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26 August 2022, Volume 43 Issue 8

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2022, 43(8):  0. 

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Contents

Contents

2022, 43(8):  0. 

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Paper

Research on GMM-HSMM-based Longitudinal Decision-making System for Two-side Independent Electric Unmanned TrackedPlatform

LIU Qingxiao, TANG Zeyue, ZHANG Chaopeng, LIU Hai'ou, CHEN Huiyan

2022, 43(8):  1733-1743.  doi:10.12382/bgxb.2021.0680

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Atpresent, theresearch on the kinematics- and dynamics-based longitudinal decision-making system of electric unmanned tracked vehicles are confronted with problems such as poor adaptability and difficulty to obtain accurate model parameters. Aiming at the driving scenarios of the unmanned tracked vehicle straight-linedriving and approaching obstacles, this study introduces the longitudinal decision-making mechanism for driversby analyzing the driving data and constructsa model usingthe combination of Gaussian Mixture Model (GMM) and Hidden Semi-Markov Model (HSMM) to simulate the longitudinal decision-making process of experienced drivers. In the GMM-HSMM system, the GMM is utilized to identify the driving intention as well as cluster and quantifythe driving behavior duringtheobstacle-approachingprocess;the HSMM is applied to model the decision transfer process and the duration of the same decision. This system is verified by a real platform under different road conditions. The experimental results indicate that the proposed driver model canwellsimulate the longitudinal decision-making mechanismfor drivers,where the acceleration is limited to 3.5 m/s², the deceleration is larger than -4.5 m/s², andthe average value of absolute acceleration at the decision boundary approaches 0.8 m/s². Meanwhile, the GMM-HSMM-basedsystem is shown to be able to adapt to different road conditions withoutrelying on accurate road parameters by retraining the decision durationdistribution.

An Environment-adaptive Method for Determining the Minimum Compression Ratio of Diesel Engines

LI Yikai, PENG Jing, SHI Zhongjie, TAN Lihong, LI Yaozong

2022, 43(8):  1744-1752.  doi:10.12382/bgxb.2021.0400

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An environmental-adaptive design method for the minimum compression ratio of diesel engines is proposed based on the thermodynamics theory and experiments to ensure that diesel engines can start smoothly in low temperature and plateau environments. In this paper, the critical ignition temperature of diesel spray is determined through optical testing, and a fitting relationship between the critical ignition temperature and ambient density is presented. Diesel engines are tested for the actual in-cylinder pressure during cold start using the motoring test method. A mathematical relationship between the minimum compression ratio and the environmental temperature and altitude is established based on optical diagnosis, motoring tests and the thermodynamic theory. Optical tests show that with the increase of ambient density, the critical ignition temperature of diesel spray drops rapidly, then slowly, before stabilizing at about 700 K. The actual in-cylinder pressure and temperature are lower than the theoretical values for adiabatic compression due to the high-level heat transfer and blow-by during cold starting. As the speed of the motoring test increases, the blow-by in the cylinder of the compression stroke decreases, resulting in an increase in pressure and temperature at the top dead center. The results of thermodynamic analysis show that, when the environmental temperature decreases from 273 K to 238 K at an altitude of 0 m, the minimum compression ratio of a diesel engine with intake preheating needs to be increased from 13.8 to 18.0. When the intake air temperature is 263 K and the altitude rises from 500 m to 4 400 m, the minimum compression ratio of a diesel engine should be increased from 12 to 17. The optimized minimum compression ratio will help improve the cold start performance under extreme conditions.

Vibration Characteristics and Improved Design of Intake-Cooling Pipes for Heavy Duty Vehicles

LIU Yuhang, LIU Xin, ZHANG Sheng, LI Hongbiao

2022, 43(8):  1753-1762.  doi:10.12382/bgxb.2021.0449

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The intake system of a heavy duty vehicle consists of intake-cooling iron pipes on both sides and an intercooler. After delivery to user, cracks are often found on the left cooling pipe, whereas the right pipe is in good condition. Vibration tests of the intake system are conducted to find out the reasons for the failure. In-situ and running vibration acceleration data are collected. Through data analysis, it is found that resonance occurs to the left intake pipe under in-situ condition or when the engine is operating at 1 700 r/min. The right intake pipe bears greater excitation acceleration than the left one. Both sides of the intake pipes share similar dominant frequencies between 0-200 Hz. According to the frequency response simulation of the left intake pipe, the resonance frequency occurs at 138 Hz and the maximum stress at the bottom of the pipe is 74.2 MPa. The structure of the left intake pipe is developed by comparing the left and right intake pipes’ parameters. Both simulation and vibration tests are conducted on the improved intake pipe. The results show that the improved pipe successfully avoids the main excitation frequency and the vibration conditions are also improved under different road conditions.

