AU2022256222A1

AU2022256222A1 - Submersible drone system

Info

Publication number: AU2022256222A1
Application number: AU2022256222A
Authority: AU
Inventors: Aodh Mchugh; Sam Rowe
Original assignee: M&r Solutions Pty Ltd
Current assignee: M&r Solutions Pty Ltd
Priority date: 2021-10-24
Filing date: 2022-10-21
Publication date: 2023-05-11

Abstract

A system includes a submersible drone comprising a payload, a propulsion system and a navigation system for determining the drone's position relative to a reference position. The drone comprises a magnet for attaching the drone to a submerged ferromagnetic surface of an object. A targeting system comprises a rangefinder for measuring a relative distance between the rangefinder and the object, and an orientation device for determining a relative bearing from the orientation device to the object. A wireless communication system communicatively connects the targeting system and drone together. A guidance system generates drive instructions based on telemetry data, the data including the position, reference position, relative distance and bearing, received in whole or in part via the wireless communication system. A drone control system controls the propulsion system in accordance with the drive instructions to move the drone to the object to attach the magnet to the surface. 2/7 00 C.0 N IlL CI 0 CD I, D N 0 I00 NN 1 I CE T-I

Description

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T-I SUBMERSIBLE DRONE SYSTEM

Field

[0001] The present invention relates to submersible drones and, more particularly, a submersible drone system for attaching and/or detaching payloads to or from aquatic objects and structures, such as hulls of watercraft.

Background

[0002] Explosive payloads may be attached to aquatic objects and structures for military purposes in times of conflict. For example, a limpet mine is a type of naval mine that magnetically attaches to the hull of a hostile target watercraft. A limpet mine is conventionally attached to the target manually by a highly skilled naval diver who must operate in a non-permission or semi-permissive aquatic environment.

[0003] Modern military vessels can easily defend against manually-deployed limpet mines, and similar explosive payloads, using a variety of inexpensive countermeasures. For example, high-powered sonar devices can be used to emit powerful sound waves that expose a naval diver to a high level of lethal risk. High value military vessels, such as aircraft carriers, are often protected using such countermeasures to the point that the ability for an individual diver to gain physical access to the vessel is not feasible.

[0004] Modern military technology has seen an explosion in the development of autonomous vehicles in the land and air battle spaces. The development of autonomous warfare in the maritime sector has, however, remained largely stagnant, including because of the poor inherent ability of GPS signals and radio frequency transmissions to propagate through salt water.

[0005] The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

Summary

[0006] According to the present disclosure, there is provided a submersible drone system for attaching or detaching a payload to or from an aquatic object or structure in a body of water, wherein the system comprises: a submersible drone comprising the payload, wherein the submersible drone includes a propulsion system and a navigation system, wherein the navigation system is configured to generate position information that includes a current position of the submersible drone below a waterline of the body of water relative to an initial reference position, and at least one magnet for magnetically attaching the submersible drone to a ferromagnetic surface of the object or structure below the waterline; a targeting system that comprises a rangefinder for measuring a relative distance between the rangefinder and the object or structure above the waterline, wherein the targeting system also comprises an orientation device for determining a relative bearing from the orientation device to the object or structure; a wireless communication system for communicatively connecting the targeting system and the submersible drone together through the body of water; a drone guidance system configured to generate drive instructions for the submersible drone based on telemetry data, wherein the telemetry data includes at least the position information, the initial reference position, the relative distance and the relative bearing, and wherein the drone guidance system receives the telemetry data, in whole or in part, from the submersible drone and/or targeting system by the wireless communication system; and a control system provided on the submersible drone, wherein the control system operatively controls the propulsion system in accordance with the drive instructions to move and guide the submersible drone to the object or structure such that the magnet attaches to the ferromagnetic surface.

[0007] The navigation system may calculate the current position of the submersible drone relative to the initial reference position by dead reckoning.

[0008] The navigation system may comprise an inertial navigation system to perform the dead reckoning.

[0009] The drone guidance system may be deployed on the targeting system. In such examples, the drone guidance system receives the position information remotely from the submersible drone by the wireless communication system, and the control system receives the drive instructions from the targeting system by the wireless communication system.

