A fragment velocity measuring device and a method for synchronously measuring fragment velocity and position thereof

Abstract

This invention relates to a fragment velocity measuring device and a method for simultaneously measuring fragment velocity and position. It addresses the problems of existing light curtain targets being prone to saturation under strong light interference, signal aliasing due to dense arrival of multiple fragments, and difficulties in field calibration. The technical solution of this invention includes a self-calibrating folding mechanical platform, two comb-shaped differential photoelectric detection units, and a data acquisition and processing unit. The self-calibrating folding mechanical platform includes first and second support arms and a damping hinge connecting them. The optical system of the comb-shaped differential photoelectric detection unit divides the detection field of view into N non-overlapping fan-shaped sub-light curtain regions. Each sub-light curtain region corresponds to an independent detection channel to reduce signal aliasing caused by multiple fragments simultaneously passing through the same detection area. The output channel number characterizes the angle / position partitioning information of the fragments. The data acquisition and processing unit is connected to the comb-shaped differential photoelectric detection unit and is used to acquire, mark, and process the angle / position information of multiple fragments output from each channel.

Description

Technical Field

[0001] This invention relates to the field of explosion field testing and photoelectric detection technology, specifically to a fragment velocity measuring device and a method for synchronously measuring fragment velocity and position, thereby achieving synchronous measurement of fragment velocity and spatial position parameters. Background Technology

[0002] The velocity, location distribution, and number of fragments from a fragmentation warhead are important parameters for evaluating its destructive effectiveness. Explosion field testing environments are typically accompanied by intense blast flashes, high-temperature fireballs, shock wave vibrations, and electromagnetic radiation, which can cause problems such as strong light saturation, false triggering, and difficulties in station deployment for non-contact measurement systems.

[0003] In existing technologies, contact-type comb targets and mesh targets rely on fragments cutting conductors to generate signals. These targets are disposable, have complex wiring, are susceptible to electromagnetic interference, and pose a risk of missed detections. Imaging methods such as high-speed photography, while providing rich information, are prone to overexposure and saturation under intense light conditions, and generate large amounts of data that are complex to process, making it difficult to quickly provide velocity and position parameters.

[0004] Traditional light curtain targets use changes in light flux to measure velocity, but they still have problems such as weak resistance to strong light interference, signal aliasing when fragments arrive in large numbers leading to indistinguishability of multiple targets, and the need for long-term optical alignment when setting up separate starting and stopping targets.

[0005] Patent No. 2024230607934 discloses a device for measuring the velocity and scattering characteristics of densely packed fragments based on an array-type comb target. The device includes a mounting bracket, an array module, and a test terminal. The array module is mounted on the mounting bracket to form a measurement target. The array module has array units. The test terminal includes an external trigger module, a data acquisition and storage module, and an output module. The external trigger module is mounted on the array units. The array units include a signal gate and a power gate. The signal gate has a signal output port, which is connected to the data acquisition and storage module via a signal line. The data acquisition and storage module is connected to the output module. The power gate has a power input port, which is connected to a power source via a power line. The test target includes a front target and a rear target. The problem with this device is:

[0006] 1. Low deployment efficiency and heavy reliance on precision instruments: The front and rear targets of this technology are separately mounted on a support structure. When deploying in the field, it is necessary to strictly ensure that the line connecting the centers of the front and rear targets is parallel to the Y-axis, and that the two target surfaces remain parallel to each other. This process usually requires a long time of manual alignment and calibration using optical instruments such as theodolites, resulting in long deployment time and low efficiency, making it difficult to meet the needs of rapid deployment in the field.

[0007] 2. Poor resistance to shock interference and easy failure of measurement geometry: The device adopts a multi-component assembled frame structure. In the environment of an explosion field, due to the lack of reliable mechanical locking and precise self-calibration mechanisms, the system is extremely susceptible to vibration interference from the explosion shock wave. This interference can cause the angle or distance between the front and rear targets to shift, thereby destroying the factory-set geometry, resulting in huge errors in the measurement data or even system failure.

