European Journal of Scientific Research - EuroJournals

European Journal of Scientific Research
ISSN 1450-216X Vol.20 No.4 (2008), pp.863-870
© EuroJournals Publishing, Inc. 2008
http://www.eurojournals.com/ejsr.htm
Development of Mechanical Prosthetic Hand System for BCI
Application
N. A Abu Osman
Department of Biomedical Engineering, Faculty of Engineering
University of Malaya, 50603, Kuala Lumpur, Malaysia
S. Yahud
Department of Biomedical Engineering, Faculty of Engineering
University of Malaya, 50603, Kuala Lumpur, Malaysia
S. Y Goh
Department of Biomedical Engineering, Faculty of Engineering
University of Malaya, 50603, Kuala Lumpur, Malaysia
Abstract
The study is to develop a prosthetic hand that can be controlled by Brain-Computer
Interface (BCI). The proposed prosthetic hand consists of palm and 5 fingers. The hand
was designed to perform the 4 predetermined essential tasks in BCI applications;
cylindrical grasp, key pinch, pulp to pulp pinch and tripod pinch. The phalanges of the
finger was modeled as three link open chain joined at the metacarpal joint (MCP), proximal
joint (PIP) and distal joint (DIP). Each segment denote as phalanx was made from two
parallel aluminum plates and connected to the other segment using a bolted spacer acting as
hinge joint. Length of each segment was made such that it will form an equiangular motion
path during trajectory. Each joint is actuated by its individual actuator. Two mechanisms
were proposed in this study. The first mechanism is the tendon drive; used terelyne string
to pull each segment to flexion. The second mechanism is a spring return; a stored resistive
force in torsion spring will kick the segment to its initial position. The hand was equipped
with potentiometers and pressure sensors for control purposes. The prototype was tested
with BCI system, in order to meet its initial objective and additional tests were carried out
to evaluate its performance. An experiment to test the performance of the prosthetic hand
was carried out successfully. Strength of each tendon was measured using a proof ring
method and motion images were captured using video camera and analyzed using Peak
Motus Performance 2000 Motion Analysis software.
1.0. Introduction
Brain-Computer interface
A brain-computer interface (BCI) is a communication system in which messages or commands convey
from an individual to external device without passing through a brain's normal output pathways of
peripheral nerves and muscles. A BCI use the recorded electroencephalogram (EEG) rhythms from the
electrodes on scalp and translated to the external device. The BCI application is useful for people with
severe motor disabilities and in worst case for a completely paralyzed or “locked-in” patient that
unable to communicate by any way. BCI application is wide and can be varied depending on the need