An Impedance-Based Catheter Positioning System for Cardiac Mapping and Navigation

Over the last years, nonfluoroscopic in vivo cardiac mapping and navigation systems have been developed and successfully applied in clinical electrophysiology. Clearly, a trend can be observed to introduce more sensors into the measurement system so that physiological information can be gathered simultaneously and more efficiently and the duration of procedure can be shortened significantly. However, it would not be realistic to equip each catheter electrode with a localizer, e.g., by embedding a miniature magnetic location sensor. Therefore, in this paper, an alternate approach has been worked out to efficiently localize multiple catheter electrodes by considering the impedance between electrodes in the heart and electrode patches on the body surface. In application of the new technique, no additional expensive and sophisticated hardware is required other than the currently existing cardiac navigation system. A tank model and a computerized realistic human model are employed to support the development of the positioning system. In the simulation study, the new approach achieves an average localization error of less than 1 mm, which proves the feasibility of the impedance-based catheter positioning system. Consequently, the new positioning system can provide an inexpensive and accurate solution to improve the efficiency and efficacy of catheter ablation.     

Design and Performance Evaluation of a Remote Catheter Navigation System

A novel remote catheter navigation system has been developed to reduce physical stress and irradiation to the interventionalist during fluoroscopic X-ray guided catheter intervention. The unique teleoperated design of this system allows the interventionalist to apply conventional axial and radial motion, as used in current practice, to an input catheter placed in a radiation-safe location to control a second catheter placed inside the procedure room. A catheter sensor (used to measure motion of the input catheter) and a catheter manipulator (used to manipulate the second catheter) are both presented. Performance evaluation of the system was assessed by first conducting bench-top experiments to quantify accuracy and precision of both sensed and replicated motion, and then conducting two experiments to evaluate the latency from sensed to replicated motion. The first study consisted of replicating motions of prescribed motion trajectories, while the second study utilized eight operators to remotely navigate a catheter through a normal carotid model. The results show the system has the ability to sense and replicate motion to within 1 mm and 1^deg in the axial and radial directions, respectively. Remote catheter manipulation was found to be operator dependent and occurred under 300 ms. Future applications of this technology are then presented.     

Intracardiac Catheter Fibrillation Thresholds as a Function of the Duration of 60 Hz Current and Electrode Area

Fibrillation thresholds and their relationship to the duration of 60 Hz current flow, expressed as the number of 60 Hz cycles applied to the heart are described. Results are obtained for catheter surface areas ranging from 0.224 mm2 to 90 mm2. The investigation indicates that the current fibrillation thresholds are exponentially related to the number of 60 Hz cycles allowed to flow and the ratio between the rheobase level and a single cycle of 60 Hz is in excess of 100:1.     

HRG旋转方位平台惯导系统频域导航算法

为提高HRG平台惯导系统的自主导航精度,提出在频域中对HRG旋转方位平台惯导系统进行导航解算,以解决其存在较大的旋转效应及划桨效应误差的问题。算法基于傅里叶变换对惯性仪表离散信号进行重构,经比力和坐标变换矩阵频域转换、频域卷积运算及傅里叶反变换后实现了用解析积分来代替数值积分,有效降低了常规时域导航算法速度求解中的时移影响。仿真结果表明,算法能够有效抑制旋转效应及划桨效应误差,提高系统的导航精度。     

SJ/T 11419-2010《导航电子地图元数据》概要

引言导航电子地图是实现导航应用产业发展的基础和重要组成部分,提高导航电子地图的内容、质量、表达、提供服务等信息的规范化和共享程度,有利于促进我国卫星导航应用市场和产业的持续有序发展。     

Characterization of Catheter Dynamics During Percutaneous Transluminal Catheter Procedures

Remote catheter navigation systems are being developed to reduce the occupational risk of the intervening physician. Despite the success of such systems, development has occurred with little fundamental knowledge of the catheter dynamics applied by the interventionalist. This paper characterizes the kinematics of a catheter during manipulation, the minimum applied force/torque during interventional procedures, and the maximum force/torque applied by an operator to overcome vasculature friction. Ten operators manipulated a 6F catheter inside a specialized catheter movement sensor to determine the velocities and accelerations of catheter motion. A mass-spring apparatus was constructed to measure the forces and torques required to overcome introducer sheath and vasculature friction. Results showed the catheter was manipulated at peak velocities and accelerations of (muplusmnsigma) : 360 plusmn 180 mmldrs^-1 and 22200 plusmn 14000 mmldrs^-2, and 19 plusmn 7 radldrs^-1 and 900 plusmn 510 radldrs^-2, for axial and radial directions of motion, respectively. A minimum force of 0.29 plusmn 0.06 N and a torque of 1.15 plusmn0.3 mNldrm was required to move the catheter through the introducer sheath; while the observed maximum applied torque was 15 mNldrm to overcome vasculature friction. The implications of these results for future design optimization of an intuitive remote catheter navigation system are considered.     

Navigation Technologies for Autonomous Underwater Vehicles

With recent advances in battery capacity and the development of hydrogen fuel cells, autonomous underwater vehicles (AUVs) are being used to undertake longer missions that were previously performed by manned or tethered vehicles. As a result, more advanced navigation systems are needed to maintain an accurate position over a larger operational area. The accuracy of the navigation system is critical to the quality of the data collected during survey missions and the recovery of the AUV. Many different methods for navigation in different underwater environments have been proposed in the literature. In this correspondence paper, the state of the art in navigation technologies for AUVs is investigated for theoretical and operational systems. Their suitability for use in different environments is compared and current limitations of these methods are identified. In addition, new approaches to address these current problems and areas for future research are suggested. Finally, it is concluded that only geophysically referenced methods will enable AUVs to navigate accurately over large areas and that advances in underwater feature recognition are required before these methods can be implemented in operational AUVs.     

