平成28年度 修士論文 · using Doppler sensor Amir Maleki Abstract Many phenomena in the...
Transcript of 平成28年度 修士論文 · using Doppler sensor Amir Maleki Abstract Many phenomena in the...
平成28年度 修士論文
Non‐contact measurement of eyeblink by using Doppler
sensor
学籍番号 1532072
氏名 AMIR MALEKI
知能機械工学専攻 内田雅文研究室
指導教員 内田雅文 准教授
副指導教員 桐本 哲郎 教授
提出日 平成29年02月28日
Non‐contact measurement of eyeblink by using Doppler
sensor
Amir Maleki
Graduate School of Informatics and Engineering
The University Of Electro‐Communications
Master Thesis
March 2017
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修士論文28年度
ドップラーセンサーを用いたアイブリンクの非接側定
論文要旨
自然界にはさまざまなゆらぎ現象が確認されるが、それらが統計的に完全に独立で不
規則な過程を示すことは稀である。瞬目はヒトにとって極めて自然な運動の一つであり、
認知科学,ヒューマンコンピュータインタフェース等に応用が期待されている。例えば
認知科学の分野では,ヒトの数々の精神的かつ身体的な運動が 1/f ゆらぎの特性を示し
得ることが確認され、多くの研究者がゆらぎ特性の意味することを見つけようと試みて
いる。瞬目は車両および航空機運転者の眠気の探知に有効である為,瞬目の計測の重要
性は高い。従来,瞬目の計測には EOG、赤外線センサ、カメラおよびドップラーセンサ
などが 用いられてきた。近年では、グーグルグラスのよう、赤外線センサなどの搭載
されたセンサにより瞬目を計測可能な眼鏡型デバイスがいくつか提案されている。ドッ
プラーセンサは、他の手法では問題となる長距離での検出などいくつかの長所がある。
故に、本研究ではドップラーセンサを搭載することによりヒトの瞬目を計測可能な眼鏡
型デバイスの開発を目的とする。
眼鏡型デバイスは運転中に装着可能である事から、運転者の眠気検出が可能であり、
ヒューマンエラーの抑制に寄与できるものと考えられる。実験はドップラーセンサーに
より瞬目を計測すると共に、身体の動きを計測するための加速度センサ、および瞬目信
号が正当であることを確認するための EOG を用いて行う。実験結果より、瞬目に関する
ドップラー周波数は 2Hz 近辺に高い周波数を含むことが確認された。さらに、観測され
るデータに頭や体の動きが含まれてしまう場合、PCA を用いてそれらから瞬目信号を分
離可能であることを確認できた。
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Non‐contactmeasurementofeyeblinkbyusingDopplersensor
Amir Maleki
Abstract
Many phenomena in the nature exhibit anomalously large temporal fluctuations
exceeding what cannot be explained as a consequence of statistically independent random
events. Eyeblink is one of the natural parts of human activities which can be used in diverse
applications such as Cognitive fields, Human Computer Interfaces etc. For instance, there is a
large and growing body of evidence that sequences of psychophysical data fluctuate as 1/ƒ
noises and many researchers are trying to find what these fluctuations are suggesting us.
Considering the fact that eyeblink has been proposed as a marvelous way for detecting driver’s
and pilot’s drowsiness, the importance for eyeblink detection is increasing. There are several
ways for eyeblink detection such as the EOG method, Infrared sensors, Cameras, and Doppler
sensors. Recently, several types of glasses have been produced, for instance ‘Google glass’,
which is able to detect eyeblink using embedded sensors such as infrared sensors. The objective
of this thesis is to develop a glass which can be used to measure human eyeblink through
embedding a Doppler sensor inside it, considering to the fact that Doppler sensors have a
number of advantages, for instance, long distance detection that is a problem in other methods.
This glass can be used during driving and flying in order to detect drowsiness and therefore
prevent accidents caused by human errors. Furthermore, it can be deployed for measuring
several psychological factors during performing tasks in clinical setups. We designed an
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experimental setup in which measurement of the eyeblink was conducted using a Doppler
sensor accompanied by an accelerometer for body movement measurements and also an EOG
(Electrooculography) recording for verifying detected eyeblink signal by Doppler sensor. From
our experimental results, we found that the Doppler frequency related to eyeblink contains a
dominant frequency near 2 Hz. Finally, we found that when blinking is accompanied with head
and body movements, eyeblink signal is separable by deploying the Principal Component
Analysis.
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ContentsFigure index ............................................................................................................................. 5
Chapter 1 Introduction .......................................................................................................... 8
1.1 Background ............................................................................................................................ 8
1.2 Motivation ............................................................................................................................. 9
1.3 Related works on the eyeblink detection ........................................................................... 10
1.3.1 EOG (Electrooculography) method .............................................................................. 10
1.3.2 Optical sensors ............................................................................................................. 12
1.3.3 IR (Infrared) sensors ..................................................................................................... 14
1.3.4 Doppler sensors ............................................................................................................ 16
1.4 Aplication ............................................................................................................................. 22
1.5 Thesis organization .............................................................................................................. 23
Chapter 2 Concept ................................................................................................................. 24
2.1 Doppler Sensor .................................................................................................................... 25
2.2 Accelerometer ..................................................................................................................... 26
Chapter 3 Measurement system ............................................................................................ 27
3.1 EOG recording ..................................................................................................................... 28
Chapter 4 Analysis method and results .................................................................................. 32
4.1 results when the subject’s head and body was steady ....................................................... 33
4.2 results when the subject’s head and body was not steady ................................................ 40
Chapter 5 Conclusion and future work .................................................................................. 54
Acknowledgment .................................................................................................................. 56
References............................................................................................................................. 57
Publications and conferences ................................................................................................ 59
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Figureindex
Figure 1.1 ORBICULARIS OCULI muscle…………………………………………………………………………………….11
Figure 1.2 Infrared proximity sensor built into Google Glass……………………………………………………15
Figure 1.3 Blink detection by calculating the peak value……………………………………………………….…16
Figure 1.4 source and motive receiver………………………………………………………………………………….…17
Figure 1.5 motive source and receiver……………………………………………………………………………………..19
Figure 2.1 the concept of the designed glass………………………………………………………………………..….24
Figure 2.2 Doppler sensor………………………………………………………………………………………………………..25
Figure 2.3 Accelerometer…………………………………………………………………………………………………….….26
Figure 3.1 Experimental system…………………………………………………………………………………………….…27
Figure 3.2 EOG recording…………………………………………………………………………………………………………28
Figure 3.3 MULTI AMPIFIER MA1000‐DIGITECS…………………………………………………………………….…29
Figure 3.4 Experimental setup when the Doppler sensor was fixed to a stand…………………………29
Figure 3.5 Experimental setup when the Doppler sensor was attached to a pair of glasses……..30
Figure 3.6 three different angles for eyeblink detection when the Doppler sensor was mounted
on a fixture and head and body were fixed………………………………………………………………................30
Figure 3.7eyeblink detection when when the Doppler sensor was attached to a pair of
glasses………………………………………………………………………………………………………………………………….…31
Figure 4.1 Eyeblink detection flow………………………………………………………………………………………….32
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Figure 4.2 Experimental Protocol……………………………………………………………………………………….……33
