A radar tracking and positioning method, device and medium combined with micro-Doppler harmonics

Abstract

The present invention discloses a radar tracking and positioning method, device, and medium in combination with micro-Doppler harmonics, relating to the field of radar signal processing. The method obtains the state information of the tracked target at the previous moment, and determines the main peak distance unit prediction range and the main peak Doppler frequency prediction range of the tracked target at the current moment based on the state information and the state transition equation; determines multiple micro-Doppler harmonic secondary peaks of the tracked target based on the main peak distance unit prediction range, the main peak Doppler frequency prediction range, and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak; determines the observation information of the main peak of the tracked target at the current moment based on the multiple micro-Doppler harmonic secondary peaks; and determines the position of the tracked target at the current moment based on the observation information of the main peak. This method can locate the position of the target at the current moment when the target tracked at the previous moment cannot be detected at the current moment, thereby ensuring the continuity of the track.

Description

Technical Field

[0001] The present invention relates to the field of radar signal processing, and in particular to a radar tracking and positioning method, device and medium combined with micro-Doppler harmonics. Background Art

[0002] Currently, radar is a common target detection method that uses electromagnetic waves reflected from targets to obtain information such as their position, speed, and type. In radar signal processing, Moving Target Indication (MTI) is often used to distinguish moving from stationary targets and eliminate multipath interference from trees, buildings, and other sources. MTI can filter out clutter and eliminate interference from stationary and slow-moving targets.

[0003] However, when radar is tracking a flying target, if the target's radial velocity component is low or the target is in a hovering state, making the Doppler frequency of the target echo close to or equal to 0, the MTI processing will severely weaken or completely eliminate the target echo, resulting in the inability to directly detect the tracked target at the current moment, and thus causing the tracking track to be interrupted.

[0004] Therefore, there is an urgent need for a method that can locate and track a target when the target cannot be directly detected by the radar. Summary of the Invention

[0005] Therefore, it is necessary to provide a radar tracking and positioning method, device and medium combining micro-Doppler harmonics to address the above technical problems. This method can locate the tracking target when the tracking target cannot be directly detected by the radar, ensuring the continuity of the track.

[0006] The present invention adopts the following technical solutions:

[0007] The present invention provides a radar tracking and positioning method combined with micro-Doppler harmonics, comprising:

[0008] When the tracked target is not detected at the current moment, the state information of the tracked target at the previous moment is obtained, and the main peak range unit prediction range and the main peak Doppler frequency prediction range of the tracked target at the current moment are determined according to the state information and the state transition equation;

[0009] Determine multiple micro-Doppler harmonic secondary peaks of the tracked target based on the main peak distance unit prediction range, the main peak Doppler frequency prediction range, and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak;

[0010] Determine the observation information of the main peak of the tracking target at the current moment based on multiple micro-Doppler harmonic secondary peaks;

[0011] According to the observation information of the main peak, the position of the tracking target at the current moment is determined.

[0012] Preferably, determining the main peak range unit prediction range and the main peak Doppler frequency prediction range of the tracking target at the current moment based on the state information and the state transition equation includes:

[0013] According to the state information and state transition equation, the predicted state information of the tracking target at the current moment is determined;

[0014] Determine the main peak range unit prediction value and the main peak Doppler frequency prediction value of the tracking target at the current moment based on the predicted state information, signal sampling rate, light speed and signal carrier wavelength;

[0015] According to the main peak range unit prediction value and the main peak Doppler frequency prediction value, the main peak range unit prediction range and the main peak Doppler frequency prediction range of the tracking target at the current moment are determined.

[0016] Preferably, determining multiple micro-Doppler harmonic secondary peaks of the tracked target according to the main peak distance unit prediction range, the main peak Doppler frequency prediction range, and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak includes:

[0017] The Doppler frequency range of the micro-Doppler harmonic secondary peak of the tracked target is obtained based on the predicted range of the main peak Doppler frequency and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak; the range unit range of the micro-Doppler harmonic secondary peak of the tracked target is the same as the predicted range of the main peak range unit;

[0018] Performing constant false alarm detection on a two-dimensional range-Doppler image within a range unit range of the micro-Doppler harmonic secondary peak to obtain a third detection target;

[0019] selecting a fourth detection target within a Doppler frequency range of a micro-Doppler harmonic secondary peak from the third detection target;

[0020] Obtaining the angle of the fourth detected target and calculating the angle difference between the angle of the fourth detected target and the angle of the tracked target at the previous moment;

[0021] The fourth detected targets whose angle difference is less than or equal to the preset angle offset threshold are determined as multiple micro-Doppler harmonic secondary peaks of the tracking target.

