OC3 Mat

The OC3 mat (Occupant Classification) detects a child seat specified in accordance with NHTSA and which is occupied on the basis of the pressure per unit area and disables the passenger airbag.

The OC3 mat consists of conductors in a pressure-sensitive resistance grid, so-called FSR elements (Force Sensitive Resistance). The conductors are connected to the electronic evaluation unit.

The FSR elements are wired in such a way that they can be sampled individually. When the mechanical load on a sensor element increases electrical resistance decreases and the measurement current changes accordingly.

Fig 1: Identifying OC3 Mat

Courtesy of BMW OF NORTH AMERICA, INC.

By analysing the signals from the individual sensors, the analyzer can map the occupancy of the seat surface and identify local concentrations of weight. The relationship between the areas and the load points indicates whether there is a person or a child seat holding a small child present.

The electronic evaluation unit of the OC3 mat sends a telegram via the LIN-bus to the Crash Safety Module.

The front passenger airbags (front and side airbags) are disabled when a child seat with small child is detected. The crash safety module activates the passenger airbag OFF indicator lamp in the roof function Center.

Fig 2: Example Of Various Surface Imprints

Courtesy of BMW OF NORTH AMERICA, INC.