Autonomous Flight Control of Hobby-Class Small Unmanned Helicopter

In this paper, we design a feed-forward trajectory following controller by using optimal preview control theory for a helicopter, based on its 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 disturbances due to attitude perturbations on the magnetic direction sensor. We show the axis transform of position and velocity has a problem and as a result it can not be applied to optimal preview control at any given yaw angle. To solve it, we propose alternative axis transform method. Finally, the performance of the designed preview controller and the proposed axis transform were verified by“circular”and“S character”trajectory following experiments.