Modern Defense Technology

Active Protection System and Technology Analysis for Military Helicopter

SHI Zhi-fu

2021, 49(5): 1-6. doi:10.3969/j.issn.1009-086x.2021.05.001

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Active protection technology as an innovative and advanced technology which can increase the battlefield survival for military helicopter.However,our military helicopter especially transport and support helicopter are lack the active protection solution,and liable to be attacked withe great damage cost.In view of the above problems,firstly,active protection system and technology for military helicopter are proposed.Then,the active protection technologies and equipment of the military helicopters at home and abroad are analyzed.At last,the key technical problems for realizing the active protection system are analyzed in detail according to the operational application process.The research results can provide references for helicopter active protection system research and design in future.

Combat Computation of Multi-Point Source Decoy System Based on Markov Model

REN Yi-dong, JIN Jia-cai, LUO Jin-liang

2021, 49(5): 7-13. doi:10.3969/j.issn.1009-086x.2021.05.002

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A method based on Markov model is proposed to calculate the damage probability of anti-radiation weapons to multi-point source decoy system.By analyzing and deducing the calculation method of damage probability of anti-radiation weapons to single point source,meanwhile introducing Markov model and constructing Markov chain,the calculation method of damage probability of anti-radiation weapons to multi-point source decoy system is designed.Furthermore,according to the requirements of mission tasks,the force requirements of anti-radiation weapons can be calculated.The simulation results verify the feasibility of the algorithm.The results also show that the damage probability and force requirement of the anti-radiation weapons for multi-point source decoy system can be well calculated by the method.

Analysis of the Influence of the Casting Cover on the Attitude of the Rotating Cabin

LI Wei-zhou, SONG Xiao-dong, WANG Shuai

2021, 49(5): 14-25. doi:10.3969/j.issn.1009-086x.2021.05.003

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During the separation process of outer cover and spacecraft body,the interaction force will affect the motion state of the spacecraft body.In order to explore the influence of the elastic separation of the outer cover on the spacecraft body.Firstly,based on the theory of multibody dynamics,Euler parameters are used to describe the attitude of rigid body.Then the dynamics equations including constraints of the system are obtained with a method of Lagrange multipliers by considering the interaction during the separation of rigid body.Finally,for the established dynamic model,the generalized α algorithm is used to solve the equation by time integration,and the corresponding calculation results are given for different conditions.The results show that the subsequent rotation state of the separated cabin changes regularly under different initial conditions.

Applications of Artificial Intelligence on the Optical Earth Observation

YAO Bao-yin, MAO Lei, XIAO Ke, QU Hui

2021, 49(5): 26-31. doi:10.3969/j.issn.1009-086x.2021.05.004

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Regarded as one of the “game-changing” cutting-edge technologies by military powers,artificial intelligence(AI) has the potential to process data efficiently and provide battlefield situation information quickly for earth observation.Firstly,the developing state of AI and its optical application on earth observation are briefly analyzed.Then,the application of AI on space-based and air-based optical earth observation is studied from several aspects,such as information collecting and information processing.Finally,the trends of AI applications on the optical earth observation are summarized.The research results can be the reference for AI application on the optical earth observation in China.

Design of Longitudinal Autopilot of UAV Based on Robust H_∞ Control

LI Yong, LI Shu-hao, DANG Li

2021, 49(5): 32-44. doi:10.3969/j.issn.1009-086x.2021.05.005

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In view of the expensive and time-consuming shortcomings of traditional gain scheduling technology in many UAV applications,through the six-degree-of-freedom nonlinear model of a fixed-wing UAV,under the condition of known the aerodynamic coefficient,aircraft moment of inertia and thrust coefficient,the linear parameter varying (LPV) aircraft model is derived from the six-degree-of-freedom nonlinear model by using Jacobian linearization method.The tensor-product (TP) model transformation method is used to transform the longitudinal nonlinear parameter-dependent LPV model of UAV into TP convex polyhedron model.The robust H_∞ controller design method of gain scheduling output feedback is applied to the TP convex polyhedron model,and the robust gain predictive autopilot flight control system of conventional fixed-wing UAV is designed.A full six-degree-of-freedom aircraft simulation test of the control system is carried out in MATLAB SIMULINK environment.The results show that the closed-loop control system has good command followed,interference suppression ability,good stability and robustness in the given flight envelope,which verifies the effectiveness of the proposed flight control system.