[0022] Preferably, the observation information includes a range unit, a Doppler frequency, an angle, and an amplitude; and determining the observation information of the main peak of the tracking target at the current moment based on multiple micro-Doppler harmonic secondary peaks includes:

[0023] The average value of the range units of multiple micro-Doppler harmonic secondary peaks is determined as the range unit of the main peak of the tracking target at the current moment;

[0024] Determine the Doppler frequency of the main peak of the tracking target at the current moment according to the Doppler frequencies of multiple micro-Doppler harmonic secondary peaks and the offset of each micro-Doppler harmonic secondary peak relative to the main peak in the Doppler dimension;

[0025] Calculating the weight of each micro-Doppler harmonic secondary peak according to the amplitudes of the multiple micro-Doppler harmonic secondary peaks;

[0026] According to the weights, the angles of multiple micro-Doppler harmonic secondary peaks are weighted averaged to obtain the angle of the main peak of the tracking target at the current moment.

[0027] Preferably, the observation information includes a range unit, a Doppler frequency, an angle, and an amplitude; and determining the position of the tracking target at the current moment based on the observation information of the main peak includes:

[0028] In the case where the positioning radar is a monostatic radar, the position of the tracked target at the current moment is determined based on the signal sampling rate, the speed of light, and the range unit of the tracked target at the current moment;

[0029] When the positioning radar is a bistatic radar, the position of the tracked target at the current moment is determined based on the distance and angle from the radar receiver to the radar transmitter, the range unit of the tracked target at the current moment, the angle of the tracked target at the current moment, the speed of light and the signal sampling rate.

[0030] Preferably, the method further comprises:

[0031] Determine multiple suspected targets from radar raw data;

[0032] If there is an associated detected suspected target associated with the motion state of the tracked target at the previous moment among the multiple detected suspected targets, then the associated detected suspected target is determined to be the target at the current moment;

[0033] If there is no associated detected suspected target, it is determined that the tracked target has not been detected at the current moment.

[0034] Preferably, if there is an associated detected suspected target associated with the motion state of the tracked target at the previous moment among the multiple detected suspected targets, determining the associated detected suspected target as the target at the current moment includes:

[0035] Traverse and detect suspected targets, and determine the first detected target within the main peak range unit prediction range and the main peak Doppler frequency prediction range;

[0036] Obtaining the angle of the first detected target and calculating the angle difference between the angle of the first detected target and the angle of the tracked target at the previous moment;

[0037] Determine a first detection target whose angle difference is less than or equal to a preset angle offset threshold as a second detection target;

[0038] The second detected target closest to the center of the main peak distance unit prediction range and the main peak Doppler frequency prediction range is determined as the target at the current moment.

[0039] Preferably, the method further comprises:

[0040] Use the target that is not associated with any track at the current moment as the starting point of the new track.

[0041] The present invention provides a radar tracking and positioning device combined with micro-Doppler harmonics, comprising:

[0042] an acquisition module, configured to acquire the state information of the tracked target at the previous moment when the tracked target is not detected at the current moment, and determine the main peak range unit prediction range and the main peak Doppler frequency prediction range of the tracked target at the current moment based on the state information and the state transition equation;

[0043] a first determination module, configured to determine a plurality of micro-Doppler harmonic secondary peaks of the tracked target based on a main peak distance unit prediction range, a main peak Doppler frequency prediction range, and an offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak;

[0044] The second determination module is used to determine the observation information of the main peak of the tracking target at the current moment based on the multiple micro-Doppler harmonic secondary peaks;

[0045] The third determination module is used to determine the position of the tracking target at the current moment based on the observation information of the main peak.

[0046] The present invention provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the computer program implements the above-mentioned radar tracking and positioning method combined with micro-Doppler harmonics.

[0047] The present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the above-mentioned radar tracking and positioning method combined with micro-Doppler harmonics is implemented.

[0048] At least one of the above technical solutions adopted by the present invention can achieve the following beneficial effects:

[0049] A radar tracking and positioning method that combines micro-Doppler harmonics is used. When the tracked target cannot be detected at the current moment, the observation information of the tracked target's micro-Doppler harmonic secondary peak is used to determine the tracked target's observation information, complete the track association and positioning of the tracked target, and ultimately ensure the continuity of the track. In the specific detection and tracking process, when the tracked target cannot be detected at the current moment, the main peak range unit prediction range and the main peak Doppler frequency prediction range of the tracked target at the current moment are obtained; based on the main peak range unit prediction range, the main peak Doppler frequency prediction range, and the offset of the micro-Doppler harmonic secondary peak relative to the main peak of the tracked target at the current moment, multiple micro-Doppler harmonic secondary peaks are determined from multiple detected targets; based on the multiple micro-Doppler harmonic secondary peaks, the observation information of the main peak of the tracked target at the current moment is determined; and based on the observation information of the main peak, the position of the tracked target at the current moment is determined, ultimately ensuring the continuity of the track. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0051] Figure 1 A schematic flow chart of a radar tracking and positioning method combined with micro-Doppler harmonics provided by the present invention;

[0052] Figure 2 The target track diagrams tracked by the present invention and conventional methods;

[0053] Figure 3 Schematic diagram of the micro-Doppler harmonic side peak in the two-dimensional range-Doppler diagram;

[0054] Figure 4 A flow chart of a radar tracking and positioning method combined with micro-Doppler harmonics provided by the present invention;

[0055] Figure 5 A schematic diagram of a radar tracking and positioning device combined with micro-Doppler harmonics provided by the present invention;

[0056] Figure 6 A schematic diagram of a computer device for a radar tracking and positioning method combining micro-Doppler harmonics provided by the present invention. DETAILED DESCRIPTION

[0057] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0058] The technical solutions provided by various embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0059] Figure 1 The following is a flow chart of a radar tracking and positioning method combined with micro-Doppler harmonics in the present invention, which specifically includes the following steps:

[0060] S101: When the tracked target is not detected at the current moment, the state information of the tracked target at the previous moment is obtained, and the main peak range unit prediction range and the main peak Doppler frequency prediction range of the tracked target at the current moment are determined based on the state information and the state transition equation.

