Dynamics modeling of multirotor type UAV with the blade element momentum theory and nonlinear controller design for a wind environment

This paper presents an aerodynamics modeling of a rotary type Vertical Take-Off and Landing (VTOL) aircraft using the Blade Element Momentum Theory (BEMT). The BEMT is incorporated into the rigid body dynamics to describe main force and its reactive torque by rotor of the multirotor UAV. The dynamics modeling can demonstrate the motion of the multirotor UAV in the presence of gust or wind in an unsteady environment effectively. In order to operate the multirotor UAV, a robust nonlinear control technique is designed to track the desired command and stabilize the UAV subject to uncertainties such as modeling error, external disturbances. The hierarchical Sliding Mode Control (SMC) is adopted to organize a multi-loop structure: the outer-loop and inner-loop mode. Actual control input is distributed by physical configuration of the multirotor UAV with the described thrust and torque modeling by the BEMT in the control allocation. Numerical simulation evaluates the feasibility of the dynamic modeling of the multrirotor UAV with BEMT in the presence of external wind effects, which enables to understand a motion of rotary type UAV in a windy environment.