阅读说明：本技术 一种凝视雷达测量下降段弹道方法 (Method for measuring descending section trajectory by staring radar ) 是由 尹晓虎 吴旻昊 张庆标 孙扬 吴宝剑 李振强 于 2020-08-03 设计创作，主要内容包括：本发明公开了一种凝视雷达测量下降段弹道方法,包括安装在雷达支架上的1个发射天线、1个接收天线阵列,测量步骤如下；S1、接收天线阵列采集的弹头的雷达数据,利用动目标检测MTD对弹头目标检测,并获得其距离和速度；S2、使用比幅和比相算法对接收天线各个通道数据进行处理得到弹头相对于雷达的方向；S3、利用卡尔曼滤波算法计算弹头点迹；S4、根据弹头点迹估计其下降段弹道参数,进而得到其下降段弹道。本发明采用固定波束始终照射下降段的炮弹目标,采用线性调频连续波体制,测量弹头目标的距离、速度、方向信息,并融合自身传感器获取的雷达姿态信息,估计弹头下降段弹道参数,使用轨迹外推算法计算得到弹头落点。(The invention discloses a method for measuring a descending section trajectory by a staring radar, which comprises 1 transmitting antenna and 1 receiving antenna array which are arranged on a radar bracket, wherein the measuring steps are as follows; s1, receiving the radar data of the warhead collected by the antenna array, detecting the warhead target by using a Moving Target Detection (MTD), and obtaining the distance and the speed of the warhead target; s2, processing the data of each channel of the receiving antenna by using a amplitude comparison and phase comparison algorithm to obtain the direction of the warhead relative to the radar; s3, calculating warhead traces by using a Kalman filtering algorithm; and S4, estimating the descending section trajectory parameters according to the bullet point trajectory, and further obtaining the descending section trajectory. The method adopts a fixed beam to irradiate a shell target in a descent section all the time, adopts a linear frequency modulation continuous wave system, measures distance, speed and direction information of the shell target, integrates radar attitude information acquired by a sensor of the device, estimates ballistic parameters of the descent section of the shell, and calculates by using a trajectory extrapolation algorithm to obtain a drop point of the shell.)

1. A method for measuring a descending section trajectory by a staring radar comprises 1 transmitting antenna and 1 receiving antenna array which are arranged on a radar bracket, wherein the transmitting antenna is positioned above the receiving antenna array, and the receiving antenna array can be manually operated to perform azimuth adjustment and pitching adjustment operations;

s1, receiving the radar data of the warhead collected by the antenna array, detecting the warhead target by using a Moving Target Detection (MTD), and obtaining the distance and the speed of the warhead target;

s2, processing the data of each channel of the receiving antenna by using a amplitude comparison and phase comparison algorithm to obtain the direction of the warhead relative to the radar;

s3, calculating warhead traces by using a Kalman filtering algorithm;

and S4, estimating the descending section trajectory parameters according to the bullet point trajectory, and further obtaining the descending section trajectory.

2. A staring radar system according to claim 1, wherein the transmitting antenna and the receiving antenna array both use a chirped continuous wave system with an operating frequency band of S-band.

3. A staring radar system according to claim 1 wherein the receive antenna array is four receive antennas arranged to form a 2 x 2 area array of a field pattern.

4. A staring radar system according to claim 1, wherein the azimuth adjustment is by means of a turntable and locking mechanism, the rotation angle being 0-360 °; the pitching adjustment is performed through a telescopic rod of the screw rod mechanism, and the rotation angle is 0-80 degrees.

5. A staring radar system according to claim 1 wherein each of the receive antennas and the transmit antenna in the array of receive antennas are spaced apart by a predetermined distance in both the up and down direction and the forward and backward direction.

Technical Field

The invention relates to the technical field of radars, in particular to a method for measuring descending section trajectory by a staring radar.

Background

In recent years, troops strengthen actual combat training, the strength is high, the frequency is high, and the problem of 'increment' that unexplosive bombs are increased and the potential safety hazard is increasingly serious is brought. Considering that the distance between the newly-added unexploded bomb and the earth surface is shallow, the fuse is not invalid, the safety risk is higher, and the influence is larger, therefore, the requirement for solving the 'increment' unexploded bomb investigation is more and more urgent. The traditional unexploded bomb is inspected in a mode that a warhead falls to the ground and then looks downwards, and the mode is generally used for inspecting dielectric constant, conductivity, density, magnetic field and even attraction abnormality caused by underground unexploded bombs in the soil environment, but the abnormality information is very weak, so that the unexploded bombs are often required to be close to the ground, and the accumulation time is increased to improve the sensitivity, so that the inspection speed is low, the efficiency is low, and the safety is poor. Therefore, a new idea of 'looking up' is provided, namely, the impact point is presumed through the trajectory of the descending section of the shell, and then unmanned fine judgment is carried out, and the method can be divided into three stages: and (4) positioning the impact point, judging the unexploded bomb and removing the unexploded bomb.

