Abstract:
A system for interconnecting a mother ship with a submersible vehicle using a cable towed by the mother ship. The cable has a first cable end connected to the mother ship and a second cable end to be connected to the submersible vehicle. The second cable end is provided with a first connector. A capturing mast is arranged at the submersible vehicle for capturing the cable towed by the mother ship. A connector holder is arranged at the submersible vehicle for holding the first connector when it is to be connected to a second connector. The second connector is connected to the submersible vehicle. A first guide is arranged at the submersible vehicle for guiding the first connector towards the connector holder of the submersible vehicle. A second guide turns the connector to a well defined position into the connector holder.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a system for interconnecting a mother ship with a submersible vehicle, using a cable towed by the mother ship, the cable having a first cable end connected to the mother ship, and a second cable end to be connected to the submersible vehicle. 
       BACKGROUND 
       [0002]    U.S. Pat. No. 5,748,102 disclose an apparatus for interconnecting an unmanned underwater vehicle and a free floating communications pod. 
       SUMMARY OF THE INVENTION 
       [0003]    The inventors have realised that thee is a need within the field of submersible vehicles, in particular autonomous underwater vehicles (AUVs) and unmanned underwater vehicles (UUVs), and even unmanned surface vehicle (USV), to be able to be recharged without having to take them ashore, or aboard or alongside a mother ship to connect manually to a power cable or the like. There is also a need to be able to upload data via high speed data link, e.g. via an optical fibre connection, to said submersible vehicle. In addition, sometimes there is an need to operate an AUV in a more conventional way, that is, operation by having real time communication with, and by having power supplied by, a surface mother ship. 
         [0004]    Therefore, it is an object of the present invention to provide a system for enabling an underwater vehicle to capture a cable towed by a mother ship, to find a first connector at an end of said cable, and to connect said connector to a second connector being part of said underwater vehicle. When the cable is connected, this enables for example for the transmission of electrical power to recharge batteries of the unmanned underwater vehicle. In one embodiment the first connector has an oval cross section. In another embodiment the connector has a circular cross section. The UUV is provided with a capturing mast, preferably arranged to be moveable, even more preferred it is arranged to be foldable, and being arranged to capture the cable during a manoeuvre wherein the UUV is travelling largely transversally to the lengthwise direction of the cable. The capturing mast is preferably arranged to fold due to the cable pulling forces and the driving force of the swimming UUV. Alternatively, a force transducer can be arranged to sense a pulling force affecting the capturing mast, and a motor or servo arrangement can be arranged to fold the capturing mast when the sensed pulling force exceeds a certain value. When a foldable capturing mast folds from an upright position to a folded position the cable follows and comes closer to an upper surface of the UUV. The cable also comes closer to a first guiding frame of a particular shape. As the cable runs in the first guiding frame, eventually the cable end together with the connector will be guided down to a connector cradle having guiding structures wherein the connector, due to the oval shape, turns into a predetermined position to enable the second connector to be linearly moved by the help of an actuator, and establish electrical contact by connecting the second connector with the first connector. 
         [0005]    Thus, according to a first aspect there is provided a submersible vehicle having means for connecting to a cable in water having a first cable end with a first connector to be connected to the submersible vehicle, the submersible vehicle comprises: 
         [0006]    a capturing mast; 
         [0007]    a first guiding means; 
         [0008]    a connector holder; 
         [0000]    wherein the capturing mast is adapted to capture the cable and guide the cable towards the first guiding means;
 
the first guiding means is adapted to guide the first connector towards the connector holder;
 
the connector holder is adapted to hold the first connector when it is to be connected to a second connector.
 
         [0009]    The submersible vehicle may further comprise: 
         [0010]    second guiding means for turning the connector to a predefined position into the connector holder. 
         [0011]    The capturing mast is preferably moveable, and even foldable. 
         [0000]    The first guiding means is a preferably a guiding frame. The second guiding means is preferably a guiding frame. 
         [0012]    The submersible vehicle further comprises an actuator arranged at the submersible vehicle for moving the second connector, towards the first connector to establish connection between the mother ship and the submersible vehicle. 
