Extraction Phase Simulation of Cargo Airdrop System

To study the characteristics of cargo extraction, the initial phase of airdrop process, a high fidelity and extendibility simulation model with uniform motion equations for all states during extraction is developed on the basis of dynamics methods and contact models between cargo and aircraft. Simulation results agree well with tests data. Cargo exit parameters, which contribute to cargo pitch after extraction, are studied. Simplified computation model of dimensionless exit time is developed and used to evaluate the relation between extraction phase and landing accuracy. Safe interval model is introduced to evaluate the safety of extraction process. Also, relations between initial parameters, including pull coefficient, aircraft pitch and CG coefficient, etc, and result parameters, including exit time, cargo safety, pitch, etc, are developed to help design of airdrop system, especially the selection of extraction parachute and cargo deployment.

Parachute dynamics and perturbation analysis of precision airdrop system

To analyze the parachute dynamics and stability characteristics of precision airdrop system, the fluid-structure interaction （FSI） dynamics coupling with the flight trajectory of a para- chute payload system is comprehensively predicted by numerical methods. The inflation behavior of a disk-gap-band parachute is specifically investigated using the arbitrary Lagrangian Euler （ALE） penalty coupling method. With the available aerodynamic data obtained from the FSI sim- ulation, a nine-degree-of-freedom （9DOF） dynamic model of a parachute-payload system is built and solved to simulate the descent trajectory of the multi-body dynamic system. Finally, a linear five-degree-of-freedom （5DOF） dynamic model is developed, the perturbation characteristics and the motion laws of the parachute and payload under a wind gust are analyzed by the linearization method and verified by a comparison with flight test data. The results of airdrop test demonstrate that our method can be further applied to the guidance and control of precision airdrop systems.

彩虹表在溯源取证中的应用

随着无线网络传输技术的发展及经济利益的驱动,近年来利用隔空投送(AirDrop)进行无线传输已渐成规模。AirDrop可匿名发送、无需联网,因此难以对其进行追踪,成为技术人员溯源的一大难题。提出一种应用彩虹表时空折中原理的溯源技术,精确匹配发送手机号码的取证方法,突破了匿名溯源技术难题。

Simulation and optimization for airdrop adaptability of overweight equipment

Airbag buffer process was analyzed with the aid of aerodynamic and thermodynamic methods.Based on the current structure of the airbag,the terminal velocity was too high.Therefore,the research on the diameter and height of the airbag was done and the feasible design area was found.With the optimized structure parameters,the airbag buffer experiment under normal conditions was conducted.Furthermore,the residual height and internal pressure of the airbag as well as the terminal velocity and acceleration of the airdrop were obtained.The experiment results show that the optimized airbag is feasible for 20 t cargo airdrop.

Structural Design Study of Air-Dropped Unmanned Maritime Mobile Search and Rescue Platforms

In order to improve the efficiency and safety of search and rescue(SAR)at sea,this paper proposes a kind of emergency rapid rescue unmanned craft(air-dropped unmanned maritime motorized search and rescue platform)that can be delivered by a large transport aircraft.This paper studies the structural design scheme of the platform,and the main scale of the platform,the choice of power system and the impact resistance performance are considered in the design process to ensure its rapid response and effective rescue capability under complex sea conditions.Simulation results show that the platform can withstand the impact of air injection into the water and the shipboard equipment can operate normally under the impact load,thus verifying the feasibility and safety of the design.This study serves to improve the maritime search and rescue system and enhance the oceanic emergency response capability.

空降车辆着陆缓冲过程系统建模仿真研究综述

系统建模仿真作为空降车辆着陆缓冲研究的重要手段,用于仿真着陆缓冲阶段的气囊排气压缩、车辆缓冲过载、姿态变化及结构冲击响应。从系统建模、匹配设计、半实物试验、空投适应性4个方面进行评估,综述现有研究应用的理论、方法和研究结论。对目前仿真模型求解效率,结构应力和气囊仿真准确度,车辆与气囊参数匹配,半实物试验,空投适应性评估等问题进行分析总结并提出进一步的研究方向。

A Bio-Inspired Flapping-Wing Robot With Cambered Wings and Its Application in Autonomous Airdrop

Flapping-wing flight, as the distinctive flight method retained by natural flying creatures, contains profound aerodynamic principles and brings great inspirations and encouragements to drone developers. Though some ingenious flapping-wing robots have been designed during the past two decades, development and application of autonomous flapping-wing robots are less successful and still require further research. Here, we report the development of a servo-driven bird-like flapping-wing robot named USTBird-I and its application in autonomous airdrop.Inspired by birds, a camber structure and a dihedral angle adjustment mechanism are introduced into the airfoil design and motion control of the wings, respectively. Computational fluid dynamics simulations and actual flight tests show that this bionic design can significantly improve the gliding performance of the robot, which is beneficial to the execution of the airdrop mission.Finally, a vision-based airdrop experiment has been successfully implemented on USTBird-I, which is the first demonstration of a bird-like flapping-wing robot conducting an outdoor airdrop mission.

