Robustness of Incremental Backstepping Flight Controllers: The Boeing 747 Case Study

Incremental control strategies have been proposed recently to reduce the dependence on the aircraft model. However, the technique still requires modeling the actuator effectiveness, which depends on inertial and aerodynamic parameters. Therefore, it is of the utmost importance to analyze the robustness of the strategy regarding these parameters. This work focuses on evaluating the robustness of an incremental backstepping strategy applied for automatic control of a Boeing 747 (B747). A sensitivity analysis is carried out to quantify the impact of inertial parameters and flight condition in the input effectiveness, whose results are used to define scheduling strategies for the incremental controller. A robustness analysis is then performed using a B747 simulator applying different maneuvers in several flight conditions. The flight performance is evaluated according to the military standard MIL-DTL-9490E. Results show that the proposed controller is robust to mismatches in the input effectiveness model, evidencing that even without using a scheduling strategy the controller is able to perform within the requirements specified in the standard.