北斗卫星导航用户终端供电系统的设计

给出卫星导航用户终端的电源系统设计.     

四自由度模块化机械臂运动学建模

首先根据四自由度(MT-R)模块化机械臂的结构特点和运动学约束,利用D-H算法对机械臂进行表示和建模,得到了以关节角度为变量的正运动学模型。利用矩阵逆乘的解析法求解机械臂逆运动学的完整解析解;最后通过仿真和实验验证了正运动学模型及运动学逆解的正确性。验证结果为机械臂末端执行器的精确定位和轨迹规划提供了理论依据。     

Improved Algorithm for Solving Inverse Kinematics of Biped Robots

Mobile Networks and Applications - Inverse kinematics is an important basic theory in walking control of biped robot. This study focuses on the parameter setting using the improved algorithm in...     

JTIDS相对导航与惯导对航迹质量影响的对比分析

针对空中机群编队的定位导航问题,本文研究了相对导航和惯性导航两种导航模式对联合战术信息分发系统网内平台位置质量的影响,并从本质上比较了二者产生的定位误差,在此基础上进一步对上述两种导航模式对 C2 平台的航迹质量影响进行了定量分析。     

仿生偏振导航传感器实验模型的构建与标定

针对研制仿生导航微传感器的需要,设计并且搭建了偏振导航传感器实验模型。分析了仿生导航传感器工作的原理,构建了传感器模型实验平台和光学标定装置。利用光学标定装置对导航传感器进行了暗场标定、均匀非偏振光标定。进行了导航定位角度输出实验,获得了导航传感器三个偏振方向分析器标准化输出曲线。测试结果表明这种新型传感器的设计是合理有效的。     

仿生偏振导航传感器实验模型的构建与标定

针对研制仿生导航微传感器的需要，设计并且搭建了偏振导航传感器实验模型。分析了仿生导航传感器工作的原理，构建了传感器模型实验平台和光学标定装置。利用光学标定装置对导航传感器进行了暗场标定、均匀非偏振光标定。进行了导航定位角度输出实验，获得了导航传感器三个偏振方向分析器标准化输出曲线。测试结果表明这种新型传感器的设计是合理有效的。     

机载导航设备自动测试系统

主要介绍了一种基于VXI总线的机载导航设备自动测试系统的设计和实现,详细论述了自动测试系统的硬件结构及软件设计。硬件设计采用货架设备和标准化组件,软件设计采用虚拟仪器。测试系统能实现设备系统级与板极的自动测试,并在保证测试过程完整性的同时实现远程诊断和数据共享。该系统具有可靠性高、测试精度高、系统开放等特点。     

增强北斗导航性能的几点建议

2010年12月18日,我国第7颗北斗(Compass)卫星入轨运行,这将使2012年前建成一个区域性覆盖的北斗系统变成现实。如何增强北斗导航性能也就成为一个研究大热点。基于对GPS/GLONASS现代化的分析,笔者提出增强北斗导航性能的下述建议:扩大北斗卫星定轨观测网,提高广播星历精度;优化北斗卫星导航电文内容,便于用户接收使用;播发北斗与GPS/GLONASS/Galileo的时差信息,扩大北斗的应用市场;研发北斗卫星自主导航技术,提高北斗系统的抗毁能力;研制MEMS化北斗卫星,建设强抗毁和强抗干扰的全新北斗星座。     

助航灯具光强测试系统研究

针对助航灯具的发光特性,提出了一种测试助航灯具出射光强分布的方法.使用线阵CCD作为光电传感器,采集、获取各个方向灯具的光强信号,利用A/D芯片和USB接口芯片实现数据的转化和实时传输.通过改进的Delaunay三角剖分线算法和B样条曲线平滑处理算法的结合,提出了一种快速生成等光强曲线的算法,给出了Matlab软件获得等光强曲线的方法.通过对PAPI灯出射光强的测试及其等光强曲线的拟合,验证了该测试装置可以较好地实现光强测试,所提算法绘制的曲线平滑、速度快.     

卫星导航定位应用标准体系

阐述了卫星导航定位系统及应用标准体系框架一基础标准、技术体制标准,关键件标准、接收设备标准和信息服务标准五个方面的组成,并列出了标准体系表.     

GPS 3D 导航设计的稳定性考虑

3D地图的出现和推广、更多信息点的地图,使大容量的存储器成为2008年导航产品发展的一个重要方向.大容量存储器的需要还来源于对数据保护的需求.本文通过对比Embedded Raw MLC和Managed Nand两种存储方式,介绍了系统硬件和软件设计对GPS导航设备稳定性的影响.     

北斗卫星导航应用标准化工作建议

介绍了卫星导航定位系统及国家发改委卫星导航应用标准专项,并针对北斗卫星导航应用标准化工作提出了建议。     

卫星导航中的一种实用权重估算模型

本文对卫星导航中的权重估算模型进行研究,通过分析卫星导航中的误差特点,利用有限数据建立误差的估算模型,在不消耗额外资源的同时得到卫星的权重,提高了卫星导航稳定性stability和可靠性。用软件实现估算模型并进行试验验证,证明了该估算模型的可行性和有效性。