WORK MACHINE AND METHOD FOR AUTOMATICALLY CONTROLLING THE TRAJECTORY OF AN IMPLEMENT RELATIVE TO A TARGET SURFACE GRADE

Description

FIELD OF THE DISCLOSURE

The present disclosure relates generally to work machines such as construction and forestry machines having ground-engaging work implements, and more particularly to systems and methods for managing the trajectory of a point of interest about a machine implement in order to maintain a desired surface grade.

BACKGROUND

Work machines of this type may for example include excavator machines, motor graders, backhoes, front shovel machines, and others. These work machines may typically have tracked ground engaging units supporting the undercarriage from the ground surface, but work machines within the scope of the present disclosure may also include stationary frames with one or more components moveable relative thereto. These work machines may further include a work implement, which includes one or more components, that is used to modify the terrain based on control signals from and/or in coordination with movement of the work machine.

Control systems are often integrated into machine platforms for managing the motion of the work implement to perform automation tasks. On grade control systems in particular, the machine control system needs to perform calculations to manage the trajectory of a point of interest about the machine implement to maintain a desired surface grade.

BRIEF SUMMARY

The current disclosure provides an enhancement to conventional systems, at least in part by introducing a novel work machine, control system, and method for utilizing time referenced lookahead and lookbehind data points relative to current point of interest trajectory for planning the upcoming trajectory path.

In one particular and exemplary embodiment, a computer-implemented method is provided for controlling movement of a ground-engaging tool for a work machine, wherein the ground-engaging tool is at a first end of an implement comprising one or more components coupled on a second end thereof to, and independently moveable with respect to, a main frame of the work machine. The method comprises: determining one or more future locations for a point of interest associated with the ground-engaging tool, based on sensed point of interest data comprising a current location, a current trajectory, and a current velocity thereof; calculating a convergence trajectory for the point of interest from the current location and with respect to a target surface profile, based at least in part on the determined one or more future locations along the current trajectory; and generating output signals for automatic control of movement of the point of interest based at least in part on the calculated convergence trajectory.

In one exemplary aspect according to the above-referenced method embodiment, one or more characteristics of the calculated trajectory may be adjusted based on one or more predicted slope transitions associated with a plurality of determined future locations. The one or more characteristics may for example comprise a magnitude of the trajectory.

In another exemplary aspect according to the above-referenced method embodiment, the one or more slope transitions may be predicted using calculated surface normal vectors respectively associated with the plurality of determined future locations.

In another exemplary aspect according to the above-referenced method embodiment, one or more previous locations of the point of interest may be determined, and the convergence trajectory calculated further based at least in part on the determined one or more previous locations.

In another exemplary aspect according to the above-referenced method embodiment, one or more characteristics (e.g., a magnitude) of the calculated convergence trajectory may be adjusted based on one or more predicted slope transitions associated with a plurality of determined previous and future locations.

In another exemplary aspect according to the above-referenced method embodiment, the one or more slope transitions may be predicted using calculated surface normal vectors respectively associated with the plurality of determined previous and future locations.

In another exemplary aspect according to the above-referenced method embodiment, the method may comprise mapping a current surface profile and the target surface profile in a three dimensional coordinate framework, and calculating an error between the current surface profile and the target surface profile with respect to a previously traversed portion by the point of interest.

In another exemplary aspect according to the above-referenced method embodiment, feedback comprising the calculated error may be generated for further calculating the convergence trajectory and/or controlling movement of the point of interest.

In another embodiment, a work machine as disclosed herein may include a ground-engaging tool at a first end of an implement comprising one or more components coupled on a second end thereof to, and independently moveable with respect to, a main frame of the work machine. One or more processors, for example including or otherwise integrated within a machine controller, may be configured to direct the performance of steps according to the above-referenced method embodiment and optional aspects thereof.

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

BRIEF DESCRIPTION OF THE DRAWINGS

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

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

FIG. 3 is a flowchart representing an exemplary embodiment of a method of controlling a point of interest to a target trajectory as disclosed herein.

FIG. 4 is a flowchart representing an exemplary embodiment of a method of determining a target trajectory as disclosed herein.

FIG. 5 is a graphical diagram representing an example of trajectory updates resulting from ground surface profile changes.

FIG. 6 is a graphical diagram representing an example of trajectory updates resulting from error variance.

