惯导辅助的无电离层与宽巷组合周跳探测与修复方法

由于卫星信号被遮挡、低信噪比或接收机运动等原因,载波相位观测值较正常值会发生周跳。为解决这一问题,基于精密单点定位与惯导组合系统,提出了一种有效的惯导辅助周跳探测与修复方法。该方法基于无电离层（ionospheric free,IF）组合与宽巷（wide lane,WL）组合,利用惯导短时高精度信息代替伪距消除站星几何距离,结合历元间差、星间差等建立惯导辅助的IF组合模型和惯导辅助的WL组合模型。惯导辅助的IF组合模型不受电离层延迟影响,但无法探测特殊比例周跳,惯导辅助的WL组合模型波长较长,却无法探测双频等周周跳,两者的综合使用实现了优势互补。实验结果表明,该方法不仅能有效探测出各种大、小、双频等周和特殊比例周跳,而且在一定卫星信号中断时间内能实现周跳瞬时校正。     

北斗三频组合数据在周跳探测和修复上的应用

随着新一代卫星导航定位系统中多个频率观测数据的应用,利用多频载波相位数据的组合特性将会使周跳的探测和修复变得更加快速准确.本文利用多频组合观测值理论,选出适合北斗数据的组合系数,并结合伪距/载波相位组合方法,对北斗三频实测载波数据进行了周跳的探测与修复研究,试验结果表明无论是小周跳、大周跳以及各种粗差,该方法都可以快速...     

摄影/惯导组合定位技术在GNSS动态定位性能测试中的应用

在分析现有GNSS动态定位精度评估方法不足的基础上,提出区别于传统组合导航滤波算法的摄影/惯导组合定位技术。将多个摄影节点的位置观测量作为基准,利用最小二乘最优估计法统一解算捷联惯导误差参数。摄影/惯导组合定位方法的基本观测量、工作模式与卫星导航定位方法有本质区别;同时又具备高精度定位、高动态定位、高数据刷新率和差异数据观测量4个条件,十分适合作为GNSS动态定位性能测试的评估技术。通过在标志场内进行的摄影测量试验和摄影/惯导组合定位性能仿真试验,验证了摄影/惯导组合定位方法的可行性。该方法为首次提出,具有一定的科学价值。     

弹道导弹的GNSS/SST/SINS组合导航系统研究

提出一种组合导航方案，该方案在硬件上采用全捷联的结构，在算法上将捷联星光跟踪仪（strapdown startracker，SST）的姿态信息，高动态GNSS的位置、速度信息与捷联惯导进行组合滤波，全面提高导航精度。设计并实现了弹道导弹GNSS／SST／SINS组合导航系统实时仿真平台，仿真结果表明了该组合方案的稳定、可靠性。     

PPP/SINS紧耦合系统仿真的研究与分析

在捷联惯导(SINS)和GPS卫星接收机进行紧耦合的研究中,采用差分定位进行紧耦合的方法比较成熟,而关于精密单点定位(PPP)与捷联惯导紧耦合的研究还比较少。本文对精密单点定位与捷联惯导紧组合系统进行了Matlab仿真,利用数学解析的方法产生机载运动轨迹,通过设置系统的参数,获得仿真SINS和GPS数据;然后,通过PPP/SINS紧组合系统的仿真程序解算,将定位结果与PPP的结果比较,表明PPP/SINS紧组合导航定位的结果比PPP的精度和可靠性好,而且收敛的速度更快,同时也验证了算法的正确性。最后,分析了不同等级惯导对定位精度的影响。     

无外观测信息的旋转捷联系统组合对准方法

针对旋转捷联系统组合对准过程中外设备与惯导系统信息更新频率不同步问题,该文提出一种无外观测信息的组合对准方法:简述了旋转调制型捷联惯导系统,采用数字高通滤波器提取了载体的瞬时速度,并利用谱条件数法计算出惯性测量单元静止和旋转状态下捷联系统的可观测度;然后将滤波提取的瞬时速度与惯导解算速度作差视为观测量进行卡尔曼组合对准。实验结果表明:无外观测信息的组合对准方法可以满足旋转捷联系统的对准需求。     

惯导/双星定位组合导航方案与精度分析

分析了惯导／双星定位组合的可行性;针对惯导／双星定位组合导航在飞行器上应用存在的有关问题进行了讨论,提出了可能的对策。通过不同方案的比较分析,给出了较为实用的惯导／双星定位组合导航系统设计方案,并对组合的时机和组合导航的精度进行了仿真计算和结果分析。结果表明,采用按精度要求进行惯导／双星定位位置组合,可以在某种程度上弥补双星定位导航系统为有源系统的缺点,并具有较高的精度。     

