Abstract:
The present invention relates to systems for launching and retrieving underwater craft from a ship. It consists mainly of a handling cradle for launching and retrieving an underwater vehicle, comprising a frame forming a dorsal ridge and providing an interface between lifting means, a crane for example, and the underwater vehicle. This frame comprises: means for adjusting the overall buoyancy; means for automatically aligning the vehicle with the dorsal ridge formed by the frame; means for grasping the vehicle from the surface after the frame has been aligned with the vehicle. In a preferred embodiment, the cradle comprises an onboard video camera enabling the operator onboard the ship to ensure that the vehicle attachment and release operations are carried out correctly. The invention advantageously allows the vehicle to be launched and retrieved automatically when the vehicle is under the surface in an area where it is not subject to the effects of the swell.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage of International patent application PCT/EP2009/056821, filed on Jun. 3, 2009, which claims priority to foreign French patent application No. FR 0803058, filed on Jun. 3, 2008, the disclosures of which are incorporated by reference in their entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to the general field of the handling, loading and unloading of objects from a transport platform. More particularly, it relates to the systems for launching and retrieving underwater craft from a ship. 
     BACKGROUND 
     The handling of a unmanned underwater vehicle, by a transport platform, a ship for example, has hitherto generally required the intervention of human operators. A lifting tool is generally used, of crane type, available onboard for various lifting operations. This lifting tool can be used simply to move the underwater vehicle on the platform, to deposit it on the surface of the water and to raise it back onboard from the surface. 
     During launching, the attaching of the vehicle to the crane and then its release are then performed manually by operators responsible for handling. A team positioned on the deck of the platform attaches the vehicle to the crane cable and a team positioned onboard a light craft, of inflatable craft type for example, releases the vehicle while the latter is floating on the surface. 
     Conversely, during the retrieval of the vehicle, a team positioned onboard a light craft attaches the vehicle from the surface, while a team positioned on the deck of the platform releases the vehicle. 
     This type of handling, in addition to the fact that it involves a large number of operators, also has the drawback that attachment and release operations must be carried out while the vehicle is on the surface and it is therefore subject to wave movement. Consequently, launching and retrieving a vehicle in heavy weather is difficult. First of all, it requires the operators to perform attachment and release operations in heavy weather, from a light craft which is ill suited to this type of weather. Then, it requires the underwater vehicle to be positioned on the surface in proximity to the platform while the movement of the waves makes it impossible to maintain a fixed position. 
     Consequently, in heavy weather, launching and retrieving the underwater vehicle becomes perilous both at the human level through the danger to which the operators responsible for handling are subject, and at the equipment level through the risk of damage by collision both to the transport platform and the light craft and to the underwater vehicle. Thus, the use of the underwater vehicle in all weathers is generally handled from a dedicated platform, equipped with specific means closely adapted to the vehicle concerned, enabling the vehicle to be attached and released automatically. 
     SUMMARY OF THE INVENTION 
     One aim of the invention is to propose a solution making it possible to employ an underwater vehicle from a transport platform without requiring the intervention of handlers in order, from a light craft, to attach the vehicle to the lifting means with which the platform is equipped and then release it. Another aim of the invention is to propose a solution that makes it possible to carry out these operations while limiting the risks of collision between the platform and the underwater vehicle when the latter is in proximity to the platform. To this end, an object of the invention is a handling cradle for launching and retrieving an underwater vehicle, comprising a frame forming a dorsal ridge and providing an interface between lifting means and the underwater vehicle. According to the invention, the frame comprises:
         means for adjusting the overall buoyancy;   means for automatically aligning the vehicle with the dorsal ridge formed by the frame;   means for grasping the vehicle after the frame has been aligned with the vehicle.       

