A new system for computer-aided preoperative planning and intraoperative navigation during corrective jaw surgery.

A new system for computer-aided corrective surgery of the jaws has been developed and introduced clinically. It combines three-dimensional (3-D) surgical planning with conventional dental occlusion planning. The developed software allows simulating the surgical correction on virtual 3-D models of the facial skeleton generated from computed tomography (CT) scans. Surgery planning and simulation include dynamic cephalometry, semi-automatic mirroring, interactive cutting of bone and segment repositioning. By coupling the software with a tracking system and with the help of a special registration procedure, we are able to acquire dental occlusion plans from plaster model mounts. Upon completion of the surgical plan, the setup is used to manufacture positioning splints for intraoperative guidance. The system provides further intraoperative assistance with the help of a display showing jaw positions and 3-D positioning guides updated in real time during the surgical procedure. The proposed approach offers the advantages of 3-D visualization and tracking technology without sacrificing long-proven cast-based techniques for dental occlusion evaluation. The system has been applied on one patient. Throughout this procedure, we have experienced improved assessment of pathology, increased precision, and augmented control.     

基于成像激光雷达的地形辅助导航研究

成像激光雷达通过扫描可以测量高精度的地形数据,基于成像激光雷达的地形辅助导航系统是纠正惯导误差的有效手段.根据激光雷达测距模型提出了基于成像激光雷达的地形辅助导航系统,将激光雷达看作一个多维距离传感器阵列,利用卡尔曼滤波器迭代估计系统的状态误差,从而纠正惯导累积误差.根据激光雷达测距关系推导了系统的扩展卡尔曼滤波方程,并对成像激光雷达多维测量数据采用最小均方误差准则进行融合,融合滤波器组合了多个测量数据的信息,有效克服了测量噪声和数据丢失对单个滤波器的影响,从而提高了导航性能.然后利用局部可观测性对系统的性能进行了分析,并对提出的算法作了大量的仿真实验进行验证.     

基于车载导航系统的路径规划方法研究

机动车数量日益增多为交通、环境、能源等带来了巨大的压力,为此提出一种改进的路径规划算法——胶囊形限制搜索区域路径规划算法。该方法在很大程度上减少了传统路径规划方法的搜索范围,并且通过设置动态搜索参数保证了最短路径规划的成功率。以拓扑结构路网数据为实验载体,对椭圆限制区域算法及改进算法进行了深入的对比和研究,并通过实验验证了改进算法的高效性和稳定性。最后,给出了中心监控式车载导航系统的初步设计方案,其由监控中心子系统、车载子系统和通信子系统三部分组成。     

A novel technique for distal locking of intramedullary nail based on two non-constrained fluoroscopic images and navigation

Distal locking is one of the most difficult steps in intramedullary nailing. Numerous methods can help the surgeon, but all are time-consuming and involve much irradiation. We have developed and tested a new method based on only two fluoroscopic shots that do not need to be taken in the axes of the holes. This avoids requiring the presence of an experienced fluoroscopy operator to accurately adjust the imaging device in front of the locking holes, and decreases the exposure to radiation of the patient and medical team. A 3-D model of the distal nail and of its locking holes was constructed from a pair of calibrated fluoroscopic views. Prior to this, the contours of the nail and locking holes projections had to be determined. A 3-D optical localizer allowed the tracking of reference frames fixed to the nail, imaging device, and drilling motor. A navigation system based on the model guided the surgeon during distal targeting. The robustness, accuracy, and duration of the technique were evaluated in laboratory. The range of acceptable orientations of the X-ray beam has also been determined. Twenty drilling tests were carried out on sawbones. The accuracy and the duration required by our system to perform the distal targeting shows potential suitability for clinical use. The drill passed through the nail locking holes for all of them. The accuracy was about 1.5 mm in translation and 1 degree in rotation. The total time spent on drilling did not exceed 15 min. The system was also assessed in vivo on three patients.     

