The integration of strap-down INS and GPS based on adaptive error damping

The concept and results of integration of a strap-down inertial navigation system (INS) based on low-accuracy inertial sensors and the global positioning system (GPS) have been presented in this paper. This system is aimed for the purposes of navigation, automatic control, and remote tracking of land vehicles. The integration is made by the implementation of an extended Kalman filter (EKF) scheme for both the initial alignment and navigation phases. Traditional integration schemes (centralized and cascaded) are dominantly based on the usage of high-accuracy inertial sensors. The idea behind the suggested algorithm is to use low-accuracy inertial sensors and the GPS as the main source of navigation information, while the acceptable accuracy of INS is achieved by the proper damping of INS errors. The main advantage of integration consists in the availability of reliable navigation parameters during the intervals of absence of GPS data. The influence of INS error damping coefficients is different depending on the fact whether the moving object is maneuvering or is moving with a constant velocity at that time. It is proposed that INS error damping gain coefficients generally should take higher values always when GPS data are absent, while at the same time their values in the error model (EKF prediction phase) can be additionally adapted according to the actual values of vehicle acceleration. The analysis of integrated navigation system performances is made experimentally. The data are acquired along the real land vehicle’s trajectory while the intervals of absence of GPS data are introduced artificially on the parts characterized both by maneuver and by constant velocity.     

轮式移动机器人DGPS与图像匹配组合导航技术

利用卡尔曼滤波器将DGPS与SIFT图像匹配算法进行了深组合,同时针对SIFT算法计算量大、计算时间长的缺点,对其进行了改进,经过实验,改进后的算法能够很好的满足系统本身对于实时匹配的要求,提高了系统导航的精度.     

MEMS惯导在旋翼飞行器中导航性能的实验分析

GNSS/MEMS INS组合导航系统是四旋翼飞行器获取位置、速度、姿态的一种重要手段.由于电机转动、气流等因素的影响,旋翼飞行器会出现小幅度的高频抖动,INS机械编排更新率若要满足这一高频运动,将带来沉重的计算负担.在实测分析飞行器抖动特性的基础上,对比了IMU原始采样率不足和仅INS机械编排更新率不足对惯导性能的影响,并分析了四旋翼飞行器所需INS机械编排更新率的底限.实验表明,飞行器高频抖动条件下,由IMU原始采样过低导致的采样混叠会对MEMS惯导性能产生严重影响;但如果原始IMU采样率足够高,而通过求平均(或累加)降采样方法适当地降低机械编排更新率(本文实验条件下可降至20 Hz),则不会明显影响导航精度.本文工作为MEMS惯导用于旋翼飞行器导航提供了参考.     

一种模糊QR滤波及在组合导航中的仿真研究

总结了常用的自适应滤波的方法，并提出了一种基于模糊逻辑的自适应卡尔曼滤波技术，用模糊逻辑自适应推理器来“在线”修正卡尔曼滤波系统噪声协方差Q和测量噪声协方差R，从而使滤波器不断执行最优估计。仿真结果表明该方法可以提高GPS／INS组合导航系统的精度和可靠性。     

基于因子图算法的INS/GPS信息滞后处理方法

针对全球定位系统（GPS）信息滞后导致惯性导航系统（INS）/GPS组合导航系统实时性差的问题,利用因子图算法可以在一个信息融合时刻处理各信息源不同时刻量测信息的特点,提出了一种INS/GPS信息滞后处理方法。在系统接收到GPS信息之前,因子图模型中只添加关于INS信息的因子节点,经增量推理求出组合导航结果,保证系统的实时性。待系统接收到GPS信息之后,再将关于GPS信息的因子节点添加到因子图模型中,修正INS误差,从而保证系统长时间高精度运行。仿真结果表明,当上一时刻实时导航状态量对INS误差修正效果随GPS信息滞后时间变长而逐渐变差时,可以采用上一时刻刚刚完成量测更新的导航状态量实现INS误差的有效修正。因子图算法在保证系统精度的前提下,避免了GPS信息滞后对INS/GPS组合导航系统实时性的不良影响。     

Embedded UAV model and LASER aiding techniques for inertial navigation systems

This work proposes the integration of two aiding information sources to enhance the performance of inertial navigation systems (INS), for precise maneuvering of uninhabited air vehicles (UAVs). A new methodology is derived to exploit vehicle dynamics (VD) information by embeding the VD equations directly in an extended Kalman filter architecture. In this technique, the INS estimates are propagated simultaneously using the VD and the INS differential equations, allowing for the estimation of the INS errors. The proposed technique reduces the computational load associated with classical VD aiding, while retaining the same accuracy enhancements. A LASER range finder sensor is also integrated for precise landing and takeoff maneuvers. Simulation results for the nonlinear dynamics of a Vario X-Treme model-scale helicopter are presented, illustrating the contributions of the proposed aiding techniques for precise UAV navigation.     

