Arrayed electrostatic sensor, projectile velocity measuring device and method based on the sensor

Abstract

The application is an array type electrostatic sensor, a projectile velocity measuring device and method based on the sensor. The array type electrostatic sensor is in the shape of a tube coaxially arranged behind the projectile outlet and the barrel or bore body, and a plurality of circumferentially arrayed graphite electrodes in a pleated triangle structure are arranged at the upstream and downstream cross sections along the axis of the tube. The measuring device comprises an induction unit, a signal conditioning unit and an analysis and calculation unit, obtains the electrostatic induction signal component belonging to the projectile, then according to the velocity range of different projectile models, selects the electrostatic induction signals of the electrodes at different positions in different cross sections to reconstruct the charge distribution and establish the cross correlation sensitivity matrix, and further based on the correlation focusing principle of the electrodes at different cross sections, proposes a data fusion algorithm of multiple sensor electrodes, and finally measures the muzzle projectile velocity. The application proposes to use electrostatic field sensing measurement as a new means for projectile testing in view of the complex environment of high temperature and high pressure at the muzzle.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of artillery projectile velocity measurement, and particularly relates to an array type electrostatic sensor, a projectile velocity measurement device and method based on the sensor. BACKGROUND

[0002] The firing process of artillery is a process in which high-temperature and high-pressure gunpowder gas propels a projectile to move at high speed along the barrel axis. The accurate measurement of muzzle initial velocity is directly related to the accuracy of exterior ballistic calculation and affects the hit rate of the projectile. The muzzle initial velocity refers to the measured velocity of the projectile when it escapes from the muzzle of the gun and still maintains the inertial effect, which can be seen in "Qin L, Fan JY, Li J, et al. Projectile muzzle initial velocity and attitude measurement method analysis and comparison[J]. Journal of Artillery Firing and Control, 2013(4):6". Due to the high-speed rotation and high overload movement of the projectile flying out of the muzzle, accompanied by high-temperature and high-pressure gunpowder gas, smoke and other harsh environments, it is difficult to measure the muzzle initial velocity. The commonly used methods for measuring the muzzle velocity of the projectile mainly include contact measurement method and non-contact measurement method. The contact measurement method measures the time when the projectile contacts the measuring device to calculate the velocity of the projectile when measuring the flight time of the projectile. The measuring device mainly includes a copper wire target and a tin foil target. The contact measurement method has simple principle, but the measurement is greatly affected by the artillery itself. Since the artillery is usually accompanied by a large amount of smoke, fire, ion dust and other phenomena when firing, it often causes problems such as difficulty in extracting zero point, which leads to a decrease in accuracy, which can be seen in "Jia Y, Han Y. A novel device for measuring velocity of projectile[J]. Transactions of the Institute of Measurement and Control, 2016, 38(9):1023-1032.". In addition, the zone intercept target measurement method in most contact measurement methods sets up two targets at a short distance on the measuring trajectory, measures the time difference of the projectile passing through the two targets to calculate the average velocity in this interval, and replaces the instantaneous velocity with this velocity, which can be seen in "Chen ZY, Wu WL. Coil target velocity measurement error analysis[J]. Measurement Technology, 2000, 5:12-14.". However, the zone intercept target measurement method destroys the structure of the barrel and is only suitable for weapon equipment laboratory occasions, which is difficult to popularize in the army practice.

[0003] The non-contact measurement method is greatly improved compared with the contact measurement method, and main velocity measuring devices include coil target, sky screen target, light screen target, high-speed camera and millimeter wave velocity radar, etc. In the non-contact measurement method, the coil target velocity measurement method has high measurement cost and cannot measure the muzzle velocity of common ammunition, so it is not suitable for popularization and use in the army; the light screen target velocity measurement method has high precision, but the organization and implementation are relatively complex and have high requirements for external environment; the high-speed camera velocity measurement method has high precision, but is easily limited by weather factors; in terms of precision, the millimeter wave radar has the highest velocity measurement precision, but is easily exposed due to obvious electric measurement radiation, so is not suitable for actual combat, and can be referred to in 'Jin Xiwen. Artillery dynamic test technology[M]. National Defense Industry Press, 2007.' Moreover, for multi-barrel high-speed naval gun, due to high firing speed, ionized gas and smoke exist in the muzzle area, so the millimeter wave radar cannot normally work in the muzzle area.

[0004] In summary, the high-temperature and high-pressure gunpowder gas and unburned ammunition powder in the gun bore bring great difficulty to real-time and accurate measurement of the projectile velocity by using the above methods, and this has been an important research focus in the field of artillery testing. SUMMARY

[0005] The purpose of the present application is to provide an array type electrostatic sensor with high signal-to-noise ratio and high temperature and pressure resistance, and an artillery projectile velocity measurement device and measurement method based on the array type electrostatic sensor.

