Accelerometer introduction, working, types, advantages and diadvantages are well explained for all the types of accelerometer focusing on automobile applications

1. Accelerometer sensor
By
Intakhab Khan (VTP2984)
Under the guidance of
Prof. A . Muthrasan

2. Table of contents
1. Introduction
2. Types
3. Working
4. Applications
5. Advantages and disadvantages
6. Manufacturers
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3. Accelerometer sensor
• Accelerometers are electronic sensor which are used to measure the acceleration of the vehicle
in all the three axis. It converts acceleration into electrical signals and sends it to electronic
control unit after amplification by which the acceleration value is interpreted. In vehicle these
accelerometers helps in finding acceleration in all thee axis for vehicle control, measurement of
vibration and shocks for engine control or suspension control and also used to deploy air bag
during accidents.
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4. Types of Accelerometers
Accelerometers
Piezoresistive piezoelectric
Capacitive
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5. Working
A. Capacitive Accelerometer
- It consists of mass attached with the springs, when the vehicle accelerates the mass moves
the opposite direction due to pseudo force which changes
the distance of separation between plates and as we know
capacitance of the capacitor is inversely proportional to the
distance of separation the capacitance changes with the
acceleration. This leads to change in voltage and this signal
is sent to ECU which is manipulated and converted into
acceleration value.
𝐶 =
𝐴ε˳
𝑑
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7. 3 axis accelerometer
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8. Working
B. Piezo resistive Accelerometer
- A piezo-resistive accelerometer has a stable structure composed on a silicon chip created by the
micromachining and semiconductor production technology. A mass and a beam on which a set
of the piezo-resisters are created on a silicon chip. A set of electrical bridged is formed by such
piezo-resistive resisters to generate signals proportional to the applied acceleration
- A piezoresistive accelerometer is based on changes in electrical resistance in a strain gauge.
sensors with conventional glued-on strain gauges or opt for microelectromechanical systems
(MEMS) technology instead.
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10. Working
C. Piezoelectric Accelerometer
- It works under the principle of piezoelectric effect which is piezoelectric materials produce
electricity when put under physical stress. When the vehicle accelerates the force acts on the
mass (Pseudo force) which leads to deformation of piezoelectric crystal structure creating the
voltage across the material as per the given equation.
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𝐸 = 𝑔𝑡
𝑚𝑎
𝐴
g = voltage sensitivity
a = acceleration
A and t is area and thickness of crystal
m is seismic mass

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12. Application
• Automobile collision safety systems uses accelerometer. When a car is acted on by a powerful
dynamic force, the accelerometer (sensing a rapid deceleration) sends an electronic signal to
an ECU, which in turn deploys the airbags.
• Electronic stability control in vehicles uses Accelerometer along with gyroscope to measure the
vehicle orientation and dynamic condition
• Vibration and shock measurement (piezoelectric)
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13. Advantages Disadvantages
➨It is simple to interface.
➨It has high impedance.
➨It offers higher sensitivity.
➨It has high frequency response.
➨It is available at lower cost due to
advancement in MEMS technology
➨It uses built-in signal conditioning
circuit to measure capacitance.
➨An Accelerometer measures change in velocity only.
It does not measure a constant velocity.
➨An Accelerometer can not measure rotation around
its own axis of movement. Due to this, it is used in
conjunction with gyroscope to measure angular
velocity.
➨It is sensitive to temperature and operates over
limited temperature range.
➨Its efficiency degrades over time.
➨It requires external power for its operation.
➨The other disadvantages are less longevity and
hysteresis error.
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14. Manufacturers
• BOSCH
• NXP
• MEMSIC
• Kionix
• STMicrocontrollers
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15. Thank You
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