Binocular system wind tunnel coordinate system calibration method based on attack angle mechanism and fixed feature points

Abstract

The invention discloses a binocular system wind tunnel coordinate system calibration method based on an attack angle mechanism and fixed feature points, and belongs to the technical field of aerodynamic test measurement and visual calibration, and the method comprises the steps: arranging a binocular system in a wind tunnel, and calibrating the internal and external parameters of the binocular system through a cross scale; arranging a plurality of circular feature mark points on the wind tunnel wall surface and the model surface with overlapped visual fields of the binocular system; the model is driven by an attack angle mechanism to perform single-rolling motion and single-pitching motion so as to calibrate the axial vectors of a wind tunnel coordinate system, the axial vectors of the wind tunnel coordinate system are obtained through shaft-shaft cross multiplication, and calibration of the wind tunnel coordinate system of a binocular system is realized through registration of a camera measurement coordinate system and the wind tunnel coordinate system. The binocular system reconstructs a three-dimensional coordinate of the fixed point in a wind tunnel coordinate system; and aiming at the condition of subsequent camera recalibration, according to the three-dimensional coordinate of the fixed point, realizing the recalibration of the wind tunnel coordinate system by adopting resection. According to the invention, high-precision and high-efficiency alignment requirements of the measurement coordinate system and the wind tunnel coordinate system of the binocular system are met.

Description

Technical Field

[0001] This invention relates to a method for calibrating the coordinate system of a binocular system in a wind tunnel based on an angle-of-attack mechanism and stationary feature points. It belongs to the field of aerodynamic test measurement and visual calibration technology, and specifically relates to a method for calibrating the coordinate system of a binocular vision measurement system in a wind tunnel environment. Background Technology

[0002] Visual measurement technology, as a non-contact, high-precision attitude measurement method, has been gradually applied in wind tunnel test sections in China to solve related data. Data calculation using visual measurement technology typically requires mapping to the wind tunnel coordinate system. However, existing wind tunnel coordinate systems suffer from computational difficulties and poor accuracy, and the accuracy of the wind tunnel coordinate system directly determines the accuracy of subsequent data calculations. In wind tunnel testing, when solving for model pose, marker points are generally used for calibration. By obtaining the coordinates of the marker points in both the model and wind tunnel coordinate systems, the transformation relationship between the two systems can be solved, thus obtaining the model's motion attitude in the wind tunnel coordinate system. General video measurement systems can only obtain the coordinates of the marker points in the world coordinate system. Therefore, to obtain the coordinates of the marker points in the wind tunnel coordinate system, the transformation relationship between the world and wind tunnel coordinate systems needs to be known. This invention refers to the process of solving the rigid body transformation relationship between the world and wind tunnel coordinate systems as wind tunnel coordinate system calibration. Currently, high-precision 3D calibration is commonly used in wind tunnel testing to quickly align the world coordinate system to the wind tunnel coordinate system. However, the manufacturing precision requirements of 3D calibration blocks are high, resulting in significant maintenance costs. The calibration process is relatively complex, and the calibration method has low versatility, making it difficult to apply to large-scale continuous wind tunnel test sites in my country. Therefore, it is necessary to research a high-precision, rapid wind tunnel coordinate system calibration method that is simple to operate and does not require calibration objects. Summary of the Invention

[0003] The purpose of this invention is to address the aforementioned problems by proposing a binocular system wind tunnel coordinate system calibration method based on an angle-of-attack mechanism and stationary feature points. It utilizes the wind tunnel's built-in angle-of-attack mechanism for self-calibration, optimizes the vector calculation process during mechanism sweep, and proposes a wind tunnel in-tunnel wind axis system self-calibration algorithm. Its key features are: this invention is not limited by model shape or wind tunnel type; it only requires initial control of the angle-of-attack mechanism to drive the model in a specific motion to complete high-precision wind tunnel coordinate system calibration; subsequent wind tunnel tests only require calibration based on stationary feature points on the wind tunnel wall.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for wind tunnel coordinate system calibration of a binocular vision system based on angle-of-attack mechanism and stationary feature points includes the following steps: S1: A binocular system is installed in the wind tunnel, and the intrinsic and extrinsic parameters of the binocular cameras are calibrated. The binocular system includes two cameras; the intrinsic parameters of the binocular system include the focal length, radial distortion, tangential distortion, and image plane distortion of each camera; the extrinsic parameters of the binocular system include the rotation matrix and translation matrix of each camera relative to the photogrammetric coordinate system. S2: The external parameters of the binocular system include the rotation matrix and translation matrix of each camera and the photogrammetric coordinate system; a number of circular feature markers are arranged on the wind tunnel wall surface and the model surface where the field of view of the binocular system overlaps; S3: Use the angle-of-attack mechanism to drive the model to perform single roll and single pitch motions to calibrate the wind tunnel coordinate system. axis, Axis vectors, and through shaft and The cross product of axes yields the wind tunnel coordinate system. Axis vectors; S4: The calibration of the binocular vision system's wind tunnel coordinate system can be achieved by registering the measurement coordinate system with the wind tunnel coordinate system. S5: Reconstructing the three-dimensional coordinates of the fixed point in the wind tunnel coordinate system using a binocular system. ; S6: If the camera is recalibrated subsequently, the three-dimensional coordinates of the fixed point will be used. The wind tunnel coordinate system was recalibrated using resection.

