Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Patent
1998-08-07
2000-03-21
Nguyen, Tan
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
701 78, 180197, B60T 800
Patent
active
060412771
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method of improving the control behavior of an ABS system.
Electronically controlled anti-lock systems (ABS) are state of the art and customary on the market in many different designs. The most important or exclusive input quantity for braking pressure control is the rotational behavior of the individual vehicle wheels which is measured by wheel sensors. A vehicle reference speed is produced by logically combining the measured quantities. The vehicle reference speed is used instead of the actual vehicle speed as a reference quantity to define the wheel slip and other control quantities and, thus, as a reference quantity for braking pressure control during an anti-lock control operation.
It is well known and can be easily observed that the control of an anti-lock system (ABS) responds in some situations although there is no reason for response. One example is the triggering of a control operation by a so-called single disturbance, i.e., by a major road surface disturbance due to a depression or a pothole, a threshold, or the like. If such a disturbance occurs in the partial braking range, i.e., during an uncontrolled braking operation, the effects of the disturbance will at least irritate the driver. Also, the major pressure relief or pressure reduction due to the wheel deceleration results in a reduced deceleration which is disadvantageous.
Therefore, an object of the present invention is to provide an improved control behavior of an ABS system and, more particularly, to suppress the unwanted effects of single disturbances in the road surface.
SUMMARY OF THE INVENTION
The present invention is based on the principle that defined criteria and data, which can be acquired from the wheel rotational behavior, are an indicator of single road surface disturbances, and that the single disturbances can be counteracted by an `additional` pressure increase. Therefore, according to the present invention, upon the commencement of an anti-lock control operation subsequent to a partial braking operation and the occurrence of an acceleration or reacceleration of the controlled wheel which is in excess of a predetermined limit value, a quotient is calculated from the maximum brake slip of the wheel and the duration of pressure reduction due to this brake slip until the reacceleration of the wheel, and the exceeding of a predetermined limit value of this quotient is assessed as identification of a single disturbance. Thereafter, according to the method of the present invention, the braking pressure on the wheel where the single disturbance occurred is increased until the acceleration falls below a predetermined limit value with a steeper braking pressure gradient compared to a normal control operation.
The method of the present invention is used especially for the front-wheel control. The precondition is a defined minimum deceleration caused by the partial braking operation. When the control system includes yaw torque management, such management is deactivated while single disturbances are `overcome`.
Further details of the present invention can be seen in the following description of embodiments making reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings,
FIG. 1 is a wiring diagram to illustrate the principle of the improved control according to the method of the present invention.
FIG. 2 is a flow chart showing the operation.
FIG. 3 is a diagram showing the variation of the vehicle deceleration, the wheel speed and the braking pressure in the associated wheel as a result of single disturbances in the road surface.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 shows the essential electric and electronic components of a brake system with wheel lock control or an anti-lock system (ABS). The drawing is used to explain the operation of an ABS and the way the method of the present invention functions. Each vehicle wheel in this embodiment includes a wheel sensor S1 to S4 which issues a signal representative of the rotation
REFERENCES:
patent: 4923255 (1990-05-01), Braschel et al.
patent: 5357434 (1994-10-01), Zimmer et al.
Batistic Ivica
Schmidt Robert
ITT Maufacturing Enterprises, Inc.
Nguyen Tan
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