Design and application of single-antenna GPS/accelerometers attitude determination system

In view of the problem that the current single-antenna GPS attitude determination system can only determine the body attitude when the sideslip angle is zero and the multiantenna GPS/SINS integrated navigation system is of large volume, high cost, and complex structure, this approach is presented to determine the attitude based on vector space with single-antenna GPS and accelerometers in the micro inertial measurement unit （MIMU）. It can provide real-time and accurate attitude information. Subsequently, the single-antenna GPS/SINS integrated navigation system is designed based on the combination of position, velocity, and attitude. Finally the semi- physical simulations of single-antenna GPS attitude determination system and single-antenna GPS/SINS integrated navigation system are carried out. The simulation results, based on measured data, show that the single-antenna GPS/SINS system can provide more accurate navigation information compared to the GPS/SINS system, based on the combination of position and velocity. Furthermore, the single-antenna GPS/SINS system is characteristic of lower cost and simpler structure. It provides the basis for the application of a single-antenna GPS/SINS integrated navigation system in a micro aerial vehicle （MAV）.     

Geometric dilution of precision for GPS single-point positioning based on four satellites

To improve the positioning accuracy in GPS point positioning, the geometric dilution of precision （GDOP） including HDOP, VDOP, TDOP, PDOP is commonly considered. The properties of the DOP for the GPS satellite navigation system are studied and the coordinate system is improved in order to decrease the amount of variables. In the end, by simulation and discussing the results, the corresponding conclusions are presented.     

GPSNISNAV integrated relative navigation and attitude determination system for ultra-close spacecraft formation flying

For the improvement of accuracy and better fault-tolerant performance, a global position system (GPS)/vision navigation (VISNAV) integrated relative navigation and attitude determination approach is presented for ultra-close spacecraft formation flying. Onboard GPS and VISNAV system are adopted and a federal Kalman filter architecture is used for the total navigation system design. Simulation results indicate that the integrated system can provide a total improvement of relative navigation and attitude estimation performance in accuracy and fault-tolerance.     

Practical integrated navigation fault detection algorithm based on sequential hypothesis testing

In detecting system fault algorithms,the false alarm rate and undectect rate generated by residual Chi-square test can affect the stability of filters.The paper proposes a fault detection algorithm based on sequential residual Chi-square test and applies to fault detection of an integrated navigation system.The simulation result shows that the algorithm can accurately detect the fault information of global positioning system(GPS),eliminate the influence of false alarm and missed detection on filter,and enhance fault tolerance of integrated navigation systems.     

视觉导航辅助的自主空中加油建模与仿真

研究了基于视觉导航方式的自主空中加油（AAR）建模问题。分析了影响自主空中加油对接阶段性能的两个最重要因素——相对距离的测量和风扰动,引入了多个摄像机,建立了适合AAR的视觉导航系统模型,建立了大气扰动和尾流等风扰动下的飞行器模型,用三次多项式规划了对接阶段的航迹并设计了LQR航迹跟踪控制律。对接过程仿真表明,视觉导航的估计精度和飞行控制律性能很好地满足了空中加油的要求。

Abstract：

The modeling problem of autonomous aerial refueling based on vision navigation was researched.The two most important factors affecting the performance of AAR were analyzed,which were the measure of the relative distance and wind disturbance.The vision navigation system suitable for AAR was adopted and modeled using multiple cameras.The dynamic model of plane with the effect of wind was built.Path of docking was planed using cubic interpolators and tracking control was designed with LQR.The result of simulation shows that the accuracy of vision navigation system and the performance of control law can meet requires of aerial refueling.     

多系统组合导航仿真器设计

通过分析多种导航系统各自的特点,从对惯性导航系统误差状态的可观测性出发,考虑到校正方式的自由选择、滤波算法的不同采用以及信源的有效性检验等因素,建立了多系统组合导航模型,并采用Simulink工具搭建了该系统仿真器模块。仿真器能够自动地将处于工作状态的导航子系统按照最优准则组合起来,不但能够独立地执行,而且可以与其它导航系统仿真器一起集成在RT-LAB实时环境下正确运行。仿真结果表明,在满足精度的前提下,该系统具有导航信息的冗余性、互补性、容错性等良好性能。

Abstract：

By studying on observable of INS error states and the characteristic of each navigation system,considering the choice of the revision way,the adoption of different filtering algorithms and the verification of the information source,a multi-system integrated navigation model was built.The simulator module of this model was constructed by Simulink tools in MATLAB,which could integrate all active navigation subsystems automatically.The simulator not only could execute independently,but also could run accurately on RT-LAB real-time environment combined with other navigation system simulators.The simulation result indicates that the simulator has many good performances which include the flexibility in integration pattern of navigation systems,the redundancy and complementarity of navigation information,the fault tolerance of the whole system,etc.     

