无人机GNSS/IMU组合导航系统完好性监测方法

Integrity monitoring method for GNSS/IMU integrated navigation system of UAV

针对民用无人机组合导航系统中,全球导航卫星系统(GNSS)和惯性测量单元(IMU)均存在故障风险的情况,提出一种兼顾GNSS和IMU故障风险的组合导航系统完好性监测方法。该方法根据故障检测结果建立完好性风险模型,设计完好性风险需求分配方案并建立各故障模式的保护级反演模型,利用滤波新息表达过去历元故障偏差对定位误差的影响,解决故障起始历元和故障偏差取值未知的前提下保护级反演难题。典型无人机低空飞行作业场景下的仿真结果表明:该方法设计的保护级反演模型计算所得保护级可跟踪定位误差的变化趋势,对定位误差形成包络,从而保障组合导航系统的完好性。

Both Global Navigation Satellite System(GNSS)and Inertial Measurement Unit(IMU)failure risks should be considered for civil UAV integrity monitoring.An autonomous integrity monitoring method for the GNSS/IMU inte⁃grated navigation system is proposed considering the risks of both IMU and GNSS failures.According to fault detection results,an integrity risk model is established,an integrity risk demand allocation scheme is designed,and a protection level inversion model of each fault mode is established.Filter innovation is used to express the influence of past epoch fault deviation on positioning error,and the problem of protection level inversion is solved under the premise that the fault starting epoch and fault deviation are unknown.The results of simulation at typical UAV low-altitude flight sce⁃narios show that the protection level of the proposed algorithm can track the changing trend of positioning errors and form a safety overbounding for positioning errors,thus ensuring the integrity of the integrated navigation system.