[0061] It should be noted that the main peak of the tracked target is the correlation peak formed by the main part of the tracked target on the range-Doppler diagram, and the micro-Doppler harmonic secondary peak of the tracked target is the correlation peak formed by the component of the tracked target that causes the micro-Doppler harmonic on the range-Doppler diagram.

[0062] In an exemplary embodiment, multiple detected suspected targets are determined from radar raw data; a detected suspected target associated with the motion state of the tracked target at the previous moment is determined as the target at the current moment; the motion state of the tracked target at the previous moment includes distance, speed and angle; if there is no detected suspected target associated with the motion state of the tracked target at the previous moment, it is determined that the tracked target has not been detected at the current moment.

[0063] In an exemplary embodiment, multiple detected suspected targets are determined from radar raw data, including: acquiring radar raw data; the radar raw data includes a reference signal and an echo signal; performing adaptive cancellation on the echo signal to obtain a cancelled echo signal; performing signal accumulation using the cancelled echo signal and the reference signal to obtain a signal accumulation result; performing digital beamforming on the signal accumulation result to obtain a two-dimensional range-Doppler map; the two-dimensional range-Doppler map includes range units, Doppler frequency, and amplitude information of the detected target; cropping the two-dimensional range-Doppler map according to observation requirements to obtain a cropped two-dimensional range-Doppler map; performing constant false alarm detection on the cropped two-dimensional range-Doppler map, performing target aggregation on the detected targets, and obtaining multiple detected suspected targets at the current moment.

[0064] Specifically, the positioning radar used to detect the target is a bistatic radar, which acquires radar raw data, including a reference signal from one channel and echo signals from seven channels. The collected echo signals are adaptively canceled to eliminate direct waves and multipath clutter interference. The calculation method of the mutual ambiguity function is shown in formula (1):

[0065]

[0066] Where d(t) is the reference signal, e(t) is the echo signal after cancellation, τ is the delay, and f d is the Doppler frequency, T is the integration time, and * indicates conjugation.

[0067] Digital beamforming is performed on the cross-ambiguity function results of the seven channels to generate a two-dimensional range-Doppler map for the corresponding beam. The formed beam is then directed toward the desired detection direction to improve the signal-to-noise ratio of the detected target in that direction. The two-dimensional range-Doppler map is cropped to reduce computational overhead. Constant false alarm detection (CFAR) is then performed on the cropped two-dimensional range-Doppler map, and target aggregation is performed on the detected targets to generate multiple detected suspected targets.

[0068] In this embodiment, positioning information data of multiple detection targets are acquired, and the positioning information data of the multiple detection targets are all integrated into a two-dimensional range-Doppler map.

[0069] In an exemplary embodiment, the main peak distance unit prediction range and the main peak Doppler frequency prediction range of the tracked target at the current moment are determined based on the state information and the state transition equation, including: determining the predicted state information of the tracked target at the current moment based on the state information and the state transition equation; determining the main peak distance unit prediction value and the main peak Doppler frequency prediction value of the tracked target at the current moment based on the predicted state information, the signal sampling rate, the speed of light and the signal carrier wavelength; determining the main peak distance unit prediction range and the main peak Doppler frequency prediction range of the tracked target at the current moment based on the main peak distance unit prediction value and the main peak Doppler frequency prediction value.

[0070] Specifically, first, the predicted state information of the tracking target at the current moment is determined according to the state information of the tracking target and the state transition equation.

[0071] The state transition equation is shown in formula (2):

[0072]

[0073] The state information includes the state vector x(t) = [s(t), v(t)] of the tracking target. T , s(t) is the radial distance of the tracking target at time t, and v(t) is the radial velocity of the tracking target at time t.

[0074] The state transfer equation assumes that the tracked target follows a uniform motion in the radial direction and ignores the influence of noise.

[0075] Secondly, the main peak range unit prediction value and the main peak Doppler frequency prediction value of the tracking target at the current moment are determined based on the predicted state information, signal sampling rate, light speed and signal carrier wavelength.

[0076] The calculation method of the main peak range unit prediction value and the main peak Doppler frequency prediction value of the tracked target at the current moment is shown in formula (3):

[0077]

[0078] Where y(t)=[r0(t),f d0 (t)] T , c is the speed of light, λ is the signal carrier wavelength, r0 is the predicted value of the main peak distance unit, f d0 is the predicted value of the main peak Doppler frequency.

