A vehicle lateral control approach for collision avoidance by emergency steering maneuvers

Many accidents lead back to the driver. It is assumed to be beneficial that driver assistance systems and/or automated driving functions ease tension off the driver or release him from the task of driving in order to reduce traffic fatalities. The development of driver assistance systems started with ABS (Anti-Lock Braking System) in 1978, TC (Traction Control) in 1987 and ESC (Electronic Stability Control) in 1995. These systems are known for their contribution on the reduction of traffic fatalities over the last years. But still far too many cars crash every day. The aforementioned systems do not take environmental information into account, which limits the collision avoidance potential. A system that senses its environment by radar and/or camera sensors is the AEB (Autonomous Emergency Braking) which is supposed to further reduce the amount of accidents in the future as the take rate increases. Although assisting the driver in emergency situations by braking is beneficial in some situations, it also has its drawbacks. The problem is that emergency braking can only be initiated if the obstacle is detected for sure. Nowadays sensors can only provide limited safe ranges. This means that at typical highway speeds the collision with a stationary obstacle can only be mitigated by braking. A swerving maneuver is a viable alternative to braking or the combination of both if the required space is not occupied by other obstacles. The emergency steering maneuver offers the advantage that the last-point-to-steer is even closer to the obstacle than the last-point-to-brake with growing vehicle speed, which yields a higher collision avoidance potential. The disadvantage is that the maneuver is far more difficult than full braking. A subject study [1] in a driving simulator has proven that the average skilled driver is not capable of steering the vehicle properly around obstacles in the majority of occasions. This is why an advanced driver assistance system (ADAS) is useful that supports the driver by steering torque overlay and, as an option, by braking interventions. The improvement on the collision avoidance behaviour of the driver has been proven by the authors in the aforementioned study [1].