         [0013]    The actuator is preferably a linear actuator arranged at the submersible vehicle for linearly moving the second connector, towards the first connector to establish connection between the mother ship and the submersible vehicle. 
         [0014]    The capturing mast is preferably arranged at a distance from the longitudinal midline of the submersible vehicle and at a front half portion of the submersible vehicle. 
         [0015]    The first guiding means is arranged near a horizontal midline and at a rear half portion of the submersible vehicle. 
         [0016]    The submersible vehicle has an upper side mainly free of protruding objects except for the capturing mast and the guiding means. 
         [0017]    The first guiding means comprises a first and a second member, the first member is arranged to guide the cable downwards and sideways towards the second guiding frame, and the second member is arranged to guide the cable mainly in sideways direction towards the second guiding frame. 
         [0000]    The submersible vehicle may be provided with a hook organ arranged at a top portion of the capturing mast. 
         [0018]    The hook organ may be partly ring shaped for surrounding the cable, and has an opening for letting the cable into space defined by the hook organ, as an alternative, the hook organ is a principally a straight member arranged with an angle towards a main portion of the mast. 
         [0019]    According to a second aspect there is provided a system for interconnecting a mother ship with a submersible vehicle, using a cable towed by the mother ship, the cable having a first cable end connected to the mother ship, and a second cable end to be connected to the submersible vehicle, the second cable end being provided with a first connector, the system comprising: 
         [0020]    a capturing mast arranged at the submersible vehicle for capturing the cable towed by the mother ship; 
         [0021]    a connector holder being arranged at the submersible vehicle for holding the first connector when it is to be connected to a second connector, the second connector being connected to the submersible vehicle; 
         [0022]    first guiding means being arranged at the submersible vehicle for guiding the first connector towards the connector holder of the submersible vehicle; 
         [0023]    second guiding means for turning the connector to a predefined position into the connector holder. 
         [0024]    According to a third aspect there is provided a method for connecting a towed cable to a submersible vehicle, the cable having a second cable end connectable to an entity, and a first cable end to be connected to the submersible vehicle, the first cable end being provided with a first connector, the method comprising the following steps: 
         [0025]    capturing the cable with the aid of a capturing mast arranged at the submersible vehicle; 
         [0026]    guiding the cable towards first guiding means with the aid of the capturing mast 
         [0027]    guiding the first connector towards a connector holder of the submersible vehicle with the aid of first guiding means; 
         [0028]    holding the first connector with the aid of the connector holder which holder is adapted to hold the connector firmly in the predefined position where it can be connected to a second connector, the second connector being connected to the submersible vehicle; 
         [0029]    moving the second connector towards the first connector. 
         [0030]    The method may further comprise the step of: 
         [0031]    turning the connector to a predefined position into the connector holder. 
         [0032]    Described embodiments discloses features that enable handling of rotationally dependent connectors, i.e., connectors that must be rotated into a particular position to be able to connect, just like many normal domestic connectors. If so rotationally independent connectors, i.e., connectors which do not need to be in a certain rotational position to enable connection, were used, the design of the embodiments could of course be simplified. On the market today there is a wider supply of rotationally dependent connectors having a wide range of specifications concerning maximum current, water resistance etc., and therefore it is desirable to not having to be forced to use rotationally independent connectors. 
         [0033]    It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, elements, integers, steps, components or groups thereof. Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]    Preferred embodiments will be explained below with the aid of enclosed drawings, of which 
           [0035]      FIG. 1  shows a side view of an UUV with means of a first embodiment for capturing a towed cable and connecting to a connector at an end of said cable; 
           [0036]      FIG. 2   a  shows a view from above of the UUV of  FIG. 1 ; 
           [0037]      FIG. 2   b  shows an aft view of the UUV of  FIG. 1   
           [0038]      FIG. 2   c  shows an enlarged side view of the aft half portion of the UUV of  FIG. 1   
           [0039]      FIGS. 2   d - f  shows detailed views of the UUV at a certain moments of cable docking 
           [0040]      FIG. 3  shows a side view of an UUV with means according to a second embodiment, for capturing a towed cable and connecting to a connector at an end of said cable; 
           [0041]      FIG. 4  shows a view from above of the UUV of  FIG. 3 ; 
           [0042]      FIG. 5  shows a detailed view of a second embodiment of a capturing mast having captured a cylindrical connector; 
           [0043]      FIG. 6  shows an even more detailed view of the cylindrical connector of  FIG. 5   
           [0044]      FIG. 7   a  shows a detailed view of the linear actuator and a connector of oval cross section; 
           [0045]      FIG. 7   b  shows a detailed view of a cam arrangement for turning the connector of the UUV into a position determined by a guiding pin of the connector of the cable. 
