Unmanned Aerial Vehicles: Embedded Control

Chapter 4

Autonomous Hovering of a Two-Rotor UAV ¹

4.1. Introduction

Nowadays, the unmanned aerial vehicles (UAVs) represent an appealing research area due to their wide-range application field. Military applications include hostile zone reconnaissance, hazardous biological or chemical agent detection, etc. Civilian applications include natural disaster support, assistance for earth science research, agricultural support, etc.

Vectored-thrust vehicles represent an interesting aerodynamic configuration which do not use control surfaces (ailerons, rudder, elevon, etc.) to drive the motion of the aircraft in hover flight [BAR 98]. The Bell Boeing V-22 Osprey employs a swashplate and differential tilting rotor to control pitch and yaw [ROS 86, MIL 91]. Vectored-thrust vehicles do not require a run-way or an auxiliary launch/recovering device, such as catapults or parachutes, because of their VTOL (vertical take-off and landing) capabilities. For these reasons we propose in this chapter a new configuration of a vectored-thrust two-rotor UAV (see Figure 4.1), where the pitch and yaw motions are controlled using a simple mechanical system based on thrust vectoring (noncyclic propellers).

An interesting two-rotor aircraft was proposed in [GRE 07]. Such a dual-propeller VTOL configuration controls the pitch and yaw motion through a combination of lateral and longitudinal tilting of the rotors (oblique propeller tilting). The mechanism used in Gress’s configuration is based on the gyroscopic ...