Despite the intense research in the last decade with the aim of developing a reliable solution for fall detection in the elderly and other risk populations, it can be asserted that the diffusion of fall detectors in the geriatric practice is near null. This scenario is similar to the very scarce use of telemedicine in healthcare. The present work begins analyzing why fall detectors have not achieved to permeate the industry. That road is used to know the drawbacks of current devices and systems, besides to allow studying several important concepts underlying the principles of fall detection. A novel smart detection system based on that survey is finally briefly presented. The design of this device is founded on the experience and results obtained by an earlier device that was designed in the framework of the thesis of one of the authors.

Computer-Aided Design and Applications is an international journal on the applications of CAD and CAM. It publishes papers in the general domain of CAD plus in emerging fields like bio-CAD, nano-CAD, soft-CAD, garment-CAD, PLM, PDM, CAD data mining, CAD and the internet, CAD education, genetic algorithms and CAD engines. The journal is aimed at all developers and users of CAD technology to ptovide CAD solutions for various stages of design and manufacturing. The journal publishes all about Computer-Aided Design and Computer-Aided technologies.

This article introduces an innovative application of Visual Basic for Applications (VBA) (Visual Basic macro language) developed in CATIA (Computer-Aided Three-Dimensional Interactive Application), computer-aided manufacturing and engineering design software. Said application enables the three-dimensional (3D) representation and development to be obtained on a plane of the surfaces of cylindrical and conical elbows utilised to join two conduits, since CATIA lacks tools for the design of elements of metal fabrication. The application permits the geometric and dimensional parameters necessary for the creation and development of the analysed elbows to be introduced via a keyboard. Once these values have been entered and it has been verified that the design of the elbow is possible, then the application is programmed within the CATIA “Wireframe and Surface Design” module to obtain the 3D representation of said elbows, and the development of their surface is projected in the CATIA “Drafting” module. Consequently, the incorporation of this tool into CATIA software could increase technical-design productivity by eliminating certain intermediate operations, such as symmetry, and through improving the geometry training of less skilled users.

The emergence of computer-aided design (CAD) has propelled the evolution of the sheet metal engineering field. Sheet metal design software tools include parameters associated to the part’s forming process during the pattern drawing calculation. Current methods avoid the calculation of a first pattern drawing of the flattened part’s neutral surface, independent of the forming process, leading to several methodological limitations. The study evaluates the reliability of the Computer Extended Descriptive Geometry (CeDG) approach to surpass those limitations. Three study cases that cover a significative range of sheet metal systems are defined and the associated solid models and patterns’ drawings are computed through Geogebra-based CeDG and two selected CAD tools (Solid Edge 2020, LogiTRACE v14), with the aim of comparing their reliability and accuracy. Our results pointed to several methodological lacks in LogiTRACE and Solid Edge that prevented to solve properly several study cases. In opposition, the novel CeDG approach for the computer parametric modeling of 3D geometric systems overcame those limitations so that all models could be built and flattened with accuracy and without methodological limitations. As additional conclusion, the success of CeDG suggests the necessity to recover the relevance of descriptive geometry as a key core in graphic engineering.

This article shows an approach to the three-dimensional modelling of a sugarcane mill and its associated steam engine, designed by the Robey and Co. engineering company in 1869. In order to obtain the 3D CAD model of said invention, CATIA V5 R20 software has been employed. Various sources of starting material, from the basis of this research and found in the process of searching for relevant information, provide information on the main elements, operating conditions, and mechanism of the machine. Thanks to the three-dimensional geometric modelling carried out, it has been possible to explain, in detail, both its operation and the final assembly of the invention through the assemblies of its different subsets, thereby obtaining a virtual recreation that shows its operation. Likewise, a study has been carried out, from a mechanical engineering viewpoint, of the gear train that transmitted the movement, in order to ascertain the compression force exerted on the sugar cane. This research, related to industrial archaeology, therefore, enables the reader to understand a machine that constituted a milestone in the sugarcane industry, while paying tribute to the English engineer, Robert Robey.

This article presents an application for educational purposes in the field of engineering graphics, which corrects the dihedral projections of the sections of a plane for a part by comparing the solution provided by the student with that obtained through 3D CAD modelling software. Said application is generated as a macro in CATIA (Computer-Aided Three-Dimensional Interactive Application), which is included as a tool in the ‘Part Design’ module. The code of this macro is written in the CATVBA language, utilizes the CATIA internal editor, and takes advantage of the capabilities offered by Visual Basic for Applications (VBA) in the design of Graphical User Interfaces (GUI). The operation of the macro consists of obtaining the section in the 3D CAD model, projecting it onto three dihedral projections of the part (elevation, plan, and profile), and calculating the visible and hidden lines by means of a numerical process based on dividing the lines into discrete sections. Likewise, to obtain numerical results, the section obtained in CATIA (reference section) is compared with the section provided by the student (section that needed to be corrected) by means of a spreadsheet (Microsoft Excel). The data of the coordinates of the points of the reference section are exported to said spreadsheet as is the data of the coordinates of the section that needed to be corrected, which is contained in a file with a dxf format (Drawing eXchange Format). From these data, by programming the appropriate formulae in the cells of the spreadsheet, the numerical values of the errors are obtained, thereby locating said errors in the dihedral projections of the section which needed to be corrected. Likewise, the application can be programmed to compare the central symmetry of both of the sections.