User Manual

Please refer to Section 11.7 for further details on output co-ordinate systems and different

options to redefine the output co-ordinate systems.

True North vs. Magnetic North

As defined above the output coordinate system of the MTw is with respect to local Magnetic

North. The deviation between Magnetic North and True North (known as the magnetic

declination) varies depending on your location on earth and can be roughly obtained from

various models of the earth’s magnetic field as a function of latitude and longitude.

11.6.3 Arbitrary Alignment

If the measured kinematics is required in an object coordinate system (O) with a known

orientation with respect to standard sensor coordinate frame (S), the object alignment

matrix can also be set with an arbitrary but known orientation. This is useful if the MTw can

only be fastened in one specific orientation.

The object alignment matrix (R

) is applied to the output data (R

) according to the

following equations.

For 3D orientation data:

 

GO GS OS

R R R

For inertial and magnetic data:

R

Example

The object alignment matrix is given by:

Local

Magnetic North

Local

vertical

Local tangent plane

Z up, default

MTw default co-ordinate system

Z up, default