Magnetic field agent

Abstract

A method of assisting an interceptor comprising an interceptor controller to engage an interception target, the method comprising: generating signals responsive to magnetic fields to which the interceptor is exposed for locations of the interceptor during motion of the interceptor along a trajectory to intercept the target; processing the signals to determine a magnetic B field generated by the target as a function of location of the interceptor along the trajectory; determining one or both of a magnitude |B| and a spatial rate of change d|B| / dr of |B| as a function of location of the interceptor during traversal of the trajectory; determining based on one or both of |B| and d|B| / dr whether or not to transmit a terminal action signal to a controller of the interceptor to indicate suitability of controlling the interceptor to execute a terminal interception action with respect to the target.

Description

MAGNETIC FIELD AGENTRELATED APPLICATIONS

[0001] This application claims benefit under 35 U.S.C. 119(a) IL Application 318662 filed January 21, 2025, the disclosure of which is incorporated herein by reference in its entirety.FIELD

[0002] Embodiment of the disclosure relate to providing data to assist an interceptor in engaging an interception target responsive to a magnetic field that the target generates BACKGROUND

[0003] Unmanned aerial vehicles (UAVs) and drones have become increasingly prevalent in both civilian and security-related environments. Modem UAVs and drones present significant challenges to detection and interception due to a combination of physical and operational characteristics.

[0004] In particular, many UAVs and drones are characterized by a small physical size and a reduced radar cross-section, which limits the effectiveness of conventional radar-based detection systems. Additionally, these platforms often exhibit minimal heat emissions, thereby reducing the reliability of infrared and thermal sensing techniques. Many UAVs and drones further operate with low acoustic and visual signatures, making detection by auditory or optical means difficult, especially at extended ranges.

[0005] Detection is further complicated in environments in which objects are partially or fully obscured by terrain, foliage, ground structures, or bodies of water, so that line-of-sight sensing methods are degraded or unavailable. As a result, traditional detection modalities, including radar-based and infrared-based systems, may be insufficient to detect, localize, or engage such targets across a wide range of operational scenarios with desired accuracy.SUMMARY

[0006] An aspect of an embodiment of the disclosure relates to providing a magnetic field agent (“MAFA”) that supports an interceptor to successfully engage an optionally moving target comprising a component, such as by way of example a propulsion and / or a propulsion control system, that generates a magnetic field during operation of the target. In an embodiment MAFA comprises a magnetic field sensor module (MSM) and optionally comprises or has access to an interceptor navigation system (INS) and a target identification module (IDM). The MSM, INS, and IDM cooperate in accordance with an embodiment of the disclosure to generate and process data to aid in controlling the interceptor to successfully engage anintended interception target responsive to the magnetic field that the target generates during target operation.

[0007] Supporting an interceptor to successfully engage a target comprises at least one or any combination of more than one of identifying the target, indicating a proximity to the target, and / or indicating a direction advantageous for homing in on the target. Engaging a target may also be referred to as intercepting a target and refers to undertaking any interaction with a target intended to destroy the target or change behavior of the target. Whereas an interception target may be any target that generates a changing magnetic field it is assumed for convenience of presentation that an interception target is a drone driven by an electric motor that generates a magnetic field.

[0008] In an embodiment the INS operates to produce navigation signals that may be processed in real time to provide at least one or any combination of more than one of real time pose (location and orientation), acceleration (a), and / or velocity (v) of the interceptor during interceptor motion along a trajectory to engage a target.

