Submersible vehicle recovery system

Abstract

A recovery system for retrieval of submersible objects onto a vessel comprises a conveyor apparatus, the conveyor apparatus operable to transport received objects from a first end of the conveyor apparatus to a second end of the conveyor apparatus, wherein the first end of the conveyor apparatus is at least partially submersible in water around the vessel such that the conveyor apparatus can receive submersible objects when in a deployed configuration, and wherein the second end is adapted to be mounted to a midship position of the vessel such that submersible objects received by the conveyor apparatus can be transported to the midship position of the vessel. A vessel comprising the recovery system and a corresponding method are also provided.

Description

[0001] SUBMERSIBLE VEHICLE RECOVERY SYSTEM

[0002] This application claims priority from GB2417820.4, filed 4 December 2024, and from GB2418797.3, filed 20 December 2024, the contents and elements of which are herein incorporated by reference for all purposes.

[0003] Technical Field

[0004] The present invention relates to a recovery system for the retrieval of submersible objects onto a sea vessel. The invention has particular relevance to the retrieval of unmanned underwater vehicles.

[0005] Background

[0006] In the field of ocean surveying, the use of unmanned underwater vehicles (UUVs) in the performance of an ocean survey is known. UUVs are generally deployed from and retrieved by sea vessels.

[0007] Deployment and retrieval of small numbers of UUVs may be conducted manually, for example by retrieving individual vehicles using a crane (or davit). Such methods do not scale efficiently with the number of UUVs, which can lead to a slow recovery rate when a large number of UUVs is used resulting in an unwanted increase in the time taken to complete a survey.

[0008] Stern-mounted ramps or conveyor belts have been used for continuously recovering objects from the water, but such systems can be cumbersome and risk damaging the vehicles. In particular, such ramps or conveyor belts often move with the pitching motion of the ship in a manner that is out-of-phase with the vehicle to be retrieved, resulting in a risk of collision between the ramp and a UUV, causing damage.

[0009] It is desirable to provide an improved recovery system for retrieval of submersible objects which reduces unwanted motion of the recovery system.

[0010] Summary

[0011] According to a first aspect of the present invention, there is provided a recovery system for retrieval of submersible objects onto a vessel, the recovery system comprising a conveyor apparatus to transport received objects from a first end of the conveyor apparatus to a second end of the conveyor apparatus, wherein when deployed the first end of the conveyor apparatus is at least partially submerged in water around the vessel such that the conveyor apparatus can receive submersible objects, and wherein the second end is adapted to be mounted to a midship position of the vessel such that submersible objects received by the conveyor apparatus are transported to the midship position of the vessel.

[0012] In some examples, the submersible objects retrieved by the system are unmanned underwater vehicles (UUVs), but other submersible objects may additionally or alternatively be retrieved by the recovery system. For example, equipment used in or related to an ocean survey, but which does not necessarily have means for propulsion, may nevertheless be retrieved from water using the recovery system, such as buoys, jettisoned data modules, batteries, and the likes.

[0013] The conveyor apparatus, when mounted to a midship position of the vessel, may be less affected by motions of the vessel, such as oscillatory motions of the vessel due to water surrounding the vessel, compared with stern-mounted recovery systems, for example. This can permit increased rate of retrieval of submersible objects from the water as it is more straightforward to receive the submersible object at the conveyor apparatus. The reduced motion can also prevent risk of damage to at least one of the vessel, the conveyor apparatus and the submersible objects being retrieved.

[0014] In some examples, the midship position of the vessel corresponds to a centre- of-mass of the vessel. This can further reduce, or minimise, the motion of the conveyor apparatus. In some examples, the midship position of the vessel corresponds to a position of minimal pitching of the vessel, to similarly reduce or minimise motion of the conveyor apparatus. In some examples, the centre-of-mass and the position of minimal pitching are co-located.

[0015] In some examples, the second end of the conveyor apparatus is mounted to the midship position of the vessel by a universal joint. This can decouple motion of the vessel from motion of the conveyor apparatus, thereby further reducing movement of the conveyor apparatus relative to the submersible objects being retrieved.

[0016] In some examples, the deployed configuration comprises the conveyor apparatus extending alongside the vessel. In such examples, the conveyor apparatus runs predominantly parallel with a centreline of the vessel, that is, in the direction of the vessel. By extending alongside the vessel, motion of the conveyor apparatus may be better correlated with motion of the vessel, which can improve performance of the recovery system by reducing misalignment, for example, and / or simplifying control of the conveyor apparatus, for example.

[0017] In some examples, the recovery system further comprises deployment apparatus to manoeuvre the conveyor apparatus to the deployed configuration. The conveyor apparatus is thereby manoeuvrable from another configuration to a deployed configuration. In some examples, the deployment apparatus comprises a crane with a winch device.

[0018] In some examples, the deployment apparatus is operable to manoeuvre the first end of the conveyor apparatus whilst the conveyor apparatus is in the deployed configuration. This allows the first end of the conveyor apparatus to be repositioned and / or reoriented whilst deployed, thereby improving the ability of the recovery system ability to retrieve submersed objects.

