激光陀螺机械抖动偏频对等效转动矢量姿态计算的影响

Influence Analysis of Laser Gyro Mechanical Dithering on Attitude Computation Using Rotation Vector Algorithm

研究了激光陀螺机械抖动偏频影响等效转动矢量姿态计算精度的机理。用双子样N次迭代算法推导了载体实际姿态角运动与机械抖动发生谐振时产生的姿态计算误差项,指出其误差作用机理与惯性导航比力方程计算中划摇误差的相似性。针对三轴激光陀螺共一个机械抖动轴和3个单轴激光陀螺构成惯性组合两种情况进行了讨论。根据对静态条件下惯性组合中激光陀螺采样信号的功率谱密度分析,指出当采样频率较低时,会产生与抖动有关的低频周期分量,与低频的载体姿态运动谐振将产生姿态计算误差,应尽量提高采样频率及等效转动矢量计算频率。

The scheme by which the laser gyro mechanical dithering affects the accuracy of the attitude compu tation using rotation vector algorithm is researched in this paper. The attitude computation error caused by the resonance between the body attitude movement and the mechanical dithering is investigated using two sample N times iteration algorithm. The comparability between this error and the sculling effect in specific force transformation is proposed. Two situations, that only one dither mechanism is used for the three axis RLG configuration and that the IMU is composed of three single axis laser gyros, are discussed. The power spectral density of the laser gyro sampling in IMU is analyzed under static state. It is shown that the low frequency periodic error caused by low frequency sarupling of the dithered gyro will resonance with the low frequency body attitude movement. In this case attitude computation error will occur. It is pointed out that the frequency of the sampiing and the rotation vector updating should be high.