ICM control unit
New: Sensors that used to be installed separately in the DSC sensor are now fitted in the ICM control unit. The ICM control unit uses these sensors to calculate variables that are important for the dynamic handling characteristics of the vehicle at that time:
- Longitudinal acceleration and vehicle inclination in longitudinal direction
- Lateral acceleration and vehicle inclination in transverse direction
- Yaw rate
Initially, the sensor signals are related to the sensor housing. However, the driving stability control needs these variables related to the co-ordinate system of the vehicle. The ICM control unit performs the necessary conversion. The correction values necessary for this are determined by an adjustment during commissioning of the ICM control unit.
An adjustment of the integrated sensors is necessary after replacement of the ICM control unit. The adjustment must take place while the vehicle is on a subsurface that is horizontal in longitudinal direction and transverse direction. Terminal 15 must be switched on.
| Item | Explanation |
|---|---|
| 1 | Redundant lateral acceleration sensor |
| 2 | Longitudinal and lateral acceleration sensor |
| 3 | Output stages for Servotronic valve and ECO valve |
| 4 | Controller for FlexRay |
| 5 | Microcontrollers |
| 6 | Rotation-rate sensor |
| 7 | Redundant rotation-rate sensor |
The ICM control unit is available as a basic version and a high version. The high version differs in that it has:
- A larger microcontroller (required for calculation of the control operation of Integral Active Steering and Active Cruise Control)
- A redundant sensor system for lateral acceleration and yaw rate (safety requirement for Integral Active Steering).
| Item | Explanation |
|---|---|
| 1 | Upper housing section |
| 2 | Mounting bolt |
| 3 | Plug connection (54-pin) |
| 4 | Spacer sleeve |
| 5 | Lower housing section |
The ICM control unit is located in the vicinity of the vehicle center of gravity.
The control unit is mounted on the transmission tunnel using 4 bolts and spacer sleeves made of aluminum. This mounting must connect the control unit with the vehicle body without play. Otherwise, the control unit housing would vibrate, which would seriously diminish the operating principle of the integrated sensor system. A second task of this mounting is to dissipate heat from the control unit to the body.