US20220332397A1

US20220332397A1 - Operating method for a mine-sweeping system, and mine-sweeping system for detonating sea mines

Info

Publication number: US20220332397A1
Application number: US17/633,078
Authority: US
Inventors: Michael Frank; Jörn Grundmann; Peter van Hasselt
Original assignee: Siemens Energy Global GmbH and Co KG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2019-08-13
Filing date: 2020-06-25
Publication date: 2022-10-20
Also published as: AU2020331545A1; WO2021028105A1; DE102019212105A1

Abstract

A method for operating a mine-sweeping system and corresponding mine-sweeping system, wherein the mine-sweeping system includes at least one drone for detonating sea mines. The drone has at least one magnet element for magnetically detonating the sea mines. The method includes a) translationally moving the at least one drone in the water and b) carrying out a first rotational movement of the drone with respect to a first degree of rotational freedom.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International Application No. PCT/EP2020/067826 filed 25 Jun. 2020, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 10 2019 212 105.5 filed 13 Aug. 2019. All of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The present invention relates to a method for operating a mine-sweeping system, wherein the mine-sweeping system comprises at least one drone for detonating sea mines. In this case, the drone comprises at least magnet element for magnetically detonating the sea mines. The invention furthermore relates to a corresponding mine-sweeping system.

BACKGROUND OF INVENTION

Known systems for remotely clearing sea mines use unmanned drones which are equipped with magnetic coils or with permanent magnets for detonating magnetic mines. These magnet elements generate strong magnetic fields, which can cause the sea mines to detonate. In this case, the drones are configured in such a way that, at the distance typical for detonation, they are not damaged by the detonation.
Such drones may have a drive system of their own, for example the German Navy has remotely controllable boats of the “Seehund” [seal] type, which are equipped with a diesel engine. The magnet element here is designed as a magnetic coil and, for detonating the mines, is integrated in the hull of the remotely controllable boats. The magnetic coil itself is in this case typically formed by a multiplicity of turns of copper cable.
In addition to such drones that float on the surface, there are also known underwater mine-sweeping drones, which may either also have a drive of their own or be towed along by other (under)water vessels.
The self-driven drones may be driven, for example, by an electric motor. In general, in the case of such self-driven drones, the magnet elements may basically be designed either as additional magnet elements or else they can carry out a dual function, in which, in addition to their function for detonating mines, they also serve for generating a magnetic excitation field in the electric motor. Examples of such mine-sweeping systems with a magnetic dual function are described in DE102016203341A1 and in the German application that has not yet been disclosed and has the application number 10 2018 217 211.0.
Many of the known mine-sweeping systems, rather than having just one drone, have a plurality of interconnected drones, wherein each of said drones comprises one or more magnetic elements for detonating the sea mines. Such an assembly of linked drones which are jointly towed as a chain by a transport ship is described, for example, in EP0475834B1. This interlinking of a plurality of drones serves to reproduce a specified magnetic signature of a hypothetical ship as accurately in every detail as possible. This is necessary because the relatively complex sea mines nowadays are configured to respond only to certain magnetic signatures which correspond to the signatures of certain types of ships. The sea mines therefore cannot readily be detonated by random magnetic signals. On the contrary, a certain time profile of a magnetic magnitude, for example the magnetic flux density measured by the sea mine, is necessary in order to cause a detonation. This time profile has to correspond as substantially as possible to the predefined magnetic signature of a certain type of ship, said signature being anticipated by the sea mine, in order to be able to bring about the detonation of the sea mine.
In order to be able to reproduce the magnetic signature of a predefined type of ship as accurately as possible, use is generally made, according to the prior art, of mine-sweeping systems, the longitudinal extent of which lies within the range of the length of the type of ship “to be simulated”. For this reason, the chain length of a plurality of linked drones of a mine-sweeping system is frequently of the order of magnitude of 100 m or more. The number of interlinked drones can be, for example, in the range between 3 and 7, with it being possible, with a higher number of drones, to typically achieve better accuracy in the reproduction of a certain defined magnetic signature.
A disadvantage of the mine-sweeping systems from the prior art is that there is a comparatively high outlay on apparatus because of the high number of drones used and because of the length of the chains of drones that are used.

