Abstract:
A system comprises a feed assembly for applying composite tape; a unit for forming lateral stripes across a portion of the tape that has been applied; a camera for capturing images of the lateral stripes; and a processor programmed to process the images of the lateral stripes to identify any discontinuities in the tape. Those stripes intersecting any discontinuities will make those discontinuities apparent.

Description:
[0001]    This is a division of copending U.S. Ser. No. 11/202,411 filed 11 Aug. 2005. 
     
    
     BACKGROUND 
       [0002]    Fabrication of a composite structure may include progressively building up a plurality of layers of thin composite tape or tow. For instance, a tape placement head of a manufacturing system moves over the surface of a template and deposits tapes of composite material onto the template. 
         [0003]    Irregularities in the deposited tape may be detected by an automatic monitoring system. During detection, a portion of the tape on the workpiece is illuminated, and images of the illuminated portion are processed to determine whether the deposited tape has any irregularities. Irregularities may include discontinuities (e.g., gaps) between a recently-applied portion of tape and a previously-applied portion of tape. 
         [0004]    The image processing may include edge detection and analysis. Such image processing is intensive. 
       SUMMARY 
       [0005]    According to an embodiment herein, a system comprises a feed assembly for applying composite tape; a unit for forming lateral stripes across a portion of the tape that has been applied; a camera for capturing images of the lateral stripes; and a processor programmed to process the images of the lateral stripes to identify any discontinuities in the tape. Those stripes intersecting any discontinuities will make those discontinuities apparent. 
         [0006]    According to another embodiment herein, a tape lamination machine comprises a forming tool; and a plurality of head assemblies for depositing composite tape on the forming tool. Each head assembly includes a feed assembly for applying composite tape, a unit for forming lateral stripes across a portion of the tape that has been applied, a camera for capturing images of the lateral stripes, and a processor programmed to process the images of the stripes to identify any discontinuities in the tape. Those stripes intersecting any discontinuities will make those discontinuities apparent. 
         [0007]    These features and functions may be achieved independently in various embodiments or may be combined in other embodiments. Further details of the embodiments can be seen with reference to the following description and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an illustration of a system for manufacturing composite components. 
           [0009]      FIG. 2  is an illustration of an inspection system of the manufacturing system of  FIG. 1 . 
           [0010]      FIG. 3  is an illustration of a head assembly of the manufacturing system of  FIG. 1 . 
           [0011]      FIG. 4  is an illustration of a vision unit of the manufacturing system of  FIG. 1 . 
           [0012]      FIG. 5  is an illustration of the vision unit of  FIG. 4 . 
           [0013]      FIG. 6  is an illustration of the vision unit of  FIG. 4 . 
           [0014]      FIG. 7  is an illustration of a portion of the manufacturing system including the head assembly of  FIG. 3 . 
           [0015]      FIG. 8  is an illustration of a portion of the manufacturing system including the head assembly of  FIG. 3 . 
           [0016]      FIG. 9  is an illustration of a system error file produced by the manufacturing system of  FIG. 1 . 
           [0017]      FIG. 10  is an illustration of a representative image provided by the vision unit of  FIG. 4 . 
           [0018]      FIGS. 11 and 12  are illustrations of the manufacturing system in first and second modes of operation in conjunction with a calibration plate. 
           [0019]      FIG. 13  is an illustration of the manufacturing system in operation on the workpiece of  FIG. 1 . 
           [0020]      FIG. 14  is an illustration of a method of performing manufacturing operations. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]      FIG. 1  illustrates a system  100  for manufacturing composite components. The system  100  includes a plurality of head assemblies  110  coupled to a translation platform  130  and operatively positioned proximate a forming tool (or template)  140 . The translation platform  130  is adapted to systematically move the head assemblies  110  along translation paths (e.g. three-dimensional paths) proximate the forming tool  140 , and each head assembly  110  is adapted to perform placement and consolidation of a fiber-reinforced composite tape material onto the forming tool  140  to produce a laminated composite workpiece  142 , as described more fully below. 
         [0022]      FIG. 2  illustrates a control system  150  of the manufacturing system  100  of  FIG. 1 . The control system  150  includes a machine controller  152  operatively coupled to the translation platform  130  and to the head assemblies  110 . The machine controller  152  is adapted to implement a control code that transmits control signals to the translation platform  130  and the head assemblies  110 . The control signals command the movement and functions of the translation platform  130  and the head assemblies  110 , thereby causing automated (or semi-automated) manufacturing of the laminated composite workpiece  142  on the forming tool  140 . In the embodiment shown in  FIG. 1 , the manufacturing system  100  is of a type known as a multi-head tape lamination machine (MHTLM). In one specific embodiment, the system  100  includes eight head assemblies  110  for the placement of composite tape, however, in alternate embodiments, any desired number of head assemblies  110  may be employed. 
