Active exoskeletons have capacity to provide biologically equivalent levels of joint mechanical power, but high mass of actuation units may lead to uncoordinated walking and extra metabolic consumption. Active exoskeletons normally supply assistance directly during push-off and have a power burst during push-off. Thus, the requirements on power of motors are high, which is the main reason for the high mass. However, in a muscle-tendon system, the strategy of injecting energy slowly and releasing quickly is utilized to obtain a higher peak power than that of muscle alone. Application of this strategy of peak power amplification in exoskeleton actuation might lead to reductions of input power and device mass. This paper presents an ankle exoskeleton which can accumulate the energy injected by a motor during the swing phase and mostly the stance phase and then release it quickly during push-off. An energy storage and release system was developed using a four-bar linkage clutch. In addition, evaluation experiments on the exoskeleton were carried out. Results show that the exoskeleton could provide a high power assistance with a low power motor and reduced the requirement on motor power by 4.73 times. Besides, when walking with the exoskeleton, the ankle peak power was reduced by 25.8% compared to the normal condition. The strategy which imitates the working pattern of the muscle-tendon system leads to a lightweight and effective exoskeleton actuation, and it also supplies ideas for the designs of lightweight actuators that work discontinuously in other conditions.

References

References
1.
Winter
,
D. A.
,
2009
,
Biomechanics and Motor Control of Human Movement
,
4th ed.
,
Wiley
,
Hoboken, NJ
.
2.
Kuo
,
A. D.
,
Donelan
,
J. M.
, and
Ruina
,
A.
,
2005
, “
Energetic Consequences of Walking Like an Inverted Pendulum: Step-to-Step Transitions
,”
Exerc. Sport Sci. Rev.
,
33
(
2
), pp.
88
97
.
3.
Sawicki
,
G. S.
, and
Ferris
,
D. P.
,
2008
, “
Mechanics and Energetics of Level Walking With Powered Ankle Exoskeletons
,”
J. Exp. Biol.
,
211
(
9
), pp.
1402
1413
.
4.
Dollar
,
A. M.
, and
Herr
,
H.
,
2008
, “
Lower Extremity Exoskeletons and Active Orthoses: Challenges and State-of-the-Art
,”
IEEE Trans. Rob.
,
24
(
1
), pp.
144
158
.
5.
Herr
,
H.
,
2009
, “
Exoskeletons and Orthoses: Classification, Design Challenges and Future Directions
,”
J. Neuroeng. Rehabil.
,
6
(
21
), pp.
21
.
6.
Browning
,
R. C.
,
Modica
,
J. R.
,
Kram
,
R.
, and
Goswami
,
A.
,
2007
, “
The Effects of Adding Mass to the Legs on the Energetics and Biomechanics of Walking
,”
Med. Sci. Sports Exerc.
,
39
(
3
), pp.
515
525
.
7.
Meuleman
,
J. H.
,
van Asseldonk
,
E. H. F.
, and
van der Kooij
,
H.
,
2013
, “
The Effect of Directional Inertias Added to Pelvis and Ankle on Gait
,”
J. Neuroeng. Rehabil.
,
10
(
1
), pp.
40
.
8.
Aliman
,
N.
,
Ramli
,
R.
, and
Haris
,
S. M.
,
2017
, “
Design and Development of Lower Limb Exoskeletons: A Survey
,”
Robot. Auton. Syst.
,
95
(
8
), pp.
102
116
.
9.
Moreno
,
J. C.
,
Pons
,
J. L.
, and
Figueiredo
,
J.
,
2018
, “ Chapter 7 - Exoskeletons for Lower-Limb Rehabilitation,”
Rehabilitation Robotics
,
1st ed
,
Academic Press
,
New York
, pp.
89
99
.
10.
Yeung
,
L.-F.
, and
Tong
,
R. K.-Y.
,
2018
, “ Chapter 5—Lower Limb Exoskeleton Robot to Facilitate the Gait of Stroke Patients,”
Wearable Technology in Medicine and Health Care
,
R. K.-Y.
Tong
, ed.,
Academic Press
,
New York
, pp.
91
111
.
11.
Ferris
,
D. P.
,
Sawicki
,
G. S.
, and
Daley
,
M. A.
,
2007
, “
A Physiologist’s Perspective on Robotic Exoskeletons for Human Locomotion
,”
Int. J. HR
,
4
(
3
), pp.
507
528
.
12.
Levine
,
D.
,
Richards
,
J.
, and
Whittle
,
M. W.
,
2012
,
Whittle’s Gait Analysis
,
Elsevier Ltd
,
Oxford
.
13.
Wu
,
Y.
,
Chen
,
K.
, and
Fu
,
C.
,
2016
, “
Effects of Load Connection Form on Efficiency and Kinetics of Biped Walking
,”
ASME J. Mech. Rob.
,
8
(
6
), p.
061015
.
14.
Roberts
,
T. J.
, and
Azizi
,
E.
,
2011
, “
Flexible Mechanisms: The Diverse Roles of Biological Springs in Vertebrate Movement
,”
J. Exp. Biol.
,
214
(
3
), pp.
353
361
.
15.
Haldane
,
D. W.
,
Plecnik
,
M. M.
,
Yim
,
J. K.
, and
Fearing
,
R. S.
,
2016
, “
Robotic Vertical Jumping Agility Via Series-Elastic Power Modulation
,”
Sci. Rob.
,
1
(
1
), p.
eaag2048
.
16.
Zaitsev
,
V.
,
Gvirsman
,
O.
,
Ben Hanan
,
U.