SUMMARY OF INVENTION

It is therefore an object of the invention to specify a method for operating a mine-sweeping system that overcomes the aforementioned disadvantage. In particular, the intention is to provide an operating method which, in comparison to the prior art, permits as accurate a reproduction of a predefined magnetic profile as possible with a reduced number of drones and with a reduced chain length. It is a further object to specify a corresponding mine-sweeping system.
These objects are achieved by the method and the mine-sweeping system as described.
The method according to the invention serves for operating a mine-sweeping system, wherein the mine-sweeping system comprises at least one drone for detonating sea mines. In this case, the drone comprises at least one magnet element for magnetically detonating the sea mines. The method comprises the following steps: a) translationally moving the at least one drone in the water, and b) carrying out a first rotational movement of the drone with respect to a first degree of rotational freedom.
The at least one drone can basically either be self-driven here, or it can be towed by another water vessel. In each case, the drone is the same element of the mine-sweeping system that, by means of at least one magnet element, can lead to a magnetically induced detonation of the sea mines. The at least one magnet element is therefore intended to be configured in such a way that the generated magnetic flux density suffices for detonating a sea mine in the environment of the drone.
The drone can in principle either float on the water surface or can be moved in a diving manner under the water surface. Basically, a combination of these “floating” and “diving” modes is also possible. In each case, according to step a), a translational moving of the drone is intended to take place. Said translational moving can be in particular a movement parallel to the water surface. The floating embodiment can involve in particular a movement along the water surface. The diving embodiment can involve a corresponding movement along a lower level lying parallel to the water surface. In other words, it can advantageously involve a horizontal translational movement. However, it is also possible and, under some circumstances, advantageous for the translational movement to additionally also contain a vertical component such that, during the horizontal movement, a diving depth of the drone is simultaneously varied. In this case, during the translational movement, the drone can therefore also sink or rise in the water. In conjunction with the present invention, it is essential only that the translational movement in step a) has at least a horizontal component, i.e., in other words, a directional component parallel to the water surface.
In step b), in addition to said translational moving, a rotational movement of the drone in the water is carried out. The sequence of said two steps a) and b) is basically as desired here: for example, they can be carried out either simultaneously or else successively, in particular in multiple successive changes. The drone, as a body which is freely movable in water, basically has three independent degrees of rotational freedom. The rotation of the drone is intended to be a rotational movement with respect to at least a first of said three degrees of rotational freedom. The effect generally advantageously achieved by the rotational movement is that, for example, the magnetic flux density is additionally varied at a target location which lies in the environment of the drone.
The described “target location” can be in particular a location in the environment of the mine-sweeping system, at which a sea mine can be brought to detonate. This target location does not have to be limited to a point-like region, but may in particular also involve a spatially extended detonating range which can have in particular the shape of a conical target region. The effect which can advantageously be achieved by the described interaction of the translational moving and the rotational movement of the drone is that a predefined magnetic profile which substantially corresponds to the magnetic signature of a given type of ship can be formed at the target location. Particularly advantageously, said target location lies upstream of the drone with respect to the translational moving (i.e. “as seen in the direction of travel”). The effect can thus be achieved that the magnetic signature required for detonating the sea mines is simulated at the target location before the drone (or else the mine-sweeping system as a whole) reaches the target location. In this way, a greater distance can be maintained between the mine-sweeping system and the detonating sea mines. The risk of damage to the mine-sweeping system upon detonation of the sea mines is thereby reduced.
In other words, by means of the described combination of translational moving and targeted rotational movement, a desired magnetic profile can be projected ahead onto a target location located upstream of the drone in the direction of travel. It is particularly advantageous if, in this case, for example, the magnitude of the magnetic flux density at said target location lying ahead is higher than in the remaining regions in the environment of the drone. The effect which can be achieved by carrying out the rotational movement (optionally in combination with the additional control variables described further below) is that, at the target location, not only is a certain magnetic flux density generated at a certain time, but that, at the target location, a certain profile of the flux density over time is also generated, which substantially corresponds to the magnetic signature to be reproduced. The magnetic profile reproduced in this way can be in particular a predefined profile of the magnitude of the magnetic flux density over time, one or more directional components of the magnetic flux density, or else a combination of said aforementioned variables.
The effect which can advantageously be achieved by this described “projection ahead” of a predetermined magnetic profile is that the mine-sweeping system brings about a reliable detonation of sea mines, with it being possible at the same time, in comparison to the prior art, to reduce the number of required drones and/or the length of the chain of drones that is used. This reduction in outlay on apparatus can be achieved in that, by means of the rotational movement of the drone, an additional degree of freedom is available in order to reproduce a complex magnetic profile at a given target destination. The extent of the mine-sweeping system can thus be reduced in particular by the fact that the movement of an extended drone chain past the sea mine is at least partially replaced by “projecting ahead” the desired magnetic signature to the potential location of the sea mine. This affords the further advantage that, under some circumstances, the detonation can also take place at a greater and therefore safer distance from the mine-sweeping system.
The mine-sweeping system according to the invention has at least one drone for detonating sea mines. The drone comprises at least one magnet element for magnetically detonating the sea mines. In addition, the drone comprises at least one control element for bringing about a first rotational movement of the drone with respect to a first degree of rotational freedom. In particular, said control element is configured to bring about the rotational movement while the drone floats on a water surface or dives below the water surface. It is therefore intended to be a control element for bringing about a rotational movement of the drone in the water. It can basically either be an active or a passive control element. An active control element is intended to be understood here as meaning a control element which has a dedicated drive element in order to actively bring about the corresponding rotational movement. A passive control element is intended to be understood here as meaning a control element which does not have a drive of its own, but rather can interact with a further drive (for example the translational drive of the drone or an external towing drive by means of a mother ship or a guiding drone) in order to bring about a rotational movement of the drone with the aid of the water flow. With the mine-sweeping system according to the invention, the advantages described further above in conjunction with the operating method can be realized.
Advantageous refinements and developments of the invention emerge from the claims and from the following description. The described refinements of the method and of the mine-sweeping system can advantageously be combined with one another.
