微小型球形飞行器飞行控制系统设计

根据微小型球形飞行器的结构特点和工作原理,设计了一套基于ARM Cortex-M3 STM32F103RBT6微控制器的飞行控制系统,进行了主要模块的功能设计与性能分析,给出了研究结论与选型依据,还设计并完成了姿态传感器两轴转台实验和飞行器室内飞行试验。测试结果表明,该控制系统的姿态传感器姿态测量精度高,能够为飞行控制提供姿态参考信息;飞行器能够圆满实现空中悬停、低空机动等飞行动作,且空中飞行姿态稳定、实时、可靠。该飞行控制系统功能可靠、性能稳定,能够较好地满足微小型球形飞行器的飞行控制要求,具有一定的实用性与扩展性。     

多旋翼无人机位置控制系统设计

摘要：为解决小型无人机位置控制系统成本高、控制精度低以及控制性能不稳定等缺点,以自主研发的多旋翼无人植保机作为研究对象来设计位置控制器。设计过程中,飞行器的位置建模误差,模型参数变化、GPS定位精度以及外部扰动（如风速）成为有待解决的难题。为解决上述问题,首先设计了卡尔曼滤波器对反馈所得速度和位置信息进行滤波,并采用参考模型滑模控制理论（Model Reference Sliding Mode Control,MRSMC）设计位置控制器,提高控制系统的鲁棒性。为了验证位置控制器的性能,进行了户外飞行实验,实验结果表明,无论是在悬停还是目标点追踪情况下,所设计控制系统都具有良好的跟踪性与鲁棒性     

一种自适应煤矿井下环境的加权质心节点定位算法

为提高煤矿井下无线传感器网络节点定位精度,提出了一种自适应煤矿井下工况环境的加权质心节点定位算法;在信标节点双链式部署结构的基础上,首先利用未知节点周围RSSI信号强度最大的信标节点之间的位置信息和信标节点的平均RSSI值自适应地估计环境参数,再应用无线信号强度衰减模型计算未知节点到信标节点的距离,最后采用加权质心定位算法的平均值确定最终的节点位置坐标;仿真实验结果表明,所提出方法的平均定位误差为0.94 m,有效降低了环境因素及RSSI的随机性对定位精度的影响,可用于煤矿井下无线传感器网络节点实时定位系统中。     

基于GPS与GPRS的远程健康监护系统的设计

为实现对存在健康隐患人群的位置及生命特征信息远程监测,设计了基于GPS(Global Positioning System)与GPRS(General Packet Radio Service)的远程健康监护系统,系统由监测节点、数据处理服务平台、各监控终端等组成。以STM32为主处理器完成对监测节点的软、硬件设计,根据生命特征传感器采集的信号特点设计驱动电路,在GPS与GPRS网络的基础上,设计监测节点软件,完成了对人体心电、温度及位置信息的实时采集和转发。数据处理服务平台负责信息存储、分析和发布,各监控终端也可以通过数据处理服务平台查询被监测者的位置与生命特征信息。测试结果表明,系统能够实现相应功能,满足应用需求。     

采用AVR控制器的GPS授时与定位装置的设计与制作

本文以解析GPS的时间信息和位置信息为目标,通过使用嵌入式GPS模块和AVR控制器,设计和制作GPS授时与定位装置,实现时间信息和位置信息的解析和显示等问题。本文首先给出了基于GPS模块和AVR控制器的授时与定位装置的整体构架,然后对各个部分的 硬件进行详细设计,给出了硬件设计电路和软件设计框图。最后对所设计的基于GPS模块和AVR控制器的授时与定位装置进行实物制作,证明了设计内容的正确性和可行性,具有一定的实际应用价值。     

基于自抗扰技术的四旋翼飞行器视觉伺服控制器设计

基于自抗扰控制技术的四旋翼飞行器视觉伺服控制器克服了惯性传感器无法获取位置信息的缺点,提高了飞行器的灵活性,能够胜任更复杂的任务;文章主要针对基于四旋翼无人飞行器的视觉伺服控制技术问题展开相关研究;选用基于HSV颜色空间的颜色特征提取的方法实现目标跟踪,再通过三角形法则确定飞行器与目标在世界坐标下的相对位置,最后引入自抗扰控制技术设计了水平位置控制器与姿态控制器;通过实验结果分析,文章设计的飞行器视觉伺服控制器可以准确地跟踪目标并实施高精度定位,并且控制系统鲁棒性强,跟踪误差小,能够有效地完成视觉伺服控制任务。     

四旋翼飞行器的自主巡航控制系统设计

针对四旋翼飞行器为六自由度,四控制量的欠驱动系统,将四旋翼飞行控制系统简化为姿态子系统和位置子系统,采用MIMU(微惯性测量组合)及GPS融合的导航方法,采用PID飞行控制策略,实现了利用地面站软件加载数字地图并进行自主巡航。     

基于BDS/GPS和百度地图的现代有轨电车监控系统的设计

为实现对现代有轨电车车辆的位置及运行状态进行实时监控,设计了一个基于BDS/GPS和百度地图的现代有轨电车监控系统;定位终端以具有我国自主知识产权的BDS/GPS双模定位模块为主,RFID系统作为辅助定位手段;数据通过HTTP的GET方法提交至服务器,由服务器端的PHP页面自动处理后存储到MySQL数据库,中心管理平台显示页面调用百度地图API,将数据显示在百度地图上;最终该系统可以实时获取并存储列车的位置坐标、速度、时间等信息,并在百度地图上以点、线和图表的形式显示出车辆的坐标和运行轨迹等;测试结果表明,该系统运行稳定,定位精度高,获取数据准确、时延小,能够满足应用需求。     

基于单目视觉的机械臂目标定位系统设计

在筒子纱染色的工业生产中,获取机械臂及纱杆锁扣的相对位置实现机械臂的精确定位和抓取目标是染色过程的关键技术。设计了基于单目视觉的机械臂目标定位及光学测量系统,通过单目光学成像的方式实时获取锁扣目标的图像,结合图像分析算法解算出目标空间位置以及目标与机械臂的相对位置。利用OPC通讯技术,将目标的空间位置信息传输给机械臂控制模块并控制机械臂的运动实现目标的抓取。通过现场实验,机械臂定位系统的定位误差在2mm范围内。     

北斗定位系统在飞行试验中的应用研究

鉴于美国GPS种种技术限制以及我国自主研发北斗系统的技术日趋成熟,在国防建设中使用北斗系统已迫在眉睫。本文从四个方面介绍了北斗系统在飞行试验中的应用,包括短报文通信应用,单点定位、事后差分应用以及实时差分应用。文章对飞行试验中的北斗数据及GPS数据结果进行比对,验证了北斗数据的准确性。最后介绍了北斗定位系统未来在国防、民用、飞行试验中的技术应用展望。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.     

Fiber Modal Index Measurements Based on Fiber Gratings

A novel method based on fiber gratings for measuring the effective indices of fiber modes is proposed. The effective index difference between the core mode and a cladding mode was obtained by analyzing the interference fringe of a pair of cascaded long-period fiber gratings. In order to extract the core mode index from the measured index difference, an index matching oil immersion method is proposed. By analyzing the interaction between the cladding mode and the oil applied on the cladding surface, the mode order and the effective index of the involved cladding mode might be calculated. Experimental results about the interference fringe shifts induced by the oil index and the oil-applied length are also presented.     

Optical Pulse Compression Schemes That Use Nonlinear Bragg Gratings

Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains.