A differential game guidance law for an endoatmospheric interceptor missile steered by aero fins and reaction jets is developed in this paper with bounded controls. For a low-altitude endoatmospheric interceptor, the propellant of the reaction-jet control system (RCS) is restricted by the missile configuration. Considering propellant limits, the effect of the RCS thrust on homing performance is investigated through game space structures. Also, to use the RCS at an appropriate timing, game space decomposition is used to determine the initiating time of the RCS. Finally, the effectiveness of the guidance law is demonstrated by a realistic ballistic missile defense scenario. It is shown that the proposed guidance law provides a significant improvement in homing accuracy compared to the conditional one. Furthermore, under propellant limits, a bigger RCS thrust cannot guarantee a higher homing accuracy.
Liquid propellant sloshing, which induces perturbations to dynamic behavior of spacecraft, is a serious problem. This paper proposes an approach based on equivalent mechanics theory and Computational Fluid Dynamics (CFD) technology to estimate the dynamic influence of propellant sloshing on spacecraft. A mechanical model was built by CFD technique and packed as a ''sloshing'' block utilized in the spacecraft Guidance Navigation and Control (GNC) simulation loop. The block takes the motion characteristics of the spacecraft as inputs and outputs perturbative force and torques induced by propellant sloshing. It is more convenient to utilize in analysis of the coupling effect between propellant sloshing dynamics and spacecraft GNC than CFD packages directly. A validation case is taken to validate the accuracy and the superiority of the approach. The deducing process is applied to practical cases, and the simulation results are presented to demonstrate the proposed approach is efficient in identifying the problems induced by sloshing and evaluating effectiveness of several typical schemes for suppressing sloshing.
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