A Detection and Control Method for a Capacitive Body-Hugging Explosive Fuse

Abstract

The present invention provides a capacitance-based ground-hugging explosion fuse detection and control method, which includes the following steps: arranging capacitance detection electrodes at the head of the fuse, and using an oscillation circuit to establish a quasi-electrostatic field in the space around the projectile body by the electrodes. When a target appears near the projectile body, the quasi-electrostatic field is disturbed, causing a corresponding regular change in the equivalent capacitance between the fuse electrodes. The detector extracts this change information through a detection circuit, and after filtering, amplification, and A / D sampling, the processor performs signal processing and gives a detonation signal to achieve ground-hugging explosion control; according to the characteristic that the capacitance change amount of the capacitance detection is inversely proportional to the cube of the distance, as the distance between the projectile and the target approaches, the target signal should first change slowly and then change extremely rapidly. By combining the two characteristics, the fast-changing interference target signal is eliminated to achieve the purpose of anti-interference. The present invention realizes reliable recognition and detonation control of different types of targets, especially soft targets, and can improve the reliability of the fuse.

Description

Technical Field

[0001] The present invention belongs to the field of fuze technology, and particularly relates to a detection and control method for a capacitance-based ground-touching explosion fuze, which uses a capacitance detection system to improve the triggering reliability of ammunition against soft targets under small impact angle conditions. Background Art

[0002] Generally, the firing angles of direct-fire weapons and air-to-ground rockets are very small. When equipped with impact fuzes and facing soft targets such as grasslands, swamps, and deserts, as well as small impact angles, there are often problems of unreliable firing, and the small impact angle triggering rate is relatively low. To solve the problem of the triggering reliability at small impact angles, various improved schemes for impact fuze mechanisms have emerged, such as adding a ground-touching explosion firing mechanism, reducing the sensitivity of the fuze, and increasing the number of switches distributed circumferentially on the fuze. To a certain extent, the triggering reliability has been improved, but it has also brought problems of premature explosion and safety, and cannot simultaneously meet the requirements of the fuze's insensitive and sensitive degrees.

[0003] The fuzes of armor-piercing projectiles for direct-fire weapons at home and abroad mainly have various firing mechanisms such as stab-fire-cap inertial triggering, power supply control with a contact switch, power supply wind cap control structure, wind cap-pin-shaped electrode structure contact switch, and spring-mass structure inertial contact switch. Among them, the spring-mass structure inertial contact switch mechanism is placed in the head mechanism and closes by relying on inertial force or forward impact force. This mechanism belongs to a single-degree-of-freedom spring-mass system and can only sense the force in a single direction, and the sensitivity consistency in all directions during ground contact is relatively poor; the closing process of the rigid moving electrode contact switch is relatively long, and the electrical connection stability is poor, which does not meet the requirements of the fuze's instantaneous initiation and ground contact sensitivity, and the ground contact firing performance at small impact angles is very poor, not meeting the requirements of the high ground contact firing rate of the armor-piercing projectile fuze at small impact angles. The fuze equipped on a certain type of air-to-ground rocket is a warhead electro-mechanical impact fuze. The inertial triggering mechanism of this fuze consists of four lateral impact explosion switches and two axial universal switches evenly distributed circumferentially along the fuze. During the test, there was a problem of premature explosion, and the fuze had problems such as low sensitivity, complex structure of the inertial triggering switch, and low reliability.

[0004] To address the key problem of the low action rate of ammunition fuzes at small impact angles, research on capacitance-based ground contact triggering and firing control technology with miniaturization and high reliability is carried out, which has important military significance and practical significance for further improving the comprehensive combat performance of ammunition. Summary of the Invention

[0005] The purpose of the present invention is to provide a fuze design with a highly reliable ground contact triggering function, and to propose a detection and control method for a capacitance-based ground-touching explosion fuze to solve the problem of low action reliability under the conditions of direct-fire weapons and air-to-ground rockets attacking soft targets or shooting at small impact angles.

[0006] The method for achieving the object of the present invention is as follows: A capacitance body-hugging blasting fuse detection and control method. Capacitance detection electrodes are arranged at the head of the fuse. Through an oscillation circuit, the electrodes establish a quasi-electrostatic field in the space around the projectile. When a target appears near the projectile, this quasi-electrostatic field is disturbed, causing a corresponding regular change in the equivalent capacitance between the fuse electrodes. The detector extracts this change information through a detection circuit, and after filtering, amplification, and A / D sampling, the processor processes the signal and gives a detonation signal to achieve body-hugging blasting control. According to the characteristic that the capacitance change amount of the capacitance detection is inversely proportional to the cube of the distance, as the distance between the projectile and the target approaches, the target signal should first change slowly and then change extremely rapidly. Combining these two characteristics, fast-changing interference target signals such as rain, snow, small branches, and weeds can be eliminated to achieve the purpose of anti-interference.

