This document discusses the components of an inertial measurement unit (IMU), including MEMS accelerometers, gyroscopes, and magnetometers. It explains that MEMS sensors use very small microelectromechanical systems composed of silicon, polymers, metals or ceramics to measure acceleration, angular velocity, and magnetic fields. Accelerometers detect acceleration by measuring changes in capacitance caused by the movement of a mass on a spring. Gyroscopes measure angular rate using the Coriolis effect to induce displacement of a vibrating mass. Magnetometers function by detecting changes in electron flow and voltage caused by magnetic fields.

1. INERTIAL MEASUREMENT UNIT(IMU)
MUHAMMAD IBRAR
BAEM-F18-025
AVIONICS SYSTEM DESIGN
DEPARTMENT OF AVIONICS ENGINEERING

2. CONTENT LIST
• WHAT IS MEMS ?
• MEMS Accelerometer
• MEMS Gyroscope
• MEMS Magnetometer
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3. What is MEMS?
• The MEMS are very small systems or devices,
composed of micro components ranging from 0.001
mm to 0.1 mm in size. These components are made of
silicon, polymers, metals, and/or ceramics, and they
are usually combined with a CPU (Microcontroller) for
completing the system.
• Now we will briefly explain how each of these Micro-
Electro-Mechanical-Systems (MEMS) sensors work.
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4. MEMS Accelerometer
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• It has a mass attached to a spring which is
confined to move along one direction and fixed
outer plates.
• So when an acceleration in a particular
direction will be applied the mass will move
and the capacitance between the plates and
the mass will change.
• This change in capacitance will be measured
and processed and it will correspond to a
particular acceleration value.

5. MEMS Gyroscope
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• The gyroscope measures angular rate using
the Coriolis Effect.
• When a mass is moving in a particular
direction with a particular velocity and when
an external angular rate will be applied as
shown with the green arrow a force will occur,
as shown with the blue-red arrow, which will
cause perpendicular displacement of the
mass.
• So similar to the accelerometer, this
displacement will cause a change in
capacitance which will be measure
microstructure and it will correspond to a
particular angular rate.

6. MEMS Gyroscope
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• The micro structure of the
gyroscope looks something like
this. A mass
• that is constantly moving, or
oscillating, and when the
external angular rate will be
applied a flexible part of the
mass would move and make the
perpendicular displacement

7. MEMS Magnetometer
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• If we have a conductive plate like shown in
the photo and we set current to flow through
it, the electrons would flow straight from one
to the other side of the plate.
• Now if we bring some magnetic field near the
plate we would disturb the straight flow and
the electrons would deflect to one side of the
plate and the positive poles to the other side
of the plate.

8. MEMS Magnetometer
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• That means if we put a meter now between
these two sides we will get some voltage
which depends from the magnetic field
strength and its direction