Patent Publication Number: US-6907326-B1

Title: Autonomous surf zone line charge deployment system

Description:
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 clearing mines and other obstacles from an area. More particularly, this invention is to an autonomous system deploying at least one line charge to clear an approach lane. 
   Access to regions held by hostile forces could require an amphibious assault through an approach lane that extends from the sea and across a beach. Prior to the amphibious assault, mines and obstacles should be cleared from the approach lane so that landing craft can safely make the assault. A more challenging part of this task is the clearance of the surf zone portion of the lane (from 10 to 0 feet of water depth) because of highly dynamic and unforgiving wave action, currents, etc. 
   Divers in demolition/assault teams have performed this task but they must bring in a substantial amount of explosive charges. By itself carrying in this load is formidable, however, the significant hazards in the dynamic surf zone additionally must be dealt with. During deployment, the demolition teams and the explosive charges often are in exposed positions. This could attract unwanted attention and draw concentrated defensive fires from entrenched, determined defenders. The extreme peril created during manned clearing operations usually means that casualties may have to be sustained among the members of these highly trained teams, and even at this cost, the success of such missions may still be in doubt. 
   Rocket deployed line charges have been used with some success. But, they usually are launched from exposed positions adjacent to a target area, and neutralization of all mines and obstacles in an area is not assured since the rocket deployed line charges do not always accurately and uniformly cover a designated area satisfactorily. 
   Thus, in accordance with this inventive concept, a need has been recognized in the state of the art for an autonomous method and means for clearing mines and other obstacles from an approach lane that reduces the hazards to personnel yet assures successful completion of the mission. 
   OBJECT AND SUMMARY OF THE INVENTION 
   An object of the invention is to provide an autonomous system to deploy at least one explosive line charge to neutralize mines and obstacles in an approach lane. 
   Another object of the invention is to provide an autonomous system to deploy at least one explosive line charge to neutralize mines and obstacles in an approach lane extending through the surf zone and partially onto the beach. 
   Another object of the invention is to provide an autonomous system to neutralize mines and obstacles in an approach lane that reduces the exposure of personnel to danger. 
   Another object of the invention is to provide an autonomous system to neutralize mines and obstacles in an approach lane to reduce the exposure of personnel to danger and using at least one line charge that can be partially deployed, further deployed, and detonated in a spacedapart sequence. 
   Another object of the invention is to provide an autonomous system to neutralize mines and obstacles in an approach lane having a buoyancy means on line charges to aid deployment through the surf zone and partially onto the beach. 
   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 present invention is to an autonomous system and method for deployment of a line charge extending through a surf zone and/or partially across a beach to clear mines and obstacles from an approach lane. A ship is distantly located from an approach lane spanning a surf zone and a beach portion, and the ship has software of an operator control station in an onboard computer. At least one system delivery vehicle having a storage bay and propulsion means transits from the ship to the approach lane in response to first instructions from the operator control station. A line charge is disposed in each bay and has one end coupled to the system delivery vehicle. A line charge delivery vehicle in each bay is connected to another end of the line charge to pull the line charge from the bay and emplace it in a straight path in the approach lane in response to second instructions from the operator control system. Explosives in all line charges are detonated to clear the approach lane. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic side view, partially in cross section of constituents of the autonomous system of the invention for clearing mines and obstacles in an approach lane extending through the surf zone and partially across a beach. 
       FIG. 2  is a schematic showing the placement of transducers associated with an acoustic long baseline (LBL) navigation system. 
       FIG. 3  is a cross-sectional schematic view showing the placement of transducers associated with the acoustic LBL navigational system taken generally along line  3 — 3  in FIG.  2 . 
       FIG. 4  shows deployment of system delivery vehicles at base positions along the seaward edge of the approach lane. 
       FIG. 5  shows line charge delivery vehicles after pulling line charges from system delivery vehicles and emplacing them in parallel paths in the approach lane. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , an autonomous line charge deployment system  10  of the invention has the capability to be deployed from over-the-horizon to where an amphibious assault can be made. The goal of most amphibious assaults is to gain a beachhead on a landmass and go through what is called an approach lane  20 . Approach lane  20  can include a surf zone  22  under water  23  (from ten to zero feet of water depth), shoreline  24 , and beach portion  25  of sand, sediment, dirt, etc. Conducting a successful amphibious assault usually requires clearance of obstacles  26  and mines  28  from both surf zone  22  and beach portion  25  of approach lane  20  to allow safe passage of personnel, materials, and vehicles. 
