IEEE Robotics & Automation Magazine - December 2021 - 32

Toward Sustainable and
Accessible Mobility
A Functional Electrical
Stimulation-Based
Robotic Bike With a
Fatigue-Compensation
Algorithm and
Mechanism for
Cybathlon 2020
By Yeongjin Kim, Seung Ryeol Lee,
Sungjun Kim, Tuani de Sa Rosa, Yujin Gong,
Chaneun Park, Jae-Han Wang, Kiwon Park,
Jung-Yup Kim, and Dongjun Shin
©SHUTTERSTOCK.COM/ANSVETA
T
32 *
he functional electrical stimulation (FES) bike
race at Cybathlon is a competition in which a
pilot with a spinal cord injury (SCI) drives a
robotic bike with using his/her paralyzed
muscles. The intelligent technologies embedded
in the robotic bike stimulate the paralyzed leg muscles
and allow these muscles to actuate again. This advanced
equipment enriches people's lives by expanding their
mobility for rehabilitation and leisure. However, due to
the energy consumption of human muscles, muscle
fatigue should be properly managed to maintain high
speeds for long durations. In this article, we propose three
methods to manage muscle fatigue: 1) a stimulationcontrol
scheme based on fatigue prediction, 2) a human-
vehicle smart interface, and 3) a muscular hypertrophy
program. Without a fatigue-compensation algorithm, a
pilot traveled only roughly 200 m in 3 min due to muscle
fatigue; however, using the proposed methods, the pilot
was able to travel 1,200 m in 3 min 53 s, after training for
only three months.
Digital Object Identifier 10.1109/MRA.2021.3111835
Date of current version: 13 October 2021
IEEE ROBOTICS & AUTOMATION MAGAZINE
* DECEMBER 2021
Introduction
Cybathlon is an international competition in which people
with physical disabilities perform various tasks using state-ofthe-art
technical assistance. The competition is intended to
promote the development and widespread use of bionic technologies.
It was first organized in Switzerland in 2016, and
the second edition, Cybathlon 2020, was conducted online in
different countries due to the COVID-19 pandemic. Currently,
Cybathlon is expanding and receiving worldwide
attention from a wide variety of rehabilitation industries.
Participating teams from different parts of the world can
compete in six disciplines.
Among the different events, the FES bike race allows people
with an SCI to ride a bike by utilizing the FES bike system
[1]-[3]. The FES bike race is the only race in which people
with SCIs are able to use their muscles. Because individuals
with SCIs cannot contract the muscles of their lower extremities
on their own, these muscles weaken over time. The regular
use of muscles can reduce the risk of health-related
problems, such as cardiovascular and other diseases [4], [5].
Muscle contraction training using an FES device is recommended
as a continuous rehabilitation strategy for enhancing
leg muscle function [6].
1070-9932/21©2021IEEE
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IEEE Robotics & Automation Magazine - December 2021

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