DETROIT - BMW AG tried to outfox the automotive airbag with its new occupant-sensing system.
The system debuts this year on its Z3 and Z8 roadsters. It uses electronic pressure mats and electromagnetic field generators to sense whether the seat is empty, is being used by an adult or is occupied by a child seat. The system can then delay or slow down deployment of the vehicle's airbags accordingly.
'Malfunctioning and the resulting injuries make it clear that the airbag, to put it bluntly, is still too stupid in its reactions,' said Wolfgang Zie-bart, BMW's board member in charge of research, development and purchasing.
'Our first move toward the intelligent airbag was to extend the seat-occupant identification principle,' Ziebart said at the SAE 2000 World Congress.
BMW's new seat contains two types of occupant-sensing systems.
The first is a pressure mat that contains strain sensors laminated in plastic. The mat can read and identify the imprint of a person's posterior and classify it by size and weight. Acura features a similar mat in its RL sedan, and General Motors plans to install one this year to detect out-of-position occupants.
BMW's second device consists of four plates buried in the cushions. The plates generate electromagnetic fields over the seat. A human body conducts electricity differently than a child seat or air, so sitting in the seat changes the field strength. The sensors can determine whether the seat is empty, being used by an adult or is filled with a child seat.
BMW partnered with microchip supplier Motorola Inc. to develop a high-speed processor that can juggle the various data inputs in the milliseconds between an impact and airbag deployment.
Ziebart also said BMW is considering whether to join the Internet purchasing venture established by General Motors, Ford Motor Co. and DaimlerChrysler.
If it did join, BMW would limit purchases to commodities such as office supplies, Ziebart said. 'We will never purchase the material that goes into our cars at an auction.'