   Autonomous deployment system  10  has an over-the-horizon support ship  30 , at least one system delivery vehicle (SYSDV)  40 , at least one line charge  50 , and at least one line charge delivery vehicle (LCDV)  60 . Autonomous deployment system  10  of the invention allows selective, controlled clearing of an area, or approach lane  20  with at least one line charge  50 . Only one SYSDV  40 , line charge  50 , and LCDV  60  are shown in  FIG. 1 , it being understood that many of these combinations, to be described, may be needed to clear a wider approach lane  20 . Autonomous deployment system  10  reduces casualties during placement and detonation of line charge  50  by keeping personnel out of a possibly hotly contested beach region and instead, using their talents at a safer remote location on ship  30 , possibly over-the-horizon to plan and execute clearing operations. 
   Support ship  30  is the staging area of system  10  and has a software control package, or operator control station (OCS)  35  running on laptop computer  36 . OCS  35  is used to plan and execute line deployment missions and allows an operator at a distant command station or at ship  30  to analyze the information of latitudes/longitudes representing the area to be cleared and monitor system status and progress. In accordance with software package of OCS  35  laptop computer  36  can display maps of the area indicating the lane to be cleared in order to confirm the information provided by the operator. Software of OCS  35  on laptop  36  tells the operator the number of SYSDV  40 s and LCDV  60 s pulling line charges  50  that must be deployed in order to clear the area of approach lane  20 . 
   Next, the software of OCS  35  will initialize each SYSDV  40  and LCDV  60  and provide first instructions  46 , or software on a first single board computer  47  in each SYSDV  40  and second instructions  68 , or software on a second single board computer  69  in each LCDV  60 . First instructions  46  in first computer  47  in each SYSDV  40  effect responsive operation of that SYSDV  40 . For example, first instructions  46  from OCS  35  can control where each SYSDV  40  should deploy its associated LCDV  60 . Second instructions  68  in second computer  69  in each LCDV  60  effect operation of that LCDV  60  in response to second instructions  68 . For example, second instructions  68  can control the elongate path  60   a  each LCDV  60  should traverse to emplace its interconnected line charge  50  along that path  60   a.    
   From laptop computer  36  in ship  30  first and second instructions  46 ,  68  in first and second computers  47 ,  69  make each SYSDV  40  and its associated LCDV  60  autonomous by providing destination/path and obstacle avoidance instructions. First and second instructions  46 ,  68  can also tell each SYSDV  40  where the deployment destination of line charge  50  by each LCDV  60  is and where each LCDV  60 &#39;s path  60   a  through approach lane  20  is. Accordingly, after each SYSDV  40  is launched, it automatically proceeds to the designated area for deployment of its payload, (LCDV  60  and its line charge  50 ), and completion of the mission. 
   At least one SYSDV  40  and LCDV  60  can have a remote control capability responsive to, for example, electromagnetic control signals  30   a  and/or acoustic control signals  30 b transmitted from ship  30 , or another remote station to allow remote control of SYSDV  40  and LCDV  60 . Additional communications capabilities can be included in communication/control modules  45  and modules of navigational equipment  66  that interface with antennas  45   a ,  66   a  and transducers  45   b ,  66   b  for SYSDV  40  and LCDV  60 , respectively. The remote control capability can be a desirable feature when tactical scenarios change. 
   SYSDV  40  of autonomous deployment system  10  can be deployed many miles from ship  30  to the seaward edge  22   a  of surf zone  22  where at least one line charge  50  is to be deployed. SYSDV  40  can have one or more propulsion means having propeller/control fin structures  41  as a swimmer delivery vehicle and/or having several tracked crawler assemblies  42  as a ground crawler vehicle similar to a heavy equipment, earth moving vehicle to propel and steer SYSDV  40  through water  23  from ship  30 . Propeller/control fin structures  41  are more likely to be selected for guided propulsion of SYSDV  40  over long distances or rough marine topography. 
