Tail-sensitive projectile steady-state scanning parameter measurement system based on backlight profile

Abstract

The invention belongs to the technical field of steady-state scanning wind tunnel tests of terminal-sensitive projectiles, and particularly relates to a backlight profile-based steady-state scanning parameter measurement system for a terminal-sensitive projectile, which comprises a backlight measurement system for steady-state scanning parameters of the terminal-sensitive projectile and a steady-state scanning parameter resolving system, wherein the terminal sensitive projectile steady-state scanning parameter backlight measurement system comprises an active light source, a high-speed camera and a vertical wind tunnel; the steady-state scanning parameter resolving system comprises an edge line segment acquisition module, a steady-state scanning angle acquisition module and a steady-state scanning rotating speed acquisition module; the obtained steady-state scanning angle and the steady-state scanning rotating speed of the terminal-sensitive projectile are important test data of a vertical wind tunnel terminal-sensitive projectile steady-state scanning parameter measurement test, and a data basis can be provided for design optimization and performance identification of the terminal-sensitive projectile.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of terminal-sensitive ammunition steady-state scanning wind tunnel test, and particularly relates to a terminal-sensitive ammunition steady-state scanning parameter measurement system based on backlight profile. BACKGROUND

[0002] Terminal-sensitive ammunition (full name "terminal-sensitive ammunition") is an intelligent ammunition capable of autonomously detecting, identifying, locking and automatically activating a combat unit to attack a battlefield target at the end of the trajectory, and has an important position in the field of weapon equipment. Steady-state scanning is one of the important links for terminal-sensitive ammunition to capture and attack targets, and the steady-state scanning parameters are closely related to the attack effect of terminal-sensitive ammunition. Measuring the steady-state scanning parameters of terminal-sensitive ammunition through vertical wind tunnel test is an important research approach. Accurate measurement of the steady-state scanning angle and rotational speed of terminal-sensitive ammunition can provide a data basis for terminal-sensitive ammunition design optimization and performance identification, and has significant engineering application value.

[0003] The measurement method of the steady-state scanning parameters of terminal-sensitive ammunition can be divided into sensor measurement method and visual measurement method. The steady-state scanning parameter measurement method based on sensors is mostly used in field tests, and the measurement data is greatly affected by the environment, and the test precision is low. Visual measurement means is mostly used in vertical wind tunnel for measuring the steady-state scanning parameters of terminal-sensitive ammunition. The commonly used visual measurement means includes laser projection measurement method and double (multi) visual measurement method. Although the laser projection measurement method can accurately obtain the steady-state scanning parameters of terminal-sensitive ammunition, the method needs to be arranged and fixed in the wind tunnel site for a long time, and the height position of the terminal-sensitive ammunition during the test is strictly required, resulting in high test cost and complex operation. Although the double (multi) visual measurement method has high measurement precision and stable data, in actual measurement, it is necessary to pre-paste mark points on the surface of the projectile body, and to perform complex data processing such as acquisition of local three-dimensional point coordinates, camera calibration and coordinate alignment, resulting in long test time and low efficiency. SUMMARY

[0004] (I) Technical problem to be solved

[0005] The technical problem to be solved by the present application is how to provide a terminal-sensitive ammunition steady-state scanning parameter measurement system based on backlight profile to overcome the shortcomings of the prior art and provide reliable data for vertical wind tunnel terminal-sensitive ammunition steady-state scanning parameter measurement test. The method requires high efficiency, low cost and high accuracy, and can meet the actual engineering application requirements.

[0006] (II) Technical scheme

[0007] To solve the above technical problems, the application provides a steady-state scanning parameter measurement system based on backlight profile of a terminal-sensitive bomb, which comprises a steady-state scanning parameter backlight measurement system of the terminal-sensitive bomb and a steady-state scanning parameter solving system; the steady-state scanning parameter backlight measurement system of the terminal-sensitive bomb comprises an active light source, a high-speed camera and a vertical wind tunnel; the steady-state scanning parameter solving system comprises an edge line segment acquisition module, a steady-state scanning angle acquisition module and a steady-state scanning rotation speed acquisition module.

[0008] The steady-state scanning parameter backlight measurement system of the terminal-sensitive bomb is used to record a backlight image sequence of the terminal-sensitive bomb in a steady-state scanning motion state by using the high-speed camera.

[0009] The edge line segment acquisition module is used to extract edge features of a profile of the terminal-sensitive bomb based on a barycentric scanning line method.

[0010] The steady-state scanning angle acquisition module is used to solve a steady-state scanning angle of the terminal-sensitive bomb based on a geometric mapping relationship.

[0011] The steady-state scanning rotation speed acquisition module is used to solve a steady-state scanning rotation speed of the terminal-sensitive bomb based on an axis matching method.

[0012] In the steady-state scanning parameter backlight measurement system of the terminal-sensitive bomb, an active light source is used to create a backlight area behind the terminal-sensitive bomb body, a high-speed camera is arranged at the same height as the terminal-sensitive bomb, the camera optical axis is horizontal and perpendicular to the axis of the vertical wind tunnel, and the distance between the camera and the terminal-sensitive bomb is greater than the virtual cone radius formed when the terminal-sensitive bomb rotates; the focal length and aperture of the camera are adjusted to ensure that the backlight image of the terminal-sensitive bomb is clear in the camera image, and the high-speed camera is used to record a backlight image sequence P of the terminal-sensitive bomb in a steady-state scanning motion state.

