Suppressing Self-Excitation in Adaptive Sliding Mode Control: Observer-Based Design and Experimental Validation of Flapping-Wing Micro Aerial Vehicle

Abstract

This work covers the design of a sliding mode control to stabilize the attitude of a flapping-wing micro aerial vehicle. The approach employs an auxiliary observer loop to avoid system excitation from unmodeled actuator dynamics, a common issue in sliding mode control applications. A proportional-integral observer is constituted in the auxiliary loop to minimize interactions with the actuator dynamics and to handle parametric uncertainties in the low bandwidth. Then, the observer-based sliding mode control is designed to track the attitude command with the reconstructed state variables from the observer loop. Furthermore, a barrier function-based adaptive gain strategy is utilized to modulate the control input according to the system’s current state, ensuring efficient use of control effort. Flight experiments were conducted with a freely movable dummy mass attached to the bottom of the vehicle, simulating external disturbances. The proposed sliding mode control outperforms PD, classical, and super-twisting sliding mode controls in tracking performance and control efficiency, while mitigating self-excitation due to discontinuous input.