   Each SYSDV  40  can be relatively large since it must transport considerable equipment and a bulky and heavy payload (LCDV  60  and line charge  50 ). SYSDV  40  has propulsion and guidance motors  43  and fuel and/or battery supply  44  for propeller/control fin structures  41  and tracked ground crawler assemblies  42 . Communications/control modules  45  are connected to structures  41  and assemblies  42  via motors  43  and are connected to single board computer  47 . Single board computer  47  can have the capacity of a desktop computer and has software  46  that is responsive to OCS  35  when each computer  47  of each SYSDV  40  is coupled to laptop computer  36  aboard ship  30 . This responsive software  46  entered into computer  47  allows it to generate proper control signals for communications/control modules  45  to get SYSDV  40  to its intended destination while avoiding any obstacles that might be encountered during the transit. En route to the intended destination, corrections and/or changes in course can be made via communications/control modules  45 . Modules  45  additionally have a navigational payload system to receive electromagnetic signals via antenna  45   a  from the global positioning system (GPS, DGPS, GPS with WAAS) and/or a long baseline acoustic navigational system to receive acoustic signals via acoustic transducers  45   b  and generate appropriate control signals to keep SYSDV  40  on course or change to a different destination as a tactical situation changes. 
   Each SYSDV  40  has a spacious storage bay  48  that can be selectably opened and closed by a hinged cover  48 a. Storage bay  48  contains a high-capacity reel  49  having a line charge  50  coiled on it and a line charge delivery vehicle (LCDV)  60 . Optionally, when a system delivery vehicle is to be used to designate an approach lane  20  (such as designator SYSDVs  40   a ,  40   b  to be described), bay  48  can contain a low-observable float  70  having a tether  71  coiled on a spool  72 . Cover  48   a  can be opened, bay  48  flooded, and tether  71  paid-out as float  70  is buoyed to surface  23   a  of water  23  as described below. 
   Typically, line charge  50  can be a series of explosive charges  51  connected together in a spaced-apart relationship from one another by flexible cord-like strength members  52 . Strength members  52  hold line explosive charges  51  as an elongate unit as it is deployed. A firing means, such as an elongate flexible detonating cord  53  may coextend with strength members  52  to explosive charges  51  to detonate them after line charge  50  has been deployed. 
   A firing device  54  can be connected to detonating cord  53  and communication/control modules  45  to initiate detonation of line charge at the proper time. Firing device  54  can be located in the components of reel  49  inside storage bay  48  of SYSDV  40 . Optionally, line charge  50  can include a redundant firing device located in LCDV  60  (not shown) that could be actuated by radio frequency, acoustic, or other signals and used in the event the primary firing device fails. The redundant firing device located on LCDV  60  can be used in the event there is unused line charge  50  remaining on reel after the deployment process is complete, which will prevent premature severing of detonation cord  53  at reel  49  when the excess line charge detonates. 
   Line charge  50  has an elongate sac  55  defining an air plenum that can surround and be connected to explosive charges  51 , strength members  52 , and detonating cord  53 . Elongate sac  55  makes line charge  50  only slightly negatively buoyant when it is in salt water  23 . Small flotation blocks (not shown) could be spaced among explosive charges  51  for buoyancy instead of elongate sac  55 . The buoyancy feature of elongate sac  55  is important because without it, LCDV  60  may not have sufficient power/traction to drag line charge  50  from reel  49  on SYSDV  40  and pay it out from reel  49  all to way through surf zone  22  and onto beach portion  25 . One option is to have each LCDV  60  bring its interconnected line charge  50  to water&#39;s edge at low tide, then later at high tide move onto beach portion  25  that is underwater at high tide. Later when the tide recedes to the next low tide condition, the part of beach portion  25  that is now not underwater can be cleared by detonation of each line charge  50 . As a further option each LCDV  60  may be made more powerful to be able to drag each line charge  50  through surf zone  23  and across beach  25 , but the more powerful LCDVs  60  might have to be larger and consequently may compromise covertness. 
