Computer Assisted, Manual Workstation

A portion of this patent document contains unpublished material which is subject to copyright. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the patent file or records of the U.S. Patent and Trademark Office, but otherwise reserves all rights to copy or reproduce the copyrighted material in any form.

This invention relates to computer assisted manufacturing systems and, in particular, to a computer assisted, manual workstation in which a sequence of operations is determined by a computer, displayed on a monitor, and the operations are performed manually.

Computers are widely used for manufacturing goods and operate either autonomously, e.g. industrial robots, or interactively. Computers are interactive in the sense of an "expert system," wherein extensive factual information on a particular topic is stored in a computer, or in the sense of augmenting the capability of a human operator, e.g. a mechanical end-effectors imitating human movement but with greater strength or precision. An expert system is commonly used for diagnostic services, e.g. medicine or vehicle repair, and replaces a human expert with a computer.

This invention is unlike any of these systems in that, in accordance with the invention, a computer responds to a particular human operator to define a task that the human operator performs at his own pace. The invention is described in the context of a glass cutting operation but can be implemented in any application in which a plurality of tasks is performed. The invention is particularly suited to manufacturing processes in which a worker performs a plurality of different tasks rather than the same task over and over again.

In a glass cutting operation, a stock sheet of glass is eight feet by twelve feet in size, or larger, and several panes or products can be cut from a single sheet. In automatic or robotic cutting systems, a stock sheet is fed to a cutting station and the panes necessary to fill one or more orders are fitted to the sheet by a pattern optimization program controlling a cutting tool, such as a diamond scribe or cutting wheel. The stock is then cut by the tool, which is mounted on what is essentially a large x-y plotter controlled by the computer.

Automatic cutting stations produce relatively few "cutoffs," pieces that are not product but are large enough to be used to fill a subsequent order, and relatively little scrap, pieces too small to be used to fill an order. One problem with a fully automated, computer controlled cutting system is high cost. Such cutters cost upwards of $100,000 and are too expensive for many small shops. Another problem is that automatic cutting systems require a large volume of orders to efficiently utilize stock. Many small shops operate at a volume below what would justify an automatic system regardless of price.

In a manual glass cutting system, the layout of the cuts is determined by a human operator and the cuts are limited by the reach of the operator and his ability to figure efficient layouts while cutting. Consequently, there are usually more cutoffs and scrap from a manual operation than from an automated operation and the cutoffs tend to be larger. It is desirable to cut finished product from the cutoffs of previous jobs, if possible, but cutoffs are a perishable commodity. The longer a cutoff remains in inventory, the more likely it is to be scratched or broken. Since an operator is not inclined to waste time looking through inventory for a cutoff of just the right size, the inventory grows. Often, a cutoff is saved until it is damaged or forgotten and then thrown away when too many cutoffs accumulate. There is a need to track cutoffs to reduce waste.

There is also a need in glass cutting operations to plan where each finished pane will be placed for the next step in a manufacturing operation, e.g. the assembly of panes into a window. The panes are cut in an essentially random order. Assembling panes into a window requires panes of the same size but different glass, e.g. "bronze" or heat reflecting glass for an outside pane and clear glass for the inside pane of doubly glazed, thermal windows. The bronze glass and the clear glass are cut at different times and from various stock sheets for one or several orders. It is very much desired that the glass cutting operation store the glass product in the proper sequence for assembling windows in the next stage of the manufacturing operation.

An automatic cutting system usually cannot recognize defects in a sheet of glass, such as nicks, scratches, and "fish-eyes" (optical distortions in the glass). An automatic cutting system cuts a glass sheet in accordance with a planned pattern on a specific stock sheet and a defective pane must be re-entered into the system as a new order. In a fully manual system, a person can work around defects in a glass sheet but the operation is time consuming and wasteful of material.

