A Three-dimensional robust nonlinear guidance law considering input dynamics and uncertainties

Taking into consideration autopilot dynamics and uncertainties, a novel three-dimensional nonlinear guidance law is proposed based on input-to-state stability (ISS) and generalized small-gain theorem for interception of maneuvering targets (evaders). We assume the autopilot dynamics follows a second-order reference model with uncertainties. Without considering autopilot dynamics and by viewing the target acceleration as a bounded disturbance input, input-to-state stability theory is utilized to design a state feedback guidance law so as to achieve robust tracking. After that the guidance law for the system composed by pursuit-evasion kinematics and autopilot dynamics is designed based on generalized small-gain theorem. So that the LOS rate is robust with respect to both the target acceleration and autopilot dynamics uncertainties. Theoretical analysis and simulation results show that the guidance law designed can lead to successful interception of maneuvering targets, and has strong robust property.