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International IEEE Conference on Intelligent systems, IS

作者： T.G.B. Amaral M.M. Crisostomo V.F. Pires Supenor School of Technology of Setlibal Polytechnic Institute of Setubal Setubal Portugal Institute of Systems and Robotics Electrical Engineering Department University of Coimbra Coimbra Portugal CAUTL I.S.T Technical University of Lisbon Portugal Superior School of Technology of Setúbal Polytechnic Institute of Setúbal Setubal Portugal

A new approach for an adaptive neuro-fuzzy inference system for modeling and control is proposed. This approach uses a general regression neural network with a different learning capability from the classical clustering algorithm normally used by this specific network. The antecedent parameters of the regression network are obtained through an iterative grid partition process instead of the usual gradient descent algorithm or the classical grid partition method in the literature of neural network modeling. The membership functions used in the antecedent part are asymmetric and with varying shapes (triangles, gaussian, trapezoidal, etc) which is less common in the fuzzy modeling literature. The consequent parameters are obtained using the least squares estimates algorithm. In the simulation, the adaptive neuro-fuzzy inference system architecture is used to model a nonlinear function and to control the motion of a helicopter in the hover flight mode with promising results.

关键词： Adaptive systems Programmable control Adaptive control Partitioning algorithms Neural networks Clustering algorithms Inference algorithms Iterative algorithms Iterative methods Shape

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A new model of the visual feedback coordinate transformation in humans based on disturbance noise and feedback error that accounts for time delays

A new model of the visual feedback coordinate transformation...

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IEEE International Workshop on Intelligent Robots and systems (IROS)

作者： E. Oyama K.F. MacDorman T. Maeda S. Tachi A. Agah Science and Technology (AIST) National Institute for Advanced Industrial Science and Technology Tsukuba Ibaraki Japan Intelligent Robotics Laboratory Graduate School of Systems Engineering Wakayama University Wakayama Japan School of Engineering University of Tokyo Bunkyo Tokyo Japan Department of Electrical Engineering and Computer Science University of Kansas Lawrence KS USA

An essential factor in understanding the motor learning capability of humans, is the coordinate transformation learning of the visual feedback controller. Although a number of learning models for the visual feedback controller have been proposed, none has been able to establish a definitive approach. In our previous work, we have suggested a learning model that uses disturbance noise and the feedback error signal to learn the human visual feedback controller's coordinate transformation. However, the model does not fully consider the time delay in the visual feedback control loop. This paper presents a modified learning model taking into account the time delay and the convergence properties of the model. Numerical simulations are presented to illustrate the effectiveness of the proposed approach.

关键词： Humans Delay effects Adaptive control Error correction Biological system modeling Feedback control Convergence Kinematics Intelligent robots Velocity control

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Assuring a sea vehicles science and technology base for transforming the 21st-century Navy

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NAVAL ENGINEERS JOURNAL 2002年第3期114卷 103-115页

作者： Metrey, RE Truver, SC Whitman, EC Wright, MA RICHARD E. METREY retired from U.S. government service in January 2001 having served as the director of the Naval Surface Warfare Center Carderock Division and prior to formation of the Carderock Division as the technical director of the David Taylor Research Center for a combined total of 15 years. Prior to serving as the technical director of the David Taylor Research Center Mr. Metrey held key positions in the Navy secretariat among them serving as the deputy assistant secretary of the Navy for surface warfare and the principal advisor to the assistant secretary of the Navy (research engineering and systems). He holds a bachelor of science degree in mechanical engineering from Marquette University Milwaukee Wisconsin and a master of science degree in mechanical engineer-ing from George Washington University Washington D.C. DR. SCOTT C. TRUVER is group vice president National Security Studies Anteon Corporation and directs the Center for Security Strategies and Operations in Anteon's Systems Engineering Group. Since 1972 he has participated in numerous studies for government and private industry in the United States and abroad he has also written extensively for U.S. and foreign publications. He has supported key offices in the Navy Secretariat Office of the Chief of Naval Operations and Headquarters U.S. Marine Corps Navy Systems Commands and laboratories and other Navy and Marine Corps commands and activities. Dr. Truver holds a doctor of philosophy degree in marine policy studies (1978)—the first Ph.D. in this field ever awarded by an institute of higher education—and a master of arts degree in political science and international relations (1974) from the University of Delaware where he held research and university fellowships. He also holds a bachelor of arts degree in political science from Susquehanna University (1972) and is a 1968 graduate of Forrest Sherman High School Naples Italy. DR. EDWARD C. WHITMAN serves as senior advisor science policy in Anteon's Center for Security St