FIG. 7 is a graphical diagram representing an example of trajectory updates resulting from user-initiated adjustments to velocity.

FIG. 8 is a graphical diagram representing an example of trajectory updates resulting from look-ahead and/or look-behind points relative to a current position of the point of interest, in accordance with an embodiment of a system and method as disclosed herein.

FIG. 9 is a graphical diagram representing an example of trajectory updates further accounting for variance in surface normal vectors from various look-ahead points, in accordance with an embodiment of a system and method as disclosed herein.

FIG. 10 is a graphical diagram representing an example of trajectory updates further accounting for variance in surface normal vectors from look-behind and look-ahead points, in accordance with an embodiment of a system and method as disclosed herein.

DETAILED DESCRIPTION

Referring now to FIGS. 1-10, various embodiments may now be described of a system and method for controlling the trajectory and velocity of a point-of-interest of a working tool attached to the work implement of a work machine, for example to accurately control movement of the working tool across transition points in a desired surface grade.

FIG. 1 depicts a representative self-propelled work machine 120 in the form of, for example, a tracked excavator machine. The work machine 120 includes an undercarriage 122 including first and second ground engaging units 124 (e.g., tracks). Only one of the ground engaging units is shown in FIG. 1. The other ground engaging unit is parallel to the illustrated ground engaging unit. The undercarriage includes respective first and second travel motors (not shown) for driving the first and second ground engaging units. The ground engaging units can be driven at the same velocity to move the undercarriage forward (e.g., in a forward direction indicated by an arrow 126) or backward (e.g., in a direction opposite the arrow 126) with respect to underlying terrain 128 (e.g., ground or other material supporting the undercarriage). The ground engagement units can also be driven at different velocities to enable the undercarriage to turn with respect to the terrain at an angle with respect to the forward direction represented by the arrow 126.

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

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

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

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

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

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

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

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

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

In the illustrated embodiment, a sensor system 204 (see FIG. 2) is also mounted on the work machine 120. As illustrated in FIG. 1, the sensor system includes a first sensor 204a mounted to the main frame 130, a second sensor 204b mounted to the boom 142, a third sensor 204c mounted to the arm 144, a fourth sensor 204d mounted to the dogbone connector 160, and a fifth sensor 204e mounted to the working tool 146.

In the illustrated embodiment, each of the first through fifth sensors is an inertial measurement unit (IMU). IMUs are tools that capture a variety of motion-based and position-based measurements, including, but not limited to, velocity, acceleration, angular velocity, and angular acceleration. IMUs include a number of sensors including, but not limited to, accelerometers, which measure (among other things) velocity and acceleration, gyroscopes, which measure (among other things) angular velocity and angular acceleration, and magnetometers, which measure (among other things) strength and direction of a magnetic field.

Generally, as discussed above, an accelerometer provides measurements, with respect to (among other things) force due to gravity, while a gyroscope provides measurements, with respect to (among other things) rigid body motion. The magnetometer provides measurements of the strength and the direction of the magnetic field, with respect to (among other things) known internal constants, or with respect to a known, accurately measured magnetic field. The magnetometer provides measurements of a magnetic field to yield information on positional, or angular, orientation of the IMU; similarly to that of the magnetometer, the gyroscope yields information on a positional, or angular, orientation of the IMU. Accordingly, the magnetometer may be used in lieu of the gyroscope, or in combination with the gyroscope, and complementary to the accelerometer, in order to produce local information and coordinates on the position, motion, and orientation of the IMU.

An accelerometer is an electro-mechanical device or tool used to measure acceleration (e.g., in meters per seconds squared (m/s²)), which is defined as the rate of change of velocity (e.g., in meters per second (m/s)) of an object. Accelerometers sense either static forces (e.g., gravity) or dynamic forces of acceleration (e.g., vibration and movement). An accelerometer may receive sense elements measuring the force due to gravity. By measuring the quantity of static acceleration due to gravity of the Earth, an accelerometer may provide data as to the angle the object is tilted with respect to the Earth, the angle of which may be established in an x-axis, y-axis, and z-axis coordinate frame. However, where the object is accelerating in a particular direction, such that the acceleration is dynamic (as opposed to static), the accelerometer produces data which does not effectively distinguish the dynamic forces of motion from the force due to gravity by the Earth. A gyroscope is a device used to measure changes in orientation, based upon the object's angular velocity (rad/s) or angular acceleration (rad/s²). A gyroscope may constitute a mechanical gyroscope, a micro-electro-mechanical system (MEMS) gyroscope, a ring laser gyroscope, a fiber-optic gyroscope, and/or other gyroscopes as are known in the art. Principally, a gyroscope is employed to measure changes in angular position of an object in motion, the angular position of which may be established in an x-axis, y-axis, and z-axis coordinate frame.

