Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2001-10-24
2003-09-16
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S072000
Reexamination Certificate
active
06622073
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the technological field of vehicle posture control apparatuses that avoid or suppress understeering tendencies (drifting out) and oversteering tendencies (spinning) by controlling the posture of a vehicle during cornering.
Conventionally, various vehicle posture control apparatuses are known, in which, such as in JP H06-183288A or JP H07-223520A, a target yaw rate is set based on the steering wheel angle and the vehicle speed, the actual yaw rate of the vehicle is detected with a yaw rate sensor, and when the deviation between the detected actual yaw rate and the target yaw rate has at least a predetermined value, an understeer control suppressing an understeering tendency of the vehicle intervenes or an oversteer control suppressing an oversteering tendency of the vehicle intervenes.
More specifically, in such a posture control apparatus, understeer control intervenes when the target yaw rate is larger than a value obtained by adding a predetermined threshold to the actual yaw rate, whereas oversteer control intervenes when the actual yaw rate is larger than a value obtained by adding a predetermined threshold to the target yaw rate.
In this conventional posture control apparatus, too much oversteer control tends to intervene when the threshold is small. When the oversteer control intervenes too early, there is the problem that this invites difficulties in turning the vehicle due to excessive control, and also the strength of the operation when intervention of control is unnecessary is a problem.
In order to rectify this, the threshold determining the intervention of the oversteer control should be increased, so that an early intervention of the oversteer control can be inhibited. However in that case, the control will intervene only when the oversteering tendency of the vehicle is already too large. Moreover, when the control finally intervenes, a strong control intervenes abruptly. Therefore, even though it is possible to ensure the stability of the vehicle, in a situation in which the oversteering tendency keeps increasing until the oversteer control intervenes, the driver may feel that the controllability worsens, leading to a sense of instability.
In view of these problems, it is an object of the present invention to ensure a high vehicle stability and to enhance the sense of stability and the controllability felt by the driver by improving the oversteer control.
SUMMARY OF THE INVENTION
In order to achieve these objects, according to a first aspect of the present invention, in addition to a first oversteer control for suppressing an oversteering tendency, a second oversteer control is provided, whose control amount is lower than that of the first oversteer control.
More specifically, the subject matter of the first aspect of the present invention is a vehicle posture control apparatus provided with a control means for controlling posture of the vehicle in yawing direction by independently controlling the brakes of the vehicle's wheels.
A special feature of the invention is that the control means carries out intervention of a first oversteer control suppressing the oversteering tendency when the oversteering tendency of the vehicle is stronger than a first preset reference value, and the control means carries out intervention of a second oversteer control, in which the control amount is lower than in the first oversteer control, when the oversteering tendency of the vehicle is not stronger than the first preset reference value, but stronger than a second preset reference value.
Thus, when the oversteering tendency of the vehicle is stronger than a first preset reference value, that is, when the oversteering tendency is relatively strong, the first oversteer control intervenes to suppress this oversteering tendency. This sufficiently ensures the stability of the vehicle.
Then, when the oversteering tendency of the vehicle is not stronger than the first preset reference value but stronger than the second preset reference value, or in other words, when there is a relatively weak oversteering tendency, intervention of the second oversteer control, whose control amount is lower than that of the first oversteer control, is carried out. Thus, by early intervention of the second oversteer control, this weak oversteering tendency is suppressed, and also growth of the oversteering tendency (the oversteering tendency becoming stronger) is suppressed. Thus, the stability of the vehicle is increased even more, improving the sense of stability felt by the driver, while strong oversteering tendencies are suppressed, and the ease of control felt by the driver is improved.
The second oversteer control is a weak control with a lower control amount. Therefore, the second oversteer control does not lead to excessive control even when it intervenes early, and unnecessary operation can be prevented from becoming too strong. As a result, an awkward feeling of the driver is prevented.
Furthermore, when for example the oversteering tendency increases even though the second oversteer control has intervened, and the oversteering tendency becomes stronger than the first preset reference value, then the first oversteer control intervenes, replacing the second oversteer control. Thus, the first oversteer control, which has a strong control amount, does not intervene abruptly. Also, the awkward feeling of the driver is largely rectified by continuously moving from the second oversteer control, which is a weak control, to the first oversteer control, which is a strong control. Also, the second oversteer control intervenes previously to intervention of the first oversteer control, so that the play of the brake system is eliminated (for example, leading to a state in which the brake pads adhere to the disk rotor). Therefore, the responsiveness of the first oversteer control is improved. Furthermore, if the first oversteer control intervenes in continuation to the intervention of the second oversteer control, the effect is substantially the same as when lowering the threshold of the oversteer control, so that an even higher stability of the vehicle can be ensured.
Consequently, providing the second understeer control separately from the first understeer control ensures a high stability of the vehicle while improving the sense of stability and the controllability felt by the driver.
It is preferable that the second oversteer control supplies, by open control, a brake pressure whose upper limit is a predetermined brake pressure that is lower than the maximum brake pressure that can be supplied in the first oversteer control.
That is to say, the responsiveness of the control is improved by supplying the brake pressure by open control. At the same time, a suppression of an oversteering tendency with a control amount that is lower than in the first oversteer control is achieved by setting a predetermined brake pressure that is lower than the maximum brake pressure that can be supplied in the first oversteer control. This way, a relatively weak oversteering tendency can be suitably adjusted without the driver noticing the intervention of a control.
It is preferable that the second oversteer control supplies brake pressure in accordance with a deviation between a target yaw rate that has been set and the actual yaw rate.
That is to say, by supplying the brake force by feedback control in accordance with a deviation between a target yaw rate that has been set and the actual yaw rate, there is no excessive suppression control of the oversteering, and an optimal control is achieved. It should be noted that the upper limit of the brake pressure can also be set to a predetermined brake pressure that is lower than the brake pressure during the first oversteer control. In this case, it is easy to achieve a suppression control of oversteering, in which the control amount is lower than in the first oversteer control.
It is preferable that the control means prohibits intervention of the second oversteer control when the vehicle has an understeering tendenc
Tanaka Hirohisa
Watanabe Yoshihiro
Yasutake Toshio
Cuchlinski Jr. William A.
Mazda Motor Corporation
Nixon & Peabody LLP
Pipala Edward
Studebaker Donald R.
LandOfFree
Vehicle posture control apparatus 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 posture control apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vehicle posture control apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3032999