Omnibearing low-false-alarm-rate real-time detection method and system based on active and passive combination

Abstract

The invention discloses an omnibearing low-false-alarm-rate real-time detection method and system based on active and passive combination, and belongs to the field of airborne alarm. The method comprises the following steps: acquiring an infrared image of an area where a target is located through a real-time detection device; performing differential filtering calculation on the infrared image to obtain a differential image; setting a threshold value, and carrying out binarization target segmentation on pixel points in the image one by one to obtain a binarization image; carrying out mark fusion on a target by adopting a run-length coding method according to the binary image; carrying out target position prediction and track maintenance by adopting a sequence image target association technology; and judging a threat target by using the difference characteristics. According to the invention, the environment and the target are detected in real time through the detection device, and the detected data are sent to the information processing device; and processing the acquired data through an information processing device so as to select a threat target from the infrared image.

Description

Technical Field

[0001] The invention belongs to the field of airborne warning, and in particular relates to an omnidirectional low false alarm rate real-time detection method and system based on active and passive combination. Background Art

[0002] Among all modern aircraft, helicopters have the mission attributes of low-altitude aviation mission execution platforms, but they also have certain weaknesses. Helicopters have poor concealment. When flying at low altitudes, their obvious infrared characteristics, radar radio frequency characteristics, and acoustic characteristics can easily be discovered by ground personnel. When helicopters fly at low altitudes and low speeds or hover due to mission requirements, they are easily attacked by the enemy. If you want to effectively protect yourself, the most effective way is to detect the enemy first and "strike first". It only takes a few seconds from the launch of the threat target to the hit, leaving the helicopter with an extremely short warning response time. Existing protection measures are also difficult to effectively detect and respond to close-range and fast-moving threat targets. Therefore, it is particularly important to conduct all-round, low false alarm rate, real-time detection and target detection of close-range, high-speed flying targets in a short period of time.

[0003] The basic idea of ​​the existing target detection algorithm is to first select a spatial filtering algorithm to perform background suppression filtering on the grayscale image, extract suspected infrared targets, improve the target signal-to-noise ratio, and suppress interference such as background noise; secondly, design a suitable false alarm suppression strategy based on the different characteristics of the target and false alarm, and fully suppress false alarms while ensuring the detection probability of infrared day targets. However, since the spatial filtering algorithm requires enhanced preprocessing of the target to suppress some weaker cloud false alarms and ground clutter false alarms, it takes a long time to process and cannot meet the system's requirements for response time; and for threat targets in the shortwave band, it is currently impossible to effectively detect and suppress false alarms for threat targets using only a single band. Therefore, it is necessary to select a suitable filtering algorithm and false alarm suppression method to improve the target detection probability and reduce the false alarm rate. Summary of the invention

[0004] Technical issues to be solved:

[0005] In order to avoid the shortcomings of the prior art, the present invention provides an all-round low false alarm rate real-time detection method and system based on active and passive combination, which detects the environment and target in real time through a detection device, and sends the detected data to an information processing device; the acquired data is processed by the information processing device to select the threat target in the infrared image, and further adopts feature definition methods such as two-color judgment and ignition detection to detect the threat target and suppress false alarms. The present invention solves the problem that the conventional target detection algorithm takes a long time and cannot effectively detect and suppress false alarms for threat targets only through a single band.

[0006] The technical solution of the present invention is: a comprehensive low false alarm rate real-time detection method based on active and passive combination, the specific steps are as follows:

[0007] Acquire infrared images of the target area through real-time detection devices;

[0008] Performing differential filtering calculation on the infrared image to obtain a differential image;

[0009] Set the threshold, perform binary target segmentation on each pixel in the image, and obtain a binary image;

[0010] The binary image is subjected to target labeling fusion by using a run length coding method;

[0011] The target position prediction and trajectory maintenance are performed using the sequence image target association technology. The threat target exhibits stable movement direction and speed during flight, while the movement trajectory of background clutter false alarms is random. Based on this feature, false alarms are eliminated to obtain candidate threat targets.

