A simplified human body model for assisting electric bicycle design

Abstract

Compared to non-electric bicycles, power-assistance ones could be designed for more postural comfort with less consideration of power production when pedalling. The present work aimed to develop a simplified human body model to assist in the design of power-assisted bicycles to better accommodate a target user population. To characterize body posture in bicycle use, the inter-segmental angles corresponding to a reference posture were measured from a sample of 63 males and females testing 4 existing bicycle models for comfort and long distance use. As a first approximation, only upper body was modelled as a 2D linkage composed of trunk (hip to shoulder) and arm (shoulder to grip) segments. To better account for postural effect, functional segment lengths were measured in the reference posture, and used to build the regression equations with body height. For a given bicycle characterized by saddle and handlebar position, the hip and shoulder angles could be fully determined for a rider using the proposed model. To validate the model, we compared the measured and predicted inter-segmental angles and showed that the proposed human model could account for the effects of both body height and bicycle’s geometry. To show the usefulness of the proposed model, a comfortable range of hip and shoulder angles was defined from the experimental data and was used to predict the fit area of handlebar and saddle position for both short and tall persons. Simulation results show that a more reclined seat tube could better accommodate both short and tall users.

Keywords: Kinematic model, bicycle design, anthropometry, postural comfort

DOI: 10.54941/ahfe1003354