Table of Content

30 October 2013, Volume 34 Issue 10

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Paper

Dynamic Modeling and Simulation for Firing Line Stabilization System of Self-propelled Antiaircraft Gun

LI Wei, HAN Chong-wei, ZHANG Tai-ping, ZHAO Wei, CHEN Teng-fei

2013, 34(10):  1201-1208.  doi:10.3969/j.issn.1000-1093.2013.10.001

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According to the mechanical structure feature of firing line stabilization system of self-propelledantiaircraft (SPAA) gun, the shaft torque characteristics of torque motor in the case of direct drive areresearched. The moment of momentum theorem and the superposition theorem are used to establish aNewton-Euler dynamic model for SPAA firing line stabilization system, and the dynamic characteristics ofturret revolution body and gun elevation axis under the conditions of vehicle motion and shooting impactdisturbance are simulated. The simulation results show that the cross coupling torque brought to the turretrevolution body due to the vehicle motion is the main disturbance torque to which the turret revolutionbody is subjected, and the control moment of azimuth axis and the disturbance torque of elevation axis in-crease with the increase in shooting angle. The inertial moment at high angle makes the control moment ofazimuth axis increases faster, and the disturbance torque of elevation axis and the disturbance torque ofazimuth axis at low angle are the main components of corresponding shaft control moment. The resultsprovide a foundation for designing of SPAA firing line stabilization system.

Study on Influence of Structural Arrangement of Recoil Mechanism on Muzzle Vibration of Gun

LIANG Chuan-jian, YANG Guo-lai, GE Jian-li, WANG Xiao-feng, ZHANG Zhen-hui

2013, 34(10):  1209-1214.  doi:10.3969/j.issn.1000-1093.2013.10.002

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Muzzle vibration is one of the most important factors influencing the firing dispersion of gun. Inorder to study the technical approaches to reducing the muzzle vibration, a launch dynamic model of alarge caliber gun is established based on the nonlinear finite element theory, in which the contact impactbetween interacting components is considered. The influences of different fixed forms and different locations of the counter-recoil mechanism and recoil mechanism on muzzle vibration are studied by numericalcomputation, and the load transfer rules of the guns with different structural arrangements are analyzed.The optimal structural arrangement is determined by contrastively analyzing the muzzle vibration responses. The results can provide theoretical reference to the overall structure design of the gun systems.

Research on Influence of Muzzle Brake Efficiency on Firing Density of Gatling Gun

LI Jia-sheng,LIAO Zhen-qiang,SONG Jie,XIAN Dong-peng

2013, 34(10):  1215-1220.  doi:10.3969/j.issn.1000-1093.2013.10.003

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In order to apply high-efficient muzzle brake to a large caliber gatling gun system,the muzzlebrake efficiency is calculated based on the gas dynamic equation of supersonic airflow. A rigid-flexiblemulti-body model is established on the basis of rigid-flexible coupling dynamics modeling theory, and the dynamics simulation and exterior ballistic calculation are performed for the shooting of gatling guns withdifferent muzzle brakes on a light tripod. The results show that increasing channel angles can significantly improve the muzzle brake efficiency and reduce the recoil displacement and velocity,restrain the elasticdeformations of tripod and barrel, as well as improve the firing stability and density of gatling gun system.The effect of brake is weakened if the channel angles exceed 120毅.

Research on Rolling and Fragmentation Mechanism of Non-penetrating Rifle Bullets

JIN Yong-xi, CHEN Bo, ZHANG Jing-min, WANG Shu, CUI Hai-lin, TAN Zhong-yu

2013, 34(10):  1221-1226.  doi:10.3969/j.issn.1000-1093.2013.10.004

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The current standard military bullets have excessive penetration power at close range. After abullet cuts through the body, its remaining energy can cause a highly lethal effect, which is unable tomeet the combat requirements of counter-terrorism and anti-hijacking. So there is an urgent need to develop the non-penetration and highly lethal technology for rifle bullets. A rolling motion model of bullet inthe muscles is established and the centrifugal fragmentation mechanism of bullet is revealed by analyzingthe basic control principle of penetration depth. The numerical simulation is used to discuss the main factors which affect the rolling and fragmentation of bullet. The rolling and fragmentation process of non-penetrating rifle bullet in gelatin target is revealed by experiment. The research results show that the centrifugal force generated by rolling bullet can make the soft bullet crushed, and the center-of-mass position ofbullet is a sensitive factor to affect the rolling of bullet. The rolling state of bullet can be controlled by adjusting the center-of-mass position of bullet, and compared with the standard rifle bullet, the penetrationdepth of new bullet can be reduced to 1/2 to reach the non-penetration and highly lethal effect by improving the bullet velocity and reducing the thickness and strength of bullet shell.

