Audi q7 2017, Manual, Page: 11 / 70

7
X
Z
Y
637_013
637_014 637_015
Measurement of longitudinal vehicle movement in X, Y and Z directions
The sensors for the measurement of longitudinal vehicle
movement 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 moveable 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. This, in turn, changes the physical magni-
tude of the capacitance, which is processed digitally and
evaluated.
Rest position Movement