Radar tracking and positioning method and device combined with micro-Doppler harmonic waves and medium

Abstract

The invention discloses a radar tracking and positioning method and device combined with micro-Doppler harmonic waves and a medium, and relates to the field of radar signal processing. Acquiring state information of the tracking target at the previous moment, and determining a main peak distance unit prediction range and a main peak Doppler frequency prediction range of the tracking target at the current moment according to the state information and the state transition equation; according to the main peak distance unit prediction range, the main peak Doppler frequency prediction range and the offset of the micro-Doppler harmonic sub-peak of the tracking target relative to the main peak, determining a plurality of micro-Doppler harmonic sub-peaks of the tracking target; determining observation information of a main peak of the tracking target at the current moment according to the plurality of micro-Doppler harmonic secondary peaks; and determining the position of the tracking target at the current moment according to the observation information of the main peak. According to the method, when the target tracked at the previous moment cannot be detected at the current moment, the position of the target at the current moment can be positioned, and the continuity of the track is ensured.

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] At present, radar uses electromagnetic waves reflected by targets to obtain status information such as the position, speed and category of targets. It is a common means of target detection. In radar signal processing, in order to distinguish moving targets from fixed targets and eliminate multipath interference caused by trees, buildings, etc., it is usually necessary to use the Moving Target Indication (MTI) method. MTI can filter out clutter and eliminate interference from stationary targets and low-speed targets.

[0003] However, when the radar is tracking a flying target, if the radial velocity component of the target is low or in a hovering state, the Doppler frequency of the target echo is close to or equal to 0. At this time, 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, thereby causing the tracking track to be interrupted.

[0004] Therefore, there is an urgent need for a method for locating a tracking target when the tracking target cannot be directly detected by a radar. Summary of the invention

[0005] Based on this, it is necessary to provide a radar tracking and positioning method, device and medium combined with 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 to ensure 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 transfer equation;

[0009] 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;

[0010] According to multiple micro-Doppler harmonic secondary peaks, the observation information of the main peak of the tracking target at the current moment is determined;

[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 distance unit prediction range and the main peak Doppler frequency prediction range of the tracking target at the current moment according to the state information and the state transfer equation includes:

[0013] According to the state information and the state transfer 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 according to the prediction state information, signal sampling rate, light speed and signal carrier wavelength;

[0015] According to the main peak distance unit prediction value and the main peak Doppler frequency prediction value, the main peak distance 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] According to the Doppler frequency prediction range of the main peak 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 of the tracked target is obtained; the range unit range of the micro-Doppler harmonic secondary peak of the tracked target is the same as the main peak range unit prediction range;

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

[0019] Screening out a fourth detection target within the Doppler frequency range of the 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 detection 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 the observation information of the main peak of the tracking target at the current moment is determined according to the multiple micro-Doppler harmonic secondary peaks, including:

[0023] The average value of the distance units of the multiple micro-Doppler harmonic secondary peaks is determined as the distance 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] Calculate the weight of each micro-Doppler harmonic secondary peak according to the amplitudes of 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 according to the observation information of the main peak includes:

[0028] In the case where the positioning radar is a single-base radar, the position of the tracked target at the current moment is determined according to the signal sampling rate, the speed of light and the distance unit of the tracked target at the current moment;

[0029] When the positioning radar is a bistatic radar, the position of the tracking 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 tracking target at the current moment, the angle of the tracking 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 detection suspected target, it is determined that the tracking 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 distance 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 last 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 is used 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 distance unit prediction range and the main peak Doppler frequency prediction range of the tracked target at the current moment according to the state information and the state transfer equation;

[0043] A first determination module is used to 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;

[0044] The second determination module is used to determine the observation information of the main peak of the tracking target at the current moment according to 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 according to the observation information of the main peak.

