AFM定位系统动态误差补偿方法研究

原子力显微镜（AFM）是进行纳米测量和操作的重要工具。针对力测量过程中AFM定位系统的测量速度慢和窄带等问题,基于逆系统的迭代学习控制思想,设计一个前馈控制环节,补偿AFM定位系统中z轴方向上动态特性非线性影响。通过在一定带宽内对期望输入信号进行轨迹跟踪,使激励力（通过悬臂梁）无失真地施加在样本上,达到AFM准确测量的目的。该方法不仅拓宽了系统频带,而且提高了系统输出对期望输入的跟踪精度。     

超高真空扫描隧道显微镜定位系统的研制

本文介绍了超高真空扫描隧道显微镜（ＵＨＶ－ＳＴＭ）定位系统的设计方法，并对误差进行了分析和修正。定位系统在操作范围为－５６０～＋５６０ｎｍ时的定位精度达到了０．１ｎｍ，该系统性能稳定，运行可靠。达到了设计要求     

浅谈煤矿人员定位系统

人员定位系统是一种集无线数据传输、信息采集与网络传输、自动控制等技术为一体的动态目标监控定位系统。该系统可以实时观察动态目标的移动情况、查询目标的历史数据、确定动态目标的当前位置等,有利于加强煤矿管理层对井下人员的管理及安全救护。本文从对人员定位系统的理解出发,对其进行的系统描述,同时联系相关的定位系统的理论,综合阐述了作者对人员定位系统的认识。     

基于3D全息技术应用设备产业经济推介设想

本文运用视觉暂停技术原理，以3D全息技术应用设备之一的广告机为例，探讨产业经济推介生动化、具象化的模式。本文采用相配套的裸眼3D软件设计3D动态内容，探索多种3D动态展示形式，包括产业地图+项目建设实景展示、产业地图+项目效果图展示、项目效果图+产品展示等形式，以达到形象化与具象化相结合、优化推介效果的目的。     

声源定位系统动态校准方法研究

基于空间移动的标准点声源设计,建立声源定位系统动态校准装置。提出空气声声源定位系统动态校准方法,获得声源定位系统动态定位实验测量结果,分析影响动态定位结果的主要因素,并进行测量结果不确定度的评定。为车辆通过噪声源定位、飞行器飞行中噪声源定位的实验室动态校准提供了计量技术支撑。     

基于立体视觉的移动机器人自主导航定位系统

描述了一种基于立体视觉的移动机器人自主导航定位系统。该系统采用双目立体视觉完成环境特征的3D信息提取,实时计算出机器人相对作业目标的位姿（6D）关系,导引移动机器人控制系统按目标异向进行运动。系统在相对位姿计算中采用旋动（Screw）理论,将带约束的多变量函数的非线性优化问题转化为线性方程组的最小二乘问题,简化了计算复杂性。实验表明,这个导航定位系统在定位精度和数据处理速度上均可满足机器人导航的要求。     

水下被动定位系统的校准子系统

减小水下被动动定位系统的定位误差是多年来人们一直关注的一个问题。对于一个实际定位系统，定位误差通常由随机误差和系统误差两部分组成，予以分别对待，可提高定位精度，其中系统误差可对采用系统校准进行消除。本文介绍一个可对实际定位系统实施校准的校准子系统。海上试验的结果表明，定位系统经过校准可有效地减小定位误差，提高定位精度。     

基于自适应卡尔曼滤波的超宽带室内定位系统

超宽带(Ultra Wideband,UWB)室内定位技术以其抗干扰、抗多径传播能力强以及低功耗、低成本、高精度等特点,得到了越来越多人的关注.该文针对传统的卡尔曼滤波算法在运用于室内UWB系统定位时,由于初始参数不定以及在环境变化或系统运行偏差后定位误差增大等问题,提出了一种自适应卡尔曼滤波算法.该算法可以在定位中自动校准参数,从而提高了定位系统的可靠性和定位精度.论文设计了以DW1000射频芯片为基础的室内定位系统,并对各种定位算法进行测试.实验结果表明:融合了自适应卡尔曼滤波的定位算法,在静态定位中可以提高定位稳定性,而在动态定位中则可以提高定位精度.系统定位精度达到10cm以内,为实际应用奠定了良好的基础.     

