The Unified Tracking Controller for a Tilt-Rotor Unmanned Aerial Vehicle Based on the Dual Quaternion

Tilt-rotor multi-rotor UAV is a rapidly expanding field of research due to its benefits of full actuation, high force and torque capabilities, and great efficiency of hovering. The current controllers of tilt-rotor multi-rotor UAVs are primarily based on the Cartesian coordinate system to describe the position combined with the classical Euler angle approach, the direction cosine matrix or the quaternion to represent the attitude, which makes control lose its mathematical simplicity and has some singularity cases. In this paper, the system modelling of a tilt-rotor multi-rotor UAV using the unit dual quaternion is presented and a novel PID feedback linearization tracker is proposed. The developed controller has advantages of singularity free, attitude/position coupled motion tracking, and robustness to external disturbance. Applying the Laplace transform, the stability analysis is conducted by analyzing the poles and zeros of the closed-loop system. Simulation studies including the 6 DoF trajectory tracking and disturbance rejection are also performed to demonstrate the effectiveness of the proposed method. The simulation results illustrate that the proposed PID feedback linearization tracker has good tracking performance for both position and attitude and strong robustness against disturbance.