Basilio Ramos Barbero

Comparative study of different digitization techniques and their accuracy

The various manufacturers of digitization systems speak of the effectiveness and accuracy of their tools under optimal conditions, but actual experimentation with simple or complex objects and different materials yields results that on occasions refute the effectiveness of those systems. In order to help choose a digitization system on the basis of its accuracy and the quality of the distribution of points and triangular meshes, in the field of reverse engineering, we compared five digitization techniques (three versions of the laser scanner, a fringe projection version and an X-ray version): (1) an ordered point cloud obtained with a laser incorporated in a CMM, (2) a disordered point cloud obtained with a manual laser the position of which is determined with a Krypton Camera, (3) an Exascan manual laser with targets, (4) an ordered point cloud obtained by high precision Computerized Tomography (CT) and (5) an Atos fringe projection scanner with targets. Each of the three calibrated pieces (a sphere, a cylinder and a gauge block) was measured five times by the five digitization systems to confirm the accuracy of the measurement. A comparison was also made of the meshes generated by the five software packages (Focus-Inspection, Metris, VxScan, Mimics and Atos) of the five digitization systems for the three calibrated pieces and two more complex pieces (a bone and an automobile window winder pulley) to determine meshing quality. Finally, all the pieces were meshed by triangulation in the Catia V5 DSE (Digitized Shape Editor) module in order to test the quality of the points distribution.

The recovery of design intent in reverse engineering problems

This article presents a method of reverse engineering applied to the particular case of a cam in order to recover the form and dimensions of the design of the original piece, which take into account: design intent, general knowledge of the problem, different geometric and dimensional restrictions, and the digitized point cloud. Rather than by employing complex mathematical algorithms, a fit is achieved by drawing a parametric outline that complies with the design intent, and by adjusting the different parameters through successive approximations using commercial CAD software commands.

A tolerance analysis and optimization methodology. The combined use of 3D CAT, a dimensional hierarchization matrix and an optimization algorithm

We propose a methodology in this study for the analysis and the optimization of assembly tolerances. A combination of three components, it involves the use of 3D CAT software, a table referred to as a “dimensional hierarchization matrix” and a tolerance optimization algorithm. The Antolin Group, a Spanish multinational in the automobile components sector, employs this system to optimize tolerance values and to reduce manufacturing costs. The matrix was designed to enable easy identification, in a single table, of all requirements that fail to meet the specifications in the different approximations, prior to the definition of the dimensional and the geometric tolerances that comply with the functional requirements, and to identify which tolerances contribute most to variations in all of the functional conditions of the mechanism. Through its different iterations, this matrix allows us to see which of the tolerances should first be modified to optimize the design requirement specifications. A tolerance optimization algorithm was also defined, which functions with the data from the dimensional hierarchization matrix.

Strategic learning of simulation and functional analysis in the design and assembly of mechanisms with CAD on a professional Master's degree course

Currently, programs that teach 3D CAD as part of an industrial engineering qualification in Spanish universities are structured around four pillars: solid design, surface design, model assemblage, and the drafting of plans. In this article, we add two new pillars: 3D CAD simulation and kinematic analysis of both mechanisms and assemblages, as part of the professional masters degree course entitled “Masters Degree in automotive components.” We should stress the novel content selected for this advanced CAD subject matter, in accordance with the needs of a group of firms and our prior experience of component design. Moreover, we recount our experiences, over two academic years, of student learning processes when using the EHEA‐based learning method that we refer to as “strategic knowledge.” The various innovative improvements throughout this experimental teaching approach were subjected to qualitative analysis.

Interactive learning management system to develop spatial visualization abilities

An Interactive Learning Management System (ILMS) is presented, which functions as a web-based Spatial Visualization Ability (SVA) learning support tool for students of engineering graphics and as a management tool for teachers to track student learning. This software is designed to fill the gaps in student knowledge, giving them more uniform spatial visualization abilities when enrolling on University Engineering degrees. The ILMS_SVA consists of: (1) a Content Management System (CMS); (2) a preliminary level assessment test; (3) a web-based tool for exercise management and self-assessment incorporating a 3D viewer that functions as an interactive tutorial (IT), allowing the manipulation of 3D objects in every exercise; (4) a database. It is designed for three types of users (student, teacher, and administrator), and has been validated with engineering graphics students at the University of Burgos (Spain) by means of experimental trials in the classroom and a user satisfaction survey, over two academic years. The results indicate that use of this tool improved SVA among students generally and was even of greater effectiveness for those students that accessed engineering courses with no prior knowledge of Technical Drawing.

The importance of adaptive expertise in CAD learning: maintaining design intent

ABSTRACT In CAD modelling, there is no one general standardised teaching-learning methodology. We use the strategic-learning methodology, maintaining design intent, fully aware that it is necessary to modify CAD models for their reuse. Questions concerning the thought processes of students when modelling with CAD and the strategies that they choose that best maintain design intent arise in the course of using the 3D modelling programmes. Our aim here is to determine the importance of adaptive expertise in the results of CAD models and, particularly, in one of its constructs: design intent. To do so, CAD-based experimentation took place over two years with 78 third-year students in the first year and with 53 third-year students in the second year from the subject module of Graphic Engineering, on the Degree in Mechanical Engineering of the University of Burgos (Spain). At the start of the year, the students conducted a survey to measure adaptive expertise. Subsequently, in the first year of experimentation, the students prepared various CAD models and the design intent was evaluated in one of them (a connecting rod or conrod), broken down into the skeleton, the structure, the modifications and the constraints. In the conrod exercise, the students also completed a questionnaire both before and after designing their models, which were analysed to detect the thought processes and the strategies that they had applied. In the second year of experimentation, design intent was incorporated in various exercises at the beginning of the year, in addition to the conrod. The main conclusion is that the correct division of the part into its pieces and adaptive expertise improved the results in relation to design intent in the CAD.In CAD modelling, there is no one general standardised teaching-learning methodology. We use the strategic-learning methodology, maintaining design intent, fully aware that it is necessary to modify CAD models for their reuse. Questions concerning the thought processes of students when modelling with CAD and the strategies that they choose that best maintain design intent arise in the course of using the 3D modelling programmes. Our aim here is to determine the importance of adaptive expertise in the results of CAD models and, particularly, in one of its constructs: design intent. To do so, CAD-based experimentation took place over two years with 78 third-year students in the first year and with 53 third-year students in the second year from the subject module of Graphic Engineering, on the Degree in Mechanical Engineering of the University of Burgos (Spain). At the start of the year, the students conducted a survey to measure adaptive expertise. Subsequently, in the first year of experimentation, the students prepared various CAD models and the design intent was evaluated in one of them (a connecting rod or conrod), broken down into the skeleton, the structure, the modifications and the constraints. In the conrod exercise, the students also completed a questionnaire both before and after designing their models, which were analysed to detect the thought processes and the strategies that they had applied. In the second year of experimentation, design intent was incorporated in various exercises at the beginning of the year, in addition to the conrod. The main conclusion is that the correct division of the part into its pieces and adaptive expertise improved the results in relation to design intent in the CAD.