Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-10-27
2001-04-10
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S048000
Reexamination Certificate
active
06216079
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle control system for stabilizing the behavior of a vehicle by controlling the braking force and the driving force applied to left and right wheels to generate a yaw moment, when the actual motion state of the vehicle deviates from a reference motion state.
2. Description of the Prior Art
There is a prior art vehicle control system which is designed, so that when a vehicle is in an unstable traveling state, whereby it is impossible to control the direction of movement of the vehicle according to a driver's will, a yaw moment for recovering control of the vehicle is generated to maintain a stable state by individually controlling the braking force and the driving force applied to left and right wheels.
With such a vehicle control system, a reference lateral slip angle and a reference yaw rate presumed to be generated by the vehicle in its stable state, are determined based on the vehicle speed and the steering operation conducted by a driver, and an actual lateral slip angle and an actual yaw rate actually generated in the vehicle are compared with the reference lateral slip angle and the reference yaw rate, respectively. To converge the deviations resulting from the comparison to 0 (zero), the braking force and the driving force applied to the left and right wheels are controlled individually in a feedback manner. Therefore, the following problems may occur.
If the vehicle is brought into a state in which the actual lateral slip angle and the actual yaw rate are smaller than the reference lateral slip angle and the reference yaw rate (i.e., into an under-steered state, for example), when the vehicle is traveling on a road near an exit of a curve, the conventional control allows a braking force to be applied to the inner wheels as viewed during turning of the vehicle, to generate a yaw moment in a direction to assist in the turning of the vehicle in order to eliminate the under-steered state. In the vehicle traveling near the curve exit where the curved road is changed to a straight road, however, the yaw moment in the direction to assist in the turning of the vehicle is generated excessively by the conventional control and hence, there is a possibility that a sense of incompatibility is provided to the driver. Such problem arises, because the conventional control is carried out based on a deviation between a reference direction of movement of the vehicle and an actual direction of movement of the vehicle, and the actual shape of the road is not taken in consideration. Namely, when the vehicle is traveling on the road near the exit of the curve, the control is carried out based on the traveling state on the current curved road and no consideration is given to the state in which the shape of the road ahead of the vehicle is such that a curved road is changed to a straight road. Therefore, the appropriate control adapted for the actual shape of the road cannot be conducted in some cases.
SUMMARY OF THE INVENTION
The present invention has been accomplished with the above circumstance in view, and it is an object of the present invention to ensure that proper control taking the shape of a road into consideration, can be carried out in a vehicle control system adapted to control at least one of the braking force and the driving force for the vehicle, to thereby inhibit an under-steered state and an over-steered state.
To achieve the above object, there is provided a vehicle control system comprising a motion state detecting means for detecting an actual motion state of a vehicle, based on parameters indicating the behavior of the vehicle, and a reference motion state determining means for determining a reference value for the motion state of the vehicle, based on the parameters indicating the behavior of the vehicle. A first comparing means compares the motion state of the vehicle detected by the motion state detecting means with the reference value determined by the reference motion state determining means, and an operation-amount calculating means calculates an operation amount for controlling the behavior of the vehicle, based on the result of the comparison by the first comparing means. A vehicle behavior control means controls at least one of a driving force and a braking force for the vehicle, based on the operation amount calculated by the operation amount-calculating means, wherein the vehicle control system further includes a road shape detecting means for detecting the shape of a road in the direction of movement of the vehicle, and an operation-amount correcting means corrects the operation amount calculated by the operation-amount calculating means, based on the shape of the road detected by the road shape detecting means.
With the above arrangement, in the system in which the operation amount for controlling the behavior of the vehicle is calculated based on the result of the comparison of the actual motion state of the vehicle with the reference motion state, and at least one of the braking force and the driving force for the vehicle is controlled based on the operation amount, the shape of the road in the direction of movement of the vehicle is detected, and the operation amount is corrected based on the shape of the road. Therefore, the control adapted for the actual shape of the road can be carried out to properly inhibit the under-steered state and the over-steered state.
In addition, the vehicle control system further include a vehicle movement-direction presuming means for presuming a direction of movement of the vehicle, based on the motion state of the vehicle detected by the motion state detecting means. A second comparing means compares the direction of movement of the vehicle presumed by the vehicle movement-direction presuming means with the shape of the road detected by the road shape detecting means, and correcting-amount calculating means calculates a correcting amount for correcting the operation amount, based on the result of the comparison by the second comparing means.
With the above arrangement, the operation amount is corrected based on the result of the comparison of the direction of movement of the vehicle presumed based on the actual motion state of the vehicle with the detected shape of the road. Therefore, the operation amount can be properly corrected in accordance with the degree of deviation of the direction of movement of the vehicle from the direction of the road.
Further, the operation-amount correcting means increases the operation amount calculated by the operation-amount calculating means, or hastens the start of control conducted based on the operation amount by the vehicle behavior control means.
With the above arrangement, the operation amount is increased, or the start of the control based on the operation amount is hastened in accordance with the deviation between the direction of movement of the vehicle and the detected shape of the road. Therefore, insufficiency of control can be avoided to permit the required effect to be sufficiently exhibited.
In addition, the operation-amount correcting means decreases the operation amount calculated by the operation-amount calculating means, or hastens the end of the control conducted based on the operation amount by the vehicle behavior control means.
With the above arrangement, the operation amount is decreased, or the end of the control based on the operation amount, is hastened in accordance with the deviation between the direction of movement of the vehicle and the detected shape of the road. Therefore, it is possible to prevent excessive control from being carried out.
The vehicle control system further includes a vehicle-position presuming means for presuming the position of the vehicle, based on the shape of the road detected by the road shape detecting means, and a road direction presuming means for presuming the direction of the road ahead of the vehicle, based on the position of the vehicle presumed by the vehicle-position presuming means and the shape of the road detected by the
Arent Fox Kintner & Plotkin & Kahn, PLLC
Gibson Eric M
Honda Giken Kogyo Kabushiki Kaisha
Zanelli Michael J.
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