[0008] 3. Insufficient resistance to strong background light interference: This technology mainly relies on the conduction principle of a contact comb target to generate signals. In the field of photoelectric detection, the intense flashes and fireballs generated instantaneously by explosions can easily cause common-mode interference at the detection front end, leading to signal saturation or false triggering. Existing technologies have failed to effectively suppress such strong ambient light at the physical layer, resulting in decreased measurement reliability under strong background radiation.

[0009] 4. Limited Multi-Target Resolution: The measurement accuracy and target resolution of this device are highly dependent on the physical partitioning and wiring density of the PCB array cells. When facing extremely dense fragment clusters, a single conduction logic can easily cause signal aliasing at the physical level. Furthermore, due to the wiring complexity and hardware cost of the contact target surface, it is difficult to achieve parallel measurement and matching with extremely high spatial resolution at a low cost.

[0010] Therefore, there is an urgent need for a fragment velocity measurement method and device that can operate stably under the intense light of an explosion, has multi-target resolution capability, and is easy to deploy quickly in the field. Summary of the Invention

[0011] In view of this, in order to solve the problems of existing light curtain targets being prone to saturation under strong light interference, signal aliasing due to dense arrival of multiple fragments, and difficulty in field station calibration, the present invention provides a fragment velocity measuring device and a method for synchronously measuring fragment velocity and position.

[0012] To achieve the above objectives, the technical solution adopted by the invention is as follows: a fragment velocity measuring device, comprising a self-calibrating folding mechanical platform, two comb-shaped differential photoelectric detection units, and a data acquisition and processing unit;

[0013] The self-calibrating folding mechanical platform includes a first support arm, a second support arm, and a damping hinge connecting the two support arms. The damping hinge is equipped with a mechanical limiting structure.

[0014] The comb-shaped differential photoelectric detection unit includes a start detection unit and a stop detection unit respectively disposed on the first support arm and the second support arm. The start detection unit and the stop detection unit have the same structure. Their optical elements include a slit entrance aperture, a lens group and a detection array located at the focal plane. The detection array includes two symmetrically arranged photosensitive element arrays, which are differentially connected to the in-phase and out-of-phase terminals of the transimpedance amplifier. The slit entrance aperture is disposed at the outlet of the two photosensitive element arrays.

[0015] The data acquisition and processing unit is connected to the comb-shaped differential photoelectric detection unit and is used to acquire, mark, and process the angle / position information of the multiple fragments output from each channel.

[0016] Furthermore, the first support arm and the second support arm are respectively equipped with a horizontal adjustment mechanism and a horizontal indicator.

[0017] Furthermore, the bottom of the first support arm, the second support arm, and the damping hinge are each provided with a base.

[0018] Furthermore, the horizontal adjustment mechanism passes through the first support arm and the second support arm and is connected to the base.

[0019] The method for synchronously measuring the fragment velocity and position of the device comprises the following steps:

[0020] S1. Deploy the first and second support arms of the station and lock them through the mechanical limiting structure in the damping hinge. Level the platform so that when the platform is deployed to the working state, the detection screens of the two comb-shaped differential photoelectric detection units are forced to be parallel and the spacing is a preset calibration value, thus achieving rapid station deployment.

[0021] S2. After the device is powered on, the optical system of the detection unit divides the detection field of view into N non-overlapping fan-shaped sub-light curtain regions through a comb-shaped segmentation structure.

[0022] S3. The data acquisition and processing unit acquires environmental signals under targetless conditions and performs adaptive setting of zero point and threshold.

[0023] S4. Extract the arrival time and channel number for each pulse.

[0024] When the strong flash (far-field signal) generated by the explosion simultaneously illuminates the first and second photosensitive arrays in the detection channels of the two detection units, the common-mode photocurrents generated by the strong light cancel each other out at the circuit input terminal, ensuring that the device continues to work under strong light.

