DSC and Integrated Chassis Management

Fig 1: Input/Output Signal Diagram - Interaction Of ICM And DSC

Courtesy of BMW OF NORTH AMERICA, INC.

On previous vehicles, the DSC control unit contained the central dynamic handling control functions. A dynamic handling control complex remains part of the DSC F0x. However, it is controlled by the central dynamic handling controller on the ICM (as are the other dynamic handling systems).

The ICM calculates the current handling status and the vehicle response desired by the driver. To do so, it makes use not only of the signals from the DSC sensor integrated in the ICM but also of those from external sensors such as the steering angle sensor and the wheel-speed sensors. If a difference between the response desired by the driver and the reaction of the vehicle is detected, the central dynamic handling controller on the ICM calculates a required compensatory yaw force.

The purpose of that yaw force is to bring about a yawing motion on the part of the vehicle that is superimposed over the existing movement of the vehicle. In that way, the vehicle handling can be corrected retrospectively, so to speak, when it threatens to become unstable. The highly advanced DSC technology and the central dynamic handling controller on the ICM even make is possible to optimize handling characteristics in advance. One example of that is brake modulation for the purposes of improved agility, which is described in one of the subsections further on.

Subordinate to the central dynamic handling controller on the ICM is an "actuator coordination" function. It decides whether and to what degree the DSC dynamic handling system is to contribute to producing the required yaw force.

The required force is signalled to the DSC's dynamic handling controller, which puts it into action by operating the actuators represented by the brakes and drivetrain.

Simple implementation of the settings specified by the ICM is, however, not the only task of the DSC's dynamic handling controller on the F01/F02. It also continues to independently perform the following original DSC functions:

• Anti-lock braking system (ABS)
• Cornering Brake Control (CBC)
• Automatic Stability Control (ASC)
• Engine drag torque control (MSR)
• Automatic Differential Brake (ADB)

The numerous additional functions over and above pure handling dynamics control are also carried out largely independently by the DSC and without intervention by the ICM.

• Functions which help to reduce stopping distance: they include brake drying, brake standby, brake fade prevention and dynamic brake control. The efficiency of the brake standby and dynamic brake control functions is further improved in combination with the "ACC Stop&Go" optional extra.
• Convenience functions which make driving easier, e. g. Automatic Hold, which is performed by the DSC and EMF in combination.
• The stresses on and wear of brake components are monitored with the aid of computation models. Based on information such as brake pressure and brake temperature and the signals from the brake-pad wear sensors, a remaining service life expressed as a mileage is calculated. The owner can view that information as a subfunction of Condition Based Service and use it as an aid to planning servicing appointments.