A precise ranging and velocity measurement method for hypersonic targets based on one-dimensional imaging detection

Abstract

This application provides a precise ranging and velocity measurement method for hypersonic targets based on one-dimensional imaging detection, comprising: step 10, one-dimensional range imaging of the hypersonic target; step 20, range measurement of the hypersonic target; step 30, coarse velocity estimation of the hypersonic target; and step 40, fine velocity measurement of the hypersonic target. This application provides high ranging accuracy and relatively high velocity measurement accuracy.

Description

Technical Field

[0001] This application relates to the field of forward-looking detection technology of radar imaging fuses, and in particular to a method for accurate ranging and velocity measurement of hypersonic targets based on one-dimensional imaging detection. Background Technology

[0002] Radar imaging fuses, through forward-looking detection and one-dimensional range imaging, can achieve precise measurement of hypersonic targets, acquiring information such as target range and velocity. High-resolution one-dimensional radar range images refer to acquiring target information using broadband radar signals. Their characteristic is that by emitting a high-frequency signal of a specific wavelength and performing a Fourier transform on the received echo signal, a high-resolution range image is obtained. This high-resolution radar range image effectively reflects the details and structural information of the target's radial range distribution along the radar's line of sight. The gradual variability of the scattering point position in the range image with the target's attitude can serve as a basis for target identification research. To achieve effective interception of hypersonic targets, the demand for accurate measurement of their spatial position and motion state information is increasing.

[0003] Traditional imaging ranging is affected by the uneven distribution of imaging points, resulting in large errors; traditional velocity estimation methods, such as the time-domain cross-correlation method and the minimum entropy method, have large computational loads and long processing times, and their accuracy is not high enough under general design parameters. Summary of the Invention

[0004] This application provides a precise ranging and velocity measurement method for hypersonic targets based on one-dimensional imaging detection, which can be used to solve the technical problem of large errors in traditional imaging ranging.

[0005] This application provides a method for accurate ranging and velocities of hypersonic targets based on one-dimensional imaging detection, the method comprising:

[0006] Step 10, one-dimensional range imaging of hypersonic targets:

[0007] Based on the target's three-dimensional geometric shape, the target is decomposed into a surface model. The visible surface echo vectors are superimposed to obtain the overall echo signal of the target. After sampling and processing the echo signal, an IFFT transformation is performed to obtain a one-dimensional imaging result.

[0008] Step 20, distance measurement of hypersonic targets:

[0009] Set a threshold value, average the distances of target imaging points with normalization amplitudes greater than the threshold value as a coarse distance estimate, and statistically calculate the mean of the coarse estimate within a specified intersection angle range. Compare the error with the actual distance, correct the coarse distance estimate, and obtain a fine distance measurement value.

[0010] Step 30, rough velocity estimation of the hypersonic target:

[0011] Based on the difference between two fine distance measurements at the measurement interval, a coarse estimate of the target's velocity is obtained.

[0012] Step 40, precise velocity measurement of the hypersonic target:

[0013] The similarity is compared using the image point distance method. The similarity between the distance image after velocity compensation within a certain velocity range and the static image result is compared, and the velocity value with the highest similarity is selected as the target's moving velocity.

[0014] Optional one-dimensional range imaging of hypersonic targets includes:

[0015] Step 11, Hypersonic Target Visible Element Identification: Based on the target's three-dimensional geometric model, obtain the vertex coordinates and external normal vectors of each triangular element of the target in the ground coordinate system, and then identify the visible surfaces.

[0016] Step 12, echo sampling matrix of hypersonic target:

[0017] Determine the radar cross section of the visible elements, and based on the transmitted signal, superimpose the echo vectors of the visible elements to obtain the overall echo signal of the target. Obtain the echo sampling matrix according to the sampling frequency.

[0018] Step 13, High-resolution one-dimensional imaging of hypersonic targets:

[0019] After processing the echo sampling matrix, an IFFT transform is performed, and the maximum value method is used to stitch together the data to remove redundancy and obtain accurate imaging results.

[0020] Optional range measurement of hypersonic targets includes:

[0021] Step 21, coarse distance estimation: Set a threshold value, record the distances of image points whose normalization amplitude is greater than the threshold value, and calculate the average value. The average value is the coarse distance estimate.