   LCDV  60  is an autonomous vehicle that will automatically navigate its way from SYSDV  40 , through surf zone  22 , shoreline  24  and onto beach portion  25  (or close to the beach) using a path  60   a  that can be made perpendicular to shoreline  24 . LCDV  60  has several tracked crawler assemblies  62  mounted on it and driving means  64  are coupled to tracked crawler assemblies  62  to impart crawling motion to LCDV  60  as it crawls along exposed floor, or bottom  23   b  under water  23  in surf zone  22  and surface of beach portion  25 . Driving means  64  can be functionally the same as motors  43 , fuel and/or batteries  44  and communication/control modules  45  of SYSDV  40 . However, since the distance LCDV  60  has to travel is less than the distance SYSDV  40  must travel, less fuel or electrical power is required. 
   LCDV  60  additionally has navigation equipment  66  to successfully navigate through surf zone  22  and beach portion  25  while maintaining the desired path  60   a  to ensure that line charge  50  is properly deployed. Navigation equipment  66  of LCDV  60  includes computer  69  and modules that provide at least the functional equivalent of communication/control modules  45  of SYSDV  40 , and an acoustic long baseline receiver  67   a  is coupled to an acoustic transducer  67   b  in addition to a compass, gyroscopes, etc. In addition to receiving second instructions  68  on second computer  69  for a mission from OCS  35  of laptop computer  36  on ship  30 , second computer  69  of LCDV  60  runs a Kalman filter to calculate position and heading accurately based on information from these sensors. An antenna  66   a  can be connected to equipment  66  to provide a means of receiving electromagnetic control signals, for example, signals  30   a  from ship  30 . Transducer  67   b  provides the capability not only to transmit acoustic signals, but also to receive acoustic control signals  30   b  and other signals, such as LBL navigation signals from transmitter  73 . 
   Components and connections for modules of communication/control modules  45  and modules for navigational equipment  66  and their appropriate interconnection to responsive machinery are well known in the art. Considerable numbers of off-the-shelf units have long been available for model aircraft and boats, unmanned reconnaissance and drone craft, and full-scale marine and aircraft systems. These applications routinely rely on interfacing with numerous navigational aids, such as GPS and acoustic signals to steer a given course to a preset destination. Therefore, having this disclosure before him, one skilled in the art to which this invention pertains is free to choose and appropriately interconnect suitable components freely available in the art. 
   Line charge  50  is attached at one end to reel  49  and at its opposite end to LCDV  60 . Since reel  49  is connected to SYSDV  40 , when LCDV  60  leaves bay  48  and exerts a pulling force on line charge  50 , line charge  50  is uncoiled from reel  49  and is pulled straight. LCDV  60  proceeds on its way and may stop in surf zone  22  or extend through it and onto beach portion  25 . Line charge  50  is pulled straight and trails behind to extend along the distance traveled by LCDV  60 . Once LCDV  60  reaches a desired depth in surf zone  22  or the desired distance from SYSDV  40  to shoreline or somewhere on beach portion  25 , reel  49  on SYSDV  40  locks and LCDV  60  continues to drive forward until a predetermined tension is created on line charge  50 . Once this predetermined tension pulls line charge  50  to a desired degree of tightness, it is straightened out and further progress of LCDV  60  is arrested. SYSDV  40  and LCDV  60  serve as anchors to hold line charge  50  in place along path  60   a  until the time it is detonated. 
   Referring additionally to  FIGS. 2 and 3 , to operationally deploy system  10  an operator, user or planner onboard ship  30  designates a particular approach lane  20  that is to be cleared of obstacles  26  and mines  28 . First and a second designator SYSDVs  40   a ,  40   b  are used to place acoustic transmitters  73 , which serve as part of the acoustic LBL system and can optionally serve as a repeater for acoustic communications. The designator SYSDVs  40   a ,  40   b  are like SYSDV  40  but do not transport a line charge  50  or LCDV  60 . OCS  35  instructs designator SYSDVs  40   a ,  40   b  where to place the acoustic LBL navigation transmitters  73 . This deployment of transmitters  73  has operator on ship  30  entering appropriate first instructions  46  from OCS  34  into single board computers in SYSDVs  40   a ,  40   b . These transmitters  73  are to be placed at seaward corner positions  22   b  seaward of outer corners  22   c  of surf zone  22 . of, approach lane  20 . 
   The primary purpose of the two transmitters  73  that are placed at the seaward corner positions  22   b  near seaward edge  22   a  of surf zone  22  (depicted in  FIG. 2 ) is to serve as part of an acoustic long baseline navigation system for the SYSDVs  40  and LCDVs  60 . The communications capability of transmitters  73  is also used to relay the results of the transmitter survey (described below) back to ship  30 . A secondary purpose would be to use them as a relay/repeater for data communications between the vehicles and the ship and/or as lane markers. 
