Combination of Composite Nonlinear Feedback and Adaptive Integral Sliding Mode Controllers for Robust Attitude Stabilization of a Fighter Aircraft

The problem of attitude stabilization of a fighter aircraft is investigated is this paper. The practical aspects of a real physical system like existence of external disturbances with unknown upper bound and actuator saturation are considered in the process of controller design of this aircraft. In order to design a robust autopilot in the presence of the actuator saturation, the Composite Nonlinear Feedback (CNF) controller along with the Adaptive Integral Sliding Mode (AISM) controller, that is called AISM-CNF control method, is used. The CNF part is used to stabilization of the nominal system and also the improvement the transient performance by considering the actuator saturation. The AISM part guarantees robustness against the disturbances. By the AISM controller the upper bounds of the disturbances are estimated and therefore the basic knowledge of the upper bound of the disturbances is not needed. The total controller satisfies the constraint on the input in the specific region of the state space. Finally, simulation results show the performance of the AISM-CNF controller in term of stabilization, robustness, and the good characteristics of the transient responses of the autopilot system in spite of actuator saturation.

Keywords:

Fighter aircraft , Actuator saturation , Composite Nonlinear Feedback (CNF) , Adaptive Inte gral Sliding Mode (ISM)