The impact point positioning is a precondition for a new approach of unexploded bomb detection technology. Therefore, the impact point positioning technical means has the following capabilities: firstly, the landing point is quickly, accurately and comprehensively positioned, and the positioning error meets the requirements of judging and checking unexploded projectiles; secondly, the projectile groups shot in alignment and intensive shooting can be quickly and accurately positioned, and no missing report or false report occurs; thirdly, the system is not influenced by smoke dust, fire light, vibration and the like in a target range and weather conditions such as sand dust, haze, rain, snow and the like, and can work all day long at day and night; fourthly, the method has the capability of detecting 'no-shot', namely, the target with a shot point outside a drop zone can be detected and positioned; fifthly, unattended operation can be performed, and personnel safety risks are eliminated; sixthly, the operation is simple, the automation degree is high, and the coordinate information of the impact point can be output in real time.

Disclosure of Invention

Object of the Invention

The invention provides a method for measuring a falling section trajectory by a staring radar.

Technical scheme

The invention provides a method for measuring a descending section trajectory by a staring radar, which comprises 1 transmitting antenna and 1 receiving antenna array, wherein the 1 transmitting antenna and the 1 receiving antenna array are arranged on a radar bracket; the measuring steps are as follows;

s1, receiving the radar data of the warhead collected by the antenna array, detecting the warhead target by using a Moving Target Detection (MTD), and obtaining the distance and the speed of the warhead target;

s2, processing the data of each channel of the receiving antenna by using a amplitude comparison and phase comparison algorithm to obtain the direction of the warhead relative to the radar;

s3, calculating warhead traces by using a Kalman filtering algorithm;

and S4, estimating the descending section trajectory parameters according to the bullet point trajectory, and further obtaining the descending section trajectory.

Preferably, the transmitting antenna and the receiving antenna array both adopt a linear frequency modulation continuous wave system (LFMCW) with an S-band working frequency band.

Preferably, the receiving antenna array is four receiving antennas, and the four receiving antennas are arranged and installed to form a 2 × 2 area array in a shape of a Chinese character tian.

Preferably, the azimuth adjustment is performed through the turntable and the locking mechanism, and the rotation angle is 0-360 degrees; the pitching adjustment is performed through a telescopic rod of the screw rod mechanism, and the rotation angle is 0-80 degrees.

Preferably, each receiving antenna and each transmitting antenna in the receiving antenna array are spaced at a preset distance in the up-down direction and the front-back direction, so as to improve the receiving-transmitting isolation.

The method has natural advantages of utilizing radar technology to position the impact point, and can adopt a high-precision and high-data-update-rate radar system to accurately measure the trajectory of the descending section (tail section) of the warhead and estimate the impact point. Unlike the gun position reconnaissance and calibration radar, this type of radar does not form a scanning beam in space and pursues a long-distance detection capability of several tens of kilometers, but uses a fixed beam to always irradiate a projectile target in a descent section, and is therefore called "staring". The method adopts a fixed beam to irradiate a shell target in a descent section all the time, adopts a linear frequency modulation continuous wave system, measures distance, speed and direction information of the shell target, integrates radar attitude information acquired by a sensor of the device, estimates ballistic parameters of the descent section of the shell, and calculates by using a trajectory extrapolation algorithm to obtain a drop point of the shell.

Drawings

Fig. 1 is a system block diagram of a staring radar according to the present invention;

FIG. 2 is a schematic structural diagram of a staring radar according to the present invention;

FIG. 3 is a flow chart of a gaze radar measured descent trajectory estimation proposed by the present invention;

FIG. 4 is a schematic diagram of a moving target detection process;

FIG. 5 is a schematic diagram of a moving target display canceller;

FIG. 6 is a schematic diagram of a MTD transversal filter structure;

fig. 7 is a diagram of amplitude and direction finding real-time processing.

