MEMS惯导在旋翼飞行器中导航性能的实验分析

GNSS/MEMS INS组合导航系统是四旋翼飞行器获取位置、速度、姿态的一种重要手段.由于电机转动、气流等因素的影响,旋翼飞行器会出现小幅度的高频抖动,INS机械编排更新率若要满足这一高频运动,将带来沉重的计算负担.在实测分析飞行器抖动特性的基础上,对比了IMU原始采样率不足和仅INS机械编排更新率不足对惯导性能的影响,并分析了四旋翼飞行器所需INS机械编排更新率的底限.实验表明,飞行器高频抖动条件下,由IMU原始采样过低导致的采样混叠会对MEMS惯导性能产生严重影响;但如果原始IMU采样率足够高,而通过求平均(或累加)降采样方法适当地降低机械编排更新率(本文实验条件下可降至20 Hz),则不会明显影响导航精度.本文工作为MEMS惯导用于旋翼飞行器导航提供了参考.

The experimental analysis of the navigation performance of MEMS INS on rotor aircrafts

GNSS/MEMS INS integrated navigation system is an important way to obtain the position,velocity and atti-tude of four rotor aircrafts. Because of the influence of the factors such as motor rotation and airflow turbulence,there is small magnitude,high frequency vibrations on the body of rotor aircrafts. This would lead to heavy calculation bur-den if the INS mechanization update rate fits the requirement of sensing the high frequency vibration. Based on the analysis to the vibration characteristics from experimental data,the difference of two cases is compared in terms of the influences on inertial navigation.One is that the original sampling rate of IMU data is insufficient;the other is that the original sampling rate of IMU data is sufficient but be down-sampled intentionally to a low rate by averaging (or integral)so as to reduce the INS mechanization rate. The result of experiment shows that on the condition of the rotor aircraft vibration,insufficient original sample rate of IMU will cause sampling aliasing and crash INS mechani-zation and GNSS/INS integration. But the proper reductionof the INS mechanization update rate as low as 20 Hz will not cause any noticeable degradation of the navigation accuracy under the test condition in this paper. The analysis and results in this paper provide reference parameters in applying MEMS INS to rotor aircraft navigation.