CA1258686A - Assembly system for seamed articles - Google Patents

Abstract

ABSTRACT

A limp material handling system includes a manipulating apparatus for selectively manipulating one or more layers of limp material on a support table. Folding is accomplished by lifting a curvilinear region of the material, reshaping that lifted region as desired, and lowering that lifted region to a curvilinear region on the support table.
A seamed article assembly system incorporates the manipulating apparatus, a seam joining apparatus and a multiple parallel endless belt system for tactile presentation of the limp material to the seam joining apparatus. An optical sensing system provides information representative of the position of the limp material being handled. A programmable computer, or controller, coordinates and controls the operation of the manipulating apparatus, seam joining apparatus, belt assembly, and optical sensing system to provide automatic assembly of seamed articles.

Description

~SSEMBLY SYSTEM FOR SEAMED ARTICLES

REFERENCE TO RELATED APPLICATIONS
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The subject matter of this application is related to that of UOS. Patent No. 4,401,044, entitled 5"5ystem and Method for Manufacturing Seamed Articles", and U.S. Patent No. 4,457,243 entitled "Automated Seamed Joining Apparatus", filed February 4, l9B3, and ~.S. Pa~ent No. 4,512,269, enti-tled "Automated Assembly System For Seamed 10 Articles", filed July 19, 1983.

BACKGROUND OF THE INVENTION

This invention relates to the assembly of seamed articles made from limp material, such as fabric. In particular, ~he invention relates to 15systems for au~omated, or computer-controlled, ~æsembly of seamed articles from limp material.

Conventional assembly line manufacture of seamed article6 construc~ed of limp ~abric consists of a series of manually con~rolled assembly operation~.
205enerally tactile presentation and control of the fabric-to-be-joined is made to the joining, or ~ewing, head under manual controll One drawbacX of ~his appli-cation techni~ue is that the technique i5 labor intensive; ~hat is, a large portion o ~he cost for 25manufacture is ~pent on labor. To reduce coRt, auto-mated or computer-controlled manufacturing techniques have been proposed in the prior art.

An automated approach to fabric presentation and control is disclo~ed in U.S. Patent NoO 4,457,243.
30-As ~here disclosed, pairs of belts assemblies are positioned on either side of a planar fabric locus. The respective bel~ assemblies are dri-ven to selectively provide relative motion along a reference axis to layers of fabric lying in the fabric 51Ocus. A joining, or sewing, head i~ adapted for motion adjacent to the abric locus along an axis per-pendicular to the reference axis. The respective belts main~ain control of the limp fabric in ~he region tra~
versed by the sewing head, with the respective belts lObeing selectively retrac~ed, permitting passage there-between of the sewing head as it advances along its axis of motion. With this approach, control of the limp fabric is permitted in the regions which are to be joined.

Systems ~or the manufact~re of seamed articles from a strip of limp abric disclosed in U.S. Patent No. 4,512,269 provide more precise "near ield" control of limp fabric, that i~
fabric control in regions close to the sewing head.
20Those systems include a feeder for selectively feeding these strips of limp fabric in the direction of a first (Y) reference axis. Control of pre~entation may also be maintained in a second (X) axis perpendicular t~ and intersecting the Y axls.

In some formsi a folding apparatus controls the position of the fabric ~o that the strip of fabric is folded onto itself along a fold axis offset from the axis of feed (Y axis) so that there is a folded portion having an upper layer overlying a lower layer. A sup-30port is used ~o position the upper and lower layers ofthe folded portion in a substantially planar fabric locus.

In one form of tho~P ~ys~ems, the 6upport includes a frame member, a support assembly coupled to ,~

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the feeder, and a drive motor and an associated linkage for selectively positioning the frame member with respect to the support assembly in the direction of the X axis. A pair of lower belt assemblies is coupled to 5the frame member, where each lower belt assembly inclu-des a plurality of continuous loop lower belts underlying the fabric locus. The lower belts are adapted on their outer, uppermost surface for fric-tional coupling with the lower layer of the folded por-lOtion. ~le lower belt assemblies are adjacentlypositioned along the X axis, with each assembly including an associated driver for ~electively driving the lower belts so that the lower fabric layer coupled to those belts is positionable in the direction of the 15X axis.

A pair of upper belt assemblies is coupled to the frame member as well. The upper belt assemblies are adapted to be positioned to overlie the lower belt assemblies. Each of the upper belt assemblies includes 20a plurality of upper belts (which may be positioned opposite the respective lower belts). The upper belts have planar lowermost portions spaced apart rom the uppermost of the lower belts. The upper belts are adapted on their outer, lowermost surface for fric-25tional coupling with the upper layer of the folded por-tion. Each of the upper belt assembiies has an associated driver for selectively driving those u~per belts so that the lower layer coupled to those belts is positionable in the direction of the X axis. The 30region between the lowermost portions of the upper belts and the uppermost portions of the lower belts defines ~he fabric locus, so that the fabric locus is substantially parallel to the plane formed by the intersecting X and Y axes.

In general, a computer-controller is used to selectively control the drivers or the respective _4_ ~5~
belts so that the upper and lower layers may be substantially independently positioned in the direction of the X axis along the fabric locus~ In alternative forms of those systems, the respective bel~ assemblies 5may be con~rollable in the Y axis direction as well, ~o that the upper and lower layers may be substantially independently positioned in the direction of both the X
and Y axes along the fabric locus, th~reby permitting control motion of the respective layers in those direc-lOtions.

