Abstract:
An unmanned floating platform is provided for continual surveillance at a station-keeping position at sea. The platform is equipped to dispatch an unmanned vehicle to conduct at least one of observation and rendezvous. The platform includes a hull, first and second hangers, and a liquid storage compartment. The hull has a submerged portion and a floating portion. The first hanger is equipped for stowing, deploying and retrieving a self-propelled unmanned vehicle and is substantially disposed in the floating portion. The second hanger houses equipment for electrical power and on-board functions. The liquid storage compartment supplies fuel to the on-board equipment and to the unmanned vehicle. For static stability, the compartment is disposed in the submerged portion. The platform may also include a superstructure for housing sensor equipment. The superstructure can be disposed above at least one of the first and second hangers. The second hanger may additionally house a tetherable observation aerial post.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     Pursuant to 35 U.S.C. §119, the benefit of priority from provisional application 61/005,117 with a filing date of Nov. 26, 2007, is claimed for this non-provisional application. 
    
    
     STATEMENT OF GOVERNMENT INTEREST 
     The invention described was made in the performance of official duties by one or more employees of the Department of the Navy, and thus, the invention herein may be manufactured, used or licensed by or for the Government of the United States of America for government purposes without the payment of any royalties thereon or therefor. 
    
    
     BACKGROUND 
     The invention relates generally to unmanned semi-autonomous remote basing at sea or littoral waters. In particular, this invention relates to a floating platform equipped with unmanned patrol vehicles as sentries. 
     Conventional long-term surveillance over regions having only intermittent human traffic, such as some coastal approaches, involve expensive and potentially hazardous human-occupied craft for detection and interdiction of unknown, possibly hostile vehicles. Shore-based remote sensing, such as by long-range radar systems provide limited observation capability. However, often assets are too disposed distant from the surveillance region to rendezvous with the observed vehicle before its departure. 
     SUMMARY 
     Conventional long-term observation options at sea yield disadvantages addressed by various exemplary embodiments of the present invention. In particular, dedication of expensive manned platforms with attendant risks for personnel and operational costs render such surveillance impractical. 
     Various exemplary embodiments provide an unmanned floating platform for continual surveillance at a station-keeping position at sea. The platform is equipped to dispatch an unmanned vehicle to conduct at least one of observation and rendezvous. The platform includes a hull, first and second hangers, and a liquid storage compartment. The hull has a submerged portion and a floating portion. The first hanger is equipped for stowing, deploying and retrieving a self-propelled unmanned vehicle and is substantially disposed in the floating portion. The second hanger houses equipment for electrical power and on-board functions. 
     The liquid storage compartment supplies fuel to the on-board equipment and to the unmanned vehicle. For static stability, the compartment is disposed in the submerged portion. In various exemplary embodiments, the platform may also include a superstructure for housing sensor equipment. The superstructure can be disposed above at least one of the first and second hangers. The second hanger may additionally shelter a tetherable observation aerial post. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and various other features and aspects of various exemplary embodiments will be readily understood with reference to the following detailed description taken in conjunction with the accompanying drawings, in which like or similar numbers are used throughout, and in which: 
         FIG. 1  is an isometric view of a floating platform in a first embodiment; 
         FIG. 2  is an isometric view of the floating platform in a second embodiment; and 
         FIG. 3  is block diagram view of an array of deployed platforms. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description of exemplary embodiments of the invention, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized, and logical, mechanical, and other changes may be made without departing from the spirit or scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims. 
       FIG. 1  shows in perspective a first embodiment  100  of a remote sea base platform. The platform includes a floating hull  110  shown from the stern with a lower portion submerged below the waterline  115 . This submerged portion includes a fuel storage compartment  120  (that may be subdivided by bulkheads). This submerged disposition of the compartment  120  augments static stability of the hull  110 . Above the waterline  115 , the hull  110  includes boarding access ledges  125  that can flank port and starboard. The hull  110  is shown as having a shallow draft. 
     On the starboard side, the hull  110  includes an operations roof  130  that covers a hanger  140  for stowage of one or more unmanned surface and submersible vehicles assigned for extended-range patrol. A ladder  135  provides access to the roof  130  from the starboard access  125 . The vehicles can be launched from and retrieved through vertically raised door that opens leading aft, the floor of the first hanger  140  being submerged below the waterline  115 . 
