Systems and methods for in-process vision inspection for automated machines

Systems and methods for in-process vision inspection for automated machines are disclosed. In one embodiment, a head assembly includes a tool moveable over a workpiece and adapted to perform a manufacturing operation on the workpiece, and an inspection unit operatively positioned proximate the tool and moveable with the tool relative to the workpiece. The inspection unit is adapted to perform a vision inspection of a portion of the workpiece simultaneously with the performance of the manufacturing operation on the workpiece. In a particular embodiment, the inspection unit includes a camera adapted to monitor an area including the portion of the workpiece upon which the tool has performed the manufacturing operation, and a processor operatively coupled to the camera and adapted to receive an image from the camera and to analyze the image to determine a presence of a defect within the portion of the workpiece.

FIELD OF THE INVENTION

This invention relates to systems and methods for visual inspection, and more specifically, to systems and methods for in-process vision inspection for automated machines, including automated multi-head composite tape placement machines and the like.

BACKGROUND OF THE INVENTION

Composite structures are commonly manufactured by progressively building up the structure with a plurality of layers of thin composite tape (or tow) laid one layer upon another. Typically, the operation begins by laying one or more tapes onto a starting template or tool that has a configuration generally corresponding to the desired shape of the article to be produced. A tape placement head of a manufacturing system moves over the surface of the template, guiding the one or more tapes of composite material onto the template. The head usually makes repeated passes over the template in a defined pattern until the composite material is entirely collated, building up successive layers of the composite tape to form the desired workpiece. A compaction roller is typically used for pressing the tape against the workpiece, thereby facilitating adhesion of the successive layers. The workpiece may then be subjected to a curing process (e.g. heating) to further adhere and bond the composite layers. Conventional systems for forming composite structures using successive layers of tape include those systems disclosed, 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.

Although desirable results have been achieved using such prior art systems, there may be room for improvement. For example, inspections to ensure the quality of the composite components manufactured using the above-described systems may require downtimes which reduce the production rate and efficiency, and increase the overall cost, of the manufacturing process. Novel systems and methods which reduce or eliminate the downtime associated with inspections during the manufacture of composite components would therefore have utility.

SUMMARY OF THE INVENTION

The present invention is directed to systems and methods for in-process vision inspection for automated machines. Embodiments of systems and methods in accordance with the present invention may advantageously perform in-process inspections simultaneously on different regions of a workpiece, and may reduce downtime and associated costs, in comparison with the prior art.

In one embodiment, a head assembly adapted to perform a manufacturing operation on a workpiece includes a tool moveable over the workpiece and adapted to perform the manufacturing operation on the workpiece, and an inspection unit. The inspection unit is operatively positioned proximate the tool and moveable with the tool relative to the workpiece. The inspection unit is adapted to perform a vision inspection of a portion of the workpiece upon which the tool has performed the manufacturing operation simultaneously with the performance of the manufacturing operation on the workpiece. In a particular embodiment, the inspection unit includes a camera adapted to monitor an area at least partially including the portion of the workpiece upon which the tool has performed the manufacturing operation, and a processor operatively coupled to the camera and adapted to receive an image from the camera and to analyze the image to determine a presence of a defect within the portion of the workpiece. In alternate embodiments, the vision inspection includes a defect detection process including at least one of a striping process and an illumination process.

DETAILED DESCRIPTION

The present invention relates to systems and methods for in-process vision inspection for automated machines, including automated multi-head composite tape placement machines and the like. Many specific details of certain embodiments of the invention are set forth in the following description and inFIGS. 1-14to provide a thorough understanding of such embodiments. The present invention may have additional embodiments, or may be practiced without one or more of the details described below.

Generally, embodiments of systems and methods in accordance with the present invention provide a vision unit operatively coupled with a head assembly adapted to perform a desired manufacturing operation, such as applying a fiber-reinforced composite tape onto a template to form a composite laminate workpiece. The vision unit advantageously performs visual inspections of the manufacturing operation during the performance of the manufacturing operation by the head assembly. Thus, embodiments of the invention advantageously reduce the labor and expense associated with performing inspections during manufacturing operations, including the manufacture of composite components, improving the production rate and efficiency, and reducing cost, in comparison with the prior art systems and methods.

