Table of Content

31 May 2019, Volume 40 Issue 5

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Contents

2019, 40(5):  0. 

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Paper

Experimental Study of the Expansion of Non-standard Metal Cylinders by Detonation

WANG Xinying， WANG Shushan， LU Xi

2019, 40(5):  897-903.  doi:10.3969/j.issn.1000-1093.2019.05.001

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The expansion fracture process and intrinsic physical mechanism of metal cylinder driven by detonation are researched for calculating the initial velocity of fragments. In the experiments, 50SiMnVB steel and 45 steel cylindrical shells with different thickness were driven by TNT explosive detonation. The image information of expansion and the history of velocity were obtained by using a high-speed framing camera and the arrayed photonic Doppler velocimetry. Experiments reveal that the oscillation of expansion velocity is due to shock wave loading, and the expansion velocities of metal cylindrical shells continue to increase after shell rupture. The experimental results show that, for the shells with the same density, the oscillation amplitudes and pulsation times of expansion velocities of the shells increase with the increase in thickness，and the rupture mode changes from pure shear to tension-shear mixing. Because of the different load coefficients caused by different thicknesses of shells, the rupture time of 45 steel shell is later than that of 50SiMnVB steel shell, and with the increase in shell thickness, the difference between rupture time and rupture radius is larger. However, due to the acceleration of detonation products after rupture, the final expansion states of the two steel shells with the same wall thickness are almost the same. Key

Research on Forecasting Methods of Braking Energy/force Distribution for High Speed Tracked Vehicles

ZHANG Shuyang， ZHANG Yunan， NING Keyan， YAN Nanming， FANG Qingfeng

2019, 40(5):  904-914.  doi:10.3969/j.issn.1000-1093.2019.05.002

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A series of models， including a dynamics model, a driving system model and a braking system model， were established to study a tracked vehicle, which are used to predict the energy/force distributions of the braking system in high speed tracked vehicle. An approach to define testing road using eight parameters such as line length, slope, radius, roil angle, pavement power spectral density, running resistance coefficient, maximum soil adhension coefficient, and maximum steering resistance coefficient, is proposed, and then the influences of these parameters on the speed of vehicle are investigated. A driving strategy to minimize the running time of vehicle is designed based on the optimal control theory, and a binary linear regression equation used to calculate the braking torque is derived statistically. The accuracy of the approach and the efficiency of the strategy are verified using the experimental and simulated results. A typical model is built based on the experimental data of 1 000 km distance field test, and is used to predict the energy/force distributions of braking system in the region of a whole distance of 6 000 km. Key

Research on Position Sensorless Control of Hub Motor in Full Speed Range

ZHAO Qijin, LIAO Zili, ZHANG Yunyin, CAI Lichun

2019, 40(5):  915-926.  doi:10.3969/j.issn.1000-1093.2019.05.003

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The compound position sensorless control technology of hub motor is studied, and the switching method of the speed transition interval is improved to increase the reliability of drive system in electric drive armored vehicle. A permanent magnet synchronous motor （PMSM）control system based on double closed loops of torque and current was built, for which the maximum torque per ampere （MTPA）control below the base speed and the flux-weakening control above the base speed are used. A simplified high frequency pulse injection method is used at low speed, and a model reference adaptive system （MRAS） is used at medium and high speeds to realize the rotor position identification in the full speed range. The variable weight weighted control switching method is adopted, and the working interval selection of the two algorithms is improved in the process of algorithm switching. The system hardware and software resources are greatly saved while assuring the identification accuracy. The simulated and experimental results show that the proposed sensorless algorithm can identify the speed and rotor position accurately in the full speed range, and the new switching method enables the motor to achieve smooth transition in the speed switch interval and ensures the reliable operation of motor. Key

Experimental Study of Air-assisted Spray Characteristics of Aviation Kerosene Piston Engine