[0019] In some examples, the deployment apparatus is operable to manoeuvre the conveyor apparatus between a stowed configuration and a deployed configuration. The stowed configuration allows the conveyor apparatus to be stowed for, as an example, transportation purposes, and then deployed only when retrieval of submersible objects is required, for example. In some examples, the stowed configuration comprises the first end of the conveyor apparatus being located on a deck of the vessel. In some examples, the stowed configuration comprises the conveyor apparatus being substantially parallel to a centreline of the vessel. In some examples, the conveyor apparatus is substantially parallel to the centreline of the vessel in both stowed and deployed configurations.

[0020] In some examples, the conveyor apparatus comprises a first conveyor belt section and a second conveyor belt section arranged in series, such that the second conveyor belt section receives objects transported by the first conveyor belt section.

[0021] In some examples, the second conveyor belt section is separated from the first conveyor belt section by a separation distance such that submersible objects, received by the first conveyor belt section and being smaller than the separation distance, are not received by the second conveyor belt section. In other words, a gap exists between the first conveyor belt section and the second conveyor belt section. This allows unwanted submersible objects, such as ocean debris and the likes, to be filtered from the conveyor apparatus, whereas submersible objects larger than the separation distance are conveyed between the first conveyor belt section and the second conveyor belt section. In some examples, the separation between the second conveyor belt section and the first conveyor belt section is positioned outboard of the vessel, above the water, such that submersible objects smaller than the separation distance fall back into the water.

[0022] In some examples, the second conveyor belt section is adapted to be mounted to the midship position of the vessel, and the first conveyor belt section is movably attachable to the second conveyor belt section.

[0023] In some examples, the second conveyor belt section is operable to transport objects received at the midship position of the vessel to a position on a deck of the vessel.

[0024] In some examples, the conveyor apparatus comprises a plurality of resiliently deformable gripping members. These gripping members may have asymmetric restoring biases, such that they are relatively stiff in a direction from the second end to the first end, and relatively pliant in a direction from the first end to the second end. The gripping members may be disposed around one or more wheels, which are driven so as to urge the submersible object towards the second end of the conveyor apparatus. The wheels may be arranged along respective driven axles (and there may be a plurality of wheels on each of the plurality of axles).

[0025] In some examples, the first end of the conveyor apparatus comprises a funnel for receiving submersible objects onto the conveyor apparatus. The funnel acts to guide submersible objects towards the conveyor apparatus, improving a rate of retrieval by the recovery system, for example. In some examples, the funnel comprises a pump configured to pump water towards the first end of the conveyor apparatus. The funnel may be defined by a cross-section of the conveyer apparatus, having a wider crosssection than the remaining portions of the conveyer apparatus. The funnel may be circular in cross-section, or have only a partially-circular cross-section, in that it may be ‘open’. For example, it may be generally U-shaped, such that submersible objects may fall into it and be captured. In such examples, retrieval of the submersible objects by the conveyor apparatus can be improved, such as by being increased in speed or by reducing the chance of an unwanted collision of the submersible object with the conveyor apparatus. In some examples, the conveyor apparatus comprises a wireless transponder located on the first end of the conveyor apparatus, the wireless transponder being configured to transmit a beacon signal or similar. In use, the beacon signal can be used by a submersible object to find and approach the first end of the conveyor apparatus.

[0026] In some examples, the conveyor apparatus comprises a recovery control system operable to determine a position of the conveyor apparatus. For instance, in some examples determines a position in space of the first end of the conveyor apparatus. Such a position may be defined in a single dimension, two dimensions, three dimensions, and so on. In some examples, the position is a position relative to a position of the vessel, such as a distance away from a side of the vessel, and / or a depth relative to a deck of the vessel, for example.

[0027] In some examples, the recovery control system is operable to determine a position of a submersible object. For example, the recovery control system may determine a geographic location of the submersible object. In some examples, the position if the submersible vehicle is relative to a position of the vessel. For example, the position of the submersible vehicle may be a proximity to the vessel, such as a distance and bearing from a position on the vessel. In some examples, the position of the submersible vehicle is relative to the first end of the conveyor apparatus, which may be manoeuvrable independently from the vessel. In some examples, the position of the submersible object is determined by acoustic methods. In some examples, the position of the submersible object is received as communicated information from the submersible object. That is, the submersible vehicle may determine its location based on a geographical positioning system such as GPS, acoustic positioning, and / or relative to the vessel, and / or the to the first end of the conveyor apparatus, and communicate the same to the recovery control system.

[0028] In some examples, the recovery control system is operable to determine current information of the water surrounding the vessel. In some examples, the current information comprises speed and direction information. The recovery control system may use the current information to orient, position, reorient, and / or reposition the conveyor apparatus. This can allow the conveyor apparatus to more effectively, such as more quickly, or energy-efficiently, retrieve the submersible objects by taking into account a likely drift direction of the submersible object due to currents. In some examples, the recovery control system is operable to communicate determined information to a submersible object. In some examples, the recovery control system communicates at least one of: a position of the conveyor apparatus, a position of the submersible object, and current information to the submersible object. Such a submersible object may have navigation control systems which, in receipt of the determined information, can use the determined information to navigate to the first end of the conveyor apparatus. In some examples, the recovery control system may communicate the information to an external navigation control unit responsible for controlling the submersible objects.

