Modified rolling guidance law for single moving mass controlled reentry vehicle against maneuvering target with impact angle constraints

This paper deals with the problem of guidance law design for the single moving mass controlled reentry vehicle when impact angle constraints and maneuvering target are taken into consideration. More specifically, a modified rolling guidance law is proposed with the interactive virtual target and the landing point prediction strategy. First, considering the fact that the roll channel can be controlled directly, the relative motion between the single moving mass controlled reentry vehicle and the target is described by the error angle between the relative velocity and the line-of-sight. Second, a nonlinear error angle command is given to reduce the rotation rate. To satisfy impact angle constraints, an interactive virtual target is presented and the “S” formed velocity of the virtual target is given to abate the error angle tracking difficulty at the final stage of the reentry phase. Then, the landing point prediction strategy is employed and the motion variation trend is also taken into consideration. As the maneuvering target is replaced with the predicted landing point, the error angle tracking difficulty caused by the target velocity decreases, which is helpful to meet impact angle constraints and improve guidance accuracy at the same time. Finally, the finite-time rolling guidance law is proposed and proved via Lyapunov stability theorem. Compared with the existing method, lower-speed rotation, smaller missing distance and less impact angle errors are obtained, which can be demonstrated by numerical simulations.