A test device and method for testing the flight status of a projectile within a fixed space under the cover of a protective cabin.

Abstract

This invention discloses a testing device and method for testing the flight state of a projectile within a fixed space under the cover of a protective chamber. The device includes a target, a protective chamber, and a balanced gun. A test window is provided on one side of the protective chamber, and a high-speed camera is positioned directly in front of the test window. A first plane mirror and a second plane mirror are installed inside the protective chamber. The surface of the first plane mirror is parallel to the projectile's flight trajectory, while the surface of the second plane mirror is inclined to the projectile's flight trajectory. A positioning rod is installed between the test window and the high-speed camera. Based on this device, experiments show that the first plane mirror records a complete image of the entire projectile flight process, while the second plane mirror displays the entire image of the target and the projectile in the lower left corner of the mirror. The test results, which affect the interpretation of the projectile's flight state parameters before and after target entry, provide data reference for weapon penetration effect evaluation and are applicable to research related to weapon penetration effect testing and evaluation.

Description

Technical Field

[0001] This invention relates to the field of damage effect assessment technology, specifically to a test device and test method for testing the flight status of a projectile in a fixed space under the cover of a protective cabin. Background Technology

[0002] In weapon penetration effect tests, the testing of projectile flight parameters (pitch angle, yaw angle, impact velocity, impact acceleration, etc.) is a crucial step in evaluating penetration effectiveness. Currently, high-speed video recorders are commonly used to record the entire test scenario to aid in the analysis and judgment of the projectile's flight attitude. However, actual tests have revealed that when personnel or buildings are relatively close to the test area, target fragments, especially steel plate targets or projectile fragments, pose a significant threat of damage to surrounding personnel and buildings. Considering safety protection requirements, protective chambers can be used to cover the entire steel plate specimen for protection in actual tests. To meet observation needs, observation windows are generally reserved under protective chamber conditions to facilitate high-speed video recording. Considering the obstruction of the projectile's flight field of view by the protective chamber, how to complete the testing of the projectile's flight status, especially the parameters before and after impact, within a limited space has become an urgent problem to be solved. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a test device for the flight status of a projectile in a fixed space under the protection of a protective cabin. The device uses a high-speed camera and two plane mirrors to record images of the projectile and the target, and to assist in the analysis and judgment of the projectile's flight attitude.

[0004] The technical problem to be solved by the present invention is to provide a method for testing the flight state of a projectile in a fixed space under the shielding conditions of a protective cabin. This method can test the flight state parameters of the projectile before and after entering the target in a limited space, providing data reference for the evaluation of weapon penetration effect, and is applicable to research work related to the test evaluation of weapon penetration effect.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a projectile flight state testing device suitable for use in a fixed space under the protection of a protective cabin, comprising a target, a protective cabin, and a balanced gun. The protective cabin is fixedly attached to the target, and the projectile fired by the balanced gun passes through the protective cabin and hits the target. The protective cabin has an openable door on its front, with a semi-circular projectile flight hole at the top of the door. A test window is provided on one side of the protective cabin, and a high-speed camera is set in front of the test window. A first plane mirror and a second plane mirror are set inside the protective cabin. The first and second plane mirrors are placed on a metal bracket with an adjustable surface tilt angle. The mirror surface of the first plane mirror is parallel to the projectile flight trajectory, and the mirror surface of the second plane mirror is tilted to the projectile flight trajectory. A positioning rod is set between the test window and the high-speed camera, and the positioning rod is located on the edge of the high-speed camera's recording field of view, closer to the target.

[0006] To further limit the above scheme, the height of the test window is higher than the flight altitude of the projectile.

[0007] To further specify the above scheme, the surface of the projectile is coated with annular color bands of different intervals, and the width d of the color bands is not less than... Where v is the projectile's flight speed and f is the frame rate of the high-speed camera.

[0008] Further defining the above scheme, the width w of the first plane mirror satisfies w≥2d, and is used to project the attitude image of the flying projectile when it passes above the mirror surface. The edge of the first plane mirror is on the same plane as the projectile's flight trajectory, and the mirror surface of the first plane mirror is parallel to the projectile's flight trajectory and is placed at a certain angle θ with the ground. The angle θ satisfies... Where l1 is the length of the first plane mirror and h is the flight altitude of the projectile.

