Unmanned aerial vehicle-mounted passive variable feature camouflage method, device and system

Abstract

The invention provides an unmanned aerial vehicle passive variable feature camouflage method, device and system, and solves the technical problem that the existing variable feature camouflage is poor in SAR (Synthetic Aperture Radar) confrontation effect. The device comprises a passive signal reflection device which is used for forming a reflection echo signal which points to the sky direction and has a determined scattering sectional area; and the unmanned aerial vehicle is used for bearing the passive signal reflection device to be controlled to form a flight path at a determined height. According to the forming characteristics of the SAR, passive variable feature camouflage is formed in an airspace above a ground protected area by using an unmanned aerial vehicle-mounted passive variable feature camouflage device, the passive variable feature camouflage device is combined with an unmanned aerial vehicle, and the passive variable feature camouflage method for the synthetic aperture radar with complex motion modulation characteristics is constructed. And starting from the working principle of the synthetic aperture radar, a variable feature camouflage movement track is designed, and the variable feature camouflage capability of the passive variable feature camouflage device on the synthetic aperture radar is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of radar countermeasure technology, and in particular to a passive variable feature camouflage method, device and system for unmanned aerial vehicles. Background Art

[0002] Synthetic aperture radar variable signature camouflage technology is one of the important issues in the field of radar confrontation. It is of great significance to reduce the reconnaissance capability of the opponent's satellite-borne and airborne imaging radars and improve the concealment and survivability of our high-value targets. At present, corner reflector-type variable signature camouflage has been widely used in variable signature camouflage for high-range resolution radars, radar seekers and other working system radars with low spatial resolution. The main principle is to use the high-power echo signal reflected by it, and through the motion characteristics such as the rotation of the corner reflector, a dynamic corner reflector echo signal different from the static corner reflector can be generated to form a variable signature. Thereby affecting the radar target detection process, it has a significant interference, deception and deception effect on the radar system, and realizes variable signature camouflage. However, this camouflage method is not applicable to radar systems with high two-dimensional spatial resolution capabilities such as synthetic aperture radar (SAR), and it is difficult to achieve effective protection of important areas. Summary of the invention

[0003] In view of the above problems, the embodiments of the present invention provide a method, device and system for passive variable signature camouflage carried by an unmanned aerial vehicle, which solve the technical problem that the existing variable signature camouflage has a poor effect in countering SAR.

[0004] The passive feature-changing camouflage device carried by an unmanned aerial vehicle according to an embodiment of the present invention comprises:

[0005] A passive signal reflection device, used for forming a reflected echo signal with a certain scattering cross-sectional area pointing in the direction of the sky;

[0006] An unmanned aerial vehicle (UAV) is used to carry a passive signal reflecting device and is controlled to form a flight trajectory at a certain altitude.

[0007] In one embodiment of the present invention, the passive signal reflecting device is fixed on the top of the UAV, close to the center of gravity of the aircraft, and the maximum reflected echo radiation direction is located at an angle of 45° to the horizontal plane, so that the horizontal angle of the passive signal reflecting device is kept greater than 30° without obvious obstruction.

[0008] The passive feature-changing camouflage method for an unmanned aerial vehicle according to an embodiment of the present invention comprises:

[0009] Determine the SAR variable signature camouflage initialization parameters;

[0010] Forming basis vectors for SAR signal coordinate system transformation according to initialization parameters;

[0011] A motion trajectory of passive variable feature camouflage is formed in the range-azimuth plane according to the initialization parameters;

[0012] The motion trajectory is converted into the motion trajectory of the northeast sky coordinate system through the SAR basis vector.

[0013] The flight trajectory coordinate information of the UAV is planned according to the motion trajectory of the northeast celestial coordinate system to form flight control instructions.