[0010] The drone guidance system may be deployed on the submersible drone. In such examples, the drone guidance system receives at least the relative distance and the relative bearing from the targeting system by the wireless communication system. The drone guidance system may be implemented on the control system.

[0011] The submersible drone may comprise an electrical conductor arranged relative to the magnet, wherein the conductor is configured such that when an electrical current flows through the conductor the magnet is caused to change in magnetic polarity causing the submersible drone to detach from the ferromagnetic surface.

[0012] The control system may cause the electrical current to flow through the conductor in response to a drone control instruction. The drone control instruction may be received by the control system from the targeting system by the wireless communication system. In other examples, the drone control instruction may be received by the control system from a satellite by a satellite receiver on the submersible drone.

[0013] The magnet may comprise a neodymium magnet.

[0014] The submersible drone may comprise a head that comprises the magnet and a tail that comprises the payload, wherein the tail is pivotably connected to the head to move pivotably between an extended condition and a stowed condition.

[0015] In the stowed condition, the tail may be longitudinally aligned substantially parallel with the ferromagnetic surface when the head is attached to the ferromagnetic surface by the magnet.

[0016] The tail may comprise one or more magnets configured to attach the tail to the ferromagnetic surface when the tail is in the stowed condition.

[0017] The magnets may be provided on a pair of opposed lateral sides of the tail.

[0018] The control system may cause the tail to move pivotably from the extended condition into the stowed condition automatically when the magnet at the head of the submersible drone attaches to the ferromagnetic surface.

[0019] The head may comprise the control system and the navigation system. The tail may comprise the payload and the propulsion system.

[0020] The wireless communication system may comprise an acoustic messaging system.

[0021] The acoustic messaging system may comprise a buoy deployable in water, wherein the buoy is communicatively connected to the targeting system, and wherein the buoy and the submersible drone each comprise an audio emitter for sending acoustic signals and a hydrophone for receiving acoustic signals.

[0022] The payload may comprise an explosive charge.

[0023] The control system may cause the explosive charge to detonate in response to a detonation instruction. The detonation instruction may be received by the control system from the targeting system by the wireless communication system. In other examples, the detonation instruction may be received by the control system from a satellite by a satellite receiver on the submersible drone.

[0024] The payload may be removably secured to the submersible drone.

[0025] The payload may comprise a GPS receiver system and a satellite transmitter, wherein the GPS receiver system is configured to determine an absolute geographical position of the submersible drone, and wherein the satellite transmitter is configured to transmit the absolute geographical position remotely to a receiver device.

[0026] The payload may comprise a pair of electrodes, wherein the electrodes are configured to engage with the ferromagnetic surface and to supply an electrical current through the ferromagnetic surface between the electrodes to detach an object that is magnetically attached to the ferromagnetic surface.

[0027] The present disclosure also provides a method for detaching a hostile payload that is magnetically attached to a ferromagnetic surface of an aquatic object or structure, wherein the method comprises: using the system described above to drive the submersible drone such that the magnet at the head of the submersible drone attaches to the ferromagnetic surface and such that the pair of electrodes engage the ferromagnetic surface either side of the hostile payload; and using the system to supply an electrical current through the ferromagnetic surface between the electrodes to cause the hostile payload to detach from the ferromagnetic surface.

Brief Description of Drawings

[0028] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: FIG. 1 is a schematic side elevation of a submersible drone system for attaching or detaching a payload to or from an aquatic object or structure according to an example embodiment of the invention; FIG. 2 is a schematic plan view of the system; FIG. 3 is an isometric view of a submersible drone included in the system, wherein a tail of the submersible drone is in an extended condition; FIG. 4 is an isometric view of the submersible drone, wherein the tail is in a stowed condition; FIG. 5 is a plan view of the submersible drone, wherein the tail is in its extended condition;

FIG. 6 is a plan view of the submersible drone, wherein the tail is in its stowed condition; and FIG. 7 is a partial plan view of a boat hull wherein a head of the submersible drone is magnetically attached to the hull, and wherein the tail is shown pivoting from its extended condition into its stowed condition.