It is desired to enhance the efficiency of a manual glass cutting operation while retaining the advantages that a manual system provides, such as the ability to detect defects. A computer assisted, manual glass cutting operation does not result from substituting a person for an X-Y table and listing the cuts in a printout or on a display. A person cannot perform the function of an X-Y table because, for example, a person has a finite reach. An optimum cutting pattern may require a cut of seventy inches or more, well beyond the reach of a person. Further, an automatic cutting system uses an X-Y table to scribe all cuts prior to fracturing the glass sheet. A person cannot scribe all cuts because of limitations of reach, because the scribed sheet cannot be easily manipulated, and because there is too much data to be understood and executed reliably. Also, the cumulative error of a person is much larger than the cumulative error of an automatic cutter.

U.S. Pat. No. 5,005,318 (Shafir) discloses a glass scribing machine in which a first carriage moves in a first direction and a second carriage, mounted on the first carriage, moves in a second direction, perpendicular to the first direction. The second carriage includes a head for scribing glass. U.S. Pat. No. 4,941,183 (Bruder et al.) discloses a computer assisted system for cutting animal skins in which an image from a template is projected onto the work and the location and position of the template is sensed by a digitizer. A computer checks the cuts to minimize waste and, if there is under-utilization of the skin, the templates are placed on the skin in a different pattern. U.S. Pat. No. 4,709,483 (Hembree et al.) discloses a glass cutting system using an X-Y table and a computer controlled head for cutting the glass in accordance with a predetermined pattern. Waste pieces are re-cut to standard sizes for storage and all cuts are labeled by a marker. U.S. Pat. No. 4,422,149 (Reinmold et al.) discloses in FIG. 1 a glass cutting machine using an X-Y plotter. U.S. Pat. No. 3,543,798 (Feillet) discloses a system for scribing a glass sheet in two directions in separate operations. The glass sheet is first scored in a first direction and then moved to a second location where the sheet is scored in a second direction, perpendicular to the first direction.

In view of the foregoing, it is therefore an object of the invention to provide a computer assisted, manual workstation.

A further object of the invention is to provide a computer assisted, manual workstation adapted to individual workers.

Another object of the invention is to provide a computer assisted, manual workstation which provides product in a coordinated fashion to the next stage of a manufacturing operation.

A further object of the invention is to provide a computer assisted, manual workstation that operates at a pace set by a human worker.

Another object of the invention is to provide a computer assisted, manual workstation that can be adapted to a particular piece of stock, e.g. to work around defects in the stock, under the control of a worker.

A further object of the invention is to provide a computer assisted, manual workstation that tracks cutoffs.

Another object of the invention is to provide a computer assisted, manual workstation that recognizes individual workers and optimizes operation according to the preferences of each worker.

A further object of the invention is to provide a computer assisted, manual workstation that displays quantitative and qualitative data for a worker.

The foregoing objects are achieved in this invention in which a manual workstation includes a personal computer provided with a board for receiving signals from a transmitter and with a video board for controlling a second display in addition to and independently of a first display. The computer is otherwise conventional, e.g. a personal computer based on a 80486 microprocessor. The first display is for quantitative data, e.g. the dimension of a cut, and the second display is for qualitative data, e.g. a graphic image illustrating the cut. The worker communicates with the computer by means of the transmitter, e.g. to indicate that a cut has been completed, or by way of the keyboard for the computer.

Software in the computer includes a pattern optimizing procedure modified to accommodate individual workers. Cuts are laid out with respect to a reference point on a cutting table and the computer optimizes both the pattern of the cuts and the sequence of the cuts for a worker. The software tracks cutoffs in inventory, directs the worker to use a cutoff rather than standard stock, when appropriate, for making product, and identifies the location of the stored cutoff. The software tracks product and directs the worker to store finished product at a particular location in a first rack and to store cutoffs at particular locations in a second rack. The product is stored in the first rack in a sequence appropriate for the next phase of manufacture, e.g. assembly into windows.