In an embodiment, for each of at least one linkage joint associated with a work implement 140 (e.g., each coupled set of components in a boom assembly), sense elements from the received work implement position sensor output signals may be fused in an independent coordinate frame associated at least in part with the respective linkage joint, the independent coordinate frame of which is independent of a global navigation frame for the work machine 120, wherein for example measurements received by work implement position sensors 204 may be merged to produce a desired output in the work implement of the work machine.

As schematically illustrated in FIG. 2, the self-propelled work machine 120 includes a control system that includes a controller 210. The controller may be part of the machine control system of the working machine, or it may be a separate control module. The controller is optionally mounted in the operator's cab 192 at the control station 194. The machine controller can include a user interface 212 such as a control panel. The user interface can include a user interface tool 214 such as an input/output device (e.g., a keyboard, a joystick, or the like.) The user interface can also include a display 216.

The machine controller 210 is configured to receive input signals from some or all of various work implement position sensors 204a. . . 204e collectively defining, or otherwise part of, the sensor system 204. The sensors of the sensor system may typically be discrete in nature, but signals representative of more than one input parameter may be provided from the same sensor.

Although not expressly shown in FIG. 2, the sensor system 204 can also refer to signals provided from the machine control system. For example, in an embodiment machine location determining sensors may include a global navigation satellite system (GNSS) receiver.

Machine location determining sensors may additionally or in the alternative include for example ground speed sensors, steering sensors, or the like, or equivalent inputs from the machine control system.

Alternative work implement position sensors may for example include rotary pin encoders mounted at pivot pins to detect the relative rotational positions of the respective components, linear encoders mounted on hydraulic cylinders to detect the respective extensions thereof, and the like.

Additional sensors may be provided and configured to produce velocity measurement signals representing a velocity measurement of respective actuators, for example including hydraulic piston-cylinder units associated with respective components of a work implement (e.g., boom assembly).

The controller 210 can be configured to produce outputs to the user interface 212 for displaying information to the human operator. In addition, or in the alternative, the machine controller can be configured to generate control signals for controlling the operation of respective actuators, or generate signals for indirect control via intermediate control units, associated with a machine steering control system 226, a machine implement control system 228, and an engine speed (propulsion) control system 230. The machine controller can generate control signals for controlling the operation of various actuators, such as hydraulic motors or hydraulic piston-cylinder units of the boom actuator 170, the arm actuator 172, and the working tool actuator 174. The control signals from the controller can be received by electro-hydraulic control valves associated with the actuators such that the electro-hydraulic control valves control the flow of hydraulic fluid to and from the respective hydraulic actuators to control the actuation thereof in response to the control signal from the controller.

The controller 210 may include, or be associated with, a processor 250, a computer readable medium 252, a communication unit 254, data storage 256 such as for example a database network, and the aforementioned user interface (control panel) 212 having the display 216 and the user interface tool (e.g., input/output device) 214 by which a human operator may input instructions to the controller.

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

Not specifically represented in FIG. 2, the controller 210 of the work machine 120 may in some embodiments further receive inputs from and generate outputs to remote devices associated with a user via a respective user interface, for example a display unit with touchscreen interface. Data transmission between, for example, a machine control system and a remote user interface may take the form of a wireless communications system and associated components as are conventionally known in the art. In certain embodiments, a remote user interface and vehicle control systems for respective work machines may be further coordinated or otherwise interact with a remote server or other computing device for the performance of certain operations in a system as disclosed herein.

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

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

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

Referring next to FIGS. 5-7, and still using an excavator as an example of the work machine 120 for illustrative purposes, a grade control system (e.g., controller 210) on such a machine attempts to manage the motion of the work implement 140, and more particularly the working tool 146, in order to keep a point of interest 148 (often the tool tip, but could represent any point on the implement) on a target grade 510. This grade can be defined as a flat plane, or could be a complex surface, represented digitally as a file of geometric data. As the point of interest traverses the surface in three-dimensional space, decisions need to be made by the control system to move it toward and keep it on the target surface.

