[0001] This application claims the benefit of priority of Korean Patent Application Serial No. 10-2017-0084723 filed on July 4, 2017 the contents of which are relied upon and

incorporated herein by reference in their entirety as if fully set forth below.

BACKGROUND

FIELD

[0002] The present disclosure relates to methods and apparatus for loading a glass sheet into a container.

Technical Background

[0003] The storage and/or transportation of glass sheets frequently involve loading multiple glass sheets into a container using an automated system, such as a robot. Many glass sheets, and in particular glass sheets used in the manufacture of visual display panels for electronic equipment such as television monitors, tablets, cell phones and the like, are exceptionally thin and prone to movement (temporary distortion or fluctuation) within the sheet as the sheet is handled by the robot and positioned within the container. If movement of the glass sheet results in contact between the glass sheet being positioned in the container, and an adjacent glass sheet previously positioned in the container, contact between surfaces of one or both of the glass sheets may occur, resulting in damage and thereby rendering either one or both glass sheets unusable for their intended purpose. Such inadvertent contact may not be immediately noticeable. Accordingly, methods to monitor a location of the glass sheet being positioned within the container, determining the likelihood that contact occurred, and alerting manufacturing personnel would be useful to reduce the cost associated with damaged and unusable ware and eliminating the potential for shipping the same.

SUMMARY

[0004] A method for loading a glass sheet is disclosed comprising (a) positioning a first glass sheet in a container, (b) detecting movement after step a) of the first glass sheet with a sensor as a distance x _s (i-l) of the first glass sheet from the sensor, and (c) positioning with a robot a second glass sheet in the container adjacent the first glass sheet. The method further comprises (d) detecting movement of the second glass sheet during step (c) as a distance xt(i) l of the second glass sheet from the sensor, (e) disengaging the robot from the second glass sheet, and (f) detecting movement after step (e) of the second glass sheet as a distance x _s (i) of the second glass sheet from the sensor. The method further comprises (g) initiating an alarm, if any one of the following conditions is met: 1) a difference between MAX(xt(i)) and MIN(xt(i)) is greater than a first predetermined value, or 2) a difference between MIN(x _s (i-l)) and MAX(xt(i)) is less than a second predetermined value, or 3) if a difference between MIN(x _s (i-l)) and MAX(x _s (i)) is less than a third predetermined value, or 4) if a difference between MAX(x _s (i)) and MIN(x _s (i)) is greater than a fourth predetermined value.

[0005] In some embodiments, the sensor can be an ultrasonic sensor.

[0006] In some embodiments, step (d) may comprise a gripping apparatus coupled to the robot, the gripping apparatus comprising a frame including a base member and a pair of opposing arm members extending therefrom, each arm member comprising an upper arm portion and a lower arm portion coupled to the upper arm portion, the lower arm portion rotatable about a pivot point, the method further comprising rotating the lower arm portions about the pivot points such that side walls of the container extend between the glass sheet and the arm members as the second glass sheet is positioned in the container.

[0007] Each lower arm portion may further comprise a gripping device coupled thereto, the method further comprising disengaging the gripping devices from the second glass sheet prior to rotating the lower arm portions.

[0008] Step (d) further comprises at least one top gripping device coupled to the base member and engaged with the second glass sheet.

[0009] In another embodiment, a method for loading a glass sheet is described comprising the steps of (a) positioning with a robot a first glass sheet in a container, (b) disengaging the robot from the first glass sheet, and (c) detecting movement after step b) of the first glass sheet with a sensor as a distance x _s (i-l) of the first glass sheet from the sensor. The method further comprises the steps of (d) positioning with the robot a second glass sheet in the container adjacent the first glass sheet, (e) detecting movement of the second glass sheet during step (d) as a distance xt(i) of the second glass sheet from the sensor, (f) disengaging the robot from the second glass sheet and (g) detecting movement after step (f) of the second glass sheet as a distance x _s (i) of the second glass sheet from the sensor. The method still further comprises (h) initiating an alarm, if any one of the following conditions is met: 1) a difference between MAX(xt(i)) and MIN(xt(i)) is greater than a first predetermined value, or 2) a difference between MIN(x _s (i-l)) and MAX(xt(i)) is less than a second predetermined value, or 3) if a difference between MIN(x _s (i-l)) and MAX(x _s (i)) is less than a third predetermined value, or 4) if a difference between MAX(x _s (i)) and MIN(x _s (i)) is greater than a fourth predetermined value.

