R. Chatila

INSA, Альтамира, Tamaulipas, Mexico

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Publications (108)14.71 Total impact

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    ABSTRACT: Simultaneous localisation and mapping (SLAM) problem is a non-linear system with dynamic state and measurement dimensions. The full observability of such system was ignored, in spite of the fact that system observability is a fundamental aspect in any state estimation problem. In this article, we present a full observability analysis of the general SLAM model. We show that known landmarks (anchor) solution does not guarantee full observability. Furthermore, we prove that to make the general SLAM model fully observable, a combination of known landmarks and invariant metrics are needed. Moreover, we propose a solution to implement a fully observable SLAM model based on mature landmark and virtual observation concepts. Simulations and experimental results are presented demonstrating the validity of the solutions in real world.
    International Journal of Systems Science 01/2011; · 1.31 Impact Factor
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    ABSTRACT: Autonomous systems have received special attention in the scientific community in the hope of designing a mobile robot with the ability to navigate in an unknown environment and simultaneous localization and mapping (SLAM) problem has been considered as a fundamental issue to realize the above task. Consequently, the robotics community has been engaged in the development and implementation of algorithms and related issues for SLAM. A lot of effort was put into solving this challenging problem [1, 2, 3, 4]. The widely used formulation of the SLAM problem has been the augmented state approach in an estimation theoretic framework, generally based on the extended Kalman filter (EKF) and using the relative observation only to update the state vector [5, 6, 7].
    12/2009: pages 339-348;
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    J. Guitton, J.-L. Farges, R. Chatila
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    ABSTRACT: In order to define an architecture for task and motion planning of a mobile robot, we propose the Cell-RRT path planner that combines the advantages of planning approaches by decomposition of the environment and the advantages of probabilistic approaches. Experiments of the method for various decomposition granularities and various adjustments of the planner settings show that using a bias towards the goal while choosing a random configuration reduces the paths length but can cause failures, that the choice of the criterion for analysing the environment is important, and that the method can profit from a reuse of already made computations in a part of the environment.
    Intelligent Robots and Systems, 2009. IROS 2009. IEEE/RSJ International Conference on; 11/2009
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    Ayman Zureiki, Michel Devy, Raja Chatila
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    ABSTRACT: We described in this chapter, our evaluation of global stereo correspondence methods based on graph cuts. The combination of a local method, able to select a reduced set of possible matches for each pixel, and a global method, based on the graph cuts algorithm, let us to achieve two goals ? Sensibly ameliorate the quality of disparity images obtained only by a local method. ? Avoid the combinatorial explosion of the Graph Cuts method executed without preliminary reduction of the graph. Some optimizations of our algorithm are currently studied. Note that we work always on pre-rectified images, and we produce an integer disparity image: we will study how to adapt this algorithm in order to find stereo matching on non-rectified images. The reduced graph approach allows us to limit the execution time and to use larger disparity ranges. We write the code with the aim to obtain results and not to optimize the performance. In addition, we did not use the best maximum flow algorithm. In the next period, we could very easily improve performances, in order to satisfy as much as possible, real time constraints. Section 4.4 has shown that the reduced graph is able to deal with sub-pixel disparities (real values). Testing this property and obtaining sub-pixel disparity images will be our main objective in our near future works.
    Stereo Vision, 11/2008; , ISBN: 978-953-7619-22-0
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    ABSTRACT: Mobile robots such as explorer rovers need task and path planning abilities in order to fulfill their assigned missions: path planning to plan their movements and task planning to plan their actions. The coupling between these two kinds of planning presents open issues such as the description of the environment and the consideration of geometric constraints that must be verified in order to act and move during an action. This paper addresses these issues by proposing an architecture in which a hierarchical task planner sends requests to a path planner in order to check the feasibility of actions. Requirements allowing the path planner to produce an answer are presented as well as the description of planning operators. Finally, we specify the mechanism and the communication language by which the task planner produces requests and takes into account answers.
    AIP Conference Proceedings. 06/2008; 1019(1):162-167.
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    ABSTRACT: In November of 1998, an expedition from Carnegie Mellon University travelled to the Patriot Hills, Antarctica. The purpose of the expedition was to demonstrate autonomous navigation and robotic classification of meteorites and the characterization of various robotics technologies in a harsh, polar setting. This paper presents early results of experiments performed on this expedition with CCD cameras and laser range finders. It evaluates the ability of these sensors to characterize polar terrain. The effect of weather on this characterization is also analyzed. The paper concludes with a discussion on the suitability of these sensors for Antarctic mobile robots.
    04/2008: pages 59-68;
  • Ayman Zureiki, Michel Devy, Raja Chatila
    ICINCO 2008, Proceedings of the Fifth International Conference on Informatics in Control, Automation and Robotics, Robotics and Automation 1, Funchal, Madeira, Portugal, May 11-15, 2008; 01/2008
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    ABSTRACT: Human-Robot Interaction (HRI) brings new challenges to robotics. We focus in this paper on the decisional issues of HRI enabled robots. We propose a control architecture specifically designed for HRI and present an implemented system that illustrates its main components and their interaction. These components provide integrated abilities to support human-robot collaborative task achievement as well as capacities to elaborate task plans involving humans and robots and to produce legible and socially acceptable behavior.