[0009] The MSM comprises at least one magnetic field sensor configured to generate real time voltage signals, hereinafter also referred to as MSM signals, responsive to a magnetic field that exhibits time dependence at the sensor during motion of the interceptor. In an embodiment the magnetic field sensor comprises at least one sensing coil configured to generate the MSM voltage signals. Optionally, the at least one sensing coil comprises at least two sensing coils having orthogonal magnetic moments that are fixed relative to a coordinate system of the body of the interceptor. During motion of the interceptor along a trajectory to engage an optionally moving target, the MSM generates MSM signals for locations of the interceptor along the interceptor trajectory responsive to magnitudes of components of a magnetic field to which the interceptor is exposed at the locations. Optionally, the MSM comprises a processor that processes signals that the at least one MSM sensing coil generates to determine a magnitude and / or at least one component of a magnetic field generated by the target at the respective trajectory positions. Optionally, the at least one component of the magnetic field comprises two or three components. Optionally, the processor processes the MSM signals to determine a maximum gradient ascent (MAGA) for the magnitude of the target magnetic field at locations of the interceptor along the trajectory. MSM signals, and / or derived functions of MSM signals, such as components and / or magnitude of a magnetic field, and / or a MAGA that the MSM may provide for locations along an interceptor trajectory may be referred to generically, individually, and / or collectively as MSM data. MSM signals comprised in MSM data may be referred to asraw MSM data and MSM data generated by processing the raw MSM data may be referred to as derived MSM data.

[0010] It is noted that whereas the above discussion describes an MSM as comprising a magnetic field sensor that is a sensing coil, embodiments of the disclosure are not limited to sensing coils. An MSM in accordance with an embodiment may comprise any of various magnetic field sensors in place of or in addition to a sensing coil. An MSM may for example comprise an Anisotropic Magneto-Resistive (AMR) sensor, an Heusler-compound Magneto- Resistive (HMR) sensor, and / or a Hall effect sensor.

[0011] The IDM receives MSM data that the MSM generates for locations along the trajectory and processes the MSM data to determine characteristics of the magnetic field and if the characteristics indicate an identity (ID) for an intended target of the interceptor. The IDM may use any of various methods, such as Al-based methods or alternative signal-processing, rulebased, or model-based techniques to determine the target ID. Optionally, the IDM comprises or has access to a library comprising for each of a plurality of potential targets a magnetic field profile, also referred to as a magnetic fingerprint. The IDM may process MSM data that the IDM receives to determine a best fit of the MSM data to a magnetic fingerprint in the library to ID the target. A magnetic fingerprint for a given target may by way of example comprise a frequency spectrum and / or a three dimensional spatial mapping of the magnitude and optionally direction of the magnetic field that the target generates relative to a coordinate system fixed to the target.

[0012] In an embodiment an interceptor controller receives MSM data that the MSM may provide for locations along an interceptor trajectory and controls the interceptor responsive thereto. In an embodiment the MSM data that the controller receives comprises a magnitude of the target magnetic field and / or a determination of proximity of the interceptor to the target, or the controller processes MSM data to determine the magnitude and / or proximity. The interceptor controller uses the magnitude and / or proximity to determine when to perform an action, also referred to as a terminal interception action, to complete a purpose (for example destruction, damage, or change of behavior) of an intended engagement with the target. In an embodiment the received MSM data comprises a MAGA or the interceptor controller processes received MSM data to determine the MAGA. The controller may control the interceptor to align and move along the identified MAGA to reduce distance to and engage the target.

[0013] In an embodiment the interceptor controller receives the target ID from the IDM and controls the interceptor trajectory responsive to the target ID.

[0014] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.BRIEF DESCRIPTION OF THE FIGURES

[0015] Non-limiting examples of embodiments of the invention are described below with reference to figures attached hereto that are listed following this paragraph. Identical structures, elements or parts that appear in more than one figure are generally labeled with a same numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are chosen for convenience and clarity of presentation and are not necessarily shown to scale.

