Three-Dimensional Guidance for Various Target Motions With Terminal Angle Constraints Using Twisting Control

In this paper, a twisting control-based guidance law considering nonlinear/coupled dynamics and terminal angle constraints is proposed in a three-dimensional (3-D) space. The terminal angle refers to the impact angle for nonmaneuvering targets, and the approach angle for maneuvering targets, respectively. To meet the terminal angle constraints in the 3-D space, the coupled line-of-sight (LOS) error dynamics is controlled to track command LOS angles, which can be obtained from the relation between the desired terminal angle and the LOS angle. Then, a barrier function-based adaptive multivariable twisting controller is designed to obtain the guidance law for nullifying the LOS angle and rate tracking errors in the mutually orthogonal planes simultaneously. By virtue of the Lyapunov stability theory, the convergence of the LOS tracking errors to a predefined neighborhood of zero is proved in the presence of bounded disturbances with unknown bounds. In addition, several modifications are included in the proposed guidance law to enhance the guidance performance. Numerical simulations in different scenarios with a realistic missile model are conducted to validate the effectiveness and robustness of the guidance law.