Vehicle motion control system

• US 5,913,578 A
• Filed: 10/28/1997
• Issued: 06/22/1999
• Est. Priority Date: 10/30/1996
• 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, Tozu, Kenji
• Primary Examiner(s): Young, Lee W.
• Assistant Examiner(s): Siconolfi, Robert
• Application Number:
  US08/959,072
• Time in Patent Office: 602 Days
• Field of Search: 303/140, 303/146, 303/147, 303/188
• US Class Current: 303/140
• CPC Class Codes: B60T 2260/02 Active Steering, Steer-by-Wire
• 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

The present invention is directed to a vehicle motion control system for maintaining stability of an automotive vehicle when the vehicle is in motion, by controlling a hydraulic braking pressure control apparatus to control a hydraulic braking pressure in each of wheel brake cylinders operatively mounted on each wheel of the vehicle to control a braking force applied thereto. A steering control unit and an anti-skid control unit are provided for actuating the apparatus to control the braking force applied to at least one of the wheels, respectively. A pressure increase compensating unit is provided for controlling a pressure increasing rate for increasing the braking pressure in at least one of the wheel brake cylinders to a desired pressure which is set after the pressure decreasing operation when the braking pressure with respect to at least one of the wheels is controlled in accordance with the control performed by the steering control unit and the control performed by the anti-skid control unit simultaneously, to be greater than a pressure increasing rate for increasing the braking pressure to the desired pressure in accordance with the control performed only by the anti-skid control unit.

Claims

1. A vehicle motion control system for maintaining stability of an automotive vehicle when said vehicle is in motion, by controlling a hydraulic braking pressure in each of wheel brake cylinders operatively mounted on wheels of said vehicle, respectively, to control a braking force applied thereto, comprising:

a hydraulic braking pressure control apparatus for controlling the braking pressure in each of said wheel brake cylinders at least in response to depression of a brake pedal;

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

steering control means for actuating said apparatus to increase and decrease the braking pressure in at least one of said wheel brake cylinders operatively mounted on at least one of said wheels to control the braking force applied thereto, 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 apparatus to decrease and increase the braking pressure in at least one of said wheel brake cylinders operatively mounted on at least one of said wheels to control the braking force applied thereto, in response to a rotational condition thereof during braking, on the basis of the output of said monitor means; and

pressure increase compensating means for controlling a pressure increasing rate for increasing the braking pressure to a desired pressure which is set after the pressure decreasing operation made by said apparatus when the braking pressure with respect to said at least one of said wheels is controlled in accordance with the control performed by said steering control means and the control performed by said anti-skid control means simultaneously, to be greater than a pressure increasing rate for increasing the braking pressure to the desired pressure in accordance with the control performed only by said anti-skid control means.

2. A vehicle motion control system as set forth in claim 1, wherein said hydraulic braking pressure control apparatus is adapted to provide a plurality of control modes including a rapid pressure increase mode for increasing the braking pressure in at least one of said wheel brake cylinders by a relatively rapid rate comparing with the other control modes, and wherein said pressure increase compensating means is adapted to provide the rapid pressure increase mode when the braking pressure with respect to at least one of said wheels is controlled in accordance with the control performed by said steering control means and the control performed by said anti-skid control means simultaneously, for a longer period than the period during which the rapid pressure increase mode is provided when the braking pressure is controlled in accordance with the control performed only by said anti-skid control means.

3. A vehicle motion control system as set forth in claim 2, wherein a pressure increasing time for the control performed only by said anti-skid control means is multiplied by a constant to provide a pressure increasing time for the control performed by said steering control means and said anti-skid control means simultaneously.

4. A vehicle motion control system as set forth in claim 1, wherein said hydraulic braking pressure control apparatus is adapted to provide a plurality of control modes including a pulse pressure increase mode for increasing the braking pressure in at least one of said wheel brake cylinders gradually by increasing the braking pressure therein intermittently in accordance with a duty ratio, and wherein said pressure increase compensating means is adapted to set the duty ratio for the pulse pressure increase mode when the braking pressure with respect to at least one of said wheels is controlled in accordance with the control performed by said steering control means and the control performed by said anti-skid control means simultaneously, to be greater than the duty ratio for the pulse pressure increase mode which is set when the braking pressure is controlled in accordance with the control performed only by said anti-skid control means.

5. A vehicle motion control system as set forth in claim 1, further comprising:

desired slip rate setting means for setting a desired slip rate for each wheel of said vehicle during braking, said hydraulic braking pressure control apparatus being controlled in response to the desired slip rate, and wherein said desired slip rate setting means is adapted to limit the desired slip rate which is set when the braking pressure with respect to at least one of said wheels is controlled in accordance with the control performed by said steering control means and the control performed by said anti-skid control means simultaneously, to be lower than a predetermined value.