Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-05-25
2001-10-09
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S079000, C701S080000, C303S150000, C303S157000, C303S183000
Reexamination Certificate
active
06301540
ABSTRACT:
This application claims priority under 35 U.S.C. Sec. 119 to No.10-162947 filed in Japan on May 26, 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 system for detecting a difference in road level, and more particularly to a system for determining if there is a difference in level on a road for vehicles by means of a linear longitudinal acceleration sensor.
2. Description of the Related Arts
Various anti-skid control systems have been proposed heretofore to prevent a wheel from being locked during a braking operation of a vehicle. For example, Japanese Patent Laid-open Publication No.5-294226 discloses an anti-skid control system which is adapted to detect a road giving a rapid variation of surface reaction force, such as a road with a difference in level, and prevent a hydraulic barking pressure from being reduced, or increase a pressure increasing gradient of the hydraulic braking pressure, thereby to improve the feeling in driving a vehicle. In the anti-skid control system as disclosed in the above-described publication, there is provided a road surface detection system which compares a wheel acceleration and a wheel speed which is reduced just before the ant-skid control starts, or just after it started, with respective predetermined levels, to determine if the road, on which the vehicle travels under the anti-skid control, is giving the rapid variation of surface reaction force.
According to the road surface detection system as disclosed in the above-described Japanese Patent Laid-open Publication No.5-294226, the difference in level on the road is detected on the basis of the reduced wheel acceleration and wheel speed, or recovered wheel acceleration and wheel speed. Therefore, vibration or the like of driven wheels might result in misjudgment of the difference in level on the road, especially on a road of low coefficient of friction. In the case where the above-described road surface detection system is used for the anti-skid control, it is necessary to prevent the wheels from being locked rapidly on the road of low coefficient of friction.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a system for detecting a difference in level on a road for vehicles, to properly determine if a vehicle is traveling on the road with difference in level.
It is another object of the present invention to provide a system for properly detecting a difference in level on a road for vehicles, thereby to perform an anti-skid control or a traction control smoothly.
In accomplish the above and other objects, a system for detecting a difference in level on a road for vehicles is proposed herein. The system includes an acceleration sensor, which detects an acceleration of a vehicle and produce a signal proportional to the acceleration. A first determination device is provided for determining if a variation of the signal output from the acceleration sensor is greater than a predetermined range. A wheel speed detection device is provided for detecting a wheel speed of at least one wheel of the vehicle. A wheel acceleration calculating device is provided for calculating a wheel acceleration of the wheel continuously on the basis of the wheel speed detected by the wheel speed detection device. And, a second determination device is provided for determining if the wheel acceleration calculated by the wheel acceleration calculating device varied in the same direction as that of the variation of the signal output from the acceleration sensor, and then varied in the reverse direction to exceed a predetermined reference value. Then, a level difference determination device is provided for determining if the wheel ran over a difference in level on a road, on the basis of the results determined by the first and second determination devices. The first determination device may be adapted to determine if the variation of the signal output from the acceleration sensor is greater than the predetermined range, on the basis of a variation of the wheel acceleration calculated by the wheel acceleration calculating device.
In the above-described system, the first determination device may be adapted to determine if a decelerating variation of the signal output from the acceleration sensor is greater than a predetermined decelerating range, and the second determination device may be adapted to determine if the wheel acceleration calculated by the wheel acceleration calculating device has been increased after the wheel acceleration was decreased, to exceed a predetermined acceleration.
Or, the first determination device may be adapted to determine if an accelerating variation of the signal output from the acceleration sensor is greater than a predetermined accelerating range, and the second determination device may be adapted to determine if the wheel acceleration calculated by the wheel acceleration calculating device has been decreased after the wheel acceleration was increased, to become lower than a predetermined deceleration.
REFERENCES:
patent: 4900100 (1990-02-01), Higashimata et al.
patent: 4903982 (1990-02-01), Harara et al.
patent: 5132907 (1992-07-01), Ishikawa
patent: 5236255 (1993-08-01), Kuwana et al.
patent: 5423601 (1995-06-01), Sigl
patent: 6045198 (2000-04-01), Naito et al.
patent: 39 33 652 (1991-04-01), None
patent: 5-213178 (1993-08-01), None
patent: 5-294226 (1993-11-01), None
Abe Yasuhiro
Banno Masaki
Kato Toshihisa
Matsubayashi Hiroyuki
Tsugawa Shinji
Aisin Seiki
Burns Doane , Swecker, Mathis LLP
Cuchlinski Jr. William A.
To Tuan C
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