[0007] To adapt to large and small impact angle intersection conditions, an inclination sensor is used to identify the impact angle of the ammunition.

[0008] The specific implementation includes the following steps:

[0009] Step 1: According to the capacitance detection principle and the projectile structure, design the double-electrode arrangement for capacitance detection.

[0010] Step 2: Apply a sinusoidal oscillation of about 2 MHz to the detection electrodes. When the projectile approaches the target, the oscillation amplitude changes. The detection circuit extracts this amplitude change information as the target signal, and the signal is amplified by the filtering and amplification circuit.

[0011] Step 3: Perform A / D sampling on the signal in Step 2. At the same time, use the inclination sensor to detect the impact angle in real time, and set the signal characteristic change thresholds for the target at long distance and short distance according to the impact angle attitude.

[0012] Step 4: As the distance between the projectile and the normal target changes from far to near, if the target signal first satisfies the slow change characteristic at long distance and then satisfies the fast change characteristic at short distance, it is determined as a normal target; if the fast change characteristic of the short-distance target signal appears first without the slow change characteristic, it is determined as an interference target.

[0013] Step 5: If no target is determined, re-execute Step 2; otherwise, if a normal target is determined, output a detonation signal.

[0014] The present invention has the following beneficial effects:

[0015] (1) Utilize the characteristic that the target signal changes extremely rapidly when approaching the target by capacitance detection to achieve reliable identification and detonation control of different types of targets, especially soft targets, and improve the action reliability of the fuse.

[0016] (2) Conduct impact angle identification, set dynamic target signal processing thresholds, and achieve highly consistent body-hugging blasting control under different projectile-target intersection conditions.

[0017] (3) According to the dynamic change characteristics that the target signal slowly changes first and then rapidly changes when the projectile-to-target distance is approaching, the interference of rain, snow, branches, weeds, etc. is realized.

[0018] (4) Using capacitance detection to achieve the function of ground-touching explosion control, avoiding the use of high-sensitivity impact switches, which can improve the safety during ammunition handling and launching processes. Description of the Drawings

[0019] Figure 1 It is the schematic diagram of a ground-touching explosion control method for a capacitance fuze provided by the present invention.

[0020] Figure 2 It is the detection signal effect diagram of a capacitance detection digital demodulation method provided by the present invention.

[0021] Figure 3 It is the target signal curve diagram under a typical intersection condition in the embodiment.

[0022] Figure 4 It is the signal processing block diagram of a ground-touching explosion control method for a capacitance fuze provided by the present invention. Detailed Embodiment

[0023] The following will make a detailed description of the specific embodiment provided by the present invention in conjunction with the drawings.

[0024] As Figure 1 shown, according to the capacitance detection principle and the projectile structure, the finite element simulation of the double-electrode size arrangement is carried out to obtain the best electrode arrangement relationship and obtain the optimal sensitivity. After the projectile is launched, the on-board battery supplies power to the fuze, and the fuze establishes a sine oscillation of about 2 MHz on the detection electrode. When the projectile approaches the target, it causes a change in the oscillation amplitude. The detection template extracts the change in the oscillation amplitude, filters the detected signal, and then the processor performs signal processing to achieve detonation control.

[0025] Traditional capacitance detection demodulation uses diode envelope demodulation, that is, by using the unidirectional conduction characteristic of the diode, when the input voltage is greater than the diode conduction voltage, the capacitor C is charged, and when the input voltage is less than the diode conduction voltage, the capacitor C discharges, thereby realizing demodulation. The selection of the values of the R and C elements in the diode demodulation module has a great influence on the demodulation effect, and it is difficult to adapt to various intersection speeds and various intersection angles of different ammunitions.

[0026] The present invention adopts two signal envelope digital demodulation methods based on Hilbert transform and extreme value method. As Figure 3 shown, it is the envelope of the oscillation signal detected by applying the digital demodulation method, which can effectively reflect the amplitude change of the oscillation signal and can adapt to various projectile-to-target intersection conditions.

