Method for recovering one or more auvs

Abstract

The invention relates to a method and system for recovering one or more autonomous underwater vehicles (AUVs) (200). The system comprises a submerged autonomous storage station (100) tethered to the seabed (1). The station comprises a collection cable (130) stretched vertically between a tethering device and a submerged float (120), as well as an acoustic signal transmitter (140) for guiding the AUVs. The method comprises a mooring phase during which each AUV (200), at the end of its mission, autonomously reaches the station and uses a mooring device (210) to hook onto the collection cable (130). The AUVs thus remain stored on the cable until a subsequent recovery step, which consists either in lifting the cable with the AUVs, or in raising the AUVs along the cable to the surface.

Description

[0001] "Method for recovering one or more AUVs"

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The present invention relates to the field of fleet management of autonomous underwater vehicles, usually referred to by the acronym AUVs from the English term Autonomous Underwater Vehicle.

[0004] More specifically, the invention relates to the field of AUV recovery at the end of a mission.

[0005] STATE OF THE ART

[0006] For applications involving the collection of information related to environmental fauna and flora, or geophysical measurements, recent solutions are based on the deployment of AUVs.

[0007] An important step involves recovering the AUVs at the end of the mission aboard a ship.

[0008] This recovery phase is often complex and time-consuming.

[0009] Systems for recovering an autonomous underwater vehicle (AUV) from a manned or remotely operated surface vessel are known. Such systems are described in patents FR2904288A1, US20230294798A1 and KR20140127376A.

[0010] Patent EP3213122 describes a deployment and recovery system for fleets of autonomous underwater vehicles (AUVs) used in oil and gas seismic surveys. In addition to the free-floating underwater vehicles, it requires three components: a dedicated vessel, a remotely operated vehicle (ROV), and an underwater elevator. Such a system is complex to operate. It requires highly skilled personnel and, moreover, has high manufacturing and maintenance costs. This complexity in AUV recovery is all the more problematic given that the latest data collection and monitoring solutions rely on AUV fleets, each fleet comprising several, or even dozens, of AUVs.

[0011] One object of the present invention is to address at least some of the limitations of prior solutions.

[0012] Another object of the present invention is to propose a solution to make the recovery of several AUVs easier and at satisfactory costs, in particular by eliminating the need for a ship to be present on site.

[0013] The other objects, features, and advantages of the present invention will become apparent from an examination of the following description and accompanying drawings. It is understood that other advantages may be incorporated.

[0014] SUMMARY

[0015] To achieve this objective, according to one embodiment, a recovery process for at least one autonomous underwater vehicle (AUV) is planned.

[0016] The AUV includes at least one propulsion device, a control device configured to control the propulsion device, an acoustic communication device configured to receive acoustic signals, and a docking device configured to dock the AUV to a storage system.

[0017] The storage system comprising at least one storage station, the storage station comprising:

[0018] • a collection cable for at least one AUV,

[0019] • at least one mooring device configured to moor the collection cable to the seabed, and preferably including at least one ballast intended to rest on the seabed, and

[0020] • at least one float exhibiting positive buoyancy in water and attached to the collection cable so that the collection cable extends between the float and the mooring device.

[0021] The process includes:

[0022] a step of securing at least one AUV to the submerged collection cable of the storage station, during which the securing device equipping the AUV is configured so as to secure the AUV to the collection cable,

[0023] a storage phase during which at least one AUV remains tethered to the collection cable,

[0024] a recovery step of at least one AUV.

[0025] Preferably, the recovery step should include at least one of the following:

[0026] o a lifting stage, at the surface of the water, of the collection cable to which at least one AUV is attached and

[0027] o a step of raising the at least one AUV to the water surface, during which the at least one AUV ascends along the collection cable. During the ascent of the AUV along the collection cable, the AUV remains attached or engaged with the collection cable.

[0028] It is possible to anticipate that multiple AUVs will be attached to the collection cable during the retrieval phase, or that a single AUV will be attached to the collection cable during the retrieval phase. In this case, several storage stations can be installed, each designed to attach one AUV, in order to manage an entire fleet. The invention also applies to the management of a single AUV and provides the same advantages for a fleet as for a single AUV, in terms of decoupling the end of the AUV's mission from the retrieval phase.

[0029] According to another object, a set is planned comprising:

[0030] - an autonomous underwater vehicle (AUV) or a plurality of autonomous underwater vehicles (AUVs), each comprising at least one propulsion device, a control device configured to control the propulsion device, and an acoustic communication device configured to receive acoustic signals,

[0031] - a storage system, preferably autonomous, for one or more autonomous underwater vehicles (AUVs), the storage system comprising at least one storage station.

[0032] At least one storage station includes:

[0033] • a collection cable for the AUV(s),

[0034] • at least one mooring device configured to moor the collection cable to the seabed, and preferably including at least one ballast intended to rest on the seabed, and • at least one float exhibiting positive buoyancy in water and attached to the collection cable such that the collection cable extends between the float and the mooring device, • an acoustic signal transmitter, preferably attached to the cable, and configured to send acoustic signals to the acoustic communication device of the AUV(s). Furthermore, each AUV includes at least one mooring device configured to moor the AUV to the cable. For each AUV, the control device is configured to command the propulsion device, at least based on the acoustic signals received by the AUV, in order to bring the AUV into a mooring configuration with the cable.

[0035] This assembly may have at least one of the following embodiments, which may be exploited and claimed independently of each other:

[0036] According to one embodiment, the AUV includes a retrieval device configured to, from the docking configuration, retract by sliding along the collection cable until it frees itself from the float and reaches the water surface.

[0037] According to one embodiment, the assembly is configured so that the AUVs of the plurality of AUVs are lashed, preferably simultaneously, onto the collection cable, that is to say that at the same instant several AUVs can be lashed and therefore fixed onto the collection cable, the lashing step having been triggered at different or identical instants.

[0038] According to one embodiment, the storage station comprises, in a retracted manner, on the float or on the cable, at least one positive buoyancy element, called a floating element, taken from a surface float and a buoy, the floating element being connected to the float or the cable by a line, during the storage phase of at least one AUV the floating element being retained below the surface of the water, and under the effect of a predetermined event, the storage station is configured to allow the floating element to return to the surface of the water.

[0039] Another object provides a method for storing a plurality of autonomous underwater vehicles (AUVs) on at least one storage station of an assembly as defined above. The method includes a phase of docking the plurality of AUVs to the submerged collection cable of the storage station.

[0040] Another object provides a method for recovering a plurality of autonomous underwater vehicles (AUVs). The recovery method comprises the steps of the storage method defined above and further includes a step of raising the AUVs to the surface. For example, this raising step may include a step of lifting the collection cable to which the plurality of AUVs are attached to the surface of the water. The recovery method may also include a step of lifting the AUVs attached to the collection cable, for example, by a ship or aircraft. The recovery method may further include a step of detaching the AUVs from the collection cable. For another example, this raising step may include a step of raising the AUV(s) to the surface. For this purpose, at least one AUV activates a surfacing device with which it is equipped.This lifting device is, for example, the propulsion device of the AUV or a ballast to regain the surface of the water.

[0041] Thus, unlike existing solutions for recovering an AUV or a fleet of AUVs, the proposed solution involves a collection phase for the AUVs that is entirely separate from the phase of bringing the AUVs aboard a vessel. These two phases become independent, both in terms of timing and the means employed; in particular, the collection phase does not require the presence of a surface vessel. AUV collection and AUV retrieval can therefore be carried out entirely asynchronously. In this respect at least, the invention offers a radically different approach from prior art solutions.

[0042] Furthermore, the collection phase can be carried out in a completely autonomous manner, that is to say without human intervention, therefore without piloting from a ship or from a human-piloted vehicle of the ROV (remotely operated vehicle) type.

[0043] This solution allows for the simple and efficient collection of AUVs at the end of their missions by storing them on the cable. The device thus forms an autonomous AUV storage station. This solution ensures the safe retrieval of AUVs by preventing their dispersal at the end of their missions, for example, due to ocean currents. Furthermore, this solution eliminates the energy consumption of the AUVs while they await retrieval from the station by a surface vessel. A larger portion of the AUVs' energy autonomy can therefore be used for their mission. To retrieve the AUVs aboard a ship or aircraft, it is simply a matter of raising the cable to the surface. This solution is much simpler and more reliable than maintaining a cable from a ship or aircraft.In particular, the heaving motions imposed on the ship by the swell, and therefore transmitted to the cable, make guiding the AUVs and securing them to the cable difficult. Some existing solutions include mechanisms to compensate for these heaving motions, but these mechanisms are expensive and can only be installed on large lifting cranes aboard large ships.

[0044] Furthermore, during the development of the present invention, collecting an entire fleet of AUVs in a basket or cage proved complex. Indeed, unless complex communication and sensor systems are deployed, AUVs frequently collide near the collection basket. These collisions can damage the AUVs or at least cause them to lose their trajectory and overshoot their target. They must then perform complex maneuvers to return to the basket, which is now behind them. During the development of the present invention, synchronizing the AUVs so that their approach maneuvers to the basket are successive and do not generate collisions was considered. This solution proved unsatisfactory in terms of collection time, either for large fleets of AUVs or for applications requiring a rapid collection phase.

[0045] Furthermore, the storage stations according to the invention have a small footprint and low weight. They are therefore easy to store, transport and operate.

[0046] Finally, the storage stations according to the invention result in low construction, operation and maintenance costs because they eliminate the need for many pieces of equipment compared to known solutions.

[0047] According to another object, a set is planned comprising:

[0048] • one or more autonomous underwater vehicles (AUVs), each comprising at least one propulsion device, a control device configured to control the propulsion device, and an acoustic communication device configured to receive acoustic signals,

[0049] • an autonomous storage system for one or more autonomous underwater vehicles (AUVs), the storage system comprising at least one storage station,

[0050] At least one storage station comprising:

[0051] • a collection cable for the AUV(s),

[0052] • at least one mooring device configured to moor the collection cable to the seabed, and preferably including at least one ballast intended to rest on the seabed, and

[0053] • at least one float exhibiting positive buoyancy in water and attached to the collection cable so that the collection cable extends between the float and the mooring device, • an acoustic signal transmitter attached to the collection cable and configured to send acoustic signals to the acoustic communication device of the AUV(s). Each AUV includes at least one mooring device configured to moor the AUV to the cable.

[0054] For each AUV, the control device is configured to command the propulsion device, at least based on acoustic signals received from the transmitter, in order to bring the AUV into a docking configuration with the collection cable.

[0055] The AUV includes a retrieval device configured to, from the docking configuration, ascend by sliding along the collection cable until it frees itself from the float and reaches the water surface.

[0056] According to another object, a storage system for a plurality of autonomous underwater vehicles (AUVs) is envisaged, each comprising at least one propulsion device, a control device configured to control the propulsion device, an acoustic communication device configured to receive acoustic signals, the storage system comprising at least one storage station, the at least one storage station comprising:

[0057] • a cable for collecting AUVs,

[0058] • at least one mooring device configured to moor the collection cable to the seabed, and preferably including at least one ballast intended to rest on the seabed, and • at least one float exhibiting positive buoyancy in water and attached to the collection cable such that the collection cable extends between the float and the mooring device, • an acoustic signal transmitter, attached to the cable, preferably fixed to the cable, and configured to send acoustic signals to the AUVs,

[0059] • a plurality of docking zones, each zone being configured to accommodate one AUV from the plurality of AUVs.

[0060] According to another object, a storage station for a plurality of autonomous underwater vehicles (AUVs) is planned. This storage station can be operated and claimed independently of the objects mentioned previously, in particular independently of the AUVs. The storage station includes at least one AUV collection cable and an acoustic signal transmitter, preferably attached to the cable, and configured to send acoustic signals to the AUVs. All the features subsequently described in the detailed description concerning storage stations are compatible with this object. The storage system does not necessarily include the AUVs.

[0061] In one example, the storage system comprises AUVs. In this case, preferably, each AUV includes at least one lashing device configured to lay the AUV to the cable. For each AUV, the control device is configured to command the propulsion device, at least based on acoustic signals received by the AUV, to bring the AUV into a lashing configuration with the cable. The system is configured so that the AUVs of the plurality of AUVs are lashed, preferably simultaneously, to the collection cable. According to this object, the lashing device configured to lay the collection cable to the seabed is optional. The collection cable can be held in the water by at least one of the following: a buoy floating on the water's surface, a vessel, or an aircraft capable of hovering, such as a helicopter. According to a first option, the cable has a plurality of stops.Preferably, the stops are evenly spaced along the cable. The spacing between two stops forms an anchoring zone for an AUV. Optionally, the distance D150 between two stops, when the cable is positioned in the water, is greater than the length L200 of an AUV.

[0062] This first option can be used regardless of whether the cable has a ballast resting on the seabed. For example, the abutments of the collection cable can be used with a cable whose end is held by an aircraft such as a helicopter or a surface vessel during the AUV mooring and collection phases. Thus, all the features relating to the abutments can be claimed independently of the features relating to the storage station's mooring. All the storage system features described and illustrated above and below are compatible with this embodiment of the collection cable including abutments.

[0063] According to a second option, alternative or combinable with the first option, the lashing device and the cable are configured so that when the collection cable is in contact with the lashing device, a movement of the AUV, preferably backwards, relative to the collection cable triggers the locking of the cable in the lashing device.