Measurement Method of Launch Caliber Expansion Deformation of Electromagnetic Railgun

WEN Yin-tang, WANG Hong-rui, ZHANG Yu-yan, WANG Zhen-chun, ZHAN Zai-ji, LIANG Bo

2013, 34(10):  1227-1230.  doi:10.3969/j.issn.1000-1093.2013.10.005

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During the electromagnetic launching process, the caliber of electromagnetic railgun may be expanded due to the electromagnetic force generated by the acute current. The caliber expansion has an effect on the repeated launch stability of the electromagnetic railgun. A novel high-speed linear array CCD measurement system was developed to detect this caliber expansion. The images obtained by the measurement system are analyzed using software methods. The results show that there is a linear relationship between caliber expansion and launching current, and the higher the launching current is, the larger the caliber expansion value is. The high-speed linear array CCD measurement system can measure the deformation of expanded caliber precisely in the sub-pixel dimension in a very short time.

Accurate Estimation of Motion Blur Parameters at Short Blurred Extent Based on Radon Transform

DUAN Ruo-ying, CHEN De-rong, JIANG Yu-ping, GUAN Yong-mei, GAO Xiang-xiao

2013, 34(10):  1231-1235.  doi:10.3969/j.issn.1000-1093.2013.10.006

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An improved algorithm based on Radon transform is proposed to identify the motion blur parameters of image at short blurred extent more accurately. Considering that the spectrogram of motion blurred image is transformed into an alternate dark and bright projection line at perpendicular direction of dark stripe by Radon transform, the position of alternate dark and bright projection line in Radon transform image should be determined. The motion blur parameters can be determined by the Radon transform angle which corresponds to the projection line and the resolution of motion blurred image. The experimental results show that the estimated error in blurred direction is less than 1°and the estimated error of blurred extent is less than 0. 5 pixels when the blurred extent is 5 ~10 pixels. The estimation accuracy of improved algorithm is higher than other algorithm at short blurred extent.

Simulation Design of a High Q Tunable Capacitor with Comb Structure

LI Yan-ning, RUAN Yong, YOU Zheng, XU Hong-wei, LI Yu-gang

2013, 34(10):  1236-1242.  doi:10.3969/j.issn.1000-1093.2013.10.007

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A design scheme of micro-electro-mechanical system (MEMS) tunable capacitor with comb structure is proposed. Simulation design was implemented in terms of structure, electrical properties and process. FEM simulation indicates that, for the tunable capacitor, the capacitance tuning ratio is 3. 45：1, the tuning range is 88. 16 ~392. 19 fF at 67 V drive voltage, the resonant frequency is 36 GHz, Q fac- tor is 223 (1 GHz), and the reflection attenuation is 0. 002 25 dB, insertion loss is 42. 75 dB, respec- tively. Compared with other tunable capacitors, the design has high Q, high adjustable capacitance rate and simple process.

Joint Resolution of Velocity and Acceleration of Maneuvering Target

LI Wen-chen, LI Hong, YANG Hui-min, WANG Ling-yan

2013, 34(10):  1243-1249.  doi:10.3969/j.issn.1000-1093.2013.10.008

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Based on the Radon-Wigner transform (RWT), the Doppler resolution and extraction are studied for velocity and acceleration of maneuvering target. The pulse Doppler radar echo model of maneuvering target and the Fourier transformation processing method are offered. The RWT method is used to estimate the parameters of maneuvering targets. The Taylor analytical expression, the velocity and acceleration independent resolution expression and the joint resolution expression are proposed. It is indicated that the motion parameters can be distinguished if the path deviation between different maneuvering targets reaches one-half wavelength. The resolution capabilities of Fourier transform,Radon-ambiguity transform(RAT) and RWT method are simulated and compared. The simulation results show that RWT has the strong resolution capability of velocity and acceleration. The joint resolution condition of velocity and acceleration is validated.

