Internal ballistic velocity testing system and method based on magnetic induction intensity

Abstract

The invention relates to an inner ballistic velocity test system and method, in particular to an inner ballistic velocity test system and method based on magnetic induction intensity, and solves the problems of complex installation and use, high test cost and low test precision of a test system based on an existing test method. The system comprises an inner ballistic velocity generation system, a signal measurement and acquisition system and a data analysis processing and velocity calculation module, the inner ballistic velocity generation system comprises a loading system and a magnetic emission part; the magnetic transmitting piece is mounted in a transmitting tube of the loading system; the signal measuring and collecting system comprises S sensors and a data collecting system, wherein the S sensors are arranged on the outer pipe wall of the transmitting pipe at intervals in the axial direction of the transmitting pipe. The input end of the data acquisition system is connected with the output end of the sensor, and the output end is connected with the input end of the data analysis processing and speed calculation module; and the data analysis processing and speed calculation module is used for carrying out filtering and noise reduction processing and correlation analysis on the magnetic induction intensity signal and calculating the inner ballistic velocity.

Description

Technical Field

[0001] The invention relates to an internal ballistic velocity testing system and method, and in particular to an internal ballistic velocity testing system and method based on magnetic induction intensity. Background Art

[0002] In order to improve the launch performance of the loading system, it is necessary to perform internal ballistic calculation and test closed-loop verification to correct the internal ballistic calculation model, so as to make the launch speed and structural strength verification more accurate. Therefore, the internal ballistic velocity test of the launch component in the experiment is a necessary task to verify the validity of the internal ballistic calculation model and calculation results. Since the launch tube is closed in the circumference when the launch component moves in the loading system, it is difficult to use ordinary high-speed cameras and other test equipment. The corresponding internal ballistic velocity can only be obtained by laser Doppler velocity measurement, laying induction sensors on the external wall of the pipe, or laying acceleration sensors on the launch component.

[0003] When the corresponding internal ballistic velocity is obtained by the laser Doppler velocimetry method, this method requires the design of a special signal capture structure and test equipment, especially high-end and precise acquisition equipment and data processing equipment are required to capture the optical signal, which is very costly.

[0004] In the prior art, there are two main methods for disposing inductive sensors on the outer wall of a pipeline to obtain the corresponding internal ballistic velocity: one is a method based on strain gauge testing, and the other is a method based on pressure sensor testing.

[0005] The strain gauge test method refers to the method of monitoring and measuring the annular strain of the tube wall caused by the movement of the internal launcher during the launch of the loading system by arranging strain gauge measuring points at a certain distance on the outer tube wall of the loading system launch tube, obtaining the change of the internal ballistic pressure during the movement of the launcher under typical test conditions, and then obtaining the relationship between the displacement of the launcher during the movement of the launcher and the bottom pressure by deduction, and then obtaining the movement speed of the launcher at different positions in the launch tube. However, when the pressure test is performed based on the strain gauge, the accuracy of the test is affected by many factors, such as the quality of the strain gauge, the installation method and the environmental conditions; on the one hand, the strain gauge is usually designed and manufactured according to the strain characteristics of a specific material, and the installation and use are relatively complicated. Correct installation and connection of the strain gauge requires certain operating skills; on the other hand, changes in the external environment will also affect the performance and measurement results of the strain gauge, such as temperature changes, humidity, vibration or electromagnetic interference; in addition, since the wall of the loading system launch tube is usually round, the surface flatness will also have a certain impact on the attachment of the strain gauge and the transmission of the strain signal, especially in the process of low-speed movement, when the bottom pressure is not high and the deformation of the tube wall is very limited, it is difficult to achieve effective measurement.

[0006] The method based on pressure sensor testing refers to arranging multiple pressure sensors on the outer wall of the launch tube of the loading system, collecting pressure sensor signals at high speed, and obtaining the arrival time of the launch component through the pressure sensor signals. Combined with the distance of the pressure sensor, the movement speed of the launch component at different positions in the launch tube is obtained. The limitation of this method is that it is necessary to process pressure sensor installation holes on the tube wall, which destroys the original structure of the tube wall, affects the overall structural strength and service life of the loading system, and is difficult to drill holes on the tube wall during the entire process of internal ballistic movement.

[0007] In the prior art, the method of placing acceleration sensors on the launcher to obtain the corresponding internal ballistic velocity is mainly missile-borne velocity measurement. For ultra-high-speed loading systems, on the one hand, the launcher is usually small, and it is difficult to install the sensor on the launcher; on the other hand, the sensor itself is expensive. If it is installed on the internal launcher, the sensor will be damaged after one use; therefore, the cost of using this method for testing is very high.

[0008] Therefore, there is an urgent need to develop an internal ballistic velocity testing system and method that is simple to install and use, whose installation will not affect the overall structural strength and service life of the loading system, has low testing cost, and can achieve high-precision and effective testing, so as to achieve accurate testing of the internal ballistic velocity, and then accurately correct the internal ballistic calculation model, so that the launch speed and structural strength verification are more accurate, thereby improving the launch performance of the loading system. Summary of the invention

[0009] The purpose of the present invention is to solve the technical problems of the existing internal ballistic velocity testing method, which is based on the test system that is relatively complicated to install and use, the installation affects the overall structural strength and service life of the loading system, the test cost is high, the test accuracy is low, and effective measurement cannot be achieved during low-speed movement. By providing an internal ballistic velocity testing system and method based on magnetic induction intensity.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0011] An internal ballistic velocity test system based on magnetic induction intensity, which is special in that:

[0012] It includes interior ballistic velocity generation system, signal measurement and acquisition system, and data analysis and processing and velocity calculation module;

[0013] The internal ballistic velocity generation system includes a loading system and a magnetic launcher;

[0014] The loading system comprises a power chamber and a launch tube connected in sequence from back to front; the power chamber is used to store high-pressure gas for launching; a valve is provided at the connection between the power chamber and the launch tube, and the power chamber and the inner cavity of the launch tube are connected and separated by the valve; the magnetic launch element is installed in the inner cavity of the launch tube, and the opening at the front end of the launch tube is the muzzle;

