Smart Industry 2/2018

vibration, sound, pressure, etc. Here
the mechanical and electronic parts
of the MEMS device are key, with a
combination of a tiny moving mechanical
part and an electronic part.
The electronic part converts changes
in the device characteristics due
to the movement of the mechanical
part into an electrical signal and
then into digital information about
the physical change being measured.
• Next, the sensor needs to have all
the right features to address the application
in question – for example,
the right size, the right power consumption,
the right temperature
range, and smart features that it
needs to fulfil the application needs.
• The final critical element is accuracy
– a measure of how closely the
output from a sensor matches the
“true” or actual value of what is being
measured. Accuracy in a sensor
depends on its ability to deal with
noise in the measurement environment,
its stability over time and
ambient temperature, and its tolerance,
i.e. the limits of variation.
While a sensor’s noise capability is a
function of the sensor design (mechanical
and electronic), the stability
and tolerance are mainly functions of
the testing and calibration processes,
and the associated algorithms that
are embedded in the sensor.
Highly accurate industrial sensors
have been produced in relatively low
quantities up to now due to the need
for long test and calibration times for
each sensor. This is where the consumer
heritage of MEMS plays a significant
role. High-volume consumer
MEMS manufacturers like ST have a
huge test and calibration capacity
installed and therefore the ability to
produce industrial sensors in large
volumes (relative to the volumes of
industrial sensors today) using the
same test and calibration equipment
used for consumer sensors. The tests
are, of course, different from those
for consumer sensors, using highly
accurate stimuli, wider temperature
ranges, a larger number of calibration
points, multiple degrees of freedom
testing, and high levels of parallelism
in the testing processes.
Stability over time
In addition, since the functionality
of the sensors is often the same as
those used for consumer applications,
a small proportion of the consumer
sensors can be sorted based on the
best characteristics and then calibrated
to meet the more demanding
industrial requirements.
Take the example of condition monitoring
of a motor through vibration
measurement. This is an application
that requires high accuracy in the
measurement of the vibration and
stability over time and temperature in
a harsh factory environment.
The more accurate the measurement,
the more insight can be gained into
the evolution of the condition of the
motor. This is an important enabler of
predictive maintenance where data
from a large number of motors is analyzed
over time to produce insights
into how and when a working motor
should be maintained.
ST offers a range of compact, highaccuracy,
high-stability, low-power
Running hot and cold
Condition monitoring of
motors through vibration
testing requires
a high degree of accuracy
over time and in
harsh environments.
Making double sure
An industrial sensor
needs to meet stringent
performance requirements
including
extended temperature
range, sensing
stability, and accuracy
as well as ensure
long-term availability,
all of which require
constant testing.
industrial sensors such as accelerometers,
gyroscopes, six-axis inertial
measurement units (IMU) and magnetometer
sensors. ST also offers a
range of temperature and pressure
sensors suitable for environmental
monitoring. These sensors can be
combined with microcontrollers and
connectivity to create smart solutions
for industrial equipment monitoring
throughout its life cycle – from transport
and installation to long-term operational
maintenance. During shipment,
accelerometers can be used
to monitor shock and vibration while
temperature and pressure sensors
monitor environmental conditions
encountered during transport.
In the installation phase, a high-resolution,
high-stability accelerometer
can be used for inclination measurement
and other accelerometers can
be used for shock and vibration measurement.
Environmental sensors also
enable monitoring of conditions during
installation. These measurements
enable equipment manufacturers and
end customers to be sure installed
equipment hasn’t suffered deterioration
before it is put into operation.
During equipment operation, accelerometers
for monitoring inclination
and shock as well as microphones
and environmental sensors can be
used to gather valuable information
to enable condition monitoring and
predictive maintenance.
Sensors have a great future ahead
as one of the key enablers of smart
industry trends and ST is working to
make that a reality today.
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