GAO Hongli, ZHANG Fujun, WANG Sufei, WU Hao, ZHOU Lei, ZHAO Zhenfeng, LIU Bolan

2019, 40(5):  927-937.  doi:10.3969/j.issn.1000-1093.2019.05.004

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Based on the air-assisted spray characteristics of two-stroke aviation kerosene piston engine, the systemic experimental study was performed, and the effects of ambient pressure, temperature and control parameters，including fuel injection duration, interval among fuel and air, and air injection duration, on spray width, penetration, spatial diffusion area and Souter mean diameter were analyzed using a high-speed camera and a phase Doppler particle analyzer combining with image processing technology in order to obtain a desired gas mixture and ensure a good match between the spray characteristics and the time-varying environment of cylinder. The results show that the increased ambient pressure is not conducive to the spray spatial diffusion, while the atomization is worsen; and the increased ambient temperature is beneficial to the evaporation and breakup of fuel droplets in the case of constant control parameters; and the decreased or increased air injection duration facilitates the extension of spray along the direction of the nozzle, and promotes the expansion and breakup of droplets. The experimental results show that the air-assisted injection system has good adaptability. Key

Soft Computing-based Assessment Method of Contribution Rate of Small Arms and Equipment System

YAO Tianle, HU Qiwei, QI Ziyuan, WEN Liang, TAO Fenghe

2019, 40(5):  938-945.  doi:10.3969/j.issn.1000-1093.2019.05.005

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The assessment of contribution rate of weapon equipment system is of great significance to the system's combat capability construction, operational support, and actual combat training. A soft computing-based assessment method for the contribution rate of weapon equipment system is proposed for the high nonlinearity, uncertainty and ambiguity of weapon equipment system. The fuzzy clustering method based on genetic algorithm is used for the soft classification of the weapons in the small arms system, and a fuzzy neural network based on soft classification is constructed. The fuzzy mapping chain based on the task sub-capacity-system sub-capability-total system capacity is used to solve the contribution rate. The contribution rate in the middle makes full use of the fault tolerance and robustness of the neural network to adapt to the incompleteness of data and the subjectivity of expert's cognition. The proposed method is used to analyze the case of a small arms equipment system, the contribution rate of the lower-level indicators to the higher-level indicators in the system is assessed, and the feasibility of the method is verified. Key

Measurement and Simulation of Thermal Response Characteristics of Fuze in Slow Cook-off Test

HAN Yanhui, LOU Wenzhong, FENG Yue, ZHENG Fuquan

2019, 40(5):  946-953.  doi:10.3969/j.issn.1000-1093.2019.05.006

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A research method for the thermal response of detonating fuze in cook-off environment is proposed to reveal the thermal response characteristics of fuze for insensitive munition, and heat transfer path and law. The cook-off test and thermal finite element simulation are made for a radio fuze of projectile for 76 mm naval gun. In the cook-off test, the heating rate of 1.17 ℃/min and the ultimate temperature of 270 ℃ are given as thermal stimulus conditions in cook-off test, and a “module replacement” method based on the thermal impedance equivalence principle, i.e., replacing the “battery component” with “thermocouple measuring system”, is used. The original heat transfer path of fuze is not affected by adding an embedded temperature measuring system. Such embedded temperature measuring system with Teflon shell is capable of recording temperature data, and has the advantages of high reliability and multi-channel synchronous sensing. In addition, the heat transfer path,i.e., pressed screw-safe and arming device-lead explosive-booster explosive, of fuze in cook-off is confirmed by comparing the temperature differences among five components in the fuze. The increases in the thermal impedances of the pressed screw and the safe and arming device can greatly reduce the accidental ignition probabilities of lead explosive and booster explosive. Key

Research on the Ignition Performance of High Insensitive Semiconductor Bridge

ZHENG Zilong, ZHANG Wenchao, QIN Zhichun, WU Ganggang, YU Chunpei, WANG Jiaxin, CHEN Yajie, YE Jiahai, TIAN Guirong