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

[0047] The present invention provides a computer device, including 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] Through a radar tracking and positioning method combined with micro-Doppler harmonics, when the tracking target cannot be detected at the current moment, the observation information of the tracking target is determined by using the observation information of the micro-Doppler harmonic secondary peak of the tracking target, and the track association and positioning of the tracking target are completed, and the continuity of the tracking track is finally guaranteed. In the specific detection and tracking process, when the tracking target cannot be detected at the current moment, the main peak distance unit prediction range and the main peak Doppler frequency prediction range of the tracking target at the current moment are obtained; 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 relative to the main peak of the tracking target at the current moment, multiple micro-Doppler harmonic secondary peaks are determined from multiple detection targets; according to the multiple micro-Doppler harmonic secondary peaks, the observation information of the main peak of the tracking target at the current moment is determined; according to the observation information of the main peak, the position of the tracking target at the current moment is determined, and the continuity of the track is finally guaranteed. 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 track diagram of the detected target tracked by the present invention and the conventional method;

[0053] Figure 3 It is a 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] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. 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 making creative work 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 in conjunction with the accompanying drawings.

[0059] Figure 1 The present invention is a flow chart of a radar tracking and positioning method combined with micro-Doppler harmonics, 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 according to the state information and the state transfer 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 causing the micro-Doppler harmonic on the range-Doppler diagram.

[0062] In an exemplary embodiment, multiple detected suspected targets are determined from radar raw data; the detected suspected targets associated with the motion state of the tracked target at the previous moment are determined as the targets 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 suspected targets are detected 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, and performing target aggregation on the detected targets to obtain multiple suspected targets detected at the current moment.

[0064] Specifically, the positioning radar for detecting the target is a dual-base radar, which obtains radar raw data, including a reference signal of one channel and echo signals of seven channels. The collected echo signals are adaptively cancelled to eliminate the interference of direct waves and multipath clutter. The calculation method of the mutual ambiguity function is shown in formula (1):

[0065]

[0066] Among them, 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 taking the conjugate.

[0067] The mutual ambiguity function results of the seven channels are digitally beamformed to obtain the two-dimensional range-Doppler map of the corresponding beam. The formed beam is pointed to the direction to be detected to improve the signal-to-noise ratio of the detected target in the corresponding direction. The two-dimensional range-Doppler map is cropped to save the amount of calculation. The cropped two-dimensional range-Doppler map is subjected to constant false alarm detection, and the detected targets are subjected to target aggregation to obtain 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 according to the state information and the state transfer equation, including: determining the predicted state information of the tracked target at the current moment according to the state information and the state transfer 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 according to the predicted state information, signal sampling rate, speed of light and 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 according to the main peak distance unit prediction value and the main peak Doppler frequency prediction value.

[0070] Specifically, firstly, 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 transfer equation.

[0071] The state transfer 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 tracked target at time t, and v(t) is the radial velocity of the tracked 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, according to the predicted state information, signal sampling rate, light speed and signal carrier wavelength, the main peak range unit predicted value and the main peak Doppler frequency predicted value of the tracked target at the current moment are determined.

