Disturbance observer-based robust integrated guidance and control design for tactical missiles

This paper documents a new integrated guidance and control (IGC) scheme for intercepting maneuvering targets by using backstepping technique, nonlinear disturbance observer (DOB) and nonlinear differentiator. More specifically, the nonlinear DOB is used to estimate and compensate the mismatched as well as matched uncertainties in IGC model and the nonlinear differentiator is used to calculate the time derivatives of the virtual control laws so as to address the problem of 'explosion of terms'. Detailed stability analysis proves that the system state tracking errors can converge to a small region around zero asymptotically and thus precise interception is achieved. Simulations results show that the proposed IGC controller exhibits better disturbance rejection performance without resort to high-gain controllers than traditional backstepping approach.