Patent Publication Number: US-11028555-B2

Title: Implement teeth grading offset determination

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is a continuation of U.S. patent application Ser. No. 15/846,919, filed Dec. 19, 2017, entitled “EXCAVATOR IMPLEMENT TEETH GRADING OFFSET DETERMINATION,” the entirety of which is incorporated by reference. 
    
    
     BACKGROUND 
     The present disclosure relates to excavators which, for the purposes of defining and describing the scope of the present application, comprise an excavator boom and an excavator stick subject to swing and curl, and an excavating implement that is subject to swing and curl control with the aid of the excavator boom and excavator stick, or other similar components for executing swing and curl movement. For example, and not by way of limitation, many types of excavators comprise a hydraulically or pneumatically or electrically controlled excavating implement that can be manipulated by controlling the swing and curl functions of an excavating linkage assembly of the excavator. Excavator technology is, for example, well represented by the disclosures of U.S. Pat. No. 8,689,471, which is assigned to Caterpillar Trimble Control Technologies LLC and discloses methodology for sensor-based automatic control of an excavator, US 2008/0047170, which is assigned to Caterpillar Trimble Control Technologies LLC and discloses an excavator 3D laser system and radio positioning guidance system configured to guide a cutting edge of an excavator bucket with high vertical accuracy, and US 2008/0000111, which is assigned to Caterpillar Trimble Control Technologies LLC and discloses methodology for an excavator control system to determine an orientation of an excavator sitting on a sloped site. 
     BRIEF SUMMARY 
     According to the subject matter of the present disclosure, an earthmoving machine comprising an earthmoving implement, and control architecture. The earthmoving implement defines a variable implement angle θ Bucket (t) that is indicative of a current position of the earthmoving implement relative to horizontal as a function of time t. The earthmoving implement comprises a plurality of implement teeth extending a tooth height h and defining an active raking ratio r. The control architecture comprises one or more linkage assembly actuators and one or more architecture controllers programmed to execute an implement teeth grading offset determination process. The implement teeth grading offset determination process comprises determining a variable implement offset angle θ Delta (t) at least partially based on a difference between an original target design angle θ Tgt (t) and the variable implement angle θ Bucket (t), the original target design angle θ Tgt (t) indicative of a target implement slope relative to horizontal as a function of time t, determining an implement offset IO based on the tooth height h, the active raking ratio r, and the variable implement offset angle θ Delta (t), and determining a new target design elevation Elv Tgt,New (t) based on the implement offset IO and an original target design elevation Elv Tgt,Orig (t). The one or more architecture controllers are further programmed to operate the earthmoving machine to grade a terrain using the plurality of implement teeth at least partially based on the new target design elevation Elv Tgt,New (t). 
     According to one embodiment of the present disclosure, a method of operating an earthmoving machine to grade a terrain comprising defining a variable implement angle θ Bucket (t) of an earthmoving implement of the earthmoving machine that is indicative of a current position of the earthmoving implement relative to horizontal as a function of time t, the earthmoving implement comprising a plurality of implement teeth extending a tooth height h and defining an active raking ratio r; determining a variable implement offset angle θ Delta (t) at least partially based on a difference between an original target design angle θ Tgt (t) and the variable implement angle θ Bucket (t), the original target design angle θ Tgt (t) indicative of a target implement slope relative to horizontal as a function of time t; determining an implement offset IO based on the tooth height h, the active raking ratio r, and the variable implement offset angle θ Delta (t); determining a new target design elevation Elv Tgt,New (t) based on the implement offset IO and an original target design elevation Elv Tgt,Orig (t); and operating the earthmoving machine to grade the terrain using the plurality of implement teeth at least partially based on the new target design elevation Elv Tgt,New (t). 
     Although the concepts of the present disclosure are described herein with primary reference to the excavator illustrated in  FIG. 1 , it is contemplated that the concepts will enjoy applicability to any type of excavator or construction machine type, regardless of its particular mechanical configuration. For example, and not by way of limitation, the concepts may enjoy applicability to a backhoe loader including a backhoe linkage. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which: 
         FIG. 1  is a side view of an excavator incorporating aspects of the present disclosure; 
         FIG. 2  is a perspective view of a dynamic sensor disposed on a linkage of the excavator of  FIG. 1  and according to various concepts of the present disclosure; 
         FIG. 3  is a side elevation view of an excavating implement of the excavator of  FIG. 1  in a tooth grading position, according to various concepts of the present disclosure; 
         FIG. 4  is a side elevation view of a plurality of teeth of the excavating implement of the excavator of  FIG. 1 , according to various concepts of the present disclosure; 
         FIG. 5  is another side elevation view of an alternative plurality of teeth of the excavating implement of the excavator of  FIG. 1 , according to various concepts of the present disclosure; and 
         FIG. 6  is a flow chart of a process used to determine an implement teeth grading offset for use by the excavator of  FIG. 1 . 
     