[0006] The technical solution for achieving the purpose of the present application is: an array type electrostatic sensor, the array type electrostatic sensor has a tubular shape and is coaxially arranged behind the projectile outlet and the barrel or bore, and a plurality of wrinkle type-triangle structure graphite electrodes are arranged in a circumferential array on the upstream and downstream cross sections along the axis of the tubular shape, each wrinkle type-triangle structure graphite electrode has an inner layer of graphite electrode wrapped by outer layers of silicon carbide ceramic, the graphite electrode layer has a sawtooth shape with a triangle shape towards the center of the circle, and the outermost layer of the graphite electrode layer is connected to a terminal post.

[0007] Further, the tubular shape is arranged at a distance of 1-5 m behind the projectile outlet by an external support, and the inner diameter of the tubular shape satisfies the condition that the projectile passes through the tubular shape without contacting the inner wall of the tubular shape.

[0008] Further, the plurality of wrinkle type-triangle structure graphite electrodes are uniformly embedded in the inner wall of the tubular shape in a circumferential array.

[0009] Further, the number of wrinkle type-triangle structure graphite electrodes at the upstream and downstream cross sections is 16, and the thickness of the inner layer of the wrinkle type-triangle structure graphite electrodes is not greater than 5 mm.

[0010] A projectile velocity measurement device uses the above array type electrostatic sensor as a sensing unit.

[0011] Further, it also includes a signal conditioning unit and an analysis and calculation unit;

[0012] The signal conditioning unit is used to filter and amplify the induction signals generated by the projectile movement. The conditioned signals are input to the analysis and calculation unit, which calculates the measured muzzle velocity.

[0013] Further, the signal conditioning unit includes a charge conversion circuit, a band-pass filter circuit, a two-stage amplifier, and a power supply and shielding box.

[0014] Further, the analysis and calculation unit reconstructs the charge distribution according to the velocity range of different projectile models and selects different positions of the electrodes in different cross sections to establish a cross-correlation sensitivity matrix. Based on the correlation focusing principle of different cross-section electrodes, a data fusion algorithm of multiple sensor electrodes is proposed to ultimately measure the muzzle velocity.

[0015] A projectile velocity measurement method based on the above device, comprising the following steps:

[0016] Step (1): Obtain the electrostatic signals U A and U B using different electrode pairs on the upstream Section A and downstream Section B of the silicon carbide-graphite array electrode electrostatic sensor.

[0017] Step (2): Reconstruct the charge distribution Q A and Q B of the upstream Section A and downstream Section B inside the tube using the filtered back-projection algorithm FBP, and then calculate the cross-correlation sensitivity matrix of the upstream and downstream electrodes.

[0018] Step (3): Derive the measured projectile cross-correlation velocity v ij using the induction signals of the upstream i-th electrode and the downstream j-th electrode, and the formula is:

[0019]

[0020] L is the distance between the upstream and downstream electrodes, and is the time difference of the projectile at the upstream i-th electrode and the downstream j-th electrode.

[0021] The cross-correlation velocity matrix V CC obtained by different electrode pairs on the upstream and downstream electrodes is:

[0022]

[0023] v ijis the cross-correlation velocity calculated from the signals measured by the upstream i-th electrode and the downstream j-th electrode; N is the number of electrodes in a single section;

[0024] Step (4): obtaining the projectile velocity distribution V d * is:

[0025]

[0026] is the generalized inverse matrix of the cross-correlation sensitivity matrix, and finally V d * The average value is taken as the muzzle projectile velocity.

[0027] Further, step (2) is specifically: calculating Q A and Q B The specific is:

[0028]

[0029]

[0030] S A T and S B T is the transpose matrix of the spatial sensitivity matrix S A and S B , S max is the maximum value in the spatial sensitivity matrix of all electrodes in the A or B section, S A1 , S A2 , …, S AM are the spatial sensitivities of the 1st, 2nd, …, Mth electrodes in the A section respectively; S B1 , S B2 , …, S BM are similar;

[0031] Then the cross-correlation sensitivity matrix of the upstream and downstream electrodes is calculated The calculation formula is:

[0032]

[0033] is the improved cross-correlation sensitivity between the i-th electrode upstream and the j-th electrode downstream in the region k.

[0034] Compared with the prior art, the present application has the following advantages:

[0035] The present application is directed to the complex environment of high temperature and high pressure at the muzzle, proposes to use electrostatic field sensing measurement as an important technology for projectile testing, and designs a new type of structure sensor, which is both a technical innovation and a mechanism innovation in the theory of muzzle projectile velocity measurement. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is an array type electrostatic sensor projectile velocity detection device schematic diagram.

[0037] Figure 2 It is a flow chart of the projectile velocity measurement method of the electrostatic velocity tomography method considering charge distribution.

[0038] Figure 3 It is a schematic diagram of a crumpled triangular graphite electrode. DETAILED DESCRIPTION

[0039] The present application will be further described in detail below in combination with the drawings.

[0040] Referring to Figure 1 , the embodiment of the present application provides an array type electrostatic sensor detection device for muzzle projectile velocity measurement, which comprises an induction unit, a signal conditioning unit and an analysis and calculation unit. The high temperature and high pressure resistant array electrode 1 in the induction unit acquires electrostatic signals; the signal conditioning unit comprises a charge conversion circuit 2, a band-pass filter circuit 3, a two-stage amplifier 4, a power supply and a shielding box 5, extracts electrostatic induction signals from the collected electrostatic signals, filters and amplifies; the analysis and calculation unit 6 comprises signal extraction and velocity measurement, which can extract induction signals and acquire muzzle projectile velocity.

