Absolute Stability Margin in Missile Guidance Loop

This paper deals with the stability analysis of a missile guidance loop by using the absolute stability theory. Most guidance loop shows in general nonlinear time-varying characteristics, the loop stability will be severely degraded as a missile approaches at a target. The problem of finding general stability analysis method which provides necessary and sufficient condition for this nonlinear time-varying guidance loop remained by now unsolved. It is well-known that the stable time interval satisfying only sufficient condition can be obtained for guidance loop by applying absolute stability analysis method. In this paper, based on the circle criterion we obtained the absolute stability margin, i.e. gain and phase margin of integrated proportional navigation guidance loop which is an integral form of proportional navigation guidance. The correlation between the absolute stability margin and the margin derived from the frozen system analysis is also discussed