Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Reexamination Certificate
1999-03-25
2001-07-31
Blum, Theodore M. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
C701S208000, C701S212000
Reexamination Certificate
active
06268825
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a navigation device for vehicles that not only gives route guidance but also controls a traveling controller, and more particularly to preparation of road shape data in a map database used by this device.
BACKGROUND ART
A navigation device that gives route guidance toward a destination is conventionally known and installation of this navigation device in vehicles is increasingly common. Such a navigation device identifies the present location of a vehicle at any time and stores road shape data on the shape of a road. Accordingly, the navigation device can also determine the curvature, etc. of a curve into which a vehicle is about to enter. Hereupon, the driver of the vehicle judges from the present vehicle speed whether or not the vehicle can safely negotiate the curve, and a system that issues an alarm or controls the deceleration of the vehicle has been proposed in case of necessity.
This proposed system uses a two-dimensional map in which the data of the plane shapes (X and Y) of a road is obtained from a topographical map as the road shape data, and the radius of curvature, etc. of a course is calculated using this two-dimensional map. Meanwhile, the lateral acceleration during turning when the vehicle travels on a curve with a radius of curvature R at a vehicle speed V can be estimated by V
2
/R. Hereupon, the turning safety is evaluated according to this lateral acceleration during turning and the coefficient of friction &mgr; between the road surface at that time and the tires of the vehicle. Then, the driver can issue an alarm and control the deceleration, etc. according to the result of evaluation.
Thereupon, to estimate the safety of vehicle movement on such a curve, the present location of the vehicle can accurately be identified and a map database with data, such as curvature (1/ R), a transverse slope (cant: &thgr;), and a lengthwise slope at each location on a road, are necessary. In other words, the lateral acceleration during turning ay of a vehicle body is given by
ay
(&tgr;)=(
V
(&tgr;))
2
/R
(&tgr;)−
g
×sin(&thgr;(&tgr;))
Where, in consideration of cant &thgr; of the road, it is assumed that the vehicle speed in the future (after &tgr; seconds) is V (&tgr;), the radius of curvature at the location is R (&tgr;), and the cant is &thgr;(&tgr;). At a sharp curve, to facilitate vehicle traveling, a cant of about up to 10% is frequently added, and accurate lateral acceleration can be forecast only when the addition of this cant is considered. Further, because the lengthwise slope of the road also affects the change of vehicle speed and the allocation of vertical tire load on each wheel, the addition of this cant also affects the evaluation of traveling stability.
However, the map database used in the present navigation system includes no cant data. Although the radius of curvature R and the lengthwise slope can be calculated from the location data and altitude data, the calculated R value includes great errors because data spacing is considerably wide. In other words, in the normal map database, location data is only provided for every map point set on a road at intervals of several 10 to several 100 meters, and it was difficult to accurately calculate the shape of a curve.
To forecast curve traveling stability accurately, the map database must be made more accurate. However, immense cost and man-hour would be required to solve this problem. Further, when preparing the map data at fine pitches, there was a problem that the data processing workload increased owing to the large amount of data required to perform the map display and route calculation using the data.
In the Japanese Patent Laid-Open Publication No. Hei 5-238405, a device that stores places requiring attention where the vehicle traveling became unstable due to the vehicle movement obtained when the vehicle actually traveled on the road is proposed. However, this device neither prepares a detailed map database nor accurately forecasts vehicle movement.
DISCLOSURE OF THE INVENTION
The objects of the present invention are to provide a vehicle navigation device that can accurately forecast vehicle movement using detailed data and can also perform effective processing for route guidance, a road shape data preparation device in the map database used thereof, and its method.
The present invention comprises a self-vehicle location detection means that detects the self-vehicle location, a map database that stores road information, a traveling control system control means that controls the traveling controller of the vehicle based on the self-vehicle location detected by the said self-vehicle location detection means and the road information read from the said map database, and a navigation means that gives guidance regarding the vehicle traveling based on the self-vehicle location detected by the said self-vehicle location detection means and the road information read from the map database, wherein the level of detail of the road information read from the map database by the navigation means is reduced to less than the level of detail of the road information read from the map database by the traveling control system control means.
According to the present invention, the level of detail of the road information to be read can be changed. For example, the level of detail can be changed by independently handling simplified and detailed map databases. In such a configuration, the route guidance uses the road information having the degree of low particularity, for example, the road shape data read from the simplified map database. Accordingly, appropriate route search and map display processing can be performed as usual. Meanwhile, to control the traveling controller, detailed road information, for example, the detailed road shape data read from the detailed map database, is used. Accordingly, the traveling stability of the vehicle can be evaluated with sufficient accuracy.
Further, in the present invention, the map database comprises the simplified map database that stores the road information for every location coordinate at a prescribed pitch and the detailed map database that stores the road information for every location coordinate at a more detailed pitch than the prescribed pitch in this simplified map database, wherein the said traveling control system control means controls the vehicle traveling controller based on the road information stored in the said detailed map database, and the said navigation means gives guidance regarding the vehicle traveling based on the road information stored in the said simplified map database.
Because the simplified map database includes only location data for every map point per, for example, several 10 to several 100 meters, curve can not be identified with sufficient accuracy. The present invention, however, does enable such curves to be identified accurately because it uses road shape data with more detail. Moreover, traveling stability can be more accurately evaluated by storing in the detailed map database data, such as the cant, the radius of curvature, and the lengthwise slope.
The present invention further may comprise a traveling status detection means that detects the traveling status data of a self-vehicle, wherein the said detailed map database can be updated based on the traveling status data obtained by this traveling status detection means and the self-vehicle location obtained by the self-vehicle location detection means.
Because detailed road shape data is obtained according to the vehicle's movement, the map data regarding all the roads of the whole country need not be prepared. Further, because the more detailed road shape data is obtained according to the movement, the detailed map database is easy to prepare.
The present invention relates to media on which a navigation program that gives guidance regarding the aforementioned vehicle traveling by a computer is recorded. Various types of such recording media may be used, such as ROM, RAM, and CD-ROM, and information may be downloaded
Blum Theodore M.
Pillsbury & Winthrop LLP
Toyota Jidosha & Kabushiki Kaisha
LandOfFree
Navigation device for vehicle and preparation of road shape... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Navigation device for vehicle and preparation of road shape..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Navigation device for vehicle and preparation of road shape... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2471044