Abstract:
A passively-actuated lanyard clamp is disclosed that provides an improved ability to deploy a terminal weight or anchor in a body of water without some of the disadvantages for doing so in the prior art. An embodiment of the present invention comprises a mechanically-bistable latch for clamping a lanyard, wherein the latch is passively-actuated by a force that develops as a result of the terminal weight reaching the bottom of the body of water.

Description:
STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH 
     This invention was made with Government support under N00014-02-C-0211 awarded by Office of Naval Research. The Government has certain rights in the invention. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to winding devices in general, and, more particularly, to winding device clamps. 
     BACKGROUND OF THE INVENTION 
     Navigation aids, channel markers, water-based mines, and the like, are floating objects (on the water surface or below) that are typically anchored to the bottom of a body of water in order to hold them at a fixed coordinate. Typically, such an object is attached, by means of a lanyard, to a submerged weight that resides on the bottom of the body of water. The lanyard provides a positive connection between the floating objects and the bottom of a body of water. For the purposes of this specification, including the appended claims, the term “lanyard” means a cord, a chain, a rope, a cable, or the like, which can be used to connect one object to another. 
     In addition, communication cables, and the like, are often deployed along the bottom of a body of water, such as an ocean, and require positive connection to the bottom at various points. 
     There are several methods to deploy a floating object or communications cable. A first deployment method requires that a weight is attached to a lanyard on board a ship floating on the surface of the water. The weight, with attached lanyard, is then allowed to fall through the water until it reaches the bottom. As the weight falls, the lanyard pays out from a capstan located on board the ship. During lanyard payout, an axial tension develops in the lanyard. The weight&#39;s arrival at the bottom is indicated by a decrease in this axial tension. Once the weight is determined to be on the bottom, the lanyard is clamped to preclude further lanyard payout. The floating object is then attached to the lanyard, the lanyard is cut above this attachment point, and the floating object is jettisoned overboard. 
     There are several drawbacks to this first method, however. First, it is a time-consuming and labor-intensive process. Second, fluctuation of underwater currents can lead to false indications that the weight has reached the bottom. Third, the process can be dangerous due to the forces that can develop when a lanyard under high axial tension is cut. 
     A second method for deploying a floating object utilizes a lanyard clamp that is submerged with the weight. A control line is attached to this lanyard clamp so that it can be actively actuated once it is determined that the weight has reached the bottom. In addition to having many of the same drawbacks of the first method, this method also adds cost and complexity due to the additional lanyard and lanyard handling apparatus. In addition, the added infrastructure exacerbates deck crowding on the ship, which exposes on-board personnel to additional safety hazard. Finally, fluctuation of underwater currents can cause snarling of the multiple lanyards during deployment. 
     There exists a need, therefore, for a weight deployment system that avoids or mitigates some or all of these problems. 
     SUMMARY OF THE INVENTION 
     The present invention provides a system for deploying a terminal weight or anchor in a body of water that avoids some of the costs and disadvantages for doing so in the prior art. In particular, the illustrative embodiment of the present invention uses a weight having a passively-actuated latch to clamp a lanyard, thereby fixing the attachment point of the lanyard to the weight. 
     In the prior art, the length of a lanyard that connects a sunken weight to an object above, such as a float, buoy, ship, and the like, is fixed by actively clamping the lanyard once it is determined it has sunk completely. This requires maintaining contact with the weight as it sinks, sensing when the weight has reached the bottom of the body of water, and actively engaging a clamping mechanism to connect the sunken weight to the object. 
     In contrast to the prior art, the present invention provides a weight having an integrated latch for clamping a lanyard, wherein the latch is passively-actuated by a force generated in response to the arrival of the weight at the bottom. As a result, the object and the attached weight can be deployed without active participation of an operator after they are placed in the water. 
     In some embodiments, the system comprises a float and a weight having an integral lanyard spool, rotator, and latch. The weight and float are connected via a lanyard that is spooled onto the lanyard spool, and which can provide a positive connection between the float and the bottom of the body of water, such as an ocean bottom. During deployment of the float, the weight is allowed to payout lanyard while it falls through the body of water until the weight rests on the bottom. Once on the bottom, the weight rotates due to the rotator and a bending moment is generated in the lanyard. The bending moment causes the actuation of the latch, which clamps onto the lanyard and prevents further lanyard payout. 
