Abstract:
A combination stabilizer system and cylindrical-shaped undersea package improves validity of data collected from ambient sea by orienting the package in an upright attitude and eliminating motion or rocking due to wave action and/or sea currents. An outrigger base assembly has a flat base surface to rest on the sea floor and is provided with upper surfaces having semi-circular cross-sectional configurations to contiguously fit adjacent to round outer contours of an undersea package. The outrigger base assembly also has laterally extending outrigger portions extending the flat base surface for increased stability. First and second case clamps have curved surfaces with semi-circular cross-sectional configurations that extend above the outrigger base assembly. The first and second clamps clamp the curved surfaces and upper surfaces onto the round contours and secure the undersea package in an upright orientation.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is a continuation of U.S. patent application Ser. No. 10/042,842, filed Jan. 11, 2002, now abandoned, entitled “Attachable stabilization Bracket for Versatile Mine System” and assigned to the Government of the United States of America. 

   STATEMENT OF GOVERNMENT INTEREST 
   The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor. 

   BACKGROUND OF THE INVENTION 
   This invention relates to a stabilizer for a mine emulation system deployed underwater. More particularly, the stabilizer bracket of this invention can be quickly mounted on a cylindrically-shaped underwater mine emulation system to stabilize and orient it in a predetermined fixed attitude to improve the quality of gathered data. 
   Acoustic/seismic, magnetic, and pressure data is collected underwater by numbers of different sensors that usually are contained in one or more housings. The housings are commonly made in cylindrical shapes to protect the sensors and interconnected processing modules from the effects of the ambient water during the long periods of time that sometimes must be spent to collect meaningful amounts of data. The housings additionally must be stable and not move since random or uncompensated motion can compromise the quality, or even the validity of the gathered data. 
   One technique currently used to stabilize the cylindrical-shaped housings is to put a dense, heavy weight on one side of the housing. This side that is weighted would nominally be considered the underside since the force of gravity would bring it to rest on the ocean bottom. However, because the cylindrical shape defines a curved outer surface, the housing is still prone to move, or rock due to wave action and/or sea currents. It has been noted that noise was present in the magnetic data, and this noise was created by sea currents/wave action rocking the housing about its cylindrical, or longitudinal axis. 
   Thus, in accordance with this inventive concept, a need has been recognized in the state of the art for an effective means that can be easily connected to a cylindrical-shaped housing to stabilize and orient it on the ocean floor. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   An object of the invention is to stabilize and orient a cylindrical-shaped housing for sensors on the ocean floor. 
   Another object is to provide a stabilization structure for the cylindrical-shaped mine emulation system to eliminate movement caused by wave action and/or sea currents. 
   Another object is to provide stabilization structure that is easily attached and removed by simple tools. 
   Another object is to provide a stabilization structure having an outrigger design to create a flat bottom for a cylindrical instrumentation housing to enhance its ability to remain stable in high sea states and in strong currents. 
   Another object is to provide a cost-effective stabilizing structure for a cylindrical housing made from materials resistant to the harsh marine environment. 
   These and other objects of the invention will become more readily apparent from the ensuing specification when taken in conjunction with the appended claims. 
   Accordingly, the invention stabilizes a cylindrical-shaped undersea package on the sea floor. An outrigger base assembly has a flat base surface to rest on the sea floor and an upper surface having a semi-circular cross-sectional configuration to contiguously fit adjacent to round outer contours of the undersea package. The outrigger base assembly has outrigger portions to laterally extend the flat base surface. First and second case clamps have curved surfaces with semi-circular cross-sectional configurations to extend above the outrigger base assembly. The first and second clamps clamp the curved surfaces onto the round contours of the undersea package and the upper surface of the outrigger base assembly onto the round contours of the undersea package. The first and second case clamps secure the undersea package in an upright orientation and resist tendencies for motion by waves and/or currents. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic representation of the stabilizer assembly of the invention installed on an undersea instrumentation package, for example a versatile exercise mine system (VEMS) on the sea floor. 
       FIG. 2  is an isometric, schematic representation of the stabilizer assembly removed from the VEMS. 