[0014] In one embodiment of the present invention, determining the SAR variable signature camouflage initialization parameters includes:

[0015] The position of the protected target in the north-east coordinate system is a column vector, denoted by P Tar =(x Tar ,y Tar ,z Tar );

[0016] The maximum flight speed of the UAV without passive variable signature camouflage device is denoted as V max ;

[0017] SAR operating frequency, denoted as f c ;

[0018] SAR flight speed, denoted as V SAR ;

[0019] SAR aperture time, denoted as T SAR ;

[0020] The motion trajectory of SAR at the nth moment in the north-eastern sky coordinate system is recorded as (x SAR (n),y SAR (n),z SAR (n)), where n is the SAR trajectory update sequence number, n = 0, 1, 2, ...;

[0021] SAR track number update time, denoted as PRI;

[0022] The single-aperture variable-signature camouflage period refers to the time required for a single-frame SAR synthetic aperture imaging, which is the number of pulse points in azimuth / the pulse repetition frequency of the system, denoted by K.

[0023] In one embodiment of the present invention, the base vectors for forming the SAR signal coordinate system transformation according to the initialization parameters include:

[0024] According to the signal processing principle of SAR, a quantitative reference for coordinate transformation of SAR motion direction and detection direction is formed.

[0025] In one embodiment of the present invention, the motion trajectory of passive variable feature camouflage formed in the range-azimuth plane according to the initialization parameters includes:

[0026] According to the signal processing principle of SAR, the quantification of the motion trajectory caused by passive variable feature camouflage is formed in the two-dimensional measurement plane of range-azimuth, which is correlated with the SAR signal.

[0027] In one embodiment of the present invention, the step of converting the motion trajectory into the motion trajectory of the northeast sky coordinate system by using the SAR basis vector includes:

[0028] The motion trajectory of the passive variable feature camouflage is determined in the northeast celestial coordinate system through coordinate system mapping.

[0029] In one embodiment of the present invention, the step of planning the flight trajectory coordinate information of the drone according to the motion trajectory of the northeast sky coordinate system to form a flight control instruction includes:

[0030] Coordinate sampling is performed to form a coordinate information sequence, and flight control instructions for the UAV equipped with a passive signal reflection device are formed based on the coordinate information sequence to control the UAV to form continuous flight in the airspace above the protected area on the ground.

[0031] The passive feature-changing camouflage device carried by an unmanned aerial vehicle according to an embodiment of the present invention comprises:

[0032] A memory, used to store program codes corresponding to the processing process of the passive variable feature camouflage method for unmanned aerial vehicles as described in any one of claims 3 to 8; a processor, used to execute the program codes.

[0033] The passive feature-changing camouflage device carried by an unmanned aerial vehicle according to an embodiment of the present invention comprises:

[0034] An initial setting device, used to determine the SAR variable signature camouflage initialization parameters;

[0035] A reference calibration device, used to form a basis vector for SAR signal coordinate system transformation according to initialization parameters;

[0036] A trajectory forming device, used for forming a motion trajectory of passive variable feature camouflage in a range-azimuth plane according to initialization parameters;

[0037] A trajectory conversion device, used for converting the motion trajectory into a motion trajectory of the northeast sky coordinate system through SAR basis vectors;

[0038] The trajectory instruction device is used to plan the flight trajectory coordinate information of the UAV according to the motion trajectory of the northeast sky coordinate system to form a flight control instruction.

[0039] The unmanned aerial vehicle passive variable signature camouflage method, device and system of the embodiments of the present invention utilize the unmanned aerial vehicle passive variable signature camouflage device to form passive variable signature camouflage in the airspace above the protected area on the ground according to the forming characteristics of SAR, and combine the passive variable signature camouflage device with the unmanned aerial vehicle to construct a synthetic aperture radar passive variable signature camouflage method with complex motion modulation characteristics. Starting from the working principle of synthetic aperture radar, the variable signature camouflage motion trajectory is designed, which significantly improves the variable signature camouflage capability of the passive variable signature camouflage device against the synthetic aperture radar. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Shown is a schematic structural diagram of a passive variable feature camouflage device mounted on an unmanned aerial vehicle according to an embodiment of the present invention.

