Patent Publication Number: US-10774506-B2

Title: System and method for controlling the operation of a machine

Description:
TECHNICAL FIELD 
     This disclosure relates generally to controlling a machine and, more particularly, to a system and method for analyzing elevation differences between adjacent slots in a work surface and providing the elevation differences exceeding one or more thresholds. 
     BACKGROUND 
     Machines such as dozers, motor graders, wheel loaders, etc., are used to perform a variety of tasks. For example, these machines may be used to move material at a work site. The machines may operate in an autonomous, semi-autonomous, or manual manner to perform these tasks in response to commands generated as part of a work plan for the machines. The machines may receive instructions in accordance with the work plan to perform operations including digging, loosening, carrying, etc., different materials at the work site such as those related to mining, earthmoving and other industrial activities. 
     Autonomously operated machines may remain consistently productive without regard to a human operator or environmental conditions. In addition, autonomous systems may permit operation in environments that are unsuitable or undesirable for a human operator. Autonomous or semi-autonomous systems may also compensate for inexperienced human operators as well as inefficiencies associated with repetitive tasks. 
     When performing slot dozing operations, adjacent slots may have lower surfaces at substantially different heights. Accordingly, if a machine does not accurately follow the path of its slot and begins to enter an adjacent slot, the machine may pass through the berm between slots and tip over or contact the berm and become buried in material. The risk of either scenario increases when the machine is operating in an autonomous or semi-autonomous manner. 
     U.S. Pat. No. 9,783,955 discloses a system for moving material with a machine utilizing two different types of material moving operations. The first material moving operation is used to fill a void to a predetermined extent and the second material moving operation is used after the void is filled to the predetermined extent. 
     The foregoing background discussion is intended solely to aid the reader. It is not intended to limit the innovations described herein, nor to limit or expand the prior art discussed. Thus, the foregoing discussion should not be taken to indicate that any particular element of a prior system is unsuitable for use with the innovations described herein, nor is it intended to indicate that any element is essential in implementing the innovations described herein. The implementations and application of the innovations described herein are defined by the appended claims. 
     SUMMARY 
     In one aspect, a system for moving material with a machine at a work site with a ground engaging work implement along a path from a first work area to a dump location includes a position sensor and a controller. The position sensor is configured to generate position signals indicative of a position of a work surface. The controller is configured to receive position signals from the position sensor, determine a topography of the work surface based upon the position signals, determine a maximum cutting capacity for a cutting operation between the work surface and a target surface beneath the work surface, and determine a maximum carrying capacity for a carrying operation along a carry surface from an end of a loading profile to the dump location. The controller is further configured to determine a first double cut location of a double cut operation along the work surface based upon the maximum carrying capacity and the topography of the work surface, with the first double cut location, the topography, and a first loading profile defining a first double cut amount of material to be moved and determine a second double cut location of the double cut operation based upon the maximum carrying capacity and a modified topography of the work surface, the modified topography of the work surface being based upon the first double cut location and the topography of the work surface, with the second double cut location, the modified topography, and a second loading profile defining a second double cut amount of material to be moved, and each of the first double cut amount of material and the second double cut amount of material is less than the maximum cutting capacity between the work surface and the target surface, and the first double cut amount of material plus the second double cut amount of material is less than the maximum carrying capacity along the carry surface. The controller is also configured to generate a first forward command to move the ground engaging work implement along the path and the first loading profile from the first double cut location and only partway towards the dump location to an intermediate position between the first double cut location and the dump location to move the first double cut amount of material to the intermediate position, generate a first reverse command to move the machine along the path to align the ground engaging work implement with the second double cut location, and generate a second forward command to move the ground engaging work implement along the path and the second loading profile from the second double cut location to the dump location to move the first double cut amount of material and the second double cut amount of material to the dump location. 
     In another aspect, a method is provided for moving material with a machine at a work site with a ground engaging work implement wherein the machine moves on a work surface along a path from a first work area to a dump location. The method includes receiving position signals from a position sensor, determining a topography of the work surface based upon the position signals, determining a maximum cutting capacity for a cutting operation between the work surface and a target surface beneath the work surface, and determining a maximum carrying capacity for a carrying operation along a carry surface from an end of a loading profile to the dump location. The method further includes determining a first double cut location of a double cut operation along the work surface based upon the maximum carrying capacity and the topography of the work surface, with the first double cut location, the topography, and a first loading profile defining a first double cut amount of material to be moved, determining a second double cut location of the double cut operation based upon the maximum carrying capacity and a modified topography of the work surface, the modified topography of the work surface being based upon the first double cut location and the topography of the work surface, with the second double cut location, the modified topography, and a second loading profile defining a second double cut amount of material to be moved, and each of the first double cut amount of material and the second double cut amount of material being less than the maximum cutting capacity between the work surface and the target surface, and the first double cut amount of material plus the second double cut amount of material being less than the maximum carrying capacity along the carry surface. The method also includes generating a first forward command to move the ground engaging work implement along the path and the first loading profile from the first double cut location and only partway towards the dump location to an intermediate position between the first double cut location and the dump location to move the first double cut amount of material to the intermediate position, generating a first reverse command to move the machine along the path to align the ground engaging work implement with the second double cut location, and generating a second forward command to move the ground engaging work implement along the path and the second loading profile from the second double cut location to the dump location to move the first double cut amount of material and the second double cut amount of material to the dump location. 
