U.S. patent application number 12/072408 was filed with the patent office on 2009-08-27 for method and apparatus for adjusting distance for generating maneuver instruction for navigation system.
Invention is credited to Clayton Napohaku, Tien Vu.
Application Number | 20090216431 12/072408 |
Document ID | / |
Family ID | 40565255 |
Filed Date | 2009-08-27 |
United States Patent
Application |
20090216431 |
Kind Code |
A1 |
Vu; Tien ; et al. |
August 27, 2009 |
Method and apparatus for adjusting distance for generating maneuver
instruction for navigation system
Abstract
A distance adjustment method and apparatus for a navigation
system produces a maneuver instruction for an intersection at the
most appropriate timing and location during the route guidance. The
method includes the steps of: searching an upcoming intersection on
the calculated route that requires the user to make a turn therein;
retrieving data concerning the upcoming intersection from a map
database; adjusting a final distance from a reference point of the
intersection by evaluating the retrieved data concerning the
intersection; and generating a maneuver instruction at a timing
when the user has reached the adjusted final distance from the
reference point of the intersection, thereby notifying the user to
make a turning maneuver at the intersection.
Inventors: |
Vu; Tien; (Torrance, CA)
; Napohaku; Clayton; (Torrance, CA) |
Correspondence
Address: |
MURAMATSU & ASSOCIATES
Suite 310, 114 Pacifica
Irvine
CA
92618
US
|
Family ID: |
40565255 |
Appl. No.: |
12/072408 |
Filed: |
February 26, 2008 |
Current U.S.
Class: |
701/533 |
Current CPC
Class: |
G01C 21/3655
20130101 |
Class at
Publication: |
701/201 |
International
Class: |
G01C 21/36 20060101
G01C021/36 |
Claims
1. A distance adjustment method for a navigation system, comprising
the following steps of: conducting a route guidance operation of
the navigation system for guiding a user to a destination through a
calculated route; searching an upcoming intersection on the
calculated route that requires the user to make a turn therein
within a predetermined distance range ahead from a current
position; retrieving data concerning the upcoming intersection from
a map database; adjusting a final distance from a reference point
of the intersection by evaluating the retrieved data concerning the
intersection; and generating a maneuver instruction at a timing
when the user has reached the adjusted final distance from the
reference point of the intersection, thereby notifying the user to
make a turning maneuver at the intersection.
2. A distance adjustment method for a navigation system as defined
in claim 1, wherein the final distance from the reference point of
the intersection is adjusted depending on a direction of the
turning maneuver at the intersection.
3. A distance adjustment method for a navigation system as defined
in claim 1, wherein the final distance from the reference point of
the intersection is adjusted depending on a direction of the
turning maneuver at the intersection and a number of lanes involved
in the intersection with use of the retrieved data concerning the
intersection.
4. A distance adjustment method for a navigation system as defined
in claim 1, wherein the final distance from the reference point of
the intersection is adjusted depending on a direction of the
turning maneuver at the intersection and a number of lanes involved
in the intersection and a width of each lane with use of the
retrieved data concerning the intersection.
5. A distance adjustment method for a navigation system as defined
in claim 1, further comprising a step of retrieving a reference
distance from the reference point of the intersection, a step of
obtaining an adjusted distance based on a direction of the turning
maneuver at the intersection and other relevant information derived
from the retrieved data concerning the intersection, and a step of
combining the reference distance and the adjusted distance to
obtain the final distance.
6. A distance adjustment method for a navigation system as defined
in claim 5, wherein said step of obtaining the adjusted distance
includes a step of detecting a number of lanes involved in the
intersection and a width of each lane from the retrieved data, and
a step of multiplying the number of lanes and the width of the
lane.
7. A distance adjustment method for a navigation system as defined
in claim 1, further comprising a step of retrieving a reference
distance from the reference point of the intersection, and a step
of changing the reference distance based on a direction of the
turning maneuver at the intersection and other relevant information
derived from the retrieved data concerning the intersection thereby
determining the final distance from the reference point.
8. A distance adjustment method for a navigation system as defined
in claim 7, wherein said step of changing the reference distance
for determining the final distance includes a step of incorporating
a half width of a road segment where one road segment is involved
in the intersection, and a step of either adding or subtracting the
half width from the reference distance depending on the direction
of the turning maneuver.
9. A distance adjustment method for a navigation system as defined
in claim 7, wherein said step of changing the reference distance
for determining the final distance includes a step of incorporating
a half width of a road segment where one road segment is involved
in the intersection, a step of incorporating a half width of a
center divider of the intersection, and a step of either adding or
subtracting the half width of the road segment and the center
divider from the reference distance depending on the direction of
the turning maneuver.
10. A distance adjustment method for a navigation system as defined
in claim 5, wherein the reference distance is modified by
evaluating various factors including a vehicle speed, traffic
congestion, and weather condition.
11. A distance adjustment apparatus for a navigation system,
comprising: means for conducting a route guidance operation of the
navigation system for guiding a user to a destination through a
calculated route; means for searching an upcoming intersection on
the calculated route that requires the user to make a turn therein
within a predetermined distance range ahead from a current
position; means for retrieving data concerning the upcoming
intersection from a map database; means for adjusting a final
distance from a reference point of the intersection by evaluating
the retrieved data concerning the intersection; and means for
generating a maneuver instruction at a timing when the user has
reached the adjusted final distance from the reference point of the
intersection, thereby notifying the user to make a turning maneuver
at the intersection.
12. A distance adjustment apparatus for a navigation system as
defined in claim 11, wherein the final distance from the reference
point of the intersection is adjusted depending on a direction of
the turning maneuver at the intersection.
13. A distance adjustment apparatus for a navigation system as
defined in claim 11, wherein the final distance from the reference
point of the intersection is adjusted depending on a direction of
the turning maneuver at the intersection and a number of lanes
involved in the intersection with use of the retrieved data
concerning the intersection.
14. A distance adjustment apparatus for a navigation system as
defined in claim 11, wherein the final distance from the reference
point of the intersection is adjusted depending on a direction of
the turning maneuver at the intersection and a number of lanes
involved in the intersection and a width of each lane with use of
the retrieved data concerning the intersection.
15. A distance adjustment apparatus for a navigation system as
defined in claim 11, further comprising means for retrieving a
reference distance from the reference point of the intersection,
means for obtaining an adjusted distance based on a direction of
the turning maneuver at the intersection and other relevant
information derived from the retrieved data concerning the
intersection, and means for combining the reference distance and
the adjusted distance to obtain the final distance.
16. A distance adjustment apparatus for a navigation system as
defined in claim 15, wherein said means for obtaining the adjusted
distance includes means for detecting a number of lanes involved in
the intersection and a width of each lane from the retrieved data,
and means for multiplying the number of lanes and the width of the
lane.
17. A distance adjustment apparatus for a navigation system as
defined in claim 11, further comprising means for retrieving a
reference distance from the reference point of the intersection,
and means for changing the reference distance based on a direction
of the turning maneuver at the intersection and other relevant
information derived from the retrieved data concerning the
intersection thereby determining the final distance from the
reference point.
18. A distance adjustment apparatus for a navigation system as
defined in claim 17, wherein said means for changing the reference
distance for determining the final distance includes means for
incorporating a half width of a road segment where one road segment
is involved in the intersection, and means for either adding or
subtracting the half width from the reference distance depending on
the direction of the turning maneuver.
19. A distance adjustment apparatus for a navigation system as
defined in claim 17, wherein said means of changing the reference
distance for determining the final distance includes a step of
incorporating a half width of a road segment where one road segment
is involved in the intersection, means for incorporating a half
width of a center divider of the intersection, and means for either
adding or subtracting the half width of the road segment and the
center divider from the reference distance depending on the
direction of the turning maneuver.
20. A distance adjustment apparatus for a navigation system as
defined in claim 15, wherein the reference distance is modified by
evaluating various factors including a vehicle speed, traffic
congestion, and weather condition.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to a method and apparatus
for generating an instruction for turning at an intersection, and
more particularly, to a method and apparatus of distance adjustment
to improve accuracy in the timing of announcing or otherwise
notifying a turning maneuver to a user by a navigation system with
respect to a particular intersection by evaluating various factors
involved in the intersection.
BACKGROUND OF THE INVENTION
[0002] A navigation system performs travel guidance for enabling a
user to easily and quickly reach the selected destination. A
typical example is a vehicle navigation system where a vehicle is
equipped with a navigation function to guide a driver to a
destination through a calculated route. Such a navigation system
detects the position of the user's vehicle, and reads out map data
pertaining to an area at the current vehicle position from a data
storage medium, for example, a CD-ROM (compact disc read-only
memory), a DVD (digital versatile disc), a hard disc, or from a
remote data server.
[0003] FIGS. 1A-1H show a typical example of overall procedure and
screen display involved in the navigation system. FIG. 1A shows an
example of locator map screen of the navigation system when the
destination is not specified. A process for specifying a
destination typically starts through a main menu screen of FIG. 1B
which displays menu items including a "Destination" menu for
entering the destination. When selecting "Destination" in FIG. 1B,
the navigation system displays a screen of FIG. 1C for specifying
an input method for selecting the destination.
[0004] By selecting, for example, a "Point of Interest" method in
FIG. 1C, the navigation system displays selection methods of point
of interest (POI) either by "Place Name" or "Place Type" in FIG.
1D. If the "Place Type" is selected in FIG. 1D, the navigation
system lists categories of POIs as shown in FIG. 1E through which
the user selects a desired category of POIs from the lists.
[0005] FIG. 1F shows a screen when the user has selected a "Fast
Foods" category in the example of FIG. 1E. Then, the screen lists
names of the fast food restaurants typically sorted by distance
from the current position of the user. If the user selects a
particular fast food restaurant from the list, the navigation
system calculates a route to the destination as shown in FIG.
1G.
[0006] After determining the route, the navigation system starts
the route guidance operation. As shown in FIG. 1H, the navigation
system shows the intersection for instructing the next turn and a
direction of the turn. Typically, such an instruction to turn will
be made by a highlighted arrow or large characters on the screen as
well as by a voice announcement when the vehicle approaches to
within a predetermined distance to the intersection.
[0007] However, a distance to the maneuver point of the
intersection may not be appropriate with respect to a timing of
announcing the maneuver action depending on circumstances of the
intersection. For example, inaccuracy of such distance or timing is
caused by a digitization method used in the map data where a
maneuver point is defined as a crossing point of center lines. The
problem associated with such a conventional method is described
with reference to FIGS. 2A and 2B.
[0008] FIGS. 2A and 2B show a case where a vehicle 29 is to make a
right turn at an intersection 20 where a crossing point 21 is a
reference point for determining a distance to the maneuver point.
In the case of FIG. 2A, an intersection 20a has a large size
because each cross street has three lanes at each side. In the case
of FIG. 2B, an intersection 20b has a small size because each cross
street has only one lane at each side.
