Braking force control system and the method thereof

A braking force control system of a vehicle, having a front wheel, a rear wheel, a front wheel cylinder for said front wheel, a rear wheel cylinder for said rear wheel and a brake drive apparatus for supplying and controlling a 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:

• target yaw rate gain calculating means for calculating a target yaw rate gain based on said vehicle speed;
• actual yaw rate detecting means for detecting an actual yaw rate;
• target yaw rate calculating means for calculating a target yaw rate based on said vehicle speed, said steering angle and said target yaw rate gain;
• estimated yaw rate gain calculating means for calculating an estimated yaw rate gain based on said vehicle speed;
• estimated yaw rate calculating means for calculating an estimated yaw rate under an estimated running condition based on said estimated yaw rate gain and said steering angle;
• target yaw rate differential calculating means for calculating a target yaw rate differential;
• estimated yaw rate differential calculating means for calculating an estimated yaw rate differential;
• yaw rate differential deviation calculating means for calculating a yaw rate differential deviation of said target yaw rate differential and said estimated yaw rate differential;
• first target braking force calculating means for calculating a first target braking force for said front wheel and a first target braking force for said rear wheel respectively based on said yaw rate differential deviation;
• yaw rate deviation calculating means for calculating a yaw rate deviation of said actual yaw rate and said target yaw rate;
• second target braking force calculating means for calculating a second target braking force for said front wheel and a second target braking force for said rear wheel respectively based on said yaw rate deviation, said steering angle, said target yaw rate gain, said vehicle speed and said actual yaw rate;
• final target braking force calculating means for calculating a final target braking force for said front wheel based on said first target braking force for said front wheel and said second target braking force for said front wheel and for calculating a final target braking force for said rear wheel based on said first target braking force for said rear wheel and second target braking force for said rear wheel;
• 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 the side of a turning center is selected when said actual yaw rate differs from said yaw rate deviation in sign and such that said front wheel on the 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 determining a judging threshold value of said yaw rate deviation and for judging whether or not said yaw rate deviation is in a control zone by comparing said yaw rate with said judging threshold value;
• and
• brake signal outputting means for outputting a brake signal to said brake drive apparatus so as to apply said final target braking force to said braking wheel.