       
    
    
     DETAILED DESCRIPTION 
       [0046]      FIG. 1  shows a side view of an UUV  110  with means for capturing a towed cable and connecting to a connector at an end of said cable. A foldable capturing mast  105  is arranged at a side of the UUV  110 , and is foldable around a pivoting point  107 . 
         [0047]    The foldable capturing mast  105  can be raised to an upright position as shown in  FIG. 1 , and can be folded by a folding angle  115  to a folded position as is shown in  FIG. 2 . The folding angle is arranged to be around 75 to 90 degrees. More preferred is around 90 degrees. The capturing mast comprises a main portion  101  and a hook portion  102 ,  103 ,  104 ,  106 . When there is captured a cable, the foldable capturing mast folds and cable pulling forces and a mid section of the hook portion arranged with a hook angle  140  in relation to the main portion  101 , forces the cable to travel towards a hook bend  102  of the foldable capturing mast. The cable  211 ,  212  now can be said to comprise two sections, a first section  211  extending from the mother ship to the hook bend  102  of the foldable capturing mast  105 , and a second section  212  extending from the hook bend  102  of the foldable capturing mast  105  to the cable end with the connector  220 . Due to the movement of the UUV  110  and of the mother ship, and according to hydrodynamics, there are forces pulling the cable section  211 ,  210  obliquely backwards in relation to UUV travelling direction  150 . When a cable angle A between the first section  211 , and the second section  212  becomes such that the cable  211  approaches (from the upper regions of the figure) a first guiding frame  120  and a second guiding frame  125 . The first guiding frame  120  is designed as a flat arch  120  having a first and a second end, the first end being fastened to the UUV upper surface at a first point, and the second end of the first guiding frame is fastened to the UUV upper surface at a second point, farther aft than the first point, and in close proximity to the cradle, in order to let the cable slip towards the cradle. The first point of guiding frame  120  is preferably identical to a foremost point of same first guiding frame  120 . The foremost point of guiding frame  120  should preferably be arranged fore of second guiding frame  125 , and in height it should preferably be positioned at least half height of least diameter (width) of connector  220 . In shown case approximately 60 millimetres and increasing as further aft and further away from the upper hull surface one gets. This will prevent the connector  220  from jumping over the first guiding frame  120  and escape in the direction of arrow  215 . 
         [0048]    The second guiding frame  125  is a tall arch with a first leg ascending to an apex, and a second leg descending from the apex to a first bend approximately at half of the height of the second guiding frame, and a third leg extending from the first bend approximately horizontally aftwards to a second bend and a third leg then bending downwards and there meeting and being attached to the cradle. 
         [0049]    With this design, as the UUV moves forward, the first section  211  of the cable  211 ,  212 , becomes guided towards the cradle and escapes at an open farther end of the cradle. At a point in time when the second section  212  of the cable  211 ,  212  become smaller and smaller it eventually flips around the foldable capturing mast  105  together with the connector  220 . 
