Abstract not found

This paper deals with the way to achieve positioning tasks by visual servoing in the case of planar and motionless objects whose shape is unknown. In fact, we consider here complex objects like those one can encount in the agrifood industry. A 3D reconstruction phase is first considered yielding to the parameters of the plane. This computation is based on the measurement of the 2D velocity in a region of interest and on the measurement of the camera velocity. Once the parameters of the plane are sufficiently stable, a visual servoing scheme is used to control the orientation of the camera with respect to the object and to ensure that it remains in the camera field of view for any desired orientation. This 3D reconstruction phase is maintained active during the servoing to improve the accuracy of the parameters and, consequently, to obtain a small positioning error. Finally, experimental results validate the proposed approach as well as for its effectiveness than for the obtained accuracy.

Abstract — We present a way to achieve positioning tasks by model-free visual servoing in the case of planar and motionless objects whose shape is unknown. Emphasize is made on the algorithm of 3d reconstruction which allows to synthetize easily the control law. More precisely, the reconstruction phase is based on the measurement of the 2D displacements in a region of interest and on the measurement of the camera velocity. However, we will show that the proposed algorithm is robust with respect to nonaccurate values of this velocity. 2D displacements rather than 2D motions are used to remove the assumption that the acquisition rate has to be high. In addition, a particular attention is paid to the complex case of large displacements to access high camera velocities. Once the parameters of the plane are sufficiently stable, a visual servoing scheme is used to control the orientation of the camera with respect to the object and to ensure that it remains in the camera field of view for any desired orientation. The 3D reconstruction phase is maintained active during the servoing to improve the accuracy of the parameters and, consequently, to obtain a small positioning error. Experimental results validate the proposed approach. I.

Abstract — The aim of this article is to achieve accurate visual servoing tasks when the shape of the object being observed as well as the final image are unknown. More precisely, we want to control the orientation of the tangent plane at a certain point on the object corresponding to the center of a region of interest and to move this point to the principal point to fulfill a fixation task. To do that, we perform a 3D reconstruction phase during the servoing. It is based on the measurement of the 2D displacement in the region of interest and on the measurement of the camera velocity. Since the 2D displacement depends on the scene, we introduce an unified motion model to deal with planar as well with non-planar objects. Unfortunately, this model is only an approximation. In [1], we propose to use active vision to enlarge its domain of validity and a 3D reconstruction based on a continuous approach. In this paper, we propose to use robust estimation techniques and a 3D reconstruction based on discrete approach. Experimental results compare both approaches. I.

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c t i v it y e p o r t 2008 Table of contents

c t i v it y e p o r t