“海狼”导弹的惯性测量装置

《航讯》1985年3月15日报道:英国宇航公司动力集团精密产品部接受一项价值一百万英镑的初始合同,以着手研制(舰艇自卫用的)垂直发射型“海狼”反导弹导弹上用的捷联式惯性测量装置(IMU)。该装置能提供导弹俯仰、偏航、滚动的角增量和角速率,以及沿导弹轴的加速度和速度增量的数字和模拟信号。垂直发射型“海狼”无作战盲区,发射速率高,能战胜饱和攻击,并扩大了拦截范围。     

基于nRF24L01的无线手持终端的设计与实现

介绍了一种基于nRF24L01无线射频模块的手持终端的的解决方案,阐述了工作原理及其软硬件设计。该手持终端的MCU采用STM32;可显示MX2100气体侦检仪绝大部分的操作界面,并可将界面的操作信息传输至上位机,也可收到上位机传送的指定气体浓度等信;具有本地存储功能。系统可用于消防员的日常模拟训练。     

基于Simulink模型的捷联算法仿真平台研究

分析了捷联系统基于Simulink模型的姿态、速度和位置积分的基本方程。建立了仿真模型，给出了组成模块和算法框图。研究了采样与静差补偿，以及四元数、姿态、住置和速度更新的算法。构造的算法仿真通用平台，其输入可为实际系统的惯性测量元件(IMU)在线、离线数据的全部或部分，或自行构造的载体在某种运动轨迹下IMU的输出。仿真结果表明，利用Simulink多种直观的位置输出，可更有效地分析捷联系统，或对多种IMU的捷联导航特性进行比较验证。     

飞行试验遥测地面站(FTTGS)方案和QUAD7系统(下)

三、QUAD7系统的硬件如前所述,QUAD7系统的硬件包括建立/控制、采集、处理、模拟、存储I/O和时间处理/合并六个部分。建立/控制部分包括SCM模块(系统控制模块)、DAT模块(数据库管理/报警门限模块、VIA模块(VME信息适配器或VI总线适配器模块和可经以太网连至系统的各X终端和彩色图形工作站。     

大视场星光修正惯性导航半实物仿真系统设计

针对飞行实验成本高、难度大的问题,设计并实现了一种大视场星光修正惯性导航系统的半实物仿真试验系统。该系统采用轨迹发生器模拟生成飞行过程中导航传感器数据,利用真实星敏感器与IMU的静态输出获得器件误差,结合时间软同步完成信息采集,通过组合导航模块实现模拟飞行过程的组合导航解算。实验结果表明,该系统具有较强的灵活性和通用性,可在地面验证星光修正惯性导航算法性能,具有一定的工程应用价值。     

一种快速精确的捷联惯性导航系统静基座自主对准新方法研究

通过对捷联惯性导航系统(SINS)静基座初始对准物理特性的深入分析,针对传统静基座初始对准方法对方位角和陀螺漂移可观测度低的不足,提出了一种基于惯性测量单元(IMU)信息的SINS静基座自主对准方法,该方法不需要进行SINS力学编排,而是充分利用IMU输出的角速度和比力信息。文中给出了静基座粗对准算法,推导了静基座精对准的动力学模型,并对该模型进行了可观测性分析,最后采用改进的Sage-Husa自适应卡尔曼滤波器进行SINS静基座初始对准仿真计算。数字仿真结果表明：该方法具有对准精度高、对准时间短、自主性强、计算量小、易于工程实现等特点。     

采用混合执行机构的卫星快速机动技术研究

研究了一种采用混合执行机构的姿态单轴快速机动的控制方法.设计了由平行构型单框架控制力矩陀螺(SGCMG)和飞轮组成的混合执行机构配置方案.综合姿态机动规划,设计了前馈和反馈相结合的姿态机动控制律,并通过执行机构动力学分析给出了操纵律.仿真结果表明:采用平行构型SGCMGs和飞轮的混合执行机构模式,可实现姿态三轴高精度稳定控制和侧摆快速机动的任务要求.     