Constant-round zero-knowledge proofs of knowledge with strict polynomial-time extractors for NP

Barak and Lindell showed that there exist constant-round zero-knowledge arguments of knowledge with strict polynomial-time extractors.This leaves the open problem of whether it is possible to obtain an analogous result regarding constant-round zero-knowledge proofs of knowledge for NP.This paper focuses on this problem and gives a positive answer by presenting a construction of constant-round zero-knowledge proofs of knowledge with strict polynomial-time extractors for NP.     

Simplified ultra-tightly coupled BDS/INS integrated navigation system

Due to advantages such as low cost, small size, low weight, low power consumption, powerful capability of anti-jamming, and high dynamics, ultra-tightly coupled GNSS/MIMU integrated navigation systems are extensively used in projectile and precision-guided munitions. To overcome the nonlinearity of baseband signal processing and the complexity of the navigation filter, in this paper, we design a novel architecture for the ultra-tightly coupled (UTC) Beidou navigation satellite system (BDS)/INS integration based on the BDS B3 signal, including the combination of code phase and carrier phase dynamics baseband prefilter model, and the navigation filter navigation error propagation and measurement models. To eliminate the clock state components, i.e., the receiver clock offset and clock drift, the pseudorange, delta pseudorange, and delta pseudorange rate residuals obtained from baseband signal prefilters are differenced between two satellites. Based on the BDS/INS simulator, a test system for the UTC BDS/INS integrated navigation system is developed and UTC performance is evaluated. Some preliminary conclusions are formed about the effectiveness of the UTC BDS/INS integration approach.     

无地面基准的相对导航系统设计与仿真

在无地面基准的机群编队飞行JTIDS/INS组合导航系统中,采用新的相对坐标系建立方法克服了绝对位置偏差对相对导航定位精度的影响,同时在原有的TOA观测量的基础上增加了DOA观测量,采用UKF非线性滤波算法进行系统滤波器设计,进一步提高了相对定位精度,并设计了JTIDS/INS组合导航仿真软件平台.仿真结果表明,该方法在收敛速度和定位精度方面都有很好的性能.     

组合导航系统INS/GNSS/SAR及其降阶模型性能的研究

介绍了高阶组合导航系统惯性导航系统 (INS) /全球导航卫星系统 (GNSS) /合成孔径雷达 (SAR)及其降阶模型. 降阶系统的卡尔曼滤波时间大大缩短了, 但其精度并未有大的降低. 仿真结果证明, INS/GNSS/SAR的降阶模型仍可为飞机提供满意的导航精度.     

组合导航系统INS／GNSS／SAR的降阶模型

在利用卡尔曼滤波器对数据进行滤波时,其计算时间是由模型的状态矢量维数n决定的。每一步迭代的计算量等于n^3。状态维数的减会使计算时间大大地缩短。本文首先介绍了高阶组合导航系统INS／GNSS／SAR,然后介绍了其降阶模型。仿真结果证明,INS／GNSS／SAR系统是一个高性能的组合导航系统,其降阶模型可为飞机提供满意的导航精度。     

自适应P值映射的惯性/天文角度组合导航算法

惯性/天文角度组合导航在应用于高动态飞行器时,动态飞行环境变更会导致星光角度观测量发生程度不等的偏差,使得常规组合滤波方法误差显著增大.为此,本文提出了基于P值映射的观测质量自主评估及自适应滤波方法,并应用于惯性/天文角度组合导航系统.该方法根据历年可见导航星情况分解冗余观测子集,再由P值度量其含有观测量偏差的显著性水平.在此基础上,通过遍历每颗导航星所隶属子集得到其观测量质量值,最后对惯性/天文角度组合滤波增益进行自适应调节.仿真结果表明,本文方法能够实现天文高度角观测质量的自主在线评估,有效提高星光观测质量下降情况下惯性/天文角度组合导航的精度和适应性.     

模糊自适应Kalman滤波器在无人机导航中的应用

针对具有不确定动态模型参数的GPS／INS组合导航系统,基于传统Kalman滤波器之上,介绍了一种模糊自适应Kalman滤波器,讨论了GPS／INS组合系统中模型参数不确定性的问题,给出了一种利用模糊自适应滤波方法进行数据融合的无人机定位误差修正方法;仿真结果表明,模糊自适应卡尔曼滤波器对非线性GPS／INS组合系统是很有效的,提高了定位精度。     

