Patent ID: 12209393

DETAILED DESCRIPTION

The present disclosure relates to earthmoving machines and, more particularly, to earthmoving machines such as excavators including components subject to control. For example, and not by way of limitation, many types of excavators typically have a hydraulically controlled earthmoving implement that can be manipulated by a joystick or other means in an operator control station of the machine, and is also subject to partially or fully automated control. The user of the machine may control the lift, tilt, angle, and pitch of the implement. In addition, one or more of these variables may also be subject to partially or fully automated control based on information sensed or received by an adaptive environmental sensor of the machine. In the embodiments described herein, a grade control system is used to determine a value such as a point of perpendicular intersection between a rear curve of an earthmoving implement and a ground surface and operate the earthmoving machine to contact, such as to smooth, the ground surface with the earthmoving implement based on the point of perpendicular intersection, as described in greater detail further below. Such determined values may be utilized by an architecture control to operate the earthmoving machine.

As the earthmoving implement may be used in many different orientations with respect to a ground surface and connection via a linkage to the earthmoving machine, a point of the earthmoving implement contacting the ground surface is dynamically and changing with respect to a geometry of the linkage. The determined values may include determining a focus and vertical guidance point for grade control based on the determined dynamically changing point on the earthmoving implement by creating a vector disposed through a center point of the earthmoving implement and is perpendicular (e.g., normal) to the ground surface (e.g., a design surface). Thus, with such determined values such as the focus and vertical guidance point, a grade control system may maintain an accurate guidance as the earthmoving implement moves over the ground surface through a range of motion and number of linkage positions as achieved by the linkage.

Referring initially toFIG.1, in embodiments, a grade control system107includes an earthmoving machine100, which is shown disposed on a ground surface126. The earthmoving machine100includes a machine chassis102, a linkage assembly104, an earthmoving implement114, and control architecture106. The linkage assembly104includes a boom linkage108, a stick linkage110, the earthmoving implement114, and a four-bar linkage112that collectively define a plurality of linkage assembly positions. The stick linkage110includes a terminal point and is mechanically coupled to a terminal pivot point of the boom linkage108. The machine chassis102is mechanically coupled to an opposing terminal pivot point of the boom linkage108. Thus, the boom linkage108is coupled between the machine chassis102and the stick linkage110, and an end of the stick linkage110is coupled to the earthmoving implement114, such as through the four-bar linkage112.

In embodiments, the linkage assembly104is configured to swing with, or relative to, the machine chassis102, and the stick linkage110is configured to curl relative to the boom linkage108. Further, the earthmoving implement114and the stick linkage110are mechanically coupled to each other, such as through the four-bar linkage112. In embodiments, the four-bar linkage112includes an implement linkage, a rear side linkage, a dogbone linkage, and a front side linkage.

The control architecture106comprises one or more linkage assembly actuators and an architecture controller programmed to execute a control scheme400(FIG.6) as described herein. In embodiments, the control architecture106comprises a non-transitory computer-readable storage medium comprising machine readable instructions. The one or more linkage assembly actuators may facilitate movement of the linkage assembly104. The one or more linkage assembly actuators may comprise a hydraulic cylinder actuator, a pneumatic cylinder actuator, an electrical actuator, a mechanical actuator, or combinations thereof. Blocks402-408of the control scheme400ofFIG.6illustrate the process the architecture controller is programmed to execute, which will be described in greater detail further below.

Referring toFIG.2, an enlarged view of the earthmoving implement114is shown with a superimposed plurality of points122that form a superimposed curve116. The superimposed curve116is representative of a continuous differential surface associated with a rear curved surface of the earthmoving implement114.

Referring toFIG.3, an enlarged view of another embodiment of an earthmoving implement214is shown with superimposed one or more points122and an interior surface218. The point122include superimposed front point222A and superimposed rear point222B, disposed at ends of a generally linear undersurface216of the earthmoving implement216. The outer, generally linear undersurface216faces in an opposite direction from the interior surface218of the earthmoving implement214. Thus, the generally linear undersurface216of the earthmoving implement214depicts a generally non-circular implement surface. For any curvature points, an intersection of a design plane normal n* of a ground surface126(e.g., a target ground surface126for smoothing) that is normal to a piecewise-derivative continuous curve (e.g., such as through a simulated arc) is determined via a process400(FIG.6), which is described in greater detail below. As a non-limiting embodiment, in sections between linear regions, multiple sample points can be added between the adjoining segments to allow for a piecewise continuous derivative linear curve to be generated. For linear regions of the characterization curve of the earthmoving implement214, a point on the front or rear edge of a line segment (e.g., the superimposed front point222A and/or the superimposed rear point222B) may be used with hysteresis to prevent bouncing and reduce error between focus points of the earthmoving implement214used in the process400for the determinations.

