Flying target attitude measurement method based on simulation imaging matching algorithm

Abstract

The invention relates to the technical field of image processing, and particularly discloses a flight target attitude measurement method based on a simulation imaging matching algorithm, which is used for solving the problems of attitude angle calculation error and measurement precision reduction caused by shock wave effect and aerodynamic disturbance in the attitude measurement process of a supersonic flight target. According to the method, the Mach number is calculated through the flight speed and the local sound velocity, a corresponding simulation image template is generated and selected, a preliminary attitude angle is solved through a simulation image matching algorithm, then the preliminary attitude angle is corrected through a Mach number correction function and an attitude dynamic adjustment item, and finally the final accurate attitude angle is obtained through Kalman filtering dynamic correction. According to the method, through the Mach number correction function and the attitude angle dynamic correction term, the precision and the real-time performance of attitude angle measurement under the supersonic flight condition are remarkably improved, and the stability and the calculation efficiency of attitude angle measurement are ensured especially under the conditions of the shock wave effect and the rapid attitude change.

Description

Technical Field

[0001] The present invention relates to the technical field of image processing, and more specifically, to a method for measuring the attitude of a flying target based on a simulation imaging matching algorithm. Background Art

[0002] In the attitude measurement of flying targets, the attitude measurement of space targets based on the simulation imaging matching algorithm is to calculate the attitude angle of the flying target by comparing the similarity between the real image and the simulated image. In the actual range test, the Mach number has an impact on the aerodynamic characteristics, imaging quality and attitude measurement accuracy of the flying target. When the Mach number is greater than 1, shock waves will be generated around the flying target, and the airflow will separate from the flying target surface, causing the aerodynamic shape of the flying target to change, making the outline of the flying target complicated. At the same time, the friction between the target surface and the surrounding air will cause the target surface temperature to rise. The infrared radiation generated by the high temperature will interfere with the normal measurement of the photoelectric theodolite, resulting in image clarity. The target image will decrease, affecting the accuracy of attitude solution. The simulation image generated based on the target in a static state or a Mach number less than 0.8 will have a deviation in the actual target image contour due to the aerodynamic effect when the Mach number is greater than 1. The simulation image with a Mach number greater than 1 needs to generate multiple simulation image templates and continuously adjust the simulation results in real-time measurement. Especially in the case of multi-station measurement, the system calculation burden will increase significantly. At the same time, the aerodynamic center of the flying target will shift, especially when the angle of attack is greater than 15°, the target attitude changes rapidly, which increases the difficulty of attitude measurement. The randomness and intensity changes of aerodynamic disturbances cause the measurement response speed of the photoelectric theodolite to be insufficient, and it cannot adapt to the rapid changes in the target attitude. Summary of the invention

[0003] In order to overcome the above-mentioned defects of the prior art, the present invention provides a flight target attitude measurement method based on a simulation imaging matching algorithm, which improves the accuracy and real-time performance of attitude angle measurement under supersonic flight conditions through a Mach number correction function and an attitude angle dynamic correction term, especially under shock wave effects and rapid attitude changes, to ensure measurement stability and improve calculation speed.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A flight target attitude measurement method based on a simulation imaging matching algorithm obtains a real image through photoelectric theodolite measurement, establishes a space model through the shape parameters of the flight target, constructs a numerical simulation environment, obtains a simulation image sequence, compares the similarity between the real image and the simulation image, and then performs attitude angle solution to obtain the azimuth, pitch angle and roll angle of the flight target, obtains the fusion similarity of multi-station measurements through multi-station similarity fusion, solves the flight target attitude angle, obtains the current Mach number through the flight speed of the flight target and the local sound speed, generates and selects a simulation image template corresponding to the current Mach number according to the Mach number, solves the initial attitude angle of the flight target based on the simulation image matching algorithm, adjusts the initial attitude angle using a Mach number correction function and a flight attitude dynamic adjustment item, adjusts the flight attitude dynamic adjustment item according to the Mach number and the angle of attack, dynamically corrects the initial attitude angle through a Kalman filter algorithm, and obtains the final corrected attitude angle of the flight target.