[0041] Figure 2 The figure is a schematic flow chart of a passive variable feature camouflage method for unmanned aerial vehicles according to an embodiment of the present invention.

[0042] Figure 3 FIG. 1 is a schematic diagram showing the position of the north-east celestial coordinate system in the passive variable feature camouflage method for unmanned aerial vehicles according to an embodiment of the present invention.

[0043] Figure 4 The figure shows a schematic diagram of a flight trajectory of a UAV in a passive variable feature camouflage method for UAV according to an embodiment of the present invention.

[0044] Figure 5 The figure is a schematic diagram showing a comparison of the effects of applying the passive variable feature camouflage method carried by an unmanned aerial vehicle according to an embodiment of the present invention.

[0045] Figure 6 FIG. 1 is a schematic diagram of the architecture of a passive variable-signature camouflage system for unmanned aerial vehicles according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the present invention clearer and more understandable, the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The architecture of the passive variable feature camouflage device mounted on a drone according to an embodiment of the present invention is as follows: Figure 1 As shown. Figure 1 As shown, this embodiment includes:

[0048] The passive signal reflecting device 1 is used to form a reflected echo signal with a certain scattering cross-sectional area pointing to the sky. The passive signal reflecting device includes but is not limited to a corner reflector, a Luneberg lens, and the like.

[0049] Drone 2 is used to control the flight trajectory at a certain height. The drone can move along the specified trajectory according to the user's instructions. The drone control instructions are generally movement trajectory instructions in the WGS84 coordinate system or the Northeast Sky coordinate system. When the drone is in flight, the top of the drone faces the sky.

[0050] The passive signal reflection device is fixed on the top of the drone, close to the center of gravity of the aircraft. The maximum reflected echo radiation direction is located at a 45° angle to the horizontal plane. The horizontal angle of the passive signal reflection device is kept greater than 30° without obvious obstruction. The above assembly structure can ensure that the passive variable feature camouflage device vibrates less when the drone is running, the signal strength in the echo radiation direction is more direct, and the signal strength and coverage range are not damaged.

[0051] The passive variable feature camouflage device carried by an unmanned aerial vehicle in the embodiment of the present invention realizes the controlled movement of the coverage area of ​​the reflection signal. A reflection signal source is formed between the protected area on the ground and the SAR signal receiving device. The reflection signal source moves sequentially along the controlled trajectory while forming a change in the direction of the reflection signal, forming a continuous multi-directional interference signal in the time domain. The reflection signal source is controlled and adjustable.

[0052] An unmanned aerial vehicle passive variable feature camouflage method according to an embodiment of the present invention is as follows Figure 2 As shown. Figure 2 In this embodiment, the present invention comprises:

[0053] Step 100: Determine initialization parameters of SAR variable signature camouflage.

[0054] In order to achieve variable feature camouflage for SAR, a series of initialization parameters related to SAR need to be obtained, including:

[0055] The position of the protected target in the north-east coordinate system is a column vector, denoted by P Tar =(x Tar ,y Tar ,z Tar );

[0056] The geographical location of the above-mentioned north-east coordinate system is defined as follows Figure 3 As shown. Figure 3 The North-East coordinate system is a coordinate system defined by the tangent plane at a certain point O in the WGS84 coordinate system. The origin of the coordinate system is O, the N axis is aligned with the due north, the E axis is aligned with the due east, and the U axis coincides with the ellipse normal at O, forming the North-East coordinate system.

[0057] The maximum flight speed of the UAV without passive variable signature camouflage device is denoted as V max ;

[0058] SAR operating frequency, denoted as fc ;

[0059] SAR flight speed, denoted as V SAR ;

[0060] SAR aperture time, denoted as T SAR ;

[0061] The motion trajectory of SAR at the nth moment in the north-eastern sky coordinate system is recorded as (x SAR (n),y SAR (n),z SAR (n)), where n is the SAR trajectory update sequence number, n = 0, 1, 2, ...;

[0062] SAR track number update time, denoted as PRI;

[0063] The single-aperture variable-signature camouflage period refers to the time required for a single-frame SAR synthetic aperture imaging, which is the number of pulse points in azimuth / the pulse repetition frequency of the system, denoted by K.