A fabric joiner, or sewing head, includes anupper assembly and a lower assembly. These upper and lower assemblies are adapted for tandem motion along the direction parallel to the Y axis between ~he upper 15belt assemblies and the lower belt assemblies. An associated driver provides control of the position of the upper and lower assemblies of the joiner along its axis of motion. The joiner is selectively operable to form seams in fabric in the ~abri~ locu~ under the 20con~rol of a computer-controller.

In one form of the systems of those systems, at least one pair of ~he pairs of the adjacent belt assemblies includes opposing pairR of closed loop belts and an associated con~roller adapted so that the pairs 250f the closed loop belts are selectively retractable in the X direction ~o permit passage of the joining head therebetween in the Y direction, for examplet in the manner disclosed in V.S. Patent No. 4,457,243.

The joining head may include a needle assembly having a thread-carrying, elonga~ed needle extending along a needle reference axis perpendicular to the fabric locus. In operation, the needle i5 driven through ~he fabric locu~ in a reciprocal motion `~, A

along the needle reference axis. The needle assembly further includes an upper feed dog assembly which is responsive to an applied upper dog drive signal for selectively driving the uppermost layer of fabric in 5the region adjacent to the needle in the direction of an upper axis which is perpendicular to the needle reference axis.

A bobbin assembly is generally used in those systems and is adapted for interaction with the needle loassembly to form the stitches of the seam. The bobbin assembly includes a lower feed dog assembly which is responsive to a lower dog drive signal for selectively driving the lowermost layer of fabric in the region adjacent to the needle in the direction of a lower axis 15which is perpendicular to the needle reference axis.

In one form of those systems, a controller generates a part assembly signal representative of the desired position of the junction of the layers of fabric relative to those layers. Registration sensors 20provide signals representative of the current position of the respective uppermost and lowermost fabric layers. A controller provides overall control for the belt assemblies as well as the feed dogs and needle and bobbin assembly rotational and feed dog control, in 250rder to achieve coordinated motions of the respective assemblies. With this configuration, the respective belt assemblies provide far field, or global, position control for the upper and lower fabric layers. The feed dogs provide near field, or local, position 30control for the upper and lower layers of fabric in the regions near the needle of the joining head.

While the above-referenced systems do effec tively provide approaches for the automated assembly of seamed articles, there are limitations in those opera-1 ~ e --6--tions, particularly regarding the positioning, orienting an~ folding of limp fabric in preparation for joining of seams. Further, automated assembly systems require a feedback control system in order to 5accomplish these preparatory operations. In all such operations, it is important that accurate and repeated edge positioning of fabric be achieved in order to assure uniform quality of garment assembly. Moreover, these aspects are particularly important in view of 10desired high volume, and in view of the prior art requirement of specialized assemhlies, requiring pattern- and size- dependent clamps or fixtures.
Another factor for such automated assembly systems is that such systems must be cost efective compared with l~the existing approaches.

Accordingly, it is an object of the present invention to provide an improved system for automatic assembly ol seamed articles.

Another object is to provide an improved 20automated assembly system for seamed articles including a relatively low cost optical feedbacX system controlling fabric location and orientation.

Yet another object is to provide an improved folding apparatus for folding fabric in automated 25seamed article assembly systems.

SUMMARY OF THE INVENTION
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Briefly, the present invention is directed to a limp material handling system including a manipu-lating system for selectively manipulating one or more 301ayers of limp material. The manipulating system includes a support assembly adapted to support the material on a reference surface. The manipulating ~ 7--system further includes a selectively operable fold assembly which includes a gripping apparatus for mecha~
nically coupling to (or grapping or gripping) a cur-vilinear region of at least an uppermost layer of smaterial on the support surface, and an apparatus for contour controlling and positioning for that gripped region of material, and for releasing that gripped region. In forms of the inventon adapted for folding limp material, the fold assembly further includes lOapparatus for selectively lifting and lowering a gripped region of material, so that a lifted region may be lowered down to the reference surface or the next uppermost layer of material overlying that reference surface. The gripping and releasing apparatus, the 15contour controlling and positioning apparatus and the lifting and lowering apparatus are all selectively operable under control of a control apparatus, which is generally controlled by a microcomputer in the pre-ferred ! orms o the invention.

Generally, the fold assembly is operative to grip a curvilinear region of the material, then to control the curvature of that gripped curvilinear region so that the region has a selected contour, and to selectively translate and rotate that gripped region 25to a selected location overlying an associated cur-vilinear region of the reference surface, and then the material is released. To fold the material, a lifting operation for the gripped resion is interspersed with these operations. Then, that translated and/or rotated 30and/or reconfigured curvilinear region is lowered to the underlying associated curvilinear region of the reference surface, or onto material overlying that associated curvilinear region on the reference surface.

Particularly, in article assembly systems in 3saccordance with the invention, the system further 8~;

includes a seam joining apparatus, such as a sewing machine, which is selectively positioned along a reference axls. The seam joining apparatus is adapted to selectively join adjacent regions of one or more slayers of the limp material elements passing through that reference axis. The assembly system further includes a multiple parallel endless belt assembly, which is adapted to selectively transport and align the limp material in order to present that material to the lOseam joining apparatus at points on the first reference axis.

This belt assembly also provides selective orientation of the limp material elements to be joined.
The respective belts of the belt assembly are selec~
15tively controllable to provide a desired tension in the limp material elements in regions of the limp material adjacent to and including the first reference axis, so that seam joining occur under controlled tension~
Furthermore, the belts may be selectively driven in 200rder to reposition upper and lower layers of a multi-layer material at the sewing head in order to accomplish relative positioning of those layers, and further to provide capability to achieve easing and the generation of three dimensional seams.