[0013] The edge line segment acquisition module extracts the edge features of the profile of the terminal-sensitive bomb based on the barycentric scanning line method as follows:

[0014] For each backlight image, the terminal-sensitive bomb target is extracted from the image based on background subtraction, the sub-pixel edge extraction method is used to preprocess the terminal-sensitive bomb target in the image to obtain the profile points of the terminal-sensitive bomb body, and the barycentric scanning line method is used to process the profile points to obtain the left and right edge line segments.

[0015] The steady-state scanning angle acquisition module solves the steady-state scanning angle of the terminal-sensitive bomb based on a geometric mapping relationship as follows:

[0016] The left and right edge features of the terminal-sensitive bomb profile are used to construct the axis feature points of the terminal-sensitive bomb and solve the image coordinates thereof, the angle between the axis of the terminal-sensitive bomb and the longitudinal axis of the image plane is solved based on the geometric relationship of the image plane, and the ray tracing method and the geometric analysis method are used to solve the steady-state scanning angle of the terminal-sensitive bomb.

[0017] The process of the steady-state scanning speed acquisition module solving the steady-state scanning speed of the terminal-sensitive projectile based on the axis matching method is as follows:

[0018] The axis matching factor ε is constructed using the left and right edge direction vectors of the terminal-sensitive projectile and the basic unit direction vector, and the axis matching factor ε of each backlight image is solved. p , based on the matching factor ε p The image sequence number corresponding to the minimum value is used to solve the steady-state scanning speed of the terminal-sensitive projectile.

[0019] The process of extracting the edge features of the terminal-sensitive projectile contour based on the centroid scanning line method by the edge segment acquisition module specifically includes the following steps:

[0020] Step 2.1: Using the backlit image without terminal sensitive projectiles as the background reference, for each image in the image sequence P, calculate the absolute value of the difference between the grayscale value of each pixel and the grayscale value of the corresponding pixel of the background reference, and compare it with the set threshold σ to obtain the binary image f(x, y, p) of each image:

[0021]

[0022] Where f(x,y,p) is the binary image of the p-th image, x,y are the 2D coordinate values ​​of the image pixels, I(x,y,p) is the grayscale value of the pixel at the (x,y) coordinate of the p-th image, I(x,y,0) is the grayscale value of the pixel at the (x,y) coordinate of the reference image, and σ is the set threshold;

[0023] Step 2.2: Perform morphological operations on each binary image and cluster it based on the four neighborhoods. Select the largest cluster to obtain the terminal-sensitive missile target image to be extracted;

[0024] Step 2.3: Use the sub-pixel edge extraction method to extract the edge of the terminal-sensitive missile target image extracted in step 2.2 to obtain the terminal-sensitive missile body contour points in each image;

[0025] Step 2.4: For each image, find the center of gravity C of the terminal sensitive projectile body contour points p , with the center of gravity C p As the center of the circle, a scan line is constructed on the image to obtain the intersection of the scan line and the projectile contour. Each scan line will form two intersections with the projectile contour. The distance between the two intersections of each scan line is calculated. The scan line with the shortest distance is used as the reference scan line. The intersection points of the scan lines with an angle of ±45° with the reference scan line and the projectile contour are extracted as the final contour points. The contour points close to the left in the image are fitted to obtain the left edge line segment. Fit the contour points close to the right side of the image to obtain the right edge segment

[0026] The steady-state scanning angle obtaining module obtains the steady-state scanning angle of the terminal-sensitive projectile based on a geometric mapping relationship, and specifically includes the following steps:

[0027] Step 3.1: For each image, the midpoints of the line segments and are extracted respectively. The midpoint of the line segment with as the vertex is taken as the axis feature point a p of the terminal-sensitive projectile, and the image coordinates of the feature point a p are solved.

[0028] Step 3.2: For each image, the included angle between the line segment and the image longitudinal axis is calculated. The included angle between the line segment and the image longitudinal axis is calculated. According to the plane geometric relationship, the included angle

[0029] between the terminal-sensitive projectile axis and the image longitudinal axis is obtained.

[0030]

[0031] wherein β p , γ p , The three angles can be calculated based on the focal length f of the high-speed camera, the pixel size dx and dy, the image coordinates of the feature point a p , and the angle θ p , and the specific calculation method is as follows:

[0032]

[0033] Step 3.4: The array K = {η1, η2,..., η p ,..., η p} is formed by the angles η P solved for all images; all maximum values in the array K are extracted and averaged, and the steady-state scanning angle η of the terminal-sensitive projectile is obtained.

[0034] The steady-state scanning speed obtaining module obtains the steady-state scanning speed of the terminal-sensitive projectile based on an axis matching method, and specifically includes the following steps:

[0035] Step 4.1: For each image, the included angle between the line segment and the image longitudinal axis is calculated. and the normalized direction vector of the line segment

[0036] Step 4.2: set the basic unit vector as Construct the axis matching factor ε and solve the axis matching factor of each image

[0037] Step 4.3: solve the axis matching factor ε of all images p Form an array ξ = {ε1, ε2,..., ε p ,...,ε P}; extract the image sequence number corresponding to all the minimum values in the array ξ and arrange them in ascending order to form a new image frame sequence array Q = {q1, q2,..., q n ,...,q N};

[0038] Step 4.4: use the new image frame sequence array to calculate the steady-state scanning real-time speed v n and the average speed

[0039] v n = 1 / ((q n -q n-2 )×ΔT)

[0040]

[0041] Wherein, the unit of real-time speed v n and the average speed is r / s, and ΔT is the time interval between adjacent two images during image acquisition.

