Control of VTOL Vehicles with Thrust-direction Tilting

An approach to the control of a VTOL vehicle equipped with complementary thrust-direction tilting capabilities that nominally yield full actuation of the vehicle's position and attitude is developed. The particularity and difficulty of the control problem are epitomized by the existence of a maximal thrust-tilting angle which forbids complete and decoupled control of the vehicle's position and attitude in all situations. This problem is here addressed via the formalism of primary and secondary objectives and by extending a solution previously derived in the fixed thrust-direction case. The proposed control design is also illustrated by simulation results involving a quadrotor UAV with all propellers axes pointing in the same monitored tilted direction

Gradient-like observer design on the Special Euclidean group SE(3) with system outputs on the real projective space

A nonlinear observer on the Special Euclidean group $\mathrm{SE(3)}$ for full pose estimation, that takes the system outputs on the real projective space directly as inputs, is proposed. The observer derivation is based on a recent advanced theory on nonlinear observer design. A key advantage with respect to existing pose observers on $\mathrm{SE(3)}$ is that we can now incorporate in a unique observer different types of measurements such as vectorial measurements of known inertial vectors and position measurements of known feature points. The proposed observer is extended allowing for the compensation of unknown constant bias present in the velocity measurements. Rigorous stability analyses are equally provided. Excellent performance of the proposed observers are shown by means of simulations

Velocity-aided Attitude Estimation for Accelerated Rigid Bodies

Two nonlinear observers for velocity-aided attitude estimation, relying on gyrometers, accelerometers, magnetometers, and velocity measured in the body-fixed frame, are proposed. As opposed to state-of-the-art body-fixed velocity-aided attitude observers endowed with local properties, both observers are (almost) globally asymptotically stable, with very simple and flexible tuning. Moreover, the roll and pitch estimates are globally decoupled from magnetometer measurements

Time sub-optimal nonlinear PI and PID controllers applied to longitudinal headway car control

Simple nonlinear PI and PID controllers combining time-(sub)optimality with linear control robustness and anti wind-up properties are presented. For illustration purposes, the proposed PID solution is applied to the longitudinal headway control of a vehicle following another vehicle

Observer design on the Special Euclidean group SE

Abstract— This paper proposes a nonlinear pose observer designed directly on the Lie group structure of the Special Euclidean group SE(3). We use a gradient-based observer design approach and ensure that the derived observer innovation can be implemented from position measurements. We prove local exponential stability of the error and instability of the non-zero critical points. Simulations indicate that the observer is indeed almost globally stable as would be expected

Point and line feature-based observer design on SL(3) for Homography estimation and its application to image stabilization

This paper presents a new algorithm for online estimation of a sequence of homographies applicable to image sequences obtained from robotic vehicles equipped with a monocular camera. The approach taken exploits the underlying Special Linear group SL(3) structure of the set of homographies along with gyrometer measurements and direct point-and line-feature correspondences between images to develop temporal filter for the homography estimate. Theoretical analysis and experimental results are provided to demonstrate the robustness of the proposed algorithm. The experimental results show excellent performance even in the case of very fast camera motion (relative to frame rate), and in presence of severe occlusion, specular reflection, image blur, and light saturation

Energy in Europe. Energy policies and trends in the European Community. July No 28. 1997

International audienceMotivated by drone autonomous navigation applications we address a novel problem of velocity-aided attitude estimation by combining two linear velocity components measured in a body-fixed frame and a linear velocity component measured in an inertial frame with the measurements of an Inertial Measurement Unit (IMU). The main contributions of the present paper are the design of a Riccati nonlinear observer, which may be viewed as deterministic versions of an Extended Kalman filter (EKF), and an analysis of observability conditions under which local exponential stability of the observer is achieved. Reported simulation results further indicate that the observer's domain of convergence is large