All of these operations are provided under the control of an assembly controller which establishes the selected positioning, folding and joining of the limp material to assemble seamed articles.

In some forms of the invention, an optical 30sensing system provides optical feedback to the controller in order to ~ense the current position and various characteristics of the material which is being assembled into articles. The optical sensing system provides information representative of the edges of . .

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~9--such materials as well, so that the folding apparatus may operate to accomplish the desired manipulations and,~or folds by con~.rolling the positioning of the edges of the material in such a manner to achieve the 5desired manipulation and/or folding.

In one form of the invention, a particularly cost effective optical sensing system is provided by incorporating a television camera for generating video sisnals using a common axis illumination system. This 10configuration provides video signals representative of an image along the camera's optical axis of the reference surface and any limp material on that surface within the field of view of the camera. The reference surface provides a relatively high contrast optical 15reflectivity with respect to material positioned on that surface.

With this configuration, the article assembly system may construct seamed articles, such as garments, in a manner providing accurate and repeatable edge 20positionin~, thereby leading to highly uniform quality of garment assembly~ Particularly, the folding a~para-tus is well adapted to attaching to the limp material, picking that edge up, reshaping that edge as desired, and moving it and placing it down elsewhere on the sur-25face with substantially high accuracyO The reshapingof the edge permits matching to another edge of material already on the surface, so that the overlying edges may be then joined to form a desired seam, thereby permitting joining of dissimilarly-shaped 30edges.

BRIFF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects of this invention, the various features ~hereof, as well as the invention itself, may be more fully understood from the following description, when read together with the accompanying drawings in which:

Fig. 1 shows an isometric representation of 5the principal elements of an exemplary embodiment of the present invention:

Fig. 2 shows a partially cutaway view of a support table for the system of Fig. l;

Fig. 3 shows schematically the upper endless belts of the system of Fig. l;

Figs. 4A and 4B illustrate the opera~ion of the xetractable belts of the system of Fig. l;

Fig. 5 shows an iso~etric representation of an exemplary fabric folding system for use with the 15system of Fig. 1 Figs. 6A-6F illustrate the folding and sewing operations performed during the automated assembly of a sleeve by the system of Fig. l;

Fig. 7 illustrates the television camera and 200n-axis light source for the system of Fig. l; and Fig. 8 shows in block diagram form an e~:e;..~.~lary configuration for generating the position signals for use with the system in Fig. 1.

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DESCRIPTIO~ OF THE PREFERRED EMBODIMENT

Fig. 1 shows an isometric representation o~
principal elements of a preferred form of an assembly system 110 together with a set of intersecting 5reference coordinate axes X, Y and Z. The system 110 includes two support tables 112 and 114 and a seam joining assembly 116. The system 110 further includes an optical sensor system overlying table 112 and including a television camera 117 and a common-axis lOillumination system lI8. In alternative embodiments, an additional optical sensor system may similarly overlie table 114, for use in loading or unloading and orienting limp material elements, for example.

~ach of the support tables 112 and 114 inclu-15des a respective one of planar upper surfaces 112a and114a. In alternative e~bodiments, other or both of the surfaces 112a and 114a may differ from planar. For example, those surfaces may be cylindrical about an axis parallel to thè Y axis.

A set of parallel endless belts ~120 an 122) is affixed to each of tables 112 and 114. Each set of belts 120 and 122 is pivotable about a respective one of axes 120a and 122a each of which is parallel to the Y axis from a position substantially parallel to one of 25surfaces 112a and 114a (closed) to a position substan-tially perpendicular to one of those surfaces (open).
In Fig. 1, belt set 120 is shown in a partially open position, and belt set 122 is shown in a closed posi-tion substantially parallel to the top surface 114a of 30table 114.

Fig. 2 shows a partially cutaway view of the support table 112. l~at support table 112 as shown includes a perforated retro-reflective surface which ~
~ 12-forms the surface 112a. In the present embodirnent, the surface 112a iâ formed by retro-reflective material ~ype for example as manufactured by 3M Corporation, where that retro-reflective material forming the sur-5face 112a includes a rectangular array of holes, eachhole having a diameter equal to 1/32 inches, with the array having a center-to-center spacing of 1/16 inches.
In alternate embodiments, the array may be other than rectangular, for example, hexagonal or spiral or cir-lOcular with holes having a sufficient diameter and theadjacent holes of the array having center-to-center spacing appropriate to permit sufficient air mass flow therethrough to provide a suitable vacuum for holding limp material down to the surface. By the way of 15example, the array of holes in surface 112a may be established using a commercial laser.

In the presently described embodiments, the upper surface 112a overlies an aluminum plate having an array of holes which substantially matches the array o 20holes in the surface 112a. That aluminum plate 130 overlies a composite beam honeycomb table top 132 which includes an array of honeycomb tubular structures extending in the direction of the Z axis. That honeycomb table top 132 is supported over a multiple 25plenum valve module which provides selectively operable rows of valves. In Fig. 2, there are eight rows of valves shown, with 6iX of those rows in the open posi-tion and two of those ro~s in the closed position~ The valve module 134 is coupled to a vacuum blower 136 30which in turn is driven by a mo~or 138. With this con-figuration, a vacuum is selectively provided to various regions at surface 112a. The vacuum is particularly useful in holding various layers of material in a desired position on surface 112a. The positionin may 35 be accomplished by a material folding or by a material manipulator, for example. The surface 112a also has ~s~

retro-reflective optical properties so that with top lighting, reflective light is directed in the Z direc-~ion to provide a high contrast background against any cloth object placed on surface 112a. Th~ latter 5feature is particularly useful in systems ha~ing opti-cal sensors which can identify the location and orien-tation of material on surface 112a.