         [0023]      FIG. 3  illustrates the head assembly  110  of the manufacturing system  100  of  FIG. 1 . The head assembly  110  includes a spindle  112  adapted to retain a roll  114  of a fiber-reinforced composite tape  115 , and a feed assembly  116  adapted to receive, guide, feed, and apply the tape  115  from the roll  114  onto the workpiece  142 . More specifically, the feed assembly  116  includes a feed roller  117  that receives the tape  115  from the roll  114 , and a compaction roller  118  that applies and compresses the tape  115  onto the workpiece  142 . The feed assembly  116  may include a variety of other components (e.g. motors, rollers, guides, sensors, etc.) adapted to cooperatively receive, feed, and guide the tape  115  from the roll  114  to the compaction roller  118 , as described more fully, for example, in U.S. Pat. No. 6,799,619 B2 issued to Holmes et al., and U.S. Pat. No. 6,871,684 B2 issued to Engelbart et al., as well as in U.S. Publication No. 20030102070 and U.S. Ser. No. 10/644,148, which is incorporated herein by reference. 
         [0024]    The head assembly  110  further includes a vision unit  160  adapted to perform in-process inspections of the manufacturing processes (in this case, composite tape application processes) performed by the head assembly  110 . 
         [0025]    As best shown in  FIGS. 3 and 6 , the vision unit  160  includes a camera  162  operatively positioned to view an area proximate the compaction roller  118  that includes the tape  114  as it is being applied and compressed onto the workpiece  142 . A vision computer (or other suitable processor)  164  is coupled to the camera  162  and is adapted to acquire and analyze an image provided by the camera  162  for irregularities. The vision computer  164  may, for example, be adapted to analyze the image to determine whether any possible irregularities or errors are present in the image, and make accept/reject decisions based on one or more predetermined criteria stored within the vision computer  164  or otherwise entered through a user interface, as described more fully below. 
         [0026]    As shown in  FIG. 2 , each vision computer  164  is coupled to a central computer  154  which, in turn, is coupled to the machine controller  152 . Communication between the vision units  160  and the central computer  154  may be accomplished by standard Ethernet connections, or alternately, by a custom network or server. Communication may also be achieved through a wireless network that utilizes spread spectrum RF to overcome sources of interference in a typical factory environment. 
         [0027]    With continued reference to  FIGS. 4-8 , the vision unit  160  also includes an encoder  166  that is driven by a drive belt  168  coupled to an encoder drive  170 . The encoder drive  170  operatively engages the compaction roller  118  so that as the compaction roller  118  rolls along the workpiece  142 , the encoder drive  170  drives the encoder  166  via the drive belt  168 . The encoder  166  provides position information to the vision computer  164  for coordinating the location of possible irregularities indicated by the vision computer  164 . As best shown in  FIG. 5 , two lighting sources  172  are laterally arranged on opposing sides of the encoder drive  170  for illuminating the area proximate the compaction roller  118  that is viewed by the camera  162 . A mirror  174  is centrally disposed between the lighting sources  172  and is positioned proximate the compaction roller  118 , and a laser  176  is positioned to project a laser line  178  through a portion of the area that is viewed by the camera  162 . The mirror  174  may be operatively positioned to enable the camera  162  to simultaneously image the tape  114  that is being placed by the compaction roller  118  as well as to detect change in the laser line  178  projected from the laser  176 . 
         [0028]    In operation, as the head assemblies  110  are operated to apply the composite tape  115  onto the workpiece  142 , the vision computers  164  monitor the application process, analyze the images in real time for possible manufacturing irregularities, and transmit the results of their image analyses to the central computer  154 . As note above, each vision computer  164  may be adapted to analyze the image to determine whether any possible irregularities are present in the image, and make accept/reject decisions. The vision computer  164  may use a variety of suitable methods and algorithms for determining whether irregularities are present in the image, and for making the accept/reject decisions, including, for example, those methods and algorithms disclosed in U.S. Pat. No. 6,871,684 issued to Engelbart et al. on Mar. 29, 2005, as well as those methods and algorithms disclosed in the following commonly-owned patents and applications, incorporated herein by reference: U.S. Pat. No. 7,171,033 by Engelbart et al., U.S. patent application Ser. No. 10/628,691 filed on Jul. 28, 2003, U.S. Pat. No. 7,289,656 by Engelbart et al., U.S. Pat. No. 7,424,902 by Engelbart et al., 2004, and U.S. Patent Publication No. 20060108048 by Engelbart et al. 