     The illustrative embodiment comprises: a weight for anchoring a lanyard; and a guide for guiding the lanyard during deployment of the weight, wherein the guide comprises a latch for clamping the lanyard when the weight is fully-deployed, and wherein the latch is passively-actuated when the weight is fully-deployed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts details of a ship deploying a float in accordance with the prior art. 
         FIG. 2  depicts a schematic diagram of details of a float deployment system in accordance with an illustrative embodiment of the present invention. 
         FIG. 3A  depicts details of float deployment system  200 , prior to deployment, in accordance with the illustrative embodiment of the present invention. 
         FIG. 3B  depicts details of float deployment system  200 , after deployment, in accordance with the illustrative embodiment of the present invention. 
         FIG. 4  depicts details of weight  204 , prior to deployment, in accordance with the illustrative embodiment of the invention. 
         FIG. 5  depicts details of weight  204 , after deployment, in accordance with the illustrative embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  depicts details of a ship deploying a float in accordance with the prior art. Float-deployment system  100  comprises weight  104 , lanyard  106 , capstan  108 , bearing  110 , float  112 , and line  114 . 
     Ship  102  carries float-deployment system  100  to a desired float deployment site. During float deployment, weight  104 , attached to lanyard  106 , is allowed to fall through the water toward the ocean bottom. Capstan  108  controls the speed of the weight&#39;s descent by maintaining an axial tension on lanyard  106  as necessary. When weight  104  reaches the ocean bottom, capstan  108  senses a decrease in the axial tension in lanyard  106  and halts its payout. 
     Once weight  104  reaches the ocean floor, float  112  is attached to lanyard  106  via line  114 . Finally, lanyard  106  detached above its junction to line  114  and float  112  is jettisoned overboard. 
       FIG. 2  depicts a schematic diagram of details of a float deployment system in accordance with an illustrative embodiment of the present invention. Float system  200  comprises float  202 , weight  204 , and lanyard  206 . 
     Float  202  is a buoyant hollow sphere, designed to float at or near the surface of a body of water, such as an ocean. In some alternative embodiments, float  202  is a non-spherical buoyant device or platform. In some alternative embodiments, float  202  is a buoyant hollow sphere or other buoyant device or platform designed to float below the surface of the water to anchor a submerged device, such as an explosive mine, acoustic source, sensor, and the like. It will be clear to those skilled in the art, after reading this specification, how to make and use float  202 . 
     Weight  204  is a non-buoyant object made of non-corrosive material. Weight  204  is designed to sink to the ocean bottom and remain substantially fixed in place once in contact with the ocean floor. In some alternative embodiments, weight  204  is made of a corrosive material, but whose rate of corrosion is slow enough to ensure sufficient lifetime of float system  200 . 
     Lanyard  206  is a metal lanyard of sufficient strength as to provide a positive connection between weight  204  and float  202 . In some alternative embodiments, lanyard  206  comprises non-metallic materials. It will be clear to those skilled in the art, after reading this specification, how to make and use lanyard  206 . 
     Weight  204  comprises lanyard spool  208 , rotator  210 , and latch  212 . 
     Lanyard spool  208  is a spool for carrying and paying out lanyard  206 . Lanyard spool is rotatable with respect to weight  204 . The rotatable nature of lanyard spool  208  enables lanyard  206  to be paid out during deployment of float  202  without a need for weight  204  to rotate. In some alternative embodiments, lanyard spool is not rotatable with respect to weight  204 . It will be clear to those skilled in the art, after reading this specification, how to make and use lanyard spool  208 . 
     Rotator  210  is a curved feature located on the bottom end of weight  204 . Rotator  210  causes a rotation of weight  204  upon contact with the ocean bottom. This rotation causes a bending moment to arise in lanyard  206 , as will be discussed below and with respect to  FIG. 5 . 
     Latch  212  is a passively-actuated latch for controlling the payout of lanyard  206  from lanyard spool  208 . Latch  212  is a mechanically-bistable latch that has two stable mechanical positions. In its first position, latch  212  guides lanyard  206  and allows its payout. In its second position, latch  212  clamps lanyard  206  and disallows its payout. 
