COUNTERMEASURE

Abstract

A countermeasure (200) for use against a vehicle having an electric motor comprising at least one magnet. The countermeasure (200) comprises an ejection system (205) comprising a plurality of pieces of magnetic material (203). The ejection system (205) is configured to release the plurality of pieces (203) in response to receipt of a trigger signal (209). Also a method of disrupting the operation of a vehicle having an electric motor comprising at least one magnet using an ejection system (205) containing a plurality of pieces (203) of magnetic material. The method comprises detecting the vehicle; receiving, at the dispersal system, a trigger signal (209); in response to the receipt of the trigger signal (209), the ejection system (205) releasing the plurality of pieces (203); some of the plurality of pieces (203) being attracted to the magnet, sticking to the magnet, and thereby obstructing the motor.

Claims

1. A countermeasure for use against a vehicle having an electric motor comprising at least one magnet, the countermeasure comprising: a dispersal system containing a plurality of pieces of magnetic material, the dispersal system being configured to release the plurality of pieces in response to a trigger signal.

2. A countermeasure according to claim 1, further comprising a control system, wherein the control system is configured to generate the trigger signal.

3. A countermeasure according to claim 1, wherein: the control system comprises a proximity fuse, the proximity fuse being configured to generate the trigger signal in response to detecting that a distance to the vehicle has fallen below a pre-determined threshold; or the control system comprises a time-delay fuse, the time-delay fuse being configured to generate the trigger signal in response to a pre-determined period of time having elapsed since the countermeasure was launched.

4. (canceled)

5. A countermeasure according to claim 1, wherein the dispersal system comprises an ejection system configured to eject the plurality of pieces from the dispersal system.

6. A countermeasure according to claim 5, wherein the ejection system comprises one or more of: a pyrotechnic charge, pressurised gas and/or an ejection mechanism.

7. A countermeasure according to claim 1, wherein the dispersal system comprises a container within which the plurality of magnetic pieces are contained.

8. A countermeasure according to claim 1, wherein the container comprises one or more openings via which pieces of magnetic material can exit the container and the dispersal system comprises one or more lids mounted for movement relative to an opening between a first position in which the lid covers the opening and a second position in which the lid does not cover the opening.

9. A countermeasure according to claim 1, wherein the pieces are sized and shaped to be ingested into the electric motor.

10. A countermeasure according to claim 1, wherein the vehicle comprises an aircraft, for example one of: a rotary wing aircraft, and a fixed wing aircraft, and an unmanned air system.

11. (canceled)

12. A countermeasure according to claim 9, wherein the vehicle comprises an unmanned air system less than 25 kg in mass.

13. A countermeasure according to claim 1, wherein the electric motor comprises one of: an AC motor, a DC motor, a brushless AC motor, a brushless DC motor, and a permanent-magnet synchronous motor.

14. A countermeasure according to claim 1, wherein: the countermeasure is mounted on a missile or an aircraft; or the dispersal system forms part of a grenade.

15. (canceled)

16. A missile comprising a countermeasure according to claim 1.

17. A method of disrupting the operation of a vehicle having an electric motor comprising at least one magnet using a countermeasure comprising a dispersal system containing a plurality of pieces of magnetic material, the method comprising: the dispersal system releasing the plurality of pieces in response to a trigger signal; and some of the plurality of pieces being attracted to the magnet and thereby obstructing the motor.

18. A method according to claim 17, further comprising detecting that a trigger condition has been met and, in response to the detecting, transmitting the trigger signal to the dispersal system.

19. A method according to claim 18, wherein detecting that the trigger condition has been met comprises: determining that a distance to the vehicle has fallen below a pre-determined threshold; or determining that a pre-determined period of time has elapsed since launch of the countermeasure.

20. (canceled)

21. A method according to claim 17, wherein being attracted to the magnet comprises being ingested into the electric motor through an air intake.