[0006] As a further solution of the present invention, a simulation image template corresponding to the current Mach number is generated and selected according to the Mach number. The constructed simulation image library is generated by computational fluid dynamics simulation software according to the set Mach number, azimuth, pitch angle and roll angle. When there is no matching Mach number in the simulation image, the simulation image templates corresponding to two adjacent Mach numbers of the Mach number that needs to be matched are linearly interpolated to obtain a simulation image of the current Mach number. The azimuth, pitch angle and roll angle corresponding to the simulation image of the current Mach number are obtained by linear interpolation. The formula for obtaining the simulation image template of the current Mach number is:

[0007]

[0008] Where: M is the current Mach number, which is equal to the ratio of the measured speed of the flight target to the arithmetic square root of the product of the specific heat capacity of the air, the gas constant of the air, and the current ambient temperature; B(M) is the simulation image template corresponding to the current Mach number; M 1 、M 2 is the first Mach number and the second Mach number adjacent to the current Mach number in the Mach number set for simulation, M 2 >M 1 ,B(M 1 )、B(M 2 ) are the simulation image templates corresponding to the first Mach number and the second Mach number respectively.

[0009] As a further solution of the present invention, the process of calculating the initial value of the attitude angle of the flight target based on the simulation image matching algorithm includes:

[0010] Step 11, obtaining a real image and a simulated image: obtaining a real image of the flight target at the calculation time through an optoelectronic theodolite, selecting a simulated image template with the smallest difference with the current Mach number from a simulated image library according to the shape parameters of the flight target and the current Mach number, and when there is no matching simulated image template, obtaining the current Mach number simulated image template through a formula of the current Mach number simulated image template, and the space attitude angle corresponding to the current Mach number simulation template, and extracting the contour features of the flight target in the current real image and the simulated image template;

[0011] Step 12, search for the maximum similarity and obtain the initial attitude angle: take the azimuth, pitch angle and roll angle as variables respectively, gradually change the three variables in the simulated image, generate simulated images under different attitude angles, binarize the real image and the simulated image template, traverse the azimuth, pitch angle and roll angle of the simulated image within the set range of the initial attitude angle, compare each frame of the simulated image with the current real image one by one, calculate the similarity between the real image and the binary image of the simulated image, and record their attitude angles, search for the maximum value of the similarity, and obtain the initial value of the attitude angle of the flying target.

[0012] As a further solution of the present invention, the correction formula for adjusting the preliminary attitude angle using the Mach number correction function and the attitude angle dynamic correction term is:

[0013] θ final =θ initial +f(M)·Δθ+g(θ 1 ,θ 2 ,θ 3 ,σ,M)

[0014] Where: θ final is the corrected attitude angle, including the corrected azimuth angle, the corrected pitch angle and the corrected roll angle, f(M) is the Mach number correction function, Δθ is the correction amount of the attitude angle, θ 1 ,θ 2 ,θ 3 are the initial values ​​of azimuth, pitch and roll angles, σ is the angle of attack coordination coefficient, g(θ 1 ,θ 2 ,θ 3 ,σ,M) is the dynamic correction term of attitude angle.

[0015] As a further solution of the present invention, the Mach number correction function performs a comprehensive correction of the attitude angle by a linear correction term, a quadratic correction term and an exponential change correction term based on the Mach number. The formula of the Mach number correction function is:

[0016] f(M)=1+α 1 (M-1)+α 2 (M-1) 2 +α3 exp(-λ(M-1))

[0017] Where: α 1 , α 2 , α 3 is the constant coefficient fitted according to the experimental data, and λ is the influencing adjustment factor.

[0018] As a further solution of the present invention, in the correction formula for adjusting the preliminary attitude angle using the Mach number correction function, when the resolution of the photoelectric theodolite is 1024×768 pixels, the frame rate is 30 frames per second, the azimuth angle measurement accuracy is 0.1°, the pitch angle measurement accuracy is 0.15°, the roll angle measurement accuracy is 0.2°, and the simulation image attitude angle generation accuracy is 0.05°, the correction amounts of the azimuth angle, the pitch angle, and the roll angle are 0.05°, 0.1°, and 0.15°, respectively.

[0019] When the angle of attack is greater than 15°, the flying target enters the critical angle of attack region, the fluid separation effect begins to appear, the aerodynamic disturbance increases, the aerodynamic characteristics of the flying target become nonlinear, the attitude angle changes more dramatically, and sensitive correction is required. An appropriate angle of attack coordination coefficient is set so that the photoelectric theodolite and the attitude angle correction method proposed in the present invention can respond to the attitude angle change more quickly, and the weight of the attitude angle dynamic correction term is increased, so that the correction process becomes more timely and accurate, especially under the shock wave effect and airflow separation, to ensure the accuracy of the attitude angle solution. When the angle of attack is less than or equal to 15°, an appropriate angle of attack coordination coefficient is set so that the attitude angle correction process is smoother, and the weight of the attitude angle dynamic correction term is reduced. At the same time, the influence of the Mach number is considered. When the Mach number is less than or equal to 1, the attitude angle dynamic correction term is less than or equal to 1, and at the same time, the change of the attitude angle is not as dramatic as when the angle of attack is greater than 15°, and the overall attitude angle dynamic correction term gradually tends to 0.

