lifting cylinder, tilt cylinder, swashplate cylinder, and other hydraulic circuits or functional components of the work vehicle. The hydraulic control valve can meter this fluid or control the flow rate of the hydraulic fluid to each hydraulic circuit it is connected to. In an alternative embodiment, the hydraulic control valve may not meter this fluid, but may selectively provide flow paths to these functional components, with metering performed by another component (e.g., a variable displacement hydraulic pump) or not at all. Hydraulic control valves can measure this fluid through multiple spool valves, the position of which controls the flow of hydraulic fluid and other hydraulic logic. Spool valves can be actuated by solenoids, pilot valves (e.g., pressurized hydraulic fluid acting on the spool valve), upstream or downstream pressure, or some combination of these and other components.

[0060] according to Figure 1 In the illustrated embodiment, the spool of hydraulic control valve 156 is switched via a pilot valve whose pressure is at least partially controlled by an electro-hydraulic pilot valve 160 connected to controller 138. The electro-hydraulic pilot valve is located within the interior area of ​​the work vehicle and receives pressurized hydraulic fluid from a hydraulic source, selectively directing this fluid to a pilot line hydraulically connected to the hydraulic control valve. In this embodiment, the hydraulic control valve and the electro-hydraulic pilot valve are separate components; however, in alternative embodiments, the two valves may be integrated into a single valve assembly or manifold. In this embodiment, the hydraulic source is hydraulic pump 158. In alternative embodiments, a pressure reducing valve may be used to reduce the pressure of the pressurized hydraulic fluid supplied by the hydraulic pump to a set pressure, such as 600 pounds per square inch, for use by the electro-hydraulic pilot valve. Figure 2In the illustrated embodiment, the valves within the electro-hydraulic pilot valve reduce the pressure of the received hydraulic fluid via solenoid-actuated spools that discharge the hydraulic fluid to a hydraulic reservoir. In this embodiment, the controller actuates the solenoids by sending a specific current (e.g., 600mA) to each solenoid. In this way, the controller can actuate the blade 142 by sending an electrical command signal to the electro-hydraulic pilot valve, which in turn provides a hydraulic signal (pilot signal) to the hydraulic control valve. This hydraulic control valve then switches a spool to direct hydraulic flow from the hydraulic pump, thereby actuating the lifting cylinder 150, tilting cylinder 152, and slant cylinder 154. In this embodiment, the controller communicates directly with the electro-hydraulic pilot valve via electrical signals transmitted through a wiring harness and indirectly with the hydraulic control valve through the electro-hydraulic pilot valve.

[0061] In alternative embodiments, controller 138 can send commands to actuate blade 142 in several different ways. As an example, the controller can communicate with the valve controller via a controlled area network (CAN) and can send command signals to the valve controller in the form of CAN messages. The valve controller can receive these messages from the controller and, based on those messages, send current to a specific solenoid within the electro-hydraulic pilot valve 160. As another example, the controller can actuate blade 142 via an input device in the cab 136. For example, the operator can use a joystick to issue a command to actuate the blade, and the joystick can generate a hydraulic signal (pilot signal) that is passed to the hydraulic control valve 156 to cause actuation of the blade. In this configuration, the controller can communicate with electrical devices (e.g., solenoids, motors) that can actuate the joystick in the cab. In this way, the controller can actuate the blade by actuating these electrical devices, rather than passing signals to the electro-hydraulic pilot valve.

[0062] Figure 3This is a left-side view of the work vehicle 100 as it travels on ground feature 190, which in this example is a ground feature with an elevation higher than the surrounding ground (e.g., an upward-facing ground feature). As the work vehicle 100 travels on the ground feature, the forward engagement point 130 is the first point of engagement on the left track 116 and right track 118, essentially engaging with the ground feature. As the work vehicle engages the ground feature at the forward engagement point, it begins to pitch upwards or backwards as the front of the work vehicle rises relative to its rear on the ground feature. During this upward or backward pitching, the work vehicle tends to pitch around the final engagement point 132. During this pitching process, a sensor 144 mounted on the chassis can send signals indicating the angle of the chassis 140 relative to the direction of gravity (i.e., orientation in the pitch direction 108) and a signal indicating the angular velocity of the chassis 140 in the pitch direction 108. These signals will indicate the tilt and velocity of upward sloping and pitching in the first direction, and these signals are the opposite of those indicating the tilt and velocity of downward sloping and pitching in the second direction. In this embodiment, the signals from sensor 144 to controller 138 can indicate a range of values, for which values ​​in half of the range indicate the pitch angle and angular velocity in the first direction, and values ​​in the other half of the range indicate the pitch angle and angular velocity in the second direction.

