捷联惯导系统IMU误差特性分析

Analysis of IMU Error Characteristics in Strapdown Inertial Navigation System

为了优化捷联惯导系统惯性测量单元性能,首先,从惯性导航系统工作原理出发,细致梳理捷联惯导误差模型,对惯性测量单元常见误差源分类,重点分析主流民航客机机型捷联惯导惯性测量单元的误差特性;然后,对由5个直线段和4个转弯组成的矩形起落航线,在无误差的理想模式和设置导航级捷联惯导惯性测量单元误差参数模式,分别进行轨迹仿真;最后,在飞行轨迹的姿态、速度、位置误差三维方向对比分析。结果表明,IMU误差诱使飞行轨迹随时间有偏离趋势,高度误差波动始终非常平稳,水平方向误差在一定时间后大幅度发散,表现出惯性导航性能的固有缺陷,即误差随时间的推移逐渐累积,会在一段平稳时间后呈发散趋势。因此在实际使用惯导中可以使用特殊的算法和硬件平台以延长误差发散之前的时间,也可以通过与GPS等数据进行组合导航的方式抑制其发散趋势。研究结果为进一步进行组合导航算法优化奠定基础。

In order to optimize the performance of IMU(inertial measurement unit)of the strapdown inertial navigation system,starting from the principle of inertial navigation system,the strapdown inertial navigation error model is carefully sorted,the common error sources of inertial measurement unit are classified,and the error characteristics of the strapdown inertial measurement unit of the existing mainstream civil aircraft are analyzed,Then,the trajectory simulation of the rectangular takeoff and landing route consisting of 5 straight segments and 4 turns is carried out in the error-free ideal mode and the error-parameter mode of the navigation cascades inertial measurement unit.Finally,the attitude,velocity and position error of flight trajectory are compared and analyzed.The results show that the IMU error induces the flight trajectory to deviate with time,the altitude error fluctuation is always very stable,and the horizontal error diverges greatly after a certain period of time,which shows the inherent defect of inertial navigation performance.The error accumulates gradually with the passage of time,and will diverge after a stable period of time.Therefore,in actual use of INS,special algorithms and hardware platforms can be considered to extend the time before the error divergence,and the divergence trend can be suppressed by combining navigation with GPS and other data.The results lay a foundation for further optimization of integrated navigation algorithm.