Patent Publication Number: US-6990390-B2

Title: Method and apparatus to detect change in work tool

Description:
TECHNICAL FIELD 
   This invention relates generally to work machines and work machine implement controls and specifically to a method and apparatus to detect a change in a work tool. 
   BACKGROUND 
   Many work machines have work tools with engaging portions that wear or may come unattached in the course of performing their functions. For example, an excavator or a wheel or track type loader may have a bucket with attachable teeth. The teeth may be used to break up dirt or other material when the excavator or loader is digging. In another example, a cold planer may have a rotor with attachable teeth used to break up pavement. In still other examples a landfill or soil compactor may have protrusions on the wheels used to compact trash, an earthmoving machine such as a dozer or backhoe loader may have a ripper with ripper teeth or an agricultural tractor may pull a tillage tool with chisels or other protrusions or attachments. 
   The engaging portions on work tools may wear or become detached from the work tool such that the work machine is unable to perform its function. If the engaging portions become detached from the work tool other problems may occur on the worksite. For example if bucket teeth from a wheel or track type loader become detached at a quarry site and an unattached tooth goes through a rock crusher, the rock crusher may be damaged and mining operations may cease for a time. If wear or detachment occurs on the protrusions of the rotor on a planer or on the chisels on a soil tillage tool, the work these tools do may become uneven and may need to be repaired. 
   The operator of a work machine such as an excavator or loader may be able to visually check to ensure that engaging portions of a work tool have not become detached or are not worn such that they can no longer perform their function. This may be done while work is being performed. For example, an operator may visually check a bucket whenever visible from the cab. However, there are periods of time the operator may be unable to see the engaging portions of the work tool to ensure the engaging portions have not detached. In other circumstances environmental factors such as dust may inhibit visibility. On automated work sites where the work machine is automated or operated remotely, it may be impossible for an operator to visually inspect the work tool. 
   Tools on some work machines may have to be visually inspected at periodic intervals with the machine in a non-working state. For example the rotor on a cold planer may have to be manually inspected at the end of each shift or scythes on a combine may need to be periodically inspected. 
   U.S. Pat. No. 5,743,031 discloses an apparatus for providing a signal indicative of loss or imminent loss of digging hardware normally arranged in operable association with an earth working implement. However, the apparatus for providing the signal is located on the digging apparatus itself. In some work environments this apparatus may fail. In an autonomous worksite without an operator, the signal may not be seen or recognized. 
   It would be preferable to have an apparatus and method that overcomes one of these and other disadvantages. 
   SUMMARY OF THE INVENTION 
   In one aspect of the present invention an apparatus for detecting a change in a work tool is disclosed. The apparatus includes a work tool having one or more engaging portions for interacting with a work environment, a sensor and a control system. The one or more engaging portions of the work tool have a predetermined relationship with at least one of the work tool and another engaging portion of the work tool. The sensor is adapted to sense the predetermined relationship. The control system is adapted to produce an error signal in response to a change in the predetermined relationship greater than a predetermined value. 
   In another aspect of the present invention a controller configured to produce an error signal in response to a change in a predetermined relationship of at least one engaging portion of a work tool and at least one of the work tool and another engaging portion of a work tool greater than a predetermined value is disclosed. 
   In still another aspect of the present invention a method for detecting a change in a work tool is disclosed. The method includes determining an existing predetermined relationship between at least one engaging portions of a work tool and at least one of the work tool and another engaging portion of the work tool; comparing the existing relationship with a desired predetermined relationship of at least one engaging portion of a work tool and at least one of a work tool and another engaging portion of the work tool; and producing an error signal in response to detecting a change in the predetermined relationship between at least one engaging portion of the work tool and at least one of the work tool and another engaging portion of the work tool. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram depicting an apparatus for detecting a change in a work tool. 
       FIG. 2  is a flow chart depicting a method for detecting a change in a work tool. 
       FIG. 3  depicts an embodiment of the invention. 
       FIG. 4  depicts a work tool with engaging portions. 
