航姿参考系统的改进杆臂效应补偿方法

Improved method of lever arm effect compensation for AHRS

振动环境下叠加在航姿参考系统(AHRS)加速度计敏感轴上的杆臂效应会对加速度计测姿精度造成极大的影响.本文对杆臂效应处理算法中的低通滤波法和力学补偿法进行分析.低通滤波法滤除杆臂效应会有整流误差残存.力学补偿法对杆臂效应中向心加速度项的补偿受限于陀螺测量精度,对杆臂效应中切向加速度项的补偿会因为直接对角速度微分求取角加速度造成误差激剧放大.针对低通滤波法与力学补偿法各自存在的不足,提出一种改进的杆臂效应补偿方法.对杆臂效应中的向心加速度项的补偿,设定角频率阈值作为判定值.在低于给定角频率阈值工况下采用低通滤波法,而在高于给定角频率阈值工况下采用力学补偿+低通滤波法.对杆臂效应中的切向加速度项的补偿,提出2种多加速度计构型,根据加速度计构型中各加速度计输出值,构造解析公式求解角加速度,避免直接微分法造成的误差放大.通过对改进补偿方法的理论推导、分析和仿真,并与低通滤波法和力学补偿法相对比,改进补偿方法显著地提高了杆臂效应误差补偿精度.

The lever arm effect superimposed on the accelerometer sensitive axis of the attitude and heading reference system(AHRS)under vibration environment will greatly affect the accuracy of the attitude measurement based on the accelerometer.This paper analyzes the low-pass filtering method and the mechanical compensation method in the lever arm effect processing algorithms.The low pass filtering method will have rectification error residual.The compensation of the centripetal acceleration term in the lever arm effect by the mechanical compensation method is limited by the gyro measurement accuracy.Meanwhile,the difference operation of angular velocity will greatly enlarge the compensation error of tangential acceleration term in lever arm effect.Aiming at the shortcomings of the low-pass filtering method and the mechanical compensation method,this paper proposes an improved compensation method of lever-arm effect.For the centripetal acceleration term,the angular frequency threshold is set as decision value.When the angular frequency is lower than the given angular frequency threshold,the low-pass filtering method is adopted;and when the angular frequency is higher than the given angular frequency threshold,the mechanical compensation+low-pass filtering method is adopted.For the tangential acceleration term,the angular acceleration can be solved analytically by multiple accelerometers,which can avoid the error amplification caused by differential operation.Through the theoretical derivation,analysis and simulation,the improved compensation method significantly improves the compensation precision of the lever arm effect,compared with the low-pass filtering method and the mechanical compensation method.