在非定常气动力作用下弹性飞行器的动稳定性及主动控制

首先导出了在非定常气动力作用下的弹性飞行器纵向运动方程。而后就简化的非定常气动力数学模型提出了分析气动弹性对飞行器稳定性影响的方法。并从有效抑制飞行器的弹性振动角度研究主动反馈控制、操纵面及陀螺位置合适选择的最优综合设计问题。     

航天器轨迹优化的通用数值方法

给出了航天器轨迹优化的一种通用数值仿真方法，该方法是由静态参数优化和动态参数优化构成，其中，静态参数优化采用可变误差多面体算法，动态参数优化采用基于最优控制理论的共轭梯度方法。     

无人机电磁弹射技术研究

与现有的各种无人机发射方式相比,无人机电磁弹射方式具有更多的优点,能更好地提高无人机发射效率。通过原理性分析以及导轨起飞运动学分析,对无人机电磁弹射技术进行了可行性研究。高功率脉冲电源系统释放强直电流后,电流经导轨与电枢形成回路,在回路间产生强磁场,无人机受电磁推力作用沿导轨高速运动。最后通过实例的计算数据比较,确定无人机电磁弹射技术是可行的且优点明显。     

多无人机辅助定位信标的区域导航定位算法

针对卫星导航系统在受到干扰不可用的情况,研究了多无人机（UAV）辅助的区域导航定位算法。以无人机作为空基信号播发平台,向地面用户广播其位置信息及同步时钟信号,地面用户通过接收无人机位置及与无人机的距离计算出其实时位置。以地面战车为例,为解决伪距单点定位算法中的矩阵不可逆问题,消除地面用户接收机的钟差,基于列文伯格-马夸尔特（LM）算法,提出一种地面用户的定位解算模型,同时,为提高一般最小二乘算法的计算精度,提出了两步最小二乘定位算法。在分析2种算法静态定位精度的基础上,设计了基于车载惯性传感器和无人机辅助定位信息的组合导航实现算法,实现了对战车的连续定位。仿真结果表明,在GNSS拒止环境下,利用无人机播发的定位信标信号并结合地面用户战车自带的惯性导航系统,可以实现对地面用户的可靠连续定位,满足一定区域范围内用户的导航定位需求。     

三维捷联磁传感器误差分析及补偿

磁传感器在导航系统中的应用日益广泛。在车载导航系统工作环境中,外界干扰磁场复杂,严重影响了磁航向测量的精度。因此对磁航向进行适当的罗差补偿是提高磁航向测量精度的有效途径。文中介绍了用磁传感器进行磁航向测量的原理,分析了由于磁场矢量叠加产生的罗差,提出了基于傅立叶级数的罗差模型和补偿方法。工程实践表明,上述方法的使用收到了较好的效果。     

磁悬浮助推发射气动力分析及风洞试验

通过分析磁悬浮助推发射装置的空气动力特征, 提出了其气动外形设计的合理原则.分析了磁悬浮橇体和支撑分离机构的气动外形方案, 并确定了优化的气动外形设计参数值.考虑地面效应模拟的同时, 在FD-06风洞中进行了缩比模型试验.结果表明, 升阻力系数随着马赫数或运载器迎角的增大而增大, 装置有上仰的趋势, 迎角为0°时, 阻力系数较小, 各系数的变化也较小.      

Bipolar nickel-metal hydride battery for hybrid vehicles

Hybrid electric vehicles are receiving increased interest as an approach to decrease vehicle pollution, dependence, and consumption of liquid petroleum and meet forthcoming Government vehicle emission standards. A number of schemes are under consideration (heat engine battery, fuel cell battery, peaking battery, inner-city battery, etc.). The success of any of the approaches will be dependent on battery capabilities, i.e., power, density, life, and cost. The nickel-metal hydride system appears to be the most promising of the candidate battery chemistries. Preliminary designs and analysis have been prepared and are presented for various configurations. Initial performance characterization tests are presented. It is concluded that a bipolar package arrangement for the Ni-MH chemistry appears most suited for the hybrid vehicle application considered     

Intelligent UUVs: Some issues on ROV dynamic positioning

Intelligent unmanned underwater vehicles (UUVs) fall under two main group categories: the remotely operated vehicles (ROVs), which are characterized by remote operation and presence of a tether cable; and the autonomous underwater vehicles (AUVs), which are characterized by their autonomous behavior and absence of a tether cable. One fundamental issue of the UUV design is the dynamic position control system. This system plays a crucial role together with the sensor architecture in the degree of system autonomy that can be achieved. This paper is concerned with a few issues when dynamically positioning remotely operated underwater vehicles (ROVs). By restricting the operating regime of ROVs to slow velocity requirements the paper investigates the implementation of a few decentralized control strategies and compare their performance measures, which are assessed by simulating a nonlinear ROV system model for each control strategy. Issues concerning input tracking, disturbance rejection, and plant variations are discussed. The evaluations consider the use of linear PID feedback and feedforward variants, and a robust nonlinear control strategies applied to a full order, fully coupled, and nonlinear vehicle model. These evaluations consider a vehicle undertaking standard mission activities where the tether cable dynamics, with load estimates obtained from a lumped mass cable model, and the vehicle actuator system are present. The paper shows that much of the performance deterioration may be attributed mainly due to cable inertia. The authors also verify that the nonlinear robust control strategy does not necessarily allow for better performance over the linear feedback control strategies implemented when vehicle motions are confined to slow velocity profiles. These and other partial results will aid the design of the control system for an underwater vehicle currently under construction     

