Footwear bio-modelling: An industrial approach

There is a growing need within the footwear sector to customise the design of the last from which a specific footwear style is to be produced. This customisation is necessary for user comfort and health reasons, as the user needs to wear a suitable shoe. For this purpose, a relationship must be established between the user foot and the last with which the style will be made; up until now, no model has existed that integrates both elements. On the one hand, traditional customised footwear manufacturing techniques are based on purely artisanal procedures which make the process arduous and complex; on the other hand, geometric models proposed by different authors present the impossibility of implementing them in an industrial environment with limited resources for the acquisition of morphometric and structural data for the foot, apart from the fact that they do not prove to be sufficiently accurate given the non-similarity of the foot and last. In this paper, two interrelated geometric models are defined, the first, a bio-deformable foot model and the second, a deformable last model. The experiments completed show the goodness of the model, with it obtaining satisfactory results in terms of comfort, efficiency and precision, which make it viable for use in the sector

A new methodological approach for shoe sole design and validation

Shoe soles are extremely complex to design and manufacture due to their organically shaped but technically precise nature and their manufacturing constraints. Consequently, there is a need for the increased design process flexibility offered by the use of specific CAD methodologies and techniques, to facilitate the work of expert designers and permit effective construction of the three-dimensional elements comprising the complete structure. Recent advances in additive manufacturing systems have extended the possibilities of shoe sole design. These systems can be used to create the final mould and to incorporate dynamic elements that are of particular value in sports footwear. In this article, we present a new methodology for the design and validation of shoe soles. The methodology assists designers in the design concept process and in transfer of the design to manufacturing. The model incorporates both a structural and a functional approach. To this end, a set of specific tools have been developed that can be used to quantify design quality. For example, the model calculates the coefficient of friction or slip resistance, necessary to comply with international standards concerning safety footwear.The financial support of this study comes from IVACE (Instituto Valenciano de Competitividad Empresarial) project: DIHUCA—complex tread designs for footwear soles (IMDEEA/2015/4)

A new surface joining technique for the design of shoe lasts

The footwear industry is a traditional craft sector, where technological advances are difficult to implement owing to the complexity of the processes being carried out, and the level of precision demanded by most of them. The shoe last joining operation is one clear example, where two halves from different lasts are put together, following a specifically traditional process, to create a new one. Existing surface joining techniques analysed in this paper are not well adapted to shoe last design and production processes, which makes their implementation in the industry difficult. This paper presents an alternative surface joining technique, inspired by the traditional work of lastmakers. This way, lastmakers will be able to easily adapt to the new tool and make the most out of their know-how. The technique is based on the use of curve networks that are created on the surfaces to be joined, instead of using discrete data. Finally, a series of joining tests are presented, in which real lasts were successfully joined using a commercial last design software. The method has shown to be valid, efficient, and feasible within the sector

Shoe last machining using virtual digitising

Shoe lasts are the moulds used in the footwear industries in order to mount the shoe. Most of the machines used in the sector to make lasts are simply mechanical copiers. CAD/CAM systems have just arrived to the shoe last market but its accuracy and efficiency is not better than traditional machines, for this reason new systems have difficulty to implant. Presented in the paper there is a tool path generation algorithm that takes the advantages of traditional copier systems that do not fulfil the CNC standards. The tool path is computed from a “virtually digitised” model of the last surface. The algorithm is then analysed in terms of computing cost and accuracy and refined by applying a series of optimisations. Some computer architectures are proposed in order to reduce the computation time. The proposed algorithm has been successfully implemented in a commercial CAD/CAM system specialised in shoe last making. Finally, some illustrative examples are shown