[0022] Step 22, fine distance measurement: Select an appropriate step size within the specified intersection angle, simulate the actual target, process the obtained echo signal and store it in the form of a txt file;

[0023] Perform imaging calculations, select image point distances with normalization amplitudes greater than the threshold value, and take the average value to obtain a rough estimate of the distance at each angle;

[0024] The coarse distance estimate at each angle is averaged to obtain the statistical value. The actual value is compared with the statistical value, and the coarse distance estimate at each angle is fine-tuned within the specified intersection angle range.

[0025] Optional, coarse velocity estimation for hypersonic targets includes:

[0026] Step 31, determine the difference between the two measurement intervals:

[0027] Based on the fine distance values ​​L1 and L2 from the two imaging measurements, the difference L between the measurements is determined as follows:

[0028] L = L1 - L2

[0029] In the formula, L1 is the fine distance value of the first imaging measurement, and L2 is the fine distance value of the second imaging measurement;

[0030] Step 32, a rough estimate of the speed:

[0031] The line connecting the detector and the target has an angle α with the target's trajectory. Based on the difference between the two measurement intervals and angle α, the displacement L′ = Lcosα on the target's trajectory is determined. The measurement time interval τ and the coarse estimate of the velocity are:

[0032]

[0033] Optionally, the precise velocity measurement of a hypersonic target is as follows:

[0034] Step 41, Single-pulse echo full compensation:

[0035] During imaging, the first and second terms of the pulse number can cause range image migration and energy divergence. A compensation factor is used to eliminate these first and second terms. The compensation factor is:

[0036]

[0037] In the formula: T r T is the pulse repetition period. s The sampling period is f0, the initial carrier frequency is f0, Δf is the carrier frequency step size, and v is v. r Here, n is the velocity estimate, k is the number of pulses, k is the nth sampling point of the pulse, and c is the speed of light.

[0038] Step 42, Speed ​​range selection:

[0039] The coarse velocity estimate is used as the center value of the search range, which is affected by the smallest resolution unit of the imaging and the measurement interval.

[0040] Step 43: Determine similarity using the imaging point distance method:

[0041] Within a certain speed range, the similarity between the speed-compensated image and the still image is compared, and the speed compensation value with the highest similarity is taken as the more accurate speed estimate.

[0042] This application offers high ranging accuracy: By utilizing statistical values ​​within a specified intersection angle, the average value of image points crossing a threshold is corrected, thus improving ranging accuracy. Furthermore, this application demonstrates high velocity measurement accuracy: By comparing the similarity between the stationary image and the imaging result after single-pulse velocity compensation, the velocity measurement accuracy is high, solving the problem of insufficient velocity measurement accuracy in existing technologies. Attached Figure Description

[0043] Figure 1 A flowchart of a method for accurate ranging and velocimetry of hypersonic targets based on one-dimensional imaging detection, provided in an embodiment of this application;

[0044] Figure 2 A flowchart illustrating one-dimensional range imaging of hypersonic targets provided in this application embodiment.

[0045] Figure 3 A flowchart illustrating the distance measurement steps for hypersonic targets provided in this application embodiment;

[0046] Figure 4 A flowchart illustrating the steps for coarse velocity estimation of a hypersonic target provided in this application embodiment;

[0047] Figure 5 A flowchart illustrating the steps for precise velocity measurement of a hypersonic target provided in this application embodiment;

[0048] Figure 6 Image point distance method for an actual velocity of 2000 m / s provided in this application embodiment;

[0049] Figure 7 The image point distance method for an actual velocity of 4500m / s is provided for the embodiments of this application. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0051] The following is a combination of... Figure 1 This application will be described in detail.

[0052] This application provides a method for accurate ranging and velocities of hypersonic targets based on one-dimensional imaging detection, the method comprising:

[0053] Step 10, one-dimensional range imaging of hypersonic targets:

[0054] The target is decomposed into a surface model based on its three-dimensional geometric shape. The visible surface echo vectors are superimposed to obtain the overall echo signal of the target. After sampling and processing the echo signal, an IFFT transformation is performed to obtain a one-dimensional imaging result.

[0055] Specifically, step 10 includes:

[0056] Step 11, Hypersonic Target Visible Element Identification: Based on the target's three-dimensional geometric model, obtain the vertex coordinates and external normal vectors of each triangular element of the target in the ground coordinate system, and then identify the visible surfaces.

[0057] Step 12, echo sampling matrix of hypersonic target:

[0058] Determine the radar cross section of the visible elements, and based on the transmitted signal, superimpose the echo vectors of the visible elements to obtain the overall echo signal of the target. Obtain the echo sampling matrix according to the sampling frequency.