[0005] Preferably, step S1 specifically includes: The crosshair scale was used to calibrate the internal and external parameters of the binocular camera:

[0006] In the formula, The pixel coordinates correspond to the camera's focal length; Represents a certain marker point Pixel coordinates; Indicates the lens focal length. Indicates the marker point Three-dimensional coordinates in the world coordinate system ; This represents the extrinsic parameter matrix from the coordinate systems of each camera in the binocular system to the world coordinate system. Indicates the principal point deviation; This indicates pixel coordinate deviation caused by lens distortion, including radial distortion. Tangential distortion Image plane distortion :

[0007] in:

[0008] The focal length of each camera Principal point deviation Radial distortion Tangential distortion Image plane distortion The intrinsic parameters constituting the binocular system, the The first three columns of elements and The elements in the fourth column represent the rotation and translation matrix components between each camera coordinate system and the world coordinate system, which together constitute the extrinsic parameters of the stereo system. It is the radial distortion coefficient. It is the tangential distortion coefficient. It is the image plane distortion coefficient. This represents the undistorted coordinates in the image coordinate system. .

[0009] Preferably, step S3 specifically includes: S31: Utilize the angle-of-attack mechanism to drive the model in a single roll motion and reconstruct the three-dimensional coordinates of a circular marker point on the model surface in at least three states. To calibrate the wind tunnel coordinate system Axis vectors ; The three-dimensional coordinates of a circular marker on the model surface in various states when the angle-of-attack mechanism drives the model to perform a single roll motion. For planes that are in the same plane, the coefficients of the following plane equations can be solved using the least squares method:

[0010] Based on the above plane equations, the X-axis vector of the wind tunnel coordinate system is obtained. : S32: Utilize the angle-of-attack mechanism to drive the model in a single pitch motion and reconstruct the three-dimensional coordinates of a circular marker point on the model surface in at least three states. To calibrate the wind tunnel coordinate system Axis vectors ; The three-dimensional coordinates of a circular marker point on the model surface in various states when the angle-of-attack mechanism drives the model to perform a single pitch motion. For planes that are in the same plane, the coefficients of the following plane equations can be solved using the least squares method:

[0011] The wind tunnel coordinate system is obtained based on the above plane equations and normals. Axis vectors : S33: Obtain the wind tunnel coordinate system using the axis vectors and their cross product. Axis vectors :

[0012] S34: Utilizing the wind tunnel coordinate system Axial vectors and wind tunnel coordinate system Axial vector cross product corrected wind tunnel coordinate system Axis vectors ;

[0013] Preferably, step S34 specifically includes: Since the initial wind tunnel coordinate system axis vectors cannot guarantee absolute perpendicularity, the wind tunnel coordinate system axis vectors are further modified to ensure that all vectors in the wind tunnel coordinate system are perpendicular to each other.

[0014] Preferably, step S4 specifically includes: Based on the X, Y, and Z axis vectors of the wind tunnel coordinate system This enables the binocular system's measurement coordinate system to be aligned with the wind tunnel's coordinate system.

[0015] Preferably, step S6 specifically includes: The three-dimensional coordinates of a fixed point on the wind tunnel wall in the wind tunnel coordinate system and corresponding points in the left and right images , Construct least-squares equations to recalibrate the wind tunnel coordinate system.