GPS信号自适应抗干扰系统

针对GPS卫星信号易受干扰,不稳定的问题,提出INS/GPS组合导航抗干扰的方法并用硬件电路进行实现验证。给出了惯性器件的误差模型,采用松散组合方式,设计卡尔曼滤波器,取姿态、速度、位置的误差作为状态变量。提出以INS与GPS输出的东北天向速度误差作为滤波器观测量的方案。通过计算机的仿真和实验验证,对系统的精度进行了分析,证明该方案是可行的,实现实时滤波计算,并能满足导航的精度要求。     

基于模糊逻辑的自适应卡尔曼滤波在GPS/INS组合导航中的应用

提出了一种利用模糊逻辑控制器来在线调节卡尔曼滤波器的自适应数据融合方法,并着重研究了其在GPS/INS组合导航中的应用．根据位置误差系数和卡尔曼滤波器的新息的统计信息，采用模糊逻辑控制器对卡尔曼滤波器进行连续修正，将卡尔曼滤波器调整到最优状态，从而提高组合导航系统的精度．仿真结果证明这种方法比标准卡尔曼滤波具有更高的精度．     

Optimizing neuro-fuzzy modules for data fusion of vehicular navigation systems using temporal cross-validation

The last two decades have shown an increasing trend in the use of positioning and navigation technologies in land vehicles. Most of the present navigation systems incorporate global positioning system (GPS) and inertial navigation system (INS), which are integrated using Kalman filtering (KF) to provide reliable positioning information. Due to several inadequacies related to KF-based INS/GPS integration, artificial intelligence (AI) methods have been recently suggested to replace KF. Various neural network and neuro-fuzzy methods for INS/GPS integration were introduced. However, these methods provided relatively poor positioning accuracy during long GPS outages. Moreover, the internal system parameters had to be tuned over time of the navigation mission to reach the desired positioning accuracy. In order to overcome these limitations, this study optimizes the AI-based INS/GPS integration schemes utilizing adaptive neuro-fuzzy inference system (ANFIS) by implementing, a temporal window-based cross-validation approach during the update procedure. The ANFIS-based system considers a non-overlap moving window instead of the commonly used sliding window approach. The proposed system is tested using differential GPS and navigational grade INS field test data obtained from a land vehicle experiment. The results showed that the proposed system is a reliable modeless system and platform independent module that requires no priori knowledge of the navigation equipment utilized. In addition, significant accuracy improvement was achieved during long GPS outages.     

Magnetic compass fault detection method for GPS/INS/magnetic compass integrated navigation systems

This paper proposes a magnetic compass fault detection method for GPS/INS/Magnetic compass integrated navigation systems. The fault is assumed to be caused by the hard iron and soft iron effect and modeled as an abrupt change in the magnetic compass output. In order to detect the fault, a test statistic related with only azimuth error measurement is determined. When a fault is detected, the GPS/INS/Magnetic compass integrated navigation system is changed into a GPS/INS integrated navigation system mode. In order to show the validity of the proposed method, computer simulation and van testing are carried out. The simulation and van test results show that the proposed navigation system gives more accurate outputs than the GPS/INS/Magnetic compass without the proposed method.     

弹道导弹惯性/双星/天文组合导航系统研究

弹道导弹飞行特点对其导航系统提出了较高的技术要求,因此提出一种惯性/双星/天文组合导航方案对弹道导弹实时估计和修正导航误差,提高导航精度,该组合导航方案以惯性导航系统与天文导航系统的姿态角差值、惯性导航系统与双星定位导航系统的位置差值作为观测量,建立弹道导弹导航系统的数学模型和观测方程,以无反馈模式联邦滤波器在线估计弹道导弹导航参数误差值.通过计算机仿真并分析仿真结果:和惯性导航系统相比较,这种组合导航系统可以提高弹道导弹导航精度,适合弹道导弹组合导航.     

UKF在INS/GPS直接法卡尔曼滤波中的应用

提出将Unscented卡尔曼滤波(UKF)用于INS/GPS组合导航系统的直接法卡尔曼滤波,避免了对非线性的系统状态方程进行线性化.以INS输出的导航参数及平台误差角等作为系统状态,惯导力学编排方程和姿态误差方程作为系统状态方程,GPS输出的导航参数作为量测,采用UKF方法对系统导航参数直接进行估计.仿真结果表明,UKF方法有效地解决了直接法卡尔曼滤波中系统状态方程的非线性问题,并使INS/GPS组合导航系统具有较高的导航定位精度.     

基于双DSP的飞艇组合导航系统设计

在分析某小型平流层验证飞艇实际应用的基础上，介绍了适合该艇的INS/GPS组合导航系统基本原理。结合高性能定点DSP TMS320F2812和双口RAM CY7C028的特点，设计了以双DSP芯片为计算核心的导航计算机，给出了组合导航系统的硬件框图与软件流程图。飞行试验结果显示该系统具有良好的实时性和满足设计要求的测量精度，为平流层飞艇组合导航系统的设计提供了一定的理论基础。