[0041] Referring to Figure 3 , the induction unit is a crumpled triangular graphite electrode shape, and the graphite electrode structure is wrapped with a sandwich type silicon carbide.

[0042] The signal extraction and velocity measurement comprises a projectile velocity measurement method of the electrostatic velocity tomography method considering charge distribution, and the main steps are as follows:

[0043] 1. Referring to Figure 2 , first, the carbonized silicon-graphite array electrode electrostatic sensor is used to collect electrostatic induction signals U A and U B of the upstream and downstream sections (Section A and Section B).

[0044] 2. The charge distribution Q A and Q B of sections A and B inside the tube are reconstructed by using the filter linear back projection algorithm (FBP) imaging algorithm.

[0045] Among them, the filter linear back projection algorithm (FBP) is used to calculate QA and Q B The formula is:

[0046]

[0047]

[0048] S A T and S B T is the spatial sensitivity matrix S A and S B is the transpose matrix of S max is the maximum value of the spatial sensitivity matrix of all electrodes of the A or B section, S A1 , S A2 , …, S AM are the spatial sensitivities of the 1st, 2nd, …, Mth electrodes of the A section respectively. B1 , S B2 , …, S BM are similar.

[0049] Then the cross-correlation sensitivity matrix of the upstream and downstream electrodes is calculated The calculation formula is:

[0050]

[0051] is the improved cross-correlation sensitivity between the ith electrode of the upstream and the jth electrode of the downstream in the region k.

[0052] 3. The measured cross-correlation velocity v ij of the projectile is derived using the induced signals of the ith electrode of the upstream and the jth electrode of the downstream, and the formula is:

[0053]

[0054] L is the distance between the upstream and downstream electrodes, and is the time difference of the projectile at the ith electrode of the upstream and the jth electrode of the downstream.

[0055] The cross-correlation velocity matrix V CC obtained by different electrodes of the upstream and downstream is:

[0056]

[0057] v ij is the cross-correlation velocity calculated from the measured signals of the ith electrode of the upstream and the jth electrode of the downstream. N is the number of electrodes in a single section.

[0058] 4. The velocity distribution V d *To:

[0059]

[0060] The generalized inverse matrix of the cross-correlation sensitivity matrix is V d * The average value is taken as the muzzle velocity of the projectile.

[0061] The present application aims at the problem that the complex and uneven charge distribution of the muzzle brings errors to the velocity tomography method, and the cross-correlation sensitivity is improved by introducing the actual charge distribution and the spatial sensitivity of the electrode, and the muzzle projectile velocity distribution measurement is realized by means of the cross-correlation velocity between the upstream and downstream electrodes, which provides an important means for accurately estimating the real average velocity of the projectile.

Claims

1. An array-type electrostatic sensor, characterized in that, The array-type electrostatic sensor is a tube set coaxially with the gun barrel or bore after the projectile exit. Multiple circumferentially arrayed pleated-triangular graphite electrodes are provided at both the upstream and downstream sections along the axis inside the tube. Each pleated-triangular graphite electrode has an inner graphite electrode layer wrapped by inner and outer silicon carbide ceramic layers. The graphite electrode layer is triangular and serrated towards the center. The outermost layer of the graphite electrode layer is connected to a terminal. Multiple pleated-triangular graphite electrodes are uniformly embedded in the inner wall of the tube along the circumference; The number of pleated-triangular graphite electrodes at both the upstream and downstream cross-sections is 16, and the thickness of the inner layer of the pleated-triangular graphite electrodes is no more than 5 mm.

2. The array-type electrostatic sensor according to claim 1, characterized in that, The tube is installed 1-5m after the bullet exit via an external support. The inner diameter of the tube is such that the bullet can pass through the tube without contacting the inner wall of the tube.

3. A projectile velocity measuring device, characterized in that, The array-type electrostatic sensor according to any one of claims 1-2 is used as the sensing unit.

4. The apparatus according to claim 3, characterized in that, It also includes a signal conditioning unit and an analysis and calculation unit; The signal conditioning unit is used to filter and amplify the induced signal generated by the projectile motion. The conditioned signal is then input to the analysis and calculation unit, which calculates the muzzle velocity of the projectile.

5. The apparatus according to claim 4, characterized in that, The signal conditioning unit includes a charge conversion circuit (2), a bandpass filter circuit (3), a secondary amplifier (4), and a power supply and shielding box (5).

6. The apparatus according to claim 5, characterized in that, The analysis and calculation unit reconstructs the charge distribution and establishes a cross-correlation sensitivity matrix by selecting electrostatic induction signals from electrodes at different positions within different cross sections according to the velocity range of different projectile models. Based on the correlation focusing principle of electrodes with different cross sections, a data fusion algorithm for multiple sensor electrodes is proposed, and the muzzle velocity of the projectile is finally measured.

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