[0010] In still another embodiment, an apparatus for loading a glass sheet into a container is disclosed, comprising a robot comprising a robot arm and a gripping apparatus coupled to an end of the robot arm. The gripping apparatus comprises a base member and first and second arm members. Each arm member of the first and second arm members comprises a first arm portion connected to the base member and a second arm portion coupled to the first arm portion and rotatable about a pivot point. The second arm portion of the first arm member is configured to rotate in a direction opposite the second arm portion of the second arm member.

[0011] In some embodiments, the base member comprises at least one gripping device.

[0012] In some embodiments, each second arm portion of the first and second arm members comprises at least one gripping device.

[0013] The apparatus may further comprise an actuator coupled between the first and second arm portions and operable to rotate the second arm portion about the pivot point, a sensor, for example an ultrasonic sensor, configured to sense a distance from the sensor to a sheet of glass as the sheet of glass is positioned within the container by the robot, and a controller operably coupled between the sensor and the robot. The controller may control the motion of the robot arm, the motion of the arm members, the rotation of the second arm portions and/or operation of one or more of the base member and second arm portion gripping devices.

[0014] Additional features and advantages of the embodiments disclosed herein will be set forth in the detailed description that follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0015] It is to be understood that both the foregoing general description and the following detailed description present embodiments intended to provide an overview or framework for understanding the nature and character of the embodiments disclosed herein. The accompanying drawings are included to provide further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description serve to explain the principles and operations thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a cross sectional side view of glass sheets being loaded into a container by a robot and including a detection apparatus for determining the distance between a sensor and the glass sheets;

[0017] FIG. 2 is a top view of the container of FIG. 1 ;

[0018] FIG. 3 is a front view of an exemplary gripping apparatus for use with a robot;

[0019] FIGS. 4A - 4E illustrate a sequence of movements of the gripping apparatus of FIG. 3, as conveyed by a robot;

[0020] FIG. 5 is a schematic diagram illustrating distance "x" of glass sheets positioned within the container of FIG. 1 as a function of time "t".

DETAILED DESCRIPTION

[0021] Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0022] Ranges can be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0023] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom - are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0024] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus, specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0025] As used herein, the singular forms "a," "an" and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0026] As used herein, the operators MAX(variable) and MIN(variable) represent the maximum and the minimum, respectively, of the variable contained within the parenthesis. The variable may be a continuous variable (e.g., a continuous function), or the variable may comprise a plurality of discrete values, for example a collection of distances.

[0027] As used herein, a robot is a machine capable of carrying out a complex series of actions automatically, especially one programmable by a controller, computer or other processing device.

[0028] As used herein, the term "articulated" in construed to mean comprising two or more sections connected by a flexible joint.

[0029] Glass destined for use in display applications, for example the manufacture of display panels, cover glass, and the like, are exceptionally thin, for example with a thickness equal to or less than 1 millimeter (mm), for example equal to or less than about 0.7 mm, equal to or less than about 0.5 mm, such as equal to or less than about 0.3 mm. Such glass sheets may, in some instances, have width and length dimensions equal to or greater than 880 mm x 680 mm, equal to or greater than 1250 mm x 1100 mm, equal to or greater than 1800 mm x 1500 mm, equal to or greater than 2200 mm x 1870 mm, equal to or greater than 3600 mm x 3100 mm, or even greater. Automated industrial processes typically employ a robot to grip the glass sheet, deliver the glass sheet to an appropriate container, for example a storage or transportation container (depending on need), and positioning the glass sheet within the container. For containers that support the glass sheets adjacent each other with a gap separating adjacent glass sheets, with the exception of the first glass sheet, each subsequent glass sheet is placed in close proximity to a previous glass sheet. As used herein, the term "adjacent" refers to the most proximate glass sheet previously or subsequently positioned in the container and is not limited to any specific distance between the glass sheets. Glass sheets with the foregoing dimensions are quite flexible, and the flexibility of the glass sheets can cause a problem during glass loading processes. Typically, such loading operations occur after final inspection of the glass sheets. Although normally very flat, if a glass sheet being loaded into the container fluctuates, it can touch an adjacent glass sheet and cause post- inspection damage to itself, the previously loaded adjacent glass sheet, or both. As a result, damaged ware can be inadvertently shipped to a customer. As used herein, fluctuation refers to out-of-plane movement of the glass sheet. That is, if the glass sheet is represented as a plane, out-of-plane movement refers to waviness, buckling, undulation, or any other movement in which the glass sheet experiences distortion or deviation from the plane.