Description of Embodiments

[0029] Referring to FIGS. 1 to 7, an example embodiment of the present invention provides a submersible drone system 10 for attaching and/or detaching a payload 12 to or from an aquatic object or structure 14 in a body of water. The system 10 includes a submersible drone 16 that comprises the payload 12, a propulsion system 18 and a navigation system 20. The navigation system 20 is configured to generate position information that includes a current position of the submersible drone 16 below a waterline 22 of the body of water relative to an initial reference position 24. The submersible drone 16 also comprises at least one magnet 26 for magnetically attaching the submersible drone 16 to a ferromagnetic surface 28 of the object or structure 14 below the waterline 22.

[0030] The system 10 comprises a targeting system 30 that comprises a rangefinder for measuring a relative distance between the rangefinder 30 and the object or structure 14 above the waterline 22. This distance is labelled 'd' in FIGS. 1 and 2. The targeting system 30 also comprises an orientation device for determining a relative bearing from the orientation device 30 to the object or structure 14. This bearing is labelled 'a' in FIG. 2. The system 10 also comprises a wireless communication system 32 for communicatively connecting the targeting system 30 and the submersible drone 16 together through the body of water.

[0031] The system 10 comprises a drone guidance system that is configured to generate drive instructions for the submersible drone 16 based on telemetry data. The telemetry data includes, at least: (i) the position information generated by the navigation system 20, (ii) the initial reference position 24, (iii) the relative distance d and (iv) the relative bearing a. The drone guidance system receives the telemetry data, in whole or in part, from the submersible drone 16 and/or targeting system 30 by the wireless communication system 32. In the example depicted, the drone guidance system is deployed on the targeting system 30 and is, therefore, implemented by a controller device of the targeting system 30. The drone guidance system obtains the position information remotely from the submersible drone 16 via the wireless communication system 32, and has local access to the values of d and a as measured by the targeting system 30. Furthermore, the drone guidance system transmits the drive instructions that it generates to the submersible drone 16 via the wireless communication system 32.

[0032] A control system is provided on the submersible drone 16. The control system operatively controls the propulsion system 18 of the drone 16 in accordance with the drive instructions generated by the drone guidance system. The drive instructions cause the control system to move and guide the submersible drone 16 to the object or structure 14 such that the magnet 26 attaches to the ferromagnetic surface 28.

[0033] More particularly, in the example depicted the object or structure 14 comprises a watercraft that has a hull that is partially submerged below the waterline 22. The targeting system 30 comprises an apparatus mounted on a boat 34 that integrally comprises the rangefinder and orientation device. In other examples, the targeting system 30 may comprise a handheld mobile device that can be used on or from any fixed or moveable object, structure or location, such as from a quayside or headland within range of the target watercraft 14. The rangefinder may comprise a laser rangefinder, also commonly known as a laser telemeter, that measures the changeable distance, d, between the boat 34 and watercraft 14 on an intermittent or continuous basis. The laser rangefinder may operate on a time of flight principle wherein a monocular of the rangefinder emits a laser pulse to a side of the watercraft 14 and then measures the time taken for the pulse to be reflected off the watercraft 14 and returned to the rangefinder.

[0034] The orientation device of the targeting system 30 may comprise an electronic or electromechanical device that is capable of measuring the changeable relative bearing, 'a', between the targeting system 30 and watercraft 14 on an intermittent or continuous basis. For example, the orientation device may comprise a gyroscope-based orientation device, such as a gimbal-based gyroscope, a mutually orthogonal fibre-optic gyroscope (FOG) or a set of mutually orthogonal micro electronic mechanical system (MEMS) devices. The orientation device may be configured to measure the angle, a, relative to a reference bearing that is stored or measured by the device. For example, the reference bearing may be an absolute bearing, such as true north or magnetic north. In the example depicted, the bearing, a, is measured relative to magnetic north, labeled 'N' in FIG. 2. In other examples, the bearing, a, may be measured relative to some other particular reference bearing that is taken and stored by the orientation device during a startup and calibration procedure.

[0035] Because the targeting system 30 is mounted on a boat 34, the absolute geographical position of the targeting system 30 may change, in addition to relative distance 'd', when the drone 16 is transiting underwater toward the watercraft 14. Similarly, the geographical position and the orientation of the watercraft 14 may change while the drone 16 is transiting. To account for any such changes, in the example depicted the targeting system 30 may also comprise a GPS receiver that is used to determine its current absolute geographical position at any one point in time. The targeting system 30 will generate the drive instructions for the drone 16 based on its current absolute geographical position, the position information received from the drone 16, the initial reference position 24 and the relative distance d and the relative bearing a.