2019, 40(5):  954-961.  doi:10.3969/j.issn.1000-1093.2019.05.007

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A negative temperature coefficient (NTC)-semiconductor bridge (SCB) was prepared to improve the safety of SCB explosive initiator by paralleling a NTC thermistor to SCB, which is able to meet the requirement of high insensitiveness in 1.5 A and maximum 2.0 A non-firing stimuli tests. The split ratios at 1.0 A and 1.5 A after paralleling NTC thermistor to SCB were analyzed. Capacitance discharge ignition test, constant current excitation test and ignition sensitivity test were made to study the ignition performances of SCB, NTC-SCB and NTC-SCB after 1.5 A, 2.25 W and 5 min safe current test. Results show that the split ratios of NTC thermistor are about 35% and 62%， and thermal equilibrium temperatures are about 112 ℃ and 170 ℃ in 1.0 A, 1.00 W and 5 min, and 1.5 A, 2.25 W and 5 min safe current test, respectively. The ignition time and critical ignition energy are not show significant changes at 33 μF/30 V, but significantly increase at 7.0 A due to slow energy input rate and NTC thermistor shunt. Furthermore, 99.9% firing current of NTC-SCB increases from 2.329 A to 3.709 A after paralleling NTC thermistor and further increases from 3.709 A to 4.285 A after 1.5 A, 2.25 W and 5 min safe current test, which can be applied to the devices with ignition current greater than 5.571 A. Key

Study of Cook-off of a Fuze and Its Equivalent Components

XUE Chaoyang， ZHI Xiaoqi， WANG Shuai， ZHOU Jie

2019, 40(5):  962-967.  doi:10.3969/j.issn.1000-1093.2019.05.008

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A simplified equivalent model is established to study the cook-off characteristics of detonation train of fuze. The cook-off test with a heating rate of 3.3 ℃/h was carried out for a fuze filled with FOX-7 lead and booster explosoves. Two equivalent schemes were designed for the same cook-off test of the equivalent components. On the basis of the experiment, a cook-off model of the equivalent components is established, and the ignition sequence of the detonation train is studied through numerical simulation. The heat transfer theory is used to analyze the ignition mechanism, and explain the ignition cause of booster explosive. The results show that the ignition occurs when the temperature at the bottom of the outer wall is 177.1 ℃. The responses of two equivalent components are the same as that of the full fuze. They are all deflagration reactions, and the fragmentation status is basically the same. The equivalent scheme is feasible. The ignition point is in the center of booster explosive, and the combustion of booster explosive causes the deflagration reaction of lead explosive. The lead explosive is generally ignited firstly during cook-off when the lead and booster explosives are the same. Key

Simulation Research of Interior Ballistics Based on Erosion Wear Characteristic of Full-bore

JIN Wenqi, NING Jingui, WANG Jian, DENG Bo

2019, 40(5):  968-977.  doi:10.3969/j.issn.1000-1093.2019.05.009

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In order to improve the simulation precision of artillery interior ballistics, on the base of the artillery erosion interior ballistics theory in Ref.\[1\], the kinetic equation of projectile and the basic equation of interior ballistics are set up by keeping the equations of the variable projectile starting pressure, and the geometric combustion law and burning rate law of gunpowder unchanged, and analyzing the full-bore erosion wear characteristics of artillery, such as variable bore sectional area, variable chamber volume and volume increment after body, and then an interior ballistics model based on the whole-bore erosion wear is established. The resolving method of interior ballistics is derived. The certain artillery test data are computed through simulation. The simulated results demonstrate that the error simulated and test velocities are less than 0.9%, which satisfies the requirement of 3% simulation error of artillery engineering practice. The proposed method is better than the artillery erosion interior ballistics theory in Ref.\[1\]. The result proves that the proposed interior ballistics model and resolving method have higher simulation precision, and could be used for the prodiction of artillery barrel life. Key