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

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

[0081] Specifically, 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, including: traversing the detected suspected targets to determine 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 a 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 gate of the tracking target at the current moment is the main peak Doppler frequency range of the tracking target at the current moment; the angle of the first detection target is obtained and the angle difference θ between the angle of the first detection target and the angle of the tracking target at the previous moment is calculated; the angle difference threshold between the angle of the first detection target and the angle of the tracking target at the previous moment is set 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 side peaks are determined from multiple detection targets according to the main peak distance unit prediction range, the main peak Doppler frequency prediction range and the offset of the micro-Doppler harmonic side peak relative to the main peak, including: obtaining the Doppler frequency range of the micro-Doppler harmonic side peak according to the main peak Doppler frequency prediction range and the offset of the micro-Doppler harmonic side peak relative to the main peak; the distance unit range of the micro-Doppler harmonic side peak is the same as the distance unit range of the main peak; performing constant false alarm detection on the two-dimensional range-Doppler map within the distance unit range of the micro-Doppler harmonic side peak to obtain a third detection target; screening out a fourth detection target within the Doppler frequency range of the micro-Doppler harmonic side peak from the third detection target; obtaining the angle of the fourth detection target, and calculating the angle difference between the angle of the fourth detection target and the angle of the target tracked at the previous moment; and determining the fourth detection target whose angle difference is less than or equal to a preset angle offset threshold as the micro-Doppler harmonic side 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 r The two-dimensional distance-Doppler map within the range is subjected to constant false alarm detection to obtain the third detection target; the third detection target is selected 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 a main peak of the tracking target at the current moment according to 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 distance units of multiple micro-Doppler harmonic side peaks is determined as the distance 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 according to the Doppler frequencies of the multiple micro-Doppler harmonic side peaks and the offset of each micro-Doppler harmonic side peak relative to the main peak in the Doppler dimension; the weight of each micro-Doppler harmonic side peak is calculated according to the amplitudes of the multiple micro-Doppler harmonic side peaks; and the angles of the multiple micro-Doppler harmonic side peaks are weighted averaged according to 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 distance unit of the tracking target at the current moment, N is the total number of micro-Doppler secondary peaks, and r i is the distance unit of the ith secondary peak.

[0093] 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, the Doppler frequency of the main peak of the tracking target at the current moment is determined. The calculation method of the Doppler frequency of the main peak of the tracking target at the current moment is 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 position of the tracking target at the current moment according to 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 single-base 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 dual-base 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 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 calculation method of the position of the tracked target at the current moment is shown in formula (7):

[0104]

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

[0106] Specifically, for a bistatic radar, the position of the tracking 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, in 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 dual-base external radiation source radar, the radiation source selected 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 of one channel and echo signals of seven channels. Perform adaptive cancellation processing on the collected echo signals to eliminate direct waves and multipath clutter interference. Use the canceled echo signal and the reference signal to calculate the mutual ambiguity function using formula (1). Perform digital beamforming on the mutual ambiguity function results of the seven channels, point the beam to the direction to be detected, improve the signal-to-noise ratio of the target in the corresponding direction, and form a two-dimensional range-Doppler map of the corresponding beam.

[0113] Step 2: The two-dimensional range-Doppler map calculated in step 1 is cropped and subjected to constant false alarm detection, and the detected targets are subjected to target aggregation to obtain multiple detected suspected targets.

[0114] Step 3: Associate the detected target with the existing track. Predict the state of the target at the current moment through the state transfer 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 the influence of noise is ignored, 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 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 the 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°, discarding the points whose angles differ too much from the previous moment. 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 ±108Hz, ±144Hz and ±193Hz on both sides of the main correlation peak. Since the point trace was not successfully associated in step three, an attempt is made to search for the target micro-Doppler harmonics. In the two-dimensional range-Doppler map calculated in step one, the data of the distance unit between 90 and 92 are taken out for constant false alarm detection. Among the detected points, the 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 the angles of these points are measured. 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, and the points with angle deviation 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 distance unit where the target is currently located is 92. The calculation method of the Doppler frequency of the tracked target is 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, 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: Among all the tracks obtained, select the track of focus for target identification, so as to know whether the target corresponding to the track has micro-Doppler harmonics and the position of its micro-Doppler harmonics in the frequency dimension. Then repeat the processing of the next frame of data from step 1.

[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 this track, the target body has a lower Doppler frequency from the 4th to the 6th second, which is approximately tangential motion relative to the radar. When only conventional methods are used to track the target body, the target cannot be directly detected during this period, resulting in a continuous interruption of the track for 3 seconds. When the tracking and positioning method combined with micro-Doppler harmonics proposed by the present invention is used, the target can be tracked and positioned even if the target has a lower Doppler frequency, thereby improving the stability of tracking rotor-type 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 rotates 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 as the main peak unit prediction range and is distributed on both sides of the main peak, such as Figure 3 shown.

