Modelling and LQR robust control of an unmanned aerial vehicle for air-launch

Abstract : A satellite launching procedure known as airlaunch is modeled and simulated at the staging phase, where a reusable unmanned aerial vehicle air-launches a second (rocket) stage. Airlaunch is described by the variations in mass, inertia and aerodynamic coefficients of airlaunch system and their effects on the stability of the airlaunch system at the stage separation. In this paper, this procedure may imply on large variation in angle of attack, sideslip and roll angle of the airlaunch system caused by perturbations on aerodynamic forces and moments during the launch phase. In order to stand these perturbations, it is proposed an LQR controller obtained by optimal and robust control theory. This controller is designed with the objective of stabilizing the system after the airlaunch. Performance of the proposed control algorithm is illustrated through computer simulations.