[0015] During launch, the valve is opened, and the high-pressure gas stored in the power chamber flows into the launch tube, pushing the magnetic launcher to move forward in the launch tube and launch it. During the forward movement of the magnetic launcher in the launch tube, the magnetic induction intensity outside the launch tube wall changes;

[0016] The signal measurement and acquisition system includes S sensors for measuring magnetic induction intensity signals and a data acquisition system; S is a natural number greater than or equal to 2;

[0017] The S sensors are arranged on the outer wall of the launch tube at intervals along the axial direction of the launch tube, and the output ends thereof are respectively connected to the input ends of the S acquisition channels of the data acquisition system in a one-to-one correspondence; the output end of the data acquisition system is connected to the input end of the data analysis processing and speed calculation module; the data acquisition system is used to continuously and in real time acquire the magnetic induction intensity signals at the respective positions measured by the S sensors, and transmit the acquired S magnetic induction intensity signals to the data analysis processing and speed calculation module;

[0018] The data analysis and processing and speed calculation module is used to perform filtering and noise reduction processing and correlation analysis on the S collected magnetic induction intensity signals, and calculate the ballistic velocity of the magnetic launcher.

[0019] Furthermore, the sensor adopts a fluxgate sensor or a Hall sensor;

[0020] The S sensors are arranged on the outer wall of the launch tube at intervals along the axial direction of the launch tube by means of bonding.

[0021] Further, the magnetic launcher includes a conventional piston used in a two-stage light gas gun and also includes a magnet;

[0022] The conventional piston comprises a piston head, a piston middle section and a piston tail which are connected in sequence from front to back, and the piston head and the piston tail are both connected to the piston middle section by threaded connection;

[0023] A recess matched with the magnet is arranged on the rear end surface of the piston head; the magnet is arranged in the recess, and the magnet is fixed by threading the piston head and the piston middle section.

[0024] Further, the data acquisition system uses a data collector of Donghua Company.

[0025] Meanwhile, the present invention also provides a method for measuring the interior ballistic velocity based on magnetic induction intensity, which is characterized by including the following steps:

[0026] Step 1: Set up the above-mentioned interior ballistic velocity test system based on magnetic induction intensity;

[0027] Step 2: Close the valve provided at the connection between the power chamber and the launch tube in the interior ballistic velocity test system based on magnetic induction intensity set up in Step 1; then inject high-pressure gas with the pressure required by the design into the power chamber, set the parameters of the data acquisition system, and turn on the data acquisition system and the data analysis, processing and velocity calculation module;

[0028] Step 3: Open the valve closed in Step 2. The high-pressure gas stored in the power chamber flows into the launch tube, pushing the magnetic launch piece to move forward in the launch tube and launching it. During the forward movement of the magnetic launch piece in the launch tube, the magnetic induction intensity outside the wall of the launch tube changes;

[0029] Step 4: Use the data acquisition system turned on in Step 2 to continuously and real-time collect the magnetic induction intensity signals measured by the S sensors at their respective positions, and transmit the S collected magnetic induction intensity signals to the data analysis, processing and velocity calculation module;

[0030] Step 5: The data analysis, processing and velocity calculation module respectively performs filtering and noise reduction processing on the S magnetic induction intensity signals collected by the data acquisition system in Step 4;

[0031] Step 6: The data analysis, processing and velocity calculation module calculates the correlation coefficient r of each group of signals with two signals as a group for the S magnetic induction intensity signals after filtering and noise reduction processing in Step 5, and compares the obtained correlation coefficient r with the set correlation coefficient threshold r0: If r≥r0, it is determined that the two signals in this group of signals are in good consistency, and record these two signals; if r<r0, it is determined that the two signals in this group of signals are in poor consistency and are not recorded; when calculating the correlation coefficient r of each group of signals with two signals as a group, the following conditions should be met: Ensure that each of the S magnetic induction intensity signals after filtering and noise reduction processing in Step 5 has at least one corresponding correlation coefficient r;

[0032] Step 7: Based on the signals recorded in Step 6, calculate the interior ballistic velocity of the magnetic launch piece at the positions of the sensors corresponding to the signals recorded in Step 6 according to the relationship between the step change of the magnetic induction intensity signal and the interior ballistic velocity, and complete the test.

[0033] Furthermore, in step 2, the pressure range of the high-pressure gas of the design required pressure is between 1 MPa and 10 MPa, and its specific value is set according to the launch speed requirement and is an empirical value.

[0034] Furthermore, in step 5, the filtering and noise reduction processing is specifically performed as follows:

[0035] Step B1: a value is given to the filtering standard deviation σ of the Gaussian signal function in the Gaussian smoothing filter; the Gaussian signal function is:

[0036]

[0037] Where: G(x) represents the Gaussian signal function; σ represents the filtering standard deviation; x represents the collected magnetic induction intensity signal;

[0038] Step B2: The collected magnetic induction intensity signal is subjected to Gaussian smoothing filtering using a Gaussian signal function with a given filtering standard deviation σ to remove high-frequency noise in the signal;

[0039] Step B3: determining in real time whether the magnetic induction intensity signal after the Gaussian smoothing filter processing in step B2 is a visible curve; if so, the visible curve is the obtained magnetic induction intensity signal after the high-frequency noise is removed, and step B4 is executed; if not, a value is re-given to the filtering standard deviation σ of the Gaussian signal function in the Gaussian smoothing filter, and then returning to step B2;

[0040] Step B4: The magnetic induction intensity signal obtained in step B3 after high-frequency noise removal is subjected to Butterworth low-pass filter processing to remove low-frequency noise in the signal, thereby obtaining a magnetic induction intensity signal after filtering and noise reduction processing, and completing filtering and noise reduction processing.

[0041] Further, in step B4, when the Butterworth low-pass filter processing is performed, the transfer function of the Butterworth low-pass filter is:

[0042]

[0043] Where: H(jw) represents the transfer function of the Butterworth low-pass filter, where jw represents the complex frequency variable; w represents the sampling frequency of the magnetic induction intensity signal; w c represents the frequency of the Butterworth low-pass filter, which is 50Hz; n represents the order of the Butterworth low-pass filter, which is 4.

