Braking force control system for turning having correction parameters capabilities and method thereof

• US 6,074,020 A
• Filed: 11/13/1996
• Issued: 06/13/2000
• Est. Priority Date: 12/13/1995
• Status: Expired due to Fees

• Current Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Takahashi, Akira, Matsuno, Koji, Matsuura, Munenori, Hiwatashi, Yutaka
• Primary Examiner(s): Graham, Matthew C.
• Application Number:
  US08/748,410
• Time in Patent Office: 1,308 Days
• Field of Search: 303/146, 303/147, 303/148, 303/149, 303/141
• US Class Current: 303/146
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02

Abstract

A braking force control system and method of a vehicle includes a vehicle speed detecting section, a steering angle detecting section, a yaw rate detecting section, a target yaw rate calculating section, a yaw rate deviation calculating section, turning requirement detecting means for detecting a driver'"'"'s requirement to turn the vehicle, brake pressure correction coefficient generating section, a target braking force calculating section, a braking force correction section for correcting the braking force according to the driver'"'"'s requirement to turn the vehicle, a braking wheel determining section for determining an object wheel to apply brakes, an output judging section, a brake signal outputting section and a brake drive apparatus for applying brake pressure to the wheel cylinder of the object wheel. Whereby, the driver can make a sharp turn even when the normal braking force control is operative.

Claims

1. A braking force control system of a vehicle, having a front wheel, a rear wheel, a front wheel cylinder for braking said front wheel, a rear wheel cylinder for braking said rear wheel, a brake drive apparatus for supplying and controlling brake pressure to said front wheel cylinder and said rear wheel cylinder, vehicle speed detecting means for detecting a vehicle speed, steering angle detecting means for detecting a steering angle, and yaw rate detecting means for detecting an actual yaw rate of said vehicle, comprising:

yaw rate gain calculating means for calculating a yaw rate gain based on said vehicle speed;

target yaw rate calculating means for calculating a target yaw rate based on said vehicle speed, said steering angle and said yaw rate gain;

yaw rate deviation calculating means for calculating a yaw rate deviation of said target yaw rate from said actual yaw rate;

turning requirement detecting means for detecting a driver'"'"'s requirement to make a positive turn of said vehicle and for outputting a requirement magnitude signal representing a magnitude of said driver'"'"'s requirement;

brake pressure correction coefficient generating means for generating a brake pressure correction coefficient corresponding to said requirement magnitude signal;

target braking force calculating means for calculating a target braking force based on said yaw rate deviation, said steering angle, said yaw rate gain, said vehicle speed and said actual yaw rate;

braking force correcting means for correcting said target braking force with said brake pressure correction coefficient such that said target braking force of said front wheel is corrected to a smaller value and said target braking force of said rear wheel is corrected to a larger value and for outputting a corrected target braking force;

braking wheel determining means for determining a braking wheel based on said actual yaw rate and said yaw rate deviation such that said rear wheel on a side of a turning center is selected as said braking wheel when said actual yaw rate differs from said yaw rate deviation in sign and such that said front wheel on an opposite side of a turning center is selected when said actual yaw rate agrees with said yaw rate deviation in sign;

output judging means for selectively determining a judging threshold value based on said yaw rate deviation, said actual yaw rate and said vehicle speed, for outputting a control signal so as to execute a braking force control when an absolute value of said yaw rate deviation is larger than said threshold value and for outputting a noncontrol signal so as to stop a braking force control when said absolute value of said yaw rate deviation is smaller than said threshold value; and

brake signal outputting means responsive to said control signal for outputting a brake signal to said brake drive apparatus so as to apply said target braking force to said braking wheel and responsive to said noncontrol signal for stopping said brake signal to said brake drive apparatus.

2. The braking force control system according to claim 1, wherein

said requirement magnitude signal is a signal representing a throttle valve opening angle.

3. The braking force control system according to claim 1, wherein

said requirement magnitude signal is a signal representing a rotational speed of a steering wheel.

4. The braking force control system according to claim 1, wherein

said brake pressure correction coefficient is selectable from a plurality of brake pressure correction coefficients.

5. The braking force control system according to claim 1, wherein

said yaw rate correction coefficient is selectable from a plurality of yaw rate correction coefficients.

