Auxiliary steering system associated with anti-skid control system for use in motor vehicle

• US 5,089,967 A
• Filed: 08/20/1990
• Issued: 02/18/1992
• Est. Priority Date: 08/10/1987
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Kuroyanagi, Masatoshi, Murakami, Fumiaki, Murakawa, Takaji, Haseda, Satoshi, Hiraiwa, Shinji, Majima, Youzou
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): TRANS, VINCENT N
• Application Number:
  US07/569,579
• Time in Patent Office: 547 Days
• Field of Search: 364/426.02, 364/424.05, 303/93, 303/95, 303/100, 303/103, 303/104, 180/197, 180/6.2, 180/6.62, 180/79.1
• US Class Current: 701/78
• CPC Class Codes: B60T 2260/024 Yawing moment compensation during mu-split braking
• CPC Class Codes: B60T 8/00 Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force by changing number of effective brake cylinders in power brake systems B60T17/10
• CPC Class Codes: B60T 8/1764 Regulation during travel on surface with different coefficients of friction, e.g. between left and right sides, mu-split or between front and rear
• CPC Class Codes: B62D 6/00 Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00
• CPC Class Codes: B62D 6/04 responsive only to forces disturbing the intended course of the vehicle, e.g. forces acting transversely to the direction of vehicle travel

Abstract

An auxiliary steering control system in connection with an anti-skid control system for use in a motor vehicle with two parts of left and right wheels, the anti-skid control system being adapted to independently control braking pressures for at least one pair of left and right wheels and including a braking actuator for adjusting braking pressures to be applied to the pair of left and right wheels. The braking actuator is controlled so that the braking pressures therefor approach the target braking forces determined on the basis of the rotational speeds of the wheels. The steering control device includes a steering actuator for adjusting steering angles of the pair of left and right wheels in response to steering control signals from a steering angle control unit. The steering control unit determines the steering angles of the pair of left and right wheels on the basis of the difference between the braking pressures therefor and outputs the steering control signals thereto so that the pair of left and right wheels assume the determined steering angles.

Claims

1. A control system for use in a motor vehicle with two pairs of left and right wheels, comprising:

a braking control device for independently controlling braking pressures for at least one of said pairs of left and right wheels, said braking control device including;

braking actuator means for adjusting braking pressures to be applied to said pair of left and right wheels in response to braking control signals;

wheel sensor means for sensing rotation speeds of said pair of left and right wheels and generating signals indicative of the sensed rotational speeds thereof;

target braking pressure determining means for determining target braking pressures for said pair of left and right wheels on the basis of said rotational speed signals from said wheel sensor means; and

braking pressure control means for outputting said braking control signals to said braking actuator means so that the braking pressures for said pair of left and right wheels assume the determined target braking pressures, respectively; and

a steering control device for controlling the steering of said pair of left and right wheels in connection with the braking control performed by said braking control device, said steering control device including;

steering actuator means for adjusting steering angles of said pair of left and right wheels in response to steering control signals; and

steering angle control means for determining the steering angles of said pair of left and right wheels on the basis of the braking pressures for said pair of left and right wheels and outputting said steering control signals indicative of the determined steering angles to said steering actuator means so that said pair of left and right wheels assume the determined steering angles, thereby canceling any yaw moment generated by said braking pressures applied to said pair of left and right wheels.

2. A control system as claimed in claim 1, further comprising braking pressure sensor means for sensing braking pressures applied to said pair of left and right wheels, and wherein said steering angle control means determines the steering angles on the basis of the difference between the braking pressures of said pair of left and right wheels sensed by said braking pressure sensor means.

3. A control system as claimed in claim 1, wherein said steering angle control means determines the steering angles of said pair of left and right wheels on the basis of the difference between the target braking pressures determined by said target braking pressure determining means.

4. A control system as claimed in claim 1, further comprising vehicle speed detection means for detecting a speed of said motor vehicle, and wherein said steering control means corrects the steering angles of said pair of left and right wheels on the basis of the detected vehicle speed.

5. A control system as claimed in claim 1, further comprising braking pressure sensor means for sensing braking pressures applied to said pair of left and right wheels, and wherein said steering angle control means determines the steering angles on the basis of the difference between the braking pressures of said pair of left and right wheels sensed by said braking pressure sensor means and the sum of the braking pressures thereof.

6. A control system as claimed in claim 1, wherein said steering angle control means determines the steering angles of said pair of left and right wheels on the basis of the difference between the target braking pressures determined by said target braking pressure determining means and the sum of the target braking pressures thereof.

7. A control system as claimed in claim 1, wherein said steering angle control means estimates the braking pressures applied to said pair of left and right wheels on the basis of said braking control signals outputted from said braking pressure control means and determines the steering angles of said pair of left and right wheels on the basis of the difference between the estimated braking pressures.