         [0029]    In one embodiment, the vision computers  164  transmit analysis results that indicate a possible manufacturing irregularity to the central computer  154 , but do not transmit analysis results if no manufacturing irregularities are indicated. Alternately, the central computer  154  may receive and maintain a running display of images (both with and without possible irregularities) as seen through the camera  162  of the vision unit  160 . For multiple head assemblies  110 , this may be accomplished by a split screen display that shows the view from each head assembly  110  simultaneously in discrete windows. It may also be done by displaying each head assembly  110  view individually through selection of that head assembly  110  from a list (e.g. as shown in  FIG. 10 ). 
         [0030]    Upon receipt of irregularity information, the central computer  154  may query the machine controller  152  for the coordinates (e.g. x-y coordinates) of the possible irregularity, and may also receive position information from the encoder  166 . The central computer  154  may then write the information regarding irregularities perceived by the vision computers  164  to a system error file  200 , and may archive the corresponding images from the vision computers  164 . 
         [0031]      FIG. 9  illustrates a representative system error file  200  produced by the central computer  154 . In this embodiment, the system error file  200  includes a plurality of error file entries  202 , which provide various information regarding the possible irregularity location (e.g. date, time, ply, course, frame, active program, current block, current head, coordinate information from the machine controller  152 , position information from the encoder  166 , etc.). In one particular embodiment, the central computer  154  maintains a running list of irregularity locations by machine coordinates, and at the end of each completed ply (or layer), the central computer  154  sends the running list to a laser projection system  156 . As shown in  FIGS. 1 and 2 , the laser projection system  156  may receive the information regarding possible irregularities from the central computer  154 , and may project an irregularity identifier  157  onto the workpiece  142 . The laser projection system  156  may include a processor that converts the machine coordinates for the purpose of locating and marking possible irregularities for detailed inspection and possible repair. The laser projection system  156  may be any suitable projection system, including those projection systems disclosed, for example, in U.S. Pat. No. 7,193,696. 
         [0032]    The central computer  154  may also archive the corresponding images from the vision computers  164 , as well as the related error file entries  202 , and make them available for subsequent viewing and inspection on a display device  158  ( FIG. 2 ). The display device  158  may be driven by the central computer  154 , or alternately, a secondary computer may be used to run the display device  158  in order to maintain the processing speed of the central computer  154  for data archiving tasks. 
         [0033]    In one embodiment, the images of possible irregularity locations from the vision computers  164  are provided to the display device  158  by selecting an appropriate error file entry  202  from the error file  200 . For example,  FIG. 10  is a representative screenshot  250  from the display device  158  that includes an image  252  provided by the vision unit  160  of  FIG. 4 . The screenshot  250  also includes a plurality of identifying data  254  corresponding to the error file entries  202  which provide information regarding the possible irregularity location. In this embodiment, a list  256  of head assemblies  110  is provided, allowing the image from each head assembly  110  to be viewed individually by selection of that head assembly  110  (e.g. Head  3 ) from the list  256 . 
         [0034]    The overall operation of the manufacturing system  100  will now be described with reference to  FIGS. 11 through 14 . The method  300  includes positioning the head assembly  110  proximate the forming tool  140  at a block  302 , initiating operation of the head assembly  110  at a block  304 , and initiating movement of the head assembly  110  using the translation platform  130  at a block  306 . At a block  308 , the fiber-reinforced composite tape  115  is applied to the forming tool  140  (or to the previously-applied layers of the workpiece  142 ). 
         [0035]    At a block  310 , inspections are performed with the vision unit  160  simultaneously with the application of the tape (block  308 ). More specifically, in a first mode of operation, the vision unit  160  is operated in a laser striping mode to detect gaps between a recently-applied portion of the tape and a previously-applied portion of the tape. As described more fully in the above-referenced issued patents and pending patent applications, in the laser striping mode of operation, the beam from the laser  176  is conditioned by a lens system to form a plurality of lateral stripes  182 . As shown in  FIG. 11 , the lateral stripes  182  are projected onto at least part of the area monitored by the camera  162 . In the example shown in  FIG. 11 , the lateral stripes  182  are projected onto the calibration plate  180 , however, during actual manufacturing operations, the lateral stripes  182  are projected onto the workpiece  142 , as shown in  FIG. 13 . A plurality of calibration grooves  184  are formed in the surface of the calibration plate  180  ( FIGS. 11 and 12 ). When the lateral stripes  182  intersect with one of the grooves  184 , a discontinuity (or jog, or gap indication)  186  in the lateral stripe  182  becomes apparent. Similarly, on the workpiece  142 , gaps which may occur between a recently-applied portion of the tape and a previously-applied portion of the tape also appear as gap indications  186 . During actual manufacturing operations, such gap indications  186  are detected by the vision computer  164  during analysis of the images acquired by the camera  162 , and corresponding error messages are generated to indicate that a gap has been detected. 