Formation Control of Multiple UAVs and Distributed Game Problem

MA Te, ZHENG Zhi-yuan, ZHAO Jun-hu

2021, 49(5): 45-50. doi:10.3969/j.issn.1009-086x.2021.05.006

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The formation of UAVs is studied by introducing game theory into distributed control,and a game-based distributed algorithm is developed.The algorithm combines the gradient descent and consensus to convert formation of UAVs into a problem of distributed game.The consensus technique is adopted to guarantee the estimation of the positions of all UAVs,and gradient descent is for the Nash equipment.By the proposed algorithm,UAVs can complete any formation even each UAV only have the neighbor UAV's information not all UAVs'.The simulation result verifies the effectiveness of the proposed algorithm.

Identity Recognition Method of Cluster Targets for Heterogeneous Sensors

ZHANG Xiao-li, XUE Shu-bo, DU Guang-yang, ZHANG Wen-hao

2021, 49(5): 51-55. doi:10.3969/j.issn.1009-086x.2021.05.007

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The identity recognition of orbital cluster targets is the premise of fusing the detection information of each sensor.Normally,the detection information of cluster targets comes from radar,infrared and other heterogeneous sensors.Aiming at the problem of identity recognition of heterogeneous sensors in the case of target mismatch is analyzed,and the motion characteristics of the orbital target in the 2D angle plane of the infrared sensor,and proposes a method of multi frame identity recognition for heterogeneous sensors based on Hough transform is proposed.The simulation results show that the matching accuracy of heterogeneous sensor in target mismatch is improved effectively.

Hypersonic Target Detection and Correlation Algorithm under the Condition of Large Time-Space Difference

BO Jun-tian, WANG Guo-hong, YU Hong-bo, ZHANG Jing-yan

2021, 49(5): 56-64. doi:10.3969/j.issn.1009-086x.2021.05.008

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Aiming at the problem that the trajectory of hypersonic targets in near space is interrupted due to the plasma sheath,a target trajectory detection and correlation algorithm under the condition of large time-space difference is proposed in the three-dimensional space.Multiple measurement points are transformed into the radial distance-time plane through Hough transform for non-coherent accumulation,and a low threshold is set to extract sub-tracks.According to the multi-information fusion of the time,speed,and azimuth between the sub-tracks,the sub-tracks belonging to the same real track are associated and the final track is output.The simulation results show that the algorithm has the ability of detection and correlation for multiple hypersonic targets interrupted track,which is of certain engineering practical significance.

Evaluation of Equipment Repair Effectiveness Based on Uncertainty Quantification Method and Cloud Model

LIU Bao-jun, LI Cheng, QING Hua, LI Chuang, YONG Xiao-ju

2021, 49(5): 65-70. doi:10.3969/j.issn.1009-086x.2021.05.009

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The effectiveness evaluation of emergency repair on equipment plays an important role in repair force construction and repair decision-making.Aiming at the uncertainty and randomness of qualitative index quantification,based on the uncertainty quantification method and cloud model,an effectiveness evaluation model of emergency repair on equipment is proposed.The feasibility of the model is verified through an example.Based on the evaluation results,the advantages and disadvantages of the repair capacity building are analyzed,and the methods to strengthen the emergency repair efficiency are presented. The evaluation model provides method basis and technical support for comprehensively improving the building capacity of the emergency repair.

Research on Construction Method of Ground-based EW Equipment Damage Structure Modules

LIU Fei, SU Zhou, JIANG Si-yu, CAI Zhi-cheng

2021, 49(5): 71-77. doi:10.3969/j.issn.1009-086x.2021.05.010

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In order to improve the efficiency and accuracy of localization and analysis for ground-based EW equipment damage in wartime,the logical relationship of functional modules is established through the hierarchical analysis of equipment functional structure.And based on physical structure,the relationship is constructed between equipment damage structure modules and functional modules.Then under the normalized rule of equipment damage structure,the construction method of the equipment normalized damage structure modules and its mathematical description model is established.Finally,the construction of a ground-based EW equipment damage structure modules and the logical relationship link of the function units can provide a reference for equipment damage analysis and repair,which also prove the construction method feasible and valid.

Maintainability Evaluation Method of Radar Equipment Based on Improved Grey-AHP

ZHANG Xin-yu, HU Bing, ZHANG Yi-nan, BIAN Zhi-yun

2021, 49(5): 78-87. doi:10.3969/j.issn.1009-086x.2021.05.11

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In order to meet the needs of maintainability evaluation of radar equipment in the evaluation and finalization stages,the maintainability evaluation index system of radar equipment is constructed.An improved analytic hierarchy process (AHP) method is put forward to weight the maintainability evaluation index of radar equipment. The Grey-AHP model for radar equipment maintainability evaluation is established,and the maintainabilities of three different development schemes are sorted to verify the effectiveness and feasibility of this method.

