Nikola Vukasinovic

Identification and optimization of key process parameters in noncontact laser scanning for reverse engineering

This Extended Technical Note shows that the final accuracy level of reverse engineered surfaces depends on scanning distance and scanning angle of the laser beam, hence it also depends on the morphology of the scanned objects. On scanning strongly curved objects, such as the ones with free form surfaces, the distance and impact angle of the laser beam are changing continuously during the scanning process. On the basis of these, two critical parameters are specified for the design model, which make it possible to predict these two factors in advance, depending on the morphology of the scanned object. First, a mathematical-statistical design model of the scanning process is generated, which relies on ANOVA (analysis of variance) and DOE (design of experiments). In the next step, a fitness function is optimized by the genetic algorithm (GA) program. This optimization improves the accuracy of the final scanned surfaces, in terms of the minimum standard deviation values of reverse engineered 3D surface model. The proposed approach was confirmed in a case study, which is presented at the end of this Technical Note.

Case Study – surface reconstruction from point clouds for prosthesis production

Currently, the production of a high-quality and highly aesthetic prosthesis is still mainly based on handwork and subjective comparison to get the proper shape and colour of the prosthesis, likely not by a first attempt. This article describes a case study whose goal was to investigate the possibilities of computer-aided surface reconstruction and supplementation to improve the quality and reduce the manufacturing time for an orthopaedic prosthesis. For this purpose, a model of human finger made of plaster had been scanned with the high fidelity laser triangulation scanner. The result was a set of very dense point clouds, representing the surface of the finger model in all its complexity. The main target of this work was to create a water-tight, high resolution computer model of a human finger, which would be ready for further manipulation, such as scaling, mirroring or stretching in arbitrary dimensions. A larger amount of such models could represent a virtual database of human shapes, which would be suitable for prosthesis production and many other (medical) purposes. The first steps after scanning were done in an attempt to reorient several scans, taken from different viewpoints, relative to each other in order to get the proper shape of a finger. This was done by applying an ICP algorithm, integrated in commercial software, and its comparison to the results of reorientation, based on information about fingers position transformation during the scanning process. This information proved to be vital for a fast and accurate alignment of the scans and successful surface generation. This paper also discusses the possibilities of avoiding the influences of geometric errors, generated by a triangulation scanner on surface alignment and the creation of a 3D model. The surface was created by applying Delaunay triangulation to the point cloud. Afterwards, it was followed by manual and automatic refining and reconstruction of a triangular mesh. The final result is a 3D computer model of a human finger with all its details, such as fingerprints and wrinkles. Additional measurements showed that the arithmetical average of deviation between a computer and a physical model was less than 0.3 mm, which is a good result for the desired purposes. The study also showed the possibilities for acceleration of scan alignment while the accuracy could be increased.

Use of MFF and Concurrent Engineering to Develop a Sustainable Product—Radical Redesign of Flushing System

The paper shows the approach to radical product redesign of sanitary flushing equipment which is conservative market niche product. The approach demonstrates use of the matrix of functions and functionalities (MFF) and elements of concurrent engineering to achieve a significant reduction of necessary resources during whole product’s lifecycle: production, use as well as its disposal. This approach led to a considerable reduction of number of different parts and materials, as well as total number of parts and overall mass of the product. The result was a product proposal, which fulfills the same functional requirements as exiting products using different principal solutions. This change of exploited working principles opened new possibilities for a significant reduction of necessary amount of flushing water, thanks to the energy stored in the new flushing device. The proposed solution was experimentally confirmed also with working prototype.

Comparison of Indian and Central European Shape Contour Meaning Comprehension

Since every culture has their own specifics, there is often the question, whether customers from diverse cultures perceive shape characteristics equally or differently? This study explore how two different cultural groups (Indian vs. Central European) of participants experience or response to predefined four types of product dimensions—aesthetic, functional, social and future. We assume that the Central-European and Indian students differ by their perception of different shapes. To gather the necessary statistical data, we prepared questionnaires wherein the samples were assessed using the semantic differential technique and a five-level Likert scale. The responses were then analyzed using Factor analysis. After conducting statistical analysis using Factor analysis, two main affective dimensions were gained, which show how differentiate Central-European and Indian participants. The methodology presented in this study can help designers to identify a pattern of consumer shape categorization.

Design2go. How, Yes, No?

This paper investigates and discusses the opportunities and possibilities of mobile and ubiquitous technologies in the NPD process. During the 2012 EGPR—internationally based NPD process in virtual environment, we made an analysis on technologies and services that were used for the purposes of the course. Our particular interest was, what platforms the students used for different tasks of the NPD process, and are there any mobile alternatives. Since mobile technologies rely more and more on cloud services this opens many other issues as well: intellectual properties rights, protection of personal information, availability of services and information for different participants, standardization of the protocols which should be well considered before any engineering process such as NPD. Our first observations showed that on one side student participants use more and more of different mobile and cloud technologies available, but on the other side there are situations where they still feel much more comfortable when using “old-fashion” technologies, especially when communicating. One interesting fact is also constantly growing wish of students to use the IT web services which they are familiar with despite all necessary IT infrastructure for their work is provided by the course organizers. This is especially important message for the organizers of such courses, to learn how to balance between accepting the opportunities of new internet tools and threats of privacy and control over the intellectual property.