BMW 5 Series: Active protection

The standard equipment of the G30 already includes the Active Protection safety package.

The Active Protection safety package comprises the following 3 functionally independent subsystems:

• PreCrash
• PostCrash
• Alertness assistant

The Active Protection safety package increases the safety of the occupants through preventative measures in the event of critical driving situations (PreCrash) and through measures after a crash (PostCrash). The attention assist monitors the driving style of the driver during the journey and encourages the driver to take breaks if necessary.

System wiring diagram for Active Protection

G30 System wiring diagram for Active Protection

1. Dynamic Stability Control (DSC)
2. Digital Motor Electronics (DME)
3. Electronic Power Steering (EPS)
4. Radar sensor for Active Cruise Control (ACC)
5. Fuse for front right power distribution box
6. Body Domain Controller (BDC)
7. CAN terminator
8. Reversible electromotive reel right, (REMARE)
9. Fuses in the power distribution box, rear right
10. Reversible electromotive reel left, (REMALI)
11. Front passenger seat module, (SMBF)
12. Advanced Crash Safety Module (ACSM)
13. Roof function center (FZD)
14. Camera-based driver support systems (KAFAS)
15. Control unit for optional equipment system (SAS)

PreCrash

The PreCrash subsystem introduces preventative protective measures for the occupants in known critical driving situations which may lead to an accident.

Identification of critical driving situations

Critical driving situations are identified with help of the inertial sensor system installed in the vehicle.

Critical driving situations include:

• Emergency braking initiated
• Strong understeer
• Strong oversteer
• Rollover of the vehicle

Imminent collisions are detected with the assistance of the camera-based driver assistance systems (KAFAS) stereo camera. On vehicles with the optional equipment active cruise control with Stop&Go function (OE 5DF) or Driving Assistant Plus (OE 5AT) the data of the radar sensor system is additionally evaluated. For the PreCrash detection, separate threshold values are made available for the triggering of the PreCrash functions are made available by the camera-based driver assistance systems or the radar system.

Convenience functions

• When the seat belt is fastened, the front seat belts are automatically pre-tensioned once when driving starts.

Safety functions

In detected situations that are critical for driving dynamics (for example, emergency braking, strong understeer, skidding) the following individual functions become active as needed:

• Automatic pre-tensioning of front seat belts
• Automatic closing of windows up to a gap
• Positioning the front passenger backrest
• Closing of the sunroof

PostCrash

The PostCrash subfunction includes the automatic braking function after an accident, which brakes the vehicle to a standstill in certain accident situations without intervention from the driver. The risk of another collision can thus be reduced. The driver may oversteer the automatic braking after a crash by pressing the brake pedal or accelerator pedal.

The automatic braking after a crash is activated if a crash with sufficient severity has been identified in the Advanced Crash Safety Module (ACSM). The Advanced Crash Safety Module (ACSM) then sends a signal to the fuel pump control electronics to switch off the electric fuel pump. The same signal is evaluated by the DSC. The DSC then brakes the vehicle to a standstill.

The DSC generates a maximum setpoint deceleration of 5 m/s2 for braking. During automatic braking the accelerator pedal and brake pedal are monitored. The automatic braking is interrupted if the accelerator pedal is pressed or if the brake pedal is pressed for a longer period by the driver. Pressing the accelerator pedal only causes the braking process to stop. Acceleration of the vehicle is not possible as the fuel pump is switched off.

Also during automatic braking the ABS prevents the wheels from blocking and the DSC stabilises the vehicle. If the DSC is in DSC OFF mode during automatic braking, a forced activation of the DSC is carried out.

Approx. 1.5 seconds after reaching standstill, the brake is automatically released and the vehicle must be secured against rolling away.

If a crash is detected, which leads to activation of the safety battery terminal, then automatic braking cannot be activated as the DSC pump is no longer supplied with power.

Automatic braking is not activated under the following conditions:

• The DSC has failed before the crash.
• The ABS has failed before the crash.
• The brake fluid level is too low.

If these faults occur during or after the crash, the control is led to the end as these faults are then interpreted as consequences of the crash.

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