     In still another aspect, a machine includes a prime mover, a ground-engaging work implement for engaging a work surface along a path, a position sensor, and a controller. The position sensor is configured to generate position signals indicative of a position of a work surface. The controller is configured to receive position signals from the position sensor, determine a topography of the work surface based upon the position signals, determine a maximum cutting capacity for a cutting operation between the work surface and a target surface beneath the work surface, and determine a maximum carrying capacity for a carrying operation along a carry surface from an end of a loading profile to the dump location. The controller is further configured to determine a first double cut location of a double cut operation along the work surface based upon the maximum carrying capacity and the topography of the work surface, with the first double cut location, the topography, and a first loading profile defining a first double cut amount of material to be moved and determine a second double cut location of the double cut operation based upon the maximum carrying capacity and a modified topography of the work surface, the modified topography of the work surface being based upon the first double cut location and the topography of the work surface, with the second double cut location, the modified topography, and a second loading profile defining a second double cut amount of material to be moved, and each of the first double cut amount of material and the second double cut amount of material is less than the maximum cutting capacity between the work surface and the target surface, and the first double cut amount of material plus the second double cut amount of material is less than the maximum carrying capacity along the carry surface. The controller is also configured to generate a first forward command to move the ground engaging work implement along the path and the first loading profile from the first double cut location and only partway towards the dump location to an intermediate position between the first double cut location and the dump location to move the first double cut amount of material to the intermediate position, generate a first reverse command to move the machine along the path to align the ground engaging work implement with the second double cut location, and generate a second forward command to move the ground engaging work implement along the path and the second loading profile from the second double cut location to the dump location to move the first double cut amount of material and the second double cut amount of material to the dump location. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts a schematic view of a work site at which a machine incorporating the principles disclosed herein may be used; 
         FIG. 2  depicts a diagrammatic illustration of a machine in accordance with the disclosure; 
         FIG. 3  depicts a diagrammatic cross-section of a portion of a work site illustrating various aspects of a material moving plan; 
         FIG. 4  depicts a diagrammatic cross-section of a portion of a work site illustrating a potential target profile; 
         FIG. 5  depicts an enlarged diagrammatic cross-section of a portion of a work site illustrating the result of a plurality of tip head operations; 
         FIG. 6  depicts an enlarged diagrammatic cross-section of a portion of a work site illustrating the result of a plurality of backstacking operations; 
         FIG. 7  depicts a diagrammatic cross-section of a portion of a work site illustrating a single cut operation; 
         FIG. 8  depicts a diagrammatic cross-section of a portion of a work site illustrating a first phase of a double cut operation; 
         FIG. 9  depicts a diagrammatic cross-section of a portion of a work site illustrating a second phase of a double cut operation; and 
         FIG. 10  depicts a flowchart illustrating a material moving process in accordance with the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts a diagrammatic illustration of a work site  100  at which one or more machines  10  may operate in an autonomous, a semi-autonomous, or a manual manner. Work site  100  may be a portion of a mining site, a landfill, a quarry, a construction site, or any other area in which movement of material is desired. Tasks associated with moving material may include a dozing operation, a grading operation, a leveling operation, a bulk material removal operation, or any other type of operation that results in the alteration of the existing topography at work site  100 . As depicted, work site  100  includes a first work area  101  having a high wall  102  at one end and a crest  103  such as an edge of a ridge, embankment, or other change in elevation at an opposite end. Material is moved generally from the high wall  102  towards the crest  103 . The work surface  104  of the work area  101  may take any form and refers to the actual profile or position of the terrain of the work area. A second work area  101  is depicted at an angle to the first work area. 
     As used herein, a machine  10  operating in an autonomous manner operates automatically based upon information received from various sensors without the need for human operator input. As an example, a haul or load truck that automatically follows a path from one location to another and dumps a load at an end point may be operating autonomously. A machine operating semi-autonomously includes an operator, either within the machine or remotely, who performs some tasks or provides some input and other tasks are performed automatically and may be based upon information received from various sensors. As an example, a load truck that automatically follows a path from one location to another but relies upon an operator command to dump a load may be operating semi-autonomously. In another example of a semi-autonomous operation, an operator may dump a bucket of an excavator in a load truck and a controller may automatically return the bucket to a position to perform another digging operation. A machine being operated manually is one in which an operator is controlling all or essentially all of the functions of the machine. A machine may be operated remotely by an operator (i.e., remote control) in either a manual or semi-autonomous manner. In some operations, a plurality of machines  10  may be configured to be operated autonomously or semi-autonomously and one or more operators responsible for overseeing the operation of the machines. At times, an operator may manually take over responsibility for the operation of one or more of the machines. 
       FIG. 2  depicts a diagrammatic illustration of a machine  10  such as a dozer with a ground-engaging work implement such as a blade  16  configured to push material. The machine  10  includes a frame  12  and a prime mover such as an engine  13 . A ground-engaging drive mechanism such as a track  15  may be driven by a drive sprocket  14  on opposite sides of machine  10  to propel the machine. Although machine  10  is shown in a “track-type” configuration, other configurations, such as a wheeled configuration, may be used. Operation of the engine  13  and a transmission (not shown), which are operatively connected to the drive sprockets  14  and tracks  15 , may be controlled by a control system  35  including a controller  36 . The systems and methods of the disclosure may be used with any machine propulsion and drivetrain mechanisms applicable in the art for causing movement of the machine including hydrostatic, electric, or mechanical drives. 
     Blade  16  may be pivotally connected to frame  12  by arms  18  on each side of machine  10 . First hydraulic cylinder  21  coupled to frame  12  supports blade  16  in the vertical direction and allows blade  16  to move up or down vertically from the point of view of  FIG. 2 . Second hydraulic cylinders  22  on each side of machine  10  allow the pitch angle of blade tip  23  to change relative to a centerline of the machine. 
     Machine  10  may include a cab  24  that an operator may physically occupy and provide input to control the machine. Cab  24  may include one or more input devices such as joystick  25  through which the operator may issue commands to control the propulsion system and steering system of the machine as well as operate various implements associated with the machine. 
     Machine  10  may be controlled by a control system  35  as shown generally by an arrow in  FIG. 2  indicating association with the machine  10 . The control system  35  may include an electronic control module or controller  36  and a plurality of sensors. The controller  36  may receive input signals from an operator operating the machine  10  from within cab  24  or off-board the machine through a wireless communications system  129 . The controller  36  may control the operation of various aspects of the machine  10  including the drivetrain and the hydraulic systems. 
