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Abderrahmane Kheddar

Bio: Abderrahmane Kheddar is an academic researcher from University of Montpellier. The author has contributed to research in topics: Humanoid robot & Robot. The author has an hindex of 45, co-authored 305 publications receiving 7235 citations. Previous affiliations of Abderrahmane Kheddar include Pierre-and-Marie-Curie University & University of Paris.


Papers
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Proceedings ArticleDOI
18 Mar 2000
TL;DR: In this paper, the authors considered whether a passive isometric input device, such as a Spaceball/sup TM, used together with visual feedback, could provide the operator with a pseudo-haptic feedback.
Abstract: This paper considers whether a passive isometric input device, such as a Spaceball/sup TM/, used together with visual feedback, could provide the operator with a pseudo-haptic feedback. For this aim, two psychophysical experiments have been conducted. The first experiment consisted of a compliance discrimination, between two virtual springs hand-operated by means of the Spaceball/sup TM/. In this experiment, the stiffness (or compliance) JND turned out to be 6%. The second experiment assessed stiffness discrimination between a virtual spring and the equivalent spring in reality. In this case, the stiffness (or compliance) JND was found to be 13.4%. These results are consistent with previous outcomes on manual discrimination of compliance. Consequently, this consistency reveals that the passive apparatus that was used can, to some extent, simulate haptic information. In addition, a final test indicated that the proprioceptive sense of the subjects was blurred by visual feedback. This gave them the illusion of using a nonisometric device.

336 citations

Journal ArticleDOI
TL;DR: This paper introduces a fast continuous collision detection technique for polyhedral rigid bodies that can robustly prevent objects interpenetrations or collisions misses, even when objects are thin or have large velocities.
Abstract: This paper introduces a fast continuous collision detection technique for polyhedral rigid bodies. As opposed to most collision detection techniques, the computation of the first contact time between two objects is inherently part of the algorithm. The method can thus robustly prevent objects interpenetrations or collisions misses, even when objects are thin or have large velocities. The method is valid for general objects (polygon soups), handles multiple moving objects and acyclic articulated bodies, and is efficient in low and high coherency situations. Moreover, the method can be used to speed up existent continuous collision detection methods for parametric or implicit rigid surfaces. The collision detection algorithms have been successfully coupled to a real-time dynamics simulator. Various experiments are conducted that show the method's ability to produce high-quality interaction (precise objects positioning for example) between models up to tens of thousands of triangles, which couldn't have been performed with previous continuous methods.

281 citations

Journal ArticleDOI
TL;DR: A new computer haptics algorithm to be used in general interactive manipulations of deformable virtual objects is presented and stable and realistic 6D haptic feedback is demonstrated through a clipping task experiment.
Abstract: A new computer haptics algorithm to be used in general interactive manipulations of deformable virtual objects is presented. In multimodal interactive simulations, haptic feedback computation often comes from contact forces. Subsequently, the fidelity of haptic rendering depends significantly on contact space modeling. Contact and friction laws between deformable models are often simplified in up to date methods. They do not allow a "realistic" rendering of the subtleties of contact space physical phenomena (such as slip and stick effects due to friction or mechanical coupling between contacts). In this paper, we use Signorini's contact law and Coulomb's friction law as a computer haptics basis. Real-time performance is made possible thanks to a linearization of the behavior in the contact space, formulated as the so-called Delassus operator, and iteratively solved by a Gauss-Seidel type algorithm. Dynamic deformation uses corotational global formulation to obtain the Delassus operator in which the mass and stiffness ratio are dissociated from the simulation time step. This last point is crucial to keep stable haptic feedback. This global approach has been packaged, implemented, and tested. Stable and realistic 6D haptic feedback is demonstrated through a clipping task experiment.

266 citations

Journal ArticleDOI
TL;DR: This paper presents an original method to generalize the hierarchy-based control schemes to account for unilateral constraints at any priority level, and applies in robotics and computer graphics animation.
Abstract: The control approaches based on the task function formalism, and particularly those structured as a prioritized hierarchy of tasks, enable complex behaviors with elegant properties of robustness and portability to be built. However, it is difficult to consider a straightforward integration of tasks described by unilateral constraints in such frameworks. Indeed, unilateral constraints exhibit irregularities that prevent the insertion of unilateral tasks at any priority level, other than the lowest, of a hierarchy. In this paper, we present an original method to generalize the hierarchy-based control schemes to account for unilateral constraints at any priority level. We develop our method first for task sequencing using only the kinematics description; then, we expand it to the task description, using the operational space formulation. The method applies in robotics and computer graphics animation. Its practical implementation is exemplified by realizing a real-manipulator visual servoing task and a humanoid avatar reaching task; both experiments are achieved under the unilateral constraints of joint limits.

241 citations

01 Jan 2004
TL;DR: This paper reports the progress in tactile interfaces technology in the following areas: teleoperation, telepresence, sensory substitution, 3D surface generation, Braille systems, laboratory prototypes, and games.
Abstract: Virtual reality techniques allow one to interact with synthetic worlds, i.e. virtual environments. Tactile feedback means conveying parameters such as roughness, rigidity, and temperature. These information and many others are obtained thanks to the sense of touch. Tactile feedback is of prime importance in many applications. In this paper we examine the state-of-the-art in tactile interfaces design. Thorough reviews of the literature reveal a significant amount of publications concerning tactile human- machine interfaces, especially onwards the ~1990. This paper reports the progress in tactile interfaces technology in the following areas: teleoperation, telepresence, sensory substitution, 3D surface generation, Braille systems, laboratory prototypes, and games. Different parameters and specifications required to generate and feed back tactile sensation are summarized.

194 citations


Cited by
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Journal ArticleDOI

[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: The field of AR is described, including a brief definition and development history, the enabling technologies and their characteristics, and some known limitations regarding human factors in the use of AR systems that developers will need to overcome.
Abstract: We are on the verge of ubiquitously adopting Augmented Reality (AR) technologies to enhance our percep- tion and help us see, hear, and feel our environments in new and enriched ways. AR will support us in fields such as education, maintenance, design and reconnaissance, to name but a few. This paper describes the field of AR, including a brief definition and development history, the enabling technologies and their characteristics. It surveys the state of the art by reviewing some recent applications of AR technology as well as some known limitations regarding human factors in the use of AR systems that developers will need to overcome.

1,526 citations

Journal ArticleDOI
TL;DR: The open motion planning library is a new library for sampling-based motion planning, which contains implementations of many state-of-the-art planning algorithms, and it can be conveniently interfaced with other software components.
Abstract: The open motion planning library (OMPL) is a new library for sampling-based motion planning, which contains implementations of many state-of-the-art planning algorithms. The library is designed in a way that it allows the user to easily solve a variety of complex motion planning problems with minimal input. OMPL facilitates the addition of new motion planning algorithms, and it can be conveniently interfaced with other software components. A simple graphical user interface (GUI) built on top of the library, a number of tutorials, demos, and programming assignments are designed to teach students about sampling-based motion planning. The library is also available for use through Robot Operating System (ROS).

1,472 citations