Figure 4.3 a sample of recorded EOG………………………………………………………………………………………34
Figure 4.4 Spectrum of the recorded EOG…………………………………………………………………………….…34
Figure 4.5 A sample conscious eyeblink detected by Deppler sensor………………………………….…..35
Figure 4.6 Spectrum of the Sample conscious eyeblink detected by Deppler sensor…………….…35
Figure 4.7 A sample unconscious eyeblink detected by Deppler sensor…………………………………..36
Figure 4.8 Spectrum of the Sample unconscious eyeblink detected by Deppler sensor……………36
Figure 4.9 Mean of 100 samples of conscious eyeblink……………………………………………………………37
Figure 4.10 Mean of 100 samples of unconscious eyeblink…………………………………………………..…37
Figure 4.11 Spectrum for mean of 100 samples of conscious eyeblink……………………………….……38
Figure 4.12 Spectrum for mean of 100 samples of unconscious eyeblink…………………………………38
Figure 4.13 Experimental results when eyeblink was conscious: (a) ‐45 degree below the eye
center, (b) 0 degree and (c) +45 degree above the eye center…………………………………………………39
Figure 4.14 Experimental results when eyeblink was unconscious: (a) measured data from ‐45
degree, below the eye center, (b) 0 degree and (c) +45 degree above the eye center………….….40
Figure 4.15 The arithmetic mean of 100 samples of Doppler signals: (a) when the subject sat in
front of the personal computer and performed a routine task and (b) when the subject
performed the walking task………………………………………………………………………………………………….…41
Figure 4.16 The power spectrum of the signals represented in figure 4.14…………………………..…42
Figure 4.17 The accelerometer signals: (a) when the subject sat in front of the personal
computer and performed a routine task and (b) when the subject performed the walking
task…………………………………………………………………………………………………………………………………….…..43
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Figure 4.18 The Power Spectrum of the signals represented in figure 4.16 (Accelerometer
signals)……………………………………………………………………………………………………………………………………43
Figure 4.19 First principal components of the signals when the angle between the sensor and
the center of eye is 0°: (a) conscious blinking and (b) unconscious blinking……………………….……45
Figure 4.20 The power spectrum of the first to sixth principal components of the signal when
the subject sat in front of a personal computer and performed a routine task…………………….….46
Figure 4.21 The power spectrum of the first to sixth principal components of the signal when
the subject performed a walking task………………………………………………………………………………………47
Figure 4.22 Reconstructed blinking signal when the subject sat in front of a personal computer
and performing a routine task…………………………………………………………………………………………………48
Figure 4.23 Reconstructed blinking signal when the subject performed a walking task……………49
Figure 4.24 Eyeblink detection procedure when the subject sat in front of a personal computer
and performing a routine task…………………………………………………………………………………………………50
Figure 4.25 Eyeblink detection procedure when the subject performed a walking task………..…50
Figure 4.26 The power spectrum of the first to sixth principal components of the signal when
the second subject sat in front of a personal computer and performed a routine task………..….51
Figure 4.27 The power spectrum of the first to sixth principal components of the signal when
the second subject performed a walking task………………………………………………………………………....52
Figure 4.28 Eyeblink detection procedure when the second subject sat in front of a personal
computer and performing a routine task…………………………………………………………………………..…….53
Figure 4.29 Eyeblink detection procedure when the second subject performed a walking
task………………………………………………………………………………………………………………………………………….53
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Chapter1Introduction
1.1Background
The importance of eyeblink detection has been raised since blinking has been introduced as
a complex phenomenon which reflects the influence of higher nervous processes so that
different experimental conditions consequences changes in blink patterns. The blink rate
decreases significantly while performing visual tasks and this inverse relationship between blink
rate and task demands may address mental demands for information processing [1][2].
Recently, development of human‐computer interfaces is attracting worldwide attention of
researches [3]. In order to measure the blinking activity there are several techniques such as
EOG (Electrooculography), image processing, Infrared proximity sensor, Doppler effect sensor,
etc. EOG technique is the most precise method but it needs several electrodes to be attached to
the skin and it seems somewhat impractical during implementing every day’s activities. Image
processing methods are noninvasive and detect the blinking patterns by focusing on face
recognition. However, in condition such as driving in which the light intensity changes time by
time the eyeblink detection may be unsuccessful [3]. One common technique of eyelid
movement detection utilizes measurements of infrared (IR) light reflected from the surface of
the eye. The performance of current IR sensors, however, is limited by their sensitivity to
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ambient infrared noise, by their small field‐of‐view and by short working distances [4]. Doppler
sensors are a non‐contact way for measuring eyeblink and it is insensitive to light intensity and
it can detect blinking from a considerable long distance. Thus using Doppler sensors has a high
potential of becoming a practical way for eyeblink detection. Unfortunately, there are a few
researches about the eyeblink detection using Doppler sensor and there is not any concrete
method for this type of eyeblink measurement.
1.2Motivation
Eyeblink may find a verity of applications. As an important example, by detecting the
eyeblink rate, the measurement of level of drowsiness in drivers becomes possible and
consequently it can drastically reduce the vehicular accidents caused by human failures.
Furthermore, eyeblink detection may find applications for measuring several psychological
factors, e.g. mental workload, cognitive load, etc. Thus it can be employed for pathological
settings and also for improvement of workers efficiency while implementing tasks. The aim of
this study is to verify eyeblink detection in several real conditions such as working with
computer at office and walking and also develop a method in which the separation of the
eyeblink signal from the original signal that is contaminated with head and body movement
becomes possible. The speed of a voluntary eyeblink for the closing and opening phases are
[52~138 mm/s] and [24~47 mm/s], respectively [5]. Therefore we can estimate that the Doppler
frequency of blinking has an approximate range of [1~5.4 Hz]. However, this range can be
extended to [1~18 Hz] due to the higher speed of blinking in some human subjects. Our
empirical results showed that the head and body movements has the same frequency range as
does blinking, therefore detection of eyeblink becomes considerably difficult in real situations
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such as performing tasks, walking, etc. Thus conventional low pass filters are almost inefficient.
We deployed Principal Component Analysis in order to extract the blinking signals from the
mixed raw signals and we observed that there is a high possibility of separating the eyeblink
signals.
1.3Relatedworksontheeyeblinkdetection
1.3.1EOG(Electrooculography)method
One of the most precise methods of eyblink detection is EOG (electrooculography). Eyeblinks
are periodic closings and re‐openings of the eyelid. The duration of the eyelid closure is used as
the criterion to discriminate an eyeblink from an eye closure. An eyeblink closure duration is
usually 300 msec and is more typically 200 msec or less. The EOG records changes in the
electrical potentials between the cornea and retina as the eyelid movement occurs. The lid
closing over the eye causes a difference in the corneal/retinal potential that is evident in the
EOG. Therefore, the EOG can be used to detect eyeblinks. However, the measurement of
eyeblink can be achieved by placing electrodes on the lower and upper (or vertical) or the left
and right (or horizontal) sites of the orbicularis oculi muscle (above and under the right eye)
shown in figure 1.1[6].
