A method for measuring the attitude of a flight target based on a simulation imaging matching algorithm

Abstract

This invention relates to the field of image processing technology, specifically disclosing a flight target attitude measurement method based on a simulation imaging matching algorithm. This method addresses the problems of attitude angle calculation errors and decreased measurement accuracy caused by shock wave effects and aerodynamic disturbances during the attitude measurement of supersonic flight targets. The method calculates the Mach number based on the flight speed and local speed of sound, generates and selects a corresponding simulation image template, uses a simulation image matching algorithm to calculate the initial attitude angle, corrects the initial attitude angle using a Mach number correction function and a dynamic attitude adjustment term, and finally uses Kalman filtering for dynamic correction to obtain the final accurate attitude angle. This invention significantly improves the accuracy and real-time performance of attitude angle measurement under supersonic flight conditions through the Mach number correction function and dynamic attitude angle correction term, especially ensuring the stability and computational efficiency of attitude angle measurement under shock wave effects and rapid attitude changes.

Description

Technical Field

[0001] This invention relates to the field of image processing technology, and more specifically, to a method for measuring the attitude of a flight target based on a simulation imaging matching algorithm. Background Technology

[0002] In flight target attitude measurement, space target attitude measurement based on simulation imaging matching algorithms calculates the flight target's attitude angle by comparing the similarity between real and simulated images. In actual range testing, Mach number affects the flight target's aerodynamic characteristics, imaging quality, and attitude measurement accuracy. When the Mach number is greater than 1, shock waves are generated around the flight target, causing airflow to separate from the target surface, altering the target's aerodynamic shape and complicating its outline. Simultaneously, friction between the target surface and the surrounding air leads to increased surface temperature; the infrared radiation generated by this high temperature interferes with the normal measurement of the photoelectric theodolite, resulting in reduced image clarity. The descent affects the accuracy of attitude calculation. Simulation images generated based on the target in a static state or at a Mach number less than 0.8 will deviate from the actual target image contour due to aerodynamic effects when the Mach number is greater than 1. Simulation images with a Mach number greater than 1 require the generation of multiple simulation image templates and continuous adjustment of simulation results during real-time measurements. Especially in the case of multi-station measurements, the computational burden on the system 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 will change rapidly, which will increase the difficulty of attitude measurement. The randomness and intensity variation of aerodynamic disturbances cause the measurement response speed of the photoelectric theodolite to be insufficient and unable to adapt to the rapid changes in the target attitude. Summary of the Invention

[0003] To overcome the aforementioned deficiencies of the prior art, this invention provides a flight target attitude measurement method based on a simulation imaging matching algorithm. By using a Mach number correction function and a dynamic attitude angle correction term, the accuracy and real-time performance of attitude angle measurement under supersonic flight conditions are improved. In particular, under shock wave effects and rapid attitude changes, the method ensures measurement stability and improves calculation speed.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for measuring the attitude of a flight target based on a simulation imaging matching algorithm is proposed. This method obtains real images using an optoelectronic theodolite, establishes a spatial model based on the target's shape parameters, constructs a numerical simulation environment, acquires a sequence of simulated images, compares the similarity between real and simulated images, and then calculates the azimuth, pitch, and roll angles of the flight target. Multi-station similarity fusion is used to obtain the fusion similarity of the measurements from multiple stations, and the flight target's attitude angles are calculated. The current Mach number is obtained from the target's flight speed and the local speed of sound. A simulated image template corresponding to the current Mach number is generated and selected. The initial attitude angles of the flight target are calculated based on the simulated image matching algorithm. The initial attitude angles are adjusted using a Mach number correction function and a dynamic flight attitude adjustment term. The dynamic flight attitude adjustment term is further adjusted based on the Mach number and angle of attack. Finally, the initial attitude angles are dynamically corrected using a Kalman filter algorithm to obtain the final corrected attitude angles of the flight target.

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

[0007]

[0008] In the formula: M is the current Mach number, which is equal to the ratio of the measured velocity of the flight target to the 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 and second Mach numbers adjacent to the current Mach number in the simulation settings, M2>M1; and B(M1) and B(M2) are the simulation image templates corresponding to the first and second Mach numbers, respectively.

