A polarized optical measurement system and method for dynamic response of a spring-mass system under high impact loads

Abstract

The application discloses a kind of high impact load under spring mass system dynamic response polarized optical measurement system and method, belong to optical measurement technical field, for analog launch load and service load etc. High impact load working condition of spring mass system, by constructing birefringent interference color feature unit on the surface of the base and mass block of spring mass system, using polarization dark field to filter background stray light, cooperate with high-speed camera, so that mass block presents as high-contrast color spot, through HSV color segmentation and relative displacement calculation based on motion coordinate system, the non-contact, clear and continuous measurement of millisecond transient displacement response of mass block is realized.The application effectively fills the experimental measurement blank of high overload dynamics, eliminates the interference of the increased mass caused by the introduction of sensor in contact measurement, and provides high-fidelity visual data support for the dynamic response research of spring mass system in high dynamic environment.

Description

Technical Field

[0001] This invention belongs to the fields of optical measurement technology and experimental mechanics testing technology, and in particular, it relates to a polarization optical measurement system and method for the dynamic response of a spring-mass system under high impact load. Background Technology

[0002] In the development of fuse safety systems for weapon systems, an inertial mechanical mechanism consisting of a spring and a mass block is typically used as the core logic element to achieve safety release and detonation control. Studying the dynamic response characteristics of this structure under launch and service drop conditions is crucial for evaluating the reliability and safety of the fuse system. However, accurately obtaining the transient displacement response curve of the internal mass block under such high impact load conditions faces three major challenges:

[0003] First, the internal motion process is difficult to measure. Fuses and similar spring-mass systems are usually encapsulated in a closed metal shell structure, and the motion state of the internal mass is invisible to external observers. Current research relies heavily on numerical calculations and simulation experiments of theoretical models, lacking direct experimental measurement data to support it, making it difficult to accurately reflect the complex nonlinear behaviors of the mass, such as friction, jamming, or abnormal rebound.

[0004] Second, the intervention error introduced by contact measurement methods cannot be ignored. Existing measurement methods mostly use accelerometers or displacement sensors directly mounted on the mass block. However, for precision inertial systems with small dimensions, the mass of the sensor itself and the tensile stiffness of the leads will significantly change the original mass distribution of the mass block and the natural frequency of the system. This "added mass effect" will lead to severe distortion of the measured dynamic response, making it impossible to reproduce the motion law of the system under real working conditions.

[0005] Third, the impact response process is extremely short, making transient capture very difficult. The dynamic response process under high-amplitude impact loads typically occurs within an extremely short time window of hundreds of microseconds to milliseconds. The mass block undergoes violent acceleration and displacement in a very short time, placing extremely high demands on the spatiotemporal resolution of the measurement system. Ordinary imaging equipment cannot meet the sampling requirements of such high-speed transient processes, and is prone to motion blur, frame loss, or artifacts, making it difficult to resolve clear and continuous motion trajectories.

[0006] Therefore, there is an urgent need for a non-contact measurement technology that can eliminate additional mass interference and has microsecond-level time resolution. Summary of the Invention

[0007] The purpose of this invention is to provide a polarization optical measurement system and method for the dynamic response of a spring-mass system under high impact loads, in order to solve the problems that traditional contact sensors are prone to detachment and introduce additional mass, leading to distortion of the dynamic response, and that the motion trajectory of the mass block is difficult to track accurately during high dynamic transient processes, in high impact load experiments such as simulated launch overload or service drop.

[0008] The technical solution to achieve the purpose of this invention is as follows:

[0009] A polarization optical measurement system for the dynamic response of a spring-mass system under high impact load includes an array light source, a polarizer, a spring-mass system, an impact loading device, and an analyzer arranged sequentially along the observation optical axis, as well as a high-speed camera.

[0010] The polarizer and analyzer are configured in an orthogonal polarization state, and the spring mass system to be tested is set between the polarizer and analyzer.

[0011] The impact loading device is used to provide an impact load to the spring mass system under test, driving the spring mass system to generate a load movement perpendicular to the observation optical axis;

[0012] The rigid support frame of the spring mass system under test has light-transmitting channels at its upper and lower ends, and reference feature units are provided on these two light-transmitting channels. The mass block of the spring mass system under test also has a light-transmitting channel, and a motion feature unit is provided on this light-transmitting channel. The reference reference feature unit and the motion feature unit exhibit different interference colors. The rigid support frame has a light-transmitting groove that covers the displacement stroke of the mass block and forms a polarized light transmission observation path with the aforementioned light-transmitting channels, so that the high-speed camera can capture the optical features of the mass block inside the spring mass system under test.

[0013] A high-speed camera is used to record a video stream of the entire process between the reference feature element representing the macroscopic motion of the rigid body support frame and the motion feature element representing the relative motion of the internal mass block.

[0014] A polarization optical measurement method for the dynamic response of a spring-mass system under high impact load includes:

[0015] First, we entered the experimental preparation stage. We turned on the area array light source and adjusted the polarizer and analyzer to the orthogonal extinction state to construct a nearly completely black dark field background. At the same time, we configured the high-speed camera to have a microsecond-level exposure time and a shooting frame rate of tens of thousands of frames per second, and put the high-speed camera in a trigger waiting state.

[0016] Then, the impact loading and dynamic response phase begins. The impact loading device is released to apply transient impact load to the rigid support frame of the spring-mass system, and the high-speed camera is simultaneously triggered to start recording images. The high-speed camera captures the video stream of the entire process of the reference feature unit and the motion feature unit, and transmits the video stream to the data processing subsystem for subsequent calculation.

[0017] The significant advantages of this invention compared to existing technologies are:

[0018] (1) Achieving in-situ measurement of quasi-zero added mass: Compared with pasted displacement sensors or other sensors, the present invention constructs optical features of quasi-zero added mass on the mass block, which effectively avoids the interference of sensor mass and lead wire pull on the dynamic characteristics of the mass block, and ensures that the recorded trajectory truly reflects the original response state of the mass block under impact load.

[0019] (2) Achieving accurate capture and reconstruction of high-dynamic motion trajectories: For the transient nonlinear motion exhibited by the spring-mass system under high impact loads, traditional visual measurements often result in blurred feature edges due to metallic reflection and high-speed motion blur, leading to broken or distorted trajectories. This invention significantly improves the image signal-to-noise ratio by combining polarized dark fields and birefringence feature units, making the mass block appear as a bright, clearly defined color block under microsecond-level exposure. This high-contrast feature ensures that the algorithm can still stably lock the center under limited sampling rates, thereby accurately reproducing the high-dynamic displacement response details of the mass block within an extremely short time window, generating continuous, smooth, and realistic motion trajectories.

[0020] (3) Effective elimination of rigid body displacement interference: Considering the structural characteristics of the spring-mass system, which consists of a base and a mass block, after the impact load is applied, the base usually undergoes violent large-displacement rigid body motion following the impact loading device. This invention utilizes the reference feature unit on the base to establish a motion coordinate system, automatically converting the absolute displacement of the mass block into a relative displacement relative to the base. This mechanism effectively filters out the overall rigid body displacement interference caused by impact vibration, directly outputting the accurate motion trajectory of the mass block relative to the base, allowing for intuitive evaluation of the reliability of the mass block's action without complex post-processing. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of a polarization optical measurement system for the dynamic response of a spring-mass system under high impact load, as described in this invention.

[0022] Figure 2 This is a schematic diagram comparing the structures of the fully transparent mass block and the opaque mass block used to construct birefringent feature units in this invention.

[0023] Figure 3This is a schematic diagram of the two-degree-of-freedom recoil inertia safety mechanism in Embodiment 1 of the present invention;

[0024] Figure 4 This is a schematic diagram showing the disassembly of the components and the layout of the optical feature units of the two-degree-of-freedom recoil inertia safety mechanism in Embodiment 1 of the present invention;

[0025] Figure 5 This is a schematic cross-sectional view of the two-degree-of-freedom recoil inertia safety mechanism in Embodiment 1 of the present invention;

[0026] Figure 6 This is a schematic diagram illustrating the principle of two-point mutual calibration and motion coordinate system establishment based on a fixed physical center distance in Embodiment 1 of the present invention.