   The basic principle of a standard passive acoustic LBL system is as follows: 
   SYSDVs  40 , LCDVs  60  and the two acoustic transmitters  73  are time synchronized, and each contains a highly accurate clock, which minimizes clock drift. The two transmitters  73  are deployed (as shown in  FIG. 2 ) and surveyed using GPS. This task can be accomplished using either divers or the designator SYSDVs  40   a ,  40   b . Latitude/longitude pairs for the position of each transmitter  73  are acoustically transmitted back to ship  30  from designator SYSDVs  40   a ,  40   b  or if divers are used to deploy the system, the position information is radioed from the divers to ship  30 . The position of each LBL navigation transmitter is then provided to each SYSDV  40  and LCDV  60  as part of first instruction  46  and second instruction  68 . Each LBL transmission of each transmitter  73  will “chirp” at different intervals (e.g. one transmitter  73  will chirp one second and the other transmitter  73  will chirp the next second, and so on). SYSDVs  40  and LCDVs  60  using the LBL system “listen” for the chirps, and when a chirp is detected the vehicle takes note of the time it was received. The SYSDVs  40  and LCDVs  60  using the LBL system know at what times each transmitter  73  will chirp, so using this information in combination with the time the chirp arrived, the “time of flight” for the chirp can be determined. So, for example, if SYSDV  40  or LCDV  60  knows that one of transmitters  73  was supposed to transmit at time 2025 seconds and it received the chirp at 2025.5 seconds, the time of flight would then be 0.5 seconds. By using the time of flight for the chirps received from each transmitter  73  and the speed of sound in water equation, which is also dependent on water temperature (a temperature sensor is a component of the LBL receiver located in each SYSDV  40  and LCDV  60 ), each of SYSDVs  40  and LCDVs  60  can determine its distance from each transmitter  73 . Since the position of each transmitter  73  has been surveyed, and the distance from each of these two points is known, each of SYSDVs  40  and LCDVs  60  can then determine both their relative and absolute positions using simple trigonometry. 
   Designator SYSDVs  40   a ,  40   b  leave ship  30  and autonomously transit to the seaward edge  22   a  of surf zone  22  of approach lane  20  in accordance with instructions on their first computers  47 . Near seaward edge  22   a , each SYSDV  40   a ,  40   b  floods ballast tanks  40   aa  and sinks to the bottom to each deploy a long baseline acoustic transmitter  73  and a low-observable float  70  at seaward corner positions  220   b  located just outside of outer corners  22   c  of surf zone  22  of approach lane  20 . 
   Each float  70  is buoyed upward and has depth sensor  74  and a GPS receiver  75  mounted on it to float at surface  23   a . Tether  71  is paidout from spool  72  on each SYSDV  40   a ,  40   b  at seaward corner positions  22   b  until each depth sensor  74  detects that float  70  has reached surface  23   a . Spool  72  is rotated to reduce the slack in tether  71 , to reduce error that might be attributed to watch circle. GPS receiver  75  on float  70  integrates its position for a given length of time to improve the accuracy of the position survey. 
   After gathering the needed data, each float is retracted below surface  23   a  to maintain covertness. The position data for each acoustic LBL navigation transmitter  73  located at each seaward corner position  22   b  is acoustically transmitted via transmitters  73  back to ship  30  and to any additional SYSDVs  40  or LCDVs  60  currently in the water. The transmitted data can be incorporated into OCS  35  in computer  36  and included as part of instructions  46  and  68  for other SYSDVs  40  and their associated LCDVs  60  that will require these coordinates to utilize the LBL navigational system to accurately emplace several line charges  50 . 
   Next, the operator on ship  30  enters two latitude/longitude pairs indicating the position of each acoustic LBL transmitter  73  located in designator SYSDVs  40   a ,  40   b  and four additional coordinates representing the corners of approach lane  20  to be cleared into OCS  35 . OCS  35  displays a map of the area of approach lane  20  and requests that the user confirms the field layout of approach lane  20 . 
