一种实时移除MEMS陀螺仪噪声的精准航姿技术

An accurate orientation technique by removing MEMS gyroscope’s noises in real time

MEMS-IMU包括三轴陀螺仪和三轴加速度计,陀螺仪的噪声导致MEMS-IMU的航姿不精确,并由此导致外部加速度呈现较大的误差。针对该问题,提出一种实时移除陀螺仪噪声的技术:方向余弦矩阵的第3列和陀螺仪的偏置同时设为状态向量,用于在线获取陀螺仪的噪声;加速度计的外部加速度和测量噪声均被设为测量余量,以便于在任意运动轨迹时能测量重力向量。陀螺仪和加速度计的测量结果通过卡尔曼滤波器融合,前者估算状态向量,后者校准状态向量的误差。通过比较MEMS-IMU在任意伪静态时的航姿和外部加速度验证本技术的可行性,实验结果表明俯仰角、横滚角、航向角和外部加速度的最大误差分别为0.5°、0.2°、2°和0.2 m/s2,该结果远好于仅用陀螺仪的航姿误差和外部加速度误差。

MEMS-IMU includes a tri-axial gyroscope and a tri-axial accelerometer, in which gyroscope’s noises lead to MEMS-IMU’s orientation inaccurate and result in external accelerations presenting errors. Based on the problem, a method of removing gyroscope’s noises in real time is proposed. The third column of directioncosine matrix and gyroscope’s bias are taken as state vector so that gyroscope’s noises could be obtained online. Both the external accelerations and measurement noises of accelerometer are regarded as measurement residuals so as to measure the gravity vector in any trajectory. A Kalman filter is utilized to fuse the measurement results of gyroscope and accelerometer, in which the former results is used to estimate the state vector and the latter results is aimed to calibrate the state vector. The feasibility of this study is verified by comparing orientation and external accelerations when MEMS-IMU is in arbitrary quasi-static. Experimental results show the maximum errors of pitch, roll, yaw and external accelerations are 0.5°, 0.2°, 2° and 0.2 m/s^2 respectively, which are much better than that only based on gyroscope.