Steering and brake controlling system
First Claim
1. A method for controlling steering and braking of a vehicle in motion having brakes and a steering mechanism, and further having an actual yaw rate defined as the sideward velocity of the vehicle and a lateral acceleration defined as the sideward acceleration of the vehicle, and with respect to which one of a desired yaw rate, defined as the desired sideward velocity of the vehicle according to a control algorithm, and a desired lateral acceleration, defined as the desired lateral acceleration of the vehicle according to a control algorithm, is ascertained, comprising the steps of:
- measuring one of said actual yaw rate and said actual lateral acceleration;
deriving a corresponding one of said desired yaw rate and said desired lateral acceleration according to said control algorithm;
determining the corresponding one of a yaw rate error, defined as the difference between said actual yaw rate and said desired yaw rate, and a lateral acceleration error, defined as the difference between said actual lateral acceleration and said desired lateral acceleration; and
controlling steering and braking of said vehicle to reduce said one of said yaw rate error and said lateral acceleration error, whereby braking distance is reduced below a braking distance obtained using braking control alone to reduce said one of said yaw rate error and said lateral acceleration error.
1 Assignment
0 Petitions
Accused Products
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.
240 Citations
21 Claims
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1. A method for controlling steering and braking of a vehicle in motion having brakes and a steering mechanism, and further having an actual yaw rate defined as the sideward velocity of the vehicle and a lateral acceleration defined as the sideward acceleration of the vehicle, and with respect to which one of a desired yaw rate, defined as the desired sideward velocity of the vehicle according to a control algorithm, and a desired lateral acceleration, defined as the desired lateral acceleration of the vehicle according to a control algorithm, is ascertained, comprising the steps of:
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measuring one of said actual yaw rate and said actual lateral acceleration; deriving a corresponding one of said desired yaw rate and said desired lateral acceleration according to said control algorithm; determining the corresponding one of a yaw rate error, defined as the difference between said actual yaw rate and said desired yaw rate, and a lateral acceleration error, defined as the difference between said actual lateral acceleration and said desired lateral acceleration; and controlling steering and braking of said vehicle to reduce said one of said yaw rate error and said lateral acceleration error, whereby braking distance is reduced below a braking distance obtained using braking control alone to reduce said one of said yaw rate error and said lateral acceleration error. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A steering and braking control apparatus for a vehicle with respect to which an actual yaw rate is defined as the sideward velocity of the vehicle and a lateral acceleration defined as the sideward acceleration of the vehicle, and with respect to which one of a desired yaw rate, defined as the desired sideward velocity of the vehicle according to a control algorithm, and a desired lateral acceleration, defined as the desired lateral acceleration of the vehicle according to a control algorithm, is ascertained, comprising:
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steering angle regulating means for controlling a steering angle of said vehicle; brake pressure regulating means for controlling brake pressure of said vehicle; control means for controlling said steering angle regulating means and said brake pressure regulating means; and means for determining and sending to said control means one of a yaw rate error, defined as the difference between said actual yaw rate and said desired yaw rate, and a lateral acceleration error, defined as the difference between said actual lateral acceleration and said desired lateral acceleration, said control means controlling said steering angle regulating means and said brake pressure regulating means according to said one of said yaw rate error and said lateral acceleration error. - View Dependent Claims (18, 19, 20, 21)
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Specification