     On the port side, the hull  110  includes aerostat doors  150  that open above to the sky availing access to a second hanger  155  for power equipment and unmanned aerial vehicles, such as an instrumented lighter-than-air balloon. At the port forecastle (towards the bow), the hull  110  includes an antenna housing  160  with mast and aerials  165  for active radar sweeps. 
       FIG. 2  shows in perspective a second embodiment  200  of the remote sea base platform. The platform includes a floating hull  210  shown from the stern with a lower portion submerged below the waterline  115 . This lower portion includes a fuel storage compartment  220  (that may be subdivided by bulkheads). Above the waterline  115 , the hull  210  includes boarding ledges  225  that can flank port and starboard. 
     On the starboard side, the hull  210  includes an operations roof  230  that covers a hanger  240  for stowage of one or more unmanned surface and submersible vehicles assigned for extended-range patrol. A ladder  235  provides access to the roof  230  from the starboard ledge  225 . The vehicles can be launched through vertically raised door that opens leading aft, the floor of the hanger  240  being submerged below the waterline  115 . 
     On the port side, the hull  210  includes aerostat doors  250  that open above to the sky availing access to a compartment  255  for power equipment and unmanned aerial vehicles. The compartment  255  can provide storage space for a variety of aerial vehicles, both powered and static-hovering. At the starboard forecastle (towards the bow), the hull  210  includes an antenna housing  260  with mast and aerials  265  for active radar sweeps. 
     Artisans of ordinary skill will recognize that these described exemplary embodiments are merely descriptive and not limiting. Alternative arrangements can be designed and produced shifting components, such as interchanging port and starboard disposition of the aerostat  150 ,  250  and hanger  140 ,  240  portions of the hull  110 ,  210 . Additionally, unmanned vehicles can be intermittently augmented by small manned vehicles for stowage and deployment, such as patrol boats. 
       FIG. 3  shows a block diagram view of an operational assembly  300  of the remote sea base platform  100 . In an exemplary operational assembly  310 , the platform  100  tethers an unmanned observation balloon  320  from the aerostat  150 . The balloon  320  an aerial post from which to survey large areas continuously. The platform  100  can also deploy an unmanned hovercraft  330  as a surface vehicle, shown in isometric view in the upper right corner. 
     Several operational assemblies  310  can be deployed as an array  340  along an extended demarcation line (e.g., parallel to a shoreline), such as for a thousand nautical miles, as illustrated in this example. This line can include such assemblies  310  at disposal intervals, of which the first, second, third, . . . and tenth stations are shown. An unauthorized speedboat  350  observed by the aerostat  320  can be assigned to one or more hovercraft  330  for interception, as shown deployed by the first and third stations for further investigation, interrogation, and/or attack at minimal risk to uniformed personnel. Artisans of ordinary skill will recognize that other deployment arrangements and auxiliary craft associated with the sea base platform can be envisioned without departing from the scope of the invention. 
     To permit the remote deployment and staging of several sensor platforms for routine patrol, unmanned vehicles can be used to perform a wide variety of observation and reconnaissance missions related to military and homeland security missions. Such remote-piloted and/or autonomous vehicles can be designed for submerged operations (underwater), at the water surface (surface vehicles or hovercraft) and flying (airborne). 
     Dispatch of unmanned vehicles conventionally requires deployed proximity of armed forces ships (Navy or Coast Guard) or shore-based host installations, both of which having crews. Only limited options are conventionally available for deploying endurance-limited unmanned air vehicles and no options exist for unmanned surface vehicles on extended-duration missions without a manned host asset or base nearby. Line-of-sight (LOS) restrictions further require presence of manned host assets to supervise and communicate with the unmanned vehicles deployed to intercept an identified intruder for investigation and/or interrogation. 
     Continuous reconnaissance and patrol of coastal regions using unmanned vehicles within an operational radius without some type of unmanned basing system necessitates unacceptable costs in logistics. Exemplary embodiments provide an unmanned system of floating platforms for to satisfy this requirement. The platforms provide fuel storage and loading systems, shelter from environmental elements, communications, and protection for extended periods of time to unmanned vehicles pre-deployed in areas intended for persistent presence of these vehicles with some necessary interdiction or countermeasure interval. These platforms enable the unmanned vehicles to affordably expand the safety perimeter around fleet assets, and at the entrance to ports, among other regions to be defended. 
