Patent Publication Number: US-8985233-B2

Title: System and method for controlling a rotation angle of a motor grader blade

Description:
RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from U.S. Provisional Application No. 61/428,843 by Christopher A. Padilla, filed Dec. 22, 2010, the contents of which are expressly incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This patent disclosure relates generally to blade control systems, and more particularly, to systems and methods for controlling a rotation angle of a motor grader blade. 
     BACKGROUND 
     Motor graders are used primarily as a finishing tool to sculpt a surface of the earth to a final arrangement. Typically, motor graders include many manual controls or input devices to steer the motor grader, position a blade, and/or articulate a frame of the motor grader. The operator may use the input devices, such as, for example, hand levers to manually adjust the motor grader. A motor grader is adjusted, for example, to an articulation angle by rotating the front frame relative to a rear frame. The operator may adjust the articulation angle while performing other tasks, such as, for example, repositioning the blade and steering. 
     Controlling the many control input devices may require a highly skilled operator. The blade, for example, is adjustably mounted to a front frame of the motor grader to move relatively small quantities of earth from side to side. Even with a skilled operator, manual control of the blade to accomplish earthmoving tasks, particularly finish work such as finish grading, is not always accurate and can require multiple trials to achieve a desired result. This duplication of work may be inefficient, time consuming, costly, and fatiguing to the operator. To increase efficiency and allow the operator to concentrate on important operational tasks, it is desirable to provide a system and method for automatically controlling the rotation angle of the blade of a motor grader. 
     The present disclosure is directed to overcome one or more of the problems as set forth above. 
     SUMMARY 
     The disclosure describes, in one aspect, a system and method for controlling a rotation angle of a blade of a motor grader having a front frame operatively coupled to a rear frame at a point defining an articulation angle between the front and rear frames. The control system includes at least one sensor operatively associated with the blade, at least one sensor operatively associated with a wheel, at least one sensor operatively associated with at least one of the front frame or the rear frame, and a controller operatively coupled to the at least one sensors. The controller is adapted to determine a current position of the blade, determine a wheel steering angle, determine an articulation angle, and control the rotation angle of the blade based in part on the wheel steering angle and the articulation angle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING(S) 
         FIG. 1  is a diagrammatic side elevational view of a motor grader having a control system in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 2  is a flow diagram illustrating one embodiment of a control process for controlling a rotation angle of a blade of a motor grader in accordance with an exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure relates to systems and methods for automatically controlling a rotation angle of a motor grader blade. An exemplary embodiment of a motor grader  100  is generally shown in  FIG. 1 , may perform some type of operation associated with an industry such as mining, construction, farming, transportation, or any other industry known in the art. The motor grader  100  is generally used as a finishing tool to alter a surface of terrain or earth  102  to a final arrangement or contour. In an illustrated embodiment, the motor grader  100  includes a front frame  104 , a rear frame  106 , and a blade  108 . The front  104  and rear  106  frames are supported by wheels  110 , which include a pair of front wheels  112  and two pairs of rear wheels  114 ,  116  (only one side shown). 
     In the illustrated embodiment, the motor grader  100  further includes a power source such as an engine  118 , an operator station or cab  120  containing controls necessary to operate the motor grader  100 , such as, for example, input devices  122  for propelling the motor grader  100  and/or for controlling the blade  108  for moving earth  102  and/or for controlling other machine components. The input devices  122  may include one or more devices embodied as a joystick disposed within the cab  120  and may be adapted to receive input from an operator indicative of a desired blade  108  or motor grader  100  movement. The cab  120  is mounted on the front frame  104 . 
     The engine  118  may power a drive system (not shown) that may include the front wheels  112  and the rear wheels  114 ,  116  adapted to support the motor grader  100 . The wheels  110 ,  112 ,  114 ,  116  may be adapted for steering and maneuvering the motor grader  100  and for propelling the motor grader  100  in forward and reverse directions. The front wheels  112  may be adapted to turn relative to the front frame  104  to steer the motor grader  100 . The angle formed between the direction of the front wheels  112  and the front frame  104  establishes a wheel steering angle. For example, when the front wheels  112  are facing forward, and the motor grader  100  is not articulated, the wheel steering angle is zero. Any pivoting by the wheels  112  relative to the front frame  104  increases the wheel steering angle by an amount that may be proportionate to the amount of pivoting of the front wheels  112 . 
     The engine  118  may embody, for example, a diesel engine, a gasoline engine, a gaseous fuel-powered engine, or any other type of combustion engine known in the art. It is contemplated that the power source  118  may alternatively embody a non-combustion source of power (not shown) such as, for example, a fuel cell, a power storage device, or another suitable source of power. The engine  118  may produce a mechanical or electrical power output that may be converted to hydraulic power. The engine  118  is mounted on the rear frame  106 . 
