A target track simulation method for an infrared search and track device

Abstract

The application discloses a target track simulation method of an infrared search and tracking device. Firstly, velocity components in X and Y directions are calculated according to the movement speed and the heading angle of a target; then, the time when the target is detected by the device in a current frame is calculated more accurately according to the velocity of the target in the X direction and the rotating speed of the device, and the specific method is as follows: the 360-degree azimuth of the device is discretized at equal time intervals to coarsely predict the time when the target is detected by the device, and linear interpolation is performed on the coarsely predicted time to realize more accurate time prediction; finally, the azimuth and the pitch angle of the target in the current frame are calculated in combination with the movement speed of the target in the X and Y directions and the distance between the target and the device. The method realizes accurate time simulation of the target in each frame through the method of azimuth equal-time discretization and linear interpolation, finally realizes accurate simulation of the azimuth and the pitch angle, and effectively improves the accuracy of target track simulation.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic simulation technology, and in particular to a target trajectory simulation method for infrared search and tracking equipment. Background Technology

[0002] Injection-based simulation systems can reduce the manpower and material costs and equipment wear and tear of field testing, save the development time and cost of target detection and recognition algorithms, provide a platform guarantee for the continuous upgrading of algorithms, and provide technical support for the development of infrared search and tracking systems. Therefore, it is particularly important to strengthen the research on injection-based simulation systems.

[0003] The prerequisite for an injection-based simulation system is to simulate the target's trajectory to obtain the target's position information (azimuth and pitch angles) in each frame of image. However, due to the relative motion between the target and the equipment, there is an error in the time when the equipment detects the target in each frame of image. This ultimately leads to errors in the target's azimuth and pitch angles in the simulated trajectory. Moreover, the greater the target's azimuth velocity, the greater the angular error. Therefore, improving the accuracy of target trajectory simulation in an injection-based simulation system has become a challenging task.

[0004] Traditional algorithms for flight path simulation technology simulate the target's position based on time intervals such as the device's scanning cycle, neglecting the target's motion and resulting in low accuracy in the simulated target trajectory position. When there is relative motion between the target and the device, and the device's rotational angular velocity is much greater than the target's angular velocity, the simulated target angle approximates a pursuit problem. This invention discretizes the device's azimuth angle at equal time intervals and then linearly interpolates the potential time intervals to infinitely approximate the position where the device's line of sight meets the target. This significantly improves the accuracy of target trajectory simulation and is of great significance to the research of injection-type simulation systems. Summary of the Invention

[0005] The purpose of this invention is to provide a target trajectory simulation method for infrared search and tracking equipment to solve the problem of low target trajectory simulation accuracy in the prior art. The method of this invention achieves accurate time simulation of the target for each frame by using time discretization and linear interpolation methods such as azimuth angle, and finally achieves accurate simulation of azimuth angle and pitch angle, effectively improving the accuracy of target trajectory simulation.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A target trajectory simulation method for an infrared search and tracking device, characterized by comprising the following steps:

[0008] First, calculate the velocity components in the X and Y directions based on the target's speed and heading angle;

[0009] Then, based on the target's velocity in the X direction and the rotation speed of the infrared search and track device, the time when the infrared search and track device detects the target in the current frame is calculated more accurately. The specific method is as follows: the device's 360° azimuth angle is discretized at equal time intervals to make a coarse prediction of the time when the infrared search and track device detects the target, and the coarse prediction time is linearly interpolated to achieve a more accurate time prediction.

[0010] Finally, by combining the target's movement speed in the X and Y directions and the distance between the target and the infrared search and tracking device, the azimuth and elevation angles of the target in the current frame are calculated.

