Inspection of seal for high altitude balloons

Aspects of the disclosure relate to systems and techniques for inspecting seals for high altitude balloons. In one example, a system may include a reflective surface, a translucent material on the reflective surface, and a movable light source configured to move along the reflective surface and provide light to the reflective surface. The light is provided such that it is reflected from the reflective surface and through the translucent material in order to backlight a balloon envelope seal for inspection. A method for inspecting a balloon envelope seal may include placing balloon envelope material on a table, forming a seal between portions of the material, moving a light over the seal, shining light onto a reflective portion of the table below the seal to backlight the seal, and inspecting the seal using the backlighting of the seal.

BACKGROUND

Computing devices such as personal computers, laptop computers, tablet computers, cellular phones, and countless types of Internet-capable devices are increasingly prevalent in numerous aspects of modem life. As such, the demand for data connectivity via the Internet, cellular data networks, and other such networks, is growing. However, there are many areas of the world where data connectivity is still unavailable, or if available, is unreliable and/or costly. Accordingly, additional network infrastructure is desirable.

Some systems may provide network access via a balloon network operating in the stratosphere. Because of the various forces experienced by these balloons during deployment and operation, there is a balancing of needs between flexibility and stability of materials. The balloons may be made of an envelope material configured in sections or lobes to create a “pumpkin” or lobed balloon. The lobes are supported by a plurality of tendons.

BRIEF SUMMARY

Aspects of the present disclosure relate to a system for inspecting seals for a balloon envelope. The system includes a reflective surface, a translucent material on the reflective surface, and a movable light source configured to move along the reflective surface and provide light to the reflective surface. The movable light source is configured such that light reflected from the reflective surface and through the translucent material in order to backlight a balloon envelope seal for inspection.

In one example, the movable light source is attached to a track such that the movable light source is movable along the track to provide light for inspection of the balloon envelope seal. In another example, the movable light source includes a housing having an open end and four walls arranged around the open end. Each of the four walls includes an end portion configured to press balloon envelope material against the translucent material and reduce the amount of light entering the housing which does not enter the housing through the translucent material. In another example, the movable light source includes a housing having an open end, a closed end, and one or more sidewalls arranged between the open end and the closed end. The closed end includes an image sensor configured to receive light reflected through the translucent material. In this example, the image sensor is a CCD configured to receive the light from the light source from the translucent material and generate an image of the seal. In addition or alternatively, the image sensor is configured to receive the light from the light source from the translucent material and send information about the seal to a computing device for processing. In this regard, the system also includes a computing device, wherein the computing device is configured to process the information about the seal and identify a problem with the seal. In another example, the system also includes the seal and the balloon envelope. In another example, the movable light source includes a housing having an open end, a closed end, and one or more sidewalls arranged between the open end and the closed end and at least one wing portion attached to the one or more sidewalls and a light source attached to the at least one wing. In this example, the light source includes an LED light strip. In addition, the at least one wing portion is arranged such that light from the light source travels through the translucent material, is reflected by the reflected surface back through the translucent material and into the open end of the housing. In another example, the system also includes a table, wherein the translucent material and the reflective surface are arranged on the table. In another example, the reflective surface is a mirror. In another example, the system also includes a heat sealer configured to move along a track and create the seal. The movable light source is attached to the heat sealer. In another example, the system also includes a heat sealer configured to move along a track and create the seal one portion at a time. The movable light source is configured to move along the track to backlight each portion of the seal. In another example, the movable light source includes an image sensor configured to send information to a computing device for processing. In another example, the movable light source is configured to receive instructions for moving along a track from a computing device. Another aspect of the disclosure provides a method of inspecting seals for a balloon envelope. The method includes placing balloon envelope material on a table, forming a seal between portions of the balloon envelope material, moving a movable light source over the seal, shining light from the movable light source onto a reflective portion of the table below the seal to backlight the seal, and inspecting the seal based using the backlighting of the seal.

In one example, the method also includes capturing light from the backlighting of the seal by an imaging device and sending information from the imaging device to a computing device for processing in order to inspect the seal. In another example, moving the movable light source includes moving the movable light source along a track positioned above the seal.

DETAILED DESCRIPTION

Aspects, features and advantages of the disclosure will be appreciated when considered with reference to the following description of embodiments and accompanying figures. The same reference numbers in different drawings may identify the same or similar elements. Furthermore, the following description is not limiting; the scope of the present technology is defined by the appended claims and equivalents. While certain processes in accordance with example embodiments are shown in the figures as occurring in a linear fashion, this is not a requirement unless expressly stated herein. Different processes may be performed in a different order or concurrently. Steps may also be added or omitted unless otherwise stated.

