Abstract:
A method of controlling the movement of a work machine arm having a series of hydraulic cylinders operatively engaged with the work machine arm is disclosed. The method includes receiving a signal from an input device to change the position of the work machine arm and determining an extension amount of one or more of the series of hydraulic cylinders. The extension amount of one or more of the series of hydraulic cylinders is changed to effect the change in the position of the work machine arm. The changes in the extension amount of the one or more of the series of hydraulic cylinders are ordered based on a pre-selected priority of movement. A system for controlling the movement of a work machine arm having a series of hydraulic cylinders operatively engaged with the work machine arm is also disclosed.

Description:
TECHNICAL FIELD  
       [0001]     This invention relates to a system and method for automatically controlling the movement of an arm on a work machine.  
       BACKGROUND  
       [0002]     Work machines are often equipped with a work machine arm capable of performing any number of tasks. For example, a work machine such as a backhoe or an excavator may include a digging work machine arm. Likewise, a work machine such as a forklift or a telescopic material handler may include a work machine arm for lifting and carrying objects. Other work machines may include work machine arms that are adapted to support vibratory compactors or other equipment.  
         [0003]     Because controlling a work machine arm is often a complex process, an inexperienced operator may have difficulty moving an element of the work machine arm, such as a work implement, along a desired path. To simplify the coordination required to accomplish this, some work machines are provided with a single input device that controls the movement of all the components of the work machine arm. Use of a single input device may simplify the operation of the work machine arm and reduce operator fatigue.  
         [0004]     U.S. Pat. No. 6,374,153 to Brandt et al. discloses an apparatus and method for providing coordinated control to a telescopic material handler. Often, a material handler is used to raise a pallet in a vertical direction. The coordinating apparatus of the &#39;153 patent enables an operator to more easily control the material handler arm so that it moves along the vertical path by simultaneously changing both the length and the angle of the boom. The &#39;153 patent discloses a control system that calculates a compensating error that may develop when one hydraulic cylinder does not receive the necessary hydraulic fluid flow due to the demand of flow from another cylinder.  
         [0005]     At times, it may be desirable to move different components of the work machine arm in an order of priority that can be adapted to the needs of a specific work site. For example, when a work machine arm is used to dig in an area adjacent a standing structure, a bucket on the work machine arm must be extended so that the bucket edge approaches the wall before the back of the bucket. In another example, the life of a specific, expensive component of the work machine arm may be prolonged by using it only when necessary. Current work machines having systems for coordinated movement do not provide for prioritizing the movement of different components of the work machine arm.  
         [0006]     The present invention is directed to overcoming one or more of the disadvantages of the prior art.  
       SUMMARY OF THE INVENTION  
       [0007]     In one aspect, a method of controlling the movement of a work machine arm having a series of hydraulic cylinders operatively engaged with the work machine arm is disclosed. The method includes receiving a signal from an input device to change the position of the work machine arm and determining an extension amount of one or more of the series of hydraulic cylinders. The extension amount of one or more of the series of hydraulic cylinders is changed to effect the change in the position of the work machine arm. The changes in the extension amount of the one or more of the series of hydraulic cylinders are ordered based on a pre-selected priority of movement.  
         [0008]     In another aspect, a system for controlling the movement of a work machine arm having a series of hydraulic cylinders operatively engaged with the work machine arm is disclosed. The system includes an input device operable to generate a signal to change the position of the work machine arm and at least one sensor associated with one or more of the series of hydraulic cylinders for determining an extension amount of the one or more of the series of hydraulic cylinders. A control module is adapted to receive the signal from the input device and to change the extension amount of one or more of the series of hydraulic cylinders to affect the change in the position of the work machine arm. The changes in the extension amount of the one or more of the series of hydraulic cylinders are ordered based on a pre-selected priority of movement. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a diagrammatic illustration of a portion of a work machine suited for use with the present invention.  
         [0010]      FIG. 2  is a block diagram illustrating an exemplary controller for operating a work machine arm.  
         [0011]      FIG. 3  is a flow chart showing an exemplary method for controlling a work machine arm using a pre-selected priority of movement.  
         [0012]      FIG. 4  is a flow chart showing an exemplary method of extending a work machine arm using a pre-selected priority of movement.  
         [0013]      FIG. 5  is a flow chart showing an exemplary method of retracting a work machine arm using a pre-selected priority of movement. 
     
    
     DETAILED DESCRIPTION  
       [0014]      FIG. 1  is a work machine  100  shown in relevant portion as a backhoe loader, that may be used for a wide variety of earth-working and construction applications. Although the work machine  100  is shown as a backhoe loader, it is noted that other types of work machines  100  having multiple linkages, e.g., excavators, front shovels, material handlers, and the like, may be used with embodiments of the disclosed system.  
         [0015]     The work machine  100  includes a work machine arm  102  having a boom  104 , a stick  106 , an extendable stick (E-stick)  108 , and a work implement  110 , all controllably attached to the work machine  100 . A boom cylinder  112  extends from the boom  104  to a body of the work machine  100  and is adapted to pivotally move the boom  104  with respect to the body of the work machine  100 . A stick cylinder  114  extends between the stick  106  and the boom  104  and is adapted to move the stick  106  with respect to the boom  104 .  
         [0016]     An E-stick cylinder  116  extends between the stick  106  and the E-stick  108 . The E-stick  108  and the E-stick cylinder  116  are contained within the stick  106  so that the E-stick  108  controllably slides, i.e., extends and retracts, relative to the stick  106 . The work implement  110  is pivotally connected to the E-stick  108  and is moved by a work implement cylinder  118 , extending from the E-stick  108  to the work implement  110 .  
         [0017]     Hydraulic cylinder valves, shown in  FIG. 2 , may control the extension and retraction of the hydraulic cylinders  112 ,  114 ,  116 ,  118 . A boom valve  208  may be associated with the boom cylinder  112 , a stick valve  210  may be associated with the stick cylinder  114 , an E-stick valve  212  may be associated with the E-stick cylinder  116 , and a work implement valve  214  may be associated with the work implement cylinder  118 . The position of valves  208 ,  210 ,  212 ,  214  may be controlled to coordinate the flow of hydraulic fluid to thereby control the rate and direction of movement of the associated hydraulic cylinder  112 ,  114 ,  116 ,  118 . It should be noted that the term “extension amount” represents both the amount of extension or retraction of the hydraulic cylinders  112 ,  114 ,  116 ,  118 .  
         [0018]      FIG. 2  shows a controller  200  for operating and controlling the movement of the work machine arm  102 . As described in greater detail below, the controller  200  may be adapted to move the components of the work machine arm  102  in an order that is based on a pre-selected priority of movement. For the purposes of this application, the term “pre-selected priority of movement” refers to a hierarchy of movement where the relative position of one or more of the hydraulic cylinders  112 ,  114 ,  116 ,  118  is changed only after another of the hydraulic cylinders  112 ,  114 ,  116 ,  118  is extended or retracted beyond a pre-designated position or amount. Accordingly, the pre-selected priority of movement prioritizes the movement of the boom cylinder  112 , the stick cylinder  114 , the E-stick cylinder  116 , and the work implement cylinder  118 . The cylinder with the higher priority is moved to or beyond a certain point before moving a cylinder with lower priority  
         [0019]     The controller  200  includes an input device  202  and a control module  204  for operating valves  208 ,  210 ,  212 ,  214  to control the position and movement of hydraulic cylinders  112 ,  114 ,  116 ,  118  on the work machine arm  102 . It may also include displacement sensors  216 ,  218 ,  220 ,  222  associated with, and adapted to monitor the position of the hydraulic cylinders  112 ,  114 ,  116 ,  118 . A mode selector  224  may also be associated with the control module  204 .  