微小卫星三轴磁强计测量误差校正方法

微小卫星在轨进行磁阻尼和磁定姿时,要利用三轴磁强计测量磁场强度,由温度变化引起的测量误差大大降低了测量精度,因而要对测量误差进行校正。文章提出一种校正方法,通过分析三轴磁强计的测量误差建立误差校正模型,利用磁环境模拟器的磁场强度、温度及三轴磁强计的输出电压,对三轴磁强计进行温度建模,利用伪逆法求得三轴磁强计的标定系数,再利用标定系数和零位电压对温度进行线性拟合,可实现三轴磁强计测量的温度补偿。在温度可变的磁环境模拟器中采用校正方法对三轴磁强计进行测试,结果显示该校正方法具有很好的实用性。     

基于IMU辅助的高动态GPS信号捕获算法

高动态环境存在较大的多普勒频移,传统的GPS信号捕获方法捕获时间较长。为了快速捕获到信号,提出将惯性测量单元(InertialMeasurementUnit,IMU)辅助与快速傅里叶变换(FFT)相结合的快速捕获算法。该算法通过外部IMU的位置、速度辅助,预先估算高动态载体产生的多普勒频移,缩小频率搜索范围;利用二维FFT方法同时搜索码相位和多普勒频率,降低计算复杂度,加快捕获速度。仿真结果表明该算法可以显著减少捕获时间,提高捕获性能。     

MPEG-4视频DCT量化模块的FPGA实现

介绍了一种采用FPGA技术实现MPEG-4 ASP级视频DCT量化模块的设计方案。该模块包括二维DCT／IDCT、量化／反量化和帧内直流／交流(DC／AC)预测。用VHDL进行描述并通过模拟试验表明,该模块可在880个时钟周期内处理完一个宏块的数据,工作频率达到40MHZ。文章采用全硬件实现方法,提出了各模块的硬件电路结构设计,减少了电路规模。     

Between a celestial body and a spacecraft: Making the space elevator a success

The space elevator will operate in near-Earth space, under the attraction of the Earth, the Moon and the Sun. It will have to avoid collisions with active satellites, with space debris and with meteoroids, not counting other minor adverse phenomena. The exceedingly long cable cannot be a passive and limp body. It must be an active part of the elevator, withstanding lunisolar and other perturbations threatening its stability. The cable must have sensors and thrusters at appropriate locations along the cable. Sensors would serve for detection of objects on a collision course and thrusters for station-keeping and for initiating evasive manoeuvres. Adaptive control must be used for that purpose. Extensive series of numerical simulations will have to be performed to ascertain that the elevator is stable and that possible oscillations do not interfere with the main function of the elevator.     

Motion of a Planet with a Complex Structure

The motion of a planet consisting of a mantle and a core (solid bodies) connected by a viscoelastic layer and interacting with each other and an external point mass by the law of gravitation is considered. The mutual motions of the core and mantle are investigated assuming that the centers of mass of the planet and external point mass moves along undisturbed Keplerian orbits around the common center of mass of the system. The planetary core and mantle have an axial symmetry and different principal moments of inertia, which leads to a displacement of the center of mantle relative to the center of core and to their mutual rotations. The results obtained on the basis of averaged equations are illustrated by the example of the Earth–Moon system.     

Equilibrium positions of a weight on a cable fixed to a dumbbell-shaped space station moving along a circular geocentric orbit

The motion of a space object in the gravitational field of the Earth is considered. The object consists of an extended space station and a weight, which is free to move along the cable fixed to the ends of the station. It is assumed that the station is composed of two masses coupled by a weightless rod, while the cable is weightless and non-stretched. The equations of motion of such a system are derived for the case when the motion proceeds in a single plane, while the center of mass of the system moves along a circular geocentric orbit. The conditions of the cable tension (conditions of being on tie) are derived. The phase portrait of the weight motion along the cable is constructed when the station is oriented to the attracting center or is perpendicular to this position. The possibility to leave the tie in this case is analyzed. Equilibrium configurations of the system are found, i.e., such motions of the object under consideration at which the weight does not change its position relative to the station. Lyapunov stability of such configurations is analyzed for two situations: when the station is composed of equal masses and when masses at the ends of the station are different. In particular, for the case of different masses it is established that there exist such positions of equilibrium at which the dumbbell is located at an angle to the direction to the attracting center. In some cases these positions can be stabilized (if the weight is fixed on the cable).     

