NO20191479A1

NO20191479A1 - Apparatus and Method for Receiving an Underwater Vehicle

Info

Publication number: NO20191479A1
Application number: NO20191479A
Authority: NO
Inventors: Gunnar Brink
Original assignee: Fraunhofer Ges Forschung
Priority date: 2017-06-06
Filing date: 2019-12-13
Publication date: 2019-12-13
Also published as: WO2018224207A1; DE102017209514A1

Description

Apparatus and Method for Receiving an Underwater Vehicle

Description

Embodiments of the present invention relate to an autonomous surface vehicle for receiving an underwater vehicle as well as to a system including a surface vehicle as well as an underwater vehicle. A further embodiment relates to a method for recovering an autonomous underwater vehicle.

Underwater vehicles or autonomous underwater vehicles (AUV) can be recovered in different ways. A common method for recovering the underwater vehicle can be described as follows: When the underwater vehicle emerges, a small buoy floating at the surface and being connected to the AUV via a rope disengages from the same. This is disclosed, for example, in WO 2014/173392 A1. Normally, after the emergence of the AUV and disengagement of the buoy, a kedge anchor having a second rope is shot with a harpoon from the ship across the rope between AUV and buoy and then slowly pulled back in order to grip the rope between buoy and AUV. Here, the rope gets caught with the kedge anchor such that the buoy can be pulled on board. The harpoon is necessary since the same can prevent that the rope is pulled into the propeller drive. This process is very error-prone and extremely time expensive. Additionally, reference is made to EP 2739524 B1.

A further variation known from further prior art is the so-called Calista concept by ifremer. Here, a launch-recovery system is described including a cage floating freely in the water, only secured by a rope. This approach is explained, for example, in WO 2008/012473 A1. By the continuous connection to the mother ship, there are limitations as regard to user friendliness and flexibility. Therefore, there is the need for an improved approach.

It is the object of the present invention to provide an improved concept for recovering underwater vehicles, in particular autonomous underwater vehicles.

This object is solved by the independent claims.

Embodiments of the present invention provide an autonomous surface vehicle for receiving an underwater vehicle having a (e.g., motor-driven) floating body, a pivot arm/cantilever and an optional auxiliary floating body connected to the main floating body via the pivot arm/cantilever. Additionally, the surface vehicle includes means for receiving the underwater vehicle, that are connected e.g., to the pivot arm or the auxiliary floating body that are spaced apart from the main floating body via the pivot arm.

Thus, embodiments of the present invention are based on the knowledge that an underwater vehicle can be caught, for example, at a rope of the same via receiving means, such as a hook projecting into the water via an e.g., laterally projecting boom from the surface vehicle (USV, unmanned surface vehicle). By spacing apart the receiving means and the (motor-driven) main hull of the USV, the danger that the rope gets caught in the ship’s propeller is reduced. Further, due to the fact that the surface vehicle can be independently driven or maneuvered, the ergonomics of the recovery process can be significantly improved. Since the surface vehicle operates autonomously according to a preferred variation, the user comfort is increased further. According to further embodiments, the danger of getting entangled can be reduced further by using a jet propulsion.

According to embodiments, the means for receiving are implemented below the water surface, e.g., one or several meters below the water surface. Here, for example, a hook or a rope floating below water can be used. Since the buoy floats at the surface and consequently the rope extends towards the bottom obliquely to the underwater vehicle, such an arrangement enables reliable gripping of the rope. According to a further embodiment, a winch can be provided, such that after catching the rope or generally after gripping the underwater vehicle, the underwater vehicle can be pulled towards the surface vehicle or can be loaded onto the same by means of this winch.

According to an embodiment, the main floating body of the surface vehicle includes a socalled double hull, possibly also with a gap between the two hulls of the double hull into which the underwater vehicle can be hauled.

According to embodiments, the pivot arm is pivotable to the side, e.g. motor-driven, or is generally pivotable. According to the preferred case, pivoting takes place (e.g., laterally) to the side. Pivoting pursues the idea that the auxiliary floating body is not disposed in a spaced-apart manner while driving through water but can be folded to the main floating body in order to improve maneuverability and water resistance. Pivoting away can either take place by pivoting out of the water or also in parallel to the main floating body. Apart from active motor-driven pivoting, pivoting can be realized, for example, in such a way that pivoting away, for example by releasing the cantilever or a locking mechanism by which the cantilever is fixed to the main floating body, takes place such that the pivot arm is folded to the main floating body while driving through water.

According to further embodiment, the surface vehicle includes a receiver that is configured to receive a signal of the underwater vehicle or a signal of the buoy connected to the underwater vehicle such that he surface vehicle can localize the underwater vehicle. According to further embodiments, maneuvering the surface vehicle to the underwater vehicle or the buoy of the underwater vehicle can take place in dependence on the localization of the underwater vehicle. Here, the control is preferably performed such that the surface vehicle is positioned with respect to the buoy such that the rope between buoy and underwater vehicle can be hauled.