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

[0010] Step 11, acquire real and simulated images: acquire real images of the flight target at the time of calculation using an optoelectronic theodolite; select the simulated image template with the smallest difference from the current Mach number from the simulated image library based on the shape parameters of the flight target and the current Mach number; if there is no matching simulated image template, obtain the current Mach number simulated image template and the corresponding spatial attitude angle using the formula of the current Mach number simulated image template; and extract the contour features of the flight target from the current real image and simulated image template.

[0011] Step 12, search for maximum similarity and obtain initial attitude angles: Using azimuth, pitch, and roll angles as variables, gradually change these three variables in the simulation image to generate simulation images under different attitude angles. Binarize the real image and the simulation image template. Within the initial attitude angle setting range, traverse the azimuth, pitch, and roll angles of the simulation image. Compare each frame of the simulation image with the current real image one by one, calculate the similarity between the real image and the binarized simulation image, and record their attitude angles. Search for the maximum similarity to obtain the initial attitude angle value of the flight target.

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

[0013] θ final =θ initial +f(M)·Δθ+g(θ1,θ2,θ3,σ,M)

[0014] In the formula: θ final The corrected attitude angles include the corrected azimuth, pitch, and roll angles. f(M) is the Mach number correction function, Δθ is the attitude angle correction amount, θ1, θ2, and θ3 are the initial values ​​of the azimuth, pitch, and roll angles, respectively, σ is the angle of attack coordination coefficient, and g(θ1,θ2,θ3,σ,M) is the attitude angle dynamic correction term.

[0015] As a further aspect of this invention, the Mach number correction function performs a comprehensive correction of the attitude angle based on the Mach number, including linear correction terms, quadratic correction terms, and exponential change correction terms. The formula for the Mach number correction function is as follows:

[0016] f(M) = 1 + α1(M-1) + α2(M-1) 2 +α3exp(-λ(M-1))

[0017] In the formula: α1, α2, and α3 are constant coefficients fitted based on experimental data, and λ is the influence adjustment factor.

[0018] As a further aspect of the present invention, in the correction formula for adjusting the initial 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 measurement accuracy is 0.1°, the pitch measurement accuracy is 0.15°, the roll measurement accuracy is 0.2°, and the simulation image attitude angle generation accuracy is 0.05°, the correction amounts for the azimuth, pitch, and roll angles are 0.05°, 0.1°, and 0.15°, respectively.

[0019] When the angle of attack is greater than 15°, the flight target enters the critical angle of attack region, the fluid separation effect begins to appear, aerodynamic disturbances increase, the aerodynamic characteristics of the flight target become nonlinear, and the attitude angle changes more drastically, requiring sensitive correction. An appropriate angle of attack coordination coefficient is set to enable the photoelectric theodolite and the attitude angle correction method proposed in this invention to respond more quickly to attitude angle changes, increasing the weight of the dynamic attitude angle correction term, making the correction process more timely and accurate, especially under the effects of shock waves and airflow separation, ensuring the accuracy of attitude angle calculation. 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, reducing the weight of the dynamic attitude angle correction term. Simultaneously, considering the influence of Mach number, when the Mach number is less than or equal to 1, the dynamic attitude angle correction term is less than or equal to 1, while the change in attitude angle is not as drastic as when the angle of attack is greater than 15°, and the overall dynamic attitude angle correction term gradually approaches 0.

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

[0021]

[0022] In the formula: β1 is the adjustment coefficient for the correction amplitude.

[0023] As a further aspect of the present invention, in the formula for the dynamic correction term of the attitude angle, when the angle of attack of the flight target 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 angle of attack of the flight target 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 aspect of the present invention, the process of dynamically correcting the initial attitude angle using the Kalman filter algorithm to obtain the final corrected attitude angle of the flight target includes the following steps:

[0025] Step 21, Initialize state and parameters: Obtain the initial azimuth angle, initial pitch angle and initial roll angle through the correction formula of Mach number correction function and attitude angle dynamic correction term, and initialize error covariance matrix, state transition 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 time based on the Kalman gain formula;

[0028] Step 24, State Update: Correct the predicted attitude angle by combining the measured values ​​and Kalman gain;

[0029] Step 25, Error Covariance Update: Update the attitude angle error covariance after correction according to the error covariance update formula;