[0029] In examples where the recovery system comprises deployment apparatus operable to manoeuvre the conveyor apparatus whilst in the deployed configuration, in some examples the deployment apparatus manoeuvres the conveyor apparatus based on a determination of the recovery control system.

[0030] In some examples, the conveyor apparatus comprises steering apparatus, operable to manoeuvre the conveyor apparatus when in the deployed configuration.

[0031] In examples where the conveyor apparatus comprises a recovery control system, the steering apparatus is operable to manoeuvre the conveyor apparatus based on a determination of the recovery control system. In some examples, the steering apparatus is operable to manoeuvre the conveyor apparatus based on the determination of least one of: a position of the conveyor apparatus, a position of the submersible object, and current information.

[0032] In some examples, the steering apparatus comprises at least one of an aileron, a rudder, thrusters, and a buoyancy device. In some examples, the buoyancy device is a variable buoyancy device, such that the buoyancy can be varied in order to determine a depth of the conveyor apparatus. In some examples, the steering apparatus is mounted to the first end of the conveyor apparatus. The buoyancy device may be a fixed buoyancy device, such that the first end of the conveyor apparatus is held at a fixed depth below the surface. Such a buoyancy device may be a buoy on the surface of the water, connected via a wire or chain to the first end of the conveyor apparatus.

[0033] In some examples, the conveyor apparatus comprises taglines, the taglines attachable to the vessel such that motion of the conveyor apparatus is limited. In some examples, the taglines are attached to the side of the vessel to reduce lateral movement relative to the vessel.

[0034] According to a second aspect of the invention, there is provided a vessel comprising the recovery system of any previous claim. The vessel, comprising a recovery system according to the invention, may more rapidly retrieve submersible objects and thereby improve power or fuel efficiency. Fewer vessels may be required to retrieve a collection of submersible objects due to the improved rate of retrieval of a single vessel comprising a recovery system according to the invention, which can reduce the fuel requirement and carbon footprint of a retrieval operation.

[0035] According to a third aspect of the invention, there is provided a method for recovery of submersible objects onto a vessel, the method comprising: providing a conveyor apparatus, a first end of the conveyor apparatus at least partially submersed in the water and a second end of the conveyor apparatus attached to a midship position of the vessel; receiving a submersible object at the first end of the conveyor apparatus; transporting the submersible object to the second end of the conveyor apparatus; and receiving the submersible object at the midship position of the vessel.

[0036] Further features and advantages of the invention will become apparent from the following description of implementations of the present disclosure, given by way of example only, which is made with reference to the accompanying drawings.

[0037] Brief Description of the Drawings

[0038] Figures 1 shows a perspective view of a recovery system mounted on a vessel in a deployed configuration according to an example;

[0039] Figure 2 shows a perspective view of the recovery system illustrated in Figure 1 in a stowed configuration on the vessel;

[0040] Figure 3 shows a side-view of the recovery system illustrated in Figure 1 in the deployed configuration with an overboard conveyor positioned to recover an unmanned underwater vehicle (UUV);

[0041] Figure 4 is a block diagram showing the main components of a recovery control system forming part of the recovery system illustrated in Figure 1; and

[0042] Figure 5 is a flowchart depicting operations in a recovery process according to an example. Detailed Description

[0043] Figures 1 and 2 show the stern portion of a vessel 80, such as a platform supply vessel, equipped with an exemplary recovery system 100 according to the present disclosure.

[0044] The recovery system 100 is for the retrieval of submersible objects from water surrounding the vessel 80. In this example, the submersible objects are unmanned underwater vehicles (UUVs) 50 which conduct oceanic surveys. Following and / or during a survey, the UUVs 50 return to the location of the vessel 80 and a recovery process is undertaken, during which the UUVs 50 are retrieved from the water and onto the vessel 80 by the recovery system 100. Once retrieved onto the vessel 80 the UUVs 50 can be moved into a vehicle processing apparatus 90 where the UUVs 50 are stored and recharged, and data collected during the survey offloaded onto a central survey system.

[0045] The recovery system 100 includes a conveyor apparatus 150, a deployment apparatus 175 and a recovery control system 200. The conveyor apparatus 150 is, generally, for transporting objects, such as UUVs 50, from the water to a position onboard the vessel 80, such as to a storage unit, cleaning area, or similar. The recovery control system 200 helps in manoeuvring the UUVs 50 and the conveyor apparatus 150 to facilitate retrieval of the UUVs 50. The deployment apparatus 175 reconfigures the conveyor apparatus 150 between a deployed configuration and a stowed configuration.

[0046] The vessel 80 undergoes pitching motions due to waves. The magnitude of the pitching motions of the vessel 80 is lower in midship regions of the vessel than in the forward or aft regions. A position of minimum pitching motion refers to the position on the vessel which experiences the least pitching motion. The position of minimum pitching motion, in the example of Figures 1 and 2, is close to the centre-of-mass of the vessel 80. It will be appreciated that the position of minimum pitching motion will vary from vessel to vessel, dependent on e.g. a weight distribution of the vessel, or a shape of the vessel. Generally, the present disclosure involves arranging components of the recovery system to reduce or minimise the impact of pitching motion of the vessel 80 on the ability of the recovery system 100 to retrieve the UUVs from the water. The conveyor apparatus 150, deployment apparatus 175 and recovery control system 200 will now be described in more detail.