     In some embodiments, the blade  108  is operatively coupled to a drawbar/moldboard/circle (DMC) assembly  124 , which includes a drawbar  126 , a moldboard  128 , and a circle  130 . The position of the drawbar  126  may be controlled by hydraulic cylinders coupled to the front frame  104 , such as, for example, a pair of lift cylinders  132 ,  134  (a right lift cylinder and a left lift cylinder respectively) and a shift cylinder  136 . The lift cylinders  132 ,  134  may be controlled independently, for example, to angle a bottom edge or cutting edge  140  of the blade  108  relative to the surface of the earth  102 . The shift cylinder  136  may be controlled to side shift the drawbar  124 . The lift cylinders  132 ,  134  and shift cylinder  136  are coupled to the front frame using a moveable coupling  138  that may be moved during repositioning of the blade  108  but that is fixed stationary during earthmoving operations. 
     The blade  108  may be coupled to the circle  130  and the circle  130  may be rotatably coupled to the moldboard  128 . The moldboard  128  may be coupled to the drawbar  126 , which may be coupled to the front frame  104  of the motor grader  100 . In some embodiments, the blade  108  may be fixedly coupled to the circle  130 . The circle  130  may rotate about an axis A, which may, in turn, cause the blade  108  to rotate about the axis A. The circle  130  is rotated by a hydraulic motor or circle drive (not shown). 
     In some embodiments, the blade  108  may be adjusted in several degrees of freedom relative to the motor grader  100 . The rotation of the blade  108  about the axis A may result in a change in a rotation angle of the blade  108  relative to a direction of travel of the motor grader  100 . Rotating the blade  108  about the axis A establishes a blade cutting angle, which may be defined as the rotation angle of the blade  108  relative to the front frame  104  and relative to the direction of travel of the motor grader  100 . At a zero degree cutting or rotation angle, the blade  108  is aligned at a right angle to the front frame  104  and orthogonal to or perpendicular to the direction of travel of the motor grader  100 . 
     In addition to rotating about axis A, the blade  108  may be tilted forward and backward. The blade  108  is hingeably coupled to the circle  130 , which allows the blade  108  to be moveable forward and backward. A tip cylinder  142  is used to move a top edge  144  of the blade  108  ahead of or behind the bottom cutting edge  140  of the blade  108 . The position of the tip edge of the blade  108  relative to the bottom cutting edge  140  is commonly referred to as a blade  108  tip. 
     In addition, the blade  108  may be slidably coupled to the circle  130  to permit movement of the blade  108  from side to side relative to the circle  130 , referred to as a blade  108  side shift. A side shift cylinder (not shown) controls the blade  108  side shift. Further, the blade  108  may be raised or lowered to adjust a height of the blade  108  relative to the surface of the earth  102 . Still further, the blade  108  may be adjusted so as to change a slope of the blade  108 . Blade  108  height may be primarily controlled by the lift cylinders  132 ,  134 . 
     The motor grader  100  may further include articulation cylinders (not shown) coupled to each side of the rear frame  106 . An articulation joint connects the front frame  104  to the rear frame  106  at axis B. The articulation cylinders may be used to rotate the front frame  104  about the articulation axis B. As shown in  FIG. 1 , the motor grader  100  is in a neutral or zero articulation angle position. A suitable sensor, such as, for example, a rotary sensor or other displacement sensor  146 , may be used to measure an articulation angle at the articulation joint. Movement of the front frame  104  relative to the rear frame  106  establishes the articulation angle. The motor grader  100  may be operated with the front frame  104   102  rotated to a full or maximum right articulation angle, a full or maximum left articulation angle, or any angle between the full right and full left articulation angles. 
     The motor grader  100  may further include a control system  148  operatively connected to the input device  122  and to the hydraulic cylinders  132 ,  134 ,  136 ,  142  for controlling, for example, movement of the blade  108  or the articulation angle of the front frame  104 , and other hydraulic actuators. In some embodiments, the control system  148  may be operatively connected to the input device  122  and to other motor grader  100  components for controlling other operations of the motor grader  100 , such as, for example, operatively connected to the wheels  110  for controlling a speed of the motor grader  100 . 
     The control system  148  may direct the blade  108  to move to a predetermined or target position in response to an operators&#39; desired movement of the blade  108  for engaging the blade  108  with the terrain of the earth  102 . The control system  148  may further direct the blade  108  to move to a predetermined or target position indicative of an automatically determined movement of the blade  108 , based in part on, for example, an engineering or site design, a map, a productivity measure, or a combination of site design and productivity measure. 
     For precise control, such as, for example, to direct the blade  108  to move precisely in response to an automatically determined movement signal or command, the control system  148  may require certain predetermined or acquired data associated with the motor grader  100 , such as, for example, the articulation angle of the motor grader  100 . The control system  148  may include one or more sensors  150  operatively connected to or associated with the motor grader  100  for determining certain operational characteristics, such as, for example, the wheel steering angle of the motor grader  100  or the rotation angle of the blade  108 . The one or more sensors  150  may embody position sensors  152  associated with each hydraulic actuator, cylinder, and motor such as the lift cylinders  132 ,  134 , shift cylinder  136 , and the circle drive motor. 