Optimal Sensor Deployment for Power Supply Vehicles under Hybrid Information-Entropy Constraints

JIANG Dongnian， LI Wei

2022, 43(8):  1763-1771.  doi:10.12382/bgxb.2021.0478

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An optimal sensor deployment method based on hybrid information entropy index is proposed to improve the fault diagnosis performance of power supply vehicles (PSVs). Low fault diagnosability of PSVs is one of the main causes of their high failure rate, and the unbalanced configuration of the measuring point sensors is the key to the difficulty of rapid and reliable detection of power vehicle faults. Thus, we can first obtain the posterior probability of sensor residual after fault using the Bayes theorem, and then calculate the Value of information (VOL) of the posterior probability for PSV fault diagnosis. Second, due to the possibility of redundancy between sensors, it is difficult for sensors to interpret the numbers and locations simultaneously. Therefore, the redundancy between sensors is further quantified by using the Transfer Entropy (TE) method, and the optimal sensor configuration problem is reduced to a multi-objective optimization problem of solving VOL and TE, which reveals the best sensor configuration. Simulation results show that the hybrid information entropy method has obvious advantages for clarifying and analyzing the maximum coverage space and the minimum configuration set of sensors in the process of fault diagnosis.

Reaction Evolution Behaviors of Pressed Plastic-Bonded Explosive (PBX) under Different Mechanical Confinement Conditions

YAO Kuiguang, WANG Shujuan, FAN Xing, NIE Shaoyun, WANG Xiang, DAI Xiaogan

2022, 43(8):  1772-1778.  doi:10.12382/bgxb.2021.0445

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An experimental study was conducted to investigate the effect of mechanical confinement on the reaction behavior and mechanism of explosives, in which different confined charges of HMX based pressed PBXs were ignited at the center of the bottom surface via non-shock initiation with a newly designed mechanically confined charge ignition experimental device. The reaction violence was characterized by the reaction pressure and confinement disc velocity, while overpressure and recovery fragments were also analyzed. The results showed that: under 2 MPa mechanical confinement, charge deflagration occurred, where the maximum pressure of PBX-1 and PBX-2 charges were about 200 MPa, and the expansion velocity of the confinement disc were about 70 m/s; under 50 MPa mechanical confinement, charge explosion occurred, where the pressure of PBX-1 and PBX-2 charges exceeded 1 GPa in hundreds or even tens of microseconds, and the expansion velocity of the confinement disc reached 500 m/s; the physical properties of PBXs may cause some differences in reaction evolution, but the influence of mechanical confinement is more obvious; the reaction pressure and confinement dics velocity differed by almost one order of magnitude under 2 MPa and 50 MPa mechanical confinement using the designed device.

Strategy of Knock Detection of Double-base Propellant/Coating Interface Debonding

DUAN Shixuan, LI Yanjun, CAO Yuyuan, ZHANG Xingcheng, SONG Fucheng, KE Yuhang

2022, 43(8):  1779-1791.  doi:10.12382/bgxb.2021.0573

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A series of strategies based on the principle of knock detection are proposed, and guidance is given to the detection process, to address the problems of low accuracy, poor efficiency, confusion, and disorder in the knock detection of the double-base propellant/coating interface debonding. Based on the basic characteristics of knock detection, two specific curved surfaces of the tested cylinder and ball head are meshed independently, and the possible accuracy and sensitivity problems in meshing are experimentally evaluated. A mathematical model of the detection efficiency of the double-based propellant/coating interface is constructed using Barlow's assessment approach as a starting point. The model quantifies the sequential detection time cost and periodic detection interval. And a box-plot based fluctuation range detection approach is proposed to visualize defect location and severity in a defect cloud map. The proposed method is of guiding significance for the knock detection test procedure and post-test treatment measures, according to the whole process flow and experiment analysis of cases.

Influence of Gas-particle Two-phase Flow on Ignition of the Solid Rocket Motor under Lateral Acceleration