[0042] (Three) beneficial effects

[0043] Compared with the prior art, the present application has the following beneficial technical effects:

[0044] ​​The application is based on monocular vision backlight profile image to measure the steady-state scanning angle and steady-state scanning speed parameters of terminal-sensitive ammunition, is suitable for terminal-sensitive ammunition steady-state scanning parameter measurement test of vertical wind tunnel, and can provide data basis for terminal-sensitive ammunition design and performance identification. Compared with laser projection measurement method and double (multiple) vision measurement method, the application adopts background subtraction and sub-pixel edge extraction method to obtain terminal-sensitive ammunition body profile points, effectively obtains edge line segment features based on barycentric scanning line method, solves terminal-sensitive ammunition steady-state scanning angle based on image geometric relationship and space geometric mapping, and solves terminal-sensitive ammunition steady-state scanning speed based on axis matching. The application has the characteristics of simple principle, high solving efficiency, reduced equipment complexity and cost, simplified test process, and improved terminal-sensitive ammunition steady-state scanning parameter measurement efficiency. In conclusion, the application realizes accurate and efficient measurement of terminal-sensitive ammunition steady-state scanning angle and steady-state scanning speed based on monocular vision backlight profile image, has the characteristics of simplicity, efficiency, feasibility, accuracy and the like, can provide reliable data for terminal-sensitive ammunition steady-state scanning parameter measurement test of vertical wind tunnel, and has engineering practical value. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 It is terminal-sensitive ammunition steady-state scanning parameter measurement flowchart based on backlight profile.

[0046] Figure 2 It is terminal-sensitive ammunition steady-state scanning parameter backlight measurement system schematic diagram; wherein, 1, backlight image sequence collected by high-speed camera; 2, high-speed camera; 3, image acquisition control system; 4, vertical wind tunnel; 5, LED high-brightness light source; 6, backlight area; 7, terminal-sensitive ammunition parachute; 8, terminal-sensitive ammunition body.

[0047] Figure 3 It is contour edge line segment extraction schematic diagram based on barycentric scanning line method. Wherein, C p It is barycenter of terminal-sensitive ammunition body profile points; dotted line is scanning line constructed on image; It is left edge line segment obtained by fitting profile points close to left side in image, It is right edge line segment obtained by fitting profile points close to right side in image.

[0048] Figure 4 It is terminal-sensitive ammunition axis feature point construction schematic diagram in image. Wherein, They are midpoints of line segment and line segment respectively, It is terminal-sensitive ammunition axis feature point constructed.

[0049] Figures 5a-5b It is geometric mapping relationship schematic diagram of terminal-sensitive ammunition steady-state scanning angle in different coordinate systems. Wherein, Figure 5ais the isometric view of the virtual cone scene formed from the optical center of the camera to the axis of the terminal sensitive bomb. The vertex of the virtual cone is S, one intersection point of the axis and the bottom surface of the virtual cone is A, and the coordinate system O W -X W Y W Z W is the world coordinate system, and the origin O W is the center of the ground of the virtual cone, and Z W is the axis coinciding with the axis of the virtual cone, and X W is the axis parallel to the Z C axis of the camera coordinate system, and the coordinate system O C -X C Y C Z C is the camera coordinate system, and the origin O C is the optical center of the camera, and Y C is the axis coinciding with the Z W axis, and the Z C axis coinciding with the optical axis of the camera W is the axis orthogonal to the Z C axis, and the line O W connecting the optical center of the camera and the point A on the ground of the virtual cone intersects at the point K; A (the imaging ray of the point A) is tangent to the ground circle of the virtual cone; an auxiliary plane is created through the point A, and the plane is perpendicular to the X C axis, and the rays O W A and X C intersect at the points D, G and N; the point M is the foot of the perpendicular line passing through the point A and perpendicular to the plane O C -X C Z C ; Figure 5b is the isometric view from the optical center of the camera to the image plane, and the coordinate system o-xy is the image coordinate system, and the origin o is the projection of the optical center O C of the camera; according to the ray locus theory, the points S and D coincide in the image plane projection, and the point S, D is s (d); the point A projects to a in the image plane, and the point M projects to m in the image plane; the angles θ, β, γ related to the scanning angle η, are marked in the figure.

[0050] Figure 6a and Figure 6b are the solving results of the steady-state scanning angle and the steady-state scanning speed. Among them, Figure 6a is the result curve diagram of the steady-state scanning angle, in which the horizontal coordinate represents time, the unit is s, and the vertical coordinate represents angle, the unit is °; Figure 6b is the result curve diagram of the steady-state scanning speed, in which the horizontal coordinate represents time, the unit is s, and the vertical coordinate represents speed, the unit is r / s. DETAILED DESCRIPTION

[0051] In order to make the purposes, contents, and advantages of the present application more apparent, the specific embodiments of the present application are described in further detail below with reference to the accompanying drawings and examples.

[0052] To solve the above technical problems, the present application provides a steady-state scanning parameter measurement system for submunition based on backlight profile, which comprises a steady-state scanning parameter backlight measurement system for submunition and a steady-state scanning parameter solving system; wherein the steady-state scanning parameter backlight measurement system for submunition comprises an active light source, a high-speed camera, and a vertical wind tunnel; the steady-state scanning parameter solving system comprises an edge line segment acquisition module, a steady-state scanning angle acquisition module, and a steady-state scanning rotation speed acquisition module.

