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为快速跟踪及定位远距离的运动车辆,本文设计了利用单目相机与激光望远测距仪的定位系统。此定位系统装备单目相机、望远测距仪与角度传感器,采用LK光流算法实时跟踪既定目标,构建了相机、测距仪、目标的坐标方程式模型,可实时解算100~300 m外运动目标的位置。该定位系统无需在被测运动车辆上安装任何设施,即可对合作或非合作目标实现跟踪定位。本文以汽车作为运动目标,使用高精度的CORS系统进行精度验证,该系统实时跟踪定位的精度可保持在亚米级。 相似文献
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针对新型半潜式无人艇在导航航行过程中轨迹跟踪误差较大的问题,提出基于模型预测控制（MPC）的轨迹跟踪控制方法．并建立新型半潜式无人艇的运动模型,基于实际参数,构建MPC目标函数和系统约束条件,将半潜式无人艇轨迹跟踪问题转化为最优值问题;利用仿真软件,对控制算法进行了仿真分析. 利用卫星定位设备进行了导航轨迹跟踪试验．仿真与试验结果表明:基于MPC的轨迹跟踪控制方法提高了半潜式无人艇的导航轨迹跟踪精度,跟踪精度比原有PID控制方法提高了50％左右. 相似文献
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针对传统伪距差分服务端压力大,以及在复杂环境下进行导航定位,某些历元卫星信号弱、卫星数不足、无法连续定位的问题,该文提出了基于扩展卡尔曼滤波算法的虚拟格网伪距差分方法。该方法充分利用先验信息和动力学模型,解决了复杂环境中动态定位结果不连续、定位精度低等问题。为验证算法的有效性,该文分别进行了动态、静态实验,并与最小二乘结果进行对比,实验结果表明:静态模式下,卡尔曼滤波算法比最小二乘算法的定位精度,在N、E、U方向分别提高48.3%、47.1%、52.5%;动态模式下,卡尔曼滤波算法比最小二乘算法更加稳定,更适合复杂环境定位。 相似文献
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多路径效应是影响卫星定位精度和稳定性的重要因素。针对多路径环境复杂多变难以进行分析的问题,该文提出了一种利用双极性天线探测多路径的方法。详细介绍了反射信号的极性特征;通过判断信号的极性可以有效地区分直射信号和反射信号。分析了通过信号极性实现多路径探测的理论:组成双极性天线的右螺旋圆极化天线和左螺旋圆极化天线能够分别输出卫星信号中的右螺旋圆极化分量和左螺旋圆极化分量,如果两个分量的载噪比差值大于一定的门槛值,就可以推断卫星信号在传输过程中经历了多路径效应。最后通过仿真实验验证了该方法的可行性和有效性。 相似文献
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随着定位服务的兴起,越来越多的人和公司注重对其所拥有的珍贵物品的管理与保护,通过对其位置的确定达到管理的目的。目前主要的定位方式是利用全球卫星导航系统(GNSS)。但是许多所要定位的珍贵物品储存于室内,而室内很难接收到卫影信号,所以无法对其进行准确定位。ZigBee室内定位技术作为目前一种新兴的短距离无线数据网络通信技术,具有低功耗、低成本、低速、高容量、高安全性、高可靠性和短时延等特点非常适合对室内珍贵物品定位。在ZigBee室内定位技术的众多定位算法中RSSI测量技术现代化无线模块已经具有对RSSI的测量功能,不需要额外硬件支持,同时误码率可以被用来估计信号衰减。同时大多数珍贵物品的所存储房间大多室内结构简单,环境因素对其影响较大,信号干扰影响基本很小。所以利用ZigBee定位算法中RSSI测量技术对室内存放的珍贵物品进行定位是可行的。 相似文献
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IRNSS-1A: signal and clock characterization of the Indian regional navigation system 总被引：4，自引：1，他引：3
An initial characterization of the L5 and S-Band navigation signals transmitted by the first satellite of the Indian regional navigation satellite system (IRNSS) is presented. In the absence of a public signal specification, a 30 m high-gain antenna has been used to record the signal spectrum and the modulated chip sequences. For the IRNSS standard positioning service, use of a Gold ranging code is confirmed and relevant shift register parameters for the two frequencies are identified. Based on a prototype receiver, L5 single-frequency code and phase observations of IRNSS-1A have also been collected. The tracking performance is described, and the measurements are used to characterize the short-term clock stability of IRNSS-1A. 相似文献
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针对Wi-Fi信号易受噪声等外界不确定因素的影响以及移动终端接收信号强度指示（RSSI）与真实值存在偏差而导致定位精度不高的问题,本文提出了一种基于GF-KF修正RSSI的室内指纹定位方法．由于采集的RSSI不稳定,该方法利用RSSI类高斯分布的特性,对RSSI数据进行高斯拟合,以得到较为确定的RSSI值．在此基础上,引入卡尔曼滤波算法对拟合后的RSSI数据进行误差修正,结合加权K近邻（WKNN）匹配算法进行定位．实验结果表明:本文方法的平均定位误差为1.5 m,2.0 m以内的误差累积分布概率为90.06％,定位效果优于同类方法． 相似文献