GUAN Dian， GUO Yawen， LI Shipeng， TANG Jianing， WANG Ningfei

2022, 43(8):  1792-1807.  doi:10.12382/bgxb.2021.0321

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Due to the acceleration environment induced by the high-speed spinning of the solid rocket, the coupling relationships of flow, heat transfer and combustion are obviously different from those in the conventional ignition process, posing a potential threat to ignition reliability and projectile safety. To investigate the ignition characteristics solid rocket motor under acceleration, a new comprehensive ignition model considering the inertial acceleration field effect of the fluid and particle, particle collision heat-transfer enhancement of propellant, acceleration-induced combustion and erosion is developed . The dynamic gas-particle distribution law is obtained during ignition under lateral acceleration of the different directions and particle sizes. The influence of particle size and acceleration on pressure peak p_max, ignition delay time ξ₁, flame propagation time ξ₂ and flame filling time ξ₃ in the ignition process is analyzed. The results show that the gas-particle distribution is effectively changed by the acceleration-loads direction, which affects the heat transfer of the propellant and the shortening of the internal ballistics in the time domain. Under the same acceleration-loads condition, the smaller particle size, the shorter the ignition delay time ξ₁ and the flame propagation time ξ₂, while the effect on the flame filling time ξ₃ can be basically ignored. At the same particle size condition, the ignition delay time ξ is reduced by the increased acceleration-loads for large aspect ratio solid rocket.

Computational Model for the Critical Ricochet Angle of a Tungsten Alloy Long Rod Projectile Impacting a Thick-walled Cylinder

JIN Wen, MEN Jianbing, JIANG Jianwei, PENG Jiacheng, LI Mei

2022, 43(8):  1808-1815.  doi:10.12382/bgxb.2021.0439

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As new technologies such as electromagnetic orbit launch emerge, high-speed long rod projectiles play a prominent role in attacking thick-walled targets, such as short-range air defense anti-earth penetrating weapons. The key for rod ammunition to be effective is to achieve stable penetration without ricochet when hitting the target. To address the ricochet problem of tungsten alloy long rod projectiles impacting thick-walled cylindrical targets, a projectile-target contact model is developed by simplifying the target and analyzing variables. A finite element simulation model is established and verified based on LS-DYNA3D nonlinear dynamics software. Simulations are performed with an impact velocity ranging from 1 000 to 2 200 m/s and a hit-offset angle of 0°-40°. Then, a modified computational model based on Rosenberg is constructed by using fitted data. Compared with numerical simulation, verification results show that the model is suitable for determining the ricochet boundary of tungsten alloy long rod projectiles impacting thick-walled cylinder targets. The model is capable of predicting the critical ricochet angle when the projectile impacts the target.

Dynamic Compression-shear Study of Fluoropolymer-matrix Reactive Materials

GE Chao, QU Zhuojun, WANG Jin, HU Die, WANG Haifu

2022, 43(8):  1816-1822.  doi:10.12382/bgxb.2021.0482

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To characterize the mechanical properties of PTFE/Al (73.5 wt.%/26.5 wt.%) fluoropolymer-matrix reactive materials,quasi-static and dynamic compression tests at elevated strain rates and temperatures, as well as dynamic compression-shear tests based on hat-shaped specimens with predesigned shear bands of different widthsare conducted. Quasi-static (10^-3 s^-1) and dynamic compression tests at elevated strain rates (3×10³-7×10³ s^-1) and temperatures (20 ℃,100 ℃,150 ℃, 200 ℃) show that the PTFE/Al material is a typical elasto-plastic material with strain hardening, strain rate strengthening and thermal softening effects. Dynamic compression-shear tests based on hat-shaped specimens with predesigned shear bands of different widths(500 μm,300 μm,100 μm)show that the difference in shear band widths induceslocalized thermal and temperature rise and hasa prominent effect on the dynamic response of fluoropolymer-matrix reactive materials.

Mesoscale Mechanism of the Shock Reaction of Al/Ni Powder Composites

XIONG Wei, ZHANG Xianfeng, CHEN Haihua, LIU Chuang, TAN Mengting

2022, 43(8):  1823-1834.  doi:10.12382/bgxb.2021.0488

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Mesoscale simulation of the energy release behaviors of Al/Ni powder composites is conducted to clarify the mechanism of shock reaction. A mesoscale model is established based on the Scanning Electron Microscope image of the Al/Ni composite to reveal the microstructure. The dynamic behaviors of both Al and Ni particles are described using Mie-Grüneisen equation of state. Furthermore, a shock reaction model for the solid-phase reaction between multiple components is established based on the reaction diffusion model. The shock pressure, temperature distribution and propagation of shock waves are obtained to analyze the dynamic response of the Al/Ni powder compaction. On the other hand, the evolution of reactants and reaction products are obtained to analyze the mass diffusion process, evolution of the chemical reaction, and the Al/Ni powder composite on mesoscale. The results show that the Al and Ni particles deform violently after compression, causing high shock pressure and temperature in the Al/Ni powder composites. The material Ni is transported into Al particles due to the concentration gradient and shock-induced temperature rise. The chemical reaction in the Al/Ni powder composite will be initiated by a critical condition with the particle velocity at about 400 m/s. Once the particle velocity exceeds the critical value, the reaction will be intensified with the increase of particle velocity. The above results agree well with related experimental results. The reaction product is first produced at the Al-Ni interface and then grows perpendicularly to the interface, accompanied by the consumption of reactants. Therefore, the shock reaction is initiated at and developed from the Al-Ni interface. Furthermore, the shock reaction makes additional contribution to the shock pressure and temperature, especially near the Al-Ni interface. The shock velocity of shock waves in the Al/Ni powder compaction also exceeds the value without considering the reaction.