   Another way to get the needed data is contrary to the autonomous procedure described above. Transmitters  73  are deployed using divers that are sent out from ship  30 . Divers make their way to the deployment position (seaward corner positions  22   b ), they survey their positions using the global positioning system (GPS), and relay the GPS coordinates of each acoustic LBL navigation transmitter  73  to ship  30 . The GPS coordinates are entered into OCS  35  on computer  36  on ship  30  to initialize SYSDVs  40  and LCDVs  60  for clearing of approach lane  20 . 
   Actual clearing of approach lane  20  can now begin in earnest. Computer  36  on ship  30  is coupled to first and second computers  47 ,  69  on SYSDVs  40  and LCDVs  60 , respectively. OCS  35  on computer  36  initializes first and second computers  47 ,  69  on SYSDVs  40  and LCDVs  60 , providing them with first and second instructions  46 ,  68  containing the field information necessary for them to complete their mission. 
   SYSDVs  40  which contain explosive line charges  50 , LCDVs  60 , and other system components needed to deploy line charges  50 , are deployed, or launched from ship  30 . Since each of SYSDVs  40  has different first instructions  46  in their first computers  47 , each of SYSDVs  40  transits to arrive at different designated base positions  80  spaced apart from one another in a side-by-side relationship along seaward edge  22   a  of surf zone  22  and approach lane  20  to be cleared, see  FIGS. 4 and 5 . 
   At positions  80  first computers  47  of SYSDVs  40  initiate flooding of one or more internal compartments  40   aa  and SYSDVs  40  sink through water  23  to bottom  23   b  of water  23 . At a predetermined time that is in accordance with first instructions  46  in first computers  47 , covers  48 a are rotated open, and bays  48  of SYSDVs  40  are flooded. In accordance with the different second instructions  68  in second computers  69  of each LCDV  60 , tracked crawler assemblies  62  of LCDVs  60  in flooded bays  48  are activated and proceed to crawl over opened covers  48   a  and onto bottom  23   b . Each LCDV  60  pulls on an interconnected line charge  50  that is each wrapped about reel  49  and rotates reel  49  as it drags part of line charge  50  behind. Each reel  49  in each SYSDV  40  continues to rotate as each LCDV  60  unwraps and pulls more and more of its interconnected line charge  50  from its position of coiled stowage. Different second instructions  68  in second computers  69  in each of LCDVs  60  guide each LCDV  60  along a different path  60   a  that are parallel and equal distantly spaced from each other. As each LCDV  60  crawls, or progresses along bottom  23   b  in surf zone  22 , each line charge  50  is dragged along and pulled straight to space and emplace explosive charges  51  apart in their predetermined parallel separation in paths  60   a . Elongate sac  54  on each line charge  50  partially buoys at least part of the load of line charge  50  upward in surf zone  22  to reduce part of the entrained load created by each line charge  50 , and the amount of force exerted by crawler assemblies  62 . 
   When only surf zone  22  of approach lane  20  is to be cleared, line charges  50  in paths  60   a  do not have to extend onto beach portion  25  and can be detonated entirely in surf zone  22 . First instructions  46  control SYSDVs  40  to allow LCDVs  60  to reach a predetermined destination (e. g. shoreline  24 ) or depth in surf zone  22 . At this predetermined destination, their interconnected reels  49  in SYSDVs  40  are locked to prevent further outward travel of LCDVs  60  that are connected to the opposite ends of line charges  50 . Each of these locked-in-place line charges  50  are stretched tight and each interconnected SYSDV  40  and LCDV  60  serve as anchors to hold the stretched line charges  50  in place along paths  60   a.    
   Once line charges SO are appropriately stretched along paths  60   a , LCDVs  60  can be inactivated to allow line charges to remain in place. Line charges  50  emplaced in surf zone  22  can be detonated now or later to clear surf zone  22 . 
   In response to a tactical situation, line charges  50  emplaced in surf zone  22  as described above can remain undetected for a prolonged period of time. Later, coiled portions of line charges  50  remaining on reels  49  in SYSDVs  40  can be utilized to enable extension of line charges  50  so that they can additionally reach across part of beach portion  25  of approach lane  20 . 
