RES E A R C H Open Access
Myoelectrically controlled wrist robot for stroke
rehabilitation
Rong Song
1
, Kai-yu Tong
2*
, Xiaoling Hu
2
and Wei Zhou
1
Abstract
Background: Robot-assisted rehabilitation is an advanced new technology in stroke rehabilitation to provide
intensive training. Post-stroke motor recovery depends on active rehabilitation by voluntary participation of
patient’s paretic motor system as early as possible in order to promote reorganization of brain. However, voluntary
residual motor efforts to the affected limb have not been involved enough in most robot-assisted rehabilitation for
patients after stroke. The objective of this study is to evaluate the feasibility of robot-assisted rehabilitation using
myoelectric control on upper limb motor recovery.
Methods: In the present study, an exoskeleton-type rehabilitation robotic system was designed to provide
voluntarily controlled assisted torque to the affected wrist. Voluntary intention was involved by using the residual
surface electromyography (EMG) from flexor carpi radialis(FCR) and extensor carpi radialis (ECR)on the affected limb
to control the mechanical assistance provided by the robotic system during wrist flexion and extension in a 20-
session training. The system also applied constan t resistant torque to the affected wrist during the training. Sixteen
subjects after stroke had been recruited for evaluating the tracking performance and therapeutical effects of
myoelectrically controlled robotic system.
Results: With the myoelectrically-controlled assistive torque, stroke survivors could reach a larger range of motion
with a significant decrease in the EMG signal from the agonist muscles. The stroke survivors could be trained in the
unreached range with their voluntary residual EMG on the paretic side. After 20-session rehabilitation training, there
was a non-significant increase in the range of motion and a significant decrease in the root mean square error
(RMSE) between the actual wrist angle and target angle. Significant improvements also could be found in muscle
strength and clinical scales.
Conclusions: These results indicate that robot-aided therapy with voluntary participation of patient’s paretic motor
system using myoelectric control might have positive effect on upper limb motor recovery.
Background
Stroke is the first leading cause of motor disabilities in
many countries, which will significantly affect the daily
activities of stroke survivors. Rehabilitation training pro-
vides an opportunity to improve motor function. Conven-
tionally, it can be conducted by therapists in a one-on-one
manual mode in hospital. In the last two decades, many
advanced rehabilitation technologies are extensively devel-
oped, which provide repetitive, well-controlled assistance
for the patients and relieve therapist from labour-intensive
work [1-4].
Mechanical design is important to decide the joint
kinematics of the extremity in the robot-aided rehabilita-
tion training. There are two types of rehabilitation robot
from the mechanical design point of view: end-effector
based robots, and exoskeleton-type robots. MIT-MANUS
was an example to the end-effector based robots, which
interacted with subjects at the end of robot arm [4]. The
design of end-effector could adapt to subjects with differ-
ent body size. While exoskeleton-type robots can resemble
human anatomy and apply torque to specific joints, more-
over, the working-space of the rehabilitation training pro-
vided by such kinds of exoskeletions could approximate
the working-space performed by human subjects [2,3].
Control strategy is another important factor to affect the
training effect of robot-aided rehabilitation. MIT-MANUS
* Correspondence: k.y.tong@polyu.edu.hk
2
Interdisciplinary Division of Biomedical Engineering, The Hong Kong
Polytechnic University, Hung Hom Kowloon, Hong Kong
Full list of author information is available at the end of the article
JNER
JOURNAL OF NEUROENGINEERING
AND REHABILITATION
© 2013 Song et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Song et al. Journal of NeuroEngineering and Rehabilitation 2013, 10:52
http://www.jneuroengrehab.com/content/10/1/52