Contributions to the automatic control of aerial vehicles

Abstract

The control of underactuated vehicles has received increasing interests in relation with various robotic applications. This thesis focuses more specifically on the general problem of automatic control of aerial vehicles, and in particular of Vertical Take-Off and Landing vehicles. The contributions of this work is twofold. Firstly, this work sets the foundations of a general control approach for a large family of thrust-propelled underactuated vehicles in order to stabilize reference trajectories either in thrust direction, velocity, or position. The basic modeling assumption is that the vehicle is propulsed via a thrust force along a single body-fixed direction and that it has full torque actuation for attitude control. Motivated by robustness issues, a novel nonlinear integrator technique is proposed allowing to compensate for modeling errors and perform robustly against external perturbations. Secondly, we propose two novel attitude estimation algorithms, based on measurements provided by a GPS and an IMU embarked on the vehicle. The proposed methods make use of the measurement of the linear velocity to estimate the vehicle's acceleration, and improves significantly the precision of the estimated attitude, especially in the case of important accelerations.