[0020] As a further solution of the present invention, in the correction formula for adjusting the preliminary attitude angle using the Mach number correction function, the attitude angle dynamic correction term is based on the changes in the Mach number, attitude angle and angle of attack, and the attitude angle is dynamically adjusted through exponential decay and smooth transition functions to compensate for the influence of aerodynamic disturbances on the attitude angle solution. The formula of the attitude angle dynamic correction term is:

[0021]

[0022] Where: β 1 is the correction amplitude adjustment factor.

[0023] As a further solution of the present invention, in the formula of the dynamic correction term of the attitude angle, when the flight target angle of attack is greater than 15°, the value range of the square of the coordination coefficient of the angle of attack is [10, 20], and when the flight target angle of attack is less than 15°, the value range of the square of the coordination coefficient of the angle of attack is [2, 5].

[0024] As a further solution of the present invention, the process of dynamically correcting the initial attitude angle by the Kalman filter algorithm to obtain the final corrected attitude angle of the flying target includes the following steps:

[0025] Step 21, initializing states and parameters: obtaining preliminary azimuth, preliminary pitch angle and preliminary roll angle through correction formula of Mach number correction function and attitude angle dynamic correction term, initializing error covariance matrix, state transfer matrix, process noise covariance matrix, measurement noise covariance matrix and measurement matrix;

[0026] Step 22, state prediction: predict the attitude angle at the current moment based on the attitude angle at the previous moment, and update the prediction error covariance matrix at the same time;

[0027] Step 23, Kalman gain calculation: Calculate the Kalman gain at the current moment based on the Kalman gain formula;

[0028] Step 24, state update: correct the predicted attitude angle by combining the measured value and the Kalman gain;

[0029] Step 25, error covariance update: update the corrected attitude angle error covariance according to the error covariance update formula;

[0030] Step 26, repeat until convergence: Repeat steps 22 to 25 until the preset convergence condition is reached, and obtain the final corrected attitude angle of the flight target.

[0031] Compared with the prior art, the technical effects and advantages of the method proposed in the present invention are as follows: by introducing a Mach number correction function, the present invention can generate a simulation image template that is more in line with actual aerodynamic characteristics for a flight state where the Mach number is greater than 1, thereby reducing the matching error between the simulation image and the real image, and can effectively compensate for the aerodynamic disturbance caused by the shock wave effect and the airflow separation, so that the attitude angle solution is more accurate; the attitude angle dynamic correction term is based on the real-time attitude angle and Mach number changes, and can dynamically adjust the attitude angle solution process, especially when the angle of attack is greater than 15°, the term can quickly respond to the rapid changes in the attitude of the flying target, and ensure that the system can adapt to the drastic fluctuations of the attitude angle; by fusing the similarity of multi-station measurements, the measurement accuracy is improved, the calculation burden is reduced, and the system can achieve stable measurement in a more complex aerodynamic environment, thereby improving the imaging quality of the photoelectric theodolite and the stability of the attitude angle solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Simulated binary images of the flight target corresponding to different attitude parameters of the present invention;

[0033] Figure 2A comparison diagram of the real image of the flying target and the real binary image of the target in the present invention;

[0034] Figure 3 It is a simulation model diagram of a certain type of missile of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0036] like Figures 1 to 3 As shown, a method for measuring the attitude of a flying target based on a simulation imaging matching algorithm proposed by the present invention is an improvement on a method for obtaining the attitude angle measurement value of a flying target based on a simulation image matching algorithm. This method obtains a real image by measuring with an optoelectronic theodolite, establishes a spatial model by the shape parameters of the flying target, constructs a numerical simulation environment, obtains a simulation image sequence, compares the similarity between the real image and the simulation image, and then performs attitude angle solution to obtain the azimuth, pitch angle and roll angle of the flying target, and obtains the fusion similarity of multi-station measurements by multi-station similarity fusion to solve the attitude angle of the flying target. The improved method proposed by the present invention first obtains the current Mach number by the flying speed of the flying target and the local speed of sound, and then generates and selects a simulation image template corresponding to the current Mach number according to the Mach number, solves the initial attitude angle of the flying target based on the simulation image matching algorithm, adjusts the initial attitude angle using a Mach number correction function and a dynamic adjustment item of the flight attitude, adjusts the dynamic adjustment item of the flight attitude according to the Mach number and the angle of attack, and dynamically corrects the initial attitude angle by a Kalman filter algorithm to obtain the final corrected attitude angle of the flying target.