A more complete understanding of the invention can be obtained by considering the following detailed description in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a glass cutting shop incorporating a computer assisted, manual workstation constructed in accordance with the invention;

FIG. 2 is a detail of a scribing tool known as a speed cutter;

FIG. 3 is a plan view of a cutting table with a glass sheet position for a first cut;

FIG. 4 is a flowchart of the software for assisting a person cutting glass;

FIG. 5 illustrates a series of menus as provided for a worker to enable customizing the cut patterns in accordance with the preferences of the worker;

FIG. 6 illustrates the two displays telling the worker the orientation, dimension, and location of the first cut;

FIG. 7 illustrates the two displays telling the worker the orientation, dimension, and location of the second cut;

FIG. 8 illustrates the two displays telling the worker where to store the first pane;

FIG. 9 illustrates the two displays when the remaining piece is scrap; and

FIG. 10 is a memory map of the data used in producing the cut sequence for a worker.

In FIG. 1, work station 10 of a glass cutting facility includes cutting table 12 and an optional feed table 13 for supplying a glass sheet (not shown) to cutting table 12. Operator 14 uses speed cutter 15 to scribe a line parallel to and a predetermined distance from an edge of the glass sheet. The glass sheet is then moved to bring the scribe line near the edge of cutting table 12 and the sheet is flexed, causing the sheet to fracture along the scribe line. The result of fracturing a sheet along predetermined scribed lines is a pane which is stored in "harp" rack 16, cutoff rack 17, or scrap bin 18. Pane 19 is one of several panes stored in rack 16.

As illustrated in FIG. 2, speed cutter 15 is a T-square having several small wheels, such as wheel 31 attached to the crossbeam of the square for enabling the square to ride along an edge of glass sheet 33. A trammel mounted, diamond point or steel wheel for speed cutter 15 (FIG. 1) is positioned along the stem of the T to determine the distance of a scribe line from the edge of sheet 33. Suitable jigs or other devices can be used for scribing curved lines.

As described thus far, the facility illustrated in FIG. 1 is a fully manual work station as known in the prior art. In accordance with the invention, computer system 20 includes CPU (central processing unit) 21, keyboard 22, first monitor 24, and second monitor 25. Computer system 20 is a personal computer such as a computer based upon an 80486 microprocessor. There are two boards added to CPU 21. The first board is a video driver for second monitor 25. The second board is a digital I/O board for receiving signals from beeper 26, attached to the belt of operator 14. Beeper 26 can be any suitable signaling device utilizing acoustic, ultra-sonic, infrared, or radio frequency waves to communicate with CPU 21. Signals emitted by beeper 26 are detected by receiver 29 and coupled to a digital I/O board within CPU 21.

As more fully described herein, first monitor 24 displays qualitative or graphic information illustrating the position of a cut for operator 14. Second monitor 25 displays quantitative data, identifying for operator 14 the specific position and orientation of a scribe line.

FIG. 3 is a plan view of table 12, partially covered by glass sheet 33. Table 12 has a textured surface and includes a plurality of holes, such as holes 41, 42, 43, and 44. Air at low pressure is supplied to the holes in table 12 for partially lifting sheet 22 and enabling the sheet to slide across the surface on table 12. The textured surface, e.g. carpeting, on table 12 facilitates holding sheet 33 in place when air is not supplied through the holes in the table.

A plurality of possible cuts is indicated in FIG. 3 by dashed lines such as lines 46 and 48. Dot-dash line 51 extends vertically across the width of sheet 33. Dot-dash line 53 extends horizontally along the length of sheet 33. The layout of all of the potential cut lines is determined by an optimizing program in the computer. Such programs are known per se in the art. In accordance with the invention, the cut pattern is optimized for an individual operator. For example, vertical line 51 is further from edge 55 than line 53 is from edge 57. In accordance with criteria previously given to the computer, the computer refines the optimized cut pattern and displays the modified cut pattern, indicating that the first scribe should be made along horizontal line 53.

