Electromechanical device for measuring passive stiffness and viscosity of human finger

Details

Supervisors

Herman, Benoît ; Dehez, Bruno

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électromécanicien, à finalité spécialisée: mécatronique

Abstract

This master's thesis intends to design a device capable of measuring finger joint's passive stiffness and viscosity or also called passive musculo-articular stiffness (PMAS). This electromechanical device aims to generate passive oscillations to a finger's joint and measure its passive resistance at different frequencies. This device based on a method developed by Lehmann and Detrembleur allows to distinguish the passive stiffness and the viscosity from the global impedance, enabling an objective and quantified measurement of PMAS. This quantification method may provide a better understanding of neurological disorders such as spasticity and therefore provide better treatments. This project was launched by the Louvain Bionics in 2019 and has already been the subject of a Master thesis in 2020. Previous works in UCLouvain have already been conducted to assess PMAS. Two machines were designed, one to assess the ankle joint and the other to assess the wrist joint. Some aspects of this thesis's prototype are largely inspired from the wrist device. The thesis follows a typical design methodology. In the first step, the context is presented. This includes anatomical and biomechanical considerations of the finger, a description of spasticity and of the quantification method of PMAS, and lastly a review of similar PMAS measuring devices. In the second step, as a result of the functional requirements built in collaboration with clinicians, conceptual designs and comparative studies are produced to generate a fitted solution to the problem. The third step characterizes the prototyping step. It involves an optimized sizing of the actuation, sensory system and mechanical transmission, a complete electrical schematic and CAD on Solidworks, and finally, future assessments of the prototype. Construction of the prototype has been initiated, but first assessments of the measurement’s precision are yet to be established.