Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
2001-04-10
2002-05-07
Camby, Richard M. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S207000, C701S210000, C340S988000
Reexamination Certificate
active
06385536
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a navigation apparatus, a method for map matching performed in the navigation apparatus, and a computer-readable medium storing a program for executing the method.
2. Description of the Prior Art
Conventional navigation apparatuses are capable of computing recommended routes based on destination data established by a user (e.g., driver) and vehicle information such as vehicle speed, the current position of the vehicle and the like. Further, the conventional navigation apparatuses are capable of displaying the computed recommended routes on a screen to provide route guidance to the user..
Further, the conventional navigation apparatuses are also capable of carrying out a map matching process. In this map matching process, first the conventional navigation apparatus compares the “shape” of a vehicle's route that the vehicle has passed to the “actual road layout.” Then, the navigation apparatus “matches” the vehicle's actual location on the road to its position on a digital road map on the screen.
Furthermore, the conventional navigation apparatuses are also capable of carrying out a corner control operation. In this corner control operation, the conventional navigation apparatus automatically shifts down into a low-speed transmission gear when the vehicle approaches a corner, so that the vehicle can turn the corner with low speed sufficient for passing the corner safely.
Hereinafter, problems involved in the conventional navigation apparatuses are described with reference to FIG.
4
. In
FIG. 4
, a freeway
50
has a main way
51
and an off-ramp (branch way)
52
which branches off at a fork. As shown in this figure, within the distance “D” indicated by the arrow, the off-ramp
52
is “gradually” away from the main way
51
according as the off-ramp
52
extends.
When the vehicle having such a conventional navigation apparatus has entered the off-ramp
52
to drive off the freeway
50
, it is impossible for the conventional navigation apparatus to know the exact location of the vehicle until the vehicle reaches a position where the off-ramp
52
is far enough away from the main way
51
. In other words, it is impossible for the conventional navigation apparatus to properly judge whether the road on which the vehicle is actually traveling is the main way
51
or the off-ramp
52
until the vehicle reaches a position where the off-ramp
52
is far enough away from the main way
51
. This is because the shape and position of the main way
51
within the distance D is very similar to those of the off-ramp
52
within the distance D, and therefore the conventional navigation apparatus cannot properly carry out the above-mentioned map matching process.
Therefore, when the vehicle having the conventional navigation apparatus enters the off-ramp
52
from the main way
51
, there is a possibility that the following problems occur.
First, since the conventional navigation apparatus cannot exactly determine the road on which the vehicle is traveling just after passing the fork, there is a possibility that the vehicle's location is displayed at a wrong position on a digital road map on the screen for a while after passing the fork.
Second, even when the vehicle has inadvertently entered the off-ramp
52
from the main way
51
, the conventional navigation apparatus cannot compute a new recommended route just after passing the fork. This is because the conventional navigation apparatus cannot properly know its current position until the vehicle is far enough away from the main way
51
. Therefore, in such a case, the conventional navigation apparatus cannot provide information as to a new recommended route just after passing the fork.
On the other hand, when the vehicle having the conventional navigation apparatus travels straight on the main way
51
without entering the branch way
52
, there is a possibility that the following problem occurs. Namely, when the vehicle travels straight on the main way
51
, there is a possibility the conventional navigation apparatus misjudges that the vehicle has entered the branch way
52
. This is because the shape and position of the main way
51
within the distance D is very similar to those of the branch way
52
within the distance D, and therefore the navigation apparatus cannot properly carry out the map matching process. Accordingly, in the case where the conventional navigation apparatus has made such a misjudgment, the navigation apparatus judges there is a corner
53
in front of the vehicle, although the vehicle is actually traveling on the main way
51
. In such a case, the navigation apparatus carries out the corner control operation to reduce the speed of the vehicle, thus leading to the possibility of a car clash.
SUMMARY OF THE INVENTION
In view of the above, it is an object of the present invention to provide a navigation apparatus which makes it possible to properly carry out the map matching process to determine the road on which a vehicle is traveling just after passing a fork or on which the vehicle is traveling just after passing the fork.
Further, it is another object of the present invention to provide a method for the map matching performed in the navigation apparatus.
Furthermore, it is other object of the present invention to provide a computer-readable medium storing a program for executing the method for the map matching performed in the navigation apparatus.
In order to achieve the above objects, the present invention is directed to a navigation apparatus which is mounted on a vehicle, the navigation apparatus being capable of displaying a vehicle's location on a digital road map on a screen to provide route guidance to a user of the vehicle, the apparatus comprising:
current position detecting means for detecting a current position of the vehicle;
a database which stores route/map data including at least information of forks in roads, in which the fork information of each of the forks is stored in association with at least two predetermined conditions relating to features of the fork;
imaging means for taking images of a road on which the vehicle is traveling;
means for detecting and monitoring lane markers on the road to obtain detection results, the detection and monitoring being performed by processing the images taken by the imaging means;
first judging means for judging whether or not a fork is located ahead of the current position of the vehicle, the judgment being made based on the route/map data;
retrieval means for retrieving the fork information of the fork from the route/map data, the retrieval being made in a case where the first judging means judges that a fork is located ahead of the current position of the vehicle;
second judging means for judging whether or not the vehicle has entered a specific area that is set with respect to the fork; and
road determining means for determining the road on which the vehicle is traveling after passing the fork or on which the vehicle is going to travel after passing the fork, the determination being made based on the detection results and the predetermined conditions relating to the fork.
According to the present invention described above, it is possible for the navigation apparatus to know the road on which the vehicle is traveling just after passing the specific fork (or, on which the vehicle is going to travel just after passing the specific fork), based on the road determination result. Further, when the vehicle's actual location is displayed at a wrong position on the digital road map, the navigation apparatus can correct the position so that the road on which the vehicle is actually traveling immediately after passing the fork just corresponds to the road image along which the vehicle's mark is moving on the digital road map. This is advantageous in the following points. Namely, the driver can know its accurate location from the displayed information on the screen immediately after passing the specific fork.
In this invention, it is preferable that the na
Camby Richard M.
Kabushikikaisha Equos Research
Lorusso & Loud
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