Quadrotors' Double-Loop Controller Design with Fully Actuated Approach

Quadrotor UAV with six degrees of freedom and four control inputs are typical complex under-actuated nonlinear system. The quadrotor can be divided into two subsystems, namely the position subsystem and the attitude subsystem. The control scheme proposed in the paper is a double closed-loop fully actuated control method, and the fully actuated control approach are designed for the two subsystems. In the design of the position loop controller, the problem of system under-actuated was solved by introducing virtual inputs. And the problem of strong coupling in the system was addressed by establishing double-loop system and using fully actuated control approach. Finally, the feasibility and effectiveness of double closed-loop fully actuated system approach were verified through simulations and comparisons with sliding mode control methods.