Midcourse Guidance Strategy for Multistage Interceptors with Coasting Phase

Abstract

This paper proposes a new approach on the impact angle control guidance problem for the multistage interceptor with nonmaneuvering phases, called coasting phase, and high acceleration buildup during the boosting phase. First, the required coasting time is determined to reach the target within the given time span considering operation time of the kill vehicle. Then, the required flight path angle profiles and corresponding guidance commands during the boosting phase are derived, in order to achieve the desirable impact angle and to minimize guidance errors at the end of the flight. To do so, the position and velocity changes of each phase are analytically calculated, and then the relationship between the time derivative of the flight path angle during the boosting phase and guidance errors accumulated throughout the flight is established. Some practical error compensation algorithms for the proposed guidance strategy are also presented. The significance of this paper lies in that it is the new analytic approach on how to determine flight path profiles of a multistage interceptor to achieve a terminal impact angle constraint considering both booting and coasting. The proposed guidance strategy is evaluated and proven to be effective through a case study with nonlinear simulations.