Since the surface vehicle can operate autonomously as discussed above, according to a further embodiment, the same can comprise means for energy generation, such as solar cells or other energy harvesters in order to prolong the operating time (for example on the high seas). This approach can be applied to any USV. In order to be able to sink even on the high seas during a storm, or in order not to have to return to the mother ship during a storm, it is possible, according to embodiments, that the surface vehicle includes a submerging function such that the same can submerge below the water surface in order to be protected from the storm.

A further embodiment relates to a system having a respective surface vehicle as well as an autonomous underwater vehicle including a jettisonable or releasable buoy connected to the autonomous underwater vehicle by means of a rope. As already discussed above, in this case, the means for receiving the underwater vehicle are configured to grip the rope between buoy and autonomous underwater vehicle.

An additional embodiment provides a method for recovering an autonomous underwater vehicle with a jettisonable or releasable buoy, again connected to the autonomous underwater vehicle by means of a rope. In this method, the following steps are performed: “jettisoning or releasing the jettisonable or releasable buoy”, “pivoting out the pivot arm”, “maneuvering the surface vehicle to the buoy” and “engaging the means for receiving the underwater vehicle with the rope of the underwater vehicle”.

Further developments are defined in the subclaims. Embodiments of the present invention will be discussed below with reference to the accompanying drawings. They show:

Fig. 1a a schematic illustration of a surface vehicle according to an embodiment;

Fig. 1b a schematic illustration of the surface vehicle of Fig. 1 together with an autonomous underwater vehicle to be recovered according to a further embodiment; and

Fig. 2a-2d schematic illustrations of a surface vehicle in combination with an underwater vehicle during the recovery process according to a further embodiment.

Before embodiments of the present invention will be discussed below based on the accompanying drawings, it should be noted that the same elements or structures are provided with the same reference numbers such that the description of the same is interapplicable or inter-exchangeable.

Fig. 1a shows a surface vehicle 10 with a main floating body 12, here configured as hull of the surface vehicle 10. A cantilever 14 projects from the main floating body 12. This cantilever 14, for example in the form of a boom or pole is configured in a pivotable manner. For the cantilever 14 not causing too strong a load for the main floating body 12, in particular in the folded out state, an auxiliary floating body 16, for example a small pontoon floating at the water surface is provided, for example at the end of the cantilever 14. This floating body results in the pole 14 not loading the USV too heavily on the side, independent of its length and weight.

According to preferred embodiments, the surface vehicle 10 can be motor-driven, wherein it is assumed in this embodiment that the main floating body 12 is provided with a motor as well as a driving propeller 70 or a jet propulsion. So-called means for receiving an underwater vehicle are arranged spaced-apart from the main floating body 12 or in particular spaced apart from the motor. These means for receiving the underwater vehicle are provided with reference number 18. This arrangement is realized in that the means 18 are provided, for example, at the cantilever 14 or the auxiliary floating body 16. The remote arrangement has the purpose of preventing collision or mutual influencing of the drive 70 with an underwater vehicle to be received. In this embodiment, the receiving means 18 are realized, for example, by an arresting hook projecting below the water surface via a rod. The hook can, for example, engage a rope of an underwater vehicle, in particular an autonomous underwater vehicle.

This process or the cooperation of the underwater vehicle will be discussed with reference to Fig. 1b. Fig. 1b shows the underwater vehicle 10, floating at the water surface 20, wherein the surface water vehicle 10 and an underwater vehicle 30 are in engagement. The surface vehicle 10 floats at the water surface with the two floating bodies 12 and 16 wherein the auxiliary floating body 16 is folded out to the side via the cantilever 14, such that a gap results between the floating bodies 12 and 16. The underwater vehicle 30 is caught by the receiving means 18 of the surface vehicle 10 via a rope 32. Gripping the rope 32 can be simplified or improved when the rope 30 is tightened towards the top via a buoy 34.

The process for recovering or generally for receiving an underwater vehicle will be discussed in detail below with reference to Fig.2a to 2d.

Fig. 2a shows the autonomous underwater vehicle 30 in underwater operation spaced apart from the surface vehicle 10. As can be seen in the underwater vehicle 30, the buoy marked with reference number 34 is not yet disconnected. Regarding the surface vehicle 10, it should be noted that the cantilever 14 is still folded in such that the auxiliary floating body 16 is folded to the main floating body in order to improve maneuverability and to reduce water resistance.