FIG. 8 is a schematic view of amplitude direction finding;

FIG. 9 is a tracking filter distance height error plot;

FIG. 10 is a graph of tracking filter observation times error;

FIG. 11 is a simulated statistical distribution diagram of impact point errors.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

As shown in fig. 1-3, the staring radar system provided by the present invention includes a transmitting antenna 1 and a receiving antenna array 2 mounted on a radar support, where the transmitting antenna 1 and the receiving antenna array 2 both use a chirped continuous wave system with an S-band working frequency band, and the receiving antenna array 2 is four receiving antennas arranged to form a 2 × 2 matrix in a shape of a Chinese character tian. The transmitting antenna 1 is located above the receiving antenna array, and each receiving antenna and each transmitting antenna in the receiving antenna array 2 are spaced at preset distances in the up-down direction and the front-back direction so as to improve the receiving-transmitting isolation. The receiving antenna array 2 can be manually operated to perform azimuth adjustment and pitching adjustment, the azimuth adjustment is performed through the rotary table and the locking mechanism, and the rotation angle is 0-360 degrees; the pitching adjustment is performed through a telescopic rod of the screw rod mechanism, and the rotation angle is 0-80 degrees.

A staring radar descending segment trajectory measuring method comprises the following steps;

s1, receiving the radar data of the warhead collected by the antenna array 2, detecting the warhead target by using a Moving Target Detection (MTD), and obtaining the distance and the speed of the target;

s2, processing the data of each channel of the receiving antenna by using a amplitude comparison and phase comparison algorithm to obtain the direction of the warhead relative to the radar;

s3, calculating warhead traces by using a Kalman filtering algorithm;

and S4, estimating the descending section trajectory parameters according to the bullet point trajectory, and further obtaining the descending section trajectory.

The method for measuring the descending section trajectory comprises the following specific steps:

1. moving Target Detection (MTD)

The ballistic staring radar emits electromagnetic waves to irradiate an airspace through which the warhead passes, and when the warhead passes through, the radar detects a warhead target from an echo. The moving target detection flow diagram is shown in fig. 4, and includes pulse compression, moving target display, moving target detection, and constant false alarm detection.

The pulse compression core algorithm is the fast fourier transform. Because the system adopts a linear frequency modulation continuous wave system, the pulse compression is adopted to realize the matched filtering of the received signals. The staring radar observes the sky, the scene is fixed, the surrounding environment is mostly a static environment, a moving target display (MTI) algorithm is used for processing, a double-delay canceller structure is selected for suppressing static clutter, the moving warhead and the static clutter are effectively separated, and a schematic diagram of a moving target display cancellation structure is shown in fig. 5.

Because the moving target display filter cannot completely suppress the static clutter, the residual clutter power output by the moving target display filter is still relatively large. Moving Target Detection (MTD) techniques can be used to ameliorate this problem. Compared with MTI, MTD can make the frequency spectrum of the filter close to the matched filter, and increase the improvement factor; weak targets in the target can be detected when the clutter is strong; fixed and spectrally spread clutter may also be filtered out.

According to the theory of optimal linear filtering, when it is known that the clutter and signal spectra are c (f), s (f), respectively, the optimal filter is:

in effect, a matched filter for spurs. It can be divided into two cascaded filters H₁(f) And H₂(f)：

It can be considered that the clutter filter H₁(f) For suppressing clutter, which is equivalent to MTI, followed by concatenated H₂(f) Is thatFor matching radar return signals. When the echo is matched and filtered, the target Doppler frequency shift f needs to be known_d. But in general f_dUnpredictable, a set of narrow band filter banks covering the entire doppler frequency range can be used. The MTD is a filter bank for filtering radar clutter and detecting targets, and fig. 6 is a schematic diagram of a MTD filter with a transverse structure, which is usually implemented by using FFT.

Constant false alarm detection is an algorithm that can provide a detection threshold and minimize the effect of various interferences on the false alarm probability of a system, and this algorithm can maintain the false alarm probability at a relatively stable value. Considering that the system works in an empty environment and background clutter is uniform, a CA-CFAR can be adopted, the algorithm obtains a detection threshold in a self-adaptive mode by calculating the arithmetic mean value of N units in a sliding window, and the detection probability approaches to the ideal detection probability of a fixed threshold of known clutter parameters along with the increase of N. The schematic diagram of the CA-CFAR algorithm is shown in FIG. 7.

2. Direction finding processing

According to the design characteristics of the system, the direction-finding antenna can be used for carrying out direction finding on amplitude or phase responses arriving in different directions, namely the common amplitude method direction finding, the common phase method direction finding and the common amplitude-phase method. The amplitude method direction finding is to determine the arrival angle of a signal according to the relative amplitude of the signal received by a receiving antenna, the amplitude comparison method is a classic algorithm thereof, a plurality of antennas with different beam directions are usually adopted to cover a certain space, the direction of a target is determined according to the relative amplitude of the same signal received by each antenna, and the processing flow is shown in fig. 8.

