The Trajectory Tracking Problem of Quadrotor UAV: Global Stability Analysis and Control Design Based on the Cascade Theory

This paper deals with the trajectory tracking problem of a six‐degree of freedom (6‐ DOF ) quadrotor unmanned aerial vehicle ( UAV ). The problem of simplified kinematics based on Euler angles is analyzed and the modified R odrigues parameters ( MRPs ) technique is introduced to model the rotational dynamics of the rigid body. A nonlinear system error model is established based on the trajectory tracking problem, and, due to the coupling property between the translational and rotational dynamics, we divide the complete closed‐loop system into two reduced‐order subsystems and a coupling term. The R odrigues theorem is applied to analyze the internal connections between the coupling term and MRPs . Therefore, the global stability conclusions, by which the trajectory tracking controller of the quadrotor UAV could be designed based on the subsystem directly in future works, are proved based on several assumptions of the subsystems. Thereafter, the controllers, using the backstepping approach and nonlinear disturbance observer/sliding mode control approach, which stabilize the quadrotor UAV globally ‐exponentially and globally uniformly bounded, are proposed based on the stability theorem proofs mentioned above. Numerical simulations are provided to show that the theoretical conclusions and the controller proposed are effective.