[0044] Furthermore, in step 6, when calculating the correlation coefficient r of each group of signals, the following formula is used for calculation:

[0045]

[0046] In the formula: r represents the correlation coefficient; m represents the number of signal acquisition points; x i ,y i Respectively represent the magnetic induction intensity at the i-th acquisition point corresponding to each of the two magnetic induction intensity signals in the group of signals, where 1≤i≤m; They respectively represent the mean values ​​of the magnetic induction intensities at the m acquisition points corresponding to the two magnetic induction intensity signals in the group of signals.

[0047] Furthermore, in step 7, when calculating the internal ballistic velocity of the magnetic launcher at the sensor position corresponding to each signal recorded in step 6, the calculation process of the internal ballistic velocity of the magnetic launcher at each sensor position is:

[0048] Step C1: for the corresponding signal recorded in step 6, calculate the first-order difference of the signal;

[0049] Step C2: 0.1 times of the maximum value of the first-order difference of the signal calculated in step C1 is used as the set mutation threshold; then the absolute value of the first-order difference of the signal calculated in step C1 is compared with the set mutation threshold respectively: if the absolute value of the first-order difference of the signal is greater than the set mutation threshold, it is determined that the signal has undergone a mutation at this location, and detection is performed within a set range before and after the mutation location on the signal to extract the mutation signal in the signal, and then the mutation duration of the signal step change and the mutation range of the magnetic induction intensity are obtained from the mutation signal; if the absolute value of the first-order difference of the signal is less than or equal to the set mutation threshold, it is determined that the signal has not undergone a mutation at this location, and no detection is performed;

[0050] Step C3: According to the mutation duration of the signal step change and the mutation range of the magnetic induction intensity obtained in step C2, the internal ballistic velocity of the magnetic launcher at the corresponding sensor position is calculated using the following formula:

[0051]

[0052] Where: V represents the internal ballistic velocity of the magnetic launcher at the corresponding sensor position; k is the proportional coefficient, which is the calibration value; Represents the slope of the magnetic induction intensity signal step, where dB is the absolute value of the range endpoint difference corresponding to the mutation range of the magnetic induction intensity obtained in step C2, and dt is the mutation duration obtained in step C2.

[0053] The beneficial effects of the present invention are:

[0054] (1) In the internal ballistic velocity testing system and method based on magnetic induction intensity of the present invention, the sensor used is a sensor for measuring magnetic induction intensity signals. The sensor measures the magnetic induction intensity signals at the positions of the sensors when the magnetic launcher moves forward in the launch tube. The installation and use of the sensor are very simple. During installation, there is no need to drill holes in the launch tube for installation. The installation can be done by pasting. Therefore, its installation will not affect the overall structural strength and service life of the loading system. It can be installed on the tube wall during the entire process of internal ballistic movement. In addition, when using the internal ballistic velocity testing system and method based on magnetic induction intensity of the present invention to perform internal ballistic velocity testing, there is no need to arrange an acceleration sensor on the launcher. It is only necessary to fix a magnet on the traditional piston to form a magnetic launcher. Therefore, compared with the prior art in which an acceleration sensor is arranged on the launcher, the corresponding The method for measuring internal ballistic velocity has a greatly reduced testing cost. In addition, the sensor in the present invention measures a magnetic induction intensity signal, rather than the annular strain of the launch tube wall measured in the method based on strain gauge testing in the prior art. Therefore, its measurement accuracy is not affected by the flatness of the launch tube surface and the quality of sensor attachment and installation, thereby greatly improving its testing accuracy. At the same time, since the sensor in the present invention measures a magnetic induction intensity signal, its measurement is not affected by the movement speed of the magnetic launcher, and effective measurement can be achieved during the low-speed movement of the magnetic launcher. In summary, the present invention solves the technical problems of the existing internal ballistic velocity testing method, the test system based on which is relatively complex to install and use, the installation affects the overall structural strength and service life of the loading system, the testing cost is high, the testing accuracy is low, and effective measurement cannot be achieved during low-speed movement.

[0055] (2) In the internal ballistic velocity testing system and method based on magnetic induction intensity of the present invention, the magnetic induction intensity signal testing principle is applied to the internal ballistic velocity testing. Preferably, the sensor is arranged on the outer wall of the launch tube along the axial direction of the launch tube by pasting. Preferably, a pit matching with the magnet is arranged on the rear end surface of the piston head of the traditional piston, and the traditional piston structure is partially improved and designed to obtain a magnetic emission element that can cause the magnetic induction intensity of the outer wall of the launch tube to change, thereby providing motion characteristics for the sensor to measure the magnetic induction intensity signal. When installing the sensor, it is not necessary to drill holes on the launch tube for installation. When obtaining the magnetic emission element, the structure of the traditional piston is not destroyed, thereby reducing the dependence on the conditions of the loading system itself, reducing the prerequisites for the internal ballistic velocity testing, reducing the condition restrictions of the internal ballistic velocity testing, improving the simplicity and effectiveness of the internal ballistic velocity testing throughout the process, and realizing non-destructive testing. It can meet the requirements of the internal ballistic velocity testing of the finalized loading system, and can be applied to the internal ballistic velocity testing of various loading methods, guiding the design of the internal ballistic structure parameters and the launching parameters of the loading system, and improving the accuracy of the internal ballistic velocity calculation.

[0056] (3) In the internal ballistic velocity testing system and method based on magnetic induction intensity of the present invention, when calculating the internal ballistic velocity, the collected magnetic induction intensity signal is first filtered, denoised and correlated, and high-frequency noise and low-frequency noise in the signal are removed, and useful signals with good consistency are selected therefrom; then, the useful signals with good consistency are used to calculate the internal ballistic velocity of the magnetic launcher at the sensor position corresponding to each useful signal with good consistency based on the relationship between the step change of the magnetic induction intensity signal and the internal ballistic velocity; because the high-frequency noise and low-frequency noise in the signal are removed and a correlation analysis is performed before the calculation, the calculated internal ballistic velocity has high accuracy, and the high-precision internal ballistic velocity is used to optimize the loading system structure parameters and the launch parameters. When verifying the effectiveness of the internal ballistic calculation model, the optimization and verification results are also more accurate, thereby improving the accuracy of the launch velocity calculation results.

