Development of a mass customization system for shoe last design

Abstract

Mass customization relates to the ability to provide customized products or services through flexible processes in high volumes and at reasonably low costs. The footwear industry is a very competitive industry with many companies and educated consumers. As consumers are becoming more demanding and companies are moving toward mass customization, the needs to develop fashionable and fitting footwear is increasing. In order to develop footwear that can match with the foot shape, 3D foot shape information is acquired using foot scanners. There are many commercial foot scanners using different techniques, but most of them are within HK$180,000-360,000 price range. Generally, 3D foot laser scanners are available mainly in research institutes and very large companies. Most conventional retail shops cannot afford to have an expensive foot scanner as the cost is still exorbitant and financially viable. In order to make mass customization possible and available widely to retail shops, cheaper foot scanner has to be developed. Once we have obtained the foot shape, the next important aspect is to design customized shoe last. For the shoe last design system, previous researches are not very useful in designing customized shoe last, matching of foot to shoe last and automatic changing of the shoe last style by changing parameter values. Therefore, it is imperative to improve the system for designing innovative shoe last, for realizing footwear mass customization. Thus, it is the aim of this research to invent a low cost foot scanner and develop a system for mass customized shoe last design. A low cost scanner was invented to scan the feet of consumers and store the data in the form of digitized feet. The method was to create 3D shape using cheap widely available web cameras. A system of similarities and differences was used to generate the 3D foot shape. The aim was to know the similarities between foot and then use the simple web cameras to capture the differences, in order to accurately create 3D foot shape. From the 3D shape, anthropometric measures and landmarks can be extracted when needed to create shoe last and for selection of shoes, preferable via the web. The technique of using low-cost web camera without the need for expensive linear gears was proposed, the expected production cost of the scanner is within HK$6,000-10,000. The accuracy of the scanner was evaluated in an experiment. Two hundred Hong Kong Chinese (100 males and 100 females) participated in the experiment. After the foot shapes were generated, the error between the predicted foot shape and the actual foot shape was computed. Error between 3D predicted foot shape from 3D foot laser scanner and 'real foot' is calculated. For males, the mean error is 0.83 mm (SD=0.86 mm). For females, the mean error is 0.78 mm (SD=0.80 mm). Error between 3D predicted foot shape from low cost foot scanner and 'real foot' is also calculated. For males, the mean error is 1.75 mm (SD=1.33 mm). For females, the mean error is 1.62 mm (SD=1.28 mm). This level of accuracy is enough for mass customized footwear design given that current foot size increment is 6.66 mm. The exploration of a computer-aided design system enables shoe last design changes, exploration and eventually enables mass customization. In this thesis, fit customization is based on previous research. The focus of the shoe-last customization has been on styling and design. Methods have been developed to realize continuous changes of styling to reflect personal taste without the need for physical design. The shoe-last design has been represented by styling curves using parametric curves. Modification of the styling curves, by changing the parameters' values, was used to explore different design. This was useful to create slight variations of shoe last. Since the designs were parameterized; shoe lasts with different shapes and sizes can be created by individuals according to their desired taste. All along, the exploitation of low cost foot scanner, and the development of the shoe last design system are contribution to the long-term development of footwear manufacturing. This systematic research reduces production cost and enables better design, at the same time, advances mass customized shoe last design for mass customized footwear manufacturing.