系缆气球的气动力估算和配平计算

从飞行力学分析的角度,用传统的气动力估算方式对具有倒"Y"型尾翼的系缆气球的气动力特性进行估算.考虑气球与系缆的综合系统,建立系缆气球平衡方程并进行配平计算.在不同的风速条件下,采用牛顿下降梯度法迭代求解非线性代数方程组形式的系缆气球平衡方程.通过不同风速及不同系缆位置的平衡状态的对比分析,确认系缆的最佳悬挂位置.      

某系留气球抗风性能仿真分析

系留气球以其显著特点已应用到许多领域,今后还会有大的发展。因所处环境的风力对飞行稳定性影响较大,故抗风能力成为系统重要指标。针对无法用实验手段进行验证的空中工作姿态,一般采取计算机仿真方法进行模拟研究。介绍了系留气球的设备组成,描述了空中飞行状态,通过建立动力学模型的数学方程式,施加1-consine型离散突风模型扰动,仿真了空中球体的俯仰角和滚转角随扰动时间的关系曲线,并对结果曲线进行分析研究,以期为同型系留气球的设计方法提供某种借鉴,为浮空器使用安全提供帮助。     

基于高阶LADRC的V/STOL飞机悬停/平移 模式鲁棒协调解耦控制

针对垂直/短距起降（V/STOL）飞机在悬停/平移模式下存在的动力学耦合、推力矢量控制冗余以及易受扰动风影响的问题,提出了一种基于高阶线性自抗扰控制（LADRC）的鲁棒协调解耦控制方法。首先根据V/STOL飞机的概念方案,建立了推力矢量模型和扰动风影响下的非线性悬停/平移运动模型。然后在此基础上,给出了该模式下位置和姿态的协调控制策略,据此通过控制量变换设计了六通道的自抗扰解耦控制律,其中利用LADRC对总扰动的实时估计补偿能力避免了多推力矢量的冗余控制。仿真比较结果验证了LADRC对悬停/平移模式控制的有效性以及对飞机内部参数摄动和外界突风干扰的鲁棒性。      

系留气球时域响应分析

为研究系留气球稳定性,建立了系留气球的三维非线性动力学模型.缆绳采用有限差分法,球体采用经典的六自由度方程,其中气动力导数以静导数、动导数和附加质量表示.以主节点运动为边界条件,以静态构型为初始条件,建立完整耦合动力学方程.利用直接求解非线性偏微分方程的方法对该系统进行时域响应分析,考察了风速对纵向和横侧向稳定性的影响,并给出相应的响应曲线.直接求解非线性耦合方程的成功,表明该数学模型及其解法是可行的.      

一种抑制扰动的轴向磁轴承鲁棒控制新方法

从鲁棒稳定性和抑制扰动的动态性能角度,分析了干扰观测器应用到轴向磁轴承时其有效带宽较低的问题,指出磁轴承易受到低频干扰并提出了一种抑制扰动鲁棒控制方法.基于动态分析建立了轴向磁轴承的名义模型,并设计了内环控制的干扰观测器,采用标准H∞问题的方法设计抑制扰动鲁棒控制器作为外环控制.仿真分析与实验说明了该方法能够提高干扰观测器的带宽,同时,实验验证了对于系统参数不确定性具有较强的鲁棒性能,对比单一的控制方法具有良好的抑制扰动能力.     

变化风场对舰载飞机着舰安全性影响

建立了复杂环境下舰载机进舰着舰的数学仿真模型,并通过大量的仿真计算,研究了舰尾流和侧风风场对舰载机进舰着舰安全性的影响,给出了一定进舰条件下舰载机所能抗御的最大侧风强度.研究结果表明,舰载机在进舰过程中必须通过驾驶员操纵抑制舰尾流扰动,否则将引起较大的着舰偏差,影响着舰安全;对于一定的进舰初始条件,舰载机只能抗御一定强度的侧风,超出允许侧风强度时舰载机将不能成功着舰.     