Aircraft Control Method Based on Attitude Feedback for Overload Tracking

JIANG Limin， LIU Hailiang， CHEN Shuxuan

2022, 43(8):  1835-1844.  doi:10.12382/bgxb.2021.0111

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For aircraft whose control forces and moments are provided by aerodynamic rudder, a method of the control system considering the maneuverability and attitude stability is proposed depending on the nonlinear mathematical model of the pitch and yaw channel. First, based on the equivalent conversion between the overload and attitude of aircraft, the accurate attitude angle command is obtained according to the overload command calculated by the guidance law. And then, using attitude feedback as the main control loop and overload compensation as the auxiliary, this control strategy enables the overload command to be tracked accurately. The six-degree-of-freedom simulation results demonstrate that the proposed method not only meets the requirements of overload tracking accuracy for guidance, but also achieves the purpose of robust stability control for aircraft attitude. This method is simple and reliable, and has been verified by engineering application.

Compact Catadioptric Bionic Compound Eye and Fast Image Mosaic Recognition Algorithm

CAO Zhaorui, HAO Yongping, LIU Wancheng, BAI Fan, SUN Haoyang, ZHANG Hui, LI Yuhai

2022, 43(8):  1845-1857.  doi:10.12382/bgxb.2021.0393

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To resolve the problems of high mass and high volume of image data generated by the multi-channel camera array in a bionic compound eye, a large FOV bionic compound eye imaging system and an image fast mosaic recognition algorithm based on multi-channel single detector is proposed. By using optical path refraction and normalization, multi view sub eye image plane coplanar and single photodetector partition imaging are realized. Based on the imaging characteristics of catadioptric eyes, an image mosaic algorithm based on the structural similarity at the feature map level is proposed. Fast reconstruction and target recognition of global images with a large field of view (FOV) in a compact space are realized by using a convolution neural network for target recognition. The proposed compound eye system has an effective optical FOV of 138°×75°, an optical dimension is 29.78 mm×19.74 mm×6.86 mm, and a global image mosaic speed is 0.011 s. The compact catadioptric compound eye has the advantages of small volume, large FOV, and low computational cost. It can provide wide area vision and fast image mosaic recognition capabilities for small unmanned equipment and low speed projectiles with limited load and computational power.

An Optimal Deployment Method of Heterogeneous Multi-static Radars for Linear Barrier Coverage

LI Haipeng， FENG Dazheng， CHEN Shaofeng

2022, 43(8):  1858-1867.  doi:10.12382/bgxb.2021.0406

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To construct a linear barrier coverage, in case of the locations of multistatic radar are constrained, an optimization method using heterogeneous multistatic radar is proposed. This method proves the composition properties of the optimal linear barrier coverage sequence by studying the relationship between heterogeneous and homogeneous multistatic radars. Then, the optimization model is established underlying these properties. Besides, the restriction of the deployment location is taken as the constraint condition of the model. Aiming at the non-convexity and non-analyticity of the objective function in the model, an optimization algorithm combining integer linear programming and enumeration method is exploited. The algorithm solves the optimization problem in layers and segments according to the situation of restricted deployment. Furthermore, it determines the optimal barrier coverage sequence based on the minimum deployment cost criterion. Simulation experiments show that the performance and cost of the radar transmitter play an essential role in determining the optimization results. This method can obtain optimized results under the constraint of the location of multistatic radar.

3D Range-gated Imaging Method Based on Parabolic Envelope Inversion

SUN Lei, JIN Dongdong, JI Chunheng, PEI Chonglei, AN Hongbo

2022, 43(8):  1868-1873.  doi:10.12382/bgxb.2021.0528

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3D range-gated imaging technology is of great significance in application fields such as 3D mapping, long-distance surveillance, navigation, and underwater target detection. The development of 3D range-gated super-resolution imaging technology and the frequently-used 3D inversion algorithms are introduced. On this basis, the 3D range-gated imaging method based on the parabolic envelope is studied. In terms of actual ranging accuracy, depth of field (DOF) of 3D imaging, real-time performance and the difficulty of system implementation, the proposed method is compared with the commonly used triangle and trapezoidal energy-related algorithms and verified by experiments. The results show that the the parabolic envelope-based 3D inversion algorithm reduces the system hardware index requirements, improves the actual ranging accuracy, and meets the demand for real-time large DOF 3D imaging, which demonstrates its good application prospects.

