REMAFA resp. REMABF: Reversible electromotive automatic reel, left and right

After evaluation of various signals and messages, the control unit recognizes whether the seat belt has to be pretensioned.

The reversible electromotive automatic reel system includes the following functions:

• Minimization of belt slack

  (the seat belt lies optimally against the driver's resp. front passenger's body)

• Stabilization of the seat position in a critical driving situation or in the event of a possible accident

  (pretensioning of the seat belt for optimizing the restraint system)

The reversible electromotive automatic reel consists of a automatic reel, electric motor with gearbox and an integrated control unit. The control unit is a bus user on the PT-CAN. After evaluation of various signals and messages, the control unit recognizes whether the seat belt has to be pretensioned. For example, the belt slack is thus removed after buckling up depending on the speed signal.

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 driving 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:

• Integrated chassis management

  The ICM control unit provides the systems in the entire vehicle with the dynamic driving state in the form of signals (e.g. data such as lateral and longitudinal acceleration, yaw rate).

• Dynamic Stability Control

  The DSC control unit supplies information about brake pressure, for example.

• Crash safety module

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

• Camera-based driver support systems

  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.

• Active cruise control

  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.

A failure of a control unit has no effect on the restraining function of the seat belt.