Figure 1
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12
1.3.2Opticalsensors
This method is based on optical tracking of eyelid movements to detect eye blinks.
Detection is based on matching SIFT (scale‐invariant feature transform) descriptors computed
on GPU. First, threshold frame difference inside the eye region locates motion regions.
Consequently, these regions are being used to calculate the optical flow. While user blinks,
eyelids move up and down and the dominant motion is in vertical direction. This method
detects 97% of blinks on their dataset. Most of the false positive detections are the result of
gaze lowering and vertical head movements. There are several methods for eyeblink detection,
one of them is optical flow estimation. It locates eyes and face position by 3 different classifiers.
The algorithm is successful mostly when the head is directly facing the camera. The KLT
(Kanade–Lucas–Tomasi) tracker is used to track the detected feature points. This blink detector
uses GPU‐based optical flow in the face region. The flow within eyes is compensated for the
global face movement, normalized and corrected in rotation when eyes are in non‐horizontal
position. Afterwards dominant orientation of the flow is estimated. The flow data are processed
by adaptive threshold to detect eye blinks. Authors report good blink detection rate (more than
90%). However this approach has problems with detecting blinks when eyes are quickly moving
up and down. The eyelid movements are estimated by normal flow instead of optical flow. It is
the component of optical flow that is orthogonal to the image gradient. Authors claim that the
computation of normal flow is more effective than the previous methods. Arai et al. present
Gabor filter‐based method for blink detection. Gabor filter is a linear filter for extracting
contours within the eye. After applying the filter, the distance between detected top and
bottom arc in eye region is measured. Different distance indicates closed or opened eye. The
problem of arc extraction arises while the person is looking down. Variance map specifies
distribution of intensities from the mean value in an image sequence. The intensity of pixels
located in eye region changes during the blink, which can be used in detection process.
Correlation measures the similarity between actual eye and open eye image. As someone
closes eyes during the blink, correlation coefficient decreases. Another blink detection
algorithm is based on the fact that the upper and lower part of eye has different distribution of
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mean intensities during open eyes and blinks. These intensities cross during the eyelid closing
and opening. Liting et al. [8] use a deformable model ‐ Active Shape Model represented by
several landmarks as the eye contour shape. Model learns the appearance around each
landmark and fits it in the actual frame to obtain new eye shape. Blinks are detected by the
distance measurement between upper and lower eyelid. Ayudhaya et al. [9] detect blinks by
the eyelid’s state detecting (ESD) value calculation. It increases the threshold until the resulting
image has at least one black pixel after applying median blur filtering. This threshold value (ESD)
differs while user blinks.
Here we will introduce briefly two proposed methods based on histogram
backprojection and the Inner movement detection based on KLT feature tracker.
1.3.2.1HistogramBackprojection
Histogram backprojection creates a probability map over the image. In other words
backprojection determines how well the pixels from the image fit the distribution of a given
histogram. Higher value in a backprojected image denotes more likely location of the given
object. High percentage of skin color pixels within the eye region represents closed eyes and
otherwise eyes are considered opened.
1.3.2.2InnerMovementDetection
Optical flow is usually used in this method. Optical flow is the relation of the motion
field:
The 2D projection of the physical movement of points relative to the observer to 2D
displacement of pixel patches on the image plane. One of the most common methods called
KLT tracker selects features suitable for tracking with high intensity changes in both directions.
14
If a user blinks, the mean displacement of feature points within the eye region should be
greater than the displacement of the rest of the points within the face area.
The first step consists of localizing a user’s face and eyes using Haar Cascade Classifier
on grayscale image. Then random KLT features within the eye and nose regions are initializes
and classified as left ocular, right ocular or non‐ocular. These features are being tracked by KLT
tracker. Tracking is reinitialized in regular intervals or in case of loss of many feature points.
After that the average displacement is computed separately for three groups of points. Finally,
the difference between the left or right ocular and non‐ocular movement displacements is
computed. If this difference exceeds a threshold value, a movement within the eye region is
anticipated [10].
1.3.3IR(Infrared)sensors
Another common method of eyeblink recording utilizes infrared (IR) photoelectric sensors.
This approach measures IR light reflected from the surface of the eye. A typical IR eyeblink
measurement device consists of an IR light emitting diode (LED), which illuminates the eye
surface, paired with an IR photodiode that detects IR light reflected back from the eye [11].
An ideal IR eyeblink detector should have several important properties. To detect the full
range of eyelid movement, the IR LED should completely illuminate the surface of the fully
opened eye, and in addition, the field‐of‐view of the IR photodiode should encompass the
whole eye area. Some currently used detectors rely on commercial proximity sensors that not
only must be positioned close to the eye but also emit a narrow IR beam resulting in incomplete
coverage of the full range of eyelid motion. Google glass implements an infrared proximity
sensor facing the users’ eye that can be used for blink detection shown in Figure 1.2.
Fig
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15
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16
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17
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18
∆ 1.2
1.3
1.4
Note that this equation only works if the relative velocity of the receiver, is towards
the source. If the motion is away from the source, the relative velocity would be in the opposite
direction and the equation would become:
1.5
The two equations are usually combined and expressed as:
1.6
If the source is moving towards the receiver, the effect is slightly different. The spacing
between the successive wave fronts would be less as seen in the figure 1.5. This would be
expressed as:
T
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o calculate t
Note that this
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19
ve source an
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nd receiver.
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20
1.10
When combined with the previous result, the equation would be expressed as:
∓
1.11
Notice that this time, the plus/minus symbol is inverted because the sign on top is to be
used for relative motion of the source towards the receiver.
By combining the previous results, we can derive one equation to use as the Doppler Equation.
This is usually expressed as:
∓
1.12
It must be noticed that the quantities for the velocity of the receiver, , and the velocity
of the source, , are only the magnitudes of the relative velocities in (or along) the LOS. In
other words, the component of the velocity of the source and the receiver, that are
perpendicular to the LOS do not change the received frequency. Secondly, the top sign in the
numerator and the denominator are the sign convention to be used when the relative velocities
are towards the other. If the source were moving towards the receiver, the sign to use in the
denominator would be the minus sign. If the source were moving away from the receiver, the
sign to use would be the plus sign.
1.3.4.2EyeblinkmeasurementusingDopplerEffect
By the time of writing this thesis there are only two related works that explain eyblink
detection using Doppler effect:
One work was conducted by Kamil et al. in 2012. The research was carried out in order
to measure the level of drowsiness in drivers. They deployed a multiple receiver microwave
Doppler radar. The sensor was consisted of a synthesized signal source with the output
frequency of 9 GHz. The system implemented a single side band SSB modulation and a
quadrature modulator structure. The modulation frequency was 1 KHz and the antenna was a
16‐element, 4×4array. The receiver was consisted of 8 channels that integrated IQ mixers [3].
21
In order to find the signal’s characteristics they implemented several methods and they
reported that:
Through frequency analysis, FFT, of the recorded eyeblink signal, the frequency related
to blinking is completely covered by the spectrum of general head movement signal.
Implementing Continuous Wavelet Transform (CWT) they reached the same results as
FFT.
They could not find any useful information in signal phase extraction.
