A review on quadrotor attitude control strategies

Quadrotors have been more frequently used in different areas, from aerial photography to drug delivery in medical emergencies. These vehicles have high maneuverability, which makes them suitable for carrying out missions that humans would not be able to do due to physical constraints. They can be used in inhospitable environments where the physical integrity and health of humans would be compromised. However, they are highly nonlinear and multivariable systems whose dynamics are strongly coupled. These characteristics turn attitude control design into a complex task. Furthermore, the controller has to be able to deal with uncertainties and exogenous disturbances in practice, intensifying the difficulty of the control problem. Therefore, a quadrotor attitude control must have high robustness and fast response without compromising its global stability. Aiming to gather solutions to this control problem, this article provides a detailed and in-depth discussion on quadrotor attitude control strategies for flight control designers, including angular representation, controller stability, fault tolerance, actuator saturation, and strategies for exogenous disturbance rejection.