[0064] A particularly advantageous feature is that the locking device is entirely passive. For example, it does not include any motorized actuators for locking and unlocking the AUV on the cable. This significantly enhances the device's reliability and lifespan. Furthermore, it greatly simplifies the AUV's design and reduces its cost. For instance, there are no actuators or batteries to power them. This solution is therefore particularly effective for deploying a fleet of numerous AUVs.

[0065] For example, the lashing system includes:

[0066] - a housing with an opening to allow the AUV to bring a section of the cable into the housing by a movement of the AUV oblique to a principal direction in which the cable extends, preferably in a direction perpendicular to a principal direction in which the cable extends,

[0067] - a locking device comprising a locking member, such as a locking finger. The locking member is configured to close the opening and prevent the cable section from exiting the housing under the effect of a movement of the AUV oblique to a main direction in which the cable extends.

[0068] The locking mechanism is elastically articulated on the housing, so as to present: - a locking configuration, in which it bears against a seat of the housing and thus closes the opening of the housing and,

[0069] - an opening configuration, in which it is moved away from the seat, thus allowing access to the accommodation through the opening

[0070] The transition from the locked to the open configuration is achieved by applying a force to the locking mechanism. The AUV is configured so that the cable exerts this force when the AUV moves relative to the cable positioned in contact with it. The locking mechanism is rotationally articulated on the AUV so that it pivots to transition from the locked to the open configuration and vice versa. Preferably, this pivoting occurs around an axis substantially perpendicular to a direction of forward movement of the AUV.

[0071] Preferably this pivoting takes place around an axis substantially parallel to a main direction along which the cable extends when the AUV is attached to the cable.

[0072] Preferably the locking device includes an elastic tab or a spring exerting on the locking member the force tending to keep it pressed against the seat (locking configuration).

[0073] For example, when the AUV is secured to the cable—that is, when the cable is inserted into the locking device and the device is in the locked position—the AUV cannot detach from the cable. Specifically, the AUV cannot detach from the cable by moving laterally or obliquely to the cable's direction. However, the AUV can slide along the cable, for example, under the influence of gravity, either out of the water or in the water.

[0074] In one example, the locking mechanism pivots away from the seat, thus allowing access to the housing through the opening.

[0075] Thus, when the locking device leaves the seat, it allows the cable to pass through the opening, particularly when the AUV moves in a direction oblique to a main direction in which the cable extends, preferably in a direction perpendicular to a main direction in which the cable extends.

[0076] In one example, the AUV is configured so that the locking element is positioned against the cable and the propulsion device generates a force that moves the locking element from its rest position to the position of

[0077] According to one example, the housing is formed by a ring having an opening closed by the locking device.

[0078] In one example, the lashing device forms a hook. In another example, the lashing device forms a carabiner system with a locking gate.

[0079] As an example, each AUV has a nose, a midplane, and two side wings extending on either side of the midplane. The midplane and each side wing can be equipped with at least one tie-down device. The midplane is substantially vertical and contains the direction of travel of the AUV when it moves in a straight line.

[0080] It should be noted that all characteristics relating to the AUV and all characteristics relating to the mooring device can be used independently of the characteristics relating to the collection cable of the storage station, and in particular independently of the characteristics relating to the fact that the cable has a ballast resting on the seabed. Thus, all characteristics relating to the mooring devices can be claimed independently of the characteristics relating to the mooring of the storage station.

[0081] Furthermore, the operation of the lashing device is independent of the presence of stops on the collection cable. All the characteristics of the recovery system described and illustrated above and below are combinable with this embodiment relating to the lashing device.

[0082] According to another object, which can be used and claimed independently of the objects mentioned above, in particular independently of a storage station, an AUV or a plurality of AUVs is provided. All the features that will be described subsequently in the detailed description concerning the AUVs are combinable with this object. In particular, all embodiments concerning the lashing device, its connection to the AUV, and its operation can be used and claimed independently of the storage station. Each AUV includes at least one lashing device configured to be able to latch onto a cable. The lashing device is configured such that contact of the lashing device with the cable or a force exerted by the cable on the lashing device causes the lashing device to latch onto the cable.

[0083] In one example, the lashing device is configured so that lashing the device to the cable is triggered by the AUV moving backward on the cable. In another example, the lashing device is located on a rear portion of the AUV or on at least one side of the AUV. In yet another example, the AUV includes two thrusters, or propulsion devices located on a rear portion of the AUV, and the lashing device is located between the two thrusters. Preferably, the lashing device is located on a midplane of the AUV. Alternatively, the lashing device is configured so that lashing the device to the cable is triggered by the AUV moving forward. In this case, the lashing device is located on a forward portion or on the nose or on at least one side of the AUV.

[0084] BRIEF DESCRIPTION OF THE FIGURES

[0085] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which:

[0086] Figures 1A and 1B schematically represent an example of a storage system according to the invention. In Figure 1A, the AUVs converge towards the storage system. In Figure 1B, the AUVs are attached to the collection cable of the storage system.

[0087] Figure 2 schematically represents an example of an AUV configured to cooperate with the storage system.

[0088] Figure 3A schematically represents a portion of the AUV in Figure 2, illustrating an example of a lashing device.

[0089] Figure 3B shows an enlarged version of the lashing device shown in Figure 3A.

[0090] Figure 3C represents a variant of the lashing device illustrated in Figure 3B.

[0091] Figure 4 schematically represents a variant of the storage system illustrated in Figure 1A.

[0092] Figure 5 schematically and functionally represents an example of a communication relay. Figure 6 schematically represents a storage system comprising several storage stations.

[0093] Figures 7 and 8 schematically represent two other examples of storage systems according to the invention.

[0094] Figure 9 schematically represents a lifting stage of a storage station on board a ship.

[0095] Figure 10A schematically represents, viewed from above, another example of an AUV configured to cooperate with the storage system.

[0096] Figure 10B is a rear view of this AUV illustrated in Figure 10A.

[0097] Figure 10C shows an enlarged version of the AUV lashing device from Figure 10A.

[0098] Figures 11 and 12A and 12B schematically represent examples of lashing devices exhibiting at least one degree of freedom with respect to the body of the AUV.

[0099] Figure 11 schematically represents an example of a pivoting articulated lashing device on the body of the AUV.

[0100] Figures 12A and 12B schematically represent an example of a lashing device that can detach from the body of the AUV and remain attached to it by a flexible link.

[0101] Figure 13 schematically represents an example of a storage station configured so that the surface buoy moves from a retracted configuration below the water surface to a deployed configuration when it is accessible from the water surface.

[0102] Figures 14 and 15 schematically represent other examples of storage stations with AUVs docked and an AUV in the ascent phase.

[0103] Figure 16 schematically represents the storage station illustrated in Figure 15 after the AUVs have been freed from the collection cable and during a phase of recovery of the AUVs by opportunistic vehicles.

[0104] The drawings are given as examples and are not limiting to the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications.

[0105] DETAILED DESCRIPTION OF THE INVENTION

[0106] Before proceeding with a detailed review of embodiments of the invention, optional features that may be used in combination or alternatively are listed below:

[0107] As an example, the AUV or flotilla of AUVs is deployed from a vehicle of opportunity. This vehicle of opportunity could be, for instance, a boat or a navigable drone, or an aircraft such as a flying drone or a helicopter. For example, a flying drone can drop one or more AUVs into the water or deposit them on the water's surface.

[0108] In one example, the storage station is deployed from an opportunistic vehicle, such as a boat, a navigating drone, or an aircraft like a flying drone or helicopter. In another example, the lashing device and cable are configured so that when the collection cable makes contact with the lashing device, movement of the AUV relative to the collection cable triggers the cable to lock into the lashing device. This locking is entirely passive and is automatically activated by the AUV's movement relative to the cable.

[0109] In one example, the lashing device includes a locking member elastically articulated on the AUV, and the lashing device and the cable are configured such that:

[0110] - when the collection cable is in contact with the locking device, a movement of the AUV, forward but also and preferably backward, relative to the collection cable triggers a movement of the locking device to reach an open configuration in which it allows the collection cable to access a housing.

[0111] - when the collection cable has entered the housing, the locking element returns elastically to a rest position, called the locking configuration, in which it prevents the collection cable from exiting the housing.

[0112] Thus, this blocking mechanism is entirely passive. It is therefore particularly reliable and robust.

[0113] According to one example, the locking element is rotationally articulated on the AUV so as to pivot to switch from the locking configuration to the opening configuration and vice versa.

[0114] Preferably, this pivoting is carried out around an axis substantially perpendicular to a straight-line forward direction of the AUV

[0115] Preferably the locking device includes an elastic tab or a spring exerting a force on the locking member tending to maintain it in the locking configuration.

[0116] As an example, the lashing device is configured so that the AUV lashes onto the collection cable by a backward movement of the AUV relative to the cable. A lashing device configured to secure the AUV by a backward movement offers numerous advantages over a forward movement. Indeed, during the development of the present invention, it was found that a lashing device configured to secure the AUV by a backward movement significantly reduces the risk of the lashing device unintentionally lashing the AUV to elements other than the collection cable, such as fishing nets, drifting ropes, or vegetation like kelp, during navigation.

[0117] In one example, the AUV has two propulsion devices positioned on a rear portion of the AUV, preferably symmetrically with respect to a median plane (ZX) of the AUV. The lashing device is positioned between the two propulsion devices. Thus, moving the AUV backward allows the cable to be easily brought into the lashing device between the two propulsion devices.

[0118] In one example, the AUV has two guide surfaces, each extending from the lashing device and configured to guide the AUV relative to the collection cable towards the lashing device during a backward movement of the AUV. These guide surfaces greatly improve the reliability of the lashing step of the incoming cable onto the collection cable. In another example, either in combination with or independently of the guide surfaces, the AUV includes at least one moving part. This moving part is configured to assume a deployed position when the AUV is moving backward and a retracted position when the AUV is moving forward. In the deployed position, the moving part is configured to guide the AUV relative to the collection cable towards the lashing device during a backward movement of the AUV. This moving part significantly facilitates guiding the cable to, or even to, the lashing device.

[0119] As an example, the AUV comprises two movable elements, located on either side of the lashing device and configured to form an angle θ between 45° and 160° when deployed, and an angle θ' between -20° and +20° when retracted. This significantly facilitates cable guidance during the lashing phase when the movable elements are deployed, without significantly increasing the AUV's drag during navigation when the movable elements are deployed.

[0120] For example, the transition from the deployed to the retracted position is entirely achieved by a forward movement of the AUV (X200), and the transition from the retracted to the deployed position is entirely achieved by a backward movement of the AUV (-X200). Thus, the alternating transition from the deployed to the retracted position is completely autonomous, i.e., without piloting, and passive, i.e., without energy.

[0121] According to one example, the AUV includes a sensor configured to identify if the cable is jammed in the lashing device and the AUV is configured to transmit to a remote receiver, via its acoustic communication device, a signal indicating that the cable is jammed in the lashing device.

[0122] In one example, the lashing device is mounted movably on the AUV body, with at least one degree of freedom. This significantly reduces the risk of lashing device failure. In another example, the lashing device is hinged to the AUV by a joint with at least one rotational degree of freedom, such as a pivot joint or a ball joint. Alternatively, or in combination, the lashing device is connected to the AUV by a deformable joint. This could be made of a deformable material such as an elastomer. Alternatively, the lashing device is configured to have two configurations: first, where it is fixed, preferably with no degrees of freedom, to the AUV body; and second, where it is detached from the AUV body, remaining connected only by one or more links, preferably flexible.

[0123] According to one example, the AUV comprises a body having a nose, a rear and at least one side extending from the nose, at least one tie-down device being located on at least one side or the seat, the body of the AUV being shaped so that when the AUV moves forward or preferably backward horizontally and in a straight line and the cable is in contact with the AUV, the cable slides to the tie-down device.

[0124] In one example, the AUV comprises two side members and at least two lashing devices, each side member being equipped with at least one lashing device. Regardless of the direction in which the AUV enters the cable, lashing is thus made simpler and more reliable. In another example, the lashing device and the cable are configured so that, in the lashing configuration, the AUV retains at least one degree of sliding freedom relative to the cable along a principal extension direction Z130 of the cable. More generally, when the AUV is lashed to the collection cable, the lashing device allows the AUV to move along the collection cable. It can also be designed to allow it to rotate around the collection cable. However, the AUV cannot disengage from the cable and move away from it. In another example, the cable includes at least one stop to prevent the AUV from sliding downwards under the effect of its gravity.This allows the AUVs to be equipped with a simple and robust locking mechanism that does not require a perfectly reliable clamping force. Under the influence of gravity, whether in the water or out of the water when the cable is brought to the surface, the AUVs slide along the cable, stopped by at least one stop.

[0125] In one example, the collection cable includes a plurality of stops distributed along its length, the spacing between two stops forming an anchoring zone for an AUV. In another example, the distance D150 separating two stops, when the cable is under tension, is greater than the length L200 of an AUV, the length of an AUV being measured along the direction of its forward movement, preferably D150 > 2 * L200. In yet another example, the stops are formed by rings, regularly spaced along the length of the collection cable.

[0126] As an example, the collection cable includes visual coding elements. These visual coding elements comprise or form a sequence of several segments of a specific length. The sequence is configured to allow the AUV to optically assess its distance from the collection cable and / or to optically identify one or more docking zones assigned to the AUV. Preferably, the visual coding elements are taken from light sources and / or retroluminescent elements and / or reflective elements.

