PhD title:

Co-advisor: Rogelio LOZANO
Grant: DGA-CNRS
Location: Heudiasyc
Date PhD finished: October 28th, 2013

Current position: IR at Renault, France

This research work addresses the flight behavior of light weight fixed-wing UAVs in windy conditions. Such aerial devices offer a smooth transition of autonomous fight control design from theory to practice in addition to providing a proper solution in environments inaccessible or dangerous to human beings. However, not having a human pilot onboard implies that UAVs rely on automation to navigate or to avoid obstacles. In addition, their relatively low operating speed makes them particularly aected by the wind field.

Motivated by these considerations, the objectives of the current research aim theoretical and experimental results in designing flight controllers for small fixed-wing UAVs of conventional conguration allowing for stable flight in windy conditions. In order to achieve these objectives, several research areas are being addressed in this thesis as it follows.

First, a comprehensive study on the aerodynamic aspect of the airplane is conducted in order to obtain the mathematical model of the aircraft in presence of wind. Further, models that reproduce the essential behavior of the system in a simplied context are analyzed. Consequently, nonlinear models of reduced complexity, that are easier to analyze and simulate and more adapted to the design of control strategies, are presented.

Secondly, the problem to be solved is formulated as a trajectory following problem in which the flight controller must be able to steer the vehicle along a path. Navigation strategies are developed in order to minimize the airplane deviation relative to the reference trajectory. The wind is considered initially measurable by a ground station and, then, estimated using adaptive navigation based on the theory of Lyapunov. The performance of the estimation algorithm is improved using control design based on the tuning functions method.

The third axis of research is the design and the implementation of an experimental setup which consists of a ground station used for visualization and control purposes and an embedded autopilot architecture containing the airframe platform equipped with appropriate avionics.