In a generally particularly advantageous manner, the drone has a longitudinal axis A, and the first degree of rotational freedom corresponds to a rotational movement about said longitudinal axis. In other words, the rotational movement may involve rolling or heeling of the drone. The elongated shape of the drone is particularly in order to permit a low-resistant movement in the water. The rotational movement about the longitudinal axis is correspondingly the rotational movement which is possible with the smallest possible resistance in the water. This applies in particular for a generally advantageous, substantially rotationally symmetrical configuration of the drone with the longitudinal axis A as axis of symmetry.
However, as an alternative to the above-described rotation about the longitudinal axis, it is also possible and advantageous under some circumstances if the first degree of rotational freedom corresponds to a rotational movement about an axis which lies perpendicular to the longitudinal axis. For example, such an axis of rotation can lie perpendicular to the longitudinal axis and (when the drone is oriented horizontally in the water) substantially parallel to the water surface. In other words, the rotational movement can then involve pitching or trimming of the drone. According to a further alternative, the axis of rotation can lie perpendicular to the longitudinal axis and (when the drone is oriented horizontally in the water) substantially perpendicular to the water surface. In other words, the rotational movement can then be a yawing or classic rotation. In principle, however, rotations are also conceivable and under certain circumstances advantageous, in which said described classic maritime degrees of rotational freedom are combined with one another such that a rotation with respect to an axis of rotation lying obliquely in relation to the longitudinal axis of the drone is carried out.
With each of the described rotational movements, a magnetic flux density brought about at the target location can advantageously be varied particularly readily if the at least one magnet element is configured for forming a magnetic field in which at least one pole axis forms an angle α, which is different from zero, with the axis of rotation relevant to the first degree of rotational freedom. Said axis of rotation can particularly advantageously be the longitudinal axis of the drone. A pole axis is intended to be understood here as meaning in general an axis of symmetry of the magnetic field, on which two magnetic poles are arranged (a north pole and a south pole). Such a pole axis is also referred to among experts as a magnetic axis. The angle α can advantageously be in the range between 10° and 90° and particularly advantageously can be in the range between 45° and 90°. A rotation about the respective axis of rotation then brings about a particularly significant change in the magnetic field generated in the environment by the drone. This significant change can be in particular a change of a magnitude, generated at the target destination, of the magnetic flux density or else also a change in the value and/or the sign of one or more individual directional components of the flux density.
In a generally advantageous manner, the method can comprise the following additional step: c) carrying out a rotational movement of the drone with respect to an additional second degree of rotational freedom.
Such a combination of at least two degrees of rotational freedom therefore corresponds to a more complex rotational movement by means of which a specific magnetic profile can be reproduced even more precisely at a predefined target location. The two degrees of rotational freedom to be combined with each other can be generally selected as desired from the three classic maritime degrees of rotational freedom described further above (i.e. in each case two of the degrees of freedom of rolling/heeling and/or pitching/trimming and/or yawing/rotating). In a particularly advantageous manner, all three of the aforementioned degrees of rotational freedom can also be combined with one another in order to permit an even more precise reproduction of a given magnetic profile at a given target location. In general, in a manner similar to step b) which has already been described, this additional step c) can be carried out simultaneously or else in an alternating manner with the translation in step a). Steps b) and c) may in principle also be carried out either simultaneously with each other or successively.
According to a further advantageous embodiment, the method can comprise the following additional step: d) changing a diving depth (T) of the drone.
The diving depth is intended to be understood here as meaning in general the vertical distance of the deepest point of the drone from the water surface. In the case of a drone which floats and is not completely immersed in the water, said diving depth can also be smaller than the vertical height of the drone. This can therefore then in particular involve an immersion depth of a drone floating on the surface.
It is also possible, by means of such a variation in the immersion depth/diving depth, for the time profile, which is generated at a given target location, of the magnetic flux density to be adapted even more precisely to a specific magnetic profile. In order to generate a specified profile of the magnetic flux density over time, the at least one degree of rotational freedom can therefore advantageously be combined with a variation in the diving depth. In general, similarly to step c) that has already been described, this additional step d) can be carried out simultaneously or else in an alternating manner with the translation in step a). Steps b), c) and/or d) can in principle be carried out either simultaneously with one another or at least partially sequentially.
Alternatively or in addition to the described variation in the diving depth, it is also possible (either within step d) or in a further optional step) for the speed and/or the direction of the horizontal movement or of the horizontal movement component of the drone to be changed. This can also advantageously permit an even more precise reproduction of a specified magnetic profile at a certain location.
According to a first advantageous embodiment, the at least one magnetic element of the drone can be a permanent magnet. Such a permanently magnetic drone has a comparatively low outlay on apparatus, and therefore it can be produced easily and is simple to operate. It is also comparatively robust.
According to an alternative second advantageous embodiment, the at least one magnet element of the drone can be an electrical coil element. An advantage of such an electrically magnetized drone is that a desired magnitude of the magnetic flux density can be modulated relatively easily in particular by means of an adjustable current flow. The electrical coil element can be, for example, either a normally conducting or else also a superconducting coil element. When a superconducting coil element is used, with the latter having a comparatively small overall size, particularly high magnetic flux densities can be generated.
It may also be advantageous to combine the first embodiment with at least one permanent magnet and the second embodiment with at least one electrical coil element with each other such that a plurality of different magnet elements are present next to one another. In general and independently of the precise design of the magnet element or of the magnet elements, the latter can be configured for forming a magnetic field, the pole number of which is advantageously between 2 and 16.
In an embodiment having at least an electrical coil element, the method can generally advantageously comprise the following additional step: e) varying an operating current of the electrical coil element over time.
By this means, the magnetic flux density at a specified target location can be additionally influenced in a particularly simple manner. In combination with the variation possibilities already described further above, a specified magnetic profile can thus be reproduced even more precisely. In general, similarly to steps b), c) and d) that have already been described, this additional step e) can be carried out simultaneously or else in an alternating manner with the translation in step a). Steps b), c), d) and/or e), if present, can also in principle be carried out either simultaneously with one another and/or at least partially sequentially.
In a generally particularly advantageous manner, the at least one drone can be a self-driven drone. A general advantage of a self-driven drone consists in not requiring an additional separate mother ship which would be at risk in the event of a detonation of a sea mine. The risks for the mother ship and the crew thereof are thus advantageously avoided.