The sewing assembly 116 includes a sewing machine 140 adapted for linear rnotion along the Y axis.
10The sewing machine is also pivotable about its needle axis as driven by control 124 by ~ay of motor 142 and gear assembly 144. The sewing assembly 116 further includes an interlocking belt asse~nbly including a first set of parallel endless belts 150 and a second 15set of parallel endless belts 152. The belts of sets 150 and 152 are adapted so that their lower surface may frictionally drive material between those lower sur-faces and an underlying support surface 160 which is generally in continuous with ~urfaces 112a and 114a, 20un~er the control of the controller 1~4.

Fig. 3 shows the belt assemblies 120 150, 152, and 122, in schematic Eorm, together with the sewing machine 140, wherein the belt sets 150 and 152 include alternating sets of three roller endless belts 25and two point continuous belts. In operation, the controller 124 controls the belts adjacent to the sewing head of sewing machine 140 to be retracted from the locus of the needle while that needle is in the region between the belts. Otherwise, the belts of the 30Opposed sets 150 and 152 are adjacent to each other.
The belts may be driven by controller 124 in a manner providing controlled fabric tension for fabric between the lower surface of the belts of sets lSO and 152 and t-he upper surface 158. In various embodiments o~ the 35invention, the surface 158 may also include multiple 1~58~6 endless belt assemblies underlying respective belts of sets 150 and 15~. The latter belt sets are also controlled by the controller 1~4 in order to achieve substantially independent control of upper and lo~er slayers of fabric positioned between the sets of belts 150 and 152 and those sets underlying sets 150 and 152.

By way of example, the belts may be 0.03 to Q.04 inches thick, 3/8 inch wide neoprene toothed timing belts with polyester fiber reinforcement sup-lOported by toothed roller assemblies. A layer ofpolyurethane foam is attached to the outer belt ~ur-faces with adhesive. With this configurationt the foam provide substantial frictional contact with material adjacent to the bel~s so that as the belt moves, it 15positions the fabric adjacent thereto in the corresponding manner. For the upper belts the layer is 3/8 inches thick and for the lower belts the layer is 1/4 inches thick. The thicker layer provides increased adapability for materials characterized by varying 20thicknesses.

Fig. 4A shows two interlocking belts of the sets 150 and 152, where the sewing machine head 140a is positioned other than between these two belts. Fig. 4B
shows those same interlocking belts when the sewing 25head 140a is positioned between those two belts 150a and 152a. With the present embodiment, as limp fabric to be ~ewn is adjustably positioned between the belts of sets of 150 and 152 and the surface 160, the sewing machine 140 may be selectively controlled to traverse 30the gaps established by the retracting belts along axis parallel to the Y axis of machine 140 so ~hat selective stitching may be accomplished on that fabric, under the control of controller 124.

The system 110 further includes a material 35manipulation system for fabric on the support table 112. That manipulation system includes the controller 124, and a folding assembly 160. The folding assembly 160 includes a controllable arm portion 162 which is selectively movable in the Z direction and selectively 5rotatable about the axis 170. The folding assembly 160 includes a hinged, linearly segmented assembly 174.
That assembly includes three elongated segments 180, 182, and 184. Each of the segments 182 and 184 is selectively rotatable with respect to segment 180 about lOone of axes 190 and 192, so that the orientation of those segments 182 and 184 are selectively controlled with respect to the angular orientation of segment 180, all under the control of controller 124. The segment 180 is rotatable about the axis 186 under the control 15Of controller 124. Each of segments 180, 182 and 184 includes a plurality ~f gripping elements distributed along the principle axis of that segment.

The gripping elements are denoted in Fig. 1 by reference designation 180a, 182a and 184a. Each of 20the gripping elements is adapted for selectively gripping regions of any fabric underlying those ele-ments. The arm por~ion 162 is selectively controllable in the Z direction. As a result, when the gripping elements are afixed to a portion of the material, tha~
25portion may be selectively lifted and then lowered (in the Z direction) with respect to the surface 112a. In the present embodiment, the elements 180a, 182a and 184a are also each selectively movable in a direction parallel to the X-Y plane in the direction perpen-30dicular to the principle axes of the respective ones ofseg~ents 180, 182 and lB4. The gripping elements 180~, 182a and 184a are also selectively rotatable about an axis 186.

With this configuration, the folding assembly 35160 may be used as a material manipulator for material .~I./fz~S~

on surface 112a, whereby selective curvilinear portions of that material may be sequentially grabbed by the gripping elements, and then translated and/or rotated and/or reshaped, and then released. The folding sassembly 160 may also be used as a material folder by selectively performing the operations described for the manipulator, interspersed with lifting and lowering operations, particularly as described in ~onfiguration Figs. 6A-6F.

In one form of the invention, each of the gripping elements may comprise a substantially tubular member coupling a vacuum thereto, which may be selec-tively applied. Alternatively9 each of the gripping elements may include a grabber which comprises an 15elongated member extending along an axis perpendicular to the Z axis having a barb extending from the tip clo-sest to the surface 112a. In the latter embodiment, the elongated member, or barbed needles, may be selac-tively reciprocated in the Z direction under the 20control of controller 124.