Multi-index Comprehensive Evaluation of Camouflage Based on Gray Theory

WANG Zhan, YAN Yun-hui, JIAO Xue-yong

2013, 34(10):  1250-1257.  doi:10.3969/j.issn.1000-1093.2013.10.009

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In order to solve the problems of that the camouflage evaluation index is too single and the evaluated results is lack of objectivity, a new comprehensive evaluation method which uses many camouflage evaluation indexes and is based on gray clustering theory is presented. At first, according to the purpose and object of evaluation, this method selects brightness contrast, color features, texture features, edge shape and spot size as the indexes of evaluation system;Secondly, the entropy method is presented in order to solve the weight of each index under the same background; At last, the camouflage effect is comprehensively evaluated by use of grey clustering decision evaluation algorithm. The different camouflage design schemes are experimentally evaluated in the same background. The result shows that the method is an objective and reliable comprehensive camouflage evaluation technology.

Angular Glint Modeling Algorithm of Phase-comparison Sum-difference Monopulse Radar Based on Deterministic Model

WANG Wei, CUI Wei

2013, 34(10):  1258-1265.  doi:10.3969/j.issn.1000-1093.2013.10.010

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A novel phase-comparison sum-difference monopulse radar angular glint modeling algorithm based on deterministic model is proposed by analyzing the shortage of conditional angular glint deviation models based on energy flow tilt theory and wave front distortion theory. The number of scattering dots and the parameters of radar can be set in this model, and the echo signals of summing channel and differential channel needed by angle measurement verification can be obtained. Theoretical analysis and simulation results show that the novel model is more accurate for the large deviation angle of each scattering point. This model is more conducive to the simulation of angular glint suppression algorithm.

Detection of Artillery Blast Point Based on Principal Component Pursuit and Analysis

QIN Xiao-yan, YUAN Guang-lin

2013, 34(10):  1266-1272.  doi:10.3969/j.issn.1000-1093.2013.10.011

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The blast point detection is a foundation of fire correction, damage evaluation and opposite firepower point estimation. Based on principal component pursuit and analysis, the proposed blast point detection method consists of foreground recovery and blast point detection. Firstly, the candidate targets are recovered from image sequence by using principal component pursuit (PCP). Then the blast points are detected with the linearity and motion direction features which are calculated via principal component analysis (PCA). Experimental results on large number of blast point image sequences show that the proposed method has superior performance in correct detection rate and false positive rate in comparison with the existing blast point detection method.

Method for Measuring Coordinates of Simultaneous Two-projectile Impact on Target

DONG Tao, HUA Deng-xin, LI Yan, NI Jin-ping

2013, 34(10):  1273-1278.  doi:10.3969/j.issn.1000-1093.2013.10.012

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In consideration of the fact that the current automatic measuring systems for impact coordinates fail to measure the coordinates of simultaneous two-projectile impact on target, a coordinate measuring scheme of simultaneous two-projectile impact on target based on a linear array CCD camera is presented. A high speed linear CCD camera, two different wavelength semiconductor lasers and a projection board are used in the scheme. The detection light screen of CCD camera, the light screen of the two lasers and the projection plane of projection board are placed in a plane. When two projectiles pass through the detection light screen at the same time, they block out partial laser light projected on the projection board and leave their shadows on it, meanwhile the shadows and images of the two projectiles are acquired by the CCD camera. The shadows and images are differentiated to obtain the position coordinates of projected points by using a computer image processing method, and then the coordinates of simultaneous two-projectile impact on target are obtained by a mathematic model based on the principle of straight line inter- section. The measuring principle and formulas are provided, and the measuring error is simulated and an- alyzed. Experimental results show that the error of the actual measurement value and the theoretical anal- ysis are consistent. The measuring principle can be used to successfully measure the coordinate of simul- taneous two-projectile impact on target, and the measuring system based on the measuring principle can be applicable to measure the impact coordinates of projectiles of high RF weapons and multibarrel weapons.

