Device for stabilizing vehicle attitude in terminal portion of countersteering state by reducing vehicle yaw moment produced by yaw moment control mechanism

• US 5,799,745 A
• Filed: 06/07/1996
• Issued: 09/01/1998
• Est. Priority Date: 06/09/1995
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Fukatani, Katsumi
• Primary Examiner(s): Cummings, Scott
• Application Number:
  US08/659,886
• Time in Patent Office: 816 Days
• Field of Search: 180/408, 180/410, 180/412, 180/413, 180/414, 180/415, 364/424.051
• US Class Current: 180/410
• 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 7/159 characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition

Abstract

A vehicle attitude control device including a yaw moment control mechanism for giving a yaw moment to the vehicle and controlling the yaw moment, and a controller for controlling the yaw moment control mechanism in a normal target follow-up control mode so that the actual yaw rate detected by a yaw rate sensor coincides with a target value determined on the basis of an angle of rotation of a steering wheel detected by a steering wheel angle sensor, and wherein a yaw moment reducing device is provided for reducing the yaw moment to be given to the vehicle by the yaw moment control mechanism, to a reduced value smaller than a normal value to which the yaw moment is controlled in the normal target follow-up control mode. The yaw moment reducing device is operated in at least a second phase of a countersteering period following a first phase which is initiated by vehicle operator'"'"'s countersteering manipulation of the steering wheel upon slipping of rear wheels of the vehicle during vehicle turning outwardly of the turning direction so as to countersteer the vehicle.

Claims

1. A vehicle attitude control device comprising a steering wheel angle sensor for detecting a rotation angle of a steering wheel which is operated by an operator of the vehicle to steer front wheels of the vehicle, a yaw rate sensor for detecting an actual value of a yaw rate of the vehicle, a yaw moment control mechanism for giving a yaw moment to the vehicle and controlling said yaw moment, and a controller for controlling said yaw moment control mechanism in a normal target follow-up control mode so that the actual value of the yaw rate detected by said yaw rate sensor coincides with a target value of the yaw rate which is determined on the basis of the rotation angle of the steering wheel detected by said steering wheel angle sensor, wherein an improvement comprises yaw moment reducing means for reducing the yaw moment to be given to the vehicle by said yaw moment control mechanism, to a reduced value smaller than a normal value to which the yaw moment is controlled in said normal target follow-up control mode under the control of said controller, said yaw moment reducing means being operated in at least a second phase of a countersteering period following a first phase of said countersteering period, said countersteering period being initiated by countersteering manipulation of said steering wheel by said operator upon slipping of rear wheels of the vehicle during turning of the vehicle outwardly of a direction of said turning so as to countersteer the vehicle, said countersteering manipulation including a rotation of said steering wheel in said first phase so that said front wheels are oriented outwards with respect to said turning direction of the vehicle, and a rotation of said steering wheel toward a neutral position thereof in said second phase.

2. A vehicle attitude control device according to claim 1, wherein said controller controls said yaw moment control mechanism in one of said normal target follow-up control mode and a yaw rate responsive control mode in which said yaw moment control mechanism is controlled on the basis of said actual value of said yaw rate detected by said yaw rate sensor such that said actual value of the yaw rate is reduced toward zero, and wherein said yaw moment reducing means includes control mode selecting means for commanding said controller to control said yaw moment control mechanism in said yaw rate responsive control mode in at least said second phase of said countersteering period, and in said normal target follow-up control mode at the other opportunities during said turning of the vehicle.

3. A vehicle attitude control device according to claim 2, wherein said controller effects proportioning control of said yaw moment control mechanism in said yaw rate responsive control mode, such that the yaw moment to be given to the vehicle by said yaw moment control mechanism is changed by an amount proportional to said actual value of the yaw rate detected by said yaw rate sensor, so as to reduce said actual value of the yaw rate toward zero, and wherein said control mode selecting means commands said controller to effect said proportioning control of said yaw moment control mechanism in at least said second phase of said countersteering period.

4. A vehicle attitude control device according to claim 1, further comprising a vehicle speed sensor for detecting a running speed of the vehicle, and wherein said controller determines said target value of said yaw rate of the vehicle on the basis of said rotation angle of said steering wheel detected by said steering wheel angle sensor and said running speed of the vehicle detected by said vehicle speed sensor such that the determined target value of the yaw rate is expected to be established when the vehicle is turning along a circular arc path with said running speed being held substantially constant, said controller controlling said yaw moment control mechanism in said normal target follow-up control mode such that said actual value of the yaw rate detected by said yaw rate sensor coincides with said determined target value.

5. A vehicle attitude control device according to claim 1, wherein said yaw moment reducing means comprises second-phase countersteering control means for commanding said controller to control said yaw moment control mechanism in a second-phase countersteering control mode in said second phase of said countersteering period such that the yaw moment to be given to the vehicle is smaller in said second-phase countersteering control mode than in said normal target follow-up control mode.

6. A vehicle attitude control device according to claim 5, wherein said yaw moment reducing means further comprises first-phase countersteering control means for commanding said controller to control said yaw moment control mechanism in a first-phase countersteering control mode in said first phase of said countersteering period such that the yaw moment to be given to the vehicle is smaller in said first-phase countersteering control mode than in said normal target follow-up control mode.

7. A vehicle attitude control device according to claim 1, wherein said yaw moment reducing means comprises steering state determining means for determining whether said steering wheel is in said first phase or said second phase of said countersteering period, on the basis of a relationship between said rotation angle of said steering wheel and said actual value of said yaw rate.

8. A vehicle attitude control device according to claim 7, wherein said steering state determining means determines whether said steering wheel is in said first phase or said second phase, on the basis of a relationship between a rate of change of said rotation angle of said steering wheel and a rate of change of said actual value of said yaw rate.

9. A vehicle attitude control device according to claim 1, wherein said yaw moment control mechanism controls said yaw moment to be given to the vehicle, by controlling a lateral force which is produced between at least one of said front wheels and rear wheels of the vehicle and a road surface on which the vehicle is running, said lateral force acting in a lateral direction of the vehicle.

10. A vehicle attitude control device according to claim 9, wherein said yaw moment control mechanism includes a steering actuator for controlling a steering angle of at least one of said front and rear wheels, to thereby control said lateral force.

11. A vehicle attitude control device according to claim 10, wherein said steering actuator controls the steering angle of said rear wheels.