[0127] According to one example, the AUV includes at least one optical sensor and the control device is configured to command the propulsion device, at least based on acoustic signals received from the transmitter and optical data provided by the optical sensor, to bring the AUV into the docking configuration with the cable.

[0128] In one example, the method further includes a step of lifting the collection cable, to which the plurality of AUVs are attached, onto a ship or aircraft, and a step of retrieving the AUVs attached to the cable and detaching them from the cable. In another example, the AUV includes a proximity sensor, selected from among an optical sensor, an acoustic wave sensor, and an electric field sensor. Preferably, the collection cable includes at least one lashing zone configured to interact with this proximity sensor so that the AUV locates the lashing zone. The proximity sensor is configured to detect the presence of the cable and provide data to the control device so that the latter guides the AUV to the cable and to the lashing zones.

[0129] In one example, the storage station includes, retracted on the float or cable, at least one positive buoyancy element, referred to as a floating element, chosen from a surface float and a buoy. The floating element is connected to the float or cable by a tether. During the storage phase of the at least one AUV, the floating element is retained below the water surface, and upon a predetermined event, the storage station is configured to allow the floating element to return to the surface. In one example, the storage station includes a retention device that engages to release the tether and / or the floating element. Preferably, the retention device includes an electromechanical actuator that releases a retention hook retaining the floating element or tether, or that releases a blade that cuts a component such as a wire retaining the floating element or tether.According to an example, the predetermined event is taken from:

[0130] the reception by the storage station of a signal, preferably acoustic, for example from a ship or aircraft or AUV,

[0131] a predetermined date and time for the end of the mission,

[0132] a predetermined end-of-mission period,

[0133] the dissolution of a salt tablet.

[0134] For example, when this event occurs, the floating element and its tether are released to rise to the surface due to their positive buoyancy. For example, the retention device includes an electromechanical actuator that releases a retention hook holding the floating element or tether, or that releases a blade that cuts a tether holding the floating element or tether. This release can also be triggered by a salt pellet that compresses a spring in the retention device.

[0135] In another example, the process further includes a step of raising the AUV(s) to the water surface. For this, at least one AUV is equipped with a retrieval device that it activates to return to the water's surface. This retrieval device is, for example, formed by or includes the propulsion system. Alternatively, the retrieval device includes a ballast. Preferably, if there are several AUVs on the same storage station, each activates its retrieval device. Alternatively, only the deepest AUV activates its retrieval device. It then comes into contact with the other AUVs, which it pushes and slides along the collection cable to bring them to the surface. This allows only one AUV to be equipped with a ballast or to have sufficient energy to perform this retrieval. In one embodiment, when an event occurs, the AUV activates its retrieval device. It rises to the surface along the cable.The event can be chosen from those listed above:

[0136] reception by the AUV of a signal, preferably acoustic, for example from a ship or aircraft,

[0137] a predetermined date and time for the end of the mission,

[0138] a predetermined end-of-mission period.

[0139] The storage station and the AUV are preferably configured so that as the AUV ascends the cable, the float can pass through the AUV. Thus, when the AUV activates its propulsion system, it initially remains attached to the collection cable and can then disengage once it reaches the end of the cable. To achieve this, the docking device can include an opening through which the cable slides as the AUV ascends. The cross-section of this opening and the cross-section of the float are configured so that the float passes through this opening, allowing the AUV to disengage from the float, and possibly even from the cable, and ascend to the surface. For example, during the ascent, the AUV rises vertically past the float but remains attached to a tether.Thus, the AUV(s) remain on the surface, making them easy to recover by the recovery vehicle, while preventing their dispersal even in the presence of currents or waves, as they remain attached to the cable. This solution allows for extremely rapid and reliable recovery of the AUV(s), even from a recovery vehicle with limited lifting capacity, such as an inflatable boat or a drone.

[0140] For example, the float has a vertically elongated shape. The dimension of the float, taken vertically, when the float is submerged is X times greater than the maximum dimension of its cross-section taken in a horizontal plane, with preferably X > 3, preferably X > 5, preferably X > 10.

[0141] Preferably the float comprises several portions, separated from each other by folding zones and shaped to facilitate folding or winding of the float, the folding zones being for example formed by spaces separating the portions or by section restrictions.

[0142] Advantageously, the deepest end of the float has a shape configured to facilitate the guidance of the AUV as it ascends along the float, for example a cone or truncated cone shape.

[0143] In one example, the stops are configured to prevent the AUVs from sliding downwards under the influence of gravity. The AUVs and the storage station are configured so that when the AUV is docked and in storage or standby mode, it has negative buoyancy. The stop prevents the AUV from sliding down the cable under the influence of gravity.

[0144] When the AUV is in the upward phase, it passes beyond the stops, preferably with the latter passing through the AUV.

[0145] To achieve this, it is planned that:

[0146] When the AUV is secured and in storage or standby mode, it has a first inclination, within a first range of inclinations relative to the horizontal, in which the stop cannot slide relative to the AUV so as to prevent the AUV from descending lower than the stop located below the AUV. When the AUV is being raised, its raising device positions its inclination within a second range of inclinations relative to the horizontal, in which the AUV's securing device has a shape complementary to that of the stop, allowing one to slide within the other, so as to allow the AUV to pass over the stop located above the AUV.

[0147] In one example, the process further includes, prior to the mooring phase, a step of installing the storage system, the installation step including the immersion of the storage station. In another example, the device is configured so that the float is located below the surface of the water. In yet another example, the device is configured so that the cable extends in the water in a substantially vertical direction.

[0148] The storage station can also be described as a recovery station, in that it enables essential steps to be taken in the recovery of AUVs.

[0149] In one example, the cable has a first and a second end; the first, or lower, end is attached to the mooring device, and the second, or upper, end is attached to the float. Alternatively, the device is configured so that the cable extends in the water in a substantially horizontal direction. In this case, the storage station preferably includes several floats.

[0150] According to one example, the lashing device includes at least one weight, preferably directly attached to the cable, for example at a so-called lower end of the cable. Alternatively, the lashing device includes at least one connecting element linking the weight to the cable, the connecting element preferably being a rope or a chain.

[0151] According to one example, the mooring system includes several connecting elements and several ballasts intended to rest on the seabed, each ballast being connected to the cable by at least one connecting element.

[0152] According to one example, the storage station comprises at least one floating element taken from among a surface float 180 and a buoy connected by a cable to the cable or the float, as well as a retention device, the storage station having:

[0153] a retracted configuration in which the retention device keeps the cable of the floating element retracted, for example in the form of a reel, so that the floating element is intended to be kept below the surface of the water,

[0154] a deployed configuration in which the retention device allows the floating element's cable to release so that the floating element returns to the water's surface due to its positive buoyancy, while remaining connected to the 130 cable or float by the cable.

[0155] The line can be an extension of the cable, beyond the submerged float. In this case, it has the same characteristics as the collection cable and differs in that it connects the submerged float to the surface. Alternatively, and preferably, it is a rope or cable with a smaller cross-section than the collection cable.

[0156] The terms phase and stage are considered equivalent.

[0157] All the described embodiments apply equally to the docking of a plurality of AUVs to the same storage station, and to the docking of a single AUV to a storage station. An example of a 1000 storage system with 200 AUVs will now be described with reference to Figures 1A and 1B.

[0158] The system comprises at least one AUV storage station 100. Each storage station 100 includes a seabed mooring device 1, at least one float 120 with positive buoyancy in water, and a cable, referred to as the collection cable 130, connected to the mooring device and the float 120. The storage station 100 is configured so that the mooring device 110 is fixed relative to the seabed 1. Thus, the storage station 100 has at least one end fixed relative to the seabed 1. The collection cable 130, the mooring device, and the float 120 are configured so that the cable 130 is submerged when positioned at a distance from the seabed. In particular, the length of the cable 130 is adjusted so that the float 120 remains submerged regardless of wave height and tide. This 120 float is also referred to as the submerged float or main float.It is configured to hold the 130 cable vertically.

[0159] Preferably, and as illustrated in the example of figures 1A and 1B, the cable 130 extends in a substantially vertical direction and at least oblique to the horizontal.

[0160] The storage station 100 further includes at least one acoustic signal transmitter 140. This transmitter is attached to the collection cable 130. Preferably, it is fixed to the cable 130. Alternatively, it is fixed to the float or to another element connected to the cable 130.

[0161] This system is configured to store AUVs, referenced in Figures 200a, 200b, and 200c. In practice, the invention proves particularly effective when the AUVs form a fleet of several dozen, or even more than one hundred. The AUVs in the same fleet may move independently or in a coordinated manner, for example, as a swarm of coordinated AUVs.

[0162] In a perfectly standard manner, each AUV 200 includes at least:

[0163] - a propulsion device 202, comprising one or more thrusters and enabling it to move and steer underwater,

[0164] - an acoustic communication device 203 configured to receive acoustic signals from the transmitter 140 of the storage station 100. For example, this acoustic communication device 203 includes at least two hydrophones, preferably three or more hydrophones, enabling the localization of a source of acoustic signals such as the transmitter 140 of the collection cable 130 by triangulation.

[0165] - an AUV 200 control module which controls and commands the propulsion device 202 and processes information including signals received from the acoustic communication device 203.

[0166] The AUV 200 is configured to control its propulsion device 202, in particular according to the acoustic signals from the transmitter 140, so as to move towards the storage station 100 and its cable 130. Figure 1A illustrates the AUVs 200a, 200b, 200c moving towards the cable.

[0167] The AUV 200 also includes at least one lashing device configured to lay the AUV 200 to the cable of storage station 100.

[0168] The 130 cable has several lashing zones, either separate or continuous, allowing multiple AUV 200s to be lashed to the same cable. In the example shown, the 130 cable has four lashing zones, 1301-1304. In practice, this number will be much higher and could include more than ten or even more than fifty lashing zones.

[0169] The cable, as well as the storage station 100, are not attached to a surface vessel. Thus, the AUVs 200 can dock with the collection cable 130, for example, when the control module determines a mission end. A mission end is determined, for example, when at least one of the following events occurs: an AUV 200 mission is completed, the AUV 200 receives a mission end signal, the AUV 200 has an energy level below a given threshold, a mission time has elapsed, a mission end time has elapsed, or the AUV 200 malfunctions.

[0170] Figure 1B illustrates the AUVs 200a, 200b, 200c attached to the cable.

[0171] When several AUVs 200 are attached to cable 130, it is possible to raise cable 310 to the surface, for example from a surface vessel or an aircraft such as a helicopter. A recovery step can then be carried out to detach the AUVs 200s attached to the cable. This step can be performed inside the vessel, aircraft, or on land.

[0172] The recovery of AUVs, in clusters and by this 100 storage station, presents many advantages.

[0173] The storage and collection phase is conducted entirely autonomously by the AUVs 200, meaning without any human operator intervention. Specifically, this storage and collection phase does not require the intervention of a surface vessel or an ROV.

[0174] Thus, AUVs 200 can be collected at storage station 100 without any restrictions regarding surface vessel access. For example, AUVs 200 can reach storage station 100 even when weather conditions prevent approach by a surface vessel.

[0175] Furthermore, the AUVs 200 can remain tethered to the 130 cable for as long as necessary for storage before retrieval. During this entire tethering period, the AUVs 200 do not disperse due to factors such as ocean currents. They also do not need to rest on the seabed, which could lead to its degradation, or even damage to the AUVs themselves. A particularly advantageous feature is that the AUVs 200 consume no energy to maintain their position before retrieval. Moreover, this solution eliminates the need for an AUV retrieval basket, the drawbacks of which were previously mentioned.

[0176] Furthermore, since storage station 100 is located on the seabed, collection operations are not affected by wave height. The immersion depth measurement of the AUV is practically unaffected by wave height, provided its immersion depth exceeds half the wave wavelength.

[0177] Furthermore, the 1000 storage system allows for the rapid retrieval of an entire cluster of AUVs, stored along the entire length of the cable at different levels. This rapid retrieval can be highly advantageous. In particular, since the 200 AUVs can be distributed along the entire length of the cable, they can dock simultaneously without the risk of collisions that could derail them from their docking trajectory.

[0178] Furthermore, the cable offers rotational symmetry adapted to changes in current direction. It allows for 360° connection of 200 AUVs. In addition, the storage stations have a small footprint and are lightweight, making them easy to store and transport.

[0179] Furthermore, bringing the cable to the surface from a surface vessel can be done using conventional cable or net lifting equipment. The 1000 storage system is therefore particularly simple to operate.

[0180] Furthermore, multiple stations can be deployed and operated simultaneously. This solution is therefore particularly well-suited for large fleets of 200 AUVs. Figure 6 illustrates an embodiment in which the 1000 storage system comprises a plurality of storage stations. In this schematic drawing, there are four of them, 100a-100d.

[0181] It also presents particularly low implementation, operation and maintenance costs since it makes it possible to do without many complex pieces of equipment essential to known solutions, such as anti-ramming recovery mechanisms.

[0182] Preferably, the mooring device is configured to moor the AUV 200 to the cable while maintaining at least one degree of sliding freedom for the AUV 200 along a principal Z130 direction of cable extension. In the example illustrated in Figures 1A and 1B, this Z130 direction is substantially vertical, particularly in the absence of marine currents. This Z130 direction can be curved under the effect of marine currents, which apply force to the cable and the subsurface float 120. It is also possible to allow the AUV 200 to rotate around the collection cable when moored to it. However, the AUV cannot disengage from the cable and move away from it.

