Patent Publication Number: US-2010126293-A1

Title: Robotic radial tool positioning system

Description:
FIELD OF THE INVENTION  
     The present invention relates to the field of robotic tool positioning assemblies and, in particular, to a robotic tool positioning assembly having two or more arms each adapted to adjust the position of a respective tool along a semi-circular path. 
     BACKGROUND OF THE INVENTION  
     In the manufacturing industry, robotic systems are used to perform a variety of tasks, including positioning workpieces, positioning tools with respect to workpieces, and assembling workpieces using tools. In such systems, accurate positioning of the tool with respect to the workpiece is critical and is thus an important design consideration. Another important design consideration is minimizing the time required to complete any single manufacturing operation. For this reason, it is known to utilize two or more robotic tools to simultaneously perform a single manufacturing operation in order to reduce the time required to complete that manufacturing operation. However, since robotic tools are often large and heavy, it is often difficult to position and support two robotic tools with respect to one another such that a single manufacturing operation may be performed using two robotic tools simultaneously. This is especially true when the robotic tools must move relative to one another with respect to two or more axes during the course of the manufacturing operation. For example, when the robotic tools must install a plurality of components along a semi-circular arc, each tool must move independent of the other in the X direction and the Y direction. Furthermore, robotic tools are often only usable over a limited range of working heights, imposing further constraints on geometric designs of robotic tool positioning systems. Accordingly, there remains a need for a robotic tool positioning system that is capable of accurately positioning two or more robotic tools with respect to a workpiece, wherein the robotic tools are moveable independent of one another. 
     SUMMARY OF THE INVENTION  
     The invention provides a robotic tool positioning system for positioning a first tool and a second tool. The robotic tool positioning system includes an inner shaft, a first tool arm, a first drive assembly, a tubular outer shaft, a second tool arm, and a second drive assembly. 
     The inner shaft that extends from an upper end to a lower end, and has a stepped profile defined by an upper portion having a first diameter and a lower portion having a second diameter that is smaller than the first diameter. A first tool arm is connected to the lower portion of the inner shaft at the lower end thereof and extends radially outward therefrom. The first tool arm has a first tool supporting surface disposed at a tool elevation for supporting the first tool thereon. The first drive assembly is configured to rotate the inner shaft about a shaft axis to selectively position the first tool along a semi-circular path. 
     The tubular outer shaft extends from an upper end to a lower end and has a bore formed therethrough, wherein the lower portion of the inner shaft extends through the tubular outer shaft. The second tool arm is connected to the tubular outer shaft at the lower end thereof. The second tool arm has a second tool supporting surface disposed at the tool elevation for supporting the second tool thereon. The second drive assembly is configured to rotate the tubular outer shaft about the shaft axis to selectively position the second tool along a semi-circular path. 
     A stepped portion may formed on the second tool arm between an inner portion of the second tool arm and the second tool supporting surface of the second tool arm, wherein an upper surface of the inner portion of the second tool arm is disposed above the tool elevation. Furthermore, a diagonal shoulder may be formed on the second tool arm, the diagonal shoulder extending inward from the stepped portion toward an inner end of the second tool arm, wherein the diagonal shoulder of the second tool arm is configured to engage a side surface of the first tool arm to restrain the first tool arm against rotating past the second tool arm. 
     Alternatively, a stepped portion may be formed on the first tool arm between an inner portion of the first tool arm and the first tool supporting surface of the first tool arm, wherein an upper surface of the inner portion of the first tool arm is disposed below above the tool elevation. Furthermore, a diagonal shoulder may be formed on the first tool arm, the diagonal shoulder extending inward from the stepped portion toward an inner end of the first tool arm, wherein the diagonal shoulder of the first tool arm is configured to engage a side surface of the second tool arm to restrain the second tool arm against rotating past the first tool arm. 
     An inner end of the second tool arm may be disposed above an inner end of the first tool arm. 
     The tubular outer shaft and the upper portion of the inner shaft may be equal in diameter. 