6. A braking force control system of a vehicle, having a front wheel, a rear wheel, a front wheel cylinder for braking said front wheel, a rear wheel cylinder for braking said rear wheel, a brake drive apparatus for supplying and controlling brake pressure to said front wheel cylinder and said rear wheel cylinder, vehicle speed detecting means for detecting a vehicle speed, and steering angle detecting means for detecting a steering angle, comprising:

a mode selector switch for selecting either a sport mode or a normal mode;

yaw rate detecting means for detecting an actual yaw rate of said vehicle;

yaw rate gain calculating means for calculating a yaw rate gain based on said vehicle speed;

turning requirement detecting means for detecting a driver'"'"'s requirement to make a positive turn of said vehicle and for outputting a requirement magnitude signal representing a magnitude of said driver'"'"'s requirement;

yaw rate correction coefficient generating means for generating a yaw rate correction coefficient corresponding to said requirement magnitude signal;

target yaw rate calculating means for calculating a target yaw rate based on said vehicle speed, said steering angle and said yaw rate gain;

target yaw rate correcting means for correcting said target yaw rate with said yaw rate correction coefficient such that said target yaw rate increases with an increase of said requirement magnitude signal when said mode selector switch is changed over to said sport mode and for passing said target yaw rate without correcting said target yaw rate when said mode selector switch is changed over to said normal mode;

yaw rate deviation calculating means for calculating a yaw rate deviation of said target yaw rate output from said target yaw rate correcting means from said actual yaw rate;

brake pressure correction coefficient generating means for generating a brake pressure correction coefficient corresponding to said requirement magnitude signal;

target braking force calculating means for calculating a target braking force based on said yaw rate deviation, said steering angle, said yaw rate gain, said vehicle speed and said actual yaw rate;

braking force correcting means for correcting said target braking force with said brake pressure correction coefficient such that said target braking force of said front wheel is corrected to a smaller value and said target braking force of said rear wheel is corrected to a larger value when said mode selector switch is changed over to said sport mode and for passing said target braking force without correcting said target braking force when said mode selector switch is changed over to said normal mode;

braking wheel determining means for determining a braking wheel based on said actual yaw rate and said yaw rate deviation such that said rear wheel on a side of a turning center is selected as said braking wheel when said actual yaw rate differs from said yaw rate deviation in sign and such that said front wheel on an opposite side of a turning center is selected when said actual yaw rate agrees with said yaw rate deviation in sign;

output judging means for selectively determining a judging threshold value based on said yaw rate deviation, said actual yaw rate and said vehicle speed, for outputting a control signal so as to execute a braking force control when an absolute value of said yaw rate deviation is larger than said threshold value and for outputting a noncontrol signal so as to stop a braking force control when said absolute value of said yaw rate deviation is smaller than said threshold value; and

brake signal outputting means responsive to said control signal for outputting a brake signal to said brake drive apparatus so as to apply said target braking force to said braking wheel and responsive to said noncontrol signal for stopping said brake signal to said brake drive apparatus.

7. The braking force control system according to claim 6, wherein

said requirement magnitude signal is a signal representing a throttle opening angle.

8. The braking force control system according to claim 6, wherein

said requirement magnitude signal is a signal representing a rotational speed of a steering wheel.

9. The braking force control system according to claims 8, wherein

said brake pressure correction coefficient is selectable from a plurality of brake pressure correction coefficients.

10. The braking force control system according to claim 6, wherein

said yaw rate correction coefficient is selectable from a plurality of yaw rate correction coefficients.

11. A braking force control method of a vehicle, having a front wheel, a rear wheel, a front wheel cylinder for braking said front wheel, a rear wheel cylinder for braking said rear wheel, a brake drive apparatus for supplying and controlling brake pressure to said front wheel cylinder and said rear wheel cylinder, vehicle speed detecting means for detecting a vehicle speed, and steering angle detecting means for detecting a steering angle, comprising the steps of:

detecting an actual yaw rate of said vehicle;

calculating a yaw rate gain based on said vehicle speed;

calculating a target yaw rate based on said vehicle speed, said steering angle and said yaw rate gain;

calculating a yaw rate deviation of said target yaw rate from said actual yaw rate;

detecting a driver'"'"'s requirement to make a positive turn of said vehicle and for outputting a requirement magnitude signal representing a magnitude of said driver'"'"'s requirement;

generating a brake pressure correction coefficient corresponding to said requirement magnitude signal;

calculating a target braking force based on said yaw rate deviation, said steering angle, said yaw rate gain, said vehicle speed and said actual yaw rate;

correcting said target braking force with said brake pressure correction coefficient such that said target braking force of said front wheel is corrected to a smaller value and said target braking force of said rear wheel is corrected to a larger value and for outputting a corrected target braking force;

determining a braking wheel based on said actual yaw rate and said yaw rate deviation such that said rear wheel on a side of a turning center is selected as said braking wheel when said actual yaw rate differs from said yaw rate deviation in sign and such that said front wheel on an opposite side of a turning center is selected when said actual yaw rate agrees with said yaw rate deviation in sign;

determining selectively a judging threshold value based on said yaw rate deviation, said actual yaw rate and said vehicle speed, outputting a control signal so as to execute a braking force control when an absolute value of said yaw rate deviation is larger than said threshold value and outputting a noncontrol signal so as to stop a braking force control when said absolute value of said yaw rate deviation is smaller than said threshold value; and

outputting a brake signal to said brake drive apparatus so as to apply said target braking force to said braking wheel and stopping said brake signal to said brake drive apparatus.