Control Strategy for Photoelectric Stabilized Platform Based on Sliding Mode Variable Structure Control

GUO Bo, KE Fang, YU Xiao, GAO Xinyang, SUN Aixian

2022, 43(8):  1874-1880.  doi:10.12382/bgxb.2021.0727

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The photoelectric tracking system is subject to disturbances in the moving process of carrier, which has a negative impact on the tracking performance of the system. Sliding mode control has good robustness and can beeasily implemented, so it can be considered in such systems. Using friction feedback and combining sliding mode control for velocity loop with PID control for tracking loop, a sliding mode variable structure control strategy applicable to photoelectric tracking system is proposed. It improves the stability and accuracy of the photoelectric stabilization platform, and at the same time, it has certain robustness, which enables the running system to have certain adaptability to the changing disturbances when the external environment changes. The sliding mode controller is designed for the two-dimensional servo turntable, and then simulated and compared with the available PID-based control scheme.The comparative test results show that under given disturbances, the stability error of velocity loop of the photoelectric stabilization platform based on the sliding mode control strategy is reduced from 72″/s (arc-seconds per second) to 12″/s, and the root mean square is reduced from 37.0″/s to 1.46″/s. The effect of the proposed sliding mode controller on improving the stability and accuracy of the photoelectric stabilization platform has been verified.

Acoustic Emission Parameters in the Damage Process of Steel Fiber Reinforced Concrete under Mixed Loading

SONG Shuizhou, REN Huilan, NING Jianguo

2022, 43(8):  1881-1891.  doi:10.12382/bgxb.2021.0468

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Using the acoustic emission (AE) technique, a series of Brazilian disk tests with a central notch (BDCN) under mixed loading are conducted to investigate the fracture mechanism of steel fiber reinforced concrete (SFRC). The evolution of the AE parameters during the fracture process is analyzed. The results indicate that the damage process consists of three stages based on the characteristics of the cumulative signal strength and load versus time relationships. The damage in the first stage is caused by the microcrack initiation, and then the coalescence and extension of microcracks. AE signals captured during the third stage are caused by the debonding and extension of steel fibers. By employing the machine learning algorithm and analyzing the AE parameters, the damage mechanism of SFRC is revealed. Using Gaussian mixture models, it is possible to classify damage sources as tensile cracks or shear cracks. Tensile cracks dominate the damage process, while shear cracks contribute to it. From the support vector machine, it is evident that the boundaries between tensile and shear cracks are not always straight lines passing through the origin.

Properties of Three-dimensional Photonic Crystals as Infrared Stealth Materials

LI Renbin， GUO Jiong， QIAO Yu， MENG Zihui

2022, 43(8):  1892-1901.  doi:10.12382/bgxb.2021.0816

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The development and application of infrared stealth materials have attracted strong attention in the world with the rapid development of infrared detection technology in recent years. Photonic crystals stand out because of the adjustable band gap. Using photonic crystals with band gap in the infrared band as surface coating material can effectively change the infrared radiation characteristics of the target and achieve infrared stealth effect. The physical theory and experimental verification are combined to study the preparation of opal-type photonic crystal infrared stealth materials based on the self-assembly technology of colloidal elements, which provides theoretical guidance and technical support for the development of new infrared stealth materials. According to the Bragg diffraction law, the diameter ranges of the colloidal photonic crystal element with the band gap in the detection bands (3-5 μm and 8-14 μm) of the infrared detector and the infrared night vision device are determined respectively. The 1- 2.21 μm colloidal polystyrene element with good monodispersity is synthesized by dispersion polymerization. Three commonly used colloidal element self-assembly approaches are studied: vertical self-assembly method, gravity sedimentation method and layer-by-layer self-assembly method. A constant-temperature water bath baking method is proposed. The experiments show that the opal-type photonic crystal prepared by this method has regular structure, and the infrared transmittance in the band gap range can be reduced from 80% to 25%. The infrared thermal imager test shows that the background material at 60 ℃ has good infrared stealth effect. The proposed method has the advantages of being applicable to multiple types of microspheres, short preparation period (only 3 h), simple preparation equipment and process, and high array regularity.