     As weight  204  sinks through the water, but prior to it reaching the ocean bottom, it creates an axial tension in lanyard  206 . This axial tension serves to keep latch  212  its first mechanically-stable position. Once weight  204  reaches the ocean bottom, however, the axial tension is reduced or eliminated. In addition, rotator  210  causes weight  204  to rotate after contacting the ocean floor. This rotation induces a side-load (i.e., a bending moment) in lanyard  206 , which causes latch  212  to actuate. As a result, latch  212  actuates passively from its first mechanically-stable position to its second mechanically-stable position. Latch  212  is described in more detail below and with respect to  FIGS. 4 and 5 . 
       FIG. 3A  depicts details of float deployment system  200 , prior to deployment, in accordance with the illustrative embodiment of the present invention. Weight  204  is depicted hanging from float  202 , which is floating on the ocean surface. Lanyard spool  208  holds nearly the entire length of lanyard  206  at the beginning of float deployment. A portion of lanyard  206  is threaded through latch  212  and fastened to float  202  to provide interconnection of float  202  and weight  204 . 
       FIG. 3B  depicts details of float deployment system  200 , after deployment, in accordance with the illustrative embodiment of the present invention. Weight  204  is depicted after it has sunk to the ocean bottom and rotated into its final rest position. Weight  204  rests at an angle, θ, which is dependent upon the relation between rotator  210  and the local slope of the ocean floor on which weight  204  rests. The bending moment induced in lanyard  206  is a function of θ and the weight of weight  204 . Weight  204 , rotator  210 , and latch  212  are designed such that the bending moment is sufficient to passively-actuate latch  212 . Upon actuation of latch  212 , the length of lanyard  206  between weight  204  and float  202  is fixed and a positive connection between float  202  and the ocean bottom is established. 
     Although the illustrative embodiment depicts rotator  210  as a rounded element, it will be to those skilled in the art, after reading this specification, how to make and use alternative embodiments of the present invention wherein rotator  210  comprises any shape sufficient to induce a suitable rotation of weight  204 . 
       FIG. 4  depicts details of weight  204 , prior to deployment, in accordance with the illustrative embodiment of the invention. Weight  204  comprises housing  402 , first guide  404 , second guide  406 , spring  408 , and bearings  410 . 
     Housing  402  is a corrosive-resistant metallic canister that houses lanyard  206  on lanyard spool  208 , and latch  212 . Housing  402  also comprises a solid region  418 , which both provides mass and is shaped to function as rotator  210 . 
     Lanyard spool  208  is a cylindrical spool for holding lanyard  206  in well-known fashion. Lanyard spool  208  is attached to housing  402  via bearings (not shown for clarity) that enable lanyard spool  208  to rotate with respect to housing  402 . Rotation of lanyard spool  208  occurs as lanyard  206  unwinds and pays out during deployment of weight  204 . Lanyard spool  208  also incorporates traveler  416 , which travels along lanyard spool  208  to guide the winding and unwinding of lanyard  206  on lanyard spool  208 . Traveler  416  also keeps the windings of lanyard  206  wound in orderly fashion on lanyard spool  208 , regardless of the orientation of weight  204 . 
     Although the illustrative embodiment comprises a lanyard spool that includes a traveler, it will be clear to those skilled in the art, after reading this specification, how to make and use alternative embodiments of the present invention wherein lanyard spool  208  does not incorporate a traveler. In some alternative embodiments, cable spool  208  comprises a flange having a rounded edge for guiding cable  206  during cable payout. 
     First guide  404 , second guide  406 , and spring  408  together compose latch  212 .  FIG. 4  depicts latch  212  in its first mechanically-stable position, wherein lanyard  206  is allowed to pass through first guide  404  and second guide  406  during lanyard payout. When latch  212  is in its first mechanically-stable position, first guide  404  and second guide  406  are aligned such that their respective through-holes are substantially coaxial and thereby form a substantially continuous single sleeve for guiding lanyard  206 . 
