Case study of a novel multi-actuated optimized reconfigurable freeform surface (MORFS) mold for custom foot orthoses

Mold design and construction is typically the most time-consuming and costly process in the fabrication of custom freeform product surfaces. Reconfigurable molds reduce this time and cost; however, some opportunities for improvement in reconfigurable systems are still possible in design by reducing system complexity and reconfigure time for a target application. A novel “multi-actuated optimized reconfigurable freeform surface (MORFS)” mold is proposed for the following key targets to (1) design the system for a targeted application, e.g., custom foot orthoses (CFOs), (2) reduce system complexity, (3) reduce system reconfigure time, and (4) ensure accuracy. The MORFS design process involves the following steps: (1) data processing, segmentation, normalization, and dimensionality reduction; (2) design of a novel mechanical subassembly; (3) development of a finite element (FE) flexible shell model of the manufacturing surface mold; (4) design optimization; and (5) development of a machine learning (ML)-based feedback control algorithm. The developed MORFS mold is 29% less complex, and 60% faster as compared with the benchmark study while maintaining the desired accuracy, i.e. mean error ≤ 1 mm . Furthermore, the accuracy of the optimized MORFS mold is also increased up to 39% as compared with the unoptimized configuration. The mechanical subassembly of the MORFS mold is improved by conducting design optimization, i.e., the number of actuators is reduced. Furthermore, the system reconfigure time is reduced significantly by using the FE model based ML control algorithm. The proposed design methodology ensured the desired accuracy of the surface construction for a target application. This case study is limited to the construction of freeform surfaces for CFOs; however, the proposed MORFS design methodology may be used to improve the time, complexity, and cost aspects of manufacturing in different areas including aerospace, automotive, biomechanics, and civil.