3D Motion Tracking by Inertial /Magnetic Sensors
Micro-machined Electro-Mechanical Systems (MEMS) Inertial Measurement Unit (IMU) typically
contains of three orthogonal rate gyroscopes and three orthogonal accelerometers, which measure
angular velocity and acceleration respectively. Three orthogonal Magnetic sensors measure the
earth magnetic field, which, after projecting to the horizontal plane (perpendicular to gravity), can
be used to calculate the heading (yaw) angle, with reference to the magnetic North or the
geographic North.
MEMS IMU is a self-contained navigation technique in which measurements provided by
accelerators and gyroscopes are used to track the orientation, velocity and position of an object
relative to a known starting point.
Magnetic heading is mainly used as an input to the data fusion, in order to correct the error on
heading introduced by gyro’s bias drifting.
The working principle:
The system can output the angular velocity, acceleration, velocity, position, and orientation in term
of the Euler angles, Quaternion, rotation vector...
Inertial/Magnetic motion tracking working principle
3 -axis
Magnetometer
Magnetic Field
3-axis Gyro
Angular Rate
Filter
Integral
Orientation
Initial
Velocity
Initial
Position
Velocity
3 -axis
Accelerometer
Acceleration
Gyroscope
ωx ωy ωz

x
ay
az


Magnetomet er
mx m y mz

Correct
gravity
Euler Angles
Quaternion
Rotation vector
Accelerome ter
a
Projection
to global

Integral
Up
Position
Integral
Velocity
VY VZ 
VX
Position
PY
PX
PZ 
Orientatio n

Coordinate Transformation
+
Filtering
 
North
East
Global system
Uniqueness of the product:
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Compact design: 27.9 x 19.5 x 4.8 mm^3, 2 gram + battery
Battery (rechargeable) driven, battery time: 4 - 200 hour
SIM card data storage + USB data transfer/battery charging
25 sensors hardware and software
3D gyro, 3D accelerometer, 3D magnetometer, temperature and internal voltages.
Heading, roll and pitch, velocity, position, angular velocity, acceleration.
Time stamping
RF data transmission /receiving
Advanced batch and data processing and filtering on pc
Fig: one prototype
Fig: 3-axis gyro
Fig: sensor power consumption
Application areas:
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Navigation of aircraft, spacecraft, submarines and ships
Indoor Navigation / Indoor pedestrian tracking
Human / Animal Motion Tracking, Position tracking
Continuous Measurement-While-Drilling Surveying
Sport training / Rehabilitation
Animation
Oil & Gas exploration
U-boat/Torpedo/ Unmanned vehicle
Working place safety and load evaluation
...
Fig: indoor navigation / indoor pedestrian tracking
Fig: monitoring of Parkinson Disease patients at home
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Fig: Continuous Measurement-While-Drilling Surveying in horizontal (directional) drilling