Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-07-13
2001-12-04
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
C701S301000, C342S455000, C340S903000
Reexamination Certificate
active
06327530
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and a method for controlling a distance between two traveling vehicles and a recording medium for storing the control method.
To improve the safety in a vehicle driving operation and reduce the driver's burden, an apparatus for automatically controlling a distance between two traveling vehicles is conventionally proposed. For example, a relative speed between the system's vehicle and a preceding vehicle is obtained. A target distance is determined in accordance with the detected relative speed (i.e., speed deviation between two vehicles). An actual distance between the system's vehicle and the preceding vehicle is detected. To eliminate the distance deviation between the actual distance and the target distance, an appropriate target acceleration is set to control an internal combustion engine of the vehicle and/or a braking apparatus so as to realize the target acceleration.
The target distance is fixed to a predetermined value when the vehicle speed is constant. The target distance is changeable in accordance with the change of the vehicle speed. The target acceleration is thus calculated based on the distance deviation between the actual distance and the target distance corresponding to the present vehicle speed.
In other words, when the distance deviation is a same value, a same target acceleration is obtained regardless of the difference in the target distance set by the driver. This makes drivers uncomfortable.
For example, the driver may set a relatively long target distance in a first driving condition and a relatively short target distance in a second driving condition. It is assumed that the distance deviation is same for both cases. In this case, unless there are any other different conditions, the same target acceleration will be obtained for both cases.
However, it depends on the target distance whether the driver preferably accepts the obtained target acceleration or not. More preferably, the driver may think that the obtained target acceleration is preferable when he or she selects the relatively long target distance. However, this driver possibly feels that the same target acceleration is inappropriate when he or she selects the relatively short target distance. On the other hand, other drivers may think that the obtained target acceleration is inappropriate for the relatively long target distance and rather preferable for the relatively short target distance.
When the target acceleration is appropriate for maintaining the long target distance, the same target acceleration will be too moderate or dull for the system's vehicle to approach to or depart from the preceding vehicle to maintain the short target distance. On the contrary, when the target acceleration is appropriate for maintaining the short target distance, the same target acceleration will be too abrupt or steep for the system's vehicle to approach to or depart from the preceding vehicle to maintain the long target distance.
It is believed that such problems come from the improperness of the conventional distance control method because the absolute value of the distance deviation is solely used to control the target acceleration of the system's vehicle.
SUMMARY OF THE INVENTION
In view of the foregoing, the present invention has an object to solve the problems caused by the conventional distance control method.
An object of the present invention is to provide a control apparatus and a method capable of optimizing the vehicle behavior during the distance control so as to fit to driver's feeling and also to provide the vehicle automatic control accepted by every driver.
An object of the present invention is to provide an apparatus and a method for controlling the distance between two traveling vehicles based on a predesignated control ratio, such as a ratio of a distance deviation to the target distance.
An object of the present invention is to provide a recording medium for storing a computer program relating to the distance control method realized by the present invention.
To accomplish the above and other related objects, one aspect of the present invention provides a distance control apparatus for controlling a space between two traveling vehicles. The control apparatus comprises an acceleration/deceleration means for accelerating and decelerating a vehicle. A relative speed detecting means is provided for obtaining a relative speed between two traveling vehicles. A control ratio detecting means is provided for obtaining a control ratio of an actual value to a target value. A target control value generating means is provided for generating a target control value required for controlling the space between the two traveling vehicles. The target control value is determined based on the control ratio obtained by the control ratio detecting means in addition to the relative speed obtained by the relative speed detecting means. A control means is provided for activating the acceleration/deceleration means in accordance with the target control value generated by the target control value generating means.
Preferably, the actual value is a value directly or indirectly representing an actual distance between the two traveling vehicles, and the target value is a value directly or indirectly representing a target distance between the two traveling vehicles.
For example, the actual value is the actual distance itself and the target value is the target distance itself. When the actual distance is 90 m and the target distance is 100 m, the control ratio becomes {fraction (9/10)} (={fraction (90/100)}). In this case, the control ratio represents the degree of how the system's vehicle is positioned closely to the target position. When the control ratio is 1, the actual distance is equal to the target distance. Thus, the acceleration/deceleration means is controlled so as to equalize the control ratio to 1.0.
According to a preferred embodiment of the present invention, the actual value is a distance deviation between the actual distance and the target distance, and the target value is the target distance. The control ratio becomes −{fraction (1/10)} (=(90−100)/100) when the actual distance is 90 m and the target distance is 100 m. In this case, the acceleration/deceleration means is controlled so as to equalize the control ratio to 0.
According to another preferred embodiment of the present invention, the actual value is an actual time interval obtained by dividing the actual distance by a present vehicle speed, and the target value is a target time interval obtained by dividing the target distance by the present vehicle speed.
According to another preferred embodiment of the present invention, the actual value is a time interval deviation between the actual time interval and the target time interval, and the target value is the target time interval.
Regarding the target control value for the acceleration/deceleration means, it is preferable to select the target control value from the group consisting of a target acceleration, a target torque, and a target vehicle speed.
Another aspect of the present invention provides a distance control method for controlling a space between two traveling vehicles. According to the control method of the present invention, a relative speed between two traveling vehicles is obtained. A control ratio of an actual value to a target value is obtained. A target control value required for controlling the space between the two traveling vehicles is generated based on the control ratio in addition to the relative speed. An acceleration/deceleration means is actuated in accordance with the target control value.
Another aspect of the present invention provides a recording medium storing a control program for controlling the space between two traveling vehicles in accordance with the present invention.
REFERENCES:
patent: 5396426 (1995-03-01), Hibino et al.
patent: 5485155 (1996-01-01), Hibino
patent: 5574463 (1996-11-01), Shirai et al.
patent: 5627511
Isogai Akira
Nishimura Takao
Teramura Eiji
Cuchlinski Jr. William A.
Denso Corporation
Donnelly Arthur D.
Pillsbury & Winthrop LLP
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