[0009] In the example of FIG. 2A, when the vehicle 29 approaches
the intersection, an actual point for making a right turn is a
corner point 23. However, since the timing of announcing the
maneuver is determined based on the distance from the reference
point 21, such announcement of "Make a Right Turn" may be made when
the vehicle is already at or very close to the corner point 23.
Such a maneuver instruction is too sudden and surprises the driver
and adversely affects the safe driving.
[0010] More specifically, as shown in FIG. 2A, the crossing
(reference) point 21 is established by two center lines of the
streets that form the intersection 20a. The distance represented by
"dr" in FIG. 2A is a reference distance between the crossing point
21 and the vehicle 29. In the conventional technology, the
reference distance "dr" is predetermined such as 40 feet so that
when a vehicle reached this distance range from a crossing point
21, the navigation system produces the maneuver instruction.
[0011] The conventional technology may work well if an intersection
is small as in the case of the intersection 20b shown in FIG. 2B.
However, if an intersection is large as in the case of FIG. 2A, the
fixed reference distance "dr" causes the problem as noted above. As
a result, the instruction to turn maneuver may come too late, which
fails to leave enough time for the driver to make the maneuver
securely. In the worst case, such an instruction for maneuver may
not be produced even when the vehicle is already within the
intersection, which may scare the driver and seriously impede the
safe driving.
[0012] Therefore, there is a need of a new method and apparatus for
navigation system to produce the maneuver instruction such as voice
announcement at a more appropriate timing. There is need of a new
method and apparatus for navigation system to produce the maneuver
instruction at an appropriate timing even when the size and
structure of the intersection, directions of turn, etc. vary.
SUMMARY OF THE INVENTION
[0013] It is, therefore, an object of the present invention to
provide a distance adjustment method and apparatus for a navigation
system which is capable of producing a maneuver instruction for an
intersection at the most appropriate timing and location.
[0014] It is another object of the present invention to provide a
distance adjustment method and apparatus for a navigation system
which adjusts a distance from the reference point of the
intersection to the point where the turn instruction will be made
by evaluating various factors including a direction of turn, a
structure and size of the intersection, etc.
[0015] It is a further object of the present invention to provide a
distance adjustment method and apparatus for a navigation system
which adjusts a distance from the reference point of the
intersection to the point where the turn instruction will be made
by evaluating various factors including a number of lanes, a width
of a lane, size of a center divider, etc.
[0016] One aspect of the present invention is a distance adjustment
method for a navigation system for announcing a maneuver
instruction at the most appropriate timing. The method includes the
steps of: conducting a route guidance operation of the navigation
system for guiding a user to a destination through a calculated
route; searching an upcoming intersection on the calculated route
that requires the user to make a turn therein within a
predetermined distance range ahead from a current position;
retrieving data concerning the upcoming intersection from a map
database; adjusting a final distance from a reference point of the
intersection by evaluating the retrieved data concerning the
intersection; and generating a maneuver instruction at a timing
when the user has reached the adjusted final distance from the
reference point of the intersection, thereby notifying the user to
make a turning maneuver at the intersection.
[0017] In the distance adjustment method of the present invention,
the final distance from the reference point of the intersection is
adjusted depending on a direction of the turning maneuver at the
intersection. Further, the final distance from the reference point
of the intersection is adjusted depending on a direction of the
turning maneuver at the intersection and a number of lanes involved
in the intersection with use of the retrieved data concerning the
intersection. Furthermore, in the distance adjustment method of the
present invention, the final distance from the reference point of
the intersection is adjusted depending on a direction of the
turning maneuver at the intersection and a number of lanes involved
in the intersection and a width of each lane with use of the
retrieved data concerning the intersection.
[0018] The distance adjustment method of the present invention
further includes a step of retrieving a reference distance from the
reference point of the intersection, a step of obtaining an
adjusted distance based on a direction of the turning maneuver at
the intersection and other relevant information derived from the
retrieved data concerning the intersection, and a step of combining
the reference distance and the adjusted distance to obtain the
final distance.
[0019] In the distance adjustment method, the step of obtaining the
adjusted distance includes a step of detecting a number of lanes
involved in the intersection and a width of each lane from the
retrieved data, and a step of multiplying the number of lanes and
the width of the lane.
[0020] The distance adjustment method of the present invention
further includes a step of retrieving a reference distance from the
reference point of the intersection, and a step of changing the
reference distance based on a direction of the turning maneuver at
the intersection and other relevant information derived from the
retrieved data concerning the intersection thereby determining the
final distance from the reference point.
[0021] In distance adjustment method of the present invention, the
step of changing the reference distance for determining the final
distance includes a step of incorporating a half width of a road
segment where one road segment is involved in the intersection, and
a step of either adding or subtracting the half width from the
reference distance depending on the direction of the turning
maneuver.
[0022] Further, the step of changing the reference distance for
determining the final distance includes a step of incorporating a
half width of a road segment where one road segment is involved in
the intersection, a step of incorporating a half width of a center
divider of the intersection, and a step of either adding or
subtracting the half width of the road segment and the center
divider from the reference distance depending on the direction of
the turning maneuver.
[0023] In the distance adjustment method of the present invention,
the reference distance is modified by evaluating various factors
including a vehicle speed, traffic congestion, and weather
condition.