     According to a preferred embodiment of the invention, the means for adjusting the overall buoyancy comprise ballast floats arranged along the frame. 
     According to another preferred embodiment of the invention, which can be combined with the preceding embodiment, the means for aligning the frame with the underwater vehicle comprise an end piece of conical overall shape arranged at one end of the frame, the end piece being dimensioned and configured to accommodate the front end of the vehicle. 
     According to another preferred embodiment of the invention, which can be combined with the preceding embodiment, the means for grasping the vehicle comprise two articulated arms arranged on the frame and configured so as to encircle the lateral walls of the vehicle. 
     Another object of the invention is a remotely-operable handling system for an underwater vehicle, which comprises lifting means associated with a handling cradle according to the invention, the grasping device being connected to the lifting means by an electric pulling cable wound on a winch. 
     According to a preferred embodiment, the handling system according to the invention also comprises control and monitoring means for ensuring the alignment of the frame with the vehicle and actuating the various means of the handling cradle, the control and monitoring signals being transmitted by the electric towing cable. 
     According to another preferred embodiment of the handling system according to the invention, which can be combined with the preceding embodiment, the control and monitoring means comprise a camera mounted on the handling cradle configured to view the underwater vehicle during its approach to the handling cradle and during the operations of aligning the frame with the vehicle. 
     Another object of the invention is a method for launching an underwater vehicle by means of the handling system according to the invention, a method whereby the following operations are carried out in succession:
         positioning the handling cradle containing the vehicle above the water plane;   lifting down the handling cradle;   controlling the immersion of the handling cradle to the desired depth;   releasing of the vehicle: opening the grasping means;   piloting the departure of the vehicle;   switching the vehicle to standalone operating mode.       

     An object of the invention is finally a method for retrieving an underwater vehicle by means of the handling system according to the invention, a method whereby the following operations are carried out in succession:
         switching the vehicle to remote-controlled operating mode;   piloting the approach of the vehicle;   inserting the vehicle into the alignment means of the handling cradle;   keeping the vehicle moving to align the frame with the vehicle;   stopping the vehicle and closing the grasping means;   lifting up the vehicle in the handling cradle;   positioning the handling cradle enclosing the vehicle in the storage area.       

     The device according to the invention advantageously enables a transport platform, a scientific ship for example, to carry an underwater vehicle, an automatic vehicle of relatively small size for example, and to automatically deploy such a vehicle, even in heavy seas, without requiring manual operations and without risking a collision between the platform and the vehicle. This deployment can also advantageously be performed with simple lifting means. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the invention will be better appreciated from the following description which explains the invention through a particular embodiment taken as a nonlimiting example and which is based on the appended figures, which represent: 
         FIG. 1 , a schematic representation of the grasping device according to the invention, 
         FIGS. 2 ,  4  and  6 , plan views illustrating the operating principle of the grasping device according to the invention, 
         FIGS. 3 ,  5  and  7 , plan views illustrating the operating principle of the grasping device according to the invention, 
         FIGS. 8 to 10 , illustrations relative to a variant embodiment incorporating video means for guiding the vehicle toward the cradle and monitoring its position. 
     
    
    