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Carrier phase–based positioning using Global Navigation Satellite System (GNSS) signals can provide centimeter-level accuracy; however, to do so requires robust, continuous tracking of the phase of the received signal. The phase-locked loop is typically the weakest link in GNSS signal processing, with frequent cycle slips and loss of lock occurring at lower signal-to-noise ratios. One way to improve the signal-to-noise ratio is to increase the coherent integration time; however doing so reduces the loop update rate, thereby degrading performance. This paper investigates this trade-off between sensitivity and loop update rate by investigation of the Kalman filter-based tracking loop. It is shown that it is possible to choose an optimal integration time for a given application. A relatively straightforward procedure is given to determine this optimal value. The results are confirmed through real-time kinematic processing of live satellite signals. 相似文献
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北斗卫星导航系统（BeiDou navigation satellite system,BDS）发播电文时利用卫星钟差a0参数修正了B3频点相位中心与质心差异的大部分偏差,利用卫星群延时间参数（timing group delay,Tgd）修正不同频点相位中心的差异部分。该方法实质是利用各向同性的卫星钟差修正具有各向异性的天线相位中心偏差,改正精度有限。为进一步提高广播星历精度,提出了先对卫星位置进行相位中心改正,再对相位中心的轨迹进行广播星历拟合的处理方法,分别比较了两种改正方法对用户距离误差（user range error,URE）以及精密单点定位精度的影响。分析表明,两种方法都能使URE和定位精度得到提高,且新方法比利用卫星钟差a0参数的修正精度提高了约76%,定位精度提高了约12.5%,同时新方法的改正精度不受时空因素影响。利用广播星历拟合修正天线相位中心与不进行天线相位中心比较,定位精度提高约38.1%。最后分析了Tgd参数修正各频点天线相位中心不一致的残差,影响在毫米级,可以用于修正相位中心的频间差异。 相似文献
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从2017年1月开始,北斗系统在播发基本导航电文的同时,提供了包含实时轨道改正数、钟差改正数、电离层格网改正数和分区综合改正数四重广域差分参数,使得系统具备了基于系统广播的电文参数实现广域单站实时动态分米级定位的能力。实际应用表明,北斗系统播发的分区综合改正数存在中断的情况,使得实时定位存在因重新收敛而造成跳变的情况。本文分析了分区中断期间定位跳变产生的原因,提出一种适用于分区切换的广域差分分米级定位算法。采用中国境内7个北斗测站10d的静态数据和车载动态数据对新算法进行评估验证。结果表明,在分区改正数中断的情况下,分区切换算法得到的坐标误差与使用连续分区综合改正数结果一致,双频动态定位水平和高程方向分别小于0.3m和0.5m,平均三维定位精度优于0.5m;车载实时动态定位测试中,分区切换前后的单双频定位精度不受切换影响,与切换前保持一致。分区切换算法有效保证了分区改正数中断后北斗广域分米级实时动态定位的连续性。 相似文献
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针对GNSS接收机在室内环境中面临的强烈的信号衰减、非视距传播和互相关效应的问题,提出了一种基于粗时段导航和RAIM算法解决A-GNSS室内定位问题的方法,并利用BDS数据验证了该方法的可靠性。结果表明,粗时段导航算法能够提供连续可靠的定位结果,应用于微弱信号环境;基于组合FDE的RAIM算法能够增加定位结果可用率,解决室内卫星信号存在的非视距传播和互相关效应的问题。基于粗时段导航与RAIM算法的A-GNSS定位技术能够应用于室内定位,仿真定位结果水平方向RMS在10 m以内。 相似文献
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Multipath in global positioning system (GPS) is the interference of the microwave signals directly from satellites and those
reflected before reaching the antenna, typically by the ground. Because reflected signals cause positioning errors, GPS antennas
are designed to reduce such interference. Recent studies show that multipath could be utilized to infer the properties of
the ground around the antenna. Here, we report one such application, i.e. a fixed GPS station used as a snow depth meter.