       FIG. 3  is a partially exploded view taken along line  3 — 3  in  FIG. 1  showing details of the stabilizer assembly. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIG. 1 , stabilizer system  10  of the invention is installed on an undersea instrumentation package, for example a versatile exercise mine system (VEMS)  30 . VEMS  30  is shown on the bottom, or sea floor  40  of a body of water  50  after it has been dropped or otherwise deployed such as by cable (not shown) from a surface vessel or aircraft. On sea floor  40  VEMS  30  will power-up and collect acoustic/seismic, magnetic, and pressure data and emulate various real mines. 
   VEMS  30  can be an exercise mine, for example the elongate, cylindrical-shaped MARK  74  VEMS of the U.S. Navy, that is designed to be placed into the ocean and rest on the floor, where it will power up and collect acoustic/seismic, magnetic, and pressure data and emulate various real mines. By emulating the mines, VEMS  30  will retrieve data from its sensors and, via software, analyze the data to determine if the mine VEMS  30  is emulating would have actuated from the signals received. 
   Heretofore, VEMS  30  has been internally weighted so that the force of gravity would cause one rounded contour  31  of its rounded, cylindrically-shaped housing  32  to come to rest on bottom  40  and tend to stay in this orientation. However, practical experience indicates that VEMS  30  is sensitive to wave action and/or sea currents that push against its sides and cause it to rock back and forth on rounded contour  31 . This rocking motion affects triaxial magnetic sensors in VEMS  30 , since they then move relative to the earth&#39;s background magnetic field. To these sensors, the rocking motion can appear as fluctuating background noise levels (fluctuations occur at frequencies associated with the frequencies of the back and forth motions of VEMS  30 ). This background noise level can be mistaken as emulations of a mine run by the VEMS  30  as a potential target, or the background noise level could mask a low level target so that VEMS  30  does not recognize it as a target. By stabilizing VEMS  30  with stabilization system  10 , the magnetic sensors will not move, and consequently the earth&#39;s background magnetic field should appear to the sensors to be stable. 
   Referring also to  FIGS. 2 and 3 , in accordance with this invention stabilization system  10  secures an outrigger base assembly  15  to VEMS  30  by a pair of stabilizing case clamps  20  and  25  wrapped around and engaging VEMS  30 . Stabilizing case clamps  20  and  25  extend parallel with respect to one another and are longitudinally separated from each other along VEMS  30 . Typically, stabilization system  10  is mounted on VEMS  30  in an assembly area prior to deployment by placing a flat base surface  15   a  of outrigger base assembly  15  on a flat surface  41  beneath VEMS  30  that has been raised by an overhead crane (not shown). The overhead crane lowers VEMS  30  onto outrigger base assembly  15 , and after proper orientation of VEMS  30  has been verified, the two stabilizing case clamps  20  and  25  are placed across the top of VEMS  30 . Case clamps  20  and  25  are secured to outrigger base assembly  15  by bolts  22  and  27 , respectively.  FIG. 3  shows bolts  27  extending through holes  28  in case clamp  25 , to engage mating threaded bores  29  in assembly  15 . Although not shown, it is understood that like bolts  27 , bolts  22  also extend through similar holes in clamp  20  to engage similar threaded bores in assembly  15 . Tightening bolts  22  and  27  in their respective bores causes case clamps  20  and  25  and outrigger base assembly  15  to securely grip, or clamp onto and engage VEMS  30 . Installation of stabilizer system  10  on VEMS  30  is now complete. Disassembly is the reverse procedure of this process of assembly. 
   Outrigger base assembly  15  has upper surfaces  16  being essentially semi-circular cross-sectional shaped to fit contiguously adjacent to the essentially circular cross-sectional shape of the outer contours  32   a  of VEMS  30  and has laterally extending outrigger portions  17  that extend flat base surface  15   a . Stabilizing case clamps  20  and  25  extend above outrigger base assembly  15  between outrigger portions  17  to clamp VEMS  30  to outrigger base assembly  15  and securely orient VEMS  30  in an upright, or other fixed orientation with respect to sea floor  40 . Stabilizing case clamps  20  and  25  do this when bolts  22  and  27  are tightened to cause a firm gripping engagement on outer contours  32   a  of VEMS  30  along curved surfaces  21  and  26  that each has an essentially semi-circular cross-sectional shape. Thus, the orientation of VEMS  30  with respect to sea floor  40  (or the relative angle between outrigger base assembly  15  and VEMS  30  or another external reference) is fixed and does not change throughout the period of an operational deployment while data is being gathered. 