[0183] For example, the lashing device can form a ring inside which the cable can slide. Conversely, when the AUV 200 moves laterally in the Z130 direction, the lashing device prevents the AUV 200 from separating from the cable.

[0184] 150 stops on the collection cable 130

[0185] Optionally, and as shown in Figures 1A and 1B, the cable is fitted with stops 150 configured to limit the movement of the lashing device and therefore of the AUV 200 along the cable 130. This prevents the AUV 200s from piling up on top of each other when the cable 130 is pulled, or under the effect of gravity, which could damage them.

[0186] Thus, it can be anticipated that when the AUV 200 is attached to the cable 130, it retains at least one degree of movement along the cable 130, for example, limited sliding, due to gravity and the stops 150. Alternatively, it can be anticipated that the attachment device eliminates any possibility of the AUV 200 sliding along the cable 130. In this case, the stops are not necessary, except to define attachment zones to ensure proper spacing of the AUV 200s from each other.

[0187] The stops 150, for example, take the form of rings fixed to the cable 130. If the lashing device forms a ring, then the stops 150 have a minimum cross-section, measured along a plane perpendicular to the direction Z130, greater than a maximum cross-section of the opening defined by the ring's opening. Thus, in this embodiment, the stops 150 define lashing zones 1301-1304 that are distinct from one another on the cable 130. A lashing zone is defined by the cable cross-section between two stops 150.

[0188] Preferably, the 1000 storage system is configured so that only one AUV 200 is docked at a given docking point. This prevents two adjacent AUV 200s from colliding in swell conditions, especially during cable retrieval.

[0189] Preferably, the 150 stops are placed on the cable at regular intervals. For example, this interval is 2 meters.

[0190] Figure 1B illustrates the distance D150 between two stops 150 and the length L200 of an AUV. In this example in Figure 1B, D150 < L200. Thus, two adjacent AUVs 200 can touch.

[0191] In the example shown in Figure 4, D150 > L200. Therefore, two adjacent AUV 200 units cannot touch. This prevents them from colliding due to currents, swell during lifting, and during cable handling during the lifting phase. Preferably, D150 > 1.2 * L200. Preferably, D150 > 1.3 * L200.

[0192] It should be noted that all the features relating to the presence of stops 150 on the collection cable 130 can be used independently of whether the cable has a ballast resting on the seabed 1. For example, the stops 150 of the collection cable 130 can be used with a cable one end of which is held by a vehicle 700, for example an aircraft such as a helicopter or a surface vessel, during the AUV mooring and collection phases, as illustrated in Figure 9. Thus, all the features relating to the stops 150 can be claimed independently of the features relating to the mooring of the storage station 100. All the features of the storage system 1000 described and illustrated above and below are compatible with the embodiment comprising a collection cable 130 equipped with stops 150.

[0193] lashing device

[0194] An example of a lashing device will now be described with reference to figures 2 and 3A to 3C.

[0195] It can be anticipated that the lashing will be carried out by moving the AUV in a -X200 direction of retreat or in an X200 direction of advance. These two embodiments are illustrated in Figures 3A to 3C. The embodiment with lashing by a retreating movement will now be described in detail.

[0196] According to one example, the lashing device 210 includes a housing 240 having an opening 241 to allow the AUV 200 to bring a section of the cable 130 into the housing 240 by a movement of the AUV 200 in a direction perpendicular to the main direction Z130 of the cable.

[0197] This housing 240 can form a groove. It can form a closed or open ring.

[0198] The lashing device 210 also includes a locking device comprising a locking member 230, such as a locking finger, configured to close the opening 241 and prevent the cable section 130 from coming out of the housing 240, for example under the effect of a movement of the AUV 200 oblique to the main direction Z130 in which the cable extends.

[0199] Preferably, the locking member 230 is elastically articulated on the housing, so as to present:

[0200] - a blocking configuration, in which it rests against a seat 222 of the housing 240 and thus closes the opening 241 of the housing 240 and,

[0201] - an opening configuration, in which it is away from seat 222 thus allowing access to housing 240 through opening 241.

[0202] The AUV 200 is configured so that the transition from the blocking configuration to the opening configuration is achieved under the effect of a stress applied to the blocking member 230. The blocking member 230 is preferably articulated in rotation so as to pivot to switch from the blocking configuration to the opening configuration and vice versa.

[0203] The locking mechanism 230 pivots away from the seat 222, thus allowing access to the housing 240 through the opening 241. Therefore, when the locking mechanism 230 moves away from the seat 222, it allows the cable to pass through the opening 241, particularly when the AUV 200 moves towards the cable in a direction perpendicular to the Z130 direction. The lashing device 210 thus forms a carabiner system with a locking gate.

[0204] When the cable is raised out of the water to retrieve the AUVs 200, the AUVs 200 are detached from the cable by applying force to the locking mechanism 230, typically a manual force exerted by one or more fingers of an operator, so as to move the locking mechanism 230 from the locked position to the open position. In the open position, the cable is removed from the housing of the lashing device 210, and the AUV 200 is then detached from the cable 130. The cable is exited by passing it through the opening 241. Therefore, it is not necessary to slide the AUV 200 to one end of the cable to remove it.

[0205] Preferably, the pivoting of the locking member 230 takes place around an axis 231 substantially perpendicular to a forward direction X200 of the AUV. This forward direction X200 corresponds to a straight-line forward movement of the AUV.

[0206] Preferably, this pivoting occurs around an axis 231 substantially parallel to the main direction Z130 along which the cable extends at the point where the AUV 200 is attached to the cable. As illustrated in the example in Figure 3B, the locking member 230 has a first end 231 by which it is articulated on a portion 221 integral with the AUV 200 and a second end 232 configured to cooperate with seat 222 in order to at least partially close the opening 241. Preferably, the lashing device 210 is configured so that the locking member 230 comes into contact with seat 222. This allows the opening 241 to be completely closed.

[0207] Alternatively, the locking member 230, in its locked configuration, is not in contact with the seat 222. It is located at a distance from the seat. In this case, the locking member 230 is positioned sufficiently close to the seat 222 so that the distance between the locking member 230 and the seat 222 does not allow the cable to pass through. Preferably, the locking device includes an elastic tab or a spring that exerts a force on the locking member 230 to keep it pressed against the seat. This elastic element is not shown. Alternatively, this elastic element can be formed by the locking member 230 itself.

[0208] The AUV 200 is configured so as to position the locking member 230 against the cable 130 and so that the propulsion device 202 generates a force enabling the locking member 230 to move from the rest position to the position of

[0209] The 210 lashing device is entirely passive. For example, it does not include any actuators, such as motorized ones, to lock and unlock the AUV 200 on the cable. This significantly increases the device's reliability and lifespan. Furthermore, it greatly simplifies the design of the AUV 200 and reduces its cost. For instance, there are no actuators or batteries to power them. This solution is therefore particularly effective for deploying a fleet of numerous AUV 200s.

[0210] When the AUV 200 is attached to the cable, i.e. when the cable is inserted into the locking device and the latter is in the locking configuration, then the AUV 200 cannot detach from the cable.

[0211] In particular, the AUV 200 cannot detach from the cable by transverse or oblique movement to the main Z130 direction of the cable. However, the AUV 200 can slide along the cable.

[0212] Preferably, and as illustrated in Figures 3A and 3B, the lashing device 210 is located on one side of the AUV. Thus, when the AUV 200 makes contact with the cable and moves backward in the direction -X200, the cable moves closer to the lashing device 210. Preferably, the shell of the AUV 200 forms a guiding surface for the AUV 200 as it slides along the cable. This guiding surface may extend over a portion of its side 20111, 2012 and up to the lashing device 210. In Figure 3A, the reference numerals 130', 130”, 130'” illustrate the successive positions of the cable relative to the body 1 of the AUV as the latter moves backward. This sliding occurs in a direction substantially parallel to the recoil direction -X200 of the AUV 200 and substantially perpendicular to the main direction Z130 along which the cable extends at the point of contact with the AUV

[0213] The progressive recoil of the AUV thus brings the lashing device 210 closer to the cable, until the latter is locked in the lashing device 210. More precisely, the recoil of the AUV causes the cable to come into contact with the locking member 230 and to rotate the latter so as to enter the opening 241.

[0214] Preferably, the AUV 200 has a curved surface that flares out towards the lashing device 210, so as to easily guide the cable towards the lashing device 210.

[0215] Thus, from the moment the AUV 200 moves back significantly towards the cable, the latter serves as a guide for the drone until the cable is inserted into the 210 lashing device.

[0216] Preferably, the first end 221 of the locking member 230 is located closer to the rear portion 260 of the AUV 200 than to the seat 222, relative to the AUV's reverse direction -X200. Thus, when the AUV 200 moves backward, the cable's contact with the release finger 230 causes the latter to pivot and the second end 232 of the member to move away from its seat 222. The locking member 230 then pivots to release the opening 241 of the housing 240.

[0217] As illustrated in Figure 3B, the lashing device 210 and the AUV body 1 are configured to form a cable guide 242 before the cable is inserted into the housing 240. This guide 242 is located downstream of the opening 241 relative to the direction of travel of the AUV along its principal forward direction X200. Therefore, this guide 242 is located upstream of the opening 241 relative to the direction of travel of the AUV along its reverse direction -X200. This guide 242 has a guide portion 244, an upstream part of which defines an entry opening 243 through which the cable enters. The guide portion 244 has a decreasing cross-section between the opening 243 and the opening 241 of the housing 240. This cross-section 245 is illustrated in Figure 3B.Thus, as the AUV moves backward in the direction -X200 opposite to its direction of advance X200, once the cable has reached the mouth 243, it is guided by the guide portion 244 to the entrance 241 of the housing 240.

[0218] The guidance device 242 can be defined by a wall formed by an extension 220 of the lashing device 210 defining the housing 240.

[0219] In the example illustrated in Figure 3B, the locking member 230 is rotationally articulated on this extension 220. The seat 222 is supported by a side 2011, 2012 of the AUV

[0220] A variant is illustrated in figure 3C. In this variant, the locking member 230 articulated on a side 2011, 2012 of the AUV The seat 222 is carried by an extension 220 of the lashing device 210 defining the housing 240.

[0221] Figure 3B illustrates two examples of lashing. References 130a' to 130a'" on the one hand, and 130b' to 130b" on the other, illustrate the successive positions over time of the AUV relative to the cable as the AUV moves backward.

[0222] References 130a' to 130a'”” correspond to cases in which the AUV 200 makes contact with the cable from its rear portion 260, the AUV 200 then sliding relative to the cable along its side 2011.

[0223] In position 130a'”” the cable is in contact with the locking member 230 and exerts on the latter a force which moves the second end 232 away from the locking member 230 relative to the seat 222.

[0224] In the example illustrated previously, the lashing device is configured to secure the AUV by a backward movement of the AUV. This backward movement is along the -X200 direction. This embodiment has the advantage of considerably reducing the risk of the lashing device unintentionally lashing the AUV to elements other than the collection cable during navigation, such as fishing nets, drifting ropes, or vegetation like kelp. Alternatively, the lashing device can be configured to secure the AUV by a forward movement of the AUV along the X200 direction. This embodiment is also illustrated in Figures 3A to 3C. The front of the AUV then corresponds to reference 206 and not to reference 260, which illustrated the sill or the rear portion 260 of the AUV. All the features of these two embodiments are combinable and interchangeable.

[0225] Alternatively, the blocking device is positioned at another location on the AUV, for example at a mid-position on the AUV, for example on the nose of the AUV

[0226] With reference to Figures 10A to 10C, another embodiment of an AUV will now be described. All the previously described characteristics of the AUV and the storage system remain perfectly valid for this embodiment and are therefore compatible with those of this new embodiment.

[0227] In this embodiment, the lashing device 210 is located on a rear portion 260 of the AUV. Thus, when the latter makes a backward movement, its rear portion 260 comes into contact with the cable 130 to lay the latter down.

[0228] In the optional example described, the AUV 200 has two propulsion devices 202a and 202b located on a rear section 260. These two propulsion devices 202a and 202b are situated on either side of a median plane ZX of the AUV, which is vertical when the AUV is moving horizontally. Advantageously, the docking device 210 is located between the two propulsion devices 202a and 202b.

[0229] The AUV 200 includes at least one guide surface 270 configured to guide the cable 130 to the lashing device 210 and the locking member 230 as the AUV reverses. During the development of the present invention, it became apparent that the maneuverability of an AUV 200 during a reversing phase can be limited. The presence of the guide surfaces 270 greatly facilitates the entry of the cable 130 into the lashing device 210. Preferably, each guide surface 270 extends from the opening 241 of the lashing device 210.

[0230] Preferably, the AUV 200 comprises two guide surfaces 270 symmetrically arranged with respect to the median plane passing through the lashing device 210. Preferably, the lashing device is located on the median plane ZX of the AUV 200. As illustrated in figures 10A and 10C, these two guide surfaces 270 then form a "V" or a portion of a "V" in a horizontal plane XY, when the AUV moves horizontally, typically along the X direction.

