Active Roll Control to Increase Handling and Comfort

The paper deals with the elaboration of an Active Roll Control (ARC) oriented both on comfort and handling improvement. The ARC determines hydraulically the variation of the equivalent stiffness of the anti-roll bars. The control strategies conceived were extensively validated through road tests managed on an Alfa Romeo sedan. The first part of the paper deals with comfort improvement, mainly consisting in an absence of bar effect during straight-ahead travel and in a modification of the roll characteristic of the car. To increase driver's handling feeling, it was necessary to optimise the ratio between front and rear roll stiffness. This purpose can be reached through control strategies based exclusively on lateral acceleration. Some control strategy corrections were necessary to optimise roll damping and front/rear roll stiffness balancing. A control logic, based on yaw rate and vehicle sideslip angle estimation, was introduced, with the main purpose of optimise yaw damping during transient manoeuvres. Road tests extensively managed validated the efficiency of active roll control strategies conceived. Finally the paper presents some example of integrations with other chassis control systems, like Vehicle Dynamics Control (VDC). The most important results obtained, both in simulation and during road tests, are presented and discussed.