The present disclosure generally relates to providing high-altitude balloons such as those used in communication networks. A single network may include a large number of balloons, each of which includes a balloon envelope having a plurality of gores. In some examples, manufacturing of a single balloon envelope involves heat sealing portions of envelope material together in order to produce the gores. Given the nature of the use of these balloons and the resources needed to manufacture each balloon, it is important to maintain quality control of each balloon and in particular, the seals which hold together the gores. By doing so, this may significantly increase the likelihood of a successful launch and extend the life of the balloon.

To assemble a gore portion of a balloon envelope, portions of material which will form the gores are laid out on a table and then sealed together, for example, using a heat bond. This heat bond of the material can be employed using various techniques. In one example, a balloon gore sealing machine including a table and an overhead sealing component, may be used in order to at least partially automate the manufacturing process. The sealing component may be configured so that it can travel along a length of the table by traversing a track positioned above the table. The sealing component may apply a heat bonding seal in order to join together the portions in a downward pressing motion, one section at a time. In this example, the sealing component moves, seals and moves again until it completes a length of the balloon envelope made from bonding the portions together.

Once the sealing component has sealed a given portion of balloon envelope, the seal may be inspected for quality. To assist with the inspection, the seal may be backlit with a diffuse light. In some instances, the lighting may be integrated into the sealing surface of the table. This may provide a uniform background against which defects may be picked out. For a long stationary seal such as is found on a balloon gore, it may be expensive and complicated to install backlit lighting integrated into a surface along length of the table.

In another example, rather than backlighting the entire seal or an entire sealing surface of the table at once, a reflective surface may be used to backlight a seal. For instance, all or a portion of the table may include a reflective surface and a light may be positioned above the surface in order to reflect light. The reflected light may act as a back light and allow an observer to inspect the seal while the envelope material is on the table.

In other examples, rather than a human observing the reflected light directly, the inspection may be performed using an imaging device such as an image sensor. An image sensor may be configured to receive light rays from the light sources that are reflected from the mirror and through the silicone. For example, once a seal is completed, the image sensor may be positioned over the seal and lowered onto the envelope material. At least some of the light will be reflected through the seal, and eventually reach the imaging device. The light which reaches the imaging device may be processed in order to provide information about the seal, and in particular, the quality of the seal. Uniformity of the seal, and therefore the light passing through the seal may be indicative of a good seal.

The features described may provide for an efficient, economical way to inspect seal quality for high altitude balloons. In addition, by at least partially automating the inspection, this may increase consistency of the inspection and likelihood of detection of potentially problematic seals.

FIG. 1depicts an example system100in which a balloon as described above may be used. This example should not be considered as limiting the scope of the disclosure or usefulness of the features of the present disclosure. For example, the techniques described herein can be employed on various types of standalone balloons or balloons used with other types of systems. In this example, system100may be considered a “balloon network.” the system100includes a plurality of devices, such as balloons102A-F, ground base stations106and112and links104,108,110and114that are used to facilitate intra-balloon communications as well as communications between the base stations and the balloons. One example of a balloon is discussed in greater detail below with reference toFIG. 2.

FIG. 2is an example balloon200, which may represent any of the balloons of balloon network100. As shown, the balloon200includes an envelope210, a payload220and a plurality of tendons230,240and250attached to the envelope210.

The balloon envelope210may take various forms. In one instance, the balloon envelope210may be constructed from materials such as polyethylene that do not hold much load while the balloon200is floating in the air during flight. Additionally, or alternatively, some or all of envelope210may be constructed from a highly flexible latex material or rubber material such as chloroprene. Other materials or combinations thereof may also be employed. Further, the shape and size of the envelope210may vary depending upon the particular implementation. Additionally, the envelope210may be filled with various gases or mixtures thereof, such as helium, hydrogen or any other lighter-than-air gas. The envelope210is thus arranged to have an associated upward buoyancy force during deployment of the payload220.

The payload220of balloon200may be affixed to the envelope by a connection (not shown) such as a cable. The payload220may include a computer system (not shown), having one or more processors and on-board data storage. The payload220may also include various other types of equipment and systems (not shown) to provide a number of different functions. For example, the payload220may include an optical communication system, a navigation system, a positioning system, a lighting system, an altitude control system and a power supply to supply power to various components of balloon200.

