Guidance law with deceleration control for moving-mass reentry warhead

A deceleration guidance law is developed for a reentry warhead with a fixed angle of attack by body geometry and a single moving-mass for attitude control. The guidance model equations, including the dynamic equations of the moving-mass two-body system and the kinematic equations between the warhead and the target, which form the basis of the study, are presented. To analyze the guidance model, the equations are simplified and new variables are introduced. By simplifying the guidance model equations, the transfer functions from the lateral position of the internal mass to the error angle are obtained. Iteration of the error angle is used to control the terminal velocity at a desired value. For the moving-mass reentry warhead studied in this paper, the relationship between the miss distance and the magnitude of the error angle is developed, and precision guidance can be achieved. Nonlinear seven-degree-of-freedom trajectory simulations verify the transfer functions and demonstrate the ability of the guidance law with deceleration control in a typical reentry mission.