一类月面钻进采样机构的鲁棒控制

在月面复杂环境下采样机构模型会发生摄动,并会受到系统扰动影响,采样控制器的鲁棒性对顺利完成采样任务具有重要意义.针对回转与进尺复合式月面自动钻进采样机构建立名义控制模型,分析月面工作过程中的模型摄动、系统扰动下的控制系统模型,利用线性矩阵不等式方法进行状态反馈鲁棒控制律设计.仿真结果表明:在有界模型摄动、有界随机系统扰动情况下,系统具有鲁棒性,并对扰动具有抑制能力.     

计算机辅助髓内钉远端锁定系统误差分析

针对长骨骨折手术,介绍了一种基于图像导引的计算机辅助骨外科手术系统,用于解决因髓内钉在植入骨髓腔过程中变形而造成的锁钉困难问题.在分析系统结构及数学模型特点的基础上,设计了一种误差分析方法来评定该系统的误差分布;引入蒙特卡罗方法具体完成了误差计算与统计,并给出了系统误差的来源分布特点;完成了系统性能的评估,为进一步优化和增强系统功能提供了理论依据.该分析方法能够为具有复杂数学模型的同类系统的设计提供一定的参考.      

挠性支承对飞轮隔振系统性能的影响分析

飞轮的高速转子在运转过程中会激发微幅多频振动,对航天器的高精度姿态稳定控制产生不利影响.本文基于飞轮隔振系统结构,建立其动力学模型,并通过实验验证该被动隔振装置的固有模态.对增加挠性支承的飞轮隔振系统的数学模型,通过仿真分析隔振装置在挠性支承条件下对飞轮扰动的抑制效果,实验测试了不同挠性支承条件对飞轮隔振系统微振动特性的影响.结果表明,隔振装置在悬臂挠性支承条件下依然具有优异的隔振性能,挠性支承刚度的适当减弱有利于飞轮隔振系统抑制扰动;挠性支承刚度会降低飞轮隔振系统的二阶结构固有振动频率,但基本不影响其涡动特性.     

一类线性不确定大系统的分散变结构控制

研究了具有参数摄动、关联影响和外界干扰等不确定性因素影响的线性大系统的分散控制问题,在假设系统不确定性有界且满足一定匹配条件的前提下,提出了一种分散变结构滑模控制算法,并给出了消颤方案和控制受限的解决方法.该算法结构简单计算量小,同时闭环系统具有较好的动态特性和较强的鲁棒性,数字仿真表明了该算法的有效性.      

Feasibility study of a sea-anchored stratospheric balloon for long-duration flights

Sea-anchored balloons are stratospheric super-pressure balloons that are anchored to the sea. The sea-anchored balloon is a simple system that has the capability for long-duration flights, fixed-point observations, flexible launch windows, easy telemetry links to ground stations, and quick recoveries. Such balloons are not required to fly through the jet stream while tethered to the ground or sea, because the tether is deployed from a reel on the balloon after reaching a floating altitude. In this study, the feasibility of the sea-anchored balloon is investigated, with particular emphasis on the tether strength, balloon altitude, and system mass, based on the present technological level of the tether’s specific strength. Although the wind distribution with altitude is a dominant factor for feasibility, a sea-anchored balloon with an altitude of about 25 km would be feasible if the velocity of the jet stream is sufficiently low. The sea-anchored balloon can be simply flight-tested, since additional ground facilities and special flight operations are not necessary.     

卫星控制系统时序建模分析方法研究

分析国内外卫星控制系统时序分析与设计方法和方法的现状,阐述了对时序进行数学建模的重要性.提出了针对时序设计过程的数学建模分析方法和时序描述的工作流图方法,通过系统性的时序建模,可求解出时序过程中的所有时间参数,以便用于时序分析和指导时序测试.     

The development of plastic,zero pressure balloon design since 1945

There have been four major thrusts in plastic, zero pressure balloon design in the U.S. since the late 1940's. First, the pioneer balloonists made designs according to geometric shapes. When these balloons began to fail, a study at the University of Minnesota produced the first mathematical model for determining the proper design for “natural shaped” balloons. With the advent of high speed digital computing came the “Sigma” tables of the 1960's. When computers became more widespread and inexpensive, direct or “full-sized” designs began to be used. Now, with the problems involved in flying heavy payloads (greater than 400 lbs) and super pressure balloons, a new tool has become available to the balloon designer. An inexpensive stress analysis code is available but is as yet unproven.     

