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The first step toward a braking system ‘by wire’ is Electro-Hydraulic Braking System (EHB). The paper describes a method to evaluate through virtual experimentation the actual improvement in vehicle behaviour, from the point of view of both handling and comfort, including also pedal feeling, due to EHB. The first step consisted in modelling the hydraulic unit, comprehensive of sensors. Then it was conceived a control logic devoted to medium-low intensity braking manoeuvres, without ABS intervention, to determine an optimal braking force distribution and pedal feeling depending on the manoeuvre. A failsafe strategy, complete of on board diagnosis, to prevent dangerous system behaviour in the eventuality of a component failure was carried out and tested. Finally, EHB wheel pressure sensors were used to improve both ABS performance, increasing the adherence estimation, and Vehicle Dynamics Control (VDC) performance, through a more precise actuation.

The attention to the perceived quality, e.g. the quality as it is evaluated by the final customer, is becoming more and more important for the car makers. The paper describes how such aspects of braking system feel quality, joined with brake thermal constraints and interactions with other vehicle subsystems, such as suspensions, tyres and rims, can become manageable by an engineering process. In order to do that experienced designers define: longitudinal brake performance, stability limits in braking in a turn by comparison with referenced cars; brake thermal constraints; brake system constraints due to interactions with other vehicle subsystems. For perceived quality, on the other hand, it's necessary to take a different kind of approach in order to define targets.