     The first drive assembly may have a first worm gear connected to the upper portion of the inner shaft, a first worm that meshingly engages the first worm gear to rotate the inner shaft, and a first robotic drive mechanism connected to the first worm for providing torque thereto. The second drive assembly may have a second worm gear connected to the tubular outer shaft, a second worm that meshingly engages the second worm gear to rotate the tubular outer shaft, and a second robotic drive mechanism connected to the second worm for providing torque thereto. Furthermore, the first worm gear and the second worm gear may be equal in diameter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       Various other uses of the present invention will become more apparent by referring to the following detailed descriptions and drawings, and which: 
         FIG. 1  is a perspective view showing a robotic radial tool positioning system according to the present invention; 
         FIG. 2  is a top view showing the robotic radial tool positioning system according to the present invention; 
         FIG. 3  is a bottom view showing the robotic radial tool positioning system according to the present invention; 
         FIG. 4  is a front sectional view showing a first tool positioner and a second tool positioner of the robotic radial tool positioning system according to the present invention, wherein the first and second tool positioner are shown rotated into alignment with one another for clarity; 
         FIG. 5  is a top sectional view showing the first tool positioner and the second positioner of the robotic radial tool positioning system according to the present invention; 
         FIG. 6  is a perspective view showing a first tool arm of the first tool positioner according to the present invention; 
         FIG. 7  is a top perspective view of a second tool arm of the second tool positioner according to the present invention; 
         FIG. 8  is a bottom perspective view of the second tool arm of the second tool positioner according to the present invention; and 
         FIG. 9A  is a top view of the first tool arm and the second tool arm disposed in an adjacent position according to the present invention; and 
         FIG. 9B  is a top view of the first tool arm and the second tool arm disposed in a spaced position according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
     Referring to the drawings, the present invention will now be described in detail with reference to the disclosed embodiments. 
       FIGS. 1-3  show a robotic, radial tool positioning system  10  according to the present invention for selectively positioning a first tool  1  and a second tool  2  along a semi-circular arc. The first and second tools may be any type of industrial tool, such as a nut-runner. The tool positioning system  10  includes a first tool positioner  12  and a second tool positioner  14  that are connected to a carrier plate  16  by a framework  18 . The carrier plate  16  is configured to support the first tool positioner  12  and the second tool positioner  14 , and the tool positioning system  10  may be supported with respect to a workpiece (not shown) by a support structure, such as a robotically-positionable gantry system (not shown). The first tool positioner  12  is connected to a first tool arm  20  that supports first tool  1  for radial positioning of the first tool  1  about a shaft axis  11 . The second tool positioner  14  is connected to a second tool arm  22  that supports the second tool  2  for radial positioning of the second tool  2  about the shaft axis  11 . The first tool arm  20  and the second tool arm  22  support the first tool  1  and the second tool  2  at a constant radial spacing with respect to the shaft axis  11 . Thus, as the first tool positioner  12  and the second tool positioner  14  rotate the first tool arm  20  and the second tool arm  22 , the first tool  1  and the second tool  2  move along a semi-circular arc having its center at the shaft axis  11 . 
       FIG. 4  is a cross-sectional view showing the first tool positioner  12  and the second tool positioner  14 , wherein the first tool positioner  12  and the second tool positioner  14  are shown rotated into alignment with one another to allow for clarity of the figure. As seen in  FIG. 4 , the first tool positioner  12  provides radial positioning of the first tool  1  by including a first housing  30 , an inner positioning shaft  32 , and a first drive assembly  34 . The inner positioning shaft  32  is disposed at least partially within the first housing  30 . The first drive assembly  34  is operatively connected to the inner positioning shaft  32  for providing a drive torque to the inner positioning shaft  32  to cause rotation of the inner positioning shaft  32  about the shaft axis  11 . 
     The first housing  30  includes a first or top panel  36  and a second or bottom panel  38 , which are connected to the top and bottom ends, respectively, of a body  40  of the first housing  30 . An upper shaft opening  42  may be formed through the top panel  36  of the first housing  30  in substantial alignment with the shaft axis  11  to allow a portion of the inner positioning shaft  32  to extend upward out of the first housing  30 . Alternatively, the upper shaft opening  42  could be omitted, and the inner positioning shaft  32  could terminate within the first housing  30 , below the top panel  36  of the first housing  30 . A lower shaft opening  44  is formed through the bottom panel  38  of the first housing  30  to allow a portion of the inner positioning shaft  32  to extend downward out of the first housing  30 . 
