Sperical ball positioning apparatus for seamed limp material article assembly system

A sewing machine system for positioning and joining a multiple layer limp material workpiece, comprising:

• A. a seam joiner including a workpiece support surface for slidingly supporting said workpiece in a workpiece plane extending parallel to first (X) and second (Y) mutually perpendicular reference axes with a relatively low coefficient of friction, and including a reciprocating needle extending along a needle axis angularly offset from said workpiece plane, and an associated bobbin assembly and controller therefore including seam joining assembly for selectively joining overlying regions of said workpiece at said needle axis,
• B. first workpiece positioning means for selectively controlling the portion of said workpiece in the direction of said first axis,
• C. second workpiece positioning means for selectively controlling the position of said workpiece in the direction of said second axis,
• D. edge sensing means for generating a position signal representative of the relative position of a predetermined edge of said workpiece with respect to said needle in the direction of said first axis,
• E. a controller including:
• (1) means selectively operative for controlling said second workpiece positioning means to drive said workpiece past said needle in the direction of said second axis,
• (2) means responsive to said position signal for controlling said first workpiece positioning means to position said workpiece with said predetermined edge to be substantially at a predetermined distance in the direction of said first axis from said needle,
• wherein said first workpiece positioning means comprises:
• A. a spherical ball member having a diameter D,
• B. at least one drive wheel, each of said drive wheels having a diameter less than D,
• C. a housing including an open-ended interior cavity adapted to receive said ball member, and further including:
• a ball support assembly including means for captively supporting said ball member in said cavity with a spherical segment of said ball member extending from said open end and whereby said ball member is rotatable within said cavity, and
• a drive wheel support assembly including means for positioning each of said wheels so that its peripheral surface is in contact with said outer surface of said ball member, whereby the coefficient of friction between said peripheral surface of said wheel and said outer surface of said ball member is greater than the coefficient of friction between said sheet member and said work surface,
• D. a housing support including means for supporting said housing whereby said ball member, said drive wheels, and said housing are on the same side of said work surface and said spherical segment is positioned opposite and adjacent to said work surface with the coefficient of friction between the outer surface of said ball member and said sheet member being greater than the coefficient of friction between said sheet member and said work surface.

Apparatus for controlling the position of a member slidingly supported on a work surface with a relatively low coefficient of friction, comprising:

• A. a plurality of positioning assemblies, each of said positioning assemblies including:
• i. a spherical ball member having a diameter D,
• ii. at least one drive wheel, each of said drive wheels having a diameter less than D,
• iii. a housing including an open-ended interior cavity adapted to receive said ball member, and further including:
• a ball support assembly including means for captively supporting said ball member in said cavity with a spherical segment of said ball member extending from said open end and whereby said ball member is rotatable within said cavity, and
• a drive wheel support assembly including means for positioning each of said wheels so that its peripheral surface is in contact with said outer surface of said ball member, whereby the coefficient of friction between said peripheral surface of said wheel and said outer surface of said ball member is greater than the coefficient of friction between said sheet member and said work surface,
• iv. a housing support including means for supporting said housing whereby said ball member, said drive wheels, and said housing are on the same side of said work surface, and said spherical segment is resiliently positioned opposite and adjacent to said work surface, with the coefficient of friction between the outer surface of said ball member and said sheet member is greater than the coefficient of friction between said sheet member and said work surface.
• B. a position detector including means for generating position signals representative of the position of said sheet member on said work surface, and
• C. a controller including means for generating said control signals from said position signals and applied signals representative of a desired position of said sheet member on said work surface whereby said wheels drive said ball member to move said sheet member toward said desired position