Xsens DOT - Orientation; Free Acceleration; Timestamp and Packet Counter; Table 9: Orientation Outputs

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Magnetic field
a.u. (arbitrary units)
6
normalized to earth field
strength
4.2.3 Orientation
The output orientation can be presented in different parameterizations:
Table 9: Orientation outputs
Parameterization
Unit
Quaternions
(-) quaternion values
Euler angles
degree. Yaw, pitch, roll (ZYX Euler Sequence.
Earth fixed type, also known as Cardan or
aerospace sequence)
A positive rotation is always “right-handed”, i.e., defined according to the right-hand rule
(corkscrew rule). Refer to this BASE article
for detailed definition of orientation outputs,
and how quaternions, Euler angles relate to each other.
Users can access conversion functions in SDK to convert orientation in quaternions to Euler
angels. Refer to SDK programming guide for more information.
4.2.4 Free acceleration
Free acceleration is the acceleration in the local earth coordinate system (L) from which
the local gravity is deducted.
Table 10: Free acceleration outputs
Data
Unit
Free acceleration
m/s
2
4.2.5 Timestamp and packet counter
Each data message from Xsens DOT is accompanied by a packet counter and a timestamp.
Packet Counter
Packet counter starts with every new measurement and increase with every generated
data message. This value wraps at 0xFFFFFFFF.
SampleTimeFine
Contains the timestamp of an output expressed in 1MHz clock ticks of the device’s local
clock. The unit of the SampleTimeFine is microsecond. If the data output rate is 60 Hz, the
time interval between two SampleTimeFine is 16667 µs.
6
one a.u. is the magnetic field strength during calibration at Xsens’ calibration lab, approximately
40 uT.