CAN communication and eCall

Source: CAN Newsletter Online January 2012

In case of a car crash, an eCall-equipped vehicle automatically calls the nearest emergency center. The eCall system collects data from the in-vehicle networks (IVN) and sends them to the center in order to request as fast as possible sufficient and all required rescuing resources. Most of the data comes from the CAN-based IVNs.

Besides the telematics equipment to call the emergency services, the eCall system comprises an interface to the IVNs. In particular, the CAN-based IVN connects the necessary “crash” sensors. This includes pressure, acceleration, roll-over sensors. In addition, seat occupancy recognition sensors indicate the number of potentially injured persons. The sensors measures, for example, the deceleration (loss of speed) and captures the time of air-back inflations. From these values the eCall system calculates the crash severity. The crash data is available after 100 ms. In the future more sensors may come, in order to improve the evaluation results.

The eCall will be sent to a public safety answering point (PASP), along with important information referred to as the MSD (minimum set of data). The MSD contains details of the exact time of the call, the GPS coordinates and the vehicle identification number (VIN). The VIN can be decoded and will provide information about the brand of the car and additional details. The MSD also contains optional fields, which can be filled with data like number of passengers as detected by closed seatbelt systems, and other sensor data from the car. If the PSAP receives such a call, the dispatcher will be able to talk to the people inside the car to obtain further information and offer reassurance. Even if there is no response, the operator can dispatch rescue services to the scene using the information provided in the MSD.