An observer-based continuous adaptive sliding mode guidance against chattering for homing missiles

A novel observer-based continuous adaptive sliding mode guidance (OCASMG) is proposed for homing missiles. First, a new sliding mode guidance law is derived from the nonlinear dynamics describing the pursuit situation of a missile and a target in the two-dimensional space, where a continuous adaptive function is introduced to overcome the chattering problem in sliding mode. Second, to improve the accuracy of target interception, a new nonlinear extended state observer (NESO) is presented to estimate target acceleration and compensate for the sliding mode guidance law. The stability of observer-based closed-loop system is proved by Lyapunov theory. Finally, simulations are conducted on the nonlinear longitudinal missile model and results demonstrate the effectiveness of proposed method.