         [0050]    The purpose of the second guiding frame  125  is to, when mast  105  is folded; the cable  211  shall be guided between the first guiding frame  120  and the second guiding frame  125 . If h 2  is made to small or UUV is travelling at a too high speed, the cable may end up above the second guiding frame  125  and the connector  220  will continue in the direction of the arrow  215 . As mentioned above, the dimensioning is a trade-off between permanent hydrodynamic resistance and the probability of successfully catching the cable and its connector at increasing speeds. A foot portion of the second guiding frame  125  that is joining the hull is preferably arranged as far aft as allowed by structural strength and geometry of UUV. This is to prevent the foot portion from disturbing the cable  211  and the connector  220  when it is to be catched by the guiding frames  120 ,  125 . The angle marked C of the second guiding frame  125  in  FIG. 2   c  is preferably as small as possible to prevent the cable from getting stuck on the second guiding frame and instead is forced in between second guiding frame  125  and first guiding frame  120 . However, an uppermost point of the second guiding frame  125  must not be arranged too much forward since it then is necessary to arrange pivoting point  107  more forward, or make main portion  101  shorter. 
         [0051]    The second section of the cable is thus guided through the cradle and when the connector is to pass the cradle it gets catched there because the cradle cross section is wider than the cable but smaller than the connector, and therefore lets the cable  211 ,  212  pass but not the connector  220 . The connector in the catched position in the cradle is given reference number  130 , for illustrative purposes. Subsequently, the catching of the connector  130 ,  220  is detected with suitable means, and the actuator is activated to press connectors together as mentioned above. 
       Considerations on Precise Position of Pivoting Point of Capturing Mast 
       [0052]    The pivoting point  107  is arranged below an upper hull surface of the UUV. It is arranged lengthwise such that, when mast is folded, depending on the length of a main portion  101  of mast  105 , the hook portion  102 ,  103 ,  104 ,  106 , lands in a position such that the cable guided by the hook has a good chance of becoming captured and guided by the guiding frame  125 . The longer the main portion of the mast, the longer forward on the UUV the pivoting point  107  should be arranged. It is also so that it is desired to have as low height of the guiding frame  125 , i.e., the measure h 2  in  FIG. 2   b  should be low in order to keep hydrodynamic drag low. This is also true for the hook, i.e. the measure h 1  of  FIG. 2   b . The height is preferably such that the connector  130 ,  220  is able to pass without getting jammed, and additionally the angle  140  of a first hook bend  102  is less than 90 degrees which entails that the mast in a folded position forces the cable towards the upper surface of the UUV hull. 
         [0053]    Many parameters influence optimal position of pivoting point  107 , length of the mast  105 , and distance sideways between mast  105 /hook  103  and guiding frames  120 ,  125 . Among these parameters are velocity of UUV, and length of cable laid out from mother ship. An arrangement of cable catching elements based on said position of pivoting point, length of mast and sideways distance are restricted by the size of the UUV. It is undesirable to have an arrangement extending outside the length and width of UUV, and it should not extend too much in height in order to reduce hydrodynamic resistance when UUV is not catching cable. Disclosed embodiments have been tested in velocities of 1 to 3 knots with good results using laid out cable lengths of 50 metres and more. It is expected that during regular operation cable lengths of 300 to 800 metres will be used. It is advantageous to have connector  130  attached at an aft or aftmost position, because this will apply the cable drag force to the UUV straight backwards. Since these forces may be in the order of 300 kilograms, it would be difficult to manoeuvre the UUV if the force were applied at another position. 
         [0054]    The guiding frames  120 ,  125  may preferably be of bent pipes, thereby reducing drag. The material could preferably be stainless steel, or of other sea-water resistant and strong material. 
       Rotating Means of First Embodiment 
       [0055]    The submersible vehicle  110  may further comprise rotating guiding means  711 - 713  at linear actuator  750  for rotating second connector  740  into position to be connected to first connector  130 , see  FIGS. 7   a , and  7   b . Suitable detection means  770  may be arranged to sense or detect that the connector  130  is safely in place in the cradle  440  in order to be connected. A pin or other mechanical protruding part  713  is arranged at the first connector  130  to cooperate with a first cam edge  711  or a second cam edge  712  attached to the second connector  740 , such that corresponding contacts of the connectors&#39; ends up straight in front of each other. 