[0016] This invention abandons the high-cost processing and maintenance of 3D calibration blocks, instead utilizing a wind tunnel's built-in angle-of-attack mechanism for self-calibration, effectively reducing equipment dependence and costs. The initial calibration only requires driving the model to complete a specific motion; subsequent calibrations can be quickly completed based on stationary feature points on the wind tunnel wall, eliminating traditional complex operating procedures and significantly improving efficiency. This technology is not limited by model shape or wind tunnel type, and can be adapted to complex scenarios such as large-scale continuous wind tunnels, overcoming the applicability limitations of traditional methods. By optimizing vector calculation and feature point constraints, this technology ensures coordinate system calibration accuracy, providing a reliable foundation for visual measurement and attitude calculation, and possesses the characteristics of low cost, high efficiency, wide adaptability, and high precision, significantly outperforming traditional calibration schemes. Attached Figure Description

[0017] Figure 1 This is a flowchart of a wind tunnel coordinate system calibration method for a binocular vision system based on an angle-of-attack mechanism and stationary feature points, according to the present invention. Figure 2 This is a flowchart of the marker detection algorithm used in the calibration process of this invention; Figure 3 This is an experimental scene diagram of a wind tunnel coordinate system calibration method for a binocular vision system based on an angle-of-attack mechanism and stationary feature points according to the present invention. Figure 4 This is a schematic diagram of the cross scale of the present invention; Figure 5 This is a schematic diagram of the angle-of-attack mechanism of the present invention driving the model to perform a single roll motion; Figure 6 This is a schematic diagram of the angle-of-attack mechanism of the present invention driving the model to perform a single pitch motion.

[0018] The markings in the attached diagram are as follows: 1. Binocular system; 2. Incoming flow vector; 3. Wind tunnel test model; 4. Circular markers on the model surface; 5. Angle of attack mechanism; 6. Wind tunnel coordinate system; 7. Circular markers on the wind tunnel wall surface. Detailed Implementation

[0019] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope and application of the present invention.

[0020] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for both fixing and circuit / signal connectivity.

[0021] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] like Figure 1As shown, one embodiment of the present invention discloses a method for calibrating the wind tunnel coordinate system of a binocular vision system based on an angle-of-attack mechanism and stationary feature points, comprising the following six parts: S1: Before the experiment, select a camera model and fixed-focus camera lens suitable for the measurement field of view according to the measurement requirements. Arrange the installation position of the binocular system reasonably, adjust the camera aperture, and complete the focusing operation. Use a crosshair to calibrate the internal and external parameters of the binocular camera; S2: Arrange several circular feature markers on the wind tunnel wall surface and model surface in the overlapping area of ​​the binocular system's field of view; S3: Use the angle-of-attack mechanism to drive the model to perform single roll motion and single pitch motion respectively to calibrate the wind tunnel coordinate system. axis, Axis vectors, and through shaft and The cross product of axes yields the wind tunnel coordinate system. Axis vectors; S4: Measurement coordinate system and wind tunnel coordinate system via camera axis, Shaft and Axis vector registration is performed to calibrate the wind tunnel coordinate system of the stereo system; S5: After the camera coordinate system and the wind tunnel coordinate system are aligned, the distortion-free coordinates of the marker point are calculated using the distortion parameters of each camera, based on the distorted pixel coordinates detected by the same 3D point in the left and right images. Based on the distortion-free coordinates, the 3D coordinates of the fixed point in the wind tunnel coordinate system are reconstructed using the stereo system. S6: If subsequent camera recalibration causes a change in the relative positional relationship between the binocular system's measurement coordinate system and the wind tunnel coordinate system, this can be addressed by adjusting the three-dimensional coordinates of the fixed points. The wind tunnel coordinate system was recalibrated using the resection method.

[0024] The specific implementation process is as follows: Step 1: Install a binocular system in the wind tunnel and calibrate the internal and external parameters of the binocular system. like Figure 3 As shown, the X-axis vector of the wind tunnel coordinate system The Z-axis vector is opposite to the direction of the incoming flow. Vertically upwards from the horizontal plane, then determine the Y-axis vector according to the right-hand rule. The direction of the binocular system is crucial. Before the test, the installation position of the binocular system should be reasonably arranged according to the wind tunnel test measurement requirements and on-site installation conditions, so that the angle between the optical axes of the two cameras is approximately 30°, and the common field of view is directly facing the model surface. For example, when measuring the bending and twisting deformation of an aircraft wing, the binocular system should be placed on the upper wall of the wind tunnel to get a top-down view of the entire wing; when measuring the aircraft's pitch attitude, the binocular system should be placed on the side wall of the wind tunnel, preferably at the same height as the aircraft, to avoid calculating motion data in the depth of field direction and improve the accuracy of pitch attitude measurement. If the wind tunnel test section has an optical window, the binocular system should be placed outside the window first.