[0036] The navigation system 20 on the submersible drone 16 may be an inertial navigation system that calculates the drone's current position at any one point in time relative to the initial reference position 24 by dead reckoning. For example, the navigation system 20 may comprise one or more motion sensors, such as MEMS accelerometers, and rotation sensors, such as gyroscopes, to measure acceleration/deceleration of the drone 16 and changes in its orientation compared to its initial orientation over time. The system 20 may take such measurements and use them to calculate an estimate of the relative drone position by dead reckoning on an intermittent or continuous basis. The drone 16 may record the initial reference position 24, and the drone's initial velocity and orientation, during a startup and calibration procedure. The startup and calibration procedure may be executed when the drone 16 is aligned next to the targeting system 30 on the boat 34 or when the drone 16 is first placed into the water over the side of the boat 34.

[0037] The wireless communication system 32 may comprise an acoustic messaging system that includes a buoy deployable in water that is communicatively connected to the targeting system 30. The buoy 32 may be attached to the boat 34 by a tether that includes a communications cable. In such examples, the buoy 32 comprises an audio emitter for sending acoustic signals generated by the targeting system 30 through the water to the drone 16. The drive instructions generated by the targeting system 30 may be encoded in these acoustic signals in encrypted form. The buoy 32 also comprises a hydrophone for receiving acoustic signals generator by the drone 16 that are forwarded by the buoy 32 to the targeting system 30. The position information generated by the drone's navigation system 20 may be encoded in these acoustic signals in encrypted form. The drone 16 may also comprise an audio emitter and hydrophone for sending/receiving acoustic signals to/from the targeting system 30 via the buoy 32. The acoustic signals may be sent in ultra-low frequencies to allow them to propagate through the water over significant distances in excess of 1,000km.

[0038] Referring to FIGS. 3 to 7, the drone 16 may comprise a head 36 and a tail 38 that are pivotably connected together by a hinge joint 40. The magnet 26 may be disposed on a frontmost surface of the head 36 and the propulsion system 18 may be disposed at a rearmost end of the tail 38. As illustrated in FIG. 7, the hinge joint 40 may be configured such that the tail 38 is pivotable about ninety degrees 90° relative to the head 36 between an extended condition (label 42) and a stowed condition (label 44) when the head 36 is magnetically attached to the surface 28 of the watercraft 14. In the extended condition, the tail 38 may be longitudinally aligned with the head 36 so that the drone 16 is generally symmetrical along its longitudinal axis. When the head 36 is attached to the surface 28, in the extended condition the tail 38 extends away from the surface 28 perpendicularly. When the tail 38 has swung into its stowed condition, the tail 38 is longitudinally aligned parallel with the surface 28.

[0039] The drone 16 may comprise one or more actuators, such as electric rotary or linear actuators, that move the tail 38 pivotably between its extended and stowed condition. The drone's control system 46 may be deployed in the head 36 and be operatively connected to the actuators. The control system 46 may be configured to cause the tail 38 to swing automatically from the extended condition to the stowed condition when the control system 46 detects that the magnet 26 has attached to the surface 28 of the watercraft 14. In another example, the control system 46 may send a notification to the targeting system 30 via the acoustic messaging system 32 when the magnet 26 attaches to the surface 28. In response to receiving the notification, the targeting system 30 may send a control instruction to the drone 16 via the acoustic messaging system 32. The control system 46 may cause the tail 38 to swing into its stowed condition when it receives the control instruction.

