Abstract:
Disclosed are an optical system and method for centering a tree within a tree spade apparatus that is mounted to a vehicle. Typically, the center point of the tree spade is difficult to align with the axis of the trunk of the tree. The present embodiments describe a projected pattern of light incident upon the tree trunk that assists the operator of the tree spade in centering the spade around the tree without additional assistance.

Description:
BACKGROUND OF THE INVENTION 
   When transplanting trees or shrubs from one location to another, digging the plant in preparation for moving is typically the most challenging part of the job. Mechanical tree spades are commonly used to remove and replant trees. A typical tree spade includes a number of blades mounted in a circular or square fashion to form a single large circumferential spade. Typically, a spade will contain four blades, but variations exist with anywhere from three to eight blades. The blades are typically driven hydraulically into the ground and collapsed around the root ball of the tree. The tree can then be lifted out of the ground and transported to a desired position. 
   A major difficulty with this procedure is the centering of the tree spade around the root ball both laterally and front to back. Proper centering on the root ball is important because it provides the least damage to the root system and the best chance for the tree to thrive in the replanted location. Current methods either involve additional personnel to guide the spade into position or rely on elaborate, expensive and complicated sensor mechanisms that produce analog or digital signals which must be processed and displayed in a meaningful manner. 
   SUMMARY OF THE INVENTION 
   An embodiment of the present invention may therefore comprise a system for centering a tree spade on a tree comprising: at least one illumination device aimed towards a central axis, the central axis that is approximately equidistant from a plurality of digging blades of the tree spade; and, an illumination beam that is projected from at least one illumination device that produces a visible light pattern on a portion of the tree when the illumination beam is incident on the portion of the tree, the light pattern that provides an indication to an operator of the tree spade of the orientation of a longitudinal axis of the tree to the central axis. 
   An embodiment of the present invention may also comprise a method of centering a tree spade on a tree comprising: projecting at least one beam of light aimed towards a central axis, the central axis that is approximately equidistant from a plurality of digging blades of the tree spade; placing the tree spade such that at least one beam of light is incident on a portion of the tree; producing a light pattern on a portion of the tree that is visible to an operator of the tree spade with at least one beam of light; and, positioning the central axis of the tree spade to the longitudinal axis of the tree based upon the orientation of the visible light pattern on the portion of the tree. 
   Additional objects, advantages, and novel features of the invention are set forth in part in the description that follows and others will become apparent to those skilled in the art upon examination of the following description and figures or may be learned by practicing the invention. To achieve the foregoing and other objects in accordance with the purposes of the present invention, as embodied, and broadly described herein, 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and form a part of the specification, illustrate the preferred embodiments of the present invention, and together with the written description and claims, serve to explain the principles of the invention. In the drawings: 
       FIG. 1  illustrates an embodiment of an optical system for centering a tree within a tree spade. 
       FIG. 2  illustrates a configuration of an embodiment of an optical system for centering a tree within a tree spade. 
       FIG. 3  illustrates a configuration of an embodiment of an optical system for centering a tree within a tree spade. 
       FIG. 4  illustrates a configuration of an embodiment of an optical system for centering a tree within a tree spade. 
       FIG. 5  illustrates another embodiment of an optical system for centering a tree within a tree spade. 
       FIG. 6  illustrates a configuration of another embodiment of an optical system for centering a tree within a tree spade. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While this invention is susceptible to embodiment in many different forms, there is shown in the drawings and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not to be limited to the specific embodiments described. 
     FIG. 1  illustrates an embodiment of an optical system for centering a tree within a tree spade. As shown in  FIG. 1 , a tree  100  is to be dug up with a tree spade  104  that is mounted to a vehicle  107 . This vehicle  107  may be a truck, a front-end loader, a skid loader or skid steer loader, an excavator, a backhoe, a mini loader, or any other type of earth moving equipment or any other vehicle upon which a mechanical tree spade may be mounted. Typically, the desired center point of the tree spade  104  is based on the central vertical axis or tree centerline  110  of the tree trunk  102  of the tree  100 . 
   In this embodiment, the tree  100  to be transplanted is shown with a vertical tree centerline  110  that extends through the tree trunk  102  to the root ball  106  and is buried in the ground. In this instance, the tree spade comprises a plurality of blades  126  that are mounted within a frame  124 . The blades  126  are typically driven into the ground from a perimeter position by hydraulic actuators  128  that are held in position by supports  127 . When extended, the blades  126  separate a conical section of earth that encompasses the root ball  106  of the tree  100 . The entire tree spade  104  is then lifted by the vehicle  107  and the tree  100  may then be transported and stored or transplanted in a new location. 
   The tree centerline  110  is ideally placed coincident to the tree spade centerline z-axis  112  in order to encompass as much of the root ball  106  as possible, and to limit the amount of root damage or root sheering that can occur if the blades  126  of the tree spade  104  are driven into the root ball  106 . As can be seen from  FIG. 1 , if the tree spade  104  is not centered upon the tree trunk  102 , and accordingly, the blades  126  of the tree spade  104  are not centered on the root ball  106 , damage will occur to the root system of the tree  100  and the likelihood of survival upon transplantation is significantly decreased. 
