Interaction design of automatic steering for collision avoidance: challenges and potentials of driver decoupling

Studies concerning collision avoidance show that most drivers tend to brake, even if evasive manoeuvres were better. Automatic steering for collision avoidance would help here. Studies in the EU project interactIVe observed that drivers show a tendency to hold the steering wheel and disturb the automatic steering when kept in the control loop. A strategy of driver decoupling, for example, by means of steer-by-wire systems could improve the automatic steering performance. However, the major challenge of using steer-by-wire systems is to enable the driver to compensate false system activation, for example, evasion into oncoming traffic. A time-dependent strategy of driver decoupling using steer-by-wire combined with override recognition by counter steering above a certain threshold was implemented in a research vehicle. The interaction strategy was tested with 45 participants on a test track in two different scenarios; a collision situation with justified evasion and a false alert scenario with unjustified system activation. In a between-subject design the decoupling strategy (using steer-by-wire) was compared against automatic steering with fully coupled driver and force feedback on the steering wheel and against Manual Driving without automatic steering. When the driver was temporarily decoupled, the obstacle avoidance performance was better but the driver was less able to counteract a false avoidance manoeuvre. The analysis of driver behaviour revealed options to improve the interaction strategy.