FIG. 1is an isometric view of a system100for manufacturing composite components in accordance with an embodiment of the invention. In this embodiment, the system100includes a plurality of head assemblies110coupled to a translation platform130and operatively positioned proximate a forming tool (or template)140. The translation platform130is adapted to systematically move the head assemblies110along translation paths (e.g. three-dimensional paths) proximate the forming tool140, and each head assembly110is adapted to perform placement and consolidation of a fiber-reinforced composite tape material onto the forming tool140to produce a laminated composite workpiece142, as described more fully below.

FIG. 2is a schematic representation of a control system150of the manufacturing system100ofFIG. 1. In this embodiment, the control system150includes a machine controller152operatively coupled to the translation platform130and to the head assemblies110. The machine controller152is adapted to implement a control code that transmits control signals to the translation platform130and the head assemblies110. The control signals command the movement and functions of the translation platform130and the head assemblies110, thereby causing automated (or semi-automated) manufacturing of the laminated composite workpiece142on the forming tool140. In the embodiment shown inFIG. 1, the manufacturing system100is of a type known as a multi-head tape lamination machine (MHTLM). In one specific embodiment, the system100includes eight head assemblies110for the placement of composite tape, however, in alternate embodiments, any desired number of head assemblies110may be employed.

FIG. 3is a side elevational view of the head assembly110of the manufacturing system100ofFIG. 1. In this embodiment, the head assembly110includes a spindle112adapted to retain a roll114of a fiber-reinforced composite tape115, and a feed assembly116adapted to receive, guide, feed, and apply the tape115from the roll114onto the workpiece142. More specifically, the feed assembly116includes a feed roller117that receives the tape115from the roll114, and a compaction roller118that applies and compresses the tape115onto the workpiece142. The feed assembly116may include a variety of other components (e.g. motors, rollers, guides, sensors, etc.) adapted to cooperatively receive, feed, and guide the tape115from the roll114to the compaction roller118, 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 co-pending, commonly-owned U.S. patent application Ser. Nos. 09/998,478 and 10/644,148, which patents and pending patent applications are incorporated herein by reference.

The head assembly110further includes a vision unit160adapted to perform in-process inspections of the manufacturing processes (in this case, composite tape application processes) performed by the head assembly110.FIG. 4is an enlarged, isometric view of the vision unit160ofFIG. 3.FIGS. 5 and 6are elevational views, andFIGS. 7 and 8are partial isometric views, of the vision unit160coupled to the other portions of the head assembly110.

As best shown inFIGS. 3 and 6, the vision unit160includes a camera162operatively positioned to view an area proximate the compaction roller118that includes the tape114as it is being applied and compressed onto the workpiece142. A vision computer (or other suitable processor)164is coupled to the camera162and is adapted to acquire and analyze an image provided by the camera162for defects. The vision computer164may, for example, be adapted to analyze the image to determine whether any possible defects or errors are present in the image, and make accept/reject decisions based on one or more predetermined criteria stored within the vision computer164or otherwise entered through a user interface, as described more fully below.

As shown inFIG. 2, each vision computer164is coupled to a central computer154which, in turn, is coupled to the machine controller152. Communication between the vision units160and the central computer154may 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.

With continued reference toFIGS. 4-8, the vision unit160also includes an encoder166that is driven by a drive belt168coupled to an encoder drive170. In this embodiment, the encoder drive170operatively engages the compaction roller118so that as the compaction roller118rolls along the workpiece142, the encoder drive170drives the encoder166via the drive belt168. The encoder166provides position information to the vision computer164for coordinating the location of possible defects indicated by the vision computer164. As best shown inFIG. 5, two lighting sources172are laterally arranged on opposing sides of the encoder drive170for illuminating the area proximate the compaction roller118that is viewed by the camera162. A mirror174is centrally disposed between the lighting sources172and is positioned proximate the compaction roller118, and a laser176is positioned to project a laser line178through a portion of the area that is viewed by the camera162. The mirror174may be operatively positioned to enable the camera162to simultaneously image the tape114that is being placed by the compaction roller118as well as to detect change in the laser line178projected from the laser176.