22. A method according to claim 17, wherein releasing the plurality of pieces comprises creating an airburst to disperse the plurality of pieces.

23. A method according to claim 22, wherein: the dispersal system comprises a pyrotechnic charge and creating the airburst comprises detonating the pyrotechnic charge; or the dispersal system comprises a container of pressurised gas and creating the airburst comprises releasing the pressurised gas.

24. (canceled)

25. A method according to claim 17, wherein the electric motor further comprises a rotor, a stator, and an air gap between the rotor and the stator, and wherein the plurality of pieces obstruct the motor by at least partially filling the air gap.

Description

DESCRIPTION OF THE DRAWINGS

[0040] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:

[0041] FIG. 1 shows a schematic view of a typical brushless DC motor of the prior art;

[0042] FIG. 2 shows a schematic view of a countermeasure according to a first embodiment of the invention;

[0043] FIG. 3 shows a schematic view of a countermeasure according to a second embodiment of the invention;

[0044] FIG. 4 shows a schematic view of the motor of FIG. 1 having been subjected to the countermeasure of the first embodiment;

[0045] FIG. 5 shows a missile according to a third embodiment of the invention; and

[0046] FIG. 6 shows a flow chart illustrating the steps of a method according to a fourth embodiment of the invention.

DETAILED DESCRIPTION

[0047] FIG. 2 shows a schematic view of a countermeasure 200 according to a first embodiment of the invention. The countermeasure 200 comprises a container 201 holding a plurality of pieces 203 of magnetic material. The container 201 is arranged to receive and retain the plurality of pieces 203.

[0048] In this example embodiment, the pieces 203 comprise iron filings. However, it will be appreciated that the pieces 203 need not necessarily be filings. In alternative embodiments, the pieces 203 may comprise one or more of filings, shavings, chips, ball bearings, and swarf. It may be that the pieces 203 are a by-product of a filing or machining operation. Alternatively, the pieces 203 may be specifically manufactured for use in the countermeasure. It will be appreciated that the plurality of pieces 203 need not necessarily all be the same, and therefore that the plurality of pieces could comprise any combination of the above described alternatives.

[0049] In alternative embodiments, the pieces 203 may be made of materials other than iron. In such embodiments, the pieces may be formed of any magnetic material, for example iron, nickel, cobalt, or aluminium. In some embodiments, the pieces are formed of one or both of ferromagnetic and ferrimagnetic materials. Ferromagnetic and ferrimagnetic materials are both attracted to magnets. Thus, in some embodiments in which the pieces comprise one or both of ferromagnetic and ferrimagnetic materials, a greater number of the pieces may be ingested into the motor due to their attraction to the magnet in the motor. Such embodiments may therefore provide a more reliable and/or effective countermeasure. Again, the plurality of pieces 203 need not necessarily be uniform and, in some embodiments, may comprise a mixture of pieces formed of different materials. Additionally or alternatively, countermeasures in accordance with the present embodiments may provide a mechanically simple and/or cost effect countermeasure for use against vehicles with electric motors, for example drones.

[0050] Whilst in FIG. 1 the pieces 203 of magnetic material are shown as being circular, it will be appreciated that FIG. 1 is a schematic representation of countermeasure 200 and that the pieces need not be circular or spherical. For example, the pieces 203 may be spherical, cuboidal, pyramidal, or indeed any other shape, regular or irregular. In some embodiments of the invention, the plurality of pieces 203 may be any size and shape suitable for being ingested into a target electric motor. The possible sizes and shapes of the pieces 203 is therefore determined by the size and form of the target motor and/or vehicle.

