Purpose of the System

Purpose of the System

With the launch of the E65/E66, a completely new passive safety system, the ISIS (Intelligent Safety Integration System), is introduced.

The MRS system (Multiple Restraint System) used so far consists of a central control unit with piezo-electric acceleration sensors and the two external satellites for side crash detection. The centralization and the associated sequential processing of different signals via conventional wiring harnesses led to high loads on the computer unit, time losses and greater susceptibility to malfunction.

Due to the limited performance of the microprocessor an expansion of the system to include other necessary sensors and trigger circuits for pyrotechnical actuators is not possible with the existing MRS.







The ISIS system consists of the Safety Information Module SIM and several control units, called satellites, that are linked across the byteflight bus. In the case of the MRS system there was only one central control unit. On the E65/E66,the acceleration sensors are integrated into the satellites.

The actuators are directly connected to the satellites and are activated by the satellites. The satellites are fitted at strategic points in the car. The distributed sensor system in the car enables measurement of the accelerations occurring as close as possible to the outer shell of the body and at the location of the collision.

The direct recording and processing of the information in the control unit mean that significantly shorter reaction times can be achieved. The mechanical time lag within the body to a central control unit is eliminated.

The distributed sensors in the satellites provide redundant information that is interchanged via the byteflight. This leads to even more reliable trigger decisions. In comparison to the MRS systems used to date, the ISIS enables,(for example in the event of a side-on collision) earlier triggering.

Because of the use of byteflight, the ISIS system has the following advantages:

- High communication speed
- Highest level of system security
- Faster trigger decisions
- Redundant information provided by the sensor
- Software update via bus
- Self-diagnostic procedure
- Mechanical safety switch is unnecessary
- No electromagnetic disturbances due to fiber-optic communication
- No electrical connection between transmitter and receiver module
- Simple system upgrade

Components

The ISIS is made up of the following components:

- SIM (System Master)
- byteflight
- A-Pillar Satellites, Left and Right
- B-Pillar Satellites, Left and Right
- Seat Satellites, Driver and Passenger
- Seat Satellite, Rear
- Door Satellite, Driver and Passenger
- Vehicle Center Satellite
- Steering Column Switch Center
- Central Gateway Module
- Driver and Passenger Front "Smart" Airbags
- Driver and Passenger Knee Airbags
- Advanced HPS I (HPS II with rear airbag option)
- Side Airbags, Driver and Passenger (Rear side airbags optional)
- Seat Belt Tensioners with Buckle Switch, Driver and Passenger
- Seat Belt Tension Limiters, Driver and Passenger
- Seat Belt End Fitting Tensioners, Left and right rear passengers
- Seat Occupancy Sensors, Driver and Passenger (4 seating positions with rear airbag option)
- Active Head Restraint (with Comfort Seat option)
- Safety Battery Terminal