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The key-enabler for tomorrow's X-by-wire systems is the mastery of today's advanced active chassis control systems that are highly safety critical, distributed and complex. The only feasible way is to compose future X-by- wire systems with established and field approved functional management, components and infrastructure technologies, which are addressed in this paper.

Integrated Chassis Management ICM is a novel and demanding approach to develop a vehicle chassis and all its control systems in a common process which explicitly addresses the interrelations between them. Primary aims are the improvement of driving safety and comfort by creating synergies in the use of sensor information, hardware, and control strategies. The Electronic Brake Management EBM is an essential part of ICM and an important step to its development.

Wheel slip control system have found a remarkable penetration in all car segments. The information on the wheel behavior has lead to further developments which control the brake performance as well as the driving of the car in general. Latest systems introduced especially on luxury cars use wheel individual brake intervention to ensure vehicle stability under various driving maneuvers within the physical limits. Such systems use vehicle dynamic sensors and special hydraulics which serve as energy source for the automatic brake application. The technical effort of such systems like the Dynamic Stability Control DSC has limited the installation to upper class cars so far. New approaches are required to allow for a more wide spread penetration. Optimized hydraulics together with a rational design of the electronics seems to offer a basis for a more cost effective design.

The high penetration rate of ABS in nearly all categories of cars assisted the development of more sophisticated wheel slip control systems. Besides traction and stability control (Automatic Stability Control ASC at BMW) especially Driving Stability Control (DSC) is the most sophisticated stability control system currently under development. The combination of DSC with other chassis control systems, which use brake intervention, becomes more important. To reduce the technical effort of the different systems involved in chassis control, different ways can be considered. To allow for a wider application of a chassis control system network, a more radical approach with higher attention on cost savings is required. A possible solution is the development of an Electronic Brake Management EBM. Different attempts are possible with various electric or hydraulic actuation and modulation concepts.

Compared with its predecessor the chassis of the new 7-series BMW features a lot of technical changes [1]. As part of the chassis of the new car, the brake system and the wheel slip control systems are characterized by some new design solutions [2]. Different designs were chosen to fulfil the requirements of the respective versions of the 7-series. New aluminium calipers are used (730i) as well as 2-piston sliding calipers for the top model 750i. The actuation is designed in accordance with the long-stroke-principle. The same vacuum-booster and tandem master cylinder is used for all variants. The wheel slip control systems range from conventional ABS, Automatic Stability Control ASC to Dynamic Stability Control DSC. Firstly introduced in '92 in the 850Ci the second generation of DSC in the new 750i features Cornering Brake Control CBC as an additional ‘active’ function.

The Dynamic Stability Control DSC is a BMW stability and traction control system. To overcome performance limits of conventional systems which rely on wheel speed sensor information only, the DSC was extended by the steering wheel position signal. The new system allows a classification of self steering behaviour and thus leads to a better recognition of the respective driving situation. Control commands of the three control circuits throttle, ignition and brake lead to considerable better stabilization of the car during critical driving maneuvres. The BMW 850 Ci is available with DSC. The DSC was compared with the convential Automatic Stability Control System ASC under various test conditions on high- and low-μ surfaces. Test results are presented and discussed. A system description together with the theoretical background of the DSC is given.