风—车—桥系统车辆风荷载突变效应风洞试验研究

侧向风作用下,车辆通过桥塔或双车交会时车辆所受风荷载会发生突变,这将影响行车的安全性和舒适性。基于自主研制的移动车辆模型风洞试验系统,针对轨道交通车辆和公路交通车辆,分别采用三车模型和单车模型测试了车辆通过桥塔和双车交会时车辆风荷载的突变过程,讨论了风速、车速、车辆所处轨道位置及车辆类型等因素对车辆气动力系数的影响。研究表明车辆运行于桥塔区域及双车交会时,车辆三分力系数均有不同程度的突变趋势;车辆运动引起的列车风使车辆阻力系数的突变程度减弱,使桥塔遮风效应的影响区域变长;公路交通车辆风荷载突变效应较轨道交通车辆的要明显;双车交会时,背风侧车辆风荷载急剧减小,迎风侧车辆三分力系数变化较平稳。     

Impact of mission requirements and constraints on conceptual launch vehicle design

The objective of this paper is to analyse the impact of mission requirements and constraints on both the optimum vehicle design and the effects on flight path selection for two types of reusable two-stage-to-orbit launch vehicles. The first vehicle type considered provides horizontal take-off and landing capabilities and is intended to be propelled by an airbreathing propulsion system during stage 1 flight. The second vehicle type assumes a vertical launch and is accelerated by a rocket propulsion system during the booster stage ascent flight. The analysis employs a design tool for simultaneous system and mission optimization. It consists of a CAD-based preliminary vehicle design tool, aerodynamic and aerothermodynamic calculation software, flight simulation programs, and a two-level decomposition optimization algorithm enabling simultaneous system and flight optimization. The results to be presented show that the cruise flight requirement for an European launched mission of the airbreathing vehicle results in a loss of 60 % payload mass as compared to a mere accelerated ascent for a near equatorial mission into the same target orbit assuming constant take-off mass. The strong dependencies of mission requirements on both the optimal vehicle design and the ascent performance are determined for the rocket-powered vehicle type by varying the inclination and altitude of the target orbit.     

Design and Application of an Adaptive Tracking Filter Control System

The design of an adaptive tracking filter control system and its application to large flexible booster vehicles is described. The problem of elastic vehicle stability is considered along with its solution by conventional and adaptive techniques. The improvement in vehicle stability, which may be achieved with the adaptive tracking filter technique as compared to conventional techniques, is shown. The control system evolved uses two adaptive tracking filters to phase stabilize the first and second bending modes, in addition to conventional compensation techniques. The application of this adaptive technique to a vehicle in which the modal frequencies are in close proximity (<2.5 percent separation) is discussed. The mechanization of the adaptive control system involves the selection of design techniques and components that are electrically and physically compatible with the intended airborne application. The development of a suitable frequency tracking technique and tracking filter is described, in addition to the electronic and mechanical design of the adaptive control system prototype.     

高超声速飞行器模型不确定性影响分析

吸气式高超声速飞行器具有严重的弹性机体和推进系统耦合的典型特征,其分析模型存在较大的不确定性,标称系统和真实系统之间存在偏差,因此研究不确定性对稳定性的影响对于控制器设计具有重要意义。针对典型的乘波体构型高超声速飞行器,建立了气动/结构/推进相互耦合的动力学模型,总结了建模中的不确定因素并将其以加性不确定模型的形式表示出来。以不确定性矩阵的最大奇异值为边界模型,以不确定性矩阵的H∞范数来表示不确定性因素对稳定性影响的大小,并通过不确定性矩阵的边界曲线分析不确定因素对模态特性的影响。结果表明,惯性因素的不确定性对稳定性的影响最大,而且其对飞行器的短周期模态和弹性模态均有较大的影响;同时,对于这一类飞行器的控制器设计必须考虑飞行器的弹性自由度。     

Magnetic Signal Processing & Analysis for Airfield Traffic Surveillance

This paper presents an innovative system for airport surface surveillance based on a novel magnetic sensing technology. Ferromagnetic objects such as vehicle motors, aircraft engines, and landing gears are detected through their deformation of the Earth's magnetic field. Tests have shown that although the local changes of the Earth's magnetic field are extremely small, the proposed sensing technology is able to detect them reliably. The primary objective of the proposed approach is to provide a complementary surveillance system for existing and future Advanced Surface Movement Guidance and Control Systems (A-SMGCS) at large airports or a cost-effective surveillance solution for monitoring critical areas at medium and small airports. Unaffected by weather conditions, interference and shadowing effects, the system provides reliable position, velocity, and direction information without requiring any equipment in aircraft or ground vehicles. The outcome of a comprehensive market analysis is discussed and test results under real life conditions at two airports are evaluated analytically.     