With general agreement among the government and commercial sectors on the importance of maintaining both naval supremacy around the world and viable maritime industries at home, the need for developing a "critical mass" of supporting science and relevant engineering practice should be apparent. Moreover, with increasing calls for "partnership" between government and industry as a key element in revitalizing U.S. shipbuilding, the existing public-sector infrastructure of research and development centers and their associated technology base are unique resources. More urgently, achieving the George W Bush administration's goal for widespread "transformation" of the U.S. armed services - the Navy and Coast Guard among them - will require creating new, innovative technologies to support advanced naval platforms for the agile, survivable, and affordable sea-going forces of the 21st century. These factors create an urgent need to reemphasize the importance of a robust technology base in marine engineening for both national and economic security. This paper reviews the arguments for increasing government support for these important disciplines. It further proposes several alternatives - driven by national economic realities - for collaboration between the public and private sectors in creating and sustaining a focal point for maritime technology at the Carderock Division of the Naval Surface Warfare Center, currently the Navy's "flagship" facility for naval platform architecture and marine systems engineering. In his seminal work, The Influence of Seapower Upon History, Alfred Thayer Mahan traced a clear connection between the sea power of ocean-going nations and their civilian maritime infrastructure-the fishing fleets, merchant marine, shipyards, harbors, port facilities, and experienced manpower that create and maintain traditions of seafaring within the lifeblood of the state. He noted: Seapower in the broad sense... includes not only the military strength afloat that r

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Intelligent Robotic systems - SIRS'99

Intelligent Robotic Systems - SIRS'99

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7th Symposium on Intelligent Robotic systems

作者： Araujo, H.J. Dias, J.M. Department of Electrical Engineering Institute of Systems and Robotics University of Coimbra 3030 Coimbra Portugal

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Integrating laser and infrared sensors for learning dynamic self-organizing world maps

Integrating laser and infrared sensors for learning dynamic ...

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International Conference on Multisensor Fusion and Integration for Intelligent systems (MFI)

作者： R. Araujo D. Lourenco G. Ferreira Institute for Systems and Robotics (ISR) and Electrical Engineering Department University of Coimbra Coimbra Portugal

Mobile robots require the ability to build their own maps to operate in unknown environments. This article introduces a new online method for learning world maps in non-static worlds. The new approach expands the previously proposed method by Araujo et al. (1998, 1999), based on the fuzzy ART neural architecture (FARTNA) towards the application in non-static worlds. For this purpose we introduce the prune-able fuzzy ART neural architecture (PAFARTNA) which extends the FARTNA self-organizing neural network to include the ability to selectively remove recognition categories. A method is proposed for the perception of object removals, and integrated with the PAFARTNA. To study and experimentally validate the proposed methods we integrated sensor information from a laser range finder sensor and a ring of infrared range sensors. Results of experiments with a Nomad 200 mobile robot are presented, demonstrating the effectiveness of the proposed methods.

关键词： Infrared sensors Subspace constraints Solid modeling Mobile robots Robot sensing systems Sonar navigation Computational efficiency Buildings Sensor phenomena and characterization Gas insulated transmission lines

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Shape tracking using centroid-based methods 3rd

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3rd International Workshop on Energy Minimization Methods in Computer Vision and Pattern Recognition, EMMCVPR 2001

作者： Abrantes, Arnaldo J. Marques, Jorge S. Department of Electrical and Computer Engineering Instituto Superior de Engenharia de Lisboa Lisbon Portugal Institute for Systems and Robotics Instituto Superior Técnico Lisbon Portugal

ISBN: (纸本)3540425233

Algorithms for tracking generic 2D object boundaries in a video sequence should not make strong assumptions about the shapes to be tracked. When only a weak prior is at hand, the tracker performance becomes heavily dependent on its ability to detect image features;to classify them as informative (i.e., belonging to the object boundary) or as outliers;and to match the informative features with corresponding model points. Unlike simpler approaches often adopted in tracking problems, this worklo oks at feature classification and matching as two unsupervised learning problems. Consequently, object tracking is converted into a problem of dynamic clustering of data, which is solved using competitive learning algorithms. It is shown that competitive learning is a key technique for obtaining accurate local motion estimates (avoiding aperture problems) and for discarding the outliers. In fact, the competitive learning approach shows several benefits: (i) a gradual propagation of shape information across the model;(ii) the use of shape and noise models competing for explaining the data;and (iii) the possibility of adopting high dimensional feature spaces containing relevant information extracted from the image. This workextends the unified framework proposed by the authors in [1]. © Springer-Verlag Berlin Heidelberg 2001.

关键词： Learning algorithms

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Fusing of image and inertial sensing for camera calibration

Fusing of image and inertial sensing for camera calibration

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International Conference on Multisensor Fusion and Integration for Intelligent systems (MFI)

作者： J. Lobo J. Dias Institute of Systems and Robotics Electrical Engineering Department University of Coimbra Coimbra Portugal

Explores the integration of inertial sensor data with vision. A method is proposed for the estimation of camera focal distance based on vanishing points and inertial sensors. Visual and inertial sensing are two sensory modalities that can be explored to give robust solutions on image segmentation and recovery of 3D structure from images, increasing the capabilities of autonomous vehicles and enlarging the application potential of vision systems. We show that using just one vanishing point, obtained from two parallel lines belonging to some levelled plane, and using the cameras attitude taken from the inertial sensors, the unknown scaling factor f in the camera's perspective projection can be estimated. The quality of the estimation of f depends on the quality of the vanishing point used and the noise level in the accelerometer data. Nevertheless it provides a reasonable estimate for a completely uncalibrated camera. The advantage over using two vanishing points is that the best vanishing point can be chosen, and that in indoors environment the vanishing point point can sometimes be obtained from the scene without placing any specific calibration target.