[0079] Finally, the main peak range unit prediction range and the main peak Doppler frequency prediction range of the tracking target at the current moment are determined according to the main peak range unit prediction value and the main peak Doppler frequency prediction value of the tracking target at the current moment.

[0080] Specifically, the target has been tracked for 3 seconds, and at the 4th second, the main peak range unit prediction value r0=91 of the target is calculated, and the main peak Doppler frequency prediction value f of the target is calculated. d0 =4Hz. The range unit is set with a fluctuation range of 1 to predict the main peak range unit of the tracking target at the current moment to [90,92]. The Doppler frequency is set with a fluctuation range of 5 to predict the main peak Doppler frequency of the tracking target at the current moment to [-1,9].

[0081] Specifically, the detected suspected target associated with the motion state of the tracked target at the previous moment is determined as the target at the current moment, including: traversing the detected suspected targets, determining the first detected target within the main peak distance unit prediction range and the main peak Doppler frequency prediction range; obtaining the angle of the first detected target, and calculating the angle difference between the angle of the first detected target and the angle of the tracked target at the previous moment; determining the first detected target whose angle difference is less than or equal to the preset angle offset threshold as the second detected target; and determining the second detected target closest to the center of the main peak distance unit prediction range and the main peak Doppler frequency prediction range as the target at the current moment.

[0082] Specifically, the range gate of the tracking target at the current moment is the main peak range unit range of the tracking target at the current moment, and the Doppler dimension gate of the tracking target at the current moment is the main peak Doppler frequency range of the tracking target at the current moment; obtain the angle of the first detected target and calculate the angle difference θ between the angle of the first detected target and the angle of the tracking target at the previous moment; set the angle difference threshold between the angle of the first detected target and the angle of the tracking target at the previous moment as θ max ; Set θ to be less than or equal to θ max All first detection targets are determined as second detection targets; and the second detection target closest to the center of the main peak distance unit prediction range and the main peak Doppler frequency prediction range of the tracking target at the current moment is determined as the target at the current moment.

[0083] If there is no second detected target, it is determined that there is no suspected target that can be associated with the motion state of the tracked target at the last moment.

[0084] S102: Determine multiple micro-Doppler harmonic secondary peaks of the tracked target according to the main peak distance unit prediction range, the main peak Doppler frequency prediction range, and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak.

[0085] In an exemplary embodiment, multiple micro-Doppler harmonic secondary peaks are determined from multiple detection targets based on a main peak range unit prediction range, a main peak Doppler frequency prediction range, and an offset of the micro-Doppler harmonic secondary peak relative to the main peak, including: obtaining a Doppler frequency range of the micro-Doppler harmonic secondary peak based on the main peak Doppler frequency prediction range and the offset of the micro-Doppler harmonic secondary peak relative to the main peak; the range unit range of the micro-Doppler harmonic secondary peak is the same as the range unit range of the main peak; performing constant false alarm detection on a two-dimensional range-Doppler map within the range unit range of the micro-Doppler harmonic secondary peak to obtain a third detection target; screening out a fourth detection target within the Doppler frequency range of the micro-Doppler harmonic secondary peak from the third detection target; obtaining an angle of the fourth detection target, and calculating an angle difference between the angle of the fourth detection target and the angle of the target tracked at the previous moment; and determining a fourth detection target whose angle difference is less than or equal to a preset angle offset threshold as a micro-Doppler harmonic secondary peak.

[0086] Specifically, the Doppler range U of the micro-Doppler secondary peak is calculated based on the predicted range of the main peak Doppler frequency of the tracking target at the current moment and the offset of the micro-Doppler harmonic secondary peak relative to the main peak in the Doppler dimension. f The prediction range of the main peak distance unit of the tracking target at the current moment is U r , take out the r The two-dimensional range-Doppler map within the range is subjected to constant false alarm detection to obtain the third detection target; the third detection target is selected from the third detection target to meet the requirements of f d ∈Uf The detection target is taken as the fourth detection target; the angle of the fourth detection target is obtained and the angle difference θ between the angle of the fourth detection target and the angle of the tracking target at the previous moment is calculated, and the angle difference threshold between the fourth detection target and the tracking target is set to θ max . Set θ to be less than or equal to θ max All fourth detected targets are identified as micro-Doppler secondary peaks.

[0087] S103: Determine observation information of the main peak of the tracking target at the current moment based on the multiple micro-Doppler harmonic secondary peaks.

[0088] The observation information includes range unit, Doppler frequency, angle and amplitude.

[0089] In an exemplary embodiment, an average value of the range units of multiple micro-Doppler harmonic secondary peaks is determined as the range unit of the main peak of the tracking target at the current moment; the Doppler frequency of the main peak of the tracking target at the current moment is determined based on the Doppler frequencies of the multiple micro-Doppler harmonic secondary peaks and the offset of each micro-Doppler harmonic secondary peak relative to the main peak in the Doppler dimension; the weight of each micro-Doppler harmonic secondary peak is calculated based on the amplitudes of the multiple micro-Doppler harmonic secondary peaks; and the angles of the multiple micro-Doppler harmonic secondary peaks are weighted averaged based on the weights to obtain the angle of the main peak of the tracking target at the current moment.

