title: Singularity-free backstepping controller for model helicopters.
abstract: This paper develops a backstepping controller for model helicopters to achieve trajectory tracking without singularity, which occurs in the attitude representation when the roll or pitch reaches ±π2. Based on a simplified model with unmodeled dynamics, backstepping technique is introduced to exploit the controller and hyperbolic tangent functions are utilized to compensate the unmodeled dynamics. Firstly, a position loop controller is designed for the position tracking, where an auxiliary dynamic system with suitable parameters is introduced to warrant the singularity-free requirement for the extracted command attitude. Then, a novel attitude loop controller is proposed to obviate singularity. It is demonstrated that, based on the established criteria for selecting controller parameters and desired trajectories, the proposed controller realizes the singularity-free trajectory tracking of the model helicopter. Simulations confirm the theoretical results.
authors.affiliation: The Seventh Research Division, Beihang University, Beijing 100191, China; School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China. Electronic address: zouyao20@126.com.
authors.forename: Yao
authors.initials: Y
authors.lastname: Zou
authors.affiliation: The Seventh Research Division, Beihang University, Beijing 100191, China; School of Automation Science and Electrical Engineering, Beihang University, Beijing 100191, China. Electronic address: weihuo@buaa.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Huo
keywords: Auxiliary dynamic system; Backstepping technique; Model helicopter; Singularity-free controller; Trajectory tracking