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LANDING AN UNMANNED AIR VEHICLE: VISION BASED MOTION ESTIMATION AND NONLINEAR CONTROL

Asian Journal of Control 2008年第3期1卷

作者： Omid Shakernia Yi Ma T. John Koo Shankar Sastry Dept. of Electrical Engineering & Computer Science University of California at Berkeley Berkeley CA94720-1774 U.S.A. Tak-Kuen John Koo received the B.Eng. degree in 1992 in Electronic Engineering and the M.Phil. in 1994 in Information Engineering both from the Chinese University of Hong Kong. From 1994 to 1995 he was a graduate student in Signal and Image Processing Institute at the University of Southern California. He is currently a Ph.D. Candidate in Electrical Engineering and Computer Sciences at the University of California at Berkeley. His research interests include nonlinear control theory hybrid systems inertial navigation systems with applications to unmanned aerial vehicles. He received the Distinguished M.Phil. Thesis Award of the Faculty of Engineering The Chinese University of Hong Kong in 1994. He was a consultant of SRI International in 1998. Currently he is the team leader of the Berkeley AeRobot Team and a delegate of The Graduate Assembly University of California at Berkeley. He is a student member of IEEE and SIAM. S. Shankar Sastry received his Ph.D. degree in 1981 from the University of California Berkeley. He was on the faculty of MIT from 1980-82 and Harvard University as a Gordon McKay professor in 1994. He is currently a Professor of Electrical Engineering and Computer Sciences and Bioengineering and Director of the Electronics Research Laboratory at Berkeley. He has held visiting appointments at the Australian National University Canberra the University of Rome Scuola Normale and University of Pisa the CNRS laboratory LAAS in Toulouse (poste rouge) and as a Vinton Hayes Visiting fellow at the Center for Intelligent Control Systems at MIT. His areas of research are nonlinear and adaptive control robotic telesurgery control of hybrid systems and biological motor control. He is a coauthor (with M. Bodson) of “Adaptive Control: Stability Convergence and Robustness Prentice Hall 1989.” and (with R. Murray and Z. Li) of “A Mathematical Introduction to Robotic Manipulati

In this paper, we use computer vision as a feedback sensor in a control loop for landing an unmanned air vehicle (UAV) on a landing pad. The vision problem we address here is then a special case of the classic ego-motion estimation problem since all feature points lie on a planar surface (the landing pad). We study together the discrete and differential versions of the ego-motion estimation, in order to obtain both position and velocity of the UAV relative to the landing pad. After briefly reviewing existing algorithm for the discrete case, we present, in a unified geometric framework, a new estimation scheme for solving the differential case. We further show how the obtained algorithms enable the vision sensor to be placed in the feedback loop as a state observer for landing control. These algorithms are linear, numerically robust, and computationally inexpensive hence suitable for real-time implementation. We present a thorough performance evaluation of the motion estimation algorithms under varying levels of image measurement noise, altitudes of the camera above the landing pad, and different camera motions relative to the landing pad. A landing controller is then designed for a full dynamic model of the UAV. Using geometric nonlinear control theory, the dynamics of the UAV are decoupled into an inner system and outer system. The proposed control scheme is then based on the differential flatness of the outer system. For the overall closed-loop system, conditions are provided under which exponential stability can be guaranteed. In the closed-loop system, the controller is tightly coupled with the vision based state estimation and the only auxiliary sensor are accelerometers for measuring acceleration of the UAV. Finally, we show through simulation results that the designed vision-in-the-loop controller generates stable landing maneuvers even for large levels of image measurement noise. Experiments on a real UAV will be presented in future work.

