31-05-2012, 11:40 AM
An Intelligent Noninvasive Sensor for Driver Pulse Wave Measurement
[attachment=23644]
I. INTRODUCTION
IT IS WIDELY agreed that one of the contributing factors of
vehicle accidents is drivers and, therefore, lots of research efforts
have been focused on driver state/behavior [1]. If a driver’s
state can be detected online and then be fed back to the drivervehicle
system, this may lead to the development of a more intelligent
driver assistance system—next-generation driver assistance
system [2]. Thus, it calls for a real-time driver state
measurement system. Moreover, this system should not, by all
means, affect driver’s controlling behavior given that driver-vehicle
system is a safety critical system. Based on the above analysis,
the research effort presented in this study has been focused
on developing such a noninvasive device for online measurement
of a driver’s physiological state. In the following, more
background of the research will be given, as well as state-ofthe-
art.
Measurement Techniques
With respect to heart rate and heart rate variability, in [25],
Knight et al. used a microphone and a pressure bulb which are
strapped around the wrist to measure the pressure of the radial
artery, and then measured HR. The strong external sound may
influence the output of the system. The approach is intrusive.
In [26], Kaniusas et al. developed a novel magnetoelastic skin
curvature to estimate blood pressure. A sensor is applied on the
neck over the carotid artery and can also be employed to measure
HR and HRV.
Sensor Selection and Design
First, the basic requirements for the sensors are analyzed considering
the application domain. The sensors of a smart wheel
operate in the inner space of a vehicle where there is no corrosive
gas, no radiation, little dust, and possibly strong UV light. However,
the sensors will have close contact with a driver’s palms,
possibly bearing sweat, machine oil, etc. A driver’s gripping
force is within the range of 0–390 N [41]. Thus, the basic requirements
for the sensors are good stability (against chemicals)
and high capacity (to withstand strong mechanical stress).
The Hardware Configuration
In total, 17 groups of sensors were used in the electronic
system. Each sensor group includes a PVDF film sensor, a
piezoresistive sensor, and a temperature sensor. The sampling
rate is 200 Hz. The speed of producing data can reach 20 Kb/s
if the system produces 2 bytes of data per sample per channel.
The hardware configuration of the electronic system is shown
in Fig. 3. An embedded system is utilized to execute logical
control, data storage, and data processing.
MECHANICAL DESIGN OF THE SYSTEM
There are several design challenges for the smart wheel
system. For example, the contact between the driver and the
steering wheel occurs at random locations; the gripping force
applied to the system varies greatly; and there are negative
effects on measurement accuracy due to the vibration from
the vehicle. To meet these challenges, the main mechanical
structure of the smart wheel was designed to withstand the
stress that a driver may apply to it.
CONCLUSION
Monitoring human physiological state is becoming increasingly
important in many application domains. In the case of
the driver-vehicle system, it is even more important in order
to achieve a safe driving. In this study, a noninvasive sensor
integrated prototype system was developed to measure driver’s
pulse wave, breathing wave, skin temperature, and gripping
force. A group of PVDF film sensor, semiconductor temperature
sensor, and tactile piezoresistive sensor were integrated
into a smart wheel system. One of the advantages of this
prototype is its nonintrusiveness.
[attachment=23644]
I. INTRODUCTION
IT IS WIDELY agreed that one of the contributing factors of
vehicle accidents is drivers and, therefore, lots of research efforts
have been focused on driver state/behavior [1]. If a driver’s
state can be detected online and then be fed back to the drivervehicle
system, this may lead to the development of a more intelligent
driver assistance system—next-generation driver assistance
system [2]. Thus, it calls for a real-time driver state
measurement system. Moreover, this system should not, by all
means, affect driver’s controlling behavior given that driver-vehicle
system is a safety critical system. Based on the above analysis,
the research effort presented in this study has been focused
on developing such a noninvasive device for online measurement
of a driver’s physiological state. In the following, more
background of the research will be given, as well as state-ofthe-
art.
Measurement Techniques
With respect to heart rate and heart rate variability, in [25],
Knight et al. used a microphone and a pressure bulb which are
strapped around the wrist to measure the pressure of the radial
artery, and then measured HR. The strong external sound may
influence the output of the system. The approach is intrusive.
In [26], Kaniusas et al. developed a novel magnetoelastic skin
curvature to estimate blood pressure. A sensor is applied on the
neck over the carotid artery and can also be employed to measure
HR and HRV.
Sensor Selection and Design
First, the basic requirements for the sensors are analyzed considering
the application domain. The sensors of a smart wheel
operate in the inner space of a vehicle where there is no corrosive
gas, no radiation, little dust, and possibly strong UV light. However,
the sensors will have close contact with a driver’s palms,
possibly bearing sweat, machine oil, etc. A driver’s gripping
force is within the range of 0–390 N [41]. Thus, the basic requirements
for the sensors are good stability (against chemicals)
and high capacity (to withstand strong mechanical stress).
The Hardware Configuration
In total, 17 groups of sensors were used in the electronic
system. Each sensor group includes a PVDF film sensor, a
piezoresistive sensor, and a temperature sensor. The sampling
rate is 200 Hz. The speed of producing data can reach 20 Kb/s
if the system produces 2 bytes of data per sample per channel.
The hardware configuration of the electronic system is shown
in Fig. 3. An embedded system is utilized to execute logical
control, data storage, and data processing.
MECHANICAL DESIGN OF THE SYSTEM
There are several design challenges for the smart wheel
system. For example, the contact between the driver and the
steering wheel occurs at random locations; the gripping force
applied to the system varies greatly; and there are negative
effects on measurement accuracy due to the vibration from
the vehicle. To meet these challenges, the main mechanical
structure of the smart wheel was designed to withstand the
stress that a driver may apply to it.
CONCLUSION
Monitoring human physiological state is becoming increasingly
important in many application domains. In the case of
the driver-vehicle system, it is even more important in order
to achieve a safe driving. In this study, a noninvasive sensor
integrated prototype system was developed to measure driver’s
pulse wave, breathing wave, skin temperature, and gripping
force. A group of PVDF film sensor, semiconductor temperature
sensor, and tactile piezoresistive sensor were integrated
into a smart wheel system. One of the advantages of this
prototype is its nonintrusiveness.