Design and analysis of a passive ankle foot orthosis by using transient structural method

Abstract

Foot drop is a condition where individuals are unable to lift the foot through the ankle. It results in slap foot after heel contact and toe drag during the swing phase. Ankle Foot Orthosis (AFO) is a mechanical device that supports both the ankle and foot of the individual and guides the movements of the foot to prevent slap foot and toe drag. There are two types of AFOs:Passive AFO and Active AFO. In this work, design and static analysis of a passive AFO to fit a human foot is presented. The static analysis was carried out for AFO made of two different materials (Polypropylene and High-Density Polyethylene (HDPE)) with two different thicknesses (3mm and 4mm). Based on the results obtained from the static analysis, the design of AFO was optimized for shape and thickness.Further dynamic analysis was carried out on the optimized AFO to know its behaviour in walking condition. The results obtained from the static and dynamic analyses showed that the polypropylene AFO was better compared to that of HDPE AFO by generating less stress, deformation, and factor of safety. The proposed AFO can be fabricated and tested for real-time walking conditions.