[0027] Figure 7 This is a schematic diagram of the zigzag groove rear seat inertia safety mechanism in Embodiment 2 of the present invention;

[0028] Figure 8 This is a schematic diagram of the layout of the mechanical feature units of the tortuous groove rear seat inertial safety mechanism in Embodiment 2 of the present invention;

[0029] Figure 9 This is a schematic diagram illustrating the principle of establishing the motion coordinate system of the zigzag groove rear seat inertial safety mechanism in Embodiment 2 of the present invention.

[0030] Figure 10 This is a flowchart of a polarization optical measurement method for the dynamic response of a spring-mass system under high impact load in this invention.

[0031] Figure 11 This is a flowchart of the image processing algorithm based on two-point mutual calibration dynamic calibration in an embodiment of the present invention. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] Combination Figure 1 This embodiment provides a polarization optical measurement system for the dynamic response of a spring-mass system under high impact load. The system mainly consists of a planar array light source 1, a polarizer 2, a spring-mass system under test 3, an analyzer 5, and a high-speed camera 6, arranged sequentially along the observation optical axis. In this system, the observation optical axis is jointly established by the line connecting the geometric center of the polarizer 2 and the lens center of the high-speed camera 6. The spring-mass system under test 3 is mounted on an impact loading device 4, which provides the impact load without obstructing the observation optical axis. Spatially, the spring-mass system under test 3 is oriented so that the direction of the light-transmitting groove of the spring-mass system 3 is strictly collinearly aligned with the observation optical axis, thereby forming a transmission optical path and ensuring that the linearly polarized light passing through the polarizer 2 can perpendicularly penetrate the interior of the spring-mass system 3. The high-speed camera 6 is electrically connected to a data processing subsystem 7.

[0034] In this embodiment, the area array light source 1 is a high-uniformity LED backlight source used to provide stable back illumination. The polarizer 2 and the analyzer 5 are configured in an orthogonal polarization state, that is, the angle between their transmission directions is 90°, thereby constructing a nearly completely extinct dark field background in the field of view of the high-speed camera 6 to effectively filter out non-polarized ambient stray light.

[0035] Regarding the selection of the impact loading device 4, this embodiment uses a Marshall hammer. The reason for choosing this device is that this embodiment aims to measure the dynamic response of the spring-mass system under simulated firing and service drop environments, that is, to simulate the dynamic response of the spring-mass system under different combinations of loads and pulse widths. Specifically, in real weapon operating conditions, the environmental mechanical parameters vary greatly: the firing load of small-caliber projectiles is typically as high as 30,000g to 110,000g, with a pulse width of approximately 3ms to 7ms; the firing load of medium and large-caliber projectiles is typically 1,000g to 30,000g, with a pulse width of approximately 1.4ms to 8ms; while the service load simulating accidental drops and impacts during the service phase is typically 5,000g to 20,000g, accompanied by an extremely short pulse width of 0.1ms to 0.3ms. The Marshall hammer possesses an extremely wide range of impact waveform adjustment capabilities. By adjusting the drop height and the stiffness and material of the buffer pad, it can generate both low-amplitude, long-pulse-width half-sine waves to accurately reproduce the recoil overload during launch, and high-amplitude, short-pulse-width impact pulses to simulate accidental drops and impacts during the operational phase. The shock wave generated by the device propagates along the preset motion axis of the internal mass block, driving the spring-mass system 3 to generate a high impact load motion perpendicular to the observation optical axis, thereby ensuring a high degree of consistency between the experimental loading conditions and the actual launch conditions.

[0036] Regarding the configuration of the high-speed camera 6, to address the challenge of capturing highly dynamic transient processes, the high-speed camera 6 is configured with a shooting frame rate of tens of thousands of frames per second, and the exposure time is strictly controlled at the microsecond level. This low exposure time setting effectively eliminates blurring caused by high-speed motion, ensuring that the feature edges in each frame are clear and sharp, thereby achieving accurate capture of transient trajectories within hundreds of microseconds to milliseconds.

