On the Autopilot Design for a Quadrotor during Landing Phase

The attitude controller and the navigation system of the quadrotor during landing phase are designed to realize the precision soft landing under external disturbance. Firstly, the mathematical model of the quadrotor with external disturbance is established based on the small angle assumption. Secondly, the quadrotor attitude controller based on L1-SMC theory is designed to resist the external disturbance. Finally, the navigation system of the quadrotor during landing phase is designed based on the improved Tao theory, and the simulation are carried out for the quadrotor attitude controller and landing phase navigation strategy. Simulation results show that the designed attitude controller can resist the external disturbance and has strong robustness and good tracking performance. The quadrotor can achieve a precise soft landing.