     The inner positioning shaft  32  is substantially cylindrical, and extends from a first or upper end  52  to a second or lower end  54  of the first housing  30 . The inner positioning shaft  32  includes a first or upper portion  56  that meets a second or lower portion  58  at a shoulder  60  that extends substantially perpendicular to the shaft axis  11  and serves to change the diameter of the inner positioning shaft  32  and thus provide a stepped profile for the inner positioning shaft  32 . In particular, the upper portion  56  of the inner positioning shaft  32  is larger in diameter than the lower portion  58  of the inner positioning shaft  32 . 
     The first drive assembly  34  is operable to provide a drive torque to the inner positioning shaft  32  of the first tool positioner  12 . The first drive assembly  34  includes a housing  62 , a first worm gear  64 , a first worm  66 , a first drive shaft  68  and a first motor  70 , as shown in  FIG. 5 . To connect the first drive assembly  34  to the first housing  30  and interface the first drive assembly  34  with the inner positioning shaft  32 , a drive opening  46  is provided through a side wall of the body  40  of the first housing  30 . The housing  62  of the first drive assembly  34  is connected to the body  40  of the first housing  30  of the first tool positioner  12  adjacent to the drive opening  46  in the body  40  of the first housing  30 . 
     The first worm gear  64  is disposed on or fabricated integrally with the upper portion  56  of the inner positioning shaft  32 . Thus, the first worm gear  64  is disposed within the first housing  30  such that the teeth of the first worm gear  64  are radially arrayed around the shaft axis  11 . Accordingly, the first worm gear  64  rotates with respect to the shaft axis  11  in unison with the inner positioning shaft  32 . 
     The first worm  66  is disposed in operable engagement with the first worm gear  64 , and extends along a first drive axis  35  substantially perpendicular to the shaft axis  11 . The first worm  66  includes at least one tooth that encircles the first worm  66  in a substantially helical configuration for meshing engagement with the teeth of the first worm gear  64 . 
     In order to drive the first worm  66 , the first worm  66  is disposed on the first drive shaft  68 , which extends along the first drive axis  35 . The first drive shaft  68  is disposed both in the first housing  30  of the first tool positioner  12 , as well as in the housing  62  of the first drive assembly  34 , and thus passes through the drive opening  46  in the first housing  30  of the first tool positioner  12 . The first drive shaft  68  operatively connects the first worm  66  to the first motor  70  for torque transmission from the first motor  70  to the first worm  66 . The first motor  70  serves as a robotic drive mechanism, and thus may be any type of robotically controllable motor, such as an electronic stepper motor, that can be computer controlled according to a predetermined or dynamically generated program, or in response to operator commands. The first motor  70  may be coupled to the first drive shaft  68  by an appropriate fitting (not shown), by a bevel gear set (not shown), a belt drive (not shown), or any other suitable conventional structure. 
     Turning again to  FIG. 4 , the second tool positioner  14  provides radial positioning of the second tool  2  by including a second housing  80 , an inner positioning shaft  82 , and a second drive assembly  84 . The outer positioning shaft  82  is disposed at least partially within the housing  80 . The second drive assembly  84  is operatively connected to the outer positioning shaft  82  for providing a drive torque to the outer positioning shaft  82  to cause rotation of the outer positioning shaft  82  about the shaft axis  11 . 
     The second housing  80  includes a first or top panel  86  and a second or bottom panel  88 , which are connected to the top and bottom ends, respectively, of a body  90 . An upper shaft opening  92  may be formed through the top panel  86  in substantial alignment with the shaft axis  11  to allow a portion of the outer positioning shaft  82  to extend upward out of the second housing  80  and to allow the inner positioning shaft  32  of the first tool positioner  12  to extend into the second housing  80  and through the outer positioning shaft  82 . A lower shaft opening  94  is formed through the bottom panel  88  of the second housing  80  to allow a portion of the outer positioning shaft  82  and a portion of the inner positioning shaft  32  to extend downward out of the second housing  80 . In order to support the outer positioning shaft  82  within the second housing  80 , an upper bearing  98  and a lower bearing  100  are provided in the second housing  80  adjacent to the top panel  86  and the bottom panel  88 , respectively. 