[0009] Further specifying the above scheme, the second plane mirror is placed near the valve side, and its width is sufficient to project the entire circular target area penetrated by the projectile into the mirror surface. The mirror surface of the second plane mirror forms an angle with the projectile's flight trajectory. It is placed at a certain angle ρ with respect to the ground. satisfy The included angle of inclination satisfies Where l is the length of the projectile and l′ is the length of the positioning line at the moment of penetration.

[0010] A test method for a projectile flight status test device applicable to a fixed space under protective cabin conditions, characterized by comprising the following steps:

[0011] (1) Adjust the recording view area of ​​the high-speed camera: Install the high-speed camera directly in front of the test window. The high-speed camera is placed in the center of the test window and its height is consistent with the center height of the test window. The distance between the high-speed camera and the test window is not less than 20m. Adjust the recording view area of ​​the high-speed camera to cover the test window. Install a positioning rod on the edge of the recording view area near the target on one side of the test window.

[0012] (2) Adjust the first plane mirror: Fix the first plane mirror on the metal bracket and adjust the tilt angle of the metal bracket to θ; according to the high-speed camera, positioning rod and projectile flight trajectory, calibrate the length l′ of the positioning line at the penetration moment and the reference position of the first plane mirror on the side closer to the target; the edge of the first plane mirror is on the same plane as the projectile flight trajectory, and the mirror surface of the first plane mirror is parallel to the projectile flight trajectory; calibrate the projection position of the projectile in the mirror when it passes the first plane mirror on the flight trajectory using a high-speed video recorder, and ensure that the projectile projection is in the middle position of the first plane mirror and remains horizontal;

[0013] (3) Adjust the second plane mirror: Fix the first plane mirror on the metal bracket and adjust the tilt angle of the metal bracket to ρ. At the same time, adjust the position of the metal bracket so that the mirror surface of the first plane mirror forms an angle with the trajectory of the projectile. Position the target so that the entire circular area at the center of the target is projected onto the second plane mirror;

[0014] (4) Projectile recording: Set the parameters of the high-speed camera and record the flight scene of the projectile according to the launch schedule;

[0015] (5) Determine the projectile's flight speed using the projection of the first plane mirror: Based on the high-speed video playback, determine that the first color band of the projectile requires a total of [m] photos from the start to the end of the distance d. The time t required for the projectile to fly this distance is calculated by the following formula.

[0016]

[0017] [·] is the rounding up sign, and f is the frame rate of the high-speed camera.

[0018] The average flight speed v1 of the projectile over this distance, as determined by the video recording, is...

[0019]

[0020] By analogy, the flight velocity of the projectile at different distances along the colored bands is determined, thus yielding the average flight velocity v of the projectile across multiple distances. n n is the number of colored stripes on the projectile;

[0021] (6) Determine the projectile attitude using the first plane mirror projection: Based on the high-speed video playback, determine the projectile image and obtain the two-dimensional coordinates (x1, y1) and (x2, y2) of the center points of the projectile tip and tail, as well as the projectile pitch angle φ and yaw angle. They can be calculated using the following formulas respectively.

[0022]

[0023]

[0024] l represents the length of the projectile; when φ > 0, the projectile is facing downwards; when φ < 0, the projectile is facing downwards.

[0025] (7) Using the second plane mirror projection to interpret the attitude change of the projectile during penetration: Obtain the two-dimensional coordinates (x3, y3) and (x4, y4) of the projectile body and tail through the image, and determine the projectile pitch angle during penetration. The projectile yaw angle Δρ can be calculated using the following formulas.

[0026]

[0027]

[0028] l″ represents the actual length of the projectile between the two points on the projectile body and the tail. At that time, the projectile was facing downwards; At that time, the projectile was facing downwards;

[0029] The projectile's flight velocity during penetration is determined using the method in step (5), and the acceleration is calculated by the change in velocity between two adjacent color bands.