[0012] The threat target is judged by the difference characteristics; the threat target generates infrared characteristics when it emits. According to the temporal and spatial distribution characteristics of the infrared characteristics in the imaging of the real-time detection device, the difference characteristics between the threat target and the non-threat target are judged, and then the threat target is confirmed.

[0013] A further technical solution of the present invention is: the real-time detection device adopts an ultra-high frame rate of 1000HZ, and adopts an inter-frame difference method when performing differential filtering calculations on infrared images. The pixel points corresponding to different frames are subtracted to determine the absolute value of the grayscale difference. When the absolute value exceeds a set threshold, it is determined to be a moving target, thereby realizing the detection function of a moving target.

[0014] A further technical solution of the present invention is: the mark fusion is to continuously search around the detected suspected pixel points, and if there are other suspected points, they are continuously marked and connected until all the pixel points are searched.

[0015] A further technical solution of the present invention is: after the candidate threat target is detected, a feature definition method of two-color judgment or ignition detection is used to further complete the detection of the threat target and false alarm suppression.

[0016] A further technical solution of the present invention is: in the process of judging the threat target, the clutter detected by the threat target is the sunlight reflection of the ground object, and based on the different spectral characteristics between the clutter and the threat target, a dual-band design is used to eliminate false alarms.

[0017] An all-round low false alarm rate real-time detection system based on active-passive combination includes a plurality of real-time detection devices and information processing devices arranged along the circumference. The data sent by each real-time detection device is processed by the information processing device to intercept threat targets.

[0018] A further technical solution of the present invention is: the number of the real-time detection devices is 4, each of which has a field of view greater than 95° and is installed around the carrier aircraft to achieve 360° all-round monitoring and confirmation of incoming threat targets.

[0019] A further technical solution of the present invention is: the real-time detection device comprises an infrared image acquisition module, and the infrared image acquisition module comprises a medium-wave infrared optical lens, a medium-wave infrared detector, a filter wheel, a short-wave infrared optical lens, and a short-wave infrared detector;

[0020] The medium-wave infrared optical lens adopts f-θ equidistant projection imaging mode, and the optical system adopts a secondary imaging optical path configuration, which is used to receive infrared radiation energy of the target and background in the field of view and converge it onto the medium-wave infrared detector for imaging;

[0021] The medium-wave infrared detector adopts a medium-wave monochromatic infrared detector with a wavelength of 3.7um to 4.8um and a surface array of 640×512 to provide sufficient angular resolution;

[0022] The filter wheel uses a motor to drive the filter wheel mechanism, and controls the filter wheel to run at a certain speed, and cooperates with the medium-wave infrared detector to perform dual-color imaging;

[0023] The short-wave infrared optical lens adopts f-θ equidistant projection imaging mode, and the optical system adopts secondary imaging optical path configuration, which is used to receive infrared radiation energy of the target and background in the field of view and converge it onto the short-wave infrared detector for imaging. The filter transmission bands in the two short-wave lenses are 0.9um~1.1um and 1.5um~1.7um respectively;

[0024] The short-wave infrared detector adopts a short-wave monochromatic infrared detector with a waveband of 0.9um to 1.7um, an array of 640×512, an actual effective array of 256×204, and a frame rate of 1000 Hz.

[0025] A further technical solution of the present invention is: the real-time detection device also includes an antenna array, a radar sensor, a frequency synthesis transceiver component, and a collection preprocessing component;

[0026] The antenna array adopts a Ku-band active phased array antenna, has a two-dimensional electronic scanning capability, can parse the input control commands and synchronize the timing to control the array, and form the radar beam required for work;

[0027] The radar sensor is used to obtain high-precision target distance and closing speed information.

