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International Conference on Automatic Face and Gesture Recognition

作者： Pedro Martins Jorge Batista Institute for Systems and Robotics Department of Electrical Engineering and Computers FCT-University of Coimbra Portugal

A framework for automatic human head pose estimation from single view images is proposed. The 6DOF head pose was estimated using pose from orthography and scaling with iterations (POSIT) where a statistical anthropometric 3D rigid model is used as an approximation of the human head, combined with active appearance models (AAM) for facial features extraction and tracking. The overall performance of the proposed solution was evaluated comparing the results with a ground-truth data obtained by a pose planar approach. The results show that orientations and head location were, on average, found within 2deg or 1 cm error standard deviations respectively.

关键词： Shape Active appearance model Head Humans Principal component analysis Facial features Application software Deformable models robotics and automation Data mining

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Estimation of vehicle velocity and traffic intensity using rectified images

Estimation of vehicle velocity and traffic intensity using r...

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IEEE International Conference on Image Processing

作者： Cristina Maduro Katherine Batista Paulo Peixoto Jorge Batista ISR-Institute of Systems and Robotics Department of Electrical Engineering FCT-Universidade de Coimbra Coimbra Portugal

This paper presents an automatic method to estimate vehicle velocity and determine the number of vehicles per lane using rectified images. This approach requires the knowledge of two lengths on the ground plane and can be applied to highway scenarios that possess fairly straight lanes in areas near the camera. A scale factor is determined, in order to ascertain vehicle velocity in the sought units. This scale factor associates distances traveled on the image plane with distances on the ground plane and can be obtained by identifying the period and location of the striped highway lanes on the rectified background image. Once the previously referred lines are located it is then possible to locate the highway lane boundaries and, therefore, determine the mean vehicle velocity of each lane.

关键词： Cameras Surveillance Automated highways Image restoration robotics and automation Road transportation Road vehicles Video sequences Computer vision Image segmentation

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A dynamic estimator on SE(3) using range-only measurements

A dynamic estimator on SE(3) using range-only measurements

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IEEE Conference on Decision and Control

作者： A. Alcocer P. Oliveira A. Pascoal R. Cunha C. Silvestre Institute for Systems and Robotics and the Department of Electrical Engineering and Computers Instituto Superior Técnico Lisboa Portugal

ISBN: (纸本)9781424431236

This paper addresses the problem of estimating the attitude and position of a rigid body when the available measurements consist only of the relative distances between a set of body fixed beacons and a set of Earth fixed landmarks. The proposed solution is given in terms of a dynamical system evolving on the Special Euclidean group SE(3), the trajectories of which are shown to locally converge to the actual attitude and position of the rigid body. Local asymptotic stability of the dynamical system is proven by using a suitable Lyapunov function, under the assumption that there is a set of noncoplanar landmarks and beacons. Simulation results are shown to illustrate the behaviour of the proposed estimator.

关键词： Position measurement Distance measurement Earth Computer vision Maximum likelihood estimation Cost function Attitude control Asymptotic stability Lyapunov method Wireless networks

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Annual business and news:: Beginning the 31st year of the Journal of Guidance, Control, and Dynamics

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2008年第1期31卷 1-1页

作者： Schmidt, George T. Aeronautics and Astronautics Massachusetts Institute of Technology (MIT) AIAA Institute of Electrical and Electronics Engineers Russian Federation Academy of Navigation and Motion Control Department of Mechanical and Aerospace Engineering and Engineering Mechanics University of Missouri-Rolla(UMR) Lockheed Electronics Company Center for Space Research University of Texas Austin United States Wright Laboratory Eglin Air Force Base UMR AIAA Guidance Navigation and Control Technical Committee American Automatic Control Council Lockheed Martin Aeronautics Company Palmdale CA United States C4ISR and Unmanned Air Vehicle (UAV) Programs for Air Vehicle Sciences and Systems Accreditation Board Engineering and Technology Inc./Aeronautical National Technical Committee on Guidance Navigation and Control Department of Mechanical and Aerospace Engineering University at Buffalo State University of New York (SUNY) AIAA Technical Committee on GN and C Air Vehicles Directorate Air Force Research Laboratory (AFRL) Wright-Patterson Air Force Base Space Access and Hypersonic Vehicle Guidance and Control Group Control Science Center of Excellence AFRL AIAA Technical Committee on Guidance Navigation and Control Department of Mechanical and Aeronautical Engineering University of California (UC) Davis United States Boeing Company Modernized Flight Control System for the Apache Longbow AIAA Institute of Electrical and Electronics Engineers AHS Jet Propulsion Laboratory California Institute of Technology Boeing Company Flight Sciences and Advanced Design Group Guidance Navigation and Control (GN and C) Systems Engineer Distributed Space Systems NASA Goddard Space Flight Center (GSFC) AIAA GN and C Technical Committee Department of Aerospace Engineering and Engineering Mechanics University of Texas Austin United States Institute of Navigation American Astronautical Society AIAA Guidance Navigation (GN and C) and Control Technical Committee Department of Aerospace Engineering Iowa State University Iowa

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Time-coordinated path following of multiple UAVs over time-varying networks using L1 adaptation

Time-coordinated path following of multiple UAVs over time-v...