,
Weiss
,
A.
,
Ayali
,
A.
, and
Kosa
,
G.
,
2015
, “
A Locust-Inspired Miniature Jumping Robot
,”
Bioinspir. Biomim.
,
10
(
6
), p.
066012
.
17.
Kovac
,
M.
,
Fuchs
,
M.
,
Guignard
,
A.
,
Zufferey
,
J. C.
,
Floreano
,
D.
, and
11222
,
2008
, “
A Miniature 7g Jumping Robot
,”
2008 IEEE International Conference on Robotics and Automation
,
Pasadena
,
May 19–23
, pp.
373
378
.
18.
Cherelle
,
P.
,
Grosu
,
V.
,
Matthys
,
A.
,
Vanderborght
,
B.
, and
Lefeber
,
D.
,
2014
, “
Design and Validation of the Ankle Mimicking Prosthetic (AMP-) Foot 2.0
,”
IEEE Trans. Neural Syst. Rehabil. Eng.
,
22
(
1
), pp.
138
148
.
19.
Fu
,
C.
,
Wang
,
J.
,
Chen
,
K.
,
Yu
,
Z.
, and
Qiang
,
H.
,
2016
, “
A Walking Control Strategy Combining Global Sensory Reflex and Leg Synchronization
,”
Robotica
,
34
(
5
), pp.
973
994
.
20.
Hitt
,
J.
,
Oymagil
,
A. M.
,
Sugar
,
T.
,
Hollander
,
K.
,
Boehler
,
A.
, and
Fleeger
,
J.
,
2007
, “
Dynamically Controlled Ankle-Foot Orthosis (DCO) With Regenerative Kinetics: Incrementally Attaining User Portability
,”
Proceedings of the 2007 IEEE International Conference on Robotics and Automation
,
Rome
,
May 21
, pp.
1541
1546
.
21.
Meijneke
,
C.
,
van Dijk
,
W.
, and
van der Kooij
,
H.
,
2014
, “
Achilles: An Autonomous Lightweight Ankle Exoskeleton to Provide Push-Off Power
,”
2014 5th IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob)
,
Sao Paulo
,
Aug. 12–15
, pp.
918
923
.
22.
Wiggin
,
M. B.
,
Sawicki
,
G. S.
, and
Collins
,
S. H.
,
2011
, “
An Exoskeleton Using Controlled Energy Storage and Release to Aid Ankle Propulsion
,”
2011 IEEE International Conference on Rehabilitation Robotics (ICORR)
,
Zurich
,
June 29–July 1
, pp.
160
164
.
23.
Elliott
,
G.
,
Marecki
,
A.
, and
Herr
,
H.
,
2014
, “
Design of a Clutch-Spring Knee Exoskeleton for Running
,”
ASME J. Med. Devices
,
8
(
3
), p.
031002
.
24.
Cherelle
,
P.
,
Matthys
,
A.
,
Grosu
,
V.
,
Vanderborght
,
B.
, and
Lefeber
,
D.
,
2012
, “
The AMP-Foot 2.0: Mimicking Intact Ankle Behavior With a Powered Transtibial Prosthesis
,”
2012 4th IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob)
,
Rome
,
June 24–27
, pp.
544
549
.
25.
Diller
,
S.
,
Majidi
,
C.
, and
Collins
,
S. H.
,
2016
, “
A Lightweight, Low-Power Electroadhesive Clutch and Spring for Exoskeleton Actuation
,”
IEEE International Conference on Robotics and Automation
,
Stockholm
,
May 16–21
, pp.
682
689
.
26.
Collins
,
S. H.
,
Wiggin
,
M. B.
, and
Sawicki
,
G. S.
,
2015
, “
Reducing the Energy Cost of Human Walking Using an Unpowered Exoskeleton
,”
Nature
,
522
(
7555
), pp.
212
215
.
27.
Collins
,
S. H.
, and
Kuo
,
A. D.
,
2010
, “
Recycling Energy to Restore Impaired Ankle Function During Human Walking
,”
PLoS One
,
5
(
2
), p.
e9307
.
28.
Mooney
,
L. M.
,
Rouse
,
E. J.
, and
Herr
,
H. M.
,
2014
, “
Autonomous Exoskeleton Reduces Metabolic Cost of Human Walking
,”
J. Neuroeng. Rehabil.
,
11
(
1
), pp.
151
.
29.
Farris
,
D. J.
, and
Sawicki
,
G. S.
,
2013
, “
Linking the Mechanics and Energetics of Hopping With Elastic Ankle Exoskeletons (Vol 113, Pg 1862, 2012)
,”
J. Appl. Physiol.
,
115
(
2
), p.
293
.
30.
Galle
,
S.
,
Malcolm
,
P.
,
Derave
,
W.
, and
De Clercq
,
D.
,
2013
, “
Adaptation to Walking With an Exoskeleton That Assists Ankle Extension
,”
Gait Posture
,
38
(
3
), pp.
495
499
.
31.
Zhang
,
L.
, and
Fu
,
C.
,
2018
, “
Predicting Foot Placement for Balance Through a Simple Model With Swing Leg Dynamics
,”
J. Biomech.
,
77
(
21
), pp.
155
162
.
32.
Wu
,
Y.
,
Chen
,
K.
, and
Fu
,
C.
,
2016
, “
Natural Gesture Modeling and Recognition Approach Based on Joint Movements and Arm Orientations
,”
IEEE Sens. J.
,
16
(
21
), pp.
7753
7761
.
This content is only available via PDF.
You do not currently have access to this content.