Vehicle motion control system

• US 5,752,752 A
• Filed: 11/27/1996
• Issued: 05/19/1998
• Est. Priority Date: 11/30/1995
• Status: Expired due to Term

• Current Assignee: Advics Company Limited (Aisin Corp.)
• Original Assignee: Aisin Seiki Co., Ltd. (Aisin Corp.)
• Inventors: Yamazaki, Norio, Yasui, Yoshiyuki, Itoh, Takayuki, Fukami, Masanobu, Tozu, Kenji
• Primary Examiner(s): Butler, Douglas C.
• Application Number:
  US08/758,245
• Time in Patent Office: 538 Days
• Field of Search: 303/140, 303/146, 303/153, 303/154, 303/139, 303/147, 364/426.016, 364/426.023, 364/424.051, 364/424.052, 701/72, 701/41, 701/71, 701/48, 180/197
• US Class Current: 303/146
• CPC Class Codes: B60T 2201/16 Curve braking control, e.g. turn control within ABS control algorithm
• CPC Class Codes: B60T 8/17555 specially adapted for enhancing driver or passenger comfort, e.g. soft intervention or pre-actuation strategies

Abstract

The present invention is directed to a vehicle motion control system for maintaining vehicle stability by controlling the braking force applied to at least one wheel of a vehicle. A vehicle condition monitor monitors a condition of the vehicle in motion. A steering control unit actuates a braking unit to apply the braking force to at least one wheel on the basis of the output of the monitor and irrespective of depression of a brake pedal. An anti-skid control unit actuates the braking unit to control the braking force applied to at least one wheel in response to a rotational condition thereof during braking. A subordinate control unit actuates the braking unit to adjust the braking force control performed by the anti-skid control unit, in accordance with a predetermined relationship between the anti-skid control unit and the subordinate control unit. And, a priority control unit is adapted to give priority the anti-skid control unit over the steering control unit, and give priority the steering control unit over the subordinate control unit, when the condition for starting the braking force control performed by both of the anti-skid control unit and the steering control unit is fulfilled with respect to at least one wheel.

Claims

1. A vehicle motion control system for maintaining stability of an automotive vehicle when said vehicle in motion, by controlling a braking force applied to the front and rear wheels of said vehicle, comprising:

vehicle condition monitor means for monitoring a condition of said vehicle in motion;

braking means for applying a braking force to each wheel of said vehicle, said braking means actuated in response to depression of a brake pedal, and said braking means actuated on the basis of an output of said monitor means and irrespective of depression of said brake pedal;

steering control means for actuating said braking means to apply the braking force to at least one of said wheels on the basis of the output of said monitor means and irrespective of depression of said brake pedal;

anti-skid control means for actuating said braking means to control the braking force applied to at least one of said wheels in response to a rotational condition thereof during braking, on the basis of the output of said monitor means;

subordinate control means for actuating said braking means to adjust the braking force control performed by said anti-skid control means, in accordance with a predetermined relationship between said anti-skid control means and said subordinate control means; and

priority control means for giving priority said anti-skid control means over said steering control means, and giving priority said steering control means over said subordinate control means, when a condition for starting the braking force control performed by both of said anti-skid control means and said steering control means is fulfilled with respect to at least one of said wheels.

2. The vehicle motion control system as claimed in claim 1, wherein said subordinate control means includes:

yaw control means for controlling the braking force applied to at least one wheel to be controlled out of said wheels, in accordance with a predetermined relationship with the braking force applied to at least one of the rest of said wheels, and on the basis of a relationship between said wheels during the control performed by said anti-skid control means, and further comprising;

limiting means for preventing said yaw control means from controlling the braking force applied to said at least one wheel to be controlled in accordance with the control performed by said steering control means, when the braking force is controlled by said anti-skid control means and said subordinate control means with respect to said at least one wheel to be controlled.

3. The vehicle motion control system as claimed in claim 2, wherein said yaw control means includes right-left yaw control means for reducing an increasing rate of the braking force applied to one of said front wheels, when the braking force applied to the other one of said front wheels is controlled by said anti-skid control means.

4. The vehicle motion control system as claimed in claim 2, wherein said yaw control means includes front-rear yaw control means for reducing an increasing rate of the braking force applied to at least one of said rear wheels, when the braking force applied to one of said front wheels is controlled by said anti-skid control means.

5. The vehicle motion control system as claimed in claim 1, wherein said subordinate control means includes pre-control means for applying the braking force to said at least one wheel to be controlled, in advance of the braking force control initiated by said anti-skid control means and/or said steering control means, and wherein said priority control means is adapted to give priority said steering control means over said pre-control means.

6. The vehicle motion control system as claimed in claim 1, wherein said braking means comprises:

wheel brake cylinders operatively connected to said front and rear wheels for applying the braking force thereto, respectively;

a hydraulic pressure generator for supplying a hydraulic pressure to said wheel brake cylinders; and

actuating means disposed between said hydraulic pressure generator and said wheel brake cylinders for controlling the hydraulic pressure in said wheel brake cylinders, said actuating means activated by said steering control means, said anti-skid control means and said subordinate control means.

7. The vehicle motion control system as claimed in claim 6, wherein said subordinate control means includes pre-anti-skid control means for activating said actuating means to control the hydraulic pressure in said wheel brake cylinders, in advance of the braking force control initiated by said anti-skid control means, and wherein said priority control means is adapted to give priority said steering control means over said pre-anti-skid control means.

8. The vehicle motion control system as claimed in claim 6, wherein said subordinate control means includes pre-steering control means for activating said actuating means to control the hydraulic pressure in said wheel brake cylinders, in advance of the braking force control initiated by said steering control means, and wherein said priority control means is adapted to give priority said steering control means over said pre-steering control means.

9. The vehicle motion control system as claimed in claim 1, wherein said steering control means includes:

oversteer restraining control means for actuating said braking means to apply the braking force to at least one of said wheels on the basis of the output of said monitor means and irrespective of depression of said brake pedal, said oversteer restraining control means actuating said braking means to apply the braking force to at least one of said wheels so as to cause an increase in turning radius, when an excessive oversteer occurs during vehicle motion; and

understeer restraining control means for actuating said braking means to apply the braking force to at least one of said wheels on the basis of the output of said monitor means and irrespective of depression of said brake pedal, said understeer restraining control means actuating said braking means to apply the braking force to at least one of said wheels so as to cause a decrease in turning radius, when an excessive understeer occurs during vehicle motion.