[0063] Similarly, the sensor 162 associated with the blade positioning unit 200 can send a blade tilt signal indicating the pitch angle of the blade 142 relative to the direction of gravity (i.e., orientation in the pitch direction 108) and a blade pitch signal indicating the angular velocity of the blade 142 in the pitch direction 108. These signals will indicate the tilt angle and velocity of upward sloping and pitching in the first direction, which are opposite to the signals indicating the tilt angle and velocity of downward sloping and pitching in the second direction. In this embodiment, the blade tilt and blade pitch signals from sensor 162 to controller 138 can indicate values ​​within a range, where values ​​in half of the range indicate the pitch angle and angular velocity in the first direction, and values ​​in the other half of the range indicate the pitch angle and angular velocity in the second direction.

[0064] As the work vehicle 100 continues to travel on the ground feature 190, the forward engagement point 130 will cease engagement with the ground and instead, it will hover above the ground by a distance determined in part by the height of the ground feature relative to the surrounding ground and the position of the work vehicle on the ground feature. At this point, although the ground feature is an upward-facing feature, it has the effect of a downward-facing feature at a lower elevation than the surrounding ground. Specifically, the area just behind the ground feature is lower than the ground feature. As the center of gravity of the work vehicle passes the top of the ground feature, the work vehicle will pitch forward, and the final engagement point will leave the ground, while the forward engagement point will descend until it contacts the ground.

[0065] As the work vehicle 100 travels on ground feature 190, the blade 142 will rise and fall relative to the ground due to the pitch of the work vehicle. When the work vehicle pitches backward, the blade will rise along with the C-frame 148, and when the work vehicle tilts forward, the blade will fall along with the C-frame, and the blade will fall forward. If the operator of the work vehicle cannot correct the ground feature by commanding the blade to rise or fall in a way that counteracts the effect of the ground feature on the blade height, the work vehicle will create vertical variations on the ground, such as hills and valleys, instead of a smooth surface. As the work vehicle travels over these newly created hills and valleys, the blade will rise and fall again as the work vehicle pitches backward and forward, creating further vertical variations. This series of hills and valleys can be referred to as a "washboard" pattern. In addition to creating this pattern, the pitch of the work vehicle will also disrupt efforts to maintain a uniform flat surface. The operator of the work vehicle can target a specific flat area (e.g., 2%), and if the work vehicle moves up and down on that flat area, the pitch of the work vehicle will create a section of the actual flat area that is either steeper or shallower than the target flat area.

[0066] Now, further illustrative references can be made. Figure 4 An exemplary embodiment of a method 300 for controlling the blade 142 relative to the chassis of a self-propelled work vehicle 100 to produce a desired profile on the ground is described.

[0067] The first exemplary step 310 of the method includes detecting the actual pitch speed of the chassis and the actual pitch angle of the chassis relative to the ground by one or more sensors 144 of a first group mounted on the chassis, and further detecting the actual lifting position of the blade relative to the chassis by one or more sensors 162 of a second group.

[0068] In a second exemplary step 320 of the method, information corresponding to a desired profile about the ground surface to be generated by the blade is provided to the controller 138. In a third exemplary step 330, the controller determines the desired profile to be generated, wherein an output signal may be provided in a fourth exemplary step 340 to automatically control the position of the blade. In a preferred embodiment, the output signal is a lift command calculated for the blade positioning system 200, which consists of three specific items. The first item is a function of the pitch speed error relative to a target pitch speed, the second item is a function of the pitch angle error relative to a target pitch angle, and the third item is a function of the lift position error relative to a target lift position, each command item corresponding to the desired profile about the ground surface.

[0069] In embodiments, the information corresponding to the desired contour of the ground surface to be generated by the blade may include a first target value and a second target value, the first target value being set to correspond to the desired pitch angle of the chassis relative to the ground, and the second target value being set to correspond to the lifting position of the blade relative to the chassis. In some embodiments, a third target value may be further set to correspond to the desired pitch angular velocity of the chassis, particularly in the case of implementing an automatic leveling control system as further described below; however, in many cases, the third target value may be implicitly represented as zero. With the above target values ​​already set, the controller may be configured to determine an error value corresponding at least to the difference between the detected actual pitch angle, the actual lifting position, and the corresponding first and second target values, and further automatically control the position of the blade based on the determined error value.