[0064] In one embodiment of the present invention, it is assumed that the coordinates of the protected target in the north-east celestial coordinate system are Tar =(0,0,0); UAV maximum flight speed V max =20m / s; SAR operating frequency f c =10GHz; SAR flight speed V SAR =7000m / s; SAR aperture time T SAR =3s; single aperture variable feature camouflage period K = 5.

[0065] Step 200: forming basis vectors for SAR signal coordinate system transformation according to initialization parameters.

[0066] According to the signal processing principle of SAR, a quantitative benchmark for coordinate transformation of SAR motion direction and detection direction is formed. It includes:

[0067] Forming SAR eastward velocity v x ,

[0068] Forming SAR northward velocity v y ,

[0069] Form the SAR azimuth basis vector B v , is a column vector;

[0070] Form the basis vector B of the SAR range direction u , is a column vector.

[0071] Step 300: forming a motion trajectory of passive variable feature camouflage in the range-azimuth plane according to the initialization parameters.

[0072] According to the signal processing principle of SAR, the quantification of the motion trajectory related to the SAR signal in the two-dimensional measurement plane of distance-azimuth is formed to cause passive variable feature camouflage. Including:

[0073] Forming the UAV periodic motion radius R Jam ,

[0074] Forming the UAV periodic motion frequency W Jam ,

[0075] Form the minimum variable characteristic camouflage speed V of the UAV in the azimuth direction Jam_min (minimum speed in azimuth),

[0076] Form the UAV's azimuth-changing characteristic camouflage speed V Jam , V Jam >V Jam_min ;

[0077] Form the UAV distance motion trajectory u Jam (t),u Jam (t) = R Jam ×cos(2πW Jam t) obtain;

[0078] Form the UAV azimuth motion trajectory vJ am (t), v Jam (t) = R Jam ×sin(2πW Jam t)+V Jam ×t.

[0079] In one embodiment of the present invention, the UAV periodic motion radius R Jam is 6 meters; the UAV periodic motion frequency W Jam The minimum variable feature camouflage speed V of the drone in azimuth is 1.667Hz. Jam_min is 3.5m / s; select the UAV azimuth variable characteristic camouflage speed V Jam =4m / s; then determine the UAV distance to the trajectory u Jam (t) and the azimuth trajectory of the UAV v Jam (t).

[0080] Step 400: Convert the motion trajectory into a motion trajectory of the northeast sky coordinate system through SAR basis vectors.

[0081] The motion trajectory of the passive variable feature camouflage is determined in the northeast sky coordinate system through coordinate system mapping. Including:

[0082] The motion trajectory of the northeast sky coordinate system P Jam (t)Through

[0083] P Jam (t) = B u ×u Jam (t)+B v ×v Jam (t)+P Tar form.

[0084] Step 500: Plan the flight trajectory coordinate information of the UAV according to the motion trajectory of the northeast celestial coordinate system to form a flight control instruction.

[0085] Using the motion trajectory P of the northeast celestial coordinate system Jam (t) Coordinate sampling is performed to form a coordinate information sequence, and flight control instructions for the UAV equipped with a passive signal reflection device are formed according to the coordinate information sequence, so as to control the UAV to form a continuous flight in the airspace above the protected area on the ground, thereby realizing the passive variable feature camouflage of the UAV in the northeast sky coordinate system and countering SAR detection.

[0086] The unmanned aerial vehicle-borne passive variable signature camouflage method of the embodiment of the present invention uses an unmanned aerial vehicle-borne passive variable signature camouflage device to form a passive variable signature camouflage in the airspace above the protected area on the ground according to the forming characteristics of SAR, and combines the passive variable signature camouflage device with the unmanned aerial vehicle to construct a synthetic aperture radar passive variable signature camouflage method with complex motion modulation characteristics. Starting from the working principle of synthetic aperture radar, the variable signature camouflage motion trajectory is designed, which significantly improves the variable signature camouflage capability of the passive variable signature camouflage device against the synthetic aperture radar.

