Patent Grant
7862394
Not Applicable.
This invention relates generally to buoys and, more particularly, to a buoy to which an electronic camera assembly is coupled, wherein the buoy has characteristics to reduce a motion of the buoy to provide a stable camera image.
Many types of flotation devices exist with differing characteristics.
Damper plates and toroid shaped flotation devices have been used to create buoys in the form of so-called “wave follower” buoys. For example, see Buoy Engineering, H. O. Berteaux, John and Sons, 1976 Pg. 212-213. Wave follower buoys are subject to relatively small amounts of motion relative to the motion of the ocean surface that they follow. However, in the presence of waves, the wave follower buoy experiences a relatively large amount of absolute heave and pitch due to the heave and pitch of the wave surfaces.
A so called “spar buoy” has less absolute heave and pitch as it tends to have a smaller cross section at the water level than a wave follower buoy, but unless the spar buoy has substantial length it will submerge in larger waves. Mass of the spar buoy can also be distributed to create a righting moment. This will decrease absolute pitch. However, spar buoys tend to experience large amounts of rotation about a central vertical axis, vertically oriented relative to the surface of the water.
An object suspended beneath a spar buoy in the presence of waves has a tendency to increase the absolute pitch, roll, and heave of the spar buoy.
It would be desirable to provide a buoy having reduced amounts of rotation about a central vertical axis than a spar buoy in some applications.
The present invention provides a floating platform to carry an electronic camera assembly configured to provide an image. The floating platform has enough stability in six degrees of motion, including in azimuth rotation, to allow the image generated by the electronic camera assembly to be stable.
In accordance with one aspect of the present invention, apparatus includes a buoyant structure having a central vertical axis when floating in water and having at least one feature to reduce a rotation of the buoyant structure about the central vertical axis when floating in the water. The apparatus further includes an electronic camera assembly coupled to the buoyant structure. The electronic camera assembly is configured to generate an electronic image signal. The apparatus further includes a tubular structure coupled to the buoyant structure and configured to remain under the surface of the water. The tubular structure includes a watertight compartment and an electronic circuit assembly disposed within the watertight compartment. The electronic circuit assembly is coupled to receive the electronic image signal and is configured to generate an optical image signal representative of the electronic image signal. The apparatus further includes a fiber optic cable coupled to the electronic circuit assembly and configured to carry the optical image signal.
In some embodiments, the at least one feature to reduce a rotation of the buoyant structure comprises a virtual mass of water disposed proximate to an outer sidewall of the buoyant structure. In other arrangements, the at least one feature comprises a fin member coupled to a least one of the buoyant structure or the tubular structure.
The foregoing features of the invention, as well as the invention itself may be more fully understood from the following detailed description of the drawings, in which:
Before describing the present invention, some introductory concepts and terminology are explained. As used herein, the term “buoyant” is used to describe an object for which, when floating in a liquid, a buoyant force acting upward upon a center of buoyancy of the object is greater than a force of gravity acting downward upon a center of mass of the object. In other words, the object tends to float in the liquid. The force of gravity can include a force of gravity of a submerged object suspended beneath and coupled to the buoyant object and the center of mass can be a combined center of mass of the buoyant object and the submerged object.
As used herein, the term “virtual mass” is used to describe an entrained volume of water (or other liquid), which fills or partially fills a cavity upon the below-described apparatus when the below-described apparatus is in water. The virtual mass, being entrained, has inertia. The virtual mass can fill and drain from the apparatus as the buoy heaves and at a relative rate relative to a wave period.
As will be understood, the apparatus can have a particular center of mass at a particular position (and relative to the water surface), and the apparatus can have a different “virtual center of mass” at a different particular position (and relative to the water surface).
It will also be understood that motion can be described as having six degrees, linear motion along three orthogonal axes and rotational motion about each of the three orthogonal axes. In general, the three orthogonal axes are fixed relative to the earth. The linear displacement motions are sometimes referred to as heave, sway, and surge. The rotational motions are sometimes referred to as pitch, roll and yaw. As used herein, the term “azimuth rotation” will be understood to be the same as yaw when two axes of the fixed coordinate system are horizontal.
