Brake controlling system

Abstract

The present invention relates to an apparatus and method for controlling vehicle motion. More specifically, the invention relates to an apparatus for improving vehicle stability by controlling the brake torque of a vehicle during, for example, cornering manuevers. In accordance with the present invention, vehicle stability is improved by independently controlling brake torque in response to sensed yaw rate.

What is claimed is:  
     
       1. An apparatus for controlling a vehicle having a plurality of wheels and a brake pedal, comprising: 
       means responsive to the influence of destabilizing forces on a vehicle for measuring an actual yaw rate of said vehicle;  
       means for determining a dynamically variable target yaw rate of said vehicle and for producing an output signal in response to a comparison of said target yaw rate and said actual yaw rate; and  
       brake controlling means, responsive to said output signal, for maintaining stability of the vehicle when said vehicle is in motion to control a braking force applied to at least one of said plurality of wheels in the absence of brake pedal input, said brake controlling means including brake fluid pressure modulator means which responds to said output signal to modulate a braking force applied to at least one wheel on one side of said vehicle differently relative to a braking force applied to at least one wheel on an opposite side of said vehicle.  
     
     
       2. The apparatus of  claim 1 , wherein said means for determining the desired  target yaw rate includes a first sensor means for detecting a steering angle of said vehicle; and, 
       a second sensor means for detecting vehicle speed.  
     
     
       3. The apparatus of  claim 2 , wherein said vehicle includes a plurality of wheels, and said second sensor means includes a wheel speed sensor for detecting the speed of rotation of each of said plurality of wheels. 
     
     
       4. The apparatus of  claim 2 , wherein said means for measuring said actual yaw rate of said vehicle includes a yaw rate gyro. 
     
     
       5. The apparatus of  claim 2 , wherein said means for measuring said actual yaw rate of said vehicle includes a pair of side-direction G sensors. 
     
     
       6. The apparatus of  claim 1 , wherein said brake controlling means includes a brake fluid pressure modulator means which responds to said output signal to modulate a braking force applied to wheels on one side of said vehicle relative to a braking force applied to wheels on an opposite side of said vehicle, so as to counteract any influence of lateral forces. 
     
     
       7. The apparatus of  claim 6 , wherein said braking force applied to said wheels on one side of said vehicle relative to said braking force applied to said wheels on said opposite side of said vehicle is modulated in the absence of brake pedal input to said vehicle. 
     
     
       8. The apparatus of claim  6   1 , wherein said brake fluid pressure modulator means counteracts any influence of lateral forces by only modulating a braking force applied to wheels on one side of said vehicle. 
     
     
       9. The apparatus of claim  6   1 , wherein said brake fluid pressure modulator means counteracts any influence of lateral forces by increasing the braking force applied to said one side of said vehicle while simultaneously decreasing the braking force applied to said opposite side of said vehicle. 
     
     
       10. A method for controlling vehicle motion of a vehicle in which the vehicle has a plurality of wheels and a brake pedal, comprising the steps of: 
       detecting an actual yaw rate of a vehicle;  
       determining a dynamically variable target yaw rate of said vehicle;  
       comparing said actual yaw rate with said target yaw rate to produce an output signal; and  
       maintaining vehicle stability in response to said output signal during an influence of lateral forces on said vehicle by controlling a braking force applied to at least one of said plurality of wheels in the absence of brake pedal input so as to modulate a braking force applied to at least one wheel on one side of said vehicle differently relative to a braking force applied to at least one wheel on an opposite side of said vehicle.  
     
     
       11. The method of  claim 10 , wherein said step of maintaining includes the step of: 
       controlling brake fluid pressure so as to modulate a braking force applied to wheels on one side of said vehicle relative to a braking force applied to wheels on an opposite side of said vehicle.  
     
     
       12. The method of claim  11   10 , wherein said step of controlling includes only modulating the braking force on either said one side of said vehicle or on said opposite side of said vehicle. 
     
     
       13. The method of claim  11   10 , wherein said step of controlling includes simultaneously modulating the braking force on both said one side of said vehicle and said opposite side of said vehicle. 
     
     
       14. An apparatus for controlling vehicle motion of a vehicle in which the vehicle has a plurality of wheels and a brake pedal, comprising: 
       means for measuring an actual yaw rate of a vehicle;  
       means for determining a dynamically variable target yaw rate of said vehicle;  
       means responsive to said measuring means and said determining means for producing an output signal in response to a comparison of said target yaw rate and said actual yaw rate; and  
       brake controlling means, responsive to said output signal, for maintaining vehicle stability at least partially in response to said output signal to control a braking force applied to at least one of said plurality of wheels in the absence of brake pedal input, said brake controlling means including brake fluid pressure modulator means which responds to said output signal to modulate a braking force applied to at least one wheel on one side of said vehicle differently relative to a braking force applied to at least one wheel on an opposite side of said vehicle.  
     