The refinement in the optimized pattern could be as simple as rotating the cut pattern or flipping the cut pattern about a vertical or a horizontal axis. The refinement is based on data supplied by each operator, who identifies himself to the computer at the beginning of each job. One item of data is the preferred reference corner. As indicated in FIG. 3 by dot 58, the lower right hand corner is the reference point for all measurements for a right-handed operator and a cut pattern is rotated or flipped to minimize the distance from that point.

FIG. 4 illustrates the overall operation of the software in accordance with the invention. Block 61 is essentially a wait loop that asks an operator to identify himself and to provide responses to a series of questions concerning the preferences of that particular person. If the preferences have been previously given, the wait loop in block 61 simply waits for the identity of a particular operator and then proceeds to the optimization. Orders for products are converted into a list of panes to be cut from particular types of glass. In a typical glass cutting operation, eight to twelve different kinds of glass are stored for a variety of applications. The sheets may differ in thickness or in glass composition or both. The production of a cut list from a plurality of shop orders is known per se in the art and is not part of this invention.

As indicated in FIG. 4, the process of optimization includes two steps. The first step is to lay out a cut pattern and the second step is to define a cut sequence. Pattern optimization is known per se in the art and there are commercially available programs for determining the optimum fit of a plurality of figures within a given outline.

In accordance with the invention, the software proposes a pattern that is then checked in the "cut sequence" portion of the software to compare the pattern with criteria including the preferences provided by an individual operator. If the criteria are not satisfied by a given pattern, the software returns to the layout procedure to produce a new solution to the optimization problem. As indicated by lines 66 and 67 in FIG. 4, this portion of the procedure is re-entrant. That is, the procedure calls itself, passing data between the optimization procedure and the cut sequence procedure until an acceptable solution is found.

It is possible, although not likely, that a solution cannot be found. Re-entrant procedures, if exercised without limit, will eventually cause a computer to stop operating. In order to prevent failure, the number of iterations, or re-entries is monitored and a limit of twenty-five re-entries is imposed. The number twenty-five is arbitrary and depends upon the configuration of a computer, specifically upon the allocated stack space.

On page 4 of Appendix A, line 3840 is the point at which the number of levels is detected and limited to twenty-five. Appendix A is the source code, written in "MegaBasic", for the procedures that control the optimization of the pattern, the cut sequence, and the display. The appendices, all written in "MegaBasic" do not include code relating to set-up or initial conditions such as defining data types, arrays, and tables, providing initial values and the like because such code is well known to skilled programmers.

In Appendix A, the procedure "Optimize.sub.-- Glazing" calls the procedure "Create.sub.-- Sub.sub.-- Plates", see lines 3000 and 3770 of Appendix A. The procedure "Create.sub.-- Sub.sub.-- Plates" calls itself; see entry points at lines 4180, 4370, 4430, and 4920. The procedure "Create.sub.-- Sub.sub.-- Plates" ends at line 4980.

FIG. 5 illustrates a menu in which an operator named "Charlie" provides data for the computer indicating preferences for horizontal movement, horizontal measurement, type of tool etc., as indicated in the menu. The path from the main menu to the "Charlie" menu is also indicated in FIG. 5. Providing and displaying a menu and storing information obtained from dialogue with a user are well known procedures and are not included in the source code included in the Appendices.

There are basically two types of hand cutting tools used in the glazing industry, a speed cutter, as described above, and a T-square. The T-square is just like the drafting tool of the same name and is used with a hand-held scribe run along the edge of the stem of the T. The choice of cutters depends somewhat upon the type of glass being cut and depends upon the subjective preferences of the worker. A workstation incorporating the invention accommodates both types of tools but the cut pattern and the cut sequence depend on which tools are available. Typically, if a speed cutter is available, then a T-square is also available but not all glass shops use speed cutters.