Cook-off Experimental and Numerical Simulation of RDX-based Aluminized Explosives

KOU Yongfeng， CHEN Lang， MA Xin， ZHAO Pin， LU Jianying， WU Junying

2019, 40(5):  978-989.  doi:10.3969/j.issn.1000-1093.2019.05.010

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The aluminum powders change the internal heat transfer mechanism of the aluminized explosive to affect the thermal reaction of the explosive during cook-off. The thermal reaction characteristics of the aluminized explosive was studied. The cook-off experiment of RDX/WAX (96/4) explosive was carried out using the method of multi-point temperature measuring, and the kinetic model parameters of RDX explosive were calibrated by comparing the experimental and calculated changing temperatures at different positions. The multi-point temperature measuring and bomb cook-off experiments of RDX/Al/binder (60/31/9) and TNT/RDX/Al (60/24/16) were performed to obtain the internal temperature and ignition time. A calculation model for the thermal reaction of aluminium explosives is established to calculate and analyze the thermal reaction characteristics of the explosives. In the simulation,the endothermic and heat conduction of aluminum powder for RDX/Al/binder, the phase transition and multi-step thermal decomposition reactions for TNT/RDX/Al, and the heat absorption of aluminum powder were considered, and a multi-component grid cell calculation method was used. The correctness of the calculated results was verified by comparing to the experimental results. The results show that the addition of aluminum powder accelerates the internal heat transfer rate of RDX/Al/binder (60/31/9), of which ignition time is shorten so that the thermal safety of explosive is lower, and has no significant effect on the heat transfer process of TNT/RDX/Al (60/24/16). Key

Simulation of Slow Cook-off for Modular Charges at Different Heating Rates

LIU Jing， YU Yonggang

2019, 40(5):  990-995.  doi:10.3969/j.issn.1000-1093.2019.05.011

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The slow cook-off characteristics of modular charge at different heating rates are investigated for analyzing the thermal stability of modular charge under external stimulus. A slow cook-off model for the modular charge was established, and the numerical simulation calculations at the heating rates of 1.8 K/h, 3.6 K/h and 7.2 K/h were made. The results show that the ignition area occurs inside the single base powder near the central flash tube when the heating rate is low（1.8 K/h and 3.6 K/h ）during slow cook-off. When the heating rate is high（7.2 K/h）, the ignition area is no longer near the single base powder near the central flash tube. The heating rate has a great effect on the ignition time and the ignition position. As the heating rate increases, the ignition time is shorted, and the ignition area moves toward the center of single base powder. The burning response area changes from a central annular area to two annular areas that are symmetric about the center. The change of heating rate has limited impact on the ignition temperature. Key

UAV Swarm Formation Reconfiguration Control with Switching Interaction Topologies

LIU Liu, LIANG Xiaolong, ZHANG Jiaqiang, HE Lülong, HOU Yueqi

2019, 40(5):  996-1002.  doi:10.3969/j.issn.1000-1093.2019.05.012

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Unmanned aerial vehicle (UAV) swarm formation reconfiguration control with switching interaction topologies is investigated. The UAV swarm formation reconfiguration control law is designed based on the consensus theory. In order to make the UAV swarm form a specified formation configuration, the formation reference vector is introduced. The necessary and sufficient conditions for UAV swarm with switching interaction topologies achieving a predefined formation configuration are proposed. Under the condition that the interaction topologies are connected, the UAV swarm system is proved to be asymptotically stable based on the Lyapunov theory, and an approach to design the parameter matrix in the control protocol is proposed based on the algebraic Riccati equation. Numerically simulated results illustrate the efficiency of proposed control protocol. Key