[0037] It should be noted that the simulation image template corresponding to the current Mach number is generated and selected according to the Mach number. The constructed simulation image library is generated by computational fluid dynamics simulation software according to the set Mach number, azimuth, pitch angle and roll angle. When there is no matching Mach number in the simulation image, the simulation image templates corresponding to the two adjacent Mach numbers of the Mach number that needs to be matched are linearly interpolated to obtain the simulation image of the current Mach number. The azimuth, pitch angle and roll angle corresponding to the simulation image of the current Mach number are obtained by linear interpolation. The formula for obtaining the simulation image template of the current Mach number is:

[0038]

[0039] Where: M is the current Mach number, which is equal to the ratio of the measured speed of the flight target to the arithmetic square root of the product of the specific heat capacity of the air, the gas constant of the air, and the current ambient temperature; B(M) is the simulation image template corresponding to the current Mach number; M 1 、M 2 is the first Mach number and the second Mach number adjacent to the current Mach number in the Mach number set for simulation, M 2 >M 1 ,B(M 1 )、B(M 2 ) are the simulation image templates corresponding to the first Mach number and the second Mach number respectively.

[0040] By generating and selecting the simulation image template corresponding to the current Mach number according to the Mach number, and performing linear interpolation when there is no matching Mach number in the simulation image library, it is possible to dynamically adapt to the real-time flight conditions of the flight target and achieve high-precision matching of attitude measurement. Under different Mach numbers, the aerodynamic characteristics of the flight target will change significantly, and the images generated by the simulation image library based on fluid mechanics simulation software can accurately reflect these changes. When the actual flight Mach number is between the preset Mach numbers in the simulation library, the linear interpolation method generates a simulation image template that approximates the current Mach number by interpolating adjacent Mach number templates, ensuring the accuracy and continuity of attitude angle solution, avoiding the error caused by direct reliance on discrete Mach number simulation images, and effectively improving the real-time and accuracy of attitude angle solution, especially when the Mach number is in a non-preset range, the simulation image template can be dynamically adjusted to ensure the stability and accuracy of attitude measurement.

[0041] It should be noted that the process of calculating the initial value of the flight target attitude angle based on the simulation image matching algorithm includes:

[0042] Step 11, obtaining a real image and a simulated image: obtaining a real image of the flight target at the calculation time through an optoelectronic theodolite, selecting a simulated image template with the smallest difference with the current Mach number from a simulated image library according to the shape parameters of the flight target and the current Mach number, and when there is no matching simulated image template, obtaining the current Mach number simulated image template through a formula of the current Mach number simulated image template, and the space attitude angle corresponding to the current Mach number simulation template, and extracting the contour features of the flight target in the current real image and the simulated image template;

[0043] Step 12, search for the maximum similarity and obtain the initial attitude angle: take the azimuth, pitch angle and roll angle as variables respectively, gradually change the three variables in the simulated image, generate simulated images under different attitude angles, binarize the real image and the simulated image template, traverse the azimuth, pitch angle and roll angle of the simulated image within the set range of the initial attitude angle, compare each frame of the simulated image with the current real image one by one, calculate the similarity between the real image and the binary image of the simulated image, and record their attitude angles, search for the maximum value of the similarity, and obtain the initial value of the attitude angle of the flying target.

[0044] When performing the above steps, it is necessary to ensure that the acquisition time of the real image and the simulated image is highly synchronized to avoid matching errors caused by changes in the target attitude. High-resolution and high-quality images are helpful to extract contour features more accurately and reduce the impact of noise on the matching results. When selecting the simulated image template with the smallest difference from the current Mach number, a reasonable difference range needs to be set to avoid inaccurate matching caused by excessive difference. When there is no matching simulated image template, the current Mach number target image template is generated by formula. The accuracy and applicability of the formula need to be ensured to maintain the reliability of matching. The target contour feature extraction should be able to cope with the interference of different lighting, perspective changes and target surface texture, to ensure that the extracted features have consistency and recognition. The binarization process needs to select a threshold that adapts to the actual situation to avoid information loss or noise introduction, thereby affecting the subsequent similarity calculation. By matching the real image with the simulated image, the initial attitude angle of the flying target can be estimated more accurately, providing a reliable starting point for the subsequent attitude solution and reducing the error accumulation in the iterative process. This method can dynamically select or generate appropriate simulated image templates according to different Mach numbers and flight target shape parameters. It has strong adaptability and is suitable for a variety of flight states and environmental conditions. Relying on the image information obtained by the photoelectric theodolite to estimate the attitude angle, it reduces the dependence on other complex sensors and reduces the complexity and cost of the system. The optimized image matching algorithm can achieve real-time or near real-time initial value solution of the attitude angle to meet the tracking requirements of rapidly changing flying targets.

