ABSTRACT Electroencep Electroencephalogr halography aphy is used for variety of clinical clinical application applicationss especially especially in diagnosis of epilepsy, coma, death of the brain etc. Brain controlled wheel chair provides mobility to paralyzed people. If the scalp of the brain is attached with electrodes, signals are generated. Later on control signals are generated to control the wheel chair.
EEG acquisition is the basis of our proect. !"## signals are the EEG$s that respond to five senses of the person such as hearing, sight, touch, smell and taste. !"## means positive pea% after every "##ms.&here are other e'amples li%e ()## signals which means signals having negative amplitude after every )##ms.
*fter acquisition of !"## signals, interface of these signals with computer is made. In this way we analyze these signals in B+I)###. B+I)### generate the control signals to control the electric wheel chair.
o, in this way a person can differentiate differentiate among the letters, numbers, numbers, obects etc. imilarly, robotic arm can be controlled whose arm or leg is disabled.
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TABLE OF CONTENTS *B&*+&..................... *B&*+&................................. ......................... .......................... .......................... .................................................&*BLE /0 +/(&E(& .......................... ...................................... ......................... ...............................) ..................) LI& /0 0IG1E....................... 0IG1E.................................... .......................................................2 ..........................................2 LI& /0 *+/(34................... *+/(34................................ ..................................................... ........................................5 5 +hapter -....................... -.................................... .......................... .......................... ......................... .................................6 .....................6 I(&/71+&I/(................... I(&/71+&I/(............................... ......................... ................................................. .................................... 6 -.- /verview...........................................................................................................6 -.) !roblem tatement....................... tatement.............................................. ..................................................................... .............................................. 8 -."!urpose of the proect............................................. proect.................................................................... .............................................8 ......................8 -.2 *pplications of the proect........................................................ proect................................................................................. ......................... 8 -.5!roect contribution...................................... contribution............................................................. .......................................................8 ................................8 -.6!roect organization ...........................................................................................9
+hapter )....................... ).................................... .......................... .......................... ......................... .................................: .....................: LI&E*&1E E;IE<.................... E;IE<................................. ................................................. .................................... : ).-elated &echnologies............... &echnologies...................................... ............................................... .................................................... ............................ : ).-.- Electrocardiography =E+G or E>G?................................................... E>G?................................................... : ).-.) 4agneto encephalography =4EG? .....................................................: .....................................................: ).-." 0unctional magnetic resonance imaging =04I? ...............................: ...............................: ).-.2 !ositron emission tomography =!E&? ..............................................-# ).-.5 Electroencephalography =EEG?.......................................... =EEG?.........................................................-# ...............-# ).) elated !roects............................................. !roects.................................................................... ...................................................-............................-)." elated elate d tudies ............................................ ................................................................... ....................................................-) .............................-) ).2 Limitations and Bottlenec%s ............................................ ................................................................... ................................-) .........-)