         [0020]     The input device  202  could be a joystick, keyboard, lever, or other input device known in the art. Adapted to generate a desired movement signal, the input device  202  receives an input from an operator and sends it to the control module  204 . In the exemplary embodiment shown, the controller  200  includes a single input device for controlling the operation of the boom cylinder  112 , the stick cylinder  114 , the E-stick cylinder  116 , and work implement cylinder  118 . However, other input devices may be used to control the operation of one or more of the cylinders independent of the input device  202  and the pre-selected priority of movement.  
         [0021]     For example, in one exemplary embodiment, the input device  202  controls only the movement of the stick cylinder  114 , the E-stick cylinder  116 , and the work implement cylinder  118 . In this exemplary embodiment, the boom cylinder  112  is controlled by a separate input device for independent control of the boom  104 . Accordingly, in this embodiment, only the stick cylinder  114 , the E-stick cylinder  116 , and the work implement cylinder  118  are subject to the pre-selected priority of movement.  
         [0022]     The control module  204  may include a processor  205  and a memory device  206 . The memory device  206  may store one or more control routines or prioritized modes, which could be software programs, for controlling the work machine arm  102  based on the pre-selected priority of movement. The processor receives the input signal from the input device  202  and executes the routines or prioritized modes to generate and deliver a command signal to actuate the hydraulic cylinder valves  208 ,  210 ,  212 ,  214  that are associated with the hydraulic cylinders  112 ,  114 ,  116 ,  118  of the work machine arm  102  according to the pre-selected priority of movement.  
         [0023]     As shown in  FIG. 2 , a displacement sensor may be associated with each hydraulic cylinder. For example, a boom displacement sensor  216  may be associated with the boom cylinder  112 , a stick displacement sensor  218  may be associated with the stick cylinder  114 , an E-stick displacement sensor  220  may be associated with the E-stick cylinder  116 , and a work implement displacement sensor  222  may be associated with the work implement cylinder  118 . The displacement sensors  216 ,  218 ,  220 ,  222  may be used to measure the extension amount of the hydraulic cylinders  112 ,  114 ,  116 ,  118 . The displacement sensors  216 ,  218 ,  220 ,  222  may be in communication with the control module  204 , and may provide signals to the control module  204  indicative of the cylinder extension amounts. The control module  204  may monitor one or more of the displacement sensors  216 ,  218 ,  220 ,  222  at a single time, but does not need to monitor them all at the same time. The control module  204  may use the information received from the displacement sensors  216 ,  218 ,  220 ,  222  to prioritize and order movement of the work machine arm  102  based on the pre-selected priority of movement.  
         [0024]     In the exemplary embodiment shown, the controller  200  includes more than one control routine or prioritized mode. Accordingly, a mode selector  224  is provided in communication with the control module  204 . The mode selector  224  is an input device that allows an operator to select or choose from the available modes, and could be a toggle, joystick, dial, or any other input device known in the art. Accordingly, the operator can select the priority of movement of the work machine arm  102  that will provide the desired results for the work site.  
         [0025]     The work machine  100  may include any number of modes and each mode may be different and may be based upon a specific use or function of the work machine. For example, one exemplary mode may be a digging mode, where the pre-selected priority of movement requires that the stick cylinder  114  and the boom cylinder  112  be substantially fully extended before allowing movement of either the work implement cylinder  118  or the E-stick cylinder  116 . The priority of movement may allow simultaneous extension of the boom cylinder and the stick cylinder, or may require that they too be moved in order, based on the priority of movement.  
         [0026]     Other modes having a different pre-selected priority of movement may be used to accomplish other desired purposes. For example, in one exemplary mode, the pre-selected priority of movement prioritizes only the movement of the stick  106 , the E-stick  108 , and the work implement  110 . In this exemplary mode, the pre-selected priority of movement allows movement of the work implement cylinder  118  only after the stick cylinder  114  is extended or retracted beyond a designated point. And the E-stick cylinder  116  may be moved only after the work implement cylinder  118  is extended or retracted beyond a designated point. In this exemplary mode, the extension and control of the boom  104  may be operated independently of and outside of the pre-selected priority of movement. For example, control and operation of the boom  104  may be controlled separately through an input device specific to the boom  104 , such as a boom joystick.  