     The controller  36  may be an electronic controller that operates in a logical fashion to perform operations, execute control algorithms, store and retrieve data and other desired operations. The controller  36  may include or access memory, secondary storage devices, processors, and any other components for running an application. The memory and secondary storage devices may be in the form of read-only memory (ROM) or random access memory (RAM) or integrated circuitry that is accessible by the controller. Various other circuits may be associated with the controller  36  such as power supply circuitry, signal conditioning circuitry, driver circuitry, and other types of circuitry. 
     The controller  36  may be a single controller or may include more than one controller disposed to control various functions and/or features of the machine  10 . The term “controller” is meant to be used in its broadest sense to include one or more controllers and/or microprocessors that may be associated with the machine  10  and that may cooperate in controlling various functions and operations of the machine. The functionality of the controller  36  may be implemented in hardware and/or software without regard to the functionality. The controller  36  may rely on one or more data maps relating to the operating conditions and the operating environment of the machine  10  and the work site  100  that may be stored in the memory of controller. Each of these data maps may include a collection of data in the form of tables, graphs, and/or equations. 
     The control system  35  and the controller  36  may be located on the machine  10  and may also include components located remotely from the machine such as at a command center  128  ( FIG. 1 ). The functionality of control system  35  may be distributed so that certain functions are performed at machine  10  and other functions are performed remotely. In such case, the control system  35  may include a communications system such as wireless communications system  129  for transmitting signals between the machine  10  and a system located remote from the machine. 
     Machine  10  may be configured to be operated autonomously, semi-autonomously, or manually. When operating semi-autonomously or manually, the machine  10  may be operated by remote control and/or by an operator physically located within the cab  24 . 
     Machine  10  may be equipped with a plurality of machine sensors  26 , as shown generally by an arrow in  FIG. 2  indicating association with the machine  10 , that provide data indicative (directly or indirectly) of various operating parameters of the machine and/or the operating environment in which the machine is operating. The term “sensor” is meant to be used in its broadest sense to include one or more sensors and related components that may be associated with the machine  10  and that may cooperate to sense various functions, operations, and operating characteristics of the machine and/or aspects of the environment in which the machine is operating. 
     A machine position sensing system  27 , as shown generally by an arrow in  FIG. 2  indicating association with the machine  10 , may include a machine position sensor  28 , also shown generally by an arrow in  FIG. 2  to indicate association with the machine, to sense the position and orientation (i.e., the heading, pitch, roll or tilt, and yaw) of the machine relative to the work site  100 . The position and orientation of the machine  10  are sometimes collectively referred to as the position of the machine. The machine position sensor  28  may include a plurality of individual sensors that cooperate to generate and provide a plurality of machine position signals to controller  36  indicative of the position and orientation of the machine  10 . In one example, the machine position sensor  28  may include one or more sensors that interact with a positioning system such as a global navigation satellite system or a global positioning system to operate as a position sensor. In another example, the machine position sensor  28  may further include a slope or inclination sensor such as pitch angle sensor for measuring the slope or inclination of the machine  10  relative to a ground or earth reference. The controller  36  may use machine position signals from the machine position sensors  28  to determine the position of the machine  10  within work site  100 . In other examples, the machine position sensor  28  may include an odometer or another wheel rotation sensing sensor, a perception based system, or may use other systems such as lasers, sonar, or radar to determine all or some aspects of the position of machine  10 . 
     In some embodiments, the machine position sensing system  27  may include a separate orientation sensing system. In other words, a position sensing system may be provided for determining the position of the machine  10  and a separate orientation sensing system may be provided for determining the orientation of the machine. 
     If desired, the machine position sensing system  27  may also be used to determine a ground speed of machine  10 . Other sensors or a dedicated ground speed sensor may alternatively be used to determine the ground speed of the machine  10 . 
     In addition, the machine position sensing system  27  may also be used to determine the elevation or topography of the work surface upon which the machine  10  is moving. More specifically, based upon known dimensions of the machine  10  and the elevation of the machine at the work site  100 , the elevation or topography of the work surface may also be determined. As a result, the machine position sensing system  27  may operate as either or both of a machine position sensing system and a work surface elevation or topography sensing system. Similarly, the machine position sensor  28  may operate as either or both of a machine position sensor and a work surface elevation or topography sensor. When operating as an elevation or topography sensor, the machine position sensor  28  may generate elevation signals that are interpreted by the controller  36  to determine the relevant elevation or topography. Other sensors or a dedicated work surface position sensor may alternatively be used to determine the elevation or topography of the work surface. 
     The control system  35  may include an additional system such as a change in terrain detection system  30  shown generally by an arrow in  FIG. 2  indicating association with the machine  10 . One type of change in terrain detection system  30  that may be used to sense a crest at the work site  100  may be an implement load monitoring system  31  shown generally by an arrow in  FIG. 2 . The implement load monitoring system  31  may include any of a variety of different types of implement load sensors depicted generally by an arrow in  FIG. 2  as an implement load sensor system  32  to measure the load on the ground engaging work implement or blade  16 . For example, as blade  16  of machine  10  moves material over a crest, the load on the blade will be reduced. Accordingly, the implement load sensor system  32  may be utilized to measure or monitor the load on the blade  16  and a decrease in load may be registered by the controller  36  as a change in terrain due to the machine  10  being adjacent the crest. In other instances, an increase in load may indicate an incline or the machine  10  encountering a pile of material. In other words, the controller  36  may determine a change in terrain based at least in part upon a change in the load on blade  16 . 
