The apparent mass and transmissibility of a bicycle-rider system

Master thesis (2019)

Authors

J.W. de Haan Mechanical Engineering

Contributors

A.L. Schwab Biomechatronics & Human-Machine Control - Mechanical, Maritime and Materials Engineering (supervisor 1)
R. Happee Intelligent Vehicles - Mechanical, Maritime and Materials Engineering (supervisor 2)
A.C. Schouten Biomechatronics & Human-Machine Control - Mechanical, Maritime and Materials Engineering (supervisor 2)
G. Dialynas Biomechatronics & Human-Machine Control - Mechanical, Maritime and Materials Engineering (supervisor 1)
Faculty
Mechanical Engineering
Copyright: © 2019 Jelle Waling de Haan
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Published Date

20-06-2019

Language

English

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Faculty

Mechanical Engineering

Abstract

The objective of this research is to identify the passive response of the rider’s body to translational and rotational random perturbations. A custom made bicycle mock-up equipped with a system of sensors has been developed, capable of measuring the linear accelerations, angular velocity and the rider’s force responses in all translational axes of all bicycle interfaces. The bicycle mock-up is driven by a hexapod that generates coloured noise perturbations in the range 0–10 Hz. Twenty four healthy male adults participated in this study and gave informed consent according to the guidelines of the ethical committee of Delft University of Technology. The responses of all subjects are represented in the frequency domain by means of frequency response functions. More specific, the interaction of the rider’s body at the seat, foot pegs and handlebars are expressed in terms of apparent mass and as seat-to-sternum transmissibility functions (STS). The apparent mass and STS transfer functions for the surge and heave motion suggest a simple underlying passive response system. For surge, a clear resonance peak was found at 2 Hz for nearly all interfaces and directions, whereas, for the heave motion a clear resonance peak at 5 Hz was found for the seat and handlebars and a resonance peak at 6 Hz for the foot pegs. The apparent mass of the pitch and yaw motion also suggest, to a certain extend, simple passive dynamics after 1 Hz characterised by resonance peaks at 1.8 and 2.3 Hz, respectively. Only the corresponding yaw STS transfer function showed a resonance peak around 2.3 Hz, as well. The sway and roll motion do not suggest simple passive dynamics showing similar trends in apparent mass characterised by an ever-decreasing gain and no resonance peaks. Finally, the surge, heave, pitch and yaw apparent mass transfer functions suggest that higher body mass in general yields higher peak magnitude and lower resonance frequency. This effect was most apparent for the surge motion.