Impact angle-constrained integrated guidance and control for supersonic skid-to-turn missiles using backstepping with global fast terminal sliding mode control

An integrated guidance and control (IGC) scheme based on global terminal sliding mode control (GTSMC), backstepping control (BC), linear feedback (LF), dynamic surface control (DSC), reduced-order extended state observer (ESO) for a supersonic skid-to-turn (STT) interceptor intercepting maneuvering targets is presented. The IGC scheme considers the delay dynamics of the rudder and solves the impact angle constraint. First, a fifth-order strict-feedback nonlinear IGC model with mismatched uncertainties was established taking into account the rudder delay dynamics. Second, the guidance and control system based on BC consists of the guidance subsystem, normal overload subsystem, attitude subsystem, rudder subsystem. Each subsystem was designed based on the GTSMC and LF. In particular, the GTSMC was designed for the guidance subsystem to ensure the fast convergence of the line-of-sight angle. The DSC was introduced to calculate virtual commands to prevent “differential explosion”. The unknown lumped disturbances, including target maneuvers, external disturbances, and perturbations caused by the aerodynamic parameters, were accurately estimated and compensated for by the reduced-order ESO in the proposed IGC scheme. The closed-loop system was proved to be stable and the system states to be uniformly bounded using Lyapunov theory. Finally, simulation results demonstrated the superiority of the proposed IGC scheme compared to previously proposed schemes.