Effects of rotor inflow models on dynamic responses of variable-pitch quadrotors

In this paper, effects of rotor inflow models on dynamic responses of variable-pitch quadrotors is investigated. The rotor inflow include both the static and dynamic inflow model formulated in first order form and fit quite into the formulation and solution methodology of the developed mathematical model. The main advantage of these models referred to computationally inexpensive and their particular form required to be coupled to the developed quadrotor model representing in the state space. Accordingly, the linear Drees model and Pitt-Peters dynamic inflow model are proposed to modify the quadrotor dynamic model and to capture the effects of rotor trailed wake provided unsteady properties for rotor aerodynamic model. This dynamic inflow is a three state model consists of uniform, sine, and cosine inflow components formulated based on rotor thrust, pitching, and rolling moments and it represents a linear radial distribution with first harmonic azimuthal distribution over the rotor disc. The linear and non-linear controllers are also designed for the variable-pitch quadrotor to improve the quality of dynamic responses. Furthermore, the non-linear controller, feedback linearization, guarantees the stability of the quadrotor in different maneuvers using the Lyapunov functions. The obtained results against experimental data show that the suggested inflow models can support the quadrotor dynamic responses with a higher resolution.