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4 wheel Active Steer (4WAS), which controls all four steering angle, is developed first in the world. This system achieves dynamic performance with secure and invigoration feel on higher level, based on active steer technology of rear axle. This paper describes aim and necessity of all four steering control, and introduces outline and efforts of this system.

The influence on vehicle dynamics of braking force distribution to four wheels has been analyzed by computer simulation and experimentation. The analytical results indicate that a suitable braking force distribution control method can improve handling and stability during braking. A new braking force distribution cintrol strategy,using a steering wheel angle feedforward function and a yaw velocity feedback function,is shown to improve vehicle dynamic behavior.

It is said that a four-wheel drive (4WD) system which can control the distribution of driving torque to the front and rear axles will result in remarkably improved tractive and cornering performance. However, because of the difficulty in obtaining accurate vehicle speed information and in identifying the influence of engine brake torque on performance on slippery roads, it has been difficult to apply an anti-lock braking system (ABS) to vehicles equipped with such a 4WD system. This paper discusses a solution to this problem achieved through the utilization of a vehicle dynamic simulation model and a new integrated anti-lock and traction distribution control method. The existence of an optimum front/rear torque split which makes it possible to estimate vehicle speed accurately and to obtain the best level of ABS control performance is shown.