Importance

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Abstract

Steering and braking are coordinated and controlled according to a sensed yaw rate error or lateral acceleration error to increase vehicle stability without increasing braking distance. A desired yaw rate or lateral acceleration rate is computed from the vehicle velocity and the steering wheel angle. If the yaw rate or the lateral acceleration is excessive, indicating instability, and the brakes are being operated, then both steering and braking are controlled to reduce the yaw rate or lateral acceleration rate. In all other cases, steering control alone is performed. The yaw rate or lateral acceleration rate is reduced under steering control by adjusting wheel positions in a direction opposite the direction of yaw or lateral acceleration. The control system of the present invention is applicable to both two-wheel and four-wheel steering and braking. The yaw rate or lateral acceleration is further reduced under braking control by decreasing brake pressure on a side of the vehicle corresponding to the direction of yaw or lateral acceleration and increasing brake pressure on the opposite side of the vehicle. In the case of anti-lock brakes, pressure is not increased beyond a slip rate threshold. Rather than controlling brake pressure, the slip rate threshold itself may be controlled in like manner to reduce the yaw rate or lateral acceleration.

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First Claim