System functions

When a seat belt is put on, the control unit activates the respective reversible electromotive automatic reel one time over a specific period. Above an encodable speed (currently 10 Km/h), the seat belt strap is rolled up by the drive thus removing the belt slack.

In critical driving situations or in the event of a possible accident, the control unit also activates the drive. An algorithm calculates the driving condition and can issue the request for belt tensioning. The duration is set in such a way that the drive is activated by the control unit until a collision occurs or until a critical driving situation ends. For calculating whether a critical driving situation exists, for example, vehicle oversteering, both control units (REMAFA and REMABF) use the data from the following systems:

• DME (Digital Engine Electronics) or DDE (Digital Diesel Electronics)

  DME (Digital Engine Electronics) or DDE (Digital Diesel Electronics) supplies the signals of the pedal sensor position.

• Integrated chassis management (ICM)

  The Integrated Chassis Management (ICM) makes information about the driver's choice and about the dynamic handling characteristics status available to the systems in the entire vehicle.

• Dynamic stability control (DSC)

  The Dynamic Stability Control (DSC) supplies information about the brake pressure.

• Crash Safety Module (ACSM)

  The Crash Safety Module (ACSM) sends a message with the status of the seat belt buckle contacts. The request for tensioning the seat belt occurs from the Crash Safety Module (ACSM).

• Camera-based driver support systems (KAFAS)

  The camera-based driver support systems (KAFAS) supply the signals of the lane departure warning and object detection. The request for tensioning the seat belt occurs through the camera-based driver support system (KAFAS).

• Active Cruise Control (ACC)

  The Active Cruise Control (ACC) processes the signals about distance and speed about objects moving away from the vehicle in front of the vehicle and sends these to the Integrated Chassis Management (ICM). The request for tensioning the seat belt is sent via the PT-CAN to the respective reversible electromotive automatic reel (REMAFA and REMABF) via the Integrated Chassis Management (ICM).

The following graphic shows functional networking for the example of F10:

Fig 1: Dynamic Stability Control - Circuit Diagram

Courtesy of BMW OF NORTH AMERICA, INC.

The central gateway module is the front electronic module (FEM) in the F30, for example.

The central gateway module is the Body Domain Controller (BDC) in the F15, for example.