[0028] The frequency synthesis transceiver component provides a reference frequency signal for the radar sensor, transmits an excitation waveform signal, receives a target echo signal, and performs frequency conversion for subsequent signal acquisition and processing; the frequency synthesis transceiver component has the functions of excitation waveform signal transmission, frequency conversion, gain control, filtering, and self-detection;

[0029] The acquisition preprocessing component can perform echo acquisition and signal processing, acquire the reference clock signal sent by the frequency synthesis transceiver component, and then perform pulse compression, PD processing, space-time processing, and target detection signal processing on the acquired data.

[0030] A further technical solution of the present invention is: the real-time detection device is interconnected with the information processing device via a data transmission bus.

[0031] Beneficial Effects

[0032] The beneficial effects of the present invention are as follows: the present invention uses a real-time detection device to perform all-round detection around the carrier aircraft, and transmits the detection data to an information processing device, which processes the data to confirm the threat target, and can warn or intercept the target object based on the confirmed target. The specific advantages are as follows:

[0033] 1. The present invention adopts an inter-frame difference algorithm, and can use the 1000Hz ultra-high frame rate of the device to monitor the background changes between two adjacent frames. Since the engine of the threat target will emit a lot of heat at the moment of ignition, a point target with a rapid increase in brightness, size and signal-to-noise ratio in a short period of time will be seen in the field of view. This feature is obviously different from the heat source in the composite background of the air and ground. In addition, since the grayscale value of the scene detected by the detector itself also fluctuates, corresponding restrictions are set. If the background change in a specific area is small and within the set limit range, this area can be considered as the background. Therefore, directly performing inter-frame difference on two adjacent frames of images can effectively solve the problem of identifying threat targets.

[0034] 2. The present invention adopts a technology for judging threat targets based on differential features, which can further confirm the threat through the differential features between threat targets and non-threat targets. The reflection of sunlight from ground objects is the most important clutter interference for threat target detection. Since the spectral characteristics of clutter and threat targets are different, false alarms can be eliminated through a dual-band design. In the range of 0.9μm to 1.7μm, the radiation of threat targets gradually increases, while the radiation intensity of sunlight reflection clutter gradually decreases. The two have opposite trends. Therefore, the two ends of the 0.9μm to 1.7μm band are selected as dual bands. The difference in the dual color ratio is large, so the differential features can be used to further distinguish real threat targets from false alarms. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the composition of an all-round low false alarm rate real-time detection system based on active and passive combination in an embodiment of the present invention.

[0036] Figure 2 It is a schematic diagram of the composition of the real-time detection device in an embodiment of the present invention.

[0037] Explanation of the reference numerals: 100, detection and alarm system; 101A, 101B, 101C, 101D, real-time detection device; 102, information processing device; 103, data transmission bus; 201, medium-wave infrared optical lens; 202, medium-wave infrared detector; 203, filter wheel; 204, short-wave infrared optical lens; 205, short-wave infrared detector; 206, antenna array; 207, frequency synthesis transceiver component; 208, acquisition preprocessing component. DETAILED DESCRIPTION

[0038] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0039] Based on the existing target detection algorithm, since the spatial domain filtering algorithm needs to enhance the pre-processing of the target and suppress some weak cloud false alarms and ground clutter false alarms, it takes a long time to process and cannot meet the system's requirements for response time; and for the threat targets in the shortwave band, the threat targets cannot be effectively detected and false alarms cannot be suppressed by only a single band. The present invention provides an all-round low false alarm rate real-time detection method based on active and passive combination, and the specific steps are as follows:

[0040] Step 1: Obtain an infrared image of the target area through a real-time detection device;

[0041] The real-time detection device adopts an ultra-high frame rate of 1000HZ and uses the inter-frame difference method when performing differential filtering calculations on infrared images. The pixel points corresponding to different frames are subtracted to determine the absolute value of the grayscale difference. When the absolute value exceeds the set threshold, it is determined to be a moving target, thereby realizing the detection function of moving targets.

[0042] Step 2: performing differential filtering calculation on the infrared image to obtain a differential image;

[0043] Step 3: Set the threshold and perform binary target segmentation on each pixel in the image to obtain a binary image;

[0044] Step 4: The binary image is marked and fused with the target by using the run length encoding method; for the detected suspected pixel points, the surrounding of the pixel points is continuously searched, and if there are other suspected points, they are continuously marked and connected until all the pixel points are searched.

