Trajectory tracking for an Ultralight WIG

In this paper we present our research about a particular ultralight WIG. We have carried out the design of a Flight Control System that has to fix the control variables trend through a non-linear mathematical model, because of the particular geometric and aerodynamic configuration of this WIG. So, the non-linear mathematical model design has to reproduce exactly the aircraft behaviour either OGE or IGE. In particular, through classical semi-empirical relations, analytical equations have been obtained in order to evaluate incidence variations, downwash and upwash angles due to the ground. In the present paper only longitudinal dynamic is considered, because of its peculiarity in WIG's aircraft dynamic. A mathematical general model has been built to evaluate aerodynamic coefficients variation laws due to altitude. This general equations system can be used in order to evaluate stability and control derivatives so it affords to simulate all the flight phases either out or in ground effect. A Simulink model has been realized and LQG/LTR robust control technique has been applied to design the controller. The simulation results have shown the accuracy of the mathematical model and that it is possible to control the studied UAV either OGE or IGE utilizing a single control system.