ACTIVE MAGNETIC FIELD BASED SENSING SYSTEM FOR IMPROVED DETECTION AND DISCRIMINATION OF SIDE IMPACT CRASHES Len Cech

Motivated by the complexity and variety of real-world side impacts, the Magnetic Side Impact (MSI) approach for side-impact crash detection and discrimination is presented. NHTSA has issued a rulemaking proposal that requires improved occupant protection in side impact crashes. It proposes 100 % passenger car compliance to a more challenging standard in the near future. OEMs will likely require new sensing technologies and configurations to meet the proposed NHTSA standard. This paper discusses a sensing technology for improved side-impact crash detection and discrimination. The MSI system induces a time-varying, fixed frequency magnetic field into the vehicle structure using a wire coil transceiver located in the vehicle door or frame. The induced field can also be sensed at other vehicle locations using a second wire coil receiver that detects changes in the magnetic field flowing through it. In normal operation, the transceiver (and receiver) signals are constant amplitude sinusoidal voltages at the transmitted frequency. During a crash, the magnetic path around the transceiver and between the transceiver and receiver is perturbed, and the resulting changes in the magnetic field are superimposed onto the MSI waveform. The received signal(s) are demodulated; leaving a signal whose content is proportional to crash severity and general impact location. The MSI system has shown to provide fast and reliable time to fire (TTF) signals in both laboratory and crash testing. The MSI uses electromagnetic waves for communicating crash information, resulting in extremely fast detection and clear separation of deploy/non-deploy events. Placing a transceiver and receiver at opposite ends of the door allows wider spatial coverage. This paper describes the model and shows crash-sensing performance and system benefits based on crashes using a full vehicle Body-in-White platform