[0045] Step 5: Use the sequence image target association technology to predict the target position and maintain the trajectory. The threat target has stable movement direction and speed during flight, and the movement trajectory of the background clutter false alarm is random. According to this feature, the false alarm is eliminated to obtain the candidate threat target.

[0046] After the candidate threat target is detected, a feature definition method of two-color judgment or ignition detection is used to further detect the threat target and suppress false alarms.

[0047] Step 6: Use differential features to determine the threat target; when the threat target emits, it generates infrared features. According to the temporal and spatial distribution characteristics of the infrared features in the imaging of the real-time detection device, the differential features between the threat target and the non-threat target are determined, and then the threat target is confirmed. In the process of determining the threat target, the clutter detected by the threat target is the reflection of sunlight from ground objects. Based on the different spectral features between the clutter and the threat target, a dual-band design is used to eliminate false alarms.

[0048] The present invention discloses an omnidirectional low false alarm rate real-time detection system based on active-passive combination, comprising a plurality of real-time detection devices and information processing devices arranged along the circumference, and the data sent by each real-time detection device is processed by the information processing device to intercept threat targets.

[0049] The above technical solution is further described below with reference to the accompanying drawings and examples:

[0050] Reference Figure 1 As shown, the present embodiment is an all-round low false alarm rate real-time detection system based on active and passive combination, including: 101A, 101B, 101C, 101D, four real-time detection devices with the same configuration installed at different positions of the carrier aircraft; 102, an information processing device; 103, a data transmission bus.

[0051] The real-time detection devices 101A, 101B, 101C, and 101D are four threat target warning devices with the same configuration installed at different positions of the aircraft. The real-time detection devices 101A, 101B, 101C, and 101D are interconnected with the information processing device 102 via a data transmission bus 103 .

[0052] Each of the real-time detection devices 101A, 101B, 101C, and 101D has a field of view greater than 95°. By installing four real-time detection devices at appropriate locations around the aircraft, 360° all-round monitoring and confirmation of incoming threat targets can be achieved.

[0053] The information processing device 102 is installed in the aircraft equipment cabin and is used to process data from four real-time detection devices, including infrared image data processing, pulse Doppler radar data processing, infrared and radar data fusion, measuring the distance, angle and speed of incoming threat targets, threat target confirmation, calculating the remaining time for incoming threat targets to hit the carrier aircraft, and guiding and controlling interference objects and interceptors to intercept incoming threat targets.

[0054] The data transmission bus 103 is used to interconnect the real-time detection devices 101A, 101B, 101C, 101D with the information processing device 102. The data transmission bus 103 can be, but is not limited to, an SRIO bus, an RS422 bus, etc.

[0055] Reference Figure 2 As shown, the real-time detection device includes: 201, medium-wave infrared optical lens; 202, medium-wave infrared detector; 203, filter wheel; 204, short-wave infrared optical lens; 205, short-wave infrared detector; 206, antenna array; 207, frequency synthesis transceiver component; 208, acquisition preprocessing component.

[0056] The medium-wave infrared optical lens 201 adopts f-θ equidistant projection imaging mode, and the optical system adopts a secondary imaging optical path configuration to receive infrared radiation energy of the target and background in the field of view and converge it onto the medium-wave infrared detector 202 for imaging.

[0057] The medium-wave infrared detector 202 is a medium-wave monochromatic infrared detector with a wavelength range of 3.7um to 4.8um and an array size of 640×512 to provide sufficient angular resolution.

[0058] The filter wheel 203 uses a motor to drive the filter wheel mechanism and controls the filter wheel to run at a certain speed, and cooperates with the medium-wave infrared detector 202 to perform dual-color imaging.