中低速磁浮列车测速定位系统的设计与实施

主要研究了将感应无线车上测址技术应用于具有强电磁干扰的磁浮测速定位系统，并研究“实时电子计数脉冲＋地址计算测速”的双重速度检测方法。对提高感应回线测速定位系统的可靠性和抗干扰能力进行了一系列的实验、验证测试，为低速磁浮测速定位系统的工程化奠定了坚实的基础。     

GPS-RTK技术在石油勘探中的应用

所谓RTK实时动态定位系统就是GPS定位技术的进一步发展,其拥有很多传统GPS所不具备的条件,并且在测绘领域中已得到了广泛使用。另测绘技术发生了一场革命性的技术变化,且产生了巨大的经济效益。通过对RTK实时动态定位系统在石油物探测量中的应用加以概述和探讨。     

Coal powder measurement by digital holography with expanded measurement area

The field of view of digital in-line holography for flow field diagnostics is restricted to a small volume due to the finite size and the low spatial resolution of the available CCD. Expansion of the measurement cross section of digital holographic particle image velocimetry was investigated with a lens-based holography configuration. By sampling the chirp signal in the center lobe completely and undersampling the chirp signal in the second- and higher-order lobes by a magnified virtual recording plane produced by an imaging camera lens, the field of view is expanded. Simulation results show that the three-dimensional (3D) location and size of the relatively large particle can be reconstructed with good accuracy. A digital holographic particle image velocimetry system was established for coal particle flow field diagnostics. Compared with the lensless configuration, the field of view of the digital holography system was enlarged 1.9 times, up to 2.78 cm × 2.78 cm × 3 cm. The 3D location, size distribution, and the 3D vector field of coal powder were obtained. The results show that the application of digital in-line holography to measure large particle flow field is feasible.     

Laser Powder Deposition of a Near Net Shape Injection Mold Core — A Case Study

Directed Light Fabrication (DLF) is a direct deposition process that fuses metal powder, in the focal zone of a laser beam, to form fully fused near net shaped components. A fully associative 3D design-through-manufacturing model is presented as a case study for the fabrication of a near net shaped injection mold core part. This study evaluates the ability to move from a parametric 3D model, integrated into a manufacturing model, to creating a control file used to produce a component using a nickel base alloy. Evaluation of the efficiency, quality, attributes and limitations of the process is reported. A high degree of accuracy for large feature location was obtained but improvements in surface finish and the dimensional accuracy of small features are required to fully realize benefits of this technology. The competing benefits of deposition accuracy and manufacturing time are discussed in terms of computerized numerical control code generation.     

基于混合坐标系的FDM型3D打印机研制

传统FDM（fused deposition molding，熔融沉积成型）型3D打印机在打印倒体件的过程中需设置辅助支撑结构，打印完成后去除支撑结构，这会导致成型件的精度降低。为解决传统FDM型3D打印机存在的问题，设计了一种基于混合坐标系的FDM型3D打印机。将基于笛卡尔坐标系的运动方式转换为基于拟球坐标系的运动方式，由X-Z平面内的旋转运动、X-Y平面内的旋转运动和Z轴方向的直线运动组合成拟球坐标系内的运动，达到无支撑3D打印的目的。介绍了基于混合坐标系的FDM型3D打印机控制系统的硬件和软件设计。用传统FDM型和基于混合坐标系的FDM型3D打印机进行打印实验并作对比，结果表明在同等级精度硬件配置的情况下，基于混合坐标系的FDM型3D打印机可以实现更高的打印精度。基于混合坐标系的FDM型3D打印机创新性强、造价低，拥有自主知识产权，具有广阔的市场前景。     

基于2D-3D双目运动估计的立体视觉定位算法

运动估计算法是影响立体视觉定位精度的重要因素,传统的3D-3D运动估计算法受噪声影响很大,计算精度不高.本文提出了一种基于2D-3D双目运动估计的立体视觉定位算法.算法不使用运动后的特征点3D坐标,而直接利用其2D图像投影坐标.首先,利用EPnP运动估计算法确定匹配内点和初始运动参数.接着,利用双目相机之间的2D投影几...     

Real-Time Recognition and Location of Indoor Objects

Object recognition and location has always been one of the research hotspots in machine vision. It is of great value and significance to the development and application of current service robots, industrial automation, unmanned driving and other fields. In order to realize the real-time recognition and location of indoor scene objects, this article proposes an improved YOLOv3 neural network model, which combines densely connected networks and residual networks to construct a new YOLOv3 backbone network, which is applied to the detection and recognition of objects in indoor scenes. In this article, RealSense D415 RGB-D camera is used to obtain the RGB map and depth map, the actual distance value is calculated after each pixel in the scene image is mapped to the real scene. Experiment results proved that the detection and recognition accuracy and real-time performance by the new network are obviously improved compared with the previous YOLOV3 neural network model in the same scene. More objects can be detected after the improvement of network which cannot be detected with the YOLOv3 network before the improvement. The running time of objects detection and recognition is reduced to less than half of the original. This improved network has a certain reference value for practical engineering application.     