Improved Navigation Algorithms Based on Split Integration for Strapdown Inertial Navigation System

LIN Yu-rong, SHEN Yi

2013, 34(10):  1279-1285.  doi:10.3969/j.issn.1000-1093.2013.10.013

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The traditional strapdown inertial navigation algorithm is to calculate the ground velocity based on integral of specific force transformation, which is solved using first-order approximation and second-order truncation. The influence of approximate integration errors on navigation precision cannot be ignored. In order to eliminate this influence, an improved strapdown inertial navigation algorithm with high precision is presented by using split integration scheme in the inertial reference frame. An analytical solution of the integrated transformed specific force increment is obtained for the thrust velocity defined by integral of specific force in the inertial frame, and a compensation scheme based on modified velocity increment is proposed for sculling error by analyzing its cause, an exact solution of the thrust velocity which can completely offset the dynamic errors, including coning error, rotation error and sculling error, is obtained. Both coning and sculling errors may be computed directly using the traditional optimization algorithms. A complete strapdown inertial navigation algorithm with high precision is developed by extending the thrust velocity update ideas into integration of the gravitational acceleration and position update. The significant advantages of the algorithm in the overall performance are demonstrated by the simulation test results under complex dynamic environment.

Effects of Relative Density of Magnesium Alloy Foams on Their Dynamic Mechanical Properties

YANG Dong-li, XU Zheng-guo, YANG Jie, WANG Lin, YANG Yuan-sheng

2013, 34(10):  1286-1290.  doi:10.3969/j.issn.1000-1093.2013.10.014

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The effects of relative density of magnesium alloy foams on their dynamic mechanical properties and energy absorption characteristics are investigated. Split Hopkinson pressure bar (SHPB) is used to evaluate the dynamic compressive behaviors of magnesium alloy foams with different densities. The experimental results show that, with the increase in relative density, the yield stress and platform stress increase significantly while the densification strain decreases. Based on the experimental results, the fitting equations of yield stress and relative density are obtained. The energy absorption properties of metal foams are characterized by energy absorption per unit volume, energy absorption efficiency and ideal energy absorption efficiency. The higher the relative density of magnesium alloy foams is within a certain range, the higher the energy absorption capacity per unit volume is. The energy absorption efficiency decreases slightly, but it is steady at about 0. 3, while the stress corresponding to the highest absorption efficiency increases. Magnesium foam is a kind of material with better protective performance, with the ideal energy absorbing efficiency reaching 0. 9.

Experimental Research on the Characteristics of Nonlocal Elastic Kernel Function Under Ultrasonic Vibration

ZHAO Bo, BIAN Ping-yan

2013, 34(10):  1291-1297.  doi:10.3969/j.issn.1000-1093.2013.10.015

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The variations in the constitutive characteristics of hard and brittle materials processed under ultrasonic vibration are researched based on the nonlocal theory in order to explore the high efficiency and ductility of ultrasonic vibration processing. The kernel function formula is deduced by analyzing the kernel parameters. The effects of internal and external characteristic variables, such as grain space, amplitude and frequency of ultrasonic vibration, on the nonlocal kernel function are systematically studied through numerical simulation. The theoretic results about the influence of ultrasonic vibration on the kernel function are verified in uniaxial tensile experiments. The research results show that, in terms of the effects of amplitudes and frequencies on the kernel function, there appears a shape of the downward parabola and there exists a critical value. In the experiment of tensile rupture, the practical influences of amplitudes and frequencies agree with the theoretic results deduced by numerical simulation. The fracture stress is minimal when the amplitude is 14. 94 μm and the frequency is 35 kHz. This study of the nonlocal elastic kernel function under ultrasonic vibration ensures an accurate understanding of the influences of ultrasonic vibration on the constitutive characteristics of materials, and provides the optimal parameters for ultrasonic vibration processing.