     DETAILED DESCRIPTION 
     The following description presents the features of the invention through a particular application taken as a nonlimiting example of deployment. The application described here relates to the implementation of handling, launching and retrieving means, remotely operated, suited to a drone-type automatic underwater vehicle. 
       FIG. 1  shows a general view of the handling cradle  10  according to the invention, intended to house the underwater vehicle during launching and retrieval maneuvers. The latter mainly comprises a central frame  11  forming a dorsal ridge and a fixing area  17  where the cradle is attached to a pulling cable  18  used to lift the cradle  10 . 
     Preferably, the cable  18  is attached to the cradle  10 , as illustrated by  FIG. 1 , via an articulated fixing. In this way, when it is suspended at the end of the cable, the cradle  10  can be freely oriented without inflicting excessive twisting on the pulling cable  18 . 
     The central frame  11  supports grasping means  14  distributed along the latter and configured to grip and hold the underwater vehicle. Preferably, these means  14  comprise articulated arms which, on command, encircle the wall of the vehicle by following the profile of this wall. To this end, the grasping means may, for example, consist, as illustrated in the figure, of a plurality of sets of rigid arms in the form of circular arcs  15 ,  16 , articulated at the frame, arranged in opposition to one another and being able, on command, to be lowered to grip the vehicle or be raised to release it. Alternatively, the arms forming each set may consist of a plurality of articulated segments, the latter configuration for example allowing a vehicle whose wall does not have a regular profile to be gripped. 
     From an operational point of view, the grasping means are actuated when as the underwater vehicle has penetrated into the space  101  delimited by the cradle, it is positioned inside this space so as to be in contact with the frame  11  and to be oriented so that its main axis is parallel to the axis  19  of the frame. 
     The frame  11  also supports means  13  for enabling automatic positioning of the vehicle inside the space  101  delimited by the cradle, in particular its alignment relative to the axis  19  of the frame. To this end, these means consist of a mechanical structure fixed to the front of the frame, defining a space  131  that can house the front end of the vehicle. According to the invention, the structure  13  has a flared opening enabling the front end of the vehicle to be housed in the housing space  131  even if the vehicle is not strictly aligned with the axis of the frame when it penetrates into the space  101  delimited by the cradle  10 . It is arranged so that, when the front end of the vehicle is completely is engaged in the housing space  131 , the frame  11  is positioned in contact with the wall of the vehicle or at least at a very short distance from the latter. 
     Preferably, the means  13  for enabling automatic positioning of the vehicle inside the cradle  10  are associated with complementary means making it possible to check that the vehicle has been correctly positioned in the cradle. These monitoring means, not represented in the figure, can take various forms, the form of devices with electrical contacts or optical devices for example. 
     According to the invention, the frame  11  also supports means  12  which provide the cradle  10  with the variable buoyancy in water. These means consist, for example as illustrated in the figure, of floats associated with ballasts configured and arranged on the structure so as to confer upon it a horizontal position when it is immersed. Thus, by varying the buoyancy of the floats, it is possible to keep the cradle at a given depth and in a horizontal position. Consequently, the grasping of the underwater vehicle can advantageously be done without the latter having to surface. Consequently, the depth at which the underwater vehicle is grasped can advantageously be chosen so that this operation takes place in calm waters. 
       FIGS. 2 to 7  present views illustrating at different instants the operating principle of the handling cradle  10  according to the invention during the retrieval of an underwater vehicle  20  by a handling system comprising such a cradle. 
       FIGS. 2 and 3  illustrate the phase of the operation during which the operations for both bringing the frame into contact with the vehicle and aligning the frame with the vehicle are carried out. 
     During this phase, the vehicle  21  is moving. It inserts its front end into the positioning means and drives, in its movement symbolized by the arrows  21  and  31 , the cradle  10  whose grasping means  14  are in the raised position. Under the action of the movement impelled by the vehicle and the inertia of the cradle, the latter performs a rotational movement in the horizontal plane and the vertical plane, a movement which has the effect of aligning the axis  19  of the frame  11  on the axis  33  of the vehicle and of bringing the frame  11  toward the wall of the vehicle. The arrows  22  and  32  symbolize these two movements impelled by the driving of the cradle  10  by the vehicle  20 . Consequently, at the end of this phase, the underwater vehicle  20  and the cradle are correctly positioned relative to one another so that the actual grasping operation can begin. The vehicle  20  then no longer exerts any propulsion. 
       FIGS. 4 and 5  illustrate the beginning of the actual grasping operation. During this phase, the vehicle and the cradle are correctly positioned relative to one another: the axes  19  and  33  are parallel and the frame  11  is in contact with the wall of the vehicle  20 . The grasping means  14  are then actuated and the arms  15  and  16  pivot according to a movement symbolized by the arrows  41  to come into contact with the wall of the vehicle on each side of this wall. 
     The actual grasping operation continues until the arms  15  and  16  have completely pivoted so that they ultimately form a belt which encircles the vehicle  20  and causes the latter to be firmly attached to the cradle  10  in its movements. This phase of the operation is illustrated by  FIGS. 6 and 7 . 
     At this stage, the vehicle-cradle assembly can be raised onboard the transport platform using the lifting means which are not represented here, a crane for example, by winding the cable  19  onto a winch situated onboard the platform. 