In Fig. 2b, both the autonomous underwater vehicle 30 and the surface vehicle 10 are prepared for the upcoming recovery maneuver. For this, in the underwater vehicle 30, the buoy 34 is jettisoned or released such that the same floats to the surface 20 and the rope 32 tightens accordingly. Releasing the buoy 34 is usually possible during the drive with a biased spring and a fastener. This fastener is released, for example by corroding a wire under tension and releasing a latch. Alternatively, releasing can also take place by means of a servomotor or a length adjuster. The buoy 34 can be released autonomously or via remote control, e.g., via radio, WLAN or acoustic signal transmission through water. An alternative variation of the releasable buoy is the jettisonable buoy, wherein the same is arranged on the underwater vehicle 30, for example, in the form of a so-called pop-off nose. The pop-off nose separates from the AUV 30 when the same penetrates the water surface 20.

Approximately at the same time (e.g., in parallel or shortly before or shortly afterwards) the cantilever 14 of the surface vehicle is folded out, such that the auxiliary floating body 16 or in particular the receiving means 18 are spaced apart.

In a next step, the surface vehicle 10 is maneuvered to the underwater vehicle 30 or in particular the buoy 34 such that, for example, the rope 32 or the buoy 34 can be gripped by means of the receiving means 18. This step is illustrated in Fig. 2c. As can be seen, maneuvering takes place, for example, such that the buoy 34 is in the gap between the two floating bodies 12 and 16 or generally such that the rope 32 comes close to the cantilever 18.

In the next step, the rope 32 is gripped by means of the cantilever 18. This step is illustrated in Fig. 2d. Gripping takes place, for example, such that, for example, the gripping means 18 configured as rod or rope can grip the rope 32 with an anchor, hook or snap hook that is submerged in water. According to embodiments, these gripping means 18 can always be within the water and can be folded out by folding out the cantilever 14 or can be lowered separately (only for the recovery maneuver). Then, the surface vehicle/USV 10 drives with receiving means that are folded out or projecting into the water via the rope 32 that is tightened between the AUV 30 and the buoy 34, such that the anchor of the surface vehicle 10 gets caught in the rope. According to an embodiment, locking is also possible, for example in the case of a snap hook. In the prior art, there are several approaches for such locking mechanisms, such as disclosed by Woods Hole Oceangraphics.

With this process, the danger that the rope 32 entangles in the propeller drive of the USV 10 between buoy 34 and AUV 30 is significantly reduced since the USV or the main hull 12 drives far enough away from AUV 30 and buoy 34, such that no entangling is possible, wherein, however, the rope can still be caught by means of the anchor rod or anchor rope 18.

According to preferred embodiments, the surface vehicle 10 is provided with a receiving apparatus, e.g., hydrophone or radio receiver to the respective CPU for position determination starting from the received signal or the received signals, such that the same can use an emitted signal of the underwater vehicle 30 or buoy 34 for localization of a reading unit. Here, it should be noted that the buoy includes, for example, the respective counterpart, i.e., a transmitter, for example in the form of an acoustic pinger, WLAN or satellite uplink. These positioning means are in particular important for the step illustrated in Fig.2b, since the surface vehicle can in that way determine the position towards which the same is to maneuver. Here, the positioning means can be supplemented by a control such that the same can maneuver the preferably autonomous surface vehicle 10 accordingly (positioning the oars and operating the drive). Preferably, but not necessarily, it is assumed that the USV is normally an unmanned surface vehicle which can either operate autonomously or is remote-controlled.

Starting from the step illustrated in Fig. 2d, according to further embodiments, it can be possible that the rope is hauled, for example by means of a winch, such that the AUV 30 is directly coupled to the USV or even received by the same. Receiving the AUV 30 into the USV 10 is, for example, possible when the USV 10 is configured as so-called SWATH having two hulls. Here, the AUV is pulled into a cage or onto a net (between the two hulls of the USV 10).

After the recovery process, the USV 10 drives, together with the fixed AUV 30, to a mother ship or to the shore and can be commercially recovered or pulled itself by means of a crane with a hook or clamping jaws. According to a further variation it would be possible that the USV 10 remains at sea. Here, according to embodiments, it is advantageous when the USV 10 comprises means for current supply, such as an energy harvest in the form of solar cells, wave energy converter or a windmill such that the same can be used at sea for weeks, months or years in an unmanned manner. According to further embodiments, it would also be possible that the USV 10 or any USV is configured as so-called semi-submersible, so that the same can submerge during a storm and remains in silent water, e.g., five meters below the water surface 20 until the storm is over. In that way, the USV 10 can operate independent of the mother ship.