     In one embodiment, the implement load sensor system  32  may embody one or more pressure sensors  33  for use with one or more hydraulic cylinders, such as second hydraulic cylinders  22 , associated with blade  16 . Signals from the pressure sensor  33  indicative of the pressure within the second hydraulic cylinders  22  may be monitored by controller  36 . Upon receipt of a signal indicating a substantial reduction in pressure within the second hydraulic cylinders  22 , the controller  36  may determine that the load on blade  16  has been substantially reduced due to the material having been pushed over a crest. Other manners of determining a reduction in cylinder pressure associated with a reduction in the load on blade  16  are contemplated, including other manners of measuring the pressure within second hydraulic cylinders  22  and measuring the pressure within other cylinders associated with the blade. An increase in pressure indicative of an increase in load may be determined in a similar manner. 
     Other manners of determining changes in terrain are contemplated including the use of perception systems, acceleration sensor, and monitoring changes in engine speed relative to torque converter speed. 
     Machine  10  may be configured to move material at the work site  100  according to one or more material movement plans along a path  117  from a first location  107  to a second spread or dump location  108 . The dump location  108  is typically but not always located downhill from the first location. The dump location  108  may be at crest  103  or at any other location. The material movement plans may include, among other things, forming a plurality of spaced apart channels or slots  110  that are cut into the work surface  104  at work site  100  along a path from the first location  107  to the dump location  108 . In doing so, each machine  10  may move back and forth along a path  117  ( FIG. 3 ) between the first location  107  and the dump location  108 . If desired, a relatively small amount of material may be left or built up as walls or berms  111  between adjacent slots  110  to prevent or reduce spillage and increase the efficiency of the material moving process. 
     As depicted in  FIG. 3 , in one embodiment, each slot  110  may be formed by removing material  105  from the work surface  104  in one or more layers  113  until the final work surface or final design plane  112  is reached. The blade  16  of machine  10  may engage the work surface  104  with a series of cuts  114  that are spaced apart lengthwise along the slot  110 . Each cut  114  begins at a cut location  115  along the work surface  104  at which the blade  16  engages the work surface and extends into the material  105  and moves towards the target surface  116  for a particular layer. As used herein, the work surface  104  along a slot prior to beginning to move material along that layer  113  is referred to as the initial surface. The target or desired position or elevation down to which material is to be cut for each layer  113  is referred to as the target surface and is beneath the work surface  104 . In many operations, the cut locations  115  begin at a location closest to the dump location  108  and are moved progressively back or uphill towards the first location  107 . Thus, as depicted in  FIG. 3 , material is moved by performing a plurality of cut operations at sequential cut locations  115  from right to left. 
     Controller  36  may be configured to guide the blade  16  along each cut  114  beginning at the initial surface and continuing until reaching the target surface  116  and then follow the target surface (which then functions as a carry surface) towards the dump location  108 . Referring to  FIG. 4 , during each material moving pass, the controller  36  may guide the blade  16  generally along a desired path or target profile depicted by dashed line  120  from the cut location  115  to the dump location  108 . A first portion of the target profile  120  extends from the cut location  115  to the target surface  116 . The first portion may be referred to as the loading profile  121  as that is the portion of the target profile  120  at which the blade  16  is initially loaded with material. A second portion of the target profile  120  extends from the intersection  123  of the cut  114  and the target surface  116  (which corresponds to the end of the loading profile) to the dump location  108 . The second portion may be referred to as the carry profile  122  as that is the portion of the target profile  120  at which the blade  16  carries the load along the target surface  116 . 
     The first portion or loading profile  121  may have any configuration and, depending on various factors including the configuration of the work surface  104  and the type of material to be moved, some cut profiles may be more efficient than others. The loading profile  121  may be formed of one or more segments that are equal or unequal in length and with each having different or identical shapes. These shapes may be linear, symmetrically or asymmetrically curved, Gaussian-shaped or any other desired shape. In addition, the angle of any of the shapes relative to the work surface  104  or the final design plane  112  may change from segment to segment. 
     The second portion or carry profile  122  may have any configuration but is often generally linear and sloped downward so that movement of material will be assisted by gravity to increase the efficiency of the material moving process. In other words, the carry profile  122  is often configured so that it slopes downward towards the dump location  108 . The characteristics of the carry profile  122  (sometimes referred to as the slot parameters) may include the shape of the target surface  116 , the depth of the target surface below the current uppermost or initial surface of the work surface  104  as indicated by reference number  124 , and the angle of the target surface as indicated by reference number  125 . In some instances, the angle  125  of the target surface  116  may be defined relative to a gravity reference or relative to the final design plane  112 . 
     As used herein, the word “uphill” refers to a direction towards the high wall  102  relative to the crest  103  or dump location  108 . Similarly, the word “downhill” refers to a direction towards the crest  103  or dump location  108  relative to the high wall  102 . 
     Referring to  FIG. 5 , a first process for spreading or dumping material involves pushing the material or overburden along the work surface until reaching a downward slope or crest. Upon reaching the crest, the overburden will fall down the slope along the crest. The process of dumping material over a crest and allowing the material to fall at the angle of repose due to gravity may sometimes be referred to as tip head dumping. In  FIG. 5 , examples of material dumped by a plurality of tip head dumping cycles are depicted schematically at  130 . 
     As the material being pushed by machine  10  falls downward due to gravity, the load on the machine  10  and blade  16  will decrease. The change in terrain detection system  30  may utilize the implement load monitoring system  31  and/or any other system such as a perception system to generate change in terrain signals that indicate a change in terrain adjacent machine  10 . Upon the change in terrain exceeding a change in terrain threshold, the controller  36  may generate command signals to move the machine  10  in reverse. The machine  10  may then be operated in reverse to back up along the path of operation until reaching the next cut location and the next sequential material moving operation performed. 
     Referring to  FIG. 6 , a second process for spreading or dumping material involves pushing the material or overburden along the work surface until reaching a desired end of travel location. Upon reaching the desired end of travel location, the machine  10  is operated in reverse which leaves a pile  131  of material on the work surface along which the machine is operating. The machine  10  is moved in reverse along the path of operation until reaching the next cut location and the next sequential material moving operation is performed. 