[0231] Optionally and advantageously, the lashing device 210 includes a movable element 250 configured to guide the cable 130 to the guide surface 270 or to the locking element 230 as the AUV moves backward. The movable element 250 is configured to adopt: - a first position 250a', known as retracted, when the AUV moves forward X200. In this position, the movable element 250 can extend primarily in a direction parallel to the direction of travel X200 of the AUV or parallel to the median axis ZX of the AUV. In this position, the movable element 250 is thus positioned in the wake of the AUV, which reduces its friction during the forward movement of the AUV 200.

[0232] - a second position 250a, called deployed, when the AUV moves backward -X200. In this position, the movable part 250 extends in an oblique direction relative to the direction of advance X200 of the AUV. It has a first end 251 fixed to the AUV and a free end 252. In this position 250a, the second end 252 is further from the median axis ZX of the AUV than the first end 251. This allows it to form a guiding angle to guide the cable 130.

[0233] Advantageously, the transition from the deployed position 250a to the retracted position 250b occurs automatically under the influence of water force. The water tends to return the moving part 250 to the retracted position 250b when the AUV 200 moves forward X200 and tends to bring the moving part 250 into the deployed position 250a when the AUV moves backward. The deployment and retraction of the moving part 250 are performed in a completely passive and automatic manner, without energy or control, which increases the reliability and robustness of the AUV 200.

[0234] In the illustrated example, the AUV 200 comprises two movable parts 250, each of which has a deployed position 250a, 250a' and a retracted position 250b, 250b'. These two movable parts form a portion of a "V". If the AUV has guide surfaces 270, then advantageously, in their deployed position 250b, 250b, the movable parts extend the guide surfaces. The collection cable 130 can thus be guided over a greater distance. This makes it possible to compensate very effectively for any angular offset that the AUV may have during its recoil movement to secure the cable 130.

[0235] Figures 10A and 10C illustrate the different positions of cable 130 during the AUV's recoil along the -X200 direction. References 130a' illustrate successive positions of the AUV 200 in which the cable 130 is not in contact with the AUV. Reference 130a” illustrates a position of the AUV 200 in which the cable 130 is in contact with the moving part 250 in its deployed position 250a. References 130a'” and 130”” illustrate successive positions of the AUV 200 in which the cable 130 is guided by the guide surface 270. Reference 130a’”” illustrates a position of the AUV 200 in which the cable 130 has entered the housing 240 of the lashing device 210 and is locked in place by the locking part 230.

[0236] According to one embodiment, when the two movable parts 250 are in the deployed position 250a, 250b, they together form an angular sector a greater than 45° and preferably between 60° and 160° and preferably between 70° and 160°, which allows very efficient guidance of the cable even when at the beginning of the maneuver the median plane ZX of the AUV 200 is not perfectly aligned with the axis Z130 of the collection cable 130. In the example illustrated in figures 10A and 10C, this angle a is 90°.

[0237] When the two moving parts 250 are in the retracted position 250a', 250b', together they form an angular sector a less than 45° and preferably less than 20° and preferably between -20° and +20°, and preferably between -10° and +10°, which reduces their friction when the AUV 200 moves forward. In the example shown in figures 10A and 10C, in the retracted position, this angle a' is 0°.

[0238] In one example, the moving part 250 is elastically deformable. It is configured so that its elasticity allows it to adopt the deployed position 250a when the AUV moves backward, for example, under the effect of water resistance when the inlet moves backward. Its elasticity allows it to return to the retracted position 250b when the AUV moves forward X200. In this example, the moving part 250 can be rigidly fixed to the AUV, without a joint.

[0239] Alternatively, the movable part 250 can be articulated on the AUV, for example with a rotational joint to move from the deployed position 250a to the retracted position 250b and vice versa. This rotational joint can be performed around a vertical axis Z when the AUV moves in a horizontal plane XY.

[0240] Finally, according to another embodiment, the mobile part 250 can be articulated on the AUV 200 while exhibiting a flexibility allowing its elastic deformation.

[0241] The presence of a movable element 250 is not limited to a lashing device 210 positioned on the rear portion 260 of the AUV. Lashing devices 210 positioned on other portions of the AUV can also be equipped with a movable element 250. Thus, in Figure 10A, a lashing device 210 is shown on a side 2012 of the AUV 210 and includes a movable element 250 for guiding the cable 130. This lashing device 210 can, for example, be identical to those illustrated and described with reference to Figures 3A and 3B. A backward movement of the AUV brings the movable element 250 into the deployed position 250a, and a forward movement of the AUV automatically returns the movable element 250 to the retracted position 250a'.

[0242] It should be noted that, according to an embodiment not illustrated, the lashing device 210 includes a movable member 250 to guide the cable 130 to the lashing device 210, but does not include a fixed guiding surface 270.

[0243] In the example illustrated in Figure 10A to 10C, the AUV 200 includes two additional propulsion devices 2021, 2021, configured to move the AUV vertically when the AUV 200 is moving in a horizontal plane ZX.

[0244] Similarly, the AUV 200 can include a lashing sensor configured to detect when the AUV 200 is lashed onto the cable. For example, this sensor could be configured to detect movement of the locking device 230. This movement could correspond to a movement away from its seat 222 followed by a movement back towards its seat 222. It could, for example, be a magnetic or optical sensor. Alternatively, the sensor equipping the AUV 200 could detect the presence of the cable, for example, by means of an optical sensor. This optical sensor could detect the presence of the cable inside the housing 240. Alternatively, the cable 130 could have an element to which a sensor of the AUV 200 is magnetically sensitive when the cable is positioned in the housing 240. This element could be carried by a sheath or a core of the cable 130.

[0245] Optionally, the AUV 200 can also be equipped with an acoustic signal transmitter to convey the cable locking status. Preferably, the docking sensor transmits the data it captures to the AUV control module, which can then transfer data related to the docking of the AUV 200 to the storage station 100 or any other remote sub-assembly 400 (an example of a remote sub-assembly 400 will be detailed later), etc.

[0246] According to one embodiment, it can be provided that the lashing device 210 is not fixed to the body 201 of the AUV, i.e., fixed without any degree of freedom from the body 201. Thus, it can be provided that the lashing device 210 has at least one degree of freedom with respect to the body 201 of the AUV 200.

[0247] This has the advantage of reducing the risk of damage to the AUV during the retrieval of the collection cable 130, to which the AUVs are attached. When the AUVs are retrieved by pulling the collection cable 130, the cable is under considerable tension due to the weight of the multiple attached AUVs. During the development of the present invention, it was found that forces, primarily generated by the weight of the AUV 200 and by wave motion when the AUV is near the surface, are concentrated on the lashing device 210. These forces can manifest, for example, as a torque exerted on the lashing device 210.These efforts can lead to the breakage of the latter or to a degradation of the body of the AUV. By providing at least degree of freedom between the lashing device 210 and the body 201 of the AUV, the latter can be placed in a position which limits or even eliminates the forces exerted between the lashing device 210 and the body of the AUV 201.

[0248] For example, it can be foreseen that the 210 tie-down device is mounted movably on the AUV 200, with at least one degree of mobility.

[0249] In one example, the lashing device 210 is articulated to the AUV 200 by a joint comprising at least one rotational degree of freedom, such as a pivot joint or a ball joint. Figure 11 illustrates an example in which the lashing device 210 has a base 280 comprising a pivot joint 281, 282 allowing rotation about an axis A1. This axis A1 is, for example, parallel to a transverse direction Y of the AUV 200. Portion 281 is fixed to the body of the AUV 201, and portion 282 is fixed, by this rotation, to the locking member 230.

[0250] Alternatively or in combination with the pivot joint 281, 282, it can be provided that the lashing device 210 has a pivot joint 283 configured to allow rotation around an axis A2 different from A1. A2 is for example parallel to the Z direction which corresponds to the vertical when the AUV 200 moves horizontally.

[0251] This method of implementation can equally well equip a drone which provides for docking by a recoil movement or a forward movement.

[0252] When the lashing device 210 is located on the rear portion 260 of the AUV 200, for example as in the example of Figures 10A-10C, it can be provided that the housing 240 and the locking device 230 are articulated on a pivot joint allowing rotation around an axis parallel to the Y direction relative to the body 201.

[0253] In another embodiment, the base 280 is provided to form a deformable joint. This base 280 thus allows displacement of the housing 240 and the locking member 230 relative to the body 201. Preferably, the base 280 allows deformation in at least two directions. For example, the base 280 comprises or is made of an elastomer. According to another embodiment, illustrated in Figures 12A and 12B, the lashing device 210 can be completely detached from the body 201 of the AUV 200. When the AUV 200 is not lashed to the cable 130, the lashing device 210 is attached to the body 201 of the AUV 200. This situation is illustrated in Figure 12A. When the AUV 200 is lashed to the cable 130, the lashing device 210 detaches from the body 201 of the AUV 200. This situation is illustrated in Figure 12B.In this configuration, the lashing device 210 remains connected to the AUV by a link 287, preferably flexible, such as a cable or rope. The length of this link 287 allows the body 201 of the AUV 200 to adopt the position imposed upon it, for example by gravity, a current, or swell, while the lashing device 110 remains firmly attached to the cable 130 and possibly to the stop 150 of the cable 130.

[0254] Preferably, this disconnection takes place automatically, for example when the lashing sensor detects the presence of cable 130 in housing 240.

[0255] According to the non-limiting example shown, the lashing device 210 includes a base 281 that is fixed, preferably fully fixed (i.e., without any degrees of freedom), to the body 201 when the lashing device 210 is attached to the body 201. For example, and only optionally, the body 201 has a cavity 290 shaped to house the base 280. The AUV 200 includes a locking device configured to lock the base 280 inside the cavity 290. This locking can be magnetic. Alternatively, a mechanical locking mechanism may be provided. For example, one of the body 201 and the base 280 includes an actuator 284 configured to move a bolt 285 which cooperates with a strike plate 286 carried by the other of the body 201 and the base 280. In the illustrated example, the actuator and the bolt are carried by the base 280 and the strike plate is formed by the body 201.The link 287 is folded inside the base 280 or inside the body 201. This link has one end 288 attached to the base 280 and the other end 289 attached to the body 201.

[0256] When cable 130 is secured to the lashing device 210, the locking mechanism is configured to unlock the base 280 from the cavity 290. The lashing device 210 therefore remains secured to cable 130. The AUV body 201 can detach from the base 280 while remaining connected to it and thus to cable 130 via the link 287. The AUV 200 therefore remains secured to the collection cable 130 via the link 287 and the lashing device 210. Note that the cavity 290 is optional and that the entire preceding description is perfectly valid even without a cavity 290 housing the base 280.

[0257] It should be noted that all the features relating to the lashing device 210 can be used independently of whether the cable has a ballast resting on the seabed 1. For example, the lashing device 210 can be used with a cable one end of which is held by an aircraft such as a helicopter or a surface vessel during the lashing and collection phases of AUVs. Thus, all the features relating to the lashing devices can be claimed independently of the features relating to the lashing of the storage station 100. Furthermore, the operation of the lashing device 210 is independent of the presence of stops 150 on the collection cable 130.

[0258] All the features of the 1000 storage system described and illustrated above and below are compatible with this embodiment of the 210 lashing device. Other sub-assemblies: In addition to the storage station(s), the 1000 storage system may include one or more of the following optional sub-assemblies:

[0259] - A device for determining ocean currents such as tables, a drifting buoy, or a Loch Doppler.

[0260] - A communication relay having a first communication channel using underwater acoustic signals and a second communication channel using radio signals.

[0261] - An autonomous or remotely operated unmanned boat, usually referred to as an SUV (Surface Unmanned Vehicle). The SUV is equipped with an acoustic signal communication channel compatible with said relay.

[0262] - Additional components configured for the deployment of the 1000 storage system at a given time, before or after the mission. These external components include, for example: a non-dedicated vessel, a satellite positioning system (GPS, Galileo, Glonass, Compass, etc.),

[0263] The following paragraphs specify optional characteristics that the various components of the 1000 storage system may have.

[0264] Collection or storage station

[0265] In addition to the mooring device 110, the float 120, the collection cable 130, and the acoustic signal transmitter 140, the autonomous collection station 100 may include the following optional elements. These elements are preferably positioned from the bottom 1 towards the surface when the storage station 100 is deployed:

[0266] - A buoy 170, for example, connected to the subsurface float 120 by a simple rope. This buoy 170 can serve as a signaling device for surface vessels or aircraft. It can then display a flag or pennant 172, or even a light. This makes it easier to identify the position of the storage station 100. Alternatively, or in combination, this buoy 170 can include a radio frequency communication device with remote communication devices 400. Also alternatively, or in combination, this buoy 170 can include a communication device 175 using acoustic signals. This allows communication with AUVs 200 or collection stations 100. Advantageously, the buoy 170 includes a radio frequency communication device, such as a repeater 500.The radio frequency communication device and a communication device 175 using acoustic signals thus allow the transfer to the AUVs 200 of information or instructions received from remote communication devices 400 located out of the water or on the surface, or the transmission to the latter of information received from the AUVs 200. For example, the buoy 170 is connected to the storage station 100 by a link 176 such as a rope or a cable.

[0267] - A surface float 180 attached to the buoy 170 by a positive buoyancy rope. This allows, for example, easier recovery of the main float 120 and the collection cable 130. For example, the float 180 is connected to the buoy 170 or to the storage station 100 by a link 181 such as a cable or rope. There may only be one of the following: buoy 170 and float 180.