Balloon-borne,high-altitude gravimetry

Gravity measurements from a high-altitude balloon can verify global and upward-continued gravity models. A gravimeter suspended beneath a balloon is in a dynamic, and largely unpredictable, environment sensing accelerations due to gravity and balloon motions. Independent measurements of balloon motions using inertial navigation data combined with ground tracking data will allow for separation of balloon-induced accelerations from gravitational accelerations. Analysis of these data must estimate: 1) vertical gravimeter accelerations due to motion and gravity, 2) horizontal velocity to estimate the Eötvös effect, and 3) gravimeter position for comparison with gravity models. The first engineering test flight occurred on 11 October 1983, during the seasonal wind reversal and was very successful. Flight duration was approximately seven hours, with two hours of data collected at each of 30 km and 26 km altitudes. The results include gravity estimates, design criteria for future flights and feasibility analysis for vertical gravity profiles during ascent and descent.     

高空气球综合/开放式设计系统

开发了一种新架构的高空气球设计系统,引入了综合性、开放式的设计理念,采用面向对象的整合方法,包含了自定义开发、多Agent基线比选等开放性设计功能,通过实例证明了该系统不仅可以进行模型建立、性能分析、费用评估等分析结果综合评价,还使方案设计与数字加工、飞行仿真等实际应用结合在一起.     

捕风一号卫星总体设计与技术特点

捕风一号卫星是中国首次实现基于星载导航卫星反射信号测量(global navigation satellite system-reflection,GNSS-R)技术的气象卫星,采用新型L波段海面风场信息探测技术,在风场测量、海面飓风风速反演等方面为国家气象、防灾减灾等行业提供服务.从系统设计角度介绍了捕风一号卫星的总...     

临近空间浮空器区域驻留控制策略研究

为了实现临近空间浮空器区域驻留飞行,基于对热环境的分析,建立了带有副气囊高空气球的空气动力学与热力学耦合动力学模型。基于准零风层特殊风场,设计了临近空间浮空器区域驻留飞行控制策略,通过副气囊调节飞行高度,利用准零风层上下纬向风方向相反的特点实现东西方向控制,用螺旋桨控制实现南北方向控制,并利用ECMWF风场数据进行了数值仿真。仿真结果表明,临近空间浮空器可以在纬度41°(N)~43°(N),经度86.5°(E)~87.1°(E)之间的区域范围内飞行7天,证明了利用准零风层风场实现临近空间浮空器区域驻留飞行的可行性。     

Cleft formation in pumpkin balloons

NASA’s development of a large payload, high altitude, long duration balloon, the Ultra Long Duration Balloon, centers on a pumpkin shape super-pressure design. Under certain circumstances, it has been observed that a pumpkin balloon may be unable to pressurize into the desired cyclically symmetric equilibrium configuration, settling into a distorted, undesired state instead. Success of the pumpkin balloon for NASA requires a thorough understanding of the phenomenon of multiple stable equilibria and developing of means for the quantitative assessment of design measures that prevent the occurrence of undesired equilibrium. In this paper, we will use the concept of stability to classify cyclically symmetric equilibrium states at full inflation and pressurization. Our mathematical model for a strained equilibrium balloon, when applied to a shape that mimics the Phase IV-A balloon of Flight 517, predicts instability at float. Launched in Spring 2003, this pumpkin balloon failed to deploy properly. Observations on pumpkin shape type super-pressure balloons that date back to the 1980s suggest that within a narrowly defined design class of pumpkin shape super-pressure balloons where individual designs are fully described by the number of gores n_g and by a single measure of the bulging gore shape, the designs tend to become more vulnerable with the growing number of gores and with the diminishing size of the bulge radius r_B Weight efficiency considerations favor a small bulge radius, while robust deployment into the desired cyclically symmetrical configuration becomes more likely with an increased bulge radius. In an effort to quantify this dependency, we will explore the stability of a family of balloon shapes parametrized by (n_g, r_B) which includes a design that is very similar, but not identical, to the balloon of Flight 517. In addition, we carry out a number of simulations that demonstrate other aspects related to multiple equilibria of pumpkin balloons.