Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Utility Patent
1998-04-07
2001-01-02
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
C340S438000, C340S905000, C701S208000
Utility Patent
active
06169952
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system for determining the passability of a vehicle, which involves perceiving a shape of a road based on map data comprised of an aggregation of a plurality of nodes and determining whether the vehicle can pass through the nodes.
2. Description of the Related Art
Such a system for determining the passability of the vehicle is known from Japanese Patent Application Laid-open No. 5-141979, wherein a radius of curvature of a curve of a road is presumed by calculating a radius of an arc passing through three nodes, and a passable speed of the vehicle calculated based on the radius of curvature of this curve is compared with a passage-predicting speed of the vehicle calculated based on a current vehicle speed. If the passage-predicting speed is equal. to or lower than the passable speed, it is determined that the vehicle can pass through the curve.
In the above conventional system, if three nodes N
1
, N
2
and N
3
exist on the same curve, as shown in
FIG. 12A
, a radius R of curvature of the curve can be correctly presumed. However, the above conventional system suffers from the following problem: If central one of the three nodes N
1
, N
2
and N
3
exists on a curve and the nodes N
1
and N
3
in front and in rear of the central node are out of the curve, as shown in
FIG. 12B
, a radius R′ of curvature of the curve presumed from the three nodes N
1
, N
2
and N
3
is larger than an actual radius R of curvature of the curve and hence, the shape of the curve cannot be correctly perceived.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to ensure that even when three or more nodes do not exist on the same curve, it can be correctly determined whether the vehicle can pass through the nodes.
To achieve the above object, according to the present invention, there is provided a system for determining the passability of a vehicle, comprising map information outputting means for outputting a map information as an aggregation of a plurality of nodes constituting a road section, subject-vehicle position detecting means for detecting a position of the subject vehicle on a map, curve section determining means for determining whether a node ahead of the subject vehicle position exists on a curve section, passing-state determination amount calculating means for calculating a passing-state determination amount of the node existing on the curve section as a value resulting from division of an amount of variation in azimuth angle of the vehicle by a distance of movement of the vehicle, and passability determining means for determining whether the vehicle can pass through the node existing on the curve section, based on the passing-state determination amount.
With the above arrangement, if it is determined whether the node ahead of the subject vehicle position exists on the curve section, the system determines whether the vehicle can pass through the node existing on the curve section. The need for determining whether the vehicle can pass through a node existing on a straight road section is thereby eliminated, resulting in few calculations being performed. In addition, the passing-state determination amount is calculated from dividing the amount of variation in azimuth angle of the vehicle by the distance of movement of the vehicle. The passing-state determination amount thus serves to accurately represent a degree of difficulty in the passage of the vehicle through the node. Even when only one or two nodes exist on a curve, it is possible to accurately determine whether the vehicle can pass through the curve.
In addition to the above feature, the amount of variation in azimuth angle of the vehicle is calculated as an angle formed by a line segment connecting the adjacent nodes and the distance of movement of the vehicle is calculated based on a distance between the adjacent nodes. The amount of variation in azimuth angle and the distance of movement can be easily and accurately calculated.
In addition to the above feature, the system further includes passable speed calculating means for calculating a passable speed enabling the vehicle to pass the node existing on a curved road section, based on the passing-state determination amount, and a preset lateral acceleration limit in order for the vehicle to pass through the node. The passing-state determination amount may be defined according to the following equation:
passable speed=(preset limit lateral acceleration/passing-state determination amount)
½
Thus, it is possible to accurately calculate a passable speed which does not exceed the preset lateral acceleration limit.
In addition to the above feature, the system further includes passable speed calculating means for calculating a passable speed enabling the vehicle to pass the node existing on a curved road section, based on the passing-state determination amount. The passable speed calculating means calculates the passable speed based on a preset yaw rate limit that is permissible in the passage of the vehicle through the node, and the passing-state determination amount according to the following equation:
passable speed=preset limit yaw rate/passing-state determination amount
Thus, it is possible to accurately calculate a passable speed which does not exceed the preset yaw rate limit.
REFERENCES:
patent: 5539397 (1996-07-01), Asanauma et al.
patent: 5546311 (1996-08-01), Sekine
patent: 5661650 (1997-08-01), Sekine et al.
patent: 5-141979 (1993-06-01), None
patent: 8-147598 (1996-06-01), None
Matsuda Shohei
Otabe Makoto
Sakaki Yuji
Blackman William D.
Carrier Joseph P.
Carrier Blackman & Associates P.C.
Cuchlinski Jr. William A.
Honda Giken Kogyo Kabushiki Kaisha
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