MW8 & MotionWare User Guide: Issue 1.2.1
Page 77
Tri-Axial Mode Data Processing
This is similar to above except all three axes are utilized to form counts based upon a
peak vector magnitude.
1. The X, Y and Z axes are sampled with filtering at 3-11Hz.
2. The peak X
2
+ Y
2
+ Z
2
value is found per second.
3. The square root of the sum of squares is calculated and added to the epoch
sum.
4.
This is compared to a minimum “not moving” threshold of approximately 0.1g.
Values below this threshold are ignored to simplify the final activity graph.
5.
The values are scaled to produce a ‘Tri-Axial count’ for the epoch.
The diagram below shows the X, Y, Z orientation relative to the watch casing:
MotionWatch XYZ axes: Tri-Axial mode
Z Axis
Y Axis
X Axis