衍射对红外成像影响的仿真计算及校正算法研究

采用夫朗和费衍射计算公式,建立了红外焦平面阵列成像衍射仿真模型,并用Mat-lab软件对不同距离探测像元之间的衍射影响进行了仿真。为了定量地描述像元间衍射影响,定义了衍射影响因子Bef、Def,并进行了计算。提出了一种基于焦平面阵列成像的衍射校正算法,根据探测像元的实际测量值和影响因子,利用联立方程组的方式对真实辐射值进行求解,并给出了该方程组的建立方法。最后对该算法的适用条件进行了分析。     

基于粒子群算法和航行规则的分步多船避碰路径规划

针对宽水域多船避碰过程中路径规划难与航行规则结合的问题,提出一种分步多船避碰路径规划算法。首先将障碍船视为静态障碍物,利用极坐标空间的粒子群路径规划算法结合船舶安全领域进行静态路径规划,得到船舶避碰转向点;然后利用航行规则对转向点的转向角度进行动态修正。通过对算法进行仿真验证,能够很好地解决多船避碰路径规划的问题,为解决多船避碰问题提供一种新的思路。     

基于红外导航的AGV设计与实现

为了满足自动运行小车高效以及适用性等需求,设计了一款高性能的小车,该小车使用红外技术进行导行, ZigBee技术进行系统通信控制,光电传感器进行障碍物检测等.通过大量实验证明,小车具有良好的性能,并能够运用到需要无人搬运操作的多种工作场合.     

ADXL345与EB3631在GPS导航中的应用

为实现用户到目标点的距离测量和方向控制,设计并实现了基于加速度传感器ADXL345和EB3631的GPS模块的实时导航系统.系统选用EB3631搭建GPS模块,通过串口与ATMEGA644P控制器通信采集GPS定位信息;采用加速度传感器ADXL345,通过ⅡC协议与控制器通信实现位移测量.在0m-500m范围内,对系统稳定性和准确性的反复测试,最终实现了相对误差在10％以内的准确度较高的导航系统.     

基于Android平台实现实时地点通讯及导航简

摘要在传统的手机通讯中往往只能传递文字或者图片的信息．随着社会的发展人们的活动范围也随之扩大,人们对位置服务的需求也越来越突出。为了满足人们对通讯和位置服务的双重需求,基于Android平台通过采用Google地图的强大功能实现了实时地点通讯和导航系统,对系统架构和服务器、客户端实现细节进行了详细的分析。该系统整合了传递文字信息、位置信息及导航的功能,使通讯内容根据实时位置在地图上显示出来。使通讯二维化,方位化,具体化。     

基于混合扩频的导航卫星抗干扰技术

随着卫星导航系统在军事上的广泛应用．研究导航系统的抗干扰技术已经成为当务之急。文中创新的将跳时技术与现有导航系统相结合,提出基于直扩／跳时（DS/TH）混合扩频的导航卫星系统方案。并分别在4种卫星导航干扰模式下,对此方案进行了抗干扰性能仿真及分析。结果表明在信噪比为-33dB误码率为10^-4时,该方案抗干扰性能比传统导航信号至少提高17dB,尤其对于抗脉冲干扰,其性能可以改善20dB左右。     

一种红外超声相结合的AGV导航系统

随着自动化技术的不断提升,AGV的应用越来越广泛。为设计一种低成本、易布设、稳定可靠的产品,提出了一种红外超声相结合的AGV导航系统。以并排对称设计的红外传感器实现纠偏,超声波传感器实现测距,采用TI公司的DSP芯片TMS320F2808为控制核心,结合优化的PID算法及智能化的路径规划算法,并采用上位机程序进行监控。经实际应用场合验证,小车具有抗干扰能力强,导航精度高,运行稳定安全等优点,适合在物料搬运、环境监测、危险区域监控等领域推广应用。     

基于STFT的卫星导航接收机抗干扰算法研究

卫星导航接收机的抗干扰问题日益突出,对于有效的抗干扰方法的研究显得尤为重要。本文对STFT(短时傅立叶变换)算法进行了修正,提出一种时间窗的改进方法。该算法的实质就是时间窗通过位移和压缩变换得到新的窗函数族,克服了原窗函数缺陷。改进的STFT算法能够有效地提高卫星导航接收机的抗干扰能力,与传统的抗干扰方法相比,该方法更具有工程实际意义。     

基于SWE的传感规划服务研究与实现

文章首先基于SWE详细分析了传感规划服务应完成的核心操作,然后重点阐述了基于SWE的传感规划服务原型系统的设计,包括系统的数据交互和系统体系结构的设计。并详细阐述了每一层设计的实现,最后基于一个红外楼宇监控无线传感器网络实现了SPS原型系统,并进行了试验,实验结果表明该原型系统中实现的SPS的核心操作能够较好地为用户请求任务提供规划服务。     