[0037] Example 1:

[0038] Combination Figure 3 , Figure 4 and Figure 5The tested spring mass system described in this embodiment is a typical dual-degree-of-freedom recoil inertia safety mechanism for a fuse. This mechanism utilizes recoil inertia to disarm under launch overload conditions, while simultaneously ensuring safety under drop inertia through the coupled motion characteristics of the two mass blocks. The tested spring mass consists sequentially of an end cap 302, an upper mass block 305, an upper return spring 306, a lower mass block 307, a lower return spring 309, and a base 310. The end cap 302 is rigidly connected to the upper end of the base 310 via four sets of screws 301, together forming the rigid support frame of the system. This rigid support frame is rigidly fixed to the impact loading device by screws, with no relative displacement. In terms of internal structural fit, the base 310 has a guide hole 314 inside. The upper mass block 305, the lower mass block 307, and the return springs 306 and 309 are all coaxially assembled along the central axis of the guide hole 314. Due to the radial constraint of the guide hole 314 wall, they can only move in a straight line. At the same time, the inner end face of the end cap 302 and the bottom inner wall of the base 310 respectively form the physical limit boundaries of the upper and lower strokes, jointly limiting the maximum relative displacement of the internal mass blocks. When the system is subjected to a high amplitude impact load, the internal upper mass block 305 and lower mass block 307, under the action of inertial force, overcome the preload force and frictional resistance of the return springs 306 and 309, and generate a relative displacement response relative to the base 310 along the central axis of the guide hole 314.

[0039] To achieve non-destructive observation of the motion of the internal enclosed mass blocks, this embodiment constructs an optical channel running along the central axis of the guide inner hole 314. Specifically, light-transmitting channels 311 and 316 are respectively provided on the end cap 302 and the base 310, and corresponding light-transmitting channels 312 and 313 are also provided inside the upper and lower mass blocks. In particular, a light-transmitting groove 315 is formed in the base 310 along the central axis of the guide inner hole 314, and the length of the light-transmitting groove 315 covers the theoretical full displacement stroke of the two mass blocks. The central vertical line connecting the aforementioned light-transmitting channels 311, 312, 313, 316 and the light-transmitting groove 315 is arranged along the central axis of the guide inner hole 314, together forming a complete polarized light transmission observation path, ensuring that the high-speed camera can clearly capture the optical characteristics of the mass blocks through the base and internal components throughout the entire dynamic response process.

[0040] To address the issue of added mass introduced by traditional contact measurement methods, this embodiment employs a near-zero added mass optical feature unit layout. Specifically, a birefringent film is attached to one end of the light-transmitting channel 311 on the end cap 302 and the light-transmitting channel 316 at the bottom of the base 310 to construct a set of relatively stationary reference feature units 303 for defining the motion coordinate system. The line connecting the centers of the two reference feature units 303 is parallel to the central axis of the guide inner hole 314. A birefringent film is attached to one end of the light-transmitting channel 312 of the upper mass block 305 as an upper motion feature unit 304; and a birefringent film is attached to one end of the light-transmitting channel 313 of the lower mass block 307 as a lower motion feature unit 308. In the orthogonally polarized dark field, the aforementioned reference feature unit 303, upper motion feature unit 304, and lower motion feature unit 308 exhibit different interference colors due to differences in bonding angle or material thickness, and all appear as high-contrast colored stripe spots. Meanwhile, the base 310 remains dark in the orthogonally polarized light field, forming a significant grayscale contrast with the feature units that exhibit bright interference colors. This effectively suppresses background noise, achieves high signal-to-noise ratio feature extraction, and facilitates subsequent high-precision motion tracking and data processing.

[0041] Example 2:

[0042] like Figure 7 and Figure 8 As shown, the tested spring mass system is a typical zigzag groove rear seat inertia safety structure. This structure mainly consists of a rear support 801, a front support 805, and a base 806, forming a rigid support base for the system. In specific assembly, the rear support 801 and the front support 805 are vertically fixed to the base 806 by fastening screws, and the three together form a structurally stable rigid support frame without relative displacement.