[0057] (4) In the internal ballistic velocity testing system and method based on magnetic induction intensity of the present invention, an internal ballistic velocity testing system is constructed from the perspective of magnetic induction intensity signal measurement, and the internal ballistic velocity is obtained based on the relationship between the step change of the magnetic induction intensity signal and the internal ballistic velocity, thereby increasing the diversity of the internal ballistic velocity test. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a structural schematic diagram of an internal ballistic velocity generation system in an embodiment of the internal ballistic velocity testing system based on magnetic induction intensity of the present invention;

[0059] Figure 2 It is a schematic structural diagram of an embodiment of the internal ballistic velocity testing system based on magnetic induction intensity of the present invention, in which sensors are arranged on the outer wall of the launch tube at intervals along the axial direction of the launch tube;

[0060] Figure 3 It is the magnetic induction intensity signal measured by the first sensor and the magnetic induction intensity signal measured by the sixth sensor collected by the data acquisition system in step 4 of the embodiment of the internal ballistic velocity test method based on magnetic induction intensity of the present invention; wherein:

[0061] (a) is the magnetic induction intensity signal measured by sensor No. 1 collected by the data acquisition system;

[0062] (b) is the magnetic induction intensity signal measured by the sixth sensor collected by the data acquisition system;

[0063] Figure 4In step 5 of the embodiment of the internal ballistic velocity testing method based on magnetic induction intensity of the present invention, the data analysis processing and velocity calculation module respectively filters and de-noises the magnetic induction intensity signal measured by the No. 1 sensor and the magnetic induction intensity signal measured by the No. 6 sensor collected by the data acquisition system, and obtains the corresponding signal; wherein:

[0064] (c) is the signal obtained after filtering and noise reduction processing of the magnetic induction intensity signal measured by sensor No. 1 collected by the data acquisition system;

[0065] (d) is the signal obtained after filtering and noise reduction processing of the magnetic induction intensity signal measured by the sixth sensor collected by the data acquisition system;

[0066] Figure 5 It is the mutation signal extracted by the data analysis and processing and speed calculation module in step C2 of step 7 of the embodiment of the internal ballistic velocity testing method based on magnetic induction intensity of the present invention from the magnetic induction intensity signal measured by the No. 1 sensor and the magnetic induction intensity signal measured by the No. 6 sensor after the recorded filtering and noise reduction processing; wherein:

[0067] (e) is the mutation signal extracted from the magnetic induction intensity signal measured by sensor No. 1 after the recorded filtering and noise reduction processing;

[0068] (f) is the mutation signal extracted from the magnetic induction intensity signal measured by sensor No. 6 after the recorded filtering and noise reduction processing.

[0069] The descriptions of the numbers in the figure are as follows:

[0070] 1-power room, 2-launching tube, 3-valve, 4-magnetic launcher, 51-sensor No. 1, 52-sensor No. 2, 53-sensor No. 3, 54-sensor No. 4, 55-sensor No. 5, 56-sensor No. 6. DETAILED DESCRIPTION

[0071] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0072] The invention discloses an interior ballistic velocity testing system based on magnetic induction intensity, comprising an interior ballistic velocity generating system, a signal measuring and collecting system, and a data analyzing and processing and velocity calculating module.

[0073] See also Figure 1The above-mentioned internal ballistic velocity generation system includes a loading system and a magnetic launcher 4; the loading system includes a power chamber 1 and a launch tube 2 connected in sequence from back to front; the power chamber 1 is used to store high-pressure gas for launching; a valve 3 is provided at the connection between the power chamber 1 and the launch tube 2, and the power chamber 1 and the launch tube 2 are connected and separated by the valve 3; the magnetic launcher 4 is installed in the inner cavity of the launch tube 2, and the frontmost opening of the launch tube 2 is the muzzle; in this embodiment, the magnetic launcher 4 is preferably transformed from a traditional piston used in a two-stage light gas gun, which includes a traditional piston used in a two-stage light gas gun and a magnet; the traditional piston used in the two-stage light gas gun includes a piston head, a piston middle section and a piston tail connected in sequence from front to back, and the piston head and the piston tail are connected to the piston middle section by threaded connection; in this embodiment, when the magnet is fixedly connected to the traditional piston, only a pit compatible with the magnet is provided on the rear end surface of the piston head of the traditional piston; the magnet is arranged in the pit, and the magnet is fixed by threading the piston head and the piston middle section. During launch, valve 3 is opened, and the high-pressure gas stored in power chamber 1 flows into launch tube 2, pushing magnetic launch element 4 to move forward in launch tube 2 and launching it. During the forward movement of magnetic launch element 4 in launch tube 2, the magnetic induction intensity outside the wall of launch tube 2 changes.

[0074] The signal measurement and acquisition system includes S sensors for measuring magnetic induction intensity signals and a data acquisition system; S is a natural number greater than or equal to 2; see Figure 2, S sensors are arranged on the outer wall of the launch tube 2 along the axial direction of the launch tube 2 at intervals, and their output ends are connected to the input ends of the S acquisition channels of the data acquisition system in a one-to-one correspondence; in this embodiment, S is equal to 6, that is, 6 sensors are arranged on the outer wall of the launch tube 2 along the axial direction of the launch tube 2 at intervals, and the 6 sensors are respectively sensor No. 1 51, sensor No. 2 52, sensor No. 3 53, sensor No. 4 54, sensor No. 55 and sensor No. 6 56 from back to front. In this embodiment, the 6 sensors are fluxgate sensors, and the 6 fluxgate sensors are arranged on the outer wall of the launch tube 2 along the axial direction of the launch tube 2 by pasting. In addition to the fluxgate sensor used in this embodiment, other sensors that can measure magnetic induction intensity signals such as Hall sensors can also be used. When installing the sensor, in addition to the pasting method used in this embodiment, other installation methods that will not damage the original structure of the launch tube 2 can also be used for installation. In this embodiment, the data acquisition system uses the data acquisition instrument of Donghua Company. The output end of the data acquisition system is connected to the input end of the above-mentioned data analysis processing and speed calculation module, that is, in this embodiment, it is connected to the computer; the data acquisition system is used to collect the magnetic induction intensity signals at their respective positions measured by the S sensors in real time and continuously, and transmit the collected S magnetic induction intensity signals to the data analysis processing and speed calculation module.