     
       15. The apparatus of  claim 1 , wherein said means for determining a dynamically variable target yaw rate of said vehicle determines the dynamically variable target yaw rate of said vehicle using utilizing an understeer coefficient greater than zero. 
     
     
       16. The apparatus of  claim 1 , wherein said brake controlling means applies a braking force to only at least one of the wheels located on an outside of a curved path of travel of the vehicle when it is determined that the vehicle is in an oversteer condition in response to said comparison of said target yaw rate and said actual yaw rate. 
     
     
       17. The apparatus of  claim 1 , wherein said brake controlling means applies a braking force to at least one of the wheels located on an inside of a curved path of travel of the vehicle when it is determined that the vehicle is in an understeer condition in response to said comparison of said target yaw rate and said actual yaw rate. 
     
     
       18. The method of  claim 10 , wherein the dynamically variable target yaw rate of said vehicle is determined utilizing an understeer coefficient greater than zero. 
     
     
       19. The method of  claim 10 , wherein when said brake force is controlled by applying a braking force to only at least one of the wheels located on an outside of a curved path of travel of the vehicle when it is determined that the vehicle is in an oversteer condition in response to said comparison of said target yaw rate and said actual yaw rate. 
     
     
       20. The method of  claim 10 , wherein said brake force is controlled by applying a braking force to at least one of the wheels located on an inside of a curved path of travel of the vehicle when it is determined that the vehicle is in an understeer condition in response to said comparison of said target yaw rate and said actual yaw rate. 
     
     
       21. The apparatus of  claim 14 , wherein said means for determining a dynamically variable target yaw rate of said vehicle determines the dynamically variable target yaw rate of said vehicle using utilizing an understeer coefficient greater than zero. 
     
     
       22. The apparatus of  claim 14 , wherein said brake controlling means applies a braking force to only at least one of the wheels located on an outside of a curved path of travel of the vehicle when it is determined that the vehicle is in an oversteer condition in response to said comparison of said target yaw rate and said actual yaw rate. 
     
     
       23. The apparatus of  claim 14 , wherein said brake controlling means applies a braking force to at least one of the wheels located on an inside of a curved path of travel of the vehicle when it is determined that the vehicle is in an understeer condition in response to said comparison of said target yaw rate and said actual yaw rate. 
     
     
       24. An apparatus for controlling a vehicle having a plurality of wheels, comprising: 
       
         means responsive to the influence of destabilizing forces on a vehicle for measuring an actual yaw rate of said vehicle;  
       
       
         means for determining a dynamically variable target yaw rate of said vehicle and for producing an output signal in response to a comparison of said target yaw rate and said actual yaw rate; and  
       
       
         brake controlling means, responsive to said output signal, for maintaining stability of the vehicle when said vehicle is in motion by controlling a braking force applied to at least one of said plurality of wheels during acceleration of said vehicle and while said vehicle is cornering, said brake controlling means including brake fluid pressure modulator means which responds to said output signal to modulate a braking force applied to at least one wheel on one side of said vehicle differently relative to a braking force applied to at least one wheel on an opposite side of said vehicle. 
       
     
     
       25. The apparatus of  claim 24 , wherein said brake controlling means applies a braking force to at least one of the wheels located on an outside of a curved path of travel of the vehicle when said actual yaw rate is greater than said target yaw rate. 
     
     
       26. The apparatus of  claim 24 , wherein said brake controlling means applies a braking force to at least one of the wheels located on an inside of a curved path of travel of the vehicle when said actual yaw rate is less than said target yaw rate. 
     
     
       27. An apparatus for controlling vehicle motion of a vehicle in which the vehicle has a plurality of wheels, comprising: 
       
         means for measuring an actual yaw rate of a vehicle;  
       
       
         means for determining a dynamically variable target yaw rate of said vehicle;  
       
       
         means responsive to said measuring means and said determining means for producing an output signal in response to a comparison of said target yaw rate and said actual yaw rate; and  
       
       
         brake controlling means, responsive to said output signal, for maintaining vehicle stability at least partially in response to said output signal by controlling a braking force applied to at least one of said plurality of wheels during acceleration of said vehicle and while said vehicle is cornering, said brake controlling means including brake fluid pressure modulator means which responds to said output signal to modulate a braking force applied to at least one wheel on one side of said vehicle differently relative to a braking force applied to at least one wheel on an opposite side of said vehicle. 
       
     
     
       28. The apparatus of  claim 27 , wherein said brake controlling means applies a braking force to at least one of the wheels located on an outside of a curved path of travel of the vehicle whenever said actual yaw rate is greater than said target yaw rate. 
     
     
       29. The apparatus of  claim 27 , wherein said brake controlling means applies a braking force to at least one of the wheels located on an inside of a curved path of travel of the vehicle when said actual yaw rate is less than said target yaw rate. 
     
