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OPTIMIZING THE SUBdivision OF ELEMENTS IN DISCONTINUITY MESHING FOR HIERARCHICAL RADIOSITY

International Journal on Artificial Intelligence Tools 2003年第4期12卷 395-411页

作者： IOANNIS A. PANTAZOPOULOS SPYROS G. TZAFESTAS Intelligent Robotics and Automation Laboratory Signals Control and Robotics Division Electrical and Computer Engineering Department National Technical University of Athens Zographou Athens Greece

This paper presents a new topological structure for use in the context of hierarchical radiosity combined with discontinuity meshing. This is most useful for a new strategy adopted for subdividing the elements of a scene consisting of convex polygons. The subdivision is done in a local optimization manner keeping the aspect ratios of produced polygons low. The generated meshes give high visual accuracy.

关键词： Hierarchical radiosity discontinuity meshing mesh pre(post)-processing multigriding aspect-ratio

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Integrating HLA into the trick simulation development toolkit

Integrating HLA into the trick simulation development toolki...

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AIAA Modeling and Simulation Technologies Conference and Exhibit 2003

作者： Crues, Edwin Z. Lin, Alexander Hasan, David A. Titan Corporation Astronautics Engineering Unit 1020 Bay Area Boulevard Suite #200 Houston TX 77058 United States NASA Johnson Space Center Automation Robotics and Simulation Division Houston TX 77058 United States

ISBN: (纸本)9781624100918

The increasing size and complexity of simulations presents a number of challenges to engineering organizations, among them: the expense of developing the models and simulation infrastructure and the need to protect proprietary information which might be a crucial part of the simulated systems. To address these challenges, the United States National Aeronautics and Space Administration (NASA) and the Japanese NAtional Space Development Agency (NASDA) are investigating the use of distributed simulation technologies and applying them to a simulation of the International Space Station (ISS) and the Japanese H-II Transfer Vehicle (HTV). The two principal technologies in this work are the Defense Modeling and Simulation Office's (DMSO) High Level Architecture (HLA) and the NASA Trick Simulation Development Toolkit (Trick). This paper presents brief overviews of HLA and Trick, a discussion of the issues associated with incorporating HLA into Trick, an analysis of a standard HLA example application, and a discussion of techniques used to fit the standard example into Trick. Finally, the paper outlines an example time-based dynamic simulation as a simple demonstration of incorporating HLA capabilities into an existing Trick based simulation. © 2003 by Edwin Z. Crues, Alexander Lin, and David Hasan.

关键词： NASA

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Trick®: A simulation development toolkit

Trick®: A simulation development toolkit

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AIAA Modeling and Simulation Technologies Conference and Exhibit 2003

作者： Paddock, Eddie J. Lin, Alexander Vetter, Keith Crues, Edwin Z. Titan Corporation Astronautics Engineering Unit 1020 Bay Area Boulevard Suite #200 Houston TX 77058 United States NASA Johnson Space Center Automation Robotics and Simulation Division Houston TX 77058 United States

ISBN: (纸本)9781624100918

The Trick®1Simulation Development Toolkit has continually evolved since the 1980s through building dynamic, high-fidelity robotics and space vehicle simulations for NASA at the Johnson Space Center (JSC). Trick has become a JSC standard simulation environment that supports the development and operations of analysis and real-time human-in-the-loop training simulations. The Trick simulation development environment and its associated robotics and space vehicle applications are in use at many JSC facilities. These simulation applications range from personal computer desktop trainers to full scale robotics hardware-in-the-loop facilities and virtual reality systems. Trick provides a data-driven real-time scheduling executive, input processing, data recording, and automatic code generation (ACG). Trick uses parsing and ACG utility processors to generate input/output mechanisms as well as math model function calls. Trick supports C and C++ programming languages for math modeling, and it also has limited support for FORTAN and Ada. The Trick utility suite also provides graphical user, developer and run-time interfaces as well as data products including strip charting. Trick is written in ANSI C, C++, Perl, flex/bison, Tcl/Tk, and UNIX shell scripts. It is very portable and scalable to almost any UNIX platform.