[0075] The data analysis and processing and speed calculation module is used to filter and de-noise the S magnetic induction intensity signals collected, and perform correlation analysis, and calculate the ballistic velocity of the magnetic launcher 4. In this embodiment, the data analysis and processing and speed calculation module includes a memory and a processor, and the memory stores a computer program. When the computer program is executed by the processor, the following process is implemented:

[0076] Step A1: receiving S magnetic induction intensity signals collected by the above data acquisition system, and filtering and noise reduction processing are performed on the S magnetic induction intensity signals respectively; in this embodiment, filtering and noise reduction processing are performed on 6 magnetic induction intensity signals respectively;

[0077] Step A2: For the S magnetic induction intensity signals after filtering and noise reduction in Step A1, taking two signals as a group, calculate the correlation coefficient r of each group of signals respectively, and compare the obtained correlation coefficient r with the set correlation coefficient threshold r0: If r≥r0, it is determined that the two signals in this group of signals have good consistency, and record these two signals; If r<r0, it is determined that the two signals in this group of signals have poor consistency and are not recorded; When taking two signals as a group and calculating the correlation coefficient r of each group of signals respectively, the following conditions should be met: Ensure that each of the S magnetic induction intensity signals after filtering and noise reduction in Step A1 has at least one corresponding correlation coefficient r; In this embodiment, when taking two signals as a group and calculating the correlation coefficient r of each group of signals respectively, ensure that each of the 6 magnetic induction intensity signals after filtering and noise reduction has at least one corresponding correlation coefficient r;

[0078] Step A3: Based on the signals recorded in Step A2, and based on the relationship between the step change of the magnetic induction intensity signal and the interior ballistic velocity, calculate the interior ballistic velocity of the magnetic emitter 4 at the sensor position corresponding to each signal recorded in Step A2, and complete the test.

[0079] In addition, the present invention also provides an interior ballistic velocity test method based on magnetic induction intensity, including the following steps:

[0080] Step 1: Set up the above-mentioned interior ballistic velocity test system based on magnetic induction intensity;

[0081] During construction, the volume of the power chamber 1 is usually within 1L, and the weight of the magnetic launcher 4 is usually between 1g and 10g. The connecting bolts between the power chamber 1 and the launch tube 2 are released, the contact surface between the power chamber 1 and the launch tube 2 is loosened, and the magnetic launcher 4 is placed at the mouth of the rear end of the launch tube 2, and then the chamber is closed, that is, the power chamber 1 and the launch tube 2 are tightly connected with bolts; in this embodiment, the volume of the power chamber 1 is 0.3L; the length of the launch tube 2 is 1.8m and the diameter is 10mm; the diameter of the magnetic launcher 4 is 10mm and the weight is 2g; when sensors are set on the outer wall of the launch tube 2 along its axial direction, the number of sensors set is determined according to the length of the launch tube 2, and adjacent sensors are usually spaced 1 / 4 in distance. 0.2m~1m, but if the ballistic velocity in one section of the launch tube 2 is not concerned, no sensor may be set in this section; in this embodiment, 6 fluxgate sensors are set on the outer wall of the launch tube 2 along its axial direction, wherein the center distance between the first sensor 51 and the second sensor 52 is 29.5cm, the center distance between the second sensor 52 and the third sensor 53 is 36.5cm, the center distance between the third sensor 53 and the fourth sensor 54 is 32.5cm, the center distance between the fourth sensor 54 and the fifth sensor 55 is 24.5cm, and the center distance between the fifth sensor 55 and the sixth sensor 56 is 34.5cm; the data acquisition system adopts the data acquisition instrument of Donghua Company;

[0082] Step 2: Close the valve 3 provided at the connection between the power chamber 1 and the launch tube 2 in the internal ballistic velocity test system based on magnetic induction intensity built in step 1; then inject high-pressure gas of the required design pressure into the power chamber 1, set the parameters of the data acquisition system, and start the data acquisition system and the data analysis and processing and velocity calculation module;

[0083] When high-pressure gas of the design required pressure is injected into the power chamber 1, the pressure range of the high-pressure gas of the design required pressure is usually between 1MPa and 10MPa, and its specific value is set according to the firing speed requirement and is an empirical value; in this embodiment, the pressure of the high-pressure gas injected into the power chamber 1 is 4.7MPa; when setting the parameters of the data acquisition system as mentioned above, the sampling frequency of the data acquisition system is usually set between 100kHz and 50MHz, and its specific setting value is set according to the estimated internal ballistic velocity; in this embodiment, the sampling frequency of the data acquisition system is set to 100kHz;

[0084] Step 3: Open the valve 3 closed in step 2, and the high-pressure gas stored in the power chamber 1 flows into the launch tube 2, pushing the magnetic launcher 4 to move forward in the launch tube 2 to launch it. During the forward movement of the magnetic launcher 4 in the launch tube 2, the magnetic induction intensity outside the wall of the launch tube 2 changes;

[0085] Step 4: The data acquisition system started in step 2 is used to continuously and in real time acquire the magnetic induction intensity signals at the respective positions measured by the S sensors, and the acquired S magnetic induction intensity signals are transmitted to the data analysis and processing and speed calculation module;

[0086] In this embodiment, the number of magnetic induction intensity signals collected by the data acquisition system is 6; taking the No. 1 sensor 51 and the No. 6 sensor 56 as examples, in this embodiment, the magnetic induction intensity signals measured by the No. 1 sensor 51 and the magnetic induction intensity signals measured by the No. 6 sensor 56 collected by the data acquisition system are respectively as follows: Figure 3 As shown in (a) and (b);

[0087] Step 5: The data analysis and speed calculation module performs filtering and noise reduction on the S magnetic induction intensity signals collected by the data acquisition system in step 4; that is, the following processes are performed on the collected S magnetic induction intensity signals:

[0088] Step B1: Give a value to the filtering standard deviation σ of the Gaussian signal function in the Gaussian smoothing filter; the above Gaussian signal function is:

[0089]

[0090] Where: G(x) represents the Gaussian signal function; σ represents the filtering standard deviation; x represents the collected magnetic induction intensity signal;

[0091] Step B2: The collected magnetic induction intensity signal is subjected to Gaussian smoothing filtering using a Gaussian signal function with a given filtering standard deviation σ to remove high-frequency noise in the signal and maintain the trend and change of the signal;