[0025] After the binocular system was installed, the camera aperture and focus were adjusted, and a suitable exposure time was set to ensure a clear image. A crosshair was placed at at least eight different locations within the wind tunnel, and the image was determined based on the known three-dimensional coordinates of the marked points on the crosshair in the world coordinate system. and the marker pixels obtained from left and right image detection in a binocular system The least squares method was used to calibrate the intrinsic and extrinsic parameters of each camera in the binocular system. The crosshair scale is shown in Figure 4.

[0026] In the formula, The pixel coordinates correspond to the camera's focal length; Represents a certain marker point Pixel coordinates; Indicates the lens focal length. Indicates the marker point Three-dimensional coordinates in the world coordinate system ; This represents the extrinsic parameter matrix from the coordinate systems of each camera in the binocular system to the world coordinate system. Indicates the principal point deviation; This indicates pixel coordinate deviation caused by lens distortion, including radial distortion. Tangential distortion Image plane distortion :

[0027] in:

[0028] The focal length of each camera Principal point deviation Radial distortion Tangential distortion Image plane distortion The intrinsic parameters constituting the binocular system, the The first three columns of elements and The elements in the fourth column represent the rotation and translation matrix components between each camera coordinate system and the world coordinate system, which together constitute the extrinsic parameters of the stereo system. It is the radial distortion coefficient. It is the tangential distortion coefficient. It is the image plane distortion coefficient. This represents the undistorted coordinates in the image coordinate system. .

[0029] Step 2: Arrangement of circular feature markers Based on the overlapping field of view of the binocular system, circular feature markers are placed at rigid locations on the model, such as the aircraft fuselage and the wind tunnel wall. The radius of each circular marker should be approximately 10-15 pixels in the image; therefore, the sizes of the circular markers on the model surface and the wind tunnel wall should be different, but not limited to coded and non-coded markers. Furthermore, at least three circular markers should be arranged and they should not be collinear.

[0030] Step 3: Wind tunnel coordinate system calibration Before the test, the wind tunnel control center coordinated with the wind tunnel to place the test model in a reference installation state with 0° pitch, 0° yaw, and 0° roll.

[0031] First, the angle-of-attack mechanism is used to drive the model to perform a single-degree-of-freedom rolling motion, as shown in Figure 5. A binocular system is used to acquire images in real time and reconstruct the three-dimensional coordinates of a circular marker point on the model surface under various states in the binocular measurement system. The specific marker detection algorithm is shown in Figure 2. It identifies the boundaries of circular markers and then uses ellipse fitting to locate the specific position of the markers.

[0032] In the formula:

[0033]

[0034] In the formula, , These represent the components of the extrinsic parameter matrices of the left and right cameras after the binocular system has been recalibrated.

[0035] Since the three-dimensional coordinates of a circular marker point on the model surface lie in the same spatial plane when the model performs a single-degree-of-freedom rolling motion, the coefficients of the following plane equations are solved using the least squares method. :

[0036] The wind tunnel coordinate system is obtained based on the above plane equations and normals. Axis vectors .

[0037] Secondly, the angle-of-attack mechanism is used to drive the model to perform a single-degree-of-freedom pitch motion, as shown in Figure 6. A binocular system is used to acquire images in real time and reconstruct the three-dimensional coordinates of a circular marker point on the model surface under various states in the binocular measurement system. .

[0038] The three-dimensional coordinates of a circular marker point on the model surface in various states when the angle-of-attack mechanism drives the model to perform a single-degree-of-freedom pitch motion. For equations within the same plane, the coefficients of the following plane equations can be solved using the least squares method. :

[0039] The wind tunnel coordinate system is obtained based on the above plane equations and normals. Axis vectors .

