Integrated architecture for vision-based indoor localization and mapping of a quadrotor micro-air vehicle

Atualmente os sistemas de pilotagem autónoma de quadricópteros estão a ser desenvolvidos de forma a efetuarem navegação em espaços exteriores, onde o sinal de GPS pode ser utilizado para definir waypoints de navegação, modos de position e altitude hold, returning home, entre outros. Contudo, o problema de navegação autónoma em espaços fechados sem que se utilize um sistema de posicionamento global dentro de uma sala, subsiste como um problema desafiante e sem solução fechada. Grande parte das soluções são baseadas em sensores dispendiosos, como o LIDAR ou como sistemas de posicionamento externos (p.ex. Vicon, Optitrack). Algumas destas soluções reservam a capacidade de processamento de dados dos sensores e dos algoritmos mais exigentes para sistemas de computação exteriores ao veículo, o que também retira a componente de autonomia total que se pretende num veículo com estas características. O objetivo desta tese pretende, assim, a preparação de um sistema aéreo não-tripulado de pequeno porte, nomeadamente um quadricóptero, que integre diferentes módulos que lhe permitam simultânea localização e mapeamento em espaços interiores onde o sinal GPS ´e negado, utilizando, para tal, uma câmara RGB-D, em conjunto com outros sensores internos e externos do quadricóptero, integrados num sistema que processa o posicionamento baseado em visão e com o qual se pretende que efectue, num futuro próximo, planeamento de movimento para navegação. O resultado deste trabalho foi uma arquitetura integrada para análise de módulos de localização, mapeamento e navegação, baseada em hardware aberto e barato e frameworks state-of-the-art disponíveis em código aberto. Foi também possível testar parcialmente alguns módulos de localização, sob certas condições de ensaio e certos parâmetros dos algoritmos. A capacidade de mapeamento da framework também foi testada e aprovada. A framework obtida encontra-se pronta para navegação, necessitando apenas de alguns ajustes e testes.

Age, pollen and spores of ODP Site 175-1082

The present-day condition of bipolar glaciation characterized by rapid and large climate fluctuations began at the end of the Pliocene with the intensification of the Northern Hemisphere continental glaciations. The global cooling steps of the late Pliocene have been documented in numerous studies of Ocean Drilling Program (ODP) sites from the Northern Hemisphere. However, the interactions between oceans and between land and ocean during these cooling steps are poorly known. In particular, data from the Southern Hemisphere are lacking. Therefore I investigated the pollen of ODP Site 1082 in the southeast Atlantic Ocean in order to obtain a high-resolution record of vegetation change in Namibia between 3.4 and 1.8 Ma. Four phases of vegetation development are inferred that are connected to global climate change. (1) Before 3 Ma, extensive, rather open grass-rich savannahs with mopane trees existed in Namibia, but the extension of desert and semidesert vegetation was still restricted. (2) Increase of winter rainfall dependent Renosterveld-like vegetation occurred between 3.1 and 2.2 Ma connected to strong advection of polar waters along the Namibian coast and a northward shift of the Polar Front Zone in the Southern Ocean. (3) Climatically induced fluctuations became stronger between 2.7 and 2.2 Ma and semiarid areas extended during glacial periods probably as the result of an increased pole-equator thermal gradient and consequently globally enhanced atmospheric circulation. (4) Aridification and climatic variability further increased after 2.2 Ma, when the Polar Front Zone migrated southward and the influence of Atlantic moisture brought by the westerlies to southern Africa declined. It is concluded that the positions of the frontal systems in the Southern Ocean which determine the locations of the high-pressure cells over the South Atlantic and the southern Indian Ocean have a strong influence on the climate of southern Africa in contrast to the climate of northwest and central Africa, which is dominated by the Saharan low-pressure cell.

The Bedford schools and charities of Sir William Harper : history of this celebrated endowment, the Act of Parliament and scheme of rules for its management, and a memoir of Sir William Harper /

Includes index.

The Puerto Rican study, 1953-1957; a report on the education and adjustment of Puerto Rican pupils in the public schools of the city of New York

Mode of access: Internet.

Schools and religion : proceedings before the United States Commission on Civil Rights : executive summary and transcripts of proceedings held in Washington, DC, New York City, and Seattle, WA, Spring/Summer 1998.

"December 1999."

On the importance of an early correct education of children : embracing the mutual obligations and duties of parent and child ; and also the qualifications and discipline of teachers, with their emolument ; and a plan suggested whereby all our common schools can advantageously be made free ; the whole interspersed with several amusing, chaste anecdotes growing out of the domestic and scolastic circle ; to which is subjoined by way of appendix, the Declaration of Independence ... ; the Constitution of the United States ; with that of the state of New York as lately adopted /

Bound in green cloth; stamped in gold and blind.

The origin and development of early Christian church architecture.

Bibliography: p. 143-147.

The American drawing-book: a manual for the amateur, and basis of study for the professional artist: especially adapted to the use of public and private schools, as well as home instruction.

Introduction and chapters 1-4 published in London under title: The elements of art.

School law of 1865. An act to establish and maintain a system of free schools, in the state of Illinois, as amended February 16, 1865.

Mode of access: Internet.

Inauguration of the schools of philosophy and the social sciences and dedication of McMahon Hall.

Mode of access: Internet.

Tables of compound interest and annuities; 48 rates, proceeding by intervals of one-sixteenth per cent. for from 1 to 120 years or periods and carried to nine decimal places ... With miscellaneous tables appended.

Mode of access: Internet.

School economy. A treatise on the preparation, organization, employments, government and authorities of schools /

Mode of access: Internet.