   Because the tree trunk  102  is centered on the same axis as the root ball  106 , the tree trunk  102  can be used as a reference for the positioning of the tree spade  104 . Whereas this positioning has typically been performed either with a second person acting as a “spotter” to direct the positioning and operation of the vehicle  107  by an operator  108 , or the operator  108  must leave the vehicle  107  (often multiple times) to verify the position of the tree spade  104  to the tree trunk  102  before digging. Both of these options are very time consuming, expensive and/or impractical. 
   The present embodiment utilizes a plurality of optical illuminators  118  and  120  which are positioned in relation to, and/or mounted upon the tree spade  104 . These illuminators  118  and  120  produce an optical signal, i.e., a visible light beam  122 , which provided an indication to the operator  108  that the tree spade  104  is centered upon the tree trunk  102 , thereby also indicating that the tree centerline  110  is coincident with the tree spade centerline z-axis  112 , and that the root ball  106  will be centered within the cone of earth defined by the extended blades  126 . In this particular embodiment, a visible light source such as a commercially available laser generator, and in particular, multiple laser generators that produce a planar, fan shaped beam of light are utilized to project a pattern of light onto the tree trunk  102  that is visible to the operator  108  of the vehicle  107  that indicates that the tree spade  104  is in proper alignment with the tree  100  so that the root ball  106  may be extracted in an optimal fashion. 
     FIG. 2  illustrates a configuration of an embodiment of an optical system for centering a tree within a tree spade. As shown in  FIG. 2  from a top view, a tree trunk  102  is to be dug up with a tree spade  104  (such as that shown in  FIG. 1 ). In this particular embodiment, illuminator  118  is positioned on the upper portion of a left side support  127  of the hydraulic actuator  128  which provides the motive force to extend the blades  126  into the ground. A second illuminator  120  is positioned on the upper portion of a right side support  127 . As can be seen in the diagram, the left and right illuminators  118  and  120  are positioned parallel to the horizontal plane of the tree spade (normal to the tree spade centerline z-axis  112 ), and project light beams  122  and  123  respectively which are directed towards the center of the tree spade, also depicted in  FIG. 2  as the intersection of a spade y-axis centerline  116  and a spade x-axis centerline  114 . By utilizing fan shaped beams of light which are directed such that the plane of each light beam  122  and  123  are coincident to the tree spade centerline z-axis  112 . In this embodiment, the first illuminator  118  projects a first light beam  122  in a first plane and the second illuminator  120  projects a second light beam  123  in a second plane. The first plane and the second plane intersect along the tree spade centerline z-axis  112 . 
   When the tree spade  104  is placed around the tree trunk  102 , and the illumination devices are switched on, the light beams  122 ,  123  will each produce a line of light directed at the center of the spade. As the spade is moved into position, the beams will become incident upon the tree trunk and/or ground in front of the tree  100  to produce a pattern of lines on the tree trunk  102 . For example, as the spade is positioned with the tree  100  near the center, the planar laser lines will show up on the tree trunk  102  in the alignment zone  132  and become visible to the operator  108 . The operator  108  can then easily position the vehicle  107  (and thus the tree spade  104 ) by visual feedback on the tree trunk  102  as well as on the ground. The illuminators  118 ,  120  may also be positioned relative to the center of the tree spade  104  by using aiming strips  130  on the opposing supports  127 . For example, the left illuminator  118  can easily be focused on an aiming strip  130  positioned on the right side support  127  while the right illuminator  120  can be focused on another aiming strip  130  positioned on the left side support  127  thereby intersecting the two beams along the centerline z-axis. By utilizing aiming strips  130  that are positioned the length of the support  127 , the relative orientation of the light beams  122 ,  123  as well as the illumination devices  118 ,  120  can be readily adjusted and oriented. 
     FIG. 3  illustrates a configuration of an embodiment of an optical system for centering a tree within a tree spade. As shown in  FIG. 3  from a top perspective view, illuminator  118  projects a light beam  122  that is visible to an operator  108  of the tree spade  104 . In this example, the light beam  122  is a planar laser beam that shows up as a left illumination beam  132  projected as a vertical line down the length of the tree trunk  102 . Similarly, illuminator  120  projects a light beam  123  that is also visible to an operator  108  and also shows up as a right illumination beam  133  projected as a vertical line down the length of the tree trunk  102 . If the front surface of the tree trunk  102  is illuminated by a just single line, the operator knows that this surface is at the intersection of the spade y-axis centerline  116  and the spade x-axis centerline  114 . In order to then center the tree  100  within the tree spade  104 , the operator would only have to position the single beam approximately in the center (left to right) of the tree trunk  102 , and drive forward a distance approximately half the diameter of the tree trunk  102 . 
