Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-10-26
2001-08-21
Louis-Jacques, Jacques H. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S036000, C701S078000, C701S083000, C303S155000, C303S166000, C303S167000
Reexamination Certificate
active
06278929
ABSTRACT:
This application claims priority under 35 U.S.C. Sec. 119 to No.10-325969 filed in Japan on Oct. 30, 1998, the entire content of which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle motion control system for controlling motion of a vehicle, and more particularly to the control system for maintaining vehicle stability by controlling a braking force applied to each wheel of the vehicle irrespective of depression of a brake pedal in the vehicle motion including a turning motion of the vehicle.
2. Description of the Related Arts
As a system for controlling a vehicle motion characteristic, especially a turning characteristic of the vehicle, an apparatus for controlling a difference between the braking force applied to right and left wheels to directly control a turning moment has been noted, and it is now on the market. For example, Japanese Patent Laid-open Publication No.9-301147 discloses a motion control apparatus which estimates an amount indicative of a condition of the vehicle in motion when the vehicle turns, and controls a hydraulic braking pressure control apparatus so as to correct a yaw moment of the vehicle to make the vehicle in motion to be stable, when the amount indicative of the condition of the vehicle in motion exceeded a threshold level for starting the control. In that publication, in order to change a range of the amount of the vehicle motion for starting the control in accordance with a coefficient of friction, is proposed the motion control apparatus, wherein the lower the coefficient of friction is, the smaller the threshold level for starting the control is set.
In the vehicle motion control system as described above, various sensors for detecting signals indicative of the condition of the vehicle in motion have been disposed. For example, Japanese Patent Laid-open Publication No.5-314397 discloses a yaw rate sensor for detecting a yaw rate of the vehicle. In this Publication, a zero point signal of the yaw rate sensor is renewed to provide such a relationship that each of positive or negative value of steering angle within a certain time period and each of positive or negative value of yaw rate within a certain time period will coincide with each other, under a certain running condition of the vehicle.
According to the apparatus for processing the sensor signal as described in the Publication No.5-314397, the renewal of the zero point may cause an error, when controlling the vehicle motion. Therefore, it is preferable not to start the vehicle motion control, when the zero point is renewed. In an apparatus having a lateral acceleration sensor for detecting the lateral acceleration of the vehicle, the center of gravity of the vehicle moves, when the vehicle runs on a rough road, for example, so that a distance will be made between the center of gravity and a position of the vehicle on which the center of the sensor is mounted, to cause an error in the detected lateral acceleration. In practice, an actual acceleration (Gyo) is calculated in accordance with the following equation:
Gyo=Gya−L·d&ggr;/dt
where “Gya” is a value detected by the lateral acceleration sensor, “L” is the distance between the center of gravity and the position of the vehicle on which the center of the sensor is mounted, and “&ggr;” the yaw rate. Thus, the error of (L·d&ggr;/dt) is caused. In particular, when a vehicle slip angle for use in a steering control by braking is calculated, the error in the output of the lateral acceleration sensor is accumulated, thereby to cause a relatively large error. Therefore, it is preferable to set a gain for starting the control to be less sensitive, such that the vehicle motion control will not start, when the error caused by the lateral acceleration sensor is estimated.
In the motion control apparatus as disclosed in the Publication No.9-301147, the threshold level for starting the control is corrected in response to the coefficient of friction of the road, but it is not corrected in advance by estimating the error caused by a monitor like the sensor as described above.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a vehicle motion control system for setting an appropriate starting reference for a vehicle motion control, without being influenced by an error caused by a monitor, to smoothly control the vehicle in motion to be stable.
In accomplish the above and other objects, the vehicle motion control system is arranged to include a hydraulic braking pressure control apparatus which is adapted to control braking force applied to each wheel of the vehicle at least in response to depression of a brake pedal, a vehicle condition monitor which is disposed in the vehicle to monitor a condition of the vehicle in motion, a vehicle condition determining device which is adapted to determine stability of the vehicle in motion, including a turning motion of the vehicle on the basis of the output of the monitor, and a braking force controller which is adapted to control the hydraulic braking pressure control apparatus in response to the result of determination of the vehicle condition determining device to control the braking force applied to each wheel of the vehicle. A starting reference setting device is provide for setting a starting reference to start the braking force control by the braking force controller in response to the result of determination of the vehicle condition determining device. Then, an error estimating device is provided for estimating an error caused by the monitor, and a correction device is provided for correcting the starting reference set by the starting reference setting device in response to the error estimated by the error estimating device.
In the vehicle motion control system, the correction device is preferably adapted to correct the starting reference set by the starting reference setting device to be relatively higher, when the error estimating device estimated the error resulted from a distance between the center of gravity of the vehicle and the center of the monitor mounted on the vehicle. The correction device may be adapted to correct the starting reference set by the starting reference setting device to be relatively higher, when the error estimating device estimated the error resulted from a zero point set for the monitor. Or, the correction device may be adapted to correct the starting reference set by the starting reference setting device to be relatively higher, when the error estimating device estimated the error resulted from inclination of the vehicle in a lateral direction thereof.
REFERENCES:
patent: 5620239 (1997-04-01), Mihara et al.
patent: 5752752 (1998-05-01), Tozu et al.
patent: 5762406 (1998-06-01), Yasui et al.
patent: 5857754 (1999-01-01), Fukami et al.
patent: 5913578 (1999-06-01), Tozu et al.
patent: 5927830 (1999-07-01), Tozu et al.
patent: 6053583 (2000-04-01), Izumi et al.
patent: 6070952 (2000-06-01), Tozu et al.
patent: 6078858 (2000-06-01), Tozu et al.
patent: 6106080 (2000-08-01), Tozu et al.
patent: 5-314397 (1993-11-01), None
patent: 8-142846 (1996-06-01), None
patent: 9-301147 (1997-11-01), None
patent: 10-282138 (1998-10-01), None
Itoh Takayuki
Tozu Kenji
Aisin Seiki Kabushiki Kaisha
Burns Doane , Swecker, Mathis LLP
Louis-Jacques Jacques H.
LandOfFree
Vehicle motion control system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vehicle motion control system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vehicle motion control system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2477858