Modeling and Simulation of a Small Quad-Rotor UAV

Small rotary-wing UAVs have many potential non-military applications and specifically multi rotor UAVs can be manoeuvrable, have the potential to hover, take off and fly in small areas. Nevertheless, their design is in some way critical. The main concern is their inadequate level of handling qualities due to the intrinsic instabilities of this type of small size vehicles. A specific hardware is also required to stabilize and control the aircraft. A non-marginal thrust-to- weight ratio is mandatory that implies adequate sizing of the power output provided by the propulsion system, generally compromising their endurance and their payload capabilities. In the last years, in the attempt to overcome these issues, several multi rotor unmanned vehicles have been developed. The aim of the present project is to create a compact, robust and highly manoeuvrable autonomous UAV. The quad-rotor ELISA (intEgrated muLtI-rotor for Surveillance Applications) is controlled changing the rotational speed of the motors. To optimize the platform control strategy, the research starts from the design and the construction of a new platform. The configuration is expected to improve the overall structural stiffness, in order to maintain the system symmetry. The research steps presented in this paper concern the analysis of the vehicle and the definition of the mathematical model describing the dynamic behaviour of the aircraft. Main results of this work will be reported and widely discussed in the paper.