Finally they selected time domain analysis in order to reach the eyeblink signal and
introduced a separated wave form for eyeblink detected by Doppler sensor.
As the signal detection procedure after passing the measured signal and signal de‐
noising procedure using multilevel discrete wavelet decomposition, they achieved a signal
containing several sinusoidal waveforms. In the next step, they calculated the envelope of the
represented signal by using a simple rectangular filter. Finally, they determined a threshold and
when the amplitude of the envelope exceeded the threshold they considered the signal as a
blink. Unfortunately, they didn’t provide detailed information for their experimental method
and also the frequency characteristics of the eyeblink signal remains undetermined.
Another study aimed to detect eyeblink using Doppler sensor was conducted by
Youngwook Kim in 2015. He performed several measurements with/without the noise caused
by human movement when the sensor was placed near the eyes. Then he analyzed the Doppler
signal in the joint time–frequency domain and suggested that the Doppler frequency produced
by eye blinking was approximately 115 Hz. Furthermore, he proposed that unconscious and
conscious eye blinking exhibited different Doppler characteristics and deployed Principal
Component Analysis In order to classify these characteristics. Then he introduced a method in
which conscious and unconscious eyeblink can be distinguished by multiplying truncated
eigenvectors with an image of eye blinking [12].
22
Kim implemented PCA method as an image processing method of target recognition for
distinguishing the conscious from unconscious blinking and also noise. He represented the
sorted eigenvalues, in which two eigenvalues contain more than 97% of the total energy and
the reconstructed two‐dimensional images from the one dimensional eigenvectors that
corresponded to the highest eigenvalues. He claimed that the first eigenvector was similar to
the image of conscious eye blinking, and the second eigenvector was analogous to that of the
unconscious eye blinking.
1.4Aplication
Eyeblink detection may find many applications in a wide variety of the fields. For
instance investigation of eye‐blinking activity can have applications in the detection of the
unconsciousness of pilots and the drowsiness of drivers. One study was conducted in 2013 by
Genis et al. in order to investigate connection between changes in blinking and changes in a
driving‐ task difficulty. They implemented a camera located inside a car for blink detection.
They reported that changes in task difficulty follow fluctuation in eyeblink frequency [14].
Another study was performed in 1998 in order to measure the Physiological workload
reactions to increasing levels of task difficulty. They measured blink intervals when changing a
pilot‐task difficulty and they observed that eyeblink interval fluctuates with task difficulty level
and this feature can be used for measuring the mental workload level allocated to each task.
Furthermore, eyeblink can be used as a simple communication (yes/no) for soldiers in the
battlefield and patients with spiral‐cord injuries, where normal verbal communication is not
possible. In addition, eye blinking can serve as a communication methodology such as human
input into a computer. For example, eye blinking has also been studied for the development of
a head set type computer mouse designed for the disabled [15].
23
1.5Thesisorganization
Chapter 1: Introduction
We discuss about the background, application, motivation and related works on eyeblink
detection in this chapter.
Chapter 2: Concept
In this chapter we introduce our concept about making a glass for eyeblink detection.
Chapter 3: Measurement system
We introduce the measurement method and system for this study and also we give detail
information about experimental items.
Chapter 4: Analysis method and results
In this chapter we represent our analysis method that is based on PCA method. We also show
our experimental results in this chapter.
Chapter 5: Conclusion
The conclusion of this study has been discussed in this chapter. We also have an overlook on
the future part of this study.
D
objective
to measu
by huma
detection
This Acce
The follo
protectio
Developing a
e of this thes
ure the drow
an errors. W
n and also w
elerometer p
owing we wi
on glass w
a glass whic
sis. This glas
wsiness stat
We deployed
we used an
plays a part i
Figure
ill introduce
without any
Chapte
ch is able to
s can measu
e in drivers
d a Doppler
n accelerom
in the analys
2.1 the con
e each part o
metal par
24
er2Con
o detect ey
ure the eyeb
and pilots a
r sensor, att
eter for hea
sis and meas
cept of the d
of the glass
rt which m
ncept
yeblink in hu
blink in diver
and therefo
tached to a
ad and bod
surements.
designed gla
. Where, th
may cause
uman subje
rse condition
re prevent a
pair of glas
y movemen
Figure 2.1 d
ass.
e glass itsel
some dist
ects is the m
ns. It can be
accidents ca
sses for eye
nt measurem
epicts the gl
lf is a plastic
turbance in
major
used
aused
eblink
ment.
lass.
c eye
n the
electrom
the expe
2
F
power Pu
is 5.8 GH
antenna
output (I
by Samra
output, i
magnetic wav
rimental me
2.1Dopp
igure 2.2 sh
ulsed Dopple
Hz which co
with a 60
& Q) and it
akhsh Co. In
.e.
ves produce
easurements
plerSens
ows the Do
er Radar (PD
orresponds
degree con
responds to
this study w
across al
ed by the Do
s.
sor
ppler senso
DR) and has
to a wavele
nical coverag
o radial velo
we calculate
ll the study.
Figure 2.2
25
oppler senso
r employed
a detection
ength of ab
ge pattern.
ocities betwe
d the amplit
2 Doppler se
or and there
in our expe
range up to
bout 5.2 cm
The outpu
een 2.6 cm/s
tude of the
ensor.
efore conseq
eriment. The
o 10 m. the c
. it has an
t is a Cohe
s and 2.6 m/
Doppler sen
quences fau
e sensor is a
center frequ
on‐board d
erent quadr
/s, manufact
nsor’s quadr
ults in
a low‐
uency
dipole
ature
tured
ature
T
W
and λ is t
2
T
power, c
accelerat
gravity in
or vibrat
(
he relation b
Where is t
the wavelen
2.2Accel
he Accelero
complete 3‐
tion with a m
n tilt‐sensing
ion. The sen
) fo
between rad
the Doppler
gth at the ce
leromete
ometer is AD
axis acceler
minimum fu
g application
nsitivity of s
or this study
dial velocity
2
r frequency,
enter freque
er
DXL335 sho
rometer wit
ull‐scale rang
ns, as well as
sensor is 300
.
Figure 2.3
26
and Doppler
is the rad
ency.
own in figur
th signal con
ge of ±3 g. It
s dynamic ac
0 mV/g. we
3 Accelerom
r frequency
2.1
dial compon
re 2.3. The
nditioned vo
t can measu
cceleration r
calculated
meter.
is:
nent of the
sensor is a
oltage outp
ure the stati
resulting from
the amplitu
target’s velo
small, thin
puts. It mea
ic accelerati
m motion, s
de of these
ocity,
, low
sures
on of
hock,
axes
Figure 3
eyeblink
conducte
A
signals to
.1 depicts t
detection, a
ed by placing
All recording
o digital by t
Chapte
the experim
and accelero
g three elect
F
gs took plac
he A/D boar
er3Mea
mental syste
ometer for h
trodes place
Figure 3.1 Ex
ce using a p
rd.