[0043] Regarding internal mechanisms and motion constraints, the structure is equipped with a return spring 802 and a mass block 803 with a zigzag groove. Two spring positioning holes are respectively provided on the inner top of the rear support 801 and the top end face of the mass block 803. Two return springs 802 are coaxially assembled with the positioning holes, elastically suspending and supporting the mass block 803 below the rear support 801. In terms of spatial freedom constraints, the mass block 803 is clamped and assembled between the front support 805 and the rear support 801, with the inner walls of the front and rear supports forming a physical limit, thus completely restricting the translation of the mass block 803 along the observation optical axis. This ensures that the mass block 803 is strictly constrained to move within a preset two-dimensional plane parallel to the vertical plane of the support. Simultaneously, the zigzag groove on the mass block 803, in conjunction with a guide pin, further restricts the displacement of the mass block along the direction perpendicular to the observation optical axis. To further ensure the stability of the motion within the two-dimensional plane, the rear support 801 is provided with a guide groove 811 along the spring axis, and the mass block 803 is placed within the guide groove 811. The rigid restraint of the guide groove 811 sidewall effectively limits the translation and oscillation of the mass block 803 within the guide groove plane in a direction perpendicular to the spring axis.

[0044] Specifically, the front support 805 and the rear support 801 are provided with coaxial positioning holes. A guide pin 804, which is a smooth cylindrical shaft with threads at both ends, arranged parallel to the direction of the observation optical axis, passes sequentially through the positioning hole of the front support 805, the beveled groove of the mass block 803, and the positioning hole of the rear support 801. The two ends of the guide pin 804 protrude from the outer surfaces of the front support 805 and the rear support 801, respectively, and are rigidly fixed at both ends by nuts, so that the smooth cylindrical pin in the center is stably placed horizontally in the beveled groove. In the initial static state, under the preload of the return spring 802 along the spring axis, the bottom end of the beveled groove of the mass block 803 remains tangentially fitted with the guide pin 804. When the system is subjected to a high-amplitude impact load along the spring axis, the mass block 803 overcomes the spring resistance and generates a relative displacement along the spring axis. During this process, the fixed guide pin 804 slides relative to the downward-moving tortuous groove. The complex geometric tooth profile of the tortuous groove hinders and guides the movement of the mass block 803 along the spring axis, thereby consuming the impact energy and achieving a specific safety function.

[0045] To transform the complex dynamic response of the tortuous groove structure into an observable polarized interference spot, a light-transmitting channel was designed into the structure. Specifically, light-transmitting channels 807 and 809 are respectively provided on the top of the rear support 801 and the base 806; a light-transmitting channel 808 is provided on the mass block 803; and to accommodate the dynamic displacement stroke of the mass block 803, a through-hole light-transmitting groove 812 is provided on the main body of the rear support 801 along the spring axis. In terms of feature unit layout, a birefringent film is attached to one end of the light-transmitting channel 807 of the rear support 801 and the light-transmitting channel 809 of the base 806, forming a set of spatially stationary reference feature units 810; a birefringent film is attached to one end of the light-transmitting channel 808 of the mass block 803 to construct a moving reference feature unit 813. During experimental observation, the light beam passes through the light-transmitting groove 812 and the thin film of each feature unit, forming a high-contrast colored interference spot in the orthogonally polarized dark field. This enables high-precision optical tracking of the nonlinear coupled motion inside the zigzag groove without damaging the original mechanical state of the mechanism.

[0046] After the system assembly and feature unit layout are completed, the overall dynamic observation workflow is as follows:

[0047] First, we enter the experimental preparation stage. We turn on the light source 1 and adjust the polarizer 2 and analyzer 5 to the orthogonal extinction state to construct a nearly completely black dark field background. At the same time, we configure the high-speed camera 6 with a microsecond-level exposure time and a shooting frame rate of tens of thousands of frames per second, and put the high-speed camera 6 into a trigger waiting state.

[0048] The system then enters the impact loading and dynamic response phase. The impact loading device 4 is released, applying a transient high-amplitude impact load to the rigid support frame of the spring-mass system 3, and simultaneously triggering the high-speed camera 6 to begin recording images. Within this extremely short impact loading window, the system base undergoes violent overall high-acceleration rigid body movement and slight deflection along with the test bench; at the same time, under the action of huge transient inertial forces, the internal mass overcomes the frictional resistance of the return spring and mechanism, and moves at extremely high speed relative to the base along a preset motion path.