GPS载波相位观测值中周跳探测与修复的研究

针对GPS载波相位定位中出现的周跳问题,提出一种新的周跳探测方法。基于非差相位观测值线性组合模式,以相位与伪距差法和电离层残差法相结合来探测与修复周跳。通过对同一组无周跳的数据采取人为加入周跳,比较两种周跳探测与修复方法的优缺点,以相位与伪距之差组合为辅助,检查大周跳,用电离层残差组合方法再对双频GPS数据进行进一步的周跳探测和修复。根据实例分析,验证该方法能够快速有效地探测并修复周跳,使双频载波相位法更具有实用性。     

基于惯导／天文高精度定姿方法

研究了利用惯性导航系统与天文导航系统进行组合定姿的方法,构造了惯导/天文组合导航系统的状态方程和量测方程;采用卡尔曼滤波技术设计了惯导/天文组合定姿算法.设计飞行器的典型飞行轨迹,通过数学仿真对该算法的有效性进行了验证.结果表明,天文导航能够有效地补偿惯性导航因陀螺漂移带来的误差,非常适用于飞行器的高精度定姿.     

基于惯导/天文高精度定姿方法

研究了利用惯性导航系统与天文导航系统进行组合定姿的方法;构造了惯导/天文组合导航系统的状态方程和量测方程;采用卡尔曼滤波技术设计了惯导/天文组合定姿算法。设计飞行器的典型飞行轨迹,通过数学仿真对该算法的有效性进行了验证。结果表明,天文导航能够有效地补偿惯性导航因陀螺漂移带来的误差,非常适用于飞行器的高精度定姿。     

一种SINS/GPS深组合导航系统技术问题分析

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。     

改进的GNSS/SINS组合导航系统自适应滤波算法

GNSS/SINS(global navigation satellite system/strapdown inertial navigation system)组合导航系统已得到广泛的应用与研究,当处于复杂环境时,GNSS输出容易出现误差均方差突变、误差均方差缓变、硬故障和软故障4种现象,进而影响组合导航系统滤波精度及载体的导航安全。为了解决上述问题,提出了一种改进的GNSS/SINS组合导航系统自适应滤波算法。首先,利用滤波过程中的观测异常检验统计量与滤波器门限值构建观测因子,然后,将变分贝叶斯原理与抗野值滤波方法结合,设计了改进的组合导航系统自适应滤波算法。仿真实验表明,相较于传统算法,当GNSS输出误差均方差发生变化时,所提算法可将位置精度及速度精度提高11.8%及13.7%;在GNSS输出发生硬故障时,所提算法可将位置精度及速度精度提高70.8%及69.6%。实验结果表明,所提算法具有较强的自适应性,可提升复杂环境下组合导航系统的精度和连续可用性。     

A scheme for weak GPS signal acquisition aided by SINS information

In order to enhance the acquisition performance of global positioning system (GPS) receivers in weak signal conditions, a high-sensitivity acquisition scheme aided by strapdown inertial navigation system (SINS) information is proposed. The carrier Doppler shift and Doppler rate are pre-estimated with SINS aiding and GPS ephemeris, so that the frequency search space is reduced, and the dynamic effect on the acquisition sensitivity is mitigated effectively. Meanwhile, to eliminate the signal-to-noise ratio gain attenuation caused by data bit transitions, an optimal estimation of the unknown data bits is implemented with the Viterbi algorithm. A differential correction method is then utilized to improve the acquisition accuracy of Doppler shift and therefore to meet the requirement of carrier-tracking loop initialization. Finally, the reacquisition experiments of weak GPS signals are implemented in short signal blockage situations. The simulation results show that the proposed scheme can significantly improve the acquisition accuracy and sensitivity and shorten the reacquisition time.     

SDINS/GPS in-flight alignment using GPS carrier phase rate

The alignments of the strapdown inertial navigation system (SDINS) utilizing GPS carrier phase rate measurements is introduced. In this paper, a measurement model of GPS carrier phase rate under two antenna configurations is derived in order to be used for the SDINS alignment process. For in-flight alignment, the performance of the proposed SDINS/GPS integration method is analyzed using the covariance analysis and the overall performance is briefly confirmed by the navigation result of a van test. Furthermore, we find that during in-flight alignment the proposed SDINS/GPS integrated system using GPS carrier phase rate measurements can be implemented in real time because the integer ambiguity problem resulting from carrier phase measurements is avoided.     

