Attitude Stabilization of a Quadrotor Helicopter Using Brushless Motors

Abstract

Control system design of quadrotor helicopters with accurate actuator modeling is an important practical design problem that many previous works did not consider. In particular, most actuators of such vehicles are brushless motors, which are hardly controlled without accurate dynamical models. In order to improve the performance of attitude stabilization control system, a new control strategy is proposed in this paper. This control strategy is based on the nonlinear modeling of brushless motors. To reduce the complexity of traditional nonlinear Volterra models, we propose the use of Hammerstein series models. Furthermore a method for identification of such model from observed input-output data is presented. As models of four brushless motor have been obtained, a backstepping attitude controller is designed to stabilize the quadrotor helicopter. Flight experiments show that the proposed control strategy can achieve higher performance than original ones. KeywordsQuadrotor helicopter; Attitude control; Nonlinear system; Hammerstein series model; Backstepping