拆掉阻挡思维的墙——从航天员教员到模拟航天员的跨界选择

当凭借影片《国王的演讲》获得第83届奥斯卡金像奖最佳男主角的科林·弗斯（ColinFirth）,在国际顶级生物学学术期刊《Cell》的子期刊《CurrentBiology》上发表了一篇极为专业的科研论文时,全世界一片哗然,为之震惊!当电影《泰坦尼克号》导演、年届57岁的卡梅隆驾驶单人深潜器下潜至马里亚纳海沟海渊底部的时候,我们看到了一个雄心勃勃的跨界玩家。为什么时下如此多的人开始拆掉阻挡思维的墙？因为界外的世界很精彩!     

Navigation Solution to Maneuver a Spacecraft Relative to a Sphere Centered on a Cooperative Satellite

A differential correction algorithm is presented to deliver an impulsive maneuver to a satellite to place it within a sphere, with a user defined radius, centered around a non-maneuvering satellite within a constrained time. The differential correction algorithm develops and utilizes the State Transition Matrix along with the Equations of Motion and multiple satellite?s state information to determine the optimum trajectory to achieve the desired results. The results from the differential correction algorithm are very accurate for prograde orbits, as presented. The results allow for orbit design trade-offs, including satellites? initial inclinations, semi-major axes, as well as the ballistic coefficients. The results also provide an empirical method to determine the optimum ΔV$\mathrm{\Delta }V$ solution for the provided problem. Understanding that the minimum fuel solution lies with a semi-major axis ratio of 1, a very accurate empirical approximation is presented for semi-major axis ratio values less than and greater than 1. This work ultimately provides the generalized framework for applying the algorithm to a unique user defined maneuvering spacecraft scenario.     

Force on a coil moving above a grid structure

The force on a coil moving with a high-speed parallel to a conducting grid consisting of parallel tubes is investigated. The coil performs a rebound motion or an oscillatory heave motion when pressed toward the grid by reactive on-board engines. The coil is approximated by two parallel wires moving parallel to the grid tubes. The corresponding electrodynamic problem is two dimensional and is solved by expansions in terms of Bessel functions. Expressions are derived for the lift and drag force as well as the heat generated in the tubes in the limit of strong skin effect. The dependence on the grid spacing is analysed in the approximation of no mutual inductance between the tubes. Two specific applications are a shunt deflecting the coil, and a funnel leading to multiple reflection. Finally, the varying magnetic flux threading the coil is considered and the thermal load of the coil is estimated.     

On a distorted flame front as a hydrodynamic discontinuity

The radius of curvature of a steady distorted flame often turns out to be considerably larger than the width of the thermal structure of the flame. Thus, even under finite deformations of the flame, its structure remains quasi-one-dimensional. This property enables the propagation velocity of a distorted flame front (relative to the gas) to be determined explicitly as a function of the hydrodynamic field and the physico-chemical parameters of the gaseous mixture. With the aid of this relationship one can try to determine the shape of the front in a model which is external with respect to the flame structure and treats the flame as a density jump in an ideal incompressible fluid. As applications, we consider (1) the structure of a Bunsen cone, (2) the extinction of a flame in a divergent flow and (3) the propagation velocity of a corrugated flame.     

Optimal Control of a Programmed Turn of a Spacecraft

A problem of optimal turn of a spacecraft is considered. The time of turn is minimized, as well as the functional having a meaning of the propellant consumption. An analytical solution to the problem stated is derived. It is demonstrated that the solution optimal in this sense belongs to a class of two-impulse controls, under which a spacecraft executes the turn along the trajectory of its free motion. The solution obtained in this paper differs from earlier available solutions considerably. The estimations of the propellant consumption for a realization of the programmed turn are made.     

Peristaltic transport of a viscoelastic fluid in a channel

This paper is devoted to the study of the peristaltic transport of viscoelastic non-Newtonian fluids with fractional Maxwell model in a channel. Approximate analytical solutions have been constructed using Adomian decomposition method under the assumption of long wave boundary layer type approximation and low Reynolds number. The effects of relaxation time, fractional parameters and amplitude on the pressure difference and friction force along one wavelength are received and analyzed. The study is limited to one way coupling model with forward effect of the fluid on the peristaltic wall. It is evident from the result that pressure diminishes with increase in relaxation time and the effects of both fractional parameters on pressure are opposite to each other. The influences of these parameters on friction force are opposite to that of pressure.