[0045] It should be noted that the correction formula for adjusting the initial attitude angle using the Mach number correction function and the attitude angle dynamic correction term is:

[0046] θ final =θ initial +f(M)·Δθ+g(θ 1 ,θ 2 ,θ 3 ,σ,M)

[0047] Where: θ finalis the corrected attitude angle, including the corrected azimuth angle, the corrected pitch angle and the corrected roll angle, f(M) is the Mach number correction function, Δθ is the correction amount of the attitude angle, θ 1 ,θ 2 ,θ 3 are the initial values ​​of azimuth, pitch and roll angles, σ is the angle of attack coordination coefficient, g(θ 1 ,θ 2 ,θ 3 ,σ,M) is the dynamic correction term of attitude angle.

[0048] The specific values ​​of the aerodynamic change characteristics of the flight target at different Mach numbers are shown in Table 1:

[0049] Table 1

[0050] Mach number Lift coefficient Drag coefficient Pitch moment coefficient Critical Mach number 0.3 1.2 0.05 0.1 0.6 0.8 1.1 0.07 0.2 0.6 2.0 0.8 0.15 0.5 0.6

[0051] It can be seen from Table 1 that the aerodynamic characteristics of the flight target change significantly with the Mach number, which puts higher requirements on the initial value calculation of the attitude angle and the formulation of subsequent control strategies to achieve the best aerodynamic performance and flight control effect.

[0052] By using the Mach number correction function and the attitude angle dynamic correction term to adjust the initial attitude angle, the problem of insufficient attitude angle solution accuracy under different flight conditions can be effectively solved. Since the aerodynamic characteristics of the flying target change significantly at different Mach numbers, it is difficult for traditional attitude angle solution methods to accurately capture these changes. By introducing the Mach number correction function f(M), the attitude angle can be corrected linearly, quadratically, and exponentially according to the current Mach number, accurately reflecting the aerodynamic disturbance effects at supersonic and hypersonic speeds, and improving the correction accuracy of the attitude angle. The attitude angle dynamic correction term g(θ 1 ,θ 2 ,θ 3 ,σ,M) takes into account the complex relationship between the initial values ​​of the azimuth, pitch and roll angles and the Mach number, especially under high angle of attack conditions (angle of attack greater than 15°), and compensates for the attitude angle changes caused by aerodynamic disturbances through exponential decay and smooth transition functions. This formula ensures the real-time and dynamic adaptability of attitude angle correction, thereby maintaining high-precision attitude angle solution under different Mach numbers and flight conditions, effectively improving the overall reliability and accuracy of flight attitude measurement.

[0053] It should be noted that the Mach number correction function performs a comprehensive correction of the attitude angle based on the Mach number using linear correction terms, quadratic correction terms, and exponential change correction terms. The formula of the Mach number correction function is:

[0054] f(M)=1+α 1 (M-1)+α 2 (M-1) 2+α 3 exp(-λ(M-1))

[0055] Where: α 1 , α 2 , α 3 is the constant coefficient fitted according to the experimental data, and λ is the influencing adjustment factor.

[0056] The Mach number correction function combines linear, quadratic and exponential change correction terms to comprehensively correct the attitude angle according to the changes in aerodynamic characteristics within different speeds of sound, thereby effectively solving the problem of low accuracy in attitude angle measurement at different flight speeds. When the speed is lower than the speed of sound, the aerodynamic characteristics are relatively stable, the aerodynamic disturbance is small, and the linear correction term α 1 (M-1) can handle the deviation of attitude angle and ensure that the calculation accuracy of attitude angle of the flying target at low speed remains at the required level. When the flying target is at transonic speed, the aerodynamic effect becomes complicated, and shock waves and airflow separation begin to appear. The secondary correction term α 2 (M-1) 2 It is used to process this nonlinear change and ensure that the attitude angle calculation error in the transonic region is effectively controlled. In the supersonic range, the shock wave effect and aerodynamic disturbance are further enhanced, and the secondary correction term can further compensate for the complex aerodynamic effects of supersonic speed. At the same time, the exponential change correction term α 3 exp(-λ(M-1)) gradually reduces the correction amplitude when the Mach number is greater than 1, reflecting the fact that the aerodynamic effect tends to be stable under hypersonic conditions and avoiding excessive correction.