As represented in FIG. 5, the trajectory for the point of interest 148 may need to be constantly evaluated and updated by the control system to adjust from a current trajectory 512 (in the example shown, having a downward slope corresponding to a first portion of the target grade 510) to a future trajectory 514 (in the example shown, having a flat slope corresponding to a second portion of the target grade) to account for changes in the surface geometry.

As represented in FIG. 6, the trajectory for the point of interest 148 may also or in the alternative need to be updated by the control system to undertake a current trajectory 512 (in the example shown, directly downward to a first portion of the target grade 510) before resuming a future trajectory 514 (in the example shown, having a flat slope corresponding to the first portion of the target grade) to account for error variance. While the illustrated example includes a current trajectory that extends directly downward toward the surface, one of skill in the art may appreciate that, even in similar contexts where the trajectory is updated to account for error variance, the current trajectory vector may be somewhat sloped relative to the ground surface to move toward and eventually intersect with the target grade at a future position corresponding to the illustrated future trajectory.

As represented in FIG. 7, the trajectory for the point of interest 148 may also or in the alternative need to be updated by the control system to account for changes in velocity manually requested by the operator.

In FIG. 3, the flowchart represents an exemplary method 300 for tracking motion of linkage joints for maintaining a desired trajectory path (e.g., corresponding to a current portion of a desired surface grade) for the point-of-interest 148 of a working tool 146. In a first step 310, the method receives a target trajectory for moving the point-of-interest. For example, the target trajectory can be a predetermined target trajectory that forms a portion of an overall terrain forming (e.g., excavation) plan. In a second step 312, the method receives inputs from the above-described IMUs 204a, 204b, 204c, 204d, 204e, and the method determines a current location of the point-of-interest. In a third step 314, the method uses inverse kinematics or other suitable techniques to determine various angles and pivoting velocities of the components of the work implement 140 to achieve the target velocity of the point-of-interest. In a fourth step 316, the method applies controlled hydraulic pressures to the actuators 170, 172, 174 to move the boom 142, the arm 144, and the working tool 146 to achieve the determined angles and pivoting velocities. In the fourth step 316, the method receives feedback from the IMUs, which enables the method to adjust the hydraulic pressures as needed to maintain the desired trajectory.

In various embodiments, the controller 210 may be configured to determine a target velocity for the point-of-interest 148, or functionally linked to another processing device for the same, based on a currently known position of the point-of-interest and based on a desired movement of the point-of-interest with respect to the terrain to be manipulated. The target velocity may for example be provided as an input to a velocity determination subsystem, which performs a modeling technique such as an inverse kinematic determination based on the target velocity to determine a desired boom pivot velocity, a desired arm pivot velocity, and a desired bucket pivot velocity.

As described above, the work machine 120 and the method 300 enable the point-of-interest 148 of the working tool 146 to be moved along a desired trajectory. In certain embodiments, because of the positions of the disclosed pivot axes associated with the linkage joints 150, 152, 154, the point-of-interest is only able to move in a point-of-interest plane perpendicular to the pivoting axes and parallel to the working direction (arrow 176). In other embodiments within the scope of the present disclosure, further components, attachments, sensors, and/or the like may be provided and enable a point-of-interest 148 of a working tool 146 to move in at least one additional degree of freedom.

In FIG. 4, an embodiment of a method 400 may now be described for further controlling a trajectory and a velocity of the work implement 140, and more particularly the point-of-interest 148, relative to a desired surface grade, and more particularly to improve accuracy of the machine control across transition points between distinct trajectories.

In a first step 410, at least target surface profile data and current point of interest data may be received, obtained, or otherwise determined. The current point of interest data may preferably include location, trajectory, and velocity of the point of interest. Such current point of interest data may be determined using techniques as disclosed above or in any number of ways as would be understood by one of skill in the art.