[0047] Conveyor apparatus

[0048] As described above, the conveyor apparatus 150 is generally representative of a series of one or more conveyor devices which are for retrieving submersible objects to the deck of the vessel 80.

[0049] In the example of Figures 1 and 2, the conveyor apparatus 150 is formed of two segments: a first conveyor belt section 152, which will hereafter be referred to as the overboard conveyor 152, and a second conveyor belt section 154, which will hereafter be referred to as the handling conveyor 154. The overboard conveyor 152 and handling conveyor 154 are connected in series, such that an object is transported along the overboard conveyor 152 from a first end 152a to a second end 152b, and then along the handling conveyor 154 from a second end 154b to a first end 154a. The overboard conveyor 152 is for retrieving UUVs 50 from the water and transporting the UUVs 50 to the vessel, and the handling conveyor 154 is for transporting the retrieved vehicles once on the vessel.

[0050] In the example of Figures 1 and 2, the conveyor apparatus 150 is reconfigurable between a deployed configuration, wherein the conveyor apparatus is operable to retrieve UUVs 50, and a stowed configuration, wherein the conveyor apparatus 150 is stored on the vessel 80 deck for transit.

[0051] Deployed configuration

[0052] Turning first to the deployed configuration of the conveyor apparatus 150, depicted by Figure 1 : the conveyor apparatus 150 is configured such that, in the deployed configuration, the overboard conveyor 152 is mounted to the vessel 80 at a midship position of the vessel 80, and in particular to the second end 154b of the handling conveyor 154. The midship region is a region between the forward and aft regions of the vessel 80, such as within a central half of the length of the vessel 80, and corresponds with a position of minimal pitching motion of the vessel 80.

[0053] In both deployed and stowed configurations, the handling conveyor 154 extends from a central position on the deck of the vessel 80 to a midship position at a side of the vessel 80, and runs generally perpendicular to the longitudinal axis of the vessel 80. The handling conveyor 154 is movably mounted on top of, and supported by, a skid frame 172. The handling conveyor 154 is movable along the top of the skid frame 172 such that a portion of the handling conveyor 154 including the second end 154b of the handling conveyor 154 can project outwards and overhang the side of the vessel 80. In the deployed configuration, a portion of the handling conveyor 154 projects out from the skid frame 172 such that a portion of the handling conveyor 154 including the second end 154b of the handling conveyor 154 overhangs the side of the vessel 80.

[0054] The overboard conveyor 152 is located overboard of the vessel 80, being attached to the second end 154b of the handling conveyor 154 by a universal joint 156. The overboard conveyor 152 is positioned alongside the vessel 80 and substantially parallel to a centreline of the vessel 80 and parallel to the port side of the vessel 80. The first end 152a of the overboard conveyor 152 is at least partially submersed in water around the vessel 80 such that the first end 152a of the overboard conveyor 152 can receive UUVs 50 from the water.

[0055] The overboard conveyor 152, being mechanically coupled to the vessel 80 at a point of minimum pitching motion, experiences reduced motion due to motion of the vessel 80. Reducing motion such as vertical displacement motion of the overboard conveyor 152 can, for example, reduce risk of damaging the UUVs 50 during retrieval. Reducing unwanted motion may also allow the recovery system 100 to tolerate rougher ocean conditions whilst conducting a recovery process, improving the robustness of the recovery system 100 and reducing the time taken to undertake a recovery process.

[0056] In Figure 1, the overboard conveyor 152 forms a 30-degree angle of inclination with respect to the horizontal plane of the deck, but this angle of inclination may vary between, for example, 0-degrees and 90-degrees, dependent upon the relative height of the deck with the waterline and the length of the overboard conveyor 152. Similarly, the overboard conveyor 152 is arranged to lie substantially parallel to the centreline 85 of the vessel 80, such that the overboard conveyor 152 lies alongside the vessel, and as such the overboard conveyor 152 forms a 90-degree angle of orientation with the handling conveyor 154. However, this angle of orientation may vary between, for example, 0-degrees, such that the overboard conveyor is co-linear with the handling conveyor, and 90-degrees as depicted in Figure 1. Such a change in angle of orientation or angle of inclination may result from an intentional reorientation during, for example, a recovery process, or may result from motion of the ship and / or water. The universal joint 156 allows the motion of the vessel 80, such as pitching or rolling motion, to be decoupled from the overboard conveyor 152, which can reduce unwanted motion of the overboard conveyor 152.