    Experimental Robotics, The Eleventh International Symposium, ISER 2008, July 13-16, 2008, Athens, Greece; 01/2008
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    Joachim Hertzberg, Raja Chatila
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    ABSTRACT: Artificial intelligence (AI) reasoning technology involving, e.g., inference, planning, and learning, has atrack record with ahealthy number of successful applications. So, can it be used as atoolbox of methods for autonomous mobile robots? Not necessarily, as reasoning on amobile robot about its dynamic, partially known environment may differ substantially from that in knowledge-based pure software systems, where most of the named successes have been registered. This Chapter sketches the main robotics-relevant topics of symbol-based AI reasoning. Basic methods of knowledge representation and inference are described in general, covering both logic- and probability-based approaches. Then, some robotics-related particularities are addressed specially: issues in logic-based high-level robot control, fuzzy logics, and reasoning under time constraints. Two generic applications of reasoning are then described in some detail: action planning and learning. General reasoning is currently not astandard feature onboard autonomous mobile robots. Beyond sketching the state of the art in robotics-related AI reasoning, this Chapter points to the involved research problems that remain to be solved towards that end. The Chapter first reviews knowledge representation and deduction in general (Sect.9.1),and then goes into some detail regarding reasoning issues that are considered particularly relevant for applications in robots (Sect.9.2). Having presented reasoning methods, we then enter the field of generic reasoning applications, namely, action planning (Sect.9.3) and machine learning (Sect.9.4). Section9.5 concludes.
    12/2007: pages 207-223;
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    ABSTRACT: Sensor-based dynamic path modification is one of powerful issues to combine planning and reactive control. This paper treats problems related to flexible trajectories implementation and presents solutions to connect functional levels from the planning to the execution. A general dynamic path structure is proposed and discussed including execution needs and constraints. Implementation algorithms are then developed and presented for general metrics and execution contexts. Finally, solutions for car-like mobile robots are encapsulated in a complete system joining these different levels and mange there functional coherence.
    12/2007: pages 289-300;
  • Abedallatif Baba, Raja Chatila
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    ABSTRACT: This paper presents experiments in dynamic targets detection using panoramic images, which represent rich visual sources of global scenes around a robot. Moving targets (people) are distinguished as foreground pixels in binary images detected using a modified optical flow approach where the intensity of lighting source is variable. The directions of detected targets are determined using two strategies; the first one is convenient for unfolded panoramic images; it searches most probable regions in the last binary image by calculating a histogram of foreground pixels on its columns. The second approach is applied on raw panoramic images; it regroups foreground pixels using a technique that generates a new pixel’s intensity depending on the intensities of its neighbors.
    12/2007: pages 215-227;
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    A. Zureiki, M. Devy, R. Chatila
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    ABSTRACT: Some recent stereo matching algorithms are based on graph cuts. They transform the matching problem to a minimisation of a global energy function. The minimisation can be done by finding out an optimal cut in a special graph. Different methods were proposed to construct the graph. But all of them, consider for each pixel, all possible disparities between minimum and maximum values. In this article, a new method is proposed: only some potential values in the disparity range are selected for each pixel. These values can be found using a local analysis of stereo matching. This method allows us to make wider the disparity range, and at the same time to limit the volume of the graph, and therefore to reduce the computation time.
    Image Processing, 2007. ICIP 2007. IEEE International Conference on; 01/2007
  • J. Held, A. Lampe, R. Chatila
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    ABSTRACT: Determining the performance of a robot is a challenge because success or failure depends not only on the capabilities of the robot but on the difficulties of the environment as well. This paper presents a method of understanding the performance of a robot with respect to its environment through the interaction of a set of metrics. Metric interactions are learned in a dynamic Bayesian network and placed in a probabilistic systems model called a system map, which is used to understand how the metrics relate both to each other and to a partially known environment. Initial results presented here demonstrate how this model identifies environmental dependencies and how performance can be predicted even in an uncertain environment
    Intelligent Robots and Systems, 2006 IEEE/RSJ International Conference on; 11/2006
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    ABSTRACT: Rackham is an interactive robot-guide that has been used in several places and exhibitions. This paper presents its design and reports on results that have been obtained after its deployment in a permanent exhibition. The project is conducted so as to incrementally enhance the robot functional and decisional capabilities based on the observation of the interaction between the public and the robot. Besides robustness and efficiency in the robot navigation abilities in a dynamic environment, our focus was to develop and test a methodology to integrate human-robot interaction abilities in a systematic way. We first present the robot and some of its key design issues. Then, we discuss a number of lessons that we have drawn from its use in interaction with the public and how that will serve to refine our design choices and to enhance robot efficiency and acceptability
    Robot and Human Interactive Communication, 2006. ROMAN 2006. The 15th IEEE International Symposium on; 10/2006