[0051] In some embodiments, each of the plurality of pieces 203 has a maximum length of less than 2.5 mm, preferably 1 mm, more preferably less than 0.5 mm, yet more preferably less than 0.25 mm. In some embodiments, each of the plurality of pieces has a maximum length of less than 0.025 mm, preferably 0.05 mm, more preferably 0.1 mm, yet more preferably 0.5 mm. In some embodiments, the plurality of pieces 203 are each of substantially identical size and shape. Embodiments in which the plurality of pieces 203 are of substantially uniform size and shape may be particularly effective against motors of a particular type and/or size. Such embodiments can therefore be said to be specialised for use against that particular type and/or size of motor. In alternative embodiments, the plurality of pieces 203 are of non-uniform size and shape. It may be that filings of certain size are more suitable for disrupting electric motors of a given size, for example depending on the size of the motor's air gap. Embodiments in which the plurality of pieces 203 vary in size and shape may therefore be suitable for use against a range of different motor types and sizes.

[0052] A pyrotechnic charge 205 is located within the container 201. In other embodiments a compressed gas charge may be used. In yet further embodiments, an ejection mechanism may be used. Pyrotechnic charge 205 is located within the container however it need not necessarily be so and, in alternative embodiments, may be located outside of the container 201 (for example adjacent to the container 201). Countermeasure 200 further comprises a control system 211 connected to pyrotechnic charge 205 to provide a trigger signal 209 to the charge. In other embodiments, control system 211 may be absent, and a user may provide a trigger signal to the pyrotechnic charge 205 directly.

[0053] In operation, the control system 211 monitors one or more conditions in order to determine that a firing condition is met. The one or more conditions may, for example, comprise a maximum distance to a target vehicle and/or a minimum elapsed time (for example, since the maximum distance criteria was satisfied). Upon detecting that the firing condition is met, the control system 211 transmits a trigger signal 209 to the pyrotechnic charge 205 causing the charge to detonate thereby dispersing the plurality of pieces 203 of magnetic material. The pieces 203 are attracted to the magnet in the electric motor of the target vehicle, entering the electric motor through an air intake in the motor. The pieces 203 then stick to and build up on the magnet, filling the air gap between the rotor and the stator and thereby physically obstructing rotation of the rotor. Thus, the electric motor is no longer able to turn and therefore can no longer propel the target vehicle. Such embodiments can be said to actively eject the plurality of pieces 203 from the container 201, and therefore to comprise an active dispersal system. In some embodiments, the pieces 203 do not stick directly to the magnet, but instead stick to an intervening material. For example, the magnet may be covered by non-magnetic sheath. In such a case, the magnetic field generated by the magnet may permeate through the sheath and thus the pieces 203 are still attracted to the magnet. Therefore, rather than directly sticking to the magnet, the pieces 203 may instead stick to the sheath, where they may still obstruct rotation of the motor.

[0054] In example embodiments, the control system 211 may comprise a fuse. In some embodiments, the fuse 211 may comprise a proximity fuse. Thus, the fuse 211 may be configured to generate the trigger signal 209 in response to detecting that a distance to a target vehicle has fallen below a pre-determined threshold. In such embodiments, the trigger condition comprises a maximum distance to the target vehicle. Alternatively or additionally, the fuse 211 may comprise a time-delay fuse. In such embodiments, the trigger condition may comprise a minimum elapsed time since launch of the countermeasure. Thus, the fuse 211 may be configured to generate the trigger signal 209 in response to a pre-determined period of time having elapsed since the countermeasure 200 was launch. For example, in some embodiments wherein the countermeasure forms part of a grenade, the pre-determined period of time may run from release of the safety lever of a handheld grenade or from the launch of the grenade from a grenade launcher. Thus, in some embodiments the control system 211 may receive a launch signal, for example a user input and/or input from a command and control system that activates the control system 211, the control system 211 then triggering the dispersal of the magnetic pieces once the firing condition has been met.

