Three dimensional adaptive dynamic surface guidance law accounting for autopilot lag

A new adaptive guidance law accounting for the autopilot lag as a second-order dynamics is proposed utilizing dynamic surface control. The target acceleration is considered as a bounded uncertainty, but its upper bound cannot be estimated as a priori. Considering the unknown parameter uncertainty, an update law is designed via Lyapunov approach. The guidance acceleration command input is determined by a dynamic surface control law with a parameter update law. Some first-order low-pass filters are introduced into the designing process to avoid the occurrence of high-order derivatives of the tangential relative velocities in the expression of the guidance law such that the guidance law can be implemented in practical applications. Simulation results show that the new guidance law is highly effective.