Post-flight Analysis and Design Improvement in Command Guidance System for a Short-range Surface-to-air Missile System

Abstract

A short-range missile with command-to line-of-sight and three-beam guidance has been considered in this paper. The earlier command guidance system (CGS) design shows unacceptably
high-low-frequency weave-mode oscillations, leading to high latax and body rate oscillations, even for benign, low-speed non-manoeuvring target engagements. For successful target
engagements with the three-beam guidance, missile is to be handed over from wide-to-medium receiver beam, and finally, from medium-to-the most accurate narrow receiver beam, depending on the angular error wrt line-of-sight as early as possible. Due to large amplitude oscillation in the earlier CGS design, the handing over of the missile to narrow receiver beam, and in many cases, to the medium receiver beam, itself could not take place, leading to failure of guidance. In this paper, the cause for this undesirable high magnitude weave-mode oscillation has been analysed in detail. After establishing this, saturation aspects of the earlier CGS design; a simple implementable CGS re-design was carried out to reduce this saturation aspect drastically for preserving almost full-phase advance effects of the linear new analogue compensators designed to give the required stability margins of guidance loop.