Integrated Chassis Management
Integrated Chassis Management
Integrated chassis management
There were two main objectives in the development of Integrated Chassis Management (ICM):
- To increase the performance of the individual driving stability control
- To improve the interplay of the individual driving stability control systems
The networking of the suspension control systems by the ICM control unit provides a hierarchical function structure of all software-based driving dynamics functions. In the second generation ICM control unit, passive and active safety networking has been implemented. Depending on the optional equipment (such as Vertical Dynamics Management VDM) and the national-market equipment (e.g. US version), several sensors are installed in the ICM control unit.
A particular experience for the customer is the coherent driving characteristics due the new Dynamic Driving Control. The driving dynamic control switch is used to operate Dynamic Driving Control.
An extra mode is available if a driving experience switch is fitted: ECO PRO.
A maximum of the following selectable programs are available:
1. SPORT+
2. SPORT
3. NORMAL or COMFORT
4. ECO PRO
Brief component description
The following components are described:
- ICM control unit
- Ride height sensor
- Centre console operating facility
ICM control unit
Sensors that were previously housed in other components are installed in the ICM control unit (depending on the configuration). The ICM control unit uses these sensors to calculate variables that are important for the dynamic handling characteristics of the vehicle:
New: The airbag sensors are integrated in the ICM control unit. This means that networking of passive and active safety has been implemented. The ACSM control unit ensures that the sensors are provided with a voltage supply.
The following sensors can be installed:
- Longitudinal acceleration sensor (maximum of 3)
- Lateral acceleration sensor (maximum of 3)
- Vertical acceleration sensor
- Yaw sensor
- Pitch rate sensor
- Yaw rate sensor
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.
WARNING: Observe repair instructions.
The ICM control unit may therefore only be removed or installed if the battery has been disconnected. The airbag control unit uses the sensor system in the ICM control unit to deploy the airbag. Otherwise there is a risk of unintentional airbag deployment.
The ICM control unit is located in the vicinity of the vehicle's centre of gravity.
The control unit is mounted on the transmission tunnel using 4 bolts and spacer sleeves made of aluminium. This mounting must connect the control unit to the vehicle body without play. Otherwise, the 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.
Ride height sensor
Depending on the optional equipment, a maximum of 2 ride height sensors are connected to the ICM control unit (1 at front axle, 1 at rear axle).
The ride-height sensors are mainly needed for the exterior lights. The ICM control unit also places the signal on the FlexRay for the Vertical Dynamics System (VDM).
The ride height sensor is a non-contact sensor. The ride height sensor proportionally converts distances into an analogue voltage signal using an angle of rotation. The sensor can be rotated by 360°. The measuring range is 70° (depending on the installation location, saw tooth-shaped characteristic curve). The signals are output as analogue electrical voltages.
Centre console operating facility
The driving experience switch controls the Dynamic Driving Control. The Dynamic Driving Control boasts the following new features: All of the drive and driving stability control systems installed in the vehicle are activated. The central control unit for this is the Integrated Chassis Management (ICM). The driving experience switch and DTC button are electrically connected to the ICM.
The following systems are influenced by Dynamic Driving Control:
- Accelerator pedal module (DME)
- Automatic gearbox (EGS)
- Steering (EPS)
- Vertical Dynamics Management (VDM) via the shock absorbers
- Dynamic stability control (DSC)
System functions
The following system functions are described:
- The Integrated Chassis Management system network
- Dynamic Driving Control
- ECO PRO mode
- Other functions
The Integrated Chassis Management system network
The following illustration shows the system network for the driving dynamics control
Dynamic Driving Control
The Dynamic Driving Control boasts the following two new features:
- All of the drive and driving dynamics control systems installed in the vehicle are switched at once.
- There is a choice of 3 stages. The state of the dynamic stability control is also taken into account, which means that 2 more stages are possible.
Dynamic Driving Control is operated using the driving dynamics control switch or driving experience switch and the DTC button arranged directly in front of it. Dynamic Driving Control thus bundles the switching of many drive and driving dynamics functions. The entire vehicle behaves in exactly the way the driver expects due to the stage selected. This bundling means that the characteristics of the vehicle are considerably more distinctive and that there is less emphasis on compromises. On the other hand, a large number of individual combinations, some of which are nonsensical, are avoided (example: sporty steering and simultaneous comfort-oriented damping).
If the SPORT+ program is selected, the vehicle automatically switches to dynamic traction control mode.
The display and control concept is extremely comprehensive. This depends on whether the Basic or High variant of the instrument cluster has been installed. If a the vehicle has a Central Information Display (CID), the display and operating concept is supplemented by graphical elements.
ECO PRO mode
For ECO PRO mode, a driving experience switch is fitted in the vehicle centre console operating facility.
ECO PRO guides the driver to adopt the best possible driving style for fuel consumption. Nevertheless sufficient driving dynamics are present. The driver is also aided in his consumption-optimized driving style by displays (see Owner's Handbook). Intelligent control of energy management and the heating and air conditioning system form the cornerstone of ECO PRO. A real life reduction in consumption of up to 10 % can be achieved.
ECO PRO comprises 4 subsections:
- Steady driving
Here, a different characteristic curve is selected for the accelerator pedal and different shift points set for the automatic transmission. For manual gearboxes, the shift point indicator is set differently. ECO PRO will also reactivate the automatic engine start-stop function if it is switched off.
- Heating and air conditioning system control
The heating and air conditioning system is tuned for efficiency. The air conditioning has a lower drying and cooling effect on the air. The refrigerant circuit is placed under a lower load. This reduces the amount of mechanical power required. Actions cause the combustion engine to emit higher levels of heat are avoided as far as possible. The positive temperature coefficient auxiliary heating (diesel engine) is operated at a lower heater output. The air conditioning compressor is switched off when the required temperature is reached, even without cooling power. The automatic engine start-stop function availability is increased. This can have acceptable comfort implications.
The vehicle memorizes these settings when ECO PRO is next activated
- Reducing electrical consumers
The mirror heating of the exterior mirrors is switched off (saves up to 100 W). The maximum temperature of the seat heating is restricted to approx. 37.5 °C (normally approx. 42 °C). The heating power of the heated rear window is also restricted.
- Displays in the instrument cluster and optionally in the central information display
Other functions
Integrated Chassis Management (ICM) assumes the following functions:
- Central plausibility monitoring for acceleration and yaw rates
- Central signal information for driving speed, longitudinal road inclination and lateral road inclination
- Driver assist system cruise control: Cruise control with brake function
- Central co-ordination of the display of Check Control messages for the suspension control system
- Central co-ordination of the torque request for suspension control systems
Notes for Service department
General notes
After installation of the new ICM control unit, the diagnosis system must be used to start-up the unit. Here, the following steps are carried out (depending on vehicle equipment):
- Adjustment of the sensor system integrated in the ICM
- Adjustment of the ride height sensors
WARNING: Observe repair instructions.
The ICM control unit may only ever be removed or fitted when the battery is disconnected. The airbag control unit uses the sensor system in the ICM control unit to deploy the airbag. Otherwise there is a risk of unintentional airbag deployment.
Diagnosis instructions
NOTICE: Follow the instructions for service functions.
The diagnosis system contains the following service functions for the Integrated Chassis Management:
- Adjustment of ICM sensor system
- Ride height adjustment
Path: Service functions > Chassis and suspension > Integrated Chassis Management
We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.