BMW 5 Series: Crash-relevant functions

The Advanced Crash Safety Module must fulfil the following crash-relevant functions:

• Evaluating the sensor signals
• Impact detection
• Determining actuators to be activated
• Specifying the trigger time and trigger sequence
• Activation of the ignition circuit output stages
• Sending the crash message to all bus users
• Crash documentation
• Emergency call function

Evaluating the sensor signals

The sensors serve to identify and verify front-end, side-on and rear-end crashes and also as roll-over detection.

The sensors are located in the Advanced Crash Safety Module (ACSM) or are directly connected to the Advanced Crash Safety Module, where their signals are evaluated and processed.

Impact detection

The G30 is equipped with the following sensors:

• One lateral and one longitudinal acceleration sensor in the B-pillars (green)
• One airbag sensor to monitor the pressure in each of the front doors (blue)
• One lateral and one longitudinal acceleration sensor in the ACSM (yellow)
• One roll rate sensor in the ACSM (yellow)
• One vertical acceleration sensor in the ACSM (yellow)
• One airbag front sensor each on the engine supports (red)

The airbag sensors in the doors assist with the identification of a side-on crash.

The airbag front sensors assist with the identification of a head-on crash and its corresponding severity.

G30 Sensors

Trigger time and trigger sequence

The Advanced Crash Safety Module uses the values transmitted by the sensors to determine the direction and severity of the crash.

In the event of a head-on crash, for example, the correspondingly high acceleration values from the longitudinal acceleration sensors in the rear doors and Advanced Crash Safety Module (ACSM) respectively must be detected. An algorithm determines the severity and direction of the crash based on the accelerations. This information is used to assist calculation of the activation times and sequence in which the restraint systems are activated.

A possible imminent rollover is also detected and the appropriate protection systems are energized.

Activation of the ignition circuit output stages

The Advanced Crash Safety Module is supplied by the power distribution box on the rear right using terminal 30B. The Advanced Crash Safety Module (ACSM) is in offline mode with terminal 30B. This means that it is active on the data bus and can perform all diagnostic functions.

Activation of the ignition circuits is blocked and is available as of the "Driving" driving condition once the system self-test is complete.

The ignition capacitors are recharged via a switching controller. These ignition capacitors make the firing energy available in the event of a crash. If the voltage supply is interrupted during a crash, the ignition capacitors serve briefly as an energy reserve.

The ignition circuit output stages consist of a high-side and a low-side power switch. The high-side power switch connects the ignition voltage, while the low-side power switch connects to the ground.

The ignition circuit output stages are controlled by a microcontroller.

The high-side and low-side power switches also serve to check the ignition circuits during the system self-test.

Sending the crash message

In the event of a collision involving activation of the restraint systems, the Advanced Crash Safety Module (ACSM) sends a crash signal to the bus users in the data bus network.

The Telematic Communication Box 2 (TCB2) is actuated in parallel via a direct single-wire connection.

The TCB2 serves as a data modem in the vehicle. The emergency GSM antenna is integrated in the TCB2. This can be used to establish a telephone connection via the connected vehicle microphone even if the vehicle has rolled over. A built-in SIM card inside the control unit makes these emergency calls possible.

As a result, the respective control units perform the following functions depending on the crash severity:

Crash documentation

In the event of a collision where one or more actuators are activated, a crash entry is stored in a non- erasable memory. After 5 crash entries, a non-erasable fault memory entry is stored together with the information that the 5 crash signals have been saved. The airbag indicator light also lights up continuously.

The 5 crash entries are also able to be stored during the course of an accident. Each crash entry is assigned a system time. The control unit remains ignitable even after 5 crash entries. The crash entries cannot be erased and serve the purpose of subsequent device diagnosis. A maximum of 5 crash entries can be saved. The control unit must then be replaced.

Emergency call function

The emergency call functions are country-specific and are available to customers in countries with ConnectedDrive Services infrastructure. An emergency call requires an active SIM card in the Telematic Communication Box 2 (TCB2) and an available mobile phone network.

The emergency call button is connected directly with the TCB2.

The manual emergency call allows the driver to request assistance in the event of a medical emergency.

The next chapters provide detailed information on which functions the G30 receives with the standard equipment BMW Assist eCall.

BMW Assist eCall

The standard equipment BMW Assist eCall always includes the option of a manual or automatic emergency call (voice call and data transmission). A voice contact is initiated and data, such as the current position, is transmitted. The emergency call is made to a BMW Call center or an emergency coordination center, depending on the national-market version.

In the event of an accident with corresponding crash severity, the Advanced Crash Safety Module (ACSM) sends a message to the TCB2. The TCB2 initiates an emergency call.

With this automatic emergency call, the presumed number of people in the vehicle and sensor data, among other things, are transmitted to the BMW Call center, in order to identify the severity of the crash.

The information about the accident available at the call center can be forwarded to the emergency coordination center. The emergency coordination center can then initiate appropriate measures.

Attempts are made at the same time to establish a voice contact with the occupants of the vehicle in order to obtain more detailed verbal information about the accident (e.g. condition of occupants).

The following tables provides information on which functions are available in the case of an emergency call with BMW Assist eCall:

If, for various reasons, a connection to the BMW Call center cannot be established, the emergency call is automatically forwarded to the emergency coordination center.

The Intelligent Emergency Call can be ordered subsequently via the ConnectedDrive Store, if the vehicle already has the ConnectedDrive Services (OE 6AK) and the TCB2.

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