Research on Testing Method of Explosion Pressure in Cabin

WANG Chuanhao, WANG Shushan, ZHANG Jingxiao, WEI Jifeng

2019, 40(5):  1003-1010.  doi:10.3969/j.issn.1000-1093.2019.05.013

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A method of testing the first reflected shock wave and the quasi-static pressure is proposed for the explosion test of the charge in a closed or quasi-sealed cabin. The frequency and amplitude characteristics of the first reflected shock wave and the quasi-static pressure formed by the in-chamber charge explosion are analyzed, and the necessity and rationality of using the different frequency response sensors to measure are illustrated. A sensor selection method is presented for using a high frequency piezoelectric sensor to measure the first reflected shock wave and a low frequency piezoelectric sensor to measure the quasi-static pressure. A special process tooling design and a sensor placement method, of which nylon sleeve tooling plays the role of insulatng and attenuating the stress wave, are presented. The design of the inner chamber pressure transmission tube can effectively eliminate the high-frequency signal generated by explosion and the interference of the optical and thermal signals on the piezoresistance sensor, thereby ensuring the test accuracy. A charge explosion experiment was conducted in the simulated cabin, and the test data is in good agreement with the calculated results of the classical formula. The research results show that the parallel test method for explosion-induced pressure load and the process tooling design is reasonable and feasible. It is recommended that the test sampling rate of the first reflected shock wave is in the order of MHz and the sampling rate of quasi-static pressure test is in the order of KHz under the premise of reasonable estimation of amplitude range of a signal to be tested. The effect of interference signal on the test is prevented using nylon sleeve tooling and an interference fit installation method. Key

Design and Implementation of Adaptive Polling Access Control Protocol Based on FPGA Tactical Data Link

DING Hongwei, LI Chao, LI Longjun, LIU Qianlin, BAO Liyong, YANG Zhijun

2019, 40(5):  1011-1019.  doi:10.3969/j.issn.1000-1093.2019.05.014

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In the tactical data link system, the tactical unit may be destroyed at any time to cause the dynamic changes in the network topology, resulting in reduced system service efficiency. In order to solve this problem, an adaptive polling access control protocol (APACP) is proposed based on the idea of dynamically adjusting the polling order. The system is modeled by the probability generating function method and the embedded Markov chain theory to obtain the analytical solution of average queue length and average polling period of system. Then the MATLAB and field programmable gate array (FPGA) are used to verify the protocol in simulation. The simulated results show that the APACP protocol can automatically adjust the polling order according to the dynamic changes of the tactical data link network topology, which significantly reduces the average queue length and average polling period of system, and overcome the empty polling of traditional polling access control protocol, thus saving the service time, improving the service efficiency and improving the system performance. Key

Research on On-axis Tracking Technology Based on Iterative UFIR Filter

YU Xiao， KE Fang, YUAN Jia, GAO Xingang

2019, 40(5):  1020-1029.  doi:10.3969/j.issn.1000-1093.2019.05.015

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An improved on-axis tracking scheme is proposed to effectively improve the tracking accuracy of photoelectric tracking system. The iterative unbiased finite impulse response (UFIR) filter algorithm is used to replace the traditional Kalman filter (KF) algorithm for state estimation and prediction. Because the iterative UFIR algorithm does not rely on the noise prior statistical information, it can overcome the shortcomings of the traditional KF algorithm and maintain the ideal prediction accuracy when the noise statistics are unknown, which makes the improved system also achieve the high tracking accuracy in actual operating condition. Two simulations were carried out，in which the KF was compared with the iterative UFIR filter， and two on-axis tracking systems which use above two algorithms were compared. Simulated results verify the correctness of the theoretical analysis, and show that the proposed scheme based on the iterative UFIR filter is more robust than the traditional KF-based scheme and has greater application potential in actual engineering where noise statistical information can't be accurately obtained in advance. Key

