光电导引的四轮移动机器人设计

全国大学生智能车竞赛要求设计一种能按要求快速稳定平移和转向的光电导引的四轮移动机器人系统。因此分别建立了前轮S-D5舵机转向模型和二阶后轮RS540电机驱动数学模型,设计了基于模糊控制的前轮转向算法、基于解析式控制器的智能自适应PID后轮驱动算法、赛道判别算法,改进了线性CCD采集图像处理算法,利用基于二值化的双向跳变沿检测法代替单向跳变沿检测并采用膨胀腐蚀算法滤除噪声。实际调试结果表明：所设计的机器人能快速稳定地沿赛道运动,验证了系统设计的可行性和算法的有效性。     

智能车竞赛中的运行稳定性探究

以追寻信标的智能车竞赛为例,探讨了智能车在运行过程保证稳定性的要素并提出了改进型处理方式.采用滤光片结合遮光板的CMOS摄像头,并对摄像头图像进行滤波,提高了图像识别稳定性;采用增量式PID算法和前馈-微分先行式PID算法分别控制舵机和电机,提高了姿态控制稳定性;采用线性CCD、红外对管、轻触开关、倾倒保护开关检测突发情况,并利用舵机、电机规避突发情况,提高了突发处理稳定性.     

属性嵌套计算网格智能算法实现车牌汉字精准识别的设计

设计了环境较差情况下高效精准、辨识汉字的智能车牌识别算法,通过引进属性嵌套计算网格实现了汉字高效辨识的车牌识别算法;算法应用结果表明:算法设计的网格密度与识别率是成正比的,采用的属性嵌套计算网格模型,显著地改进了字符的识别率;将属性计算网格算法与属性嵌套计算网格算法对比可知,采用属性嵌套计算网格算法识别率是98.7%,识别率明显较高;设计算法系统不仅实现了汉字识别的稳定、智能特性,同时表现了抵抗较强外界干扰的特性,这一研究对于智能化汉字识别有明显的借鉴价值。     

基于体感控制耦合深度相机的手势识别算法

针对当前手势识别算法易受光线变化、复杂场景等干扰,从而导致手势识别准确性下降的问题,定义了一种体感控制与深度相机的手势识别算法。所提出的手势识别方法结合了体感控制(Leap Motion)传感器和Kinect深度传感器,可以有效提高手势识别精度与鲁棒性。通过体感控制传感器提取指尖与手的质心距离、指尖与手掌平面的高度、指尖与手掌中心的角度,以及指尖在手参照系统中的3D位置;通过Kinect深度传感器来提取手指样本与手部中心的距离、手部轮廓的局部曲率、手部形状的连通区域以及距离特征之间的相似性;为了结合两种不同传感器数据的互补信息,摒弃冗余,通过采集的指尖3D位置,找到旋转平移参数,以最小化所有采集帧中指尖点的平均投影误差来定义一种联合校准方法,确定体感控制传感器和Kinect深度传感器的外部参数,完成两种传感器坐标转换;采用支持向量机(SVM)进行分类学习,完成手势识别任务。实验表明：相对于已有的手势识别算法,所提算法不仅在Jochen.Triesch手势数据库中具有更高的平均识别率,约为97%,而且在不同光线、不同肤色和背景的复杂环境下,其同样具有更高的准确率与稳健性。     

追寻信标的智能车最优导航策略

基于NXP嵌入式控制芯片的智能车,提出用于追寻信标的自主导航策略.采用基于连通域图像的扫描算法,对摄像头图像进行扫描与滤波,从而得出正确的发光信标位置;采用基于映射关系的畸形矫正算法,通过映射公式对发光信标的图像进行畸变矫正;采用线阵CCD摄像头与接近开关相结合的方法作为避障策略.经实验测试与竞赛检验,该导航策略具有较高的行驶效率以及较低的误判率.     

智能车转向系统的研究及设计

智能车的底层控制主要包括油门、刹车和转向三部分。转向部分主要以电子式助力转向系统(EPS)为基础进行设计。电子控制式电动助力转向系统具有较好的操纵性、安全性、轻便性以及节能性等优点。然而,传统汽车上应用的助力转向系统仅起到辅助作用,对于无人驾驶的智能车来说功率过小,无法实现智能车在静止或者低速行驶时的转向控制,并且智能车的转向控制策略也有所不同。通过选择合理的转向电机、合适的传感器,设计了一套适合智能车的转向系统。通过反复试验,该转向系统可以很好的实现智能车转向控制。     

多普勒加速度测量的数字相关鉴相算法

针对激光多普勒加速度测量系统信号信噪比较差的问题,提出了一种采用数字相关鉴相算法进行加速度解调的方法。使用数字相关鉴相算法计算激光多普勒加速度测量系统中两路干涉信号的相位差,再由相位差的变化率来计算目标加速度,从而实现运动物体加速度的连续测量。仿真结果表明:该算法在信噪比为20dB时,加速度测量的误差为0.135m/s~2,分辨率为7.3×10~(-3) m/s~2。搭建了激光多普勒加速度测量系统,对压电陶瓷振荡器的加速度进行测量,加速度的测量误差为0.13m/s~2。测量结果表明,该算法能够有效减少随机噪声的干扰,提高加速度的测量精度。     

基于支持向量机的图像飞机目标自动识别算法研究

为了能够快速、准确地识别飞机目标,文章给出了一种基于支持向量机的飞机目标自动识别方法;采用Touzi边缘提取,得到目标形状参数的几何特征,Hu不变矩等16个特征矢量作为SVM的训练样本,通过SVM训练得到飞机目标识别模型,从而完成飞机目标的自动识别;试验结果显示,该算法对不同尺度和模糊程度的飞机目标的识别度可达99%; 该算法减少了样本训练时间,在提高识别准确率的同时降低了算法的复杂度,具有识别度高、识别速度快的特点,可用于飞机目标的快速识别。     

试飞机载测试系统一体化验证平台的设计与实现

为提高智能车对多车道的实际道路车辆行驶环境的适应性,提出了一种基于三车道模型的车辆检测方法。方法在预处理的基础上利用极角及位置约束的Hough变换得到可能的车道线信息并利用消失点对车道线进行筛选;利用三车道四线模型对车道线进行匹配;对于每条车道,分别利用车辆灰度信息对车道线内车辆进行识别,并利用视频的连贯性对车辆识别结果进行修正并跟踪车辆。该算法通过对车道线的二次筛选,提高了三车道模型的准确率,进一步提高了对于不同车道车辆识别的正确率。实验结果表明,在结构化道路上,对于不同路况,算法均具有较好的实时性和鲁棒性。     

基于改进的自适应回归时序模型故障诊断

汽车变速箱的故障诊断工作比较复杂,由于传统的诊断方法已不能满足复杂的故障现象, 文中提出了一种基于改进的自适应回归时序模型故障诊断方法;方法采用了基于时间序列故障诊断技术,首先测取工作环境下的振动信号,然后建立被诊断对象的时间序列数学模型,最后用信息距离判别法诊断出故障类型,提高了诊断效率;最后在变速箱进行了实验研究;选用型号为621B40型ICP加速度传感器测取变速箱的振动信号,通过设置模型参数(n,m)来模拟故障检测,实验分析表明,提出的算法可以有效地识别变速箱系统中不同严重程度的故障,且与传统的故障诊断算法相比,提出的算法对提高识别率和降低计算复杂度都有着明显的优势。     

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.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

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.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

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.