[0030] Fluctuation of the glass sheets in a loading process can occur for many reasons, e.g., air turbulence in the loading area, a mechanical problem with the robot, mismatch with the container size, momentum, etc., so addressing the root cause of the fluctuation is difficult.

[0031] Systems to detect post-inspection damage by additional inspection can introduce further delay, and can create a bottleneck in the production process leading to increased cost. If such systems are implemented, they are typically introduced on a sampling basis, as re- inspecting each glass sheet would also be impractical.

[0032] Accordingly, a real-time glass position monitoring system is described. The monitoring system utilizes a sensor to measure distances from the sensor to a glass sheet being loaded into a container, and compares those distances with the location of a previously loaded glass sheet. The distance data is sent from the sensor to a controller, for example a programmable logic controller (PLC). The controller can then be used to activate an alarm if there is a possibility the adjacent glass sheets contacted each other, although it should be noted that other, more automated command functions can be implemented. For example, in some embodiments, feedback from the controller based on the distance data could be used to control the robot or to initiate other factory processes.

[0033] Shown in FIGS. 1 and 2 are a cross sectional side view and a top view, respectively, of a container 10 including at least one glass sheet 12 positioned therein. Container 10 includes a front wall 14, a back wall 16 opposing front wall 14, and a pair of opposing side walls 18, 20 connected to front wall 14 and back wall 16. Container 10 further includes a bottom wall 21 connecting to the side, front and back walls. As shown in FIG. 1, a robot 22 including a gripping apparatus 24 holds a second glass sheet 26 and positions second glass sheet 26 into container 10 adjacent the initial at least one glass sheet 12. An exemplary gripping apparatus 24 is illustrated in FIG. 3 coupled to robot arm 30 (typically an articulated robot arm) including a frame comprising base member 32 and arm members 34a, 34b extending therefrom, and a plurality of gripping devices attached to the frame. In the embodiment of FIG. 3, gripping apparatus arm members 34a and 34b are articulated arm members further comprising first, upper arm portions 36a, 36b, and second, lower arm portions 38a, 38b, respectively, lower arm portions 38a, 38b being coupled to upper arm portions by and rotatable about pivot points 40a, 40b, respectively, as indicated by arrows 42a, 42b. Lower arm portions 38a, 38b may be further coupled to upper arm portions 36a, 36b by actuating devices 44a, 44b, respectively, for example pneumatic or hydraulic cylinders, or electric or electromagnetic actuators (e.g., solenoids or the like), which, when actuated, rotate the lower arm portions about their respective pivot points.

[0034] Gripping apparatus 24 further comprises one or more gripping devices 46 coupled to base member 32, a griping device 48a coupled to lower arm portion 38a and a gripping device 48b coupled to lower arm portion 38b. Each of gripping devices 46, 48a and 48b can be opened and closed remotely by way of an actuator (not shown) such that the gripping devices engage and disengage with a glass sheet. As best seen with the aid of FIG. 3, when held by gripping devices 48a, 48b, side edge 50a, 50b of a glass sheet, for example glass sheet 26, are separated from arm portions 34a, 34b by gaps 52a, 52b. Gaps 52a, 52b are sized to accommodate and receive side walls 18 and 20 of container 10, as will be described in more detail below.

[0035] To better distinguish the glass sheets, the initial glass sheet previously (most recently) loaded into the container 10 will be designated the (i-l)th glass sheet, and the glass sheet (second glass sheet 26) to be positioned adjacent the (i-l)th glass sheet by robot 22 will be referred to as the (i)th glass sheet. As illustrated in FIG. 1, the (i)th glass sheet 26 is depicted as contacting the (i-l)th glass sheet 12 and potentially damaging the (i)th glass sheet, the (i- l)th glass sheet, or both the (i)th glass sheet and the (i-l)th glass sheet.