[0024] Another aspect of the present invention is a distance
adjustment apparatus for a navigation system to generating a
maneuver instruction at the most appropriate timing by implementing
the various steps of the display method described above. The
distance adjustment apparatus of the present invention adjusts a
distance from the reference point of the intersection to the point
where the turn instruction will be made by evaluating various
factors including a direction of turn, a structure and size of the
intersection, a number of lanes, a width of a lane, size of a
center divider, etc.
[0025] According to the present invention, the navigation system is
able to produce the maneuver instruction for the intersection at
the most appropriate timing. During the route guidance operation,
the method and apparatus of the present invention adjusts a
distance from the reference point of the intersection to the point
where the turn instruction will be made by evaluating the
information. Such information includes a type of an intersection, a
size of the intersection such as a number of lanes, a shape or size
of a center divider if any, and a direction of turn such as right
turn or left turn, a speed of a vehicle, weather condition, etc. In
one embodiment, in addition to the reference distance "dr"
incorporated in the conventional technology, the present invention
utilizes the adjusted distance "da" so that the maneuver
instruction is produced when the vehicle reaches the final distance
"dr +da" from the reference point. In another embodiment, a
specific structure concerning a double-digitized road and its
associated data such as a center divider are incorporated to
determine the adjusted final distance. Thus, the driver is informed
to make a turn sufficiently prior to reach the turning point of the
intersection but is not too early until reaching the turning
point.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIGS. 1A-1H are schematic diagrams showing an example of
operational process and screen display involved in the navigation
system for selecting a destination, determining a calculated route
to the destination, and conducting a route guidance operation to
the destination.
[0027] FIGS. 2A and 2B are schematic diagrams showing situations
involving the problem arises in the conventional technology for
producing a maneuver instruction at an intersection where an
intersection has a large size with many lanes in FIG. 2A and an
intersection has a small size with one lane in FIG. 2B.
[0028] FIGS. 3A-3C are schematic diagrams showing an example of
basic concept of the present invention to solve the problems arise
in the intersection of FIG. 2 where FIG. 3A shows an adjusted
distance "da" for the case of right turn, where FIG. 3A shows a
problem arises in left turn when the same adjusted distance "da" is
used, and FIG. 3C shows the situation of left turn where the
distance "da" is adjusted based on the size of the
intersection.
[0029] FIG. 4 is a schematic diagram showing an example of
intersection to illustrate a method for determining an adjusted
distance "da" shown in FIGS. 3A and 3C for producing a maneuvering
instruction with a more appropriate timing under the present
invention.
[0030] FIG. 5 is a flow chart showing an example of operational
steps for adjusting a distance between a reference point and an
announcement point in the situation shown in FIGS. 3A and 3C under
the present invention.
[0031] FIGS. 6A and 6B a schematic view showing another example of
intersection to illustrate a method for adjusting a distance for
producing a maneuvering instruction with a more appropriate timing
under the present invention.
[0032] FIG. 7 is a flow chart showing an example of operational
steps for adjusting a distance between a reference point and an
announcement point in the situation shown in FIGS. 6A and 6B under
the present invention.
[0033] FIG. 8 is a block diagram showing an example of functional
structure of the apparatus under the present invention for
adjusting a distance thereby producing a maneuver instruction at an
appropriate timing.
[0034] FIG. 9 is a functional block diagram of a vehicle navigation
system implementing the method for adjusting a distance thereby
producing a maneuver instruction at an appropriate timing.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0035] The method and apparatus for adjusting a distance between a
reference point and an announcement point thereby producing a
maneuver instruction at an appropriate timing is explained in
detail with reference to the accompanied drawings. The present
invention is designed to produce a maneuver instruction, typically,
voice announcement of "Make a Right Turn", "Make a Left Turn", etc.
at an appropriate timing, i.e., not too late and not too early.
During the route guidance operation, the method and apparatus of
the present invention adjusts a distance from the reference point
of the intersection to the point where the turn instruction will be
made by evaluating the information on a type of an intersection, a
size of the intersection such as a number of lanes, a shape or size
of a center divider if any, and a direction of turn such as right
turn or left turn, a speed of a vehicle, weather condition,
etc.
[0036] Thus, the navigation system of the present invention is able
to provide the maneuver instruction at an appropriate timing for a
driver corresponding to particular conditions of the intersection.
Thus, the driver is informed to make a turn sufficiently prior to
reach the turning point of the intersection but is not too early
until reaching the turning point. The navigation system achieves
this effect by adjusting the timing or distance from the reference
point for announcing the maneuver instruction by evaluating the
various factors obtained from the existing and future map database
incorporated in the navigation system.
[0037] It should be noted that the present invention is described
herein mainly for the case where the display method and apparatus
is applied to a vehicle navigation system for an illustration
purpose. However, the method and apparatus under the present
invention can be implemented to other devices with the navigation
function, such as cellular phones, portable data terminals, laptop
computers, or personal computers.
[0038] FIGS. 3A-3C are schematic diagrams showing an example of
basic concept of the present invention to solve the problems arise
in the intersection of FIG. 2. FIG. 3A shows an adjusted distance
"da" for the case of right turn in addition to the traditional
reference distance "dr". FIG. 3B shows a problem arises in making a
left turn when the same adjusted distance "da" shown in FIG. 3B is
used. FIG. 3C shows the situation of making a left turn where the
distance "da" is adjusted based on the size of the intersection to
solve the problem of FIG. 3B.
[0039] In the example of FIGS. 3A-3C, in addition to the reference
distance "dr" incorporated in the conventional technology, the
present invention utilizes the adjusted distance "da". As noted
above, the reference distance "dr" is a predetermined distance such
as 40 feet which is so designed that when the vehicle has reached
this distance range from a reference (crossing) point, the
navigation system produces the maneuver instruction in the
conventional technology. While the reference distance "dr" is
basically the same as in the conventional technology, the adjusted
distance "da" varies depending on the size and structure of the
intersection, the direction of turn, etc.
[0040] In the example of FIGS. 3A-3C, the reference (crossing)
point 21 is used as a reference for determining a timing (distance)
for generating the maneuver instruction such as "Make a Right
Turn". Similar to the situation of FIG. 2, the diagram of FIG. 3A
shows the case where the driver of the vehicle 29 is going to make
a right turn at the intersection 20. Also similar to the situation
of FIG. 2, since the vehicle 29 is on the rightmost lane, the
vehicle has to make the right turn in the intersection 20
immediately after passing the corner point 23.
[0041] In the present invention, the adjusted distance "da" is
added to the reference distance "dr" so that the maneuver
instruction such as "Make a Right Turn" is generated at a location
A which is a final distance (sum of distances da+dr) away from the
reference point 21. The location A will be, for example, about 30
feet away from the corner point 23 which is a point for the right
turn. As a consequent, the navigation system allows the user to be
well prepared for the maneuver and to make a right turn safely and
comfortably at the corner point 23.
[0042] FIG. 3B shows the case where the driver of the vehicle 29 is
going to make a left turn at the intersection 20, and the vehicle
29 is now on the leftmost lane. In this situation, the vehicle has
to make the left turn immediately after passing the reference point
21. In this example, it is assumed that the same adjusted distance
"da" as that of FIG. 3A is added to the reference distance "dr" so
that the maneuver instruction such as "Make a Left Turn" is
generated at a location B (sum of distances da+dr). Since the
reference point 21 is far away from the current vehicle position
29, the maneuver instruction is too early for the user, i.e., not a
good timing in this situation.
[0043] FIG. 3C shows the way for solving the problem involved in
the example of FIG. 3B where the driver of the vehicle 29 is going
to make a left turn at the intersection 20, and the vehicle 29 is
now on the leftmost lane. In this example, the adjusted distance
"da" is changed from that of FIG. 3A in taking the size and
structure of the intersection 20, the direction of turn, and the
vehicle speed, etc., into consideration. As shown, because there is
a relatively long distance between the start point of the
intersection (ex. corner point 23) and the center line 22A, the
adjusted distance "da" is greatly reduced from that of FIG. 3A.
Accordingly, the navigation system generates the maneuver
instruction such as "Make a Left Turn" at a location C which is a
final distance (sum of distances da+dr), and which is an
appropriate timing, i.e, not too late and not too early.
[0044] FIG. 4 is a schematic diagram showing an example of
intersection to illustrate a method for determining an adjusted
distance "da" shown in FIGS. 3A and 3C for producing a maneuvering
instruction with a more appropriate timing under the present
invention. Based on the information related to a particular
intersection, the method of the present invention adjusts a
distance (timing) for producing a maneuver instruction with a more
appropriate timing. In the example of FIG. 4, each cross street
involving the intersection has three lanes 31 for each side of
opposite direction.
[0045] The information on the number of lanes can be obtained from
the map database which is stored in a storage medium such as DVD,
HD (hard disc), etc. of the navigation system. The information on
the number of lanes may not be sufficiently provided in the today's
map database but will be fully provided in the map database of near
future. A width of each lane is given in the map database, or known
by a person of ordinary skill in the art, or can be estimated
relatively accurately according to the information such as
functional classes of the road segments.
[0046] In this example, a size of a cross street is determined by a
number of lanes and a width of each lane, for example, 10 feet.
Thus, in the case where the number of lanes is 3, and the width of
each lane is 10 feet, the total distance (width) of the cross
street at one side is calculated by 3 multiplied by 10 feet, which
results in 30 feet. Thus, in determining the overall distance to a
maneuvering point, the reference distance "dr" is offset by the
adjusted distance "da" which is 30 feet in this case.
[0047] The lane width may not be limited to a particular value but
may vary between street to street. For example, the lane width may
be different according to the type of the street or functional
class, such as a residential street, a main street or a street in
an industrial area, etc. Thus, for adjustment of the distance in
the present invention, for a larger street, a wider width is
assigned while a narrower width is assigned to a smaller
street.
[0048] Thus, in the example of FIG. 4, the adjusted distance "da"
is the sum of width of three lanes 31, which starts from the
reference point 21. As noted above, the reference point 21 is the
crossing point of the center lines 22A and 22B of the two cross
streets. As shown in the examples of FIGS. 3A and 3C, the adjusted
distance "da" will be changed depending on whether the vehicle is
going to make a right turn or left turn, vehicle speed, etc.
[0049] FIG. 5 is a flow chart showing an example of operational
steps for adjusting a distance between a reference point and an
announcement point in the situation shown in FIGS. 3A and 3C under
the present invention. As noted above, the process of the present
invention for adjusting the timing of announcing the maneuver
instruction is conducted during the route guidance operation. Thus,
the operation shown by FIG. 5 will be carried out when the
navigation system or a device with a navigation function is in the
route guidance mode in guiding the user to the selected destination
through he calculated route.
[0050] As noted above, the process of FIG. 5 is directed to the
method of the present invention for adjusting the timing (distance)
for producing the maneuver instruction such as by voice
announcement and/or mark, etc. at an intersection. In the first
step 101, the navigation system determines whether there is an
intersection that requires the user to make a turn on the
calculated route to reach the destination. Such determination is
made for a predetermined distance range of the calculated route to
the destination ahead of the current vehicle position.