Referring toFIG.4, an enlarged view of yet another embodiment of an earthmoving implement314as a circular implement for an earthmoving machine300is shown. The earthmoving machine300is generally similar to the earthmoving machine100except with respect to the earthmoving implement314and a linkage assembly312as described herein. The earthmoving implement314is coupled via a lower linkage of a linkage assembly312to the stick linkage110at a terminal point G. The linkage assembly312includes the lower linkage, an upper linkage connected to the stick linkage110above the terminal point G, and an intermediate linkage disposed an opposite ends of the lower and upper linkages. The intermediate linkage is coupled to the lower linkage at a lower linkage coupling point at an end of the lower linkage opposite of the terminal point G. A distance C is defined between the terminal point G and the lower linkage coupling point. A center point328of the earthmoving implement314is a distance B away from the lower linkage coupling point, and the center points328is a distance A away from the terminal point G. Distances A, B, and C are able to be measured and calibrated to determine a location of a rotary axis of center point328through the earthmoving implement314. A radius D from the center point328to an outer surface of the earthmoving implement314may then be used to determine a position of an outer surface point330of the earthmoving implement with respect to a ground surface126such that the outer surface point330is normal to the ground surface126along vector332of the ground surface126, as shown inFIG.5and described in greater detail below. The outer surface point330is dynamically changing with respect to a point that is normal to a selected portion of the ground surface126. Determination of this dynamically changing point may then be used to control and provide guidance to the earthmoving implement314during a smoothing, compacting, and/or other grading of the ground surface126.

FIG.5depicts a side view of the earthmoving implement314in three separate positions302,304,306with respect to and in contact with a ground surface126. In position302, the earthmoving implement314is disposed against left angled ground surface126A at outer surface point330A such that the outer surface point330A is normal to the ground surface126A along vector332A of the ground surface126. The outer surface point330A is thus representative of a point of perpendicular intersection between the curve of the earthmoving implement314and the ground surface126A along the vector332A projecting from the ground surface126A. The vector332A, which is dynamic, is disposed at an angle α1 with respect to an axis334that is statically disposed between the terminal point G of the stick linkage110and the center point328of the earthmoving implement314.

In position304, the earthmoving implement314is disposed against an underlying ground surface126B at outer surface point330B such that the outer surface point330B is normal to the ground surface126B along vector332B of the ground surface126B. The outer surface point330B is thus representative of a point of perpendicular intersection between the curve of the earthmoving implement314and the ground surface126B along the vector332B projecting from the ground surface126B. The dynamic vector332B is disposed at an angle α2 with respect to the static axis334.

In position306, the earthmoving implement314is disposed against right angled ground surface126C at outer surface point330C such that the outer surface point330C is normal to the ground surface126C along vector332C of the ground surface126C. The outer surface point330C is thus representative of a point of perpendicular intersection between the curve of the earthmoving implement314and the ground surface126C along the vector332C projecting from the ground surface126C. The dynamic vector332C is disposed at an angle α3 with respect to the static axis334. In the non-limiting, illustrated embodiments ofFIG.5, the angles α1, α2, and α3 are different with respect to one another as the respective outer surface points330A, B, C dynamically change and are determined with respect to respective vectors332A, B, C of respective ground surfaces126A,126B,126C.

Referring again toFIG.6, blocks402-408of the control scheme400illustrate the process the architecture controller of the control architecture106is programmed to execute. The process is executed by the architecture controller to determine a point of perpendicular intersection between an excavating implement114,214,314and a ground surface126as described herein.

