Warhead fragments motion trajectories tracking and spatio-temporal distribution reconstruction method based on high-speed stereo photography

High speed photography technique is potentially the most effective way to measure the motion parameter of warhead fragment benefiting from its advantages of high accuracy,high resolution and high efficiency.However,it faces challenge in dense objects tracking and 3D trajectories reconstruction due to the characteristics of small size and dense distribution of fragment swarm.To address these challenges,this work presents a warhead fragments motion trajectories tracking and spatio-temporal distribution reconstruction method based on high-speed stereo photography.Firstly,background difference algorithm is utilized to extract the center and area of each fragment in the image sequence.Subsequently,a multi-object tracking(MOT)algorithm using Kalman filtering and Hungarian optimal assignment is developed to realize real-time and robust trajectories tracking of fragment swarm.To reconstruct 3D motion trajectories,a global stereo trajectories matching strategy is presented,which takes advantages of epipolar constraint and continuity constraint to correctly retrieve stereo correspondence followed by 3D trajectories refinement using polynomial fitting.Finally,the simulation and experimental results demonstrate that the proposed method can accurately track the motion trajectories and reconstruct the spatio-temporal distribution of 1.0×10^(3)fragments in a field of view(FOV)of 3.2 m×2.5 m,and the accuracy of the velocity estimation can achieve 98.6%.

Three-dimensional reconstruction of precession warhead based on multi-view micro-Doppler analysis

The warhead of a ballistic missile may precess due to lateral moments during release. The resulting micro-Doppler effect is determined by parameters such as the target's motion state and size. A three-dimensional reconstruction method for the precession warhead via the micro-Doppler analysis and inverse Radon transform(IRT) is proposed in this paper. The precession parameters are extracted by the micro-Doppler analysis from three radars, and the IRT is used to estimate the size of targe. The scatterers of the target can be reconstructed based on the above parameters. Simulation experimental results illustrate the effectiveness of the proposed method in this paper.

Double casing warhead with sandwiched charge:The axial distribution of fragments velocities

The double casing warhead with sandwiched charge is a novel fragmentation warhead that can produce two groups of fragments with different velocity,and the previous work has presented a calculation formula to determine the maximum fragment velocity.The current work builds on the published formula to further develop a formula for calculating the axial distribution characteristics of the fragment velocity.For this type of warhead,the simulation of the dispersion characteristics of the detonation products at different positions shows that the detonation products at the ends have a much larger axial velocity than those in the middle,and the detonation products have a greater axial dispersion velocity when they are closer to the central axis.The loading process and the fragment velocity vary with the axial position for both casing layers,and the total velocity of the fragments is the vector sum of the radial velocity and the axial velocity.At the same axial position,the acceleration time of the inner casing is greater than that of the outer casing.For the same casing,the fragments generated at the ends have a longer acceleration time than the fragments from the middle.The proposed formula is validated with the X-ray radiography results of the four warheads previously tested experimentally and the 3D smoothedparticle hydrodynamics numerical simulation results of several series of new warheads with different configurations.The formula can accurately and reliably calculate the fragment velocity when the lengthto-diameter ratio of the charge is greater than 1.5 and the thickness of the casing is less than 20%its inner radius.This work thus provides a key reference for the theoretical analysis and the design of warheads with multiple casings.

Axis intersection measurement of three-axis turntable with two crosshair targets

In order to measure three-axis intersection error, two crosshair targets were fixed in the inner axis frame of a three-axis turntable. Also a theodolite was used to point its telescope to the targets and to measure the horizontal angles when three axes were on equi-spaced angle positions. The calculation equations of the axis intersection were deduced from the mounting position of the theodolite, positions of two targets, angular positions of three axes, and the measured horizontal angles with the theodolite. Finally, a practical measurement is carried out on a horizontal three-axis turntable and error analysis is conducted.

Application of hybrid robust three-axis attitude control approach to overactuated spacecraft——A quaternion based model

