载体运动对双轴连续旋转调制式惯导方案误差的影响

Influence of body dynamics on the error of INS scheme with dual-axis continuous autocompensation technique

引入系统级旋转自补偿技术可以提高惯性导航系统的精度,该技术是指对整个IMU施加旋转运动从而改变元器件的工作方式,使元件误差得到调制,在进行积分时调制后的误差在一个周期内得到抵消。在捷联式惯导系统中,当载体处于动态时,标度因数误差和安装误差与惯性传感器的输出产生耦合,旋转调制对系统的补偿效果将受到影响。改进的途径一是提高元件标度因数稳定性,减小系统安装误差角;二是隔离载体运动,即减小陀螺仪和加速度计的输出值。本文通过对比分析在静态和动态条件下双轴连续旋转调制式惯导的误差方程,解释了载体运动对旋转调制效果的影响机理,并通过数字仿真验证了载体运动对系统补偿效果的影响。分析和仿真发现,在静态和动态条件下旋转调制都可以提高系统的精度,而在静态条件下或者在通过环架结构隔离了载体运动后旋转调制的效果相对于动态下有较为明显的提高。

Systemic rotation autocompensation technique can improve the precision of inertial navigation system.This technique introduces gimbals to allow IMU undergo intentionally devised mechanical motions.The operating mode of the inertial sensors is changed,and the low frequency contents of their output errors are shifted to sinusoidal form.The integration process will attenuate the effect of the sinusoidal errors.When the system applies the strapdown configuration,the coupling of the scale factor and misalignment instability with craft dynamics may degrade the autocompensation.Two approaches are often used to address the degradation,to improve the stability of the scale factor and misalignment,or to isolate the craft dynamics.The dual-axis continuous rotation autocompensation mechanization is introduced in this paper.The rotatory INS＇s error equations are analyzed when the craft is in static and dynamic state respectively.How the craft dynamics degrade the autocompensation is explained.The digital simulation is designed and the theoretical analysis is validated.Based on the theoretical analysis and digital simulation,it is concluded that dual-axis continuous rotation autocompensation technique can improve the system precision on either static or dynamic conditions.When the craft is in static state or is isolated from body dynamics by gimbal system,the system precision is much better than that in other conditions.