[0030]

[0031] The above formula can be used to obtain the law governing the change of acceleration.

[0032] The beneficial effects of adopting the above technical solution are as follows: The testing device of the present invention has a protective chamber set in front of the target, and is equipped with a high-speed camera and two plane mirrors. The two plane mirrors are set at different angles to image the projectile and the target. The high-speed camera records the imaging process. The structure is simple and the recording is accurate.

[0033] The projectile flight state testing method of this invention can meet the testing requirements of projectile flight state, especially state parameters (pitch angle, yaw angle, target velocity, target acceleration, etc.) before and after target entry, in a fixed space under the condition of protective cabin shielding. The testing method is simple, easy to implement in engineering, and the auxiliary testing materials are inexpensive. It can provide relatively comprehensive test data reference for weapon penetration effect evaluation and is suitable for research work related to weapon penetration effect test evaluation. Attached Figure Description

[0034] Figure 1 This is a diagram showing the equipment layout of the present invention;

[0035] Figure 2 This is a schematic diagram of the installation structure of the protective cabin and the target;

[0036] Figure 3 This is the front view of the steel plate target;

[0037] Figure 4 This is a right view of the steel plate target;

[0038] Figure 5 This is a front view of the protective cabin;

[0039] Figure 6 This is the installation structure diagram of the first plane mirror;

[0040] Figure 7 This is a schematic diagram of the arrangement of the first and second plane mirrors from a top view.

[0041] Figure 8 This is a schematic diagram of the projectile's projection in the first plane mirror;

[0042] Figure 9 This is a schematic diagram of the projectile's projection in the second plane mirror;

[0043] Figure 10 This is a structural diagram of a metal support frame;

[0044] The components include: 1. Balanced gun, 2. High-speed camera, 3. Positioning rod, 4. Projectile, 5. Positioning line, 6. First plane mirror, 7. Second plane mirror, 8. Video recording area, 9. First projection of the projectile, 10. Second projection of the projectile, 11. Projection of the steel plate target, 12. Target, 13. Protective chamber, 14. Test window, 15. Projectile flight hole, 16. Valve, 17. Steel plate target, 18. Metal support. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0046] Appendix Figure 1 This is a schematic diagram of the layout of all equipment in the test method for the flight state of a projectile in a fixed space under the shielding condition of a protective cabin based on plane mirror imaging in this invention. (See attached diagram.) Figure 2-7 The device includes a target 12, a protective chamber 13, and a counterbalanced gun 1. The protective chamber 13 is fixedly attached to the target 12, and the projectile 4 fired from the counterbalanced gun 1 passes through the protective chamber 13 and hits the target 12. The structure of the protective chamber 13 is shown in the attached figure. Figure 5 As shown, the protective cabin 13 has an openable door 16 on the front, which facilitates the entry and exit of equipment and personnel. It is closed before the formal test to reduce the scattering of fragments. The top of the door 16 has a semi-circular projectile flight hole 15. The diameter of the hole is larger than the diameter of the projectile to facilitate the unobstructed flight of the projectile during the test.

[0047] As attached Figure 6-9 As shown, a first plane mirror 6 and a second plane mirror 7 are installed inside the protective cabin 13. The first plane mirror 6 and the second plane mirror 7 are placed on a metal bracket 18 with an adjustable surface tilt angle. The mirror surface of the first plane mirror 6 is parallel to the flight trajectory of the projectile 4, and the mirror surface of the second plane mirror 7 is tilted to the flight trajectory of the projectile 4. The width w of the first plane mirror 6 satisfies w≥2d, and it is used to project the attitude image of the projectile when it passes above the mirror surface. The edge of the first plane mirror 6 is on the same plane as the flight trajectory of the projectile. The mirror surface of the first plane mirror 6 is parallel to the flight trajectory of the projectile and is tilted at a certain angle θ with the ground. The tilt angle θ satisfies... Where l1 is the length of the first plane mirror 6, and h is the flight altitude of the projectile. The second plane mirror 7 is placed near the valve side, and its width is sufficient to project the entire circular target area penetrated by the projectile into the mirror surface. The mirror surface of the second plane mirror 7 forms an angle with the projectile's flight trajectory. It is placed at a certain angle ρ with respect to the ground. satisfy The included angle of inclination satisfies Where l is the length of the projectile and l′ is the length of the positioning line at the moment of penetration.

