Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-08-20
2001-03-13
Chin, Gary (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S037000, C073S105000
Reexamination Certificate
active
06202020
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to methods and systems for determining the condition of the road travelled by an automotive vehicle for use in controlling the vehicle.
Various methods have been developed to aid a driver of a vehicle to stop on unstable road conditions, such as icy or water-covered roads. For example, anti-lock brake systems work to eliminate, or at least minimize, slippage of the wheels when the brakes are applied so as to maintain control of the vehicle on undesirable surface conditions. However, in these instances, it is not until the brakes are applied that the condition of the road is determined. The braking must then be adjusted even further.
Thus, it is desirable to determine the condition of the road prior to applying brakes to the wheels so that proper braking is initiated at the beginning of the braking cycle. It is also desirable to warn the driver of undesirable road conditions so that appropriate acceleration, steering and braking can be applied accordingly.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and system for determining the condition of the road travelled by a vehicle.
It is yet another object of the present invention to provide a method and system for providing a visual warning to the driver of the vehicle when the speed of the vehicle is inappropriate based on the road conditions.
Still further, it is an object of the present invention to provide a method and system for controlling braking of the vehicle based on a-priori knowledge of the condition of the road.
A method and system for determining the condition of a road travelled by a vehicle includes a sensor for sensing a speed of the vehicle and an accelerometer for sensing a vertical acceleration of the vehicle. A central processing unit determines a first road profile interval having upper and lower threshold values based on the speed of the vehicle and the condition of the road based on the vertical acceleration and the first road profile interval. Based on whether the road is rough or smooth, the vehicle's suspension or braking system can be controlled accordingly.
The first road profile interval is based on the mean vehicle speed and maximum and minimum vertical acceleration values representative of rough and smooth road conditions, respectively. If the sensed vertical acceleration exceeds the maximum vertical acceleration value, a rough road condition is determined. On the other hand, if the sensed vertical acceleration is less than the minimum vertical acceleration value, a smooth road surface is detected.
In a preferred embodiment, a second road profile interval having upper and lower threshold values representative of the maximum and minimum vertical acceleration distributions corresponding to rough and smooth roads, respectively, is utilized. The condition of the road is further determined based on a comparison of the vertical acceleration and the second road profile threshold if the vertical acceleration falls within the first road profile interval. In this embodiment, a standard deviation of the vertical acceleration is determined. If the standard deviation of the vertical acceleration exceeds the upper threshold value of the second road profile interval, then a rough road condition is determined. Again, if the standard deviation of the vertical acceleration is less than the lower threshold value of the second road profile interval, a smooth road condition is detected.
In yet another embodiment, a dynamic coefficient of friction corresponding to the minimum coefficient of friction required to achieve a particular change in vehicle speed is determined. The dynamic coefficient of friction is compared to a predetermined threshold, and if the dynamic coefficient of friction is less than the predetermined threshold, the vehicle is travelling at an excessive speed.
The dynamic coefficient of friction is determined in one of two ways. In a first method, a fore/aft acceleration of the vehicle is sensed and the dynamic coefficient of friction is determined based on a current value of the fore/aft acceleration and a previous value of the fore/aft acceleration. In an alternative method, a distance traveled by a pair of wheels of the vehicle is determined over a predetermined time interval. The dynamic coefficient of friction is determined based on the distance traveled by the pair of wheels and the speed of the vehicle over the predetermined time interval.
The dynamic coefficient of friction can then be displayed to the driver of the vehicle for use in controlling the vehicle. The central processing unit can also control the vehicle in response to the dynamic coefficient of friction. Here, a braking system of the vehicle can be controlled to avoid slippage on a smooth, icy road.
These and other features of the present invention can be understood from the following specification and drawings.
REFERENCES:
patent: 4422322 (1983-12-01), Spangler
patent: 4651290 (1987-03-01), Masaki et al.
patent: 4666218 (1987-05-01), Masaki et al.
patent: 4809197 (1989-02-01), Tashiro et al.
patent: 4837727 (1989-06-01), Tashiro et al.
patent: 4883325 (1989-11-01), Shimanuki et al.
patent: 4984163 (1991-01-01), Kuwana et al.
patent: 5085288 (1992-02-01), Shiraishi et al.
patent: 5123715 (1992-06-01), Okubo
patent: 5229955 (1993-07-01), Nishiwaki et al.
patent: 5833328 (1998-11-01), Matsuda
patent: 5900819 (1999-05-01), Kyrtsos
Carlson & Gaskey & Olds
Chin Gary
Meritor Heavy Vehicle Systems LLC
LandOfFree
Method and system for determining condition of road does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for determining condition of road, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for determining condition of road will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2437551