关键词： Motion estimation computer vision based control unmanned air vehicle differential flatness

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Automatic seizure detection based on time-frequency analysis and artificial neural networks

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Computational Intelligence and Neuroscience 2007年第unknown期2007卷 1-13页

作者： Tzallas, A.T. Tsipouras, M.G. Fotiadis, D.I. Department of Medical Physics Medical School University of Ioannina GR 451 10 Ioannina Greece Unit of Medical Technology and Intelligent Information Systems Department of Computer Science University of Ioannina GR 451 10 Ioannina Greece Biomedical Research Institute Foundation for Research and Technology-Hellas (BRI-FORTH) University of Ioannina GR 451 10 Ioannina Greece

The recording of seizures is of primary interest in the evaluation of epileptic patients. Seizure is the phenomenon of rhythmicity discharge from either a local area or the whole brain and the individual behavior usually lasts from seconds to minutes. Since seizures, in general, occur infrequently and unpredictably, automatic detection of seizures during long-term electroencephalograph (EEG) recordings is highly recommended. As EEG signals are nonstationary, the conventional methods of frequency analysis are not successful for diagnostic purposes. This paper presents a method of analysis of EEG signals, which is based on time-frequency analysis. Initially, selected segments of the EEG signals are analyzed using time-frequency methods and several features are extracted for each segment, representing the energy distribution in the time-frequency plane. Then, those features are used as an input in an artificial neural network (ANN), which provides the final classification of the EEG segments concerning the existence of seizures or not. We used a publicly available dataset in order to evaluate our method and the evaluation results are very promising indicating overall accuracy from 97.72 to 100.

关键词： .EEG signals epileptic Nonstationary time-frequency EEG recordings timefrequency Automatic Seizure detection of seizures several features

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Evaluating state-of-the-art Treebank-style parsers for Coh-Metrix and other learning technology environments

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Natural Language Engineering 2006年第2期12卷 131-144页

作者： Hempelmann, Christian F. Rus, Vasile Graesser, Arthur C. McNamara, Danielle S. Institute for Intelligent Systems Department of Computer Science The University of Memphis Memphis TN 38120 United States

This paper evaluates four of the most commonly used, freely available, state-of-the-art parsers on a standard benchmark as well as with respect to a set of data relevant for measuring text cohesion, as one example of a learning technology application that requires fast and accurate syntactic parsing. We outline advantages and disadvantages of existing technologies and make recommendations. Our performance report uses traditional measures based on a gold standard as well as novel dimensions for parsing evaluation. To our knowledge, this is the first attempt to evaluate parsers across genres and grade levels for the implementation in learning technology using both gold standard and directed evaluation methods. © 2006 Cambridge University Press.

关键词： computer program listings

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TRACKING DOMAINS FOR UNSTABLE PLANTS WITH SATURATING-LIKE ACTUATORS

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Asian Journal of Control 2008年第4期1卷

作者： V.A. Yakubovich S. Nakaura K. Furuta Vladimir A. Yakubovich is a corresponding member of Russian Academy of Science. Vladimir A. Yakubovich was born in Novosibirsk Russia in 1926. he entered Moscow University in 1946 and graduated in 1949. he received the Candidate of Science degree (Ph.D.) in 1953 and the Doctor of Science degree in 1959 from Leningrad University. In 1959 he joined the Leningrad University and he has remained since then. He is the author of more than 270 papers and a coauthor of seven books in different areas of applied mathematics and control theory. he has worked in parametric resonance theory in the theory of stability of nonlinear systems and in optimization theory. Dr. Yakubovich has served on many scientific committees and editorial boards. he is a member of several scientific socienties in Russia. He was awarded the Norbert Wiener Prize (1991) a prize from the international editorial company “Nauka” for best publication in its journals (1995) and the IEEE Control Systems Award (1996). Since 1991 he has been a corresponding member of the Russian Academy of Sciences. Dept. of Control Engineering Tokyo Institute of Technology Japan. Shigeki Nakaura received his B.S. and M.S. degrees in Control Engineering from the Tokyo Institute of Technology in 1995 and 1997 respectively. He is currently a PhD student of the Tokyo Institute of Technology. His research interests include robotics and intelligent machining. He is a member of SICE JSPE and IEEE. Katsuhisa Furuta was born in Tokyo Japan in 1940. He received his B.S. M.S. and Ph.D. degrees in Engineering from the Tokyo Institute of Technology in 1962 1964 and 1967 respectively. he was a post doctoral fellow at Laval University (Quebec Canada) from July 1967 to August 1969. Since then he has been a member of the teaching staff of the Tokyo Institute of Technology Department of Control Engineering where he is currently a Professor Graduate School of Information Science and Engineering. He was a Russell Severance Springer Professor University of California at