Design of PID Controller for Nonlinear System with Dead-zone and Saturation

PENG Fu-ming, FANG Bin

2013, 34(10):  1298-1303.  doi:10.3969/j.issn.1000-1093.2013.10.016

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Based on the describing function model of dead-zone and saturation and the method of determining the stabilizing region of PID controller for linear system, an approach is presented for the design of PID controller for a given nonlinear system with dead-zone and saturation. The new equivalent inverse Nyquist plots are given for the different sinusoidal input amplitudes of nonlinear component, and the parameters of PID controller are selected from the intersection sets of stabilizing controller parameter region for different sinusoidal input amplitudes. The controller can effectively mitigate the nonlinear effect. For unstable open-loop system, a prefilter is added on the reference input. The proposed approach can be used to stabilize the closed-loop system with nonlinearity. The simulation examples demonstrate the validity of the proposed approach.

Parametric Inversion of Material Based on Genetic Algorithm and Target Echo Characteristics

SUN Tie-lin, SUN Hui

2013, 34(10):  1304-1310.  doi:10.3969/j.issn.1000-1093.2013.10.017

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Dispersion equation of Lamb wave in underwater elastic plate coated with viscoelastic damping layers is derived, and the phase velocity and attenuation coefficient of Lamb wave propagating in the submerged composite plate at different frequency-thickness products are obtained under the condition of certain elastic modulus. The phase velocities and attenuation coefficients of the first two Lamb wave modes propagating in the composite plate at certain frequency-thickness product are measured by the echo measurement experiment of submerged elastic plate coated with viscoelastic damping layers, the elastic modulus of viscoelastic material is then inversed by substituting the experimental results into the dispersion equation. The results show that the phase velocity and attenuation coefficient of composite plate, and the inversed elastic modulus of viscoelastic material coincide with the theoretical values well, error in experiment less than four percent, it's proved to be feasible to inverse elastic modulus of viscoelastic material based on genetic algorithm and echo characteristic.

Research Notes

Adjustment and Control of a Certain Top-mounted Gun Based on a Novel Fractional Order Neural Sliding Mode Strategy

GAO Qiang, HOU Run-min, YANG Guo-lai,MAO Bin,HOU Yuan-long

2013, 34(10):  1311-1317.  doi:10.3969/j.issn.1000-1093.2013.10.018

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A novel fractional order neural sliding mode control (FNSMC) strategy is proposed for the nonlinearities of a gun control system (GCS) which is used to control the elevation of a certain topmounted gun. A fractional order PID type sliding surface is especially designed by introducing the fractional order calculus, and an equivalent control discipline with fractional order dynamics is induced. The saturation function is employed as switch function. To achieve the best control performances, a dynamic adjustment approach of the switch gain is introduced based on RBF neural network. The dynamic and static characteristics of the fractional order sliding mode control (FSMC) system are analyzed by numerical simulation, demonstrating that FSMC can reach up to the steady state more smoothly, which significantly suppresses the chatter effects and enhances the response rate of the control system. Finally, a series of experiments on a semi-physics simulation platform are conducted to investigate the performances of control system. The results show that the proposed FNSMC is of more excellence than the conventional integer order neural SMC(CNSMC). The FNSMC-based control system is of better tracking accuracy as well as high robustness, and the fast, smooth and accurate adjustments of the gun can be achieved.

Research on the Associated-tube Type Firing Mechanism for Pneumatic Fire-extinguishing Cannon

LIU Shao-gang, LIU Gang, ZHAO Dan, GUO Yun-long

2013, 34(10):  1318-1323.  doi:10.3969/j.issn.1000-1093.2013.10.019

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A quick pressing firing mechanism of the pneumatic fire-extinguishing cannon is studied,in which an associated tube is used for servo launch, solving the problem of that the launch gas pressure in the bore is required transiently to achieve the pressure in the gas chamber while launching. A dynamic model of firing process and a parameter model of gas in the bore are established, and a motion equation of projectile during firing is given. The variation characteristics of gas parameters in the bore are obtained by the simulation analysis of firing process in MATLAB environment. The effect of different firing angles on the firing characteristics is studied, and the optimal firing angle is obtained. The impact process of the firing mechanism is verified by using the software. The result shows that the firing mechanism with associated tube can be used effectively to solve the problem of high-pressure gas reaching the total launching pressure in the chamber transiently.