     The control system  148  may be adapted to receive inputs from the input device  122  and the sensors  146 ,  150 . The control system  148  is further adapted to control or direct the movement of the blade  108  based at least in part on the inputs from the input device  122  and the sensors  146 ,  150 . The position sensors  152  provide information to the control system  148  associated with its respective hydraulic actuator, cylinder, and motor. Consequently, the control system  148  can determine a position of the blade  108 . In addition, the control system  148  receives articulation information from the rotary sensor  146 . 
     Alternatively, or additionally, the one or more sensors  150  may embody at least one wheel angle sensor  154  associated with at least one of the front wheels  112  and may be adapted to monitor the front wheels  112  to determine the wheel steering angle. In some embodiments, the wheel angle sensor monitors the wheel steering angle. In other embodiments, the wheel angle sensor monitors the angles of steering linkages associated with the front wheels  112  or the extension amount of an actuator, such as, for example, a hydraulic actuator (not shown) that controls steering. The wheel angle sensor  154  may be located at any of number of different positions where it can monitor the amount of turn of a front wheel  112  or sense movement of the input device  122  indicative of a desired turn. With blade  108  position, articulation angle, the wheel steering angle information, and other such information associated with operations of the motor grader  100 , the control system  148  may control motor grader  100  operations as discussed above. 
     The control system  148  may include one or more control modules (e.g. ECMs, ECUs, etc.). The one or more control modules may include processing units, memory, sensor interfaces, and/or control signal interfaces (for receiving and transmitting signals). The processing units may represent one or more logic and/or processing components used by the control system  148  to perform certain communications, control, and/or diagnostic functions. For example, the processing units may be adapted to execute routing information among devices within and/or external to the control system  148 . 
     Further, the processing units may be adapted to execute instructions, including from a storage device, such as memory. The one or more control modules may include a plurality of processing units, such as one or more general purpose processing units and or special purpose units (for example, ASICS, FPGAs, etc.). In certain embodiments, functionality of the processing unit may be embodied within an integrated microprocessor or microcontroller, including integrated CPU, memory, and one or more peripherals. The memory may represent one or more known systems capable of storing information, including, but not limited to, a random access memory (RAM), a read-only memory (ROM), magnetic and optical storage devices, disks, programmable, erasable components such as erasable programmable read-only memory (EPROM, EEPROM, etc.), and nonvolatile memory such as flash memory. 
     INDUSTRIAL APPLICABILITY 
     The industrial applicably of the systems and methods for automatically controlling a rotation angle of a motor grader blade described herein will be readily appreciated from the foregoing discussion. Although shown as a motor grader, any type of machine that performs at least one operation associated with, for example, mining, construction, and other industrial applications may embody the disclosed systems and methods. The machine may also be associated with non-industrial uses and environments, such as, for example, cranes, earthmoving vehicles, backhoes, and/or material handling equipment. Moreover, the systems and methods described herein can be adapted to a large variety of machines and tasks. 
     As discussed, one exemplary motor grader suited to the disclosure includes a control system  148  that is adapted or configured to generate a desired or optimal blade rotation angle and/or control the position of the blade to achieve the desired or optimal blade rotation angle based in part on the articulation angle and the wheel steering angle. In accordance with certain embodiments,  FIG. 2  illustrates an exemplary embodiment of the control system  148  and the process of automatically controlling the rotation angle of a motor grader blade ( 200 ). 
     The control system  148  is adapted to receive articulation angle information from the rotary sensor  146  associated with the front  104  and rear  106  frames (Step  202 ). The control system  148  is further adopted to received wheel steering angle information from a wheel angle sensor  154  associated with at least one of the front wheels  112  of the motor grader  100  (Step  204 ). In some embodiments, the control system  148  may determine a turn radius based in part on the wheel steering angle and the articulation angle (Step  206 ). In the illustrated embodiment, the control system  148  controls the rotation angle of the blade  108  based in part on the articulation angle and the wheel steering angle (Step  208 ). 
     In some embodiments, the optimal rotation angle of the blade  108  may be embodied in a table that correlates the optimal rotation angle with the combination of articulation angle information and wheel steering angle information. In some embodiments, the control system  148  may incorporate other information associated with the operation of the motor grader  100  to determine a current turn radius, such as, for example, a wheel lean angle. Further, additional information associated with the characteristics of the motor grader  100 , such as, for example, machine dimensions or blade length, or information associated with the application, such as, for example finish grade for a cul-de-sac, may be used to determine the optimal rotation angle of the blade  108  of the motor grader  100 . The optimal rotation angle of the motor grader  100  blade  108  may be associated with sending material to an ideal location outside of the turn radius of the motor grader  100  with less rework or fewer grading cycles. 
     It will be appreciated that the foregoing description provides examples of the disclosed systems and methods. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. 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.