Robust sliding-mode attitude controller design for a small-scale helicopter based on extended state observer

In this paper, the application of sliding mode control for a small-scale helicopter was studied. The roll and pitch controller is designed based on a two-loop structure in which the inner-loop control law implements sliding mode control technique to track the reference angular rate and the outer-loop control law is designed to stabilize the attitude. To improve the robustness of the attitude controller and to reduce the chattering in the sliding mode controller(SMC), an extended state observer(ESO) is designed to estimate the neglected items and external disturbances. In the simulations, we use a full six-DOF model to check whether the controller would work for the full small-scale helicopter system. Simulation results demonstrate the effectiveness and robustness of the proposed controller.