[0090] Specifically, the average value of the distance units of multiple micro-Doppler harmonic secondary peaks is determined as the distance unit of the main peak of the tracking target at the current moment. The calculation method of the distance unit of the main peak of the tracking target at the current moment is shown in formula (4):

[0091]

[0092] Among them, r is the range unit of the tracking target at the current moment, N is the total number of micro-Doppler secondary peaks, r i is the distance unit of the i-th secondary peak.

[0093] Based on the Doppler frequencies of multiple micro-Doppler harmonic secondary peaks and the offset of each micro-Doppler harmonic secondary peak relative to the main peak in the Doppler dimension, the Doppler frequency of the main peak of the tracking target at the current moment is determined. The Doppler frequency of the main peak of the tracking target at the current moment is calculated as shown in formula (5):

[0094]

[0095] Among them, f d is the Doppler frequency of the tracking target at the current moment, f i is the theoretical value of the offset of the ith secondary peak relative to the main peak in the Doppler dimension, f i ′ is the actual Doppler frequency of the secondary peak.

[0096] The weight of each micro-Doppler harmonic secondary peak is calculated according to the amplitudes of the multiple micro-Doppler harmonic secondary peaks.

[0097] The weight of the micro-Doppler harmonic secondary peak is calculated as shown in formula (6):

[0098]

[0099] Among them, ω i is the weight of the i-th micro-Doppler harmonic secondary peak, N is the number of micro-Doppler secondary peaks, A i is the amplitude of the ith secondary peak.

[0100] According to the weights, the angles of multiple micro-Doppler harmonic secondary peaks are weighted averaged to obtain the angle of the main peak of the tracking target at the current moment.

[0101] S104: Determine the current position of the tracking target based on the observation information of the main peak.

[0102] In an exemplary embodiment, the position of the target tracked at the previous moment at the current moment is determined based on the observation information of the main peak, including: when the positioning radar is a monostatic radar, the position of the tracked target at the current moment is determined based on the signal sampling rate, the speed of light, and the distance unit of the tracked target at the current moment; when the positioning radar is a bistatic radar, the position of the tracked target at the current moment is determined based on the distance and angle from the radar receiver to the radar transmitter, the distance unit of the tracked target at the current moment, the angle of the tracked target at the current moment, the speed of light, and the signal sampling rate.

[0103] Specifically, for a single-base radar, the position of the tracked target at the current moment is calculated as shown in formula (7):

[0104]

[0105] Among them, R is the distance between the target and the radar at the current moment, c is the speed of light, τ is the time delay, and the data sampling rate is f s When τ = r / f s .

[0106] Specifically, for a bistatic radar, the position of the tracked target at the current moment is calculated as shown in formula (8):

[0107]

[0108] Among them, R R is the distance from the current tracking target to the radar, L is the distance from the receiving station to the transmitting station, θ R =θ T -θn -θ, θ T is the angle from the receiving station to the transmitting station relative to true north, θ n is the angle of the antenna normal relative to true north.

[0109] In an exemplary embodiment, a target that is not associated with any track at the current moment is used as the starting point of the new track.

[0110] Specifically, during the actual tracking process, different tracking targets will form multiple tracks. The target that cannot be associated with all target tracks at the current moment is used as the starting point of the new track. According to the conventional detection method and the detection method provided in the present invention, the detection targets at subsequent moments are used to try to associate them until a stable track is formed.

[0111] In a specific embodiment, the radar system is a bistatic external radiation source radar, and the selected radiation source is a digital television signal with a carrier frequency of 554 MHz and a signal sampling rate of 10 MHz.

[0112] Step 1: Collect radar raw data, including a reference signal from one channel and echo signals from seven channels. Adaptive cancellation is performed on the collected echo signals to eliminate direct waves and multipath interference. The cross-ambiguity function is calculated using formula (1) using the canceled echo signals and the reference signal. Digital beamforming is performed on the cross-ambiguity function results of the seven channels, directing the beam to the direction to be detected, improving the signal-to-noise ratio of the target in the corresponding direction, and forming a two-dimensional range-Doppler map of the corresponding beam.

[0113] Step 2: Perform cropping and constant false alarm detection on the two-dimensional range-Doppler map calculated in step 1, and perform target aggregation on the detected targets to obtain multiple detected suspected targets.

[0114] Step 3: Associate the detected target with the existing track. Predict the current state of the target through the state transition equation. In this embodiment, let the target state vector x(t) = [s(t), v(t)] T , s(t) is the target radial distance, v(t) is the target radial velocity, assuming that the target body tracked at the previous moment follows a uniform motion in the radial direction and ignores the influence of noise, its state transfer equation is formula (2).

[0115] Furthermore, the main peak distance unit prediction value and the main peak Doppler frequency prediction value can be obtained by formula (3).

