Orientador: Nelson Luis Cappelli / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-06T21:31:33Z (GMT). No. of bitstreams: 1 Lima_ThalesCoelhoBorges_D.pdf: 3224309 bytes, checksum: 0b88922a88b1f511034fc43574f8d0e3 (MD5) Previous issue date: 2006 / Resumo: Este trabalho apresenta o desenvolvimento de um equipamento microprocessado, de custo reduzido, para geração de sinal de correção diferencial para GPS, em tempo real e configuração e supervisão do receptor GPS base. Foi estruturado em duas etapas. Na primeira, desenvolveu-se um protótipo com o intuito de comprovar a viabilidade técnica e econômica e na segunda, o desenvolvimento do equipamento de correção diferencial capaz de atuar de forma autônoma. O aplicativo computacional desenvolvido é responsável pela geração do sinal de correção diferencial no formato do protocolo RTCM SC-104, configuração e inicialização do receptor GPS e operações de geo-referenciamento. O equipamento de correção diferencial possui um microcontrolador dedicado, display alfanumérico, teclado multifunção para configuração e operação do sistema e interfaces de comunicação. A placa processadora possui duas interfaces seriais padrão RS-232C. Uma delas tem a função de configuração e leitura das informações geradas pelo receptor GPS base. A outra atua somente como saída, enviando o sinal de correção diferencial. Desenvolveu-se um sistema de modulação/demodulação e conversão de taxa, de custo reduzido, para ajustar o sinal ao meio de comunicação. Este sistema é constituído por dois módulos independentes, onde um deles está conectado ao equipamento de correção diferencial na transmissão e o outro no módulo receptor para o envio ao receptor GPS móvel. Fez-se uso de rádios de comunicação VHF/UHF para o envio do sinal de correção. Foram realizados diversos testes ao longo do desenvolvimento de todas as etapas deste trabalho. Inicialmente, avaliou-se o aplicativo computacional responsável pela geração do sinal de correção diferencial no formato RTCM-SC 104. Nos testes subseqüentes avaliaram-se o sistema de comunicação proposto, as rotinas desenvolvidas para a configuração do receptor GPS e o equipamento de correção diferencial final. O projeto do equipamento microprocessado mostrou que é possível a construção de uma estação privada para a geração do sinal de correção diferencial, de custo reduzido, possibilitando o aumento do número de usuários no segmento agrícola, por meio da redução do custo dos sistemas de posicionamento / Abstract: This work presents the development of low cost microprocessor-based equipment that generates differential correction signal to GPS, in real time, and the configuration and supervision of GPS base receptor. It was structured in two phases. In the first one, a prototype was developed aiming to prove its economical and technical viability and in the second one, the development of the equipment of differential correction able to act in an autonomous way. The computer application developed is responsible to generate the differential correction signal in the RTCM SC-104 protocol format, the configuration and initialization of the GPS receptor and the geo-reference operations. The equipment developed has a dedicated microcontroller, alphanumeric display, multifunctional keyboard for the configuration and operation of the system and the communication interfaces. The motherboard has two serial interfaces RS-232C standard. The first interface function is to configure and to read the information generated by the GPS base receptor. The second performs only as ¿gate¿, to send the differential correction signal. A low cost system of modulation/demodulation and ¿tax¿ conversion was developed, to adjust the signal and communication channel. This system has two independent modules, one module is connected to the differential correction equipment in the transmission and the second is connected to the receptor to send the signal to the mobile GPS. Radio communication UHF/VHF was used to send the correction signal. Several tests were performed during the all the phases of the development. First, the computer application responsible to generate the differential correction signal RTCM-SC 104 standard was evaluated. Second, the proposed communication system and the configuration routines for the GPS receptor and the final differential correction equipment were tested. The micro processed equipment project proved that is possible to build a private low cost station to generate the differential correction signal, allowing the increase the number of agriculturist business users, by reducing the cost of the positioning systems / Doutorado / Maquinas Agricolas / Doutor em Engenharia Agrícola

Spacecraft missions such as spacecraft docking and formation flying require high precision relative position and attitude data. Although Global Positioining Systems can provide this capability near the earth, deep space missions require the use of alternative technologies. One such technology is the vision-based navigation (VISNAV) sensor system developed at Texas A&M University. VISNAV comprises an electro-optical sensor combined with light sources or beacons. This patented sensor has an analog detector in the focal plane with a rise time of a few microseconds. Accuracies better than one part in 2000 of the field of view have been obtained. This research presents a new approach involving simultaneous activation of beacons with frequency division multiplexing as part of the VISNAV sensor system. In addition, it discusses the synchronous demodulation process using digital heterodyning and decimating filter banks on a low-power fixed point DSP, which improves the accuracy of the sensor measurements and the reliability of the system. This research also presents an optimal and computationally efficient six-degree-of-freedom estimation algorithm using a new measurement model based on the attitude representation of Modified Rodrigues Parameters.

Spacecraft missions such as spacecraft docking and formation flying require high precision relative position and attitude data. Although Global Positioining Systems can provide this capability near the earth, deep space missions require the use of alternative technologies. One such technology is the vision-based navigation (VISNAV) sensor system developed at Texas A&M University. VISNAV comprises an electro-optical sensor combined with light sources or beacons. This patented sensor has an analog detector in the focal plane with a rise time of a few microseconds. Accuracies better than one part in 2000 of the field of view have been obtained. This research presents a new approach involving simultaneous activation of beacons with frequency division multiplexing as part of the VISNAV sensor system. In addition, it discusses the synchronous demodulation process using digital heterodyning and decimating filter banks on a low-power fixed point DSP, which improves the accuracy of the sensor measurements and the reliability of the system. This research also presents an optimal and computationally efficient six-degree-of-freedom estimation algorithm using a new measurement model based on the attitude representation of Modified Rodrigues Parameters.