[0057] It should be noted that in the correction formula for adjusting the preliminary attitude angle using the Mach number correction function, when the resolution of the photoelectric theodolite is 1024×768 pixels, the frame rate is 30 frames per second, the azimuth angle measurement accuracy is 0.1°, the pitch angle measurement accuracy is 0.15°, the roll angle measurement accuracy is 0.2°, and the simulation image attitude angle generation accuracy is 0.05°, the correction amounts of the azimuth angle, pitch angle, and roll angle are 0.05°, 0.1°, and 0.15°, respectively.

[0058] The above are the specific application scope and setting conditions of the present invention. These limiting conditions ensure that under specific photoelectric theodolite parameters, the Mach number correction function can fully play its role, provide high-precision attitude angle correction, and ensure the reliability and accuracy of flight attitude measurement.

[0059] When the angle of attack is greater than 15°, the flying target enters the critical angle of attack region, the fluid separation effect begins to appear, the aerodynamic disturbance increases, the aerodynamic characteristics of the flying target become nonlinear, the attitude angle changes more dramatically, and sensitive correction is required. An appropriate angle of attack coordination coefficient is set so that the photoelectric theodolite and the attitude angle correction method proposed by the present invention can respond to the attitude angle change more quickly, increase the weight of the attitude angle dynamic correction term, and make the correction process more timely and accurate, especially under the shock wave effect and airflow separation, to ensure the accuracy of the attitude angle solution. When the angle of attack is less than or equal to 15°, an appropriate angle of attack coordination coefficient is set to make the attitude angle correction process smoother, reduce the weight of the attitude angle dynamic correction term, and consider the influence of the Mach number at the same time. When the Mach number is less than or equal to 1, the attitude angle dynamic correction term is less than or equal to 1, and at the same time, the change of the attitude angle is not as dramatic as when the angle of attack is greater than 15°, and the overall attitude angle dynamic correction term gradually tends to 0.

[0060] It should be noted that in the correction formula for adjusting the preliminary attitude angle using the Mach number correction function, the attitude angle dynamic correction term is based on the changes in the Mach number, attitude angle and angle of attack. The attitude angle is dynamically adjusted through exponential decay and smooth transition functions to compensate for the influence of aerodynamic disturbances on the attitude angle solution. The formula for the attitude angle dynamic correction term is:

[0061]

[0062] Where: β 1 is the correction amplitude adjustment factor.

[0063] It should be noted that in the formula of the dynamic correction term of the attitude angle, when the flight target angle of attack is greater than 15°, the value range of the square of the coordination coefficient of the angle of attack is [10, 20], and when the flight target angle of attack is less than 15°, the value range of the square of the coordination coefficient of the angle of attack is [2, 5].

[0064] In the formula of the attitude angle dynamic correction term, the value range of the square of the angle of attack coordination coefficient is based on the changes in the aerodynamic characteristics of the flight target at different angles of attack. When the angle of attack is greater than 15°, the flight target enters the critical angle of attack and the aerodynamic disturbance is severe. Therefore, the square of the coordination coefficient is set to ([10,20]) to more sensitively capture the rapid changes in the attitude angle. When the angle of attack is less than 15°, the flight target is in a relatively stable aerodynamic state and the airflow separation effect is small. The square of the coordination coefficient is set to ([2,5]) to ensure a smooth correction process. The data range is limited based on the results of wind tunnel tests, aerodynamic simulations, and actual flight experience to ensure the accuracy and stability of the system's attitude angle correction under different angles of attack, which is consistent with the aerodynamic response of the actual flight target.

[0065] It should be noted that the process of dynamically correcting the initial attitude angle through the Kalman filter algorithm to obtain the final corrected attitude angle of the flying target includes the following steps:

[0066] Step 21, initializing states and parameters: obtaining preliminary azimuth, preliminary pitch angle and preliminary roll angle through correction formula of Mach number correction function and attitude angle dynamic correction term, initializing error covariance matrix, state transfer matrix, process noise covariance matrix, measurement noise covariance matrix and measurement matrix;

[0067] Step 22, state prediction: predict the attitude angle at the current moment based on the attitude angle at the previous moment, and update the prediction error covariance matrix at the same time;

[0068] Step 23, Kalman gain calculation: Calculate the Kalman gain at the current moment based on the Kalman gain formula;

[0069] Step 24, state update: correct the predicted attitude angle by combining the measured value and the Kalman gain;

[0070] Step 25, error covariance update: update the corrected attitude angle error covariance according to the error covariance update formula;

[0071] Step 26, repeat until convergence: Repeat steps 22 to 25 until the preset convergence condition is reached, and obtain the final corrected attitude angle of the flight target.