[0053] The steady-state scanning parameter backlight measurement system for submunition is used to record a backlight image sequence of the submunition in a steady-state scanning motion state by using the high-speed camera.

[0054] The edge line segment acquisition module is used to extract edge features of the submunition profile based on a barycentric scanning line method.

[0055] The steady-state scanning angle acquisition module is used to solve the steady-state scanning angle of the submunition based on a geometric mapping relationship.

[0056] The steady-state scanning rotation speed acquisition module is used to solve the steady-state scanning rotation speed of the submunition based on an axis matching method.

[0057] In the steady-state scanning parameter backlight measurement system for submunition, an active light source is used to create a backlight area behind the submunition body, a high-speed camera is arranged at the same height as the submunition, the camera optical axis is horizontal and orthogonal to the axis of the vertical wind tunnel, and the distance between the camera and the submunition is greater than the virtual cone radius formed by the rotation of the submunition; the focal length and aperture of the camera are adjusted to ensure that the backlight image of the submunition is clearly visible in the camera image, and the high-speed camera is used to record a backlight image sequence P of the submunition in a steady-state scanning motion state.

[0058] The process of extracting edge features of the submunition profile based on the barycentric scanning line method by the edge line segment acquisition module is as follows:

[0059] For each backlight image, the submunition target is extracted from the image based on background subtraction, the submunition target in the image is preprocessed by using a sub-pixel edge extraction method to obtain profile points of the submunition body, and the profile points are processed by using the barycentric scanning line method to obtain left and right edge line segments.

[0060] The process of solving the steady-state scanning angle of the submunition based on the geometric mapping relationship by the steady-state scanning angle acquisition module is as follows:

[0061] The left and right edges of the terminal-sensitive bomb profile are used to construct the axis feature points of the terminal-sensitive bomb and to solve their image coordinates. The angle between the axis of the terminal-sensitive bomb and the longitudinal axis of the image plane is solved based on the geometric relationship of the image plane. The stable scanning angle of the terminal-sensitive bomb is solved by using the ray tracing method and the geometric analysis method.

[0062] The process of solving the stable scanning speed of the terminal-sensitive bomb based on the axis matching method by the stable scanning speed acquisition module is as follows:

[0063] The axis matching factor ε is constructed by using the left and right edge direction vectors and the basic unit direction vector of the terminal-sensitive bomb, and the axis matching factor ε of each back light image is solved. p The axis matching factor ε is constructed by using the left and right edge direction vectors and the basic unit direction vector of the terminal-sensitive bomb, and the axis matching factor ε of each back light image is solved. p The stable scanning speed of the terminal-sensitive bomb is solved based on the image sequence number corresponding to the minimum value of the matching factor ε.

[0064] The process of extracting the edge feature of the terminal-sensitive bomb profile based on the barycentric scanning line method by the edge line segment acquisition module includes the following steps:

[0065] Step 2.1: Using the back light image without the terminal-sensitive bomb as the background reference, the absolute value of the difference between the gray value of each pixel point of each image in the image sequence P and the gray value of the corresponding pixel point of the background reference is calculated, and compared with the set threshold σ, to obtain the binary image f(x,y,p) of each image:

[0066]

[0067] Where f(x,y,p) is the binary image of the pth image, x and y are the 2D coordinate values of the image pixel, I(x,y,p) is the gray value of the (x,y) coordinate pixel point of the pth image, I(x,y,0) is the gray value of the (x,y) coordinate pixel point of the reference image, and σ is the set threshold;

[0068] Step 2.2: Morphological operation is performed on each binary image, and clustering is performed based on the four-neighborhood, and the largest cluster is selected to obtain the terminal-sensitive bomb target image to be extracted;

[0069] Step 2.3: The sub-pixel edge extraction method is used to extract the edge of the terminal-sensitive bomb target image extracted in step 2.2, to obtain the terminal-sensitive bomb profile points of each image;

[0070] Step 2.4: For each image, the barycenter C of the terminal-sensitive bomb profile points is solved p The barycenter C of the terminal-sensitive bomb profile points is solved pAs the center of the circle, a scan line is constructed on the image to obtain the intersection of the scan line and the projectile contour. Each scan line will form two intersections with the projectile contour. The distance between the two intersections of each scan line is calculated. The scan line with the shortest distance is used as the reference scan line. The intersection points of the scan lines with an angle of ±45° with the reference scan line and the projectile contour are extracted as the final contour points. The contour points close to the left in the image are fitted to obtain the left edge line segment. Fit the contour points close to the right side of the image to obtain the right edge segment

[0071] The process of the steady-state scanning angle acquisition module solving the steady-state scanning angle of the terminal-sensitive projectile based on the geometric mapping relationship specifically includes the following steps:

[0072] Step 3.1: For each image, extract line segments separately and line segments midpoint Constructed with The midpoint of the line segment formed by the vertices is taken as the characteristic point a of the terminal-sensitive projectile axis p , and solve the feature point a p Image coordinates

[0073] Step 3.2: For each image, calculate the line segments Angle with the vertical axis of the image Calculating Line Segments Angle with the vertical axis of the image According to the plane geometry relationship, the angle between the axis of the terminal-sensitive projectile and the vertical axis of the image is

[0074] Step 3.3: Use the high-speed camera manual or camera calibration to obtain the pixel size dx, dy and focal length f of the high-speed camera. Based on the camera imaging principle, ray tracing method and geometric analysis method, solve the angle η corresponding to each image. p :

[0075]

[0076] Among them, β p , γ p , The three angles can be obtained by using the focal length f of the high-speed camera, the pixel size dx, dy, and the feature point a p Image coordinates Angle θ p The specific calculation method is as follows:

[0077]

[0078] Step 3.4: Calculate the angle η for all images pAn array K = {η1, η2,..., η p ,...,η P} is formed; all maximum values in the array K are extracted and averaged to obtain the steady-state scanning angle η of the terminal-sensitive projectile.