FigO 5 shows an alternative embodiment 160' for the assembly 160 of Fig. 1. In t~at Fig. 5, corresponding elements are identified with identical reference designations. In Fig. 5, assembly 160 inclu-25des an elongated carrier assembly 210 having a cur-vilinear central axis 212 extending along its length.
Axis 212 is substantially parallel to surface 112aO In other embodiments, for example, where surface 112a is not planar~ the axis 212 may not be para~lel to surface 30112a. In the present embodimentD the carrier assembly 210 includes a hinged housing (including sections 214, 216 and 217) and a flexible member 218 which is coaxial with axis 212. One end of flexible member 218 is fixed to housing segment 214 at point 220 and the other end 3sis slidably coupled to housing segment 218 at point lZSB~86 ~17-

2~2. Forcers 230 and 232 are adapted to applying trans~erse forces -to member 218 at points between the end points to control the curvature of axis 212. As the forcers 230 and 232 control the orientation of the 5axis 212, each of the gripping elements may be selec-tively displaced to provide the desired orientation of the gripping elements. This embodiment in effect pro-vides a cubic spline. In other embodiments, differlng nu~bers of forcers may be used. In the assembly 160, lOflexible cubic ~or higher-order) splines may be used to position the gripping elements in any or all of segments 180, 182 and 184. J

With either configuration 160 or 160', the gripping elements may be selecti~ely driven to form a 15desired curvilinear contour over a portion of material on the table 112a The ~ripping elements 180a, 182a and 184a may be selectively lowered to the material on the table 112a so that those gripping elements may be activated to couple to tor "grab"~ the material at a 20corresponding curvilinear region of at least an upper-most layer of the fabric on the surface 112a. To par tially accomplish folding, the assembly 160 (or 160') may then be raised in the Z direction in a manner lifting that uppermost layer of the material.

The gripping element~ may then be translated and/or rotated, and repositioned (to modify the cur-vature of axis 212) so that the grabbed region of the uppermost layer of material is repositioned to a selec-tive location overlying a predetermined location over 30the surface 112a. The assembly 160 (or 160') may then be lowered so that the lifted material is adjacent to the surface 112a or overlying the material on surface on 112a. All of this operation is under the control of controller 124. The vacuum at surface 112a holds the 35material in position when that material is adapted to surface 112a.

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By selec-tively performing this operation over desired curvilinear regions of the material, a desired folding operation of the material may be a~tained.
Figs. 6A-6F show an exemplary folding sequence for 5asse~bling a sleeve. In that figure, a multilayer fabric assembly is first sewn (with easing) along the dotted line designatea 240 in Fig. 6Ao Tha~ assembly includes an in-sleeve portion 242 and an out-sleeve portion 244. Initially, the gripping elements 180a, lOlB2a and 184a may be positioned along th~ heavy lined portion of in-sleeve 242 denoted X in Fig. ÇA. That contour may be then picked up and translated, reshaped and lowered (and held with vacuum at the surface 112) so that the contour X is reshaped and positioned at the 151Ocation shown in Fig. 6B. With this configuration, the in-sleeve portion 242 has been folded about the axis A-A. The elements 180a, 182a and 184a may then release the material and the gripping elements may be rearranged to match the contour denoted Y in ~ig. 6B.
20That portion of the material may then be picked up by the gripping elements and the contour reshaped 50 that it is then repositioned and shaped as shown in Fig. 6C, with contour X overlapping contour Y0 As a result, the material assembly is then folded along line B-B. Then, 25contour Y is released and the elements 180ag 182a and 184a are controlled to grip the contour Z on portion 244 shown in Fig. 6C. That contour is then lifted and folded about line C-C as shown in Fig. 6D. Then con-tour Z is released and the gripping elements are con-30figured to grip contour W shown in Fig. 6D. Thatgripped contour is then folded about line D-D, as shown in Fig. 6E. The sleeve assembly is then presented to sewing head 140a.

By performing a tacking operation, the sewing 35head 140a as shown in Fig. 6F, the sleeve may be par-tially assembled. The material may then be translated ~'~5~ P
back out to th~ surface 112a, and the contour T of the out-sleeve 244 may be lifted by the assembly 160 tor 160') including elements 180a, 182a and 184a, and transferred and reconfigured to unfold about line C C
5and match the con~ours X and Y as shown in Fig. 6F.
The out-sleeve is then released from elements 180a, 182a and 184a, and the folded assembly is then trans-ferred by way of belts 120 and 150 to the sewing head 140a, where the elbow seam 240 is then joined. Thus, lOwith this configuration, the sleeve shown in Fig. 6F is assembled automatically under the control of controller 124. In all of these operations, the vacuum at surface 112a serves to hold material adjacent to that surface in place.

Figs. 7 and 8 show the components of the optical sensor system of the present embodiment. Fig.
7 includes an ~ptical sensor 117, and an illumination system 118. In the present embodiment, the sensor 117 is in the form of a conventional television camera, 20although other image signal generating devices may be used. The television camera 117 is supported so that its optical axis 117a is substantially normal to the surface 112a of the table 1120 The illumination system 118 includes a light source 260 and an associated beam 25splitter 262. The beam splitter is positioned on the axis 117a between the camera 117 and surface 112a.
That beam splitter 262, for example a mirror type beam splitter, is adapted to receive incident light from the light source 260 along path 260a, reflect a portion of 30that light along optical axis 117a to the surface 112a, and then to pass a portion of light reflected from sur-face 112a ~or material positioned on that surface) back along the axis 117a to the television camera 117.