         [0036]    Alternately, during the inspections performed using the vision unit  160  (block  310 ), irregularities (including foreign objects and debris (FOD)) may be detected using a second or “illumination” mode of operation. Again, as described more fully in the above-referenced issued patents and pending patent applications, in the illumination mode of operation, the lighting sources  172  are activated to brightly illuminate the area monitored by the camera  162 . For example,  FIG. 12  shows the lighting sources  172  operating in the illumination mode of operation on the calibration plate  180 . The vision computer  164  analyzes the resulting images for discontinuities in reflected light intensity, and determines whether irregularities (e.g. bumps, ripples, etc.) are present on the calibration plate  180  (or on the workpiece  142 ) based on one or more predetermined criteria. The one or more predetermined criteria may, for example, be defined in terms of a presumed area. Any detected discontinuities in reflected light intensity having an area that meets or exceeds the presumed area may be classified as irregularities, and a corresponding error indicator message may be returned by the vision computer  164 . 
         [0037]    With continued reference to  FIG. 14 , at a determination block  312 , the method  300  determines whether the inspections performed using the vision unit (block  310 ) resulted in the detection of an irregularity. If not, the method  300  proceeds to the determination block  320  to determine whether manufacturing operations are complete. If manufacturing operations are not complete, the method  300  returns to the block  308  and continues the application of the fiber-reinforced composite tape, and the performance of the inspections (block  310 ), and repeats these operations as needed. 
         [0038]    Alternately, if an irregularity is determined at the block  312 , then at a block  314 , the irregularity-related information is output to the central computer  154  ( FIG. 2 ). At a block  316 , the projection system  156  may be used to illuminate the area of the possible irregularity, and at a block  318 , the area of the possible irregularity may be further inspected, analyzed, and repaired if necessary. The method  300  then proceeds to the determination block  320  to determine whether manufacturing operations are complete, and if not, the method  300  returns to the block  308  and continues the application of the fiber-reinforced composite tape, and the performance of the inspections (block  310 ), and repeats these operations as needed. If manufacturing operations are complete, then the method  300  terminates at the block  322 . 
         [0039]    Embodiments of systems and methods herein may provide significant advantages over prior systems and methods. For example, because the head assembly  110  includes its own dedicated vision unit  160  for performing inspections, in-process inspections may be performed simultaneously on different regions of the workpiece  142  as the head assemblies  110  are simultaneously performing manufacturing operations. The vision units  160  advantageously reduce downtime of the manufacturing system  100  by reducing or eliminating the need to shift inspection hardware between head assemblies  110 . Also, because the central computer  154  has been relieved of the tasks of image acquisition, image analysis, and decision making by the vision computers  164 , the central computer  154  is able to perform other tasks (e.g. archival tasks) relatively more rapidly in order to keep pace with the speed of material placement and inspection by the head assemblies  110 . 
         [0040]    It will be appreciated that a variety of embodiments in accordance with the present invention may be conceived, and that the invention is not limited to the particular embodiments described above and shown in the accompanying figures. For example, in alternate embodiments, the functions of the central computer  154  and the machine controller  152  ( FIG. 2 ) may be combined into a single computer. Similarly, the display  158  may be integrated with the central computer  154  or with the machine controller  152 . Of course, a variety of other embodiments may be conceived by combining various other components. 
         [0041]    Furthermore, embodiments herein may be used in a wide variety of manufacturing applications for manufacturing a wide variety of components for a wide variety of products. For example, in the manufacturing system  100  shown in  FIG. 1 , the forming tool  140  is adapted for forming an elongated, tubular workpiece  142 . In one specific embodiment, the workpiece  142  is a fuselage portion of an airplane, such as the  787  passenger aircraft commercially-available from The Boeing Company of Chicago, Ill. It will be appreciated, however, that alternate embodiments of the invention may be employed for the manufacture of composite components for a variety of other products, including other components for commercial and military aircraft, rotary wing aircraft, missiles or other types of flight vehicles, as well as components for boats, automobiles, trucks and other types of terrestrial vehicles, and any other desired structures. 
         [0042]    Furthermore, although the disclosed embodiments have been described as being adapted for the application and collation of fiber-reinforced composite tape, it may be appreciated that in alternate embodiments, head assemblies having vision inspection units herein may be equipped with other types of tools for performing other types of manufacturing operations. For example, in alternate embodiments, assemblies may include riveters, welders, wrenches, clamps, sanders, nailers, screw guns, mechanical and electromagnetic dent pullers, and virtually any other desired type of manufacturing tools and measuring instruments.