     First guide  404  is a cylindrical metallic tube with a protuberance at one end. The outer surface of the protuberance has serrations to enhance its surface roughness and thereby improve its clamping capability. In some alternative embodiments, the surface of the protuberance is not structured. In some alternative embodiments, the surface of the protuberance is structured without serrations. First guide  404  forms a first sleeve for guiding lanyard  206  by virtue of through-hole  412 . The diameter of through-hole  412  is just slightly larger than the diameter of lanyard  206 . In some alternative embodiments, through-hole  412  comprises a material or sleeve of material, such as Teflon, plastic, ceramic, and the like, to facilitate the passage of cable  206 . 
     Second guide  406  is formed as an integral part of housing  402 . Like first guide  404 , second guide  406  comprises a protuberance having serrations to enhance its surface roughness. Second guide  406  forms a second sleeve for guiding lanyard  206  by virtue of through-hole  414 . The diameter of through-hole  414  is just slightly larger than the diameter of lanyard  206 . 
     In some alternative embodiments of the present invention, at least one of first guide  404  and second guide  406  comprise a material other than metal. Suitable materials for use in first guide  404  and second guide  406  include, without limitation, metals, graphite, plastics, ceramics, Kevlar, and polycarbonate materials. In some alternative embodiments, through-hole  414  comprises a material or sleeve of material, such as Teflon, plastic, ceramic, and the like, to facilitate the passage of cable  206 . 
     Spring  408  is a metallic spring for actuating latch  212 . When latch  212  is actuated, it moves to its second mechanically-stable position, as depicted below and with respect to  FIG. 5 . Spring  408  provides sufficient force to actuate latch  212  and hold first guide  404  in its actuated position, such that the actuation of latch  212  is irreversible. For the purposes of this specification, including the appended claims, the term “irreversible” means that latch  212  can not be returned to its first mechanically-stable position without directly resetting latch  212 . In order to reset latch  212 , some disassembly of weight  204  is typically required. 
     Bearings  410  are roller bearings for guiding lanyard  206  from traveler  416  to second guide  406 . In some alternative embodiments of the present invention, bearings  410  are not required. Although the illustrative embodiment comprises bearings  410  that are roller bearings, it will be clear to those skilled in the art, after reading this specification, how to make and use alternative embodiments of the present invention wherein bearings  410  comprise bearings of other types. It will be clear to those skilled in the art how to make and use bearings  410 . 
       FIG. 5  depicts details of weight  204 , after deployment, in accordance with the illustrative embodiment of the invention. Latch  212  is depicted as having been actuated and is now in its second mechanically-stable position. 
     Latch  212  is passively actuated by the generation of a side load in lanyard  206 . The side load arises due to a rotation of weight  204  as it hits the ocean bottom. Upon reaching the ocean bottom, the axial tension on lanyard  206  decreases and rotator  210  rotates weight  204 . As weight  204  rotates, a laterally-directed force arises on first guide  404 . This force causes a misalignment of the protuberances of first guide  404  and second guide  406 . As a result, spring  408  is allowed to decompress and drive first guide  404  into a wedged position against second guide  406  and the interior wall of housing  402 . 
     Since lanyard  206  is threaded through both first guide  404  and second guide  406 , it becomes clamped between these guides as first guide moves into its latched position. Thus, further payout of lanyard  206  is halted and a positive connection is established between float  202  and weight  204 , which now rests on the ocean bottom. 
     It is to be understood that the above-described embodiments are merely illustrative of the present invention and that many variations of the above-described embodiments can be devised by those skilled in the art without departing from the scope of the invention. For example, in this Specification, numerous specific details are provided in order to provide a thorough description and understanding of the illustrative embodiments of the present invention. Those skilled in the art will recognize, however, that the invention can be practiced without one or more of those details, or with other methods, materials, components, etc. 
     Furthermore, in some instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the illustrative embodiments. It is understood that the various embodiments shown in the Figures are illustrative, and are not necessarily drawn to scale. Reference throughout the specification to “one embodiment” or “an embodiment” or “some embodiments” means that a particular feature, structure, material, or characteristic described in connection with the embodiment(s) is included in at least one embodiment of the present invention, but not necessarily all embodiments. Consequently, the appearances of the phrase “in one embodiment,” “in an embodiment,” or “in some embodiments” in various places throughout the Specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments. It is therefore intended that such variations be included within the scope of the following claims and their equivalents.