[0025] When the fragment (near-field target) passes through the light curtain, the fragment first blocks the first photosensitive array, generating a pulse of polarity; then the fragment passes through the narrow blind zone of 0.1mm-1.0mm between the two arrays, at which point the signal crosses zero; finally, the fragment blocks the second photosensitive array, generating a pulse of opposite polarity; the circuit output forms an "S"-shaped or bipolar analog signal;

[0026] The system detects the curtain pulses in real time and extracts the arrival time of each pulse. or Simultaneously, the sub-light curtain channel number (K) corresponding to the triggered signal is recorded.

[0027] S5. Output fragment location partitioning information based on channel number and device geometry. In the case of multiple targets, the system matches the event of starting the detection unit with the event of stopping the detection unit according to the correspondence between time window and channel number.

[0028] S6. Calculation speed based on the time difference of successfully matched events;

[0029] The time difference = - Combined with the preset calibration interval L, using the formula Calculate the fragment velocity.

[0030] Furthermore, in step S5, near-time events within the same channel are distinguished by minimum time interval, pulse amplitude, or pulse width characteristics.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects:

[0032] 1. This invention employs a self-calibrating folding mechanical platform with integrated precision damping hinge 4. By utilizing the mechanical limiting structure inside the hinge (such as a hard limiting block or locking pin), the parallelism and preset distance L of the two detection screens are physically limited, enabling rapid station deployment with "deployment and calibration" and significantly improving field testing efficiency. This invention eliminates the cumbersome on-site calibration steps, enabling rapid and accurate station deployment without external instruments, and greatly shortening deployment time.

[0033] 2. This invention utilizes a mechanical limiting mechanism to generate a "rigid locking" force, ensuring that the support arm remains locked in its calibrated position even under impact and vibration. This prevents changes in the distance L between the two screens and their parallelism, improves dynamic vibration resistance, and ensures measurement accuracy in extreme environments. The physical locking mechanism of this invention effectively avoids measurement errors caused by geometric failures, guaranteeing data reliability even in harsh explosive environments.

[0034] 3. This invention employs a unique comb-shaped differential photoelectric detection structure, which connects two symmetrically arranged arrays of photosensitive elements to the circuit in a differential manner. Since the instantaneous strong light (common-mode interference) generated by the explosion field produces approximately equal currents on the symmetrical array, the differential balancing structure can cancel them out at the input end, thereby suppressing signal saturation and false triggering caused by strong background light at the physical layer. This enables the device to stably capture fragment targets in a strong light background, significantly improving its anti-saturation capability.

[0035] 4. This invention utilizes field-of-view physical segmentation technology to divide the detection field of view into N non-overlapping fan-shaped sub-light curtain regions, each region corresponding to an independent detection channel. This design not only significantly improves the spatial resolution when multiple fragments arrive simultaneously and solves the signal aliasing problem, but also enables the system to directly output the position partition information of the fragments according to the trigger channel number, realizing integrated synchronous high-precision measurement of velocity and spatial position parameters. Attached Figure Description

[0036] Figure 1 This is a structural block diagram of the present invention.

[0037] Figure 2 This is a schematic diagram of the overall structure of the self-calibrating folding mechanical platform of the present invention in its unfolded working state.

[0038] Figure 3 This is a schematic diagram of the self-calibrating folding mechanical platform of the present invention in a folded and stored state.

[0039] Figure 4 The diagram shows the optical imaging and dual-array layout of the differential photoelectric detection unit, where (a) is a schematic diagram of the optical path structure of the differential detection unit; and (b) is a schematic diagram of the mapping relationship between the detection array and the object-side field of view.

[0040] Figure 5 This is a schematic diagram showing the connection between the differential transimpedance amplifier and the signal conditioning circuit.

[0041] Figure 6 This is a schematic diagram illustrating the principle of comb-shaped light curtain field segmentation and multi-target detection.