     
       30. An apparatus for controlling a vehicle having a plurality of wheels and a brake pedal, comprising: 
       
         means responsive to the influence of destabilizing forces on a vehicle for measuring an actual yaw rate of said vehicle;  
       
       
         means for determining a dynamically variable target yaw rate of said vehicle and for producing an output signal in response to a comparison of said target yaw rate and said actual yaw rate; and  
       
       
         brake controlling means, responsive to said output signal, for maintaining stability of the vehicle when said vehicle is in motion by controlling a braking force applied to at least one of said plurality of wheels, said brake controlling means including a brake fluid pressure modulator means which responds to said output signal to modulate a braking force applied to wheels on one side of said vehicle differently relative to a braking force applied to wheels on an opposite side of said vehicle, so as to counteract any influence of lateral forces, said braking force applied to said wheels on one side of said vehicle relative to said braking force applied to said wheels on said opposite side of said vehicle being modulated in the absence of brake pedal input to said vehicle. 
       
     
     
       31. An apparatus for controlling a vehicle having a plurality of wheels and a brake pedal, comprising: 
       
         means responsive to the influence of destabilizing forces on a vehicle for measuring an actual yaw rate of said vehicle;  
       
       
         means for determining a dynamically variable target yaw rate of said vehicle and for producing an output signal in response to a comparison of said target yaw rate and said actual yaw rate; and  
       
       
         brake controlling means, responsive to said output signal, for maintaining stability of the vehicle when said vehicle is in motion by controlling a braking force applied to at least one of said plurality of wheels, said brake controlling means including a brake fluid pressure modulator means which responds to said output signal to modulate a braking force applied to at least one wheel on one side of said vehicle differently relative to a braking force applied to at least one wheel on an opposite side of said vehicle, so as to counteract any influence of lateral forces, said brake fluid pressure modulator means counteracting any influence of lateral forces by increasing the braking force applied to said at least one wheel on said one side of said vehicle while simultaneously decreasing the braking force applied to said at least one wheel on said opposite side of said vehicle. 
       
     
     
       32. The apparatus of  claim 31 , wherein said pressure modulator means modulates the braking force applied to the wheels on one side of said vehicle relative to the braking force applied to the wheels on an opposite side of said vehicle. 
     
     
       33. An apparatus for controlling a vehicle having a plurality of wheels, comprising: 
       
         means responsive to the influence of destabilizing forces on a vehicle for measuring an actual yaw rate of said vehicle;  
       
       
         means for determining a dynamically variable target yaw rate of said vehicle and for producing an output signal in response to a comparison of said target yaw rate and said actual yaw rate; and  
       
       
         brake controlling means, responsive to said output signal, for maintaining stability of the vehicle when said vehicle is in motion by controlling a braking force applied to at least one of said plurality of wheels to increase a braking force applied to at least one of said plurality of wheels located on an outside of a curved path of travel of the vehicle to compensate for an oversteer condition when it is determined that the vehicle is in said oversteer condition in response to said comparison of said target yaw rate and said actual yaw rate. 
       
     
     
       34. The apparatus of  claim 33 , wherein said brake controlling means increases a braking force applied to only at least one of said plurality of wheels that is located on the outside of the curved path of travel when said actual yaw rate is greater than said target yaw rate. 
     
     
       35. An apparatus for controlling a vehicle having a plurality of wheels, comprising: 
       
         means responsive to the influence of destabilizing forces on a vehicle for measuring an actual yaw rate of said vehicle;  
       
       
         means for determining a dynamically variable target yaw rate of said vehicle and for producing an output signal in response to a comparison of said target yaw rate and said actual yaw rate; and  
       
       
         brake controlling means, responsive to said output signal, for maintaining stability of the vehicle when said vehicle is in motion by decreasing a braking force applied to only one or both of said plurality of wheels located on an inside of a curved path of travel of the vehicle when said actual yaw rate is greater than said target yaw rate. 
       
     
     
       36. The apparatus of  claim 35 , wherein said at least one of said plurality of wheels include front and rear wheels located on the inside of the curved path of the vehicle. 
     
     
       37. An apparatus for controlling a vehicle having a plurality of wheels and a brake pedal comprising: 
       
         means responsive to the influence of destabilizing forces on a vehicle for measuring an actual yaw rate of said vehicle;  
       
       
         means for determining a dynamically variable target yaw rate of said vehicle and for producing an output signal in response to a comparison of said target yaw rate and said actual yaw rate, respectively; and  
       
       
         brake controlling means, responsive to said output signal, for maintaining stability of the vehicle when said vehicle is in motion by controlling a braking force applied to at least one of said plurality of wheels in the absence of brake pedal input, said brake controlling means increasing the braking force applied to a first wheel of said plurality of wheels when it is determined that the vehicle is in an oversteer condition in response to said comparison of said target yaw rate and said actual yaw rate and increasing the braking force applied to a second wheel of said plurality of wheels different from said first wheel when it is determined that the vehicle is in an understeer condition in response to said comparison of said target yaw rate and said actual yaw rate.