[0040] Then, using the wind tunnel coordinate system Axis vectors and Axis vectors Cross product yields the wind tunnel coordinate system Axis vectors :

[0041] Finally, due to the initially established wind tunnel coordinate system Axis vectors With wind tunnel coordinate system Axis vectors Not necessarily perfectly vertical, therefore a wind tunnel coordinate system is used. Axis vectors wind tunnel coordinate system Axis vectors Cross product corrected wind tunnel coordinate system Axis vectors :

[0042] Step 4: Registration of the binocular system measurement coordinate system with the wind tunnel coordinate system Step 3 describes the solution to obtain the wind tunnel coordinate system. axis, axis, Since all axis vectors are in the binocular system measurement coordinate system, the binocular system measurement coordinate system needs to be... , , Rotate until each is aligned with the wind tunnel coordinate system. axis, axis, The axial vectors are parallel.

[0043] Step 5: Fixed Point 3D Reconstruction After camera calibration, the binocular system's measurement coordinate system is aligned parallel to the wind tunnel coordinate system. Based on the pixel coordinates of circular feature markers placed on the wind tunnel wall surface within the overlapping field of view of the binocular system, these markers are mapped onto the left and right camera images. , First, increase the distortion parameters of the left and right cameras respectively to adjust the distortion coordinates. , Distortion is removed, and 3D reconstruction is performed on the distortion-free coordinates to obtain the 3D coordinates of each circular marker point in the current wind tunnel coordinates. .

[0044] Step 6: Based on fixed points Wind tunnel coordinate system alignment Because the camera's installation position, focal length, exposure time, and aperture need to be adjusted to meet different test scenarios or different test requirements within the same test scenario, both the internal and external parameters of the camera change. If the camera calibration process is to be coordinated with the wind tunnel control center after each binocular system camera calibration to control the angle-of-attack mechanism to perform single-degree-of-freedom motion to calibrate the wind tunnel coordinate system, it will inevitably make the wind tunnel coordinate system calibration process cumbersome and time-consuming.

[0045] However, the position of the circular feature markers on the wind tunnel wall surface within the overlapping field of view of the binocular system remains unchanged, and their three-dimensional coordinates in the initial wind tunnel coordinate system remain the same. All have been determined, and the alignment of the binocular system measurement coordinate system with the wind tunnel coordinate system under this condition can be achieved by using the resection method.

Claims

1. A method for calibrating a wind tunnel coordinate system based on an angle-of-attack mechanism and stationary feature points in a binocular system, characterized in that, Includes the following steps: S1: A binocular system is set up in a wind tunnel, and the internal and external parameters of the binocular camera are calibrated using a crosshair; the binocular system consists of two cameras; S2: Arrange several circular feature marks on the wind tunnel wall surface and model surface in the overlapping area of ​​the binocular system's field of view; S3: Using the angle-of-attack mechanism to drive the model, perform single roll and single pitch motions respectively, to calibrate the wind tunnel coordinates. Tie axis, Axis vectors, and through shaft and The cross product of axes yields the wind tunnel coordinate system. Axis vectors; S4: The calibration of the binocular vision system's wind tunnel coordinate system can be achieved by registering the measurement coordinate system with the wind tunnel coordinate system. S5: Using a binocular system, reconstruct the three-dimensional coordinates of the fixed points in the wind tunnel coordinate system. ; S6: If the camera is recalibrated subsequently, the three-dimensional coordinates of the fixed point will be used. The re-intersection method was used to recalibrate the wind tunnel coordinate system.

2. The method for calibrating the wind tunnel coordinate system of a binocular system based on an angle-of-attack mechanism and stationary feature points according to claim 1, characterized in that, Step S1 specifically includes: The internal and external parameters of the binocular camera were calibrated using a crosshair scale. In the formula, The pixel coordinates correspond to the camera's focal length; Represents a certain marker point Pixel coordinates; Indicates the lens focal length. Indicates the marker point Three-dimensional coordinates in the world coordinate system ; This represents the extrinsic parameter matrix from the coordinate systems of each camera in the stereo system to the world coordinate system, where ij represents the subscript of the matrix elements. ; Indicates the principal point deviation; The principal point deviation of the camera's imaging plane; This indicates the pixel coordinate deviation caused by lens distortion: in: Focal length of each camera Principal point deviation Radial distortion Tangential distortion Image plane distortion The intrinsic parameters of a binocular system, among which It is the radial distortion coefficient. It is the tangential distortion coefficient. It is the image plane distortion coefficient. This represents the undistorted coordinates in the image coordinate system. , The first three columns and the fourth column represent the rotation matrix components and translation matrix components between each camera coordinate system and the world coordinate system, respectively, which together constitute the extrinsic parameters of the binocular system.

