Comprehensive System Identification of Ducted Fan UAVs - Cal Poly

CHAPTER 5 – CONCLUSIONSThe need for accurate simulation models of small scale, ducted-fan, unmanned airvehicles has lead to the development of techniques unique to this class of vehicles. Takenas a whole, this research activity shows that by combining existing industry tools withnew techniques a fairly high fidelity model can be constructed. This modelcomprehensively contains sensor and high fidelity actuator models along with nonlinearbare airframe models.Models and trends were developed by analyzing a number of different vehiclesspanning almost 50 years. All the vehicles showed that the ducted fan is vulnerable to ahigh degree of pitching and translation at slow speeds due to a strong effect of the lateraland longitudinal moment derivatives, Mu and Lv. This class of vehicles also shows thatthe coupling of roll and pitch due to the spinning ducted fan proves troublesome duringidentification. This is avoided by identifying the linear coupling and then removing itfrom the correlated responses. The use of flight test results, simulation analysis, and windtunnel data all may be required to ensure proper modeling techniques.Sensor performance is seen to be less than desirable due to the small packagingand weight of the available components. In the area of actuation, the maximum rate of theservos was seen to have profound effects on high bandwidth performance. This isimportant to consider because almost all MOUT exercises require some sort of higherbandwidth maneuvering.Overall, this research has shed some light on some of the unique tasks andprocedures for the system identification of ducted fan unmanned air vehicles.- 119 -