MAHONY , Robert

An image-based strategy for visual servo control of a class of dynamic systems is proposed. The class of systems considered includes dynamic models of unmanned aerial vehicles capable of quasi-stationary flight (hover and near hover flight). The control strategy exploits passivity-like properties of the dynamic model to derive a Lyapunov...

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Control design for robotic systems guaranteeing safety and convergence properties in cluttered environments is intrinsically challenging due to their potentially conflicting ob jectives. While several research streams tackle the problem from different angles, a general solution for nonlinear dynamical systems is still out of reach. In this...

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This paper considers the problem of tracking reference trajectories for systems defined on matrix Lie Groups. Both the reference system (exosystem) and controlled system have states on the same matrix Lie group, with the exosystem having constant velocity. The measurements are associated with a group action on a homogeneous space of the state...

Flight performance of aerial robotic vehicles is critically dependent on the quality of the state estimates provided by onboard sensor systems. The attitude estimation problem has been extensively studied over the last ten years and the development of low complexity, high performance, robust non-linear observers for attitude has been one of the...

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An image-based visual servo control is presented for an Unmanned aerial vehicle (UAV) capable of stationary or quasi-stationary flight with the camera mounted on board the vehicle. The target considered consists of a finite set of stationary and disjoint points lying in a plane. Control of the position and orientation dynamics are decoupled...

A robust and reliable attitude estimator is a key technology enabler for the development of autonomous aerial vehicles. This paper is an introduction to attitude estimation for aerial robotic systems. First, attitude definition and parameterizations are recalled and discussed. Then, several attitude estimation techniques – ranging from...

Equivariance is a common and natural property of many nonlinear control systems, especially those associated with models of mechatronic and navigation systems. Such systems admit a symmetry, associated with the equivariance, that provides structure enabling the design of robust and high-performance observers. A key insight is to pose the...

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This paper introduces a novel approach for estimating the relative pose of a mobile robot equipped with an onboard IMU, a velocity sensor complemented with a monocular camera observing a planar scene. The proposed solution relies on the design of a deterministic Riccati observer that exploits the first-order approximations of a class of...

Image moments provide an important class of image features used for image-based visual servo control. Spherical image moments have the additional desirable property that they are invariant under rotation of the camera frame. For these features one can study the local and global stability and performance of the position control independently of...

— A key requirement for effective control of quadro-tor vehicles is estimation of both attitude and linear velocity. Recent work has demonstrated that it is possible to measure horizontal velocities of a quadrotor vehicle from strap-down ac-celerometers along with a system model. In this paper we extend this to full body-fixed-frame velocity...

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This article proposes a nonlinear complementary filter for the special linear Lie-group SL(3) that fuses low-frequency state measurements with partial velocity measurements and adaptive estimation of unmeasured slowly changing velocity components. The obtained results have direct application on the problem of filtering a sequence of image...

A nonlinear observer on the Special Euclidean group 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 SE(3) is that we can...

This paper provides a nonlinear attitude estimation method for vehicles performing high acceleration maneuvers when measurements of linear velocity and the ambient magnetic field are delayed. Linear velocity is measured using the Global Positioning System (GPS) and the delays of GPS and magnetometer measurements are assumed to be known...