MoTeC Interpreter - Manual (Page 20)

18 Analysis Tools
However, if a new track map is to be calculated and drawn, some extra
information must be logged. The necessary channels are:
Speed
Lateral G force
Lap Beacon
The Track Map is automatically generated from an analysis of vehicle speed
and lateral G force. The accuracy of the track map is therefore completely
dependant on the quality of the data recorded in the log file. If the track map
looks distorted, the calibration of either lateral G or speed is incorrect.
Longitudinal G is not required, however it is used to calculate corrected speed
which eliminates the effect of wheel locking and/or lifting to improve the Track
Map calculation. If Longitudinal G is not available, it is important to choose a
lap which does not have any wheel locking from which to generate the track
map. Wheel locking can be seen from a sudden downwards spike in wheel
speed.
If the track map is drawn as a mirror image of the real track, then
Lateral G force calibration is incorrect. Lateral G should be positive for
Left hand corners. Lateral G can be inverted using channel maths to correct
this if necessary.
Check the G sensor calibration by turning it onto its side – with the left
side of the sensor facing up it should read +1G; with the right side of
the sensor facing up it should read -1G. The sensor should be zeroed
before each session for best results.
Check the speed calibration by comparing the lap distance reported in
interpret against the stated track length. They should be within 100M.
Sensor noise is a common cause of being unable to draw a correct
Track Map. In the Graphical Analysis section check the speed trace
for smoothness, the data should follow consistent trends, data that
jumps up and down by more than 2 km/h is and indication of poor sensor
mounting or interference. Similarly the Lateral G sensor should be
reasonably smooth with readings close to zero when driving on straights.