Comprehensive System Identification of Ducted Fan UAVs - Cal Poly

Commercial interest has also been seen by companies and organizations lookingfor stable camera and surveillance platforms. Bridge inspection, traffic monitoring, andsearch and rescue in hostile environments all can benefit from use of a small unmannedvehicle capable of hovering flight. A unique class of small rotorcraft UAVs (RUAVs)incorporating all of the characteristics yields a small design with certain designdifficulties. These RUAVs possess the problem of making a small-scale vehicleunmanned along with the inherently unstable nature of rotorcraft dynamics. The ductedfan RUAV design fulfills the collision and troop handling safety requirements. However,these ducted fans introduce a strong tendency to correct themselves in pitch and roll withlongitudinal and lateral velocity, respectively.These ducted fan RUAVs have low inertias with most of the weight near thecenter of the vehicle. Their small size and weight make for stringent volumetric and massrestrictions. This leads to lower performance subsystems, especially sensors andactuators. High degrees of cross coupling due to strong gyroscopic effects are created bythe fast spinning propellers. The unconventional designs that have little or no knowledgebase established make physics based modeling difficult 2 . Most RUAV types include theability for a wide range of scales to be produced. Because of the relative simplicity ofconstruction, bigger and smaller vehicles alike can be produced. Usually shorter designcycles due to limited funding and demanding project requirements leave these vehicles inneed of accurate models early in the design cycle. Flight vehicles are available very earlyin the design sequence and make for easier flight test based identification. Thesecharacteristics combine to mandate accurate dynamic models. This research work willfocus on the comprehensive identification of these models.- 2 -