Abstract
To clarify the temporal limitation of the driver's steering behavior to avoid an obstacle ahead, avoidance maneuvers and results of avoidance operation were examined under the condition where the obstacle appearing timing was directly controlled on a driving simulator. All 25 subject drivers successfully avoided the obstacle when the time margin was longer than 3.0 seconds, though no drivers were able to avoid collision when the time margin was 1.2 seconds or shorter. When the driver was expecting an obstacle, it was confirmed that the steering latency decreased and the steering velocity increased as the time margin becomes shorter. The driver's minimum latency was estimated around 0.3 seconds and the maximum steering velocity around 500 degrees/second. However, the performance to avoid an obstacle deteriorated and the ratio of successful avoidance decreased when the driver was not anticipating appearance of an obstacle.