[0040] Referring to FIG. 5, the drone's navigation system 20 and control system 46 may be contained inside of the head 36 and the payload 12 may be secured inside or to the tail 38. The propulsion system 18 may comprise a rotatable propeller that is semi enclosed within a chamber 50 at the rear end of the tail 38. A set of actuable vanes (not shown) may also be disposed in chamber 50 that control the direction of water driven by the propeller. The control system 46 may control the orientation of the vanes to steer the drone 16 when it is transiting to the target watercraft 14 through the water. The tail 38 may also comprise one or batteries for powering the various electronic and electrical components of the drone 16. The drone 16 may comprise first and second sets of magnets 52, 54 arranged along respective first and second lateral sides of the tail 38. As illustrated in FIG. 7, each set of magnets 52, 54 may be positioned to secure the relevant lateral side of the tail 38 magnetically to the surface 28 of the watercraft 14 when the tail 38 swings into its stowed condition. The tail 38 may be configured to swing in a clockwise and/or counterclockwise direction relative to the head 36 into the stowed condition to cause the relevant set of magnets 52, 54 to engage with the surface 28.

[0041] The magnet 26 on the head 36 and the magnets 52, 54 on the tail 38 may comprise neodymium magnets. Each magnet may comprise an electrical conductor (not shown) arranged relative to the magnet, such as a copper wire wound around the magnet, such that when an electrical current flows through the conductor the magnet temporarily reverses its polarity thus causing the magnet to detach from the surface 28 of the watercraft 14. The control system 46 may be operatively connected to each of the conductors so that the control system 46 may release the drone 16 from the watercraft 14 when required. The control system 46 may be configured to release the drone 16 when it receives a drone control instruction directing it to do so. The control instruction may be sent to the drone 16 by the targeting system 30 via the acoustic messaging system 32. In another example, the control instruction may be sent to the drone 16 from a satellite in the form of a short burst data transmission that is received by a satellite receiver provided on the submersible drone. In this configuration, an operator who is based at a remote location may cause the drone 16 to be released from the watercraft 14 at a required point in time.

[0042] The control system 46 may comprise a processor, a programmable logic controller (PLC), a programmable logic array (PLA) or similar electronic controller device. The control system 46 may comprise a single integrated electronic controller device or multiple controller devices (including multiple processors or PLAs) connected together via a network, bus or similar communications system.

[0043] The payload 12 may comprise a variety of different objects, devices and/or materials according to the particular purpose that the drone system 10 is used for. For example, the drone system 10 may be used in an offensive configuration wherein the payload 12 comprises an explosive charge or other ordnance for destroying a target military warship 14. In use, the drone 16 may initially be stored on the boat 34 and the boat 34 will be piloted through the water 22 to bring it within operable range of the warship 14. When the boat 34 has reached a suitable position, the drone 16 and targeting apparatus 30 may each be switched on by an operator on the boat 34 and the devices may execute their respective startup and calibration procedures. During the startup phase, the targeting apparatus 30 may determine and record the reference bearing that will subsequently be used to calculate the relative bearing, 'a', between the targeting apparatus 30 and warship 14. The drone 16 may determine and record the initial reference position 24, and the drone's initial velocity and orientation, which will subsequently be used by the drone's navigation system 20.

[0044] The drone 16 may then be lowered into the water 22 by the operator next to the boat 34 with the tail 38 arranged in the extended condition. The operator will then target the warship by aiming the laser beam of the targeting apparatus 30 onto a side 28 of the warship's hull above the waterline 22. Once released, the drone 16 descends to an operational depth and begins to transit towards the warship 14 below the waterline 22. When in transit, the drone 16 continuously or intermittently calculates an estimate of its current position relative to the initial reference position 24 by dead reckoning and transmits this position information to the targeting apparatus 30 via the acoustic buoy 32.

At the same time, the targeting apparatus 30 continuously or intermittently measures the current relative distance, d, and bearing, a, between the boat 34 and warship 14. The targeting apparatus 30 generates the drone drive instructions based on the position information received from the drone 16, the initial reference position 24 and the distance, d, and bearing, a, and transmits the drive instructions to the drone 16 via the acoustic buoy 32. Because the position of the boat 34 in the water is subject to change in the example depicted, the targeting apparatus 30 may also take the boat's absolute geographical position into account when generating the drone drive instructions. The drive instructions are relayed to the drone 16 through the water via the acoustic buoy 32.

