GNSS/IMU组合导航观测量丢弃策略

Measurement discarding strategy for GNSS/IMU integration

传统的GNSS/IMU(global navigation satellitesystem/inertial measurement unit)组合导航系统采用固定速率更新策略,平等地对待每一个观测量。因而在受到突发干扰情况下,精度恶化的观测量可能影响到更新后的组合导航结果的精度。该文提出一个双门限的观测量丢弃策略,它同时监控估计量的误差累计程度和观测量的恶化程度。当估计量误差很低或者观测量恶化很严重时,把观测量丢弃掉,使组合导航系统工作在INS(inertial navigation system)单独导航模式。真实的外场试验结合仿真干扰表明:含观测量丢弃策略的扩展Kalman滤波(EKF)跟传统的固定更新速率EKF相比,在干扰条件下具有更低的误差。

In conventional GNSS/IMU（global navigation satellite system/inertial measurement unit） integration,the updating frequency is constant and measurements are used to execute updates when they are received.As a result,the integration accuracy is vulnerable to measurement degradation caused by GNSS signal outages.This paper presents a double-threshold measurement discarding strategy,which monitors both the state estimation and the measurement quality.Measurements will be discarded and the integrated system will work in the INS（inertial navigation system） mode alone when the state estimation is accurate enough or the measurements are less accurate.Real data tests and simulations confirm that the measurement discard strategy using EKF（extended Kalman filtering） has better navigation performance in measurement degradation situations.