[0092] Step B3: determining in real time whether the magnetic induction intensity signal after the Gaussian smoothing filter processing in step B2 is a visible curve; if so, the visible curve is the obtained magnetic induction intensity signal after the high-frequency noise is removed, and step B4 is executed; if not, a value is re-given to the filtering standard deviation σ of the Gaussian signal function in the above Gaussian smoothing filter, and then returning to step B2;

[0093] In this embodiment, when the given filtering standard deviation σ is 5, the magnetic induction intensity signal after Gaussian smoothing filtering becomes a visible curve, and the Gaussian smoothing filtering of the signal is completed;

[0094] Step B4: performing a Butterworth low-pass filter process on the magnetic induction intensity signal after high-frequency noise removal obtained in step B3 to remove low-frequency noise in the signal, thereby obtaining a magnetic induction intensity signal after filtering and noise reduction processing, and completing filtering and noise reduction processing;

[0095] When performing Butterworth low-pass filter processing as described above, the transfer function of the Butterworth low-pass filter is as follows:

[0096]

[0097] In the formula: H(jw) represents the transfer function of the Butterworth low-pass filter, where jw represents the complex frequency variable; w represents the sampling frequency of the magnetic induction intensity signal; w c represents the frequency of the Butterworth low-pass filter; since the frequencies of environmental noise and electromagnetic interference signals are generally above 50 Hz, the frequency w c of the Butterworth low-pass filter is usually taken as 50 Hz; n represents the order of the Butterworth low-pass filter; in order to make the signal steeper, the order n of the Butterworth low-pass filter is usually taken as 4, which can ensure that important low-frequency information in the signal is retained; in order to avoid phase distortion and maintain time alignment, preferably, zero-phase filtering is used for Butterworth low-pass filter processing, which can ensure that the time characteristics of the signal remain unchanged;

[0098] Taking the first sensor 51 and the sixth sensor 56 as examples, in this embodiment, after the data analysis and processing and speed calculation module filters and denoises the magnetic induction intensity signals measured by the first sensor 51 and the sixth sensor 56 collected by the data acquisition system, the corresponding signals obtained are respectively as Figure 4 shown in (c) and (d) below;

[0099] Step 6: The data analysis and processing and speed calculation module takes two signals as a group from the S magnetic induction intensity signals after filtering and denoising in Step 5, calculates the correlation coefficient r of each group of signals respectively, and compares the obtained correlation coefficient r with the set correlation coefficient threshold r0: if r≥r0, it is determined that the two signals in this group of signals are in good agreement, and these two signals are recorded; if r<r0, it is determined that the two signals in this group of signals are in poor agreement and are not recorded; when calculating the correlation coefficient r of each group of signals with two signals as a group, the following conditions should be met: each of the S magnetic induction intensity signals after filtering and denoising in Step 5 should have at least one corresponding correlation coefficient r;

[0100] In this embodiment, when calculating the correlation coefficient r of each group of signals with two signals as a group, each of the 6 magnetic induction intensity signals after filtering and denoising should have at least one corresponding correlation coefficient r; when calculating the correlation coefficient r of each group of signals as described above, the following formula is used for calculation:

[0101]

[0102] In the formula: r represents the correlation coefficient; m represents the number of signal acquisition points; x i,y i Respectively represent the magnetic induction intensity at the i-th acquisition point corresponding to each of the two magnetic induction intensity signals in the group of signals, where 1≤i≤m; Respectively represent the mean values ​​of the magnetic induction intensities at the m acquisition points corresponding to the two magnetic induction intensity signals in the group of signals;

[0103] By calculating the correlation coefficient r of the signals between different sensors and conducting correlation analysis, the time delay relationship between the signals of different sensors can be clarified and the synchronization relationship between the signals can be determined; when the correlation coefficient r is 1, it indicates that the two signals are completely linearly positively correlated; when the correlation coefficient r is 0, it indicates that the two signals are uncorrelated; when the correlation coefficient r is -1, it indicates that the two signals are completely linearly negatively correlated; the above-mentioned set correlation coefficient threshold r0 is usually 0.8; in this embodiment, taking the signals corresponding to sensor No. 1 51 and sensor No. 6 56 as an example, the correlation coefficient r calculated using the signals corresponding to sensor No. 1 51 and sensor No. 6 56 is 0.98, which is greater than the set correlation coefficient threshold r0 of 0.8, indicating that the signals corresponding to sensor No. 1 51 and sensor No. 6 56 have good consistency and are useful signals, which are recorded and subsequently used for the calculation of the ballistic velocity in the magnetic launcher 4 at the corresponding sensor position;

[0104] Step 7: According to the signals recorded in step 6, based on the relationship between the step change of the magnetic induction intensity signal and the internal ballistic velocity, the internal ballistic velocity of the magnetic emission element 4 at the sensor position corresponding to each signal recorded in step 6 is calculated;

[0105] When the internal ballistic velocity of the magnetic transmitter 4 at the sensor position corresponding to each signal recorded in step 6 is obtained by the above calculation, the calculation process of the internal ballistic velocity of the magnetic transmitter 4 at each sensor position is:

[0106] Step C1: for the corresponding signal recorded in step 6, calculate the first-order difference of the signal;

[0107] In order to facilitate the detection of signal mutations, which are usually manifested as drastic changes in signal values ​​in a short period of time, these changes can be detected by calculating the first-order difference of the signal;

[0108] Step C2: 0.1 times the maximum value of the first-order difference of the signal calculated in step C1 is used as the set mutation threshold; then the absolute value of the first-order difference of the signal calculated in step C1 is compared with the set mutation threshold respectively: if the absolute value of the first-order difference of the signal is greater than the set mutation threshold, it is determined that the signal has undergone a mutation at this location, and detection is performed within a set range before and after the mutation location on the signal to extract the mutation signal in the signal, and then the mutation duration of the signal step change and the mutation range of the magnetic induction intensity are obtained from the mutation signal; if the absolute value of the first-order difference of the signal is less than or equal to the set mutation threshold, it is determined that the signal has not undergone a mutation at this location, and no detection is performed;