[0059] Step 13, High-resolution one-dimensional imaging of hypersonic targets:

[0060] After processing the echo sampling matrix, an IFFT transform is performed, and the maximum value method is used to stitch together the data to remove redundancy and obtain accurate imaging results.

[0061] Step 20, distance measurement of hypersonic targets:

[0062] A threshold value is set, and the average distance of target imaging points with a normalization amplitude greater than the threshold value is used as a coarse distance estimate. The mean of the coarse estimate is calculated within a specified intersection angle range, and the error is compared with the actual distance. After correcting the coarse distance estimate, a fine distance measurement value is obtained.

[0063] Specific step 20 includes:

[0064] Step 21, coarse distance estimation: Set a threshold value, record the distances of image points whose normalization amplitude is greater than the threshold value, and calculate the average value. The average value is the coarse distance estimate.

[0065] Step 22, fine distance measurement: Select an appropriate step size within the specified intersection angle, simulate the actual target, process the obtained echo signal and store it in the form of a txt file;

[0066] Perform imaging calculations, select image point distances with normalization amplitudes greater than the threshold value, and take the average value to obtain a rough estimate of the distance at each angle;

[0067] The average of the coarse distance estimates at each angle is used as the statistical value. The actual value is compared with the statistical value, and the coarse distance estimates at each angle are fine-tuned within a specified intersection angle range. This avoids excessive errors caused by uneven distribution of target imaging points. The table below shows the distance measurement results when the relative velocity between the projectile and the target is 5000 m / s.

[0068] Table 1: Distance Measurement Table When the Relative Velocity Between Projectile and Object is 5000 m / s

[0069] Simulated counting Bullet range Measuring distance 0 925.0270 924.5890 1 850.0294 949.5956 2 775.0323 774.6928 3 700.0357 699.5894 4 625.0400 624.7726 5 550.0455 549.7672 6 475.0526 474.7600

[0070] Step 30, rough velocity estimation of the hypersonic target:

[0071] Based on the difference between two fine distance measurements taken at the measurement interval, a rough estimate of the target's velocity is obtained.

[0072] Specifically, step 30 includes:

[0073] Step 31, determine the difference between the two measurement intervals:

[0074] Based on the fine distance values ​​L1 and L2 from the two imaging measurements, the difference L between the measurements is determined as follows:

[0075] L = L1 - L2

[0076] In the formula, L1 is the fine distance value of the first imaging measurement, and L2 is the fine distance value of the second imaging measurement;

[0077] Step 32, a rough estimate of the speed:

[0078] The line connecting the detector and the target has an angle α with the target's trajectory. The change of α between the two measurement intervals is very small and can be ignored. Based on the difference between the two measurement intervals and the angle α, the displacement L′ = Lcosα on the target's trajectory is determined, the measurement time interval τ is given, and the rough estimate of the velocity is:

[0079]

[0080] Step 40, precise velocity measurement of the hypersonic target:

[0081] The similarity is compared using the image point distance method. The similarity between the distance image after velocity compensation within a certain velocity range and the static image result is compared, and the velocity value with the highest similarity is selected as the target's moving velocity.

[0082] Specifically, step 40 includes:

[0083] Step 41, Single-pulse echo full compensation:

[0084] During imaging, the first and second terms of the pulse number can cause range image migration and energy divergence. A compensation factor is used to eliminate these first and second terms. The compensation factor is:

[0085]

[0086] In the formula: T r T is the pulse repetition period. s The sampling period is f0, the initial carrier frequency is f0, Δf is the carrier frequency step size, and v is v. r Here, n is the velocity estimate, k is the number of pulses, k is the nth sampling point of the pulse, and c is the speed of light.

[0087] Step 42, Speed ​​range selection:

[0088] The coarse velocity estimate is used as the center value of the search range, which is affected by the smallest resolution unit of the imaging and the measurement interval.

[0089] Step 43: Determine similarity using the imaging point distance method:

[0090] Within a certain speed range, the similarity between the speed-compensated image and the still image is compared, and the speed compensation value with the highest similarity is taken as the more accurate speed estimate. The similarity is determined using the imaging point distance method, which involves summing the absolute values ​​of the distance differences between each imaging point in both images whose normalization amplitude is greater than a threshold value; a smaller sum indicates a higher similarity.

[0091] This application offers high ranging accuracy: By utilizing statistical values ​​within a specified intersection angle, the average value of image points crossing a threshold is corrected, thus improving ranging accuracy. Furthermore, this application demonstrates high velocity measurement accuracy: By comparing the similarity between the stationary image and the imaging result after single-pulse velocity compensation, the velocity measurement accuracy is high, solving the problem of insufficient velocity measurement accuracy in existing technologies.

