Observer-based adaptive fuzzy sliding-mode controller design for missile autopilot systems

In this paper, an adaptive fuzzy sliding-mode controller with an observer for missile autopilot systems is proposed with actuators, mainly consisting of the thrust vector control and the rolling torque control system, for the task of intercepting a theater ballistic missile. Considering states unknown and disturbances, the autopilot system stability and convergence are analyzed and demonstrated. Here, the sliding-mode, the fuzzy inference mechanism, and the adaptive algorithm and a switching surface are used to design the autopilot system controller with an observer to eliminate the necessity of measuring angular velocity, where the observer-based fuzzy sliding-mode controller is used to estimate the upper bound of disturbances, and the observer-based adaptive fuzzy sliding-mode controller with center adaption of membership functions is used to estimate the optimal bound of disturbances, respectively. Finally, the stability of the overall system is analyzed thoroughly via Lyapunov stability theory and Barbalat's lemma to achieve controller design for missile autopilot systems. Furthermore, extensive simulation results are conducted to validate the effectiveness of the proposed autopilot system.