[0048] The surface of the projectile 4 in this invention is coated with annular colored bands at different intervals, and the width d of the colored bands is not less than Where v is the projectile's flight speed and f is the frame rate of the high-speed camera.

[0049] A test method for a projectile flight status test device suitable for use in a fixed space under protective cabin conditions includes the following steps:

[0050] (1) Adjust the recording view area of ​​the high-speed camera: Install the high-speed camera directly in front of the test window. The high-speed camera is placed in the center of the test window and its height is consistent with the center height of the test window. The distance between the high-speed camera and the test window is not less than 20m. Adjust the recording view area of ​​the high-speed camera to cover the test window. Install a positioning rod on the edge of the recording view area near the target on one side of the test window.

[0051] (2) Adjust the first plane mirror: Fix the first plane mirror on the metal bracket and adjust the tilt angle of the metal bracket to θ; according to the high-speed camera, positioning rod and projectile flight trajectory, calibrate the length l′ of the positioning line at the penetration moment and the reference position of the first plane mirror on the side closer to the target; the edge of the first plane mirror is on the same plane as the projectile flight trajectory, and the mirror surface of the first plane mirror is parallel to the projectile flight trajectory; calibrate the projection position of the projectile in the mirror when it passes the first plane mirror on the flight trajectory using a high-speed video recorder, and ensure that the projectile projection is in the middle position of the first plane mirror and remains horizontal;

[0052] (3) Adjust the second plane mirror: Fix the first plane mirror on the metal bracket and adjust the tilt angle of the metal bracket to ρ. At the same time, adjust the position of the metal bracket so that the mirror surface of the first plane mirror forms an angle with the trajectory of the projectile. Position the target so that the entire circular area at the center of the target is projected onto the second plane mirror;

[0053] (4) Projectile recording: Set the parameters of the high-speed camera and record the flight scene of the projectile according to the launch schedule;

[0054] (5) Determine the projectile's flight speed using the projection of the first plane mirror: Based on the high-speed video playback, determine that the first color band of the projectile requires a total of [m] photos from the start to the end of the distance d. The time t required for the projectile to fly this distance is calculated by the following formula.

[0055]

[0056] [·] is the rounding up sign, and f is the frame rate of the high-speed camera.

[0057] The average flight speed v1 of the projectile over this distance, as determined by the video recording, is...

[0058]

[0059] By analogy, the flight velocity of the projectile at different distances along the colored bands is determined, thus yielding the average flight velocity v of the projectile across multiple distances. n n is the number of colored stripes on the projectile;

[0060] (6) Determine the projectile attitude using the first plane mirror projection: Based on the high-speed video playback, determine the projectile image and obtain the two-dimensional coordinates (x1, y1) and (x2, y2) of the center points of the projectile tip and tail, as well as the projectile pitch angle φ and yaw angle. They can be calculated using the following formulas respectively.

[0061]

[0062]

[0063] l represents the length of the projectile; when φ > 0, the projectile is facing downwards; when φ < 0, the projectile is facing downwards.

[0064] (7) Using the second plane mirror projection to interpret the attitude change of the projectile during penetration: Obtain the two-dimensional coordinates (x3, y3) and (x4, y4) of the projectile body and tail through the image, and determine the projectile pitch angle during penetration. The projectile yaw angle Δρ can be calculated using the following formulas.

[0065]

[0066]

[0067] l″ represents the actual length of the projectile between the two points on the projectile body and the tail. At that time, the projectile was facing downwards; At that time, the projectile was facing downwards;

[0068] The projectile's flight velocity during penetration is determined using the method in step (5), and the acceleration is calculated by the change in velocity between two adjacent color bands.

[0069]

[0070] The law governing the change of acceleration can be obtained through formula (7).