Correction of Static Pointing Error of a Novel Optical Testing Target

ZHANG Shaojun, XUE Xiangyao, GAO Yunguo, WANG Guang

2019, 40(5):  1030-1037.  doi:10.3969/j.issn.1000-1093.2019.05.016

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The error sources that cause the pointing error are briefly analyzed to check whether the spatial static pointing error of a newly developed optical testing target satisfies the design index of 5′, and a pointing error model of target mechanism is established by the homogeneous coordinate transformation method. The azimuth and elevation errors of target are calibrated using Leica total station with high precision, and the pointing error of target is further synthesized. The calibrated results reveal that the maximum spatial static pointing error, θ_max, is 275″, the mean value, θ, is 165.9″, and the square root, σ_θ, is 71.5″. In order to further improve the pointing accuracy of target, the least square method is used to fit the coefficients in the error model based on the calibrated data samples, and the calculated error models are used as the correction models of azimuth and elevation errors. When the pointing errors are corrected by using the proposed models, the average pointing error values of target mechanism at calibration points and the specific orbit are 21.1″ and 20.9″, respectively, and the root mean square are 10.6″ and 7.2″, respectively, which indicates that the static pointing error of the new target is greatly improved after error correction. Key

Research on the Underwater Target Motion Analysis Based on Acoustic Field Interference Feature Match

XU Guojun, ZHANG Lin, HAN Mei, FAN Peiqin

2019, 40(5):  1038-1049.  doi:10.3969/j.issn.1000-1093.2019.05.017

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A method of target motion parameters estimation based on the feature matching analysis of range-frequency spectrum interference fringes of target radiated noise is studied for the underwater target motion analysis. The feature quantity of target distance and the target azimuth under the current hypothesis are obtained using the calculation method of the target motion elements of two azimuths and two distances by taking the target initial and instantaneous distances as the cyclic observation factors. The matching cost factor of distance feature is constructed based on the target distance feature information calculated by time-frequency spectrum interference structure of target radiated noise, and the spatial visualization of target motion elements solution is realized. The simulated and experimental results show that the high accuracy information of initial distance, course and velocity of target can be clearly estimated in the spatial distribution map of target motion elements solution. The method can significantly improve the estimated speed and accuracy of the target motion elements. Key

Research on Underwater Acoustic Detection Algorithm of Aerial Targets Based on Harmonic Set Detection

MU Sen， LI Jinghua， ZHANG Heng， CHEN Guo

2019, 40(5):  1050-1057.  doi:10.3969/j.issn.1000-1093.2019.05.018

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The line spectrum in noise spectrum has obvious harmonic relation when a propeller-driven aircraft flies over the water surface at a certain height. With the cross-border propagation of noise from air to water and the change of underwater propagation environment, the harmonic relation tends to weaken. To solve this problem, an underwater acoustic detection algorithm based on the combination of harmonic set detection and strongest line detection is proposed, and the detection threshold is adaptively adjusted by using the threshold adjustment factor α, which improves the target detection performance under the condition of the low signal-to-noise ratio at a long distance and can effectively detect the propeller-driven aircrafts in underwater environment. The detection results of the measured signals received by the single hydrophone in water show that the detection distance can reach 2.48 km for a propeller-driven aircraft with a cruise speed of 36 m/s. Key

AUV Underwater Docking Collision Analysis and Guidance Structure Optimization Based on ADAMS Simulation

