Guidance information estimation of the semi-strapdown infrared imaging seeker

Advanced homing missile's guidance law for highly maneuvering targets, requires the information of both inertial Line of Sight (LOS) angular rate and maneuvering target acceleration. Nevertheless, the semi-strapdown seeker is not able to measure the LOS angular rate directly and the differential operations commonly used in traditional methods will amplify sensor's measurement errors, causing poor calculation accuracy of the LOS angular rate. By analyzing the mathematical relationship between the missile-to-target relative motion and the angle tracking system, an integrated relative motion and angle tracking filter model is proposed in this paper. To overcome the disadvantage of infrared seeker that it cannot measure the missile-to-target relative distance directly, this paper puts forward a new relative distance estimation method based on infrared imaging principle to enhance the observability of the integrated filter model. The simulation results demonstrate the validity and stability of the proposed method.