15
Document MT1600P.2019.A
© Xsens Technologies B.V.
MTi Family Reference Manual
4
MTi System Overview
4.1 Test and Calibration
A correct calibration of the sensor components inside the MTi is essential for an accurate output. The
quality and importance of the calibration are of highest priority. E
ach Xsens’
MTi is calibrated and tested
by subjecting each device to a wide range of motions and temperatures.
The individual calibration parameters are used to convert the sensor component readout (digitized
voltages) to physical quantities as accurately as possible, compensating for a wide range of deterministic
errors. Additionally, the calibration values are used in Xsens sensor fusion algorithms, as discussed
later in this document.
Each MTi contains individual test and calibration data in its eMTS (electronic Motion Tracker Settings).
It is digitally signed by a Test Person and states the calibration values determined during the calibration
of the MTi at Xsens’ calibration facilities.
The values can be seen by connecting the MTi to MT Manager
and navigating to Device Settings
→
Modelling Parameters.
Next to the calibration values shown in MT Manager, each device is calibrated according to more
complicated models to ensure accuracy (e.g. non-linear temperature effect, cross coupling between
acceleration and angular rate
4
).
4.2 Coordinate systems
Data from the MTi is represented in various coordinate systems, which are explained below.
4.2.1 Calibrated inertial data and magnetic field data
The default sensor-fixed frame (S
xyz
) is a right-handed Cartesian coordinate system that is fixed to the
device. When the sensor is rigidly attached to another object or vehicle but not aligned, it may be
convenient to rotate the sensor coordinate system S
xyz
to an object coordinate system (O
xyz
).
Refer to
BASE by Xsens - MTi reference co-ordinate systems
for more information on the available
orientation resets.
S
xyz
or O
xyz
are the coordinate frames used to express the rate of turn, acceleration and magnetic field
outputs. The encased version of the MTi shows S
xyz
on the sticker. Figure 8 and Figure 7 depict the
sensor coordinate system on the MTi 600-series and MTi 1-series. Later in this document, small x, y
and z are the axes labels for S
xyz
and O
xyz
. Capital X, Y and Z stand for the local-earth fixed coordinate
system (L
XYZ
).
4
Also known as “g
-
sensitivity”.