     In one embodiment, subsequent end of travel locations may be identified when the material being pushed by blade  16  engages the previously deposited pile  131  of material. Systems such as those used to monitor a change in terrain may detect when the material being pushed engages a previous pile  131  of material. More specifically, engagement or interaction of material being pushed with a previous pile  131  of material may be monitored by a change in load on the machine  10  and/or blade  16 , deceleration of the machine, and/or a change in pitch angle of the machine. Other systems such as a perception system may be used in addition or in the alternative. 
     Control system  35  may include a module or planning system  37  for determining or planning various aspects of the excavation plan. The planning system  37  may receive and store various types of input such as the configuration of the work surface  104 , the final design plane  112 , a desired loading profile  121 , a desired carry profile  122 , and characteristics of the material to be moved. Operating characteristics and capabilities of the machine  10  such as maximum load may also be entered into the planning system  37 . 
     In embodiments, the maximum load for a plurality of different operating conditions may be stored within the data map of the controller  36 . For example, the maximum load that may be moved by the machine  10  may defined as a function of the volume of the blade  16  and, in one example, may depend on the characteristics (e.g., water content) of the material being moved. In another example, the maximum load may depend on the maximum slope along which the machine  10  is operating. For example, the machine  10  may not be able to push as much material when operating uphill as compared to downhill. Further, the machine  10  may have different maximum loads depending on whether the machine is performing a cutting operation or a carry operation. Based upon each of the foregoing, a maximum load may be determined. 
     The planning system  37  may simulate the results of cutting the work surface  104  at a particular cut location and for a particular target profile, and then choose a cut location that creates the most desirable results based on one or more criteria. The planning system  37  may determine the depth and location of each of the layers  113  to be removed. In addition, the planning system  37  may determine the sequential cut locations  115  along each layer  113  as well as the shape of the cuts or loading profile  114  through each layer. The planning system  37  may also be operative to plan other aspects of the material moving plan. 
     In embodiments, the planning function may be performed while operating the machine  10 . In other embodiments, some or all aspects of the planning function may be performed ahead of time and the various inputs to the planning system  37  and the resultant cut locations, target profiles, and related data stored as part of the data maps of the controller  36 . 
     During the planning process, the planning system  37  may divide the path  117  along each slot  110  into a plurality of increments  109  ( FIG. 4 ) and data stored within controller  36  for each increment. The controller  36  may store information or characteristics of each increment  109  such as its position along the path, its elevation relative to a reference such as sea level, its angular orientation relative to a ground reference, and any other desired information. The information regarding each path  117  may be stored within an electronic map within the controller  36  as part of a topographical map of the work site  100 . By dividing the path  117  into a plurality of increments  109 , the analysis and planning process may be simplified by analyzing the characteristics at each increment. 
     Information regarding each path  117  may be obtained according to any desired method. In one example, the machine  10  may utilize the machine position sensing system  27  described above to map out the contour of work surface  104  as machine  10  moves across it. This data may also be obtained according to other methods such as by a vehicle that includes lasers and/or cameras. It should be noted that as the machine  10  moves material  105  to the dump location  108 , the position or contour of the work surface  104  will change and may be updated based upon the current position of the machine  10  and the position of the blade  16 . 
     As may be seen in  FIG. 4 , moving the blade  16  along the target profile  120  will result in a volume of material being moved from slot  110 . The planning system  37  may use the shape of the loading profile  121  and the cut location  115  to determine the volume of material that would be moved by blade  16  if the machine  10  were to follow the target profile  120 . More specifically, the planning system  37  may use three-dimensional data that is used to represent the machine  10 , the work surface  104 , and the target profile  120  to make a volumetric calculation of the volume of material that will be moved for a particular target profile  120 . 
     Planning system  37  may be configured to determine a cut location in any of a plurality of manners. In one configuration, the planning system  37  may analyze potential cut locations along path  117  using an admissible heuristic process or technique. In doing so, the planning system  37  may perform a coarse analysis along the path  117  of the machine  10  to determine a start location for a more precise or fine analysis that is used to determine an optimized cut location. 
     The planning system  37  may analyze one or more parameters along the path  117  to determine an optimized cut location. In one embodiment, the parameter to be analyzed may be the amount of material to be moved at each potential cut location. The amount of material to be moved may be expressed in terms of volume, percentage of volume that the blade  16  may carry, percentage of load on the blade, or in any other desired manner. In other embodiments, alternative or additional parameters may be used. 
     When utilizing volume of material as the parameter, the planning system  37  may be configured to seek a cut location  115  in which the volume of material to be cut is a predetermined percentage of the maximum volume of the blade  16 . In one embodiment, the loading percentage may be set at approximately 80%. In other embodiments, the loading percentage may be set at a lower volume such as approximately 70% and, in other embodiments, the loading percentage may be higher such as approximately  90 %. It should be noted that during the analysis, the volume of material that may be moved may change based upon the slope of the path  117  along which the machine  10  is operating. 
     Referring to  FIG. 7 , typical or traditional material cutting and carry operations are depicted with the material dumped or spread using a backstacking process. More specifically, during such operations, the machine  10  is positioned on the work surface  104  so that the tip  23  of the blade  16  is aligned with the desired cut location  140 . The machine  10  is then propelled forward and downhill (from left to right in  FIG. 7 ) with the tip  23  of the blade  16  cutting into and following the loading profile  147  to load the blade  16  and move material along the carry surface  142  until reaching the dump location. The machine  10  is then propelled in reverse until reaching the next cut location at which point the material moving operation is repeated. 
     The amount of material cut from the work surface  104  is first identified at  143  adjacent the cut location and the same material is identified again as a pile of material  144  formed as part of the backstacking process. In other words, the same material is depicted in  FIG. 7  at its initial position at  143  prior to the cutting operation and at  144  after the carry operation has been completed. Since the material moving operation depicted in  FIG. 7  includes only a single cut operation, the process is referred to herein as a “single cut operation” and the cut location  140  is referred to as a “single cut location.” 