A novel hybrid robust three-axis attitude control approach, namely HRTAC, is considered along with the well-known developments in the area of space systems, since there is a consensus among the related experts that the new insights may be taken into account as decision points to outperform the available materials. It is to note that the traditional control approaches may generally be upgraded, as long as a number of modifications are made with respect to state-of-the-art, in order to propose high-precision outcomes. Regarding the investigated issues, the robust sliding mode finite-time control approach is first designed to handle three-axis angular rates in the inner control loop, which consists of the pulse width pulse frequency modulations in line with the control allocation scheme and the system dynamics. The main subject to employ these modulations that is realizing in association with the control allocation scheme is to be able to handle a class of overactuated systems, in particular. The proportional derivative based linear quadratic regulator approach is then designed to handle three-axis rotational angles in the outer control loop, which consists of the system kinematics that is correspondingly concentrated to deal with the quaternion based model. The utilization of the linear and its nonlinear terms, simultaneously, are taken into real consideration as the research motivation, while the performance results are of the significance as the improved version in comparison with the recent investigated outcomes. Subsequently, there is a stability analysis to verify and guarantee the closed loop system performance in coping with the whole of nominal referenced commands. At the end, the effectiveness of the approach considered here is highlighted in line with a number of potential recent benchmarks.

Underactuated spacecraft angular velocity stabilization and three-axis attitude stabilization using two single gimbal control moment gyros

Angular velocity stabilization control and attitude stabilization control for an underactuated spacecraft using only two single gimbal control moment gyros （SGCMGs） as actuators is investigated. First of all, the dynamic model of the underactuated spacecraft is established and the singularity of different configurations with the two SGCMGs is analyzed. Under the assumption that the gimbal axes of the two SGCMGs are installed in any direction, and that the total system angular momentum is not zero, a state feedback control law via Lyapunov method is designed to globally asymptotically stabilize the angular velocity of spacecraft. Under the assumption that the gimbal axes of the two SGCMGs are coaxially installed along anyone of the three principal axes of spacecraft inertia, and that the total system angular momentum is zero, a discontinuous state feedback control law is designed to stabilize three-axis attitude of spacecraft with respect to the inertial frame. Furthermore, the singularity escape of SGCMGs for the above two control problems is also studied. Simulation results demonstrate the validity of the control laws.

A Three-Axis Robot Using a Remote Network Control System

For the petroleum industry, to reduce the risk of a gas explosion in dangerous working areas, the use of explosion-proof equipment such as air-driven devices which are free from explosions becomes essential. Moreover, for the purpose of saving manpower, a remote operation using a robot via a visual monitoring system and a network is used. However, to overcome the drawback of costly manpower and to improve safety in explosion-prone zones, a three-axis robot using a remote network control system is proposed. In this paper, the three-axis robot can be monitored online via the USB protocol. Furthermore, it also can be remotely manipulated via the TCP/IP protocol by clicking the command of the VB interface on the client pc. Consequently, the remote-control three-axis robot can not only work for people in severe and dangerous circumstances but also can reduce the cost of manpower.

IMPROVED QUANTITATIVE FEEDBACK THEORY TECHNIQUE AND APPLICATION TO THREE-AXIS HYDRAULIC SIMULATOR

In order to meet tracking performance index of three-axis hydraulic simulator, based on classical quantitative feedback theory （QFT）, an improved QFT technique is used to synthesize controller of low gain and bandwidth. By choosing a special nominal plant, the improved method assigns relative magnitude and phase tracking error between system uncertainty and nominal control plant. Relative tracking error induced by system uncertainty is transformed into sensitivity problem and relative tracking error induced by nominal plant forms into a region on Nichols chart. The two constraints further form into a combined bound which is fit for magnitude and phase loop shaping. Because of leaving out pre-filter of classical QFT controller structure, tracking performance is enhanced greatly. Furthermore, a cascaded two-loop control strategy is proposed to heighten control effect. The improved technique＇s efficacy is validated by simulation and experiment results.

Misalignment Angle Calculation Accuracy Analysis of Three-Axis Stabilized Geostationary Satellite

The most challenging problem of navigation in three-axis stabilized geostationary satellite is accurate calculation of misalignment angles, deduced by orbit measurement error, attitude measurement error, thermal elastic deformation, time synchronization error, and so on. Before the satellite is launched, the misalignment model must be established and validated. But there were no observation data, which is a non-negligible risk of yielding the greatest returns on investment. On the basis of misalignment modeling using landmarks and stars, which is not available between different organizations and is developed by ourselves, experimental data are constructed to validate the navigation processing flow as well as misalignment calculation accuracy. In the condition of using landmarks, the maximum misalignment calculation errors of roll, pitch, and yaw axis are 2, 2, and 104 micro radians, respectively, without considering the accuracy of image edge detection. While in the condition of using stars, the maximum errors of roll, pitch, and yaw axis are 1, 1, and 3 micro radians, respectively, without considering the accuracy of star center extraction. Results are rather encouraging, which pave the way for high-accuracy image navigation of three-axis stabilized geostationary satellite. The misalignment modeling as well as calculation method has been used in the new generation of geostationary meteorological satellite in China, FY-4 series, the first satellite of which was launched at the end of 2016.