[0057] Stowed configuration

[0058] Figure 2 displays the conveyor apparatus 150 in the stowed configuration. In the stowed configuration, the overboard conveyor 152 is located on the deck of the vessel 80 and lies parallel with the centreline of the vessel 80. The first end 152a of the overboard conveyor 152 is retained in a cradle 132. The handling conveyor 154 is retracted along the skid frame 172 to sit entirely on top of the skid frame 172 and does not overhang the side of the vessel 80. In this way, all components of the conveyor apparatus 150 are located on the deck of the vessel 80 in the stowed configuration. The conveyor apparatus 150, being stored on the deck of the vessel 80 in the stowed configuration, is thereby more secure during ocean transit. The overboard conveyor 152 being located on the deck in the stowed configuration allows the overboard conveyor 152 to be inspected and undergo maintenance, or cleaning to remove, for example, seaweed and other ocean debris which might accumulate whilst the overboard conveyor 152 is partially submersed during a recovery process.

[0059] In some examples, in the stowed configuration components of the conveyor apparatus 150 may be detached from one another to allow for more space efficient storage, for example.

[0060] Deployment apparatus

[0061] The deployment apparatus 175 generally represents devices operable to reconfigure the conveyor apparatus 150 between the deployed configuration and the stowed configuration. The deployment apparatus 175 of the present example includes a winch device 180 mounted to a crane 185, and hydraulic actuators 187.

[0062] The crane 185 and winch device 180 are located on the deck of the vessel 80, proximate the cradle 132 which retains the first end 152a of the overboard conveyor 152 in the stowed configuration. The winch device 180 includes a cable attached to the first end 152a of the overboard conveyor 152. The winch device 180 is operable to increase and decrease the length of cable currently deployed, thereby lowering or raising the overboard conveyor 152. The winch device 180 can lift the first end 152a of the overboard conveyor 152 out of the water and up to the level of the deck, including into the cradle 132. The crane 185 is operable to manoeuvre the first end 152a of the overboard conveyor 152 by changing the orientation of the cable of the winch device 180. The crane 185 can thereby reorientate and reposition the overboard conveyor 152 between a deployed configuration and a stowed configuration.

[0063] The hydraulic actuators 187 are attached to the first end 154a of the handling conveyor 154 and are operable to extend and retract the handling conveyor 154 relative to the skid frame 172 upon which the handling conveyor 154 is mounted. The handling conveyor 154 being extended refers to projecting a portion of the handling conveyor 154 overboard of the side of the vessel 80, as in the deployed configuration. The handling conveyor 154 being retracted refers to the handling conveyor 154 being entirely positioned on the deck of the vessel 80, such as in the stowed configuration.

[0064] In reconfiguring the conveyor apparatus 150 between the deployed configuration and the stowed configuration, the constituent components of the deployment apparatus 175 may work in tandem or sequentially to perform the necessary manoeuvres for reconfiguration. For example, the winch 180 may first lift the first end 152a of the overboard conveyor 152 from the water to deck-height. The hydraulic actuators 187 may then retract the handling conveyor 154. The crane 185 and the winch 180 may then be used to reposition the first end of the overboard conveyor 152 into the cradle 132.

[0065] Overboard conveyor

[0066] Returning now to considering the conveyor apparatus 150, specific features of the overboard conveyor 152 will now be described. Figure 3 shows the overboard conveyor 152 in the deployed configuration.

[0067] The overboard conveyor 152 has two driven belts 300a, 300b arranged in a stacked configuration, with a first driven belt 300a as a top belt and a second driven belt 300b as a bottom belt such that a channel is formed between the first driven belt 300a and the second driven belt 30b. Each driven belt 300a, 300b has rubberised flexible transverse ribs 302a, 302b facing towards the channel formed by the driven belts 300a, 300b. UUVs 50 are received in the channel between the top belt 300a and the bottom belt 300b, such that they are engaged by the flexible transverse ribs E302a,b. The flexible transverse ribs 302a, b are flexible such that they conform to the shape of the received vehicle 50, but sufficiently rigid such that the vehicle 50 is gripped between the top and bottom belts 300a, b as the vehicle 50 is transported to the vessel 80 deck by the conveyor apparatus 150. This can ensure that the vehicle 50 is not displaced from the conveyor apparatus 150 and thereby reduces the likelihood of damage to the vehicle 50.

[0068] The overboard conveyor 152 includes a funnel 160 mounted by a hinge at the first end 152a, the opening of the funnel 160 facing away from the first end 152a of the overboard conveyor 152. The funnel 160 guides UUVs 50 in the water onto the overboard conveyor 152. The funnel 160 is equipped with water pumps (not pictured) which are arranged to propel water into the funnel 160, towards the first end 152a of the overboard conveyor 152. The flow of water produced by the water pumps further helps guide UUVs 50 in the water onto the overboard conveyor 152. The funnel 160, being mounted by a hinge, can be reorientated relative to the overboard conveyor 152. This can improve the ease of retrieval of UUVs 50 which approach the first end 152a of the overboard conveyor 152 from an angle rather than aligned colinearly with the conveyor 152.