   In accordance with a sequence preprogrammed in first instructions  46 , the passage of time, or a remote acoustic signal  30   b , first instructions  46  can unlock SYSDVs  40  to release reels  49  to unwind more of line charges  50  that are still coiled on them. Second instructions  68  reactivate LCDVs  60  to pull line charges  50  to further extend in paths  60   a  parallel with respect to one another across shoreline  24  and partially onto beach portion  25 . Line charges  50  extend paths  60   a  equally spaced apart from and parallel with each other throughout surf zone  22  and beach portion  25  of approach lane  20 . Detonation of extended line charges  50  can be made in sequences or simultaneously via each firing device  54 . 
   Line charges  50  also can be emplaced throughout surf zone  22  and part of beach portion  25  of approach lane in a single uninterrupted sequence. Emplacement of the entire lengths of line charges  50  need not have a period of time elapse while parts of line charges  50  are extended in surf zone  22 . This uninterrupted, continuous sequence can include tightening of emplaced line charges  50  that extend from SYSDVs  40  at seaward base positions  80  at seaward edge  22   a  to LCDVs  60  where they have progressed to inland positions  90  at the inland edge  25   a  of approach lane  20 . 
   First and second instructions  46  and  68  control emplacement of line charges  50  in parallel equally spaced apart distributions  60   a  of explosive charges  51  of line charges  50  in surf zone  22  and beach portion  25 . The separations between distributions  60   a  and the spacing between explosive charges  51  assure the creation of an aggregate intense explosive effect to neutralize obstacles  26  and mines  28  (usually by destruction) within approach lane  20  and make approach lane  20  safe for transit of personnel, materials, and vehicles. 
   In these or other deployment sequences the locations and paths of SYSDVs  40  and LCDVs  60  can be different. The payloads of line charges  50  can be different to include one or more larger explosive charges or instrumentation packages to accomplish some other desired tactical result. Irrespective of the exact configuration of the constituents of system  10  of the invention, it is a covert and fully autonomous means of clearing obstacles and mines in approach lane  20  that is capable of being safely deployed from over-the-horizon and keeping personnel away from danger. 
   SYSDV  40  could use tracked crawler assemblies  42  in a crawler mode that allow SYSDV  40  to crawl on bottom  23   b  of water  23  to deliver LCDVs  60  and line charges  50 . SYSDV  40  could use propeller/fin arrangement  41  in the swimmer-delivery mode that propels SYSDV  40  through water  23  above bottom  23   b  and through water  23  to deliver LCDVs  60  and line charges  50 . Both delivery capabilities are schematically depicted for SYSDV  40  and could be used alone or in combination depending on what is found to be the most effective way to successfully complete the mission. 
   A swimmer-type vehicle could be used instead of a crawler type LCDV  60 , but this might limit deployment of line charges  50  to only part of surf zone  22 . The clock of GPS could be used to synchronize a passive acoustic LBL navigational system, such as described above to simplify the synchronization process. 
   Another option is to have all of the navigation components installed only on LCDVs  60  instead of on both LCDVs  60  and SYSDVs  40 . The navigation data from such LCDVs  60  would be shared with SYSDVs  40  for use during transit of SYSDVs  40  from ship  30  to approach lane  20  through a temporary umbilical connected to LCDVs  60  in storage bays  48 . Having all of the navigational components in LCDVs  60  reduces the overall system cost since all SYSDVs  40  and LCDVs  60  are destroyed at the time of detonation of their emplaced line charges  50 . 
   Having the teachings of this invention in mind, modifications and alternate embodiments of autonomous system  10  may be adapted without departing from the scope of the invention. Its uncomplicated, compact design incorporates structures and technologies long proven to operate successfully in the hostile marine environment. Autonomous system  10  lends itself to numerous modifications to permit its reliable use in different ways for different purposes in hostile and demanding environments both on open water and over many different types of land mass, including but not limited to beaches, hard-pack, soft mud, marsh, tidal flats etc. Autonomous system  10  of the invention can be made larger or smaller in different shapes and fabricated from a wide variety of materials to assure resistance to corrosion, sufficient strength for heavy loads, and long-term reliable operation under a multitude of different operational requirements. 
   The disclosed components and their arrangements as disclosed herein, all contribute to the novel features of this invention. Autonomous system  10  provides a multipurpose and capable means of emplacing elongates line charges  50  to assure neutralization of obstacles and mines irrespective of ambient conditions and terrain. Therefore, autonomous 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.