One way to provide powered lower limb prostheses with greater adaptability to a wearer's intent is to use a neural signal to provide feedforward control of prosthesis mechanics. We designed and tested the feasibility of an experimental powered ankle-foot prosthesis that uses pneumatic artificial muscles and proportional myoelectric control to vary ankle mechanics during walking. The force output of the artificial plantar flexor muscles was directly proportional to the subject's residual gastrocnemius muscle activity. The maximum force generated by a pair of artificial muscles fixed at nominal length was 3513 N. The maximum planter flexion torque that could be generated during walking was 176 Nm. The force bandwidth of the pneumatic artificial muscles was 2 Hz. The electromechanical delay was 33 ms, the time to peak tension was 48 ms, and the half relaxation time was 50 ms. We used two artificial muscles as dorsiflexors and two artificial muscles as plantar flexors. The prosthetic ankle had 25 deg of dorsiflexion and 35 deg of plantar flexion with the artificial muscles uninflated. The intent of the device was not to create a commercially viable prosthesis but to have a laboratory prototype to test principles of locomotor adaptation and biomechanics. We recruited one unilateral transtibial amputee to walk on a treadmill at 1.0 m/s while wearing the powered prosthesis. We recorded muscle activity within the subject's prescribed prosthetic socket using surface electrodes. The controller was active throughout the entire gait cycle and did not rely on detection of gait phases. The amputee subject quickly adapted to the powered prosthesis and walked with a functional gait. The subject generated peak ankle power at push off that was similar between amputated and prosthetic sides. Our results suggest that amputees can use their residual muscles for proportional myoelectric control to alter prosthetic mechanics during walking.

References

References
1.
Au
,
S.
,
Berniker
,
M.
, and
Herr
,
H.
,
2008
, “
Powered Ankle-Foot Prosthesis to Assist Level-Ground and Stair-Descent Gaits
,”
Neural Netw.
,
21
(
4
), pp.
654
666
.10.1016/j.neunet.2008.03.006
2.
Bellman
,
R. D.
,
Holgate
,
M. A.
, and
Sugar
,
T. G.
,
2008
, “
SPARKy 3: Design of an Active Robotic Ankle Prosthesis With Two Actuated Degrees of Freedom Using Regenerative Kinetics
,” 2nd IEEE/RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics (
BioRob 2008
), Scottsdale, AZ, October 19–22, pp.
511
516
.10.1109/BIOROB.2008.4762887
3.
Sup
,
F.
,
Varol
,
H. A.
, and
Goldfarb
,
M.
,
2011
, “
Upslope Walking With a Powered Knee and Ankle Prosthesis: Initial Results With an Amputee Subject
,”
IEEE Trans. Neural Syst. Rehabil. Eng.
,
19
(
1
), pp.
71
78
.10.1109/TNSRE.2010.2087360
4.
Huang
,
S.
, and
Ferris
,
D. P.
,
2012
, “
Muscle Activation Patterns During Walking From Transtibial Amputees Recorded Within the Residual Limb-Prosthetic Interface
,”
J. Neuroeng. Rehabil.
,
9
, p. 55.10.1186/1743-0003-9-55
5.
Seyedali
,
M.
,
Czerniecki
,
J. M.
,
Morgenroth
,
D. C.
, and
Hahn
,
M. E.
,
2012
, “
Co-Contraction Patterns of Trans-Tibial Amputee Ankle and Knee Musculature During Gait
,”
J. Neuroeng. Rehabil.
,
9
, p. 29.10.1186/1743-0003-9-29
6.
Silver-Thorn
,
B.
,
Current
,
T.
, and
Kuhse
,
B.
,
2012
, “
Preliminary Investigation of Residual Limb Plantarflexion and Dorsiflexion Muscle Activity During Treadmill Walking for Trans-Tibial Amputees
,”
Prosthet. Orthot. Int.
,
36
(
4
), pp.
435
442
.10.1177/0309364612443379
7.
Wentink
,
E. C.
,
Prinsen
,
E. C.
,
Rietman
,
J. S.
, and
Veltink
,
P. H.
,
2013
, “
Comparison of Muscle Activity Patterns of Transfemoral Amputees and Control Subjects During Walking
,”
J. Neuroeng. Rehabil.
,
10
, p. 87.10.1186/1743-0003-10-87
8.
Daerden
,
F.
, and
Lefeber
,
D.
,
2002
, “
Pneumatic Artificial Muscles: Actuators for Robotics and Automation
,”
Eur. J. Mech. Environ. Eng.
,
47
(
1
), pp.
11
21
.
9.
Davis
,
S.
,
Tsagarakis
,
N.
,
Canderle
,
J.
, and
Caldwell
,
D. G.
,
2003
, “
Enhanced Modelling and Performance in Braided Pneumatic Muscle Actuators
,”
Int. J. Rob. Res.
,
22
(
3–4
), pp.
213
227
.10.1177/0278364903022003006
10.
Klute
,
G. K.
,
Czerniecki
,
J. M.
, and
Hannaford
,
B.
,
2002
, “
Artificial Muscles: Actuators for Biorobotic Systems
,”
Int. J. Rob. Res.
,
21
(
4
), pp.
295
309
.10.1177/027836402320556331
11.
Collins
,
S. H.
,
Adamczyk
,
P. G.
,
Ferris
,
D. P.
, and
Kuo
,
A. D.
,
2009
, “
A Simple Method for Calibrating Force Plates and Force Treadmills Using an Instrumented Pole
,”
Gait Posture
,
29
(
1
), pp.
59
64
.10.1016/j.gaitpost.2008.06.010
12.
Hansen
,
A. H.
,
Childress
,
D. S.
,
Miff
,
S. C.
,
Gard
,
S. A.
, and
Mesplay
,
K. P.
,
2004
, “
The Human Ankle During Walking: Implications for Design of Biomimetic Ankle Prostheses
,”
J. Biomech.
,
37
(
10
), pp.
1467
1474
.10.1016/j.jbiomech.2004.01.017
13.
Baratta
,
R.
, and
Solomonow
,
M.
,
1990
, “
The Dynamic Response Model of Nine Different Skeletal Muscles
,”
IEEE Trans. Biomed. Eng.
,
37
(
3
), pp.
243
251
.10.1109/10.52326
14.
Costa
,
P. B.
,
Ryan
,
E. D.
,
Herda
,
T. J.
,
Walter
,
A. A.
,
Hoge
,
K. M.
, and
Cramer
,
J. T.
,
2012
, “
Acute Effects of Passive Stretching on the Electromechanical Delay and Evoked Twitch Properties: A Gender Comparison
,”
J. Appl. Biomech.
,
28
(
6
), pp.
645
654
.
15.
Hopkins
,
J. T.
,
Feland
,
J. B.
, and
Hunter
,
I.
,
2007
, “
A Comparison of Voluntary and Involuntary Measures of Electromechanical Delay
,”
Int. J. Neurosci.
,
117
(
5
), pp.
597
604
.10.1080/00207450600773764
16.
Sale
,
D.
,
Quinlan
,
J.
,
Marsh
,
E.
,
McComas
,
A. J.
, and
Belanger
,
A. Y.
,
1982
, “
Influence of Joint Position on Ankle Plantarflexion in Humans
,”
J. Appl. Physiol.
,
52
(
6
), pp.
1636
1642
.
17.
Vandervoort
,
A. A.
, and
McComas
,
A. J.
,
1986
, “
Contractile Changes in Opposing Muscles of the Human Ankle Joint With Aging
,”
J. Appl. Physiol.
,
61
(
1
), pp.
361
367
.
You do not currently have access to this content.