     In many instances, the maximum amount of material that may be cut during a cutting operation is 90% of the capacity or volume of the blade  16 . Attempting to cut a greater amount of material may result in the machine  10  becoming stuck and/or cause excess wear on the machine. However, the machine  10  will typically have a substantially greater capacity to push or move material along the work surface  104  during the carry portion of a material moving operation (i.e., after the cutting operation). In some instances, this may be the result of the material being cut having been compacted as compared to material being carried and/or due to the nature of the cutting process. Whereas in one example the maximum amount of material that may be cut is 90% of the volume of the blade, the maximum amount of material that may be carried during the subsequent carrying operation may be 150% of the volume of the blade  16 . Each of the percentages identified above may be affected by the characteristics of the material being moved and the maximum uphill slope encountered by the machine  10  during the relevant operation. 
     As may be understood from  FIG. 7 , after each load of material is cut from the work surface  104  and then carried to the dump location  108 , the machine  10  operates in reverse to move back to the next single cut location. As described with respect to  FIGS. 8-9 , the planning system  37  disclosed herein is configured to generate cut locations and loading profiles that increase the amount of material that is carried during each carry operation. As a result, the number of carry operations required to move a specified total volume of material is reduced and as is the amount of time the machine is operated in reverse without pushing material. Such alternate cutting and carrying operations are referred to herein as a “double cut operation” as is explained in further detail below. 
     In operation, the planning system  37  determines a first double cut location  146  ( FIG. 8 ) at which a volume of material is cut that is less than the maximum cutting capacity of the machine  10  and is approximately equal to one half of the maximum carrying capacity. Using the expected new or modified topography of the work surface as a result of the first double cut operation, the planning system  37  then determines a second double cut location  150  ( FIG. 9 ) at which the volume of material that is cut is also less than the maximum cutting capacity of the machine  10  and is also approximately equal to one half of the maximum carrying capacity. 
     Although described in the example above with the volume of material equal to approximately one half of the carrying capacity of the machine  10 , other volumes may be used. For example, the volume split between the first and second double cut operations does not need to be 50/50. The planning system  37  may select the first and second cutting locations so that a greater volume of material may be cut during either cutting operation so long as the volume does not exceed the cutting capacity of the machine  10 . Further, the total volume cut by the first and second cutting operations does not need to equal the maximum capacity of the carrying operation. In some instances, it may be desirable to carry less than the maximum capacity. 
     Referring back to  FIG. 8 , the first stage of a double cut operation is depicted. The machine  10  is positioned on the work surface  104  so that the tip  23  of the blade  16  is aligned with a desired first double cut location  146 . As discussed above, the first double cut location  146  may be selected by the planning system so that the volume of material moved by cutting at the first double cut location  146  and with a desired loading profile  147  results in the movement of a volume of material less than the maximum cutting capacity of the blade  16  and approximately half of the carrying capacity of the blade. Using the example above in which the maximum cutting capacity is 90% of the blade volume and the maximum carrying capacity is 150% of the blade volume, the first cut location  146  may be selected so that 75% of the capacity of the blade  16  will be cut. 
     The machine  10  is then propelled forward and downhill with the tip  23  of the blade  16  cutting into the work surface  104  at the first double cut location  146  and following the loading profile  147  to load the blade  16  and move material along the carry surface  142  towards the dump location. Unlike the single cut operation described above, the machine  10  only travels partway towards the dump location  108  to an intermediate position between the first double cut location  146  and the dump location before being propelled in reverse to leave a pile of material  500  along the path but spaced from the first double cut location  146 . In  FIG. 8 , the amount of material that is cut from the work surface  104  is first identified at  149  adjacent the first double cut location  146  and the same first double cut amount of material is identified again as the pile of material  148  somewhat downhill from the first double cut location. 
     The distance the machine  10  travels forward before stopping and operating in reverse is referred to herein as the double cut separation distance  160 . The double cut separation distance  160  is intermediate the distance from the location where the blade  16  reaches the target surface  116  (i.e., where the machine  10  completes the cutting operation) to the location at which it stops moving forward. In embodiments, the double cut separation distance  160  may be approximately two times the length of the machine  10 . Other distances are contemplated. 
     A first reversing operation is performed by propelling the machine  10  in reverse away and uphill from the pile of material  148  until the machine reaches a position on the work surface  104  at which the tip  23  of the blade  16  is aligned with the desired second double cut location  150  ( FIG. 9 ). The second double cut location  150  may be selected by the planning system  37  so that the volume of material moved by cutting at the second double cut location (and after material has been removed by the first double cut operation) results in the movement of another 75% of the volume of the blade  16 . As with the first double cut operation, the volume of material being cut by the blade  16  is less than the maximum cutting volume of the machine  10 . 
     The machine  10  is then propelled forward and downhill with the tip  23  of the blade  16  cutting into the work surface  104  at the second double cut location  150  and following the loading profile  151  to load the blade  16  and move material along the carry surface  142  towards the dump location  108 . The machine  10  travels partway towards the dump location  108  only partially loaded with material from the second double cut operation until it reaches the material left as the pile of material  148  from the first double cut operation. As the machine  10  continues in the forward and downhill direction, the blade pushes the pile of material  148  together with the material cut at the second double cut location  150  until it reaches the dump location  108 . 
     A second reversing operation is performed by propelling the machine  10  in reverse away and uphill from the dump location  108  until the machine reaches a position on the work surface  104  at which the tip  23  of the blade  16  is aligned with the next cut location, at which point the next material moving operation (i.e., a single cut or double cut) is performed. 
     As depicted in  FIG. 9 , the amount of material cut from the work surface  104  in the first double cut operation adjacent the first double cut location  146  is identified at  149  uphill from the dotted line  152  that corresponds to the work surface prior to the first double cut operation. That same material is identified as a portion  156  of the pile of material  155  at the dump location  108 . The amount of material that is cut from the work surface  104  in the second double cut operation adjacent the second double cut location  150  is identified at  154  and the same second double cut amount of material is identified as a portion  157  of the pile of material  155 . 
