Seat Occupancy Detector (OC-3 MAT)

Seat Occupancy Detector (OC-3 Mat)





Because of the legal situation in the USA, the presence of a child seat for a child up to one year old must be automatically detected and the passenger airbags then deactivated. The OC3 mat detects a child seat that conforms to the relevant standard (NHTSA FMVSS 208) by virtue of the pattern of the impression it makes on the seat and deactivates the passenger airbags.
A straightforward seat occupancy detector recognizes a certain weight (> 12 kg) as proof that the seat is occupied. In order to meet legislative requirements, the seat occupancy detector (SEE) has been developed into an intelligent occupant classifier (OC). This was achieved by means of the following measures:
^ By a larger number of sensor elements
^ By sensing a larger area of the seat
^ By an intelligent electronic analyzer
The OC3 mat is capable of distinguishing between a one-year-old child in a childs seat and a light person (approximately 45 kg).
The OC3 mat is integrated into the seat area of the passenger seat. The OC3 mat consists of conductors with pressure dependent resistor elements (FSR, or Force Sensitive Resistance elements). The conductors are connected to the electronic analyzer.
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.





By analyzing the signals from the individual sensors, the analyzer maps the occupancy of the seat surface and can identify the local concentrations of weight. The distances between the areas where pressure is applied and the concentrations of pressure reveal whether the seat is occupied by a person (A) or a child seat (B).
The analyzer of the OC3 mat sends a message to the MRS4RD control unit via the Kbus. If the system detects that the seat is unoccupied or that a child seat for a child up to one year old is fitted, the airbags on the passenger side are deactivated. The MRS4RD control unit switches on the airbag warning light. The airbag warning light indicates that the airbags on the passenger side are deactivated.

Note: The airbag warning light is switched on if the seat is unoccupied.