The Impact Study of Three-axis Servo System Interference Torque based on Virtual Prototype

The three-axis servo system with the core of gyro stabilization is the foundation to realize its function, and a key technology of the seeker devolopment. In order to reduce the costs, improve the efficiency of research and devolopment, a new method that instead of physical prototype by virtual prototype was proposed. Adams and MATLAB/simulink are used to establish the mechanical dynamics model and controller model of the three-axis servo system. The simulation data which was processed and analyzed is compared with test data, to determine the control parameters of the virtual prototype and improve the accuracy of the model, and test the multiple condition simulation,which can provide a reference for practical production.The simulation results verify the feasibility of the models.

杀爆战斗部破碎形态及破片飞散特性数值模拟研究

针对战斗部威力与毁伤效能评估需求,采用FEM和SPH方法基于相同的结构尺寸和材料参数构建了某型杀爆战斗部的数值模型,研究了杀爆战斗部的弹体破碎形态及破片飞散速度沿轴线分布规律,同时对爆炸能量在各物质之间的传递及分配情况进行了计算。研究结果表明:SPH方法可以较好的模拟弹体裂纹扩展和破片生成,但在破片初速计算上,SPH方法忽略了爆轰产物加载过程,而FEM方法无法计算破片速度牵连作用,两者与试验结果相比分别偏低4.4%和7.5%,SPH方法可以更加准确反映爆炸能量在各物质之间的传递及分配规律,其中破片动能占爆炸总能量的36%,壳体拉伸、断裂的塑性变形能占爆炸总能量的5.7%。

侵彻战斗部-引信宽频域加载特性

为揭示侵彻过程中战斗部对引信边界载荷的影响规律,建立战斗部动力学模型和有限元模型。通过有限元差分法计算和数值模拟分析战斗部在不同频率半正弦信号激励下对引信的瞬态加载特性,并采用数值模拟和打靶试验研究弹靶作用时弹体和引信体的过载时域响应特性,通过冲击响应谱数值计算得到引信过载在频域范围的响应放大倍数。研究结果表明:侵彻战斗部在宽频域范围具有明显的轴向振动放大特性。引信过载频响特性与谐响应分析结果表明,侵彻战斗部在宽频域范围轴向振动放大特性的根本原因是战斗部1阶或多阶轴向振动固有频率的谐振,为指导弹载产品的抗高过载优化设计提供了依据。

两种钛合金半穿甲战斗部侵彻单层钢靶性能试验研究

选取亚稳态β型TB17和高损伤容限α+β型TC4-DT两种高韧钛合金材料,对2种钛合金材料在高应变率条件下动态力学响应特性进行测试分析,并应用125 mm火炮发射装置开展2种钛合金半穿甲战斗部侵彻单层钢靶性能试验研究。结果表明,作为半穿甲战斗部的壳体材料,应选择屈服强度与冲击韧性匹配性好的钛合金,其中更应关注钛合金材料的塑性变形能力和抗冲击韧性;随着侵彻着角的增加,侵彻单层钢靶过程弹体头部侵蚀量及径向墩粗程度更严重,不利于弹体保持侵彻强度及装药安定性。

圆锥-球缺组合药型罩战斗部侵彻双层水间隔靶板

为提升聚能战斗部毁伤性能,基于组合药型罩战斗部的起爆机理,设计一种圆锥-球缺组合药型罩聚能战斗部及双层水间隔靶板结构,建立该战斗部侵彻双层水间隔靶板的物理模型,进行数值模拟计算,根据计算结果加工战斗部及靶板的1∶3缩比模型样机,展开相应试验,为设计全尺寸战斗部样机奠定了基础。试验结果表明:该战斗部侵彻含水夹层目标时具有独特的优势,对目标的破坏效应显著增强。

加强筋位置对半穿甲战斗部侵彻多层钢靶性能影响研究

为了研究加强筋位置对半穿甲战斗部侵彻多层钢靶性能的影响,通过试验及数值仿真,研究了加强筋在弹体轴向不同位置处的2种半穿甲战斗部,以一定速度(710 m/s)、着角(20°)侵彻8层钢靶的弹道偏转、弹孔尺寸、余速的差异。研究结果表明:加强筋位置由弹尖向质心位置逼近时弹道偏转角减小、弹孔长轴减小、穿甲能力提升;弹道偏转角增量与靶间距呈正相关关系;弹道偏转角、侵彻余速、弹头侵蚀量及弹孔仿真结果与试验实测值最大偏差为8.82%,仿真与试验结果符合较好。研究结果可为半穿甲战斗部方案设计提供参考。

