Because of its flexibility, SoftFoot Pro perfectly reproduces the natural positions assumed by human feet and allows for performing everyday actions such as bending down to tie a shoe or picking something up from the ground, and improving the user’s ability to ascend and descend stairs. Image courtesy of IIT-Istituto Italiano di Tecnologia.
The new SoftFoot Pro is a motorless, flexible, waterproof prosthetic foot that is inspired by the anatomy of the human extremity. Designed by the Istituto Italiano di Tecnologia (IIT, Italian Institute of Technology), Genoa, its design is unique on an international level and aims to serve both as a flexible technological prosthesis for people with limb loss and as a solution for humanoid robots of the future.
Weighing about 450 grams, it can support loads of up to 100kg. It consists of a mobile arch mechanism in titanium (or aeronautical-grade aluminum alloy), whose ends are connected by 5 high-strength plastic chains arranged in parallel to simulate the plantar fascia of human feet. These chains are traversed lengthwise by a high-performance, mechanically inextensible cable of 210mm, connected at the heel. Each chain is characterized by multiple modules made of high-strength plastic that are linked by pairs of elastics. The arch system and the elastic chains constitute the artificial equivalent of the architecture composed by the tarsus, metatarsus, and phalanges of the human foot.
This architecture allows the replication of the windlass mechanism, which progressively stiffens the plantar fascia to evenly distribute the force applied on the ground during walking, which contributes to more efficient negotiation with obstacles, better forward propulsion, and improved energy efficiency. The adaptable and elastic feature of the sole helps with absorbing approximately 10–50% of the impact on the ground.
Moreover, the foot sole deforms and adapts to uneven terrain and obstacles, thus minimizing them, improving the naturalness of the step, and enhancing the stability of the user. SoftFoot Pro is designed to be used on uneven terrain, including slippery grounds, where it is typically more challenging for prosthetic users, and for robots, to maintain balance. Being waterproof makes it adequate to be used outdoors, on grass, beaches, and slippery terrain, avoiding the need for the user to switch to activity-specific prostheses.