In view of the goal of making the balloon envelope210as lightweight as possible, it may be comprised of a plurality of envelope lobes or gores that have a thin film, such as polyethylene or polyethylene terephthalate, which is lightweight, yet has suitable strength properties for use as a balloon envelope. In this example, balloon envelope210is comprised of envelope gores210A-210D.

Pressurized lift gas within the balloon envelope210may cause a force or load to be applied to the balloon200. In that regard, the tendons230-250provide strength to the balloon200to carry the load created by the pressurized gas within the balloon envelope210. In some examples, a cage of tendons (not shown) may be created using multiple tendons that are attached vertically and horizontally. Each tendon may be formed as a fiber load tape that is adhered to a respective envelope gore. Alternately, a tubular sleeve may be adhered to the respective envelopes with the tendon positioned within the tubular sleeve.

Pressurized lift gas within the balloon envelope210may cause a force or load to be applied to the balloon200. In that regard, the tendons230provide strength to the balloon200to carry the load created by the pressurized gas within the balloon envelope210. In some examples, a cage of tendons (not shown) may be created using multiple tendons that are attached vertically and horizontally. Each tendon may be formed as a fiber load tape that is adhered to a respective envelope gore. Alternately, a tubular sleeve may be adhered to the respective envelopes with the tendon positioned within the tubular sleeve.

Top ends of the tendons230and250may be coupled together using an apparatus, such as termination plate240positioned at the apex of balloon envelope210. Bottom ends of the tendons230may also be connected to one another. For example, a corresponding apparatus, e.g., base plate (not shown), may be disposed at a base or bottom of the balloon envelope210. The termination plate240at the apex may be the same size and shape as and base plate at the bottom of the balloon envelope. Both plates may include corresponding components for attaching the tendons230to the balloon envelope210.

In one example, a balloon gore sealing machine or assembly including a table may be used. InFIG. 3, one example of a table component300for the assembly is shown. As shown, the table component300includes a first level302and a second level304and an indicator306disposed on a surface303of the first level302. The indicator306may be used to mark a position on the table component300for placing a tendon on an envelope gore being manufactured. The table component.300made me used for shaping and heat-sealing together individual envelope gores made from sheets of balloon material308(shown as rolled). In this regard, the table component300also includes a curve strip310that can be used to indicate where the heat seal may occur, for example, at an edge of the envelope gore created from the roll of balloon material303.

A sheet of the material308may be fed onto the table component300in order to create a given envelope gore. For example, a straight sheet of the balloon material308may be rolled out onto the table either manually or automatically using a belt driven track (not shown). Once the balloon material308is rolled out, it may be held down on the table component300using a series of restraints or clamps312. The series of clamps312may help keep the balloon material308from shifting while it is being worked on.

First level302may be a working area of the table component300. The first level302may include a smooth top layer of a compliant material, such as fiberglass and/or silicone, or other types of types of similar materials that have a level of heat resilience. The table component300may include also additional heat resistant material where the heat seal occurs, such as at curve strip310. The curve strip310may include additional material, such as fiberglass impregnated with a polytetrafluoroethylene (PTFE) coating, which has a higher melting point than the top layer coating of the table component300. This extra coating may also help prevent the material308from sticking to the table component300due do the heat sealing being conducted at the strip310.

Second level304of the table component300may be configured for stacking up assembled envelope gores of the balloon envelope. For example, the second level304may include a trough like resting area for holding the envelope gores during manufacture. A surface305of the second level304may be configured so that the surface is wide enough to stack up a plurality of assembled envelope gores including the tendon attached to each gore portion.

An overhead heat sealer may be used in order to at least partially automate the manufacturing process.FIG. 4is an example of a heat sealing component450for the assembly. In this example, the sealing component450includes a sealing device452coupled to the track456via an actuating arm454. In some examples, a control unit460may be utilized for controlling operations of the sealing component450using communication link462, which can be a wired or wireless link.

Sealing device452may include an electrically heatable element451disposed on the device. The heatable element451may be of a predetermined width and length that may be used to unite layers of the balloon material. For example, the heatable element451, when activated, for example by a flow of electricity, may reach a certain temperature that is hot enough to heat bond or otherwise melting a section of two sheets of balloon material together. In some embodiments, sealing device452may provide a combination of operations for heat sealing and cutting of the balloon material308. For example, the sealing device452may be configured to cut the balloon material308by using heat and an amount of pressure or blade like cutting members (not shown) attached to the heatable element451.