With this illumination arrangement, common 35axis illumination is achieved for the system for use ~'~5~

~ith the r~tro-reflector configuration on surf~ce 112a.
The surface 112a may alternatively be forme~ by a translucent material which is backlit, or by a rluorescent surface (with appropriate filters for 5camera 117), although the retro-reflective common axis illumination app~oach is the preferred form for the present embodiment~

In operation, the camera 117 provides video signals representa~ive af the image along the optical lOaxis 117a of the surface 112 and any material thereon.
The retro~reflective surface 112a in effect provide a high contrast background with respect to any material on surface 112.

At t~e controller 124, these video siynals 15are processed to provide the position signals for use with the automatic seam joining and folding control portions of controller 124. Fig. 8 shows a block diagram of a portion of controller 124 which performs this function, in conjunction with the surface 112a, 20camera 117, and illumination source 118 and a video monitor 266. In the present embodiment, the controller 124 includes a type LSI-11/23 microcomputer, manufac-tured by Digital Equipment Corporation, Maynard, Massachusetts. Fig. 8 also shows the interface between 25the camera and illumination system and ~he LSI-11/23 computer.

In operation, the functional block of controller 124 in Fig. 8 performs edge detection of the material against the background provided by surface 30112a. The edge detection is performed by differen-tiating, or thresholding, the video signal generated by the camera 117 as the camera scanning beam sweeps across the image, marking the times within the sweep at which ~here is a predetermined change in video signal 5~

intensity. These various "edge" times for each scan line are provided to the computer upon request. ~y way of example, where the camera 117 is an RCA type TC1005/C49 came~a, the image of the table may be 5scanned in two seconds, and the edge information pro-vid~d to the microcomputer, together with some data checks and filtering on the raw data. Also within this time frame, the microcomputer computes the area of a material element in the field of view, the center of lOthat area, and the angle the principal axis of that material with respect to the a reference axis on sur-face 112a. Appendices A and B show an exemplary technique for performing these data processing operationsO

With this configuration, the ~elevision camera 117 provides an output signal from its video amplifier circuitry and uses a separately generated vertical sweep signal generated by a digital~to-analog converter controlled by the microeomputer in controller 20124. With this arrangement, the D/A controlled ver-tical sweep provides capability to increase a number o scan lines and also to correct for non-linearity in a relatively inexpensive camera yoke. The timing and control portion of the controller 124 converts the 25event detectors put into a series of digital words that contain a time of the event and the scan line number in which the event occurred. With this type system, a relatively high degree of edge resolution can be achieved ~ithout requiring the conventional type pixel-30image processing approach, and associated substantialcomputation cost and time. In alternative embodiments of the invention, the overall seamed article assemblies system may be configured with conventional type optical sensing system, although at relatively high cost com-35pared ~ith the particularly cost effective system shownin Figs. 7 and 8.

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-2~-The invention may be embodied in other speci-fic forms without departing from the spirit or essen-tial characteristics thereof. The present embodiments are therefore to be considered in all respects as Sillustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all change which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

,. , -~25~ 36 APPENDIX A

WorXpiece Recognition A. Sensor Information The camera scans the workpiece with respect to X-Y
5coordinates with the workpiece lying between X-coordinates O and XN with upper and lower limits XL and XH, respectively. Scan lines run parallel to Y-axis, separated by ax. Scan information consists of y-values for background-fabric transitions in the y-lOdimension, where Yl is the left edge transition and Y2 is the right edge transition in a scan line, The distance between left edge and right edge transitions for the ith scan line, ~Yi, is equal to Y2i-yli. The differential area for the ith scan line, d~i equals 5~i~Yi' or ty2i-yli~ dx, or dydx.

B. Computation Area A= ¦JdA

XN Y2~) = ~ ~ dydx O yl(X~

XN
lo [Y2(~) - yl~x)] dx XN
= ~ æX o~Y2(X) ~ Yl~X)]
N

= ~x ~ Yi i--O

~5~3~8~;

~entroid xc= - Jlx dA
A

XN y2(x) r ~ x dydx 'Yl (x) X~
f X[Y2 ( x ) -Yl ( x ) ~dx A '~

~x XN
_ ~ xty2(x) - Yl(X)]
A X=O

~x N
A 1=O

CentroidYc ~ y dA

X~ y~x) J I y dydx A O Yl ~x) ~ 3 dx A l 2 ¦Yl~X) XN r y22(X~ yl~(x, ax A O l 2 ~x XN
= ~ ~ ~y22 ( X) - yl2 ( 2A X=O

~x N
._ ~ (y22i - Y21i 2A i=O

. ~ ,~' ., ~ " .

:~ .

~S~8~j Moment IXX - J~y2 dA

JN Y2(X) 2 O l(X) XN r Y3 ~Y2~X)l dx Jo 3 yl(x X~ fy23(x) - yl3(x) ~ dx ~x XN
5 = ~ Y23~x) - yl3(x) ]

3 X=O

~x ~ 3 3 Y2i ~ Yli) 3 i=O

Moment Iyy = JJx2 dA

XN x2 dydx o Jyl(x) = ~N x2 [y2(x)--yl(x)3 dx O
XN
= ~ ~ X2 ~y2~X) ~ yl~x)]
X:o N

~)~ Z X2i~Yi ~,:o ~'~5~

Mc)merlt I xy -Jrxy dA

XN Y2 ( x ) ~l(X) ~N X ( ¦ ~x XN ~Y22(X) ~ yl2(x)7 dx = J Xl--~

= _ ~ x~y22(x~ _ yl2(x)]
2 X=O

x ~ ~ 22i - Y21i ) 2 i=O

, :: .

