Vrije Universiteit Brussel

Design of a below-knee prosthesis powered by Pleated Pneumatic Artificial Muscles

Introduction

Due to an accident or vascular disease the lower limb is often as such damaged that the victim or patient must undergo an amputation. The amputation which is meant in this context is a below-knee (or transtibial) amputation, thus the patient preserves a stump.

The amputated lower limb is then replaced by a transtibial prosthesis. Nowadays, such prostheses are passive systems. This means that during forward locomotion, the spring stifness remains the same in any circumstance. The prosthesis cannot adapt to changing ground surface properties nor to a changing intention of the patient. Due to these restrictions, transtibial amputees can't retrieve their originial natural gait pattern. The continuous abnormal gait eventually creates medical pathologies.

Goal of the project

The main goal of this project is to improve the gait pattern of transtibial amputees and try to let their pattern evolve in a more efficient manner by developing an intelligent prosthesis. This prosthesis will be actuated by pleated pneumatic artificial muscles. By controlling the air pressure in these muscles, a system with variable compliance can be realised. The key advantage of such a system is that the natural step frequency is adjustable related to the movement circumstances. Also shock absorption and intrinsic safety must be mentioned as important advantages.

Planned Project tasks

(Literature) study of existing passive transtibial prostheses and study of human gait kinematic and dynamic aspects.
Realization of pc-program in matlab for optimal prosthesis setup
Selection of suitable muscle and muscle configuration
CAD-design of prosthesis
Manufacturing of the required prosthesis components
Setup of pneumatic/electric circuit
Integration of prosthesis in labo
First global practice test
Evaluation of prototype
Modification period
Second evaluation
Start of test period with transtibial amputees

Financial support

This research is financed by the Fonds voor Wetenschappelijk Onderzoek-Vlaanderen, project G.0496.06.

Project group

The research cell behind this FWO-project consists of an interuniversitary and multidisciplinary project group. Three departments are involved: two departments of mechanical engineering (Vrije Universiteit Brussel and Katholieke Universiteit Leuven) and the department of Human Biometry and Biomechanics (Vrije Universiteit Brussel).