12. A braking force control method of a vehicle, having a front wheel, a rear wheel, a front wheel cylinder for braking said front wheel, a rear wheel cylinder for braking said rear wheel, a brake drive apparatus for supplying and controlling brake pressure to said front wheel cylinder and said rear wheel cylinder, vehicle speed detecting means for detecting a vehicle speed, and steering angle detecting means for detecting a steering angle, comprising the steps of:

selecting either a sport mode or a normal mode;

detecting an actual yaw rate of said vehicle;

calculating a yaw rate gain based on said vehicle speed;

detecting a driver'"'"'s requirement to make a positive turn of said vehicle and for outputting a requirement magnitude signal representing a magnitude of said driver'"'"'s requirement;

generating a yaw rate correction coefficient corresponding to said requirement magnitude signal;

calculating a target yaw rate based on said vehicle speed, said steering angle and said yaw rate gain;

correcting said target yaw rate with said yaw rate correction coefficient such that said target yaw rate increases with an increase of said requirement magnitude signal when said mode selector switch is changed over to said sport mode and passing said target yaw rate without correcting said target yaw rate when said mode selector switch is changed over to said normal mode;

calculating a yaw rate deviation of said target yaw rate from said actual yaw rate;

generating a brake pressure correction coefficient corresponding to said requirement magnitude signal;

calculating a target braking force based on said yaw rate deviation, said steering angle, said yaw rate gain, said vehicle speed and said actual yaw rate;

correcting said target braking force with said brake pressure correction coefficient such that said target braking force of said front wheel is corrected to a smaller value and said target braking force of said rear wheel is corrected to a larger value when said mode selector switch is changed over to said sport mode and for passing said target braking force without correcting said target braking force when said mode selector switch is changed over to said normal mode;

determining a braking wheel based on said actual yaw rate and said yaw rate deviation such that said rear wheel on a side of a turning center is selected as said braking wheel when said actual yaw rate differs from said yaw rate deviation in sign and such that said front wheel on an opposite side of a turning center is selected when said actual yaw rate agrees with said yaw rate deviation in sign;

determining selectively a judging threshold value based on said yaw rate deviation, said actual yaw rate and said vehicle speed, outputting a control signal so as to execute a braking force control when an absolute value of said yaw rate deviation is larger than said threshold value and outputting a noncontrol signal so as to stop a braking force control when said absolute value of said yaw rate deviation is smaller than said threshold value; and

outputting a brake signal to said brake drive apparatus so as to apply said target braking force to said braking wheel and stopping said brake signal to said brake drive apparatus.

13. A braking control system for a vehicle having front and rear wheels, comprising:

a yaw rate detector for detecting an actual yaw rate of the vehicle;

detecting means for detecting running conditions of the vehicle;

target yaw rate calculating means for calculating a target yaw rate based on said vehicle running conditions;

target braking force calculating means for calculating target braking forces for said front and rear wheels so as to accord said actual yaw rate with said target yaw rate;

turning adjustment detecting means for adjusting operation of the braking control system in response to an adjustment requirement by a driver, the turning adjustment detecting means producing an adjustment signal in response to an input by the driver;

turning amount correcting means for correcting at least one of said target yaw rate and said target braking forces in response to the adjustment signal; and

a brake drive apparatus provided to control brake pressure to be applied to each wheel cylinder depending on said target braking forces.

14. The braking control system according to claim 13, further comprising:

a mode selector switch provided to select either a first mode to execute a braking control in accordance with the correction performed by said turning amount correcting means or a second mode to execute a braking control without the correction performed by said turning amount correcting means.

15. The braking control system according to claim 14, wherein said turning amount correcting means is adapted to correct both said target braking forces and said target yaw rate when said first mode is selected.

16. The braking control system according to claim 13, wherein said turning amount correcting means is adapted to correct a target braking force for a front wheel to decrease and to correct a target braking force for a rear wheel to increase.

17. The braking control system according to claim 16, wherein said turning adjustment detecting means is adapted to produce the adjustment signal based on a throttle valve opening degree.

18. The braking control system according to claims 17, wherein the magnitude of correction of said target braking forces for said front and rear wheels is changed depending on said throttle valve opening degree.