Design Scheme of Virtual Twin System for UAV Combat

JI Guang, HAO Jianguo, ZHANG Zhenwei

2022, 43(8):  1902-1912.  doi:10.12382/bgxb.2021.0408

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To deal with the low precision of the UAV model in the process of combat simulation, the difficulty of virtualreality interactive operation, and the weak combat experience of commanders, the design scheme of the combat simulation system is proposed based on virtual twin technology, which is used for synchronous operation of actual UAV combat and simulation/deduction, and outputting intelligent assisted decision-making according to the battlefield situation. On the basis of digital twin, the connotation of virtual twin technology is proposed. Combined with the advanced means of artificial intelligence, the framework of virtual twin system for UAV combat is designed. Finally, taking the combat process of individual combat quadrotor UAV as an example, the hardware and software architecture is designed, and the operation process is analyzed. The case study findings shows that the model under the virtual twin system runs more accurately, and can realize the virtual-reality synchronization, interactive operation, visual interface and intelligent decision-making real-time output, so that the commander's sense of participation is enhanced, and the combat command efficiency is improved.

TSO-GRU-Ada Maneuver Trajectory Prediction Based on Maneuver Unit Library

TANG Shangqin, WEI Zhenglei, XIE Lei, ZHOU Huan, ZHANG Zhuoran

2022, 43(8):  1913-1925.  doi:10.12382/bgxb.2021.0417

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Maneuver trajectory prediction is an important part of autonomous air combat. To deal with the problem of low accuracy and time-consuming prediction of Unmanned Combat Aerial Vehicle (UCAV) maneuver trajectory, a prediction model based on the gated recurrent neural network with adaptive boosting algorithm integrated with triangle optimization is proposed. Firstly, a three-degree-of-freedom model of the UCAV is established to solve the trajectory data source problem. Secondly, through the four trajectory characteristics, the trajectories are divided into three categories, namely, planar maneuver, spatial left-turning maneuver and spatial right-turning maneuver, and 21 basic maneuver units are constructed. Then the gated recurrent neural network is explained. To prvent the network gradient optimization from falling into the local optimum, the triangle search optimization algorithm is introduced to update the internal weights and biases of the network. At the same time, to improve the prediction accuracy, the adaptive boosting algorithm is used to build a strong predictor. The optimal parameters of the predictor are selected through experiments, and the predictions are made under different maneuver units. The prediction results have high accuracy and all of them can meet the time consumption requirements. Finally, to test the prediction performance for the maneuver trajectory, a trajectory is selected from the Air Combat Maneuvering Instrument, and compared with results from five different prediction models. The results show that the proposed method has the best prediction accuracy.

Adaptive Robust Path Following Controller for Quadrotor UAVs Based on Parameter Estimation

XIU Yang, DENG Hongbin, WEI Yiran, LI Dongfang

2022, 43(8):  1926-1938.  doi:10.12382/bgxb.2021.0444

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To improve the path following accuracy and flight robustness of quadrotor UAVs, an adaptive robust path following controller based on parameter estimation is proposed. The controller can adaptively estimate the gyroscopic factors and drag coefficients for the UAV model, compensate the system’s control input based on estimated values, and offset the negative impact of the external environment with an anti-interference capacity. The controller can effectively improve the path following and anti-interference performance of quadrotor UAVs. First, a nonlinear mechanical model of a quadrotor UAV is established. Second, the path following targets for UAVs are divided into attitude angle targets and moving position targets. Third, the backstepping sliding mode method and adaptive control method are used to design the control input equation and the estimation updating law of the UAV. Simultaneously, the asymptotic stability of the UAV attitude system and motion position system is verified by applying the Lyapunov method. Lastly, the effectiveness and superiority of the proposed controller are verified by simulation and experiments.

Finite-time Path-following Controller for UUV Based on PSO-NTSMC

YU Haomiao， LIU Chengwei， GUO Chen, JIA Zhaoyan

2022, 43(8):  1939-1946.  doi:10.12382/bgxb.2021.0491

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For the path-following problem of underactuated unmanned underwater vehicle (UUV), the path-following control strategy is proposed based on the particle swarm optimization and nonsingular terminal sliding mode control (PSO-NTSMC) method. Firstly, the linear path-following guidance law is developed by line of sight and Serret-Frenet frame. Then, the path-following controller is designed based on the nonsingular terminal sliding mode, which can stabilize the path-following errors. Furthermore, the PSO is introduced to optimize the controller parameters in order to obtain better control performance. Finally, the numerical simulation results show that the designed controller can accurately execute the horizontal straight path following in finite time, and can effectively overcome the influence of constant unknown current and model parameter perturbations.