[0016] Fig. 1 schematically illustrates an airborne interceptor comprising a MAFA operating to engage an interception target that is a drone, in accordance with an embodiment of the disclosure; and

[0017] Fig. 2 shows a flow diagram that illustrates operation of the MAFA in assisting the interceptor to successfully engage the target in accordance with an embodiment of the disclosure.DETAILED DESCRIPTION

[0018] In the discussion, unless otherwise stated, adjectives such as “substantially” and “about” modifying a condition or relationship characteristic of a feature or features of an embodiment of the disclosure, are understood to mean that the condition or characteristic is defined to within tolerances that are acceptable for operation of the embodiment for an application for which it is intended. Wherever a general term in the disclosure is illustrated by reference to an example instance or a list of example instances, the instance or instances referred to, are by way of nonlimiting example instances of the general term, and the general term is not intended to be limited to the specific example instance or instances referred to. The phrase “in an embodiment”, whether or not associated with a permissive, such as “may”, “optionally”, or “by way of example”, is used to introduce for consideration an example, but not necessarily a required configuration of possible embodiments of the disclosure. Unless otherwise indicated, the word “or” in the description and claims is considered to be the inclusive “or” rather than the exclusive or, and indicates at least one of, or any combination of more than one of items it conjoins. Whereas features and actions of flow diagrams shown in the figures and discussed inthe specification are presented and discussed substantially in an ordered sequence of flow diagram blocks, the features and actions in a given flow diagram may be undertaken in an order other than that presented in the flow diagram and may comprise blocks additional to those shown.

[0019] Fig. 1 schematically shows an interceptor 30 comprising a MAFA 40 engaging a drone 20 optionally with an intention to destroy the drone, in accordance with an embodiment of the disclosure. The drone is assumed to comprise at least one component such as an electric motor or an electric motor control system for example a pulse width modulation (PWM) control system or a combustion engine with spark ignition that generates a magnetic field during operation of the drone.

[0020] In Fig. 1 for convenience of presentation drone 20 is assumed by way of example to be powered by an electric motor 22 that generates the magnetic field. In the figure the magnetic field emanates from a region of the drone that houses the motor and is schematically represented by concentric dashed circles 24. Magnetic field 24 is hereinafter also referred to as a B field 24, or simply B field, where the bold script indicates that the field is a vector field. A magnetic field fingerprint for B field 24 may comprise a frequency spectrum, mapping of field components Bx, By, and Bz, and / or magnitude |B| as a function of spatial coordinates of a coordinate system fixed relative to the body of target 20. MAFA 40 as shown greatly enlarged in an inset 50 comprises an MSM 42, and optionally an INS 44 and an IDM 46. B field 24 has magnitude |B| = (Bx2+ By 2 + Bz2)l / 2.

[0021] MSM 42 is assumed by way of example, to comprise three B field sensing coils (not explicitly shown) configured to provide MSM signals responsive to components of B field 24 for poses along a trajectory that interceptor 40 traverses to engage target 20. The MSM signals and components for a given pose are optionally defined for coordinate axes X, Y, Z of an optionally Cartesian coordinate system 41 fixed relative to the body of interceptor 30. The poses are optionally provided by INS 44, which may also provide velocity (v) and acceleration (a) for each of the poses. Pose, acceleration, and / or velocity may be referred to generically, individually, and / or collectively as INS data.

[0022] MSM 42 comprises or has access to any suitable configuration of hardware and software preprocessing components for preprocessing MSM signals and INS data. The MSM comprises a processor including executable code and / or data, hereinafter referred to as software, for processing preprocessed MSM signals and INS data to generate real time derived MSM data for locations along the trajectory traveled by interceptor 30. Derived MSM data optionallycomprises components Bx, By, and Bz, of B field 24, magnitude |B| of the field, and / or a MAGA equal to a gradient V|B| of the field. In Fig. 1 MAGA for B field 24 at the location of interceptor 30 shown in the figure is represented by a shaded block arrow 26. In an embodiment, the derived MSM data comprises a high pass filtered frequency spectrum for |B| having a lower cutoff frequency L selected to improve signal to noise ratio (SNR) of the spectrum.

[0023] In an embodiment, IDM 46 receives MSM data for B field 24 for a plurality of locations of interceptor 30 along the interceptor’s trajectory and processes the MSM data using any one or any combination of more than one of various methods to determine an ID for drone 20. The methods may comprise artificial intelligence (Al) based methods, rule based methods, and / or model based methods. By way of example, to perform a model based method, the IDM may comprise or have access to a library comprising for each of a plurality of potential targets a magnetic fingerprint. The IDM processes the MSM data for B field 24 to determine a best fit of the MSM data to a magnetic fingerprint in the library to ID the target. Processing may be performed by a processor that the IDM comprises or to which the IDM has access.