[0092] The embodiments described above do not constitute a limitation on the scope of protection of this application.

Claims

1. A method for precise ranging and velocity measurement of hypersonic targets based on one-dimensional imaging detection, characterized in that, The method comprises: Step 10, one-dimensional range imaging of the hypersonic target: According to the three-dimensional geometric shape of the target, the target is decomposed into a facet model, the echo vectors of the visible facets are superimposed to obtain the overall echo signal of the target, and after sampling operation of the echo signal, IFFT transformation is performed to obtain the one-dimensional imaging result; Step 20, range measurement of the hypersonic target: Set a threshold value, average the range of the target imaging points with a normalized amplitude greater than the threshold value to obtain a coarse range estimation value, and in a specified intersection angle range, the average of the coarse estimation values is counted, the error is compared with the actual range, and the coarse range estimation value is corrected to obtain a fine range measurement value; Step 30, coarse velocity estimation of the hypersonic target: According to the difference between the two fine range measurement values of the measurement interval, the coarse velocity estimation value of the target is analyzed; Step 40, fine velocity measurement of the hypersonic target: The similarity is compared by using the image point distance method, the similarity of the range image after velocity compensation in a certain velocity interval and the static imaging result is compared, and the velocity value with the highest similarity is selected as the motion velocity of the target.

2. The method of claim 1, wherein, One-dimensional range imaging of the hypersonic target comprises: Step 11, visible facet judgment of the hypersonic target: according to the three-dimensional geometric model of the target, the vertex coordinates and the outer normal vectors of each triangular facet of the target in the ground coordinate system are obtained, and the visible facet judgment is performed; Step 12, echo sampling matrix of the hypersonic target: The radar scattering cross section of the visible facet is determined, the echo vectors of the visible facets are superimposed according to the transmitted signal to obtain the overall echo signal of the target, and the echo sampling matrix is obtained according to the sampling frequency; Step 13, high-resolution one-dimensional imaging of the hypersonic target: After operation and processing of the echo sampling matrix, IFFT transformation is performed, the maximum value method is used for splicing to remove redundancy to obtain an accurate imaging result.

3. The method of claim 1, wherein, Range measurement of the hypersonic target comprises: Step 21, coarse range estimation: set the threshold value, record the distances of the image points with a normalized amplitude greater than the threshold value and take the average value, and the average value is the coarse range estimation value; Step 22, fine range measurement: select an appropriate step size within the specified intersection angle, simulate the actual target, and store the processed echo signal in the form of a txt file; Perform imaging operation, select the distance of the image points with a normalized amplitude greater than the threshold value, take the average value to obtain the coarse range estimation value at each angle; The average of the coarse range estimation values at each angle is taken as the statistical value, the actual value and the statistical value are compared, and the coarse range estimation value at each angle is fine-tuned within the specified intersection angle range.

4. The method of claim 1, wherein, Coarse velocity estimation of the hypersonic target comprises: Step 31, determine the difference value of the measurement interval: According to the fine range values L1 and L2 of the two imaging measurements, the difference value L of the measurement interval is determined as: L = L1 - L2 In the formula, L1 is the fine range value of the first imaging measurement, and L2 is the fine range value of the second imaging measurement; Step 32, coarse velocity estimation value: The line connecting the detector and the target and the trajectory of the target form an angle α, according to the difference value of the measurement interval and the angle α, the displacement L' = Lcosα on the target motion trajectory is determined, the measurement time interval τ, and the coarse velocity estimation value is:

5. The method of claim 1, wherein, The fine measurement of the speed of hypersonic target is: Step 41, full compensation of single pulse echo: The first order and second order of the number of pulses in the imaging process will cause the distance image to move and the energy to diverge, and the first order and second order are eliminated by using compensation factor, and the compensation factor is: where T r is the pulse repetition period, T s is the sampling period, f0is the initial carrier frequency, Δf is the carrier frequency step, v r is the velocity estimate, n is the pulse number, k is the sample number within the pulse, and c is the speed of light. Step 42, selection of speed range: The coarse speed estimate value is taken as the center value of the search range, and the search range is affected by the minimum resolution unit of imaging and the measurement interval; Step 43, similarity is judged by using imaging point distance method: The similarity of the speed compensation image and the still imaging in a certain speed range is compared, and the speed compensation value with the highest similarity is taken as the more accurate speed estimate value.

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