Research on FMC analytic algorithm of PBN track transition coding

Airborne navigation database(NavDB) coding directly affects the result of analysis on the instrument flight procedure by the modern aircraft flight management computer(FMC). A reasonable flight track transition mode can improve the track tracking accuracy and flight quality of the aircraft. According to the path terminator(PT) and track transition characteristics of the performance based navigation(PBN) instrument flight procedure and by use of the world geodetic system(WGS)-84 ellipsoidal coord...     

Accuracy improvement of GPS/MEMS-INS integrated navigation system during GPS signal outage for land vehicle navigation

To improve the reliability and accuracy of the global positioning system (GPS)/micro electromechanical system (MEMS)inertial navigation system (INS) integrated navigation system,this paper proposes two different methods.Based on wavelet threshold denoising and functional coefficient autoregressive (FAR) modeling,a combined data processing method is presented for MEMS inertial sensor,and GPS attitude information is also introduced to improve the estimation accuracy of MEMS inertial sensor errors.Then the positioning accuracy during GPS signal short outage is enhanced.To improve the positioning accuracy when a GPS signal is blocked for long time and solve the problem of the traditional adaptive neuro-fuzzy inference system (ANFIS) method with poor dynamic adaptation and large calculation amount,a self-constructive ANFIS (SCANFIS) combined with the extended Kalman filter (EKF) is proposed for MEMS-INS errors modeling and predicting.Experimental road test results validate the efficiency of the proposed methods.     

Intelligent fault-tolerant algorithm with two-stage and feedback for integrated navigation federated filtering

In order to take full advantage of federated filter in fault-tolerant design of integrated navigation system, the limitation of fault detection algorithm for gradual changing fault detection and the poor fault tolerance of global optimal fusion algorithm are the key problems to deal with. Based on theoretical analysis of the influencing factors of federated filtering fault tolerance, global fault-tolerant fusion algorithm and information sharing algorithm are proposed based on fuzzy assessment. It achieves intelligent fault-tolerant structure with two-stage and feedback, including real-time fault detection in sub-filters, and fault-tolerant fusion and information sharing in main filter. The simulation results demonstrate that the algorithm can effectively improve fault-tolerant ability and ensure relatively high positioning precision of integrated navigation system when a subsystem having gradual changing fault.     

Fast fine acquisition algorithm of GPS receiver aided by INS information

Acquisition time of global position system (GPS) receiver, which is the main factor contributes to time to first fix (TTFF), can be shortened by estimating the Doppler frequency shift through external inertial navigation system (INS) information and almanac data and reducing the searching area. The traditional fast acquisition is analyzed, the fast acquisition of the GPS receiver aided is presented by INS information, and the signal is fine captured by spectrum zooming. Then the algorithm is simulated by sampled GPS intermediate frequency (IF) signal and the result verifies that this acquisition can dramatically improve the capability of GPS receiver and reduce its acquisition time.     

分布式INS/GPS组合导航仿真器开发

在研制INS/GPS组合导航系统之前建立INS/GPS组合导航仿真器系统是节约研制成本和缩短开发周期的有效途径,利用多台计算机搭建分布式组合导航仿真器能够更逼真的对系统进行仿真。该仿真器由GPS仿真子系统、INS仿真子系统和INS/GPS组合导航仿真子系统三大部分组成,对该系统之间的硬件接口设计、算法和软件开发进行了论述,对比较难解决的系统同步问题提出了解决方法。最终的设计方案已成功的应用于某飞机仿真系统中。     

组合导航系统故障诊断方法设计与实现

提出了一种组合导航系统的故障诊断方法,根据不同导航子系统的特点,采用基于双状态递推器的卡方检验法、似然比检验法以及空间解析几何法分别对SINS/GPS,ADS和SINS/ADS/DME系统进行故障诊断。另外,作者利用VC实现了一套用于进行组合导航的系统故障诊断的方法,并进行了实时的诊断验证实验,其结果表明根据经验、卡方分布表以及误差标准等因素考虑选择的阈值结合相应算法的诊断准确性高,并且抗野值干扰能力强。     

基于自适应航迹融合算法的GPS／SINS紧组合导航系统研究

针对开环校正GPS/INS组合导航系统卡尔曼滤波器在长时间工作条件下滤波精度下降的问题,提出了基于自适应航迹融合算法的紧组合GPS/INS导航系统方案.设计了一个与GPS/INS滤波器并行的独立GPS滤波器,利用自适应航迹融合算法对两个滤波器输出的局部航迹进行融合,从而得到系统航迹.数学仿真结果表明,该方案能够有效提高导航系统的导航精度和容错能力.     

