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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Adapta??o eletr?nica de um leitor mec?nico de coto, investiga??o e desenvolvimento de interface CAD

Lacerda, Ivan Max Freire de 20 February 2009 (has links)
Made available in DSpace on 2014-12-17T14:57:49Z (GMT). No. of bitstreams: 1 IvanMFL.pdf: 663615 bytes, checksum: a9a612a8d366a8eadb51a7b7c58984a5 (MD5) Previous issue date: 2009-02-20 / Due to advances in the manufacturing process of orthopedic prostheses, the need for better quality shape reading techniques (i.e. with less uncertainty) of the residual limb of amputees became a challenge. To overcome these problems means to be able in obtaining accurate geometry information of the limb and, consequently, better manufacturing processes of both transfemural and transtibial prosthetic sockets. The key point for this task is to customize these readings trying to be as faithful as possible to the real profile of each patient. Within this context, firstly two prototype versions (α and β) of a 3D mechanical scanner for reading residual limbs shape based on reverse engineering techniques were designed. Prototype β is an improved version of prototype α, despite remaining working in analogical mode. Both prototypes are capable of producing a CAD representation of the limb via appropriated graphical sheets and were conceived to work purely by mechanical means. The first results were encouraging as they were able to achieve a great decrease concerning the degree of uncertainty of measurements when compared to traditional methods that are very inaccurate and outdated. For instance, it's not unusual to see these archaic methods in action by making use of ordinary home kind measure-tapes for exploring the limb's shape. Although prototype β improved the readings, it still required someone to input the plotted points (i.e. those marked in disk shape graphical sheets) to an academic CAD software called OrtoCAD. This task is performed by manual typing which is time consuming and carries very limited reliability. Furthermore, the number of coordinates obtained from the purely mechanical system is limited to sub-divisions of the graphical sheet (it records a point every 10 degrees with a resolution of one millimeter). These drawbacks were overcome by designing the second release of prototype β in which it was developed an electronic variation of the reading table components now capable of performing an automatic reading (i.e. no human intervention in digital mode). An interface software (i.e. drive) was built to facilitate data transfer. Much better results were obtained meaning less degree of uncertainty (it records a point every 2 degrees with a resolution of 1/10 mm). Additionally, it was proposed an algorithm to convert the CAD geometry, used by OrtoCAD, to an appropriate format and enabling the use of rapid prototyping equipment aiming future automation of the manufacturing process of prosthetic sockets. / Devido aos avan?os no processo de fabrica??o de pr?teses ortop?dicas, a necessidade de uma melhor qualidade t?cnica na leitura da forma (i.e., com menos incertezas) da parte residual dos amputados tornou-se um desafio. Para superar esses problemas ? necess?rio ser capaz de obter informa??es precisas da geometria do membro e, consequentemente, melhorar os processos de fabrica??o de pr?teses e cartuchos transfemurais e transtibiais. O ponto-chave para esta tarefa ? personalizar essas leituras tentando ser o mais fiel poss?vel ao verdadeiro perfil de cada paciente. Dentro deste contexto, duas vers?es (α e β) de um prot?tipo de um scanner 3D mec?nico para ler forma residual de membros com base em t?cnicas de engenharia reversa foram concebidas. Prot?tipo β ? uma vers?o melhorada do prot?tipo α, apesar de ainda trabalhar em modo anal?gico. Ambos os prot?tipos s?o capazes de produzir uma representa??o CAD do membro atrav?s de apropriada planilha gr?fica e foram concebidos para funcionar exclusivamente atrav?s de meios mec?nicos. Os primeiros resultados foram encorajadores, uma vez que foram capazes de conseguir uma grande redu??o em rela??o ao grau de incerteza das medi??es quando comparadas com as dos m?todos tradicionais, que s?o muito imprecisas e desatualizadas. Por exemplo, n?o ? incomum ver estes m?todos arcaicos sendo usados utilizando fitas m?tricas caseiras para medir a forma da perna do paciente. Embora o prot?tipo β tenha melhorado as leituras, ainda ? necess?rio algu?m para introduzir os pontos plotados (i.e., aqueles marcados na planilha em formato de disco gr?fico) para um software acad?mico CAD chamado OrtoCAD. Esta tarefa ? realizada por digita??o manual, que ? morosa e tem confiabilidade limitada. Al?m disso, o n?mero de coordenadas obtidas a partir do sistema puramente mec?nico ? limitado ?s subdivis?es do disco gr?fico (ele grava um ponto a cada 10 graus com uma resolu??o de um mil?metro). Estes inconvenientes foram resolvidos na concep??o da segunda vers?o do prot?tipo β, na qual foi desenvolvida uma adapta??o eletr?nica, tornando-o capaz de realizar uma leitura autom?tica (i.e., sem interven??o humana no modo digital). Um software de interface (i.e., driver), foi desenvolvido para facilitar a transfer?ncia de dados. Resultados muito melhores foram obtidos significando menor grau de incerteza (ele registra um ponto a cada 2 graus com uma resolu??o de 1/10 mm). Al?m disso, foi proposto um algoritmo para converter a geometria CAD, utilizada pelo OrtoCAD, para um formato adequado e que permita a utiliza??o de equipamento de prototipagem r?pida destinado a uma futura automa??o do processo de fabrica??o dos cartuchos de pr?teses.

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