Referring now to
The assembly can also include a battery 36 coupled to power at least the electronic circuit assembly 31.
In some embodiments, the electronic image signal and the optical image signal are representative of still images, e.g., snapshots, taken by the electronic camera assembly 20. In other arrangements, the electronic image signal and the optical image signal are representative of video images, e.g., moving images, taken by the electronic camera assembly 20.
In some embodiments, the electronic image signal and the optical image signal are representative of images of visible light taken by the electronic camera assembly 20. In other arrangements, the electronic image signal and the optical image signal are representative of images of infrared light taken by the electronic camera assembly 20. In some embodiments, the electronic image signal and the optical image signal are representative of images of both visible light and infrared taken by the electronic camera assembly 20
The tubular structure can also include a compartment 33 configured to flood with water, W. To this end, the compartment 33 can have holes 14.
In some embodiments, the buoyant structure 1 is an inflatable bag 1 in the form of an inflated balloon-like structure having a specific gravity less than the specific gravity of the water, W. In some embodiments, the inflatable bag 1 has a concave bottom 16. The inflatable bag 1 supports the tubular structure 3 below a surface of water, W, which tubular structure 3 would otherwise sink.
Although, in the apparatus 10, the buoyant structure 1 comprises the inflatable bag 1, in other embodiments, the buoyant structure 1 can be a flotation device of any type. Another exemplary embodiment is shown in
In some embodiments, the inflatable bag 1 includes a damper skirt 4 that extends around the base of the inflatable bag 1 in a direction approximately perpendicular to the central vertical axis la, i.e., essentially horizontally. The damper skirt 4 can be made of a semi-rigid material. The damper skirt 4 can be supported by a ribbon fence 5. The ribbon fence 5 can form a plurality of compartments, e.g., 5a-5h, which plurality of compartments may also include compartments (not shown) around the backside of the inflatable bag 1. The ribbon fence 5 is described in greater detail below in conjunction with
When the apparatus 10 is floating in the water, W, the damper skirt 4 is below the surface of the water, W. The in-water weight of the tubular structure 3 and the buoyancy of the inflatable bag 1 are configured so that the damper skirt 4 is below the surface of the water, W.
The damper skirt 4 provides a surface having a surface area in contact with the water, W, which surface resists vertical motion, V, within the water, W. In order to move vertically (heave) or tip (pitch and/or roll) relative to the surface of the water, W, in response to a wave in the water, W, the damper skirt 4 or a part of the damper skirt 4 must travel vertically through the water, W. A resistance to vertical movement of the damper skirt 4 is provided by the water above and/or below the damper skirt 4. Wave energy that would otherwise cause relative heave and/or pitch and roll of the inflatable bag 1 relative to the surface of the water, W, is dissipated by this resistance against vertical movement of the damper skirt 4 within the water, W. In essence, the inflatable bag 1 tends to follow the up and down (heave) and angular (pitch and roll) motion of waves. The buoyant structure 1 thus represents a so-called wave follower buoy.
It should be recognized that waves tend to have relatively small surface angles, for example, on the order of ten to fifteen degrees. Thus, the pitch and roll of a wave follower buoy are limited.
Referring now to
Referring now briefly to
Referring again to
Compartments 5a-5h act as containers for the water, W, partially entraining water, and therefore, forming a virtual mass. Taking the compartment 5a as representative of the other compartments 5b-5h, fluid can enter the compartments 5a through the hole 6 or the open top 7 and can drain from the compartment 5a through the hole 6. The hole 7 is sized in relation to a period of surface waves so that the ribbon fence 5 generally retains water.
When the inflatable bag 1 rises due to the motion of the water, some water tends to drain out of the holes, e.g., the hole 6, dissipating kinetic energy of the inflatable bag 1 created by the rising motion of the ocean. Vertical motion of the inflatable bag 1 relative to the surface of the water, W, is thereby reduced.