[0059] The short-wave infrared optical lens 204 adopts f-θ equidistant projection imaging mode, and the optical system adopts a secondary imaging optical path configuration, which is used to receive the infrared radiation energy of the target and background in the field of view, and converge it onto the short-wave infrared detector 205 for imaging. The filter transmission bands in the two short-wave lenses are 0.9um~1.1um and 1.5um~1.7um respectively.

[0060] The short-wave infrared detector 205 is a short-wave monochromatic infrared detector with a wavelength of 0.9um to 1.7um, an array of 256×204, and a frame rate of 1000 Hz.

[0061] The antenna array 206 adopts a Ku-band active phased array antenna and has a two-dimensional electronic scanning capability. It can parse the input control commands and synchronize the timing to control the array and form the radar beam required for work. The antenna array 206 has different beam angle modes according to the working state requirements, such as a wide beam mode for searching and a narrow beam mode for tracking.

[0062] The frequency synthesis transceiver component 207 provides the radar system with a reference frequency signal, transmits an excitation waveform signal, receives a target echo signal, and performs frequency conversion for subsequent signal acquisition and processing. The frequency synthesis transceiver component 207 has functions such as excitation waveform signal transmission, frequency conversion, gain control, filtering, and self-detection.

[0063] The acquisition preprocessing component 208 can perform echo acquisition and signal processing. The acquisition preprocessing component 208 acquires the reference clock signal sent by the frequency synthesis transceiver component 207, and the acquired data is then subjected to signal processing such as pulse compression, PD processing, space-time processing, and target detection.

[0064] Furthermore, the information processing device 102 in this embodiment is used to process the infrared image data, pulse Doppler radar data, infrared and radar data sent by the real-time detection device, measure the distance, angle and speed of the incoming threat target, confirm the threat target, calculate the remaining time for the incoming threat target to hit the carrier aircraft, and guide and control interference objects and interceptors to intercept the incoming threat target.

[0065] The infrared and radar data are subjected to a modified K-nearest-neighbor infrared-radar track fusion algorithm, which can effectively obtain the angle, speed and distance information of the target track while further suppressing false alarms. Infrared sensors can provide target angle track information with high accuracy, but cannot provide target distance and speed information, while radar sensors can only provide target distance and approach speed information with high accuracy. Correct infrared / radar track association and fusion are required to obtain target angle, speed and distance track information with high accuracy. Correct track association is the key to the entire track data processing. The modified K-nearest-neighbor infrared-radar track fusion algorithm solves the problem of repeated tracking in the sensor field of view coverage area through methods such as time registration, space registration and distributed sensor fusion tracking, and can achieve real-time high-precision positioning of threat targets, improving the accuracy of target tracking and target recognition capabilities.

[0066] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A omnidirectional low false alarm rate real-time detection method based on active and passive combination, characterized in that The specific steps are as follows: Acquire infrared images of the target area through real-time detection devices; Performing differential filtering calculation on the infrared image to obtain a differential image; Set the threshold, perform binary target segmentation on each pixel in the image, and obtain a binary image; The binary image is subjected to target labeling fusion by using a run length coding method; Use sequence image target association technology to predict target position and maintain trajectory; The moving direction and speed of the threat target during flight are stable, while the moving trajectory of the background clutter false alarm is random. Based on this feature, false alarms are eliminated to obtain candidate threat targets. The threat target is judged by the difference characteristics; the threat target generates infrared characteristics when it emits. According to the temporal and spatial distribution characteristics of the infrared characteristics in the imaging of the real-time detection device, the difference characteristics between the threat target and the non-threat target are judged, and then the threat target is confirmed.

2. According to claim 1, a comprehensive low false alarm rate real-time detection method based on active and passive combination is characterized in that: The real-time detection device adopts an ultra-high frame rate of 1000HZ and uses the inter-frame difference method when performing differential filtering calculations on infrared images. The pixel points corresponding to different frames are subtracted to determine the absolute value of the grayscale difference. When the absolute value exceeds the set threshold, it is determined to be a moving target, thereby realizing the detection function of moving targets.