Tracking and Aiming Adaptive Control for Unmanned Combat Ground Vehicle on the Move Based on Reinforcement LearningCompensation

WEI Lianzhen, GONG Jianwei, CHEN Huiyan, LI Zirui, GONG Cheng

2022, 43(8):  1947-1955.  doi:10.12382/bgxb.2021.0786

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To deal with the nonlinear interference caused by chassis movement and road surface undulations with the tracking and aiming of unmanned combat ground vehicles, a tracking and aiming adaptive control method for unmanned combat ground vehicles on the move based on reinforcement learning compensation is proposed. This method consists of a main controller and a compensation controller. The main controller uses the PID control algorithm combined with the current tracking error to obtain the main control quantity, and the compensation controller uses the Dueling DQN reinforcement learning network to process the current state of the combat vehicle as well as the road surface undulation information near the local planning path to obtain the compensation control quantity. Firstly, the integrated kinematics model of the unmanned combat ground vehicle is established. Then, the compensation control algorithm based on reinforcement learning is described. Finally, simulation and verification are performed in three-dimensional scenes based on the V-REP dynamic software. The experimental results show that the tracking and aiming control method based on reinforcement learning compensation has good adaptive ability for chassis movement and road surface undulations, which effectively improves the tracking/aiming accuracy and stability of unmanned combat vehicles.

Flashover Characteristics of Insulation Materials of Spacecraft Induced by ESD EMP

ZHANG Yan, ZHAO Xin, LIU Shanghe, QIAN Yuxing, ZHANG Lu, GE Xianghu

2022, 43(8):  1956-1965.  doi:10.12382/bgxb.2021.0396

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To explore flashover characteristics of different insulation materials induced by electromagnetic pulse (EMP) produced during electrostatic discharge (ESD), the ESD EMP-induced flashover test system was employed. According to the theory of secondary electron emission avalanche and superposition principle, and combined with the experiments, the induced flashover law of finger metal electrodes covered by three commonly used spacecraft insulation materials, namley, polymethyl methacrylate (PMMA), polytetrafluoroethylene (PTFE) and epoxy resin (EP) were investigated under the condition of ESD EMP irradiation. The results showed that: the ESD simulator generates EMP radiation field through electrostatic discharge by contacting with vertical metal coupling plate, which forms a compound electric field induced flashover combinded with the DC electric field on both ends of the electrode; when the induced voltage produced by the compound field between two electrodes is less than the flashover voltage of the insulation material, induced flashover cannot be generated; when the induced voltage is close to the material flashover voltage, induced flashover probability exists; the higher the ESD output voltage, the greater the induced voltage generated by the compound field, and the higher the induced flashover probability of the insulation materials, the dielectric strength of the three insulating materials is, the lower the probability of induced flashover under the condition of ESD EMP of the same intensity, so the time required to form a perforative discharge channel between the electrodes during flashover induction increases, the time delay becomes longer, and the induced flashover current increases accordingly.

Calibration and Verification of Dynamic Mechanical Properties of High-strength Armored Steel Based on Johnson-Cook ConstitutiveModel

ZHANG Dujiang， ZHAO Zhenyu， HE Liang， REN Jianwei， QIANG Lusheng， ZHOU Yilai

2022, 43(8):  1966-1976.  doi:10.12382/bgxb.2021.0409

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A specific type of armored steel with high yield strength has been widely used in China to improve the protection performance of armored vehicles. To numerically simulate the dynamic properties of the material，the material’s dynamic constitutive parameters based on the Johnson-Cook constitutive model are calibrated and verified through experiments. First，quasi-static mechanical properties of the armor steel are systematically measured using a universal material testing machine under temperatures ranging from room temperature to 550 ℃.The compression properties of the material are further measured at various strain rates using a separated Hopkinson pressure bar system. Second，based on the Johnson-Cook constitutive model，the measured dynamic properties of the armor steel are fitted to obtain the material’s constitutive parameters. Finally，a monolithic beam made of the armor steel is impacted by a aluminum foam projectile launched from a light-gas gun，and the test results are compared with finite element simulation results obtained using the constitutive parameters and the ideal elastic-plastic constitutive model. The results show that the armor steel demonstrates strong strain rate strengthening effect and thermal softening effect. The relative error between the peak deflection values of the monolithic beam obtained from J-C constitutive model simulation and experimental study is 1.7%-6.1%，and that for residual deflection is 0.6%-7.6%.