+hapter "....................... ".................................... .......................... .......................... ......................... ...............................-" ...................-" &//L *(7 &E+@(IA1E.................. &E+@(IA1E............................... ..........................................-" .............................-" ".- @ardware used with technical specifications...................................................-" ".-.- *ctive Electrodes for EEG ignal *cquisition.................................-" ".-.) *mplifier Board....................................................... Board....................................................................... ......................... .........-2 -2 ".) oftware, simulation tool used ........................................................................-6 ........................................................................-6 ".).- B+I)###...........................................................................................-6
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+hapter 2.............................................................................................-8 4E&@/7/L/GIE..........................................................................-8 2.-@ardware Implementation procedure................................................................-8 2.-.- EEG *cquisition..............................................................................-8 2.-.) *mplifier Board............................................................................... -8
+hapter 5.............................................................................................)E1L& *(7 *(*L3I.............................................................)5.- !resentation of the findings .............................................................................)+hapter 6................................................................................................................)6
+/(+L1I/(...................................................................................)6 BIBL/G*!@3 *(7 E0E(+E...............................................)8
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LIST OF FIGURES Fig. 2.1 – Waveforms of Differe! EEG"S Fig. #.1 – A$!ive E%e$!ro&e Com'oe!s Fig. #.2 – S$(ema!i$ of Am'%ifier Boar& Fig. ).1 – *ro!e$!io Cir$+i! Fig. ).2 – Is!r+me!a!io Am'%ifier Fig. ).#,a- – 1s! S!age Fi%!er Fig. ).#,- – 2& S!age Fi%!er Fig. /.1 – So+& Car& S$o'e EEG Ra0 Siga% Fig. /.2 Origia% So+& Car& Siga% 0i!( Noise avig Fre3+e$4 5 6 Fig. /.# E4e B%i7 Tes! Fig. /.) – Too!( Gri&ig Tes! Fig. /./ ECG Siga% Fig. /.5 ECG Siga% 0i!( Fre3+e$4 4 S!o''ig Brea!( Fig. /.8 Origia% ECG Siga% Usig L*F
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LIST OF ACRON9:S
EEG
Electroencephalography
E+G
Electrocardiography
g
Gain esistor
B+I
Brain +omputer Interface
4EG
4agneto Encephalography
04I
0unctional 4agnetic esonance Imaging
!E&
!ositron Emission &omography
B
Blind ignal eparation
&00
pace &ime 0requency 0iltering
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C(a'!er 1 INTRODUCTION 1.1
Overvie0
&he proect is about controlling the wheel chair via electroencephalographic =EEG? signals. Electroencephalography means recording of electric signals from the brain. It is used for variety of clinical applications especially in diagnosis of epilepsy, coma, stro%e, tumor etc. &here are many waveforms in EEG depending upon its frequency and shape for e'ample delta, beta, mu, !"##, ()## etc. !"## signals are the EEG$s that respond to five senses of the person such as hearing, sight, touch, smell and taste. !"## means positive pea% after every "##ms.&here are other e'amples li%e ()## signals which means signals having negative amplitude after every )##ms. !"## are the signals that are used to control the direction of electronic wheel chair. &hese signals are generated from the specific position on the brain such as 0", 02, !" and !2. Letters 0 and ! are frontal and parietal lobe using the international -#)# system of electrode placement. It is system for the placement of electrodes at specific intervals along the head that is used most widely around the world. Each lobe is identified using letters such as !, 0 and + etc. If the scalp of the brain is attached with electrodes at 0", 02, !" and !2 positions, !"## signals will generate. &hese signals are of low amplitude. &herefore they are amplified many times. Later on these amplified signals are interfaced with software B+I)###. B+I)### is used for the building brain computer interface systems from the EEG$s such as !"## signals. It provides control capability and the communication capability to person with disabilities li%e paralysis etc. Later on control signals are generated using B+I)### to control the wheel chair. .
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1.2 *ro%em S!a!eme! &here are millions of paralyzed people around the world. * person with paralyze legs and arms can not move around independently. EEG signals are of very low amplitude such as few micro volts only. &he acquisition of these signals can easily subect to noise. EEG varies from people to people. &herefore B+I)### has to average 5#6# signals of different people.
1.#
*+r'ose of !(e 'ro;e$!
&he ultimate purpose is to provide mobility to paralyze people by using brain controlled wheel chair. !aralyzed muscles such as legs and hands are disabled organs of the body. o, if only the brain fully functional then he can still move easily around with brain controlled wheel chair.
1.) A''%i$a!ios of !(e 'ro;e$! Brain controlled wheel chair can be used to control the robotic arm by replacing robotic arm with wheel chair. imilarly, it provides the mobility to paralyzed people.
1./
*ro;e$! $o!ri+!io
o
Low amplitude EEG signals acquisition
o
*mplification of acquired signals
o
7igitization of the amplified signals
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o
Interface with computer using software B+I)### to generate control signals for wheel chair.