The compartments 5a-5h can further increase the resistance to vertical motion of the inflatable bag 1 relative to the surface of the water, W, by partially enclosing the water, W, and therefore, forming the virtual mass. The virtual mass essentially requires the damper skirt 4 to vertically move the virtual mass of water within the compartments 5a-5h as the inflatable bag 1 otherwise attempts to move vertically relative to the surface of the water, W, in response to a wave. The virtual mass has inertia, which acts to further decrease the heave and pitch (and/or roll) of the inflatable bag 1 relative to the surface of the water, W.
Furthermore, the virtual mass of water entrained in the compartments 5a-5h provides the above-described at least one feature configured to reduce a rotation of the buoyant structure 1 about the central vertical axis 20 when floating in the water, W. The virtual mass provides an inertia spaced out from the central vertical axis 20. That inertia resists rotation by any force causing a torque about the central major axis 20. In some arrangements, an outer largest diameter of the ribbon fence is about fourteen inches, and a diameter of the sidewall Is of the inflatable bag 1 is about ten inches.
Furthermore, with regard to rotation, the ribbon fence 5, being spaced apart from the central vertical axis 1a by a relatively large amount, and also, therefore, having a relatively large surface area in contact with the water, W, also tends to reduce a rotation of the buoyant structure about the central vertical axis 1a due to surface tension and drag upon the surface of the ribbon fence 5 if rotation were to occur.
It should be understood that rotation about the central vertical axis 1a is not precisely the same as yaw or azimuth rotation, both of which generally refer to a fixed coordinate system. Instead, the central vertical axis 1a can move as the buoyant structure 1 moves angularly due to wave motion. However, reduction of rotation about the central vertical axis 1a does tend to reduce yaw or azimuth rotation of the buoyant structure 1.
The damper skirt 4 and ribbon fence 5 are described to be associated with each other, each constructed from semi-rigid materials for the purpose of stabilizing the inflatable bag 1, when in the presence of waves. However, in other arrangements, the damper skirt 4 is a submerged damper plate and the ribbon fence 5 is not used. The damper plate alone can also decrease both the heave and pitch of the apparatus 10 relative o the surface of the water, W.
The tubular structure 3 comprises the electronics circuit assembly 31 enclosed in a watertight compartment 32. In some embodiments, the tubular structure 3 is coupled to the bottom of the buoyant structure 1 by a nylon cord 8. One end of the nylon cord 8 can connect to a point 8a within the tubular structure 3 approximately one-quarter from the top of the tubular structure 3 and the other end can connect to a center of a bulkhead 9, which is a rigidly coupled to the inflatable bag 1. Electrical wires 35 pass from the electronics circuit assembly 31 into and though the bulkhead 9 and into the inflatable bag 1. Beneath the bulkhead 9 is a bumper 39.
The nylon cord 8 and the location of the couplings at 8a and 8b between the tubular structure 32 and the inflatable bag 1, decouple the motion of inflatable bag 1 from the tubular structure 3 such that, over a certain range, motion of inflatable bag 1 does not affect the motion of tubular structure 3 and the motion of the tubular structure 3 does not affect the motion of inflatable bag 1. The range of motion depends on the dimensions of the decoupling apparatus including the diameter of the tubular structure 3 and the distance between the top of the tubular structure 3 and bumper 39.
The tubular structure 3 is free to tilt until the top of the tubular structure 3 collides with the bumper 39. Similarly, the inflatable bag 1 can freely pitch and/or roll until the bumper 39 collides with the top 32a of the tubular structure 3.
In some arrangements, the tubular structure 3 can tilt relative to the inflatable bag 1 by at least ten to fifteen degrees before contact between the tubular structure 3 and the bumper 39. The bumper 39 absorbs some of the energy of an impact between the inflatable bag 1 and the tubular structure 3, decreasing the effect such impact would have on motions of the inflatable bag 1, and also preventing damage to the inflatable bag 1 that would otherwise result from direct impact between the inflatable bag 1 and the tubular structure 3. The bumper 39 also protects the electrical wiring 35 that feeds into the inflatable bag 1, preventing interruption or interference with electrical signals carried in the wires 35 due to impacts between the tubular structure and the bulkhead 9 through which wires 35 pass.