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    ABSTRACT: The Aurora programme is the European Space Agency programme of planetary exploration focused primarily on Mars. Although the long-term goals of Aurora are uncertain, the early phases of the Aurora programme are based on a number of robotic explorer missions – the first of these is the ExoMars rover mission currently scheduled for launch in 2013 (originally 2011). The ExoMars rover – developed during a Phase A study – is a 240 kg Mars rover supporting a 40 kg payload (called Pasteur) of scientific instruments specifically designed for astrobiological prospecting to search for evidence of extant or extinct life. In other words, ExoMars represents a new approach to experimental astrobiology in which scientific instruments are robotically deployed at extraterrestrial environments of astrobiological interest. Presented is an outline of the design of the rover, its robotic technology, its instrument complement and aspects of the design decisions made. ExoMars represents a highly challenging mission, both programmatically and technologically. Some comparisons are made with the highly successful Mars Exploration Rovers, Spirit and Opportunity.
    International Journal of Astrobiology. 06/2006; 5(03):221 - 241.
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    A. Lampe, R. Chatila
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    ABSTRACT: Measuring the performance of robots, and more precisely of autonomous robots dealing with complex and changing environment, is a long standing issue. There is today no satisfactory known metric to measure quantitatively and precisely how a robot system satisfies accurately the specification expectations, neither do we know how to qualify and delineate in general the operational domains of the robot. This paper presents an approach aiming at qualifying robot autonomy. We present a method based on the measure of robot performance in achieving a given task related to environment complexity. In order to test a large number of tasks and environment configurations, we have designed a robot simulator that allows the use of the same algorithms implemented on the real robot and in simulation. To illustrate the work, we present results based on hundreds of simulations of a navigation mission and compare robot performance when algorithm parameters change
    Robotics and Automation, 2006. ICRA 2006. Proceedings 2006 IEEE International Conference on; 06/2006
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    ABSTRACT: This paper presents the approach, algorithms and processes we developed to perform autonomous navigation in a natural environment. After a description of the global approach, we discuss the characteristics of natural environment representations. Then the perception functions for terrain mapping and robot localization, as well as motion planning are described. Navigation strategies for selecting perception tasks and subgoals for motion planning are proposed. The current state of integration in the experimental test bed EDEN is finally presented. Results from this experiment illustrate the approach troughout the paper.
    04/2006: pages 423-443;
  • Simon Lacroix, Raja Chatila
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    ABSTRACT: This paper presents an experimented approach to autonomous robot navigation in an unknown natural environment. The approach involves several levels of reasoning, several environment representations, and three different motion modes. We focus on the navigation level of the whole system, which is in charge of reaching a distant goal by selecting sub-goals to reach, motion modes to apply, and perception tasks to execute for this purpose. We present how a terrain model dedicated to the navigation process is built on the 3D data acquired by the robot, and we describe an approach to tackle the difficult problem of planning perception and motion tasks. Experimental results on a realistic test site are presented and discussed.
    04/2006: pages 538-547;
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    ABSTRACT: A cross-country rover cannot rely in general on permanent and immediate communications with a control station. This precludes direct teleoparation of its motions. It has therefore to be endowed with a large autonomy in achieving its navigation. We have designed and experimented with the mobile robot ADAM a complete system for autonomous navigation in a natural unstructured environment. We describe this work in this paper. The approach is primarly based on the adaptation of the perception and motion actions to the environment and to the status of the robot. The navigation task involves several levels of reasoning, several environment representations, and several action modes. The robot is able to select sub-goals, navigation modes, complex trajectories and perception actions according to the situation.
    04/2006: pages 1-19;
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    P. Menezes, F. Lerasle, J. Dias, R. Chatila
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    ABSTRACT: This article describes a method to track 3D articulated structures from a monocular perspective image sequence using a particle filter. This structure is composed of a set of linked degenerated quadrics (cones) which are truncated by pairs of planes also modelled as degenerated quadrics. This set of truncated cones is connected by joints containing one or more degrees of freedom. The method is based upon the estimation of the contours of the structure's silhouette projected on the image plane, to validate each of the particles which correspond to proposed configurations. This validation is performed using a criterion that combines a measure based on the contours, a measure of similarity between the colour distribution around a point on the structure and a reference distribution, and other criteria that reinforce the overall cost function. The results show the feasibility of the approach when using a single camera to track a 3D model containing eight degrees of freedom
    Humanoid Robots, 2005 5th IEEE-RAS International Conference on; 01/2006

Publication Stats

2k Citations
14.71 Total Impact Points


  • 2009–2011
    • INSA
      Альтамира, Tamaulipas, Mexico
  • 2007
    • University of Toulouse
      Tolosa de Llenguadoc, Midi-Pyrénées, France
  • 2006
    • University of Surrey
      Guilford, England, United Kingdom
    • ARC Centre of Excellence for Autonomous Systems
      Sydney, New South Wales, Australia
  • 2000
    • Carnegie Mellon University
      • Robotics Institute
      Pittsburgh, Pennsylvania, United States
  • 1992
    • Fatec Sao Jose dos Campos
      São José dos Campos, São Paulo, Brazil