3. The method of claim 1, wherein the method is characterized in that: The marking fusion is to continuously search around the detected suspected pixel points, and if there are other suspected points, they are continuously marked and connected until all the pixel points are searched.

4. According to claim 1, a comprehensive low false alarm rate real-time detection method based on active and passive combination is characterized in that: After the candidate threat target is detected, a feature definition method of two-color judgment or ignition detection is used to further detect the threat target and suppress false alarms.

5. According to claim 1, a comprehensive low false alarm rate real-time detection method based on active and passive combination is characterized in that: In the process of judging the threat target, the clutter detected by the threat target is the sunlight reflection of the ground object. Based on the different spectral characteristics between the clutter and the threat target, the dual-band design is used to eliminate the false alarm.

6. An all-round low false alarm rate real-time detection system based on active and passive combination, used to implement the all-round low false alarm rate real-time detection method based on active and passive combination according to any one of claims 1 to 5; characterized in that: It includes a plurality of real-time detection devices and information processing devices arranged along the circumference, and the data sent by each real-time detection device is processed by the information processing device to intercept the threatening target.

7. The all-round low false alarm rate real-time detection system based on active and passive combination according to claim 6 is characterized by: There are four real-time detection devices, each of which has a field of view greater than 95° and is installed around the carrier aircraft to achieve 360° all-round monitoring and confirmation of incoming threat targets.

8. The all-round low false alarm rate real-time detection system based on active and passive combination according to claim 7, characterized in that: The real-time detection device comprises an infrared image acquisition module, and the infrared image acquisition module comprises a medium-wave infrared optical lens, a medium-wave infrared detector, a filter wheel, a short-wave infrared optical lens, and a short-wave infrared detector; The medium-wave infrared optical lens adopts f-θ equidistant projection imaging mode, and the optical system adopts a secondary imaging optical path configuration, which is used to receive infrared radiation energy of the target and background in the field of view and converge it onto the medium-wave infrared detector for imaging; The medium-wave infrared detector adopts a medium-wave monochromatic infrared detector with a wavelength of 3.7um to 4.8um and a surface array of 640×512 to provide sufficient angular resolution; The filter wheel uses a motor to drive the filter wheel mechanism, and controls the filter wheel to run at a certain speed, and cooperates with the medium-wave infrared detector to perform dual-color imaging; The short-wave infrared optical lens adopts f-θ equidistant projection imaging mode, and the optical system adopts secondary imaging optical path configuration, which is used to receive infrared radiation energy of the target and background in the field of view and converge it onto the short-wave infrared detector for imaging. The filter transmission bands in the two short-wave lenses are 0.9um~1.1um and 1.5um~1.7um respectively; The short-wave infrared detector adopts a short-wave monochromatic infrared detector with a waveband of 0.9um to 1.7um, an array of 640×512, an actual effective array of 256×204, and a frame rate of 1000 Hz.

9. The all-round low false alarm rate real-time detection system based on active and passive combination according to claim 8, characterized in that: The real-time detection device also includes an antenna array, a radar sensor, a frequency synthesis transceiver component, and a collection preprocessing component; The antenna array adopts a Ku-band active phased array antenna, has a two-dimensional electronic scanning capability, can parse the input control commands and synchronize the timing to control the array, and form the radar beam required for work; The radar sensor is used to obtain high-precision target distance and closing speed information. The frequency synthesis transceiver component provides a reference frequency signal for the radar sensor, transmits an excitation waveform signal, receives a target echo signal, and performs frequency conversion for subsequent signal acquisition and processing; the frequency synthesis transceiver component has the functions of excitation waveform signal transmission, frequency conversion, gain control, filtering, and self-detection; The acquisition preprocessing component can perform echo acquisition and signal processing, acquire the reference clock signal sent by the frequency synthesis transceiver component, and then perform pulse compression, PD processing, space-time processing, and target detection signal processing on the acquired data.

10. The all-round low false alarm rate real-time detection system based on active and passive combination according to claim 6, characterized in that: The real-time detection device is interconnected with the information processing device via a data transmission bus.

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