[0036] Also shown in FIG. 1 is detection apparatus 54 comprising sensor 56, for example an ultrasonic sensor, configured to measure a distance between sensor 56 and a glass substrate placed into container 10, although in further embodiments alternative sensors configured to measure distance to a glass sheet may be used, for example a laser sensor. An ultrasonic sensor is advantageous, however, since a laser sensor may have difficulty sensing distance to a transparent substrate (e.g., a transparent glass sheet). An exemplary ultrasonic sensor is model T30UXIA available from Banner Engineering Corporation, although other ultrasonic sensors can be employed. If, as in the present embodiment, data output from the sensor is analog, detection apparatus 54 may further comprise an analog-to-digital (A/D) converter 58 configured to receive an analog data signal from sensor 56 over data line 60 and convert the analog signal to a digital data signal. The digital data signal from A/D converter 58 is then provided to controller 62 over data line 64. Controller 62 may further, in some embodiments, control operation of gripping apparatus 24 (e.g., gripping devices 46, 48a and 48b and lower arm portion actuating devices 44a, 44b), although in further embodiments, gripping apparatus 24 may be operated by a separate controller. It should be noted that communication between data components (controllers, databases, etc.) may, in some embodiments, be carried out wirelessly. However, care must be taken to shield against or otherwise exclude electrical noise common to industrial environments.

[0037] Controller 62 may encompass all apparatus, devices, and machines for processing data, including by way of example a programmable processor (e.g., programmable logic controller, PLC), a computer, or multiple processors or computers. Controller 62 may include, in addition to hardware, code that creates an execution environment for a computer program, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.

[0038] A computer program (also known as a program, software, software application, script, or code) may be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and it may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program may be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program may be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[0039] The processes described herein may be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows may also be performed by, and apparatus may also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit) to name a few.

[0040] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random-access memory or both. The essential elements of a computer are a processor for performing instructions and one or more data memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Moreover, a computer may be embedded in another device, e.g., a mobile telephone, a personal digital assistant (PDA), to name just a few.

[0041] Computer readable media suitable for storing computer program instructions and data include all forms data memory including nonvolatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[0042] To provide for interaction with a user, embodiments described herein may be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, and the like for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, or a touch screen by which the user may provide input to the computer. Other kinds of devices may be used to provide for interaction with a user as well; for example, input from the user may be received in any form, including acoustic, speech, or tactile input.

[0043] Embodiments described herein may be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a client computer having a graphical user interface or a Web browser through which a user may interact with an implementation of the subject matter described herein, or any combination of one or more such back end, middleware, or front end components. The components of the system may be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network ("LAN") and a wide area network ("WAN"), e.g., the Internet.

[0044] The computing system may include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. [0045] Controller 62 may be used to initiate an alarm and/or initiate movement of robot 22 or robot components in response to distance information received from sensor 56. For example, controller 62 may include software configured to compare data received from sensor 56 (e.g., via A/D converter 58) against pre-programmed logic conditions and initiate a response, for example an alarm, according to programmed instructions. In further embodiments, controller 62 may be in communication with an input-output (I/O) device 66 over data line 68, I/O device 66 configured to display data related to the operation of robot 22 to factory personnel, and in particular information related to positioning of glass sheets into container 10, including alarm conditions. I/O device 66 may further include apparatus, such as a keyboard, computer mouse, or other input device, to provide communication between controller 62 and an operator or other factory personnel.

[0046] In some embodiments, controller 62 may further be in communication with a database 69 for storing data from the controller, and which database may further include one or more software programs for analyzing data provided from controller 62 and/or database 69, so as to compare such data with historical information. For example, in some embodiments, database 69 may include historical process data, certain glass attributes such as thickness and dimensions as well as glass type, alarm history, etc. Analysis of historical data may be useful in discovering process trends for troubleshooting purposes or process improvement.

