Modeling and Robust Control for Full-flight Envelope Trajectory Tracking of a QuadCP-VTOL Unmanned Aerial Vehicle

Abstract

A robust adaptive mixing controller (RAMC) is designed to solve the trajectory tracking problem of a quad-tiltrotor convertible plane (CP) unmanned aerial vehicle (UAV). This kind of system is a hybrid aerial vehicle that combines advantages of rotary and fixed-wing aircraft. In this work, the equations of motion of this UAV are obtained using the Euler-Lagrange formalism and assuming it as a multibody mechanical system. The non-conservative forces and torques generated by the propellers, servomotors and aerodynamic surfaces, are mapped to the generalized forces vector. Aiming to design the RAMC, an LPV representation of the system is derived from the nonlinear model, from which several mixed H2/H∞ candidate controllers are designed according to the UAV forward motion, and an adaptive mixing scheme is employed to smoothly interpolate these controllers, providing stability to the closed-loop system for the full-flight envelope of the UAV. The efficiency of the RAMC is verified in a high-fidelity simulator developed on the Gazebo and ROS platforms, in which the UAV is required to track a reference trajectory with different flight requirements, such as hovering, transition, cruise and level turn.