     The outer positioning shaft  82  is generally cylindrical and tubular and extends from a first or upper end  102  to a second or lower end  104 . The outer positioning shaft  82  has a bore  106  that is substantially cylindrical and extends axially through the outer positioning shaft  82  along the shaft axis  11  of the tool positioning system  10 . The inner diameter of the bore  106  of the outer positioning shaft  82  is complementary to the outer diameter of the lower portion  58  of the inner positioning shaft  32 , such that the lower portion  58  of the inner positioning shaft  32  may be disposed at least partially within the bore  106  of the outer positioning shaft  82  and extend through the outer positioning shaft  82 . The maximum degree of axial insertion of the inner positioning shaft  32  into the bore  106  of the outer positioning shaft  82  is limited by engagement of the upper end  102  of the outer positioning shaft  82  with the shoulder  60  of the inner positioning shaft  32 . Furthermore, the outer diameter of the outer positioning shaft  82  may be substantially equal to the outer diameter of the upper position  56  of the inner positioning shaft  32 , which allows the first housing  30  and the second housing  80  to be identical in construction, since the geometric configuration of the inner positioning shaft  32  between the bearings  48 ,  50  of the first housing  30  is substantially identical to the geometric configuration of the outer positioning shaft  82  between the bearings  98 ,  100  of the second housing  80 . 
     The second drive assembly  84  is operable to provide a drive torque to the outer positioning shaft  82  of the second tool positioner  14 . The second drive assembly  84  includes a housing  112 , a second worm gear  114 , a second worm  116 , a drive shaft  118  and a second motor  120 , as shown in  FIG. 5 . To connect the second drive assembly  84  to the second housing  80  and interface the second drive assembly  84  with the outer positioning shaft  82 , a drive opening  96  is provided through a side wall of the body  90  of the second housing  80 . The housing  112  of the second drive assembly  84  is connected to the body  90  of the second housing  80  of the second tool positioner  14  adjacent to the drive opening  96  in the body  90  of the second housing  80 . 
     The second worm gear  114  is disposed on or fabricated integrally with the outer positioning shaft  82 . Thus, the second worm gear  114  is disposed within the second housing  80  such that the teeth of the second worm gear  114  are radially arrayed around the shaft axis  11 . Accordingly, the second worm gear  114  rotates with respect to the shaft axis  11  in unison with the outer positioning shaft  82 . The second worm gear  114  is substantially identical to the first worm gear  64 , and the first and second worm gears  64 ,  114  are of substantially equal diameter. 
     The second worm  116  is disposed in operable engagement with the second worm gear  114  and extends along a second drive axis  85  that extends substantially perpendicular to the shaft axis  11 . The second worm  116  includes at least one tooth that encircles the second worm  116  in a substantially helical configuration for meshing engagement with the teeth of the second worm gear  114 . The second worm  116  is substantially identical to the first worm  66 , and the first and second worms  66 ,  116  are of substantially equal diameter. 
     In order to drive the second worm  116 , the second worm  116  is disposed on the second drive shaft  118 , which extends along the second drive axis  85 . The second drive shaft  118  is disposed both in the second housing  80  of the second tool positioner  14 , as well as in the housing  112  of the second drive assembly  84  and thus passes through the drive opening  96  in the second housing  80  of the second tool positioner  14 . The second drive shaft  118  operatively connects the second worm  116  to the second motor  120  for torque transmission from the second motor  120  to the second worm  116 . The second motor  120  serves as a robotic drive mechanism and thus may be any type of robotically controllable motor, such as an electronic stepper motor, that can be computer controlled according to a predetermined or dynamically generated program, or in response to operator commands. The second motor  120  may be coupled to the second drive shaft  118  by an appropriate fitting (not shown), by a bevel gear set (not shown), a belt drive (not shown), or any other suitable conventional structure. 
