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This paper deals with the aerodynamic modeling of a ducted fan Vertical TakeOff and Landing (VTOL) Unmanned Aerial Vehicle (UAV) and the problem of attitude stabilization when the vehicle is remotely controlled by a human pilot in presence of crosswind. The main aerodynamic elements, which are inherent to the presence of the duct and explain the flight dynamics of this kind of vehicle, are first presented. Then, an attitude control is designed from a linearization of the dynamic model around the hovering flight equilibrium. As the vehicle is axis-symmetric, the pitch and the roll dynamics have a similar expression. For this reason, the presentation is focused on the design of the pitch controller. Similar results can be directly deduced for the roll. Experiments, led on the HoverEye platform designed by Bertin Technologies, show that the proposed attitude control is sufficient to open a large secure flight envelope.

16; International audience; This paper considers the problem of obtaining good attitude estimates from measurements obtained from typical low cost inertial measurement units. The outputs of such systems are characterized by high noise levels and time varying additive biases. We formulate the filtering problem as deterministic observer kinematics posed directly on the special orthogonal group SO(3) driven by reconstructed attitude and angular velocity measurements. Lyapunov analysis results for the proposed observers are derived that ensure almost global stability of the observer error. The approach taken leads to an observer that we term the direct complementary filter. By exploiting the geometry of the special orthogonal group a related observer, termed the passive complementary filter, is derived that decouples the gyro measurements from the reconstructed attitude in the observer inputs. Both the direct and passive filters can be extended to estimate gyro bias online. The passive filter is further developed to provide a formulation in terms of the measurement error that avoids any algebraic reconstruction of the attitude. This leads to an observer on S(3), termed the explicit complementary filter, that requires only accelerometer and gyro outputs; is suitable for implementation on embedded hardware; and provides good attitude estimates as well as estimating the gyro biases online. The performance of the observers are demonstrated with a set of experiments performed on a robotic test-bed and a radio controlled unmanned aerial vehicle.

This paper considers the problem of obtaining high quality attitude extraction and gyros bias estimation from typical low cost intertial measurement units for applications in control of unmanned aerial vehiccles. Two different non-linear complementary filters are proposed: Direct complementary filter and Passive non-linear complementary filter. Both filters evolve explicity on the special orthogonal group SO(3) and can be expressed in quaternion form for easy implementation. An extension to the passive ocmplementary filter is proposed to provide adaptive gyro bias estimation.