         [0027]     In another exemplary mode, only the stick cylinder  114  and the work implement cylinder  118  are controlled by the pre-selected priority of movement. Accordingly, the pre-selected priority of movement allows movement of the work implement cylinder  118  only after the stick cylinder  114  is extended or retracted beyond a designated point. In this exemplary embodiment, the movement of the E-stick cylinder  116  and the movement of the boom cylinder  112  may be independently controlled by, for example, a separate boom joystick and a separate E-stick joystick.  
         [0028]     In yet another exemplary mode, the pre-selected priority of movement controls only the stick cylinder  114  and the E-stick cylinder  116 . Accordingly, the pre-selected priority of movement may allow movement of the E-stick cylinder  116  only after the stick cylinder  114  is extended or retracted beyond a designated amount. In this exemplary mode, the boom cylinder  112  and the work implement cylinder  118  may be independently controlled and not based on the priority of movement. In any exemplary mode, the pre-selected priority of movement during retraction of the work machine arm  102  may or may not be the reverse of the pre-selected priority during extension of the work machine arm  102 . Other modes would be apparent to one skilled in the art.  
         [0029]     It should be noted that any mode may be adapted to include an optional transitioning feature for smoothly transitioning the movement from one hydraulic cylinder to the next hydraulic cylinder. This transitioning feature may be used to slow, or ramp down the velocity of one hydraulic cylinder when it is extended or retracted beyond the pre-designated position, while at the same time, ramping up the velocity of the next hydraulic cylinder. So doing provides a smooth transition between hydraulic cylinders as the work machine arm is operated.  
         [0030]      FIG. 3  is a block diagram  300  showing steps for moving the work machine arm  102  based on the pre-selected priority of movement. The flow chart  300  begins at a start step  302 . At a step  304 , an operator selects a mode on the work machine  100  using the mode selector  224 . The selected mode may be any routine or process that controls the movement of the work machine arm  102  using a pre-selected priority of movement.  
         [0031]     At a step  306 , the input device  202  generates a signal to change the position of the work machine arm  102 . The signal is sent from the input device  202  to the control module  204 . At a step  308 , the control module  204  determines the extension amount of the hydraulic cylinders  112 ,  114 ,  116 ,  118  on the work machine arm  102  based upon measurements taken and signals received from the respective displacement sensors  216 ,  218 ,  220 ,  222 . At a step  310 , the control module  204  adjusts the extension amount of one or more of the hydraulic cylinders  112 ,  114 ,  116 ,  118  on the work machine arm  102  according to the priority of movement for the mode, and further based upon the signal received from the input device  202 . At a step  312 , the flow chart  300  ends.  
         [0032]     The flowcharts of  FIGS. 4 and 5  illustrate an exemplary method of extending and retracting a work machine arm according to an exemplary pre-selected priority of movement.  
       INDUSTRIAL APPLICABILITY  
       [0033]     An exemplary mode is described with reference to  FIGS. 4 and 5 .  FIG. 4  illustrates a flow chart  400  detailing the extension of the work machine arm  102  from a carry position to a fully extended or a maximum reach position according to an exemplary pre-selected priority of movement.  FIG. 5  illustrates a flow chart  500  detailing retraction of the work machine arm  102  from the maximum reach position according to the exemplary pre-selected priority of movement. In the exemplary pre-selected priority of movement, the stick cylinder  114  has the first priority, the work implement cylinder  118  has the second priority, and the extendable stick cylinder  116  has the third priority. The boom cylinder  112 , in this exemplary embodiment, is operated independent of the pre-selected priority of movement. In this example, the pre-selected priority of movement for retraction is not the reverse of the pre-selected priority of movement for extension, but instead, the same pre-selected priority of movement is assigned to both extension and retraction of the work machine arm  102 . It should be noted that the same or different pre-selected priority of movements may be assigned to extension and retraction of the work machine arm  102 .  