[0072] Example

[0073] In order to clearly illustrate the progress of the method proposed in the present invention, an example is given to illustrate that in a certain type of missile test, for a target with an imaging length of 180 pixels and a width of 30 pixels, the measurement results of the attitude angle are compared with the attitude angle results measured by the inertial navigation pitch angle measurement method and the central axis method, and the advantages of the method proposed in the present invention are shown.

[0074] The inertial navigation (INS) pitch angle measurement method measures the pitch angle of the flying target through the gyroscope and accelerometer in the inertial measurement unit (IMU). The INS system can sense the rotational motion and linear acceleration of the flying target, and obtain the attitude angle of the flying target at different time points by integrating the acceleration and angular velocity. Measurement principle: The gyroscope detects the angular velocity of the flying target, while the accelerometer senses the direction of gravity. Combining the data of these two sensors, the attitude angle of the flying target, including the pitch angle, is obtained by integration calculation. Features: The INS pitch angle measurement method does not rely on external reference signals and is suitable for long-term autonomous flight. However, due to the drift error of the INS system, the measurement results will accumulate errors over time, so regular correction is required.

[0075] The central axis method is a method of measuring the attitude angle by the angle between the geometric axis (i.e., longitudinal axis) of the flying target and the horizontal plane. It determines the pitch angle by observing the angle difference between the flying target and the horizontal reference through visual or optical equipment, such as photoelectric theodolites. Measurement principle: The pitch angle is determined by measuring the angle between the longitudinal axis (central axis) of the flying target and the ground reference plane. This can be done by external observation equipment, such as optical instruments or laser rangefinders, to accurately calculate the attitude angle. Features: The central axis method has high accuracy, especially under stable external observation conditions, and is suitable for real-time monitoring of attitude changes of flying targets, but requires external reference objects and equipment support.

[0076] As shown in Table 2 below, the attitude angle measurement result data of the method proposed in the basic invention in single-station and dual-station measurements, the attitude angle measurement data of the inertial navigation pitch angle measurement method and the central axis method are compared, and the measurement errors are calculated.

[0077] Table 2

[0078]

[0079]

[0080] Through actual verification, the method proposed by the present invention is superior to the central axis method measurement. The calculation accuracy of the present invention in the two-station fusion measurement is higher than the accuracy of single-station measurement.

[0081] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0082] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for measuring the attitude of a flying target based on a simulation imaging matching algorithm, which obtains a real image by measuring with an optoelectronic theodolite, establishes a spatial model by using the shape parameters of the flying target, constructs a numerical simulation environment, obtains a simulation image sequence, compares the similarity between the real image and the simulation image, and then performs attitude angle calculation to obtain the azimuth, pitch angle and roll angle of the flying target, obtains the fusion similarity of multi-station measurements by multi-station similarity fusion, and calculates the attitude angle of the flying target, characterized in that: The current Mach number is obtained through the flight speed of the flying target and the local speed of sound, a simulation image template corresponding to the current Mach number is generated and selected according to the Mach number, the initial attitude angle of the flying target is solved based on the simulation image matching algorithm, the initial attitude angle is adjusted using the Mach number correction function and the flight attitude dynamic adjustment item, the flight attitude dynamic adjustment item is adjusted according to the Mach number and the angle of attack, the initial attitude angle is dynamically corrected through the Kalman filter algorithm, and the final corrected attitude angle of the flying target is obtained.

2. A method for measuring a flying target attitude based on a simulation imaging matching algorithm according to claim 1, characterized in that: Generate and select a simulation image template corresponding to the current Mach number according to the Mach number. The constructed simulation image library is generated by computational fluid dynamics simulation software according to the set Mach number, azimuth, pitch angle and roll angle. When there is no matching Mach number in the simulation image, linear interpolation is performed on the simulation image templates corresponding to the two adjacent Mach numbers of the Mach number that needs to be matched to obtain the simulation image of the current Mach number. The azimuth, pitch angle and roll angle corresponding to the simulation image of the current Mach number are obtained by linear interpolation. The formula for obtaining the simulation image template of the current Mach number is: Where: M is the current Mach number, which is equal to the ratio of the measured speed of the flight target to the arithmetic square root of the product of the specific heat capacity of the air, the gas constant of the air, and the current ambient temperature; B(M) is the simulation image template corresponding to the current Mach number; M1 and M2 are the first Mach number and the second Mach number adjacent to the current Mach number in the Mach number set for simulation; M2>M1; B(M1) and B(M2) are the simulation image templates corresponding to the first Mach number and the second Mach number, respectively.