[0024] In an embodiment a controller that controls operation of interceptor 30 receives MSM data generated by MSM 42 from MAFA 40 and processes the MSM data to control the interceptor. For example, for received MSM data comprising measures of B field magnitude |B| as a function of location of interceptor 30, the controller may use |B| to control the interceptor to execute a terminal interception action to attempt a successful interception of target 20 if |B| is greater than a predetermined |B| threshold. Alternatively or additionally the controller may trigger a terminal interception action if a rate of change of |B| as a function of location of the interceptor is greater than a predetermined threshold. Alternatively or additionally the controller may use |B| to determine proximity of the interceptor to target 20. If the proximity is less than a predetermined upper bound, the controller may control interceptor 30 to trigger a terminal interception action. For received MSM data comprising MAGA 26 the controller may use the MAGA to direct motion of the interceptor to bring the interceptor to within a range of target 20 advantageous for executing a terminal interception action to complete interception of the target. Optionally, for situations in which received MSM data does not explicitly comprise a MAGA, if the received MSM data is sufficient, the interceptor controller may calculate a MAGA from the MSM data and use the calculated MAGA to direct interceptor motion.

[0025] In an embodiment the interceptor controller receives from MAFA 40 an ID determined by IDM 46 for target 20 and MSM data provided by MSM 42 and MSM data extracted from amagnetic fingerprint of B field 24 for a current location of interceptor 30 provided by INS 44. The interceptor controller may use the MSM 42 data and extracted MSM fingerprint data to control the interceptor. For example, the controller may use the extracted fingerprint MSM data to calibrate the MSM 42 data and magnitude |B| for B field 24 and use the calibrated |B| or function thereof to trigger a terminal interception action. In an embodiment the interceptor controller may use the ID for target 20 to determine whether or not the target is an intended interception target for which the interceptor was launched, and if not an intended target to veer away from target 20 towards another target or abort interception.

[0026] By way of numerical example, assume that the magnetic B field generated by the electric motor in drone 30 may be approximated by a magnetic dipole field. The the magnitude of the |B| of B field 24 decreases with the inverse of the cube of distance from the drone and may be given by an expression |B(r)| = .0M / 4nr^. In the expression for |B(r)|,0is the permeability of free space, AT is a magnetic moment of the motor, and r is distance from the drone. The magnetic moment AT is given by an expression M = NIA where N is a number of coils in the drone motor, A is their cross section area, and I current in the coils. Drone motors are typically relatively small high RPM motors often characterized by a small number of coils N between about 12 to about 14, small coil areas A between about 0.001(square meters) and 0.005 m^, and small operating currents I between about 20Ato 100A (amperes). Assuming the values given in the preceding sentence for the motor in drone 20 the magnetic moment M of the motor may range from about 0.01 Am^ to about 0.1 Am^. If the drone structure shields the magnetic field generated by the motor and reduces the strength of the magnetic B field of the motor outside of the drone by 50%, the motor magnetic B field outside the drone may be approximated by a magnetic field generated by a magnetic moment AT between 0.005 Am^ to about 0.05 Am^.

[0027] In an embodiment, for a relatively small interceptor MSM 42 of MAFA 40 may comprise one or more sensing coils having diameters between about 5 mm and about 10 mm,. Outputs of the sensing coils may be filtered by a high-pass filter and coupled to one or more operational amplifiers (not shown). In an embodiment, the high-pass filter may have a passband extending from about 100 Hz to about 5 kHz, thereby reducing flicker noise and environmental magnetic noise and improving signal-to-noise ratio (SNR). Optionally the outputs of the sensing coils may be filtered by a plurality of high-pass relatively narrow passband filters having passbands tailored to frequency ranges of particular interest.

