Directional Stability of a Front Wheel Drive Passenger Car with Preemptive Use of the Direction Sensitive Locking Differential (DSLD)

Paper i proceeding, 2020

The topic of this paper is the bigger picture of vehicle dynamics and handling characteristics of cars, with a focus on driving safety. More specifically, the directional stability gain obtained using the semi-active differential (DSLD) is experimentally verified in transient steering maneuvers using a prototype in a FWD Saab 9-3 Aero. Stemming from the obvious need to enable low speed maneuvering, the open differential was developed already in the beginning of the automotive era and it has ever since maintained a position as the unquestioned solution almost irrespective of the driving situation. However, due to the inherent compromise between low speed maneuverability and high speed stability in road vehicle design, there are fundamental benefits of locking the differential more or less preemptively during for example expressway driving. In recent decades electronic stability control (ESC) has become the go-to solution to improve driving safety by increasing the directional stability in transient maneuvers. However, similar but significantly greater stability gains can be accomplished by utilizing controllable differentials. All in all this means that the mentioned inherent compromise between maneuverability and stability can be circumvented and the overall handling characteristics of cars can be fundamentally improved.