For example, the drone can have an electric drive. For this purpose, the drone can comprise an electric motor which can drive, for example, a propeller of the drone. The at least one magnetic element serving for detonating mines can advantageously simultaneously be a magnet element of an excitation device of the electric motor, similarly as is described in DE102016203341A1 and in the German application which has not been published and has the application number 10 2018 217 211.0. In this case, it is generally particularly advantageous if the electric motor has a correspondingly weak magnetic shielding.
As already mentioned, the sequence of the described steps may be configured differently. Thus, according to a first advantageous variant, both steps a) and b) can take place simultaneously. This is intended to be understood as meaning that the two steps mentioned at least partially overlap in time. They therefore do not absolutely have to have precisely the same duration. For example, it is thus possible and, under some circumstances, advantageous if step a) lasts for a longer period of time t_aand step b) is carried out within the period of time t_ain one or more individual and comparatively shorter time intervals t_b. The individual time intervals t_bmay in principle be configured here either to be of the same length as one another or else to differ in length. It is only essential, in the case of this first embodiment variant, for step b) to take place while step a) lasts, i.e. while the drone is moved. Step b) is advantageously carried out several times in succession during said movement. In this way, a controlled simulation of the desired magnetic signature can take place during the movement of the drone and therefore during its change in position. An advantage of this first embodiment variant is that the time for moving the drone can simultaneously also be used for the specific variation of the magnetic field generated in the environment. A specified, extended spatial area can therefore be covered by the mine-sweeping system in a comparatively short overall period and can nevertheless be particularly reliably freed from active sea mines.
According to an alternative second variant, both steps a) and b) may, however, also take place successively. In particular, both steps can each be carried multiple times in a repeated changing sequence. In other words, the drone can in each case alternately be moved translationally for a distance in order then, at the reached position, to bring about a specific reproduction of the predefined magnetic profile by means of the at least one rotational movement. These two steps a) and b) can each alternately be carried out successively for a multiplicity of times in order thereby to reliably scan a spatially extended area and to free the same from sea mines. An advantage of this second embodiment variant can consist in being able to particularly accurately reproduce a specified magnetic profile at a given fixed target location by decoupling the horizontal movement and specific modulation of the magnetic field generated in the environment.
In general and irrespective of the precise sequence of the two described steps a) and b), it is advantageous in every case if step b) is carried out a plurality of times successively, wherein, during the individual implementations of step b), the drone takes up in each case a different position with a projection onto the water surface. Step b) can be repeated in particular in a periodically recurring sequence. In this case, the duration of the individual time intervals t_bfor step b) can in each case advantageously be in a range of between 1 second and 3 minutes, particularly advantageously between 10 seconds and 3 minutes. Such a time interval is sufficient in order, at a given position of the drone, to reproduce a specified magnetic signature at at least one target location and in particular also at a plurality of target locations in the environment of this position.
The mine-sweeping system can advantageously also comprise a plurality of drones for detonating sea mines. It can therefore also be provided within the scope of this invention that a plurality of such drones are linked in the manner of a chain and move together through the sea. However, by means of the advantages of the invention that are described further above, the number of individual drones and/or the spatial extent of the chain can be reduced in comparison to the prior art, with a specified magnetic profile nevertheless being able to be reproduced sufficiently accurately.
In such an embodiment with a plurality of drones, it is particularly advantageous if all of said individual drones have the features described further above. All of the individual drones can expediently in each case have at least one magnet element for magnetically detonating sea mines. The translational moving according to step a) is advantageously coupled for the individual drones of the chain. However, a certain translational relative movement of the individual drones is not ruled out here since a particularly accurate reproduction of a given magnetic profile can therefore also be achieved therewith. The rotational movement according to step b) has to be realized at least for one of the drones in the chain. However, it is particularly advantageous if all the drones of the chain carry out such a rotational movement according to step b). This rotational movement can basically take place either in a manner synchronized for all of the drones of the chain or else independently of one another. If different rotational movements of the individual drones are carried out separately, a particularly accurate reproduction of a given complex magnetic profile can in turn be achieved.
In such an embodiment with a chain of a plurality of linked drones, it is particularly advantageous if at least one of the drones is self-driven. This one drone can then tow the remaining drones of the chain behind it. Alternatively, it is, however, also possible and, under some circumstances, advantageous if all of the drones of the chain have a drive of their own. A translational relative movement and a separate rotation of the individual drones is therefore made possible particularly easily.
According to an advantageous embodiment of the mine-sweeping system, the at least one drone can be a self-driven drone. Irrespective of whether said drone is self-driven or whether it is moved passively, the control element for bringing about the first rotational movement can basically be either an active or a passive control element. It is particularly advantageous if the at least one drone has a drive element of its own which can drive both the translational movement of the drone and the rotational movement of the drone. In order to trigger the rotational movement, in this case there can optionally be an additional passive control element, for example a rudder or a flap. However, an additional active control element for the rotational movement can also be present, for example a separate motor.
In a generally advantageous manner and independently of the translational drive of the drone, the at least one control element can be, for example, a rudder, a flap or a motor. The motor can particularly advantageously be a separate motor which is provided in addition to a translational drive motor of the drone. In particular, this can be a separate electric motor. It can be arranged, for example, axially in the vicinity of the center of gravity of the drone where it can particularly effectively trigger a rolling movement.
In general and independently of the drive of the drone and the precise realization of the control element, the drone can be designed in such a manner that a magnetic flux density of at least 5 mT, in particular at least 50 mT or even at least 500 mT can be achieved in a region outside the drone (but in the vicinity of its housing). With such high magnetic flux densities in the vicinity of the drone, a magnetic mine at a relatively far target location can be detonated even from a relatively great distance. For this purpose, an outer wall of the drone can be formed from an amagnetic material. In conjunction with the present invention, an amagnetic material is intended to be understood as meaning in general a material having a relative permeability μ_rof at least 300.
In addition, the at least one drone can generally advantageously also comprise a further detonation system for acoustic and/or electrical detonation of sea mines. According to a particularly advantageous embodiment of the mine-sweeping system, the latter can in turn comprise a plurality of drones for detonating sea mines.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below using a number of exemplary embodiments with reference to the attached drawings, in which:

FIG. 1 shows a schematic illustration of a magnetic signature, to be reproduced, of a ship,

FIG. 2 shows a schematic sectional illustration of a mine-sweeping system according to a first exemplary embodiment of the invention,

FIG. 3 shows a rectangular coil,

FIG. 4 shows a three-dimensional profile for a magnetic flux density formed with the rectangular coil of FIG. 3,

FIG. 5 shows the dependency of the magnetic flux density on the distance from the coil center for various directions in space,

FIG. 6 shows the dependency of various components of the magnetic flux density on the revolution angle for a magnetic quadrupole, and

FIG. 7 shows a schematic illustration of a mine-sweeping system according to a second example of the invention.

DETAILED DESCRIPTION OF INVENTION

In the figures, identical or functionally identical elements are provided with the same reference signs.
FIG. 1 shows a schematic illustration of a magnetic signature 1 of a ship which has a longitudinal extent in the region of approximately 200 m. This magnetic signature is intended to be reproduced as accurately in every detail as possible by a mine-sweeping system in order therefore, for a modern complex sea mine, to simulate the passing by of a corresponding ship and thus to bring the sea mine to detonate. FIG. 1 illustrates the dependency of the magnitude of the magnetic flux density B on the position of an observation point, for example below the ship. Accordingly, the horizontal distance d of the observation point from the center of gravity of the ship is illustrated in meters on the abscissa. This therefore involves a position-dependent magnetic signature 1. By way of example, only the magnitude of the magnetic flux density is illustrated in FIG. 1. Corresponding additional curves arise analogously if, depending on the horizontal distance, the individual direction components (for example in the Cartesian directions in space x, y and z) of the magnetic flux density are taken into consideration. Modern complex sea mines are frequently configured to compare a measured profile of the magnitude of the magnetic flux density and also of the individual direction components thereof with the known magnetic signatures of predefined types of ship and to detonate only if there is a sufficiently high correspondence.
In the following, a magnetic signature is understood as meaning in general the dependency of the magnetic flux density on a position coordinate as is illustrated in FIG. 1. Since, however, a sea mine is not spatially extended, it can measure the detected magnetic parameter not as a function of the location, but only as a function of the time. This time dependency is calculated from the positional dependency, shown in FIG. 1, of a magnetic parameter in combination with the speed of the passing ship and the (shortest) distance at which the ship passes the stationary sea mine. The sea mine therefore actually measures a time-dependent magnetic profile which is produced as a function of the magnetic signature outlined in FIG. 1. The task of a mine-sweeping system is therefore to simulate the corresponding time-dependent magnetic profile of such a passing ship as well as possible, specifically ideally not only for the magnitude of the magnetic flux density B that is illustrated in FIG. 1, but simultaneously also for one or more direction components. Complex characteristic patterns for certain defined types of ship can be produced in this case.
FIG. 2 shows a schematic partially perspective sectional illustration of a mine-sweeping system 21 according to a first example of the invention. In the example shown, this mine-sweeping system 21 comprises only a single drone 22 which here is diving in the water 20 and below the water surface 29, specifically with a diving depth T. Alternatively or additionally, however, a use floating on the water surface also comes into consideration. The drone 21 has a central longitudinal axis A and moves along a travel direction v which coincides here with the longitudinal axis A.
The drone 22 is a self-driven drone which can itself be moved in the water by means of an electric motor 23 and a propeller 24 mechanically coupled thereto, and does not have to be towed by a mother ship. Alternatively, however, an embodiment with only a passive towing drive is also conceivable. The drone 22 is configured to generate, at a target location 26, a time-dependent magnetic profile which corresponds as exactly as possible to the magnetic profile which a ship traveling past at a typical travel speed and having a specified magnetic signature would generate. In other words, the intention is to simulate the magnetic signature of a known type of ship in order to bring a sea mine positioned at the target location 26 to detonation.
In order to generate the desired time-dependent magnetic profile at the target location 26, the drone 22 is equipped with at least one magnet element. Only by way of example are a plurality of different magnet elements shown for the drone 22 in FIG. 2: this drone thus has firstly a plurality of coil elements 27 a which are used as excitation coils of the electric motor 23. However, these coil elements 27 a carry out a dual function and serve at the same time to contribute to the generation of the desired magnetic profile at the target location 26. In addition, in the rear part of the drone 22, further coil elements 27 b are shown which likewise contribute to the generation of the desired magnetic profile, but are not part of the electric motor. Of the two types of coil 27 a and 27 b, there can be in each case one or more in such a drone. It is particularly advantageous if the individual coil elements can be fed with a variable current such that the amplitude of the generated magnetic field can be additionally modulated. In the front region, the drone 22 additionally has a permanent magnet 28 which is illustrated here by way of example as an annular disk magnet. In principle, however, such permanent magnets can be present in the drone in any form and also in any number. Such permanent magnets can also contribute to the generation of the desired magnetic profile. However, the arrangement of the individual different types of magnet elements 27 a, 27 b and 28 within a drone should be understood here as merely being by way of example. Although a plurality of such elements may be arranged within a drone, it is, however, generally sufficient if a drone comprises at least one magnetic element in order to bring about a magnetic detonation of a sea mine.
