Realization and Evaluation of a Prosthetic Foot Multibody Model in Quasi-Static and Dynamic Conditions =

Nowadays, innovations in lower limb prosthetic head towards active prostheses development or cheaper prostheses affordable by a wider group of people. Evaluation and optimization of prostheses’ passive com-ponents, like the foot component of a lower limb prosthesis, could be useful to improve prosthesized sub-jects’ comfort and prostheses’ physiological response, as well as simplify the role of the active components. This study proposes to utilize multibody analysis to reproduce the elastic behaviour of a commercial pros-thetic foot in order to run a dynamic simulation of gait’s stance phase. The multibody model realization is carried on with different CAD software and completed in MATLAB, while the static and dynamic analysis of the prosthetic foot are performed with Simulink alongside MATLAB itself. Most of the Simulink’s block utilized to build the multibody model are taken from Simscape Multibody library. All the simulations will be conducted on a Vari-Flex foot (Össur). Although the optimization of a generic flexible body is usually performed with a Finite Element Method (FEM) software, the use of a multibody software could cut down the computational time effort required to perform a dynamical analysis: the dynamic simulation of gait’s stance phase performed in this study lasts about 30 seconds, while a complete FEM dynamic analysis could take more than 1 hour. On the other hand, the simple multibody model proposed in this Thesis could not describe properly the static and quasi-static behaviour of the prosthetic foot. Another key feature of the model is that joint’s viscoelastic values are easily computed using an analytical formula deducted from a simple quasi-static model: a wedged beam loaded at the free end. Below, the steps followed to reach the goal are listed: •??Define stiffness’ starting value; •??Segmentation of the prosthetic foot real model in order to realize a multibody model; •??Reproduce quasi-static loading simulation on Vari-Flex foot; •??Tune joints’ stiffness using the results obtained by quasi-static mechanical simulations in previous works; •??Simulate gait effects on the multibody model in order to evaluate the errors committed calculating foot deflection over gait. This Thesis is part of a project by Fondazione IIT (Istituto Italiano di Tecnologia) – Department of Rehab Technologies funded by INAIL (Istituto Nazionale Assicurazione Infortuni sul Lavoro). The project’s pur-pose is developing limb prosthetic solutions for the Italian Sistema Sanitario Nazionale.