         [0034]     The flow chart  400  begins at a start step  402 . At a step  404 , a signal is generated by the input device  202  to extend the work machine arm  102 . The control module  204  receives the signal at a step  406 , and monitors the positions of the hydraulic cylinders  114 ,  116 ,  118  associated with the work machine arm  102 , at a step  408 . This may be accomplished using the displacement sensors  218 ,  220 ,  222  that are associated with the hydraulic cylinders  114 ,  116 ,  118  and that send signals to the control module  204  indicative of the position or extension amount of the hydraulic cylinders  114 ,  116 ,  118 .  
         [0035]     In this exemplary embodiment of a priority of movement mode, the stick  106  has priority over the other components of the work machine arm  102 . Accordingly, the hydraulic cylinders associated with the E-stick  108  and the work implement  110  may not be extended or retracted until the stick cylinder  114  is extended beyond a pre-selected extension amount or point. The pre-selected point may be a position where the stick cylinder  114  is substantially fully extended. Thus, the control module  204  will extend the stick cylinder  114  to the pre-selected point before moving the E-stick cylinder  116  and the work implement cylinder  118 . If the stick cylinder  114  is not substantially fully extended, the control module  204  may not move the E-stick cylinder  116  and the work implement cylinder  118 . In one exemplary embodiment, a transitioning feature may slow, or ramp down, the velocity of one hydraulic cylinder, such as the stick cylinder  114  when it is extended or retracted beyond the pre-selected point, while at the same time, ramping up the velocity of the next hydraulic cylinder, such as the E-stick cylinder  116 , to smoothly transition between cylinders. This transitioning feature may be applied to any cylinder, whether extending or retracting.  
         [0036]     In this exemplary embodiment, and based upon the pre-selected priority of movement, the control module  204  determines whether the stick cylinder  114  is substantially fully extended, at a step  410 . If the stick cylinder  114  is not substantially fully extended, the stick cylinder  114  is further extended at a step  412 . As the stick cylinder is extended at step  412 , the position of the stick cylinder  114  is continually monitored at step  408 . Once the stick is moved to the pre-selected point or substantially fully extended at step  410 , other cylinders  116 ,  118  associated with the work machine arm  102  may be allowed to further extend the work machine arm  102  according to the pre-selected priority of movement. In this exemplary embodiment, if the stick is substantially fully extended at step  410 , the work implement  110  may then be moved by the work implement cylinder  118 .  
         [0037]     If at step  410  the work implement cylinder  118  is substantially fully extended, the pre-selected priority of movement allows movement of the work implement cylinder  118 . At a step  418 , the control module  204  determines whether the extension amount of the work implement  110  is substantially fully extended. It should be understood that due to the configuration of the exemplary work machine arm  102  shown and described with reference to  FIG. 1 , that when the work implement cylinder  118  is fully retracted, the work implement  110  is fully extended, or at a maximum reach with respect to the stick  106  and the E-stick  108 .  
         [0038]     If the work implement cylinder  118  is not fully retracted at a step  420 , the work implement cylinder  118  is further retracted. The position of the work implement cylinder  118  is continuously monitored at step  408  by the work implement displacement sensor  222  and the control module  204 . If the work implement cylinder  118  is fully retracted at step  420 , the E-stick cylinder  116  may be extended at a step  422 . Full extension of the E-stick results in the full extension of the work machine arm  102 , providing a maximum reach. Accordingly, at a step  424 , the extension ends. It should be noted that at any point during extension of the work machine arm  102 , the operator may stop the extension simply by eliminating the signal or generating a contrary signal at the input device  202 .  