[0087] In an embodiment of the present invention, a UAV-mounted passive variable feature camouflage method has a flight trajectory such as Figure 4 As shown. Figure 4 In the process, the synthetic aperture radar moves in a straight line in a plane, the protected object on the ground remains stationary, and the passive variable feature camouflage device on the drone makes a compound circular and linear motion in the plane (i.e. spiral advance). The motion trajectory remains unchanged in each cycle, and the circular motion radius is R Jam , the linear motion can be along the up, down, left, and right directions in the figure. The range motion of the passive variable signature camouflage device on the unmanned aerial vehicle refers to the linear motion along the line of sight of the synthetic aperture radar, while the azimuth motion is the motion component along the flight direction of the radar. In the application, the spatial position relationship between the ground protected object, the passive variable signature camouflage device on the unmanned aerial vehicle, and the SAR is not limited to that shown in this figure.

[0088] Comparison of application effects of the passive variable feature camouflage method for unmanned aerial vehicles according to an embodiment of the present invention Figure 5 As shown. Figure 5 In the figure, part (a) is a simulated SAR image without variable feature camouflage conditions, and part (b) is a variable feature camouflage effect diagram of the passive variable feature camouflage method onboard an unmanned aerial vehicle proposed in the present invention. It can be seen that the method of the present invention can achieve effective variable feature camouflage coverage of the target.

[0089] An unmanned aerial vehicle-mounted passive feature-changing camouflage device according to an embodiment of the present invention comprises:

[0090] A memory, used to store program codes corresponding to the processing process of the passive feature-changing camouflage method for unmanned aerial vehicles in the above-mentioned embodiment;

[0091] The processor is used to execute the program code corresponding to the processing process of the passive feature-changing camouflage method for unmanned aerial vehicles in the above-mentioned embodiment.

[0092] The processor may be a DSP (Digital Signal Processor) digital signal processor, an FPGA (Field-Programmable Gate Array) field programmable gate array, an MCU (Microcontroller Unit) system board, a SoC (system on a chip) system board, or a PLC (Programmable Logic Controller) minimum system including I / O.

[0093] An unmanned aerial vehicle passive variable feature camouflage system according to an embodiment of the present invention is as follows Figure 6 As shown. Figure 6 In this embodiment, the present invention comprises:

[0094] Initial setting device 10, used to determine SAR variable signature camouflage initialization parameters;

[0095] A reference calibration device 20, for forming a basis vector for SAR signal coordinate system transformation according to initialization parameters;

[0096] A trajectory forming device 30, used to form a motion trajectory of passive variable feature camouflage in a range-azimuth plane according to initialization parameters;

[0097] The trajectory conversion device 40 is used to convert the motion trajectory into the motion trajectory of the northeast sky coordinate system through the SAR basis vector;

[0098] The trajectory instruction device 50 is used to plan the flight trajectory coordinate information of the UAV according to the motion trajectory of the northeast celestial coordinate system to form a flight control instruction.

[0099] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A passive variable feature camouflage device for unmanned aerial vehicles, characterized in that: include: A passive signal reflection device, used for forming a reflected echo signal with a certain scattering cross-sectional area pointing in the direction of the sky; An unmanned aerial vehicle (UAV) is used to carry a passive signal reflecting device and is controlled to form a flight trajectory at a certain altitude.

2. The passive feature-changing camouflage device for unmanned aerial vehicles according to claim 1, characterized in that: The passive signal reflecting device is fixed on the top of the UAV, close to the center of gravity of the aircraft, and the maximum reflected echo radiation direction is located at an angle of 45° to the horizontal plane, and the horizontal angle of the passive signal reflecting device is kept greater than 30° in the direction range without obvious obstruction.