[0109] In this embodiment, taking the No. 1 sensor 51 and the No. 6 sensor 56 as examples, the data analysis processing and speed calculation module extracts the mutation signals from the magnetic induction intensity signals measured by the No. 1 sensor and the No. 6 sensor after the filtering and noise reduction processing, respectively. Figure 5 As shown in (e) and (f); the duration of the signal step change obtained from the mutation signal corresponding to the first sensor 51 is 0.301s, the mutation range of the magnetic induction intensity is 24602nT~22123nT, and the absolute value of the difference between the range endpoints is 2.479uT; the duration of the signal step change obtained from the mutation signal corresponding to the sixth sensor 56 is 0.035s, the mutation range of the magnetic induction intensity is 24314nT~22685nT, and the absolute value of the difference between the range endpoints is 1.629uT;

[0110] Step C3: Calculate the internal ballistic velocity of the magnetic emission element 4 at the corresponding sensor position according to the mutation duration of the signal step change and the mutation range of the magnetic induction intensity obtained in step C2;

[0111] The sensor senses the distance range of the magnetic emitter 4 as an "unknown" length Δx. By detecting the extracted mutation signal, the slope of the signal step can be obtained. Assuming that Δx is small enough, the magnetic induction intensity B is proportional to the position x of the magnetic emitter 4, that is: dx = kdB, then the internal ballistic velocity of the magnetic emitter 4 at the corresponding sensor position is calculated using the following formula:

[0112]

[0113] Wherein: V represents the internal ballistic velocity of the magnetic launcher 4 at the corresponding sensor position; k is the proportional coefficient, which is a calibration value. Under the same working condition, the magnetic launcher 4 has the same proportional coefficient k at different sensor positions; represents the slope of the magnetic induction intensity signal step, where dB is the absolute value of the difference between the range endpoints corresponding to the mutation range of the magnetic induction intensity obtained in step C2, and dt is the mutation duration obtained in step C2;

[0114] In this embodiment, the first sensor 51 and the sixth sensor 56 correspond to They are 8.23uT / s and 46.5uT / s respectively; k is taken as 10.15m / uT, and the calculated ballistic velocity in the magnetic launcher 4 at the position of sensor No. 1 51 is 83.53m / s, and the calculated ballistic velocity in the magnetic launcher 4 at the position of sensor No. 6 56 is 472m / s.

[0115] By using the internal ballistic velocity testing system and method based on magnetic induction intensity of the present invention, after the internal ballistic velocity is tested, it can be subsequently compared and analyzed with the theoretical calculation results to optimize the loading system structure parameters and launch parameters, verify the effectiveness of the internal ballistic calculation model, and thus improve the accuracy of the launch velocity calculation results.

[0116] In summary, the present invention builds an internal ballistic velocity testing system from the perspective of magnetic induction intensity signal measurement, obtains the internal ballistic velocity based on the relationship between the step change of the magnetic induction intensity signal and the internal ballistic velocity, and increases the diversity of the internal ballistic velocity test.

Claims

1. An interior ballistic velocity testing system based on magnetic induction intensity, characterized in that: It includes interior ballistic velocity generation system, signal measurement and acquisition system, and data analysis and processing and velocity calculation module; The internal ballistic velocity generation system comprises a loading system and a magnetic launching member (4); The loading system comprises a power chamber (1) and a launch tube (2) connected in sequence from back to front; the power chamber (1) is used to store high-pressure gas for launching; a valve (3) is provided at the connection between the power chamber (1) and the launch tube (2), and the power chamber (1) and the launch tube (2) inner cavity are connected and separated by the valve (3); the magnetic launch element (4) is installed in the inner cavity of the launch tube (2), and the frontmost opening of the launch tube (2) is the muzzle; During launch, the valve (3) is opened, and the high-pressure gas stored in the power chamber (1) flows into the launch tube (2), pushing the magnetic launch element (4) to move forward in the launch tube (2) to launch it. During the process of the magnetic launch element (4) moving forward in the launch tube (2), the magnetic induction intensity outside the launch tube (2) wall changes. The signal measurement and acquisition system includes S sensors for measuring magnetic induction intensity signals and a data acquisition system; S is a natural number greater than or equal to 2; S sensors are arranged on the outer wall of the launch tube (2) at intervals along the axial direction of the launch tube (2), and their output ends are respectively connected to the input ends of S acquisition channels of the data acquisition system in a one-to-one correspondence; the output end of the data acquisition system is connected to the input end of the data analysis processing and speed calculation module; the data acquisition system is used to continuously and in real time acquire magnetic induction intensity signals at respective locations measured by the S sensors, and transmit the acquired S magnetic induction intensity signals to the data analysis processing and speed calculation module; The data analysis and processing and speed calculation module is used to perform filtering and noise reduction processing and correlation analysis on the collected S magnetic induction intensity signals respectively and in turn, and calculate the internal ballistic speed of the magnetic launcher (4).

2. The internal ballistic velocity testing system based on magnetic induction intensity according to claim 1, characterized in that: The sensor adopts a fluxgate sensor or a Hall sensor; The S sensors are arranged at intervals on the outer wall of the launch tube (2) along the axial direction of the launch tube (2) by means of bonding.

3. The internal ballistic velocity testing system based on magnetic induction intensity according to claim 1, characterized in that: The magnetic launcher (4) comprises a conventional piston used in a two-stage light gas gun and also comprises a magnet; The conventional piston comprises a piston head, a piston middle section and a piston tail which are connected in sequence from front to back, and the piston head and the piston tail are both connected to the piston middle section by threaded connection; A recess matched with the magnet is arranged on the rear end surface of the piston head; the magnet is arranged in the recess, and the magnet is fixed by threading the piston head and the piston middle section.

4. The internal ballistic velocity testing system based on magnetic induction intensity according to claim 1, characterized in that: The data acquisition system uses a data collector from Donghua Company.