[0028] For the foregoing parameters of MSM 42, and for a magnetic field B field 24 generated by drone 20 and characterized by a magnetic dipole moment M between about 0.005 A m2and about 0.05 A m2, MSM 42 may operate to detect the magnetic field and generate raw and derived MSM data at interceptor-to-target distances between about 1 m and about 5 m. The generated data may be sufficiently accurate to determine, to within about 0.5 m, an advantageous location at which to trigger a terminal interception action by interceptor 30.

[0029] Fig. 2 shows a flow chart 200 illustrating operation of MAFA 40, in accordance with an embodiment of the disclosure.

[0030] In a block 202 a UAV interception target 20 is detected and in a block 204 an interceptor 30 having a MAFA 40, comprising an MSM 42, & optionally an INS 44, and IDM 46 is launched to intercept the target. A conventional interceptor guidance system directs the interceptor along a trajectory to engage the target. In a block 208 the INS produces navigation data that provides pose, velocity, and acceleration of the interceptor during flight of the interceptor and the MSM generates MSM signals responsive to magnetic fields at locations of the interceptor. Optionally in a block 210 the MSM processes the MSM signals and INS data to determine a B field that the target generates and a real time high bandpass filtered, high SNR frequency spectrum for the B field, vector components (Bx, By, Bz) and magnitude |B| of the target B field. In a block 212 MSM determines a rate of change with distance, d|B| / dr, and optionally a maximum gradient ascent (MAGA) for the B field for a current location of the interceptor. In a decision block 214 MSM determines if magnitude |B| is greater than a predetermined |B| action threshold |B|tand / or d|B| / dr is greater than a predetermined d|B| / dr action threshold (d|B| / dr)th. Optionally, if one or both of |B|tjj and / or d|B| / dr is greater than its respective threshold, in a block 216 MAFA transmits a terminal action signal to a controller of the interceptor that operates to trigger execution of a terminal interception action by the interceptor. On the other hand if neither |B|tnor d|B| / dr is greater than its respective threshold, in a block 218 MAFA may provide the interceptor controller with MAGA to enable the controller to use MAGA to control the interceptor heading.

[0031] It is noted that in the above scenario decision block 214 compares both |B|tjj and d|B| / dr to determine if one or both |B|tand d|B| / dr is / are greater than its threshold to determine whether or not to trigger a terminal interception action. In an embodiment MAFA 40 may be configured to compare only one of |B|tand d|B| / dr to its respective action threshold to determine whether or not to trigger a terminal interception action. In yet another embodimentMAFA may determine whether or not to compare |B|th, d|B| / dr or both |B|tjj and d|B| / dr, where “or” is the exclusive or, to their respective threshold to determine whether or not to trigger a terminal action based on an ID of the target provided by IDM 46.

[0032] Descriptions of embodiments of the invention in the present application are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments utilize only some of the features or possible combinations of the features. Variations of embodiments of the invention that are described, and embodiments of the invention comprising different combinations of features noted in the described embodiments, will occur to persons of the art. The scope of the invention is limited only by the claims.

Claims

CLAIMS1. A method of assisting an interceptor comprising an interceptor controller to engage an interception target, the method comprising:generating signals responsive to magnetic fields to which the interceptor is exposed for locations of the interceptor during motion of the interceptor along a trajectory to intercept the target;processing the signals to determine a signal proportional to the magnetic B field generated by the target as a function of location and / or time of the interceptor along the trajectory;determining one or both of a magnitude |B| and a rate of change of |B|, equal to a spatial or temporal rate of change, d|B| / dr and / or d|B| / dt, as a function of location and / or of time of the interceptor during traversal of the trajectory;determining based on one or both of |B| and the rate of change (d|B| / dr and / or d|B| / dt) whether or not to transmit a terminal action signal to a controller of the interceptor to indicate suitability of controlling the interceptor to execute a terminal interception action with respect to the target.

2. The method according to claim 1 wherein determining whether or not to transmit the terminal action signal comprises determining based on |B|.

3. The method according to claim 2 wherein determining based on |B| comprises determining whether or not |B| is greater than a predetermined |B| threshold.