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

[0031] Compared to existing technologies, the technical effects and advantages of the proposed method are as follows: By introducing a Mach number correction function, this invention can generate simulation image templates that better reflect actual aerodynamic characteristics for flight states with Mach numbers greater than 1. This reduces the matching error between simulation and real images, effectively compensates for aerodynamic disturbances caused by shock wave effects and airflow separation, and makes attitude angle calculations more accurate. The dynamic attitude angle correction term, based on real-time changes in attitude angle and Mach number, can dynamically adjust the attitude angle calculation process. Especially when the angle of attack is greater than 15°, this term can quickly respond to rapid changes in the flight target's attitude, ensuring that the system can adapt to drastic fluctuations in attitude angle. By using multi-station measurement fusion similarity, the measurement accuracy is improved, the computational burden is reduced, and the system can achieve stable measurements in more complex aerodynamic environments, thus improving the imaging quality and stability of the photoelectric theodolite's attitude angle calculations. Attached Figure Description

[0032] Figure 1 These are simulated binary images of the flight target corresponding to different attitude parameters in this invention;

[0033] Figure 2 This is a comparison image of the actual flight target and the actual binary image of the target in this invention;

[0034] Figure 3 This is a simulation model diagram of a certain type of missile of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] like Figures 1 to 3 As shown, the present invention proposes an improved method for measuring the attitude of a flight target based on a simulation imaging matching algorithm. This method improves upon the previous method of obtaining flight target attitude angle measurements using a simulation image matching algorithm. The previous method used an optoelectronic theodolite to obtain real images, established a spatial model based on the flight target's shape parameters, constructed a numerical simulation environment, obtained a sequence of simulation images, compared the similarity between real and simulation images, and then calculated the azimuth, pitch, and roll angles of the flight target. Furthermore, it used multi-station similarity fusion to obtain the fusion similarity of multi-station measurements and calculated the flight target attitude angles. The improved method proposed in this invention first obtains the current Mach number based on the flight target's speed and the local speed of sound. Then, it generates and selects a simulation image template corresponding to the current Mach number, calculates the initial attitude angles of the flight target based on the simulation image matching algorithm, adjusts the initial attitude angles using a Mach number correction function and a dynamic flight attitude adjustment term, adjusts the dynamic flight attitude adjustment term based on the Mach number and angle of attack, and dynamically corrects the initial attitude angles using a Kalman filter algorithm to obtain the final corrected attitude angles of the flight target.

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

[0038]

[0039] In the formula: M is the current Mach number, which is equal to the ratio of the measured velocity of the flight target to the 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 and second Mach numbers adjacent to the current Mach number in the simulation settings, M2>M1; and B(M1) and B(M2) are the simulation image templates corresponding to the first and second Mach numbers, respectively.

[0040] By generating and selecting a simulation image template corresponding to the current Mach number, and performing linear interpolation when no matching Mach number is found in the simulation image library, the system can dynamically adapt to the real-time flight conditions of the target, achieving high-precision matching for attitude measurement. At different Mach numbers, the aerodynamic characteristics of the target change significantly, and the images generated by the simulation image library based on fluid dynamics simulation software accurately reflect these changes. When the actual flight Mach number falls within the preset Mach numbers in the simulation library, the linear interpolation method generates a simulation image template that approximates the current Mach number through interpolation of adjacent Mach number templates. This ensures the accuracy and continuity of attitude angle calculation, avoids errors caused by directly relying on discrete Mach number simulation images, and effectively improves the real-time performance and accuracy of attitude angle calculation. Especially when the Mach number is outside the preset range, the system can dynamically adjust the simulation image template, ensuring the stability and accuracy of attitude measurement.

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

[0042] Step 11, acquire real and simulated images: acquire real images of the flight target at the time of calculation using an optoelectronic theodolite, select the simulated image template with the smallest difference from the current Mach number from the simulated image library based on the shape parameters of the flight target and the current Mach number, if there is no matching simulated image template, obtain the current Mach number simulated image template and the corresponding spatial attitude angle of the current Mach number simulated image template through the formula of the current Mach number simulated image template, and extract the contour features of the flight target in the current real image and simulated image template;

