Contribuição na acurácia de observações em ensaios controlados de uma estação total robótica para fins de monitoramento de estrutura
Carregando...
Data
2016-09-05
Autores
Ferreira, Nemer Ricardo Amaral [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Seja por ação da natureza ou ação humana, estruturas artificiais (pontes, edifícios, barragens, etc.) ou naturais (placas litosféricas, superfícies com risco de desmoronamento, vulcões, etc.) sempre estarão sujeitas a mudanças em suas dimensões, tanto na forma, como no tamanho ou na posição, por isso estas estruturas merecem acompanhamento ao longo do tempo para que acidentes possam ser evitados. No monitoramento de estruturas, a utilização de instrumentos de medição dos mais variados tipos podem ser empregados: teodolito, nível, estação total e, mais recentemente, a tecnologia GNSS (Global Navigation Satellite System), o laser scanner e a ETR (estação total robótica). Para Kuang (1996) qualquer medida, mesmo aquelas com instrumentos de tecnologias mais recentes, há de se considerar erros inerentes ao processo de medição, os quais são causados por fatores instrumental, do meio ambiente ou de limitação humana. Estes erros, portanto, devem ser eliminados ou minimizados, para que se tenha maior confiabilidade nos dados coletados em campo e que servirão de análise para estudo das variações dimensionais de uma estrutura. Analisar a acurácia das observações com o equipamento que se está trabalhando, portanto, é fundamental no controle de estruturas. Esta pesquisa tem o objetivo de apresentar a acurácia de observações coletadas com uma estação total robótica modelo IS 203 da marca Topcon, com a finalidade de modelar possíveis erros que comprometam a investigação de variações na geometria de uma estrutura. Uma importante revisão das definições de acurácia e precisão é apresentada. As especificações informadas pelo fabricante do equipamento foram a base para o chamado processo de análise de acurácia das observações a priori. Nesta fase, equacionou-se todos os erros, de acordo com suas fontes. No caso da estação total, suas observáveis (direções e distâncias) têm suas fontes de erros. As direções sofrem influências dos erros de pontaria, de nivelamento e de leitura, ou seja, os chamados erros internos (relativo ao instrumento ou ao observador) e, também, dos erros externos (relativo aos fatores ambientais) que são o erro de centragem e da refração atmosférica. Os erros que afetam a medida linear também são divididos em componentes internos (o erro zero, o erro cíclico e o erro de medida da fase) e externos (refração atmosférica). Na sequência, aplicou-se a análise de acurácia das observações a posteriori para a determinação da variância em função do erro verdadeiro e modelada de todos os erros vistos anteriormente. Alguns experimentos foram realizados para analisar os resultados à luz dos procedimentos de modelagem executados. No experimento 1, realizado no laboratório de geodésia, a busca para identificar erro no comportamento espectral da ETR, relacionando este com a grandeza observada, não teve êxito, pois uma metodologia diferente deve ser empregada. Recomendam-se estudos mais aprofundados à respeito da instabilidade na taxa de coleta desse tipo de sensor, relacionando inclusive esses efeitos ao erro cíclico (σci) aqui abordado. No experimento 2, realizado num campo de calibração para estudos fotogramétricos, o deslocamento simulado foi detectado pelo sensor da ETR com diferença na ordem do décimo do milímetro em relação aos equipamentos que foram considerados como referência, e na ordem do milímetro para um deslocamento simulado na dezena do centímetro. O tratamento das observações mostrou ser eficaz quando comparado às observações com equipamentos considerados de referência. Recomendado analisar a capacidade de dilatação do material que compõe a estrutura ou objeto que é fonte de observação (monitoramento) e assim conhecer o impacto desse fenômeno na medida final. No experimento 3, com observações em alvos posicionados na parede de um prédio, as épocas de observação foram muito próximas, o que não possibilitou verificar algum tipo de deformação, sendo recomendado períodos mais espaçados, ou em diferentes condições, tais como época seca e úmida, ou fria e de calor. Importante enfatizar que a essência deste estudo vale para qualquer tipo de sensor em qualquer trabalho que se busque acurácia das observações. Assim, nesse trabalho entende-se ter elencado as influências dos erros, sistemáticos e aleatórios, nas observações coletadas com o sensor utilizado, visando a acurácia destas observações.
By action of nature or human action, artificial structures (bridges, buildings, dams, etc.) or natural (lithospheric plates, areas at risk of landslides, volcanoes, etc.) are always subject to change in its dimensions, both in form , as in size or position, so these structures has monitoring over time so that accidents can be prevented. Monitoring structures the use of measuring instruments of all kinds can be used: theodolite, level, total station and more recently, the GNSS technology (Global Navigation Satellite System), the laser scanner and the ETR (robotic total station). For Kuang (1996) any measure, even those with latest technology tools, you must consider errors inherent in the measurement process, which are caused by instrumental factors, environmental or human limitation. These errors therefore should be eliminated or minimized, in order to have more reliable data collected in the field and to serve as analysis to study the dimensional variations of a structure. To analyze the accuracy of the observations with the equipment you are working, so it is essential to control structures. This research aimed to present the accuracy of observations collected with a robotic total station IS 203 model Topcon brand, in order to model possible errors that compromise the investigation of variations in the geometry of a structure. A major review of the accuracy of definitions and accuracy was presented. The specifications informed by the equipment manufacturer were the basis for the so-called process analysis accuracy of a priori observations. At this stage, it equated to all errors, according to their sources. In the case of total station, its observable (directions and distances) have their sources of error. The directions are influenced by the aiming errors of flatness and reading, ie the so-called internal errors (relative to the instrument or to the observer), and also external errors (on environmental factors) that are the centering error and atmospheric refraction. Errors that affect the linear measurement are also divided into internal components (zero error, cyclic error and the measurement error of the stage) and external (atmospheric refraction). Following, we applied the accuracy of analysis of subsequent observations to determine the variance due to the real error and modeled all the errors seen before. Some experiments were performed to analyze the results in light of the performed modeling procedures. In experiment 1, conducted in the laboratory of geodesy, the search to identify error in the spectral behavior of the RTS, relating this to the observed magnitude, was not successful because a different methodology should be employed. Are recommended further studies regarding the instability in the collection rate of this type of sensor, including those relating to the effects of cyclic error (σci) addressed here. In experiment 2, performed a calibration field for photogrammetric studies, the simulated displacement was detected by RTS sensor with a difference of a tenth of a millimeter in relation to the equipment that was considered as a reference, and the order of a millimeter to a simulated shift in ten centimeter. The treatment of observations proved to be effective when compared to observations considered the reference equipment. Recommended analyze the expansion capacity of the material that comprises the structure or object that is the source of observation (monitoring) and thus know the impact of this phenomenon in the final measure. In experiment 3, with observations positioned targets on the wall of a building, the observation times were very close, which is not possible to verify some kind of deformation, being recommended more spaced periods, or under different conditions, such as dry season and wet or cold and heat. Important to emphasize that the essence of this study holds true for any type of sensor in any work that seeks accuracy of the observations. Thus, this work is meant to have part listed the influences of errors, systematic and random, the observations collected with the sensor used, aiming the accuracy of these observations.
By action of nature or human action, artificial structures (bridges, buildings, dams, etc.) or natural (lithospheric plates, areas at risk of landslides, volcanoes, etc.) are always subject to change in its dimensions, both in form , as in size or position, so these structures has monitoring over time so that accidents can be prevented. Monitoring structures the use of measuring instruments of all kinds can be used: theodolite, level, total station and more recently, the GNSS technology (Global Navigation Satellite System), the laser scanner and the ETR (robotic total station). For Kuang (1996) any measure, even those with latest technology tools, you must consider errors inherent in the measurement process, which are caused by instrumental factors, environmental or human limitation. These errors therefore should be eliminated or minimized, in order to have more reliable data collected in the field and to serve as analysis to study the dimensional variations of a structure. To analyze the accuracy of the observations with the equipment you are working, so it is essential to control structures. This research aimed to present the accuracy of observations collected with a robotic total station IS 203 model Topcon brand, in order to model possible errors that compromise the investigation of variations in the geometry of a structure. A major review of the accuracy of definitions and accuracy was presented. The specifications informed by the equipment manufacturer were the basis for the so-called process analysis accuracy of a priori observations. At this stage, it equated to all errors, according to their sources. In the case of total station, its observable (directions and distances) have their sources of error. The directions are influenced by the aiming errors of flatness and reading, ie the so-called internal errors (relative to the instrument or to the observer), and also external errors (on environmental factors) that are the centering error and atmospheric refraction. Errors that affect the linear measurement are also divided into internal components (zero error, cyclic error and the measurement error of the stage) and external (atmospheric refraction). Following, we applied the accuracy of analysis of subsequent observations to determine the variance due to the real error and modeled all the errors seen before. Some experiments were performed to analyze the results in light of the performed modeling procedures. In experiment 1, conducted in the laboratory of geodesy, the search to identify error in the spectral behavior of the RTS, relating this to the observed magnitude, was not successful because a different methodology should be employed. Are recommended further studies regarding the instability in the collection rate of this type of sensor, including those relating to the effects of cyclic error (σci) addressed here. In experiment 2, performed a calibration field for photogrammetric studies, the simulated displacement was detected by RTS sensor with a difference of a tenth of a millimeter in relation to the equipment that was considered as a reference, and the order of a millimeter to a simulated shift in ten centimeter. The treatment of observations proved to be effective when compared to observations considered the reference equipment. Recommended analyze the expansion capacity of the material that comprises the structure or object that is the source of observation (monitoring) and thus know the impact of this phenomenon in the final measure. In experiment 3, with observations positioned targets on the wall of a building, the observation times were very close, which is not possible to verify some kind of deformation, being recommended more spaced periods, or under different conditions, such as dry season and wet or cold and heat. Important to emphasize that the essence of this study holds true for any type of sensor in any work that seeks accuracy of the observations. Thus, this work is meant to have part listed the influences of errors, systematic and random, the observations collected with the sensor used, aiming the accuracy of these observations.
Descrição
Palavras-chave
Acurácia, Erros, ETR, Monitoramento de estruturas, Accuracy, Errors, RTS, Monitoring structures