[0079] The steady-state scanning speed obtaining module obtains the steady-state scanning speed of the terminal-sensitive projectile based on an axis matching method, and the process specifically includes the following steps.

[0080] Step 4.1: For each image, the normalized direction vectors of the line segment and the line segment are calculated respectively.

[0081] Step 4.2: A basic unit vector is set as An axis matching factor ε is constructed using and the axis matching factor ε of each image is solved.

[0082] Step 4.3: The axis matching factors ε solved for all images p form an array ξ = {ε1, ε2,..., ε p ,...,ε P}; all minimum values in the array ξ are extracted, and the image sequence numbers corresponding to the minimum values are arranged in ascending order to form a new image frame sequence array Q = {q1, q2,..., q n ,...,q N};

[0083] Step 4.4: Using the new image frame sequence array, the real-time scanning speed v n and the average scanning speed

[0084]

[0085]

[0086] of the terminal-sensitive projectile are calculated. n The units of the real-time scanning speed v and the average scanning speed are r / s, and ΔT is the time interval between adjacent two images in image acquisition.

[0087] Embodiment 1

[0088] In this embodiment, the following is referred to Figure 1As shown, it is a flow chart for measuring the steady-state scanning parameters of the back light profile of the terminal-sensitive bomb, the terminal-sensitive bomb is located in the flow field of the vertical wind tunnel and is in the steady-state scanning state, the image acquisition control system is normally operated, and the high-speed camera is used to record the back light image sequence of the terminal-sensitive bomb in the steady-state scanning motion state;For each back light image, the terminal-sensitive bomb target is extracted from the image based on background subtraction, the sub-pixel edge extraction method is used to preprocess the terminal-sensitive bomb target in the image, and the terminal-sensitive bomb profile points are obtained;The left edge line segment and the right edge line segment are obtained by using the barycentric scanning line method to process the profile points;The terminal-sensitive bomb axis feature points are constructed by using the left and right edges of the terminal-sensitive bomb profile, and the image coordinates of the terminal-sensitive bomb axis feature points are solved;The angle between the terminal-sensitive bomb axis and the longitudinal axis of the image plane is calculated based on the geometric relationship of the image plane;The ray tracing method and the geometric analysis method are used to solve the steady-state scanning angle of the terminal-sensitive bomb;The axis matching factor epsilon is constructed by using the left and right edge direction vectors of the terminal-sensitive bomb and the basic unit direction vector, and the axis matching factor epsilon of each back light image is solved p , the minimum value of the matching factor epsilon p The image sequence number corresponding to the minimum value is used to solve the steady-state scanning speed of the terminal-sensitive bomb. The steady-state scanning angle and the steady-state scanning speed of the terminal-sensitive bomb can provide data basis for the design optimization and performance identification of the terminal-sensitive bomb.

[0089] Based on the steady-state scanning parameter measurement system, a terminal-sensitive bomb steady-state scanning parameter measurement method based on back light profile is provided, and the steady-state scanning parameter measurement method comprises the following steps:

[0090] Step 1: Establish a terminal-sensitive bomb steady-state scanning parameter back light measurement system, and use a high-speed camera to record a back light image sequence of the terminal-sensitive bomb in a steady-state scanning motion state;

[0091] Step 2: Extract the terminal-sensitive bomb profile edge features based on the barycentric scanning line method;

[0092] Step 3: Solve the steady-state scanning angle of the terminal-sensitive bomb based on the geometric mapping relationship;

[0093] Step 4: Solve the steady-state scanning speed of the terminal-sensitive bomb based on the axis matching method.

[0094] In step 1, the terminal-sensitive bomb steady-state scanning parameter back light measurement system is established, and image acquisition is completed, which is as follows:

[0095] As Figure 2As shown, the back light measurement system for establishing the steady-state scanning parameters of the terminal-sensitive projectile is established, a back light area is created behind the body of the terminal-sensitive projectile using an active light source, a high-speed camera is arranged at the same height as the terminal-sensitive projectile, the optical axis of the camera is ensured to be horizontal and orthogonal to the axis of the vertical wind tunnel, and the distance between the camera and the terminal-sensitive projectile is ensured to be greater than the virtual cone radius formed when the terminal-sensitive projectile rotates; the focal length and aperture of the camera are adjusted to ensure that the back light image of the terminal-sensitive projectile is clearly visible in the image of the camera, and the high-speed camera is used to record the back light image sequence P of the terminal-sensitive projectile in the steady-state scanning state.

[0096] In step 2, the edge features of the terminal-sensitive projectile are extracted based on the barycentric scanning line method, and the specific steps are as follows:

[0097] For each back light image, the terminal-sensitive projectile target is extracted from the image based on background subtraction, the sub-pixel edge extraction method is used to pre-process the terminal-sensitive projectile target in the image to obtain the profile points of the terminal-sensitive projectile body, and the barycentric scanning line method is used to process the profile points to obtain the left edge line segment and the right edge line segment.