[0043] Step 12, search for maximum similarity and obtain initial attitude angles: Using azimuth, pitch, and roll angles as variables, gradually change these three variables in the simulation image to generate simulation images under different attitude angles. Binarize the real image and the simulation image template. Within the initial attitude angle setting range, traverse the azimuth, pitch, and roll angles of the simulation image. Compare each frame of the simulation image with the current real image one by one, calculate the similarity between the real image and the binarized simulation image, and record their attitude angles. Search for the maximum similarity to obtain the initial attitude angle value of the flight 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 target attitude. High-resolution and high-quality images help 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 due to excessive difference. When there is no matching simulated image template, the target image template for the current Mach number is generated by formula. It is necessary to ensure the accuracy and applicability of the formula to maintain the reliability of the matching. The target contour feature extraction should be able to cope with the interference of different lighting, viewing angle changes and target surface textures to ensure that the extracted features have consistency and recognizability. The binarization process needs to select an appropriate threshold to avoid information loss or noise introduction, which would affect subsequent similarity calculations. By matching the real image and the simulated image, the initial attitude angle of the flying target can be estimated more accurately, providing a reliable starting point for subsequent attitude calculations and reducing error accumulation during the iteration process. This method can dynamically select or generate suitable simulated image templates according to different Mach numbers and flying target shape parameters, making it highly adaptable and applicable to various flight states and environmental conditions. Attitude angle estimation is performed using image information acquired by an electro-optical theodolite, reducing reliance on other complex sensors and lowering system complexity and cost. An optimized image matching algorithm enables real-time or near-real-time initial attitude angle calculation, meeting 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 as follows:

[0046] θ final =θ initial +f(M)·Δθ+g(θ1,θ2,θ3,σ,M)

[0047] In the formula: θ final The corrected attitude angles include the corrected azimuth, pitch, and roll angles. f(M) is the Mach number correction function, Δθ is the attitude angle correction amount, θ1, θ2, and θ3 are the initial values ​​of the azimuth, pitch, and roll angles, respectively, σ is the angle of attack coordination coefficient, and g(θ1,θ2,θ3,σ,M) is the attitude angle dynamic correction term.

[0048] The specific values ​​of the aerodynamic characteristics of the 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] As can be seen from Table 1, the aerodynamic characteristics of the flight target change significantly with different Mach numbers. This places higher demands on the initial value calculation of attitude angles and the formulation of subsequent control strategies in order to achieve the best aerodynamic performance and flight control effect.

[0052] By using a Mach number correction function and a dynamic attitude angle correction term to adjust the initial attitude angle, the problem of insufficient accuracy in attitude angle calculation under different flight conditions can be effectively solved. Since the aerodynamic characteristics of a flight target change significantly at different Mach numbers, traditional attitude angle calculation methods struggle to accurately capture these changes. By introducing the Mach number correction function f(M), linear, quadratic, and exponential corrections to the attitude angle can be made based on the current Mach number, accurately reflecting the aerodynamic disturbance effects under supersonic and hypersonic conditions and improving the accuracy of attitude angle correction. The dynamic attitude angle correction term g(θ1,θ2,θ3,σ,M) considers the complex relationship between the initial values ​​of azimuth, pitch, and roll angles and the Mach number, especially under high angle-of-attack conditions (angle of attack greater than 15°), compensating for attitude angle changes caused by aerodynamic disturbances through exponential decay and a smooth transition function. This formula ensures the real-time nature and dynamic adaptability of attitude angle correction, thus maintaining high-precision attitude angle calculations 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 is a comprehensive correction of the attitude angle based on the Mach number, including linear, quadratic, and exponential correction terms. The formula for the Mach number correction function is as follows:

[0054] f(M) = 1 + α1(M-1) + α2(M-1) 2 +α3exp(-λ(M-1))

[0055] In the formula: α1, α2, and α3 are constant coefficients fitted based on experimental data, and λ is the influence adjustment factor.

[0056] The Mach number correction function combines linear, quadratic, and exponential correction terms to comprehensively correct attitude angles for changes in aerodynamic characteristics across different speed ranges, effectively addressing the issue of low accuracy in attitude angle measurements at varying flight speeds. Below the speed of sound, aerodynamic characteristics are relatively stable with minimal aerodynamic disturbances; the linear correction term α1(M-1) can handle attitude angle deviations, ensuring that the accuracy of attitude angle calculations for flight targets at low speeds remains at the required level. When the flight target is in the transonic range, aerodynamic effects become more complex, and shock wave and airflow separation phenomena begin to appear. The quadratic correction term α2(M-1)... 2To address this nonlinear variation, the calculation error of attitude angles is effectively controlled in the transonic region. In the supersonic range, shock wave effects and aerodynamic disturbances are further enhanced, and the quadratic correction term can further compensate for the complex aerodynamic effects of supersonic speeds. At the same time, the exponential change correction term α3exp(-λ(M-1)) gradually decreases in magnitude when the Mach number is greater than 1, reflecting the characteristic that aerodynamic effects tend to stabilize under hypersonic conditions and avoiding overcorrection.