    
    
     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 a dynamic sensor of the machine. 
     In the embodiments described herein, an excavator  100  includes control architecture that includes one or more linkage assembly actuators and one or more architecture controllers programmed to execute an implement teeth grading offset determination process. As described in greater detail further below, the implement teeth grading offset determination process may be executed to determine a new target design elevation Elv Tgt,New (t) as a grading setting when a plurality of implement teeth  130  are closer to a terrain than a rear implement point Q of an excavating implement  114  such that the plurality of implement teeth  130  are configured to be used for grading the terrain. However, when the plurality of implement teeth  130  are farther from the terrain than the rear implement point Q such that a rear implement edge is configured to be used for grading the terrain, an original target design elevation Elv Tgt,Orig (t) may be utilized as a grading setting. 
     Referring initially to  FIG. 1 , an excavator  100  includes a machine chassis  102 , an excavating linkage assembly  104 , an excavating implement  114 , and control architecture  106 . The excavating linkage assembly  104  is configured to move or swing with, or relative to, the machine chassis  102 . The excavating linkage assembly  104  includes an excavator boom  108  and an excavator stick  110 . The excavating implement  114  is mechanically coupled to a terminal point of the excavator stick  110  and is configured to curl relative to the excavator stick  110 . In embodiments, the excavating implement  114  is mechanically coupled through a coupling  112  to the terminal point of the excavator stick  110 . The excavator boom  108 , the excavator stick  110 , and the excavating implement  114  collectively define a variable implement angle θ Bucket (t) that is indicative of a current position of the excavating implement  114  relative to horizontal as a function of time t. 
     Referring to  FIGS. 1, 3, and 4-5 , the excavating implement  114  comprises a plurality of implement teeth  130  extending a tooth height h from an internal leading edge J I  of the excavating implement to an external leading edge J E  of the excavating implement  114 . The implement teeth are spaced along the internal leading edge J I  and define an active raking ratio r. The active raking ratio r is representative of a portion of the area between the internal leading edge J I  of the excavating implement and the external leading edge J E  of the excavating implement that is occupied by the collective surfaces of implement teeth  130 . For example, an active raking ratio of 1.0 indicates that equal portions of the area between the internal leading edge J I  of the excavating implement  114  and the external leading edge J E  of the excavating implement  114  are occupied by the implement teeth  130  and spaces  132  between the implement teeth. Higher active raking ratios may represent wider and/or more narrowly spaced teeth, while lower active raking ratios may represent narrower and/or more widely spaced teeth. 
     In embodiments, the implement dynamic sensor  120  comprises an inertial measurement unit (IMU), an inclinometer, an accelerometer, a gyroscope, an angular rate sensor, a rotary position sensor, a position sensing cylinder, or combinations thereof. The IMU may include a 3-axis accelerometer and a 3-axis gyroscope. As shown in  FIG. 2 , the implement dynamic sensor  120  includes accelerations A x , A y , and A z , respectively representing x-axis, y-axis-, and z-axis acceleration values. 
     The control architecture  106  includes one or more linkage assembly actuators and one or more architecture controllers programmed to execute an implement teeth grading offset determination process. In embodiments, the control architecture comprises a non-transitory computer-readable storage medium comprising machine readable instructions that the one or more architecture controllers are programmed to execute. The one or more linkage assembly actuators may facilitate movement of the excavating linkage assembly  104 . Further, 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. 
     The implement teeth grading offset determination process is illustrated in  FIG. 6  through a control scheme  200  and steps  202 - 206 . The implement teeth grading offset determination process includes determining in step  202  a variable implement offset angle θ Delta (t) at least partially based on a difference between an original target design angle θ Tgt (t) and the variable implement angle θ Bucket (t). The original target design angle θ Tgt (t) is indicative of a target implement slope relative to horizontal as a function of time t. Further, an implement offset IO ( FIG. 5 ) is determined in step  204  based on the tooth height h, the active raking ratio r, and the variable implement offset angle θ Delta (t). In step  206 , a new target design elevation Elv Tgt,New (t) is determined based on the implement offset IO and the original target design elevation Elv Tgt,Orig (t). 
     The one or more architecture controller are further programmed to operate the excavator  100  to grade a terrain, such as of a ground  126 , using the plurality of implement teeth  130  at least partially based on the new target design elevation Elv Tgt,New (t). In embodiments, the excavating implement  114  includes a rear implement point Q. The one or more architecture controllers are programmed to execute the implement teeth grading offset determination process when the excavating implement  114  is curled to bring the plurality of implement teeth  130  closer to the terrain than the rear implement point Q such that the plurality of implement teeth  130  are configured to be used for grading the terrain, such as the ground  126 . The one or more architecture controllers are further programmed to return to the original target design elevation Elv Tgt,Orig (t) as a grading setting when the excavating implement  114  is curled to bring the rear implement point Q closer to the terrain than the plurality of implement teeth  130  such that the rear implement point Q is configured to be used for grading the terrain, such as the ground  126 . 
     Referring to  FIGS. 3-5 , a tooth axis P intersects a bottom edge point of the excavating implement  114  and a coaxially aligned point on a tooth  130 A of the plurality of implement teeth  130  at the external leading edge J E  of the excavating implement  114 . The variable implement angle θ Bucket (t) is indicative of the current position of the excavating implement  114  relative to horizontal and with respect to the tooth axis P. Further, the original target design angle θ Tgt (t) is indicative of the target implement slope relative to horizontal and with respect to the tooth axis P. 
     In embodiments, the plurality of implement teeth  130  include uniform teeth heights. Alternatively, the plurality of implement teeth  130  include variable teeth heights such that the tooth height h may defined by an average of the variable teeth heights or may defined by a common tooth height. The common tooth height is defined by a majority height of the plurality of implement teeth  130 . 
     Referring to  FIG. 4 , the plurality of implement teeth  130  may include straight edge teeth. Each tooth  130 A may include a tooth width w 1 , and each space  132 A between the plurality of implement teeth  130  may include comprises an air space width w 2 . The active raking ratio r may be defined by a following equation: 
     