[0071] Based on the aforementioned testing equipment and methods, the flight parameters (pitch angle, yaw angle, target velocity, target acceleration, etc.) of the projectile before and after target entry were tested. The testing process is as follows:

[0072] First, parameters were set and tests were conducted. The first plane mirror 6 was placed 1.5m away from the target, with its front end aligned with the ballistic trajectory in a vertical plane. The first plane mirror 6 was 1m wide and fixed to a bracket with an inclination angle θ = 45°. A high-speed video recorder 2 was used to calibrate the projected position of the projectile 4 as it passed the first plane mirror 6. The projectile's projection was positioned in the middle of the first plane mirror 6 and remained horizontal. The second plane mirror 7 was fixed to a bracket with an inclination angle ρ = 70°, forming an angle with the projectile's horizontal flight trajectory. Placement. Using a high-speed video recorder, adjust the second plane mirror 7 so that the circular area (circular radius equal to the projectile radius) at the target center (the center point of projectile penetration) and the 4m long projectile are fully projected onto the second plane mirror 7. The projectile is painted with alternating color stripes, each 50cm wide, for a total of 8 color stripes. The projectile's flight speed is set to 450m / s. The high-speed camera is set to capture 10,000 photos per second. Recording of the projectile's flight scene is conducted according to the launch schedule. After recording, the footage is played back and the test data is analyzed.

[0073] The test window of the protective cabin is 3m high and 4m wide. The missile's flight altitude is designed to be 2.5m. The missile is launched by a balanced cannon. The high-speed camera equipment is located outside the test window, 30m vertically away, and is placed in the center of the test window at the same height as the center of the test window.

[0074] Based on the field of view of the high-speed camera, a positioning rod is installed on the edge of the visible area near the target on one side of the test window. The vertical distance between the positioning rod and the test window is 5m, and the height of the positioning rod is 5m. Based on the high-speed camera, the positioning rod, and the trajectory, the length of the positioning line at the penetration moment is determined to be l′ = 1.5m. The first plane mirror is placed 1.5m away from the target on the side closest to it, with the front end of the first plane mirror in the same vertical plane as the trajectory. The first plane mirror is 1m wide and fixed on a bracket with an inclination angle θ = 45°. The projection position of the projectile in the first plane mirror as it passes through the first plane mirror on its flight trajectory is determined using a high-speed video recorder. The projectile's projection is positioned in the middle of the first plane mirror and remains horizontal.

[0075] The second plane mirror is fixed on a bracket with an inclination angle of ρ = 70°, forming an angle with the missile's flight trajectory (horizontal direction). Placement. By adjusting the second plane mirror using a high-speed video recorder, the circular area (circular radius equal to the projectile radius) of the target center (the center point of projectile penetration) and the 4m long projectile can be fully projected onto the second plane mirror.

[0076] The projectile is painted with alternating colored stripes, each 50cm wide, for a total of eight stripes. The projectile's flight speed is set to 450m / s. A high-speed camera is set to capture 10,000 images per second. The projectile's flight is recorded according to the launch schedule, and the recordings are then played back to analyze the test data.

[0077] Based on the above-mentioned parameters, a test was conducted. The test observed that the first plane mirror recorded a complete image of the entire flight process of the projectile, while the target and projectile images were displayed in the lower left corner of the second plane mirror.

[0078] The projectile's flight speed is determined by projecting the projectile onto the first plane mirror. Based on the high-speed video playback, 11 photos are needed to determine the first color band at a distance of 50cm. According to formulas (1) and (2), the average flight speed v1 of the projectile determined by the high-speed video at this distance is 454.5m / s, which is 1% different from the design speed.

[0079] The projectile's attitude is determined using the projection of the projectile onto the first plane mirror. Based on high-speed video playback, the two-dimensional coordinates of the projectile's tip and tail center points are obtained. The projectile's pitch angle φ = 0.3° and yaw angle are then calculated. It is evident that the missile's attitude shifted downwards during flight.

[0080] The attitude changes of the projectile during penetration are determined by projecting the projectile onto a second plane mirror. Two-dimensional coordinates of two points—the projectile body and the projectile tail (connected by a line parallel to the projectile's central axis)—are obtained from the image, and the projectile's pitch angle during penetration can be calculated. The projectile's yaw angle Δρ = 0.5°. This indicates that the projectile's attitude changes during hard penetration of the steel plate target.

