Ford Motor Company Limited

Jahanbakhsh Asgari

Davorin David Hrovat

Minh N Tran

Michael G Fodor

Method, for use in a vehicle including a four wheel steering system and an electronic control unit having memory, of controlling the four wheel steering system while at least one of the wheels is under a torque load such that the vehicle behaves like a front wheel steering vehicle under no torque load, or a four wheel steering vehicle under no torque load. The method includes determining at least one control gain for the four wheel steering system so that the torque loaded vehicle behaves like a front wheel steering vehicle under no torque load, and controlling the four wheel steering system according to the control gain, thereby improving directional stability of the vehicle travelling on a slippery road surface. Apparatus is provided for carrying out the method.

Method and apparatus for four wheel steering control

A vehicle traction controller controls vehicle traction and directional stability by determining the rotational velocity of the vehicle. The rotational velocity of the vehicle is measured and compared to a predefined range. If the rotational velocity is outside of the predefined range, then a wheel torque value, which is indicative of a braking force to be applied independently of driver initated braking, is generated for each wheel which is on a side of the vehicle as determined by the rotational velocity. The wheel torque value is compared to a range of values, which is based on road surface friction, and altered if the wheel torque value is outside of the range of values. Wheel spin and skid control is employed to reduce wheel spin and skid.

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Detroit, MI, United States of America

Jahanbakhsh Asgari