       Second Embodiment 
       [0056]      FIG. 3  shows a side view of an UUV  110  with means according to a second embodiment for capturing a towed cable and connecting to a connector at an end of said cable. A foldable capturing mast  305  is arranged to extend from a top surface of the UUV  110 , and is foldable around a pivoting point  307  (not shown). The pivoting point  307  of capturing mast  305  is preferably arranged at a front third portion of the UUV to allow for portions  301  and  302  to show sufficient length. The length of portion  302  is longer than the connector  420 , preferably at least 50 millimetres longer. The pivoting point is preferably arranged in a central third portion regarding its position in a port-starboard direction. 
         [0057]    The foldable capturing mast  305  can be raised to an upright position as shown in  FIG. 3 , and can be folded by a folding angle  315  to a folded position as is shown in  FIG. 4 . The folding angle is arranged to be around 90 degrees. Folding is arranged to occur when cable forces together with hydrodynamic forces exceeds a certain value, which value could be predetermined or made dependent on UUV speed. The capturing mast comprises a main portion  301  and a hook portion  302  including a hook organ  303 . When there is captured a cable, the foldable capturing mast folds and cable pulling forces, forces the cable to travel towards the hook organ  303  of the foldable capturing mast  305 . The cable  411 ,  412  now can be said to comprise two sections, a first section  411  extending from the mother ship to the hook organ  303  of the foldable capturing mast  305 , and a second section  412  extending from the hook organ  303  of the foldable capturing mast  305  to the cable end with a connector  420 . Due to the movement of the UUV  110  and of the mother ship, and according to hydrodynamics, there are forces pulling the cable section  411 ,  412  obliquely backwards in relation to UUV travelling direction  350 . 
       Flipping of Connector 
       [0058]    The second cable section  412  becomes smaller and smaller as the cable slides through the hook organ  303 , and eventually it comes to the cable end and the connector  420  flips around and gets catched in the hook organ  303 . The detailed design of the hook organ  303  and the connector  420  and how they cooperate will be explained further with reference to  FIG. 5 . The hook organ  303  is preferably shaped as a non-closed ring  303 . The ring  303  has a predetermined inner diameter which is adapted to an outer diameter of a tubular casing  510  of the connector  420  in that a tubular casing  510  of the connector  420  narrowly passes through the hook organ  303  but gets hung up by a spring ring  515 . The tubular casing  510  is provided with a helical groove  505 . There is provided, at ring  303 , an abutment  530  that prevents the tubular casing  510  from rotating and also from translational movement. The connector body  511  is provided with a pin  610  that fits movably in the helical groove  505 . The pin  610  of the connector body and the helical groove  505  of the tubular casing is arranged to cooperate in that the pin  610  of the connector body  511  of connector  420  is guided by the helical grove of the tubular casing  510  such that the connector body  511  begins to turn when the cable section  411  pulls the connector  420  and continues to turn until a keel  520  of the connector body  511  makes contact with rod portion  540  of hook portion  302  of the mast. The connector body  511 , which encompasses the electrical contacts, in this way becomes in a predefined rotational position, when the keel  520  faces downwards. 
       Bringing Connector to Connecting Position 
       [0059]    The spring ring  515  of the tubular casing  510  is devised to give at a predetermined, higher amount of force, and the connector  420  can continue further, guided by a rail  430  for the keel  520 , down to a connecting position, i.e. to the cradle  440 , where the UUV connector is to be connected with the aid of a linear actuator. The rail  430  and the keel  520  are devised such that when the keel has entered the rail, it will not come into a lock before it has moved into the connecting position, i.e. into the cradle  440 . The keel  520  is provided with a derailing guard  521  for preventing the keel  520  from undesirably leaving the rail  430  during the connector&#39;s travel to the cradle  440 . 
         [0060]    Thus, when the connector is catched in the hook organ  303 , this is sensed by first suitable detection means and the hook portion  302  is extended towards the cradle  440 . There are arranged rails  430  for guiding the hook portion with the connector  420  towards the cradle  440 . When the connector is safely in place in the cradle this is detected with second suitable detection means, and an actuator is activated to press connectors together in the same way as mentioned above, establishing an electrical connection between the UUV  110  and the mother ship. 
         [0061]    The connector  420  is preferably provided with a spring ring  515  for re-turning the tubular casing  510  to it original position where it will be ready to repeat its task at a new connection operation.