[0057] It should be noted that in the correction formula for adjusting the initial 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 measurement accuracy is 0.1°, the pitch measurement accuracy is 0.15°, the roll measurement accuracy is 0.2°, and the simulation image attitude angle generation accuracy is 0.05°, the correction amounts for the azimuth, pitch, and roll angles are 0.05°, 0.1°, and 0.15°, respectively.

[0058] The above defines the specific scope and conditions for the application of this invention. These limitations ensure that, under specific photoelectric theodolite parameters, the Mach number correction function can fully function, providing high-precision attitude angle correction and guaranteeing the reliability and accuracy of flight attitude measurement.

[0059] When the angle of attack is greater than 15°, the flight target enters the critical angle of attack region, the fluid separation effect begins to appear, aerodynamic disturbances increase, the aerodynamic characteristics of the flight target become nonlinear, and the attitude angle changes more drastically, requiring sensitive correction. An appropriate angle of attack coordination coefficient is set to enable the photoelectric theodolite and the attitude angle correction method proposed in this invention to respond to attitude angle changes more quickly, increasing the weight of the dynamic attitude angle correction term, making the correction process more timely and accurate, especially under the effects of shock waves and airflow separation, ensuring the accuracy of attitude angle calculation. 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, reducing the weight of the dynamic attitude angle correction term. Simultaneously, considering the influence of Mach number, when the Mach number is less than or equal to 1, the dynamic attitude angle correction term is less than or equal to 1, while the change in attitude angle is not as drastic as when the angle of attack is greater than 15°, and the overall dynamic attitude angle correction term gradually approaches 0.

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

[0061]

[0062] In the formula: β1 is the adjustment coefficient for the correction amplitude.

[0063] It should be noted that in the formula for the dynamic correction term of attitude angle, when the angle of attack of the flight target 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 angle of attack of the flight target 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 for the dynamic attitude angle correction term, the range of the squared coordination coefficient is based on 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 squared coordination coefficient ([10,20]) is set to more sensitively capture rapid changes in attitude angle. When the angle of attack is less than 15°, the flight target is in a relatively stable aerodynamic state with small airflow separation effect. The squared coordination coefficient ([2,5]) is set to ensure a smooth correction process. The data range limitation is 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 conditions, conforming to the aerodynamic response of the actual flight target.

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

[0066] Step 21, Initialize state and parameters: Obtain the initial azimuth angle, initial pitch angle and initial roll angle through the correction formula of Mach number correction function and attitude angle dynamic correction term, and initialize error covariance matrix, state transition 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 time based on the Kalman gain formula;

[0069] Step 24, State Update: Correct the predicted attitude angle by combining the measured values ​​and Kalman gain;

[0070] Step 25, Error Covariance Update: Update the attitude angle error covariance after correction according to the error covariance update formula;

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

[0072] Example

[0073] To clearly illustrate the advancements of the method proposed in this invention, an example is provided. In a missile test, for a target with an imaging length of 180 pixels and a width of 30 pixels, the measured attitude angles show the advantages of the method proposed in this invention compared to the attitude angles measured by the inertial navigation pitch angle measurement method and the centerline method.

[0074] Inertial navigation (INS) pitch angle measurement methods use gyroscopes and accelerometers in an inertial measurement unit (IMU) to measure the pitch angle of a flying target. The INS senses the rotational motion and linear acceleration of the flying target. By integrating the acceleration and angular velocity, the attitude angles of the flying target at different time points are obtained. Measurement principle: The gyroscope detects the angular velocity of the flying target, while the accelerometer senses the direction of gravity. Combining the data from these two sensors, the attitude angles of the flying target, including the pitch angle, are calculated through integration. Characteristics: 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, the measurement results accumulate errors over time, thus requiring periodic calibration.

[0075] The centerline method measures attitude angles by the angle between the target's geometric axis (longitudinal axis) and the horizontal plane. It determines the pitch angle by observing the angular difference between the target and a horizontal reference using visual or optical equipment, such as an electro-optical theodolite. Measurement principle: The pitch angle is determined by measuring the angle between the target's longitudinal axis (centerline) and the ground reference plane. This can be accurately calculated using external observation equipment, such as optical instruments or laser rangefinders. Features: The centerline method offers high accuracy, especially under stable external observation conditions, and is suitable for real-time monitoring of target attitude changes, but it requires external reference points and equipment support.