钝尾车辆被动通风减阻方法的数值模拟

为了减小车辆阻力,提高燃油利用率,提出了一种钝尾车辆的被动通风减阻方法,即在钝尾车辆的下部适当部位开一个适当尺寸的通孔,以便为均衡车体前后的压力提供一个通道,当车辆行驶时,使得车体前部的"高压"气体能够通过这个孔流到相对"低压"的车体底部区域,从而减少车辆的压差阻力以降低燃油消耗。并对其在10、15、20、25、30及35m/s的各种通常的行驶速度下进行了3-D数值模拟,结果证明这种减阻方法的十分有效。     

Enhanced space integrated GPS/INS (SIGI)

Safe, reliable, and low cost space-based navigation is being provided with embedded INS/GPS systems such as the space integrated GPS/INS (SIGI). The SIGI is being used for various space vehicle applications such as launch vehicles, orbital vehicles, and re-entry vehicles. This paper describes current space vehicle navigation capabilities. The SIGI is being enhanced to provide additions to these existing capabilities with such items as higher processing and a commercial-off-the-shelf operating system. This will allow hosting of various software applications such as advanced navigation functions, flight control, guidance and vehicle management algorithms. The SIGI can host redundancy management functions by incorporating a cross channel data link card (CCDL) using a high speed firewire bus. The SIGI can then be used as a redundancy management platform which has application to current space vehicle avionics topologies incorporating distributed processing architectures     

Probabilistic transient thermal analysis of an atmospheric reentry vehicle structure

Thermal analysis plays an important role in the structural design of atmospheric reentry vehicles, which are subjected to severe aerodynamic heating. It is sometimes difficult to assess the design safety margin because of uncertainties in the predicted heat flux and the material properties used in the thermal analyses. However, probabilistic techniques allow the effects of uncertainties to be analyzed, and the present study demonstrates the probabilistic thermal analysis of the PARTT reentry vehicle using the Monte Carlo technique to investigate the probabilistic temperature responses. The temperature responses were found to depend significantly on time and location, and reliability was predicted at all locations. The peak temperature of the vehicle's main structure was found to be strongly correlated with heat shield temperature, and analysis of the contributions of random parameters showed that heat flux and heat shield emissivity significantly affect the peak temperature. These results indicate that the thermal design of the heat shield shell is very important for the whole structure. It is expected that such information will provide good insight for the design of a reentry vehicle's structure.     

Recent developments of electric vehicles and their propulsionsystems

Major recent electric vehicle (EV) programs in North America, Europe, and Japan are reviewed. The developments discussed include electric vehicles for fleet operation and electric passenger cars for urban transit. All major auto makers have had their own concept electric vehicle programs, targeted at commercial production in the late 1990s. It Is noted that, with different objectives for various electric vehicles, considerations such as cost, reliability, efficiency, maintenance, durability, weight, size, and noise level should be compromised for the propulsion system design. Consequently, DC motor drives, induction motor drives, and permanent magnet brushless DC motor drives will continually be used for EV propulsion systems in the future, with DC drives being gradually replaced by AC drives. The rapid advances in power semiconductor devices and microprocessors have made it possible to build reliable and cost-effective AC drive systems     

机场跑道摩擦系数测试试验数据分析

介绍了自行研制的机场跑道摩擦系数测试车的测量原理与系统组成。以在车体后桥部位安装的专用测量轮为测试栽体，测量该测量轮所受的垂直正压力和水平摩擦力，计算跑道的摩擦系数。采用对比试验方法．进行了本车与瑞典Safegate跑道摩擦系数测试车的测量试验，并对本车和瑞典Safegate测试车的测量误差和测量数据的稳定性、重复性、相关性等进行了统计分析。     

高精度陆用惯导零速修正技术研究

零速修正技术是提高陆用惯导定位精度的一项有效手段。在周期性停车过程中,惯导系统除了将速度误差清零外,还能将由陀螺漂移、平台误差角等因素引起的位置误差进行补偿。本文采用离散线性卡尔曼滤波方法,通过连续三个停车时刻的速度误差构造观测向量,对惯导速度误差、加速度误差和陀螺漂移进行估计,进而补偿位置误差。车载试验表明,该零速修正方法位置精度高,且停车时间短,能够满足地面车快速响应的要求。