Sensor Setup






The minimum CLASSAX sensor setup consists of two axle sensors across the whole width of the lane surrounded by an inductive loop. Two axle sensors are necessary to obtain an axle speed information which is needed to determine distances between axles. The inductive loop serves as a presence detector which does not require to be actually touched by any part of the vehicle and thus reliably allows to assign detected axles to particular vehicles. Knowledge of the number of axles a vehicle has along with the distances between them yields already a quite good information basis for classification.

Moreover, the inductive loop registers a certain amount of detuning which depends from properties of the vehicle and serves as an additional characteristic.

For higher demands there are two additional angled axle sensors, each one covering half of the lane width. These two sensors deliver an axle and tire width information. Although this does not yet enable real dual-tire detection it enhances performance to an extent which allows to handle pretty complex classification schemes.

CLASSAX uses fiber-optic SPx axle sensors from SENSOR LINE which ideally meet the requirements found here. 90 cm of travel path between the first and the last sensor are far sufficient; this facilitates axle detection significantly which in turn yields excellent accuracy.