The compartment 33 of the tubular structure 3, also referred to herein as a collar, stores the entire buoyant structure 1 before it is deployed, as shown in
The flooding of the compartment 33 results in the center of mass of the tubular structure 3 being lower in the water, W, increasing the period of swing of the tubular structure 3 relative to the inflatable bag 1. This stabilizes the entire apparatus 10 and decreases the heave, pitch, and roll of the inflatable bag 1 relative to the surface of the water, W.
In some embodiments, the center 15 of the bottom 16 of the inflatable bag 1 is pulled upward by straps 13 secured at regions 36, along the inside wall of inflatable bag 1, resulting in the concave bottom 16. This reduces the buoyancy of inflatable bag 1, aiding in maintaining the waterline above the damper skirt 4 and approximately at the midpoint of the ribbon fence 5. The bottom 16 of the inflatable bag 1 can be upwardly arched at its center 15 so that the greatest buoyant forces are located at the outer portions of the inflatable bag 1. This shape decreases the pitch and roll of the inflatable bag 1 by creating a longer torque arm, which must be overcome for the inflatable bag 1 to pitch or roll. This righting moment further aids in stabilizing the inflatable bag 1. Furthermore, adhesion to the water, W, caused by the upwardly arched center 15 also tends to decrease the heave of the inflatable bag 1.
Although the apparatus 10 has the inflatable bag 1 with the concave bottom 16, in other embodiments, the buoyant structure 1 can be comprised of any material with a bottom having an upwardly arched shape.
Referring now to
In some embodiments, the antennas 60, 62 are patch antennas or arrays of patch antennas. In some embodiments, the radar detection antenna 56 and the AIS antenna 56 are comprised of a gas bottle 56 used to hold a gas, for example CO2 to inflate the inflatable bag 1. An inflation mechanism 58 can puncture the gas bottle 56 upon deployment of the apparatus 10 (
In some embodiments, the UHF antenna 50 is a UHF satellite communications antenna having four vertical portions, only two of which 50a, 50b are shown, and having upper and lower joining portions 50c, 50d. In some embodiments, straps 52a-52d generate tension upon the vertical portions 50a-50b, holding them in a vertical orientation.
In some embodiments, the UHF antenna 50 is right circularly polarized and is comprised of conductors imprinted upon flex circuit material.
In order to operate in the above-described bands, the electronic circuit assembly 31 of
Referring now to
As described above, each one of the electronic camera signals 76a-76d can be representative of still images or moving video images. Also, each one of the electronic camera signals 76a-76d can be representative of images of visible light, or infrared light, or of both.
As is known and as described above, motion can be described in terms of six degrees of motion; linear motion along three orthogonal axis and rotational motion bout each one of the three orthogonal axes. The image correction provided by the image processor 76 can provide image stabilization in one, two, three, four, five, or six degrees of motion.
The image processor 78 is also configured to combine processed signals representative of the electronic camera signals 76a-76d into an electronic image signal representative of a panoramic view azimuthally about the buoyant stricture 1. In some embodiments, the panoramic view is throughout three hundred sixty degrees in azimuth.
Each lens 74a, 74d has a focal length selected and/or each CCD has a number of pixels selected to achieve an azimuth viewing angle so that a ship at a horizon range from the apparatus 10 occupies at least one pixel associated with at least one of the plurality of cameras 70a-70d. In some embodiments, the focal length of each lens 74a-74d is about three millimeters. In some embodiments, each one of the CCDs 72a-72d has 350,000 pixels for each of three colors.
The electronic camera assembly 20 can also include an inertial sensor 84 coupled to provide an inertial signal 86 to the image processor 78. The electronic camera assembly 20 can also include an electronic compass 80, for example, a flux gate compass 80, coupled to provide a compass signal 82 to the image processor 78. The inertial signal 86 and the compass signal 82 can be used by the image processor 78 in order to provide the above-described image stabilization.