[0045] Based on the drive instructions received, the drone's control system 46 controls the propulsion system 18 so that the drone 16 heads toward the surface 28 of the warship's hull that the laser of the targeting apparatus 30 is pointing at. The operator on the boat 34 keeps the laser pointed at the target surface 28 until the drone 16 reaches the warship 14. When the drone 16 is at the surface 28, the magnet 26 at the head 36 attaches itself to the surface 28. Once attached, the tail 38 of the drone 16 swings through 90 degrees into its stowed condition 44, as shown in FIG. 7, so that the magnets 54 on the side of the tail 38 that faces the warship 14 also attach themselves to the surface 28. Moving the tail 38 into its stowed condition 44 provides several advantages, which include: (i) the drone 16 is streamline in shape to minimise the impact of water resistance acting on the drone 16 when the warship 14 is moving through the water in the forward travel direction labelled 60 in FIG. 7; (ii) the shaped explosive charge 12 is positioned close to the surface 28 to maximise the explosive impact; (iii) the drone 16 is less visible when the surface 28 is viewed through the water by a person looking over a side of the warship 14.

[0046] The explosive payload 12 may detonate after a set period of time stored by the drone's control system 46. In other examples, the control system 46 may cause the explosive payload 12 to detonate in response to a relevant control instruction received by the drone 16. The control instruction may be issued by the targeting system to the drone 16 via the acoustic messaging system 32. In another example, the control instruction may be issued from a remote command headquarters via satellite in short burst transmission that is received by a satellite receiver provided on the drone 16. On receiving the control instruction, the control system 46 may initiate a fuse connected to a primer which, in turn, causes the explosive payload 12 to detonate.

[0047] In another example, the drone system 10 may be used in a surveillance and reconnaissance configuration wherein the payload 12 comprises an apparatus equipped with an underwater GPS receiver and satellite transmitter system. More particularly, the GPS system may be configured to determine an absolute geographical position of the drone 16 when the drone 16 is attached to a watercraft 14. The satellite transmitter may periodically transmit the absolute geographical position to a receiver device that is based at a remote command headquarters, thus allowing the geographical position of the watercraft 14 to be tracked and monitored remotely. The underwater GPS system may comprise a pair of antennas that transmit signals through the hull of the watercraft 14 by through-wall electromagnetic wave theory to communicate with GPS satellites. For example, the underwater GPS system may be based on the underwater location tracking system that is disclosed in US Patent Application Publication No. US 2020/0177221 Al published on 4 June 2020 with the title "SUBMERGED MARITIME TAG TRACK AND LOCATE DEVICE AND SYSTEM", the contents of which are incorporated herein by reference. The technology disclosed in the foregoing patent publication may also be used to receive control instructions from a remote command headquarters in examples where the drone 16 is used in an offensive configuration to attach and denote explosive payloads.

[0048] In another example, the drone system 10 may be used in a defensive configuration wherein the payload 12 comprises an apparatus that is used to remove a hostile device, such as magnetic limpet mine, attached magnetically to the side of friendly watercraft. More particularly, the apparatus 12 may comprise a pair of electrodes (not shown) that outwardly protrude from a lateral side of the drone's tail 38. The electrodes may be configured to make contact with the watercraft surface 28 when the tail 38 swings into the stowed condition 44. Once in contact, the electrodes supply an electrical current through the surface 28 between the electrodes.

[0049] In this defensive configuration, the drone system 10 may be used to guide the drone 16 toward the limpet mine so that the head 36 magnetically attaches to the watercraft's hull surface 28 to one side of the mine. The tail 38 may then swing into its stowed condition 44 so that the two electrodes engage the hull surface either side of the mine. The apparatus 12 may then send an electrical current through the hull surface between electrodes. The current alters the magnetic polarity of the hull's surface so that the polarity matches the polarity of the magnetic surface of the mine that is attached to the hull. The polarity change causes the limpet mine to detach from the hull and to descend toward the seabed. The drone 16 may then release itself from the hull and transit back to the boat 34 and/or reference position 24.

[0050] The drone 12 may comprise a modular configuration wherein the payload 12 is removably secured to the tail 38. In this configuration, the payload 12 can be periodically removed, replenished, maintained or replaced depending on the mission profile. It will be appreciated that the drone control system 10 may be used to attach or remove payloads to aquatic objects other than watercraft, including static and moving waterborne objects and structures. For example, the system 10 may be used to attach hostile payloads to submerged metal parts of oil rigs, quaysides or jetties.

