Nonlinear robust control design of a small-scale helicopter

In this paper, we focus on the design of a nonlinear robust controller for a small-scale helicopter. A three-layer control architecture is adopted: the inner loop controller is designed combining second-order sliding mode control with extended state observer to control the angular rates and yield good robustness properties with respect to model uncertainties and gust disturbances; the middle loop controller is used to control the attitude; the outer loop controller is responsible for trajectory tracking control, a new feedback loop-acceleration feedback is introduced to compensate for the effect of the disregarded force components. Simulation results are also given to show the effectiveness of the proposed controller and its robustness to cope with model uncertainties and gust disturbances.