       
         
           
             r 
             = 
             
               
                 5 
                 ⁢ 
                 
                   w 
                   2 
                 
               
               
                 6 
                 ⁢ 
                 
                   w 
                   1 
                 
               
             
           
         
       
     
     In an embodiment in which there are X number of teeth and Y number of air spaces between the teeth, the active ratio r may be defined by a following equation: 
     
       
         
           
             r 
             = 
             
               
                 Y 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 
                   w 
                   2 
                 
               
               
                 X 
                 ⁢ 
                 
                     
                 
                 ⁢ 
                 
                   w 
                   1 
                 
               
             
           
         
       
     
     Alternatively, referring to  FIG. 5 , the plurality of implement teeth  130  may include one or more angled teeth, one or more non-uniform shaped teeth, or combinations thereof. The active raking ratio r may then at least be partially based on an average width of the plurality of implement teeth  130  and an average width of spaces  132  between the plurality of implement teeth  130 . 
     In embodiments, the implement offset is determined based on a following equation:
 
 h*r *sin θ Delta ( t )
 
     Further, the new target design elevation Elv Tgt,New (t) is defined by a following equation:
 
 Elv   Tgt,New ( t )= Elv   Tgt,Orig ( t )+ h*r *sin θ Delta ( t )
 
     The variable implement offset angle θ Delta (t) may be in a range of from about 0 degrees to about 180 degrees. However, when the variable implement offset angle θ Delta (t) is outside a range of from about 0 degrees to about 180 degrees, sin θ Delta (t) may be set to zero. This setting may avoid a negative implement offset IO, for example. In embodiments, the implement offset IO is in a range that is a function of teeth height and/or length. As a non-limiting example, the teeth length may be longer than 10 inches. As an example and not a limitation, in embodiments, the implement offset IO is in a range of from about 0.5 inches to about 3 inches. 
     It is contemplated that the embodiments of the present disclosure may assist to permit a speedy and more cost efficient method of determining grade plane signals and/or offsets 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 invention, 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 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. 
     For the purposes of describing and defining the present invention it is noted that the terms “substantially” and “approximately” and “about” 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” and “about” 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 invention, 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.”