27
asurem
em. This sys
head and bo
ed on the sub
xperimental
personal co
mentsys
stem consis
ody measure
bjects face a
l system.
omputer aft
stem
sts of a Do
ement and a
and using a m
er convertin
ppler senso
an EOG reco
multi amplifi
ng the anal
or for
ording
ier.
logue
T
and upp
electrode
to verify
MULTI A
paced on
electrode
resistanc
0.3 Sec, H
3.1E
he EOG reco
per sites of
e placed ove
the blinking
AMPIFIER MA
n the upper
es the elect
ce and bette
HFF = 100 Hz
EOGreco
ording for t
the orbicul
er the forehe
g signals co
A1000‐DIGIT
and lower s
rodes the s
er measurem
z, Sensitivity
ording
he eyeblink
laris oculi m
ead as the g
llected by t
TECS. As we
sites of the
urface of th
ment of the
y = 500 μV, t
Figure 3.
28
took place
muscle (abo
ground elect
he Doppler
e can see th
orbicularis o
he skin was
EOG. The s
he reference
2 EOG recor
by placing t
ove and und
trode, repres
sensor the
he positive a
oculi, respe
cleaned ca
etting for th
e setting wa
rding.
two electro
der the righ
sented in fig
EOG were r
and negative
ctively. Befo
refully for r
he Multi am
as standard.
des to the l
ht eye) and
gure 3.2. In o
recorded us
e electrodes
ore attachin
reducing the
mplifier was:
ower
d one
order
sing a
s was
g the
e skin
TC =
Figure 3.
D
frequenc
O
1‐ W
2‐ W
3 shows the
Doppler and
cy of 1000 H
Our experime
When the Do
When the Do
Figure 3.4 E
e MULTI AMP
Figure 3
Accelerome
z by using an
ent was cond
oppler senso
oppler senso
Experimenta
PIFIER MA10
3.3 MULTI AM
eter sensors
n AD board (
ducted in tw
r was fixed t
r was attach
al setup whe
29
000‐DIGITEC
MPIFIER MA
s recordings
(TRM‐7100)
wo parts:
to a stand, s
hed to a pair
en the Dopp
CS.
A1000‐DIGIT
s were carr
manufactur
hown in figu
r of glasses, d
ler sensor w
ECS.
ried out tho
red by Interf
ure 3.4.
depicted in f
was fixed to a
orough a sa
face.
figure3.5.
a stand.
ample
Figure
In
angles: ‐4
eye and +
Doppler
Figure 3
e 3.5 Experim
n part 1, the
45 degree (u
+45 degree
sensor was 5
.6 three diff
mental setu
Doppler sig
under the ey
(above the e
5 cm.
ferent angleson a f
p when the
nal produce
ye), 0 degree
eye), shown
s for eyeblinixture and h
30
Doppler sen
ed by eyblink
e (horizontal
in figure 3.6
nk detection head and bod
nsor was atta
k was measu
l to the eye o
6. The distan
when the Ddy were fixe
ached to a p
ured from th
or at the sam
nce between
Doppler sensed.
pair of glasse
hree differen
me level wit
n the eye and
or was mou
es.
nt
h the
d
nted
In
eye and
was 0° ac
Figure 3
T
1‐ W
2‐ W
n part 2, the
Doppler sen
cross all mea
3.7eyeblink d
hen the mea
When subject
When subject
e Doppler Se
nsor was 5 c
asurements,
detection wh
asurement w
ts sat in fron
ts performe
ensor was a
cm. In this p
, depicted in
hen when th
was conduct
nt of a perso
d a walking
31
ttached to t
part the ang
n figure 3.7.
he Doppler s
ed in two co
onal compute
task.
the glass an
gle between
sensor was a
onditions:
er and perfo
nd the distan
the eye and
attached to a
ormed a rou
nce betwee
d Doppler se
a pair of glas
tine task.
n the
ensor
sses.
A
Doppler s
order to d
signal rec
steady an
and body
collected
eyeblink s
frequency
was perfo
analysis w
Cha
s the proced
sensor and E
define the do
corded by Do
d the subject
y movement u
Doppler sign
signal from th
y and calculat
ormed by de
was conducted
apter4
dure of the
OG when th
ominant frequ
oppler signal
ts could able
using the acc
nals, contami
hem. Finally,
ted the mean
efining a thr
d using MATL
Fi
Analys
eyeblink det
e head and
uency associa
during perfo
to move thei
celerometer a
nated with t
we selected t
n of them as t
eshold value
LAB software
igure 4.1 Eye
32
ismeth
tection, first,
body were s
ated with eac
rming two ta
r heads and b
at this stage.
he head and
the principal
the reconstru
e. Figure 4.1
.
eblink detec
hodand
we recorde
steady. Then
ch subject. N
asks in which
bodies arbitra
After that, w
body movem
components
ucted eyeblink
depicts the
ction flow.
dresult
ed and verifi
we analyzed
ext, we meas
h the head a
ary. We also
we applied P
ment, in orde
which had th
k signal. The
eyeblink de
s
ed eyeblink
d obtained da
sured the eye
nd body wer
recorded the
CA method t
er to separat
he same dom
eyeblink dete
etection flow
using
ata in
eblink
re not
e head
to the
te the
minant
ection
w. The
4
In
head on
the EOG
procedur
each me
after the
represen
recorded
Fo
points fo
consciou
figure 4.4
4.1resul
n this part w
a fixture. Th
signals in
re for signal
asurement a
e global max
nts the EOG
d by the Dop
ollowing the
or each eye
s and unco
4 shows the
tswhen
we measured
he EOG signa
order to co
l detection
and then we
ximum of th
G recording
ppler sensor.
F
e fact that th
blink sample
nscious blin
correspond
thesub
d both EOG
al was passe
onfirm each
first we calc
e cropped h
e EOG, this
and the r
Figure 4.2 Ex
he sampling
e. We colle
nking. Figur
ing frequenc
33
ject’she
and Dopple
d through a
h eyeblink' d
culated the
alf a second
is shown in
red signal r
xperimental
g frequency
cted 100 sa
re 4.3 repre
cy spectrum
eadandb
er signal wh
low pass filt
detection u
global max
d of recorde
figure 4.2.
represents t
Protocol.
was 1 KHz t
amples for e
esents a sam
m.
bodywa
hen the subj
ter. In fact w
sing Dopple
ximum of th
ed Doppler s
In this figur
the original
therefore we
each measu
mple of rec
assteady
ects placed
we have reco
er signal. As
e EOG signa
signal before
re the blue s
l eyeblink s
e had 1000
rement for
cording EOG
y
their
orded
s the
al for
e and
signal
signal
data‐
both
G and
F
signal is
the origi
between
are unde
rom the Pow
located in t
nal recorded
the eye an
er 10 Hz.
