02-03-2013, 11:27 AM
Overview of Automotive Sensors
[attachment=52386]
Abstract
An up-to-date review paper on automotive sensors is
presented. Attention is focused on sensors used in production automotive
systems. The primary sensor technologies in use today are
reviewed and are classified according to their three major areas
ofautomotive systems application–powertrain, chassis, and body.
This subject is extensive. As described in this paper, for use in automotive
systems, there are six types of rotational motion sensors,
four types of pressure sensors, five types of position sensors, and
three types of temperature sensors. Additionally, two types of mass
air flow sensors, five types of exhaust gas oxygen sensors, one type
of engine knock sensor, four types of linear acceleration sensors,
four types of angular-rate sensors, four types of occupant comfort/
convenience sensors, two types of near-distance obstacle detection
sensors, four types of far-distance obstacle detection sensors,
and and ten types of emerging, state-of the-art, sensors technologies
are identified.
INTRODUCTION
SENSORS are essential components of automotive electronic
control systems. Sensors are defined as [1] “devices
that transform (or transduce) physical quantities such as
pressure or acceleration (called measurands) into output
signals (usually electrical) that serve as inputs for control
systems.” It wasn’t that long ago that the primary automotive
sensors were discrete devices used to measure oil pressure,
fuel level, coolant temperature, etc. Starting in the late 1970s,
microprocessor-based automotive engine control modules
were phased in to satisfy federal emissions regulations. These
systems required new sensors such as MAP (manifold absolute
pressure), air temperature, and exhaust-gas stoichiometric
air-fuel-ratio operating point sensors. The need for sensors is
evolving and is progressively growing. For example, in engine
control applications, the number of sensors used will increase
from approximately ten in 1995, to more than thirty in 2010,
as predicted in [2].
OBJECTIVE
MEMS-based automotive sensor technology was recently
reviewed by Eddy and Sparks [5]. Frank’s 1997 publication [6]
emphasized electronic circuits and sensor manufacture. Two
classic references on automotive sensors include: Wolber’s
1978 publication [7] and Heintz and Zabler’s 1982 publication
[8]. The objective of the present paper is to provide
an up-to-date overview of current-production and emerging
state-of the-art, automotive sensor technologies.
SENSOR CLASSIFICATION
As shown in Fig. 1, the three major areas of systems application
for automotive sensors are powertrain, chassis, and body.
In the present systems-classification scheme, anything that isn’t
powertrain or chassis is included as a body systems application.2
Fig. 1 also identifies the main control functions of each area of
application and the elements of the vehicle that are typically involved.
The automotive industry has increasingly utilized sensors
in recent years. The penetration of electronic systems and
the associated need for sensors is summarized in Table I.
Powertrain applications for sensors, shown in Table I, can be
thought of as the “1stWave” of increased use of automotive sensors
because they led the first widespread introduction of electronic
sensors. Chassis applications for sensors are considered
to be the “2nd Wave” of increased use of sensors, and body applications
are called the “3rd Wave.”
CURRENT-PRODUCT SENSOR TECHNOLOGIES
Table II through IV list 40, 27, and 40 sensors; respectively,
for powertrain, chassis and body automotive systems applications.
This gives a total of 107 sensors (which still isn’t all inclusive).
These 107 sensors are thought to be representative of
most of the major applications for sensors used in automobiles.5
Coverage of all details, pertaining to all automotive sensors, is
beyond the scope and size constraints of this paper. Attention
is, therefore, focused on sensors used in automotive production
systems (i.e., sensors used for instrumentation, or less significant
applications, are omitted).
Pressure Sensors
Pressure sensors have some very diverse automotive applications.
They measure pressures ranging from 10 kPa-vacuum (for
OBD evaporative fuel leak detection), to 180 MPa (for diesel
common-rail fuel pressure systems). This is a 18 000:1 variation
in full-scale pressure range measurement requirements! Clearly,
a sensor technology used in the 10-kPa application won’t be robust
enough for the 180-MPa fuel-pressure application. Consequently,
there exist several different pressure sensor technologies.
Pressure sensors have the second greatest unit sales and
the sixth highest gross sales revenue, which makes them number
two in the present categorization scheme.7 In 1999, in North
America, pressure sensors accounted for 9 % of all automotive
sensors sales revenue, with unit sales of 78 million sensors [3],
[9].
Other Sensors
1) Mass Air Flow: MAF mass air flow sensors are fourth
highest in gross sales revenue. On high-performance engines,
sensors based on a thermal heat-loss principle, including a
hot-wire element (plus a companion compensating hot-wire
element), are mounted in a bypass channel of the air intake to
measure mass air flow into an engine [30]. This type of sensor
measures true mass provided there’s no pulsating reversal of
air flow. Under certain operating conditions, pulsating reversal
of air flow does occur; in which case, another configuration
of the thermal flow sensor is used. This type utilizes a heat
source and dual upstream and downstream thermal flow-detection
elements (which are fabricated on a micromachined
low-thermal-mass diaphragm) [31].
SUMMARY
A comprehensive review of current-production and emerging
state-of the-art automotive sensor technologies is made. This
paper covers nearly 50 different types of automotive sensors—
all of which currently find widespread application, or
are expected to have a significant future impact on automotive
systems development. For automotive powertrain applications,
the predominant sensors in use today are rotational motion,
pressure and temperature. For chassis applications, predominant
sensors include inertial acceleration and inertial angular
rate sensors. As opposed to powertrain and chassis, body
systems applications sensors are more diverse and no single
sensor types dominate. Ten types of emerging, state-of the-art,
sensors technologies are also identified.
