Synchronization of EMG and GRF Measurement System Using

Report
Moulali.P
Central Scientific Instruments Organization (CSIO),
Council for Scientific and Industrial Research (CSIR),
Chandigarh, India.
Overview
 Introduction
 EMG
 VGRF
 Objective
 Methods & Materials
 Experimental set-up for data acquisition
 Software Analysis
LabVIEW VI for data acquisition

Matlab Analysis
Results and Discussion
Conclusions
Future Work
References

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

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May 11, 2010
1. INTRODUCTION
Raw EMG signal
 EMG -Electromyography :
study of muscle function
through analysis of
electrical signals
emanated during
muscular contraction.
 VGRF-Vertical Ground
Reaction Force: vertical
component of force
exerted on foot by the
ground during walking.
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Amplitude
(mv)
Time(ms)
Fz1
Fz2
Fz3
 Four active EMG surface electrodes attached to right
leg of subject over
i. gastrocnemius lateralis (GL)
ii. tibialis anterior (TA)
iii. biceps femoris (BF)
iv. vastus lateralis (VL)
Biometrics SX230 active surface electrode
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Objective
Synchronizing EMG and VGRF data using LabVIEW software
and analyzing the LabVIEW data with Matlab tool box.
 Hardware and software development for acquisition of
EMG and force plate data (VGRF) at a time.
Applications:
 Displaying synchronized data in one panel side by side.
 Acquired (synchronized) data provides comparison of
VGRF & EMG data simultaneously.
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Materials & Methods
Experimental set-up
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Subject with EMG electrodes walking over the Kistler force plate
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LabVIEW VI for data acquisition
Synchronized data is acquired and stored in computer for
further analysis
EMG data acquired directly and low pass filters used
before acquiring GRF data
Block diagram of VI for synchronization of both EMG and force plate data.
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Matlab Analysis
 Obtained data from LabVIEW is imported into Matlab
tool for analysis.
 It is observed that there is DC offset error in the raw
EMG signal but no such effect is observed in in force
signal.
 Next the signal is rectified and passed through low
pass filter and notch filter.
 RMS, Mean and Median are calculated
 From VGRF peak values are calculated by writing
separate Matlab code
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Raw
EMG
Signal
Elimination of DC Offset
Rectification
Low Pass Filtered Signal
Notch Filtered Signal
Time
Domain
RMS
Frequency
domain
Mean
Median
Flow chart showing steps involved in EMG signal analysis
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Results and Discussion
 To show results MATLAB Graphical User Interface
(GUI) was developed.
 Using GUI , synchronized data was loaded into the
program and the required parameters of EMG and
force data were evaluated.
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Developed GUI for analysis of synchronized EMG and force data
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Conclusion
 Analyzed data helps us to understand how GRF have
stimulated the muscle activity.
 Results obtained from analyzing module are exactly
not matching to those obtained from the software that
are provided along with those system. It is because the
techniques used for analysis is not alike or some
multiplication factor missing .
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Future scope
 Analysis module is in developing stage , so we are
trying to incorporate a number of other parameters,
which will enhance the performance of developed
tool.
 The parameter values are to be cross verified with
standard reference tool.
May 11, 2010
References
[1]. Q.H Huang, Y.P Zheng, X.Chena, J.F He and J Shi (2007). A
system for the synchronized recording of sonomyography,
electromyography and joint angle. Open Biomed Eng J.2007; 1:
(77-84).
[2]. Finch.A.E, Ariel G.A, and Penny A.M , Biomechanical
integration of essential human movement parameters.
[3]. Levin.O, Mizrahil.J, Adam.D, Verbitsky.O and Isakov.E.(). On
the correlation between force plate data and EMG in various
standing conditions.
[4]. Sousa.F, Conceiltao.F, Gonltalyes.P, Carvalho.J.M,
Soares.DScarrone.F, Loss.J, Vilas-Boas.J.P(2002). Biomechanical
analysis of elementary ballet jumps; Integration of force plate
data and EMG records. ISBS 2002, Caceres-ExtremaduraSpain(175-178).
May 11, 2010
THANK YOU
May 11, 2010

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