Fig
Figur
wer spectru
he frequenc
d conscious
d Doppler s
ure 4.3 a sa
e 4.4 Spectr
m of the EO
cies up to 10
eyeblink an
ensor was 0
34
mple of reco
rum of the re
OG signal we
0 Hz. Figure
nd its power
0°. As we ca
orded EOG.
ecorded EOG
e can see th
e 4.5 and fig
r spectrum
n see most
G.
at most of t
gure 4.6 show
respectively
of the powe
the power o
w one samp
y when the a
erful freque
of the
ple of
angle
encies
Fig
F
and its p
0°. As we
Figure
gure 4.6 Spe
igure 4.7 an
ower spectr
e can see mo
4.5 A samp
ectrum of th
nd figure 4.8
rum respect
ost of the po
le conscious
e Sample co
8 depicts the
ively when t
owerful frequ
35
s eyeblink de
onscious eye
e case for t
the angle be
uencies are
etected by D
eblink detect
he original r
etween the
under 10 Hz
Deppler sens
ted by Depp
recorded co
eye and Do
z.
sor.
ler sensor.
onscious eye
ppler senso
eblink
r was
Figu
A
waveform
unconsci
form and
each mea
Figure 4
ure 4.8 Spec
As a result
ms and it
ous eyeblin
d their frequ
asurement:
4.7 A sample
ctrum of the
we can se
can be gre
k. To better
uency charac
e unconsciou
Sample unc
ee that con
eatly used
r understand
cteristics we
36
us eyeblink d
conscious ey
nscious and
in order t
ding the con
e calculated
detected by
yeblink detec
d unconscio
o distinguis
nscious and
the arithme
Deppler sen
cted by Dep
ous eyeblink
sh between
d unconsciou
etic mean of
nsor.
pler sensor.
k have diffe
n conscious
us eyeblink
f 100 sample
erent
and
wave
es for
F
blinking w
igure 4.9 to
when the an
Fi
o figure 4.1
ngle between
Figure 4.9 M
gure 4.10 M
1100
10 represent
n the eye an
Mean of 100
Mean of 100
37
t the result
nd Doppler s
0 samples of
samples of u
4.1
ts for both
sensor is 0°.
conscious e
unconscious
conscious a
eyeblink.
s eyeblink.
and uncons
scious
F
in figure
selected
A
unconsci
of subjec
average
opening
proposed
igures 4.11 a
4.8 and figu
those frequ
Figure 4
Figure 4.
As a result
ous blinking
cts and may
speed of ey
phase, res
d frequency
and Figure 4
re 4.9. For b
encies less t
4.11 Spectru
.12 Spectrum
we can se
g are near 2
vary for eac
elid has bee
pectively. T
range assoc
4.12 represen
better analyz
than 20 Hz.
um for mean
m for mean o
ee that the
Hz. Howeve
ch individua
en suggested
Thus as we
ciated with e
38
nts the pow
zing the freq
n of 100 sam
of 100 samp
e dominant
er this freque
l. As we intr
d [52~138 m
expected
eyelid speed
er spectrum
quency featu
mples of cons
ples of uncon
t frequencie
ency depend
roduced in t
mm/s] and [2
the obtaine
[1~5.4 Hz].
m of the repr
ures of the e
scious eyebl
nscious eyeb
es for both
ds only to th
he previous
24~47 mm/s
ed frequenc
esented sign
eyeblink we h
ink.
blink.
h conscious
he blinking s
chapter tha
s] for closing
cy is within
nals
have
and
speed
at the
g and
n the
F
from thre
respectiv
Figure
A
detection
condition
best dete
this posit
igure 4.13 a
ee different
vely.
4.13 Experimcen
As we can s
n angle bet
n that the se
ectable angl
tion.
nd Figure 4.
angles; ‐45°
mental resulnter, (b) 0 de
ee in this f
ween ‐45°
ensor is fixed
le is 0° beca
14 show the
°, 0°, 45°; for
lts when eyeegree and (c
figure, obvio
to +45°. Th
d and the he
use the rad
39
e measured D
r both consc
eblink was co) +45 degree
ously, the e
is means th
ead is movin
ial velocity o
Doppler sign
cious and un
onscious: (ae above the
eyblink is w
hat eyeblink
ng upward a
of the eyelid
nal produced
conscious ey
) ‐45 degreeeye center.
well detectab
k detection
nd downwa
d has the m
d by eyeblin
yeblink,
e below the e
ble from a
is practical
rd. Howeve
aximum val
k
eye
wide
in a
r, the
ue at
Figure 4deg
In
between
and unco
blinking
blinking t
s
In
1. W
in
4.14 Experimgree, below
n this figure
‐45° to +45
onscious blin
is stronger
the eyelid m
4.2rsteady
n this part w
When the su
n this case th
mental resultthe eye cen
we also se
5° and the b
nking have d
than that o
movement is
resultsw
we measured
bject sat in
he subject w
ts when eyeter, (b) 0 de
e that the e
best detecta
different wa
of unconscio
accompanie
whenthe
the eyeblin
front of a p
was able to m
40
blink was unegree and (c)
eyblink is w
ble angle is
aveforms an
ous blinking
ed with the m
esubjec
k signal for t
ersonal com
move his hea
nconscious: ) +45 degree
well detectab
0°. But we
nd also the d
g due to the
muscle mov
ct’shead
two conditio
mputer and p
ad arbitrary.
(a) measuree above the
ble from a w
observed th
detected sig
e fact that
ements arou
andbod
ons:
performed a
ed data fromeye center.
wide angle r
hat the cons
gnal of cons
in the cons
und the eye.
dywasn
an everyday
m ‐45
range
scious
scious
scious
.
not
task,
2. W
In
consciou
samples
Figure 4fron
A
the head
distorted
the signa
body mo
previous
method
separatio
of ICA on
method a
When the sub
n this part d
s eyeblink.
for both con
4.15 The aritnt of the pers
As we can se
d and body m
d signal. The
al thorough
ovements h
works by s
for signal se
on purposes
n the signal
and finally w
bject perform
due to the m
Figure 4.15
nditions.
hmetic measonal compu
ee the measu
movement a
ere are sever
a low pass o
ave similar
some autho
eparation, IC
s. We exami
separation
we selected P
med a walki
more powe
5 and 4.16
n of 100 samuter and perperformed
ured signals
and we need
ral proposed
or band pas
frequency
ors, using co
CA (Indepen
ned ICA met
procedure a
PCA method
41
ng task.
rful signal in
show the
mples of Doprformed a rod the walkin
by the Dop
d to find a w
d ways for s
ss filter, but
component
ommon filte
dent Compo
thod in our
and therefor
d.
n conscious
arithmetic
ppler signalsoutine task ag task.
ppler sensor
way to separ
ignal separa
due to fact
ts and as it
ers seems a
onent Analy
study, but d
re poor resu
s blinking w
mean of th
s: (a) when tand (b) when
are comple
rate eyeblin
ation. One o
that eyebli
t has been
almost hope
ysis) is widel
due to the i
ults, we tried
e only study
he 100 colle
he subject sn the subject
etely distorte
k signal from
of them is to
nk and head
reported in
eless. As ano
ly used for s
nefficient im
d to find ano
y the
ected
at in t
ed by
m the
o pass
d and
n the
other
signal
mpact
other
B
the powe
W
except fr
In order
accelerom
Accelero
efore apply
er spectrum
Figure 4.1
We can see
requencies n
to better un
meter. Figu
meter and f
ing PCA met
of the recor
16 The powe
that in figu
near 2 Hz the
nderstanding
ure 4.17 sh
igure 4.18 re
thod, in ord
rded signals
er spectrum
re 4.16 (a),
e signal has
g this featur
hows the r
epresents its
42
der to study
. Figure 4.16
of the signa
frequencies
most of its p
re we also m
recorded he
s power spe
frequency c
6 depict the
als represent
s from 2 to
power in fre
measured th
ead and bo
ctrum.