[attachment=52386]
Abstract
An up-to-date review paper on automotive sensors is
presented. Attention is focused on sensors used in production automotive
systems. The primary sensor technologies in use today are
reviewed and are classified according to their three major areas
ofautomotive systems application–powertrain, chassis, and body.
This subject is extensive. As described in this paper, for use in automotive
systems, there are six types of rotational motion sensors,
four types of pressure sensors, five types of position sensors, and
three types of temperature sensors. Additionally, two types of mass
air flow sensors, five types of exhaust gas oxygen sensors, one type
of engine knock sensor, four types of linear acceleration sensors,
four types of angular-rate sensors, four types of occupant comfort/
convenience sensors, two types of near-distance obstacle detection
sensors, four types of far-distance obstacle detection sensors,
and and ten types of emerging, state-of the-art, sensors technologies
are identified.
INTRODUCTION
SENSORS are essential components of automotive electronic
control systems. Sensors are defined as [1] “devices
that transform (or transduce) physical quantities such as
pressure or acceleration (called measurands) into output
signals (usually electrical) that serve as inputs for control
systems.” It wasn’t that long ago that the primary automotive
sensors were discrete devices used to measure oil pressure,
fuel level, coolant temperature, etc. Starting in the late 1970s,
microprocessor-based automotive engine control modules
were phased in to satisfy federal emissions regulations. These
systems required new sensors such as MAP (manifold absolute
pressure), air temperature, and exhaust-gas stoichiometric
air-fuel-ratio operating point sensors. The need for sensors is
evolving and is progressively growing. For example, in engine
control applications, the number of sensors used will increase
from approximately ten in 1995, to more than thirty in 2010,
as predicted in [2].
OBJECTIVE
MEMS-based automotive sensor technology was recently
reviewed by Eddy and Sparks [5]. Frank’s 1997 publication [6]
emphasized electronic circuits and sensor manufacture. Two
classic references on automotive sensors include: Wolber’s
1978 publication [7] and Heintz and Zabler’s 1982 publication
[8]. The objective of the present paper is to provide
an up-to-date overview of current-production and emerging
state-of the-art, automotive sensor technologies.
SENSOR CLASSIFICATION
As shown in Fig. 1, the three major areas of systems application
for automotive sensors are powertrain, chassis, and body.
In the present systems-classification scheme, anything that isn’t
powertrain or chassis is included as a body systems application.2
Fig. 1 also identifies the main control functions of each area of
application and the elements of the vehicle that are typically involved.
The automotive industry has increasingly utilized sensors
in recent years. The penetration of electronic systems and
the associated need for sensors is summarized in Table I.
Powertrain applications for sensors, shown in Table I, can be
thought of as the “1stWave” of increased use of automotive sensors
because they led the first widespread introduction of electronic
sensors. Chassis applications for sensors are considered
to be the “2nd Wave” of increased use of sensors, and body applications
are called the “3rd Wave.”
CURRENT-PRODUCT SENSOR TECHNOLOGIES
Table II through IV list 40, 27, and 40 sensors; respectively,
for powertrain, chassis and body automotive systems applications.
This gives a total of 107 sensors (which still isn’t all inclusive).
These 107 sensors are thought to be representative of
most of the major applications for sensors used in automobiles.5
Coverage of all details, pertaining to all automotive sensors, is
beyond the scope and size constraints of this paper. Attention
is, therefore, focused on sensors used in automotive production
systems (i.e., sensors used for instrumentation, or less significant
applications, are omitted).
Pressure Sensors
Pressure sensors have some very diverse automotive applications.
They measure pressures ranging from 10 kPa-vacuum (for
OBD evaporative fuel leak detection), to 180 MPa (for diesel
common-rail fuel pressure systems). This is a 18 000:1 variation
in full-scale pressure range measurement requirements! Clearly,
a sensor technology used in the 10-kPa application won’t be robust
enough for the 180-MPa fuel-pressure application. Consequently,
there exist several different pressure sensor technologies.
Pressure sensors have the second greatest unit sales and
the sixth highest gross sales revenue, which makes them number
two in the present categorization scheme.7 In 1999, in North
America, pressure sensors accounted for 9 % of all automotive
sensors sales revenue, with unit sales of 78 million sensors [3],
[9].
Other Sensors
1) Mass Air Flow: MAF mass air flow sensors are fourth
highest in gross sales revenue. On high-performance engines,
sensors based on a thermal heat-loss principle, including a
hot-wire element (plus a companion compensating hot-wire
element), are mounted in a bypass channel of the air intake to
measure mass air flow into an engine [30]. This type of sensor
measures true mass provided there’s no pulsating reversal of
air flow. Under certain operating conditions, pulsating reversal
of air flow does occur; in which case, another configuration
of the thermal flow sensor is used. This type utilizes a heat
source and dual upstream and downstream thermal flow-detection
elements (which are fabricated on a micromachined
low-thermal-mass diaphragm) [31].
SUMMARY
A comprehensive review of current-production and emerging
state-of the-art automotive sensor technologies is made. This
paper covers nearly 50 different types of automotive sensors—
all of which currently find widespread application, or
are expected to have a significant future impact on automotive
systems development. For automotive powertrain applications,
the predominant sensors in use today are rotational motion,
pressure and temperature. For chassis applications, predominant
sensors include inertial acceleration and inertial angular
rate sensors. As opposed to powertrain and chassis, body
systems applications sensors are more diverse and no single
sensor types dominate. Ten types of emerging, state-of the-art,
sensors technologies are also identified.