3. Calculating warhead trace

And calculating the trace point of the warhead by MTD and direction finding processing and combining attitude data acquired by an attitude measuring sensor of the system. In the descending section, the position and the speed of the warhead are measured by using a radar, observed quantities are a pitch angle theta and an azimuth angle phi of a distance r, and the radar observed quantities can be converted into input quantities in a trajectory equation through coordinate conversion, wherein the input quantities are the position (x, y, z) and the speed of the warheadDue to the influences of radar system noise, target signal-to-noise ratio, external electromagnetic interference and the like, certain errors exist in the warhead position information observed by the radar, and the error of the drop point is estimated directly through single observation. In order to improve the accuracy of the point estimation of the bullet, the accuracy of the point estimation of the bullet can be improved by fully utilizing an observation sequence obtained by a radar in the process that the bullet passes through a radar beam and combining Kalman filtering. The descending section adopts a constant acceleration Kalman model to describe the warhead track more accurately. Assume that the warhead state is defined by a six-dimensional vector as follows:

the motion and observation equations for the target are:

x_k＝Φ_k,k-1x_k-1+_k,k-1w_k-1

z_k＝H_kx_k+v_k

v_kand w_k-1Is zero mean and noise covariance is Q_kAnd R_kWhite gaussian noise. Posterior probability density p (x) at time k-1_k-1|y_k-1) Is a mean value of

Variance is P_k-1|k-1Gaussian form of (a). The five formulas of Kalman filtering are respectively:

X_forecast(k)＝AX_estimation(K-1)+B×g

P_forecast(k)＝AP_estimation(K-1)A^T+Q_k

K＝P_forecast(k)H×(H×P_forecast(k)×H^T+R)^-1

P_estimation(K)＝(I-KH)P_forecast(k)

according to the radar system and the antenna parameters, the radar bandwidth is 50MHz, the radar ranging precision is about 0.5m, the worst antenna angle measurement precision is assumed to be 2 degrees, and the position error corresponding to the position 750m farthest is 26 m. The results of the simulation using these parameters are shown in fig. 9 and 10. It can be known that in the process of the warhead passing through the radar beam, the radar can obtain dense position observation, and the position error is reduced and stabilized to about 3m after about 100 times of observation by using the data and Kalman filtering processing.

4. Descent segment trajectory parameter estimation

The content of the external ballistic research comprises the mass center movement of the bullet, the stress condition of the bullet during flying, the law of the bullet in the motion around the center and the influence factors generated by the law, the application of the law of the external trajectory in practice and the like. It is mainly divided into two major parts, particle ballistics and rigid body ballistics. Particle ballistics is that under a certain assumption, some forces and all moments which have small influence on the movement of a warhead are omitted, the warhead is taken as a particle, and the movement law of the warhead under the action of gravity, air resistance and thrust of a rocket engine is researched. Particle ballistics research is to simplify the trajectory calculation problem under conditions, analyze factors affecting trajectory, and preliminarily analyze the causes of dispersion and resulting shooting errors. Here, the bullet will be regarded as a particle hereinafter because the attitude of the bullet is stable due to the observed descent trajectory, and the particle ballistics fully satisfies the accuracy requirement.

Taking a 122 grenade warhead as an example, a particle trajectory model is used to describe the trajectory equation as follows:

c is the coefficient of the trajectory,

as the speed of the bullet head,τ_onis the ground standard virtual temperature, tau_zThe deficiency temperature at the height z; h (a), (b)z) is a gas weight function and a resistance functionC_xonZero angle of attack drag coefficient; g is the acceleration of gravity.

The simulation is carried out by setting the initial speed of the warhead of a typical 122 grenade gun to be 618m/s, the diameter of the grenade to be 0.122m, the weight to be 21.76kg, the shooting angle to be 240mil and the trajectory coefficient to be 0.25, and the trajectory of the warhead is relatively straight in the descending section. During the irradiation of the radar beam, the distance between the bullet and the radar is 470-580m, the radial speed of the bullet relative to the radar is 100-180m/s, and the included angle between the radar beam and the axial direction of the target is 50-70 degrees. The time length of the radar irradiation period is 0.8s, and a plurality of warhead running traces can be obtained.

After filtering the trajectory, the trajectory coefficient C is estimated by the least square method, thereby dropping the segment trajectory. And continuously extrapolating the trajectory after the irradiation time of the radar beam, and solving the intersection point of the trajectory and the ground plane, namely the coordinates of the impact point. The accuracy of ballistic extrapolation is inversely proportional to the length of the extrapolation time and directly proportional to the accuracy of the ballistic model. As the radar is observed near the descending section, the atmospheric environment and the stress characteristics of the warhead are stable, so that the end trajectory model is accurate, only the influence of extrapolation time on the final drop point precision is analyzed, the impact point error of 122mm is statistically obtained through Monte Carlo simulation for 1000 times, as shown in figure 11, and the standard deviation of the error is about 3.15 m.

It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.