In the example of FIG. 2, the current direction of travel v of the drone is coaxial with the longitudinal axis A. In principle, however, the translational movement of the drone may also have different direction components. In FIG. 2, the direction of travel v is slightly oblique in the coordinate system shown (with the Cartesian direction coordinates x, y and z). The direction of travel v does indeed have a relatively large horizontal direction component within the xy plane which lies parallel to the water surface. However, it additionally also has a slight component in the z direction which corresponds here to a slight sinking of the drone.
In addition to this translational movement, the drone, however, also executes at least one rotation movement with respect to at least one degree of rotational freedom. The three independent degrees of rotational freedom of the drone are denoted by the arrows r1, r2 and r3 in FIG. 2. In this case, the degree of rotational freedom r1 corresponds to rolling or heeling of the drone, the degree of rotational freedom r2 corresponds to pitching or trimming, and the degree of rotational freedom r3 corresponds to yawing or rotating. A complex rotational movement may also take place in which the drone is rotated about a plurality of the aforementioned degrees of rotational freedom. In each case, the described rotation of the drone modulates the magnetic flux density generated at a certain time at the target location 26. This relates in general both to the magnitude and to the individual direction components of the flux density. The rotational movement can therefore be used in order, at the target location 26, to reproduce the time-dependent magnetic profile, which is intended to correspond to the magnetic signature of a passing ship, as accurately as possible. In order to improve the reproduction of the desired magnetic profile even further, the described rotational movement can optionally be combined with a variation of the diving depth T and/or with a variation of the operating current of the coil element 27 a or 28 a and/or with a variation of direction of travel v and/or travel speed.
It is generally particularly effective if, during the travel of the drone 22 through the water, at least the described rotation movement is carried out multiple times successively. It can therefore be achieved that a desired magnetic profile is reproduced successively at different target locations 26. This is true irrespective of whether the rotational movement, which is carried out, is carried out in each case simultaneously with the translational forward movement or in an alternating manner with the translational forward movement of the drone.
It is particularly advantageous if the rotational movement of the drone is at least a rotational movement with respect to the first degree of rotational freedom r1, in other words if it comprises rolling or heeling of the drone. In order to permit such rolling, the drone 22 of FIG. 2 is provided with a control element 25. This can be either an active control element (for example an electric motor) or else a passive control element (for example a rudder or a flap). Corresponding further control elements, not illustrated specifically here, can also be provided for the rotational movement with respect to the other degrees of rotational freedom r2 and/or r3.
The mine detonation by the described mine-sweeping system 21 is particularly effective if, at the target location 26, a comparatively high magnetic flux density in comparison to the other environment of the drone is generated, wherein said target location 26 can still lie upstream of the drone, as seen in the direction of travel v. Particularly advantageously, it can lie upstream of the drone, as shown in the direction of travel in FIG. 2, and below the drone with respect to the water surface. The desired magnetic profile can in each case be projected ahead to said target location and sea mines arranged at the target location can already be brought to detonation at a certain distance from the drone passing by, which reduces the risk of damage to the drone during detonation.
It is intended to be clarified with the following FIGS. 3 to 6 how the described rotational movement of the drone contributes to varying the magnetic field generated at a target location 26 by means of the at least one magnet element. FIG. 3 thus shows an approximately square-shaped rectangular coil 31 as can be used, for example, as coil element 27 a or 27 b in the drone of FIG. 2. The Cartesian coordinate directions x, y and z shown in FIG. 3 illustrate only a local coordinate system here and are not necessarily intended to correspond to the spatial directions illustrated in FIG. 2. However, the local coordinate system is retained in the following FIGS. 4 and 5. When current flows through the rectangular coil 31, a two-pole magnetic field is generated, the pole axis of which is denoted here by P.