       FIG. 5  depicts information from a sensor indicative of a predetermined relationship. 
       FIG. 6  depicts another embodiment of the invention. 
   

   DETAILED DESCRIPTION 
   While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     FIG. 1  shows a block diagram of an embodiment of the invention. It includes a work tool  10 , a sensor  12  and a control system  14 . The work tool  10 , sensor  12  and control system  14  may be located on a work machine  302  ( FIG. 3 ),  602  ( FIG. 6 ). The work machine may be a wheel loader, a track-type tractor, an excavator, a cold planer, a track-type dozer, an agricultural machine with a tillage tool, a backhoe loader, a combine, a soil or landfill compactor or any other work machine that could include the work tool  10 , sensor  12  and control system  14 . 
   The work tool  10  may be a bucket on an excavator, wheel loader, track-type tractor or backhoe loader. In an alternative embodiment it may be a rotor on a cold planer or a wheel on a landfill or soil compactor. In still other embodiments it may be a sickle on a combine, a tillage tool attached to an agricultural machine or a ripper on a dozer or backhoe loader. The work tool  10  may be an integral part of the work machine or it may be an optional attachment. In some embodiments, it may be pulled by the work machine such as a tillage tool pulled by an agricultural tractor. 
   The work tool  10  has one or more engaging portions  16  for interacting with a work environment. For example; the work tool  10  may be a bucket  304  ( FIG. 4 ) and may have one or more teeth  306  for digging into dirt, rock or other materials. In other embodiments a rotor may have protrusions for breaking apart pavement, soil or other materials or a wheel on a compactor may have protrusions to compact trash, soil or other materials. In still other embodiments, a tillage tool may have chisels for breaking apart soil, a ripper a tooth for breaking up soil or other materials, or a sickle on a combine may have serrated sections for cutting wheat, soybeans or other crops being harvested. 
   The one or more engaging portions  16  of the work tool  10  customarily have a predetermined relationship with at least one of the work tool  10  and another engaging portion of the work tool  16 . For example, a bucket may have six teeth that protrude a certain distance from the edge of the bucket, or a rotor may have eight rows of twelve protrusions, protruding a certain distance from the surface of the rotor, spaced five inches apart. In other embodiments, a compactor wheel may have ten rows of protrusions, spaced four inches apart, with six protrusions per row spaced five inches apart protruding a certain distance from the wheel surface, or a ripper may have a tooth protruding a certain distance from the ripper edge. In still other embodiments, a sickle on a combine may have multiple sections protruding a certain distance from an edge of the sickle or a tillage tool may have six rows of chisels spaced a certain distance from each other with each chisel protruding a certain distance from the chisel holder. 
   The sensor  12  is adapted to sense an existing predetermined relationship  26  between one or more engaging portions of the work tool  16  to at least one of the work tool  10  and another engaging portion of the work tool  16  and relay information indicative of the existing predetermined relationship  26  to the control system  14 . For example the sensor  12  may sense the distance that each tooth on a bucket protrudes from the bucket edge or it may sense the distance each rotor protrusion protrudes from the surface of the rotor. In alternative embodiments, the distance protrusions on a compactor wheel protrude from the wheel surface or the distance a ripper tooth protrudes from the ripper edge may be sensed. In still other embodiments, the distance a section protrudes from a sickle on a combine or the distance a chisel protrudes from a chisel holder on a tillage tool may be sensed. 
   The sensor  12  may be a laser scanner such as those produced by Riegl Inc., Optech, Inc. or Schwartz, Inc. In another embodiment the sensor  12  may be a radar scanner. In still other embodiments the sensor  12  may be a charge coupled device (CCD) or an infrared camera. 
   In an alternative embodiment the invention may include a plurality of sensors  12  that are adapted to sense the predetermined relationship. 