[0047] For purposes of illustration and not limitation, container 10 may include a plurality of slots 70 defined between projections 72 positioned along inside surfaces of the container walls, the slots configured to receive individual glass sheets. For example, as illustrated in FIG. 2, a plurality of slots 70 defined between a plurality of projections 72 are disposed in opposing relationship along inside surfaces of side walls 18 and 20 of container 10 such that adj acent glass sheets positioned in the slots are substantially parallel with each other and substantially parallel with front and back walls 14, 16. For example, container 10 may comprises a resilient material comprising the projections and slots, for example a foam polymer material such as a closed cell foam material, applied to the inside surfaces of the container. Bottom wall 21 may also include a plurality of slots, similarly defined between a plurality of projections, the bottom slots aligned with slots along the sides of the container such that a generally planar substrate, for example a glass sheet, can be held in an upright position within a set of slots substantially parallel with the front and back walls of the container.

[0048] During operation, robot 22 acquires a glass sheet by engaging edges of the glass sheet with gripping apparatus 24. For example, a top edge 49 of the glass sheet may be gripped by one or more gripping devices 46, and side edges 50a, 50b may be gripped by gripping devices 48a, 48b, respectively, thereby providing lateral support to the glass sheet.

[0049] FIGS. 4A - 4E show a sequence of steps illustrating a process for depositing glass sheet 26 (e.g., the (i)th glass sheet) in container 10. In accordance with the sequence step shown in FIG. 4A, once the glass sheet 26 has been engaged by robot 22, robot 22 transports glass sheet 26 to a position over container 10 and aligned with a pair of opposing slots 70 arranged along the inside surfaces of opposing side walls 18, 20 of container 10. At the sequence step shown in FIG. 4B, robot 22 begins lowering glass sheet 26 downward, for example vertically downward, into container 10. As glass sheet 26 is lowered into container 10, the glass sheet comes within range of sensing beam 82 from sensor 56, for example an ultrasonic beam, whereupon distance information regarding the distance between sensor 56 and glass sheet 26 is collected and communicated to controller 62 via A/D converter 58. Griping devices 48a, 48b are disengaged from side edges 50a, 50b of the glass sheet, and actuator devices 44a, 44b rotate lower arm portions 38a, 38b about pivot points 40a, 40b, thereby providing unobstructed access to gaps 52a, 52b between the glass sheet side edges 50a, 50b and the side walls 18, 20 of container 10. At the sequence step shown in FIG. 4C, as robot 22 lowers the glass sheet into container 10, the side arm portions 34a, 34b are positioned external to the side walls 18, 20 of container 10, and the side walls extend into the gaps between the glass sheet and arm members 34a, 34b while glass sheet 26 is lowered into the side wall slots within the container. At the sequence step shown in FIG. 4D, glass sheet 26 is fully positioned within container 10, and the one or more top gripping devices 46 disengage from the glass sheet. At the sequence step shown in FIG. 4E, robot 22 withdraws gripping apparatus 24 and moves to retrieve another glass sheet for placement into container 10. A cover, (not shown) may be placed overtop the container at the completion of the loading process.

[0050] In accordance with the present disclosure, a glass sheet placed into container 10 by robot 22 is sensed by sensor 56 and a distance between the sensor and the glass sheet is obtained. For purposes of discussion, this glass sheet may arbitrarily be designated as the (i- l)th glass sheet. When the (i-l)th glass sheet is finally positioned into container 10 by robot 22 and released by gripping apparatus 24, controller 62 in communication with sensor 56 records the final position (distance) of the (i-l)th glass sheet in a memory component. Robot 22 then retrieves another glass sheet, designated as the (i)th glass sheet. A distance of the (i)th glass sheet from sensor 56 as robot 22 positions the (i)th glass sheet is monitored and recorded. The distance may be sampled at any suitable sampling rate depending on the capability of A/D converter 58. When the (i)th glass sheet is finally positioned adjacent the (i-l)th glass sheet, the (i)th glass sheet is re-designated the new (i-l)th glass sheet in preparation for the next (i)th glass sheet. Thus, the previous glass sheet is designated the (i- l)th glass sheet and the subsequent glass sheet is designated the (i)th glass sheet, and each (i)th glass sheet thereafter becomes an (i-l)th glass sheet upon retrieval of the next (i)th glass sheet. Put another way, for each new (i)th glass sheet, the previous (i)th glass sheet becomes the (i-l)th glass sheet. It should be apparent that this iterative process relies on only two glass sheets at any one time, the already-deposited (i-l)th glass sheet and the new, (i)th glass sheet to be deposited. Data for any previous glass sheets before the (i-1) glass sheet, although unnecessary, may however be captured if desired and stored in database 69.