[0027] The Hilbert transform is equivalent to an orthogonal filter, but it does not change the amplitude of the signal. By constructing an analytic signal, with the original signal as the real part and the signal after the Hilbert transform as the imaginary part, the analytic signal is obtained as shown in Equation (3):

[0028]

[0029] The Hilbert envelope can be expressed as:

[0030]

[0031] The basic principle of detecting the signal envelope by the extreme value method is as follows: For the signal sequence x(t) = [x(1), x(2), …, x(n)], first perform a difference calculation on the sequence to judge the change trend of the signal sequence within the interval range, and then screen the maximum and minimum values according to the change trend. The upper envelope of the signal is restored by the spline interpolation method between two maximum values, and the lower envelope of the signal is restored by the spline interpolation method between two minimum values.

[0032] As Figure 2 shown, it is the target detection signal curve during the actual projectile approaching the target. When the projectile is 0.6 m to 0.3 m away from the ground target, the amplitude of the target signal slowly decreases. When the projectile further approaches the target to a distance below 0.2 m, the amplitude of the target signal rapidly decreases. When the projectile encounters rain, snow, branches, and weeds during flight, there will be multiple rapid decrease characteristics, rather than the characteristics of first slowly decreasing and then rapidly decreasing consistent with the target.

[0033] As Figure 3 shown, to implement signal processing and detonation control according to the signal characteristics Figure 2 shown, the following steps need to be completed:

[0034] (1) Collect the output of the inclination sensor, identify the large and small fall angles, and set the threshold values of the amplitude threshold, amplitude change amount, and amplitude change rate under the large and small fall angle conditions respectively;

[0035] (2) Control the A / D to sample the target signal;

[0036] (3) Amplify, differentiate, and integrate the signal. According to the threshold values set in (1), judge whether the amplitude threshold, amplitude change amount, and amplitude change rate simultaneously satisfy the opening of the AND gate. If they do not satisfy simultaneously, repeat step (2) for the next sampling; if they satisfy simultaneously, judge whether it meets the slow change characteristic or the fast change characteristic according to the time when the amplification, differentiation, and integration processing reach the threshold value, and mark whether it meets the slow change characteristic or the fast change characteristic;

[0037] (4) Process the determination in step (3) in three categories: a. If a slow-varying feature appears, return to (2); b. If a fast-varying feature appears and the mark has never had a slow-varying feature, it is determined as interference and the next sampling is performed; c. If a fast-varying feature appears and the mark has had a slow-varying feature, it is determined as the target and the detonation signal is output;

[0038] (5) For the slow-varying feature and the fast-varying feature to be marked as appearing only after appearing multiple times, the specific determination count setting needs to be determined according to the intersection speed and intersection angle of different ammunition applications.

Claims

1. A capacitance body ground-hugging explosive fuse detection and control method, characterized in that, It includes the following steps: Arrange capacitive detection electrodes at the head of the fuse. Through an oscillation circuit, the electrodes establish a quasi-electrostatic field in the space around the projectile. When a target appears near the projectile, this quasi-electrostatic field is disturbed, causing a corresponding regular change in the equivalent capacitance between the fuse electrodes. The detector extracts this change information through a detection circuit, and after filtering, amplification, and A / D sampling, the processor processes the signal and gives a detonation signal to achieve ground-hugging explosion control; According to the characteristic that the capacitance change of the capacitive detection capacitor is inversely proportional to the cube of the distance, as the distance between the projectile and the target approaches, the target signal should first change slowly and then change extremely rapidly. By combining these two characteristics, the fast-changing interference target signal is eliminated to achieve the purpose of anti-interference; The specific implementation includes the following steps: Step 1: Design the double-electrode arrangement for capacitive detection according to the capacitive detection principle and the projectile structure; Step 2: Establish a sine oscillation on the detection electrodes. When the projectile approaches the target, the oscillation amplitude changes. The detection circuit extracts this amplitude change information as the target signal, and the signal is amplified by the filtering and amplification circuit; Step 3: Perform A / D sampling on the signal in Step 2. At the same time, the angle of fall is detected in real time through an inclination sensor, and the signal characteristic change thresholds at long distance and short distance of the target are set according to the angle-of-fall attitude; Step 4: The distance between the projectile and the normal target is from far to near. If the target signal first satisfies the slow change characteristic at long distance and then satisfies the fast change characteristic at short distance, it is recognized as a normal target; if the fast change characteristic of the short-distance target signal appears first without the slow change characteristic, it is recognized as an interference target; Step 5: If no target is recognized, repeat Step 2; Otherwise, it is recognized that there is a normal target and a detonation signal is output.

2. A capacitance body surface-mounted blasting fuse detection and control method according to claim 1, characterized in that In Step 1, a sine oscillation of 2 MHz is established on the detection electrodes.

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