Output Feedback Tracking Control of an Underactuated Quad-Rotor UAV

This paper proposes a new controller for an underactuated quad-rotor family of small-scale unmanned aerial vehicles (UAVs) using output feedback (OFB). Specifically, an observer is designed to estimate the velocities and an output feedback controller is designed for a nonlinear UAV system in which only position and angles are measurable. The design is performed via a Lyapunov type analysis. A semi- global uniformly ultimate bounded (SGUUB) tracking result is achieved. Simulation results are shown to demonstrate the proposed approach.