[0116] In this embodiment, the target entity tracked at the last moment has been tracked continuously for 3 seconds. The predicted value r0=91 is calculated at the 4th second. d0=4Hz. Set the gate range of the distance dimension to [90,92] and the gate range of the Doppler dimension to [-1,9]. Traverse all detection points in the relevant gate at the current moment, estimate the angle of the detection points, and set the maximum allowable angle offset range θ max =5°, discard the points whose angles differ too much from the previous moment, and there are no remaining points, so the track cannot be successfully associated in this step.

[0117] Step 4: For the target detected in the first frame, or the detection point that is not associated with any existing track, use it as the starting point of the new track, establish the initial correlation gate according to the above method, and try to associate it with the detection points at subsequent times until a stable track is formed.

[0118] Step 5: In this embodiment, it is known that the micro-Doppler harmonic secondary peaks of the tracked target are near ±108 Hz, ±144 Hz, and ±193 Hz on both sides of the main correlation peak. Since the point trace was not successfully associated in step 3, an attempt is made to search for the target micro-Doppler harmonics. In the two-dimensional range-Doppler map calculated in step 1, the data with distance units between 90 and 92 are extracted and constant false alarm detection is performed. Among the detected points, points with Doppler frequencies in the range of -108-1Hz to -108+9Hz, 108-1Hz to 108+9Hz, -144-1Hz to -144+9Hz, 144-1Hz to 144+9Hz, -193-1Hz to -193+9Hz, and 193-1Hz to 193+9Hz are selected, and angle measurement is performed on these points. The target angle at the previous moment is -33.15°. The angle of the detection point is compared with the target angle at the previous moment. Points with angle deviations exceeding 5 degrees are discarded. The remaining points are micro-Doppler harmonic secondary peaks. The micro-Doppler harmonic secondary peak information is shown in Table 1.

[0119] Table 1

[0120] Distance unit Doppler frequency (Hz) Amplitude Angle (°) 92 -193 <![CDATA[1.53×10 10 ]]> -32.37 92 -107 <![CDATA[5.67×10 9 ]]> -33.15 92 108 <![CDATA[1.07×10 10 ]]> -32.00 92 144 <![CDATA[8.59×10 9 ]]> -31.65

[0121] From the information of the micro-Doppler secondary peak, we can know that the target is currently located in the range unit 92. The Doppler frequency of the tracked target is calculated as shown in formula (9):

[0122]

[0123] According to formula (6), the weights of the secondary peaks are ω1 = 0.38, ω2 = 0.1408, ω3 = 0.2658, and ω4 = 0.2134, and the angle of the target at the current moment is θ = -32.23°.

[0124] Step 6: The radar used in this embodiment is a bistatic radar, L = 12100m, θ n =-178.50°,θT =-154.62°, the actual distance R of the target relative to the radar can be calculated by formula (8) R =1721.9m.

[0125] Step 7: From all the obtained tracks, select the track of interest for target identification. This will determine whether the target corresponding to the track has micro-Doppler harmonics and the location of its micro-Doppler harmonics in the frequency dimension. Then, repeat the process from step 1 for the next frame of data.

[0126] According to the above steps, the selected track is continuously tracked and positioned for a total of 10 seconds, and the results shown in Table 2 can be obtained. According to the azimuth and distance of the target at each moment, the track is plotted in the coordinate system, as shown in Figure 2 As shown in the figure, from the 4th to the 6th second in this track, the target body has a low Doppler frequency, which is approximately tangential to the radar. When using conventional methods to track the target body alone, the target cannot be directly detected during this period, resulting in a continuous interruption of the track for 3 seconds. When using the tracking and positioning method incorporating micro-Doppler harmonics proposed in this invention, tracking and positioning of the target can be maintained even if the target has a low Doppler frequency, improving the stability of tracking of rotorcraft targets.

[0127] Table 2

[0128]

[0129] In a specific embodiment, when using radar to detect a target, if some parts of the target are in relative motion with the main body (such as the propeller of a multi-rotor drone rotating relative to the fuselage), a micro-Doppler frequency shift will be generated in the echo, and then a micro-Doppler harmonic secondary peak will be generated on the two-dimensional range-Doppler map. The secondary peak has the same range unit prediction range as the main peak and is distributed on both sides of the main peak, such as Figure 3 shown.

[0130] In a specific embodiment, the following Figure 4 The process shown in the figure is carried out. First, radar data is collected and preprocessed to obtain multiple detected targets. An attempt is made to associate the detected targets with existing tracks to determine whether the previously tracked target track failed to be associated. If so, the target's position is estimated using the micro-Doppler harmonics. If so, the target's position is estimated using the micro-Doppler harmonics' secondary peaks to ensure track continuity.

[0131] The server mentioned in the present invention can be a server set up on a business platform, or a device such as a desktop computer, a notebook computer, etc. that can execute the solution of the present invention. For the sake of convenience, the following description will only be made with the server as the execution subject.

[0132] When applying the radar tracking and positioning method combined with micro-Doppler harmonics provided by the present invention, it is not necessary to Figure 1 The steps are executed in the order shown. The specific execution order of the steps can be determined according to needs, and the present invention does not limit this.