[0268] - an anchorage. The anchorage is configured to stabilize the mooring of storage station 100 to the seabed 1. The anchorage can be an element sealed into the seabed, for example, a concrete structure anchored in a rocky bottom. The anchorage can also be an element sealed into a structure, for example, fixed to the seabed, such as a platform or a wind turbine base. The anchorage can be an anchor 111 and its chain 111'. The anchor 111 is, for example, connected to the ballast 110 or the cable 130.

[0269] - at least one light source 160. This optional light source is configured to illuminate at least certain areas of the cable. This facilitates the optical guidance of the AUVs 200 to the cable and their docking to it when light conditions are low, typically at great depths. It is preferably attached to the cable 130. For this purpose, at least one of the following light sources can be provided for the storage station 100: battery-powered lights such as LEDs (light-emitting lamps) or light sticks, typically chemically activated. Preferably, the guidance light sources are attached between two cable stops 150 or to the stops 150. Alternatively, each light source 160 is formed by a stop. This allows the AUVs to identify each of the docking areas even more precisely.

[0270] As an example, the 130 collection cable includes visual coding elements. These elements comprise or form a sequence of several segments of a specific length. This sequence is configured to allow the AUV to perform at least one of the following two functions:

[0271] - to allow the AUV to assess its distance to the 130 collection cable. This allows it to more precisely identify its anchoring zone.

[0272] - to allow the AUV to optically identify one or more assigned docking zones. It is indeed possible to designate certain AUVs to dock only in specific docking zones, corresponding, for example, to an upper section of the cable. This will allow for the easy retrieval on a ship of a group of AUVs that need to be recovered more frequently than another group, or for concentrating the AUVs to be retrieved in docking zones near the surface.

[0273] In one example, the visual coding elements are the light sources 160. These can be luminous rings or strips placed along the cable 130, for example, along the same anchoring zone. Alternatively, the visual coding elements are retroluminescent or light-reflecting elements. The light can be supplied by sources placed along the cable 130.

[0274] Alternatively, the light source is carried by the AUV 200 and the 130 cable is equipped with retroluminescent segments. In both cases, the sequence can be an alternation of dark and light segments, retroluminescent or not, or even of different colors arranged in a specific way. Combined, the 130 collection cable can be designed to have one or more light sources for one or more anchoring zones, and the AUV can also carry a light source to illuminate the 130 cable.

[0275] AUV

[0276] Examples of the AUV 200 are shown in Figures 2 and 10A-10C. In addition to the propulsion unit 202, the acoustic communication unit 203, the control module, and the optional docking device 210, the AUV 200 may include one or more of the following optional components. These components may be integrated into a shell of the AUV body 201:

[0277] - a source of electrical energy,

[0278] - a control and command device,

[0279] - a benchmark of attitude and direction

[0280] - at least one pressure sensor,

[0281] - A proximity sensor, configured to detect the presence of the cable and provide data to the control device so that the latter guides the AUV 200 towards the cable and, more specifically, towards the anchoring zones. The first phase, based on the AUV receiving signals emitted by the beacons carried by the storage station 100, allows guidance when the AUV is several meters, or even tens, hundreds, or kilometers away from the cable. The second phase, based on the use of the proximity sensor, allows guidance when the AUV is less than 4 meters, or even less than 2 meters, from the cable. The proximity sensor is configured to perform optical, acoustic, or electrical detection of the cable 130.

[0282] Optical detection. According to a first embodiment, the proximity sensor comprises at least one optical sensor, for example a camera 204, 205, associated with an image processing unit. Thus, in this case, the control device takes into account acoustic and optical signals to guide the AUV 200 and bring it into contact with the cable for docking. Preferably, the control device takes into account the acoustic signals in the first phase of approaching the storage station 100, and then, in the second phase, takes into account the optical data from the proximity sensor to dock with the cable 130. During this second phase, the control device preferably also takes into account the acoustic signals emitted by the transmitter 140 of the storage station 100.To this end, it can be provided that the collection cable 130 includes, at least at one or more anchoring points 1301-1304, visual patterns, for example, as previously indicated, a succession of shapes and / or colors that facilitate the detection and location of the cable 130, or even light sources. This embodiment with an optical sensor allows for particular discretion, especially with regard to sonar operated by third parties. In the example illustrated in Figure 2, the optical sensor includes at least one camera, and preferably a so-called front camera 205 configured to capture images located in front of the AUV 200 and a so-called vertical camera 204 configured to capture images located below the AUV 200. Whether or not the collection cable 130 includes one or more light sources 160, it can be provided that the AUV includes an onboard light source.It can thus project light onto the cable to facilitate the optical guidance of the AUV 200 on the cable 130 during the docking phase. This light source is preferably positioned to illuminate the rear of the AUV 200 if the latter is configured to dock with the cable 130 using a recoil movement (-X200), as illustrated in Figure 10B. This light source is preferably positioned to illuminate the front of the AUV 200, as illustrated in Figure 2, if the latter is configured to dock with the cable 130 using a forward movement (X200).

[0283] Acoustic detection. Alternatively, or in combination with an optical sensor, the AUV 200 proximity sensor can be equipped with an acoustic wave localization device, typically an active sonar. In this case, it comprises an acoustic wave emitter and a receiver for the waves it has emitted and which have been reflected by surrounding objects, typically the collection cable 130. For this purpose, the collection cable 130 can be provided with a reflective material, at least at one or more of its attachment points 1301-1304, that reflects acoustic waves particularly well. For example, this could be a material incorporating air bubbles, such as a porous material, for example, foam-based or gel-based. Preferably, the acoustically reflective material is located at the attachment point 1301-1304.Thus, in this embodiment with an acoustic sensor, during the first approach phase, the AUV 200 simply listens to the signals emitted by the storage station 100. During the second approach phase, the AUV 200 begins emitting acoustic signals for reflection by the storage station. Preferably, the same acoustic device is used for both phases. This embodiment with an acoustic sensor allows for high positioning accuracy relative to the cable, even under conditions of poor optical visibility, for example, when the water is turbid. Therefore, it can be useful to equip a single AUV 200 with at least one optical sensor and at least one acoustic sensor.

[0284] Electrical detection. Alternatively, or in combination with an optical or acoustic sensor, the AUV 200 proximity sensor can be equipped with a localization device that detects an electric field. For this purpose, the collection cable 130 is electrified at least at one or more of the anchoring points 1301-1304. For example, cable 130 may include an electrical cable powered by a battery or connected to an electrical grid. Thus, in this embodiment, during the first approach phase, the AUV listens for signals emitted by the storage station. During the second approach phase, the AUV detects the electric field generated by cable 130 in order to locate it. This embodiment with an electric field sensor allows for high positioning accuracy relative to the cable, even in poor visibility conditions, for example, when the water is turbid.Thus, it may be useful to equip the same AUV with at least one optical sensor and at least one electric field sensor.

[0285] The AUV includes a proximity sensor, taken from among an optical sensor, an acoustic wave sensor and an electric field sensor, and the collection cable includes at least one docking zone configured to react with this proximity sensor.

[0286] The proximity sensor is configured to detect the presence of the cable and provide data to the control device so that the latter guides the AUV 200 towards the cable and, more specifically, towards the anchoring zones. The system is configured so that, in a first phase, based on the AUV's reception of acoustic signals emitted by the beacons carried by the storage station 100, it provides guidance when the AUV is several meters, or even tens, hundreds, or kilometers away from the cable. The second phase, based on the use of the proximity sensor, provides guidance when the AUV is less than 4 meters, or even less than 2 meters, from the cable. The proximity sensor is configured to perform optical, acoustic, or electrical detection of the cable 130.

[0287] Communication relay

[0288] Optionally, the 1000 storage system includes a 500 communication relay. This relay is schematically illustrated in Figures 1A, 1B, and 2. Preferably, this relay is integrated into the buoy 170. It comprises a body 501 on or within which at least some of the following elements are positioned:

[0289] - a submarine communication channel using 502 acoustic signals,

[0290] - a 503 surface communication module using radio signals,

[0291] - a 504 radiolocation module, for example via satellite (GPS etc.),

[0292] - a 505 processing unit,

[0293] - a source of electrical energy 506.

[0294] Optionally, the 1000 storage system includes a 300 SUV that integrates the aforementioned 500 communication relay and its own propulsion and guidance system. Example of a recovery process

[0295] An example of a recovery process will now be described.

[0296] Preparation and launching of the 200 AUVs

[0297] Prior to the immersion of the AUVs 200, the operator records in the memory of the processing units of each AUV 200 at least some of the following information: - The X and Y coordinates, in an absolute reference frame, of the point where the AUV 200 must remain while awaiting rendezvous with the storage station 100 assigned to it,

[0298] - The stationary immersion instruction awaits the acoustic signal enabling the connection to the storage station

[0299] - The estimated time of assembly,

[0300] - The immersion approach instruction to the storage station, which differs for each AUV, for the purpose of attaching it to the cable,

[0301] - The immersion depth of the acoustic emitter of storage station 100 and the characteristics of its acoustic signals: for example recurrence, frequency and waveform.

[0302] Then a flotilla of AUVs 200 is put into the water to conduct a mission, for example, reconnaissance of the seabed in a defined area preferably in an absolute reference frame, that is to say with known geographical coordinates.

[0303] The AUV 200, or flotilla of AUVs 200s, is deployed from a vehicle of opportunity. This vehicle of opportunity could be, for example, a boat or a navigable drone, or an aircraft such as a flying drone or a helicopter. For example, a flying drone can drop one or more AUVs 200s into the water or deposit them on the water's surface.

[0304] Preparation and setup of one or more stations

[0305] One or more autonomous storage stations for 100 AUVs (Automated Unmanned Vehicles) are carried aboard an opportunistic vehicle. For example, a flying drone can drop one or more storage stations into the water or deposit them on the water's surface. This can be the same opportunistic vehicle that drops the AUVs or a different one. The opportunistic vehicle that deposits the storage station(s) can be a boat or a navigable drone, or an aircraft such as a flying drone or a helicopter. Before the start of the rendezvous operations, the boat rendezvouses with each mooring point of the stations, whose coordinates are known in an absolute reference frame.

[0306] Preferably, the mooring coordinates are calculated so that the AUVs 200s reach their assigned station at the scheduled time facing the current.

[0307] The storage station(s) 100 are deployed. They are, for example, launched from the opportunity vehicle. Preferably, the cable lengths of the storage stations 100 are adjusted so that the subsurface float 120 remains permanently submerged regardless of wave height and tide.

[0308] Rallying of the 200 AUVs from the storage stations

[0309] 1. When the AUV needs to return to the storage station 100, it determines the direction of the acoustic transmitter 140 carried by the station by exploiting the receiving capabilities of its acoustic communication device 203 preferably by measuring the phase difference of the signals received between at least three hydrophones.

[0310] 2. As it approaches cable 130 from station 100, at a certain point, the AUV activates its proximity sensor. If it is an optical sensor, the image processing unit of the optical sensor, preferably its onboard camera 205, detects the presence of cable 130, whether or not it is equipped with a light source 160, and then communicates to the computer of its control module the angular correction to be applied to the heading of the AUV 200 so that it moves directly towards cable 130 at the set immersion depth. The same applies if the proximity sensor is:

[0311] - an active sonar, carried by the AUV and which directs the latter by emitting acoustic signals reflected by the 130 cable or,

[0312] - an electric field sensor that allows the detection of an electric field generated by the 130 cable.

[0313] At the moment of collision between the AUV 200 and the cable, an impact occurs. The cable then begins to slide along the port side 2011 or starboard side 2012 of the AUV, positioning the cable within the field of vision of the optical sensors. As described previously with reference to the optional variants illustrated in Figures 3B and 3C, the AUV 200 can be guided by the guiding device 242 to the housing 240 of the lashing device 210, which preferably forms a groove. Upon contact with the elastically articulated locking member 230, the cable enters the bottom of the housing 240. Once the constricting opening 241 has been passed, the locking member 230 returns to its initial locking configuration and prevents the cable 130 from exiting the housing 240. The AUV 200 is thus permanently lashed to the cable 130.

[0314] 4. The AUV 200's propulsion system is then deactivated to limit its electrical consumption. Preferably, the AUV 200 exhibits negative buoyancy in fresh or salt water. Under gravity, it then slides downwards along the cable until it encounters a stop, for example, a ballast or a locking ring.

[0315] The rallying operations of all AUVs 200 continue according to the sequence of steps 1 to 3 described above.

[0316] Awaiting the vessel of opportunity for the replenishment of the storage stations

[0317] Once all 200 AUVs have reached the storage station(s), the entire storage system (1000) enters a standby mode, also known as the storage configuration, awaiting the arrival of the recovery vehicle (700) which will retrieve the storage stations (100) one after the other. The recovery vehicle (700) is, for example, a ship, as illustrated in Figure 9. It can also be an aircraft with a high lifting capacity, such as a helicopter or a drone, as illustrated in Figure 16. As mentioned previously, a particularly advantageous feature is that this standby phase is completely separate from the AUV deployment and recovery phases. During this phase, the 200 AUV(s) remain docked to the storage station (100).

[0318] AUV recovery and possibly recovery from the storage station

[0319] According to a first embodiment, the lifting of the storage stations 100 is similar to the hauling of lobster pots onto a fishing vessel. It can be done manually or using specific handling equipment 701 (cranes, hydraulic winches, pulleys, A-frame gantry cranes, etc.), for example, carried by a ship or a structure such as a platform, or even by aircraft. An example of lifting carried out by a ship is illustrated in Figure 9.