[0051] In the examples described above, the guidance system is deployed on the targeting system 30. Accordingly, the drive instructions for the drone 16 are generated on the targeting system 30 and transmitted to the drone 16 through the water via the buoy 32. However, in embodiments the drone 16 may generate its own drive instructions locally. For example, the targeting apparatus 30 may continuously send guidance information to the drone 16 via the buoy 32 that includes the current distance, d, and bearing, a, measured by the targeting apparatus 30 when the drone 16 is in transit. The control system 46 on the drone 16 may implement an integral guidance system that determines its own drive instructions/behaviour for the drone 16. The control system 46, accordingly, determines the drive instructions/behaviour based on the guidance information received from the targeting apparatus 30 and the estimated drone positions calculated by the drone 16 by dead reckoning relative to the initial reference position 24.

[0052] In other embodiments, the drone guidance system may be implemented on an apparatus that is separate to the targeting system 30 and drone 16 and that communicates with such devices via the buoy 32. In such examples, the drone guidance system remotely receives the telemetry data from the targeting system 30 and drone 16 via the buoy 32, and remotely transmits the drive instructions to the drone 16 through the water via the buoy 32.

[0053] Now that example embodiments of the submersible drone system 10 have been described, it will be apparent that it provides a number of advantages over the prior art, including the following:

(i) The autonomous drone 16 allows the relevant payload to be delivered to an aquatic object, and attached and detached to/from a submerged part of the object, from a remote location without exposing the operator to unnecessary risk;

(ii) Once attached, the tail 38 of the drone 16 swings into its stowed position to minimise water resistance drag and make the drone 16 less visible when viewed through the water. In examples where the drone 16 includes an explosive payload, the tail 38 also positions the explosive charge close to the surface 28 of the target;

(iii) The drone 16 can detach itself from the aquatic object in response to a control instruction remotely issued to the drone 16, and transit back to the drone operator;

(iv) A range of different payloads can be attached and detached to aquatic objects using the drone 16. This includes explosive charges for use in combat and electronic and electromechanical systems for reconnaissance and surveillance purposes and for removing hostile devices from boat hulls;

(v) The relevant payload can be attached and detached to/from a range of different aquatic objects and structures. This includes boat hulls and submerged metal parts of floating rigs, jetties, quaysides and other water-based structures.

[0054] The skilled addressee will appreciate that certain features depicted in the figures may be shown for simplicity and clarity and have not necessarily been shown to scale. For example, the dimensions and/or relative positioning of some of the features may be exaggerated relative to other features to facilitate an understanding of the various example embodiments exemplifying the principles described herein. Also, common but well understood features that are useful or necessary in a commercially feasible embodiment may not be depicted in order to provide a less obstructed view of these various examples. It will also be understood that the terms and expressions used herein adopt the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein.

[0055] The location and disposition of the features depicted in the figures may vary according to the particular arrangements of the embodiment(s) as well as of the particular applications of such embodiment(s). References to positional descriptions in this specification are to be taken in context of the relevant example embodiments shown in the Figures and are not to be taken as limiting the scope of the principles described herein to the literal interpretation of the term, but rather as would be understood by the skilled addressee.

[0056] Any method steps, processes and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0057] For the purpose of this specification, the word "comprising" means "including but not limited to", and the word "comprises" has a corresponding meaning. It is to be understood that, if any prior art is referred to herein, such reference does not constitute an admission that the prior art forms a part of the common general knowledge in the art, in Australia or any other country.

[0058] The above embodiments have been described by way of example only and modifications are possible within the scope of the claims that follow.

Claims

1. A submersible drone system for attaching or detaching a payload to or from an aquatic object or structure in a body of water, wherein the system comprises: a submersible drone comprising the payload, wherein the submersible drone includes a propulsion system and a navigation system, wherein the navigation system is configured to generate position information that includes a current position of the submersible drone below a waterline of the body of water relative to an initial reference position, and at least one magnet for magnetically attaching the submersible drone to a ferromagnetic surface of the object or structure below the waterline; a targeting system that comprises a rangefinder for measuring a relative distance between the rangefinder and the object or structure above the waterline, wherein the targeting system also comprises an orientation device for determining a relative bearing from the orientation device to the object or structure; a wireless communication system for communicatively connecting the targeting system and the submersible drone together through the body of water; a drone guidance system configured to generate drive instructions for the submersible drone based on telemetry data, wherein the telemetry data includes at least the position information, the initial reference position, the relative distance and the relative bearing, and wherein the drone guidance system receives the telemetry data, in whole or in part, from the submersible drone and/or targeting system by the wireless communication system; and a control system provided on the submersible drone, wherein the control system operatively controls the propulsion system in accordance with the drive instructions to move and guide the submersible drone to the object or structure such that the magnet attaches to the ferromagnetic surface.