In block402, the architecture controller is programmed to generate a continuous differential surface (e.g., such as the superimposed curve116ofFIG.2) associated with a rear curved surface of the earthmoving implement114,214,314, and to project the continuous differential surface onto a two-dimensional (2D) plane (such as an XY plane including an x-axis and a y-axis) associated with the earthmoving implement114,214,314. As described herein with respect toFIGS.1-2and4, the linkage assembly112,312of the earthmoving implement114,214,314may include the boom linkage108and the stick linkage110, each including a centerline. The 2D plane associated with the earthmoving implement114,214,314may pass through each centerline of the boom linkage108and the stick linkage110. The boom linkage108may be coupled between the machine chassis102and the stick linkage110, and an end of the stick linkage110may be coupled to the earthmoving implement114,214,314, via the linkage assembly112,312.

In embodiments, to generate the continuous differential surface associated with the rear curved surface of the earthmoving implement114ofFIG.2, the architecture controller may be configured to locate a flat surface of a bottom of the earthmoving implement114, locate a ground surface point of the ground surface126(FIG.1), and position an initial curvature point (e.g., corresponding to point A) as one of one or more curvature points of a curvature of the earthmoving implement114extending from the flat surface onto the ground surface point of the ground surface126. The one or more linkage assembly actuators may be used to lift and curl the earthmoving implement114to a subsequent curvature point (such as corresponding to point B) of the earthmoving implement114and to position the subsequent curvature point (e.g., corresponding to point B) onto the ground surface point126. The subsequent curvature point is one of the one or more curvature points (e.g., corresponding to points A-F ofFIG.2). Further subsequent curvature points may continue to be located and positioned, each as one of the one or more curvature points, on the curvature of the earthmoving implement114on the ground surface point126.

The one or more points (e.g., points A-F) of the rear curved surface of the excavating implement114may be mapped based on the one or more curvature points located and positioned on the ground surface126. The one or more points (e.g., points A-F) mapping the rear curved surface of the earthmoving implement114may then be projected onto the 2D plane of the earthmoving implement114. The continuous differential surface (e.g., the superimposed curve116ofFIG.2) associated with the rear curved surface of the earthmoving implement114may be generated based on the one or more points projected onto the 2D plane (e.g., the superimposed points122associated with points A-F ofFIG.2). A y-axis of the 2D plane may be defined by a vector disposed between the initial curvature point of the one or more curvature points and a final curvature point of the one or more curvature points. The one or more curvature points may include at least five curvature points (e.g., corresponding to points B-F), and the continuous differential surface may be mapped with a tangential line that starts on the flat surface of the bottom of the earthmoving implement114(e.g., starting at point A).

In embodiments in which the one or more curvature points are not strictly monotonically increasing, the earthmoving implement114may be bisected to create a bisection lane. Two separate projections may then be created for the one or more curvature points respectively below and above the bisection lane. The continuous differential surface may be generated based on the one or more curvature points respectively below and above the bisection lane.

In an aspect, the architecture controller may be configured to project k measured-up points associated with the rear curved surface of the earthmoving implement114,214,314onto the 2D plane. A y-axis of the 2D plane may then be defined as going from a first to a last of the k measured-up points, and the projected k measured-up points may be denoted as xkand f(xk) with respect an x-axis.

In block404, the architecture controller is programmed to determine a piecewise-derivative continuous curve based on the continuous differential surface projected on to the 2D plane, and to determine a derivative of the piecewise-derivative continuous curve. To determine the piecewise-derivative continuous curve based on the continuous differential surface projected on to the 2D plane, the architecture controller may be configured to determine a smooth piecewise cubic function p(x)∈1[I] that is differentiable with a single continuous derivative characterizing one or more points x defining the continuous differential surface projected on to the 2D plane. The smooth piecewise cubic function in each subinterval Ii[xi, xi+1] is given by
p(x)=fiH1(x)+fi+1H2(x)+diH3(x)+di+1H4(x),  (Equation 1)where H1(x)=φ((xi+1−x)/hi), H2(x)=φ((x−xi)/hi), H3(x)=−hiψ((xi+1−x)/hi), H4(x)=hiψ(x−xi)/hi), andwhere hi=xi+1−xi, φ(t)=3t2−2t3, and ψ(t)=t3−t2.