GUO Jingqian， ZHENG Rong， L Houquan

2019, 40(5):  1058-1067.  doi:10.3969/j.issn.1000-1093.2019.05.019

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The guiding performance of a self-developed underwater docking device is analyzed based on the docking test of autonomous underwater vehicle (AUV) in Qiandao Lake. An AUV docking collision model is established using the software ADAMS based on the hydrodynamic characteristics of AUV and contact impact parameters. The effectiveness of the proposed model is verified by comparing the attitudes and velocities of AUV in the test and simulated results. The guiding capabilities of convex, conical and concave guiding covers are discussed in terms of the offset distance and included angle of AUV docking. The generatrix curvature of guiding cover was optimized to design an improved S-shaped guiding cover by analyzing the simulated results. It is found that, under the same conditions of AUV docking attitude, the maximum AUV docking offset distance adjusted by the improved S-shaped guiding cover is 100 cm, which is 20 cm longer than that adjusted by convex guiding cover, and the maximum AUV docking angle adjusted by the improved S-shaped guiding cover is 22°, which is 1° lower than that adjusted by convex guiding cover. But the impact force generated by S-shaped guiding cover and the AUV docking time both are decreased, and the effect of adjusting AUV movement trend is obviously improved. The guiding performances of the improved S-shaped cover and the convex guiding cover were validated through the AUV docking tests. The test results show that the guiding performance of the improved S-shaped guiding cover is dramatically improved. Key

Analysis of Micromechanical Characteristics of Softness Consolidation Abrasives

JI Shiming， QIU Wenbin， ZENG Xi， XI Fengfei， QIU Lei， ZHENG Qianqian， SHI Meng

2019, 40(5):  1068-1076.  doi:10.3969/j.issn.1000-1093.2019.05.020

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A model of microscopic contact mechanics inside abrasives group is established to analyze the force chain transfer process. The Li-Dafalias elastoplastic dilatant constitutive model is used to reflect the relationship between micro-force and displacement within the abrasives group. The evolution of force chain network of abrasives group with different porosities and the pressure distribution on workpiece surface were simulated using the three-dimensional particle flow code (PFC3D) software. The simulated results show that, when the porosity exceeds 44%, the internal force chain transmission path of abrasives group disappears; the surface pressure of workpiece exhibits a periodic distribution, and the pressure amplitude decreases with the increase in porosity. A test platform was set up, and the influence laws of porosity and abrasive mesh on the surface roughness of workpiece can be concluded after a series of polishing experiments by pneumatic grinding wheels with softness consolidation abrasives. The experimental results show that the contour arithmetic mean deviation of workpiece surface roughness is small and decreases from 313.744 nm to 67.11 nm when the abrasive mesh is 800 and the porosity is 24%. Key

A Measuring System for Inner Diameter of Small-caliber and Long Gun Bore Based on Frequency Domain Interferometry

MA Heli, TAO Tianjiong, LIU Shenggang, WANG Xiang, WENG Jidong

2019, 40(5):  1077-1082.  doi:10.3969/j.issn.1000-1093.2019.05.021

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The machining quality of two-stage light gas gun bore has asignificant effect on the accuracy of experimental data of shock loading in dynamic high pressure physics research. An inner diameter measuring system based on all-fiber frequency domain interferometry ranging technology is demonstrated，which is used to acquire the accurate inner diameter of bore with small caliber and large length-diameter ratio. The micro fiber-optic probes are used as ranging sensors to precisely measure the coordinates of measuring points in the bore. The inner diameter is calculated by using the elliptic equation to fit the coordinates. The measured result of 28 mm bore with a length of 7 400 mm indicates that the most deviation is 0.014 mm compared to the measured results of three-point inside micrometer. Key

Allocation Optimization of Carrying Spare Parts for Combined Arms Unit Based on Random Common Cause Failure in Wartime

WANG Qiang, JIA Xisheng, CHENG Zhonghua, RAN Qiaoran, SUN Zheng

2019, 40(5):  1083-1092.  doi:10.3969/j.issn.1000-1093.2019.05.022

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The common cause failure events usually happen in the weapon and equipment for implementing the combat mission. The analysis of common cause failure events is of practical significance to the precise equipment support. A kind of random common cause failure has not been considered in the optimization model of carrying spare parts allocation for the combined arms unit implementing the task. An optimization method for spare parts allocation under random common cause failure is proposed. A spare parts demand model with the condition of equipment fault correlation is established, and an optimal model for carrying spare parts allocation under multiple constraints is developed. The Lagrange multiplier is introduced, and the optimal allocation scheme is obtained using the marginal effect method. A real example is used to verify the validity of the proposed model. The results show that the proposed model can be used to obtain the optimal allocation of multi-constraint spare parts under the condition of the random common cause failure. Key