关键词： C++ (programming language)

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Integration of topological and metric maps for indoor mobile robot path planning and navigation 2nd

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2nd Hellenic Conference on Artificial Intelligence, SETN 2002

作者： Zavlangas, Panagiotis G. Tzafestas, Spyros G. Intelligent Robotics and Automation Laboratory Signals Control and Robotics Division Department of Electrical and Computer Engineering National Technical University of Athens Zografou Athens15773 Greece

ISBN: (纸本)3540434720

Autonomous mobile robots need to use spatial information about the environment in order to effectively plan and execute navigation tasks. The information can be represented at different levels of abstraction, ranging from detailed geometric maps to coarse topological maps. Each level is adequate for some sub-task, but not for others. In this paper, we consider the representation of spatial knowledge at two different levels of abstraction, which are commonly considered in the robotics literature: the geometric level, and the topological level. We propose to represent the environment by local metric maps connected into a topological network. This technique allows us to use maps that are not metrically consistent on the global scale, although they are metrically consistent locally. The structure allows also the combination of abstract global reasoning and precise local geometric computations. Moreover, this structure reflects the typical organization of indoor environments, where rooms and hallways define independent but connected local working spaces. To navigate in the environment, the robot uses the topological information to plan a sequence of sectors to traverse, and uses the metric information in each sector to locally move within the sector and to the next one. The functioning of the proposed system with respect to omnidirectional mobile robots and results of simulated experiments are presented. © Springer-Verlag Berlin Heidelberg 2002.

关键词： Abstracting

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An automated tether management system for microgravity extravehicular activities

An automated tether management system for microgravity extra...

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IEEE International Conference on robotics and automation (ICRA)

作者： M.A. Minor C.R. Hirschi R.O. Ambrose Department of Mechanical Engineering University of Utah Salt Lake UT USA Automation Robotics and Simulation Division Robotics Systems Technology Branch Houston TX USA

An automated tether system has been developed for the purpose of improving the efficiency of micro-gravity activities of fully suited astronauts. System features include gripping of multiple anchor types, remote release of the tether from an anchor, and controlled retraction of the tether. Two main mechanisms make up the system. First, a remotely releasable, self-locking robotic gripper with opposing jaws that grasps a variety of anchors such as handrails, tether loops, and guide wires. Second, an automated tether retractor that is capable of active or passive operation. Passive retractor operation saves power by emulating existing safety tether systems and active operation expedites tether retraction and allows towing.

关键词： Grippers robotics and automation Wires Automatic control Safety Control systems Space vehicles Orbital robotics Space technology Space shuttles

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Optimal genetic representation of complete strictly-layered feedforward neural networks

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6th International Work-Conference on Artificial and Natural Neural Networks, IWANN 2001

作者： Raptis, Spyros Tzafestas, Spyros Karagianni, Hermione Intelligent Robotics and Automation Laboratory Division of Signals Control and Robotics Department of Electrical and Electronic Engineering National Technical University of Athens Zographou Campus Athens15773 Greece

ISBN: (纸本)9783540422372

The automatic evolution of neural networks is both an attractive and a rewarding task. The connectivity matrix is the most common way of directly encoding a neural network for the purpose of genetic optimization. However, this representation presents several disadvantages mostly stemming from its inherent redundancy and its lack of robustness. We propose a novel representation scheme for encoding complete strictly-layered feedforward neural networks and prove that it is optimal in the sense that it utilizes the minimum possible number of bits. We argue that this scheme has a number of important advantages over the direct encoding of the connectivity matrix. It does not suffer from the curse of dimensionality, it allows only legal networks to be represented which relieves the genetic algorithm from a number of checking and rejections, and the mapping from the genotypes to phenotypes is one-to-one. Additionally, the resulting networks have a simpler structure assuring an easier learning phase. © Springer-Verlag Berlin Heidelberg 2001.

关键词： Genetic algorithms

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An opposition class piloted mission to Mars using telerobotics for landing site reconnaissance and exploration

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AIP Conference Proceedings 2001年第1期552卷 115-120页

作者： Philip J. Burley Steven E. Fredrickson, Ph.D. Darby F. Magruder John D. Rask 1Orbit Dynamics Branch Flight Design and Dynamics Division Mission Operations Directorate NASA Johnson Space Center Houston Texas 77058 2Special Projects Office Automation Robotics and Simulation Division Engineering Directorate NASA Johnson Space Center Houston Texas 77058 3Robotic Systems Technology Branch Automation Robotics and Simulation Division Engineering Directorate NASA Johnson Space Center Houston Texas 77058 4Ascent/Descent Dynamics Branch Flight Design and Dynamics Division Mission Operations Directorate NASA Johnson Space Center Houston Texas 77058

