Investigation On Combined Measurement Of Guided Projectile's Attitudes Based On Gyro/Magnetometer

The attitude measurement of flying projectile is a very important problem which must be resolved when designing the guided projectile. The three-axis magnetometer sensor and the two-axis MEMS angular rate gyro are combined to obtain the attitudes of the guided projectile in this paper. The measurement signal's noise is reduced by the wavelet threshold filtering algorithm. And then the data fusion algorithm based on weighty coefficient is applied to calculate the attitude angles of the guided projectile.In this paper, a simplified calculation method is adopted to calculate the roll angle of the guided projectile. The wavelet threshold filtering algorithm is supplied to reduce the noise of the simulated measurement signals with different Signal Noise Ratio (SNR). The roll angle at a certain time t0 is obtained through iterative calculation by processing the three-axis magnetometer sensor's signal. After the roll angle is obtained, the threes-axis magnetometer sensor's measurement signals are also used to calculate the yaw angle and pitch angle at time t0. When the attitude angles at time t0 are obtained, the weighty coefficients of the magnetometer sensor and the angle rate gyroscope are determined by least square estimate method. The yaw angle and pitch angle at the next sampling interval are calculated using the data fuse algorithm based on weighty coefficient.The method of using threes-axis magnetometer sensor and two-axis micro mechanical angle rate gyroscope to measure the projectile's attitude angles is theoretically feasible. And this method is demonstrated to determine the projectile's attitude angles in free flight through numerical simulations. The simulation results show that the accuracy of attitude calculation is higher when the SNR is larger, and the accuracy of attitude calculation is low with decreasing the SNR to 2. This method is also demonstrated well to determine the guided projectile's attitude angles under controlled flight condition through numerical simulations. In this case, the requirement of accuracy and rapidity can be satisfied to some extent.