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作者： Aguiar, A.P. Pascoal, A.M. Kaminer, I. Dobrokhodov, V. Xargay, E. Hovakimyan, N. Cao, C. Ghabcheloo, R. Instituto Superior Técnico Lisbon Portugal Naval Postgraduate School Monterey CA 93943 United States University of Illinois at Urbana-Champaign Urbana IL 61801 United States University of Connecticut Storrs CT 06269 United States Tampere University of Technology Tampere Finland Institute for Systems and Robotics and Electrical Engineering and Computers Instituto Superior Técnico Portugal Department of Mechanical and Astronautical Engineering Naval Postgraduate School United States Department of Mechanical Science and Engineering University of Illinois Urbana-Champaign United States Department of Mechanical Engineering University of Connecticut United States Department of Intelligent Hydraulics and Automation Tampere University of Technology Finland

ISBN: (纸本)9781563479458

Motivated by challenging mission scenarios, this paper tackles the problem of multi-Unmanned Aerial Vehicle (UAV) cooperative control in the presence of time-varying communication networks. Specifically, we address the problem of steering a fleet of UAVs along given paths (path following) so as to meet spatial and/or temporal constraints. One possible scenario is the situation where a fleet of vehicles is tasked to execute collision-free maneuvers under strict spatial constraints and arrive at their final destinations at exactly the same time. The paper builds on previous work by the authors on coordinated path following and extends it to allow for time-varying communication topologies. Path following control in 3D builds on a nonlinear control strategy that is first derived at the kinematic level (outer-loop control). This is followed by the design of an L1 adaptive output feedback control law that effectively augments an existing autopilot and yields an inner-outer loop control structure with guaranteed performance. Multiple vehicle time-critical coordination is achieved by enforcing temporal constraints on the speed profiles of the vehicles along their paths in response to information exchanged over a dynamic communication network. We address explicitly the situation where each vehicle transmits its coordination state to only a subset of the other vehicles, as determined by the communications topology adopted. Further, we consider the case where the communication graph that captures the underlying communication network topology may be disconnected during some interval of time (or may even fail to be connected at any instant of time) and provide conditions under which the complete coordinated path following closed-loop system is stable. Hardware-in-the-Loop (HITL) simulation results demonstrate the benefits of the developed algorithms. ©;2008 by A. P. Aguiar, I. Kaminer, R. Ghabcheloo, A. M. Pascoal, E. Xargay, N. Hovakimyan, C. Cao, V. Dobrokhodov.

关键词： Cooperative communication

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Vehicle communications: A short survey

Vehicle communications: A short survey

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2007 IADIS International Conference on Telecommunications, Networks and systems, TNS 2007, part of the 1st IADIS Multi Conference on Computer Science and Information systems, MCCSIS 2007

作者： Fernandes, Pedro Nunes, Urbano ISR - Institute of Systems and Robotics Department of Electrical and Computer Engineering University of Coimbra Polo II Coimbra Portugal

ISBN: (纸本)9789728924409

Inter-vehicle communications (IVC) consists in a real application of vehicular ad-hoc networks (VANET) and is part of Intelligent Transportation systems (ITS). An overview of IVC is presented. To guarantee IVC effectiveness, attention must be paid to one of the most important component of the system: the driver and the way he/her receives crucial information. A brief summary of the communication issues is presented. © MCCSIS 2007 .All right reserved.

关键词： Automobile drivers

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A Drowsiness and Point of Attention Monitoring System for Driver Vigilance

A Drowsiness and Point of Attention Monitoring System for Dr...

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International Conference on Intelligent Transportation

作者： Jorge Batista ISR-Institute of Systems and Robotics Department of Electrical Engineering and Computers FCTUC University of Coimbra Coimbra Portugal

This paper presents a framework that combines a robust facial features location with an elliptical face modelling to measure driver's vigilance level. The proposed solution deals with the computation of eyelid movement parameters and head (face) point of attention. The most important facial feature points are automatically detected using a statistically anthropometric face model. After observing the structural symmetry of the human face and performing some anthropometric measurements, the system is able to build a model that can be used in isolating the most important facial feature areas: mouth, eyes and eyebrows. Combination of different image processing techniques are applied within the selected regions for detecting the most important facial feature points. A model based approach is used to estimate the 3D orientation of the human face. The shape of the face is modelled as an ellipse assuming that the human face aspect ratio (ratio of the major to minor axes of the 3D face ellipse) is known. The elliptical fitting of the face at the image level is constrained by the location of the eyes which considerable increase the performance of the system. The system is fully automatic and classifies rotation in all-view direction, detects eye blinking and eye closure and recovers the principal facial features points over a wide range of human head rotations. Experimental results using real images sequences demonstrates the accuracy and robustness of the proposed solution.