[0081] During the penetration process, the projectile's flight speed is determined using the method in step (7), and the acceleration is calculated by the change in the speed of two adjacent color bands. Based on the image interpretation, the calculated flight speed and acceleration are shown in Table 1 below.

[0082] Table 1. Calculation results of velocity and acceleration

[0083] Ribbon 1 Ribbon 2 ribbon 3 ribbon 4 ribbon 5 Ribbon 6 Ribbon 7 ribbon 8 Speed ​​(m / s) 454.5 454.5 400.5 365 310 253 / / <![CDATA[Acceleration (m / s 2 )]]> 0 <![CDATA[-4.9×10 4 ]]> <![CDATA[-4.9×10 4 ]]> <![CDATA[-5×10 4 ]]> <![CDATA[-5.2×10 4 ]]> / /

[0084] As can be seen from the table above, during the projectile penetration process, the projectile velocity decreases only slightly in the initial stage, and then drops sharply as the projectile penetrates deeper into the target. However, because the generation of fragments, bright light, and smoke during projectile penetration obscures the latter half of the penetration process, data processing at the initial distance is more complete and reliable in actual tests. Data for the latter part cannot be quantitatively calculated and can only be qualitatively inferred. This phenomenon is consistent with the general rules of penetration tests.

[0085] The beneficial effects of adopting the above technical solution are as follows: The test method for projectile flight state in a fixed space under the shielding condition of a protective cabin proposed in this invention can meet the test requirements for projectile flight state parameters, especially the state parameters before and after target entry, in a fixed space under the shielding condition of a protective cabin. It is also applicable to the test under the condition of no protective cabin. The test method is simple, easy to implement in engineering, and the auxiliary test materials are inexpensive. It can provide relatively comprehensive test data reference for the evaluation of weapon penetration effect and is applicable to the research work related to the test evaluation of weapon penetration effect.

Claims

1. A test device for the flight status of a projectile within a fixed space under the protection of a protective chamber, comprising a target (12), a protective chamber (13), and a counterbalanced gun (1), wherein the protective chamber (13) is fixedly attached to the target (12), and the counterbalanced gun (1) fires a projectile (4) that passes through the protective chamber (13) and hits the target (12), characterized in that: The protective cabin (13) has an openable door (16) on the front, and a semi-circular projectile flight hole (15) is left at the top of the door (16). A test window (14) is opened on one side of the protective cabin (13). A high-speed camera (2) is set in front of the test window (14). A first plane mirror (6) and a second plane mirror (7) are set inside the protective cabin (13). The first plane mirror (6) and the second plane mirror (7) are placed on a metal bracket (18) with an adjustable surface tilt angle. The mirror surface of the first plane mirror (6) is set parallel to the flight trajectory of the projectile (4), and the mirror surface of the second plane mirror (7) is set at an angle to the flight trajectory of the projectile (4). A positioning rod (3) is set between the test window (14) and the high-speed camera (2). The positioning rod (3) is located on the edge line of the high-speed camera (2) recording area near the target (12).

2. The test equipment for testing the flight status of a projectile within a fixed space under the shielding conditions of a protective cabin, as described in claim 1, is characterized in that: The test window is at a height higher than the flight altitude of the projectile (4).

3. The test equipment for testing the flight status of a projectile within a fixed space under the cover of a protective cabin, as described in claim 1, is characterized in that: The surface of the projectile (4) is coated with annular colored bands at different intervals, and the width d of the colored bands is not less than Where v is the projectile's flight speed and f is the frame rate of the high-speed camera (2).

4. The test equipment for testing the flight status of a projectile within a fixed space under the cover of a protective cabin, as described in claim 3, is characterized in that: The width w of the first plane mirror (6) satisfies w≥2d and is used to project the attitude image of the flying projectile when it passes above the mirror surface. The edge of the first plane mirror (6) is on the same plane as the flight trajectory of the projectile. The mirror surface of the first plane mirror (6) is parallel to the flight trajectory of the projectile and is tilted at a certain angle θ with the ground. The tilt angle θ satisfies Where l1 is the length of the first plane mirror (6) and h is the flight altitude of the projectile.