[0070] According to this embodiment, the fifth step 350 of the method may include displaying a mark on a display unit 166 associated with the work vehicle (e.g., a display unit in the cab 136) on a mobile computing device carried by an operator or other user. The mark may, for example, correspond to one or more determined error values ​​(e.g., in absolute or relative form). Even in embodiments where error values ​​are not explicitly determined and therefore can be displayed, additional or alternative marks may be displayed, including, for example, the actual (i.e., detected) pitch speed and / or target pitch speed of the chassis relative to the ground, the actual (i.e., detected) pitch angle and / or target pitch angle of the chassis relative to the ground, the actual (i.e., detected) lifting position and / or target lifting position of the blade relative to the chassis, one or more characteristics of the desired profile of the ground surface, control signals associated with the controlled position of the blade, etc.

[0071] In one embodiment, information corresponding to the desired profile of the ground surface to be produced by the scraper may be provided by or otherwise provided as part of an automated leveling control system. The system may include a user interface configured to allow an operator to input, select, or otherwise specify a desired leveling profile (surface slope), wherein target values ​​corresponding to scraper control parameters can be automatically derived. Operator selection may take the form of predetermined group settings, wherein target values ​​may be retrieved at least initially from memory, or the operator may select one or more baseline values, wherein the controller obtains or determines control parameters corresponding to the baseline values. In some embodiments, the controller may be connected to receive input signals corresponding to one or more characteristics of the unleveled surface, wherein one or more target values ​​may be derived at least in part based on the input signals.

[0072] In an alternative embodiment, information corresponding to the desired profile of the ground surface to be generated by the blade can be manually provided by the system user through, for example, a user interface configured for it. Manual user input in this embodiment typically includes a first target value corresponding to the desired pitch angle of the chassis relative to the ground, and a second target value corresponding to the lifting position of the blade relative to the chassis. A third target value corresponding to the desired pitch angular velocity of the chassis can also optionally be set manually, but if not set manually, it can be implicitly represented as zero.

[0073] In another alternative embodiment, the control system can selectively operate in a first operating mode, in which at least the lifting position of the blade is controlled based on control signals in response to manually input commands, such as via a joystick or similar component in the cab. At the end of the first operating mode (which may occur automatically upon termination of a manually input command or upon receiving a dedicated mode switching input signal), a first target value and a second target value can be set to correspond to the corresponding actual values ​​detected for the chassis pitch angle relative to the ground and the blade lifting position relative to the chassis. At this point, a second operating mode can be activated to automatically control the blade's position corresponding to a desired profile of the ground surface based on each of the chassis's actual pitch speed, the chassis's actual pitch angle relative to the ground, and the working implement's actual lifting position relative to the chassis. Activation of the second operating mode may be automatically triggered at the end of the first operating mode, or may require a separate input signal from the operator or other source.

[0074] In another alternative embodiment, the actual values ​​detected for the chassis pitch angle relative to the ground and the blade's lifting position relative to the chassis are provided as input to the filtering stage, wherein a first target value and a second target value are dynamically set to correspond to the respective outputs from the low-pass filtering stage. The low-pass filter can typically be used in the filtering stage and includes, for example, but is by no means explicitly limited to, a moving average filter used to smooth fluctuations in the input time-series data.

[0075] The control system and method 300 disclosed herein can alternatively be configured to determine a desired profile of the ground surface to be produced by the shovel by means of one or more target values ​​corresponding to a respective characteristic set at each of one or more locations associated with the shovel. Although the physical sensors according to this disclosure are not located on the shovel itself, or at least do not depend on inputs of actual measurements for control parameters, this embodiment can implement one or more virtual sensors 164 projected at corresponding locations associated with the shovel.

[0076] For example, in steps 320 and 330, based on the input signals received in step 310 from the first group of sensors 144 and the second group of sensors 162, the controller can be configured to generate predicted values ​​for a corresponding characteristic at each of the one or more locations, based on at least one of the actual pitch speed of the chassis, the actual pitch angle of the chassis relative to the ground, and the actual lifting position of the work vehicle relative to the chassis, and further determine an error value corresponding to at least the calculated difference between the predicted value and the target value of the corresponding characteristic. With the error value representing the difference between the target flat ground profile (i.e., the target positioning of the blade) and the actual flat ground profile (i.e., the measured or projected positioning of the blade) already determined, in step 340, the controller further automatically controls the position of the blade via a control signal arriving at the blade positioning unit 200 based on the determined error value.