     Although  FIGS. 7-9  are depicted as using a backstacking dumping process, the single and double cut operations may be used with any type of dumping process such as the tip head dumping depicted in  FIG. 5 . Further, although the carry surface  142  is depicted as including downward and level surfaces in  FIGS. 6-9 , the carry surface may also include sections that extend upward. Thus, while a downward slope will increase the carrying capacity of the machine  10  as compared to a level surface, an upward slope will decrease the carrying capacity of the machine. 
     INDUSTRIAL APPLICABILITY 
     The industrial applicability of the planning system  37  described herein will be readily appreciated from the forgoing discussion. The foregoing discussion is applicable to systems in which one or more machines  10  are operated autonomously, semi-autonomously, or manually at a work site  100  to move material. Such system may be used at a mining site, a landfill, a quarry, a construction site, a roadwork site, a forest, a farm, or any other area in which movement of material is desired. 
     The flowchart of  FIG. 10  depicts a material movement process in which the planning system  37  may determine an optimal location for a cut that forms a portion of a single cut operation or pair of cuts that form a portion of a double cut operation. At stage  50 , the final design plane  112  may be set or stored within or entered into the controller. In one embodiment, the final design plane  112  may be entered by an operator or other personnel. In another embodiment, the final design plane  112  may be generated by the controller. 
     At stage  51 , the operating characteristics of the machine  10  may be stored or set within the controller  36 . The operating characteristics may include a desired load on the machine  10  and the dimensions of the machine. In embodiments, the operating characteristics of the machine may include the volume of material that can be moved during cut and carry operations as a function of the volume of the blade. The volume of material that can be moved may also be stored as a function of characteristics of the work site  100  including the maximum slope of the path along which the machine  10  is traveling, characteristics of the material being moved and/or any other desired characteristics. 
     One or more desired loading profiles of the target profile may be stored or set within the controller  36  at stage  52 . As stated above, the loading profiles may have any desired configuration. At stage  53 , the carry profile or slot parameters may be stored or set within the controller  36 . The slot parameters may define the shape of the target surface  116 , the depth of the carry surface below the work surface and each subsequent carry surface, the angle of the carry surface relative to a fixed reference, and the curvature of the carry surface. 
     At stage  54 , double cut characteristics may be stored or set within the controller  36 . The double cut characteristics may include a biasing factor and a double cut separation distance  160 . The biasing factor may be used to determine whether to use a single cut or a double cut operation if the efficiencies of the two processes are similar. The double cut separation distance  160  may set the distance the machine  10  moves the material cut at the first double cut location  146 . 
     The controller  36  may receive at stage  55  data from the position sensor  28 . At stage  56 , the controller  36  may determine the position or topography of the work surface  104  based upon the data from the position sensor  28 . 
     At stage  57 , the next dump end location may be accessed or determined. Regardless of whether the machine  10  is operating using a tip head dumping process or a backstacking process, the next dump end location may be determined, for example, based upon GPS coordinates, the previous dump end location, the terrain detection system  30  and/or any other desired sensors or systems. 
     At stage  58 , the controller  36  may determine the desired volume of material to be moved using a single cut operation. In doing so, the controller  36  may analyze the characteristics of the material being moved and the profile or topography of the work surface  104  to determine the maximum volume of material that the machine  10  can cut. 
     At stage  59 , the controller  36  may determine the next single cut location based upon the current profile or topography of the work surface  104  and the maximum volume of material the machine  10  can cut. For example, the controller  36  may analyze a plurality of potential cut locations and, based upon the current topography of the work surface  104  and/or the characteristics of the material, select a single cut location  140  and loading profile  141  that optimizes one or more operating characteristics. In one embodiment, the controller  36  may select the single cut location  140  to move a maximum amount of material in the most efficient manner possible. The maximum amount of material may be set to correspond to the maximum amount of material the machine  10  can cut. 
     The controller  36  may determine at stage  60  the efficiency of the single cut material moving operation Eff  singlecut  based upon the single cut location  140  selected by the controller. The single cut efficiency Eff singlecut  may be determined based upon the volume of material moved divided by the distance that the machine  10  traveled to move that volume of material. More specifically, the single cut efficiency Eff singlecut  may be expressed as:
 
Eff singlecut =Vol singlecut /2*Dist singlecut    (1)
 
where Vol singlecut  is the volume of material moved during the single cut operation, and Dist singlecut  is the distance moved by the machine  10  during the single cut operation. As depicted at  161  in  FIG. 7 , Dist singlecut  corresponds to the distance from the single cut location  140  to the edge of the pile of material  144  moved during the single cut operation. The Dist singlecut  in the denominator of Equation (1) is multiplied by the numeral “2” to account for the distance the machine  10  moves in the forward direction from the single cut location  140  to the dump location  108  and the distance the machine moves in reverse from the dump location back to the next cut location.
 
     At stage  61 , the controller  36  may determine the volume of material to be moved using a double cut operation. In doing so, the controller  36  may analyze the characteristics of the material being moved and the profile or topography of the work surface to determine the maximum volume of material that the machine  10  can carry. 
     At stage  62 , the controller  36  may determine the first double cut location  146  based upon the current profile or topography of the work surface  104  and the maximum volume of material that the machine  10  can carry. For example, the controller  36  may analyze a plurality of potential cut locations and, based upon the current topography of the work surface  104  and/or the characteristics of the material, select a first double cut location  146  and loading profile  147  that optimizes one or more operating characteristics. In one embodiment, the controller  36  may select the first double cut location  146  to move a desired amount of material in the most efficient manner possible. In one embodiment, the desired amount of material may be set to correspond to the half of the maximum amount of material the machine  10  can carry. 