   The control system  14  has a memory  18  that stores a desired predetermined relationship  20  and a predetermined value  22 . The control system  14  is adapted to produce an error signal  24  in response to a change in the predetermined relationship greater than a predetermined value  22 . For example, the work tool  10  may be a bucket, the engaging portion  16  of the bucket may be six teeth, and the predetermined relationship may be the distance the teeth protrude from the edge of the bucket. In this embodiment, the control system memory  18  may store the desired predetermined relationship  20  of the six teeth each protruding five inches from the edge of the bucket. In another embodiment, if the work tool  10  is a rotor on a cold planer, the engaging portion  16  of the rotor is eight rows of twelve protrusions, spaced five inches apart and the predetermined relationship is the distance the protrusions protrude, the control system  14  may store the desired relationship  20  of the protrusions all protruding a distance of six inches from the rotor surface. In still another embodiment, if the work tool is a ripper, the engaging portion  16  of the ripper is a ripper tooth and the predetermined relationship is the distance the ripper tooth protrudes from the ripper, the control system  14  may store the desired relationship  20  of the ripper tooth protruding sixteen inches from the ripper. If the work tool  10  is a wheel of a soil or landfill compactor, the engaging portion  16  is ten rows of protrusions, spaced four inches apart, with six protrusions per row spaced five inches apart and the predetermined relationship  20  is the distance the protrusions protrude from the wheel surface, the control system  14  may contain a desired relationship  22  of each protrusion protruding six inches from the wheel surface. Other embodiments of desired predetermined relationships  20  will be obvious to one skilled in the art. 
   The control system  14  receives from the sensor  12  information indicative of the existing predetermined relationship  26 . For example, if the work tool  10  is a bucket, the engaging portion  16  of the bucket is six teeth, and the predetermined relationship is the distance the teeth protrude from the edge of the bucket, if one tooth becomes detached from the bucket and the other five teeth are still attached and unworn, the control system  14  will receive information from the sensor  12  indicative of the existing predetermined relationship  26  of five teeth protruding the desired distance from the bucket edge and one tooth protruding little if any distance from the bucket edge. In another embodiment, the work tool  10  may be a rotor on a cold planer, and the engaging portion  16  of the rotor may be eight rows of twelve protrusions, spaced five inches apart. The predetermined relationship in this example may be the distance the protrusions protrude. If there is no wear on the protrusions, the control system  14  may receive information indicative of the existing predetermined relationship  26  of the protrusions all protruding a distance of six inches from the rotor surface. 
   In still another embodiment, the work tool  10  may be a ripper and the engaging portion  16  of the ripper may be a ripper tooth. The predetermined relationship may be the distance the ripper tooth protrudes from the ripper and the normal protrusion may be sixteen inches. If the tooth has a broken tip, the control system  14  may receive information indicative of the existing predetermined relationship  26  of the ripper tooth protruding thirteen inches from the ripper. 
   The work tool  10  may be a wheel of a soil or landfill compactor and the engaging portion  16  may be ten rows of protrusions, spaced four inches apart, with six protrusions per row spaced five inches apart. The predetermined relationship may be the distance the protrusions protrude from the wheel surface. If two protrusions have worn two inches down and the remaining protrusions are worn one inch, the control system  14  may receive information indicative of an existing predetermined relationship  26  of two protrusions protruding four inches from the wheel surface and the remaining protrusions protruding five inches from the wheel surface. Other embodiments of existing predetermined relationships  26  will be obvious to one skilled in the art. 
   The control system memory  18  stores a predetermined value  22  that is compared to any change in the predetermined relationship. If the change is greater than the predetermined value  22 , the control system  14  produces an error signal  24 . For example, the work tool  10  may be a bucket and the engaging portion  16  of the bucket may be six teeth. The predetermined relationship may be the distance the teeth protrude from the edge of the bucket. The control system memory  18  may store the predetermined value  22  of one inch. If there is a change of more than one inch in the distance any tooth protrudes from the bucket edge between the desired relationship  22  and the existing relationship, the control system  14  will produce an error signal  24 . 
