9
X
Z
Y
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Measurement of longitudinal vehicle movement in X, Y and Z directions
The sensors for the measurement of longitudinal vehicle move-
ment in X, Y and Z directions work on the "seismic mass" principle.
Capacitor plate
(movably mounted)
Seismic mass
Spring element
Capacitor plate
(stationary)
Housing
Direction of measurement
Design of the sensor
A movably mounted mass (seismic mass) is integrated in the
sensor at a defined distance to a stationary capacitor plate acting
as an electrode. The seismic mass also has electrodes, which
combine with the stationary electrodes to form a capacitor.
An acceleration force acting on the sensor changes the position of
the seismic mass relative to the stationary capacitor plate due to
inertia. This, in turn, changes the physical magnitude of the capaci-
tance, which is processed digitally and evaluated accordingly.
Rest position Movement
Coordinates