FIG. 4 shows the simulated three-dimensional profile of the magnetic flux density B formed by the rectangular coil 31 of FIG. 3 when a constant current flow is provided. The profiles are shown for the magnitude of the magnetic flux density, the profiles being produced from the center point Z outward for three different surface sections: a square-shaped cutout of the xy plane, a square-shaped cutout of the xz plane and a square-shaped cutout of the yz plane each having an edge length which corresponds to a multiple of the coil diameter. For this purpose, the corresponding surface cutouts are divided by hatching into regions of similar magnetic flux density, with the division into the value ranges having been selected in accordance with a logarithmic scale. The end points of the value ranges are indicated in arbitrary units, with the numerical values only being intended to clarify that a logarithmic scale has been used. It can readily be seen in FIG. 4 that, for a certain distance from the center, the magnitude of the magnetic flux density B which is formed depends greatly on the spatial orientation of the observation point. By means of a rotational movement of the drone which carries the coil, a significant modulation of the magnetic flux density generated at an outer target location can therefore be achieved. This modulation is particularly powerful if the rotational movement takes place about an axis of rotation which encloses an angle different from 0 with the pole axis P. In other words, the field distribution in the environment changes particularly powerfully if, during the rotation, the magnetic pole axis P itself is tilted.
FIG. 5 shows the dependency of the magnetic flux density B, formed by the rectangular coil 31 of FIG. 3, on the distance d from the coil center M. This dependency is shown for different directions in space: the curve Bx thus shows the distance dependency for various positions along the x axis. The curve By analogously shows the distance dependency for various positions along the y axis. Finally, the curve Bw shows the distance dependency along the diagonal direction (within the xz plane) which is denoted by w in FIG. 4. The values for the magnitude of the magnetic flux density B are in turn each specified in arbitrary units on a logarithmic scale. The values for the distance d are specified in multiples of the coil diameter. The conspicuous points of the two curves By and Bw mark the locations of the conductors through which current passes. It is shown that, at relatively great distances of a plurality of coil diameters, the magnitudes of the flux densities on the x axis are significantly larger than on the other two axes. It is also shown that, by means of a corresponding rotation of the drone, the magnetic flux density generated at the target location can be powerfully modulated. The direction components (not shown here) can also be correspondingly modulated, with it also being possible to bring about a sign change in the event of a correspondingly high angle of rotation.
The embodiments in conjunction with FIGS. 3 to 5 apply not only to the coil geometry under consideration here but in a similar manner also for other coil shapes. The powerful direction dependency of the generated magnetic flux density applies in a similar manner also to permanently magnetic dipoles. Even in the case of multi-pole magnet systems, a rotation of the excitation device can bring about a significant modulation of the magnetic flux density generated. This is intended to be clarified by way of example by FIG. 6 for a magnetic quadrupole arrangement: FIG. 6 thus shows the dependency of various components of the magnetic flux density on the revolution angle 63 for a magnetic quadrupole which can be realized, for example, by a symmetrical arrangement of four electrical coil elements. The upper part of FIG. 6 shows how the magnitude of the magnetic flux density 61 (here in arbitrary units) varies over a half revolution of 180° about the quadrupole arrangement. This revolution has been simulated with a constant radius. The magnetic flux density 61 here in each case reaches a maximum in the region of the two magnetic pole axes P1 and P2 while it decreases by a significant factor in the regions in between.
It is shown in the lower part of FIG. 6 how the direction components 62 of the magnetic flux density vary during a corresponding revolution. The values for the direction components 62 are also specified here in arbitrary units. The curve Br denotes the profile of the local radial direction component, while the curve Bt shows the profile of the local tangential direction component. As seen over the half revolution of 180°, powerful modulations each having two zero crossings are produced for the two curves. Therefore, via corresponding rotation of a drone with a magnetic quadrupole, a powerful modulation can be achieved both for the magnitude of the magnetic flux density and for the individual direction components. In particular, a specified complex profile of the individual direction components can be reproduced.
If, therefore, the sea mine which is to be detonated carries out a comparison with a stored desired profile not only for the magnitude of the magnetic flux density, but also for the individual direction components thereof, then, by means of a suitable sequence of rotational movements of the drone, the desired magnetic profile can nevertheless be substantially reproduced.
FIG. 7 finally shows a schematic illustration of a mine-sweeping system 21 according to a further example of the invention. The mine-sweeping system illustrated here has a guiding drone 22 which can be constructed, for example, similarly to the drone 22 of FIG. 2. In particular, said guiding drone 22 can be a self-driven drone and can carry out similar translational movements and rotational movements as the drone of FIG. 2. In addition, the mine-sweeping system 21 of FIG. 7 also has two further drones 71 which are connected to the guiding drone 22 by a towing cable 72. This multi-sectional mine-sweeping system is also configured overall for forming a predefined magnetic profile at a target location 26. For this purpose, each of the drones 22 and 71 has at least one magnet element. The two rear drones 71 are also designed to in each case carry out rotational movements independently of one another with respect to at least one degree of rotational freedom. By means of this plurality of rotatably designed drones 22 and 71, the desired magnetic profile can be modulated even more accurately in detail at the target location 26. The outlay on apparatus (i.e. in particular the number of drones and/or the spatial extent of the chain) can advantageously be kept smaller here than in the prior art because of the use of the rotational movements.