Comparison of the Accuracy of 2D vs. 3D FDTD Air-Coupled GPR Modeling of Bridge Deck Deterioration

Computational modeling is beneficial in the preparation for nondestructive wave-based sensing. Forward models, which can be implemented through a variety of computational modeling techniques, enable parametric evaluations to assess the functionality of a sensor under different conditions, and are integral to the solution of the inverse problem. The focus of this article is on the comparison of two-dimensional (2D) and three-dimensional (3D) Finite Difference Time Domain (FDTD) models. This article gives a presentation of the accuracy of 2D modeling by comparing FDTD simulations of reinforced bridge deck deterioration in 2D and 3D. Simulations for a healthy and delaminated bridge deck are examined. It is shown that the difference in propaga-tion between the 3D and 2D point sources must be considered and is more pronounced at greater distances from the source location. The effect of scattering from the delamination is visible and, while there is variation in amplitude between the 3D and 2D models, the shapes of the resulting waveforms (including the peak arrival times) are well matched.     

Integral floating display systems for augmented reality

Novel integral floating three-dimensional (3D) display methods are proposed for implementing an augmented reality (AR) system. The 3D display for AR requires a long-range focus depth and a see-though property. A system that adopts a concave lens instead of a convex lens is proposed for realizing the integral floating system with a long working distance using a reduced pixel pitch of the elemental image. An investigation that reveals that the location of the central depth plane is restricted by the pixel pitch of the display device is presented. An optical see-through system using a convex half mirror is also proposed for providing 3D images with a proper accommodation response. The concepts of the proposed methods are explained and the validity of system is proved by the experimental results.     

Role of optics in the accuracy of depth-from-defocus systems

The depth-from-focus-defocus approach to 3D reconstruction is based on the fact that objects closer to or farther from the object in focus appear blurred, and the amount of blur increases with the distance from the object in focus. An important characteristic of any depth-from-defocus system is the depth reconstruction accuracy. Several 3D reconstruction algorithms have been proposed, and the influence of image noise and image spectrum on the system accuracy has been studied. However, so far the effect of optics on the accuracy has not been fully explored. Here, we derive an expression estimating the system accuracy as a function of its optical parameters. It turns out that optics plays a major role in the accuracy, and tenfold increase of the lens focal length, and the aperture can increase the overall accuracy by a factor of more than 1000. The derived expression allows one to review several results, revealing that the accuracy is defined primarily by the optics. We also provide guidelines for the design of new depth-from-defocus systems in compliance with predefined specifications by choosing the appropriate optics.     

Precise Orbit Determination for the FY-3C Satellite Using Onboard BDS and GPS Observations from 2013, 2015, and 2017

Using the FengYun-3C (FY-3C) onboard BeiDou Navigation Satellite System (BDS) and Global Positioning System (GPS) data from 2013 to 2017, this study investigates the performance and contribution of BDS to precise orbit determination (POD) for a low-Earth orbit (LEO). The overlap comparison result indicates that code bias correction of BDS can improve the POD accuracy by 12.4%. The multi-year averaged one-dimensional (1D) root mean square (RMS) of the overlapping orbit differences (OODs) for the GPS-only solution is 2.0, 1.7, and 1.5 cm, respectively, during the 2013, 2015, and 2017 periods. The 1D RMS for the BDS-only solution is 150.9, 115.0, and 47.4 cm, respectively, during the 2013, 2015, and 2017 periods, which is much worse than the GPS-only solution due to the regional system of BDS and the few BDS channels of the FY-3C receiver. For the BDS and GPS combined solution (also known as the GC combined solution), the averaged 1D RMS is 2.5, 2.3, and 1.6 cm, respectively, in 2013, 2015, and 2017, while the GC combined POD presents a significant accuracy improvement after the exclusion of geostationary Earth orbit (GEO) satellites. The main reason for the improvement seen after this exclusion is the unfavorable satellite tracking geometry and poor orbit accuracy of GEO satellites. The accuracy of BDS-only and GC combined solutions have gradually improved from 2013 to 2017, thanks to improvements in the accuracy of International GNSS Service (IGS) orbit and clock products in recent years, especially the availability of a high-frequency satellite clock product (30 s sampling interval) since 2015. Moreover, the GC POD (without GEO) was able to achieve slightly better accuracy than the GPS-only POD in 2017, indicating that the fusion of BDS and GPS observations can improve the accuracy of LEO POD. GC combined POD can significantly improve the reliability of LEO POD, simply due to system redundancy. An increased contribution of BDS to LEO POD can be expected with the launch of more BDS satellites and with further improvements in the accuracy of BDS satellite products in the near future.     

用于机器人视觉的大景深便携式三维扫描系统

针对机器人视觉对便携式三维扫描系统的大景深要求,利用Scheimpflug条件对CCD平面进行偏转,成功地将扫描系统的景深从30mm提高到了100mm以上;并根据CCD偏转后的摄像机模型,在理论上完整地推导了便携式集成三维扫描系统的物像关系方程。针对景深扩大后带来的测量精度降低的问题,提出了一种对系统全景深范围进行分段校准的新方法,提高了测量精度与系统分辨率。三维重建时,根据被扫描物体所对应的图像点在像平面上的不同位置分别调用不同的标定参数将二维图像坐标转变为物体的空间坐标,测量精度可以达到0.06mm。