In order to evaluate an obstacle avoidance performance of a vehicle, behavior was studied in steering maneuver, such as lane change.

A vehicle with four wheel steering (4WS) was found to contrihute to improvement of the vehicle transient response in steering maneuver on a dry road surface. On a slippery road surface, 4WS was also effective to improve vehicle maneuverability.

Effect of traction force control to front and rear wheels on vehicle dynamics was also discussed.