[0051] The step 101 will be repeated until an intersection will be
found, and if it is determined that there is an intersection, the
navigation system detects a reference point of the intersection in
the step 102. Typically, the reference point is a center point of
the intersection such as the point 21 in FIGS. 3A-3C which is
defined as a crossing point of the center lines 22A and 22B of the
cross streets involving the intersection 20. Such a reference point
is typically a connection point of two road segments (links)
defined in the map data, and an absolute location of the reference
point can be obtained as a form of longitude and latitude data from
the map database.
[0052] As noted above, in the example of FIGS. 3A-3C, the reference
point is used for establishing an appropriate distance from a
vehicle position to announce the maneuver instruction for the
intersection. In the step 103, the navigation system will check the
map database to see whether information concerning a lane number is
available. If it is available, the navigation system will retrieve
the lane number information and temporarily stores the information
in a memory to be used for adjustment calculation and will proceed
to the next step.
[0053] As noted above, information concerning a lane number may not
be complete in the currently marketed map database but will be
fully available in the near future. If the lane number information
is not available from the map database, the procedure will simply
proceed to the next step. During this process, if lane number
information is unavailable, the navigation system may assume the
lane number based on the type and road class of the cross
street.
[0054] In the next step 104, the navigation system will check
whether other relevant information is available from the map
database. The information relevant to the distance adjustment of
the present invention may include a structure of cross street
(whether there is a center divider, a width of each lane, etc.), a
functional (road) class of street (major street, residential
street, etc.), a current speed of the vehicle, a direction of turn
at the intersection, etc. After obtaining all the relevant
information in the steps 103 and 104, the navigation system
performs a calculation operation in the step 105.
[0055] In the calculation operation in the step 105, the navigation
system incorporates the lane number and the lane width to determine
an overall distance from the reference point to the entrance point
of the intersection. As will be described later, if the
intersection (cross street) includes a center divider, the size and
shape of such a center divider will be incorporated in the
calculation. Through the calculation operation, the navigation
system determines the adjusted distance "da" described above with
reference to FIGS. 3A-3C which may be varied depending on the
direction of turn (right or left).
[0056] Based on the calculation operation in the step 105, the
navigation system determines the timing of announcing the maneuver
instruction in the step 106. In the example of FIGS. 3A-3C, the
timing (final distance) is determined by adding the adjusted
distance "da" to the reference distance "dr". Finally, in the step
107, the navigation system produces the maneuver instruction by
voice announcement and/or displaying a mark, icon, etc. at the
timing determined above.
[0057] FIGS. 6A and 6B are schematic diagrams showing a situation
of intersection wherein the cross street includes a relatively
large center divider (road separator bunk) that separates opposing
traffic. In the map database industry, such a street is sometimes
called a double-digitized road which is a divided road with at
least one lane traveling in each of two opposite directions. In the
map data, the opposite directions of travel for such a
double-digitized road are represented as different road
segments.
[0058] In the example of FIGS. 6A and 6B, dotted lines represent
the road segments associated with the intersection links where a
cross street extending in a horizontal direction is a
double-digitized road. Road segments 70A and 70B comprise
double-digitized road, where the road segment 70A represents a road
for the left (west) direction and the road segment 70B represents a
road for the right (east) direction. Center dividers (Road
separator bunks) 71 are provided at the center of the
double-digitized road to separate the roads of opposite
directions.
[0059] Thus, in the intersection 20c of FIGS. 6A and 6B, the basic
difference from the intersection of FIGS. 3A-3C is that (1) the
cross street has one lane on each side and (2) the cross street has
the center divider 71. Similar to the example of FIGS. 3A-3C, a
reference point 21 is shown in FIGS. 6A and 6B which is a center
point of the intersection 20c. A reference distance "dr" is
predefined with respect to the reference point 21 which is
basically the same as that used in FIGS. 2A-2B and 3A-3C to produce
the maneuver instruction when the vehicle has arrived at this
distance.
[0060] A road width L1 represents the width of the road segment
70A, a road width L2 represents the width of the road segment 70B,
and L3 represents a width of the center divider 71. The existing
map database includes, at least in a certain level, the information
regarding the road width L1 and L2 of the road segments and the
width L3 of the center divider so that the navigation system is
able to retrieve them. A map database in the near future will
incorporate such information in a more complete fashion.
[0061] FIG. 6A shows the case where the vehicle is going to make a
left turn and FIG. 6B shows the case where the vehicle is going to
make a right turn. The method of the present invention in the
embodiment of FIGS. 6A and 6B determines the distance or timing for
announcing the maneuver instruction in a manner more precise than
that of FIGS. 3A-3C. This is done by (1) taking a center position
of each lane into consideration, and also (2) taking a width of the
center divider into consideration.
[0062] In FIG. 6A, a final distance "D1" for adjusting a timing of
producing a maneuver instruction for a left turn is established
with respect to the reference point 21 by changing the reference
distance "dr". As indicated by the thick arrow, it is assumed that
the vehicle is going to make a left turn toward the center position
of the road segment 70A. Thus, since the reference point 21 is a
center of the intersection, a half of the road width L1 of the road
segment 70A and a half of the width L3 of the center divider 71 are
incorporated in adjusting the distance.