In many mechanical systems, the tracking control is one of the most important issues. Therefore for the unstable system subject to actuator saturation, the domain of the initial states corresponding to an arbitrary reference signal, within which tracking condition can be achieved, is interesting to be considered. In this paper, an approximate tracking domain is derived analytically. First in Theorem 1, for simple case, it is constructed by using the partial Lyapunov function and the absolute stability theory. In the following Theorems 2 and 3, a new idea is used to obtain larger domains. Finally in the last section, a simple numerical example is given.

关键词： Actuator constraint tracking control nonlinear analysis absolute stability

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Comparison of seven approaches for holter ECG clustering and classification

Comparison of seven approaches for holter ECG clustering and...

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29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBS 2007), vol.10

作者： Vaclav Chudacek Milan Petrik George Georgoulas Miroslav Cepek Lenka Lhotska Chrysostomos Stylios Gerstner laboratory at Department of Cybernetics Czech Technical University Czech Republic Czech Republic Department of Cybernetics Center for Machine Perception Czech Technical University Czech Republic Intelligent Control Systems Laboratory Georgia Technology Research Institute Atlanta USA Czech Republic Department of Computer Science and Engineering Neural Computing Group Czech Technical University Czech Republic Czech Republic Department of Cybernetics Gerstner Laboratory Czech Technical University Czech Republic Department of Informatics and Communications Technology TEI Epirus Artas Greece

In this work we present a comparative study, testing selected methods for clustering and classification of holter electrocardiogram (ECG). More specifically we focus on the task of discriminating between normal 'N' beats and premature ventricular 'V' beats. Some of the tested methods represent the state of the art in pattern analysis, while others are novel algorithms developed by us. All the algorithms were tested on the same datasets, namely the MIT-BIH and the AHA databases. The results for all the employed methods are compared and evaluated using the measures of sensitivity and specificity.

关键词： Electrocardiography Testing Decision trees Laboratories Cybernetics Sensitivity and specificity Heart rate variability Clustering algorithms Spatial databases Computational complexity

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Panel: Industry Relationship Development

Panel: Industry Relationship Development

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IEEE International Conference on Information Reuse and Integration (IRI)

作者： Stuart Rubin Shu-Ching Chen Susanne Bahr William A. Gruver Robert Hockett Michael Jiang Gordon K. Lee Michael Leyton June R. Massoud Mariofanna Milanova Antony Satyadas Michael Smith Daniel Yeung SPAWAR Systems Center USA Florida International University USA Florida Institute of Technology USA Emeritus of Engineering Science Intelligent Robotics Corporation-Simon Fraser University USA Cornell University USA Motorola USA San Diego State University USA Center for Discrete Mathematics & Theoretical Computer Science (DIMACS) Rutgers University USA Independent Montreal Canada University of Arkansas Little Rock USA IBM Senior Certified Executive Architect IBM Software Group USA University of California Berkeley USA Hong Kong Polytechnic University Hung Hom Hong Kong China

The purpose of the industrial panel is summarily stated as follows. This panel serves the goal of finding ways to increase industrial participation in the SMC Transaction journals. Only through industrial collaboration can the SMC society maintain financial solvency and an influx of industrial and academic minds into its constituent fields. It is our hope that the industrial panel will provide vision and direction with these ends in mind. Invitees to the panel currently serve or have served as a CEO, president, vice-president, or other ranking executive of a corporation or federal agency that has a vested interest in transitioning research; or, as a dean (any subrank), provost, president, or grant agent of an accredited North American Research University that has experience in marketing patents, or other research products such as software, etc. Several distinguished university professors have also be invited. They have special insight into technology transition, and have a track record of bringing in funding, as appropriate, publication (not necessarily extensive, which helps us to bolster our IEEE Transaction journals as one of the subjects of our planned deliberations). The panel will address, as its primary focus, how to increase the market share of our IEEE SMC Transactions (especially Part C), while maintaining or improving their quality, maintaining or improving their financial solvency, and publishing research that industry and government need done and can share in an open forum.