Modeling and Simulation of Surface Topography under Ball-end Milling Based on Dynamic Response of Milling System

DONG Yongheng， LI Shujuan， ZHANG Qian， LI Pengyang， LI Qi， JIA Zhen， LI Yan

2022, 43(8):  1977-1989.  doi:10.12382/bgxb.2021.0472

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Milling surface topography modeling based on the dynamic response of the weak-stiffness ball-end milling system has an important theoretical value for improving surface quality. To do this, first of all, the kinematic trajectory of the ball-end milling cutter teeth is established by homogeneous coordinate transformation, and a solution for the milling force is put forward according to the mechanical modeling method. A dynamic model for the flexible cutter-flexible workpiece milling system is established based on the regenerative vibration theory. A method for solving dynamic displacement of processes based on the full discrete method with the effect of variable time delay considered is proposed. And a linear interpolation method is adopted to modify the cutter tooth trajectory. Then, a simulation method for the surface topography under ball-end milling is proposed by combining Z-MAP method and numerical method. After completing geometric simulation of the surface topography generated by the machining path, a physical simulation considering the dynamic displacement of the process system induced by vibration is carried out. Lastly, a validation experiment is conducted by milling material 7050-T6 using a carbide ball-end milling cutter. The experiment and simulation results are consistent, indicating that the modeling method is effective and can provide theoretical basis for selecting and optimizing actual machining parameters.

Microstructures and Mechanical Properties of Welded Joints Made of 603 High Strength Steel and High Nitrogen AusteniticStainless Steel

YANG Dongqing, ZHANG Jian, FAN Jikang, ZHOU Zhao, WANG Kehong

2022, 43(8):  1990-1997.  doi:10.12382/bgxb.2021.0490

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Due to superior mechanical properties, high nitrogen austenitic stainless steel and 603 martensitic high strength steel are ideal materials for armor protection. According to the principle of “low strength matching”, ER307Mo austenitic stainless steel wire is selected for welding 30mm thick high nitrogen austenitic stainless steel and 603 martensitic high strength steel by pulse MIG butt welding. The microstructures and mechanical properties of the welded joints are analyzed. The results show that the welded joints with good surface appearance and no internal cracks and fusion defects are obtained. The microstructure is primarily austenite and ferrite dendrite surrounded by austenite matrix. The microstructure near the fusion line of high nitrogen austenite stainless steel is mainly austenite, and the microstructure near the fusion line of 603 steel is mainly strip martensite, bainite and tempered martensite. The joint's fracture is mainly ductile fracture, with a small percentage of cleavage fracture. EDS point scanning results show that the second phase particles at the center of the dimple are Fe rich carbides. The average tensile strength of the welded joints is 722 MPa and the average elongation after fracture is 20.2%. The dynamic yield strength of the welding metal is 913 MPa, the maximum engineering stress is 2 045 MPa, and the impact resistance exceeds that of the 603 steel base metal.

Piezoelectric MEMS Accelerometer With d₃₁ Mode Cantilever Structure

SHI Shuzheng, GENG Wenping, LIU Yong, BI Kaixi, LI Fen, CHOU Xiujian

2022, 43(8):  1998-2006.  doi:10.12382/bgxb.2021.0464

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To meet the requirements for integrated manufacturing of highly sensitive passive accelerometers, a MEMS piezoelectric accelerometer sensitive structure with four integrating cantilevers picking up microsphere under d₃₁ operating mode is proposed. The theoretical models of dynamic vibration and vibration picking are established, and the structure of the sensor is modeled and simulated by COMSOL 5.0 software. The geometric size and structure of the micro-device satisfying vibration picking conditions are determined by optimization. Heterogeneous integrated fabrication of high-quality PZT piezoelectric thin film based on silicon is realized by sol-gel method. Micro-device is fabricated by MEMS process and the sensor is assembled. The test results show that the relationship between the input acceleration and the output voltage of the accelerometer is V=1.881a-0.033 and the voltage sensitivity reaches 13.8 mV/g at 1 152 Hz, exhibiting good sensitivity, linearity, and anti-interference capability. The correctness of the research method and the feasibility of the manufacturing process are verified, providing a new technological approach for the high-performance acceleration sensor.

Reliability Modelling of Hybrid Redundancy System Based on Generalized Stochastic Petri Nets

SUN Chenfeng, L Weimin, CONG Linhu, XU Pengbo

2022, 43(8):  2007-2016.  doi:10.12382/bgxb.2021.0473

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To address the problems of difficult description of the dynamic performance of redundancy systems and the complex calcuation brought by common cause failure (CCF), a generalized stochastic petri net (GSPN) considering the CCF is proposed. The concepts of shock place and transition are introduced in the modeling of typical redundancy structure to expand the petri net modeling methods and the reachability graphs are generated to verify the feasibility of the models, which efficiently describe the dynamic failure behaviors of the system. By using the timed/immediate transitions and designing the net structure properly, the model realizes the failure information maintenance. Based on the model, the Monte Carlo simulation method is employed to generate system life data and calculate the system reliability. Finally, this paper takes the PLC system of a missile as an example to achieve the modeling from the unit level to the systemic level, and to realize the reliability solution based on hybrid redundancy structure. The results show that the difference between the results of the proposed method and the conventional analytical method which also considers CCF is less than 0.02, which proves its feasibility.