重力扰动矢量对惯导系统影响误差项指标分析

摘要

针对制约现有惯导系统精度提升的重力扰动矢量误差项问题，从惯导系统误差模型入手，着重分析了重力扰动矢量水平分量（垂线偏差）在导航系统中的误差传播特性，利用简化的垂线偏差统计模型推导出导航系统位置误差均方差表达式；通过现有全球重力场高阶球谐模型（EGM2008），分析了垂线偏差全球均方差水平引起的惯导系统在典型载体运行速度下位置误差项大小，进而给出了垂线偏差补偿的误差项指标，在此基础上，分析了EGM2008在惯导系统中的适用性，结果表明，当EGM2008模型阶数小于12阶时才能满足导航系统计算资源要求，模型补偿精度为5.86，适用于位置误差要求小于0.8 nm/h的惯导系统。%The characteristics of gravity disturbing vector errors and their influences on navigation algorithm are studied for suppressing the navigation errors. Based on the error model of the inertial navigation systems (INS), the position error excited by horizontal component of gravity disturbing vector is studied, and according to which, the position RMS is derived. The global average variance of vertical deflection is used to quantify the vertical-deflection-induced position RMS under different velocities of vehicle set. Then the indexes of vertical deflection influencing on INS are proposed. Experiments with digital signal processor show that the requirements of computing resources of the navigation system can only be satisfied when with <12-order spherical harmonic gravity model EGM2008, and the compensation precision of the model is 5.86. This gravity model can be applied to such INS as the position error is <0.8nm/h.