关键词： Industrial relations USA Councils Sliding mode control Publishing computer industry intelligent robots Competitive intelligence Service robots Mathematics computer science

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Probabilistic bisimulations for quantum processes

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Information and Computation 2007年

作者： Yuan Feng Runyao Duan Zhengfeng Ji Mingsheng Ying State Key Laboratory of Intelligent Technology and Systems Department of Computer Science and Technology Tsinghua University Beijing 100084 China State Key Laboratory of Computer Science Institute of Software Chinese Academy of Sciences Beijing 100084 China

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Verification of Authentication Protocols for Epistemic Goals via SAT Compilation

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Journal of computer science & Technology 2006年第6期21卷 932-943页

作者：苏开乐陈清亮 Abdul Sattar 岳伟亚吕关锋郑锡忠 Department of Computer Science Sun Yat-Sen University Guangzhou 510275 P.R China Institute for Integrated and Intelligent Systems Griffth University Brisbane Qld 4111 Australia College of Computer Science and Technology Beijing University of Technology Beijing 100022 P.R. China Department of Computer Science Brandenburg University of Technology Cottbus 03036 Germany

This paper introduces a new methodology for epistemic logic, to analyze communication protocols that uses knowledge structures, a specific form of Kripke semantics over hostile networks. The paper particularly focuses on automatic verification of authentication protocols. Our approach is based on the actual definitions of a protocol, not on some difficultto-establish justifications. The proposed methodology is different from many previous approaches to automatic verification of security protocols in that it is justification-oriented instead of falsification-oriented, i.e., finding bugs in a protocol. The main idea is based on observations： separating a principal executing a run of protocol from the role in the protocol, and inferring a principal＇s knowledge from the local observations of the principal. And we show analytically and empirically that this model can be easily reduced to Satisfiability （SAT） problem and efficiently implemented by a modern SAT solver.

关键词： authentication protocol formal verification knowledge structure SAT

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Deeper natural language processing for evaluating student answers in intelligent tutoring systems

Deeper natural language processing for evaluating student an...

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21st National Conference on Artificial Intelligence and the 18th Innovative Applications of Artificial Intelligence Conference, AAAI-06/IAAI-06

作者： Rus, Vasile Graesser, Arthur C. Institute for Intelligent Systems Department of Computer Science 373 Dunn Hall Memphis TN 38152 Institute for Intelligent Systems Department of Psychology 373 Dunn Hall Memphis TN 38152

ISBN: (纸本)1577352815

This paper addresses the problem of evaluating students' answers in intelligent tutoring environments with mixed-initiative dialogue by modelling it as a textual entailment problem. The problem of meaning representation and inference is a pervasive challenge in any integrated intelligent system handling communication. For intelligent tutorial dialogue systems, we show that entailment cases can be detected at various dialog turns during a tutoring session. We report the performance of a lexico-syntactic approach on a set of entailment cases that were collected from a previous study we conducted with AutoTutor. Copyright © 2006, American Association for Artificial Intelligence (***). All rights reserved.

关键词： Artificial intelligence

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Dependency-based textual entailment

Dependency-based textual entailment

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FLAIRS 2006 - 19th International Florida Artificial Intelligence Research Society Conference

作者： Rus, Vasile Department of Computer Science Institute for Intelligent Systems University of Memphis Memphis TN 38120 United States

This paper studies the role of dependency information for the task of textual entailment. Both the Text and Hypothesis of an entailment pair are mapped into sets of dependencies and a score is computed that measures the similarity of the two sets. Based on the score an entailment decision is made. Two experiments are conducted to measure the impact of dependencies on the entailment task. In one experiment we compare the dependency-based approach with a baseline approach on a standard data set. In a second experiment, we measure the performance on a subset of the standard data set. The subset is so selected to minimize the effect of other factors, such as word-level information, in the performance measurement process. A brief discussion compares the dependency-based approach to other, similar approaches. Copyright © 2006, American Association for Artificial Intelligence (***). All rights reserved.

关键词： Information technology

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