~;~513~

C. Principal Axis with Respect to Centroid Coordinate Frame -The next step is to convert the moments from the measurement into centroid frame, which is parallel to 5the original frame, but offset by ~le coordinates of the computed centroid. The converted moments are:

xx = Ixx ~ ycA

Iyy - Iyy - x~cA

Ixy = Ixy - XcycA

~ = - tan~l[ x~ Iyy~

where a' corresponds to the angular offset of the w~rk-piece centroid with respect to the principal axes.

D. Algorithm in BASIC

Below is shown all the BASIC language statemen~s 15that are necessary to implement the "moment calculations". Only eight multiplications and nine additions or subtractions are required in the high-frequency loop. YL and YR represent the values for the left and right profile, respectively, o the workpiece 20for each scan line.

100 FOR X = O TO XMAX STEP DX

200 READ YL, YR

i8~
-2~-210 DY = YR - YL
220 YRSQ = YR ~ ~R
230 YLSQ = YL * YL
240 DYSQ = YRSQ - YLSQ
250 YRCUB = YRSQ * YR
260 YLCUB = YLSQ * YL

300 SUMl = S~Ml + DY
310 SUM2 - SUM2 + X * DY
320 SUM3 = SUM3 + DYSQ
330 SUM4 = SUM4 + YRCUB - YLCUB
340 SUM5 = SUM5 + X * X * DY
350 SUM6 = SUM6 ~ X * DYSQ

~00 A = DX * SUMl 410 XC = DX ~ SUM2/A
420 YC = DX * S~M3/(2 * A) 440 IXX - DX * SVM4 / 3 450 IYY = DX * SUM5 460 IXY = DX * SUM6 / 2 480 IXX - IXX - YC * YC * A
490 IYY = IYY - XC * XC * A
500 IXY = IXY - XC * YC * A
510 Theta = 0.5 * ATAN((-2*IXY)/(IXX-IYY)) APPENDIX B
Sleeve Data Base The following information forms the "data base" for the machine, before each sewing or folding operation, for each sleeve size and styleO (Only the right or 35 1eft sleeve need be defined): ~
1. Nominal visual Area of worXpiece ~A) ~s~

2. Reasonable Tolerance for computed area (+ ~A) 3. Centroia correction as function of ar~a variation ( ~xc/~A ~ a Yc/ ~A )

4. With respect to a "sleeve" coordinate system (i.e., origin at centroid, x-axis along longitudinal principal axis):

A. Checkpoints (e.g. to identify left-vs. right-hand piece, verify measure-ment - expected coordina~es of intercept of centroid axes (~xc,Yc) and workpiece - reasonable tolerance for any detected edge (+ ~x, ~ ~y) B. Seam "trajectory"

- coordinates of first stitch (eOg. off leading edge) - number of individual stitches - individual stitch segments - ~x, ~y from previous stitch -maximum sewing machine speed over segment -easing rate over segment (standard material) -gap stretching rate over segment ~standard material) -feeddogs up-down flag -presser foot up-down flag C. Folding "trajectory"

The transformation from "plotting" to "centroid" coor-~ . .

~' 3~' ` '`

dinates involves a ~xc,Yc) offset, followed by a rota-tion by angle 0:
r coS~ -Sin~ 1 (X)C= r(X)p-(xc~yc)]~ ~
Sin~ Cos9 The transformation relationship for the stitch segments

5(Si - sj) is slightly different:
r COs0 -sine -( Q S)c = ( ~s)p I
L Sine cOse , To provide measurement and a First Reasonableness Test where both the workpiece and table coordinate frame visible within the camera field-of-view, the scan lOalgorithm is as follows:

1. For each scan linei d Yl, Y2 3 ~ Yn tn varies with shape) -If (Y2 -Yl) ~ ~ or (Yn~Y~ or if (Y3 -Y2)~ ~ or (Yn l~Yn-2)< ~ then - increment a count0r and use previous ~ Yi -For j = 3 to n-2, step 2 - ~Yi = ~Yi ~ ~Yj~l ~ Yj) ~Accumulate y's or Area computation.

~ .

~'~5~

2. Compute Area as ~x ~ ~ Yi i=l 3. Compare Ameas with ADB ~ ~ ADB

If not in interval, repeat measurement and incremént counter. If counter is beyond a threshold, alert operator.

E'or each scan line, partial sums can be accumulated for the centroid and principal angle:

For i = 1 to M

-Accumulate (i ~x) ~ Yi ~For xc) .
xi -Accumulate (i X)2 ~yi ~For Iyy) x2 -For j = 3 to n-2, step 2 -Accumulate (y2j+l _ y2j~ ~For Yc~

-Accumulate (y3 ~, j~l J) ~For IXx) ~z~

-Accumulate (i ~x) ~y2~ y2j3 (For Ixy) Using those partial sums, the centroid and principle angle can easily be calculated using the algorith~ described in Appendix A, that is:

N N n-2 xc = - ~ xi Yi, Yc = ~ ~ ~ 3 ~Y j~i ~ Y j) i=l i=l To pro~ide a Second Reasonableness Test and Right- vs. Left-Piece identification, even if the detected area, centroid, and principal angle seem reasonable, there may still be ~ome ambiguity whether a lO"righthand" or "lefthand" piece was loaded and scanned.

