Impact angle constrained sliding mode guidance against maneuvering target with unknown acceleration

In this paper, a sliding mode guidance law for impact angle control is proposed against a maneuvering target with unknown acceleration, which is capable of achieving the acceptable miss distance and a wide range of the desired impact angle. The main idea is to separate the switching surfaces for the impact angle constraint and the homing constraint, then to associate the two surfaces by introducing an appropriate virtual controller. Because of the unknown target acceleration, an adaptive procedure is designed to select the gain of the switching controller which accounts for the uncertainty bound regarding the target acceleration. The stability of the proposed approach is analyzed by Lyapunov theory, and the capturability analysis is also presented. Simulation results confirm the effectiveness of the proposed guidance against a maneuvering target as well as a nonmaneuvering target with absence and presence of noise.