   In another embodiment the work tool  10  may be a rotor on a cold planer, and the engaging portion  16  of the rotor may be eight rows of twelve protrusions, spaced five inches apart. The predetermined relationship may be the distance the protrusions protrude. The control system memory  18  may store the predetermined value  22  of one half inch. If there is a change of more than one half inch in the distance any protrusion protrudes from the rotor surface between the desired relationship  20  and the existing relationship, the control system  14  will produce an error signal  24 . 
   In still another embodiment, the work tool  10  may be a ripper and the engaging portion  16  of the ripper may be a ripper tooth. The predetermined relationship may be the distance the ripper tooth protrudes from the ripper and the control system memory  18  may store a predetermined value  22  of two inches. If there is a change of more than two inches in the distance the ripper tooth protrudes from the ripper between the desired relationship  22  and the existing relationship, the control system  14  may produce an error signal  24 . 
   If the work tool  10  may be a wheel of a soil or landfill compactor and the engaging portion  16  may be ten rows of protrusions, spaced four inches apart, with six protrusions per row spaced five inches apart. The predetermined relationship may be the distance the protrusions protrude from the wheel surface, and the control system memory  18  may store a predetermined value  22  of one inch. If there is a change of more than one inch in the distance any protrusion protrudes from the wheel surface between the desired relationship  20  and the existing relationship, the control system  14  may produce an error signal  24 . The present invention contemplates other predetermined values  22 , selectable and known by those having ordinary skill in the art. 
   The error signal  24  may be used to produce an audible or visible alarm. It may be connected to a visual display for the operator. It may be transmitted to a remote site. The error signal  24  may be used to shut down or in some way alter a machine&#39;s operation. The present invention contemplates other ways to process the error signal  24 , so as to generate a perceivable indication to the operator which are known to those skilled in the art. 
   The control system  14  may include one or more controllers (not shown) located in the work machine. Alternatively the control system  14  may include one or more controllers located remotely or a combination of controllers located on the machine and remotely. 
   In some instances, the work tool  10  may be in a position such that the sensor  12  may not be able to accurately sense the predetermined relationship. For example, a laser scanning sensor may not be able to accurately detect the length of teeth on an excavator bucket if the bucket is currently digging. The control system  14  may be adapted to sense the position of the work tool  10  and the engaging portions of the work tool  16  and determine whether the sensor  12  is able to accurately sense the predetermined relationship. The control system  14  may also be adapted to position the work tool  10  such that the sensor  12  or a plurality of sensors  12  can accurately sense the predetermined relationship For example, if a laser scanning sensor is unable to accurately detect the length of teeth on an excavator bucket as the bucket is currently digging, the control system  14  may be adapted to move the bucket to a position where the laser scanner can accurately detect the length of the teeth. 
     FIG. 2  is a flow chart depicting an exemplary embodiment of a method for detecting a change in a work tool  10 . In block  202 , an existing predetermined relationship  26  between at least one engaging portion of a work tool  16  and at least one of the work tool  10  and another engaging portion of the work tool  16  is determined. The sensor  12  senses the existing predetermined relationship  26  and information indicative of the relationship is transmitted to the control system  14 . 
   In block  204 , the existing predetermined relationship  26  is compared to a desired predetermined relationship  20  between at least one engaging portion of a work tool  16  and at least one of the work tool  10  and another engaging portion of the work tool  16 . The control system  14  has a desired predetermined relationship  20  stored in the control system memory  18  and this is compared to the existing predetermined relationship  26 . 
   In decision block  206  a determination is made whether there has been a change in the predetermined relationship based on the comparison between the existing predetermined relationship  26  and the desired predetermined relationship  20 . If there has been a change, control passes to block  208 . If there has not been a change, the sequence ends. The control system  14  is adapted to determine whether there is a change between the existing and desired predetermined relationship  20 ,  26 . 
   In decision block  208 , a determination is made as to whether the change in the predetermined relationship is greater than the predetermined value  22 . If the change is greater than the predetermined value  22 , control passes to block  210 . If the change is not greater than the predetermined value  22  control goes to the end of the sequence. The control system  14  is adapted to make this determination. 
   In block  210 , an error signal  24  is produced; which may, for example, be generated by the control system  14  ( FIG. 1 ). 
