Guidance law design based on extended sliding mode control

For the case of a three-dimensional interception, a continuous extended sliding mode guidance law with robustness is proposed. Based on variable structure control theory and the method of zeroing the rate of line-of-sight (LOS) angle between missile and target, a suitable sliding sector is chosen instead of conventional sliding mode, and a three-dimensional continuous extended sliding mode guidance law is designed by considering the maneuvering acceleration of target as a disturbance with known boundary. The reachability and asymptotic stability of the sliding sector is strictly proven by Lyapunov stability theory. The guidance method directly obtains the information of LOS rate measurement and avoids the difficulties associated with target maneuver estimation. The proposed method is simple, so it is convenient for practical implementation. Simulating results show that the guidance law is more suitable for the missile to intercept the target with high maneuver than the proportional navigation law.