Dynamic modeling of a parafoil system considering flap deflection

In order to better study the dynamic characteristics and the control strategy of parafoil systems,considering the effect of flap deflection as the control mechanism and regarding the parafoil and the payload as a rigid body,a six degrees-of-freedom(DOF)dynamic model of a parafoil system including three DOF for translational motion and three DOF for rotational motion,is established according to the K rchhoff motion equation.Since the flexible winged paafoil system flying at low altitude is more susceptibleto winds,the motion characteristics of the parafoil system Wth and Wthout winds are simulated and analyzed.Furthermore,the ardropm test is used to further verify the model.The comparison results show that the simulation trajectory roughly overlaps with the actual flight track.The horzontnl velocity of the simulation model is in good accordance with the airdrop test,with a deviation less than0.5m/s,while its simulated vertical velocity fuctuates slightly under the infuence of the wind,and shows a similar trend to the ardrop test.It is concludedthat the established model can well describe the characteristics of the parafoil system.

装备空投多体系统动力学建模与仿真方法研究进展

装备空投是将装备向指定的地面区域快速投送的技术,拥有快速响应和长距离作战的特点。装备空投系统是典型的多体系统,目前,仍然面临落点精度及安全性等关键瓶颈问题,与空投所涉及的流固耦合、强非线性、接触碰撞、大变形结构动力学密切相关。因此,该文从多体系统动力学建模、动力学性能预测与优化设计等方面综合阐述装备空投的国内外研究进展,总结装备空投的研究发展趋势以及技术难题,指出了提高装备空投精度和安全性的前沿研究方向。

不确定因素下空投系统气囊缓冲仿真研究

在货台空投稳降阶段,降落伞系统的摆动及着陆区域不平整地形等不确定因素不仅对气囊缓冲能力产生影响,严重时甚至可能导致货台侧翻,有必要针对这种更为一般的着陆条件进行仿真分析。在现有的空投系统气囊缓冲过程仿真模型基础上,考虑货台下落姿势和地面坡度两个因素,构建不确定因素下气囊缓冲的仿真模型,通过蒙特卡洛仿真获取大量结果样本点,结合置信水平得到货台着陆可靠度。算例结果表明,所建模型能有效模拟缓冲气囊的实际工作特性,仿真算法结果合理,可行性高,具有更广泛的工程应用价值。

货台空投系统气囊缓冲过程仿真

基于热力学方法,建立了货台空投系统气囊缓冲过程仿真模型。综合考虑了实际缓冲工作过程中气囊的形变与排气口面积的变化,从而更加有效的模拟了该型缓冲气囊的实际工作特性。仿真结果与试验结果一致,能够准确的计算缓冲过程最大过载、缓冲过程时间等特性。基于DirectXSDK实现了气囊缓冲过程的可视化仿真。建模方法与可视化技术可用于其他型号气囊的缓冲特性仿真计算工作。

考虑多种影响因素下的改进重装空投系统建模

针对当前重装空投数学模型与实际系统存在偏差的问题,放宽建模假设,提出了牵引伞力作用方向,建立了涵盖刚体货物、舱内地板角、牵引伞等影响因素的空投数学响应模型。针对建模过程的复杂性,改进了传统分离体法建模方法,简化了建模过程,提高了模型的扩展性。最后,通过与现有重装空投模型的理论分析与仿真对比,证明了该模型具有较小的建模误差,更贴近于实际重装空投系统。

翼伞精确空投系统关键技术和发展趋势

为保证载机安全的同时提高着陆精度,重点对翼伞精确空投系统进行研究。介绍精确空投系统中翼伞的应用发展和国内外研究小组的工作,对翼伞精确空投系统的关键技术进行详细阐述,介绍翼伞精确空投的几个典型应用,探讨翼伞精确空投的发展趋势。该研究可对我国进行翼伞精确空投系统实验研究和工程设计提供一定的技术参考。