     FIG. 3  depicts an embodiment of the invention including an excavator  302  having a bucket  304 , a sensor  12  and a control system  14 . The bucket  304  may include a plurality of teeth  306 . 
     FIG. 4  depicts the bucket  304  and bucket teeth  306 . The bucket  304  includes an edge  402 . A predetermined relationship exists between the bucket edge  402  and the end of each bucket tooth  306 . In this embodiment the predetermined relationship is the distance  404  between the bucket edge  402  and the end of each bucket tooth  306 . 
   Referring to  FIG. 3 , in an exemplary embodiment, the sensor  12  may be a laser scanning sensor such as those produced by Riegl Inc., Optech, Inc. or Schwartz, Inc. The sensor  12  may be capable of scanning objects in a defined area  308  and sensing the shape of objects in direct view of the sensor  12 , if other objects do not obstruct the direct view. 
     FIG. 5  depicts an electronic display indicative of bucket characteristics generated through the sensor  12  sensing the bucket  304 , the bucket teeth  306  and the distance between the edge of the bucket and the end of each bucket tooth  404 . 
   Referring to  FIG. 3 , the control system  14  is adapted to determine the position of the bucket  304 , including the bucket teeth  306 . The control system  14  may determine the position of the bucket  304 , including the bucket teeth  306 , through sensors that sense the position of hydraulic cylinders that move the work tool  10  (not shown) and the geometry of the excavator  302 . This method is well known to those of ordinary skill in the art. Other methods of sensing the position of the bucket  304 , which are contemplated by the present invention, are those known by those of ordinary skill in the art. 
   The control system  14  is adapted to determine if the bucket  304  is in the defined area  308  and if the sensor  12  has a view of the bucket  304  such that it can sense the distance  404  between the bucket edge  402  and the end of each tooth  306 . The control system  14  may be adapted to move the bucket  304  to a position in the defined area  308  such that the sensor  12  may sense the distance  404  between the edge of the bucket  402  and the end of each tooth  306 . 
   The control system  14  may include a memory  18  that stores a desired distance between the edge of the bucket  402  and the end of each tooth  306 . For example, this desired distance may be the distance between the edge of the bucket  402  and the end of each tooth  306  when a tooth  306  is first attached to the bucket  304 . 
   The control system  14  may be adapted to receive information from the sensor  12  indicative of the existing distance  404  between the edge of the bucket  402  and the end of each tooth  306 . Further, the control system  14  may be adapted to compare the desired distance between the edge of the bucket  402  and the end of each tooth  306  with the existing distance  404  between the edge of the bucket  402  and the end of each tooth  306 , and determine the difference for each tooth  306 . 
   The control system memory  18  may store an acceptable tooth length difference as a predetermined value  22 . The control system  14  may be adapted to compare the difference between the desired distance between the edge of the bucket  402  and the end of a tooth  306  and the existing distance  404  between the edge of the bucket  402  and the end of a tooth  306  with the accepted tooth length difference for each tooth  306 . If the difference between the desired distance between the edge of the bucket  402  and the end of a tooth  306  and the existing distance  404  between the edge of the bucket  402  and the end of a tooth  306  is greater than the accepted tooth length difference, the control system  14  may produce an error signal  24 . 
   The excavator  302  may have an operator display that displays a warning in response to the error signal  24 . In another embodiment the excavator  302  may have an audible alarm that sounds in response to the error signal  24 . In still another embodiment the excavator  302  may have a control system  14  that sends the error signal  24  to a remote location. Other responses contemplated by the present invention to the error signal  24  will be obvious to those of ordinary skill in the art. 
     FIG. 6  depicts another embodiment of the invention. This embodiment includes a track-type tractor  602 . The track-type tractor  602  may include a ripper  604 , a sensor  12  and a control system  14 . The ripper  604  may include a ripper tooth  606  and a ripper edge  608 . 
   The sensor  12  may be a radar scanning sensor. The sensor  12  may be capable of scanning objects in a defined area  610  and detecting the shape of the objects. 