Support infrastructures based on high altitude platforms for navigation satellite systems

In this article the use of an augmentation system based on high altitude platforms (HAPs) for supporting global navigation satellite systems is discussed. In fact, HAP-based systems are being studied and designed for several communication applications, but they can also be considered added value infrastructure if integrated with navigation systems, providing aiding services based on terrestrial stations or geostationary satellites. The article investigates the results of a feasibility study for the design of a stratospheric pseudo-satellite to provide additional ranging signal to improve the accuracy and availability of the overall navigation system, and an effective integrity service, strengthening the reliability of the positioning procedures. The work here presented discusses issues that have arisen in the design, and provides simulation performance of the proposed architecture.     

基于MPF的惯性导航系统快速对准技术

针对目前应用于惯性导航系统初始对准中的扩展卡尔曼滤波存在对准精度低、时间长的缺点,提出一种基于模型预测滤波的快速对准技术。该方法将惯性器件测量误差视为模型误差使用MPF进行实时预测,并以此来修正惯性导航系统的平台误差角。这样,MPF不仅有效提高了平台误差角的估计精度,而且降低了系统状态变量的维数,大大缩短了初始对准时间。仿真结果表明,MPF在平台对准精度和快速性方面均明显优于EKF,初时对准时间仅是EKF的10%,而对准精度却高于EKF。     

某无人机导航控制系统模块化设计

针对某无人机导航控制系统,设计了基于DSP的机载导航系统软件,提出了一种模块化的设计思想,阐明了模块化的设计思路,给出了导航软件的部分组成及其实现的功能,最后在此设计基础上给出半物理仿真。结果表明,导航软件的模块化设计条理清楚,可以全面的对导航系统进行统筹,改善开发环境,缩短开发周期,对加快无人机研制进度有重要的意义。     

Image focus measure based on polynomial coefficients and spectral radius

In this paper, a new measure of image focus based on the statistical properties of polynomial coefficients and spectral radius is proposed. Spectral radius captures the dominant features and represents the important dynamics of an image. It is shown that the proposed focus measure is monotonic and unimodal with respect to the degree of defocusation, noise and blurring effects. Moreover, it is sufficiently invariant to contrast changes occur due to the variations in intensities of illumination. The noise studies show that the proposed focus measure is robust under the different noisy and blurring conditions. The performance of proposed focus measure is gauged by comparing with the existing image focus measures. Experimental results using synthetic as well as real-time images with known and unknown distortion conditions show the wider working capability and higher prediction consistency of the proposed focus measure. Moreover, the performance of the proposed approach is validated with most popular five image quality databases: TID2008, LIVE, CSIQ, IVC and Cornell-A57. Experimentation on the databases shows that the proposed metric provides the comparatively higher correlation with ideal mean observer score than the existing metrics.     

基于机器视觉和激光雷达的车辆智能导航系统

常规的车辆智能导航系统无法准确计算其与前方障碍物之间的距离,因此,基于机器视觉和激光雷达设计了车辆智能导航系统.在车辆智能导航系统的硬件设计中,设计视觉传感芯片外围电路,配置视觉传感芯片电路元件参数,保障视觉传感装置的稳定运行,设计激光雷达温度补偿装置,保证激光雷达装置的电路稳定.在车辆智能导航系统的软件设计中,去除图...     

基于信息熵的船舶航行与区域监控方法

针对内河与沿海日益复杂及巨量的船舶目标活动带来的监管挑战,开展了船舶AIS信息应用研究。通过数据清洗、目标编批实现AIS船舶目标的初步整编和区域划分,并基于信息熵方法评估船舶目标航行状态,进而提供区域目标密度、区域航行风险评估。研究成果有助于提高目标与区域精细管理能力,降低水面交通风险。     

基于视觉检测与自主导航的轮式机器人平台

近年来,机器人产业发展迅速,为适应社会发展需求,构建了基于机器人系统ROS,以Kinect2为核心的轮式机器人平台,其涵盖了机器人运动、视觉检测与导航、机械臂控制等多学科知识的运用,并具有较好的功能扩展性。实践表明,该平台能够较好地实现机器人视觉检测与导航、机械臂抓取等功能,并可基于该平台开发如巡检机器人、餐厅服务机器人等具有特定功能的机器人平台。