13,960 research outputs found

    On Advanced Mobility Concepts for Intelligent Planetary Surface Exploration

    Get PDF
    Surface exploration by wheeled rovers on Earth's Moon (the two Lunokhods) and Mars (Nasa's Sojourner and the two MERs) have been followed since many years already very suc-cessfully, specifically concerning operations over long time. However, despite of this success, the explored surface area was very small, having in mind a total driving distance of about 8 km (Spirit) and 21 km (Opportunity) over 6 years of operation. Moreover, ESA will send its ExoMars rover in 2018 to Mars, and NASA its MSL rover probably this year. However, all these rovers are lacking sufficient on-board intelligence in order to overcome longer dis-tances, driving much faster and deciding autonomously on path planning for the best trajec-tory to follow. In order to increase the scientific output of a rover mission it seems very nec-essary to explore much larger surface areas reliably in much less time. This is the main driver for a robotics institute to combine mechatronics functionalities to develop an intelligent mo-bile wheeled rover with four or six wheels, and having specific kinematics and locomotion suspension depending on the operational terrain of the rover to operate. DLR's Robotics and Mechatronics Center has a long tradition in developing advanced components in the field of light-weight motion actuation, intelligent and soft manipulation and skilled hands and tools, perception and cognition, and in increasing the autonomy of any kind of mechatronic systems. The whole design is supported and is based upon detailed modeling, optimization, and simula-tion tasks. We have developed efficient software tools to simulate the rover driveability per-formance on various terrain characteristics such as soft sandy and hard rocky terrains as well as on inclined planes, where wheel and grouser geometry plays a dominant role. Moreover, rover optimization is performed to support the best engineering intuitions, that will optimize structural and geometric parameters, compare various kinematics suspension concepts, and make use of realistic cost functions like mass and consumed energy minimization, static sta-bility, and more. For self-localization and safe navigation through unknown terrain we make use of fast 3D stereo algorithms that were successfully used e.g. in unmanned air vehicle ap-plications and on terrestrial mobile systems. The advanced rover design approach is applica-ble for lunar as well as Martian surface exploration purposes. A first mobility concept ap-proach for a lunar vehicle will be presented

    Organização e armazenamento de arquivos de back up de banco de dados.

    Get PDF
    bitstream/CNPTIA/10060/1/doc33.pdfAcesso em: 29 maio 2008

    Procedimento para criação do ambiente de armazenamento em banco de dados da Agência de Informação da Embrapa.

    Get PDF
    Introdução. Apresentação dos comandos utilizados na criação. Do ambiente de trabalho da Agência. Descrição dos comandos utilizados na criação. Do ambiente de trabalho da Agência. Scripts de comandos. Considerações finais.bitstream/CNPTIA/9944/1/doc19.pdfAcesso em:28 maio 2008

    Using multiple related ontologies in a fuzzy information retrieval model.

    Get PDF
    With the Semantic Web progress many independently developed distinct domain ontologies have to be shared and reused by a variety of applications. The use of ontologies in information retrieval applications allows the retrieval of semantically related documents to an initial users´ query. This work presents a fuzzy information retrieval model for improving the document retrieval process considering a knowledge base composed of multiple domain ontologies that are fuzzy related. Each ontology can be represented independently as well as their relationships. This knowledge organization is used in a novel method to expand the user initial query and to index the documents in the collection. Experimental results show that the proposed model presents better overall performance when compared with another fuzzy-based approach for information retrieval.SBIA 2008

    Estudo comparativo dos ambientes para ensino a distância Web Course Tools e AulaNet.

    Get PDF
    Este trabalho apresenta um levantamento das caracterrsticas e um estudo comparativo entre dois ambientes de autoria e aplicação de cursos a distância presentes no mercado. Para este estudo foram utilizados os ambientes Web Course Tools WebCT, versão 30, desenvolvido pela Universidade de Columbia, no Canadá, e o AulaNet, versão 1 .2, desenvolvido pela Pontifícia Universidade Católica do Rio de Janeiro.bitstream/item/76663/1/CNPTIA-COM.TEC.-9-00.pd

    Avaliação de plantas subespontâneas de melancia nos campos experimetais da Embrapa Semi-Árido.

    Get PDF
    Com o objetivo de examinar a variação existente em plantas subespontâneas encontradas nas Estações da Embrapa Semi-Árido (Campo Experimental de Bebedouro, Campo Experimental de Mandacaru e Campo Experimental da Caatinga), se fez uma coleta de sementes e frutos nas mesmas

    Procedimentos para elaboração de um curso a distância.

    Get PDF
    Exemplo de um ambiente de curso a distância. Descrição do procedimento para elaboração de um curso a distância: Estabelecimento de contato com os clientes que estão requisitando o curso a distância. Identificação de requisitos gerais, requisitos funcionais e requisitos computacionais. Preparação do material do curso para WWW. Implantação do curso.bitstream/CNPTIA/9214/1/DOCUMENTO6int.pdfAcesso em: 29 maio 2008
    corecore