Lionel Cordesses

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An accurate vehicle guidance system is required for some precision agriculture operations. It can be used for high speed direct seeding on a farm tractor. Such a system also ensures neither overlapping nor missing areas during the harvest, even when visibility is poor. But, automatic path following in the field is a difficult problem. Many vehicle guidance(More)
Visual servoing requires an object in the field of view of the camera, in order to control the robot evolution. Otherwise, the virtual link is broken and the control loop cannot continue to be closed. In this paper, a novel approach is presented in order to guarantee that the object remains in the field of view of the camera during the whole robot motion.(More)
Oscillators are the subjects of intensive research. From Colpitts oscillators to phase locked loops, methods have been proposed to improve stability, frequency resolution, and spectral purity. Among the all-digital approaches, direct digital frequency synthesis are now available as integrated circuits and they output waveforms up to hundreds of megahertz.(More)
Precision agriculture involves very accurate f a r m vehicle control along recorded paths, which are no t necessarily straight lines. In this paper, we investigate the possibility of achieving this task wi th a CP-DGPS as the unique sensor. T h e vehicle heading is derived according t o a K a l m a n state reconstructor, and a nonlinear velocity independent(More)
Direct digital synthesis (DDS) is a useful tool for generating periodic waveforms. In this two-part article, the basic idea of this synthesis technique is presented and then focused on the quality of the sinewave a DDS can create, introducing the SFDR quality parameter. Next effective methods to increase the SFDR are presented through sinewave(More)
An accurate localization system (Carrier Phase diierential GPS receiver) allows the design and implementation of an absolute vehicle guidance system. The preliminary work, presented in this paper, was aimed at validating the use of one GPS receiver in a vehicle guidance system, without any orientation sensor. We designed and implemented a non linear control(More)
In this paper, we address the problem of combine harvester control using a single CP-DGPS receiver, without any attitude measurement unit. A non linear, velocity independent control law has been designed. It relies upon the kinematic model of the combine harvester. Two approaches aimed at estimating the heading of the farm vehicle have been investigated.(More)
This paper presents a path planning algorithm for a tractor to execute specific farmwork tasks requiring the complete coverage of a field while minimizing the overlapping between successive passages. The proposed method is based on the determination of a set of characteristic points from which a graph is defined. The covering trajectory is determined by(More)
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