5. A method for measuring interior ballistic velocity based on magnetic induction intensity, characterized in that: It includes the following steps: Step 1: Set up the internal ballistic velocity test system based on magnetic induction intensity as described in any one of Claims 1 to 4; Step 2: Close the valve (3) provided at the connection between the power chamber (1) and the launch tube (2) in the internal ballistic velocity test system based on magnetic induction intensity set up in Step 1; then inject high-pressure gas with a pressure meeting the design requirements into the power chamber (1), set the parameters of the data acquisition system, and turn on the data acquisition system and the data analysis, processing, and velocity calculation module; Step 3: Open the valve (3) closed in Step 2. The high-pressure gas stored in the power chamber (1) flows into the launch tube (2), pushing the magnetic launch member (4) to move forward in the launch tube (2) and launch it. During the forward movement of the magnetic launch member (4) in the launch tube (2), the magnetic induction intensity outside the wall of the launch tube (2) changes; Step 4: Use the data acquisition system turned on in Step 2 to continuously and real-time collect the magnetic induction intensity signals measured by the S sensors at their respective positions, and transmit the S collected magnetic induction intensity signals to the data analysis, processing, and velocity calculation module; Step 5: The data analysis, processing, and velocity calculation module respectively performs filtering and noise reduction processing on the S magnetic induction intensity signals collected by the data acquisition system in Step 4; Step 6: The data analysis, processing, and velocity calculation module calculates the correlation coefficient r for each group of two signals from the S magnetic induction intensity signals after filtering and noise reduction processing in Step 5, and compares the obtained correlation coefficient r with the set correlation coefficient threshold r0: If r≥r0, it is determined that the two signals in this group have good consistency, and record these two signals; If r<r0, it is determined that the two signals in this group have poor consistency and are not recorded; When calculating the correlation coefficient r for each group of two signals, the following conditions should be met: Ensure that each of the S magnetic induction intensity signals after filtering and noise reduction processing in Step 5 has at least one corresponding correlation coefficient r; Step 7: Based on the signals recorded in Step 6, calculate the internal ballistic velocity of the magnetic launch member (4) at the positions of the sensors corresponding to the signals recorded in Step 6 based on the relationship between the step change of the magnetic induction intensity signal and the internal ballistic velocity, and complete the test.

6. The internal ballistic velocity test method based on magnetic induction intensity according to Claim 5, characterized in that: In Step 2, the pressure range of the high-pressure gas with the pressure meeting the design requirements is between 1 MPa and 10 MPa, and its specific value is set according to the launch velocity requirement, which is an empirical value.

7. The internal ballistic velocity test method based on magnetic induction intensity according to Claim 5, characterized in that: In Step 5, the specific filtering and noise reduction processing is as follows: Step B1: Assign a value to the filtering standard deviation σ of the Gaussian signal function in Gaussian smoothing filtering; The Gaussian signal function is: Where: G(x) represents the Gaussian signal function; σ represents the filtering standard deviation; x represents the collected magnetic induction intensity signal; Step B2: The collected magnetic induction intensity signal is subjected to Gaussian smoothing filtering using a Gaussian signal function with a given filtering standard deviation σ to remove high-frequency noise in the signal; Step B3: determining in real time whether the magnetic induction intensity signal after the Gaussian smoothing filter processing in step B2 is a visible curve; if so, the visible curve is the obtained magnetic induction intensity signal after the high-frequency noise is removed, and step B4 is executed; if not, a value is re-given to the filtering standard deviation σ of the Gaussian signal function in the Gaussian smoothing filter, and then returning to step B2; Step B4: The magnetic induction intensity signal obtained in step B3 after high-frequency noise removal is subjected to Butterworth low-pass filter processing to remove low-frequency noise in the signal, thereby obtaining a magnetic induction intensity signal after filtering and noise reduction processing, and completing filtering and noise reduction processing.

8. The method for measuring interior ballistic velocity based on magnetic induction intensity according to claim 7, characterized in that: In step B4, when the Butterworth low-pass filter processing is performed, the transfer function of the Butterworth low-pass filter is: Where: H(jw) represents the transfer function of the Butterworth low-pass filter, where jw represents the complex frequency variable; w represents the sampling frequency of the magnetic induction intensity signal; w c represents the frequency of the Butterworth low-pass filter, which is 50Hz; n represents the order of the Butterworth low-pass filter, which is 4.

9. The method for measuring interior ballistic velocity based on magnetic induction intensity according to claim 5, characterized in that: In step 6, the following formula is used to calculate the correlation coefficient r of each group of signals: In the formula: r represents the correlation coefficient; m represents the number of signal acquisition points; x i ,y i Respectively represent the magnetic induction intensity at the i-th acquisition point corresponding to each of the two magnetic induction intensity signals in the group of signals, where 1≤i≤m; They respectively represent the mean values ​​of the magnetic induction intensities at the m acquisition points corresponding to the two magnetic induction intensity signals in the group of signals.

10. The method for measuring interior ballistic velocity based on magnetic induction intensity according to claim 5, characterized in that: In step 7, when calculating the internal ballistic velocity of the magnetic transmitter (4) at the sensor position corresponding to each signal recorded in step 6, the calculation process of the internal ballistic velocity of the magnetic transmitter (4) at each sensor position is: Step C1: for the corresponding signal recorded in step 6, calculate the first-order difference of the signal; Step C2: 0.1 times of the maximum value of the first-order difference of the signal calculated in step C1 is used as the set mutation threshold; then the absolute value of the first-order difference of the signal calculated in step C1 is compared with the set mutation threshold respectively: if the absolute value of the first-order difference of the signal is greater than the set mutation threshold, it is determined that the signal has undergone a mutation at this location, and detection is performed within a set range before and after the mutation location on the signal to extract the mutation signal in the signal, and then the mutation duration of the signal step change and the mutation range of the magnetic induction intensity are obtained from the mutation signal; if the absolute value of the first-order difference of the signal is less than or equal to the set mutation threshold, it is determined that the signal has not undergone a mutation at this location, and no detection is performed; Step C3: According to the mutation duration of the signal step change and the mutation range of the magnetic induction intensity obtained in step C2, the internal ballistic velocity of the magnetic emission element (4) at the corresponding sensor position is calculated using the following formula: Where: V represents the internal ballistic velocity of the magnetic launcher (4) at the corresponding sensor position; k is the proportional coefficient, which is the calibration value; Represents the slope of the magnetic induction intensity signal step, where dB is the absolute value of the range endpoint difference corresponding to the mutation range of the magnetic induction intensity obtained in step C2, and dt is the mutation duration obtained in step C2.

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