Nonlinear disturbance observer enhanced dynamic inversion control of missiles

Nonlinear dynamic inversion control (NDIC) is one of the most promising nonlinear control methods in aerospace engineering. For longitudinal dynamics of a missile, this paper proposes a nonlinear disturbance observer based approach to enhance its disturbance attenuation ability and performance robustness against uncertain aerodynamic coefficients. Stability of the proposed nonlinear disturbance observer enhanced NDIC is established. Its flexibility and efficiency are demonstrated by two different choices of the nonlinear gain function in the observer. Simulation results show that the nonlinear disturbance observer based technique can significantly improve disturbance attenuation ability and performance robustness of dynamic inversion control.