Abstract: The ability of trajectory tracking and control during landing flight is a key factor affecting the performance of unmanned helicopter (UH) on board. Aiming at the uncertainty of the UH model system and the problem of being disturbed by gusts in the process of landing, a method of trajectory tracking and control based on the extend stated observer (ESO) and 〖JP2〗the dynamic surface strategy is proposed. Firstly, a mathematical UH model is built. Secondly, the composite disturbance ESO is structured to observe the effects of unmodeled dynamics and gust disturbances, and the uncertainty of the system is suppressed by feedforward compensation to achieve the system’s robustness for disturbance. Thirdly, the trajectory tracking control is structured with a layered structure in the form of inner and external rings, the problem of “differential explosion” and insensitive adjustment of control parameters is solved by the dynamic surface strategy, and the Lyapunov method is used to prove that the whole system is uniformly asymptotically stable. Finally, the experiment show that the designed control has better tracking performance.

Key words: unmanned helicopter (UH), autonomous landing, trajectory tracking, backstepping, dynamic surface, extend stated observer (ESO)