Dynamic Modeling of Rotor Flapping Dynamics of an Unmanned Helicopter and Investigation of Applicability of System Identification and Control using Approximate Model

Khalesi, Mohammad Hossein; Salarieh, Hassan; Saadat Foumani, Mahmoud

Dynamic Modeling of Rotor Flapping Dynamics of an Unmanned Helicopter and Investigation of Applicability of System Identification and Control using Approximate Model

Document Type : Original Article

Authors

Mohammad Hossein Khalesi

Hassan Salarieh

Mahmoud Saadat Foumani

Abstract

Mathematical Modeling of the main rotor dynamics is very important in modeling of unmanned
helicopters, and its quality and performance will play an effective role in ability of the model to behave
the same as a real helicopter. There are different methods for modeling rotor dynamics which are different
from each other in simplifying assumptions and relations complexity. In most investigations, the complete
unmanned helicopter dynamic modeling is performed, applied and evaluated which decreases the
concentration on main rotor modeling and its quality. In this paper, main rotor dynamics have been
modeled independently using 2 different methods (theoretical method based on blade element theory and
approximate method using 1st order dynamics for flapping). Considering complexities arisen in
theoretical modeling method, using similarly behaving approximate model will make the final model
more applicable. To do this, using system identification technique, the probability of using approximate
model instead of theoretical one (which is a closer model to real rotor dynamics) has been investigated.
After that, a robust control system is designed based on approximate model and its successful
implementation in controlling the theoretical model, shows that it is possible to control the theoretical
model using much simpler approximate one.

Keywords

Main Rotor Modeling

Unmanned Rotorcraft

Flapping Dynamics

Blade Element Theory

System Identification