1.5
*ro;e$! orgai6a!io
+hapter - is the introduction of the proect. It includes the overview, statement of the problem, purpose, applications of the proect. +hapter ) is about literature review of the proect. It includes related technologies, proects, studies and limitations of the proect. +hapter " is about the tools and techniques of the !roect. It includes the hardware used with complete technical specifications, software tools used for the proect. +hapter 2 is about the methodologies and implementation of the proect. It includes design,
analysis
procedures, implementation
procedure
and
verification
of
functionalities and mathematical modeling of the proect. +hapter 5 is about the results and analysis of the proect. It includes hardware and software results, discussion of the findings, limitations and recommendations of the proect +hapter 6 is about the conclusion of the whole report
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C(a'!er 2 LITERATURE RE
Re%a!e& Te$(o%ogies
&he core of proect is the EEG$s. EEG stands for electroencephalography. Electro means electric signals, encephalo means related to the brain and graphy means drawing. It means EEG is the drawing of electric signals from the scalp of the brain. *s it is related to the brain so, its related technologies are as follows
2.1.1 E%e$!ro$ar&iogra'(4 ,ECG or E=G*n E+G is the recording of electrical activity from the heart detected by electrodes attached to the outer surface of the s%in and recorded by a device e'ternal to the body.
2.1.2 :age!o e$e'(a%ogra'(4 ,:EG4agneto encephalography is used for mapping brain activity from electric currents produced within the brain. In this way, magnetic field is produced. &he recording of these magnetic fields is called 4agneto encephalography. esearch areas are !ictorial evaluation of brain various parts, +ognitive brain processes etc.
2.1.# F+$!ioa% mage!i$ resoa$e imagig ,F:RI0unctional magnetic resonance imaging is the measuring of brain activity by detecting changes in the blood flow. It is used both in research and clinical use.
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2.1.) *osi!ro emissio !omogra'(4 ,*ET!ositron emission tomography is a procedure for the acquisition of three dimensional pictures of the functional processes of the human body.
2.1./ E%e$!roe$e'(a%ogra'(4 ,EEGEEG signals first have been recorded in -98#Cs. lowly scientists discover that these EEG signals not only show the function of the brain but also give information about the body movements. 7ifferent diseases or disorders in the brain can be recorded and diagnosed. Electro =electric signals from neuron within the scalp? graphy means drawing or recording the signals. &hese are also called bioelectric signals. &here are certain wave patterns in EEG which is shown in fig. ).D
7elta frequency range is up to 2 @
D
&hetas frequency range is between 29 @
D
*lpha frequency range is up to 9-" @
D
Beta frequency range is greater than -""# @
D
Gamma frequency range is from "#-## plus @
D
4u frequency range is between 9-" @
Fi . 2.1 – Waveforms of &iffere! EEG"s
-#
ome EEG artifacts are D
Eye blin%s
D
Eye movements
D
E'tra/cular muscle activity
D
E4G which is due to the activation of muscles
D
Gloss %inetic artifacts
D
Environmental artifacts are due to not good grounding of electrodes which cause 5#6# @ artifact, movement of the subect etc
2.2 Re%a!e& *ro;e$!s
&here are several proects related to brain controlled wheel chair had been done before. @umana has built the brain controlled wheel chair with great success. Its author is !/ FE>E3. It was published on 7E+ :, )#-# under the license of B3 (/*. &he !arts of the !roect are EEG headset, electric wheelchair, laptop, an auridono, interfacing circuit, softwareCs &he software used is specifically written for the proect. -H In Fapan researchers had made a success in controlling the wheel chair by thought .&he electrodes cap acquire the brain waves in -)5 th of a second. It is very efficient and is :5 percent accurate after the e'periments were made. (ational Geographic had also made a documentary on it. )H imilarly &oyota and i%en research lab have already made the brain controlled wheel chair. "H
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2.# Re%a!e& S!+&ies
In Fapan$s BI&/3/&* +ollaboration +enter observed that the sensor set used for the recording of EEG can also be used for Blind signal separation and space time frequency filtering. Blind signal separation =B? can also be used to control the electric wheel chair. B separates the two components from the signal such as noise components and required signal components of brain waves. imilarly, space time frequency filtering =&00? can also be used to control the electric wheel chair. *s the name suggests, space time frequency filtering =&00? e'tracts space and time patterns and frequency oscillation data from EEG electrodes to discriminate significant features and components. 2H
2.) Limi!a!ios a& Bo!!%ee$7s
Electroencephalography has much limitation such as poor spatial resolution of EEG signal, sensitive to post synaptic signals. 4ost importantly different people have different EEG$s. It means that EEG varies in amplitudes from people to people. o there is need of training of subect on the software such as B+I)### which is used to control the electric wheel chair.