[0063] Namely, with use of the reference point 21 and the reference
distance "dr", the final distance D1 is calculated as follows:
D1=dr-(L1/2+L3/2)
where L1 is a road width of the road segment 70A and L3 is a width
of the center divider 71. It is apparent that if there are two road
segments 70A on one side, L1/2 will be modified to L1(1+1/2) and so
on. Accordingly, the navigation system generates the maneuver
instruction such as "Make a Left Turn" at the distance D1 away from
the reference point 21, which is an appropriate timing, i.e, not
too late and not too early.
[0064] In FIG. 6B, a final distance "D2" for adjusting a timing of
producing a maneuver instruction for a right turn is established
with respect to the reference point 21 by changing the reference
distance "dr". As indicated by the thick arrow, it is assumed that
the vehicle is going to make a right turn toward the center
position of the road segment 70B. Thus, since the reference point
21 is a center of the intersection, a half of the road width L2 of
the road segment 70B and a half of the width L3 of the center
divider 71 are incorporated in adjusting the distance.
[0065] Namely, with use of the reference point 21 and the reference
distance "dr", the final distance D2 is calculated as follows:
D2=dr+(L2/2+L3/2)
where L2 is a lane width of the road segment 70B and L3 is the
width of the center divider 71. It is apparent that if there are
two road segments 70B on one side, L2/2 will be modified to
L2(1+1/2) and so on. Accordingly, the navigation system generates
the maneuver instruction such as "Make a Right Turn" at the
distance D2 away from the reference point 21, which is an
appropriate timing, i.e, not too late and not too early.
[0066] In the present invention, it is preferable to also modify
the reference distance "dr" dynamically by taking the speed of the
vehicle, type of the street being driven on, traffic congestion,
weather condition, etc., into consideration. For instance, the
reference distance "dr" may be modified such that the higher the
speed of the vehicle, the longer the reference distance becomes.
Further, the reference distance "dr" may be modified such that if
the weather condition is not good (ex. raining), the reference
distance becomes longer.
[0067] FIG. 7 is a flow chart summarizing the operational steps
described with reference to FIGS. 6A and 6B for distance (timing)
adjustment for issuing a maneuver announcement. As noted above,
FIGS. 6A and 6B are directed to the situation of intersection
wherein at least one cross street is a double-digitized road which
includes a relatively large center divider. In the step 110, the
navigation system checks whether there is an intersection that
requires the user to make a turn on the calculated route to reach
the destination.
[0068] Such determination is made for a predetermined distance
range of the calculated route to the destination ahead of the
current vehicle position. The step 110 will be repeated until an
intersection that needs to make a turning maneuver will be found on
the calculated route. If it is determined that there is an
intersection, the navigation system detects a reference point of
the intersection and the predetermined reference distance "dr" in
the step 111.
[0069] Typically, the reference point is a center point of the
intersection as shown in FIGS. 6A and 6B, an absolute location of
which can be obtained as a form of longitude and latitude data from
the map database. The reference distance "dr" is predetermined as
described with respect to the conventional technology and it will
be adjusted by the present invention based on various factors,
vehicle speed, weather condition, etc. In the step 112, the
navigation system determines the direction of the turn at the
upcoming intersection. If it is a left turn, the process goes to
the steps 113-116 and if it is a right turn, the process goes to
the steps 117-120.
[0070] In the case of left turn, the navigation system detects a
width L1 of the road segment 70A in the step 113. The navigation
system also detects a width L3 of the center divider 71 in the step
114. In the step 115, the navigation system applies the formula
"D1=dr-(L1/2+L3/2)" to obtain the distance D1 with use of the
reference point 21 and the reference distance "dr", where L1 is the
road width of the road segment 70A and L3 is a width of the center
divider 71. Based on the calculation, in the step 116, the
navigation system produces the maneuver instruction by voice
announcement and/or displaying a mark, icon, etc., for the left
turn, when the vehicle reaches the distance Dl from the reference
point 21.
[0071] In the case of right turn, the navigation system detects a
width L2 of the road segment 70B in the step 117. The navigation
system also detects a width L3 of the center divider 71 in the step
118. In the step 119, the navigation system applies the formula
"D1=dr+(L1/2+L3/2)" to obtain the distance D2 with use of the
reference point 21 and the reference distance "dr", where L2 is the
road width of the road segment 70B and L3 is a width of the center
divider 71. Based on the calculation, in the step 120, the
navigation system produces the maneuver instruction by voice
announcement and/or displaying a mark, icon, etc., for the right
turn, when the vehicle reaches the distance D2 from the reference
point 21.
[0072] FIG. 8 is a functional block diagram showing an example of
basic structure of the apparatus of the present invention for
adjusting the timing (distance) of announcing the maneuver
instruction for an upcoming intersection. The structure of FIG. 8
is applicable to any electronic device having a navigation function
which enables the electronic device to guide the user to a
particular location as noted above. The apparatus of the present
invention for the distance and timing adjustment includes a monitor
150 for graphical user interface, and a controller (CPU) 139 for
controlling an overall operation of the apparatus of the present
invention.
[0073] The block diagram of FIG. 8 further includes a map data
storage 131 such as a DVD or a hard disc for storing map data, a
map memory 134 for storing a required portion of the map data
retrieved from the map data storage 131, an input device 137 such
as a joystick, a remote controller or other input device for the
user to select menus, change directions, scroll the screen, change
the location of the cursor on the screen, etc., a position
measuring device 133 for detecting a current position of the user,
and a buffer memory 148 for storing data concerning the upcoming
intersection such as a location of the reference point, number of
lanes, width of lane, structure of intersection, functional class
of cross street, etc.