[0130] In a specific embodiment, the following can be done: Figure 4 The process shown is processed. First, the radar is used to collect data, and the collected data is preprocessed to obtain multiple detection targets. Try to associate the detection target with the existing track to determine whether the target track tracked at the last moment has failed to be associated. If the association fails, confirm whether the detection target of the track has micro-Doppler harmonics. If so, use the micro-Doppler harmonics sub-peak to estimate the position of the target to ensure the continuity of the track.

[0131] The server mentioned in the present invention may be a server set 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 convenience of description, the following description is only based on 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 includes:

[0135] The acquisition module 501 is used 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 according to the state information and the state transfer equation;

[0136] A first determination module 502 is used to 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;

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

[0138] The third determination module 504 is used to determine the position of the tracking target at the current moment according to the observation information of the main peak.

[0139] For the specific definition of a radar tracking and positioning device combined with micro-Doppler harmonics, please refer to the definition of a radar tracking and positioning method combined with micro-Doppler harmonics in the above text, which will not be repeated here. Each module in the above-mentioned radar tracking and positioning device combined with micro-Doppler harmonics can be implemented in whole or in part by software, hardware and a combination thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[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 device 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, and 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 can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and 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 may be arbitrarily combined. 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 the state information of the tracked target at the previous moment, and determining the main peak distance unit prediction range and the main peak Doppler frequency prediction range of the tracked target at the current moment according to the state information and the state transfer equation; 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; Determining observation information of a main peak of the tracking target at a current moment according to the multiple micro-Doppler harmonic secondary peaks; The position of the tracking target at the current moment is determined according to the observation information of the main peak.

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

3. The method according to claim 1, characterized in that The determining of 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 comprises: 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 Doppler frequency range of the micro-Doppler harmonic secondary peak of the tracked target is obtained; the range unit range of the micro-Doppler harmonic secondary peak of the tracked target is the same as the main peak range unit prediction range; Performing constant false alarm detection on the two-dimensional range-Doppler image within the range unit of the micro-Doppler harmonic secondary peak to obtain a third detection target; Filtering out a fourth detection target within the Doppler frequency range of the micro-Doppler harmonic secondary peak from the third detection target; Acquire the angle of the fourth detection target, and calculate the angle difference between the angle of the fourth detection target and the angle of the tracking target at the 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 sub-peaks of the tracked target.

4. The method according to claim 1, characterized in that: The observation information includes a distance unit, a Doppler frequency, an angle, and an amplitude; and the step of determining the observation information of the main peak of the tracking target at the current moment according to 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; Determine 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 the weight of each micro-Doppler harmonic secondary peak according to the amplitudes of the multiple micro-Doppler harmonic secondary peaks; According to the weights, weighted averaging is performed on the angles of the plurality of micro-Doppler harmonic secondary peaks to obtain the angle of the main peak of the tracking target at the current moment.

5. The method according to claim 1, characterized in that: The observation information includes a distance unit, a Doppler frequency, an angle, and an amplitude; and determining the position of the tracking target at the current moment according to 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 distance unit of the tracked target at the current moment; When the positioning radar is a bistatic radar, the position of the tracking target at the current moment is determined according to the distance and angle from the radar receiving end to the radar transmitting end, the distance unit of the tracking target at the current moment, the angle of the tracking target at the current moment, the speed of light and the signal sampling rate.

6. The method according to claim 1, characterized in that 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.

7. The method according to claim 6, 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; Acquire the angle of the first detected target, and calculate 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 detection 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.

8. 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.

9. A radar tracking and positioning device combined with micro-Doppler harmonics, characterized in that: include: An acquisition module is used to acquire the state information of the tracked target at the previous moment when the tracked target cannot be detected at the current moment, and determine the main peak distance unit prediction range and the main peak Doppler frequency prediction range of the tracked target at the current moment according to the state information and the state transfer equation; A first determination module is used to determine 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; A second determination module is used to determine the observation information of the main peak of the tracking target body at the current moment according to the multiple micro-Doppler harmonic secondary peaks; The third determination module is used to determine the position of the tracking target at the current moment according to the observation information of the main peak.

10. 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 8 is implemented.

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