With reference to Fig.1, it should be noted that folding out is herein described as laterally folding out, i.e., such that the cantilever 14 and hence also the second floating body 16 move parallel to the water surface. Different trajectories would be possible, for example a circular path around a circular joint or also in combination with a shift of the auxiliary floating body along the main floating body. Alternatively, a trajectory would be possible according to which the cantilever is folded to the main floating body at first and then the auxiliary floating body or generally the element carrying the means for receiving are offset towards the rear, such that, for example in the case of a two-hull concept, the AUV can be pulled into the USV. Here, it should also be noted that obviously any other deflecting movements, such as to the top (out of the water) or to the front, would be useful. Pivoting can be supported, according to embodiments, by a pivoting and/or locking mechanism connecting the cantilever to the main floating body and being configured to pivot the auxiliary floating body away from the main floating body or pivot the same towards the main floating body and/or to fix the cantilever in the pivoted-out and/or folded-in position.

The deflection movement can, for example, be motor-driven or can also be controlled by means of locking. Here, folding out and folding in can be performed by releasing the cantilever and controlling the main floating body by a motor in such a direction that the cantilever is folded in and out.

Another embodiment provides a system including an above described USV and AUV.

According to a further embodiment, a method as discussed in particular with respect to Fig. 2a to 2d is provided.

Although some aspects have been described in the context of an apparatus, it is obvious that these aspects also represent a description of the corresponding method, such that a block or device of an apparatus also corresponds to a respective method step or a feature of a method step. Analogously, aspects described in the context of a method step also represent a description of a corresponding block or detail or feature of a corresponding apparatus. Some or all of the method steps may be performed by a hardware apparatus (or using a hardware apparatus), such as a microprocessor, a programmable computer or an electronic circuit. In some embodiments, some or several of the most important method steps may be performed by such an apparatus.

Claims

1. Autonomous surface vehicle (10) for receiving an underwater vehicle (30) comprising:

a main floating body (12);

a pivot arm (14); and

means (18) for receiving the underwater vehicle (30) that are spaced apart from the main floating body (12) via the pivot arm (14).

2. Autonomous surface vehicle (10) according to claim 1, wherein the main floating body (12) is motor-driven.

3. Autonomous surface vehicle (10) according to claim 1 or 2 including an auxiliary floating body (16) connected to the main floating body (12) via the pivot arm (14).

4. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the pivot arm (14) is pivotable or motor-pivotable; and/or

wherein the pivot arm (14) is connected to the main floating body (12) via a pivot and/or a locking mechanism, wherein the pivot and/or locking mechanism is configured to pivot the auxiliary floating body (16) away from the main floating body (12) and to pivot the same towards the main floating body (12) and/or to fix the same in the pivoted-out position.

5. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the pivot arm (14) is configured to be folded in in an unlocking state due to the main floating body (12) driving through water (20).

6. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the means (18) for receiving are arranged below the water surface.

7. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the means (18) for receiving comprise a hook for a floating rope (32) of the underwater vehicle (30).

8. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the means (18) for receiving comprise a rod projecting into the water (20) or a rope (32) floating below the water (20).

9. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the means (18) for receiving comprise a winch or other means (18) for hauling the underwater vehicle (30).

10. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the surface vehicle (10) comprises a receiver that is configured to receive a signal of the underwater vehicle (30) or a buoy (34) connected to the underwater vehicle (30) to localize the underwater vehicle (30) or the buoy (34) connected to the underwater vehicle (30) and to receive a position signal for the underwater vehicle (30) or the buoy (34) of the underwater vehicle (30) in that way.

11. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the surface vehicle (10) comprises a control that is configured to control the motor-driven main floating body (12) such that the surface vehicle (10) is maneuvered in dependence on the position signal for the underwater vehicle (30) or for the buoy (34).

12. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the main floating body (12) includes a double hull and/or wherein the main floating body (12) includes a double hull with a gap and the gap is configured to receive the underwater vehicle (10).

13. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the surface vehicle (10) is configured to submerge below the water surface.

14. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the surface vehicle (10) is autonomous and/or includes means (18) for energy generation.

15. Autonomous surface vehicle (10) according to one of the preceding claims, wherein the motor-driven main floating body (18) includes a jet propulsion.

16. System comprising an autonomous surface vehicle (10) according to one of the preceding claims as well as an autonomous underwater vehicle (30) including a jettisonable or releasable buoy (34) connected to the autonomous underwater vehicle (30) via a rope (32),

wherein the means (18) for receiving the underwater vehicle (30) are configured to come into engagement with the rope (32) between buoy (34) and autonomous underwater vehicle (30).

17. Method for recovering an autonomous underwater vehicle (30) with a jettisonable or releasable buoy connected to the autonomous underwater vehicle (30) via a rope (32) by using an autonomous surface vehicle (10) according to one of claims 1 to 15, comprising:

jettisoning or releasing the jettisonable or releasable buoy (34);

pivoting the pivot arm (14);

maneuvering the surface vehicle (10) to the buoy (34); and

engaging the means (18) for receiving the underwater vehicle (30) with the rope (34) of the underwater vehicle (30).