The image processor is configured to generate an optical image signal 88 carried by the optical fiber cable 22 of
Referring now to
The distortion removal module 100 is configured to remove optical distortions primarily attributable to the lenses 74a-74d. To this end, the distortion removal module 100 can receive lens calibration data values 118 from a lens calibration data array 116 stored in a memory. The lens calibration data array 116 can be generated and stored at the time of manufacture of the electronic camera assembly 20 by one of a number of techniques know to one of ordinary skill in the art. The lens calibration values 116 can essentially reduce aberrations, improving the rectilinear nature of the scene so that vertical or horizontal lines, such as the horizon, are restored to straight lines in the output imagery.
The image processor 78 can also include a pitch and roll stabilization module 102 coupled to receive distortion corrected signals 100a-100d from the distortion removal module 100 and configured to generate pitch and roll stabilized signals 102a-102d. While shown as one module, the pitch and roll stabilization module 102 can include two separable portions. A first portion of the pitch and roll stabilization module 102 can receive the inertial measurement signal 86 from the inertial measurement unit 84 and the compass signal 82 from the electronic compass 80. With the inertial data 86 and with the compass data 82, the pitch and roll stabilization module 102 can coarsely adjust the lens calibrated signals 100a-100d to reduce apparent pitch, roll, and yaw (or azimuth) rotational movements of the electronic camera assembly 20 (FIGS, 1, 2, and 6).
In some embodiments, a second portion of the pitch and roll stabilization module 102 can also make finer corrections to reduce the apparent pitch, roll, and yaw (or azimuth) rotational movements of the electronic camera assembly 20. In some arrangements, the pitch and roll stabilization module 102 can automatically find and track features in the scene such as a horizon, for example, by contrast between the sky and the water, within the lens-calibrated signals 100a-102d and can make adjustments to the lens calibrated signals 100a-100d to keep the horizon and earth-fixed features stationary.
It should be understood that, once the images represented by the electronic camera assembly 20 are stabilized in pitch and roll, then the images are related to a fixed coordinate system, and the last rotation, which is referred to above as a mechanical rotation of the buoyant structure 1 (
A panorama generation module 104 can combine or stitch together the images represented by the pitch and roll stabilized signals 102a-102d to provide a panoramic signal 106 representative of a panoramic view about the electronic camera assembly 20. In some embodiments, the panoramic signal 106 is representative of a three hundred sixty degree panoramic view in azimuth about the electronic camera assembly 20.
The pitch and roll stabilization module 102 and the panorama generation module 104 can be coupled to receive camera alignment data values 122 from a camera alignment data array 120 stored in a memory. The camera alignment data values 122 can represent axial and rotational alignments of the four electronic camera assemblies relative to a coordinate system, for example, a Cartesian coordinate system.
An azimuth stabilization module 108 can further stabilize the panoramic signal 106 in azimuth to provide a stabilized panoramic signal 110. The azimuth stabilization module 108 can be coupled to receive the compass signal 82 and can be configured to adjust or stabilize the stabilized panoramic signal 110 according to compass rotations.
Without the above described at least one feature (e.g., the virtual mass within the compartments 5a-5h,
The stabilized panoramic signal 110 can be received by an optical converter 112, which can convert the stabilized panoramic signal 110 to an optical stabilized panoramic signal 114. The optical stabilized panoramic signal 114 can be coupled to and carried by the fiber optic cable 122 of
In one particular embodiment, the optical stabilized panoramic signal 114 (i.e., the fiber optic cable 22) is coupled to a submarine (see, e.g.,
When one or more of the systems 132 are included, the image processor 78 can include a combining module 126 configured to combine the stabilized panoramic signal 114 with signals 130 to and/or from one or more of the radio elements 132. The combining module 126 can generate a combined signal 128, which combined signal can couple to the optical converter 112, in which case the signal 114 is a combined optical signal having information to/from all of the combined elements 132 and also having the optical stabilized panoramic signal.
The optical stabilized panoramic signal 114 or the combined signal 114 can be the same as or similar to the stabilized signal 88 of
It should be appreciated that
Alternatively, the processing and decision blocks represent steps performed by functionally equivalent circuits such as a digital signal processor circuit or an application specific integrated circuit (ASIC). The flow diagrams do not depict the syntax of any particular programming language. Rather, the flow diagrams illustrate the functional information one of ordinary skill in the art requires to fabricate circuits or to generate computer software to perform the processing required of the particular apparatus. It should be noted that many routine program elements, such as initialization of loops and variables and the use of temporary variables are not shown. It will be appreciated by those of ordinary skill in the art that unless otherwise indicated herein, the particular sequence of blocks described is illustrative only and can be varied without departing from the spirit of the invention. Thus, unless otherwise stated the blocks described below are unordered meaning that, when possible, the steps can be performed in any convenient or desirable order.
Referring now to
At block 154, distortion is removed, for example, as described above in conjunction with the distortion removal module 100 of
At block 156, the horizon is stabilized, i.e., the images are stabilized in pitch and roll, for example, as described above in conjunction with the pitch and roll stabilization module 102 of
At block 158, the pitch and roll stabilized signals (e.g., 102a-102d,
At block 160, the panorama (e.g., 108,
At block 162, the stabilized panoramic signal is converted to an optical signal (e.g., 114,
Lens calibration data values 164 (e.g., 118,
Referring now to
The apparatus 170 would behave like a spar buoy subject in particular to an unacceptable amount of rotation about a central vertical axis 172a, however, the apparatus 170 also includes features, i.e., fin members 174a, 174b, that prevent substantial and rapid rotation of the apparatus 170. As described below in conjunction with
Prior to deployment of the apparatus 170, the buoyant structure 172 can be contained within the compartment 33. Upon deployment, by way of its own buoyancy, the buoyant structure 172, a cylindrical buoy, can move upward relative to the tubular structure 3, and the compartment 33 can flood with water through the holes 14. An end 172a of the buoyant structure 172 can remain within the compartment 33, retained to the tubular structure 3 with a cord or the like.
In some other embodiments, the buoyant structure 172 deploys to a position entirely outside of the compartment 33 and the apparatus 170 can include the bumper 39 of
While the fin members 174a, 174b are shown to be coupled to the tubular structure 3, in other embodiments, the fin members 174a, 174b can be coupled instead to the cylindrical buoy 172.
Referring now to
For above-described alternate embodiments for which the feature 182 is coupled to the buoyant structure 172 of
Referring now to
Referring now to
Referring now to
Referring now to
Referring now to
Referring now to
In some embodiments, the launch tube 202 is a conventional submarine launch tube, conventionally used for deployment of communication type buoys.
A lift body 206 can be coupled to the fiber optic cable 22, here indicated to have two portions 22a, 22b, in order to lift the fiber optic cable up and away from the submarine, and in particular, up and away from a propeller 204. The lift body can be the same as or similar to a lift body described in U.S. patent application Ser. No. 11/613,426, filed Dec. 20, 2006, which application is incorporated by reference herein in its entirety.
In some embodiments, the portions 22a, 22b of the fiber optic cable 22 are coupled together at the lift body 206.
In some embodiments, at least the portion 22a is deployed from a spool within the lift body and 206. In some embodiments, the portion 22a can be more than one kilometer long, for example, five kilometers long. In some embodiments, the portion 22a deploys from the lift body 206 as the submarine moves through the water and while the buoyant structure 1 is on the surface of the water, resulting in minimal tension upon the portion 22a. Once the portion 22a is fully deployed, one or both of the portions 22a, 22b can be automatically cut.
In other embodiments, the portion 22a is deployed from a spool within the tubular structure 3.
All references cited herein are hereby incorporated herein by reference in their entirety. Having described preferred embodiments of the invention, it will now become apparent to one of ordinary skill in the art that other embodiments incorporating their concepts may be used. It is felt therefore that these embodiments should not be limited to disclosed embodiments, but rather should be limited only by the spirit and scope of the appended claims.
This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/053,172 filed May 14, 2008, which application is incorporated herein by reference in its entirety.
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