Wind rejection via quasi-continuous sliding mode technique to control safely a mini drone

International audienceThe objective of this paper is to show how to build a nonlinear robust control law, which ensures trajectory tracking for a drone quadrotor under unpredictable wind perturbations. The first step is to find the aerodynamic forces and moments using a combination of momentum and blade element theory. Then the model is rewritten in state-space form, where the control inputs are selected to be proportional to the squares of rotor angular velocities. The other terms dependent linearly on rotors and wind velocities are considered as disturbances. Such a decomposition of thrust and selection of disturbances are almost exact in the hover flight. In literature, fixed bounds are often assumed on each component of the disturbance input vector, but for synthesis of the proposed control law, the big issue is that the disturbance depends on wind signals, the control itself, and state of the system. Chattering effects and their reduction are analysed and investigated in the last part of the paper by introducing rotors dynamics in control design. High order sliding mode control is applied and the recent tool of quasi-continuous sliding mode control is analyzed. Results of numeric experiments demonstrate the effectiveness of the proposed controls