货台空投系统的三维动画仿真

提出了基于DirectX的货台空投系统三维动画仿真软件的设计思想和实现方法,将空投系统仿真与计算机三维动画实现技术相结合,设计开发了多级多伞货台空投系统的三维动画仿真软件。具备数据管理与分析、系统动力学计算、降落伞动力学计算、关键计算参数的实时查询、空投过程三维动画演示、货台出机安全性分析等功能。应用本软件对实际空投过程进行了仿真,精度和效果均与试验录像基本吻合。还可以用于各种其他类型的货台空投系统以及伞兵或运动员跳伞训练系统的仿真和设计分析。

基于有限元分析的重型装备空投系统匹配和评估

针对采用实装试验研究空投装备着陆缓冲过程的方法难以得到有效结果的问题,采用非线性有限元分析方法,结合气体热力学理论,建立重型装备空投系统解析模型和非线性有限元模型,结合试验数据验证模型的有效性和精度.在分析重型装备空投着陆缓冲过程的响应特性基础上,采用拉丁超立方试验设计方法和移动最小二乘法构建响应面模型,结合环境条件的统计规律研究空投系统的匹配和评估方法.分析高海拔条件下空投过程中存在的问题,给出其发生机理并提出解决方案.

粒子群算法在翼伞空投系统航迹规划中的应用

针对当前翼伞系统研究中未考虑到地形威胁、火力威胁对航迹规划影响的问题,对地形威胁和火力威胁进行了建模,结合翼伞飞行特性,引入最小威胁曲面生成三维航迹搜索空间,并利用粒子群算法搜索优化翼伞系统的航迹。仿真结果表明,粒子群算法能有效地减小搜索空间,提高规划的效率,且使规划出的航迹能够躲避威胁,满足航程和高度的要求。

采用卫星与惯性导航对空投精确控制研究

精确空投系统需要载荷投放到空中后在运动状态下,载荷捷联的卫星与惯性组合导航子系统完成初始对准,为后续精确对准及组合导航提供初始姿态矩阵。在上述条件下因陀螺无法测出地球自转角速度,而且重力加速度受到干扰,传统的静基座及晃动基座对准的方法无法采用。因此如何完成载体空中动基座对准成为精确空投系统的技术难点。针对上述问题,提出了一种运动状态下,利用导航坐标系和载体坐标系比力映射关系的求解初始姿态矩阵的方法。上述算法是在卫星导航装置辅助下,测得对准时段内的载体位置坐标及导航坐标系下载体的运动速度,根据比力方程并对姿态矩阵进行分解,导出初始姿态矩阵的解算表达式。模拟空投载体的下落过程,对算法误差进行了仿真分析,结果表明算法产生的误差角均为小角度,并可以进行后续精确对准。验证了上述方法可以满足精确空投系统的载体空中动基座初始对准的需求。

空投着陆缓冲系统效能评估模型

为了有效构建空投缓冲系统效能评估体系,研究建立了不同缓冲系统通用效能评估模型。模型综合分析缓冲系统作战能力与保障能力,建立了空投缓冲系统效能指标体系。在此基础上,运用效能评估ADC模型与AHP方法,结合指标能力量化准则实现对缓冲系统效能的定量评定。通过实例计算,验证了模型的正确性和有效性,为缓冲系统的发展论证与使用决策提供依据。

翼伞空投系统模糊控制器的设计与实现

翼伞系统为复杂的非线性系统,在飞行过程中易受外界因素的干扰。针对翼伞空投系统在实际工程中的应用,提出1种基于模糊逻辑的翼伞导航控制算法。首先,建立六自由度的翼伞系统动力学模型,针对其动力学特性设计飞行控制方案,最后讨论风的干扰对系统稳定性的影响。仿真结果表明,模糊控制算法简单有效,易于实现,完全满足航迹跟踪的要求。

空投装备气囊缓冲系统评价方法

以热力学理论和有限元法为基础,建立装备-气囊系统有限元模型,并利用试验数据对模型进行验证。对比结果表明,所建模型系统的精度较高,可以用在下一步的仿真分析工作中。针对缓冲气囊的复杂非线性模型计算规模大、难以进行大规模计算的问题,以着陆初速度、初始侧倾角、初始俯仰角、横向速度和地面坡度为变量,分别以最大冲击加速度、最大侧倾角、最大俯仰角以及气囊最大内压为响应,结合扩展拉丁超立方设计,采用径向基函数构建多工况响应代理模型。考虑空投装备在着陆过程中环境因素以及空投装备着陆姿态的影响,利用蒙特卡罗法结合代理模型对多工况下的空投装备着陆成功概率进行计算。通过计算得到着陆成功概率为95.84%,冲击加速度为其主要影响因素,气囊内压为次要因素。