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In this article, a vision based landing framework is proposed for fixed-wing UAVs. Being able to automatically land a UAV without on-ground instrumentation or in the case of e.g. GPS loss, is a challenge of strong practical relevance. In this study, the Avion Jaune UAV, was considered to apply such a framework enabling it with vision-only landing capability. The proposed approach considers the synthesis...
Stabilization of a class of underactuated vehicles with uncertain measurements of the position tracking error is addressed. Nonlinear feedback laws ensuring semi-global stability for a large class of uncertainties on these measurements are derived based on properties of saturated controls. Practical relevance of the proposed results is illustrated by two application examples for Vertical Take-Off...
A novel approach for reconfigurable control systems design against sensor and actuator faults is proposed. The scheme is based on an estimation of the state and of the fault parameters, and on a Partially Observable Markov Decision Process (POMDP), used for the decision task of the feedback controller. The following fault types are considered: locking and loss of effectiveness of the device. The modelling...
This paper presents a novel obstacle avoidance scheme for UAVs. This scheme is based on the use of a technique recently developed by one of the authors, which is based on a transformation of a variable constraint into an input saturation. In the case of obstacle avoidance, this saturation is designed so as to ensure a safe trajectory around the obstacles, offering a proof of this desired behavior...
This paper proposes a nonlinear vision based flight control law for the automatic landing of an aircraft. Although a number of methods have been proposed in this domain, our method differs by the following features. First, we do not assume knowledge of the runway size or distance from the aircraft, or the help of a ground technology to guide the aircraft. Second, this design addresses the model nonlinearities,...
In this paper we propose a vision based flight control law for the automatic landing of an aircraft. Newly defined visual features obtained by a 2D-video camera embed the needed information about the relative pose between the aircraft and the runway. To cope with their dependence on the unknown distance to the ground, a depth estimation algorithm is proposed. With these elements, several nonlinear...
This paper proposes a key feature for vision based automatic landing of a UAV: the addition to a given control law of the constraint that a given ground point be maintained in the camera field of view (FoV). This feature is an application case of an output constraint method recently developed and available for any nonlinear system. This method is based on an observation made for relative degree one...
The paper concerns the stabilization of thrust-propelled underactuated vehicles in the context of sensor-based control. First, a class of nonlinear feedback laws that ensure semi-global stabilization despite possibly large uncertainties on the position measurements is proposed. Then, application to the visual servoing of a Vertical Take-Off and Landing (VTOL) drone with a video camera is considered...
The paper addresses the control of Vertical Take Off and Landing (VTOL) Underactuated Autonomous Vehicles (UAVs) in hover flight, based on measurements provided by an on-board video camera and rate gyros. The objective is to stabilize the vehicle to the pose associated with a visual image of a planar target. By using the homography matrix computed from the camera measurements of the target, stabilizing...
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