3. The method for measuring the attitude of a flying target based on a simulation imaging matching algorithm according to claim 1, characterized in that: The process of solving the initial value of the flight target attitude angle based on the simulation image matching algorithm includes: Step 11, obtaining a real image and a simulated image: obtaining a real image of the flight target at the calculation time through an optoelectronic theodolite, selecting a simulated image template with the smallest difference with the current Mach number from a simulated image library according to the shape parameters of the flight target and the current Mach number, and when there is no matching simulated image template, obtaining the current Mach number simulated image template through a formula of the current Mach number simulated image template, and the space attitude angle corresponding to the current Mach number simulation template, and extracting the contour features of the flight target in the current real image and the simulated image template; Step 12, search for the maximum similarity and obtain the initial attitude angle: take the azimuth, pitch angle and roll angle as variables respectively, gradually change the three variables in the simulated image, generate simulated images under different attitude angles, binarize the real image and the simulated image template, traverse the azimuth, pitch angle and roll angle of the simulated image within the set range of the initial attitude angle, compare each frame of the simulated image with the current real image one by one, calculate the similarity between the real image and the binary image of the simulated image, and record their attitude angles, search for the maximum value of the similarity, and obtain the initial value of the attitude angle of the flying target.

4. The method for measuring the attitude of a flying target based on a simulation imaging matching algorithm according to claim 3, characterized in that: The correction formula for adjusting the initial attitude angle using the Mach number correction function and the attitude angle dynamic correction term is: i final =θ initial +f(M)·Δθ+g(θ1,θ2,θ3,σ,M) Where: θ final is the corrected attitude angle, including the corrected azimuth angle, corrected pitch angle and corrected roll angle, f(M) is the Mach number correction function, Δθ is the correction amount of the attitude angle, θ1, θ2, θ3 are the initial values ​​of the azimuth angle, the pitch angle and the roll angle respectively, σ is the angle of attack coordination coefficient, and g(θ1,θ2,θ3,σ,M) is the dynamic correction term of the attitude angle.

5. The method for measuring the attitude of a flying target based on a simulation imaging matching algorithm according to claim 4, characterized in that: The Mach number correction function performs a comprehensive correction of the attitude angle using linear correction terms, quadratic correction terms, and exponential change correction terms based on the Mach number. The formula of the Mach number correction function is: f(M)=1+α1(M-1)+α2(M-1) 2 +α3exp(-λ(M-1)) Where: α1, α2, α3 are constant coefficients fitted according to the experimental data, and λ is the influencing adjustment factor.

6. The method for measuring the attitude of a flying target based on a simulation imaging matching algorithm according to claim 4, characterized in that: In the correction formula for adjusting the preliminary attitude angle using the Mach number correction function, when the resolution of the photoelectric theodolite is 1024×768 pixels, the frame rate is 30 frames per second, the azimuth angle measurement accuracy is 0.1°, the pitch angle measurement accuracy is 0.15°, the roll angle measurement accuracy is 0.2°, and the simulation image attitude angle generation accuracy is 0.05°, the correction amounts of the azimuth angle, pitch angle, and roll angle are 0.05°, 0.1°, and 0.15°, respectively.

7. The method for measuring the attitude of a flying target based on a simulation imaging matching algorithm according to claim 4, characterized in that: In the correction formula for adjusting the preliminary attitude angle using the Mach number correction function, the attitude angle dynamic correction term is based on the changes in the Mach number, attitude angle and angle of attack. The attitude angle is dynamically adjusted through exponential decay and smooth transition functions to compensate for the influence of aerodynamic disturbances on the attitude angle solution. The formula for the attitude angle dynamic correction term is: Where: β1 is the correction amplitude adjustment coefficient.

8. The method for measuring the attitude of a flying target based on a simulation imaging matching algorithm according to claim 7, characterized in that: In the formula of the attitude angle dynamic correction term, when the flight target angle of attack is greater than 15°, the value range of the square of the angle of attack coordination coefficient is [10, 20], and when the flight target angle of attack is less than 15°, the value range of the square of the angle of attack coordination coefficient is [2, 5].

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