Autonomous flight control of hobby-class small unmanned helicopter: trajectory following control by using preview control considering heading direction

In this paper, we design a feed-forward trajectory following controller by using optimal preview control theory for a helicopter, based on a transition model and an LQI position controller derived from previous work. In order to apply optimal preview control theory to trajectory following control at any given yaw angle, we propose a correction method for eliminating the disturbances due to attitude perturbations on the magnetic direction sensor. We show that there is a problem with the axis transform of position and velocity, and as a result it cannot be applied to optimal preview control at any given yaw angle. To solve this problem, we propose an alternative axis transform method. Finally, the performance of the proposed preview controller and axis transform were verified by ´circular´ and ´s character´ trajectory following experiments.