Complex Shape Measurement Using 3D Scanner

Abstract

Sistem Pemeriksaan Automatik biasanya bermula dengan teknik Reka bentuk Berbantukan Komputer (CAD) dan berakhir dengan janaan arahan mesin untuk menukarkan bahan mentah kepada produk akhir, memperolehi data tiga dimensi untuk membina model permukaan berparameter bagi tujuan analisis ralat, duplikasi atau memperbaiki objek tersebut. Ia melibatkan pendigitalan permukaan objek yang perlu diperiksa, janaan model CAD dan analisis keputusan pemeriksaan. Pendigitalan boleh dilakukan dengan teknik kuar sentuh atau pengesan tanpa sentuh. Biasanya, tanpa bantuan daripada pengeluar, adalah sukar untuk memantau dan mengenal pasti perubahan produk selepas digunakan. Tambahan pula, reka bentuk cetakan asal tidak didedahkan. Objektif utama kertas ini ialah mencadangkan suatu algoritma yang mampu mengekstrak maklumat daripada objek berbentuk kompleks yang telah didigitalkan (dengan menggunakan pengimbas laser), misalnya cangkukan lutut, untuk menjanakan reka bentuk cetakannya. Diharapkan penyelidik lain, terutamanya dalam bidang perubatan dan bio-kejuruteraan mendapat manfaat daripada algoritma ini untuk meramal dan menganggar perubahan bekas cangkukan perubatan dan seterusnya mengubah reka bentuknya untuk memenuhi kehendak pesakit. Kata kunci: Pemeriksaan automatik, reka bentuk cetakan, cangkukan lutut, pengimbas 3D, gantian lutut total Automated inspection systems usually start from computer-aided design (CAD) techniques, and end with either generation of machining instructions required to convert a raw material into a finished product, or to obtain three-dimensional data for constructing a parametric surface model of the product for the purpose of error analysis, or to duplicate or enhance the object. It involves surface digitization of an existing part that needs inspection, CAD model creation and analyzing the inspection results. Most of the time, without the help from the manufacturer, it is very difficult to do inspection and to detect any changes of the product after being used. In addition, the original blueprints of most manufacturing products are not being revealed to the public. The main objective of this paper is to propose an algorithm that is able to extract information from digitized complex shape objects (using laser scanner), such as the medical knee implant (knee prosthesis), to generate their blueprint. It is hoped that other researchers, especially in the medical and bioengineering field, can benefit from this proposed algorithm to predict or approximate the changes of the medical ex-plant and modify its design to suit the patient needs. Key words: Automated inspection, blueprint, prosthesis, 3D scanner, total knee replacement

Measurement of Wear in Orthopedic Prosthesis

“…Besides wear measurements, CMM method provides volumetric and linear creep measurements [22,25,26]. Estok II et al [25] measured the creep deformation of UHMWPE and cross-linked polyethylene by CMM method.…”

“…Rahmat et al [22] used CMM laser scanner for digitizing complex shaped knee prosthesis. They proposed an algorithm to gain information from digitized data.…”

“…They can measure the dimensions with tactile probe or scanning probe [21,22]. This technique is one of the geometry based method that can be used both for evaluating wear volume and wear distribution over the worn surface [10,11].…”