     This sea base platform stows and shelters the unmanned vehicles in standby mode and allows for continuous staging. For patrol or interdiction, the unmanned vehicles can be refueled and deployed absent manned platforms in the vicinity. Optionally, the platform can include tools for standard maintenance and minor repair. Additionally, the hangers can support unmanned systems with a wide variety of sensors and automated data fusion systems for watch at standoff distances from harbors or manned craft. These sensors facilitate persistent surveillance with minimal resources. Optimally queued, the unmanned vehicles enable low-risk interception and low-cost countermeasure capabilities, within minimal autonomous reaction intervals. The platform can be designed to include minimal facilities for human visitation for inspection, modification or other related purposes. 
     This remote floating station as described above provides a reconfigurable, modular, autonomous and remotely-operated multi-purpose barge or buoy that can preferably be anchored for station-keeping to avoid drift. Alternatively, the station can be free-floating to facilitate redeployment. Such a floating platform can be configured for either sea (blue water) or river (brown water) disposition to provide an operating home base, logistics host, and refuge for wide ranging sensors and primarily unmanned systems. 
     The sea base platform may be towed out by a sea-worthy tugboat or other appropriate vessel and moored in position for deep sea missions. A littoral base platform may be towed by a smaller tugboat for deployment at the mouth of a river, harbor, or port entrance for either defense or blockade. From the anchored position, one or more of the unmanned vehicles can be dispatched for target reconnaissance and/or interception of unknown or potentially hostile craft. The dispatch orders may optionally be automatically conditioned, or alternatively arranged to transmit an alert to an authorized designate (such as a combat vessel or shore facility). 
     For proximate missions to shore, such as port defense or river mouth surveillance, radio and/or wire-link communications can be included to enable human-intervention before unmanned vehicle dispatch. For far-field missions at remote locations, satellite communications can be used for exchanging routine maintenance and status update information. The onboard radar system provides self-defense surveillance capability. To extend either communications distances or the area of coverage, the onboard aerostat can be launched to perform either function. 
     Sensor payloads can be selected based on the mission of the sea base platform and operational environment at the deployment location. Sensors can include but are not limited to received signals or measurements from radar, biological, chemical, radiation, acoustic, optical, infrared and hydro-acoustic systems. Specific sensor packages may include anti-submarine warfare suites such as dipping-sonar and acoustic arrays that can be operated autonomously by the sea base platform. Alternate sensor packages may include devices for automated mine clearing along a shipping lane. 
     Automated data fusion gear, hardware and software can be housed and operated on the platform to accumulate and fuse raw data streams into various levels of knowledge. These data can be transmitted to a host network for further analysis. A sensor fusion example would be automated target recognition of sea lane traffic and queuing of high radiation levels emanating from a vessel within range. Reconfiguration, reprogramming, software uploads, data downloads at any level and remote operation of the sea base platforms can be conducted through the data links using secure-communication methods. 
     Electrical power can be provided to the unmanned sea base platform by any combination of existing or future fuel and/or energy harvesting schemes. These can include solar, wind, ocean-current, geothermal or other conversion methods that can charge batteries in house-keeping mode. Such systems can be supplemented or substituted by on-board generators depending on the power requirements for selected mission scenarios. For example, high levels of power may be necessary for radar transmission and communications, or to operate rotary wenches and similar devices on-board the platform. 
     The unmanned sea base platform can be provisioned on location by sea. Periodic maintenance and refueling can be performed by crews who board the platform and execute duties such as operational verification of mooring lights, electronic systems, control panels and moorings. In turn the unmanned sea base platform supports native onboard systems and sensors, capture, launch, and refuel and provide power and communications for the unmanned vehicles. 
     The sea base platform also provides an unmanned remote logistics base for other emerging unmanned systems. This may include providing a refueling base for unmanned surface vehicles that are not indigenous to the platform, but share a common integrated refueling scheme. Alternatively, this may include service for a non-indigenous aerial vehicle in extended operations from shore beyond its round-trip endurance, such as provide safe haven for manned or unmanned aircraft that experience technical problems or hostile attack and seek refuge. The platform can be reconfigured to support any future system that requires remote pre-deployed supporting assets and logistic needs. 
     While certain features of the embodiments of the invention have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the embodiments.