In operation, as the head assemblies110are operated to apply the composite tape115onto the workpiece142, the vision computers164monitor the application process, analyze the images in real time for possible manufacturing defects, and transmit the results of their image analyses to the central computer154. As note above, each vision computer164may be adapted to analyze the image to determine whether any possible defects or errors are present in the image, and make accept/reject decisions. The vision computer164may use a variety of suitable methods and algorithms for determining whether defects or errors 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 co-pending, commonly-owned patent applications, incorporated herein by reference: U.S. patent application Ser. No. 09/819,922 by Engelbart et al. filed on Mar. 28, 2001, U.S. patent application Ser. No. 10/628,691 filed on Jul. 28, 2003, U.S. patent application Ser. No. 10/726,099 by Engelbart et al. filed on Dec. 2, 2003, U.S. patent application Ser. No. 10/946,267 by Engelbart et al. filed on Sep. 21, 2004, U.S. patent application Ser. No. 10/904,727 by Engelbart et al. filed on Nov. 24, 2004, and U.S. patent application Ser. No. 10/904,719 by Engelbart et al. filed on Nov. 24, 2004.

In one embodiment, the vision computers164transmit analysis results that indicate a possible manufacturing error or defect to the central computer154, but do not transmit analysis results if no manufacturing errors are indicated. Alternately, the central computer154may receive and maintain a running display of images (both with and without possible defects) as seen through the camera162of the vision unit160. For multiple head assemblies110, this may be accomplished by a split screen display that shows the view from each head assembly110simultaneously in discrete windows. It may also be done by displaying each head assembly110view individually through selection of that head assembly110from a list (e.g. as shown inFIG. 10).

Upon receipt of defect information, the central computer154may query the machine controller152for the coordinates (e.g. x-y coordinates) of the possible defect, and may also receive position information from the encoder166. The central computer154may then write the information regarding defects perceived by the vision computers164to a system error file200, and may archive the corresponding images from the vision computers164.

FIG. 9is a representative system error file200produced by the central computer154. In this embodiment, the system error file200includes a plurality of error file entries202which provide various information regarding the possible defect location (e.g. date, time, ply, course, frame, active program, current block, current head, coordinate information from the machine controller152, position information from the encoder166, etc.). In one particular embodiment, the central computer154maintains a running list of defect locations by machine coordinates, and at the end of each completed ply (or layer), the central computer154sends the running list to a laser projection system156. As shown inFIGS. 1 and 2, the laser projection system156may receive the information regarding possible defects from the central computer154, and may project a defect identifier157onto the workpiece142. The laser projection system156may include a processor that converts the machine coordinates for the purpose of locating and marking possible defects for detailed inspection and possible repair. The laser projection system156may be any suitable projection system, including those projection systems disclosed, for example, in co-pending, commonly-owned U.S. patent application Ser. No. 10/822,538 filed on Apr. 12, 2004, which application is incorporated herein by reference.

The central computer154may also archive the corresponding images from the vision computers164, as well as the related error file entries202, and make them available for subsequent viewing and inspection on a display device158(FIG. 2). The display device158may be driven by the central computer154, or alternately, a secondary computer may be used to run the display device158in order to maintain the processing speed of the central computer154for data archiving tasks.

In one embodiment, the images of possible defect locations from the vision computers164are provided to the display device158by selecting an appropriate error file entry202from the error file200. For example,FIG. 10is a representative screenshot250from the display device158that includes an image252provided by the vision unit160ofFIG. 4. The screenshot250also includes a plurality of identifying data254corresponding to the error file entries202which provide information regarding the possible defect location. In this embodiment, a list256of head assemblies110is provided, allowing the image from each head assembly110to be viewed individually by selection of that head assembly110(e.g. Head3) from the list256.

The overall operation of the manufacturing system100will now be described with reference toFIGS. 11 through 14. Specifically,FIGS. 11 and 12are isometric views of the manufacturing system100in operation in conjunction with a calibration plate180, andFIG. 13is an isometric view of the manufacturing system100in operation on the workpiece142(FIG. 1).FIG. 14is a flowchart showing a method300of performing manufacturing operations in accordance with an embodiment of the invention. The method300includes positioning the head assembly110proximate the forming tool140at a block302, initiating operation of the head assembly110at a block304, and initiating movement of the head assembly110using the translation platform130at a block306. At a block308, the fiber-reinforced composite tape115is applied to the forming tool140(or to the previously-applied layers of the workpiece142).

