A novel Treadmill Body Weight Support System

A novel Treadmill Body Weight Support System using Pneumatic
Muscle Actuators
Tran Van Thuc, Flavio Prattico, M. Azuwan Mat Dzahir, S.Yamamoto

Abstract— This paper proposes a new Body Weight Support
(BWS) system using Pneumatic Artificial Muscle (PAM)
actuators with active model tracking center of pressure (COP).
The experiments were implemented showed that the new system
was much fitter with normal gait than counter weight system.
I. INTRODUCTION
Treadmill BWS system has been developed for
locomotion gait training system which enables patients who
cannot fully bear their weight due to hemiplegic, paraplegia,
or recover from spinal cord injury. Passive and dynamic BWS
systems, which applied so many kinds of actuator such as:
spring, pneumatic cylinder, or linear motor…, were illustrated
by [1, 2]. Those systems were characterized the ability to
provide a constant or synchronously modulated support force;
however, they did not consider tracking the COP and moving
of the center of mass in frontal axis.This paper introduces an
active Treadmill BWS system which uses PAM actuators and
characterizes COP tracking during walking.
III. RESULT AND DISCUSSION
The active model, itself tracked the COP in frontal axis
and gave desired unloading force, showed its trajectories
much fitter with COP trajectory of the normal walking than the
others. From the Fig.1 (a), in almost cases, the trajectory using
counter weight system is the biggest whilst the trajectory using
active model shows same size with the normal walking. In
Fig.1 (b) and (c), we show more clearly when the correlation
line of active model is closes to a straight line, in contrast,
counter weight system and simple model trajectories
represented as complex curves. It was due to the effect of
fluctuation of trunk when hanging by a rope in the counter
weight system while the active model was synchronous with
the moving of COP during walking.
II. METHOD
In this study, a new active BWS system has been
developed. The system included two PAM actuators which
connected a harness and a solid bar in horizontal. Each
actuator has 350 mm in free length and 25 mm in relaxed
diameter. The system was fixed on a reliable cantilever beam
and installed together with a treadmill which had four force
sensors in the four corners to measure the reaction force of
subject during walking. The control system was designed base
on NI cDAQ-9178 chassis with analog I/O modules NI-9215
and NI-9264 using LabVIEW 2013 from National Instrument.
Three experiments was implemented with a healthy subject
using counter weight system as [3], simple model and active
model with unloading force up to 30%, 50% and 70% of body
weight. Experiments were implemented at 2.0 km/h velocity
of treadmill and the data were recorded in 2 minutes.
Tran Van Thuc, He received master’s degree (2013) in mechanical
engineering from Hanoi University of Science and Technology. Since Sept.
2013, he has been a doctoral course at SIT. 307 Fukasaku, Minuma-ku,
Saitama-City, Saitama, 337-8570 Japan. (phone: +080-9410-7979; email:
[email protected]).
Flavio Prattico, He received master’s degree (2011) in Mechanical
Engineering from University of L’Aquila. Since Oct. 2011, he has been a
doctoral course at University of L’Aquila, Department of Mechanical,
Energetic, and Processing Engineering.
Mohd Azuwan Mat Dzahir, He received master’s degree (2011) in
mechanical engineering from Faculty of Mechanical Engineering at
niversiti Teknologi Malaysia; UTM. Since Sept., 2011, he has been a
doctoral course at SIT. 307 Fukasaku, Minuma-ku, Saitama-City, Saitama,
337-8570 Japan. (e-mail: [email protected]).
Shin-ichiroh Yamamoto, He received the Ph.D. (2000) degree in science
from the Department of Life Science, The University of Tokyo. He is a
professor
at
SIT,
Japan.
(phone:+81-48-720-6024;
e-mail:
[email protected])
(a)
(b)
(c)
Figure 1. (a) was COP trajectories in one gait cycle at 30% BWS
comparing to normal walking . (b), (c) represented correlation between COP
trajectories of BWS sytems and normal walking. Black line represents for
normal walking while blue, red and green lines represent for walking due to
counter weight system, simple model, and active model respectively.
REFERENCES
[1]
[2]
[3]
Frey,M, et al. , A Novel Mechatronic Body Weight Support System.
Neural Systems and Rehabilitation Engineering, IEEE Transactions on,
2006. 14(3): p. 311-321.
Glauser, M., L. Zongli, and P.E. Allaire, Modeling and Control of a
Partial Body Weight Support System: An Output Regulation
Approach. Control Systems Technology, IEEE Transactions on, 2010.
18(2): p. 480-490.
Colombo, G., M. Wirz, and V. Dietz, Driven gait orthosis for
improvement of locomotor training in paraplegic patients. Spinal
Cord, 2001. 39(5): p. 252-5.

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