Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
2001-02-23
2003-04-22
Beaulieu, Yonel (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Reexamination Certificate
active
06553282
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of recognizing the shape of a road which can be used by, for example, a system provided on a vehicle. In addition, this invention relates to an apparatus for recognizing the shape of a road which can be used by, for example, a system provided on a vehicle. Furthermore, this invention relates to a recording medium which stores a computer program for recognizing the shape of a road.
2. Description of the Related Art
A known obstacle detecting apparatus for a vehicle emits a forward wave beam such as a light beam or a millimeter wave beam from the body of the vehicle, and controls the forward wave beam to periodically scan a given angular region in front of the body of the vehicle. In the case where an obstacle exists in the given angular region, the forward wave beam encounters the obstacle before being at least partially reflected thereby. A portion of the reflected wave beam returns to the apparatus as an echo wave beam. The apparatus detects the obstacle in response to the echo wave beam.
The known obstacle detecting apparatus is used in a warning system for a vehicle which alarms when an obstacle such as a preceding vehicle exists in a given angular region in front of the present vehicle. The known obstacle detecting apparatus is used also in a system for a vehicle which controls the speed of the vehicle to maintain a proper distance between the vehicle and a preceding vehicle.
The known obstacle detecting apparatus additionally has the function of determining whether or not the detected obstacle is a preceding vehicle. In general, this determination is responsive to the output signals from a steering angle sensor and a yaw rate sensor. In the case where the present vehicle is traveling along a straight portion of a road while a preceding vehicle is traveling along a curved road portion extending ahead of the straight road portion, the known obstacle detecting apparatus has a chance of erroneously determining the preceding vehicle.
In view of such a problem in the known obstacle detecting apparatus, it is proposed to recognize the shape of a road from objects on the sides of the road such as delineators. When there is a plurality of sensed delineators, a road edge or edges can be detected from the sensed delineators. On the other hand, when there is only one sensed delineator, a road edge can not be detected.
Japanese patent application publication number 8-249598 discloses an apparatus for sensing delineators and recognizing a road shape from information about the sensed delineators. According to Japanese application 8-249598, in the case where only one sensed delineator exists, a road shape is recognized from the trajectory or locus of the delineator which reflects relative motion between the present vehicle and the delineator. When the present vehicle is traveling along a curved road with a constant radius of curvature, it is possible to accurately recognize the road shape from the trajectory of the delineator. The accurate recognition of the road shape provides accurate detection of a preceding vehicle. On the other hand, when the present vehicle is traveling along a curved road with a varying radius of curvature, the shape of a road portion extending ahead of the sensed delineator can not be accurately recognized from the delineator trajectory.
Japanese patent application publication number 10-239436 discloses an apparatus for detecting the vehicle-to-vehicle distance. The apparatus in Japanese application 10-239436 emits a forward laser beam, and controls the forward laser beam to periodically scan a given angular region in front of the body of the present vehicle. The apparatus in Japanese application 10-239436 detects objects in the given angular range from return laser beams coming therefrom. Specifically, the apparatus detects the distances to the objects and the directions (the angular positions) of the objects relative to the present vehicle. The detected objects include reflectors on the right-hand and left-hand sides of a road. In the apparatus of Japanese application 10-239436, the shape of the road is recognized from the loci (trajectories) of detected reflectors on the road sides. The apparatus of Japanese application 10-239436 has a problem similar to that in the apparatus of Japanese application 8-249598.
SUMMARY OF THE INVENTION
It is a first object of this invention to provide a method of accurately recognizing the shape of a road even when only one sensed delineator exists.
It is a second object of this invention to provide an apparatus for accurately recognizing the shape of a road even when only one sensed delineator exists.
It is a third object of this invention to provide a recording medium which stores a computer program for accurately recognizing the shape of a road even when only one sensed delineator exists.
A first aspect of this invention provides a method of applying a transmission wave to a predetermined angular range in a width-wise direction of a vehicle, and recognizing a shape of a road extending ahead of the vehicle on the basis of a reflected wave which results from reflection of the transmission wave. The method comprises the steps of detecting a position of each object and a relative speed of the object on the basis of the reflected wave; determining whether each object is moving or stationary on the basis of the detected relative speed of the object and a speed of the vehicle; for at least one of right-hand and left-hand sides of the vehicle, calculating and memorizing a vehicle width-wise direction position where each stationary object effective for road shape recognition passes through the related side of the vehicle on the basis of the detected position of the object and a result of determining whether the object is moving or stationary; and recognizing a line connecting the memorized vehicle width-wise direction position and the detected position of the currently handled object corresponding to the effective stationary object as a road edge.
A second aspect of this invention is based on the first aspect thereof, and provides a method further comprising the steps of calculating and memorizing an average vehicle width-wise direction position among the calculated vehicle width-wise direction positions; and using the average vehicle width-wise direction position in the road edge recognition.
A third aspect of this invention provides an apparatus for recognizing a road shape. The apparatus comprises radar means for applying a transmission wave to a predetermined angular range in a width-wise direction of a vehicle, and detecting a position of each object on the basis of a reflected wave which results from reflection of the transmission wave; and recognizing means for recognizing a shape of a road extending ahead of the vehicle on the basis of a result of detection by the radar means. The recognizing means comprises 1) object recognizing means for detecting a position of each object and a relative speed of the object on the basis of the result of detection by the radar means, and for determining whether the object is moving or stationary on the basis of the detected relative speed of the object and a speed of the vehicle; 2) position calculating and memorizing means for, regarding at least one of right-hand and left-hand sides of the vehicle, calculating and memorizing a vehicle width-wise direction position where each stationary object effective for road shape recognition passes through the related side of the vehicle on the basis of a result of function by the object recognizing means; 3) correspondence determining means for determining whether or not an object currently handled by the object recognizing means corresponds to the vehicle width-wise direction position memorized by the position calculating and memorizing means; and 4) road edge recognizing means for, in cases where the correspondence determining means determines that the object currently handled by the object recognizing means corresponds to the vehicle width-wise direction positi
Morikawa Katsuhiro
Shirai Noriaki
Beaulieu Yonel
Posz & Bethards, PLC
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