To determine the derivative of the piecewise-derivative continuous curve, the architecture controller may be configured to differentiate the piecewise-derivative continuous curve to determine the following:

∂∂xd⁢p⁡(x)=fi⁢∂∂xH1(x)+fi+1⁢∂∂xH2(x)+di⁢∂∂xH3(x)+di+1⁢∂∂xH4(x),(Equation⁢2)where⁢∂∂xH1(x)=1hi⁢(6⁢((xi+1-x)hi)2-6⁢((xi+1-x)hi)),∂∂xH2(x)=1hi⁢(6⁢((x-xi)hi)-6⁢((x-xi)hi)2),∂∂xH3(x)=3⁢(xi+1-xhi)2-2⁢(xi+1-xhi),∂∂xH4(x)=3⁢(x-xihi)2-2⁢(x-xihi).

In block406, the architecture controller is programmed to project a vector as a design plane normal n* (such as vectors332,332A,332B, and332C ofFIGS.4-5) of a ground surface126for smoothing onto the 2D plane associated with the earthmoving implement114,214,314. In block408, the architecture controller is programmed to determine a point of perpendicular intersection (such as at outer surface point330,330A,330B, and330B ofFIGS.4-5) between the derivative of the piecewise-derivative continuous curve and the design plane normal n* (such as vectors332,332A,332B, and332C ofFIGS.4-5) of the respective ground surface126projected onto the 2D plane. In embodiments, the architecture controller may further be programmed to operate the earthmoving machine100,300using the one or more linkage assembly actuators and the determined and dynamically changing point of perpendicular intersection to smooth the ground surface126.

To determine the point of perpendicular intersection between the derivative of the piecewise-derivative continuous curve and the design plane normal n* of the ground surface projected onto the 2D plane, the architecture controller may be configured to iterate over the regions from i=0 to i=n−1 and find the point of perpendicular intersection between the derivate

∂∂xdp⁡(x)
and the design plane normal n* as defined by when

∂∂xd⁢p⁡(x)=-nx*ny*.

In embodiments, when at least two points or zero points of perpendicular intersection are found, the point of perpendicular intersection selected may be a point nearest to an origin of the design plane normal n* of the ground surface126. When at least two points are equidistant from the origin, the point of perpendicular intersection selected may be a point of the equidistant points that is furthest along a direction of travel of the earthmoving implement

It is contemplated that the embodiments of the present disclosure may assist to permit a speedy and more cost efficient method of determining values to aid in grade control of a ground surface, and methods to operate an earthmoving implement based on such determined values, in a manner that minimizes a risk of human error with such value determinations. Further, the controller of the excavator or other control technologies are improved such that the processing systems are improved and optimized with respect to speed, efficiency, and output.

A signal may be “generated” by direct or indirect calculation or measurement, with or without the aid of a sensor.

For the purposes of describing and defining the present disclosure, it is noted that reference herein to a variable being a “function” of a parameter or another variable is not intended to denote that the variable is exclusively a function of the listed parameter or variable. Rather, reference herein to a variable that is a “function” of a listed parameter is intended to be open ended such that the variable may be a function of a single parameter or a plurality of parameters.

It is also noted that recitations herein of “at least one” component, element, etc., should not be used to create an inference that the alternative use of the articles “a” or “an” should be limited to a single component, element, etc.

It is noted that recitations herein of a component of the present disclosure being “configured” or “programmed” in a particular way, to embody a particular property, or to function in a particular manner, are structural recitations, as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is “configured” or “programmed” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.

It is noted that terms like “preferably,” “commonly,” and “typically,” when utilized herein, are not utilized to limit the scope of the claimed disclosure or to imply that certain features are critical, essential, or even important to the structure or function of the claimed disclosure. Rather, these terms are merely intended to identify particular aspects of an embodiment of the present disclosure or to emphasize alternative or additional features that may or may not be utilized in a particular embodiment of the present disclosure.

For the purposes of describing and defining the present disclosure it is noted that the terms “substantially” and “approximately” are utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The terms “substantially” and “approximately” are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

Having described the subject matter of the present disclosure in detail and by reference to specific embodiments thereof, it is noted that the various details disclosed herein should not be taken to imply that these details relate to elements that are essential components of the various embodiments described herein, even in cases where a particular element is illustrated in each of the drawings that accompany the present description. Further, it will be apparent that modifications and variations are possible without departing from the scope of the present disclosure, including, but not limited to, embodiments defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.

It is noted that one or more of the following claims utilize the term “wherein” as a transitional phrase. For the purposes of defining the present disclosure, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.”