Temporary Cavity Model of Spherical Fragments Penetrating Ballistic Gelatin

MO Gen-lin, WU Zhi-lin, LIU Kun

2013, 34(10):  1324-1328.  doi:10.3969/j.issn.1000-1093.2013.10.020

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Ballistic gelatin is used as a stimulant for human tissue in the experimental study of temporary cavity which is an important factor of ballistic injury. To study the motion of temporary cavities, the steel spheres with diameters of 3 mm, 4 mm and 4. 8 mm are fired into the gelatin blocks at 650 ~1 000 m/ s in the experiments. The movement of temporary cavity is recorded by a high speed camera. The sine motion of the cavity wall is deducted based on the displacement field assumption and the elastic deformation assumption of gelatin. The empirical relations between amplitude and energy, and frequency and energy are established using the experimental data while a penetration model of spherical fragments in gelatin is built. The model is used to predict the temporary cavity for a 5. 2 mm tungsten sphere penetrating into gelatin at 800 m/ s. The predicted results are in good agreement with the experimental data.

A Method for Measuring the After-effect Duration and Operating Range of Projectiles

WANG Bao-yuan, DONG Wen-xiang, SHAO Xiao-jun, ZHANG Peng-fei, GUO Min, GAO Xiao-ke

2013, 34(10):  1329-1333.  doi:10.3969/j.issn.1000-1093.2013.10.021

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The research on the characteristics of artillery projectiles within the after-effect period is of great importance to the artillery engineering practice. At present, there is not a mature and practical method for the measurement of two important parameters, such as after-effect duration and operating range. A measuring method is proposed to measure the after-effect duration and operating range of artillery projectiles. In the method, a high speed digital camera technology and an image processing software are used to obtain the projectile position coordinates and time when the band leaves the muzzle and the projectile base leaves the shock wave. The difference between the two position coordinates is the operating range of projectile in the after-effect period, and the difference between the times when the band leaves the muzzle and the projectile base leaves the shock wave is the duration of after-effect period. The method was used successfully to measure the after-effect duration and operating range of projectile for a small caliber artillery in a range test.

A Method of Controlling an Optical-electronic Turret by Fusion of PI Controller and Kalman Filter

MIN Chao-bo, ZHANG Jun-ju, CHANG Ben-kang, LIU Lei, SUN Bin

2013, 34(10):  1334-1340.  doi:10.3969/j.issn.1000-1093.2013.10.022

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Since the image stabilization and target tracking of a optical-electronic turret require precise and effective position control, a control method of optical-electronic turret, including the precise position control of DC motor using the fusion of PI controller and Kalman filter and the predicted parameter self-adaption for PI control, is proposed. This method replaces a differentiation element which is in the PID controller with Kalman filter in order to simplify the parameters tuning of the PID controller,while the contorl performance is unchanged. And the predicted self-adaption for PI controller is achieved using the inverse model of DC motor and Kalman prediction. The experimental result shows that, compared with the common PID controller, the proposed method has better dynamic property, and can improve the control performance of shipborne optical-electronic turret.

Research on Extrapolation Method for Transient Surface Temperature Sensor

HAO Xiao-jian, HAO Li-na, ZHOU Han-chang, JIANG San-ping, LI Yuan

2013, 34(10):  1341-1344.  doi:10.3969/j.issn.1000-1093.2013.10.023

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A new temperature extrapolation method, which is used to broaden the measurement range of a sapphire optical fiber blackbody cavity temperature sensor, is proposed. A transient heating black body cavity extrapolation model is set up by analyzing the thermal conductivity law of the blackbody cavity, and the method of separation of variables is used to solve the extrapolation model. The sensor can be used to measure the transient high surface temperature (3 005 ℃) by temperature extrapolation. Experimental verification of the extrapolation method is designed and completed. When a high power and high frequency modulated CO² laser pulse is used as exciting source to heat the sensor to 1 500℃, the measured time response of the sensor is on the order of 10_-2 s. The sensor and a high-speed infrared thermometer are simultaneously used to measure the variations in temperature of the coatings inside and outside the blackbody cavity by using CO² laser step pulse. The result shows that the extrapolation model is valid.