[0042] In the figure: 1-base, 2-first support arm, 3-second support arm, 4-damping hinge, 5a-start detection unit, 5b-stop detection unit, 6-level adjustment mechanism; 7-level indicator, 8-first photosensitive element array; 9-second photosensitive element array; 10-slit entrance aperture. Detailed Implementation

[0043] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] like Figure 1 and Figure 3 As shown, this embodiment provides a fragment velocity measuring device, including a self-calibrating folding mechanical platform, two sets of comb-shaped differential photoelectric detection units, and a data acquisition and processing unit;

[0046] The self-calibrating folding mechanical platform includes a base 1, a first support arm 2, a second support arm 3, and a precision damping hinge 4 (including a mechanical limiting structure) connecting the first support arm 2 and the second support arm 3. A horizontal adjustment mechanism 6 (passing through the first and second support arms and connected to the base 1) is provided on the base 1. A horizontal indicator 7 is provided on the first and second support arms for quick leveling on the ground in the field. A mechanical limiting structure is provided inside the precision damping hinge 4. When the two support arms are unfolded to the limiting point, the mechanical limiting structure (existing structure, such as a hard limiting block or locking pin) rigidly locks the support arms to prevent angular deviation caused by shock waves. This keeps the detection screens of the start detection unit 5a and the stop detection unit 5b installed at the ends of the two support arms parallel, and the distance L between the two screens is the factory calibration value.

[0047] The calibration value L can be set according to measurement requirements, for example, within the range of 0.5m to 2.0m; in one example, L is 1.0m. Since L is guaranteed by mechanical limits and structural machining accuracy, there is no need to use a theodolite to perform long-term alignment calibration of the two screens during station deployment, thereby shortening the station deployment time and reducing the risk of alignment failure caused by shock wave vibration.

[0048] like Figure 4As shown, the comb-shaped differential photoelectric detection unit consists of a start detection unit 5a and a stop detection unit 5b, which are respectively disposed on the first support arm 2 and the second support arm 3. The start detection unit 5a and the stop detection unit 5b have the same structure. Their optical elements include a slit entrance aperture 10, a lens group, and a detection array located at the focal plane. The detection array includes two rows of symmetrically arranged photosensitive element arrays, which are differentially connected to the in-phase and out-of-phase terminals of the transimpedance amplifier. The slit entrance aperture 10 is disposed at the outlet of the two rows of photosensitive element arrays.

[0049] like Figure 6 As shown, the field of view of each detection unit is divided into N fan-shaped sub-light curtain regions by a comb-shaped segmentation structure (N is a positive integer, 8 in this example). Specifically, the comb-shaped segmentation structure can be composed of multiple independent side-by-side photodiode arrays combined with a single imaging lens, or the field of view can be physically segmented by setting a grating plate with multiple slits behind the imaging lens. Each sub-light curtain corresponds to a set of independent detection channels.

[0050] Each detection channel's detection array consists of a first photosensitive array 8 and a second photosensitive array 9 symmetrically arranged, with a narrow blind zone (e.g., 0.1mm to 1.0mm) between them. The purpose of this blind zone is to ensure a clear zero-crossing point or time interval between the negative pulse output by the first array and the positive pulse output by the second array when the fragment passes through, thereby forming a distinctive "S"-shaped or bipolar analog signal. This facilitates high-precision zero-crossing detection by subsequent circuits, further improving noise immunity. This creates a time-series characteristic of the fragment passing through the screen: "first blocking the first array, then crossing the blind zone, and then blocking the second array."

[0051] like Figure 5 As shown, the first photosensitive array 8 and the second photosensitive array 9 are differentially connected to the inverting and non-inverting inputs of the transimpedance amplifier, and are coupled with signal conditioning circuits such as limiting / filtering / comparison. For strong background light in the far field, because the illumination on the two arrays is approximately symmetrical, the resulting common-mode photocurrents cancel each other out at the differential input, thus significantly reducing the risk of saturation and false triggering caused by the explosive flash. For fragmented targets, because the changes in luminous flux caused by their obstruction / reflection are directional in space and temporal, the differential output forms a characteristic overpass pulse, which facilitates reliable triggering and time extraction.

