光纤陀螺惯性测量单元数据频混误差仿真分析

导航计算机对光纤陀螺（FOG）测量数据的异步重采样将引起数据的频谱混叠误差。基于FOG信号检测特点，以FOG闭环输出数据更新率、惯性测量单元（IMU）异步通信定时脉冲频率为参量，以载体的正弦干扰频率为变量，以导航计算机接收信号直流（DC）分量的幅值误差抑制为目标，建立了仿真模型。分析了现有内插抽取方案和滑动滤波方案的数据频混误差及延时特性。提出了类盲发变滑窗长度方案，抑制了频混误差响应谱对滑窗长度的敏感性。仿真结果表明，相比滑窗长度偏离最优值4%的滑动滤波方案，变滑窗长度方案的误差最大值从0.056 85降至0.009 737，能更好地适应定时脉冲信号频率抖动或切换的工程应用需求。

Simulation and analysis of data frequency mixing errors in IMU based on FOG

The asynchronous resampling of fiber optic gyroscope (FOG) output data by navigation computer can cause frequency mixing errors. Based on the characteristics of FOG signal detection, a simulation model was established using the update rate of FOG closed-loop output and the resampling frequency of inertial measurement unit (IMU) as parameters, the sinusoidal noise frequency of vehicle as a variable, and the decrease of signal direct current (DC) amplitude error received by navigation computer as the target. The frequency mixing errors and delay characteristics of interpolation and decimation scheme and sliding filter scheme were analyzed. A variable sliding window length scheme was proposed and the sensitivity of error response spectrum to sliding window length was suppressed. The simulation results show that the maximum error of the variable sliding window length scheme is reduced from 0.056 85 to 0.009 737 compared with the sliding filter scheme with sliding window length's deviation from the optimal value of 4%. Besides, the proposed scheme can better accommodate the engineering requirement of timing pulse frequency dithering or switch.