[0133] The above is a radar tracking and positioning method combined with micro-Doppler harmonics provided by one or more embodiments of the present invention. Based on the same idea, the present invention also provides a corresponding radar tracking and positioning device combined with micro-Doppler harmonics, such as Figure 5 shown.

[0134] Figure 5 A schematic diagram of a radar tracking and positioning device combined with micro-Doppler harmonics provided by the present invention, comprising:

[0135] An acquisition module 501 is configured to acquire state information of the tracked target at a previous moment when the tracked target is not detected at the current moment, and determine a predicted range of a main peak range unit and a predicted range of a main peak Doppler frequency of the tracked target at the current moment based on the state information and a state transition equation;

[0136] A first determining module 502 is configured to determine a plurality of micro-Doppler harmonic secondary peaks of the tracked target based on a predicted range of a main peak distance unit, a predicted range of a main peak Doppler frequency, and an offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak;

[0137] The second determining module 503 is configured to determine the observation information of the main peak of the tracking target at the current moment based on the multiple micro-Doppler harmonic secondary peaks;

[0138] The third determining module 504 is configured to determine the current position of the tracking target based on the observation information of the main peak.

[0139] The specific limitations of a radar tracking and positioning device incorporating micro-Doppler harmonics can be found in the limitations of a radar tracking and positioning method incorporating micro-Doppler harmonics described above and will not be further elaborated here. Each module in the aforementioned radar tracking and positioning device incorporating micro-Doppler harmonics can be implemented in whole or in part via software, hardware, or a combination thereof. Each of these modules can be embedded in or independent of a processor in a computer device in hardware form, or stored in a computer device memory in software form, allowing the processor to call and execute the corresponding operations of each module.

[0140] The present invention also provides a computer-readable storage medium, which stores a computer program, which can be used to execute the above Figure 1 A radar tracking and positioning method combining micro-Doppler harmonics is provided.

[0141] The present invention also provides Figure 6 The structural diagram of the computer equipment shown in FIG. Figure 6 As shown in the figure, at the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory. Of course, it may also include other hardware required for the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to achieve the above Figure 1 A radar tracking and positioning method combining micro-Doppler harmonics is provided.

[0142] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0143] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of the present invention.

Claims

1. A radar tracking and positioning method combined with micro-Doppler harmonics, characterized in that: include: When the tracked target is not detected at the current moment, obtaining state information of the tracked target at the previous moment, and determining a main peak range unit prediction range and a main peak Doppler frequency prediction range of the tracked target at the current moment based on the state information and a state transition equation; determining a plurality of micro-Doppler harmonic secondary peaks of the tracked target according to the main peak distance unit prediction range, the main peak Doppler frequency prediction range, and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak; Determining observation information of a main peak of the tracking target at a current moment according to the multiple micro-Doppler harmonic secondary peaks; Determining the current position of the tracking target based on the observation information of the main peak; The method of determining multiple micro-Doppler harmonic secondary peaks of the tracked target based on the main peak distance unit prediction range, the main peak Doppler frequency prediction range, and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak includes: obtaining the Doppler frequency range of the micro-Doppler harmonic secondary peak of the tracked target based on the main peak Doppler frequency prediction range and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak; the distance unit range of the micro-Doppler harmonic secondary peak of the tracked target is the same as the main peak distance unit prediction range; performing constant false alarm detection on a two-dimensional range-Doppler map within the distance unit range of the micro-Doppler harmonic secondary peak to obtain a third detection target; screening out a fourth detection target within the Doppler frequency range of the micro-Doppler harmonic secondary peak from the third detection target; obtaining an angle of the fourth detection target, and calculating an angle difference between the angle of the fourth detection target and the angle of the tracked target at a previous moment; The fourth detection targets whose angle difference is less than or equal to the preset angle offset threshold are determined as the multiple micro-Doppler harmonic secondary peaks of the tracked target.

2. The method according to claim 1, characterized in that Determining the main peak range unit prediction range and the main peak Doppler frequency prediction range of the tracking target at the current moment based on the state information and the state transition equation includes: Determining predicted state information of the tracking target at the current moment according to the state information and the state transition equation; Determine a main peak range unit prediction value and a main peak Doppler frequency prediction value of the tracked target at a current moment according to the predicted state information, the signal sampling rate, the speed of light, and the signal carrier wavelength; The main peak range unit prediction range and the main peak Doppler frequency prediction range of the tracking target at the current moment are determined according to the main peak range unit prediction value and the main peak Doppler frequency prediction value.

3. The method according to claim 1, characterized in that The observation information includes a range unit, a Doppler frequency, an angle, and an amplitude; and determining the observation information of the main peak of the tracking target at the current moment based on the multiple micro-Doppler harmonic secondary peaks includes: Determine an average value of the distance units of the plurality of micro-Doppler harmonic secondary peaks as the distance unit of the main peak of the tracking target at the current moment; Determining the Doppler frequency of the main peak of the tracking target at the current moment according to the Doppler frequencies of the multiple micro-Doppler harmonic secondary peaks and the offset of each micro-Doppler harmonic secondary peak relative to the main peak in the Doppler dimension; Calculating a weight of each micro-Doppler harmonic secondary peak according to the amplitudes of the multiple micro-Doppler harmonic secondary peaks; According to the weights, a weighted average is performed on the angles of the multiple micro-Doppler harmonic secondary peaks to obtain the angle of the main peak of the tracking target at the current moment.