2. The system according to claim 1, wherein the navigation system calculates the current position of the submersible drone relative to the initial reference position by dead reckoning.

3. The system according to claim 2, wherein the navigation system comprises an inertial navigation system to perform the dead reckoning.

4. The system according to claim 1, wherein: the drone guidance system is deployed on the targeting system and receives the position information remotely from the submersible drone by the wireless communication system; and the control system receives the drive instructions from the targeting system by the wireless communication system.

5. The system according to claim 1, wherein the drone guidance system is deployed on the submersible drone, and wherein the drone guidance system receives at least the relative distance and the relative bearing from the targeting system by the wireless communication system.

6. The system according to claim 5, wherein the drone guidance system is implemented by the control system.

7. The system according to any one of the preceding claims, wherein the submersible drone comprises an electrical conductor arranged relative to the magnet such that when an electrical current flows through the conductor the magnet is caused to change polarity causing the submersible drone to detach from the ferromagnetic surface.

8. The system according to claim 7, wherein the control system causes the electrical current to flow through the conductor in response to a drone control instruction, wherein the drone control instruction is received by the control system from either the targeting system by the wireless communication system or from a satellite by a satellite receiver on the submersible drone.

9. The system according to any one of the preceding claims, wherein the submersible drone comprises a head that comprises the magnet and a tail that comprises the payload, wherein the tail is pivotably connected to the head to move pivotably between an extended condition and a stowed condition.

10. The system according to claim 9, wherein in the stowed condition the tail is longitudinally aligned parallel with the ferromagnetic surface when the head is attached to the ferromagnetic surface by the magnet.

11. The system according to claim 10, wherein the tail comprises one or more magnets configured to attach the tail to the ferromagnetic surface when the tail is in the stowed condition.

12. The system according to any one of claims 9 to 11, wherein the control system causes the tail to move pivotably from the extended condition into the stowed condition automatically when the magnet attaches to the ferromagnetic surface.

13. The system according to any one of claims 9 to 12, wherein the head comprises the control system and the navigation system, and wherein the tail comprises the payload and the propulsion system.

14. The system according to any one of the preceding claims, wherein the wireless communication system comprises an acoustic messaging system.

15. The system according to claim 14, wherein the acoustic messaging system comprises a buoy deployable in water, wherein the buoy is communicatively connected to the targeting system, and wherein the buoy and the submersible drone each comprise an audio emitter for sending acoustic signals and a hydrophone for receiving acoustic signals.

16. The system according to any one of the preceding claims, wherein the payload comprises an explosive charge.

17. The system according to claim 16, wherein the control system causes the explosive charge to detonate in response to a drone control instruction, wherein the drone control instruction is received by the control system from either the targeting system by the wireless communication system or from a satellite by a satellite receiver on the submersible drone.

18. The system according to any one of claims 1 to 15, wherein the payload comprises a GPS receiver system and a satellite transmitter, wherein the GPS receiver system is configured to determine an absolute geographical position of the submersible drone, and wherein the satellite transmitter is configured to transmit the absolute geographical position remotely to a receiver device.

19. The system according to any one of claims 1 to 15, wherein the payload comprises a pair of electrodes configured to engage with the ferromagnetic surface and to supply an electrical current through the ferromagnetic surface between the pair of electrodes.

20. A method for detaching a hostile payload that is magnetically attached to a ferromagnetic surface of an aquatic object or structure, the method comprising: using the system according to claim 19 to drive the submersible drone such that the magnet attaches to the ferromagnetic surface and such that the pair of electrodes engage the ferromagnetic surface either side of the hostile payload; and using the system to supply an electrical current through the ferromagnetic surface between the electrodes to cause the hostile payload to detach from the ferromagnetic surface.