[0098] In step 3, the steady-state scanning angle of the terminal-sensitive projectile is solved based on the geometric mapping relationship, and the specific steps are as follows:

[0099] The left and right edge profile of the terminal-sensitive projectile is used to construct the feature points of the axis of the terminal-sensitive projectile and solve the image coordinates thereof, the angle between the axis of the terminal-sensitive projectile and the longitudinal axis of the image plane is calculated based on the geometric relationship of the image plane, and the ray tracing method and the geometric analysis method are used to solve the steady-state scanning angle of the terminal-sensitive projectile.

[0100] In step 4, the steady-state scanning speed of the terminal-sensitive projectile is solved based on the axis matching method, and the specific steps are as follows:

[0101] The left and right edge direction vectors of the terminal-sensitive projectile and the basic unit direction vectors are used to construct the axis matching factor ε, and the axis matching factor ε of each back light image is solved p based on the minimum value of the matching factor ε p The image sequence number corresponding to the minimum value is used to solve the steady-state scanning speed of the terminal-sensitive projectile.

[0102] The step 2 specifically includes the following steps:

[0103] Step 2.1: using the back light image without the terminal-sensitive projectile as a background reference, for each image in the image sequence P, the absolute value of the difference between the gray value of each pixel point and the gray value of the corresponding pixel point of the background reference is calculated, and compared with the set threshold σ to obtain the binary image f(x, y, p) of each image:

[0104]

[0105] Where f(x,y,p) is the binary image of the p-th image, x,y are the 2D coordinate values ​​of the image pixels, I(x,y,p) is the grayscale value of the pixel at the (x,y) coordinate of the p-th image, I(x,y,0) is the grayscale value of the pixel at the (x,y) coordinate of the reference image, and σ is the set threshold;

[0106] Step 2.2: Perform morphological operations on each binary image and cluster it based on the four neighborhoods. Select the largest cluster to obtain the terminal-sensitive missile target image to be extracted;

[0107] Step 2.3: Use the sub-pixel edge extraction method to extract the edge of the terminal-sensitive missile target image extracted in step 2.2 to obtain the terminal-sensitive missile body contour points in each image;

[0108] Step 2.4: For each image, Figure 3 As shown, find the center of gravity C of the terminal sensitive projectile body contour point p , with the center of gravity C p As the center of the circle, a scan line is constructed on the image to obtain the intersection of the scan line and the projectile contour. Each scan line will form two intersections with the projectile contour. The distance between the two intersections of each scan line is calculated. The scan line with the shortest distance is used as the reference scan line. The intersection points of the scan lines with an angle of ±45° with the reference scan line and the projectile contour are extracted as the final contour points. The contour points close to the left in the image are fitted to obtain the left edge line segment. Fit the contour points close to the right side of the image to obtain the right edge segment

[0109] Wherein, the step 3 specifically includes:

[0110] Step 3.1: For each image, Figure 4 As shown, extract line segments respectively and line segments midpoint Constructed with The midpoint of the line segment formed by the vertices is taken as the characteristic point a of the terminal-sensitive projectile axis p , and solve the feature point a p Image coordinates

[0111] Step 3.2: For each image, calculate the line segments Angle with the vertical axis of the image Calculating Line Segments Angle with the vertical axis of the image From the plane geometry relationship, we can get the angle between the axis of the terminal-sensitive projectile and the vertical axis of the image.

[0112] Step 3.3: Obtain the pixel size dx, dy and focal length f of the high-speed camera by using the high-speed camera manual or camera calibration, and solve the angle η corresponding to each image based on the camera imaging principle, ray tracing method and geometric analysis method p :

[0113]

[0114] wherein β p , γ p , The three angles can be obtained by using the focal length f of the high-speed camera, the pixel size dx, dy, the image coordinates of the feature point a p The angle θ p is calculated, and the specific calculation method is as follows:

[0115]

[0116] Step 3.4: An array K = {η1, η2,..., η p ,...,η p} is formed by all the angles η P solved for all images; all maximum values in the array K are extracted and averaged, and the steady-state scanning angle η of the terminal-sensitive projectile is obtained.

[0117] The step 4 specifically comprises:

[0118] Step 4.1: For each image, the normalized direction vectors of the line segment and the line segment are calculated respectively

[0119] Step 4.2: Set the basic unit vector as The axis matching factor ε is constructed by using and the axis matching factor ε of each image is solved

[0120] Step 4.3: An array ξ = {ε1, ε2,..., ε p ,...,ε p} is formed by all the axis matching factors ε P solved for all images; all minimum values in the array ξ are extracted, and the image sequence numbers corresponding to the minimum values are arranged in ascending order to form a new image frame sequence array Q = {q1, q2,..., q n ,...,q N};

[0121] Step 4.4: The steady-state scanning real-time rotating speed v n and the average rotating speed ​

[0122] v n = 1 / ((q n - q n-2 ) x AT)

[0123]

[0124] wherein the real-time rotating speed v n and the average rotating speed are both in r / s, and AT is the time interval between two adjacent images in image acquisition.