[0052] The data acquisition and processing unit is connected to the comb-shaped differential photoelectric detection unit and includes a multi-channel analog-to-digital converter, a timestamp module, and a processor / programmable logic device, used to acquire, mark, and process the angle / position information of the multiple fragments output from each channel.

[0053] The measurement method of the device of the present invention for measuring the velocity and position of fragments includes the following steps:

[0054] S1. Take out the device in the folded storage state, unfold the first support arm 2 and the second support arm 3, and lock the mechanical limiting structure (such as a hard limiting block) in the precision damping hinge 4 connecting the support arms to rigidly lock the two support arms in the preset position.

[0055] With the aforementioned mechanical locking, there is no need to use optical instruments such as theodolites. The device forcibly limits the detection screens of the start detection unit 5a and the stop detection unit 5b to remain parallel, and the distance L between the two screens is fixed to the factory calibration value, which is 1.0m in this embodiment.

[0056] Observe the horizontal indicator 7 on the support arm, and quickly level it by adjusting the horizontal adjustment mechanism 6 to adapt to the field ground and complete the rapid deployment of the station;

[0057] S2. After the device is powered on, the optical system of the detection unit divides the detection field of view into 8 non-overlapping fan-shaped sub-light curtain regions through a comb-shaped segmentation structure (such as a grating plate or diode array).

[0058] S3. The data acquisition and processing unit acquires environmental signals under targetless conditions and performs adaptive setting of zero point and threshold to prepare for subsequent capture of weak signals.

[0059] S4. Extract the arrival time and channel number for each pulse.

[0060] When the strong flash (far-field signal) generated by the explosion simultaneously illuminates the first photosensitive array 8 and the second photosensitive array 9 in the detection channels of the two detection units, due to the symmetrical arrangement of the two arrays and their connection to the in-phase / out-of-phase input of the differential transimpedance amplifier, the common-mode photocurrent generated by the strong light cancels each other at the circuit input, avoiding circuit saturation and ensuring that the device can still work under strong light.

[0061] When fragments (near-field targets) pass through the light curtain, they create directional occlusion:

[0062] The fragment first blocks the first photosensitive array 8, generating a polar pulse;

[0063] The fragment then passes through a narrow dead zone of 0.1mm-1.0mm between the two arrays, at which point the signal crosses zero;

[0064] Finally, the fragment blocks the second photosensitive array 9, generating pulses of opposite polarity;

[0065] The above process generates a distinctive "S"-shaped or bipolar analog signal at the circuit output, which contains obvious zero-crossing points and is very beneficial for high-precision time extraction.

[0066] The system detects the curtain pulses in real time and extracts the arrival time of each pulse. or To improve accuracy, threshold zero-crossing interpolation or leading edge fitting algorithms are used to determine the time.

[0067] The system also records which sub-light curtain channel number K the triggered signal belongs to, which represents the angle or spatial position of the fragment's flight.

[0068] S5. Output fragment location partitioning information based on channel number and device geometry. In the case of multiple targets, the system matches the event of starting detection unit 5a with the event of stopping detection unit 5b according to the correspondence between time window and channel number.

[0069] Multi-target processing: When multiple fragments trigger different sub-light curtain channels, the device can record multi-channel events in parallel; for near-time events in the same channel, they are distinguished by minimum time interval, pulse amplitude or width characteristics or multi-threshold decision, reducing aliasing and mismatch;

[0070] The geometric relationship of the device includes: the detection surfaces of the start detection unit 5a and the stop detection unit 5b are parallel to each other, and the distance L is fixed to the factory calibration value by the mechanical limiting structure of the damping hinge 4; each detection channel number k uniquely corresponds to a pre-calibrated sector angle range or spatial partition.

[0071] S6. Calculation speed based on the time difference of successfully matched events.

[0072] Based on time difference = - Combined with the preset calibration interval L, using the formula Calculate the fragment velocity.