水下导航定位技术综述

自主式水下航行器(AUV)作为海洋资源的开发与利用的主要载体,执行任务时需要准确的定位信息. 现有AUV主要采用捷联惯性导航系统(SINS)为主,声学导航和地球物理场匹配导航技术为辅的导航方式. 本文简述水下导航方式基本原理、优缺点和适用场景;探讨各类导航方式包含的关键技术,提高组合导航精度和稳定性. 通过分析现阶段存在问题,展望水下导航的未来发展趋势.      

State transformation extended Kalman filter for GPS/SINS tightly coupled integration

Extended Kalman filter (EKF) is a widely used estimator for integrated navigation systems, and it works well in general situations. However, in adverse conditions such as partially observable environments and highly dynamic maneuvers, the performance of the traditional EKF-based strap-down inertial navigation system (SINS)/GPS integrated navigation system is easily to be affected by the dynamic changes of the specific force, thus leading to the problem of error covariance inconsistency. Though the inconsistency problem can be overcome to some extent if the system matrix, the states and the error covariance matrix are propagated as fast as possible in the SINS calculation rate, the problem cannot be fully solved. State transformation extended Kalman filter (ST-EKF) mechanization, with a new converted velocity error model for the SINS, is proposed, which can also be used to solve the inconsistency problem. In the ST-EKF, the specific force vector in the system error model is replaced by the nearly constant gravity vector for local navigation. Since the propagation and the updating of the ST-EKF can be executed simultaneously in the updating interval, the computation cost is greatly reduced compared with the traditional EKF. Experiments for the GPS/SINS tightly coupled navigation, including linear vibration Monte Carlo test and an unmanned aerial vehicle flight test, are implemented to evaluate the performance of the proposed ST-EKF. The results show that the proposed ST-EKF has superior performance to the traditional EKF, especially in partially observable situations.     

载波相位测量在高精度导航信号监测接收数据处理中的应用

在GPS广域差分系统中,参考站需要进行高精度导航信号监测接收,并获得良好的伪距观测数据。载波相位测量由于其测量精度高且观测噪声小,因此在伪距观测数据处理方面,发挥了重要作用。介绍了载波相位测量在高精度导航监测接收的伪距观测数据处理方面的具体应用,提出了一种综合利用三频电离层残差和裁波相位变化率,来实时可靠地检验并修复周跳的方法。     

Performance of GPS and GPS/SINS navigation in the CE-5T1 skip re-entry mission

A CE-5T1 spacecraft completed a high-speed skip re-entry to the earth after a circumlunar flight on October 31, 2014. In addition to the strapdown inertial navigation system (SINS), a lightweight GPS receiver with rapid acquisition was developed as a navigation sensor in the re-entry capsule. The GPS receiver effectively solved the poor accuracy problem of long-term navigation using only the SINS. In contrast to ground users and low-earth-orbit spacecraft, numerous factors, including high altitude and kinetic characteristics in high-speed skip re-entry, are important for GPS positioning feasibility and were presented in accordance with the flight data. GPS solutions started at nearly 4900 km orbital altitude during the phases of re-entry process. These solutions were combined by an inertial measurement unit in a loosely coupled integrated navigation method and SINS navigation initialization. A simplified GPS/SINS navigation filter for limited resources was effectively developed and implemented on board for spacecraft application. Flight data estimation analyses, including trajectory, attitude, position distribution of GPS satellite, and navigation accuracy, were presented. The estimated accuracy of position was better than 42 m, and the accuracy of velocity was better than 0.1 m/s.     

利用神经网络预测的GPS/SINS组合导航系统算法研究

提出了一种基于神经网络预测的GPS/SINS组合导航系统算法。GPS信号可用时,该算法分别将惯性传感器的输出以及卡尔曼滤波器的输出信息作为神经网络的输入及理想输出信息,并进行在线训练;当GPS信息失锁时,利用已经训练好的神经网络预测各导航参数误差,并校正SINS。地面静态实验与动态跑车实验结果证明了该方法的可行性与有效性。     

Integrated Navigation System and Experiment of a Low-Cost and Low-Accuracy SINS/GPS

When SINS (strap-down inertial navigation system) is combined with GPS, the observability of the course angle is weak. Although the course angle error is improved to some extent through Kalman filtering, the course angle still assumes a divergent trend. This trend is aggravated further when using low-cost and low-accuracy SINS. In order to restrain this trend, a method that uses AHRS to substitute for SINS course angle information is put forward aimed at the hardware component characteristic of the low-cost and low-accuracy SINS including AHRS (attitude and heading reference system) and IMU (inertial measurement unit). Real static and dynamic experiments show that the method can restrain the divergent trend of the navigation system angle effectively, and the positioning accuracy is high.