关键词： Cameras Calibration Robustness Image segmentation Remotely operated vehicles Mobile robots Machine vision Noise level Accelerometers Indoor environments

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Issues on the geometry of central catadioptric image formation

Issues on the geometry of central catadioptric image formati...

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Conference on Computer Vision and Pattern Recognition (CVPR)

作者： J.P. Barreto H. Araujo Institute of Systems and Robotics Department of Electrical and Computer Engineering University of Coimbra Coimbra Portugal

ISBN: (纸本)0769512720

An imaging system with a single effective viewpoint is called a central projection system. The conventional perspective camera is an example of a central projection system. systems using mirrors to enhance the field of view while keeping a unique center of projection are also examples of central projection systems. Perspective image formation can be described by a linear model with well known properties. In general central catadioptric imaging, the mapping between points in the world and in the image is highly nonlinear. The paper establishes a general model for central catadioptric image formation made up of three functions: a linear function mapping the world into an oriented projective plane, a nonlinear transformation between two oriented projective planes, and a collineation in the plane. The model is used to study issues in the projection of lines. The equations and geometric properties of general catadioptric imaging of lines are derived. The application of the results in auto-calibration of central catadioptric systems and reconstruction are discussed. A method to calibrate the system using three line images is presented.

关键词： Cameras Mirrors Nonlinear equations Application software Data mining Computational geometry Robot vision systems Computer vision Surveillance Virtual reality

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Multi-echo technique for feature detection and identification using simple sonar configurations

Multi-echo technique for feature detection and identificatio...

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IEEE/ASME (AIM) International Conference on Advanced Intelligent Mechatronics

作者： F. Moita U. Nunes Electrical Engineering Department ISEC-Coimbra Polytechnic Institute Coimbra Portugal Institute for Systems and Robotics DEE Coimbra University Coimbra Portugal

ISBN: (纸本)0780367367

This work presents the study and development of sonar sensor configurations and processing methods with capability to detect and identify planes, edges and corners. The systems presented can be easily applied to settled robots or new platforms to improve the quality and quantity of ultrasonic data. No special configurations as arrays or cells of sensors are used in this work, only standard configurations that can be found and applied in a great number of mobile robots. New multi-echo functionalities are introduced and combined with EERUF, providing a new ME-EERUF (Multi-Echo Error Eliminating Rapid Ultrasonic Firing) method that simultaneously increases the sonar acquisition rate and provides inter-sensor measurements, necessary to implement feature detection and identification algorithms. Sonar feature-based and grid-based maps are built and integrated online using Bayesian probabilistic approaches. Experimental results using data collected in a specular indoor environment are presented in the paper.

关键词： Sonar detection Computer vision Ultrasonic imaging Robot sensing systems Sonar measurements Acoustic sensors Sensor arrays Mobile robots Ultrasonic transducers Sensor systems

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Development of InP-based test structures for optical MEMS applications

Development of InP-based test structures for optical MEMS ap...

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International Symposium Semiconductor Device Research (ISDRS)

作者： M. Pruessner R. Grover L. Calhoun R. Ghodssi Laboratory for Physical Sciences College Park MD USA The Institute for Systems Research ISR University of Maryland College Park MD USA Department of Electrical and Computer Engineering University of Maryland College Park MD USA

ISBN: (纸本)0780374320

III-V semiconductors such as InP have a direct bandgap and thus allow active optical devices such as lasers and optical amplifiers to be realized. The monolithic integration of InP based active optical devices with MEMS actuators will enable a new generation of versatile wavelength division multiplexed (WDM) devices from lossless switches to tunable lasers and optical filters to be realized at the 1.55 /spl mu/m communications wavelength. While the electro-mechanical properties of silicon are well known,, those of InP must first be studied before InP-based optical micro-electro-mechanical systems (MEMS) can be realized. This can be done by the M-Test, which utilizes electrostatically actuated beams to obtain bending and stress parameters of thin films. An applied voltage between a beam and substrate causes the beam to bend down toward the substrate. The electrostatic force increases as 1/g/sup 2/ where g is the beam-to-substrate gap. The mechanical bending force of the beam is proportional to k(/spl Delta/g) where /spl Delta/g is the change in beam to substrate gap and k is the spring constant of the beam. The spring constant k is dependent on both material properties as well as beam geometry. Because the electrostatic and mechanical forces increase at different rates, it should be clear that an instability point exists at which the two forces no longer balance and the beam is pulled in to the substrate. This instability is known to occur at 2/3 the original beam to substrate gap. By measuring the pull in voltage for various beam geometries, Young's modulus and intrinsic stress of the beam material can be found. Both properties are fundamental for MEMS design.

关键词： Testing Micromechanical devices Substrates Optical filters Optical films Indium phosphide Optical devices Stimulated emission Semiconductor optical amplifiers Wavelength division multiplexing

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