The sealing component450may be configured so that it can travel along a length of the table by traversing a track positioned above the table. For example, sealing device452may be moved along track456mounted on an overhead support457. The track456can be configured so that sealing device452can move forward and back horizontally by using actuating arm454. This forward and back movement of the sealing device452along track456can be manually or automatically operated, for example, by using commands from the control unit460.

The actuating arm454can also be activated to cause the sealing device452to move vertically. For example, the actuating arm454may include housing (not shown) that can extend and retract the arm between first and second positions. In some aspects, extension of the actuating arm454allows the sealing device452to be pressed against the balloon material in order to cause the heat bond activation. As with the movement along track456, the actuating arm454can extend and/or retract manually, automatically or some combination thereof, for example, by using commands from control unit460.

FIG. 5is an example of a balloon gore sealing assembly500, which may include machinery components such as the table component300and sealing component400as described above. The assembly500may be used to manufacture envelope gores for balloons. To join the sheets of film material together, sealing component450may move forward and back from one end of table component300to an opposite end, thereby traversing along a length of the table component300. The sealing component450may operate by heat sealing a section, for example by one meter more or less in length, of the balloon envelope material308resting on the first level. For example, sealing component450may be pressed down on the table component300for heating sealing a particular section of the envelope gore material and subsequently lifted up and moved to a next section to be heat sealed. This up, move and down motion of the sealing component450can be repeated until the entire length of the laid out material is heat sealed in successive sections resulting in a completed envelope gore. The process of manufacturing envelope gores can be repeated with the successive sheets of material308until a sufficient number of gores have been manufactured.

Once the sealing component450has sealed a given portion of balloon envelope, the seal may be inspected for quality. In some examples, the inspection may be performed immediately after a seal is completed. This may involve a manual inspection (by an operator) or may be partially or fully automated. For example, a seal may be inspected to insure that the seal was fully formed (i.e. there are no gaps along the seal), that the envelope material is properly arranged (i.e. there are no unintentional folds or gathers in the material), that no debris is within the seal, etc. As an example, a good seal should appear to be uniform along the length of the seal.

To assist with the inspection, the seal may be backlit with a diffuse light. In some instances, the lighting may be integrated into the sealing surface of the table. This may provide a uniform background against which defects may be picked out. For a long stationary seal such as is found on a balloon gore, it may be expensive and complicated to install backlit lighting integrated into a surface along length of the table.

In another example, rather than backlighting the entire seal or the entire sealing surface of the table at once, a reflective surface may be used to backlight a seal. For instance, all or a portion of the table may include a reflective surface520(more clearly shown inFIG. 7) and a light may be positioned above the surface. The reflective surface520may include a mirror or mirror finish may be applied to the table on which the heat seals will be made. In addition, a layer510of translucent material, such as silicone, may be placed on top of the mirror to form the sealing surface and to better facilitate the heat sealing process. This layer may thus correspond to the curve strip310of the table component300. The mirror may be used to reflect light from above the surface of the table through the silicone and the seal. The reflected light may act as a back light and allow an observer to inspect the seal while the envelope material308is on the table component.

In some examples, a light source may be incorporated into a lighting system that is attached to or separate from the sealing component450.FIG. 6is an example of aspects of a lighting system650. The lighting system may include a movable inspection device652including the light source. In this example light sources654and658are incorporated into respective wing portions664and668which are attached to a housing660. The movable inspection device may be automated and follow the same or a similarly arranged track as the sealing component450. As shown in the example ofFIG. 6, lighting system650is depicted as separate from sealing component450. However, in some examples, movable inspection device652may be attached to or simply placed adjacent to sealing component450during operation.

In some examples, a control unit680may be utilized for controlling operations of the light system650using communication link662, which can be a wired or wireless link. In this regard, the control unit680and communication link662may be the same or similarly configured as control unit460and communication link662.

Track656may correspond to track456. In this way, lighting system650may be configured so that it can travel along a length of the table by traversing a track positioned above the table. For example, housing650may be moved along track656mounted on an overhead support657. As with track456and sealing component450, track656can be configured so that lighting system650can move forward and back horizontally by using actuating arm651. This forward and back movement of the housing650along track656can be manually or automatically operated, for example, by using commands from the control unit460.