LIST OF REFERENCE SIGNS

1 Magnetic signature
20 Water
21 Mine-sweeping system
22 Drone
23 Electric motor
24 Propeller
25 Control element
26 Target location
27 a Coil element
27 b Coil element
28 Permanent magnet
29 Water surface
31 Rectangular coil
61 Magnitude of the magnetic flux density
62 Magnetic flux density
63 Revolution angle in degrees
71 Drone
72 Towing cable
A Longitudinal axis
B Magnetic flux density
Br Radial component of the magnetic flux density
Bt Tangential component of the magnetic flux density
Bx Profile of the flux density along the x axis
By Profile of the flux density along the y axis
Bw Profile of the flux density along the direction w
d Distance from the center of gravity
M Center point of the coil element
P Pole axis
P1 First pole axis
P2 Second pole axis
r1 First degree of rotational freedom
r2 Second degree of rotational freedom
r3 Third degree of rotational freedom
T Diving depth
v Direction of travel
w Diagonal direction in space in yz plane
x,y,z Cartesian directions in space

Claims

1.-15. (canceled)

16. A method for operating a mine-sweeping system, wherein the mine-sweeping system comprises at least one drone for detonating sea mines, wherein the drone comprises at least one magnet element for magnetically detonating the sea mines, wherein the method comprises:

a) translationally moving the at least one drone in the water, and

b) carrying out a first rotational movement of the drone with respect to a first degree of rotational freedom, characterized in that the drone has a longitudinal axis,

wherein the first degree of rotational freedom corresponds to a rotational movement about the longitudinal axis.

17. The method as claimed in claim 16, further comprising:

c) carrying out a rotational movement of the drone with respect to an additional second degree of rotational freedom.

18. The method as claimed in claim 17, further comprising:

d) varying a diving depth of the drone.

19. The method as claimed in claim 16,

wherein the at least one magnet element of the drone is a permanent magnet.

20. The method as claimed in claim 16,

wherein the at least one magnet element of the drone is an electrical coil element.

21. The method as claimed in claim 20, further comprising:

e) varying an operating current of the electrical coil element over time.

22. The method as claimed in claim 16,

wherein the drone is a self-driven drone.

23. The method as claimed in claim 16,

wherein steps a) and b) take place simultaneously.

24. The method as claimed in claim 16,

wherein steps a) and b) take place successively.

25. The method as claimed in claim 16,

wherein the mine-sweeping system comprises a plurality of drones for detonating sea mines.

26. A mine-sweeping system, comprising:

at least one drone for detonating sea mines,

wherein the drone comprises at least one magnet element for magnetically detonating the sea mines,

wherein the drone comprises at least one control element for bringing about a first rotational movement of the drone with respect to a first degree of rotational freedom,

wherein the drone has a longitudinal axis,

27. The mine-sweeping system as claimed in claim 26,

wherein the at least one drone is a self-driven drone.

28. The mine-sweeping system as claimed in claim 26,

wherein the control element is a rudder, a flap, or a motor.

29. The mine-sweeping system as claimed in claim 26,