[0320] For this purpose, preferably the surface float 180 and / or the buoy 170 remain accessible on the surface of the water, preferably from the release point of the storage station 100. This makes it easier to locate the cable 130 as well as to retrieve the cable 130.

[0321] According to a first variant, the storage station 100 is configured to be fully raised above the seabed to recover the AUV(s) 200. This is the case, for example, if the storage station 100 itself needs to be recovered. The ballast 110 and the anchor 111 (if any) are then to be raised to the surface. The length L111' of the chain 111', extended by a line connecting the ballast 110 to the anchor 111, is chosen to allow the unit to be raised to the surface of the mooring area while maintaining the anchor's position relative to the seabed. For example, this length L11T is designed to be greater than or equal to the water depth at the anchor 111, or even twice the water depth. This embodiment is illustrated in Figure 9. Typically, the mooring area of ​​the storage station 100 is located between 1.5 and 6 meters from the seabed 1, and the water height separating the seabed 1 from the surface can be greater than 50 or even several hundred meters.More generally, if there are several mooring areas to accommodate multiple AUVs 200, the main 120 float can be located less than 30, 20, or even 10 meters from the seabed, depending on the number and size of the AUVs 200. If there is only one mooring area to accommodate a single AUV 200, the main 120 float is preferably located less than 10 meters from the seabed, typically around 4 meters.

[0322] According to another variant, no surface float 180 or buoy 170 is present on the surface before the recovery stage. This offers advantages in terms of discretion. Furthermore, it prevents third parties from seizing the storage station 100 to which one or more AUVs are moored. In addition, it prevents the surface current or swell exerted on the surface float 180 or buoy 170 from putting excessive stress on the cable 130 and damaging or displacing it.

[0323] For this purpose, the storage station 100 is designed to include, in a retracted configuration, at least one of the following: the surface float 180 and / or the buoy 170, attached to the float 120 or the cable 130. Thus, during the AUV navigation, rendezvous, and storage phases, the surface float 180 and / or the buoy 170 are kept below the water's surface. For example, the cable 181 and / or 176 attached to the cable 130 or the float 120 is designed to be retracted or coiled, for example, into a reel. Upon a predetermined event, the storage station 100 is configured to allow the surface float 180 and / or the buoy 170 to return to the surface. For this purpose, storage station 100 includes a retention device which engages to release the cable 181, 176.

[0324] The predetermined event is, for example, chosen from:

[0325] the reception by storage station 100 of a signal, preferably acoustic, for example from a ship or an aircraft or an AUV 200,

[0326] a predetermined date and time for the end of the mission,

[0327] a predetermined end-of-mission duration, the dissolution of a salt tablet.

[0328] For example, when this event occurs, the surface float 180 and its cable 181 and / or the buoy 170 and its cable 176 are released to rise to the surface due to their positive buoyancy. For example, the retention device includes an electromechanical actuator that releases a retention hook holding the surface float 180 and / or the buoy 170 or their cables 181, 176, or that releases a blade that cuts a cable holding the surface float 180 and / or the buoy 170 or their cables 181, 176. This release can also be triggered by a salt pellet that compresses a spring in the retention device. When the salt pellet dissolves in water, the spring extends and actuates the retention device, including, for example, the blade or the retention hook. Figure 13 illustrates this variant.The retention device preferably includes a device 182, such as a cage, box, or reel, containing the retracted line 181 and the surface float 180 below the water's surface. References 180', 180”, 180'”, respectively illustrate the surface float 180 in the following stages: retracted configuration, beginning of ascent to the surface, and reaching the water's surface. Naturally, this could refer to the surface float 180 and / or the buoy 170, as illustrated in Figure 13 by references 1807170'. Only one AUV 200 is shown in this figure; there could, of course, be several.

[0329] According to yet another possibility, the AUV(s) 200 are configured to return to the surface after the storage phase. This embodiment is compatible with the previous embodiment in which the surface float 180 and / or the buoy 170 are kept submerged before being raised to the surface.

[0330] To do this, when an event occurs, the AUV activates its onboard ascent device. It then releases its tether to cable 130 and ascends to the surface. The event can be one of those listed above:

[0331] reception by the AUV 200 of a signal, preferably acoustic, for example from a ship or aircraft,

[0332] a predetermined date and time for the end of the mission,

[0333] a predetermined end-of-mission period.

[0334] The ascent device is for example formed by the propulsion device of the AUV 200. Alternatively or in combination the ascent device may include a ballast, for example with positive buoyancy if the AUV has negative buoyancy.

[0335] Storage station 100 and AUV 200 are preferably configured so that when the AUV travels up the cable, float 120 can pass through AUV 200.

[0336] Thus, when the AUV activates its propulsion device, it can disengage from the collection cable 130. The AUV 200 can then return to the surface of the sea to be recovered by an opportunity vehicle 700, such as a ship or an aircraft, for example a drone.

[0337] Figure 14 illustrates this method of recovering the AUV 200. In this figure, the same AUV 200 can be seen transitioning from a storage phase, supported by a stop 150 due to gravity, to a retrieval phase during which the AUV 200 ascends along the storage station, initially remaining engaged with the collection cable 130, then with the submerged float 180, before disengaging from these to return to the water's surface. This embodiment applies equally to a storage station receiving a single AUV 200 or to a storage station receiving multiple AUV 200s.

[0338] Once the AUV reaches the water's surface, its recovery can be carried out in a particularly simple manner. For example, by hand from a vessel, even a small one such as a small inflatable boat. The AUV can also be recovered by an aircraft 700. In this case, the aircraft 700 can be equipped with a recovery net 711 for the AUV 200 or with a hook 712 attached to the aircraft 700's body by a cable 710, as illustrated in Figure 16.

[0339] For this purpose, it can be provided that the lashing device 210 includes an opening 241 inside which the cable 130 slides when the AUV 200 is raised along the cable 130. The section of this opening and the section of the float 120 are configured so that the float 120 passes through this opening 241, thus allowing the AUV 200 to disengage from the cable 130 and the float 120 and rise to the surface.

[0340] For example, the float 120 is expected to have a vertically elongated shape, as illustrated in Figures 14-16. Its vertical direction when submerged is X times greater than the maximum dimension of its cross-section in a horizontal plane, preferably with X > 3, preferably X > 5, preferably X > 10. Preferably, the float 120 comprises several portions 121a-121f. These portions 121a-121f are separated from each other by folding zones 122 shaped to facilitate folding or winding the float 120, for example, around a pulley or drum. As illustrated in Figures 14 and 15, the portions 121a-121f comprise a positive buoyancy material, for example, foam or an air-filled volume, and the folding zones 122 are formed by spaces separating the portions 121a-121f.Alternatively, portions 121a-121f comprise a positive buoyancy material, for example, foam, and the folding zones 122 are formed by cross-sectional restrictions in this material. Thus, the float 120 comprises, alternately, portions 121a-121f having a first cross-section and portions 122 having a second cross-section smaller than the first. The cross-sections are taken along a horizontal plane.

[0341] The AUV 200, after passing through the float 120, can either be completely released from the storage station or, as illustrated in Figure 16, attached to a cable 181, 176, one end of which is fixed to the float 120 or to the cable 130. This cable 181 rises to the surface, preventing the AUV 200 from dispersing after its ascent, even in the presence of currents or waves. This solution allows for extremely rapid and reliable recovery of the AUV 200(s), even from a low-lifting, opportunistic vehicle 700 such as an inflatable boat or a drone.

[0342] Advantageously, the deepest end of the float 120 has a shape configured to facilitate the guidance of the AUV 200 as it ascends along the float 120. Typically, the end 121f of the float 120 has a flared shape whose cross-section increases as it approaches the water surface. Preferably, the portions 12a-121e of the float 120 located above the end portion 121f have an identical cross-section S121a. The upper end 121fsup of the portion 121f has a cross-section S121fsup identical to the cross-section S121a. The lower end 121finf of portion 121f has a cross-section S121tint that is smaller than the cross-section S121fsup, as illustrated in Figure 14. Portion 121f, for example, has a cone or truncated cone shape. This greatly facilitates the guidance of the AUV 200s as they ascend along the float 200.

[0343] This embodiment can be envisaged even when there are stops 150 separating several storage zones 1301-1304. As previously indicated, the stops 150 are configured to stop the downward sliding of the AUVs 200 under the effect of their gravity.

[0344] The AUVs 200 and the storage station 100 are configured such that:

[0345] When the AUV is secured and in storage or standby mode, it exhibits negative buoyancy. The stop 150 prevents the AUV 200 from sliding down the cable under the effect of gravity.

[0346] when the AUV is in the upward phase, it passes beyond the 150 stops, the latter passing through the AUV.

[0347] Advantageously, the ability to pass through a stop or to be stopped by it depends on the relative inclination of the AUV 200 with respect to the stop 150. This inclination is controlled by the AUV during ascent and is determined passively, by gravity, when the ascent device is not activated.

[0348] To achieve this, it is planned that:

[0349] When the AUV is secured and in storage or waiting mode, it exhibits an initial trim, within a first range of inclinations relative to the horizontal. For example, under the effect of its negative buoyancy and gravity, the AUV 200 is expected to tend to tilt relative to the horizontal. The positioning of the lashing device relative to the AUV's center of gravity tends to cause the AUV to be tilted when it is against a stop 150. Its trim is then not horizontal, or is inclined at least 20° relative to the horizontal. The stop 150 cannot then pass through the cross-section of the opening 241 in the lashing device. The respective cross-sections of the stop 150 and the opening 241 of the lashing device are chosen accordingly. This inclination is illustrated in figures 14 and 15 by the AUV 200 which are in stops on the stops 150. This inclination is represented by the angle a.When the AUV is in the lifting phase, its lifting mechanism positions its attitude within a second range of inclinations relative to the horizontal. For example, the AUV 200 positions itself so that its attitude is horizontal or at an inclination of, for example, + or 20° relative to the horizontal. In this inclination, the lashing device has a shape complementary to that of the 150 stop, allowing one to slide within the other. Typically, the stop can pass through the opening 241. Thus, it can be predicted that when the AUV is attached to the cable, it retains at least one degree of freedom relative to the cable to move along the cable 130, for example, according to a sliding motion limited by gravity and the stops 150. This inclination of the AUVs 200 is illustrated in figures 14 and 15 by the AUVs 200 which are moving up along the float 120. In this example, the angle a becomes zero.

[0350] This embodiment allows several AUVs 200 to be stored on the same storage station 100, and several storage areas 1301-1304 to be defined, in particular to avoid collisions between AUVs, while allowing the recovery of AUVs on the surface without having to raise the storage station 100.

[0351] Preferably, if there are several AUVs 200 on the same storage station 100, each activates its own lifting device. Alternatively, only the deepest AUV 200 activates its lifting device. It then makes contact with the other AUVs, pushing and sliding them along the collection cable 130 to bring them to the surface. This allows only one AUV to be equipped with a ballast or to have sufficient power to perform this lifting operation.

[0352] Use of the communication relay

[0353] According to an optional variant, the implementation of the 500 communication relay can be used for one or more of the following steps:

[0354] - Remotely monitor the progress of the rendezvous stages. For this purpose, the 500 communication repeater integrated into the 170 buoy or in an SUV 300 uses its acoustic communication channel 502 to receive coded signals from the 200 AUVs, representing their progress, such as immersion depth and distance from the cable. Once decoded, this information is transmitted using the 503 radio communication channel and received on land or aboard a vessel.

[0355] - Guide the recovery vehicle 700, for example a boat, to the storage station(s) 100. To facilitate the guidance of the opportunity vehicle 700 to the storage station 100 to be retrieved, the radio communication channel of repeater 503 is used to transmit its GPS coordinates to the vehicle 700, which then navigates to the received position. - Assist the guidance of the AUV 200 to the cable 130 by measuring the distance.

[0356] In the previously described case, AUV 200 only knows the direction of approach to cable 130. Knowing the horizontal distance between it and the cable can be useful, particularly for slowing down on approach for a smooth engagement or for detecting when it is moving away, which would necessitate a U-turn. To this end, the clock offset of the acoustic transmitter located on the cable at storage station 100 relative to the GPS time reference must be measured and this information transmitted to the AUVs 200. Subsequently, the difference between the TOA (Time of Arrival) of reception and the transmission time, multiplied by the average speed of sound in water, gives the distance between AUV 200 and transmitter 140.This distance is then corrected for the difference in immersion between the AUV 200, known using its pressure sensor, and that of the transmitter 140 measured along the cable 130 to obtain a distance projected in the horizontal plane.

[0357] Determination of the clock offset of the acoustic signal transmitter The following paragraphs propose a method for determining the clock offset of the acoustic signal transmitter 140 carried by the storage station 100. The communication relay 500 is integrated into the body of the buoy 170.

[0358] Acoustic communication channel 175 detects the signal from the acoustic transmitter 140 of storage station 100. It deduces a measured TOA, Tm, in the GPS time reference frame, the GPS time signal being delivered by the GPS receiver with an accuracy better than 10 A -5 seconds.

[0359] It is then possible to calculate the emission time, Te, of said signal by applying the correction related to the propagation time of the signal in water. This propagation time is equal to the oblique distance, Do, separating the emitter 140 from the receiver of acoustic signals divided by the speed of sound in water.