4. The method according to claim 1, wherein The observation information includes a range unit, a Doppler frequency, an angle, and an amplitude; and determining the position of the tracking target at the current moment based on the observation information of the main peak includes: In the case where the positioning radar is a monostatic radar, determining the position of the tracked target at the current moment according to the signal sampling rate, the speed of light, and the range unit of the tracked target at the current moment; When the positioning radar is a bistatic radar, the position of the tracked target at the current moment is determined based on the distance and angle from the radar receiving end to the radar transmitting end, the range unit of the tracked target at the current moment, the angle of the tracked target at the current moment, the speed of light, and the signal sampling rate.

5. The method according to claim 1, wherein The method further comprises: Determine multiple suspected targets from radar raw data; If there is an associated detected suspected target associated with the motion state of the tracked target at the previous moment among the multiple detected suspected targets, determining the associated detected suspected target as the target at the current moment; If the associated detected suspected target does not exist, it is determined that the tracked target has not been detected at the current moment.

6. The method according to claim 5, characterized in that If there is an associated detected suspected target associated with the motion state of the tracked target at the previous moment among the multiple detected suspected targets, determining the associated detected suspected target as the target at the current moment includes: Traversing the detected suspected targets, determining a first detected target within the main peak distance unit prediction range and the main peak Doppler frequency prediction range; Obtaining the angle of the first detected target, and calculating the angle difference between the angle of the first detected target and the angle of the tracked target at the previous moment; Determine a first detection target whose angle difference is less than or equal to a preset angle offset threshold as a second detection target; The second detected target closest to the center of the main peak distance unit prediction range and the main peak Doppler frequency prediction range is determined as the target at the current moment.

7. The method according to claim 1, characterized in that The method further comprises: Use the target that is not associated with any track at the current moment as the starting point of the new track.

8. A radar tracking and positioning device combined with micro-Doppler harmonics, characterized in that: include: an acquisition module, configured to, when a tracked target cannot be detected at a current moment, acquire state information of the tracked target at a previous moment, and determine a main peak range unit prediction range and a main peak Doppler frequency prediction range of the tracked target at the current moment based on the state information and a state transition equation; The first determination module is configured to determine multiple micro-Doppler harmonic secondary peaks of the tracked target based on the main peak distance unit prediction range, the main peak Doppler frequency prediction range, and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak; the determining multiple micro-Doppler harmonic secondary peaks of the tracked target based on the main peak distance unit prediction range, the main peak Doppler frequency prediction range, and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak includes: obtaining, based on the main peak Doppler frequency prediction range and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak, The Doppler frequency range of the micro-Doppler harmonic secondary peak to the tracked target is the same as the distance unit prediction range of the main peak; a constant false alarm detection is performed on the two-dimensional range-Doppler map within the distance unit range of the micro-Doppler harmonic secondary peak to obtain a third detection target; a fourth detection target within the Doppler frequency range of the micro-Doppler harmonic secondary peak is screened out from the third detection target; the angle of the fourth detection target is obtained, and the angle difference between the angle of the fourth detection target and the angle of the tracked target at the previous moment is calculated; the angle difference is used as the The fourth detected target having a value less than or equal to a preset angle offset threshold is determined as a plurality of micro-Doppler harmonic secondary peaks of the tracked target; the determining the plurality of micro-Doppler harmonic secondary peaks of the tracked target according to the main peak distance unit prediction range, the main peak Doppler frequency prediction range, and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak includes: obtaining the Doppler frequency range of the micro-Doppler harmonic secondary peak of the tracked target according to the main peak Doppler frequency prediction range and the offset of the micro-Doppler harmonic secondary peak of the tracked target relative to the main peak; the distance unit of the micro-Doppler harmonic secondary peak of the tracked target The distance unit range is the same as the main peak distance unit prediction range; a constant false alarm detection is performed on the two-dimensional range-Doppler map within the distance unit range of the micro-Doppler harmonic secondary peak to obtain a third detection target; a fourth detection target within the Doppler frequency range of the micro-Doppler harmonic secondary peak is screened out from the third detection target; an angle of the fourth detection target is obtained, and an angle difference between the angle of the fourth detection target and the angle of the tracking target at the previous moment is calculated; and a fourth detection target whose angle difference is less than or equal to a preset angle offset threshold is determined as a plurality of micro-Doppler harmonic secondary peaks of the tracking target; A second determining module is configured to determine observation information of a main peak of the tracking target body at a current moment based on the multiple micro-Doppler harmonic secondary peaks; The third determining module is used to determine the position of the tracking target at a current moment according to the observation information of the main peak.

9. A computer-readable storage medium, characterized in that The storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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