Unless the piece is exactly symmetrical about its two principal axes, the four predicted x, y inter-cepts with the piece edges can be checked to 1) ascer-tain whether a right- or left-handea piece was loaded 15and 2) perform a final reasonableness test.
In the present form, only "mirror" loading about the piece longitudinal axis is allowed; i.e., only the y+ and y intercepts str used to determine whether a right- or left~-handed piece was loaded. If 20the x+, x_ are not confirmed, the piece is rejected (or centroid corrected). Thus t the piece can not be loaded backwardsO

~51~ 6 Also, if the predicted XC, Yc in~ercepts are "close" and consistent with a slightly larger or smaller area, the centroid and principal angle is adjusted slightly to allow for miscut pieces or unpre-5dictable manual folding variations.

An exemplary algorithm is as follows:

1. Determine if predictable intercepts y~, y can be confirmed with actual camera data.

a. convert the x-components ¦in table coordinates) of y~ and y to a par-ticular scan line number (i.e., i+, i_~.

b. convert the y-components (in table coordinates~ of y+ and y to a particular camera y-displacement (i.e., ~ y+, y ).

c. Look at the raw camera data (or repeat the scan) for a y+ value (i.e., table-piece transition~ along scan line i~
and a y value along scan line i_. Use ~o a reasonable y for success criterion.

d. If concurrence results, proceed to Step 2.
If not, swap y+ and y_ and repeat Steps la-lc (look for concurrence for mirror-image around x axis).

e. If concurrence results from swapping the y's, then change the sign of the y-component for all trajectory points (i.e., start end of seam and y $or each stitch~.

f. If no concurrence again, ~hen stop and inform operator.

. Repeat Steps la-lc or x+ and x . If concurrence, preceed to Step 3, if not, stop and inform operator.

3. Correct the trajectory for the small differences between predicted and measured intercept values, using one of the following rules:
a. Xc = Xc ~ a xc/ ~ ~
YC Yc ~ ~Yc/ a ~ A
e = e + ae/ ~ ~ A

where ~x~/ a ~ A, etc. are empirical values from the data base.

Then use the new XC, Yc~ and e values to retransform the æewing/folding trajectory from centroid to table coordinates.

b. Use the (X~(act~a~ +(predict)) value to correct all positive x-coordinates of trajectories (i.e., beginning and ending of seams and folds, but not ~ x,~y of stitches).
This, if the detect~d x~ point falls further from the centroid than the predicted x+ point, "expand" the beginning or end of the trajectory further away from the centroid in the ~x direction.

Repeat similarly for the -x, +y, and -y directions~

The last step prior to ~ewing is to transform the 30stitch trajectory from table into sewing module (control~ coordinates.

~l~58~6 It's preferred to define the x sewing axis as ori-ginating from ~he sewing gap so that the velocity of the workpiece may change as it crosses the gap, due to different main motor and stretching motor rates. In 50rder to simplify sewing "navigation" equations, - (XTS, -YTS~ is subtracted from every non-stitch segment (i.e., non x, y) coordinate of the tra-jec~ory. This converts the centroid and seam start-end points into sewing coordinates.

- The sewing translator is slewed to the y-coordinate of the start of the seam.

- Simultaneously, the belts (and workpiece) are moved, continually keeping track Df the x-coordinate of the centroid (or the first stitch) in sewing coordinates as it decreases toward zero (approaches the needle).

n (Xc) sewing reaChes the value of (Sl(x) _ Xc) table l(x)sewing) (i.e., the start of ths first stitch passes under the needle), and/or the fabric is detected under the needle, then sewing commences by issuing ~x, ~ y commands to the belts and translator from the sewing trajectory.

- The x-position of the centroid (or first stitch) is continually be updated, so t~lat the piece can be brought back to the original position on ~he loading table (or taken to the proper position on the folding table) after sewing is completed~

- ~hen the centroid (or first stitch) passes across the sewing gap, its speed is goverened by ~he main motor and the stretching motor.

:' '

Claims (2)

1. A limp material handling system, comprising:

a limp material manipulating system for selectively manipulating one or more layers of limp material, comprising:

A. a support assembly adapted to support said material on a reference surface, B. a fold assembly including selectively operable:

i. means for gripping a curvilinear region of at least an uppermost layer of said material, ii. means for:

(a) controlling the curvature of said gripped curvilinear region whereby said gripped curvilinear region has a selected contour, (b) selectively translating and selectively rotating said gripped curvilinear region to a selected location overlying an associated curvilinear region of said reference surface, and iii. means for releasing said gripped curvilinear region to said associated curvilinear region of said reference surface or the next uppermost layer of said material overlying said associated curvilinear region of said reference surface, and C. a controller including means for selectively controlling said fold assembly, and further comprising:

an optical sensing system including means for generating position signals representative of the shape and orientation of said material on said reference surface, and including means for transferring said signals to said controller, wherein said controller is responsive to said position signals to control said fold assembly.

2. A limp material handling system according to claim 1 wherein said optical sensing system includes:

A. an optical sensor means for generating video signals and an associated means for supporting said sensor directing the optical axis of said sensor toward said reference surface from above said surface, said video signals being representative of an image along said optical axis on said reference surface and said material thereon, B. a plurality of retro-reflective elements on said reference surface, said retro-reflective elements being adapted to reflect light incident thereon along said optical axis back along said optical axis dispersed substantially about said optical axis, and C. a common axis illumination system including a directional light source and associated beam splitter, said beam splitter being positioned along said optical axis between said camera means and said reference surface, whereby at least a portion of light from said light source is directed along said optical axis toward said reference surface, and at least a portion of said reflected light passed through said beam splitter to said camera means, wherein said controller is responsive to said video signals to generate said position signals.