Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
2001-06-05
2002-10-22
Chin, Gary (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S001000, C701S041000, C701S070000, C303S146000
Reexamination Certificate
active
06470250
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a vehicle attitude control apparatus whereby the behaviour of a vehicle can be stabilized.
DESCRIPTION OF THE RELATED ART
If a vehicle has entered a state of under-steer or a state of over-steer, then it is sought to stabilize the behaviour of the vehicle by controlling the braking forces applied to the vehicle wheels.
However, if the steering angle is raised excessively in order to eliminate a state of under-steer, then it becomes difficult to maintain a linear region where the lateral slip angle of the vehicle wheels is proportional to the cornering force, and hence even if the braking forces are controlled in the foregoing manner, it is not possible to stabilize the vehicle behaviour.
It is an object of the present invention to provide a vehicle attitude control apparatus capable of resolving the aforementioned problem.
SUMMARY OF THE INVENTION
The vehicle attitude control apparatus according to the present invention comprises: an operating member; a steering actuator driven in accordance with the operation of the operating member; a mechanism for transmitting movement of the steering actuator to the wheels of a vehicle, in such a manner that the steering angle changes in accordance with the movement thereof; means for determining a behaviour index value corresponding to changes in vehicle behaviour on the basis of changes in the steering angle; means for determining the amount of operation of the operating member; means for determining a target behaviour index value corresponding to the determined amount of operation, on the basis of a stored relationship between the amount of operation and the target behaviour index value; means for determining whether or not the vehicle is in a state of under-steer; means for controlling the steering actuator in such a manner that the behaviour index value follows the target behaviour index value, when the vehicle is not in the state of under-steer; means for controlling the braking forces at the vehicle wheels in such a manner that the behaviour index value follows the target behaviour index value, when the vehicle is not in the state of under-steer; and means for determining an instability index value correlating to the degree of under-steer.
A first aspect of the present invention further comprises: means for storing a predetermined first relationship between the behaviour index value, the target behaviour index value, the instability index value and a corrected behaviour index value for steering; means for determining the corrected behaviour index value for steering on the basis of the determined behaviour index value, the determined target behaviour index value, the determined instability index value, and the stored first relationship; means for storing a predetermined second relationship between the behaviour index value, the target behaviour index value, the instability index value and a corrected behaviour index value for braking; and means for determining the corrected behaviour index value for braking on the basis of the determined behaviour index value, the determined target behaviour index value, the determined instability index value, and the stored second relationship; wherein the first relationship is determined in such a manner, as the magnitude of the instability index value increases up to a predetermined set value, the deviation between the target behaviour index value and the corrected behaviour index value for steering decreases, and when the target behaviour index value and the behaviour index value are equal, the corrected behaviour index value for steering becomes equal to the behaviour index value; the second relationship is determined in such a manner that as the magnitude of the instability. index value increases up to a predetermined set value, the deviation between the target behaviour index value and the corrected behaviour index value for braking increases, and when the target behaviour index value and the behaviour index value are equal, the corrected behaviour index value for braking becomes equal to the behaviour index value; and when the vehicle is in the state of under-steer, the steering actuator is controlled in such a manner that the corrected behaviour index value for steering instead of the behaviour index value follows the target behaviour index value, and the braking forces are controlled in such a manner that the corrected behaviour index value for braking instead of the behaviour index value follows the target behaviour index value.
A second aspect of the present invention comprises: means for storing a predetermined first relationship between the behaviour index value, the target behaviour index value, the instability index value and a corrected target behaviour index value for steering; means for determining the corrected target behaviour index value for steering on the basis of the determined behaviour index value, the determined target behaviour index value, the determined instability index value, and the stored first relationship; means for storing a predetermined second relationship between the behaviour index value, the target behaviour index value, the instability index value and a corrected target behaviour index value for braking; and means for determining the corrected target behaviour index value for braking on the basis of the determined behaviour index value, the determined target behaviour index value, the determined instability index value, and the stored second relationship; wherein the first relationship is determined in such a manner, as the magnitude of the instability index value increases up to a predetermined set value, the deviation between the corrected target behaviour index value for steering and the behaviour index value decreases, and when the target behaviour index value and the behaviour index value are equal, the corrected target behaviour index value for steering becomes equal to the target behaviour index value; the second relationship is determined in such a manner that, as the magnitude of the instability index value increases up to a predetermined set value, the deviation between the corrected target behaviour index value for braking and the behaviour index value increases, and when the target behaviour index value and the behaviour index value are equal, the corrected target behaviour index value for braking becomes equal to the target behaviour index value; and when the vehicle is in the state of under-steer, the steering actuator is controlled in such a manner that the behaviour index value follows the corrected target behaviour index value for steering, instead of the target behaviour index value, and the braking forces are controlled in such a manner that the behaviour index value follows the corrected target behaviour index value for braking instead of the target behaviour index value.
According to each of the aspects of the present invention, when the vehicle is not in a state of under-steer, the steering actuator and braking forces at the wheels are controlled in such a manner that the deviation between the determined behaviour index value and the target behaviour index value for the vehicle corresponding to the amount of operation of the operating member is reduced, thereby stabilizing the vehicle behaviour.
According to the first aspect of the present invention, if the vehicle is in the state of under-steer, then the steering actuator is controlled in such a manner that the deviation between the corrected behaviour index value for steering, instead of the behaviour index value, and the target behaviour index value is reduced, and the braking forces are controlled in such a manner that the deviation between the corrected behaviour index value for braking, instead of the behaviour index value, and the target behaviour index value is reduced. As the amount of under-steer increases, the deviation between the target behaviour index value and the corrected behaviour index value for steering decreases, and the deviation between the target behaviour index value and the corrected behaviour index valu
Hayama Ryouhei
Kato Kazuhiro
Nakano Shiro
Nishizaki Katsutoshi
Segawa Masaya
Chin Gary
Jordan and Hamburg LLP
Koyo Seiko Co. Ltd.
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