characteristi
results.
ted in figure
o 4 Hz and i
equencies be
he body mov
ody movem
ics we calcu
e 4.14.
in figure 4.1
etween 5 to
vement usin
ments using
ulated
16(b),
7 Hz.
g the
g the
Figucomput
Figure
F
those fre
Now that
section w
PCA met
re 4.17 The er and perfo
e 4.18 The P
rom the fre
equencies be
t we know w
we have trie
hod.
acceleromeormed a rou
Power Spect
quency cha
etween 10 t
which freque
ed to separa
eter signals: (tine task an
rum of the s
racteristics o
to 13 Hz are
encies conta
ate the eyeb
43
(a) when thed (b) when t
signals represignals).
of the head
the domina
ain the most
blink signal f
e subject satthe subject p
esented in fig
and body m
ant frequenc
t powerful p
from the or
t in front of tperformed t
gure 4.16 (A
movements
cy for this p
part of the s
iginal measu
the personahe walking t
Acceleromete
we can see
articular sub
ignal, in the
ured signal
l task.
er
e that
bject.
e next
using
44
4.3 Applying PCA for signal separation
In this section in order to extract the principal components of the original signals we
implemented the Principal Component Analysis (PCA) [13]. In the previous parts each original
signal was divided into 100 datasets of 1000 point length (or one seconds), thus we obtained
100 samples of eyeblink signals for each measurement. Then we arranged these samples into
matrices so that the size of each matrix was 100×1000. Then we calculated the PCA of each
matrix.
X , ⋯ ,
⋮ ⋱ ⋮, ⋯ ,
4.1
So that:
.
In which:
Uistheleftsingularvectors
Then we calculated the principal components of the matrix, X:
E S 4.3
In which E represents the principal components.
Figure 4.19 represents the first principal components for the measured signal when the
head and body were steady when the angle between the eye and Doppler sensor was 0°.
Figure 4
A
same as
because
the inver
A
first we s
that the
compone
the recon
4.19 First prthe cente
As we can se
obtained d
of axis rotat
rse of repres
As the recons
selected the
dominant
ent that hav
nstructed ey
incipal compr of eye is 0°
ee the first p
ata using th
tions during
sented signa
struction pro
e first to sixt
frequency o
e dominant
yeblink signa
ponents of t°: (a) conscio
principal com
he arithmeti
PCA proced
l in figure 4.
ocedure for
th principal c
of eyeblink
frequency a
al. Figure 4.2
45
he signals wous blinking
mponents of
ic mean of t
dure, the obt
10.
the case wh
components
is near 2
at 2 Hz and t
20 and figur
when the angand (b) unc
f each meas
the signals
tained signa
hen the head
s of each sig
Hz, we cho
then we calc
re 4.21 show
gle betweenonscious bli
sured signal
in the previ
al for uncons
d and body
gnal and con
ose those se
culated the
w the power
the sensor nking.
s are exactl
ious section
scious eyebl
were not ste
nsidering the
elected prin
mean of the
r spectrum o
and
y the
n. But
ink is
eady,
e fact
ncipal
em as
of the
first to
Figure 4
In
represen
feature o
and yell
frequenc
principal
eyeblink.
to other
separatio
mean of
sixth princi
4.20 The powthe subject
n figure 4.2
nts the Powe
of the signal
ow lines as
cy at 2 Hz an
component
. The other p
movements
on and we s
them as the
ipal compo
wer spectrut sat in front
20, the hor
er of the sig
we selected
ssociated w
nd from the
ts which ha
principal com
s such as he
elected the
e reconstruct
nents for b
m of the firsof a person
rizontal axis
gnal at each
d those freq
with the firs
experimenta
ave the mos
mponents ha
ead and bod
first to third
ted signal as
46
both workin
st to sixth pral computer
s represents
frequency.
uencies up t
st to third
al results in
st of the po
ave differen
dy movemen
d principal c
s eyeblink.
ng with co
rincipal comr and perfor
s the frequ
To better u
to 6 Hz. As w
principal c
the previou
ower at 2 H
t dominant
nts. Thus we
components
mputer and
ponents of tmed a routin
uency and t
understandin
we can see,
omponents
us section, w
z as the rep
frequencies
e used this f
s and then w
d walking t
the signal wne task.
the vertical
ng the frequ
the blue, or
have dom
we consider t
presentative
s and they be
feature for s
we calculate
tasks.
hen
l axis
uency
range
inant
those
es for
elong
signal
d the
Figure 4
F
the walk
represen
understa
6 Hz. As
compone
other pri
before, w
for eyebl
4.21 The pow
igure 4.21 r
ing task. In t
nts the Pow
anding the fr
we can see
ents have do
incipal comp
we selected
link. Figure 4
wer spectruthe
represents t
this figure, th
wer of the
requency ch
e the blue a
ominant freq
ponents are
these signa
4.22 and figu
m of the firse subject per
he power sp
he horizonta
signal at
haracteristics
and purple
quency at 2
e the represe
ls and calcu
ure 4.23 rep
47
st to sixth prrformed a w
pectrum of
al axis repre
each frequ
s of the sign
lines associa
Hz and they
entatives of
lated the m
resent the re
rincipal comwalking task.
the signal w
sents the fre
uency and
nal we select
ated with th
y are explai
f other mov
ean of them
esults:
ponents of t
when the su
equency and
like figure
ted those fr
he first and
ning the eye
ements. The
m as the reco
the signal w
ubject perfo
d the vertica
4.20 to b
requencies b
d fourth prin
eblink signal
erefore as it
onstructed s
hen
rmed
al axis
better
below
ncipal
l. The
t said
signal
Figure 4
In
the norm
measure
the wave
blinking
task, we
due to th
toward le
and if th
value for
4.22 Reconst
n figures 4.2
malized ampl
d by Dopple
eform and a
signal when
selected th
he phase sh
eft or right.
e selected s
r this subject
tructed blink
22, the horiz
litude of the
er sensor, oc
also the tim
n the subject
e largest wa
ift induced
As the proc
signal exceed
t was 0.4 V.
king signal wand perform
zontal axis r
e signal. Refe
ccurs at the
me when it o
t sat in fron
ave form be
by the signa
cedure of ey
ds this thres
Figure 4.24 d
48
when the subming a routin
epresents th
erring back t
time near 0
occurs, in fig
nt of a perso
etween 0.4 t
al separation
yeblink dete
shold value,
depicts the e
bject sat in frne task.
he time and
to figure 4.2
0.5 s. There
gure 4.22, w
onal comput
to 0.9 s as t
n procedure
ection first w
the eyeblin
eyeblink det
ront of a per
d the vertica
2, the peak o
efore, consid
which is ass
ter and perf
the eyeblink
e the signal
we defined a
nk is detecte
tection flow
rsonal comp
al axis repre
of eyeblink s
dering the si
ociated with
formed a ro
k signal. How
may shift sli
a threshold v
ed. The thres
.
puter
sents
ignal,
ize of
h the
utine
wever
ightly
value
shold
Figure 4.