     At stage  63 , the controller  36  may determine the second double cut location  150  based upon the expected profile or topography of the work surface  104  as it would appear after the first double cut operation and the maximum volume of material that the machine  10  can carry. The controller  36  may analyze a plurality of potential cut locations and, based upon the expected topography of the work surface  104  after the expected first double cut operation and/or the characteristics of the material, select a second double cut location  150  and loading profile  151  that optimizes one or more operating characteristics. In one embodiment, the controller  36  may select the second double cut location  150  to move a desired amount of material in the most efficient manner possible. In one embodiment, the desired amount of material may be set to correspond to the half of the maximum amount of material the machine  10  can carry. 
     The controller  36  may determine at stage  64  the efficiency of the double cut material moving operation Eff doublecut  based upon the double cut locations  146 ,  150  selected by the controller. The double cut efficiency Eff doublecut  may be determined based upon the volume of material moved divided by the distance that the machine  10  traveled to move that volume of material. More specifically, the double cut efficiency Eff doublecut  may be expressed as:
 
Eff doublecut =Vol doublecut /(2*Dist doublecut1 +Dist doublecut2 )   (2)
 
where Vol doublecut  is the total volume of material moved during the double cut operation In other words, the volume of material moved during the first double cut operation plus the volume of material moved during the second double cut operation. Dist doublecut1  is the distance moved by the machine  10  during the first double cut operation. As depicted at  162  in  FIG. 8 , Dist doublecut1  is the distance from the first double cut location  146  to the location of the pile of material  148 . As depicted at  163  in  FIG. 9 , Dist doublecut2  is the distance from the second double cut location  150  to the dump location for the entire pile of material  155 . The Dist doublecut1  and Dist doublecut2  in the denominator of Equation (2) is multiplied by the numeral “2” to account for the distance the machine  10  moves in the forward direction from each of the double cut locations  146 ,  150  and the distance the machine moves in reverse from the first pile of material  148  and the second pile of material  155 , respectively, back to the next cut location.
 
     In some embodiments, the single cut efficiency Eff singlecut  may be multiplied by a biasing factor Bias doublecut  to determine a double cut efficiency threshold Threshold doublecut  at stage  65 . The biasing factor Bias doublecut  may be used to determine which cutting operation (i.e., single cut or double cut) to use if the efficiencies are of the two operations are similar or close. More specifically, the double cut efficiency threshold Threshold doublecut  may be expressed as:
 
Threshold doublecut =Eff singlecut *Bias doublecut    (3)
 
     In an embodiment in which the biasing factor Bias doublecut  is equal to 1.0, the controller  36  may select the cutting operation based upon whichever has the highest efficiency. In other embodiments, the biasing factor Bias doublecut  may be set at greater than 1.0 so that the controller  36  may utilize the single cut operation unless the double cut operation is more efficient than the single cut operation. In an example, the biasing factor biasing factor Bias doublecut  may be set at greater than 1.1 so that the controller  36  may utilize the single cut operation unless the double cut operation at least 10% more efficient than the single cut operation. 
     At stage  66 , the controller  36  may determine whether the double cut efficiency Eff doublecut  exceeds the double cut efficiency threshold Threshold doublecut . If the double cut efficiency Eff doublecut  does not exceed the double cut efficiency threshold Threshold doublecut , the controller  36  may generate at stage  67  a single cut operating command to perform a single cut operation. When operating autonomously, the controller  36  may generate operating commands to move the machine  10  so that the tip  23  of the blade  16  is aligned with the single cut location  140 . Further commands may be generated to propel the machine  10  forward with the tip  23  of the blade  16  following the loading profile  141  and moving the material to the dump location  108 . Upon reaching the dump location  108 , the machine  10  may be propelled in reverse to move the machine to the next cut location and then repeating stages  55 - 68 . In embodiments, stage  55  may be performed while the machine is operating in reverse. In other embodiments, stage  55  may be performed while the machine  10  is moving towards the dump location  108 . If desired, the analysis of stages  56 - 68  may be performed while the machine is being propelled in reverse. When operating semi-autonomously, the controller  36  may autonomously perform some but not all of the operations for the single cut operation. 
     If the double cut efficiency Eff doublecut  exceeds the double cut efficiency threshold Threshold doublecut  the controller  36  may generate at stage  68  a double cut operating command to perform a double cut operation. When operating autonomously, the controller  36  may generate operating commands to move the machine  10  so that the tip  23  of the blade  16  is aligned with the first double cut location  146 . Further commands may be generated to propel the machine forward with the tip  23  of the blade  16  following the loading profile  147  and moving the material towards the dump location  108 . 
     Upon traveling the double cut separation distance  160  after the blade  16  has reached the carry surface  142 , further commands may be generated to propel the machine in reverse until the tip  23  of the blade is aligned with the second double cut location  150 . Further commands may be generated to propel the machine forward with each tip  23  of the blade following the loading profile  151  and moving the material towards the dump location  108 . Upon reaching the pile of material  148  moved during the first double cut operation, the machine  10  will carry material from both the first and second double cut operations to the dump location  108 . Upon reaching the dump location  108 , the machine  10  may be propelled in reverse to move the machine to the next cut location and then repeating stages  55 - 68 . In embodiments, stage  55  may be performed while the machine is operating in reverse. In other embodiments, stage  55  may be performed while the machine  10  is moving towards the dump location  108 . If desired, the analysis of stages  56 - 68  may be performed while the machine is being propelled in reverse. When operating semi-autonomously, the controller  36  may autonomously perform some but not all of the operations for the double cut operation. 
     Various alternatives are contemplated. For example, as described above, rather than splitting the volume of material equally between the first and second double cut operations, the volume may be split in other ratios. Further, although the efficiencies of the single and double cut operations are calculated above based upon the distance traveled by the machine  10 , the efficiencies could be calculated in other manners such as based upon other operating parameters associated with the material moving operations including the travel time or fuel consumption for each process. 
     It will be appreciated that the foregoing description provides examples of the disclosed system and technique. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated. 
     Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. 
     Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.