3. The binocular system wind tunnel coordinate system calibration method based on angle-of-attack mechanism and stationary feature points according to claim 1, characterized in that, In step S2, the binocular system includes two cameras, left and right, and the two cameras are installed at an angle of 20 to 30 degrees. When arranging circular feature markers, it is necessary to ensure that both the left and right cameras can capture the circular feature markers.

4. The wind tunnel coordinate system calibration method for a binocular vision system based on an angle-of-attack mechanism and stationary feature points according to claim 1, characterized in that, Step S3 specifically includes: S31: Utilizes an angle-of-attack mechanism to drive the model in a single roll motion, causing the model to rotate around... Rotate the axis from its initial state and calculate the wind tunnel coordinate system. axis; S32: Utilizes the angle-of-attack mechanism to drive the model in a single pitch motion, causing the model to rotate... The axis rotates from its initial state to calibrate the wind tunnel coordinate system. axis; S33: Utilizing the wind tunnel coordinate system Axis vectors and The cross product of axial vectors yields the wind tunnel coordinate system. Axis vectors : S34: Utilizing the wind tunnel coordinate system Axial vectors and wind tunnel coordinate system Axial vector cross product corrected wind tunnel coordinate system Axis vectors ; 。 5. The wind tunnel coordinate system calibration method for a binocular vision system based on an angle-of-attack mechanism and stationary feature points according to claim 4, characterized in that, Step S31 specifically includes: when the model performs a single roll motion, it is necessary to reconstruct the three-dimensional coordinates of a certain circular marker point on the model surface. To calibrate the wind tunnel coordinate system Axis vectors ; When the angle-of-attack mechanism drives the model to perform a single roll motion, the three-dimensional coordinates of a certain circular marker point on the model surface will be in at least three states. For planes that are in the same plane, the coefficients of the following plane equations can be solved using the least squares method: The wind tunnel coordinate system is obtained based on the above plane equations and normals. Axis vectors .

6. The wind tunnel coordinate system calibration method for a binocular vision system based on an angle-of-attack mechanism and stationary feature points according to claim 3, characterized in that, Step S32 specifically includes: the three-dimensional coordinates of a circular marker point on the model surface in each state when the angle-of-attack mechanism drives the model to perform a single pitch motion. For planes that are in the same plane, the coefficients of the following plane equations can be solved using the least squares method: The wind tunnel coordinate system is obtained based on the above plane equations and normals. Axis vectors .

7. The wind tunnel coordinate system calibration method for a binocular vision system based on an angle-of-attack mechanism and stationary feature points according to claim 3, characterized in that, Step S34 specifically includes: since the initial wind tunnel coordinate system axis vectors and wind tunnel coordinate system axis vectors cannot guarantee absolute perpendicularity, the wind tunnel coordinate system axis vectors are further modified to ensure that each vector in the wind tunnel coordinate system is perpendicular to the other.

8. The wind tunnel coordinate system calibration method for a binocular vision system based on an angle-of-attack mechanism and stationary feature points according to claim 1, characterized in that, Step S4 specifically includes: wind tunnel coordinate system , , Axis vectors This enables the binocular system's measurement coordinate system to be aligned with the wind tunnel's coordinate system.

9. The wind tunnel coordinate system calibration method for a binocular vision system based on an angle-of-attack mechanism and stationary feature points according to claim 1, characterized in that, Step S6 specifically includes: The three-dimensional coordinates of a fixed point on the wind tunnel wall in the wind tunnel coordinate system and corresponding points in the left and right images , Construct least-squares equations to recalibrate the wind tunnel coordinate system: In the formula The focal lengths of the left and right cameras corresponding to the pixel coordinates; These are the intrinsic parameter matrices for the left and right cameras, respectively. Let be the rotation and translation matrix from the right camera to the wind tunnel coordinate system; Let be the rotation and translation matrix from the left camera to the wind tunnel coordinate system; , Let i and j represent the extrinsic parameter matrices from the left and right camera coordinate systems to the wind tunnel coordinate system after the binocular system has been recalibrated, respectively, where i and j are the subscripts of the matrix elements. .

Images