[0073] Many specific details have been set forth in the foregoing description in order to provide a full understanding of the invention. However, the invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed above.

[0074] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fragment velocity measuring device, characterized in that, It includes a self-calibrating folding mechanical platform, two comb-shaped differential photoelectric detection units, and a data acquisition and processing unit; The self-calibrating folding mechanical platform includes a first support arm (2), a second support arm (3), and a damping hinge (4) connecting the two support arms. The damping hinge (4) is provided with a mechanical limiting structure. The comb-shaped differential photoelectric detection unit includes a start detection unit (5a) and a stop detection unit (5b) respectively disposed on the first support arm (2) and the second support arm (3). The start detection unit (5a) and the stop detection unit (5b) have the same structure. Their optical elements include a slit entrance aperture (10), a lens group and a detection array located at the focal plane. The detection array includes two symmetrically arranged photosensitive element arrays, which are connected to the in-phase and out-of-phase ends of the transimpedance amplifier in a differential manner. The slit entrance aperture (10) is disposed at the outlet of the two photosensitive element arrays. The data acquisition and processing unit is connected to the comb-shaped differential photoelectric detection unit and is used to acquire, mark, and process the angle / position information of the multiple fragments output from each channel.

2. The fragment velocity measuring device according to claim 1, characterized in that, The first support arm (2) and the second support arm (3) are respectively provided with a horizontal adjustment mechanism (6) and a horizontal indicator (7).

3. The fragment velocity measuring device according to claim 2, characterized in that, The bottom of the first support arm (2), the second support arm (3) and the damping hinge (4) are respectively provided with a base (1).

4. A fragment velocity measuring device according to claim 2 or 3, characterized in that, The horizontal adjustment mechanism (6) passes through the first support arm (2) and the second support arm (3) and is connected to the base (1).

5. The method for synchronously measuring the fragment velocity and position of the device according to claim 1, characterized in that, The steps are as follows: S1. Deploy the first support arm (2) and the second support arm (3) and lock them through the mechanical limiting structure in the damping hinge (4). Level the platform so that when the platform is deployed to the working state, the detection screens of the two comb-shaped differential photoelectric detection units are forced to be parallel and the spacing is the preset calibration value, so as to achieve rapid deployment. S2. After the device is powered on, the optical system of the detection unit divides the detection field of view into N non-overlapping fan-shaped sub-light curtain regions through a comb-shaped segmentation structure. S3. The data acquisition and processing unit acquires environmental signals under targetless conditions and performs adaptive setting of zero point and threshold. S4. Extract the arrival time and channel number for each pulse. When the intense flash generated by the explosion simultaneously illuminates the first photosensitive array (8) and the second photosensitive array (9) in the detection channels of the two detection units, the common-mode photocurrent generated by the intense light cancels each other out at the circuit input terminal, ensuring that the device continues to work under intense light. When the fragment passes through the light curtain, it first blocks the first photosensitive array (8), generating a pulse of polarity; then the fragment passes through the narrow blind zone of 0.1mm-1.0mm between the two arrays, at which point the signal crosses zero; finally, the fragment blocks the second photosensitive array (9), generating a pulse of opposite polarity; the circuit output forms an "S"-shaped or bipolar analog signal; The system detects the curtain pulses in real time and extracts the arrival time of each pulse. or Simultaneously, the sub-light curtain channel number K corresponding to the triggered signal is recorded; S5. Output fragment location partitioning information based on channel number and device geometry. In the case of multiple targets, the system matches the event of starting the detection unit (5a) with the event of stopping the detection unit (5b) according to the correspondence between the time window and the channel number. S6. Calculation speed based on the time difference of successfully matched events; The time difference = - Combined with the preset calibration interval L, using the formula Calculate the fragment velocity.

6. The method for synchronously measuring fragment velocity and position according to claim 5, characterized in that, Step S5 distinguishes near-time events within the same channel by minimum time interval, pulse amplitude, or pulse width characteristics.

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