   The design and construction of the stabilizer system  10  are uncomplicated to lower construction costs. Outrigger base assembly  15  and stabilizer base clamps  20  and  25  can be suitably constructed of strong aluminum, stainless steel, or other materials that can handle the expected loads induced by water entry and coming to rest against bottom  40 , and bear the weight of VEMS  30 . The materials are chosen to be non-corrosive, or corrosion resistant so as not to be affected by salt water. Stabilizer system  10  is not intended to be a lifting mechanism or hard point for deployment of VEMS  30 . Other hard points and/or connecting structure (not shown) associated with VEMS  30  are used for deployment to sea floor  40 . Outrigger base assembly  15  is built to be sufficiently strong to support the weight of VEMS  30  on sea floor  40  with the attached stabilizer system  10 . 
     FIG. 3  shows threaded bolts  27 , flat washers  27   a , and lock washers  27   b  as attachment hardware for stabilizing case clamp  25 . Although flat washers, lock washers, holes, and threaded bores associated with bolts  22  are not shown it is understood that stabilizing case clamp  20  also can be connected to outrigger base assembly  15  in this manner. Other mechanisms to connect stabilizing case clamps  20  and  25  to the outrigger base assembly  15  might be chosen, such as hinges, over-center latches, captive pins, etc. Stabilizing case clamps  20  and  25  and/or outrigger base assembly  15  could also utilize rubber pads, or other resiliently engaging means  21   a ,  26   a , and  16   a  to prevent damage to VEMS  30  and its protective coating, and to provide additional gripping frictional force. Stabilizing case clamps  20  and  25  can have a variety of cross-sectional shapes, such as square, triangular, circular, elliptical, for examples. Outrigger base assembly  15  can be made from different stock including square tube, round tube, I-beams, C-beams, or other cross-sectional shapes. An exemplary VEMS  30  having a diameter of 21.0 inches can have outrigger base assembly  15  and stabilizing case clamps  20  and  25  shaped to have an inner radius of 10.5 inches to accommodate the exemplary VEMS  30 . The length and width of outrigger base assembly  15  should be the maximum practical length so as not to interfere with detachable hardware or sensors or access ports on the exemplary VEMS  30 . Therefore, outrigger base assembly  15  of stabilizer system  10  provides a flat bottom for VEMS  30  and greatly enhances the ability of VEMS  30  to remain stable even in high sea states or locations where strong sea currents are prevalent. 
   Having the teachings of this invention in mind, different applications, modifications and alternate embodiments of this invention may be adapted. Stabilizer system  10  can be made in larger or smaller sizes and in a multitude of different shapes, and could be made from a wide variety of materials. In other words, the design and construction of stabilizer system  10  allows for accommodation of different underwater systems other than the cylindrical shape of VEMS  30  by substituting differently dimensioned and shaped components. Stabilizer system  10  of the invention can easily be removed and reinstalled if necessary, and simple tools are all that are required to perform this operation. Optionally, the reliable, uncomplicated and cost effective design of stabilizer system  10  can permit its non-recyclable use to stabilize undersea packages. Other modifications could be made as will be apparent to one skilled in the art to which this invention pertains. 
   The disclosed components and their arrangements as disclosed herein all contribute to the novel features of this invention. Stabilizer system  10  of this invention is an effective improvement that can be readily connected or disconnected to enable its addition or removal from VEMS  30  without undue effort. Therefore, stabilizer system  10 , as disclosed herein is not to be construed as limiting, but rather, is intended to be demonstrative of this inventive concept. 
   It should be readily understood that many modifications and variations of the present invention are possible within the purview of the claimed invention. It is to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.