[0125] A specific application example process is given below, and the effectiveness of the application in engineering application is verified:

[0126] The back light measurement system for the steady-state scanning parameters of the terminal-sensitive projectile is shown in Figure 2 ; the measurement object is the terminal-sensitive projectile body 8. The vertical wind tunnel 4 is normally operated and a stable flow field is established. The terminal-sensitive projectile body 8 is hung below the terminal-sensitive projectile parachute 7 and is in a steady-state scanning state in the flow field. The LED high-brightness light source 5 is normally operated and forms a back light area behind the terminal-sensitive projectile body. The image acquisition control system 3 controls the high-speed camera 2 to take pictures of the terminal-sensitive projectile body and the back light area to obtain a back light image sequence. In the test, the pixel size of the high-speed camera is 5.5 x 5.5 μm, the focal length is 35 mm, the resolution is 2048 x 1024, the sampling frequency is 450 Hz (frame frequency 450 fps), the sampling time is 4 s, and a total of 1800 images are recorded. The back light image sequence of the terminal-sensitive projectile is processed by using the solving method described in the application to obtain the steady-state scanning angle result curve as shown in Figure 6a , and the steady-state scanning rotating speed result curve as shown in Figure 6b . The minimum value of the steady-state scanning angle obtained by solving is 47.9°, the maximum value is 49.0°, and the average value is 48.47°. The maximum value of the steady-state scanning rotating speed obtained by solving is 10.1 r / s, the minimum value is 9.9 r / s, and the average value is 10.01 r / s. In order to verify the effectiveness of the method described in the application, the steady-state scanning parameter measurement results of the terminal-sensitive projectile under the same working condition are compared with the true value measured by the binocular vision measurement system with higher measurement accuracy. The average value of the steady-state scanning angle is 48.50°, and the average value of the steady-state scanning rotating speed is 10.00 r / s. Therefore, the measurement results of the steady-state scanning parameters of the terminal-sensitive projectile obtained by the method of the application have small errors compared with the actual values, which verifies the effectiveness of the method. The steady-state scanning parameter measurement results can provide data basis for the design optimization and performance identification of the terminal-sensitive projectile.

[0127] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present application, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A terminal-sensitive projectile steady-state scanning parameter measurement system based on backlight profile, characterized in that: The steady-state scanning parameter measurement system includes: a terminal-sensitive projectile steady-state scanning parameter backlight measurement system and a steady-state scanning parameter solution system; wherein the terminal-sensitive projectile steady-state scanning parameter backlight measurement system includes an active light source, a high-speed camera, and a vertical wind tunnel; the steady-state scanning parameter solution system includes an edge segment acquisition module, a steady-state scanning angle acquisition module, and a steady-state scanning speed acquisition module; The terminal-sensitive projectile steady-state scanning parameter backlight measurement system is used to record a backlight image sequence of a terminal-sensitive projectile in a steady-state scanning motion state using a high-speed camera; The edge segment acquisition module is used to extract the edge features of the terminal-sensitive projectile contour based on the centroid scanning line method; The steady-state scanning angle acquisition module is used to solve the steady-state scanning angle of the terminal-sensitive projectile based on the geometric mapping relationship; The steady-state scanning speed acquisition module is used to solve the steady-state scanning speed of the terminal-sensitive projectile based on the axis matching method.

2. The backlight profile-based terminal-sensitive projectile steady-state scanning parameter measurement system according to claim 1, characterized in that: In the terminal-sensitive projectile steady-state scanning parameter backlight measurement system, an active light source is used to create a backlight area behind the terminal-sensitive projectile body, a high-speed camera is arranged at the same height as the terminal-sensitive projectile, the camera optical axis is ensured to be horizontal and orthogonal to the incoming flow axis of the vertical wind tunnel, and the camera position is ensured to be much larger than the virtual cone radius formed when the terminal-sensitive projectile rotates; the camera focal length and aperture are adjusted to ensure that the backlight image of the terminal-sensitive projectile is clearly visible in the camera image, and the high-speed camera is used to record the backlight image sequence P of the terminal-sensitive projectile in the steady-state scanning motion state.

3. The backlight profile-based terminal-sensitive projectile steady-state scanning parameter measurement system according to claim 2, characterized in that: The process of extracting the edge features of the terminal-sensitive projectile contour based on the centroid scanning line method by the edge segment acquisition module is as follows: For each backlit image, the terminal-sensitive missile target is extracted from the image based on background subtraction, and the terminal-sensitive missile target in the image is preprocessed using the sub-pixel edge extraction method to obtain the terminal-sensitive missile body contour points; The centroid scanning line method is used to process the contour points to obtain the left edge segment and the right edge segment.

4. The backlight profile-based terminal-sensitive projectile steady-state scanning parameter measurement system according to claim 3, characterized in that: The process of the steady-state scanning angle acquisition module solving the steady-state scanning angle of the terminal-sensitive projectile based on the geometric mapping relationship is as follows: The terminal-sensitive projectile axis feature points are constructed using the left and right edges of the terminal-sensitive projectile contour and their image coordinates are solved. The angle between the terminal-sensitive projectile axis and the longitudinal axis of the image plane is calculated based on the geometric relationship of the image plane. The steady-state scanning angle of the terminal-sensitive projectile is solved using the ray tracing method and geometric analysis method.

5. The backlight profile-based terminal-sensitive projectile steady-state scanning parameter measurement system according to claim 4, characterized in that: The process of the steady-state scanning speed acquisition module solving the steady-state scanning speed of the terminal-sensitive projectile based on the axis matching method is as follows: The axis matching factor ε is constructed using the left and right edge direction vectors of the terminal-sensitive projectile and the basic unit direction vector, and the axis matching factor ε of each backlight image is solved. p , based on the matching factor ε p The image sequence number corresponding to the minimum value is used to solve the steady-state scanning speed of the terminal-sensitive projectile.