基于分层融合结构的组合导航系统仿真分析

依据多传感器信息融合理论，将分层融合结构是应用到组合导航系统中，并与目前广泛应用的联合滤波算法（Federated Filtering)进行了比较。对INS/GPS/Doppler系统的仿真结果表明，有序分层融合结构可有效地应用于多传感器组合导航系统，并且导航精度优于联合滤波的结果。     

运载火箭导航计算子系统建模与仿真

以国产CZ系列运载火箭为研究对象，在分析火箭导航计算子系统数学模型的基础上，建立导航计算系统的仿真模型并进行了全数字仿真。先将子系统分解成一系列功能相对独立的模块。如地球引力加速度计算模块、速度计算模块、位移计算模块等。采用MATLAB／Simulink对这些功能模块建立仿真单元模型，然后再进行仿真单元模型的集成。构建出运载火箭导航计算子系统的仿真模型，输入该型号运载火箭实际飞行中采样得到的加速度计输出信号进行仿真验证，得到的速度与位移变化仿真结果与实际情况基本相符，证明仿真模型建立正确、方法采用得当、有效。     

声学多普勒速度仪陆上仿真方法研究及其实现

随着声学测速精度的不断提高,声学多普勒速度仪已应用于多种载体的水下导航。根据多普勒速度仪的陆上仿真的需要,研究了多普勒速度仪的测速原理及矢量合成原理和坐标变换方法,推导了深度仿真和速度仿真公式,给出了仿真方法,同时设计了一种基于PXI的波形采集和回放模块,试验证明了所推导的公式的正确性和仿真方法的有效性。这种仿真方法对于不同类型的声学多普勒速度仪具有通用性,仿真电路实现了模块化设计,适用于其它的工程应用。     

基于降阶模型的GPS/PINS组合导航试验研究

卡尔曼滤波器的计算负担与其阶数的三次方成正比，为了研究GPS／PINS（Platform Inertial Navigationsystem）组合导航系统的性能，基于卡尔曼滤波器降阶模型，设计了GPS／PINS实时组合导航跑车试验系统，跑车试验过程中实时采集GPS的位置和速度信息以及平台惯组的加速度和姿态角等信息，进行滤波解算，实时输出解算结果。为评估二者的组合效果，同时接入差分高精度GPS，跟组合结果进行比对。试验结果表明，基于降阶模型的组合导航系统可以满意的完成导航任务。     

船用平台式INS光学标校初始对准方法研究

为了解决航海型平台式惯性导航系统（INS）非自主式初始对准问题，建立了不同观测量条件下统一的INS初始对准方程。通过系统可观测性分析，得出增加外部姿态角的观测信息将有效提高INS平台失准角和惯性元件误差的估计能力的结论。设计出一种独特的可测量低动态载体两维姿态的高精度光学测量系统（OCS）用以提高航海型平台式INS初始对准精度。建立OCS／GPS／计程仪（LOG）／INS初始对准卡尔曼滤波器，并进行了基于部分试验数据的数字仿真，与传统的基于位置和速度的GPS／LOG／INS初始对准方法相比，基于OCS的系统不仅缩短了对准时间，还有效改善了系统惯性元件的误差估计精度。     

卫导辅助下的舰船捷联惯导航行间粗对准方法

针对舰船捷联惯导在行进间难以实现自主的粗对准,研究了在动基座下的舰船捷联惯导的粗对准,提出了一种采用全球定位系统(global position system, GPS)辅助舰船捷联惯导系统在运动中实现粗对准的方法。该方法利用GPS获得的位置信息,通过对捷联惯导基本方程的数值积分,计算捷联姿态矩阵。相比于借助外测速度实现粗对准,该方法借助GPS获得的位置信息实现粗对准,不需要装备多普勒测速仪。因此,该方法成本更低、具有实用性。经试验验证,该方法能使舰船捷联惯导在航行间快速的计算出初始捷联矩阵,满足姿态误差角小于1°的精度要求。