[0011] The target trajectory simulation method for the infrared search and tracking device is characterized by the following steps:

[0012] A. Calculate the velocity components V of the target in the X and Y directions based on the target's velocity V and heading angle h. x and V y :

[0013] V x =V*sin(h)

[0014] V y =V*cos(h)

[0015] B. Target simulation time calculation:

[0016] a) Roughly predict simulation time based on sampling at time intervals such as equipment azimuth angle;

[0017] The equipment's 360° azimuth angle is calculated per T. d Samples are taken once per second, assuming the device rotates at a speed of T revolutions per second. c If the device scans for one lap, then the total number of samples N is:

[0018]

[0019] The azimuth angle rotated by the device at each sampling interval is:

[0020]

[0021] The azimuth angle of the device after the current sampling time is:

[0022] azi d_t =azi d_t-1 +azi d

[0023] The initial sampling azimuth angle of the device is 0°;

[0024] The azimuth angle of the target after the current sampling time is

[0025]

[0026] Y t =Y t-1 +T d *V y

[0027] X t =X t-1 +T d *V x

[0028] Among them, X t-1 and Y t-1 These are the target's X and Y coordinates after the previous sampling time, respectively. t and Y t These are the target's X and Y coordinates after the current sampling time;

[0029] After the current sampling time, the azimuth angle of the device is less than the azimuth angle of the target, i.e., Δ d_t-1 <0; while the azimuth angle of the device is greater than the azimuth angle of the target after the current sampling time, Δ d_t When the value is greater than 0, the device has detected the target within the current sampling interval, that is:

[0030] Δ d_t-1 <0&&Δ d_t >0

[0031] Δ d_t =azi d_t -azi t_t

[0032] Δ d_t-1 =azi d_t-1 -azi t_t-1

[0033] Among them, azi d_t-1 and azi t_t-1 The azimuth angles of the device and the target since the last sampling time are given, and the current sampling interval is the simulation time for coarse prediction.

[0034] b) Perform linear interpolation on the coarse prediction time to further refine the simulation time prediction;

[0035] Linear interpolation is performed on the coarse prediction sampling interval:

[0036]

[0037] Δ0 d_t =azi d_t -k*Δ d_t

[0038] Where k is (Δ d_t-1 ,azid_t ) and (Δ d_t ,azi d_t-1 Determine the slope of the straight line, Δ0 d_t This is the equipment azimuth angle when the difference between the equipment azimuth angle and the target azimuth angle is 0;

[0039] The time T at which the device detects the target in the current frame is:

[0040]

[0041] Among them, T c The time it takes for the equipment to complete one revolution, in seconds;

[0042] C. Calculate the azimuth and elevation angles of the target in the current frame based on the time the device detected the target and the target's velocity in the X and Y directions:

[0043]

[0044]

[0045] Among them, X T Y T Z T The three coordinates of the target when the device detects it:

[0046] X y =V x *T

[0047] Y T =V x *T.

[0048] The main challenge in flight path simulation lies in calculating the time it takes for the equipment to detect a target. Because of the relative motion between the target and the equipment, errors occur in the equipment's calculation of the target detection time, which in turn reduces the accuracy of the azimuth and pitch angle simulations. Traditional methods simulate the target's position based on time intervals such as the equipment's scanning cycle, neglecting the target's motion.

[0049] Compared with the prior art, the beneficial effects of the present invention are:

[0050] 1. The method of the present invention takes into account the relative motion between the target and the equipment, reduces the time error of the equipment detecting the target, and improves the simulation accuracy of azimuth and elevation angles.

[0051] 2. The calculation process in the method of the present invention is relatively simple, which facilitates the improvement of the real-time performance of the injection simulation system. Attached Figure Description

[0052] Figure 1 This is a flowchart of the method of the present invention.

[0053] Figure 2 The azimuth simulation results are for the flight path.

[0054] Figure 3 The simulation results show the pitch angle of the flight path.

[0055] Figure 4 This is a comparison chart of the azimuth simulation errors of the present invention and the traditional method. Detailed Implementation

[0056] Please see Figure 1 This invention discloses a target trajectory simulation method for infrared search and tracking devices.

[0057] As shown in the figure, it includes the following steps:

[0058] First, calculate the velocity components in the X and Y directions based on the target's speed and heading angle;

[0059] Then, based on the target's velocity in the X direction and the rotation speed of the infrared search and track device, the time when the infrared search and track device detects the target in the current frame is calculated more accurately. The specific method is as follows: the 360° azimuth angle of the infrared search and track device is discretized at equal time intervals to make a coarse prediction of the time when the infrared search and track device detects the target, and the coarse prediction time is linearly interpolated to achieve a more accurate time prediction.