[0069] The overboard conveyor 152 also includes thrusters 162 and a buoyancy device 164 mounted at the first end 152a of the overboard conveyor 152. The thrusters 162 are operable to provide a thrusting force in the water such that the position of the first end 152a of the overboard conveyor 152 can be changed. The buoyancy device 164 is a variable buoyancy device, the buoyancy of which can be varied to achieve a desired depth of the first end 152a of the overboard conveyor 152. In a negative buoyancy state, the buoyancy device 164 allows the first end 152a of the overboard conveyor 152 to be submersed under the water. In a neutrally buoyant state, the buoyancy device 164 allows the first end 152a of the overboard conveyor 152 to remain relatively fixed in position, neither sinking nor rising from a current depth. In a positively buoyant state, the buoyancy device 164 enables the first end 152a of the overboard conveyor 152 to float on the surface of the water, being only partially submersed. The depth of the first end 152a of the overboard conveyor 152 can therefore be varied to most effectively receive the UUVs 50. Furthermore, the buoyancy device 164 can provide a depthaveraging effect as opposed to closely following the surface of the water, which can further reduce or smooth unwanted motion of the overboard conveyor 152.

[0070] The overboard conveyor 152 is attached to tag lines 166 which are also attached to the side of the vessel 80. The tag lines can reduce the movement of the overboard conveyor 152 to thereby improve its stability, and can limit the distance the overboard conveyor 152 can stray from the vessel 80. Additionally, fenders 168 are provided alongside the vessel 152, between the overboard conveyor 152 and the side of the vessel 80, to reduce the impact of collisions between the overboard conveyor 152 and the side of the vessel 80. This can further reduce likelihood of damage to the vessel 80, the conveyor apparatus 150 and / or retrieved UUVs 50.

[0071] The second end 152b of the overboard conveyor 152 is separated, at the universal joint 156, from the handling conveyor belt 154 by a separation distance. The received UUVs 50 are larger than the separation distance and so span the gap between the onboard conveyor 152 and the handling conveyor 154. Submersible objects which have been inadvertently retrieved by the overboard conveyor 152 and which are smaller than the separation distance fall through the gap and back into the water. This reduces the delivery by the recovery system 100 of objects other than UUVs 50 to the deck area of the vessel 80. In other examples, the overboard conveyor 152 has multiple conveyor segments separated by such gaps to achieve this effect.

[0072] In this example, the winch device 180 and crane 185 of the deployment apparatus 175, the thrusters 162, and buoyancy device 164 collectively compose steering apparatus 250. When in the deployed configuration, the steering apparatus 250 can be controlled to steer the overboard conveyor 152, making translational and orientational adjustments of the first end 152a of the overboard conveyor 152.

[0073] Recovery control system

[0074] Figure 4 schematically illustrates the recovery control system 200, which is generally representative of information processing capabilities of the recovery system 100, and in particular using received data to inform operation of the recovery system 200, in particular when in the deployed configuration. The recovery control system 200 in this example includes a steering control unit 210, a real-time locating system 220, a wireless communications system 230, and an environmental conditions unit 240, but more generally may only have one or more of the described units.

[0075] The wireless communications system 230 enables communication between components of the recovery control system 200, such that the steering control unit 210 can receive and send data, such as positional information or operational instructions, to and from the environmental conditions unit 240, real-time location system 220, steering apparatus 250, conveyor apparatus 150, and / or UUV 50. The wireless communications system 230 may utilise WiFi, RF, Bluetooth, or similar. It will be appreciated that generally the wireless communications system 230 represents connectivity between the associated components of the recovery control system, and that in other examples wired communication links may be used, where appropriate.

[0076] The steering control unit 210 communicates operational instructions via the communications system 230 to the steering apparatus 250. As described earlier, devices of the steering apparatus 250, such as the thrusters and variable buoyancy device 164, are operable to provide translative and orientational adjustments of the first end 152a of the overboard conveyor 152. The operational instructions communicated by the steering control unit 210 to the steering apparatus 250 include steering commands indicative of translative and orientational adjustments to be made by the steering apparatus 250. The operational instructions may be determined by a human operator at a user interface of the steering control unit 210, or provided automatically according to a control scheme, an example of which will be described shortly.

[0077] The real-time locating system 220 is configured to provide a real-time locating system. In this example, wireless transponders 225 are provided on the first end 152a of the conveyor apparatus 150, as well as on the UUVs 50, and signals provided by the transponders 225 are received by a receiver 227. The respective positions and orientations, within a common coordinate system, of the conveyor apparatus 150 and the UUVs 50 equipped with transponders 225 are determined by the real-time locating system 220. In some examples, the UUVs 50 can self-determine their respective positions relative to the vessel 80 using acoustic positioning techniques and communicate this information to recovery control system 200 via the communications system 230. The environmental conditions unit 240 includes instrumentation operable to determine information about the present ocean environment of the vessel 80. For example, the environment conditions unit 240 is operable to determine the direction and the strength of a current in the water surrounding the vessel 80. The environment conditions unit 240 is also operable to determine whether the sea-state surrounding the vessel 80 is too rough, or the wind too strong, to safely conduct a retrieval operation, or, conversely, that the conditions fall within tolerances of the recovery system 100.

[0078] The steering control unit 210 receives position and orientation data provided by the real-time locating system 220, as well as environmental conditions information from the environmental conditions unit 240, in order to determine a recovery process. Instructions are communicated to the steering apparatus and the UUVs 50 in order to conduct the recovery process. The recovery process may be fully automated according to a control scheme, or may involve collaborative control between a control scheme and an operator, or may be entirely manually operated by an operator.

