Attitude control strategy of quad-tiltrotor UAV in transition mode

Abstract

Tiltrotor has been developed as a platform that combined the features of multicopter aircaft and fixed-wing aircraft to overcome both shortcomings. However, since the aerodynamic forces and moments continuously change during the transition mode, the controller design for transition mode is required separately to the hovering and forward modes. In this paper, nonlinear model of quad-tiltrotor was derived for constructing simulator and dynamics analysis. From the dynamic model analysis, the conversion corridor line was calculated using aerodynamic coefficients, and nonlinear controller for transition mode was obtained. The aerodynamic coefficients which are key points for design controller is obtained using on-line Kalman Filter.