Gear Performance Degradation Feature Extraction Based on Local Characteristic-scale Decomposition and Modified CompositeSpectrum Analysis

TONG Rui, KANG Jianshe, SUN Jian, YANG Wen, LI Baochen

2019, 40(5):  1093-1102.  doi:10.3969/j.issn.1000-1093.2019.05.023

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Since the vibration signal of gear is complicated and degradation features are hard to extract, a novel method based on local characteristic-scale decomposition (LCD) and composite spectrum (CS) entropy is proposed. The CS algorithm is modified, and Fourier transform is replaced by discrete cosine transform so as to reduce the information missing and improve the feature sensitivity. On this basis, LCD-CS algorithm is proposed for degradation feature extraction. Vibration signal is decomposed by using LCD method with high frequency harmonics. Bayesian information criterion and kurtosis time series cross correlation coefficients are used to screen the intrinsic scale components, so as to abandon the unnecessary components and extract the feature information effectively. In order to improve the degradation measurability of features, the selected ISC components are fused by using the modified CS algorithm, and the CS entropy is extracted as feature vector. The proposed method is applied to the gear run-to-failure degradation experiment, and the feature extraction and degenerative status recognition of the measured signals are carried out. The results show that the modified composite spectrum entropy has a good ability to characterize the gear degenerative state. Key

State Switching-based Distributed Multi-robot Formation Control

WEI Heng， L Qiang， LIU Yang， LIN Huican， LIANG Bing

2019, 40(5):  1103-1112.  doi:10.3969/j.issn.1000-1093.2019.05.024

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Traditional multi-mobile robot formation control algorithms, such as artificial potential field method, virtual structure method, leader-follower method and behavior-based method, have good effects in a specific part of formation control, and have not effectively solve a series of complete movement of formation, marching, transformation and obstacle avoidance. For the advantages and disadvantages of the algorithms mentioned above, the switching system is applied, and a distributed multi-robot formation control algorithm based on state switching is proposed. A state-switching trigger mechanism based on complex information is designed. The switching mechanism is triggered by the robot's own state and the surrounding environment, and one or more algorithms of formation control are reasonably selected. A formation feedback mechanism based on ultra-wideband (UWB) rangefinding is proposed, which makes use of the simple data structure of UWB to facilitate the processing of the micro-mobile robot, and completes the keeping and feedback of formation in real time. A distributed state estimation algorithm is proposed to provide the running state of robot for the trigger mechanism. The proposed strategy is applied to the actual robot formation control by constructing a multi-mobile robot platform, and the effectiveness and stability of the algorithm are verified. Key

Multi-object Optimization Design of Hinge Point Location of a New Deployment Mechanism for Scissors-type Bridge

HAN Jun， ZHU Pengcheng， ZHANG Shuai， HONG Huangjie

2019, 40(5):  1113-1120.  doi:10.3969/j.issn.1000-1093.2019.05.025

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A new deployment mechanism of scissors-type mobile bridge is presented. For the intermittent hydraulic oil overflow in driving cylinder cavity of engineering prototype due to overload during initial deploying, an optimal method for improving the stress state of driving cylinder is proposed. The kinematics and statics models of deployment mechanism are established using Denavit-Hatenberg homogeneous transformation matrix. A multi-objective optimization model for designing the location of hinge point in deployment mechanism is constructed based on different characteristics of driving force and locking force of hydraulic cylinder. The key hinge point location of deployment mechanism was optimized for the engineering prototype, and the correctness of calculation model was proved by using ADAMS. The research result shows that the maximum pulling force of optimized hydraulic cylinder is reduced by 59.5 percent, and the force distribution of hydraulic cylinder is significantly improved; the proposed calculation model is correct, and the optimization method has quick convergence speed and steady performance. Key