[0077] As used in this article, the phrase "one or more" when used with a list of items means that different combinations of one or more items can be used, and it may be necessary to use only one of each item in the list. For example, "one or more" in items A, B, and C can include, but is not limited to, items A or items A and B. The example could also include items A, B, and C, or items B and C.

[0078] Therefore, it can be seen that the apparatus and methods of this disclosure readily achieve the stated objects and advantages, as well as those inherent therein. Although certain preferred embodiments of this disclosure have been illustrated and described for the present purpose, many changes can be made by those skilled in the art in the arrangement and construction of components and steps, and these changes are included within the scope and spirit of this disclosure as defined by the appended claims. Each feature or embodiment of the disclosure may be combined with any other feature or embodiment of the disclosure.

Claims

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, wherein, The blade is connected to the chassis and is raised and lowered relative to the chassis via at least a blade positioning unit, the method comprising: detecting an actual pitch speed of the chassis and an actual pitch angle of the chassis relative to the ground by a first set of one or more sensors mounted on the chassis; detecting an actual raised position of the blade relative to the chassis by a second set of one or more sensors (162) associated with the blade positioning unit; determining a desired profile to be produced by the blade with respect to the ground surface; and automatically controlling a position of the blade corresponding to the desired profile with respect to the ground surface as a function of each of the actual pitch speed of the chassis, the actual pitch angle of the chassis relative to the ground, and the actual raised position of the blade relative to the chassis.

2. The method of claim 1, wherein, The step of determining a desired profile to be produced by the blade with respect to the ground surface comprises: 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 raised position of the blade relative 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 raised position, and the respective first and second target values, and further automatically controlling the position of the blade as a function of 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 determined error values.

5. The method of any one of claims 2 to 4, wherein, The first and second target values are set to correspond to input received from a user via a user interface engaged with the automatic grading control system.

6. The method of claim 5, wherein, The step of determining a desired profile to be produced by the blade with respect to the ground surface further comprises: dynamically setting a third target value corresponding to a pitch speed of the chassis.

7. The method of any of claims 2-4, further comprising: selectively initiating a first operating mode in which the raised position is controlled based on control signals responsive to a manual input command, upon termination of the manual input command ending the first operating mode, setting the first and second target values to correspond to respective actual values detected for the pitch angle of the chassis relative to the ground and the raised position of the blade relative to the chassis, and initiating a second operating mode to automatically control the position of the blade corresponding to the desired profile with respect to the ground surface as a function of each of the actual pitch speed of the chassis, the actual pitch angle of the chassis relative to the ground, and the actual raised position of the blade relative to the chassis.

8. The method of any one of claims 2 to 4, wherein, providing the actual values detected for the pitch angle of the chassis relative to the ground and the raised position of the blade relative to the chassis as input to a filter stage, wherein the first and second target values are dynamically set to correspond to respective outputs from the filter stage.

9. The method according to any one of claims 1 to 4, 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 of: an actual pitch speed of the chassis; an actual pitch angle of the chassis relative to the ground; an actual lift position of the blade relative to the chassis; a desired profile with respect to the ground surface; and a control signal associated with a controlled position of the blade.

10. The method of claim 1, further comprising projecting one or more virtual sensors on a corresponding location associated with the shovel blade, wherein, The step of determining a desired profile with respect to the ground surface to be produced by the blade comprises setting one or more target values corresponding to respective properties at each of the one or more positions.

11. The method according to claim 10, further comprising: generating a predicted value for a respective property at each of the one or more positions as a function of at least each of the actual pitch speed of the chassis, the actual pitch angle of the chassis relative to the ground, and the actual lift position of the blade relative to the chassis.

12. The method according to 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 property.

13. The method according to claim 12, further comprising: automatically controlling the position of the blade as a further function of the determined error value.

14. The method according to any one 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 of the determined error values.

15. A self-propelled work vehicle (100) comprising: a chassis (140) supported by a plurality of ground engaging units (116, 118); a blade (142) connected to a front portion of the chassis in a work direction by a positioning unit (200) configured to at least raise or lower the blade relative to the chassis; a first set of one or more sensors (144) fixed relative to the chassis and configured to generate output signals corresponding to an actual pitch speed of the chassis and an actual pitch angle of the chassis relative to the ground; a second set of one or more sensors (162) connected to the positioning unit and configured to generate output signals corresponding to an actual lift position of the blade relative to the chassis; and a controller (138) functionally linked to the first set of sensors, the second set of sensors, and the positioning unit, and further configured for performing the steps of the method according to any one of claims 1 to 14. ​

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