[0079] For example, the real-time locating system 220 may record position and orientation data which indicates that the UUVs 50 are located deeper than a current position of the first end 152a of the overboard conveyor 152. The control scheme, executed by the steering control unit 210, correspondingly instructs the variable buoyancy device 164 to decrease buoyancy to a negative buoyancy state such that the first end 152a of the overboard conveyor 152 sinks to the depth of the UUVs 50. The change in depth of the overboard conveyor 152 can additionally or alternatively be achieved using the winch device 180. Alternatively, the control scheme may instruct the UUVs 50 to navigate upwards to the current depth of the first end 152a of the overboard conveyor 152, and the overboard conveyor 152 to remain fixed in position. In a further example, the control scheme instructs both the UUVs 50 and the overboard conveyor 152 to reposition to conduct retrieval.

[0080] In another example, the UUVs 50 may be located at the same depth of the first end 152a of the conveyor apparatus 150, but at a different position in the water. The control scheme may, correspondingly, instruct the thrusters 162 to manoeuvre the first end of the conveyor apparatus 150 closer to the UUVs 50. The change in position of the conveyor apparatus can additional or alternatively be achieved using the crane 185, and may also involve paying out or taking in cable at the winch device 180. In yet another example, measurements of the water conditions may indicate that it is possible to retrieve the UUVs 50 such that the conveyor apparatus 150 and opening angle of the funnel 160 are aligned colinear with the direction of a current of the water, such that the UUVs 50 are passively swept into the first end 152a of the conveyor apparatus 154, thereby increasing the rate of recovery.

[0081] Figure 5 displays a flowchart depicting a process for recovery of a submersible object by the recovery system 100 of the previously described examples.

[0082] At block S101, a conveyor apparatus is provided, a first end of the conveyor apparatus at least partially submersed in the water and a second end of the conveyor apparatus attached to a midship position of the vessel. The conveyor apparatus may have been in a stowed configuration before being reconfigured into a deployed configuration. This block may include determining the midship position associated with the minimum pitching motion of the vessel and attaching the second end of the conveyor apparatus to that position.

[0083] At block S203, a submersible object is received at the first end of the conveyor apparatus. This block may include manoeuvring the submersible object and / or the conveyor apparatus in order to receive the submersible object at the first end of the conveyor apparatus.

[0084] At block S205, the submersible object is transported to the second end of the conveyor apparatus. This may involve retaining the submersible object on the conveyor apparatus.

[0085] At block S207, the submersible object is received at the midship position of the vessel. The submersible object may undergo further transportation at the midship position to transport the submersible object to, for example, a vehicle processing apparatus on the vessel.

[0086] Modifications

[0087] The above examples are to be understood as illustrative examples of the invention. Other examples are envisioned:

[0088] For example, it will be appreciated that, in other examples, the midship position at which the conveyor apparatus 150 is positioned may be a region of reduced pitching motion rather than the position of absolute minimum pitching motion of the vessel. For example, the layout of the deck may restrict installation of the conveyor apparatus 150 at the point of minimum pitching motion, but nevertheless pitching motion may be reduced by selecting another midship position, compared with the stern region.

[0089] For example, the conveyor apparatus may only include an overboard portion of one or more conveyor segments which, in the deployed position, spans from a partially submersed position in the water to the midship position. At the midship position, a handling system may fulfil the role of the handling conveyor 154 in returning objects received from the overboard conveyor 152 to the vehicle processing apparatus 90. The handling system may be, for example, a slide or chute, a robotic arm, or manual handling by persons onboard the vessel.

[0090] For example, in the deployed configuration of Figure 1 the handling conveyor 154 overhangs the side of the vessel 80, but in other examples the handling conveyor 154 may run up to, but not over, the side of the vessel 80.

[0091] For example, in the examples of Figures 1 and 2, UUVs are being retrieved from the water. However, the skilled person will appreciate other objects may be retrieved, such as buoys, or data modules (including seismic sensor payloads) and / or batteries jettisoned by UUVs for retrieval, for example.

[0092] In the examples of Figures 1 and 2, the overboard conveyor transports objects received from the water to a midship position on the deck of the vessel, but in other examples may be configured to transport items to a midship position located elsewhere on the vessel, such as a side hanger accessible from a side of the vessel rather than the deck, but which nevertheless may experience reduced pitching.

[0093] In the examples of Figures 1 and 2, the deployment apparatus is a crane with a winch device. However, in other examples other deployment means may be used. For example, the overboard conveyor may be suitably flexible such that the overboard conveyor can be stowed in a rolled-up or folded configuration and unfurled or unfolded into a deployed position. In other examples, the conveyor apparatus may expand telescopically, or be levered into position. The deployment apparatus may be attached directly to the conveyor apparatus; for instance, reconfiguration of the conveyor apparatus may be achieved by actuators disposed along the conveyor apparatus. In the examples of Figures 1 and 2, in the stowed configuration the overboard conveyor is located on the deck. However, in other examples the overboard conveyor may be stowed in other locations, such as in an overboard position but out of the water. This may allow the overboard conveyor to be deployed more rapidly.

[0094] In the examples of Figures 1 and 2, the overboard conveyor comprises two rubberised belts which act to retain a vehicle. However, in other examples the overboard conveyor may only comprise a single belt. In examples the conveyor may comprise, for example, magnets or other adhesive or fastening elements in order to retain the received object.