[0074] In FIG. 8, the apparatus for timing adjustment under the
present invention is able to retrieve the map data from the map
data storage 131 and the map memory 134. Based on the retrieved map
data, the display apparatus displays the map image on the monitor
150 which includes the calculated route to the destination, a
current vehicle position, etc. The CPU 139 controls an overall
operation of the timing and distance adjustment operation for the
turning maneuver under the present invention.
[0075] When the navigation system is in the route guidance mode to
guide the user to the destination through the calculated route, the
CPU 139 determines whether there is an intersection that requires
the user to make a turn on the calculated route to reach the
destination. If there is an intersection to make a turn, the CPU
139 detects the reference point of the intersection and the
reference distance "dr". The CPU 139 also detects the information
concerning the intersection such as a direction of turn, a number
lanes involved, a width of the lane, a number of lanes, a
particular structure of the intersection, a functional class of
cross street, etc. After obtaining all the relevant information,
the CPU 139 performs a calculation operation and determines the
adjusted distance described above with reference to FIGS. 3A-3C and
6A-6B. The CPU 139 instructs to produce the maneuver instruction by
voice announcement and/or displaying a mark, icon, etc. when the
vehicle reaches the adjusted distance.
[0076] FIG. 9 shows an example of structure of a vehicle navigation
system for implementing distance adjustment method of the present
invention. While the vehicle navigation system is explained for an
illustration purpose, the present invention can also be applied to
other types of navigation system, such as a portable navigation
device implemented by a PDA (personal digital assistant) device,
other hand-held devices such as a wireless telephone, a wrist
watch, a laptop or notebook computer.
[0077] In the block diagram of FIG. 9, the functional blocks
similar to those of FIG. 8 are denoted by the same reference
numerals. The navigation system includes a data storage medium 131
such as a hard disc, CD-ROM, DVD or other storage means for storing
the map data. The navigation system includes a control unit 132 for
controlling an operation for reading the information from the data
storage medium 131, and a position measuring device 133 for
measuring the present vehicle position or user position. For
example, the position measuring device 133 has a vehicle speed
sensor for detecting a moving distance, a gyroscope for detecting a
moving direction, a microprocessor for calculating a position, a
GPS (global positioning system) receiver for receiving and
analyzing GPS signals, and etc.
[0078] The block diagram of FIG. 9 further includes a map
information memory 134 for storing a portion of the map data
relevant to the intended operation of the navigation system which
is read from the data storage medium 131, a database memory 135 for
storing database information such as point of interest (POI)
information which is read out from the data storage medium 131, a
remote controller 137 for executing a menu selection operation,
cursor movements, an enlarge/reduce operation, a destination input
operation, etc. and a remote controller interface 138. Although a
remote controller is a typical example for selecting menus,
executing selected functions and etc., the navigation system
includes various other input methods to achieve the same and
similar operations done through the remote controller.
[0079] In FIG. 9, the navigation system further includes a bus 136
for interfacing the above functional blocks in the system, a
processor (CPU) 139 for controlling an overall operation of the
navigation system, a ROM 140 for storing various control programs
such as a route search program and a map matching program necessary
for navigation control as well as a local brand icon display
program for the present invention, a RAM 141 for storing a
processing result such as a guide route, a display controller 143
for generating map image (a map guide image and an arrow guide
image) on the basis of the map information, a VRAM 144 for storing
images generated by the display controller 143, a menu/list
generating unit 145 for generating menu image/various list images,
a synthesizing unit 146, a wireless transceiver 149 for wireless
communication to retrieve data from a remote server, a buffer
memory 148 for temporally storing data concerning the upcoming
intersection such as a location of the reference point, width of
lane, structure of intersection, etc.
[0080] The CPU 139 controls an overall operation of the navigation
system including the distance adjustment operation under the
present invention as described above for producing a maneuver
instruction at an appropriate timing. The data related to the
distance adjustment will be stored in the buffer memory 148 for
further processing. A program that performs the procedure of the
present invention including the one shown in the flow charts of
FIGS. 5 and 7 may be stored in the ROM 140 or other storage medium
and is executed by the CPU 139. Thus, the navigation system is able
to produce the maneuver instruction for the intersection at the
most appropriate timing.
[0081] As has been described above, according to the present
invention, the navigation system is able to produce the maneuver
instruction for the intersection at the most appropriate timing.
During the route guidance operation, the method and apparatus of
the present invention adjusts a distance from the reference point
of the intersection to the point where the turn instruction will be
made by evaluating the information. Such information includes a
type of an intersection, a size of the intersection such as a
number of lanes, a shape or size of a center divider if any, and a
direction of turn such as right turn or left turn, a speed of a
vehicle, weather condition, etc. In one embodiment, in addition to
the reference distance "dr" incorporated in the conventional
technology, the present invention utilizes the adjusted distance
"da" so that the maneuver instruction is produced when the vehicle
reaches the distance "dr+da" from the reference point. In another
embodiment, a specific structure concerning a double-digitized road
and its associated data such as a center divider are incorporated
to determine the adjusted distance. Thus, the driver is informed to
make a turn sufficiently prior to reach the turning point of the
intersection but is not too early until reaching the turning
point.
[0082] Although the invention is described herein with reference to
the preferred embodiment, one skilled in the art will readily
appreciate that various modifications and variations may be made
without departing from the spirit and scope of the present
invention. Such modifications and variations are considered to be
within the purview and scope of the appended claims and their
equivalents.
* * * * *