Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication
Reexamination Certificate
2001-02-27
2003-04-22
Nguyen, Thu (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
C342S454000, C340S437000, C180S169000
Reexamination Certificate
active
06553283
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 and delineators on the sides of the road.
Japanese patent application publication number 5-159199 discloses a warning system for a vehicle. The system in Japanese application 5-159199 emits a forward laser beam from the body of the vehicle, and controls the forward laser beam to periodically scan a given angular region in front of the body of the vehicle. In the case where an object exists in the given angular region, the forward laser beam encounters the object before being at least partially reflected thereby. A portion of the reflected laser beam returns to the system as an echo laser beam. The system detects the object in response to the echo laser beam. In addition, the system calculates the distance to the object from the time interval between the moment of emission of the forward laser beam and the moment of reception of the related echo laser beam. In the system of Japanese application 5-159199, a decision is made as to whether or not the distance to the object monotonically changes. When it is decided that the distance to the object monotonically changes, the object is judged to be a reflector on a curved road side. In this case, the system stops the generation of an alarm.
The system of Japanese application 5-159199 does not discriminate a reflector on a right-hand road side and a reflector on a left-hand road side from each other. Therefore, it is difficult for the system to distinctively recognize a right-hand road edge and a left-hand road edge.
Japanese patent application publication number 8-249598 discloses an apparatus for sensing delineators and recognizing a road shape from information about the sensed delineators. The apparatus in Japanese application 8-249598 emits a forward electromagnetic wave beam from the body of the vehicle, and controls the forward electromagnetic wave beam to periodically scan a given angular region in front of the body of the vehicle. In the case where an object exists in the given angular region, the forward electromagnetic wave beam encounters the object before being at least partially reflected thereby. A portion of the reflected electromagnetic wave beam returns to the apparatus as an echo electromagnetic wave beam. The apparatus detects the object in response to the echo electromagnetic wave beam. Specifically, the apparatus calculates the distance to the object from the time interval between the moment of emission of the forward electromagnetic wave beam and the moment of reception of the related echo electromagnetic wave beam. In addition, the apparatus calculates the direction of the object relative to the vehicle.
The apparatus in Japanese application 8-249598 decides whether each detected object is a delineator on a right-hand road side or a delineator on a left-hand road side in response to the horizontal variation in the position of the object relative to the vehicle. For example, decided delineators on a right-hand road side are linked by lines, and the set of the lines is recognized as a right-hand road edge. In the apparatus of Japanese application 8-249598, the decision as to whether each detected object is a right-hand delineator or a left-hand delineator is responsive to the horizontal variation in the relative position of the object. Therefore, it is difficult to implement the decision regarding an object detected for the first time. The result of the decision tends to be inaccurate when the horizontal variation in the relative position of an object is small or when the sign of the horizontal variation in the relative position of an object inverts.
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 the 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.
Japanese patent application publication number 7-270536 discloses an object determination apparatus for a vehicle. The apparatus in Japanese application 7-270536 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 7-270536 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 are sorted with respect to distance. Each continuity between two adjacent objects among the detected objects is judged, and the detected objects are separated into groups in response to the judgement results. According to the total number of the objects in each group and the relation among the relative positions thereof, it is decided whether they are discrete objects or continuous objects. The continuous objects are recognized as road facilities, while the discrete objects are recognized as preceding vehicles.
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 the time-domain variation in the relative position of a road-side object is unknown.
It is a second object of this invention to provide an apparatus for accurately recognizing the shape of a road even when the time-do
Morikawa Katsuhiro
Shirai Noriaki
Denso Corporation
Law Offices of David G. Posz
Nguyen Thu
LandOfFree
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