[0049] Throughout the physical response process, the polarized beam continuously penetrates the light-transmitting channels of the base and the mass block. Accompanying the high-speed relative displacement of the internal mass block, the motion feature units on the attached mass block are illuminated in the orthogonally polarized dark field, appearing as a stream of bright, colored interference spots that continuously move along the trajectory of the internal mechanism. The high-speed camera 6 fully captures the entire process of the reference feature unit representing the macroscopic motion of the base and the motion feature units representing the relative motion within the interior, transmitting the high-frame-rate video stream to the data processing subsystem 7 for subsequent processing.

[0050] Combination Figure 10 and Figure 11 The data processing subsystem 7 receives the video stream transmitted by the high-speed camera 6 and performs processing according to the following steps:

[0051] Step S1: Dynamic Background Subtraction and Morphological Denoising. First, N still images are acquired before the impact begins, and the pixel mean is calculated to construct a static background model. During the motion of the spring-mass system 3, each current image is compared with the static background model using absolute difference to eliminate background interference that does not change over time. Subsequently, the difference image is binarized, and morphological opening operations (erosion followed by dilation) are applied to effectively remove isolated noise points caused by ambient light flicker, extracting a high signal-to-noise ratio moving foreground mask containing only birefringent feature unit spots.

[0052] Step S2: Feature Segmentation and Center Extraction Based on HSV Space. First, using the captured 2D image as a reference, the pixel at the top left corner of the image is set as the absolute origin, the horizontal direction to the right is the positive global X-axis, and the vertical direction downwards is the positive global Y-axis, thus establishing a global absolute coordinate system. Then, the masked image data is mapped from the RGB color space to the HSV color space. Utilizing the characteristic that interference colors are insensitive to light intensity, specific hue threshold ranges are set for the reference feature unit and the motion feature unit respectively to achieve semantic segmentation of the region. For each effective connected component after segmentation, let the coordinates of the effective pixels within the connected component in the global absolute coordinate system be (x, y), and the corresponding binarized pixel value be I(x, y). Pixel values ​​in the target region belonging to the feature unit spot are set to 1, and those in the background region are set to 0. Using the image moment algorithm, the zeroth moment m of each connected component is calculated. 00 First moment m in the X direction 10 With the first moment m in the Y direction 01 The discrete calculation formulas are as follows: , , Subsequently, the center coordinates (x, y) of the connected domain of the target feature unit are calculated by using the ratio of the first moment to the zeroth moment. c ,y c The solution formula is: , By iterating through the above formula, the absolute coordinates P of the two centers of the reference feature element can be obtained accurately and synchronously. ref1 (x1,y1) and P ref2 (x2, y2), and the absolute coordinates (x3, y3) of the center of the motion feature unit.

[0053] Step S3: Construction of the motion coordinate system. After extracting the absolute coordinates of each feature unit, a motion coordinate system is constructed based on these coordinates. For example... Figure 6 and Figure 9 Set the center P of the lower reference feature element of the spring mass system 3. ref1 Let O' be the origin of the motion coordinate system, and let P be the center P of the reference feature element pointing upwards from this origin. ref2 The direction of the Y-axis is positive, and the direction from the center of the lens of the high-speed camera 6 to the measured spring-mass system 3 is positive, which is the Z-axis. Based on this, in the two-dimensional observation plane perpendicular to the Z-axis, a straight line passing through the origin O' and orthogonal to the Y-axis is defined as the X-axis, and the positive direction of the X-axis is determined strictly according to the three-dimensional Cartesian right-hand rule. When processing each frame of transient image, the system redetermines the origin and spatial axis of the motion coordinate system based on the real-time absolute coordinates of the center of the reference feature unit extracted in step S2. Since the motion coordinate system maintains synchronous translation and in-plane micro-rotation with the base, when the motion coordinates of the mass block are calculated in this coordinate system, the macroscopic rigid body motion disturbance of the base as a whole is naturally filtered and canceled in the coordinate transformation, thereby directly extracting the pure high-fidelity relative displacement response.