If a speed cutter is the primary tool, then certain cuts cannot be made, for example, a cut longer than the reach of the speed cutter (the stem of the T). Such cuts should be avoided, if possible, to avoid changing tools in the middle of a pattern. Also, the length of the available T-squares and the number and size of the speed cutters dictate how the cutting sequence must be presented to the worker. Since glass "cutting" actually involves scribing and fracturing the glass, it is difficult to cut a piece having a width less than twice the thickness of the glass. This limit is also included in the criteria for evaluating a pattern. These particulars relate to the application of the invention to glass cutting and are built into the criteria for determining the optimum cut pattern and cut sequence. Different criteria would be used in adapting the invention to other applications. Whatever the application, the invention provides a mechanism for tailoring a manual task to the limits, preferences, and pace of an individual worker.

After a solution to the layout problem is accepted, the cut data is displayed in quantitative and qualitative form as a sequence of tasks; see block 68 in FIG. 4. In FIG. 6, monitor 25 displays the legend "H-53.50" and monitor 24 displays a graphic illustrating the cut as bright, horizontal line 73. Different areas in the graphic are preferably provided with distinct colors identifying the portions of the sheet as product, cutoff, or scrap. In the monochromatic illustration of FIG. 6, areas 71 and 72 are cross-hatched to indicate scrap. The remaining areas are product.

After the cut data is displayed for the operator, the computer enters a wait loop, indicated in FIG. 4 by block 74. Specifically, the computer is looking for a response from the operator by way of beeper 26 (FIG. 1) or keyboard 22 (FIG. 1). In one embodiment of the invention, either the "return" key on the keyboard or the beeper is used to indicate the successful completion of an operation. The beeper is the primary mechanism for indicating a cut is completed.

The computer interprets a signal from the beeper as an indication that the cut has been successfully completed as directed and proceeds to display the next task. Since the completed cut was the first cut in a sheet of glass containing a plurality of panes, the computer will then display the second cut to separate the first product from the remaining cutoff. As illustrated in FIG. 7, the second cut is a vertical cut 80.75 inches from the right hand end of the sheet. This cut is indicated by bright line 75. Area 71 remains colored (cross-hatched) as scrap and areas 77 and 78 are colored (cross-hatched) as cutoffs.

After the operator actuates the beeper, the software updates internal tables, as indicated by block 76 in FIG. 4, and re-executes pattern optimization to determine the next cut. The optimization takes very little time and is typically transparent to an operator. Even at twenty-four levels of iteration, optimization takes less than one second while running the source code in an interpretive mode. When compiled, the optimization procedure would take approximately one fourth of a second to execute under worst case conditions.

After the vertical cut illustrated in FIG. 7, the computer displays the separated product on monitor 24 and indicates the size and storage location for the product on monitor 25, as illustrated in FIG. 8. Pane 78 is highlighted with bright lines as shown to provide further indication to the worker that the pane is completed. Other highlighting techniques could be used. The storage location shown on monitor 25 is a unique slot within harp rack 16 (FIG. 1). Even though it is the first product from a sheet, the computer knows whether or not the product should be stored in the first slot in the harp rack in order to provide product in an appropriate sequence for subsequent manufacturing operations. The storage sequence is determined in accordance with order entry information forwarded to computer system 20 from an external source.

After additional vertical cuts are made and product is removed, one is left with scrap 71 and the operator knows to place piece 71 in the scrap bin because of its color code in the display, as shown in FIG. 9.

Although the example illustrated in FIGS. 5-9 assumes a stock sheet of glass as the starting material, the same sequence is performed with a cutoff retrieved from rack 18 (FIG. 1). The dimensions of the cutoff are known to the computer, which tracks both product and cutoffs, and the optimization procedures operate on any size starting material.

As a default value, the computer will use both cutoffs and standard inventory, selecting that which produces the best yield. In accordance with the invention, an operator can override the default selection and specify that only standard inventory be used or specify that only cutoffs be used. Using only standard inventory saves time and using only cutoffs quickly reduces the inventory of cutoffs. The choice of source material does not affect subsequent manufacturing operations because the harp rack is loaded in the proper sequence to produce product at the next station.

