Signal Processing - November 2016 - 33

assessed by the CISPR25, ISO11452, ISO7637, and ISO10605
may cause a malfunction of the DSM system. Therefore, it is
standards, respectively.
essential to design an analog signal processing circuit with a
consideration of EMC to protect the DSM system from noise
and interference from the ECUs.
Conclusions
Therefore, in this section, we investigate the four EMCs,
Traffic accidents are one of the most serious problems
i.e., electromagnetic interference (EMI), electromagnetic susthreatening the safety of automobile users. As reported in
ceptibility (EMS), surge, electrostatic discharge (ESD), that
[4], the driver's incapacitation due to drowsiness and fatigue
need to be considered when applying a DSM system using
is one of the major causes resulting in fatal traffic acciphysiological signals to the vehicles.
dents. The DSM system is an innovative
EMI is the electromagnetic wave emitsolution that can dramatically reduce trafThe DSM system is an
ted from the ECU. As the electromagnetic
fic accidents caused by the driver's incainnovative solution
waves can cause errors in other electronic
pacitation [35]. Therefore, it is essential
that can dramatically
devices, ECUs should be designed not
to develop DSM systems using vision senreduce traffic accidents
to emit electromagnetic waves over the
sors and SASs or using the driver's physicaused by the driver's
levels approved by the standard. In generological signals such as ECG or PPG. The
incapacitation.
al, EMI is classified into conducted emisDSM systems using physiological signals
sion (CE) and radiated emission (RE);
have recently been developed by automoCE is the electromagnetic noise that is generated at frebile manufacturers because physiological signals contain
quencies of 30 MHz or lower from an ECU and penetrates
an accurate information of the HR, which is very useful to
into other ECUs through signal lines and power lines.
determine the driver's physical status. In this study, we have
Meanwhile, RE is the electromagnetic noise that is created
introduced analog signal processing techniques employed
at frequencies of 30 MHz or higher and propagates through
in the DSM systems to acquire the physiological signals and
the air.
DSM algorithms to detect the driver's status. However, DSM
The EMS indicates the impact of electromagnetic intersystems using physiological signals require further research
ference from outside a vehicle. EMS is classified into bulk
on analog signal processing techniques, since physiological
current injection (BCI) and radiated susceptibility (RS).
signals are very weak and vulnerable to noise and interferBCI is defined as the endurance of electromagnetic interence in the in-vehicle environments. Studies have shown
ference released through power connectors, while RS is
that automobile manufacturers, universities, and research
the endurance of electromagnetic interference transmitted
institutions are making efforts to improve the performance
through the air. Therefore, in particular, the noise floor of
of the DSM systems using physiological signals and to apply
the DSM systems for HR monitoring should be set to satthe system to real vehicles. We expect that employing the
isfy a noise level equivalent to 25 nV peak to peak over the
DSM system will reduce traffic accidents due to the driver's
incapacitation and, therefore, enhance the safety of automobandwidth of 0.5-40 Hz [34].
bile users.
A surge noise occurs when a sudden voltage is applied or
current change occurs, for example, turning on/off of adjacent ECUs. This may supply a large current or voltage to the
Acknowledgments
DSM system instantaneously. In general, a human's heart
Seung-Hyun Kong is the corresponding author of this artiis the most sensitive to an electric current in a frequency
cle. This work (2013R1A2A2A01067863) was supported
range between 50-60 Hz so that a small current of 35 nA
by the Midcareer Researcher Program through a National
Research Foundation grant funded by the Korean governroot mean square (rms) can damage the heart and cause a
ment (MEST).
life-threatening event. Therefore, the DSM systems using the
ECG should be carefully designed by employing a resistance
or current limiting to allow a current of less than 10 nA rms
Authors
to flow through the system [34].
Youjun Choi (uchoi@kaist.ac.kr) received his B.S. degree in
Electrostatic discharge (ESD) is the sudden flow of elecelectrical engineering from Chonbuk National University in
tricity between two electrically charged objects by contact; it
2006, his M.S. degree in mechatronics engineering from the
occurs when the driver touches the electrodes. The DSM sysGwangju Institute of Science and Technology in 2008, and he
tem needs to limit the current that can be discharged through
is currently a Ph.D. candidate with the Cho Chun Shik
the contact of the driver's hand, so it requires a built-in protecGraduate School for Green Transportation at the Korea
tion circuitry to mitigate the ESD [34].
Advanced Institute of Science and Technology, South Korea.
As a result, the DSM systems using physiological signals
Since 2011, he has been a senior researcher at the Korea
must be tested based on EMC standards. The EMC tests should
Automotive Technology Institute. His research interests
be conducted with the CISPR (International Special Commitinclude mobility integration service and driver status monitortee on Radio Interference) standards for emissions and the the
ing systems for automotive.
International Organization for Standardization (ISO) stanSang Ik Han (sangik.han@kaist.ac.kr) received his
dards for susceptibility. EMI, EMS, surge noise, and ESD are
B.S. degree in electrical and electronics engineering from
IEEE SIgnal ProcESSIng MagazInE

November 2016

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