In other examples, track656may be the same track as657. Thus, once the sealing component450has completed a seal and moves onto the next seal location, the movable inspection device652may follow immediately behind the sealing component450on track656/456and light the seal.

As with actuating arm454, actuating arm654can also be activated to cause the housing652to move vertically. For example, the actuating arm651may include housing (not shown) that can extend and retract the arm between first and second positions. In some aspects, extension of the actuating arm651allows the housing652to be pressed against the balloon material308during inspection. As with the movement along track652, the actuating arm651can extend and/or retract manually, automatically or some combination thereof, for example, by using commands from control unit680.

In other examples, rather than a human observing the reflected light directly, the inspection may be performed using an imaging device.FIG. 7is a cross sectional view of the housing652shown in a configuration where the housing is pressed against the table component300during an inspection of the seal.FIG. 8is a view from the perspective of arrow A inFIG. 6in order to illustrate the internal configuration of the housing652.FIG. 9is an example 900 of lighting system650depicted above the table component300. For simplicity, sealing component450is not shown, but may also hang from track656(here, the same as track456) adjacent to the movable inspection device652via the actuating arm454.

In the examples ofFIGS. 7-9, the housing652includes a top portion710and four walls720,722,724,726(best shown inFIG. 8) that extend away from the top portion. As noted above, two wing portions664and668each including a respective light source654and658are attached to the housing660at a preselected angle. The light sources may include LED light strips. The angle may be preselected to ensure that adequate light from the light sources will be reflected off of the reflective surface520and back to an imaging device. The top portion of the housing may include an imaging device730mounted thereon.

The imaging device730may include a camera or charge coupled device (CCD) image sensor. An end portion of each wall includes a respective seal portion740,742,744,746. These seal portions may be configured to press envelope material308against the layer510of translucent material of the table component300and prevent light from hitting a surface of the layer510from within the housing660below the imaging device.

The imaging device730may be configured to receive light rays from the light sources654and658that are reflected from the reflective surface520and through the layer510. For example, once a seal is completed, the housing652may be positioned over the seal and lowered onto the envelope material308using actuating arm651. The seal portions740,742,744,746of the walls720,722,724, and726then press the envelope material308against the layer510sealing out any light which would come from within the housing.

Light rays from the light sources654and656may then shine through the layer510and onto the reflective surface520. At least some of the light rays will be reflected through the layer510, through the seal, and eventually reach the imaging device730. The amount of light that reaches the imaging device730is related to the preselected angle of the wing portions664and668as well as the position of and amount of light generated by the light sources654and656. The light which reaches the imaging device may be processed in order to provide information about the seal, and in particular, the quality of the seal. Again, uniformity of the seal, and therefore the light passing through the seal may be indicative of a good seal.

To better aid in understanding an example of some of the aspects described above, reference is now made toFIG. 11, which illustrates a flow diagram1000depicting a method of manufacturing a balloon envelope. As previously discussed, the following operations do not have to be performed in the precise order described below. Rather, as mentioned above, various operations can be handled in a different order or simultaneously, and operations may be added or omitted.

In this example, balloon envelope material is placed on a table at block1010. A seal is formed between portions of the balloon envelope material at block1020. A movable light source is moved over the seal at block1030. This may include moving the movable light source along a track positioned above the seal. Light is shined from the moveable light source onto a reflective surface portion of the table below the seal to backlight the seal at block1040. Light from the backlighting of the seal is captured by an imaging device at block1050. Information from the imaging device is sent to a computing device for processing at block1060. And, at block1070, the seal is inspected using the backlighting of the seal and the processed information.

Most of the foregoing alternative examples are not mutually exclusive, but may be implemented in various combinations to achieve unique advantages. As these and other variations and combinations of the features discussed above can be utilized without departing from the subject matter defined by the claims, the foregoing description of the embodiments should be taken by way of illustration rather than by way of limitation of the subject matter defined by the claims. As an example, the preceding operations do not have to be performed in the precise order described above. Rather, various steps can be handled in a different order or simultaneously. Steps can also be omitted unless otherwise stated. In addition, the provision of the examples described herein, as well as clauses phrased as “such as,” “including” and the like, should not be interpreted as limiting the subject matter of the claims to the specific examples; rather, the examples are intended to illustrate only one of many possible embodiments. Further, the same reference numbers in different drawings can identify the same or similar elements.