Appendix B contains the procedures for advising the operator what to do with the piece that was just cut and for storing the size and location of a cutoff. Appendix C contains the procedures for determining dimensions and orientations in a cut pattern. Appendix D contains the procedures for determining whether or not the cut pattern in a viable solution when compared with the criteria including the preferences of an individual worker.

FIG. 10 illustrates a memory map of the data used by the software in accordance with the invention. The storage areas are dynamically allocated by the software and include the cut list, current inventory of stock sheets of glass, current inventory of cutoffs, data on various tools used by an operator, e.g. the reach of a T-square, operator preferences, e.g. right- or left-handedness, reach, location of reference point, and the inventory of product stored in sequence for the next operation. An operator has access to all of this data, listed as catalogues in a menu, in order to correct for errors or breakage.

Problems are accommodated by a "hot key" on the computer keyboard. Depressing the hot key causes the computer to produce a list of possible problems which need to be addressed. In the particular application of glass cutting, such problems include bad breakouts, chipped corners, lost cutoffs, special interruptions, re-cuts and others types of problems. Some problems depend on the status of the cutting process at the time the worker alerts the system that there is a problem. Appendix E is a straightforward procedure for looking for a signal from a beeper or a hot key. The routine is somewhat hardware dependent in that it is intended to interface with an I/O board that receives a signal from receiver 29 (FIG. 1). Appendix F is a procedure for presenting menus to a worker in response to the worker actuating a hot key. The menu items relate specifically to a glass cutting operation. Line 9235 in Appendix E links the I/O procedure in Appendix E to the problem handling procedure in Appendix F.

The invention thus provides a computer assisted, manual workstation adapted to individual workers who work at their own pace performing tasks that are individually optimized for each worker. The system accommodates defects in materials or other problems and tracks inventories of stock, product and cutoffs. The product is stored in sequence in preparation for the next phase of manufacture, further increasing the efficiency of the workplace. The workstation displays information in both qualitative and quantitative fashion to provide unambiguous guidance of each step in the production of goods. Each step is displayed at a pace determined by a worker.

Having thus described the invention, it will be apparent to those of skill in the art that various modifications can be made within the scope of the invention. For example, the criteria for evaluating a pattern can be weighted or placed in hierarchical order. If weighted, the criteria are divided between needs, wants, and "don't care." Needs will always cause a cut sequence to be reconstructed. Wants or preferences will cause a cut sequence to be reconstructed unless there have been too many iterations already, e.g. more than twenty iterations. "Don't care" does not cause a reconstruction of the cut sequence. With hierarchical criteria, low priority criteria are dropped if a cutting solution cannot be found. A system including hierarchical or a weighted criteria could have a limit on the number of iterations less than twenty-five.

Data embedded in the program as part of an instruction can be stored in memory as data, and vice-versa. The choice depends upon how much flexibility one wants to give to an operator. For example, the number of iterations before the system gives up trying to optimize a pattern could be stored in RAM and be accessible to an operator through a set-up or configuration menu. A hardware modification to a computer to provide separate RAM for a memory stack would increase the size of the stack and increase the number of iterations that could be made safely.

In one embodiment of the invention, the beeper has a single key and emits a CW signal. A beeper could have more than one key and emit modulated signals which would then be distinguishable, e.g. to provide a hot key capability at the beeper rather than at the keyboard. The location of the monitors is a matter of preference. The first monitor need not be located immediately adjacent the CPU.

While described in the context of a glass cutting facility, the invention can be used in other applications, such as manual fabrication and assembly and manual machining operations. The term "manual workstation" is not intended to mean that only manual tools are used, e.g. a scribe, hammer, or handsaw. Manually controlled power tools appropriate for the particular goods can be used. ##SPC1##