[0054] Step S4: Two-point mutual calibration dynamic calibration. In each frame of the image, based on the absolute coordinates P of the two centers of the reference feature unit obtained in step S2... ref1 (x1,y1) and P ref2 (x2, y2), the two centers P of the real-time calculation reference feature element. ref1 With P ref2 The Euclidean distance D between them pixel1 , Combined with the preset physical center distance D between the two reference feature elements. real1 Using the formula λ = D real1 / D pixel1 The current dynamic pixel equivalent λ is calculated in real time, in mm / pixel. This step automatically compensates for scale drift caused by light source flicker, light spot edge erosion, or minor camera vibrations, ensuring measurement accuracy. The specific implementation mechanism of the two-point mutual calibration and automatic compensation is as follows: In high-impact environments, light source flicker, light spot edge halo effects, or minor camera vibrations can cause global false scaling of the image, i.e., scale drift. This step abandons the traditional single fixed scale calibration, and instead uses the dynamically calculated pixel equivalent λ for each frame as the dynamic scale, directly substituting it into the physical displacement calculation of the target motion feature unit in the current frame. Through this frame-by-frame refresh calibration method, global optical distortion errors are naturally canceled out in the pixel-to-physical scale multiplication conversion, thereby achieving automatic compensation for measurement errors and ensuring measurement accuracy under high dynamic response.

[0055] Step S5: Trajectory Calculation and Physical Quantity Output. Combining the high-speed camera's set frame rate f and the current image's frame sequence number n, the actual physical time t corresponding to the current frame is calculated synchronously according to the formula t = n / f. Based on the absolute coordinates P of the two centers of the reference feature unit at time t of the current frame extracted in Step S2... ref1 (x1,y1) and P ref2 (x2, y2) and the absolute coordinates (x3, y3) of the motion feature unit are used. Then, using a two-dimensional rigid body coordinate transformation matrix composed of translation vectors and rotation matrices, the absolute coordinates of the motion feature unit are projected onto the motion coordinate system established in step S3. Specifically, firstly, according to P... ref1 (x1,y1) and P ref2 The coordinate difference of (x2, y2) and Combined with the Euclidean distance D between the two centers obtained in step S4 pixel1 Extract the sine and cosine components of the deflection angle θ of the moving coordinate system relative to the global absolute coordinate system, i.e. and Then, the relative coordinates (x, y) of the current frame after removing base pose interference are calculated according to the following matrix formula. t ,y t ):

[0056]

[0057] In the matrix operations described above, the coordinate difference operation on the right side dynamically anchors the origin of the coordinate system to the base P. ref1 Translation compensation at (x1, y1); the rotation matrix multiplication operation on the left side achieves rotation compensation to counteract the overall rigid body deflection of the base. Extract the relative coordinates (x1, y1). t ,y t The pixel displacement increments Δx along the local X and Y axes are obtained by subtracting the relative coordinates (x0, y0) at rest at time t0 before the initial impact. t with Δy t Subsequently, the pixel displacement increment is multiplied by the pixel equivalent λ at time t. t That is, according to formula S xt = Δx t × λ t With S yt = Δy t ×λ t S xt S represents the actual physical displacement of the mass block along the X-axis at time t. ytThe actual physical displacement of the mass block along the Y-axis at time t is represented by this formula, accurately mapping the abstract image pixel scale to the real mechanical spatial physical scale. The final output is the relative motion trajectory and displacement-time curve of the mass block relative to the base over time.

[0058] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A polarization optical measurement system for the dynamic response of a spring-mass system under high impact load, characterized in that, It includes a planar array light source, a polarizer, a spring mass system, an impact loading device, and an analyzer arranged sequentially along the observation optical axis, as well as a high-speed camera; The polarizer and analyzer are configured in an orthogonal polarization state, and the spring mass system to be tested is set between the polarizer and analyzer. The impact loading device is used to provide an impact load to the spring mass system under test, driving the spring mass system to generate a load movement perpendicular to the observation optical axis; The rigid support frame of the spring mass system under test has light-transmitting channels at its upper and lower ends, and reference feature units are provided on these two light-transmitting channels. The mass block of the spring mass system under test also has a light-transmitting channel, and a motion feature unit is provided on this light-transmitting channel. The reference reference feature unit and the motion feature unit exhibit different interference colors. The rigid support frame has a light-transmitting groove that covers the displacement stroke of the mass block and forms a polarized light transmission observation path with the aforementioned light-transmitting channels, so that the high-speed camera can capture the optical features of the mass block inside the spring mass system under test. A high-speed camera is used to record a video stream of the entire process between the reference feature element representing the macroscopic motion of the rigid body support frame and the motion feature element representing the relative motion of the internal mass block.

