Spatial Evasive Strategy for a Bank-to-Turn Hypersonic Vehicle with Autopilot Dynamics and Rigid Roll Rate Constraint

An application oriented spatial evasive strategy for hypersonic vehicles was derived, which took account for autopilot dynamics lags and roll rate constraint. The spatial evasive problem between a Bank-to-Turn(BTT) hypersonic evader and a Side-to-Turn(STT) interceptor was formulated as Linear Quadratic Differential Game(LQDG) problem originally, and an analytic suboptimal solution was derived. In ideal case, the suboptimal strategy for the evader turned out to be constant maneuver with maximum acceleration in an optimal and dynamic evasive plane. However, for engineering applications, the autopilot dynamics lags and rigid roll rate constraint were introduced into the suboptimal strategy. And then the conditions under which the proposed evasive strategy maintained superior were analyzed. By comparison with conventional evasive strategies, the performance of these strategies was summarized. Consequently, the application oriented spatial evasive strategy was degenerated to a swing maneuver with certain frequency, and a precise estimation for the switching frequency was proposed as well.