Equipment Maintenance Scheduling Optimization Model Based on Cost Analysis

SONG Wei-xing, WU Jing-jing, DONG Zhi-peng, ZHANG Jun, ZHOU Kai

2021, 49(5): 88-94. doi:10.3969/j.issn.1009-086x.2021.05.012

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Aiming at the problems of large equipment maintenance support tasks,limited support resources,extensive maintenance scheduling organization,and low support benefits.An equipment maintenance cost model,accurately calculates the equipment maintenance cost is established by using the activity-based costing method to analyze the relationships between equipment maintenance resource input and benefits,and also a multi-objective equipment maintenance optimization model is established,which is with the goal of the largest number of repaired equipment and the lowest average maintenance cost.Aiming at the characteristics of multiple model parameters and complex calculations,an improved hybrid nested particle swarm algorithm is designed based on a comprehensive use of particle swarm algorithm and genetic algorithm.A maintenance organization is taken as an example to carry out simulation calculations to verify the model and algorithm.The model and algorithm provide a certain theoretical basis for equipment maintenance decision-making.

Brief Review of Compressed-Gas Ejection Application in Weapon System

ZHAO Fang, WANG Tai-jiang, CHEN Qin, REN Ze-bin

2021, 49(5): 95-103. doi:10.3969/j.issn.1009-086x.2021.05.013

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Compressed air ejection has the advantages of suitable for general use,fast ejection speed,no thermal protection,safety,reusable,environmental and low cost,which is widely used in aerospace,ships and war-ships,land-based weapon system,etc.A large number of literatures are classified and summarized,and the compressed air ejection application research fields are viewed briefly.The key technologies and development prospects of compressed air ejection in various application fields are analyzed briefly.It concluds that the development of an efficient and miniaturized compressed air ejection system is an inevitable trend in all fields,and the research results provide effective references for the application and research of compressed air ejection in future.

Simulation Analysis of Mission Planning for Low Slow Small Target Compound Interception

BIAN Wei-wei, LÜ Xin, LIU Chan, JIA Yan-xiang, QIU Xu-yang

2021, 49(5): 104-110. doi:10.3969/j.issn.1009-086x.2021.05.014

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In view of the fact that a single interception method can not meet the needs of low slow small target prevention and control under different scenarios and environmental constraints,combined with the effectiveness and constraints of interception equipment,a composite interception task planning method based on particle swarm optimization algorithm is proposed.In order to reduce the mapping space of mission planning and improve the iterative speed of the algorithm,the coding method based on Interception effectiveness feasible region is adopted.And in order to control the search process of the algorithm,the shrinking and expanding motion of the particle swarm is changed by the concentration allowed value to enhance the coverage area.Taking learning factor,population size and inertia weight as main parameters,the task planning method is simulated and analyzed.The simulation results show that the improved algorithm can match the general optimization ability and convergence speed,and has good time performance while obtaining feasible solutions.This method can provide a theoretical reference for improving the efficiency of compound interception mission planning.

Numerical Simulation of Dynamic Response Characteristic of Charge Structure under Two Types of Penetration Loads

ZHANG Li-jian, GUO Hong-wei, LÜ Yong-zhu, LI Bao-hua

2021, 49(5): 111-117. doi:10.3969/j.issn.1009-086x.2021.05.015

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To study the dynamic response characteristics of charge structure under two types of penetration loads,the models of warhead penetrating integral concrete target and multi-layer interval concrete target are constructed respectively.Using LS-DYNA software,the process of dynamic penetrating concrete target is simulated.The difference of impact load,the distribution of plastic deformation area in charge,and the change of the gap between charge tail and shell are compared and analyzed.The results show that the charge mainly bears the axial overload,plastic deformation occurs at the front section of charge for the integral concrete target.For the multi-layer interval concrete target,the lateral overload is greatly increased.The charge tail,the local side of the charge and the corner point between charge and shell become the area with large plastic deformation.Under the condition of penetration,there are repeated contact collision and separation between charge tail and shell.Compared with the integral target,the dynamic collision between charge and shell is more frequent,more intense and lasts longer in the penetration process of multi-layer interval target.

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