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C(a'!er # TOOLS AND TECNI>UES #.1 ar&0are +se& 0i!( !e$(i$a% s'e$ifi$a!ios &he hardware consists of three maor parts which are active electrode or passive electrode, amplifier board and digital board. *ctive Electrode consists of operation amplifier and silver wire. *mplifier board consists of instrumentation amplifier, filters, right leg driver and operation amplifiers. &he detailed description of all parts used is give below,
#.1.1 A$!ive E%e$!ro&es for EEG Siga% A$3+isi!io Electrodes are used to detect electrical current. In our case we place them on our scalp to detect brainwaves. &here are two basic types of electrodes •
*ctive
•
!assive
*ctive electrodes are electrodes plus some circuitry which is used for amplification. It greatly improves the EEG signal. !assive electrodes are simple electrodes requires the s%in preparation and conductive paste
#.1.1.1 A$!ive E%e$!ro&e Com'oe!s
&he active electrode components is shown in 0ig ".-
•
)##% esistors
•
-##/hm esistors
•
-##p0 +apacitors
-"
•
-#n0 +apacitors
•
&L+)8) /p amps amplifies the EEG signals
•
ilver wire of -mm diameter
Fig. #.1 – A$!ive E%e$!ro&e Com'oe!s
#.1.1.2 *assive E%e$!ro&e Com'oe!s
!assive electrodes need no additional circuitry. &here are many %ind of passive electrodes li%e saline salt electrode, pasteJgel electrodes etc.
#.1.2 Am'%ifier Boar& *mplifier Board components used for amplification of signals are
•
!rotection +ircuit
•
Instrumentation *mplifier
•
/perational *mplifier
•
Low !ass 0ilter
•
7L +ircuit
&he schematic of amplifier board is shown in fig. ".)
-2
-5
Fig. #.2– T(e S$(ema!i$ of Am'%ifier Boar& 0igure ".) is the schematic of the amplifier board which we unfortunately were unable
to complete due to non availability of components and issues in the ma%ing of active electrodes. o, we adopt the design of different amplifier board with little modification of 0ig. ".).
#.2 Sof!0are? sim+%a!io !oo% +se&
#.2.1 BCI2@@@ B+I stands for brain computer interface. It is used for research, signal acquisition, stimulus operation and brain monitoring applications. B+I provides control capability and the communication capability to person with disabilities li%e !aralysis etc. It is used for the building of B+I systems from the brain signals. *lgorithms are provided in the B+I toolbo'es. /nly we need is to provide the !"## signals to B+I)###. B+I)### ta%es 5#6 samples of !"## signals of different person and as% them thin% about some specific thing. In this way, 5#6# samples are averaged. &he need of too many samples is due the fact that EEG waveform varies from person to person.
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C(a'!er ) :ETODOLOGIES ).1
ar&0are Im'%eme!a!io 'ro$e&+re
&he design of the hardware needs signal acquisition, signal amplification and computer interface. &he detailed description of all parts is give below,
).1.1 EEG A$3+isi!io EEG signals are merely of few micro volts. o, passive electrodes are used. 7ue to very low amplitude of EEG signal, it can be easily subected to noise particularly 5#J6#@z hum main from the wirings nearby.
).1.2 Am'%ifier Boar& *fter the acquisition of signals, they are amplifier thousand times5H. &he detailed description is given below ).1.2.1 *ro!e$!io Cir$+i!
&he EEG signal is pic%ed up by the two topmost electrodes and passed through the protection circuit. It serves two purposes
•
It protects the circuit from E7
•
It protects the user from failing circuitry
+apacitors of ))## ohm +)-#, +)#6 and +)#8 cancel out radiofrequency signals. &hen the transistors act as clamping diodes and some resistors as shown in 0ig.2.-
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Fig. ).1 – *ro!e$!io Cir$+i!
).1.2.2 Is!r+me!a!io Am'%ifier
Instrumentation amplifier is a %ind of differential amplifier whose output is the difference of the inputs multiplied by the gain. Gain can be set by a single resistor which is -).). I+ used is *76)# which is a high precision instrumentation amplifier. Its maor application is E+G amplification. 0ollowing are the two characteristics of instrumentation amplifier, •
4easures ; difference between two locations
•
+ommonmode signal K = =? =? ? inputs J )
5#J6# main hum canceled by instrumentation amplifier as main hum on both electrodes are same. It ensures the main hum never enters the system. 7L stands for ight Leg 7river because it is attached to right leg. It is used to cancel commonmode signals coming from mains hum.