2. The polarization optical measurement system according to claim 1, characterized in that, The high-speed camera is electrically connected to the data processing subsystem; the data processing subsystem processes the video stream acquired by the high-speed camera to obtain the relative motion trajectory and displacement-time curve of the mass block relative to the rigid support frame over time.

3. The polarization optical measurement system according to claim 1, characterized in that, The solution process includes dynamic background subtraction and morphological denoising to obtain a moving foreground mask, mapping the masked image data from the RGB color space to the HSV color space, performing semantic segmentation on the moving feature units, using the image moment algorithm to obtain the center coordinates of the moving feature units, identifying the reference feature units based on the foreground mask and establishing a motion coordinate system using the center coordinates of the reference reference feature units. Calculate the dynamic pixel equivalent, and based on the dynamic pixel equivalent, convert the coordinate change of the center coordinate of the motion feature unit in the motion coordinate system into the actual physical displacement, and finally output the relative motion trajectory and displacement-time curve of the mass block.

4. The polarization optical measurement system according to claim 3, characterized in that, The process of establishing the motion coordinate system includes: taking the center of the lower reference feature unit as the origin O' of the motion coordinate system, taking the direction from the origin to the center of the upper reference feature unit as the positive Y-axis, taking the direction from the center of the high-speed camera lens to the spring mass system under test as the positive Z-axis, defining the straight line passing through the origin O' and orthogonal to the Y-axis as the X-axis to establish a three-dimensional rectangular coordinate system. When processing each frame of transient image, the origin and spatial axis of the motion coordinate system are re-determined based on the real-time center coordinates of this set of reference feature units.

5. The polarization optical measurement system according to claim 3, characterized in that, The actual physical displacement includes the displacement along the X-axis and the displacement along the Y-axis, including: Extract the relative coordinates (x, y) of the center of the motion feature unit on the mass block at time t in the motion coordinate system. t ,y t The pixel displacement increments Δx along the X and Y axes are obtained by subtracting the relative coordinates (x0, y0) at rest at time t0 before the initial impact. t with Δy t Subsequently, the pixel displacement increment is multiplied by the pixel equivalent λ corresponding to the current time. t The displacement along the X-axis and the actual physical displacement along the Y-axis are obtained as follows: S xt = Δx t × λ t ;S yt = Δy t ×λ t ; λ t Let λ be the dynamic pixel equivalent at time t. t = D real1 / D pixel1 ; Δx t with Δy t The relative coordinates (x) of the current frame t ,y t The pixel displacement increments along the local X and Y coordinate axes are obtained by subtracting the relative coordinates (x0, y0) at rest at time t0 before the initial impact; θ is the deflection angle of the motion coordinate system relative to the global absolute coordinate system, (x3, y3) are the absolute coordinates of the center of the motion feature unit, and D real1 D is the physical center distance between two reference feature elements. pixel1 This is the Euclidean distance between the centers of two reference feature units, calculated in real time in the global absolute coordinate system. The positive X-axis of the global absolute coordinate system is along the horizontal direction to the right of the image, and the positive Y-axis is along the vertical direction downwards of the image.

6. The polarization optical measurement system according to claim 1, characterized in that, The reference feature unit and the motion feature unit are birefringent thin films.

7. The polarization optical measurement system according to claim 1, characterized in that, The impact loading device is a Marschaete hammer.

8. A polarization optical measurement method for the dynamic response of a spring-mass system under high impact load, employing the polarization optical measurement system described in any one of claims 1-7, characterized in that, include: First, we entered the experimental preparation stage. We turned on the area array light source and adjusted the polarizer and analyzer to the orthogonal extinction state to construct a nearly completely black dark field background. At the same time, we configured the high-speed camera to have a microsecond-level exposure time and a shooting frame rate of tens of thousands of frames per second, and put the high-speed camera in a trigger waiting state. Then, the impact loading and dynamic response phase begins. The impact loading device is released to apply transient impact load to the rigid support frame of the spring-mass system, and the high-speed camera is simultaneously triggered to start recording images. The high-speed camera captures the video stream of the entire process of the reference feature unit and the motion feature unit, and transmits the video stream to the data processing subsystem for subsequent calculation.

Images