Guidance law design and guidance loop analysis for strapdown imaging seekers

Abstract

This thesis describes guidance law design and guidance loop analysis for the air-to-surface missile using a passive strapdown imaging seeker. Recent advance in missile technology, there have been dramatic considerations on strapdown imaging seekers for measurement sensors due to their benefits such as cost saving associated with reducing the mechanical complexity. However, several fundamental problems have arisen: since the LOS rate is directly measured in the body axis not in the inertial reference frame, any significant noise or phase lag can make systems unstable during the transformation of the LOS rate from the body to the inertial reference frame; a strapdown imaging seeker provides bearing (LOS angle) only measurements, so that it can be suffered from the lack of the target observability. In addition, there is a limitation on permissible LOS rate to prevent acquiring a blurred image from target detection processing, that is a large pitch rate motion is restricted. Therefore, this paper deals with the stability and the observability analysis of a homing guidance loop with strapdown imaging seekers. In addition, a new guidance law in a way of increasing the observability and guaranteeing a small LOS rate simultaneously is proposed. A guidance filter based on the MGPMF (Modified gain Pseudo-Measurement Filter) is also designed to estimate necessary state variables. Finally, the homing guidance loop employing the proposed guidance law is mathematically analyzed in the first place, and then it is evaluated by number of simulations.