The authors propose a new architecture for a first piloted mission to Mars. A crew travels to and from Mars in the same type of vehicle as will be used for the first piloted landing mission. Two or three surface rovers travel to Mars separately. The rovers land at widely separated potential human landing sites within a single hemisphere. The piloted vehicle (orbiter) achieves an orbit around Mars with a period equal to one Martian day (sol), so that continuous line-of-sight communications exists between the orbiter and the rovers. The crew operates the rovers from orbit using telerobotics and telepresence technology. The rovers, which have traverse ranges measured in kilometers per day, perform extensive landing site reconnaissance, weather observations, and geological sample collection and analysis, including water detection experiments. The mission lasts approximately 40 days in Mars orbit. Major objectives include rigorous flight test of the piloted vehicle, precision landing site characterization and selection at a level of detail unattainable from orbit, and predeployment of the teleoperated rovers for later use as robotic assistants during human surface missions. All of these objectives can reduce the risk to the first crew to land on Mars. Such a mission could be launched at least one synodic period ahead of the earliest planned piloted landing.

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Fuzzy logic control of a robot manipulator based on visual servoing

Fuzzy logic control of a robot manipulator based on visual s...

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IEEE International Symposium on Industrial Electronics (ISIE)

作者： C.S. Kim W.H. Seo S.H. Han O. Khatib Department of Mechanical Design Graduate School of Kyungnam University Masan South Korea Division of Mechanical Engineering and Automation Kyungnam University Masan South Korea Computer Science and Robotics Laboratory Department University of Stanford Stanford CA USA

ISBN: (纸本)0780370902

In this paper, a solution to a manipulation control problem (target identification and grasping) using a real platform in combination with a vision system is proposed. The task for the end-effector is to approach a randomly placed spherical object of known size. The control law is approximated by using an approach based on fuzzy logic. The controller determines the parameters of the target (a spherical object acquired from the vision system mounted on the manipulator) using a vision algorithm. The fuzzy rules are built in a supervised way, after studying the behavior of the system. Experimental results obtained using an industrial manipulator (AM1 with 6 DOF model in Samsung Electronics Co., Ltd., Korea) are presented.

关键词： Fuzzy logic Robot control Manipulators Visual servoing Control systems Machine vision Fuzzy systems Electrical equipment industry Electronics industry Industrial electronics

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A study on neural networks for vision-based road following of autonomous vehicle

A study on neural networks for vision-based road following o...

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IEEE International Symposium on Industrial Electronics (ISIE)

作者： D.Y. Jeong S.J. Park S.H. Han M.H. Lee T. Shibata Department of Mechanical Design Graduate School of Kyungnam University Masan South Korea School of Electricity and Electronics TongMyong University South Korea Division of Mechanical and Automation Engineering Kyungnam University Masan South Korea School of Mechanical Engineering Pusan National University busan South Korea Robotics Department Mechanical Engineering Laboratory Ministry of International Trade and Industry Japan

ISBN: (纸本)0780370902

This paper describes a neural network control for an autonomous vehicle to follow roadways with a vision camera. Without a complex geometric reasoning from visual image to vehicle-centered representation in conventional studies, the control system transfers the inputs of visual information into the output of steering angle directly. The neural networks replaces the human driving skill of nonlinear relation between vanishing lines of road boundary on the camera image and the steering angle of vehicle on the real ground. In straight and curved road, the driving performances by the proposed control scheme are measured in the configuration of disturbance and white noise correspond to vehicle joggling and sensing error.

关键词： Neural networks Road vehicles Cameras Vehicle driving Remotely operated vehicles Mobile robots Control systems Humans Land vehicles Performance evaluation

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On tracking control of mobile manipulators

On tracking control of mobile manipulators

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IEEE International Conference on robotics and automation (ICRA)

作者： Wenjie Dong Yangsheng Xu Qi Wang Department of Mechanical and Automation Engineering Chinese University of Hong Kong The Seventh Research Division Beijing Aeronautics and Astronautics University Beijing China The Robotics Institute Carnegie Mellon University USA

This paper studies the tracking control problem of mobile manipulators with consideration of the interaction between the mobile platform and the manipulator. A global tracking controller is proposed based on the dynamics of the defined tracking error and the extended Barbalat's lemma. The proposed controller ensures that the full state of the system asymptotically track the given desired trajectory globally in the presence of the system coupling. Extensive simulations presented in the paper show the effectiveness of the proposed approach.

关键词： Manipulator dynamics Vehicle dynamics Aerodynamics Control systems Automatic control robotics and automation Vehicles Stability Mobile robots Error correction

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