The rapid increase in performance of mass market commodity microprocessors and significant disparity in pricing between PCs and scientific workstations has provided an opportunity for substantial gains in performance ...
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The rapid increase in performance of mass market commodity microprocessors and significant disparity in pricing between PCs and scientific workstations has provided an opportunity for substantial gains in performance to cost by harnessing PC technology in parallel ensembles to provide high end capability for scientific and engineering applications. The Beowulf project is a NASA initiative sponsored by the HPCC program to explore the potential of Pile-of-PCs and to develop the necessary methodologies to apply these low cost system configurations to NASA computational requirements in the Earth and space sciences. This paper describes the technologies and methodologies employed to achieve the increased performance of PCs. Both opportunities afforded by this approach and the challenges confronting its application to real-world problems are discussed in the framework of hardware and software systems as well as the results from benchmarking experiments. Finally, near term technology trends and future directions of the Pile-of-PCs concept are considered.
Over the last few years there has been a phenomenal growth in the use of WWW (World Wide Web) for a wide variety of purposes from advertising and publicity, to collaborative work and teaching. Because it is so easy to...
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Many space robotic systems would be required to operate in uncertain or even unknown environments. In the paper, the problem of identifying such environments for compliance control is considered. In particular, neural...
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Many space robotic systems would be required to operate in uncertain or even unknown environments. In the paper, the problem of identifying such environments for compliance control is considered. In particular, neural networks are used for identifying environments that a robot establishes contact with. Both function approximation and parameter identification (with fixed nonlinear structure and unknown parameters) results are presented. The environment model structure considered is relevant to two space applications: cooperative execution of tasks by robots and astronauts, and sample acquisition during planetary exploration. Compliant motion experiments have been performed with a robotic arm, placed in contact with a single degree-of-freedom electromechanical environment. In the experiments, desired contact forces are computed using a neural network, given a desired motion trajectory. Results of the control experiments performed on robot hardware are described, along with relevant discussions.
Many robotic systems would, in the future, be required to operate in environments that are highly uncertain and possessing means of self-actuation. In this paper, the problem of identifying uncertain environments for ...
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Many robotic systems would, in the future, be required to operate in environments that are highly uncertain and possessing means of self-actuation. In this paper, the problem of identifying uncertain environments for stable contact control is considered. In particular, system parameters are identified under the assumption that environment dynamics have a fixed nonlinear structure. A robotics research arm, placed in contact with a single dof electromechanical environment dynamics emulator, is commanded to move through a desired trajectory. The command is implemented using a compliant control strategy.
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