Variable Gain Predictive PN Guidance for Interception of High Speed Re-entry Targets

A new guidance philosophy by introducing a trajectory dependent variable guidance gain in the predictive PN guidance has been proposed in this paper. The predictive PN guidance uses nonlinear models of interceptor and target to compute zero effort miss and time to go, while guidance gain computation utilizes a formula obtained by application of optimal control theory for a weighted control minimization of a linearized geometry PN guidance problem, where weight in the cost function could be any positive definite explicit function of time. The specific problem considered in this paper is interception of high speed re-entry ballistic target at various altitudes, this guidance logic shapes the guidance demand according to the maximum capability of the vehicle in such a fashion that almost full guidance correction happens during initial phase of the interceptor flight where it has sufficient aerodynamic capability. Hence the guidance demands in latter phase of the trajectory is almost negligible, where the interceptor capabilities are very low. The simulation has been done and improvement of this guidance against PN and Predictive PN guidance are shown. This guidance is named as ``variable gain predictive PN guidance (VGPRPN)''. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.