Modal Characterization of Manual Wheelchairs

Abstract

Manual wheelchair (MWC) users are exposed to whole-body vibrations (WBVs) during propulsion. Vibrations enter the MWC structure through the wheels’ hub, propagate according to the MWC dynamical response, and finally reach the user’s body by the footrest, seat, backrest, and handrims. Such exposure is likely to be detrimental to the user’s health and a source of discomfort and fatigue which could, in daily life, impact users’ social participation and performance in sports. To reduce WBV exposure, a solution relies on MWC dynamical response modelling and simulation, where the model could indeed be used to identify parameters that improve the MWC dynamic. As a result, it is necessary to first assess the MWC dynamical response. In this approach, experimental modal analyses were conducted on eleven MWCs, including daily and sport MWCs (tennis, basketball, and racing). Through this procedure, modal properties (i.e., modal frequencies, damping parameters, and modal shapes) were identified for each MWC part. The results pointed out that each MWC investigated, even within the same group, revealed specific vibration properties, underlining the difficulty of developing a single vibration-reducing system for all MWCs. Nevertheless, several common dynamical properties related to MWC comfort and design were identified.