In an embodiment, the target surface profile may be determined in a work machine coordinate system. In other embodiments within the scope of the present disclosure, a position of the work machine and the target surface profile parameters may be determined in a target surface coordinate system. In either example, the grade control system may reliably direct control of a grading operation in accordance with the determined target surface profile, wherein for example movement of the work machine and/or one or more work implement components is controlled or directed based at least in part on the determined target surface profile and further in view of monitored positions and/or movements of the work implement. In some embodiments, wherein for example a location of the point of interest is desired in the same three-dimensional reference coordinate plane as the target surface profile data, the location of the point of interest may initially be determined in a first reference coordinate plane, such as for example where the location is determined relative to a location on or associated with the main frame of the work machine, and then converted as needed to a second reference coordinate in which the target surface profile data is provided or otherwise available.

In a second step 412, “look-ahead” points and/or “look-behind” points are determined relative to the current position of the point of interest. As represented in FIG. 8, these data points may represent an elevation 524 with respect to the target surface 510 (i.e. the distance between the target surface grade and the point of interest 148), and in some embodiments may further represent a surface normal indication (i.e., a vector representing the pose of the surface at the point of interest location). The look-ahead and look-behind points may for example be time based. In the illustrated embodiment, the working tool 146 and point of interest 148 are shown with respect to a current location 516 (i.e., at time t=t0), whereas a future position of the working tool and the point of interest after some period of time (i.e., t=t1) given its current trajectory 512 are represented as look-ahead working tool position 518 and look-ahead point of interest position 522, respectively.

In a third step 414, utilizing an indication of the elevation 524 (e.g., distance to the surface) of the point of interest 148 at the current location 516 as well as the time based look-ahead elevation, a trajectory determination can be made that allows the point of interest to converge toward the target surface. Because this is a time based lookahead, the distance 526 traversed for this convergence will typically vary with the current velocity of the point of interest.

In a fourth step 416, transitions in the target surface profile 410 may be identified or predicted using surface normal vectors from one or more of the look-ahead and/or look-behind points. In an embodiment, as represented in FIG. 9, multiple look-ahead points 520 (corresponding to time t=t1) and 530 (corresponding to time t=t2) for the working tool 146 and the point of interest 148 may be utilized, potentially allowing for more fidelity in the process of deciding upon a trajectory. The working tool at the first look-ahead point 518 and the point of interest at the first look-ahead point 522 are generated based on the current location 516 and the current trajectory of the working tool 146 and the point of interest 148, further in view of the first look-ahead time (t=t1). The working tool at the second look-ahead point 528 and the point of interest at the second look-ahead point 532 are also generated based on the current location and the current trajectory of the working tool 146 and the point of interest 148, further in view of the second look-ahead time (t=t2). In particular, look-ahead points that are further separated from the current location of the point of interest 146 could allow for the determination of slope changes on the surface, a key indicator of an upcoming transition that the control system must handle.

Utilizing the surface normal vectors 534 from various look-ahead points, or in the illustrated embodiment a first surface normal vector 534a corresponding to the point of interest at a first look-ahead 522 and a second surface normal vector 534b corresponding to the point of interest at a second look-ahead point 532, the system can compare slopes of upcoming points along the path of the current trajectory 512. Varying slopes indicated by the surface normal vectors inform the machine control that a transition is upcoming.

In a fifth step 418, this information can be used to manage of one or more trajectory characteristics, for example the magnitude of the trajectory for the point of interest, effectively slowing down the work implement as it approaches a transition, and preferably helping to ensure an accurate cut through the transition.

As further represented in FIG. 10, similar logic can be applied to a look-behind point 540 (corresponding to time t=t−1), whereby the machine control can evaluate the slope of the surfaces that have already been traversed by the working tool at the look-behind point 536. Utilizing the surface normal vector 534o data for the look-behind point serves as an indicator that the point of interest is exiting a transition point.

Similar to the previous scenario, the variance in surface normal vectors 534o from the look-behind point 540 relative to the current location 516 of the point of interest 148 can provide evidence of the change in slope of the surface. This information can be utilized to modify one or more characteristics (e.g., the magnitude) of the implement trajectory, ensuring that the implement pulls away from a surface transition in a controllable manner.

The trajectory magnitude determination driven by surface normal vectors 534 may typically impact the overall velocity of the working tool 146 and/or point of interest 148 entering and exiting a transition point. Because the look-ahead and/or look-behind points are time based, this also impacts the distance of these points relative to the point of interest 148 at the current location 516. This improves the accuracy of the machine control across a transition point because of the “convergence” effect that occurs as the distance magnitude of the look-ahead and/or look-behind points is reduced when controlling around the transition.

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

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