     As shown in  FIG. 6 , the first tool arm  20  is a rigid, elongate member that extends from an inner end  130  to an outer end  132 . The first tool arm  20  has a generally rectangular configuration, including a top surface  134 , a bottom surface  136 , and side surfaces  138 . 
     The inner end  130  of the first tool arm  20  is configured to be connected to the inner positioning shaft  32  of the first tool positioner  12  such that the first tool arm  20  extends substantially perpendicular to the inner positioning shaft  32  of the first tool positioner  12 . In particular, a mounting aperture  140  extends through the first tool arm  20 , from the top surface  134  of the first tool arm  20  to the bottom surface  136  of the first tool arm  20 , at the inner end  130  thereof. Thus, the first tool arm  20  may be seated over the lower end  54  of the inner positioning shaft  32 . The first tool arm  20  is rigidly connected to the lower end  54  of the inner positioning shaft  32  of the first tool positioner  12  by any suitable fastening structure. Accordingly, rotation of the inner positioning shaft  32  in response to the drive torque provided by the first drive assembly  34  causes rotation of the first tool arm  20  around the shaft axis  11 . 
     The outer end  132  of the first tool arm  20  includes a first tool supporting surface  142  that is configured to support the first tool  1 . The first tool supporting surface  142  may be at substantially the same elevation as and substantially coincident with the top surface  134  of the first tool arm  20 . For example, the first tool supporting surface  142  of the first tool arm  20  may include a first tool aperture  144  that extends through the first tool arm  20  from the tool supporting surface  142  of the first tool arm  20  to the bottom surface  136  of the first tool arm  20 . The first tool aperture  144  is configured to supportably receive the first tool  1  at a predetermined elevation, and the first tool  1  may be fixed in position with respect to the first tool arm  20  by a friction fit, or by any suitable fasteners. However, it should be understood that the first tool aperture  144  is not necessary, in that other structures could be provided to support the first tool  1  at a predetermined elevation. 
     As shown in  FIGS. 7-8 , the second tool arm  22  is a rigid, elongate member that extends from an inner end  150  to an outer end  152 . The second tool arm  22  has a generally rectangular stepped configuration, including a top surface  154 , a second tool supporting surface  156  that is separated from the top surface  154  by a shoulder  158 , an inner bottom surface  160  that is separated from an outer bottom surface  162  by a diagonal shoulder  164 , and side surfaces  166 . 
     The inner end  150  of the second tool arm  22  is configured to be connected to the outer positioning shaft  82  of the second tool positioner  14  such that the second tool arm  22  extends substantially perpendicular to the outer positioning shaft  82  of the second tool positioner  14 . In particular, a mounting aperture  168  extends through the second tool arm  22 , from the top surface  154  of the second tool arm  22  to the inner bottom surface  160  of the second tool arm  22 , at the inner end  150  thereof. Thus, the second tool arm  22  may be seated over the lower end  104  of the outer positioning shaft  82 . The second tool arm  22  is rigidly connected to the lower end  104  of the outer positioning shaft  82  of the second tool positioner  14  by any suitable fastening structure. Accordingly, rotation of the outer positioning shaft  82  in response to the drive torque provided by the first drive assembly  34  causes rotation of the second tool arm  22  around the shaft axis  11 . 
     The second tool supporting surface  156  is disposed at the outer end  152  of the second tool arm  22  and is configured to support the second tool  2 . For example, the second tool supporting surface  156  of the second tool arm  22  may include a second tool aperture  170  that extends through the second tool arm  22  from the tool supporting surface  156  of the second tool arm  22  to the outer bottom surface  162  of the second tool arm  22 . The second tool aperture  170  is configured to supportably receive the second tool  2  at a predetermined elevation, and the second tool  2  may be fixed in position with respect to the second tool arm  22  by a friction fit, or by any suitable fasteners. 
