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Attitude dynamics aiding for line-of-sight angular rate reconstruction of strap-down seeker

To solve the problem that the line-of-sight (LOS) angular rate extraction accuracy of strap-down seeker is usually affect by the measurement accuracy of attitude angular rate and the accuracy of attitude angle calculation, a new LOS angular rate filtering method aided by the attitude control rudder angle was proposed. First, the filtering equation of MEMS inertial measurement unit (IMU) was established based on the attitude dynamics; second, the Unscented Kalman Filter (UKF) was employed to estimate the three axis angular rate, three axis attitude angle, attack angle and the slip angle; third, the Euler transformation matrices of LOS angle in inertial reference system were derived, based on which the tracking differentiator was employed to realize the filtering of LOS angle and estimation of LOS angular rate. The simulation result implies that the estimation error of angular rate and attitude angle is reduced respectively to 60% and 50%, while the error of LOS angle and LOS angular rate is 0.6° and 0.06°/s respectively, and the estimation error of attack angle and slip angle is about 0.6°, which proves the validity of the method.