[0051] It should also be apparent that if desired, the foregoing iterative process can be replaced with a numbered sequence, wherein the initial glass sheet is designated the (i)th glass sheet and each subsequent glass sheet is designated the (i+n)th glass sheet, where n is an index number that increases by 1 each time a new glass sheet is retrieved and added to the container. Indexing the glass sheets in such a manner can add a counting routine to the process if needed or desired, and further facilitate retention of historical data.

[0052] Returning to the iterative scenario, and referring to FIG. 5, three exemplary curves are shown plotted as a distance "x" from sensor 56 as a function of time "t". Curve 90 represents the distance from sensor 56 of a previous glass sheet in place within container 10, second curve 92 represents a new glass sheet in the process of being loaded into the container, third curve 94 represents a subsequent glass sheet being loaded into the container after the (i)th glass sheet in order to show repetition of the loading cycle, which will become more clear with the following description. As before, the previous glass sheet is designated the (i-l)th glass sheet and the new glass sheet in the process of being loaded into the container is designated the (i)th glass sheet. The subsequent glass sheet will be designated, for purposes of discussion and illustration, as the (i+l)th glass sheet to avoid undue confusion.

[0053] Sensor 56 monitors the position (distance from sensor 56) of the (i-l)th glass sheet (glass sheet 12 in accordance with FIGS. 1 and 2) during loading of the (i)th glass sheet (glass sheet 26 in accordance with FIGS. 1 and 2) until such time as the (i)th glass sheet comes within range of the sensor at time t = 0. As shown by curve 90, a fluctuation in the shape of the (i-l)th glass sheet occurs at time t-1. Accordingly, a variation in distance is sensed by sensor 56 and communicated to controller 62. Since the (i)th glass sheet has not at this time come within range of the sensor, controller 62 records the position of the (i-l)th glass sheet during the fluctuation and determines a minimum position and optionally a maximum position of the (i-l)th glass sheet during the fluctuation.

[0054] Still referring to FIG. 5, at t = 0, the (i)th glass sheet engaged by robot 22 comes within range of sensor 56, and fluctuation of the (i)th glass sheet is measured by the sensor as the (i)th glass sheet is positioned within container 10. The fluctuation of the (i)th glass sheet during the positioning is measured by the sensor as a distance xt(i) and the distance data xt(i) is communicated to controller 62. Simultaneous with the acquisition of the (i)th glass sheet by sensor 56, monitoring of the (i-l)th glass sheet ceases, since the (i)th glass sheet now blocks the view by sensor 56 of the (i-l)th sheet. At t=+l (where +1 indicates an arbitrary unit of time, dependent on the process cycle time) the robot (e.g., gripping apparatus 24) disengages from the (i)th glass sheet. Controller 62 identifies a maximum distance between the sensor and the (i)th glass sheet and a minimum distance between the sensor and the (i)th glass sheet during the period between t=0 and t=+l, designated as MAX(xt(i)) and MIN(xt(i)), respectively.

[0055] During the period t=+l and t=+2 (where +2 represents an arbitrary unit of time greater than +1, dependent on the process cycle time), the (i)th glass sheet is disengaged from the robot. Sensor 56 monitors any fluctuation of the (i)th glass sheet as a distance x _s (i) between the sensor and the (i)th glass sheet and communicates the distance information to controller 62. Controller 62 identifies a maximum distance between the sensor and the (i)th glass sheet and a minimum distance between the sensor and the (i)th glass sheet during the period between t=+l and t=+2, designated as MAX(x _s (i)) and MIN(x _s (i)), respectively. At t=+2 a subsequent glass sheet is positioned in container 10 and the foregoing cycle repeats. The previously-designated (i)th glass sheet becomes the (i-l)th glass sheet, and the subsequent glass sheet (the (i+1) glass sheet) becomes the new (i)th glass sheet. This sequence is repeated until all glass sheets have been loaded into the container.