应用差分进化-神经网络模型的杀爆弹瞄准点分配方法

为在不增加计算时耗的前提下提升多枚杀爆弹对面目标打击毁伤效能,建立融入动爆威力计算的多瞄准点规划方法.对面目标采用结构化网格划分方法实现多枚杀爆弹对目标毁伤区域的精确计算,并进行计算结果验证,基于多次计算结果采用神经网络方法建立单枚弹药对面目标毁伤区域的计算代理模型,在同样计算条件下,比非代理模型计算时间缩短1000倍;据此,通过差分进化算法实现多枚杀爆弹对面目标打击瞄准点及末端弹道参数的规划.通过实例对比分析表明:该瞄准点规划方法形成的打击方案比传统以毁伤半径为输入的方法毁伤效果大幅提升,最低提升25.5%,且单次规划时间不超过3 s,解决了瞄准点规划中毁伤效能模型复杂度与计算耗时之间的矛盾.

动能侵彻弹装药起爆可靠性试验及敏感因素分析

为研究弹体结构设计对弹体装药起爆可靠性的影响,设计了一种低成本、便捷式引战静态匹配试验装置,开展了不同条件下引信与装药的传爆裕度试验。基于移动最小二乘法,构建了可表征起爆可靠性的多变量响应函数,定量分析了各敏感因素及其耦合作用对起爆可靠性的影响规律。结果表明:传爆间隙和缓冲层厚度对弹体装药起爆影响较大,而隔板厚度在预设3~5 mm范围内的影响较小;为保证动能侵彻弹在使用环境温度范围内可靠作用,引信相对偏离位置、隔板厚度、传爆间隙以及缓冲层厚度分别不应超过25、3.5、25以及22 mm。该试验装置、分析方法及研究成果可为动能侵彻弹结构设计及可靠性验证提供借鉴和指导。

战斗部破片光电测速系统设计

战斗部破片的飞行速度是体现其性能指标的重要参数;针对目前在战斗部破片速度参数测试中存在对测试环境要求高,测试面积小,设备结构易被破片误击而损坏,成本昂贵等问题,设计了非接触式战斗部破片光电测速系统,包含原向反射膜、反射式光电探测装置、光电转换电路、信号处理电路及测速装置;阐述了系统结构组成和测速原理,通过反射式光电探测装置与光电转换电路,将得到的光信号转换为电信号,利用集成信号处理电路对电信号滤波放大,比较整形处理,由FPGA,STM32及其他外设组成的测速装置自动处理数据输出并显示战斗部破片的飞行速度结果;实验结果表明:该系统能够可靠,稳定地完成战斗部破片速度的测量任务;与传统测速系统相比,具有不受限于环境,测试区域大,易维护,低成本,操作简单等优势。

不同组合式聚能战斗部对水下目标的毁伤研究

为研究不同组合药型罩聚能型鱼雷战斗部对含水复合结构的穿透性能,建立了聚能装药侵彻含水复合结构的数值计算模型,分析了射流成型过程和穿靶过程。结果表明:圆柱-球缺组合罩相比于其他2种组合药型罩对含水复合结构的穿透性能更好,对后效靶造成的穿深最大。圆柱-球缺组合罩形成的射流长度相比于其他2种组合药型罩分别长10.4%和28.9%,头部速度分别高20.6%和54.3%。侵彻含水复合结构时,圆柱-球缺组合罩形成的水下空腔、水介质径向扩展速度均最小,所以在侵彻含水复合结构后得以保留最大的剩余动能,从而对后效靶造成的穿深最大。合理匹配圆柱-球缺药型罩圆柱部直径d和高度h可提升其对含水复合结构的穿透能力,当d=22 mm、h=16 mm时,圆柱-球缺组合罩可对后效靶取得最大穿深411 mm。结论可为聚能型鱼雷战斗部的组合药型罩选择提供参考。

Cluster Warhead Dispersing Technique and Its Interior Ballistic Calculation

Cluster warhead dispersing technique is analyzed with gas dynamic theory. It is seen that the front cover opening and two stage dispersing system is suitable for guided sub missiles whose number is not so large. The interior ballistic performances of this system are calculated with numerical calculation method. The performances such as the pressure in the pressure chambers and the velocity of the sub missiles are obtained in curve form.