   The control system  14  may determine the position of the ripper  604 , including the ripper tooth  606  and ripper edge  608 . The control system  14  may sense the position of the ripper  604 , including the ripper tooth  606  and ripper edge  608 , through sensors that sense the position of hydraulic cylinders that move the ripper (not shown) and the geometry of the track-type tractor. This method is well known to those of ordinary skill in the art. Other methods of sensing the position of the ripper  604  which are contemplated by the present invention are those known by those in the art. 
   The control system  14  may determine if the ripper  604  is in the defined area  610  such that the sensor  12  may sense the distance  612  between the ripper edge and the end of the ripper tooth  612 . The control system  14  may move the ripper  604  to a position in the defined area  610  in which the sensor  12  can sense the distance  612  between the edge of the ripper  608  and the end of the ripper tooth  606 . 
   The control system  14  may also include a memory  18  that stores a desired distance between the edge of the ripper  608  and the end of the ripper tooth  606 . This desired distance may be the distance between the edge of the ripper  608  and the end of the ripper tooth  606  when the tooth  606  was first attached to the ripper  604 . 
   The control system  14  may receive information from the sensor  12  indicative of the existing distance  612  between the edge of the ripper  608  and the end of the ripper tooth  606 . The control system  14  may compare the desired distance between the edge of the ripper  608  and the end of the ripper tooth  606  with the existing distance  612  between the edge of the ripper  608  and the end of the ripper tooth  606  and determine the difference. 
   The control system memory  18  may store an accepted tooth length difference as a predetermined value  22 . The control system  14  may compare the difference between the desired distance between the edge of the ripper  608  and the end of the ripper tooth  606  and the existing distance  612  between the edge of the ripper  608  and the end of the ripper tooth  606  with the accepted tooth length difference  22 . If the difference between the desired distance between the edge of the ripper  608  and the end of the ripper tooth  606  and the existing distance  612  between the edge of the ripper  608  and the end of the ripper tooth  606  is greater than the accepted tooth length difference  22 , the control system  14  may produce an error signal  24 . 
   The track-type tractor  602  may have a operator display that displays a warning in response to the error signal  24 . In another embodiment the loader may have an audible alarm that sounds in response to the error signal  24 . In still another embodiment the loader may have a control system  14  that sends the error signal  24  to a remote location. Other responses to the error signal  24  which are contemplated by the invention will be known to those of ordinary skill in the art. 
   INDUSTRIAL APPLICABILITY 
   The present invention provides an apparatus and method for detecting a change in a work tool  10 . A work machine  302  ( FIG. 3 ),  602  ( FIG. 6 ) on a work site may have a work tool  10 ,  304  ( FIG. 3 ),  604  ( FIG. 6 ) with ground engaging portions  306  ( FIG. 3 ),  606  ( FIG. 6 ) that may wear or become detached from the work tool  10 ,  304  ( FIG. 3 ),  604  ( FIG. 6 ). When the ground engaging portions of the work tool  306  ( FIG. 3 ),  606  ( FIG. 6 ) wear or become detached, the work may not be done correctly and may have to be repeated. Additional damage may be done and time wasted when a ground engaging portion such as a tooth  306  ( FIG. 3 ) on an excavator bucket  304  ( FIG. 3 ) becomes detached and damages other equipment on the work site. For example, a detached excavator bucket tooth  306  ( FIG. 3 ) may damage a rock crusher at a quarry. 
   The apparatus senses an existing predetermined relationship  26  such as the distance from the edge of an excavator bucket to the end of the bucket tooth  404  ( FIG. 4 ) and compares this to a desired predetermined relationship  20 . The apparatus produces an error signal  24  if the difference between the existing predetermined relationship  26  and the desired predetermined relationship  20  is greater than a predetermined value  22 . The error signal  24  may activate various alarms or displays to inform the operator that a work tool  10  has changed. 
   Other aspects, objects and features of the present invention can be obtained from a study of the drawings, the disclosure and the appended claims.