   Additionally, the relative distance of the tree spade centerline z-axis  112  to the tree centerline  110  (typically the hardest distance for a tree spade operator to judge) is easily and readily determined by the relative distance of the left illumination beam  132  to the right illumination beam  133  depicted as A and B in  FIG. 3 . As the operator  108  drives toward the tree  100  the illumination beams  132 ,  133  (lines) will either be converging (distances A and B increasing), meaning that the tree is on the other side of center, or the illumination beams  132 ,  133  will be diverging (distances A and B decreasing), meaning that the tree is on the near side of center. With immediate feedback, the operator can quickly and easily place the tree trunk  102  in the center of the tree spade  104  without additional personnel or without leaving the vehicle. 
     FIG. 4  illustrates a configuration of an embodiment of an optical system for centering a tree within a tree spade. As shown in  FIG. 4  from a top perspective view, illuminator  118  projects a light beam  122  and illuminator  120  projects a light beam  123  that are visible to an operator  108  of the tree spade  104  in the same manner as  FIG. 3 . In this example, a third illuminator  121  projects a light beam  125  along the spade x-axis centerline  114 . This beam is also visible to an operator  108  and can be projected as a vertical line down the length of the tree trunk  102  or as a single spot. In this manner, it may be easier for the operator to readily find the spade x-axis centerline  114 . Additionally, the illuminators may project beams that are of different colors so that the operator  108  may have additional optical feedback to assist them in positioning the spade with respect to the tree  100 . For example the left and right side illumination beams  130 ,  132  may utilize green laser light while the centerline illuminator  114  utilizes red laser light to produce a red center illumination beam  134 . 
     FIG. 5  illustrates an additional configuration of an embodiment of an optical system for centering a tree within a tree spade. As is similarly shown in  FIG. 3 ,  FIG. 5  shows a top view of the system where the illuminators  118 ,  120  are mounted near the bottom portion of the tree spade  104 . The frame  124  of the tree spade  104  in  FIG. 5  is a square configuration and is positioned much lower to the ground in this particular spade. In this instance, the illuminators  118 ,  120  are mounted directly to the frame  124  and are not positioned directly on the diagonal (i.e., 45 degrees from the spade y-axis centerline  116  and the spade x-axis centerline  114 ). As long as the illuminators  118 ,  120  are symmetrically aligned with respect to the coordinate axis (x-y-z  114 ,  116 ,  112 ) of the tree spade, the principals of alignment and positioning are the same. With the illuminators  118 ,  120  placed on the lower portion of the tree spade  104 , the shading provided by the tree  100  and spade itself allow the illumination to be seen with greater contrast. This ability to position the illuminators  118 ,  120  at various places within the system allows for greater versatility of the application. 
   For instance, the illumination system may be integrally designed into a tree spade as original equipment or the system may be applied as an aftermarket item that is readily adaptable to existing equipment. Likewise, the mounting of the components may be accomplished in a temporary manner with magnets, adhesives, hook and latch or temporary fasteners or the like, or the system can be permanently mounted by bolting, welding etc., with fine adjustment and aiming allowances. This versatility also allows the system to be used with a wide variety of spade devices and configurations. The system readily adapts to spades with varying numbers of blades and functions on front-mounted, rear-mounted and even non-vehicle mounted spades. 
   The powering of the illuminators  118 ,  120  can be by any means available at the site, such as dedicated, independent battery operation or the vehicle electrical system may be utilized. A simple switching mechanism, either wired or wireless can be adapted to wherever the operator is when performing digging operations. Typically, a simple on-off switch is positioned within the operator&#39;s compartment of the digging vehicle and illumination can be readily switched by the operator when needed. This switch can be a toggle type switch or can be a momentary switch to reduce power draw when the illumination is not needed. 
     FIG. 6  illustrates a configuration of another embodiment of an optical system for centering a tree within a tree spade. As is similarly shown in  FIG. 4 ,  FIG. 6  shows a top view which describes a system where three illuminators  118 ,  120 ,  121  are mounted near the bottom portion of the tree spade  104 . The frame  124  of the tree spade  104  in  FIG. 6  is a square configuration and is positioned much lower to the ground in this particular spade. In this example, a third illuminator  121  projects a light beam  125  along the spade x-axis centerline  114 . This beam is also visible to an operator  108  and can be projected as a vertical line down the length of the tree trunk  102  or as a single spot. The illuminators  118 ,  120 ,  121  in this embodiment may also be positioned relative to the center of the tree spade  104  by using aiming blocks  136 ,  138 ,  140  on the opposing side of the frame  124 . For example, the left illuminator  118  can easily be focused on the right aiming block  138  while the right illuminator  120  can be focused on the left aiming block  136 , and the center illuminator  121  can be focused on the center aiming block  140  thereby intersecting the three beams along the centerline z-axis. By utilizing aiming blocks  136 ,  138 ,  140  that are positioned, the frame  124 , the relative orientation of the light beams  122 ,  123 ,  125 , as well as the illumination devices  118 ,  120 ,  121  can be readily adjusted and oriented. 
   The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.