[0060] Finally, by combining the target's movement speed in the X and Y directions and the distance between the target and the infrared search and tracking device, the azimuth and elevation angles of the target in the current frame are calculated.

[0061] Specifically, the method includes the following steps:

[0062] A. Calculate the velocity components V of the target in the X and Y directions based on the target's velocity V and heading angle h. x and V y :

[0063] V x =V*sin(h)

[0064] V y =V*cos(h)

[0065] B. Target simulation time calculation:

[0066] a) Roughly predict the simulation time based on time interval sampling of the azimuth angle of the infrared search and tracking device;

[0067] The infrared search and tracking equipment is positioned at 360° azimuth angles per T. d Samples are taken once per second, assuming the infrared search and tracking device rotates at a speed of T revolutions per second. cIf the infrared search and tracking device scans one lap in seconds, then the total number of samples N is:

[0068]

[0069] The azimuth angle rotated by the device at each sampling interval is:

[0070]

[0071] The azimuth angle of the infrared search and tracking device after the current sampling time is:

[0072] azi d_t =azi d_t-1 +azi d

[0073] The azimuth angle of the infrared search and tracking device at the initial sampling time is 0°;

[0074] The azimuth angle of the target after the current sampling time is

[0075]

[0076] Y t =Y t-1 +T d *V y

[0077] X t =X t-1 +T d *V x

[0078] Among them, X t-1 and Y t-1 These are the target's X and Y coordinates after the previous sampling time, respectively. t and Y t These are the target's X and Y coordinates after the current sampling time;

[0079] After the current sampling time, the azimuth angle of the infrared search and tracking device is less than the azimuth angle of the target, i.e., Δ d_t-1 <0; while the azimuth angle of the infrared search and tracking device is greater than the azimuth angle of the target after the current sampling time, Δ d_t When the value is greater than 0, the infrared search and tracking device has detected the target within the current sampling interval, i.e.:

[0080] Δ d_t-1 <0&&Δ d_t >0

[0081] Δ d_t =azi d_t -azi t_t

[0082] Δ d_t-1 =azi d_t-1 -azi t_t-1

[0083] Among them, azi d_t-1 and azi t_t-1 The azimuth angles of the infrared search and tracking device and the target since the last sampling time are given, and the current sampling interval is the simulation time for coarse prediction.

[0084] b) Perform linear interpolation on the coarse prediction time to further refine the simulation time prediction;

[0085] Linear interpolation is performed on the coarse prediction sampling interval:

[0086]

[0087] Δ0 d_t =azi d_t -k*Δ d_t

[0088] Where k is (Δ d_t-1 ,azi d_t ) and (Δ d_t ,azi d_t-1 Determine the slope of the straight line, Δ0 d_t The azimuth angle of the infrared search and tracking device when the difference between the azimuth angle of the infrared search and tracking device and the azimuth angle of the target is 0;

[0089] The time T at which the infrared search and track device detects the target in the current frame is:

[0090]

[0091] Among them, T c The time taken for the infrared search and track device to complete one revolution, in seconds;

[0092] C. Calculate the azimuth and elevation angles of the target in the current frame based on the time the infrared search and tracking device detects the target and the target's velocity in the X and Y directions:

[0093]

[0094]

[0095] Among them, X T Y T Z T When the infrared search and track device detects the target, the target's three-coordinate position is:

[0096] X y =V x *T

[0097] Y T =V x *T.

[0098] The technical solutions in the embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0099] Simulation environment: Visual Studio 2019, MATLAB 2016a;

[0100] Simulation method: Assume that the rotation speed of the device is 300° / s, that is, 1.2 seconds per revolution, the initial distance between the target and the device is 5km, the initial azimuth angle is 0°, the azimuth angle is the angle between the target and true north, the target heading angle is 120°, the heading angle is the angle between the target's flight direction and true north, the target's flight altitude is 2km, and the target speed is 0.3Ma. The simulation generates N consecutive frames of the azimuth and pitch angles of the infrared search device detecting the target.