[0055] Launch of the countermeasure 200 may be determined by detecting the loss of a connection signal received by the countermeasure 200 from a launch platform, for example a grenade launcher or an aircraft. Alternatively or additionally, launch may be determined by detecting that the countermeasure 200 has undergone an acceleration corresponding to the launch of the countermeasure. For example, the control system 211 may be configured to determine that the countermeasure has been launched by detecting an acceleration undergone by a grenade comprising the countermeasure 200 when fired from a grenade launcher or by detecting an acceleration resulting from the firing of a motor of a missile comprising the countermeasure 200. In some embodiments, the trigger condition comprises detection of a pre-determined user input. Thus, the control system 211 may be configured to generate the trigger signal 209 in response to a received user input. In some embodiments, the trigger condition may comprise a combination of multiple of the above listed conditions. For example, in some embodiments, the control system 211 may generate the trigger signal only when both a distance to a target vehicle has fallen below a pre-determined threshold and a pre-determined period of time having elapsed since the countermeasure 200 was fired. In some embodiments, the control system 211 may be configured to also require that one or more safety related requirements be met before generating the trigger signal 209. For example, the control system 211 may be configured to only generate the trigger signal if it has previously detected an acceleration corresponding to launch of a system comprising the countermeasure 200. The required acceleration may, for example, correspond to firing of a grenade comprising the countermeasure 200 from a grenade launcher or to launching of a missile comprising the countermeasure 200.

[0056] In some embodiments, the countermeasure 200 may comprise part of or be mounted on a missile or an aircraft. For example, the countermeasure may be carried by a helicopter or by a drone. In alternative embodiments, the countermeasure 200 may comprise part of or be mounted on a projectile, for example a grenade.

[0057] In some embodiments, the countermeasure is configured to create an airburst of the plurality of pieces 203. An airburst will be understood by the skilled person to mean an airborne explosion of the plurality of pieces 203, such that the plurality of pieces are dispersed to form a cloud of the pieces 203. In such embodiments, the countermeasure may comprise means of launching the container 201 prior to release of the particles. Thus, the countermeasure may comprise a launch platform for the container. The launch platform may comprise a pyrotechnic charge, or a source of pressurised gas. Detonating the pyrotechnic charge or releasing the pressurised gas launches the container 201.

[0058] In some embodiments, the dispersal system 204 comprises a release mechanism for the container 201 such that the plurality of pieces 203 are allowed to egress the container 201, but are not actively ejected from the container 201 by ejection system 205. Such embodiments can be said to provide passive dispersal of the plurality of pieces 203, and therefore to comprise a passive dispersal system. It will be appreciated by the skilled person that, in this context, passive is intended to mean that an ejection system 205 does not comprise exert a force to propel the plurality of pieces 203 from the container 201.

[0059] FIG. 3 shows a schematic view of a countermeasure 300 according to a second example embodiment of the invention. Those elements of the second embodiment that correspond to similar elements of the first embodiment are labelled with the same reference numeral but incremented by 100.

[0060] In this example embodiment, countermeasure 300 comprises a passive dispersal system. The passive dispersal system comprises an aperture in the bottom of container 301 closed by a door 307. The door 307 is shown in a closed position 307a, in which the aperture is closed by the door and the plurality of pieces 303 are thereby retained in the container 301. On receipt of the trigger signal 309 from control system 311, door 307 moves to an open position 307b, providing an outlet by which the plurality of pieces 303 can egress the container 301. Such an embodiment may, for example, disperse the plurality of pieces by opening the aperture to allow the plurality of pieces 303 to exit the container 301 under the influence of gravity. It will be appreciated by the skilled person that the plurality of pieces 303 will exit the container 301 gradually over a period of time. It will also be appreciated that the length of time required for substantially all the plurality of pieces 303 to exit the container 301 will be determined by the number and geometry of the pieces 303 and the size of the aperture. Thus, such a passive dispersal system can be designed to release the pieces 303 at a pre-determined rate.