In
the norm
and also
when the
1 s as th
value wa
23 Reconstr
n figure 4.23
malized amp
the time w
e subject pe
e eyeblink s
s 0.4 V. Figu
ructed blinki
3, the horizo
plitude of th
when it occu
rformed a w
signal. The p
ure 4.25 show
ng signal wh
ontal axis re
e signal. Lik
urs, in figure
walking task,
procedure o
ws the eybli
49
hen the subj
epresents th
ke figure 4.2
e 4.23, whic
we selected
of eyeblink d
nk detection
ject perform
he time and
22 considerin
ch is associa
d the largest
detection is
n flow for th
med a walkin
the vertica
ng the size o
ated with th
t wave form
the same a
he walking ta
g task.
al axis repre
of the wave
he blinking s
between 0.
nd the thres
ask:
sents
eform
signal
52 to
shold
Figure 4
Figure 4.
A
waveform
4.24 Eyeblink
25 Eyeblink
As we can s
ms exceeded
k detection p
detection p
see in thes
d the thresh
procedure w
and perform
rocedure wh
e figures th
old value.
50
when the sub
ming a routin
hen the subj
he eyeblink
bject sat in fr
ne task.
ject perform
k occur bec
ront of a per
med a walkin
cause the p
rsonal comp
ng task.
peak of sele
puter
ected
F
dominan
0.4 V.
Figure 4the
In
represen
lines asso
Thus we
selected
subject s
igure 4.26 t
nt frequency
4.26 The powe second sub
n figure 4.2
nts the Powe
ociated with
selected th
signals as t
at in front o
to 4.29 dep
for the seco
wer spectrubject sat in fr
26, the hor
er of the sig
h the first to
e first to th
he reconstr
of a personal
icts the res
ond subject
m of the firsront of a per
rizontal axis
gnal at each
o third princ
hird principa
ucted signal
computer a
51
ult for the
was also 2 H
st to sixth prrsonal comp
s represents
frequency.
ipal compon
l componen
l for eyeblin
and perform
second sub
Hz. The thre
rincipal comuter and pe
s the frequ
As we can
nents have d
nts and then
nk during pe
med a routine
bject. We ob
shold value
ponents of trformed a ro
uency and t
the blue, or
dominant fr
n we calcula
erforming th
e task.
bserved tha
was also de
the signal woutine task.
the vertical
range and y
equency at
ated the me
he task whe
t the
efined
hen
l axis
ellow
2 Hz.
an of
n the
Figure 4
In
the norm
the first
the mean
4.27 The pow
n figures 4.2
malized amp
and second
n of them as
wer spectruthe sec
27, the horiz
litude of the
principal co
s the reconst
m of the firscond subject
zontal axis r
e signal. In t
omponents
tructed signa
52
st to sixth prt performed
epresents th
his figure th
have domin
al of eyeblin
rincipal coma walking ta
he time and
he blue and
nant frequen
nk for the wa
ponents of task.
d the vertica
orange lines
ncy at 2Hz a
alking task.
the signal w
al axis repre
s associated
and thus we
hen
sents
d with
took
Figure
Figure 4.
In
exceed t
in figure
the signa
4.28 Eyeblin
29 Eyeblink
n figures 4.2
he threshold
4.29 it is bet
al separation
nk detection
comp
detection p
28 and 4.29
d value. In f
tween 0.3 to
n method the
n procedure
puter and pe
rocedure wh
9 eyeblink o
igure 4.28 t
o 0.82 s. As w
e signals are
53
when the se
erforming a
hen the seco
occurs when
he selected
we can see d
e shifted to r
econd subjec
routine task
ond subject
n the select
eyblink sign
due to the p
right and left
ct sat in fron
k.
performed a
ted wavefor
nal is betwee
phase shift d
t, respective
nt of a perso
a walking tas
rms for eye
en 0.5 to 1 s
uring perfor
ely.
onal
sk.
eblink
s and
rming
54
Chapter5Conclusionandfuturework
In this thesis, we have introduced a glass which can be used for diverse applications
such as detecting driver’s and pilot’s drowsiness and also for measuring several
psychophysiological factors. Because it is proposed that eyeblink is a representative for higher
nervous processes and it can be used for measuring the level of the cognitive and mental
workload during performing tasks. We also introduced an experimental method for eyenlink
detection in which we measured eyeblink for both cases when the head and body of the
subjects were steady and unsteady. First, we analyzed the frequency characteristics of the
eyeblink when the head and body was steady and then we tried to separate the eyeblink signal
from the measured signal which was contaminated with the head and body movement using
PCA method. We observed that eyeblink measurement is practical when the Doppler sensor
was placed in front of the eye, 5 cm away from it, and the angle between the eye and the
sensor was between ‐45° to 45°. The best detectable angle was 0° because the radial velocity at
this position has the maximum value. Furthermore, from our experimental results we showed
that the Doppler frequency of eyeblink is near 2Hz and this frequency is equivalent to the
propose speed of blinking which are [52~138 mm/s] and [24~47 mm/s] for the closing and
opening phases, respectively. This frequency may vary from subject to subject. In addition we
proposed that the boundary between conscious blinking and unconscious blinking is achievable
because the waveforms of the conscious and unconscious blinking are different. Finally, we
introduced a method to separate the blinking signal from a signal that had been mixed with
head and body movements. This method addresses the advantages of the PCA analysis for
pattern recognition and also eyeblink detection. For the feature work we plan to perform the
eyeblink detection and also distinguishing the type of it, conscious and unconscious, by using an
55
appropriate neural network. The results of this work can also be used for the neural network
training processes.
56
Acknowledgments
I wish to dedicate this thesis to my advisor, Professor Masafumi Uchida for his kind, unstinting
and endless supports during my research periods at the University of Electro‐Communications. I
also want to thank my angelic friends, Ali Mokhtari, his sister, Nazila, and his wife, Negar, for
their warm supports during my life in Japan. Finally, I need to thank Mr. Inoue for his
unswerving supports during my academic life at in japan.
57
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utilizing microwave Doppler sensor, in Proc. MIKON, vol. 2, 623–626
[4] Steven B Ryan, Krystal L Detweiler, Kyle H Holland et al. (2006), A long‐range, wide field‐
of‐view infrared eyeblink detector, Journal of Neuroscience Methods 152, 74–82
[5] Kwon K, Shipley R J, Edirisinghe M et al. (2013), High‐speed camera characterization of
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59
Publicationsandconferences
[1] Amir Maleki, Yuki Oshima, Akio Nozawa, Tota Mizuno, and Masafumi Uchida, Analysis of
Fluctuation in Repeated Handwriting Based on Psychophysiological Factors,7th International
Conference on Unsolved Problems on Noise, 21 (2015)
[2] Amir Maleki and Masafumi Uchida, Non‐contact measurement of eyeblink by using
Doppler sensor, AROB 22nd, 2017
[3] Ryo Hasegawa, Amir Maleki, Masafumi Uchida, Evaluation of Body Sway Using Tactile
Stimuli on the Body Trunk, IEEJ Trans., EIS, 136(8), 1135‐1141, Aug 2016