5. The test equipment for testing the flight status of a projectile within a fixed space under the cover of a protective cabin, as described in claim 3, is characterized in that: The second plane mirror (7) is placed near the valve side, and its width is sufficient to project the entire circular target area penetrated by the projectile into the mirror surface. The mirror surface of the second plane mirror (7) forms an angle with the trajectory of the projectile. It is placed at a certain angle ρ with respect to the ground. satisfy The included angle of inclination satisfies Where l is the length of the projectile and l′ is the length of the positioning line at the moment of penetration.

6. A test method for a test device for testing the flight status of a projectile within a fixed space under the shielding conditions of a protective cabin, as described in claim 4 or 5, characterized in that: Includes the following steps (1) Adjust the recording view area of ​​the high-speed camera: Install the high-speed camera directly in front of the test window. The high-speed camera is placed in the center of the test window and its height is consistent with the center height of the test window. The distance between the high-speed camera and the test window is not less than 20m. Adjust the recording view area of ​​the high-speed camera to cover the test window. Install a positioning rod on the edge of the recording view area near the target on one side of the test window. (2) Adjust the first plane mirror: Fix the first plane mirror on the metal bracket and adjust the tilt angle of the metal bracket to θ; according to the high-speed camera, positioning rod and projectile flight trajectory, calibrate the length l′ of the positioning line at the penetration moment and the reference position of the first plane mirror on the side closer to the target; the edge of the first plane mirror is on the same plane as the projectile flight trajectory, and the mirror surface of the first plane mirror is parallel to the projectile flight trajectory; calibrate the projection position of the projectile in the mirror when it passes the first plane mirror on the flight trajectory using a high-speed video recorder, and ensure that the projectile projection is in the middle position of the first plane mirror and remains horizontal; (3) Adjust the second plane mirror: Fix the second plane mirror on the metal bracket and adjust the tilt angle of the metal bracket to ρ. At the same time, adjust the position of the metal bracket so that the mirror surface of the second plane mirror forms an angle with the trajectory of the projectile. Position the target so that the entire circular area at the center of the target is projected onto the second plane mirror; (4) Projectile recording: Set the parameters of the high-speed camera and record the flight scene of the projectile according to the launch schedule; (5) Determine the projectile's flight speed using the projection of the first plane mirror: Based on the high-speed video playback, it is determined that the first color band of the projectile requires a total of [m] photos from the start to the end of the distance d. The time t required for the projectile to fly this distance is calculated by the following formula. [·] is the rounding up sign, and f is the frame rate of the high-speed camera. The average flight speed v1 of the projectile over this distance, as determined by the video recording, is... By analogy, the flight velocity of the projectile at different distances along the colored bands is determined, thus yielding the average flight velocity v of the projectile across multiple distances. n n is the number of colored stripes on the projectile; (6) Determine the projectile attitude using the first plane mirror projection: Based on the high-speed video playback, determine the projectile image and obtain the two-dimensional coordinates (x1, y1) and (x2, y2) of the center points of the projectile tip and tail, as well as the projectile pitch angle φ and yaw angle. They can be calculated using the following formulas respectively. l is the length of the projectile; when φ > 0, the projectile is facing downwards. When φ < 0, the projectile is facing downwards; (7) Using the second plane mirror projection to interpret the attitude change of the projectile during penetration: Obtain the two-dimensional coordinates (x3, y3) and (x4, y4) of the projectile body and tail through the image, and determine the projectile pitch angle during penetration. The projectile yaw angle Δρ can be calculated using the following formulas. l″ represents the actual length of the projectile between the two points on the projectile body and the tail. At that time, the projectile was facing downwards; At that time, the projectile was facing downwards; The projectile's flight velocity during penetration is determined using the method in step (5), and the acceleration is calculated by the change in velocity between two adjacent color bands. The above formula can be used to obtain the law governing the change of acceleration.

Images