     According to the invention, the cradle  10  therefore constitutes an element of a complete handling system including the cradle  10 , the pulling cable  19 , the lifting means and monitoring and control means. The function of these means is to allow the various means possessed by the cradle  10  to be employed. The control and monitoring means in particular enable an operator situated onboard to manage the means  12  providing the variable buoyancy of the cradle, to manage the grasping means  14  and to manage control of the winch which actuates the unwinding and winding of the pulling cable  19 , actions which cause the cradle  10  to be lifted down and up. In the case where the handling system is in particular intended for the launching and retrieval of an automatic drone-type vehicle, these control and monitoring means may preferably be configured to enable the operator to check the correct positioning of the cradle  10  and of the underwater vehicle  20 , in particular before actuating the grasping means  14  during the vehicle retrieval operation. To this end, the cradle  10  is equipped with complementary means configured to transmit to the control and monitoring means information relating to the positioning of the vehicle in the cradle. These complementary means may consist of video means, a camera fixed to the rear of the frame  11  for example. They also facilitate the approach operations of the vehicle  20  toward the cradle  10 , an approach which may be performed automatically by the vehicle  20  or conducted from the transport platform by an operator, the vehicle then being remotely controlled from the platform for the cradle linking phase. 
       FIGS. 8 to 10  illustrate the manner in which a handling system as described previously and comprising a video camera onboard the cradle  10  can be employed to handle the taking over and retrieval of an automatic underwater vehicle. The figures present views of the underwater vehicle to be retrieved for instants corres-ponding to different phases of the operation. These views obtained from a video camera positioned on the rear end of the frame  11  of the cradle  10  are used by the operator to manage the necessary maneuvers. The procedure for launching the vehicle using this same handling system can also be easily deduced from the procedure used to retrieve it. 
     In such a context, the vehicle  20  is, for example, positioned at the end of a mission in the vicinity of the cradle  10  which waits for it at a given depth, chosen according to the calm nature of the waters at this depth, then switches to a remote-controlled operating mode. The operator onboard the platform obtains an image similar to that of  FIG. 8 . 
     The operator then acts on the navigation and propulsion controls of the vehicle so as to guide the latter toward the cradle and to engage its front end in the positioning means  13 . The operator onboard the platform obtains an image similar to that of  FIG. 9 . 
     It maintains the propulsion of the vehicle so that the end of the vehicle is entirely housed in the positioning means  13  and so that the cradle  10 , driven in the movement of the vehicle, is oriented so that the frame  11  is aligned with the axis of the vehicle. It simultaneously monitors the progress of the maneuvers carried out and of the result obtained on a video camera linked to the video camera positioned at the rear of the frame. 
     Then, as soon as the vehicle  20  and the frame  11  of the cradle  10  are aligned and in contact with one another, in a situation corresponding to the image of  FIG. 10 , in which the vehicle is centered, the operator stops the vehicle propulsion system and actuates the grasping means  14 , so as to enclose the vehicle in the cradle. The cradle  10  is then raised onboard the transport platform by controlling the winding of the pulling cable  18 , and positioned in its storage area by the lifting means. 
     The exchanges of information and commands between the cradle  10  and the control and monitoring means are handled, conventionally, via the cable  18  which links the cradle to the lifting means. To this end, this cable, called “electric towing cable”, may include a plurality of strands intended to fulfill the pulling function and one or more strands forming electrical conductors intended to conduct the signals exchanged by the cradle and the control and monitoring means. Alternatively, it may include strands consisting of optical fibers. 
     As for the exchanges of commands and information between the vehicle and the control and monitoring means, these may be carried out by any appropriate communication means. In a particular embodiment of the handling system, the communication means may, for example, be installed on the cradle. 
     Implementing and installing a handling system as described previously is advantageously made simple by the use of the cradle  10  according to the invention, which in itself takes into account most of the specific features of the vehicle  20  to be launched and retrieved. In this way, since the cradle  10  constitutes a true adaptation interface, it is notably useful to install specific lifting and pulling means. Incidentally, the procedures for launching and retrieving an underwater vehicle are also simplified. They can also largely be remotely operated. 
     Consequently, the method for launching an underwater vehicle by means of the handling system according to the invention implements the following operations in succession:
         positioning the cradle  10  containing the vehicle above the water plane;   lifting down the empty cradle  10 ;   controlling the immersion of the cradle to the desired depth; unwinding the electric pulling cable  18 ;   releasing the vehicle  20 : opening the grasping means  14 ;   remotely piloting the departure of the vehicle  20 ;   switching the vehicle  20  to standalone operating mode.       

     Similarly, the method for retrieving an underwater vehicle by means of the handling system according to the invention implements the following operations in succession:
         switching the vehicle  20  to remote-controlled operating mode;   piloting the approach of the vehicle;   inserting the vehicle into the alignment means  13  of the cradle;   keeping the vehicle moving to align the frame  11  with the vehicle  20 ;   stopping the vehicle and closing the grasping means  14 ; attachment;   raising the cradle  10  enclosing the vehicle  20 ;   positioning the cradle  10  enclosing the vehicle  20  in the storage area.       

     Implementing such methods advantageously does not assume the intervention of operators to perform attachment and release operations in sometimes perilous conditions.