     The second tool arm includes a stepped portion  172 , which is defined between the shoulder  158  and the diagonal shoulder  164 . An inner portion  174  of the second tool arm  22  is defined between the inner end  150  of the second tool arm  22  and the diagonal shoulder  164 , and has a substantially continuous elevation. The diagonal shoulder  164  begins outward of the mounting aperture  168  and extends at an angle, such as 30 degrees, with respect to the side surfaces  166  of the second tool arm. Thus, the width of the stepped portion  172  widens as the diagonal shoulder  164  progresses toward the outer end  152  of the second tool arm  22 . An outer portion  176  of the second tool arm  22  is defined between the outer end  152  of the second tool arm  22  and the shoulder  158 , and has a substantially continuous elevation. The shoulder  158  extends between the side surfaces  166  of the second tool arm  22  and may have a shape that is straight, arcuate, segmented or any combination thereof. The shoulder  158  may extends substantially perpendicular to the side surfaces  166  of the second tool arm, or at an angle thereto. 
     The elevation of the second tool arm  22  drops between the inner end  150  of the second tool arm  22  and the outer end  150  of the second tool arm  22  at the stepped portion  172 . The elevation of the second tool supporting surface  156  of the second tool arm  22 , which is located in the outer portion  176  of the second tool arm  22 , is substantially the same as or slightly lower than the elevation of the inner bottom surface  160  of the second tool arm  22 , which is located in the inner portion  174  of the second tool arm  22 . Additionally, the depth of the inner portion  174  of the second tool arm  22  and the depth of the outer portion  176  of the second tool arm  22  may be substantially equal. 
     As shown in  FIGS. 9A-9B , the first tool arm  20  and the second tool arm  22  move along a semi-circular path A between an adjacent position ( FIG. 9A ) and spaced positions ( FIG. 9B ). During movement of the first tool arm  20  and the second tool arm  22 , the first tool supporting surface  142  of the first tool arm  20  and the second tool supporting surface  156  of the second tool arm  22  remain at a common tool elevation to support the first tool  1  and the second tool  2  at the tool elevation throughout movement of first tool arm  20  and the second tool arm  22 . In a case where the first and second tools  1 ,  2  have a limited range of effective working heights, supporting the first and second tools  1 ,  2  at a common tool elevation allows maximum utilization of working range of both of the first and second tools  1 ,  2 . 
     The adjacent position is established when the first tool arm  20  is at a minimum angular spacing from the second tool arm  22 . However, the adjacent position may be established at any angular orientation of the first and second tool arms  20 ,  22  with respect to the carrier plate  16  or other fixed portion of the tool positioning system  10 . In the adjacent position, the first tool arm  20  and the second tool arm  22  are in a nested configuration, wherein a portion of the top surface  134  of the first tool arm  20  is directly adjacent to and facing the inner bottom surface  160  of the second tool arm  22 , and further wherein one of the side surfaces  138  of the first tool arm  20  is adjacent to and facing the diagonal shoulder  164  of the second tool arm  22 . Additionally engagement of one of the side surfaces  138  of the first tool arm  20  with the diagonal shoulder  164  of the second tool arm  22  prevents further movement of the first tool  1  toward the second tool  2 , thus preventing a collision of the first and second tools  1 ,  2 . 
     The spaced position is established when the first tool arm  20  is disposed at any angular spacing with respect to the second tool arm  22  that is substantially greater that the minimum angular spacing as dictated by engagement of one of the side surfaces  138  of the first tool arm  20  with the diagonal shoulder  164  of the second tool arm  22 . 
     In use, an operator may either manually or programmatically utilize the tool positioning system  10  to selectively position the first tool  1  and the second tool  2  along a semi-circular arc. To selectively position the first tool  1 , the operator actuates the first drive assembly  34  of the first tool positioner  12  to apply a drive torque to the inner positioning shaft  32 , which causes rotation of the inner positioning shaft  32 , the first tool arm  20 , and the first tool  1 . To selectively position the second tool  2 , the operator actuates the second drive assembly  84  of the second tool positioner  14  to apply a drive torque to the outer positioning shaft  82 , which causes rotation of the outer positioning shaft  82 , the second tool arm  22 , and the second tool  2 . 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments, but to the contrary, it is intended to cover various modifications or equivalent arrangements included within the spirit and scope of the appended claims. The scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.