A Novel Fixed-Time Convergence Three-Dimensional Guidance Law for Intercepting Highly Maneuvering Targets

In this paper, a novel three-dimensional fixed-time convergence guidance law for intercepting highly maneuvering targets is proposed. It comprehensively considers the impact angle constraint, guidance command input saturation constraint, and autopilot second-order dynamics. The guidance law is firstly designed based on a novel fixed-time convergent sliding mode surface proposed in this paper. Then, a backstepping control method is adopted for consideration of autopilot second-order dynamics. By constructing an adaptive auxiliary system, the problem of guidance command input saturation is solved. Additionally, the fixed-time convergence disturbance observer is used to estimate the guidance system disturbance. Using the Lyapunov theory, the stability and fixed-time convergence of the proposed guidance law are proved and analyzed. Finally, the simulation comparison of four different guidance laws shows the excellent guidance performance of the proposed guidance law.