Instrumentation amplifier amplifies the EEG .It has low impedance and is little subected to noise .&he gain is
-9
G K - 5# J g,
=Eq. 2.-?
where g K )-6 )-8
=Eq. 2.)?
/ne e'ternal resistor is used to set the gain such as g. g are of ))## ohm each as shown in 0ig. 2.)
Fig. ).2 – Is!r+me!a!io Am'%ifier
).1.2.# O'era!io Am'%ifiers
Instrumentation amplifier is then followed by the noninverting amplifier. *n operational amplifier is a differential amplifier with a single ended output.
Fig. ).#,a- – 1s! S!age Am'%ifier
-:
Fig. ).#,- – 2& S!age Am'%ifier
Gain of -st stage amplifier is 2# as shown in 0ig, 2."=a?. 7ue to !)#", gain can be varied from 6 to -##. Last amplifier amplifies EEG signal -6 times more as shown in fig. 2."=b?. G K =!)#" ))) ))5? J !)#" )))
=Eq. 2."?
)#
C(a'!er / RESULTS AND ANAL9SIS /.1 *rese!a!io of !(e fi&igs &he most interesting part of the proect is their results and analysis. *fter the acquisition of bioelectric signals from passive electrodes, it is sent to instrumentation amplifiers and then operation amplifiers for the amplification of EEG signals. 0or the visualization of these EEG$s we use the software named sound card scope. &he raw EEG obtained using sound card scope is shown in fig. 5.-.
Fig. /.1 – So+& $ar& s$o'e EEG ra0 siga%
)-
EEG signal with frequency 6 @z having noise is shown in fig. 5.). *s e'plained in the last chapter noise can be in the form of 7+ offsets which will also be amplified along with the EEG li%ewise, noise can be 5#J6# @z main hum due to surroundings wiring.
Fig. /.2 Origia% so+& $ar& siga% 0i!( oise (avig fre3+e$4 5 6
Fig. /.# E4e %i7 !es!
))
&he ideal test for EEG is the eye blin% test and tooth grinding test. In eye blin% test, amplitude is increased. &his can be seen in spectrum analyzer shown in 0ig. 5."
Fig. /.) – Too!( gri&ig
In tooth grinding test? ma'imum amplitude of the raw EEG is increased and minimum is decreased as shown in 0ig. 5.2.
Fig. /./ ECG siga%
)"
&he E+G signal can be obtained by putting two active electrodes near heart and ground electrode at right leg as shown in 0ig. 5.5. &he frequency of E+G signal obtained by stopping the breath is 8".5: @z as shown in fig. 5.6.
Fig. /.5 ECG siga% 0i!( fre3+e$4 4 s!o''ig rea!(
)2
&o obtain the real EEG or E+G signal we have to filter the signal. * signal is a mi'ture of EEG or E+G with noises. o, using the low pass filter which is inside the sound card scope, pure E+G is obtained. &he low pass filtered signal is shown in 0ig. 5.8. &he cutoff frequency of the low pass filter is 5# @z.
Fig. /.8 – Origia% ECG +sig L*F
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C(a'!er 5
CONCLUSION &o achieve the goal of ma%ing of brain controlled wheel chair, !"## signal has acquired. It is obtained by putting passive electrodes at positions !", !2, 0" and 02 of the head. *fter the acquisition of !"## signal has made, amplification of the signal has done. *mplification has been made by instrumentation amplifier *76)# with the gain of -).). *gain the amplification is made by two operational amplifiers &L+)88 with the gain of 2# and -6 respectively. *fter the amplification of !"## signals, signals are digitized using microcontroller. &he output of the microcontroller is -2 @z !<4 square wave signal. In this way, brain computer interface is achieved.
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BIBLOGRA*9 AND REFRENCES
-HhttpMJJnews.nationalgeographic.comJnewsJ)##:J#8J#:#8#)braincontrolled wheelchair.html )HhttpMJJwww.instructables.comJidJBrain+ontrolled
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