[0360] The distance in the horizontal plane, Dh, is equal to the length of the link between the sub-surface float 120 and the buoy 170 possibly corrected for the immersion depth of the float 120.

[0361] The vertical distance, Dv, is equal to the difference in immersion between the hydrophone of the acoustic receiver 502 of buoy 170 and that of the transmitter 140.

[0362] The average speed of sound in water, Cm, is determined by knowing the salinity and temperature of the water.

[0363] Do and Te are calculated using the following formulas:

[0364] Do = Square root ( (Dh)A 2 + (Dv) A 2)

[0365] Te=Tm - ( Do / Cm )

[0366] Subsequently, the time difference between Te and the second round of the immediately lower satellite geolocation system will determine the clock offset of storage station 100. This value will be transmitted to the AUVs 200 using acoustic communication channel 502 of relay 500.

[0367] Variants

[0368] Several variations of the previous examples will now be described. All these variations can be combined with the previously described features and with each other. Use of the SUV

[0369] In this variant, the 500 communication relay is an integral part of a 400 SUV already present on site if required for the primary seabed exploration mission. The resulting advantage is having the simplest and least expensive 100 storage station possible.

[0370] As illustrated in Figure 1A, the SUV then presents a body 301 which forms the body 501 of the relay, as well as the components 502-506 described previously with reference to the communication relay 500.

[0371] Use of the current determination method

[0372] The current determination method, such as a current table based on the tide time, a drifting buoy, or a Doppler log attached to a boat, is used to predict the strength and direction of the current at the scheduled arrival time of the AUVs 200. This arrival time can preferably be set at slack tide, or the mooring position of the storage station 100 can be adjusted so that the AUVs 200 reach cable 130 facing the current. This makes the mooring of the AUVs 200 to cable 130 even more reliable.

[0373] Use of a 120 float attached to the 170 buoy

[0374] From the opportunity boat, approaching storage station 100, the operator throws a grapple, aiming at the floating cable 181 separating the float 180 from the buoy 170. This makes the lifting of storage station 100 faster and reduces the risk of all or part of the device getting caught in the propeller or appendages of the opportunity boat.

[0375] Variations concerning the mooring of storage stations.

[0376] In addition to the ballast 110, an anchor 111 and its chain 111 can be provided when launching the storage station 100 to counteract the drift of the storage station 100 in case of strong currents.

[0377] Moreover, as illustrated in figure 7, several ballasts 110a, 110b can be provided for the same storage station 100. For example, each of these ballasts 110a, 110b is linked to the cable 130 by a rope or a chain 1101a, 1101b.

[0378] In the example illustrated in Figure 8, the storage station 100 is configured so that the cable 130 is not positioned substantially vertically. The cable has an oblique direction or curvature relative to the vertical. To achieve this, at least two mooring devices (typically ballasts 110s, 110a, 110b) can be provided, each connected to the collection cable 130. One or more floats 120a, 120b, 120c are also provided, connected to the collection cable 130, to keep the latter away from the seabed 1.

[0379] In the illustrated example, the storage station 100 has two ground anchoring devices 110, here two ballasts 110s 110a, 110b, and three floats 120a, 120b, 120c. The collection cable 130 then has a curved shape extending mainly in a horizontal direction. Locally, the collection cable 130 exhibits varying extension directions Z130', Z130” along its length.

[0380] Alternatively, two mooring devices 110 on the ground and a single float 120 can be provided, for example located at an equal distance between the two mooring devices.

[0381] All the characteristics described with reference to the storage stations mentioned previously can be combined with this example.

[0382] This example with a non-vertical cable has the advantage of limiting the maximum height H100 to which the storage station 100 rises from the seabed 1. This embodiment can prove useful when the water height is low or when underwater or surface activities prevent the deployment of a storage station 100 over a greater height.

[0383] In light of the preceding description, it is clear that the invention significantly simplifies the recovery of AUVs, particularly large fleets of AUVs. Furthermore, the storage system is particularly inexpensive, easy to transport, and simple to store.

[0384] The embodiments described above mention the presence of multiple AUVs on a single storage station to highlight the advantages provided. However, it is clear that each of these embodiments is perfectly applicable to the docking of a single AUV to a storage station.

[0385] The invention is not limited to the embodiments previously described and extends to all embodiments covered by the invention.

Claims

44 Demands 1. Method for recovering at least one autonomous underwater vehicle (AUV) (200), - the AUV (200) comprising at least one propulsion device (202), a control device configured to control the propulsion device (202), an acoustic communication device (203) configured to receive acoustic signals, and a docking device (210) configured to dock the AUV (200) to a storage system (1000), - the storage system (1000) comprising at least one storage station (100), the storage station (100) comprising: • a collection cable (130) from at least one AUV (200), • at least one mooring device (210) configured to moor the collection cable (130) to the seabed (1), and preferably comprising at least one ballast (110) intended to rest on a seabed (1), and • at least one float (120) exhibiting positive buoyancy in water and attached to the collection cable (130) such that the collection cable (130) extends between the float (120) and the mooring device, the process comprising: a step of securing at least one AUV (200) to the submerged collection cable (130) of the storage station (100), during which the securing device (210) equipping the AUV (200) is configured so as to secure the AUV (200) to the collection cable (130), a storage phase during which at least one AUV (200) remains secured to the collection cable (130), a recovery step of at least one AUV (200), the recovery step comprising at least one of: o a lifting stage, at the surface of the water, of the collection cable (130) to which the at least one AUV (200) is attached during the lifting stage and o a step of raising the at least one AUV (200) to the surface of the water, during which the at least one AUV (200) ascends along the collection cable (130) while remaining attached to the collection cable (130), the AUV (200) being equipped with a lifting device which it activates to ascend.

2. Method according to the preceding claim, further comprising, prior to the lashing step, an installation step of the storage system (1000), the installation step comprising the immersion of the storage station (100) and the collection cable (130) being configured so that the float (120) is located below the surface of the water.

3. A method according to any one of the preceding claims, wherein, during the storage phase, several AUVs (200) are simultaneously lashed onto the collection cable (130) of a storage station (100) and are recovered during the same recovery step.45 4. A method according to any one of the preceding claims, further comprising, prior to the docking step, a docking step of at least one AUV (200) during which the control device of the AUV (200) is configured to command the propulsion device, at least as a function of the acoustic signals received from the transmitter (140), in order to bring the AUV (200) into a docking configuration with the collection cable (130).

5. A method according to any one of the preceding claims, wherein the recovery step includes the step of raising the collection cable (130) to the surface of the water.

6. Method according to the preceding claim, wherein during the lifting step a plurality of AUVs (200) is lashed to the collection cable (130).

7. A method according to any one of claims 1 to 4, wherein the recovery step includes the step of raising the at least one AUV (200) to the surface of the water, during the raising step the at least one AUV (200) ascends along the collection cable (130), the raising device comprising the propulsion device or a ballast.

8. Method according to the preceding claim, wherein the storage station (100) comprises at least one positive buoyancy element, referred to as the floating element, taken from a surface float (180) and a buoy (170), the floating element being connected to the float 120 or to the cable (130) by a rope (181, 176) and wherein, during the ascent step, the AUV (200) ascends vertically beyond the float (120) while remaining connected to the rope (181, 176).

9. A method according to any one of the two preceding claims, wherein when a predetermined event occurs, the AUV activates its ascent device so as to rise to the surface along the collection cable (130), the event being taken from: reception by the AUV (200) of a signal, preferably acoustic, for example from a ship or aircraft, a predetermined date and time for the end of the mission, a predetermined end-of-mission period.

10. A method according to any one of the three preceding claims, wherein the storage station (100) and the AUV (200) are configured such that when the AUV (200) moves up the cable, the float (120) can pass through the AUV (200) until it is free from the float (120).

11. A method according to the preceding claim, wherein the lashing device (210) comprises an opening (241) within which the cable 130 slides during the ascent of the AUV (200) along the cable (130), the cross-section of this opening (241) and the cross-section of the float (120) are configured such that the float (120) passes through this opening (241), thus allowing the AUV (200) to disengage from the cable (130) and the float (120) and ascend to the surface, the float (120) having a vertically elongated shape, the dimension of the float (120), taken vertically, when the 46 float (120) is submerged is X times greater than the maximum dimension of its section taken in a horizontal plane, with preferably X > 3, preferably X > 5, preferably X > 10.

12. A method according to any one of the two preceding claims, wherein the float (120) comprises several portions (121 a-121 f), separated from each other by folding zones (122) and shaped to facilitate the folding or winding of the float 120, the folding zones being formed by spaces separating the portions (121 a-121 f) or by section restrictions.

13. A method according to any one of the six preceding claims, wherein, during the storage phase, several AUVs (200) are simultaneously lashed onto the collection cable (130) of a storage station (100), the collection cable (130) comprising stops (150) configured to prevent the downward sliding of the AUVs (200) under the effect of their gravity, the AUVs 200 and the storage station 100 being configured such that: When the AUV is secured and in storage or standby mode, it exhibits negative buoyancy; the stop (150) prevents the AUV (200) from sliding downwards along the cable under the effect of gravity. when the AUV is in the upward phase, it passes beyond the stops (150) located above the AUV (200), preferably the stops (150) passing through the AUV (200).

14. A method according to any one of the seven preceding claims, wherein, when the AUV is attached to the collection cable (130) and in the storage phase, it has a first inclination, within a first range of inclinations relative to the horizontal, in which the stop (150) cannot slide relative to the AUV (200) so as to prevent the AUV from descending lower than the stop (150) located below the AUV (200), when the AUV is in the ascent phase, its ascent device positions its inclination in a second range of inclinations relative to the horizontal, in which the AUV's lashing device (200) has a shape complementary to that of the stop (150) allowing one to slide into the other, so as to allow the AUV to pass the stop (150) located above the AUV (200).

15. A method according to any one of the eight preceding claims, wherein the AUV (200) comprises a proximity sensor, taken from an optical sensor, an acoustic wave sensor and an electric field sensor, and wherein the collection cable (130) comprises at least one docking zone (1301-1304) configured to react with this proximity sensor so that the AUV (200) locates the docking zone (1301-1304).

16. A method according to any one of the preceding claims, wherein the storage station (100) comprises, in a retracted manner, on the float (120) or on the cable (130), at least one positive buoyancy element, referred to as a floating element, taken from a surface float (180) and a buoy (170), the floating element being connected to the float (120) or to the cable (130) by a line (181, 176), during the storage phase of at least one AUV (200) the floating element being retained below the surface of the water, and, in response to a predetermined event, the storage station (100) is configured to allow the floating element to return to the surface of the water.

17. Method according to the preceding claim, wherein the storage station (100) includes a retention device that engages to release the cable (181, 176) and / or the floating element, preferably, the retention device includes an electromechanical actuator that releases a retention hook retaining the floating element or the cable (181, 176) or that releases a blade that cuts an element such as a wire retaining the floating element or the cable (181, 176).

18. A method according to either of the two preceding claims, wherein the predetermined event is, for example, taken from: the reception by the storage station (100) of a signal, preferably acoustic, for example from a ship or an aircraft or an AUV (200), a predetermined date and time for the end of the mission, a predetermined end-of-mission period, the dissolution of a salt tablet.

19. A method according to any one of the preceding claims, further comprising, prior to the docking step, an installation step of the storage system (1000), the installation step comprising an immersion of the storage station (100) and the collection cable (130) being configured so that the float (120) is located below the surface of the water.

20. A method according to any one of the preceding claims, wherein the lashing device (210) is configured so that the AUV (200) lashes onto the collection cable (130) by a recoil movement of the AUV (200) relative to the collection cable (130).

21. Method according to the preceding claim, wherein the AUV (200) has two propulsion devices (202a, 202b) positioned on a rear portion (260) of the AUV (200), preferably symmetrically with respect to a median plane (ZX) of the AUV (200), and the docking device (210) is positioned between the two propulsion devices (202a, 202b).

22. Assembly for implementing the process according to claim 1, comprising: - one or a plurality of autonomous underwater vehicles (AUVs) (200), each comprising at least one propulsion device (202), a control device configured to control the propulsion device (202) and an acoustic communication device (203) configured to receive acoustic signals, - an autonomous storage system (1000) for one or a plurality of autonomous underwater vehicles (AUVs) (200), the storage system (1000) comprising at least one storage station (100), characterized in that at least one storage station (100) comprises: • a collection cable (130) for the AUV(s) (200), • at least one mooring device (210) configured to moor the collection cable (130) to the seabed (1), and preferably comprising at least one ballast (110) intended to rest on a seabed (1), and • at least one float (120) exhibiting positive buoyancy in water and attached to the collection cable (130) such that the collection cable (130) extends between the float (120) and the mooring device, • an acoustic signal transmitter (140) connected to the collection cable (130) and configured to send acoustic signals to the acoustic communication device of the AUV(s) (200), and in that • Each AUV (200) includes at least one lashing device (210) configured to lash the AUV (200) to the cable, • for each AUV, the control device is configured to command the propulsion device, at least according to the acoustic signals received from the transmitter (140), in order to bring the AUV (200) into a docking configuration with the collection cable (130), • and wherein the AUV (200) includes a retrieval device configured to, from the docking configuration, retract by sliding along the collection cable (130) until it is free from the float (180) and reaches the water surface.

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