基于光栅投影和点云体积计算的过度包装检测系统

为了实现商品过度包装的无接触检测,设计了一种基于光栅投影的商品过度包装检测系统。首先利用投影仪和两个高分辨率摄像头,实现物体三维点云的获取,再提出物体点云的包围盒获取算法,计算物体的包围盒体积及三维点云体积,最后根据容积率和空隙率,检测商品包装是否过度。实验结果表明,系统能有效基于点云形状生成包围盒,点云体积计算准确度能达到95％,耗时比广泛使用的Poisson方法明显减少。     

应用于移动平台的器官柔性形变仿真方法

研究了应用于移动平台的器官柔性形变仿真方法。提出了面向移动平台的碰撞检测方法,通过模型的外层包围盒迅速剔除场景中未发生碰撞的情况,进而对模型的几何面元进行相交检测,从而实现对器官的碰撞检测。研究了应用于虚拟器官的质点-弹簧模型,通过对形变区域的控制降低形变的计算量,通过对虚拟器械的运动控制避免形变过程中虚拟器官发生穿透或者脱离器械的现象。实验结果表明,器官柔性形变仿真与交互方法计算速度快、交互过程自然,可应用于移动平台的虚拟手术仿真系统中。     

增强现实系统虚实亮度评价方法研究

在增强现实系统中,虚拟物体与真实环境之间具有相匹配的亮度关系,会使虚实融合达到逼真的效果。为了获得虚实物体的亮度匹配,根据图像亮度处理的原理,对增强现实系统的虚实环境提出了整体和局部两种亮度评价算法,并对新型光学透视式头盔显示器的亮度匹配算法进行了改进,提高了系统效率。实验结果表明,对在不同情况下的真实环境和虚拟物体来说,这两种算法各有其优点,调节后的结果是理想的。     

基于仿射变换从序列图像恢复物体的三维结构

提出了一种基于仿射变换重建物体三维结构的新算法。不同于以往的基于仿射变换的重建算法,该算法首先基于新的仿射投影矩阵分解算法得到物体三维结构值及摄像机的外参数信息;其次用光束法平差修正模型误差和提高三维结构的精度。算法用仿真实验和实拍图像都得到了精确、可靠的结果。     

卡尔曼预测及姿态补偿算法研究及在机载天线稳定跟踪系统扰动隔离应用

为集中展示校园风貌和文化氛围,基于Creator和Vega平台实现了自动导航寻径的虚拟校园漫游系统。结合校园建筑特点,引入面向对象思想并应用有向无环树状图组织场景数据,实现了对虚拟场景的层次化管理。在建模阶段,利用不同精度的纹理贴图生成不同精度的模型,给出了支持LOD的快速建模方法。在漫游导航中,通过鼠标拾取实时显示虚拟物体的属性信息,运用方向优先的Dijkstra算法查找最短路径并实现漫游导航功能。在普通PC上测试,无论是单个模型的渲染效率还是系统的整体性能,场景的逼真度和浏览的顺畅性都较为理想,体现出人机工程顺畅和自然的特征。     

用角加速度测量物体转动惯量的实验方法

经研究发现测量物体转动惯量使用被测物体的振动周期,转动惯量与振动周期的平方成正比,二者之间非线性关系,在提高测量精度与优化测量方法工作中未见有降低二者之间的幂而获得线性关系的数学模型。国基项目为了提高转动惯量的测量精准度,探索出的数学模型深奥,算法繁杂。虽然航空航天检测部门的最新专利成果中有启蒙式利用标准块校正转动惯量提高检测精度与效率的尝试,但未推导、合理应用线性数学模型,转动惯量只能在小量程内近似标定,同时形成精确探测与定距呈反方向的关系,限制了测量精度与效率。本文利用角加速度与转动惯量形成正比的数学关系,推导出数学模型可以依据需求而设置测量精度,理论上可以任意设置测量精度。     

虚拟校园三维场景构建与漫游导航的实现

为集中展示校园风貌和文化氛围,基于Creator和Vega平台实现了自动导航寻径的虚拟校园漫游系统;结合校园建筑特点,引入面向对象思想并应用有向无环树状图组织场景数据,实现了对虚拟场景的层次化管理;在建模阶段,利用不同精度的纹理贴图生成不同精度的模型,给出了支持LOD的快速建模方法;在漫游导航中,通过鼠标拾取实时显示虚拟物体的属性信息,运用方向优先的Dijkstra算法查找最短路径并实现漫游导航功能;在普通PC上测试,无论是单个模型的渲染效率还是系统的整体性能,场景的逼真度和浏览的顺畅性都较为理想,体现出人机工程顺畅和自然的特征。     

基于Delphi 7.0和FX2N PLC的自动控制液压试验系统研制

通过优化照相机的内部参数,运用基于转轴法的外切矩形法对工件进行定位,确定工件像素级的姿态和尺寸。选取物体的ROI后,运用双线性差值算法,实现工件边缘的亚像素提取,通过黑塞范式直线拟合,找到精确的物体边缘。最终实现了运用500万像素的工业照相机,在全景拍摄条件下,测量尺寸在80mm到150mm的工件,测量重复性精度可以达到0.015mm。     

基于全景环带成像的语义视觉里程计

视觉里程计在智能机器人、自动驾驶等领域有着广泛的应用.但是基于有限视场(FOV)针孔相机的经典视觉里程计算法容易受到环境中运动物体和相机快速旋转的影响,在实际应用中鲁棒性和精度不足.针对这一问题,提出全景环带语义视觉里程计.通过将具有超大视场的全景环带成像系统应用到视觉里程计,并将基于深度学习的全景环带语义分割所提供的语义信息耦合到算法的各个模块,减小运动物体和快速旋转的影响,提高在应对这两种挑战性场景时算法性能.实验结果表明,相较于经典的视觉里程计,所提算法在实际环境下可以实现更加精确和鲁棒的位姿估计.     

基于神经网络的相位-高度映射算法

建立高精度的相位-高度映射关系是结构光测量技术中的关键技术之一.在精确建立相机图像和投影仪图像对应关系的基础上,使用三层反向传播神经网络训练来建立图像坐标与被测物体三维坐标之间的映射关系.使用带有圆形标志点的平面标定板进行神经网络的样本采集与训练.为了验证本文算法的测量精度,使用训练好的网络对一个标准球和石膏头像进行了测量.实验结果表明,本文算法可以测量具有复杂自由曲面的物体,测量精度可达0.095mm.     

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.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

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.     

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.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

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.