[0061] It may be that the dispersal of the plurality of pieces is assisted by motion of a platform carrying the countermeasure 300. For example, the countermeasure 300 may be carried on an aircraft, for example a drone. In such embodiments, motion of the aircraft over the period of time during which the plurality of pieces 303 are being released disperses the plurality of pieces 303 along a flight path of the aircraft. Thus, by controlling the flight path of the platform, it is possible to control the dispersal of the plurality of pieces to target a particular area. Such embodiments can be said to “crop-dust” a target area.

[0062] It will be appreciated that other means may also be used to provide passive dispersal of the plurality of pieces 303. For example, in alternative embodiments, the countermeasure 300 may be arranged to spin, for example due to having been launched from a rifled grenade launcher, and so eject the plurality of pieces 303 through the outlet under the centrifugal forces provided by the spin of the countermeasure 300. In other embodiments, the container 301 may be rotated and/or translated relative to a base (not shown) of the dispersal system, thereby generating forces that encourage the plurality of pieces to exit the container.

[0063] In FIG. 3, countermeasure 300 is shown as having a hinged door 307 which rotates about a hinge point between the closed position 307a and the open position 307b. However, in alternative embodiments the door 307 may be arranged to open and close in other ways, for example by sliding between the open and closed positions. Alternatively, the door 307 may comprise a frangible portion of the container 301 which, on activation of the dispersal system, is broken to provide the outlet. It will be appreciated by the skilled person that the precise means by which the outlet from container 301 is provided is not an essential feature of the invention and therefore that any other known means of providing an openable outlet from a container may also be used. Similarly, although FIG. 3 shows countermeasure 300 having only a single door 307, it will be appreciated by the skilled person that alternative embodiments may comprise any number of outlets and a corresponding number of doors.

[0064] In some embodiments, for example those in which the outlet is provided by a frangible portion of container 301, the outlet may not be closable again once opened. In such embodiments, the countermeasure 300 is a single use item. In alternative embodiments, for example those having one or more doors 307, it may be possible to close the outlet after use. In such embodiments, it may be possible to refill the container with a new plurality of pieces 303 and reset the countermeasure, allowing it to be reused.

[0065] FIG. 4 shows a schematic view of the prior art motor 100 of FIG. 1 having been subjected to the countermeasure 200 of the first embodiment. The plurality of pieces 203, having been released by the dispersal system and attracted to the magnet on the rotor 101, have been ingested into the motor 100 and have accumulated on the magnet of rotor 101. The build-up of pieces 203 has partially filled the air gap between the rotor 101 and the coils 107 of the stator 103, and thereby physically obstructs the rotation of the rotor 101 relative to the stator 103. In some cases, the build-up of pieces 203 may be such to entirely block rotation of the motor. In other cases, the motor may be configured to automatically shut down in the event of arrested rotation of the rotor 103 in order to prevent damage to the coils 107 by excessive electric currents. In such cases, the build-up need not necessarily entirely block rotation of the rotor 103. Instead, the build-up need only be sufficient to impede rotation of the rotor 103 to the extent necessary to initiate an automatic shut-down. In either case, the motor is no longer usable and the operation of the vehicle is disrupted. It may be that the vehicle is completely immobilised by the action of the countermeasure 200. It may be that the vehicle is still operable, but only with reduced performance and/or capability. Although the motor 100 shown in FIGS. 1 and 4 comprises six coils 107, the skilled person will appreciate that electric motors can be constructed with other numbers of coils and that the countermeasure 200 will be similarly effective against such motors.

[0066] FIG. 5 shows a missile 500 according to a third embodiment of the invention. In some embodiments, the missile may comprise any of an anti-air missile, a ground attack missile, and a loitering munition. The missile 500 comprises a countermeasure 100 according to the first embodiment. In some embodiments, missile 500 further comprises a seeker 501. The seeker is configured to detect and track a target vehicle in order to provide guidance of the missile 500 to the target vehicle. In certain some embodiments, the seeker 501 provides some of all of the functions of the control system 211 of the first embodiment. For example, it may be that the seeker 501 detects the target vehicle and monitors the distance to the target vehicle.