Because the satellite moves in the sky, the excess path length of reflected waves changes at rates dependent on the antenna
height. This causes quasi-periodic variations of the amplitude and phase of the received signals. Accumulation of snow reduces
effective antenna heights, and we can see it by analyzing multipath signatures. Signal-to-noise ratios (SNR) are often used
to analyze multipath, but they are not always available in raw GPS data files. Here, we demonstrate that the geometry-free
linear combination (L4), normally used to study the ionosphere, can also be used to analyze multipath signatures. We obtained
snow depth time series at a GPS station in Hokkaido, Japan, from January to April in 2009 using L4 and SNR. Then, we compared
their precisions. We also discuss mechanisms responsible for the possible underestimation of the snow depth by GPS. Finally,
we investigate the possibility of inferring physical conditions of the snow surface using amplitudes of multipath signatures. 相似文献
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In the complex urban environments, land vehicle navigation purely relying on GNSS cannot satisfy user needs due to the loss of satellite signals caused by obstructions such as buildings, tunnels, and trees. To solve this problem, we introduce a GPS-/MSINS-/magnetometer-integrated urban navigation system based on context awareness. In this system, the data from the Micro Strapdown Inertial Navigation System (MSINS) are used to analyze and detect the context knowledge of vehicles, whose sensor errors can be compensated by the heuristic drift reduction algorithm for different motion situations. When GPS is available, the vehicle position can be estimated by unscented Kalman Filter, whereas in the case of GPS outages, the vehicle attitude is provided by an attitude and heading reference system and the motion constraints-aided algorithm is used to complete the positioning. In the experiment validation, the integrated navigation system is set up by low-cost inertial sensors. The result shows that the proposed system can achieve high accuracy when GPS is available. For most of the time without GPS, the system can guarantee the positioning precision of 10 m and compensate the errors of MSINS effectively, which fully satisfies positioning needs in complex urban environments. 相似文献
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为了满足高动态用户及强干扰条件下的应用需求,提出了一种基于卫星信号矢量跟踪的SINS/GPS深组合导航方法,设计了基于FPGA硬件平台的实施方案。利用组合卡尔曼滤波器反馈回路取代了传统接收机中独立、并行的跟踪环路,能够同时完成所有可视卫星信号的跟踪和导航信息处理;通过矢量跟踪算法对所有可视卫星信号进行集中处理,能够增强跟踪通道对信号载噪比变化的适应能力,从而提高接收机在强干扰或信号中断条件下的跟踪性能;根据SINS导航参数和星历信息推测GPS伪码相位和多普勒频移等参数,用以辅助卫星信号的捕获和跟踪,能够大大缩短接收机的搜索捕获时间,并增强接收机在高动态条件下的跟踪性能。基于矢量跟踪的深组合方法不仅在GPS信号短暂中断期间,能够保证系统的导航精度和可靠性,而且在强干扰环境中能够维持较好的伪码相位和载波频率跟踪性能。 相似文献
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David Underwood 《GPS Solutions》1999,3(2):48-52
The use of the Global Positioning System (GPS) for position and attitude determination has been exploited for many years.
In these systems, it was required that multiple antennas maintained phase lock to common view satellites for long periods
of time in order to determine integer ambiguities. The challenge to overcome with the ballistic space probe is the high rotational
spin of this particular rocket. The antennas, mounted on the outside skin of the rocket, are in full view of each satellite
only for a fraction of a second before the rocket core eclipses them as it rotates. The antennas rarely see common satellites.
This article describes as system that overcomes these obstacles and provides position, acceleration, attitude, and rotation
rate. The approach uses a two-antenna system. One antenna is mounted either side of the rocket facing out. A hybrid tracking
channel combines signals from both antennas to overcome the signal blockage due to the rocket core as well as to defeat the
effect on the tracking channel due to the spin. The amplitude and phase of the spin rotation signature from each satellite
is extracted from the dual antenna data and used to compute the attitude and spin rate of the vehicle. ? 1999 John Wiley &
Sons, Inc. 相似文献
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在卫星导航定位过程中,当辅助式定位算法在信号质量不佳时,利用更多的观测卫星数据进行冗余计算,能够补齐缺失的信号时间并得到定位结果. 由我国自行研制的北斗卫星导航系统(BDS)采用了混合卫星星座,有一类地球同步轨道(GEO)卫星,具有24 h可见、轨道高覆盖面大、信号功率强等优势. 论文分析了在特殊情况下,只能接收到GEO卫星时的辅助式定位算法以及算法的性能差异. 结果表明:在没有高程等先验信息辅助的情况下,直接使用5颗GEO卫星也能获得一定的定位精度保障. 相似文献
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与先期采用消电离层组合仅估计相位中心偏差(phase center offset, PCO)参数不同,欧洲的伽利略（Galileo）系统发布的地面校正的卫星天线参数基于原始频点,且包含天线相位中心变化(phase center variation, PCV)参数。为此,分析了校正的卫星天线参数特性,发现其水平向PCO与卫星类型相关,FOC(full operational capability)卫星的PCV参数较IOV(in-orbit validation)卫星稳定,仅依赖天底角。利用20个MGEX (multi-GNSS experiment)测站连续15 d的数据分析校正天线参数对双频组合/ 非组合精密单点定位（precise point positioning, PPP）的影响, 并与消电离层天线参数的定位结果比较,结果表明,其水平方向精度基本一致,双频组合PPP高程方向的精度提高约6.3%,双频非组合高程方向的精度提高约11.9%,基于原始频点的校正天线参数在双频非组合PPP定位中表现出更优的自洽性。 相似文献