Augmented and Virtual Reality techniques for footwear

The use of 3D imaging techniques has been early adopted in the footwear industry. In particular, 3D imaging could be used to aid commerce and improve the quality and sales of shoes. Footwear customization is an added value aimed not only to improve product quality, but also consumer comfort. Moreover, customisation implies a new business model that avoids the competition of mass production coming from new manufacturers settled mainly in Asian countries. However, footwear customisation implies a significant effort at different levels. In manufacturing, rapid and virtual prototyping is required; indeed the prototype is intended to become the final product. The whole design procedure must be validated using exclusively virtual techniques to ensure the feasibility of this process, since physical prototypes should be avoided. With regard to commerce, it would be desirable for the consumer to choose any model of shoes from a large 3D database and be able to try them on looking at a magic mirror. This would probably reduce costs and increase sales, since shops would not require storing every shoe model and the process of trying several models on would be easier and faster for the consumer. In this paper, new advances in 3D techniques coming from experience in cinema, TV and games are successfully applied to footwear. Firstly, the characteristics of a high-quality stereoscopic vision system for footwear are presented. Secondly, a system for the interaction with virtual footwear models based on 3D gloves is detailed. Finally, an augmented reality system (magic mirror) is presented, which is implemented with low-cost computational elements that allow a hypothetical customer to check in real time the goodness of a given virtual footwear model from an aesthetical point of view

Automation of the shoe last grading process according to international sizing systems

The last is the basic industrial component in footwear manufacturing, from which product development starts. Correct last grading ensures the best fit for the intended group of users of the footwear model to be produced. The size marked on the last should respect the specific intervals defined in the different international sizing systems, like the European, UK, US or Mondopoint systems, which are all described in international standards. New approaches in the field of CAD/CAM have emerged over recent years towards the automation of this process. However, these are partial approaches that neither address the grading process according to the different standards nor consider the various parts of the shoe that are not affected by size increments. This paper presents a new accurate and efficient technique for the automation of the shoe last grading process based on the conjugate gradient method. Through this method, it is possible to obtain a graded shoe last that conforms to the international standards in force relative to shoe sizing and allows for the shoe parts that are not affected by size increments. This technique is based on the target measures of length and perimeter of the last to be graded and aims to minimise the quadratic difference between these values and those obtained from the graded last. This method has been evaluated through a battery of tests performed on a geometrically heterogeneous group of shoe lasts. The results obtained were accurate and the execution time was fast enough to be used for mass production

Online simulation as a collision prevention layer in automated shoe sole adhesive spraying

Robotisation in the footwear sector is a major challenge for the industry with difficulties present due to the inherent adaptive needs of some of the automated tasks performed by robotic arms. One of those of particular concern is collision prevention: working with those robots in automated online environments, considering they have limited awareness of the environment, may lead to dangerous situations with the movement of the robot along the calculated paths. To overcome this problem, a collision prevention layer based on a custom robotic software simulator is presented and justified in this paper to be used on automated shoe sole adhesive spraying cells. The performed experiments prove the feasibility of the proposed method in a real scenario with the speed and precision required by the automated task

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Definición y visualización de superficies recortadas

D.L.: BI 788-1997Las superficies recortadas presentan algunas dificultades de diseño y visualización. El primer problema es consecuencia de realizar la definición de las curvas de recorte en un espacio (el paramétrico) diferente del de diseño (R3). Para solucionarlo, proponemos un método de obtención de la curva de recorte a partir de curvas tridimensionales, presentando el caso general y un caso particular más simple. Por último se trata la visualización realista de la superficie. Planteamos, para ello, un algoritmo de poligonalización sobre el espacio paramétrico. Estas técnicas se han empleado para el diseño de pisos de calzado, proyecto conjunto de la Universidad de Alicante e INESCOP.Proyecto PYM (Diseño y Fabricación por Ordenador de Pisos y Moldes para Calzado), Universidad de Alicante - Instituto Español del Calzado y Conexa

Shoe last machining using virtual digitising

Shoe lasts are the moulds used in the footwear industries in order to mount the shoe. Most of the machines used in the sector to make lasts are simply mechanical copiers. CAD/CAM systems have just arrived to the shoe last market but its accuracy and efficiency is not better than traditional machines, for this reason new systems have difficulty to implant. Presented in the paper there is a tool path generation algorithm that takes the advantages of traditional copier systems that do not fulfil the CNC standards. The tool path is computed from a “virtually digitised” model of the last surface. The algorithm is then analysed in terms of computing cost and accuracy and refined by applying a series of optimisations. Some computer architectures are proposed in order to reduce the computation time. The proposed algorithm has been successfully implemented in a commercial CAD/CAM system specialised in shoe last making. Finally, some illustrative examples are shown