         [0039]     The flow chart  500  of  FIG. 5  describes an exemplary method for retracting the work machine arm  102  from the fully extended position. The method described in flow chart  400  and the method to be described in flow chart  500  may be associated with the same mode, such as the digging mode.  
         [0040]     The flow chart  500  starts at a step  502 . At a step  504 , a signal is generated at the input device  202  to move the hydraulic cylinders  114 ,  116 ,  118  associated with the work machine arm  102 . At a step  506 , the control module  204  receives the signal from the input device  202 . Because this exemplary mode is a digging mode, at a step  508 , the work implement  110  may be set at a digging angle, such as, for example, 30° with respect to the ground. Further, because the pre-selected priority of movement may be employed with a system for coordinated movement, the work implement  110  may be maintained at the digging angle during the process described for retracting other components of the work machine arm  102 .  
         [0041]     At a step  510 , the positions of the hydraulic cylinders  114 ,  116 ,  118  are monitored by the displacement sensors  218 ,  220 ,  222 . At a step  512 , the control module  204  determines whether the stick cylinder  114  is substantially fully retracted. Because the stick cylinder  114  has the highest priority of movement, the control module  204  may not change the extension amounts of the E-stick cylinder  116  and the work implement cylinder  118  until the stick cylinder  114  is substantially fully retracted. If the stick cylinder  114  is not substantially fully retracted, at a step  514 , the stick cylinder  114  is retracted. Step  510  monitors the position of the stick cylinder to determine when the stick cylinder  114  is substantially fully retracted. According to the pre-selected priority of movement, at step  512 , after the stick cylinder  114  is substantially fully retracted, the work implement cylinder  118  may be moved next.  
         [0042]     At a step  520 , the control module determines whether the extension amount of the work implement cylinder  118  is fully extended. When the work implement cylinder  118  is fully extended, the work implement  110  is in a fully retracted position or, if the work implement is a bucket, the work implement  110  is in a fully curled position.  
         [0043]     If the extension amount of the work implement cylinder  118  is not fully extended, the position of the work implement cylinder  118  may be monitored by the work implement displacement sensor  222  and the control module at step  510 . If the work implement cylinder  118  is fully extended, the E-stick cylinder  116  may be retracted. When the E-stick cylinder  116  is fully retracted, the process ends at a step  526 .  
         [0044]     In the exemplary mode described with reference to  FIGS. 4 and 5 , the retraction priority is not the reverse of the extension priority. This is due to the desire during digging to minimize the use and extension of the E-stick cylinder based upon this exemplary pre-selected priority of movement.  
         [0045]     Further, although the exemplary embodiment of a digging mode described with reference to  FIGS. 4 and 5  includes a pre-designated cylinder position that is fully extended or retracted before other cylinders may move according to the priority of movement, such full extension or retraction is not required. In other embodiments, the cylinders need only be extended or retracted beyond any designated point to activate the next priority in the pre-selected priority of movement.  
         [0046]     Although in the exemplary embodiment describe above, the boom  104  is separately operated, and not controlled by the priority of movement, in another embodiment, the boom  104  is also controlled to the priority of movement of the present invention. Additionally, although the disclosed system is described with reference to a work machine arm  102  for digging, the pre-selected priority of movement may be used on other work machines, including, for example, excavators, shovels, telescopic material handlers, forklifts, etc. For example, if the work implement were pallet forks, the pre-selected priority of movement may operate to prevent tipping the pallet forks.  
         [0047]     In another example, the pre-selected priority of movement may be used to control a work machine arm during other work scenarios, including, for example, when the work implement  110  is a hydraulic hammer or a vibratory compactor. The pre-selected priority of movement may prioritize the movement of the stick  106  and E-stick  108 , and may be coordinated so that the hydraulic hammer or vibratory compactor is always vertical, with only the stick  108  and E-stick  110  being prioritized.  
         [0048]     Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims.