Patent Application
20160016649
Aspects and embodiments of the invention are directed to Autonomous Underwater Vehicles (AUVs) and methods for controlling an AUV; more particularly, AUVs equipped and enabled to operate in a hover mode and methods for controlling the operational hover mode as well as its engagement and disengagement.
Autonomous Underwater Vehicles (AUVs) are well developed and used in numerous subsea applications, most notably collecting bathymetric data and ocean bottom imaging by means of sensors carried aboard. As the name implies, these vehicles operate autonomously without pilots, unlike Remotely Operated Vehicles (ROVs), which typically include a coupled tether management system (TMS) as known in the art. Although AUVs may have an acoustic communication mechanism for communication with a separated, distant launch/retrieval platform, for the most part a flight plan is loaded into an onboard computer, the vehicle (AUV) is lowered into the water, and it flies that flight plan usually following the marine bottom closely to collecting data of interest.
AUVs generally carry their own onboard power source such as batteries or fuel cells, further differentiating them from ROVs. The onboard power source must power both the vehicle's propulsion as well as the onboard instrumentation. To minimize the power used for propulsion and maximize battery life and mission duration almost all AUVs take the shape of a torpedo, as illustrated in
Depending on the mission and depth rating of the AUV, its length, girth, and weight can range quite broadly. Shallow rated vehicles, e.g., may be as small as 6 feet in length, 10 inches in diameter, and weigh only a few hundred pounds (e.g., Bluefin Robotics). AUVs depth rated to 10,000 feet or more may commonly be as long as 21 feet, 40 inches in diameter, and weigh between 2000 and 3300 pounds in the air (e.g., Kongsberg; C&C Technologies). As known, all AUVs are made near neutrally buoyant in the water by use of syntactic foam or other recognized means.
The aforementioned torpedo design conserves power, allowing for longer missions given a fixed amount of power. AUVs of this design are typically capable of two-day long missions, although advances in battery and fuel cell technology promise longer duration missions in the future. Of these torpedo-like AUVs, there are some generally shared features amongst all of them. For example, propulsion derives from a variable speed propeller driven by an electric motor near or at the rear of the vehicle (
AUVs of this aforementioned style are very mature and capable, and are used in all of the oceans of the world for survey work. Their dependence, however, on the hydrostatic forces of water acting on their flight surfaces or the body of the vessel for control, which is largely derived from their forward motion through the water, ill adapts them for hovering still and controlled hovering in the water column. While horizontal and vertical thrusters could be added to the vehicle to add this capability, this substantially adds to the vehicle's complexity and cost as well as adding drag that affects speed and/or mission duration given fixed battery life. Those skilled in the art will appreciate that there are other reasons beyond cost and complexity why even tunnel thrusters are problematical for the applications embodied by the instant invention.
A technique of ocean bottom seismic sensing involves downloading data from a series of Ocean Bottom Seismic nodes (OBS nodes or, simply ‘nodes’). Like the AUV, nodes are autonomous; they contain a self-contained power source and are able to record and store large amounts of seismic, electromagnetic, and similar data recorded by various sensors contained in the node. Data may be communicated with the node via multiple mechanisms; for example, wireless acoustic methods are commercially available, however bandwidth for such systems is very low, even over short distances. A node may have 64 gigabytes or more of recorded data to be recovered by the AUV. Thus, radio frequency (RF) or optical communications remain available as choices. Radio frequencies require very close antenna proximity as sea water is very poor at transmission of radio frequencies, with attenuation in excess of 40 db/meter. Optical transmission can carry very high bandwidths depending on the technology employed but transmission fidelity is adversely affected by the turbidity of the water, which would be made more problematic by AUV thrusters. Operating near a muddy ocean bottom as is found in the Gulf of Mexico, for example, thrusters tend to turn up the mud making optical transmission of data difficult or impossible. Turbidity in the deep ocean is generally not a problem except for the issues created by the vehicle itself. Whether via RF or optical transmission, and even assuming a gigabit/second or better transmission rate, large datasets are difficult to collect by a moving AUV; e.g., in motion a slow fly-by or tight circling pattern.
Although ROVs can hover and could perform the tasks at hand, ROVs require pilots, and while some ROVs can achieve speeds of torpedo-style AUVs, the speed with which ROVs can traverse a large field of widely spaced nodes (which may typically be deployed on a grid of 200-500 meters) is limited not by the ROV's speed but by the speed that the ROV's tether management system (TMS) can be towed through the water.
For these and other reasons known in the art, there exists a need to provide a conventional torpedo-styled, high-speed AUV with the ability to stop and controllably hover with stability over a target on the marine bottom. Advantageously, the ability to stop and hover the AUV would occur without forward speed and without thruster assistance, using the AUV's conventional flight surfaces for attitude, heading, and elevation control.
AUV is an autonomous underwater vehicle.
The term ‘vehicle’ is used interchangeably with AUV generally with reference to motion or flight through the water.
A ‘flight surface’ refers to one or more wings or one or more elevators and rudders, which generally occur in pairs near the rear of the AUV in close proximity to the propeller. They may be aft of the propeller or closely spaced just forward of the propeller, and may be replicated at other points further forward on the vehicle.
‘Effective operation of the flight surface’ means that the flight surface is able to perform the intended function of the flight surface; e.g., positional and directional stability and control of the AUV when there is fluid flow across the flight surface.
The term ‘propeller’ or ‘propeller mechanism’ is disclosed as the apparatus to move the AUV through the water; however, any other controllable thrust system as known in the art would be suitable. Thus use of the term ‘propeller’ is not to be interpreted to exclude other thrust systems or techniques and may be used interchangeably herein.
The term ‘about’ means the amount of the specified quantity plus/minus a fractional amount (e.g., ±10%, ±9%, ±8%, ±7%, ±6%, ±5%, ±4%, ±3%, ±2%, ±1%, etc.) thereof that a person skilled in the art would recognize as typical and reasonable for that particular quantity or measurement. Likewise, the term ‘substantially’ means as close to or similar to the specified term being modified as a person skilled in the art would recognize as typical and reasonable; for e.g., within typical manufacturing and/or assembly tolerances, as opposed to being intentionally different by design and implementation.
The most general aspects of the invention are an autonomous underwater vehicle (AUV) including a deployable anchor and a method for operating an AUV having a deployable anchor in a hover mode.
An aspect of the invention is an autonomous underwater vehicle (AUV) that includes an elongate body including a bow region and a stern region, wherein the body includes a cavity disposed between the bow region and the stern region; an anchor rode extender/retractor mechanism disposed within or on the body; an anchor rode coupled at one region thereof to the anchor rode extender/retractor mechanism; an anchor coupled to another region of the anchor rode and adapted to be disposed in the cavity in a retracted mode; and a propulsion/stabilization component. According to various exemplary, non-limiting embodiments, the AUV may include the following additional features, limitations, and/or characteristics:
An aspect of the invention is a method for controlling a submersed AUV, including the steps of providing an AUV having a deployable anchor on an anchor rode in a cavity of the AUV, and at least one of a) a combined propulsion/stabilization component and b) a propulsion component and a controllable flight surface, traveling at a given speed in a substantially horizontal, X-direction, in a marine environment; reducing the speed of the AUV while maintaining a minimal thrust sufficient for effective operation of the flight surface; deploying the AUV anchor from the cavity so that it engages the bottom of the marine environment a predetermined distance short of a known target position on the bottom of the marine environment; paying out or taking up a length of the anchor rode so as to adjust a position of the AUV in the X-direction in relation to the known target position; and further reducing the speed of the AUV in the X-direction to zero while maintaining a thrust sufficient for effective operation of the flight surface, whereby the AUV is in a hover mode proximate the target position. According to various exemplary, non-limiting embodiments, the method may include the following additional steps, features, limitations, and/or characteristics:
It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein.
a and 2b schematically illustrate the operation of the flight surfaces of a typical AUV as illustrated in
a is a schematic, side cross sectional view of an AUV, illustrating a compartment or cavity where an anchor can be stored and from where it can be deployed; in
a, b) diagrammatically illustrate the hydrodynamic forces acting on a flight control surface of the AUV, according to an illustrative aspect of the invention.
a and 2b schematically illustrate the operation of the flight surfaces of a typical AUV as illustrated in
a, b, c) are views of an AUV and regions thereof, illustrating a compartment or cavity 170 in the body of the AUV where an anchor 200 can be stored and from where it can be deployed. In
a is a bottom view of the AUV with the anchor 200 fully retracted and stowed in the cavity 170.
As illustrated in
As illustrated in
With reference to
There is a risk that the anchor 200 may break free as its shank 240 is righted or that the AUV 100 may be pulled to the bottom 10 while the anchor 200 is taken aboard the AUV during retraction. To help alleviate these or other potential problems and their consequences, high pressure water (or other fluid) jets 190 are installed in the cavity 170 that houses the anchor 200, as shown in
While several inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.
All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.
The indefinite articles “a” and “an,” as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean “at least one.”
The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.
As used herein in the specification and in the claims, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as “only one of” or “exactly one of,” or, when used in the claims, “consisting of,” will refer to the inclusion of exactly one element of a number or list of elements. In general, the term “or” as used herein shall only be interpreted as indicating exclusive alternatives (i.e. “one or the other but not both”) when preceded by terms of exclusivity, such as “either,” “one of,” “only one of,” or “exactly one of.” “Consisting essentially of,” when used in the claims, shall have its ordinary meaning as used in the field of patent law.
As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.
It should also be understood that, unless clearly indicated to the contrary, in any methods claimed herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited.
In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.
The instant application claims priority to U.S. provisional application Ser. No. 61/777,273 filed Mar. 12, 2013, the subject matter of which is incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US14/21978 | 3/7/2014 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61777273 | Mar 2013 | US |