关键词： Monitoring Face detection Facial features Humans Robustness Head Eyes Eyelids Performance evaluation Area measurement

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Linear solution for the pose estimation of noncentral catadioptric systems

Linear solution for the pose estimation of noncentral catadi...

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International Conference on Computer Vision (ICCV)

作者： Nuno Goncalves Helder Araujo Institute of Systems and Robotics-Coimbra Department Electrical and Computers Engineering University of Coimbra Coimbra Portugal

This paper presents a linear method to estimate the pose of a noncentral catadioptric system with a quadric shaped mirror in relation to a world reference frame (or local reference frame without loss of generality). The vision system is assumed to be calibrated. The method uses also as input data the structure of the scene. It is proved that any reflection point should belong to an analytical quadric that intersects the mirror quadric itself. This constraint can be written linearly in the 3D scene point coordinates (in the camera reference frame). The unknown pose screw transformation that relates camera and world reference frames can then be used in the linear model, allowing for the construction of a linear equation in the pose transformation elements. Additional constraints are used to force the estimated rotation elements to build an orthogonal matrix. Tests with simulated data and also on real images with different mirrors proved the method to be consistent and to estimate the pose accurately. However, it was also observed that the method is sensitive to noise. The results are compared with another method.

关键词： Cameras Mirrors Machine vision Robot kinematics Optical sensors Robot vision systems Polynomials Layout Optical reflection Testing

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Synchronization in multi-agent systems with switching topologies and non-homogeneous communication delays

Synchronization in multi-agent systems with switching topolo...

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Proceedings of the 46th IEEE Conference on Decision and Control, Pages 4593-5051

作者： Reza Ghabcheloo A. Pedro Aguiar Antonio Pascoal Carlos Silvestre Department Electrical Engineering and Computers and the Institute for Systems and Robotics Instituto Superior Técnico Lisboa Portugal

ISBN: (纸本)9781424414970;1424414970

We study the synchronization problem for n single state agents with linear continuous time dynamics. The agent states are required to synchronize and travel at a desired common speed. This problem arises naturally in the design of coordinated path-following algorithms problem [9] and in studies on the synchronization of Kuramoto oscillator networks [17]. When the desired speed is zero or there are no time delays, it has been shown in the literature that a so-called neighboring control rule makes the states synchronize asymptotically under some connectivity conditions on the union of the underlying communication graphs. We will show that when both the desired speed and the communication delay are non-zero, the behavior of the synchronization system changes significantly. We start by considering asymmetric networks and switching topologies with homogeneous time delays. We then address some issues related to the behavior of the synchronization system in the presence of heterogeneous time delays. We provide connectivity conditions under which the synchronization problem is solved and introduce synchronization laws that compensates for the effect of non-zero speed and time delays. Simulations illustrate the synchronization of three agents.

关键词： synchronous system desired speed Multi-agent systems topology control rule time delay zero speed Communication Research

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Coordinated Path-Following Control for Nonlinear systems with Logic-Based Communication

Coordinated Path-Following Control for Nonlinear Systems wit...

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Proceedings of the 46th IEEE Conference on Decision and Control, Pages 5052-5510

作者： A. Pedro Aguiar Antonio M. Pascoal Department Electrical Engineering and Computers and the Institute for Systems and Robotics Instituto Superior Técnico Lisboa Portugal

ISBN: (纸本)9781424414970;1424414970

We address the problem of designing decentralized feedback laws to force the outputs of decoupled nonlinear systems (agents) to follow geometric paths while holding a desired formation pattern. To this effect we propose a general framework that takes into account i) the topology of the communication links among the agents, ii) the fact that communications do not occur in a continuous manner, and iii) the cost of exchanging information. We provide conditions under which the resulting overall closed loop system is input-to-state stable and apply the methodology for two cases: agents with nonlinear dynamics in strict feedback form and a class of underactuated vehicles. Furthermore, we address explicitly the case where the communications among the agents occur with non-homogenous, possibly varying delays. A coordinated path-following algorithm is derived for multiple underactuated autonomous underwater vehicles. Simulation results are presented and discussed.

关键词： Communication Research Nonlinear systems Closed loop systems Agents Nonlinear Dynamics Standing Orders Autonomous underwater vehicles Feedback Telecommunication links

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