[0076] Table 2 below shows a comparison of attitude angle measurement results using the proposed method in single-station and dual-station measurements, attitude angle measurement data using the inertial navigation pitch angle measurement method and the centerline method, and calculates the measurement error.

[0077] Table 2

[0078]

[0079]

[0080] Practical verification shows that the method proposed in this invention is superior to the centerline method. The calculation accuracy of this invention in two-station fusion measurements is higher than that in single-station measurements.

[0081] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0082] In conclusion, 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 within the protection scope of the present invention.

Claims

1. A method for measuring the attitude of a flight target based on a simulation imaging matching algorithm, comprising: obtaining real images through photoelectric theodolite measurement; establishing a spatial model based on the shape parameters of the flight target; constructing a numerical simulation environment; acquiring a sequence of simulated images; comparing the similarity between real images and simulated images; calculating the attitude angles to obtain the azimuth, pitch, and roll angles of the flight target; and obtaining the fusion similarity of multi-station measurements through multi-station similarity fusion to calculate the attitude angles of the flight target. The method is characterized by... The current Mach number is obtained by measuring the flight speed of the target and the local speed of sound. A simulation image template corresponding to the current Mach number is generated and selected. The initial attitude angle of the target is calculated based on the simulation image matching algorithm. The initial attitude angle is adjusted using the Mach number correction function and the dynamic adjustment term of the flight attitude. The dynamic adjustment term of the flight attitude is adjusted according to the Mach number and the angle of attack. The initial attitude angle is dynamically corrected by the Kalman filter algorithm to obtain the final corrected attitude angle of the target.

2. The method for measuring the attitude of a flight target based on a simulation imaging matching algorithm according to claim 1, characterized in that, The simulation image library is generated based on the Mach number and selects the corresponding simulation image template. It is constructed using computational fluid dynamics simulation software based on the set Mach number, azimuth, pitch, and roll angles. When no matching Mach number is found in the simulation image, the simulation image templates corresponding to the two adjacent Mach numbers to the desired match are linearly interpolated to obtain the simulation image for the current Mach number. The azimuth, pitch, and roll angles corresponding to the simulation image for the current Mach number are obtained through linear interpolation. The formula for obtaining the simulation image template for the current Mach number is: In the formula: M is the current Mach number, which is equal to the ratio of the measured velocity of the flight target to the 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 and second Mach numbers adjacent to the current Mach number in the simulation settings, M2>M1; and B(M1) and B(M2) are the simulation image templates corresponding to the first and second Mach numbers, respectively.

3. The method for measuring the attitude of a flight target based on a simulation imaging matching algorithm according to claim 1, characterized in that, The process of calculating the initial value of the flight target's attitude angle based on the simulation image matching algorithm includes: Step 11, acquire real and simulated images: acquire real images of the flight target at the time of calculation using an optoelectronic theodolite; select the simulated image template with the smallest difference from the current Mach number from the simulated image library based on the shape parameters of the flight target and the current Mach number; if there is no matching simulated image template, obtain the current Mach number simulated image template and the corresponding spatial attitude angle using the formula of the current Mach number simulated image template; and extract the contour features of the flight target from the current real image and simulated image template. Step 12, search for maximum similarity and obtain initial attitude angles: Using azimuth, pitch, and roll angles as variables, gradually change these three variables in the simulation image to generate simulation images under different attitude angles. Binarize the real image and the simulation image template. Within the initial attitude angle setting range, traverse the azimuth, pitch, and roll angles of the simulation image. Compare each frame of the simulation image with the current real image one by one, calculate the similarity between the real image and the binarized simulation image, and record their attitude angles. Search for the maximum similarity to obtain the initial attitude angle value of the flight target.

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

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

6. The method for measuring the attitude of a flight target based on a simulation imaging matching algorithm according to claim 4, characterized in that, In the correction formula for adjusting the initial 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 measurement accuracy is 0.1°, the pitch measurement accuracy is 0.15°, the roll measurement accuracy is 0.2°, and the simulation image attitude angle generation accuracy is 0.05°, the correction amounts for the azimuth, pitch, and roll angles are 0.05°, 0.1°, and 0.15°, respectively.

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

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

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