GPS/捷联惯性组合导航系统的性能研究

Performance Study of an Integrated NAVSTAR GPS/SINS Navigation System

采用卡尔曼滤波器进行最优组合的GPS/捷联惯性组合导航系统是一种精度高、成本效益好、功能可靠的导航系统。它既能增强GPS接收机的抗干扰能力又能抑制惯导的积累误差。机动飞行和干扰环境下所进行的模拟计算表明,采用C/A码GPS接收机和低精度(0.1°/h陀螺,1×10^(-3)加速度计)捷联惯导所组成的系统,定位精度可达20m(1σ),速度精度约为0.1m/s(1σ)。与纯惯导相比,性能精度约提高2个数量级。系统具有对惯性元件进行测漂补偿,对GPS用户钟差进行估计校正和实现惯性平台空中对准的功能,能缩短地面准备时间,提高飞行器的快速反应能力,是一种在航空、航天等领域中有着广阔应用前景的导航定位系统。

Integration of a Strapdown Inertial Navigation System (SINS) with a Glo-bal Positioning System (GPS) receiver presents many advantages. With thisintegrated design approach, the authors overcome some of the recognized limi-tations of an INS such as: (1) unbounded position error and pilot initialization,(2) stand-alone GPS limitations such as poor satellite geometry and dynamicnoise. This paper discusses the synergistic effect obtainable with such an approach,and emphasizes Kalman filter design, system configurations and performanceevaluation. This paper analyzes a specific example and the key features of suchan analysis are: (1) A comprehensive digital computer simulation is developed. (2) Covariance analysis results are presented to demonstrate the impro-ved performance of the proposed integrated system composed of medium accu-racy strapdown instrument package and C/A Code GPS receiver under diffe-rent flight scenarios. In the covariance analysis just mentioned, the authors show that beforeloss of the GPS signal, the navigation errors are bounded by the GPS solutionaccuracy. North, East and vertical velocity errors are 0.07, 0.1 and 0.08m/s(1σ), respectively. North and East positions and altitude errors are 11, 15 and20m (1σ) for precise position locating. During the 180sec GPS signal outagedue to aircraft maneuvers and/or radio noise jamming, the position error inc-reases from 18m to 80m, the horizontal velocity error goes from 0.1m/s to0.7m/s. As a result of inertial velocity aiding, fast reacquiring of the jammedor masked satellite signal can be realized, the navigation error quickly returnsto its full operational values. Accurate and rapid INS in-flight alignment canbe accomplished in aircraft straight flight and turns by using GPS measure-ments. Initial rms azimuth alignment errors are reduced from about 35 arcminto about 2, 5 arcmin in less than 3 minutes. In this paper the authors show that the present integrated system approachallows the error estimation filter design to be less dependent on strict modellingof error dynamics, and that the system can be implemented with a modulardesign approach and is cost-effective and reliable.