[0067] It may be that missile 500 further comprises a motor 503. The motor 503 may comprise any of a rocket motor, a turbojet, and a turboprop or any other engine suitable for driving a propeller. The motor 503 serves to provide propulsion of the missile 500 to a target.

[0068] In some embodiments, missile 500 further comprises a plurality of control surfaces 505, for example control fins. In some embodiments, the control surfaces are moveable, for example by controllable actuators, in order to control the missile attitude. In some embodiments, the control surfaces 505 are controlled according to feedback from the seeker 501 on the relative positions of the missile 500 and the target vehicle. Thus, the seeker 501 and control surfaces 505 enable controlled guidance of missile 500 to the target vehicle.

[0069] In alternative embodiments, the missile 500 does not comprise a seeker 501 and comprises only fixed fins. For example, the missile 500 may comprise an unguided rocket.

[0070] FIG. 6 shows a flow chart illustrating the steps of a method 600 according to a fourth embodiment of the invention.

[0071] An optional first step of the method 600, represented by item 601, comprises detecting a target vehicle. The target vehicle comprises an electric motor including at least one magnet. It may be that the target vehicle is propelled at least in part by the electric motor. For example, the target vehicle may be an aircraft, for example one of a rotary wing aircraft and a fixed wing aircraft. Thus, the electric motor may drive one or more propellers of the aircraft. The vehicle may comprise an unmanned air system (e.g. a drone). Alternatively, the target vehicle may be a ground vehicle, and the electric motor may drive one or more wheels or tracks of the ground vehicle.

[0072] An optional second step of the method 600, represented by item 602, comprises, in response to the detecting, launching the portion of the countermeasure containing the plurality of magnetic pieces in response to detection of the target vehicle.

[0073] An optional third step of the method 600, represented by item 603, comprises detecting that a trigger condition has been met and, in response to the detecting, transmitting a trigger signal to a dispersal system. In some embodiments, detecting that the trigger condition has been met comprises determining that a distance to the target vehicle has fallen below a pre-determined threshold. In some embodiments, detecting that the trigger condition has been met comprises determining that a pre-determined period of time has elapsed since launch.

[0074] An optional fourth step of the method 600, represented by item 605, comprises receiving, at the dispersal system, the trigger signal.

[0075] A fifth step of the method 600, represented by item 607, comprises, in response to the receipt of the trigger signal, the dispersal system releasing a plurality of pieces of magnetic material. In some embodiments, releasing the plurality of pieces comprises creating an airburst to disperse the plurality of pieces. In some embodiments, the dispersal system comprises a pyrotechnic charge and creating the airburst comprises detonating the pyrotechnic charge. In some embodiments, the dispersal system comprises a container of pressurised gas and creating the airburst comprises releasing the pressurised gas. In some embodiments the dispersal system comprises an ejection mechanism and creating the airburst comprises activating the ejection mechanism.

[0076] A sixth step of the method 600, represented by item 609, comprises some of the plurality of pieces being attracted to the magnet, sticking to the magnet, and thereby obstructing the motor. In some embodiments, being attracted to the magnet comprises being ingested into the electric motor through an air intake. In some embodiments, the electric motor further comprises a rotor, a stator, and an air gap between the rotor and the stator. In such embodiments, it may be that the plurality of pieces obstruct the motor by filling the air gap. In some embodiments, obstructing the motor comprises entirely blocking the motor. In alternative embodiments, obstructing the motor comprises hindering the rotation of motor.

[0077] Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.

[0078] Although the present invention and the described embodiments are particularly useful in disrupting the operation of unmanned vehicles, and UAS especially, it will be appreciated that the invention is suitable for use against any vehicle having an open-vented electric motor, be it manned or unmanned. It will also be appreciated that the invention provides a general technique for disabling electric motors, and therefore may be usable against targets other than vehicles and/or for purposes other than disrupting the propulsion of a vehicle.

[0079] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.