6. The backlight profile-based terminal-sensitive projectile steady-state scanning parameter measurement system according to claim 5, characterized in that: The process of extracting the edge features of the terminal-sensitive projectile contour based on the centroid scanning line method by the edge segment acquisition module specifically includes the following steps: Step 2.1: Using the backlit image without terminal sensitive projectiles as the background reference, for each image in the image sequence P, calculate the absolute value of the difference between the grayscale value of each pixel and the grayscale value of the corresponding pixel of the background reference, and compare it with the set threshold σ to obtain the binary image f(x, y, p) of each image: Where f(x,y,p) is the binary image of the p-th image, x,y are the 2D coordinate values ​​of the image pixels, I(x,y,p) is the grayscale value of the pixel at the (x,y) coordinate of the p-th image, I(x,y,0) is the grayscale value of the pixel at the (x,y) coordinate of the reference image, and σ is the set threshold; Step 2.2: Perform morphological operations on each binary image and cluster it based on the four neighborhoods. Select the largest cluster to obtain the terminal-sensitive missile target image to be extracted; Step 2.3: Use the sub-pixel edge extraction method to extract the edge of the terminal-sensitive missile target image extracted in step 2.2 to obtain the terminal-sensitive missile body contour points in each image; Step 2.4: For each image, find the center of gravity C of the terminal sensitive projectile body contour points p , with the center of gravity C p As the center of the circle, a scan line is constructed on the image to obtain the intersection of the scan line and the projectile contour. Each scan line will form two intersections with the projectile contour. The distance between the two intersections of each scan line is calculated. The scan line with the shortest distance is used as the reference scan line. The intersection points of the scan lines with an angle of ±45° with the reference scan line and the projectile contour are extracted as the final contour points. The contour points close to the left in the image are fitted to obtain the left edge line segment. Fit the contour points close to the right side of the image to obtain the right edge segment 7. The backlight profile-based terminal-sensitive projectile steady-state scanning parameter measurement system according to claim 6, characterized in that: The process of the steady-state scanning angle acquisition module solving the steady-state scanning angle of the terminal-sensitive projectile based on the geometric mapping relationship specifically includes the following steps: Step 3.1: For each image, extract line segments separately and line segments midpoint Constructed with The midpoint of the line segment formed by the vertices is taken as the characteristic point a of the terminal-sensitive projectile axis p , and solve the feature point a p Image coordinates Step 3.2: For each image, calculate the line segments Angle with the vertical axis of the image Calculating Line Segments Angle with the vertical axis of the image From the plane geometry relationship, we can get the angle between the axis of the terminal-sensitive projectile and the vertical axis of the image. Step 3.3: Use the high-speed camera manual or camera calibration to obtain the pixel size dx, dy and focal length f of the high-speed camera. Based on the camera imaging principle, ray tracing method and geometric analysis method, solve the angle η corresponding to each image. p : Among them, β p , γ p , The three angles can be obtained by using the focal length f of the high-speed camera, the pixel size dx, dy, and the feature point a p Image coordinates Angle θ p The specific calculation method is as follows: Step 3.4: Calculate the angle η for all images p The array K={η1,η2,...,η p ,...,η P }; Extract all the maximum values ​​in the array K and calculate the average value to obtain the steady-state scanning angle η of the terminal-sensitive projectile.

8. The backlight profile-based terminal-sensitive projectile steady-state scanning parameter measurement system according to claim 7, characterized in that: The process of the steady-state scanning speed acquisition module solving the steady-state scanning speed of the terminal-sensitive projectile based on the axis matching method specifically includes the following steps: Step 4.1: For each image, calculate the line segments separately and line segments The normalized direction vector Step 4.2: Set the base unit vector to use Construct the axis matching factor ε and solve the axis matching factor for each image Step 4.3: Calculate the axis matching factor ε for all images p The array ξ={ε1,ε2,...,ε p ,...,ε P Extract the image sequence numbers corresponding to all the minimum values ​​in the array ξ and arrange them in ascending order to form a new image frame sequence array Q = {q1, q2, ..., q n ,...,q N }; Step 4.4: Use the new image frame sequence array to calculate the real-time rotation speed v of the terminal-sensitive projectile in steady-state scanning n and average speed v n =1 / ((q n -q n-2 )×ΔT) Among them, the real-time speed v n and average speed The unit is r / s, and ΔT is the time interval between two adjacent images during image acquisition.

9. The backlight profile-based terminal-sensitive projectile steady-state scanning parameter measurement system according to claim 8, characterized in that: The system is suitable for steady-state scanning parameter measurement tests of terminal-sensitive projectiles in vertical wind tunnels, and can provide a data basis for the design and performance evaluation of terminal-sensitive projectiles.

10. The backlight profile-based terminal-sensitive projectile steady-state scanning parameter measurement system according to claim 8, characterized in that: The system uses background subtraction and sub-pixel edge extraction methods to obtain the contour points of the terminal sensitive projectile body, and effectively obtains edge line segment features based on the centroid scanning line method; The steady-state scanning angle of the terminal-sensitive projectile is solved based on image geometric relationships and spatial geometric mapping; the steady-state scanning speed of the terminal-sensitive projectile is solved based on axis matching; the system principle is simple and the solution efficiency is high, which effectively reduces the complexity and cost of the equipment, and at the same time streamlines the test process, which can effectively improve the measurement efficiency of the steady-state scanning parameters of the terminal-sensitive projectile.

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