Attitude Tracking Control of Flight Vehicle in Terminal Guidance Phase Based on Fully Actuated System Approach

This paper deals with the problem of attitude tracking control for a flight vehicle in the terminal guidance phase under multi-source disturbances. First, a nonlinear dynamic model for the flight vehicle is formulated in strict-feedback form. Second, external disturbances, aerodynamic parameter variations, and unmodeled dynamics during the terminal guidance phase are treated as a lumped disturbance. An extended state observer (ESO) is then employed to estimate this lumped disturbance, which is further compensated for within the controller. Subsequently, a tracking controller is designed by combining the fully actuated system (FAS) approach with backstepping control, which transforms the original nonlinear system into a desired linear closed-loop system. Based on Lyapunov stability theory, it is proven that the attitude tracking errors converge into the neighborhood of the origin. Finally, the effectiveness of the proposed controller is verified through numerical simulations.