At a block310, inspections are performed with the vision unit160simultaneously with the application of the tape (block308). More specifically, in a first mode of operation, the vision unit160is 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 (previously incorporated by reference herein), in the laser striping mode of operation, the beam from the laser176is conditioned by a lens system to form a plurality of lateral stripes182. As shown inFIG. 11, the lateral stripes182are projected onto at least part of the area monitored by the camera162. In the example shown inFIG. 11, the lateral stripes182are projected onto the calibration plate180, however, during actual manufacturing operations, the lateral stripes182are projected onto the workpiece142, as shown inFIG. 13. A plurality of calibration grooves184are formed in the surface of the calibration plate180(FIGS. 11 and 12). When the lateral stripes182intersect with one of the grooves184, a discontinuity (or jog, or gap indication)186in the lateral stripe182becomes apparent. Similarly, on the workpiece142, gaps which may occur between a recently-applied portion of the tape and a previously-applied portion of the tape also appear as gap indications186. During actual manufacturing operations, such gap indications186are detected by the vision computer164during analysis of the images acquired by the camera162, and corresponding error messages are generated to indicate that a gap has been detected.

Alternately, during the inspections performed using the vision unit160(block310), defects (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 (previously incorporated by reference herein), in the illumination mode of operation, the lighting sources172are activated to brightly illuminate the area monitored by the camera162. For example,FIG. 12shows the lighting sources172operating in the illumination mode of operation on the calibration plate180. The vision computer164analyzes the resulting images for discontinuities in reflected light intensity, and determines whether defects (e.g. bumps, ripples, irregularities, etc.) are present on the calibration plate180(or on the workpiece142) 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 defects, and a corresponding error indicator message may be returned by the vision computer164.

With continued reference toFIG. 14, at a determination block312, the method300determines whether the inspections performed using the vision unit (block310) resulted in the detection of a defect. If not, the method300proceeds to the determination block320to determine whether manufacturing operations are complete. If manufacturing operations are not complete, the method300returns to the block308and continues the application of the fiber-reinforced composite tape, and the performance of the inspections (block310), and repeats these operations as needed.

Alternately, if a defect is determined at the block312, then at a block314, the defect-related information is output to the central computer154(FIG. 2). At a block316, the projection system156may be used to illuminate the area of the possible defect, and at a block318, the area of the possible defect may be further inspected, analyzed, and repaired if necessary. The method300then proceeds to the determination block320to determine whether manufacturing operations are complete, and if not, the method300returns to the block308and continues the application of the fiber-reinforced composite tape, and the performance of the inspections (block310), and repeats these operations as needed. If manufacturing operations are complete, then the method300terminates at the block322.

Embodiments of systems and methods in accordance with the present invention may provide significant advantages over the prior art. For example, because the head assembly110includes its own dedicated vision unit160for performing inspections, in-process inspections may be performed simultaneously on different regions of the workpiece142as the head assemblies110are simultaneously performing manufacturing operations. The vision units160advantageously reduce downtime of the manufacturing system100by reducing or eliminating the need to shift inspection hardware between head assemblies110. Also, because the central computer154has been relieved of the tasks of image acquisition, image analysis, and decision making by the vision computers164, the central computer154is 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 assemblies110.

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 computer154and the machine controller152(FIG. 2) may be combined into a single computer. Similarly, the display158may be integrated with the central computer154or with the machine controller152. Of course, a variety of other embodiments may be conceived by combining various other components.

Furthermore, embodiments of the invention 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 system100shown inFIG. 1, the forming tool140is adapted for forming an elongated, tubular workpiece142. In one specific embodiment, the workpiece142is 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.

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 in accordance with the present invention may be equipped with other types of tools for performing other types of manufacturing operations. For example, in alternate embodiments, assemblies in accordance with the invention 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.

While embodiments of the invention have been illustrated and described above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of these embodiments. Instead, the invention should be determined entirely by reference to the claims that follow.