4. The method according to claim 1 wherein determining whether or not to transmit the terminal action signal comprises determining based on the rate of change (d|B| / dr and / or d|B| / dt).

5. The method according to claim 4 wherein determining based on d|B| / dr comprises determining whether or not d|B| / dr is greater than a predetermined rate of change (d|B| / dr and / or d|B| / dt) threshold.

6. The method according to claim 1 wherein determining whether or not to transmit the terminal action signal comprises determining based on both |B| and the rate of change.

7. The method according to claim 6 wherein determining based on both |B| and the rate of change (d|B| / dr and / or d|B| / dt) comprises determining whether or not |B| is greater than a predetermined |B| threshold and the rate of change is greater than a predetermined rate of change (d|B| / dr and / or d|B| / dt) threshold.

8. The method according to any of the preceding claims wherein determining one or both of the magnitude |B| and d|B| / dr as a function of location of the interceptor comprises determining one or both of |B| and rate of change (d|B| / dr and / or d|B| / dt) responsive to pose of the interceptor during motion of the interceptor along the trajectory.

9. The method according to claim 8 and comprising determining one or both of magnitude |B| and rate of change (d|B| / dr and / or d|B| / dt) responsive to velocity of the interceptor during motion of the interceptor along the trajectory.

10. The method according to any of the preceding claims and further comprising determining a maximum gradient ascent (MAGA) for |B|.

11. The method according to claim 10 wherein if it is determined not to transmit a terminal action signal to the controller transmitting the MAGA to the control so that the controller can use the MAGA to control heading of the interceptor.

12. The method according to any of the preceding claims wherein determining the magnetic B field generated by the target comprises determining an identification, ID, for the target.

13. The method according to claim 12 and further comprising using a magnetic fingerprint associated with the target ID to determine whether or not to transmit the terminal interception action signal.

14. A magnetic field agent (MAFA) for assisting an interceptor in engaging an interception target that generates a magnetic field during operation, the MAFA comprising:a magnetic sensing module (MSM) comprising at least one magnetic field sensor configured to generate real-time sensor signals responsive to a time-varying magnetic field at locations of the interceptor along a trajectory;a processor configured to process the sensor signals to generate magnetic sensing module (MSM) data for a magnetic B field generated by the target, the MSM data comprising a magnitude |B| a spatial rate of change d|B| / dr of |B| of the B field; one or more vector components of the B field of the B field; andan interface configured to provide the MSM data to a controller of the interceptor to assist in controlling the interceptor to engage the interception target.

15. The MAFA in accordance with claim 1 wherein the MSM data additionally comprises, a maximum gradient ascent (MAGA) for magnitude |B|.

16. The MAFA according to claim 14 or claim 15 wherein the at least one magnetic field sensor comprises one or more sensing coils.

17. The MAFA according to claim 16 wherein the at least one or more sensing coils comprises two magnetic field sensors having orthogonal magnetic moments fixed relative to a body coordinate system of the interceptor.

18. The MAFA according to any one of claims 14-17 and further comprising or having access to an interceptor navigation system (INS) configured to generate real-time INS data comprising pose and velocity of the interceptor as the interceptor traverses the trajectory .

19. The MAFA according to claim 18 wherein the processor processes the sensor signals and the INS data to generate and associate the MSM data with spatial locations of the interceptor along the interceptor trajectory.20 The MAFA according to any of claims 14-19 wherein the at least one magnetic field sensor comprises at least one or any combination of more than one of an anisotropic magnetoresistive (AMR) sensor; a Heusler-compound magneto-resistive (HMR) sensor; and / or a Halleffect sensor.

21. The MAFA according to any of claims 14-20 and comprising a target identification module (IDM) configured to process MSM and INS data to determine an ID for the target.

22. The MAFA according to claim 21 wherein the MAFA is configured to provide a magnetic field fingerprint for the target based on the target ID.

23. The MAFA according to any one of claims 14-22 wherein the MAFA is integrated into the interceptor.

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