[0101] Based on the target's heading angle and initial distance, it can be determined that the target's trajectory relative to the equipment is one of approaching from a distance and then moving away. As the target approaches, its pitch angle increases, reaching its maximum when it is closest to the equipment. Then, the target moves away from the equipment, at which point its pitch angle gradually decreases. Figure 3 As can be seen from the pitch angle image of the target relative to the equipment, the pitch angle generated by the simulation is consistent with the actual situation.

[0102] The target's heading angle is 120°, and its initial azimuth angle is 0°. This means that throughout the flight, the target's azimuth angle increases from 0°, approaching 180° as it moves infinitely away from the flight path. Because the target's area gradually decreases with distance, it will become undetectable by the equipment after a certain distance. Therefore, if... Figure 2 As shown, the target's azimuth angle did not approach 180°, and the overall trend of the azimuth angle change is consistent with the analysis of the actual situation.

[0103] from Figure 2 and Figure 3 The comparative analysis shows that when the pitch angle reaches its maximum value, the target is at its closest position to the equipment. At this time, the target's azimuth velocity is the greatest and the azimuth angle changes the fastest, which is consistent with the actual situation.

[0104] Figure 4 The simulation accuracy of this algorithm is compared with that of traditional algorithms. As can be seen from the figure, the angle error of this algorithm is relatively small, the simulation accuracy is high, and the simulation error is always kept at a small level regardless of how the azimuth angular velocity changes.

Claims

1. A target trajectory simulation method for an infrared search and tracking device, characterized in that: It includes the following steps: First, calculate the velocity components in the X and Y directions based on the target's speed and heading angle; Then, based on the target's velocity in the X direction and the rotation speed of the infrared search and track device, the time when the infrared search and track device detects the target in the current frame is calculated more accurately. The specific method is as follows: the 360° azimuth angle of the infrared search and track device is discretized at equal time intervals, the time when the infrared search and track device detects the target is coarsely predicted, and the coarsely predicted time is linearly interpolated to achieve a more accurate time prediction. Finally, the azimuth and elevation angles of the target in the current frame are calculated by combining the target's motion velocity in the X and Y directions and the distance between the target and the infrared search and track device; Specifically, the steps include the following: A. Based on the target's speed of movement and heading angle Calculate the velocity components of the target in the X and Y directions. and : B. Target simulation time calculation: a) Roughly predict the simulation time based on time interval sampling of the azimuth angle of the infrared search and tracking device; The infrared search and tracking device is positioned at 360° azimuth angles according to each... Samples are taken once per second, assuming the infrared search and tracking device rotates at a speed of one revolution per second. If the infrared search and tracking device scans once per second, then the total number of samples taken is [number]. for: The azimuth angle rotated by the device at each sampling interval is: The azimuth angle of the infrared search and tracking device after the current sampling time is: The azimuth angle of the infrared search and tracking device at the initial sampling time is 0°; The azimuth angle of the target after the current sampling time is in, and These are the target's X and Y coordinates after the previous sampling time. and These are the target's X and Y coordinates after the current sampling time; If, after the previous sampling time, the azimuth angle of the infrared search and tracking device is less than the azimuth angle of the target, that is... However, at the current sampling time, the azimuth angle of the infrared search and tracking device is greater than the azimuth angle of the target. If the infrared search and tracking device detects the target within the current sampling interval, then: in, and The azimuth angles of the infrared search and tracking device and the target since the last sampling time are given, and the current sampling interval is the simulation time for coarse prediction. b) Perform linear interpolation on the coarse prediction time to further refine the simulation time prediction; Linear interpolation is performed on the coarse prediction sampling interval: in, for( )and( Determine the slope of the straight line. The azimuth angle of the infrared search and tracking device when the difference between the azimuth angle of the infrared search and tracking device and the azimuth angle of the target is 0; The time T at which the infrared search and track device detects the target in the current frame is: in, The time taken for the infrared search and track device to complete one revolution, in seconds; C. Calculate the azimuth and elevation angles of the target in the current frame based on the time the infrared search and tracking device detects the target and the target's velocity in the X and Y directions: in, When the infrared search and track device detects the target, the target's three-coordinate position is: 。

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