Fluid-pressure and analogous brake systems – Speed-controlled – With yaw control
Reexamination Certificate
2001-01-26
2001-09-04
Graham, Matthew C. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
With yaw control
Reexamination Certificate
active
06283560
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a braking force control system for an automotive vehicle, which can improve vehicle cornering stability by applying an appropriate braking force to a vehicle wheel during vehicle cornering.
2. Description of the Prior Art
In recent years, various braking force control systems for improving vehicle cornering stability have been developed and further put to practical use, by which an appropriate braking force can be applied to the vehicle wheel on the basis of some forces applied to the vehicle during cornering.
For instance, in the case of Japanese Published Unexamined Patent Application No. 5-24422, a technique for applying an appropriate braking force to a predetermined vehicle wheel is disclosed such that a target yaw rate is calculated on the basis of steering wheel angle and vehicle speed, and further a target braking force is calculated under due consideration of cornering power of a vehicle model (determined in accordance with various vehicle items and equations of motion) on the basis of detected loads applied to the vehicle wheels so that the actual yaw rate can become closer to the target yaw rate.
In the above-mentioned prior art technique, however, since the braking force is so controlled that the actual yaw rate may become closer to the target yaw rate obtained by calculation, in case the target yaw rate is set to an erroneous value, the braking force is determined erroneously, with the result that there exists a possibility that the vehicle can be lead into spin or drifts out. Therefore, for instance, when the driver turns the steering wheel excessively (e.g., to its full lock angle) to keep the vehicle away from an obstruction on a slippery road, there exists a problem in that such a large target yaw rate at which a stable vehicle driving cannot be attained is set In addition, when a braking force is applied to the vehicle wheel in such a way that the actual yaw rate become closer to the target yaw rate, there exists a possibility that the vehicle can be lead into spin or drift out.
SUMMARY OF THE INVENTION
With these problems in mind, therefore, it is a object of the present invention to provide a braking force control system for automotive vehicle, by which the vehicle can be driven stably during cornering, without setting an excessive target braking force, even when the driver unavoidably turns the steering wheel excessively on a slippery road, for instance.
To achieve the above-mentioned object, the first aspect of the present invention provides a braking force control system, comprising: vehicle speed detecting means for detecting a vehicle speed; steering wheel angle detecting means for detecting a steering angle; actual yaw rate detecting means for detecting an actual vehicle yaw rate; lateral acceleration detecting means for detecting a lateral vehicle acceleration; vehicle body slip angular velocity calculating means for causing a computer to calculate a vehicle slip angular velocity on the basis of the detected vehicle speed, the detected actual vehicle yaw rate, and the detected lateral vehicle acceleration; steering wheel angle correcting means for causing a computer to correct the detected steering wheel angle on the basis of the calculated vehicle slip angular velocity; target yaw moment calculating means for causing a computer to calculate a target yaw moment on the basis of the detected actual vehicle yaw rate, the detected vehicle speed, and the steering wheel angle corrected by said steering wheel angle correcting means; braked wheel selecting means for causing a computer to select a wheel to be braked on the basis of the detected actual vehicle yaw rate and the target yaw moment calculated by said target yaw moment calculating means; target braking force calculating means for causing a computer to calculate a target braking force to be applied to the wheel selected by said braked wheel selecting means on the basis of the target yaw moment calculated by said target yaw moment calculating means; and braking signal outputting means for causing a computer to output a signal to a brake drive section, for application of the target braking force calculated by said target braking force calculating means to the wheel selected by said braked wheel selecting means.
Here, it is preferable that when the vehicle body slip angular velocity calculated on the basis of the detected vehicle speed, the detected actual vehicle yaw rate, and the detected lateral vehicle acceleration lies within a predetermined set value, said steering wheel angle correcting means outputs the value detected by said steering wheel angle detecting means as it is to said target yaw moment calculating means as a corrected value.
Further, the second aspect of the present invention provides a braking force control system, comprising: vehicle speed detecting means for detecting a vehicle speed; steering wheel angle detecting means for detecting a steering angle; actual yaw rate detecting means for detecting an actual vehicle yaw rate; lateral acceleration detecting means for detecting a lateral vehicle acceleration; vehicle body slip angle calculating means for causing a computer to calculate a vehicle body slip angle on the basis of the detected vehicle speed, the detected actual vehicle yaw rate, and the detected lateral vehicle acceleration; steering wheel angle correcting means for causing a computer to correct the detected steering wheel angle on the basis of the calculated vehicle body slip angle; target yaw moment calculating means for causing a computer to calculate a target yaw moment on the basis of the detected actual vehicle yaw rate, the detected vehicle speed, and the steering wheel angle corrected by said steering wheel angle correcting means; braked wheel selecting means for causing a computer to select a wheel to be braked on the basis of the detected actual vehicle yaw rate and the target yaw moment calculated by said target yaw moment calculating means; target braking force calculating means for causing a computer to calculate a target braking force to be applied to the wheel selected by said braked wheel selecting means on the basis of the target yaw moment calculated by said target yaw moment calculating means; and braking signal outputting means for causing a computer to output a signal to a brake drive section, for application of the target braking force calculated by said target braking force calculating means to the wheel selected by said braked wheel selecting means.
Here, it is preferable that when the vehicle body slip angle calculated on the basis of the detected vehicle speed, the detected actual vehicle yaw rate, and the detected lateral vehicle acceleration lies within a predetermined set value, said steering wheel angle correcting means outputs the value detected by said steering wheel angle detecting means as it is to said target yaw moment calculating means as a corrected value.
Further, the third aspect of the present invention provides a braking force control system, comprising: vehicle speed detecting means for detecting a vehicle speed; steering wheel angle detecting means for detecting a steering angle; actual yaw rate detecting means for detecting an actual vehicle yaw rate; lateral acceleration detecting means for detecting a lateral vehicle acceleration; vehicle body slip angular velocity calculating means for causing a computer to calculate a vehicle body slip angular velocity on the basis of the detected vehicle speed, the detected actual vehicle yaw rate, and the detected lateral vehicle acceleration; actual yaw rate correcting means for causing a computer to correct the detected actual vehicle yaw rate on the basis of the calculated vehicle body slip angular velocity; target yaw moment calculating means for causing a computer to calculate a target yaw moment on the basis of the detected vehicle speed, the detected steering angle, and the actual vehicle yaw rate corrected by said actual yaw rate correcting means; braked wheel selecting means for causing a com
Fuji Jukogyo Kabushiki Kaisha
Graham Matthew C.
Smith , Gambrell & Russell, LLP
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