8. A control system as claimed in claim 1, wherein said braking actuator means comprises solenoid valves for adjusting the braking pressures for said pair of left and right wheels and said steering angle control means estimates the braking pressures applied thereto on the basis of the opening times of said solenoid valves.

9. A control system as claimed in claim 1, wherein said steering angle control means comprises:

means for determining a basic rear wheel steering angle on the basis of braking pressures for a front of said pairs of left and right wheels;

means for determining a vehicle speed coefficient value on the basis of a speed of said vehicle; and

means for outputting a rear wheel steering command value as one of said steering control signals when said front pair of wheels have a steered angle lens than a predetermined value, said rear wheel steering command value being output on the basis of said basic rear wheel steering angle and said vehicle speed coefficient value.

10. A control system as claimed in claim 1, wherein said steering angle control means comprises:

means for determining a basic rear wheel steering angle on the basis of a steering angle of a front of said pairs of left and right wheels and a speed of said vehicle;

means for determining a correction value on the basis of braking pressures of said front pair of wheels; and

means for outputting a rear wheel steering command value as one of said steering control signals when said steering angle of said front pair of wheels exceeds a predetermined value, said rear wheel steering command value being output on the basis of said basic rear wheel steering angle and said correction value.

11. A control system for use in a motor vehicle having a front and rear pair of left and right wheels, comprising:

anti-skid braking system means for independently controlling braking pressures for the left and right wheels of at least one of said pairs of wheels during braking operation so that slip ratios of said left and right wheels approach target slip ratios, respectively, said target slip ratios being determined by said anti-lock braking system means in response to rotational speeds of said left and right wheels;

means for obtaining a pressure difference between said braking pressures for said left and right wheels;

means for calculating a steering angle of said at least one pair of wheels in accordance with the obtained pressure difference so as to cancel a yaw moment, said yaw moment being generated by said motor vehicle due to a braking force difference caused by the pressure difference; and

drive means for steering said at least one pair of wheels in accordance with the steering angle calculated by said calculating means.

12. A control system as claimed in claim 11, wherein said pressure difference obtaining means includes pressure sensor means for sensing the braking pressures for said left and right wheels and pressure difference calculating means for calculating said pressure difference between the sensed braking pressures for said left and right wheels.

13. A control system as claimed in claim 11, wherein said anti-lock braking system means comprises:

wheel spaced sensor means for sensing speeds of said left and right wheels;

setting means for setting target braking pressures for said left and right wheels on the basis of the sensed wheel speed; and

adjusting means for adjusting the braking pressures for said left and right wheels so that the braking pressures therefor approach the target braking pressures set by said setting means, and

wherein said pressure difference obtaining means calculates the pressure difference between the target braking pressures for said left and right wheels, respectively.

14. A control system as claimed in claim 11, further comprising vehicle speed detection means for detecting a speed of said motor vehicle, said calculating means correcting the steering angle on the basis of the detected vehicle speed.

15. A control system as claimed in claim 11, further comprising means for calculating a sum of the braking pressures for said left and right wheels, and wherein said steering angle is calculated on the basis of the sum of the braking pressures and the pressure difference.

16. A control system as claimed in claim 11, wherein said anti-lock braking system means comprises:

wheel speed sensor means for sensing speeds of said left and right wheels;

adjusting means for independently adjusting the braking pressures for said left and right wheels in response to control signals; and

control means for outputting said control signals to said adjusting means so as to control the braking pressures for said left and right wheels, said control signals being generated on the basis of said sensed wheel speeds, said pressure difference obtaining means calculating the pressure difference between the braking pressures for said left and right wheels on the basis of said control signals outputted from said control means.

17. A control system as claimed in claim 11, wherein said anti-lock braking system means includes solenoid valves for adjusting the braking pressures for said left and right wheels so as to estimate the braking pressures on the basis of the opening times of said solenoid valves.

18. A control system as claimed in claim 11, wherein said steering angle calculating means comprises:

means for determining a basic rear wheel steering angle on the basis of said pressure difference of said front pair of left and right wheels;

means for determining a vehicle speed coefficient value on the basis of a speed of said vehicle; and

means for outputting a rear pair steering angle when said front pair of wheels have a steered angle less than a predetermined value, said rear pair steering angle being output on the basis of said basic rear wheel steering angle and said vehicle speed coefficient value.

19. A control system as claimed in claim 11, wherein said steering angle calculating means comprises:

means for determining a basic rear wheel steering angle on the basis of a steering angle of said front pair or left and right wheels and a speed of said vehicle;

means for determining a correction value on the basis of said pressure difference of said front pair of wheels; and

means for outputting a rear pair steering angle when said steering angle of said front pair of wheels exceeds a predetermined value, said rear pair steering angle being output on the basis of said basic rear wheel steering angle and said correction value.