[0095] In the examples of Figures 1 and 2, the steering apparatus has a variable buoyancy device and thrusters attached to the first end of the overboard conveyor. In other examples, other devices operable to manoeuvre the first end of the overboard conveyor may additionally or alternatively be used, such as an aileron or a rudder.

[0096] It is to be understood that any feature described in relation to any one example may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the examples, or any combination of any other of the examples. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Claims

CLAIMS1. A recovery system for retrieval of submersible objects onto a vessel, the recovery system comprising a conveyor apparatus, the conveyor apparatus operable to transport received objects from a first end of the conveyor apparatus to a second end of the conveyor apparatus, wherein the first end of the conveyor apparatus is at least partially submersible in water around the vessel such that the conveyor apparatus can receive submersible objects when in a deployed configuration, and wherein the second end is adapted to be mounted to a midship position of the vessel such that submersible objects received by the conveyor apparatus can be transported to the midship position of the vessel.

2. The recovery system of claim 1, wherein the midship position of the vessel corresponds to a centre-of-mass of the vessel or a position of minimal pitching motion of the vessel.

3. The recovery system of claim 1 or claim 2, wherein the second end of the conveyor apparatus is mounted to the midship position of the vessel by a universal joint.

4. The recovery system of any previous claim, wherein the deployed configuration comprises the conveyor apparatus extending alongside the vessel.

5. The recovery system of any previous claim, wherein the recovery system further comprises deployment apparatus operable to manoeuvre the conveyor apparatus to the deployed configuration.

6. The recovery system of claim 5, wherein the deployment apparatus comprises a winch device.

7. The recovery system of claim 5 or 6, wherein when the conveyor apparatus is in the deployed configuration, the deployment apparatus is operable to manoeuvre the first end of the conveyor apparatus between different positions.

8. The recovery system of any one of claim 5 to 7, wherein the deployment apparatus is operable to manoeuvre the conveyor apparatus between a stowed configuration and the deployed configuration.

9. The recovery system of claim 8, wherein the stowed configuration comprises the first end of the conveyor apparatus being located on a deck of the vessel.

10. The recovery system of claim 8 or 9, wherein the stowed configuration comprises the conveyor apparatus being substantially parallel to a centreline of the vessel11. The recovery system of any previous claim, wherein the conveyor apparatus comprises a first conveyor belt section and a second conveyor belt section arranged in series, such that the second conveyor belt section receives objects transported by the first conveyor belt section.

12. The recovery system of claim 11, wherein the second conveyor belt section is separated from the first conveyor belt section by a separation distance such that submersible objects, received by the first conveyor belt section and being smaller than the separation distance, are not received by the second conveyor belt section.

13. The recovery system of claim 11 or 12, wherein the second conveyor belt section is adapted to be mounted to the midship position of the vessel, and the first conveyor belt section is movably attachable to the second conveyor belt section.

14. The recovery system of claim 13, wherein the second conveyor belt section is operable to transport objects received at the midship position of the vessel to a position on a deck of the vessel.

15. The recovery system of any previous claim, wherein the first end of the conveyor apparatus comprises a funnel for receiving submersible objects onto the conveyor apparatus.

16. The recovery system of claim 15, wherein the funnel comprises a pump configured to pump water towards the first end of the conveyor apparatus.

17. The recovery system of any previous claim, comprising a recovery control system operable to determine a position of the conveyor apparatus.

18. The recovery system of claim 17, wherein the recovery control system is operable to determine a position of a submersible object.

19. The recovery system of claim 17 or 18, wherein the recovery control system is operable to determine current information of the water surrounding the vessel.

20. The recovery system of any one of claim 17 to 19, wherein the recovery control system is operable to communicate determined information to a submersible object.

21. The recovery system of any one of claim 17 to 20 when dependent on claim 8, wherein the deployment apparatus is operable to manoeuvre the conveyor apparatus based on a determination of the recovery control system.

22. The recovery system of any previous claim, wherein the conveyor apparatus comprises steering apparatus, operable to manoeuvre the conveyor apparatus when in the deployed configuration.

23. The recovery system of claim 22 when dependent on any one of claim 17 to 20, wherein the steering apparatus is operable to manoeuvre the conveyor apparatus based on a determination of the recovery control system.

24. The recovery system of claim 22 or 23, wherein the steering apparatus comprises at least one from an aileron, a rudder, thrusters, and a buoyancy device, wherein optionally the buoyancy device is a variable buoyancy device;25. The recovery system of any previous claim, wherein the conveyor apparatus comprises taglines, the taglines attachable to the vessel such that motion of the conveyor apparatus is limited.

26. A vessel comprising the recovery system of any previous claim.

27. A method for recovery of submersible objects onto a vessel, the method comprising providing a conveyor apparatus, a first end of the conveyor apparatus at least partially submersed in the water and a second end of the conveyor apparatus attached to a midship position of the vessel; receiving a submersible object at the first end of the conveyor apparatus; transporting the submersible object to the second end of the conveyor apparatus; receiving the submersible object at the midship position of the vessel.

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