[0056] Next, values of A, B, C and D of curve 92 representing the (i)th glass sheet are explained. At the moment the (i)th glass sheet comes into range of sensor 56, fluctuation of the (i)th glass sheet is monitored and recorded. The value "A" represents the difference between the maximum distance value MAX(xt(i)) and the minimum distance value MIN(xt(i)) of xt(i) during the loading of the (i)th glass sheet, where xt(i) is the distance of the (i)th glass sheet from sensor 56 as a function of time. That is, "A" represents a spatial envelope defined by the fluctuation of the (i)th glass sheet. If "A" is greater than a, where a is a predetermined set point or limit, controller 62 can initiate an alarm based on programming of the controller. The value of a can be dependent upon a variety of different variables, including the flexibility of the glass sheet (dependent on the glass size, thickness, etc.), size of the container, container slot spacing, factory ventilation (air flows), gripping apparatus construction and so forth, and is typically determined by experimentation. Mathematically, the alarm condition for "A" can be expressed as (MAX(xt(i)) - MIN(xt(i))) > a.

[0057] The value "B" is used to determine whether the (i)th glass sheet is likely to have contacted the (i-l)th glass sheet during loading of the (i)th glass sheet. "B" represents the difference between the minimum value of x _s (i-l) and the maximum value of xt(i), where xt(i- 1) is the distance of the (i)th glass sheet from sensor 56 as a function of time. Which is to say "B" represents the difference between the minimum distance MIN(x _s (i-l)) of the (i-l)th glass sheet from sensor 56 prior to the time the (i)th glass sheet is acquired by sensor 56 and the maximum distance MAX(xt(i)) between the sensor and the (i)th glass sheet during the period between the time the (i)th glass sheet is acquired by the sensor and the time the (i)th glass sheet is released by the robot. If "B" is less than β, where β is a predetermined set point or limit, controller 62 can initiate an alarm. The value of β can be dependent upon a variety of different variables, including the flexibility of the glass sheet (dependent on the glass size, thickness, etc.), size of the container, container slot spacing, factory ventilation (air flows), gripping apparatus construction and so forth, and is typically determined by experimentation. Mathematically, the alarm condition for "B" can be expressed as (MIN(x _s (i-l)) - MAX(xt(i)))

< β·

[0058] The value "C" is used to determine if the final position of the (i)th glass sheet (prior to acquisition by the sensor of the (i+l)th glass sheet and subsequent designation of the (i)th glass sheet as the new (i-l)th glass sheet) is sufficiently close to the (i-l)th glass sheet that the (i)th and (i-l)th glass sheet may contact. If "C" is less than γ, where γ is a predetermined set point or limit, the controller can initiate an alarm. The value of γ can be dependent upon a variety of different variables, including the flexibility of the glass sheet (dependent on the glass size, thickness, etc.), size of the container, container slot spacing, factory ventilation (air flows), gripping apparatus construction and so forth, and is typically determined by experimentation. Mathematically, the alarm condition for "C" can be expressed as (MIN(x _s (i-l)) - MAX(xs(i))) < γ.

[0059] The value "D" represents the difference between the maximum value MAX(x _s (i)) and the minimum value MIN(x _s (i)) of x _s (i), where x _s (i) is the distance of the (i)th glass sheet from sensor 56 as a function of time. More specifically, "D" represents the difference between the maximum and minimum distances of the (i)th glass sheet after the (i)th glass sheet has been placed in the container and released by the robot. Put more plainly, "D" represents the total out-of-plane excursion of the glass sheet after gripping apparatus 24 has released the (i)th glass sheet. The value of "D" should be at least less than the pitch between slots. If "D" is larger than δ, where δ is a predetermined set point or limit, the controller can initiate an alarm. The value of δ can be dependent upon a variety of different variables, including the flexibility of the glass sheet (dependent on the glass size, thickness, etc.), size of the container, container slot spacing, factory ventilation (air flows), gripping apparatus construction and so forth, and is typically determined by experimentation. Mathematically, the alarm condition for "D" can be expressed as (MAX(x _s (i)) - MIN(x _s (i))) > δ.

[0060] It should be noted that an alarm may be initiated if any one or more of the above conditions A through D occur.

[0061] It will be apparent to those skilled in the art that various modifications and variations can be made to embodiments of the present disclosure without departing from the spirit and scope of the disclosure. Thus it is intended that the present disclosure cover such

modifications and variations provided they come within the scope of the appended claims and their equivalents.