3. A passive variable feature camouflage method for unmanned aerial vehicles, characterized in that: include: Determine the SAR variable signature camouflage initialization parameters; Forming basis vectors for SAR signal coordinate system transformation according to initialization parameters; A motion trajectory of passive variable feature camouflage is formed in the range-azimuth plane according to the initialization parameters; The motion trajectory is converted into the motion trajectory of the northeast sky coordinate system through the SAR basis vector. The flight trajectory coordinate information of the UAV is planned according to the motion trajectory of the northeast celestial coordinate system to form flight control instructions.

4. The passive feature-changing camouflage method for unmanned aerial vehicles as claimed in claim 3, characterized in that: Determining the SAR variable signature camouflage initialization parameters includes: The position of the protected target in the north-east coordinate system is a column vector, denoted by PT ar =(x Tar ,y Tar ,z Tar ); The maximum flight speed of the UAV without passive variable signature camouflage device is denoted as V max ; SAR operating frequency, denoted as f c ; SAR flight speed, denoted as V SAR ; SAR aperture time, denoted as T SAR ; The motion trajectory of SAR at the nth moment in the north-eastern sky coordinate system is recorded as (x SAR (n),y SAR (n),z SAR (n)), where n is the SAR trajectory update sequence number, n = 0, 1, 2, ...; SAR track number update time, denoted as PRI; The single-aperture variable-signature camouflage period refers to the time required for a single-frame SAR synthetic aperture imaging, which is the number of pulse points in azimuth / the pulse repetition frequency of the system, denoted by K.

5. The passive variable feature camouflage method for unmanned aerial vehicles as claimed in claim 3, characterized in that: The base vectors for forming the SAR signal coordinate system conversion according to the initialization parameters include: According to the signal processing principle of SAR, a quantitative reference for coordinate transformation of SAR motion direction and detection direction is formed.

6. The passive variable feature camouflage method for unmanned aerial vehicles as claimed in claim 3, characterized in that: The motion trajectory of forming passive variable feature camouflage in the range-azimuth plane according to the initialization parameters includes: According to the signal processing principle of SAR, the quantification of the motion trajectory related to the SAR signal causing the passive variable feature camouflage in the two-dimensional measurement plane of range-azimuth is formed.

7. The passive feature-changing camouflage method for unmanned aerial vehicles as claimed in claim 3, characterized in that: The step of converting the motion trajectory into the motion trajectory of the northeast sky coordinate system by using the SAR basis vector comprises: The motion trajectory of the passive variable feature camouflage is determined in the northeast celestial coordinate system through coordinate system mapping.

8. The passive feature-changing camouflage method for unmanned aerial vehicles as claimed in claim 3, characterized in that: The step of planning the flight trajectory coordinate information of the UAV according to the motion trajectory of the northeast sky coordinate system to form a flight control instruction includes: Coordinate sampling is performed to form a coordinate information sequence, and flight control instructions for the UAV equipped with a passive signal reflection device are formed based on the coordinate information sequence to control the UAV to form continuous flight in the airspace above the protected area on the ground.

9. A passive variable feature camouflage device carried by an unmanned aerial vehicle, characterized in that: include: A memory, used to store program codes corresponding to the processing process of the passive variable feature camouflage method for unmanned aerial vehicles as claimed in any one of claims 3 to 8; A processor is used to execute the program code.

10. A passive variable feature camouflage device carried by an unmanned aerial vehicle, characterized in that: include: An initial setting device, used to determine the SAR variable signature camouflage initialization parameters; A reference calibration device, used to form a basis vector for SAR signal coordinate system transformation according to initialization parameters; A trajectory forming device, used for forming a motion trajectory of passive variable feature camouflage in a range-azimuth plane according to initialization parameters; A trajectory conversion device, used for converting the motion trajectory into a motion trajectory of the northeast sky coordinate system through SAR basis vectors; The trajectory instruction device is used to plan the flight trajectory coordinate information of the UAV according to the motion trajectory of the northeast sky coordinate system to form a flight control instruction.

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