A fault tolerant control method for quadrotor based on inner and outer loops

Inner and outer loops structure was adopted to avoid direct design of the under-actuated control laws of quadrotor, the position subsystem was the outer loop and attitude subsystem was the inner loop. First, the control inputs of position subsystem were recursively obtained by backstepping method, according to which the desired roll and pitch angles were derived and the under-actuated control law was calculated. The corresponding attitude control laws were further designed by backstepping using the target trajectory of attitude, which included the derived desired roll and pitch angles and the given desired yaw angle. Considering actuator faults, adaptive method was used to estimate faults of the inner and outer loops to realize the fault tolerant control for quadrotor. Compared with the direct design, the structure of under-actuated control law was simple and could achieve actuator fault tolerance. The results show that the quadrotor can still realize the steady tracking of position and attitude with actuator faults, which proves the effectiveness of obtained control laws. © 2019, Central South University Press. All right reserved.