BMW 7 Series: Functions

Integrated Chassis Management

Overview

With the E71, the notion of a higher-level driving dynamics control system was implemented for the first time in a standard model. This central function is also referred to as "Integrated Chassis Management" ("ICM" for short) and is integrated in the control unit of the same name in the E71.

The previous strategy was to use one control unit to perform the control tasks for each main movement direction. This approach was not employed in the E71 or the F01/F02.

Fig. 17: Identifying Control Units And Main Movement Directions Of Vehicle

INDEX REFERENCE CHART

1. Longitudinal dynamics
2. Lateral dynamics
3. Vertical dynamics

ICM - Integrated Chassis Management
VDM - Vertical Dynamics Management

As is the case in the E71, the new ICM control unit in the F01/F02 essentially performs the calculations for the control functions that influence the longitudinal and lateral dynamics. The actuators are activated by separate control units (e. g. AS control unit). The functional range of the ICM control unit in the F01/F02 has grown considerably when compared to the E71.

The Vertical Dynamics Management (VDM) is still responsible for controlling the vertical dynamics. The vertical dynamic control and dynamic drive functions are therefore accommodated in the VDM control unit.

Signals that provide information on the current driving situation are obviously exchanged between the ICM and VDM.

The main focus of this section is to describe the functions of the ICM control unit.

An introductory overview of these functions is provided in the following illustration and explanation. The functions are dealt with in more depth in the following chapters.

Fig. 18: Identifying ICM Control Unit Functions

INDEX REFERENCE CHART

1. Input signals from external sensors
2. Integrated Chassis Management
3. Output signals (target values at actuators and actuator control units)
4. Driver assistance functions
5. "Central driving dynamics and steering control" function
6. "Sensor signal processing and signal provision" function
7. "Driving dynamics control" function
8. DSC sensor in the ICM control unit (longitudinal acceleration, lateral acceleration, yaw rate)
9. Redundant DSC sensor in the ICM control unit (lateral acceleration, yaw rate)

Signal Provision

The ICM control unit reads signals from external and also internal sensors. These sensor signals are processed and converted into physical signals that describe the driving dynamics of the vehicle, and are subsequently made available to a large number of systems in the vehicle. Examples of these signals are road speed and lateral acceleration.

The central driving dynamics control system in the ICM firstly evaluates the current driving condition and driver's command, also taking the dynamic driving systems installed in the vehicle into account.

On the basis of this information, the system decides whether or not to intervene in the driving dynamics, and also the extent the intervention. The highly intelligent dynamic driving systems permit slight and barely noticeable interventions as soon as e. g. a tendency towards understeering is detected.

A coordinator ensures that the most suitable actuator is activated in each case. Where several actuators are used simultaneously, a great deal of importance has been placed on ensuring that these interventions are in perfect harmony.

The driving dynamics control provides the driver with the choice of one of four driving dynamics settings (Normal, Comfort, Sport and Sport+). By making this choice, the driver influences the central driving dynamics control system and therefore all dynamic driving systems and drive train systems. All systems are matched appropriately to every setting and, most importantly, their interaction with each other within one specific setting is also perfectly coordinated. The status of the Dynamic Stability Control is also taken into account thus ensuring that two additional driving dynamics specifications are possible.

The ICM control unit is also responsible for the Servotronic function including valve actuation. This steering control function is also influenced by the driving dynamics control.

Driver Assistance Functions

The ICM control unit incorporates the "Cruise control with braking" and "Active Cruise Control with Stop&Go" control functions. In addition, the ICM coordinates activation of the vibration actuator in the steering wheel for the "Lane Departure Warning" and "Active Blind Spot Detection" driver assistance functions.

READ NEXT: