U.S. patent application number 09/725208 was filed with the patent office on 2001-05-31 for on-vehicle information processor with map data and map data management.
Invention is credited to Ikeuchi, Tomoya, Maegawa, Satoshi, Mikuriya, Makoto, Nakao, Yoshihisa, Shimotani, Mitsuo, Takenaka, Shoichiro, Umezu, Masaharu.
Application Number | 20010002456 09/725208 |
Document ID | / |
Family ID | 18342596 |
Filed Date | 2001-05-31 |
United States Patent
Application |
20010002456 |
Kind Code |
A1 |
Ikeuchi, Tomoya ; et
al. |
May 31, 2001 |
On-vehicle information processor with map data and map data
management
Abstract
An on-vehicle information processor is configured such that,
when there is a request for access from application units to the
same map data stored in a data management unit, a request analyzing
unit maintains the map data unlocked so that the applications can
access the map data.
Inventors: |
Ikeuchi, Tomoya; (Tokyo,
JP) ; Umezu, Masaharu; (Tokyo, JP) ; Takenaka,
Shoichiro; (Hyogo, JP) ; Nakao, Yoshihisa;
(Hyogo, JP) ; Maegawa, Satoshi; (Hyogo, JP)
; Mikuriya, Makoto; (Tokyo, JP) ; Shimotani,
Mitsuo; (Tokyo, JP) |
Correspondence
Address: |
LEYDIG VOIT & MAYER, LTD
700 THIRTEENTH ST. NW
SUITE 300
WASHINGTON
DC
20005-3960
US
|
Family ID: |
18342596 |
Appl. No.: |
09/725208 |
Filed: |
November 29, 2000 |
Current U.S.
Class: |
701/461 ;
340/995.1; 711/100 |
Current CPC
Class: |
G01C 21/32 20130101 |
Class at
Publication: |
701/208 ;
340/995; 711/100 |
International
Class: |
G01C 021/32 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 1999 |
JP |
11-341031 |
Claims
What is claimed is:
1. An on-vehicle information processor for providing map
information based on map data, comprising: application processing
means for providing predetermined map information based on map data
and map management data; a data reading unit for reading the map
data and the map management data from a recording medium; a data
management unit for managing the map data and the map management
data independently; and a request analyzing unit for responding to
a request from said application processing means to permit access
from said application processing means to the map data and the map
management data managed by said data management unit.
2. The on-vehicle information processor according to claim 1,
wherein said data management unit acquires the map management data
provided initially to said application means, so as to manage the
acquired map management data; said request analyzing unit reads out
the map management data from the recording medium via said data
reading unit so as to supply the map management data thus read out
to said application means, when the map management data is
initially required by said application means; and said request
analyzing unit supplies the map management data managed by said
data management unit to said application means when the map
management data is subsequently required by said application
means.
3. The on-vehicle information processor according to claim 1,
wherein said data management unit is provided with a map data cache
and a control unit for controlling the map data cache.
4. The on-vehicle information processor according to claim 3,
wherein the control unit in said data management unit controls the
total size of map data stored in said map data cache to be smaller
than a predetermined upper limit.
5. The on-vehicle information processor according to claim 3,
wherein said request analyzing unit grants access from a plurality
of application means to the same map data stored in the map data
cache.
6. The on-vehicle information processor according to claim 3,
wherein the map data cache stores count information indicating a
number of application means accessing a storage area storing the
map data, and the control unit determines the map data stored in
the map data cache that should be discarded, based on the count
information stored in the map data cache.
7. The on-vehicle information processor according to claim 6,
wherein the map data cache stores information relating to
chronological sequence of storage of the map data or information
indicating time of access to the map data, and the control unit
determines the map data stored in the map data cache that should be
discarded, based on the information stored in the map data cache.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to on-vehicle
information processors for providing map information based on map
data and, more particularly, to an on-vehicle information processor
in which a large volume of map data and associated map management
data is managed efficiently.
[0003] 2. Description of the Related Art
[0004] FIG. 10 is a block diagram showing a construction of an
on-vehicle information processor disclosed in Japanese Laid-Open
Patent Application No. 10-253367. Referring to FIG. 10, the
on-vehicle information processor comprises applications 101-103 for
providing services to a user by processing map data and the like;
an operating system 104 for providing basic functions related to a
recording medium 105 for storing map data and the like and a memory
106 for temporarily storing map data when the application is
executed; a cache 111 for caching the map data and the like; and a
device driver 121 for directly controlling the recording medium
105. The applications 101-103 and the operating system 104 are
stored in, for example, a read-only memory (ROM) and executed by a
microprocessor after being developed in a random access memory
(RAM) or the like.
[0005] A description will now be given of the operation according
to the related art.
[0006] FIG. 11 shows an example of how a cache is used in the
related-art on-vehicle information processor.
[0007] When any of the applications 101-103 reads out the map data
from the recording medium 105 via the operating system 104, the map
data is stored in the cache 111 and retained therein according to a
predetermined caching system. When the cache 111 becomes full, the
data is discarded appropriately. When any of the applications
101-103 accesses the data stored in the cache 111, accessed data,
for example, data items 111-1 - 111-3, are locked so that the other
applications are prevented from accessing the data 111-1 - 111-3.
In this way, the integrity of the cache 111 is maintained.
[0008] The applications 101-103 provides services to the user based
on the map data thus read out. For example, the application
displays a road map on a display.
[0009] As described, in the related-art on-vehicle information
processor, the data is locked so that applications other than the
initially accessing application are prevented from accessing that
data. Therefore, accessing from a plurality of applications to the
same data in the cache is not permitted. Accordingly, improvement
in the processing speed cannot be hoped for.
SUMMARY OF THE INVENTION
[0010] Accordingly, a general object of the present invention is to
provide an on-vehicle information processor in which the
aforementioned drawback is eliminated.
[0011] Another and more specific object is to provide an on-vehicle
information processor in which the processing speed is improved by
allowing a plurality of applications to access the same map data
temporarily stored in a map data cache.
[0012] Still another object of the present invention is to provide
an on-vehicle information processor in which map data and map
management data read out by a data reading unit are managed
independently such that the map data and the map management data
are read out from a data managing unit when required, so that the
efficiency in processing an application is improved.
[0013] The aforementioned objects can be achieved by an on-vehicle
information processor for providing map information based on map
data, comprising: application processing means for providing
predetermined map information based on map data and map management
data; a data reading unit for reading the map data and the map
management data from a recording medium; a data management unit for
managing the map data and the map management data independently;
and a request analyzing unit for responding to a request from the
application processing means to permit access from the application
processing means to the map data and the map management data
managed by the data management unit.
[0014] The data management unit may acquire the map management data
provided initially to the application means, so as to manage the
acquired map management data; the request analyzing unit reads out
the map management data from the recording medium via the data
reading unit so as to supply the map management data thus read out
to the application means, when the map management data is initially
required by the application means; and the request analyzing unit
may supply the map management data managed by the data management
unit to the application means when the map management data is
subsequently required by the application means.
[0015] The data management unit may be provided with a map data
cache and a control unit for controlling the map data cache.
[0016] The control unit in the data management unit may control the
total size of map data stored in the map data cache to be smaller
than a predetermined upper limit.
[0017] The request analyzing unit may grant access from a plurality
of application means to the same map data stored in the map data
cache.
[0018] The map data cache may store count information indicating a
number of application means accessing a storage area storing the
map data, and the control unit may determine the map data stored in
the map data cache that should be discarded, based on the count
information stored in the map data cache.
[0019] The map data cache may store information relating to
chronological sequence of storage of the map data or information
indicating time of access to the map data, and the control unit may
determine the map data stored in the map data cache that should be
discarded, based on the information stored in the map data
cache.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Other objects and further features of the present invention
will be apparent from the following detailed description when read
in conjunction with the accompanying drawings, in which:
[0021] FIG. 1 is a block diagram showing a hardware construction of
an on-vehicle information processor according to a first embodiment
of the present invention;
[0022] FIG. 2 is a block diagram showing a hierarchical
construction of the on-vehicle information processor according to
the first embodiment;
[0023] FIG. 3 is a block diagram showing a construction of a map
manager;
[0024] FIG. 4 shows an operation performed when map data is stored
in a map data cache;
[0025] FIG. 5 is an example of how a map data cache is used;
[0026] FIG. 6 is a block diagram showing a construction of a data
management unit in an on-vehicle information processor according to
a second embodiment of the present invention;
[0027] FIG. 7 is a flowchart illustrating an operation of a data
management unit in the on-vehicle information processor according
to the second embodiment;
[0028] FIG. 8 is a block diagram showing a construction of a data
management unit in an on-vehicle information processor according to
a third embodiment of the present invention;
[0029] FIG. 9 is a block diagram showing a construction of a data
management unit in an on-vehicle information processor according to
a fourth embodiment of the present invention;
[0030] FIG. 10 is a block diagram showing a construction of an
on-vehicle information processor according to the related art;
and
[0031] FIG. 11 is an example of how a cache is used in the
on-vehicle information processor according to the related art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] First Embodiment
[0033] FIG. 1 is a block diagram showing a construction of an
on-vehicle information processor according to a first embodiment of
the present invention. FIG. 2 is a block diagram showing a
hierarchical construction of the on-vehicle information processor
according to the first embodiment. FIG. 3 is a block diagram
showing a map manger of FIG. 2.
[0034] Referring to FIG. 1, the on-vehicle information processor
comprises: a read-only memory (ROM) 1 for storing programs such as
applications that implement a navigation system, an operating
system, device drivers and a map manager described later; a
microprocessor 2 for controlling hardware 5 by executing related
processes in accordance with a program such as the operating
system; a random access memory (RAM) 3 for temporarily storing
programs being accessed and data associated therewith; a recording
medium 4 for storing map data 31 including information relating to
road links and nodes for respective areas of a predetermined size,
map management data 32 including information related to the map
data, such as the number of levels of scales and scale sizes at
respective levels, the recording medium 4 being comprised of, for
example, a digital versatile disk-ROM (DVD-ROM) and a device for
driving the same; hardware 5 that implements a navigation system,
including, for example, a vehicle speed sensor, a global
positioning system (GPS), a display and a remote controller. In
addition to the information related to the roads, the map data may
include additional information related to buildings, stores and the
like.
[0035] Referring to FIG. 2, the on-vehicle information processor
further comprises: an application unit (application processing
means) provided with a plurality of applications 12-14 that provide
predetermined services related to map information based on the map
data 31 and the map management data 32; a map manager 21 provided
with the request analyzing unit 22, a data reading unit 23 and a
data management unit 24. The map manager 21 is implemented as a
part of the operating system or as the device driver. Information
(not shown) is transferred between the applications 12-14 and the
hardware 5 via the operating system and the device driver so that
various services are provided to the user.
[0036] The request analyzing unit 22 of the map manager 21 permits
access from the applications 12-14 to the map data 31 and the map
management data 32 managed by the map management unit 24 in
response to a request from the application means 12-14. The data
reading unit 23 reads the map data 31 and the map management data
32 from the recording medium 4. The data management unit 24
independently manages the map data 31 and the map management data
32 read out by the data reading unit 23.
[0037] Referring to FIG. 3, the data management unit 24 comprises:
a map data cache 42 having a total of n data storage areas 42-1 -
42-n; a control unit 41 for controlling the map data cache 42; and
a map management data cache 43 for storing map management data.
Each of the data storage areas 42-1 - 42-n, generically denoted as
42-i, stores map data for one geographical area. A predetermined
area in the random access memory 3, accessible at a higher speed
than the recording medium 4, is used as a cache.
[0038] A description will now be given of the operation according
to the first embodiment.
[0039] FIG. 4 shows an operation performed when the map data 31 is
stored in the map data cache 42. FIG. 5 is an example of how the
map data cache 42 is used according to the first embodiment.
[0040] The process involving the map management data will be
described.
[0041] When any of the applications 12-14 is executed such that the
map management data 32 is required, the application sends a request
for access to the map management data 32 to the map manager 21.
Since the map management data 32 is not managed by the data
management unit 24, the request analyzing unit 22 controls the data
reading unit 23 to read the map management data 32 from the
recording medium 4 and supplies the data thus read out to the data
management unit 24.
[0042] The map management data 32 supplied to the map management
unit 24 is stored by the control unit 41 in the map management data
cache 43. The request analyzing unit 22 reads out the map
management data 32 from the data management unit 24 and supplies
the data thus read out to the requesting application. The map
management data 32 may also be read out by the data reading unit 23
and stored in the data management unit 24 when the information
processor is started.
[0043] When any of the application means 12-14 sends a request for
access to the map management data 32 to the map manager 21
subsequently, the request analyzing unit 22 of the map manager 21
reads out the map management data from the map management data
cache 43 via the control unit 41 of the data management unit 24 and
supply the data thus read out to the requesting application.
[0044] The requesting application provides services to the user,
based on the map management data thus read out, the map data
described later, information obtained from the hardware 5 such as a
GPS receiver, and the like. Thus, navigation images are displayed
and audio navigation is given.
[0045] A description will now be given of the process involving the
map data.
[0046] When any of the applications 12-14 requires map data, the
application sends a request for the map data 31 to the map manager
21. The request analyzing unit 22 determines whether the requested
map data 31 is stored in the map data cache 42 of the data
management unit 24. When it is determined that the map data 31 is
not stored in the map data cache 42, the request analyzing unit 22
controls the data reading unit 23 to read out the map data 31 from
the recording medium 4 and supplies the data thus read out to the
data management unit 24.
[0047] The map data 31 supplied to the data management unit 24 is
stored by the control unit 41 in the map data storage area 42-i
constituting the map data cache 42. The request analyzing unit 22
reads out the map data from the data management unit 24 and
supplies the map data to the requesting application.
[0048] When it is determined that the map data 31 is stored in the
map data cache 42, the request analyzing unit 22 allows the control
unit 41 to read out the map data 31 and supplies the data thus read
out to the requesting application. The map data remains unlocked so
that, where there is a request for access from another application,
the request analyzing unit 22 permits the requesting application to
access the unlocked data so that the requested data is provided to
the requesting application. More specifically, as shown in FIG. 5,
when the three data items stored in respective map data storage
areas 42-1 - 42-3 are used by the applications 12-14, other
applications can access any of the three map data items stored in
the map data storage areas 42-1 - 42-3.
[0049] As described, according to the first embodiment, assuming
that a map data item stored in the map data cache 42 is already
accessed by a first application, access from a plurality of other
applications including second, third ... applications to the same
data item is granted so that the processing speed is improved.
[0050] In further accordance with the first embodiment, the map
data and the map management data read out from the data reading
unit 23 are managed independently by the data management unit 24
and are read out by the data management unit 24 when required. With
this, a large volume of map data and map management data can be
managed efficiently, thus improving the efficiency in application
processes.
[0051] Second Embodiment
[0052] FIG. 6 is a block diagram showing a construction of a data
management unit in an on-vehicle information processor according to
a second embodiment of the present invention. Referring to FIG. 6,
the data management unit comprises: a maximum total data size
setting unit 51 for setting an upper limit size defined as a
maximum size of map data stored in the map data cache 42; a total
data size calculating unit 52 for calculating a total size of map
data stored in the map data cache 42; a map data storage
determination unit 53 for determining whether a new map data item
is to be stored in the map data cache 42; and a discarded map data
determination unit 54 for determining the map data item that should
be discarded so as to release the corresponding map data storage
area in the map data cache 42.
[0053] The other components of the on-vehicle information processor
according to the second embodiment are identical to the
corresponding components of the first embodiment so that the
description thereof is omitted.
[0054] A description will now be given of the operation according
to the second embodiment.
[0055] FIG. 7 is a flowchart showing the operation of the data
management unit 24 of the on-vehicle information processor
according to the second embodiment.
[0056] In step ST1, the total data size calculating unit 52 of the
control unit 41 calculates a total size of map data stored in the
map data cache 42 before storing the map data 31 read out by the
data reading unit 23 in the map data cache 42. In step ST2, the map
data storage determination unit 53 determines whether a sum of the
total size of stored map data and the size of map data read out is
below the upper limit size set by the maximum total data size
setting unit 51.
[0057] When it is determined that the sum of the total size of
stored map data and the size of the map data read out is below the
upper limit, the map data read out is stored in step ST3 in the map
data storage area 42-i in the map data cache 42.
[0058] When it is determined that the sum of the total size of
stored map data and the size of the map data read out exceeds the
upper limit, the discarded map data determination unit 54
determines in step ST4 the map data to be discarded. In step ST5,
the map data thus determined to be discarded is discarded so that
the map data read out is stored in its place.
[0059] The operation described above is repeated whenever the map
data is read out by the map reading unit 23.
[0060] The discarded map data determination unit 54 may also be
employed when the map data cache stores the n map data items, to
determine the map data to be discarded. The map data thus
determined to be discarded is discarded so that the map data read
out is stored in place of the discarded data.
[0061] The other aspects of the operation according to the second
embodiment are the same as the corresponding aspects according to
the first embodiment so that the description thereof is
omitted.
[0062] As described, according to the second embodiment, the total
size of map data stored in the map data cache 42 is controlled to
be smaller the predetermined upper limit. Accordingly, the memory
size used in the map data cache 42 is known so that the memory
management is easy.
[0063] Third Embodiment
[0064] FIG. 8 is a block diagram showing a construction of a data
management unit in an on-vehicle information processor according to
a third embodiment of the present invention. Referring to FIG. 8,
the data management unit 24 comprises a map data storage area
identification unit 61 provided in the control unit 41. Reference
numeral 71 indicates a number of applications accessing a map data
item stored in the map data storage area 42-i. The map storage area
identification unit 61 refers to the number 71 before discarding
map data stored in the map data cache 42, so as to select the map
data storage area 42-i in which the number 71 is zero.
[0065] The other components of the on-vehicle information processor
according to the third embodiment are identical to the
corresponding components of the second embodiment so that the
description thereof is omitted.
[0066] A description will now be given of the operation according
to the third embodiment.
[0067] When a map data item stored in the map data cache 42 is
discarded in the third embodiment, the map data storage area
identification unit 61 of the control unit 41 refers to the number
71 of accessing applications so as to select the map data item not
accessed by any of the applications 12-14. The selected data item
is discarded by the discarded map data determination unit 54. A
replacing map data item is stored in the map data storage area 42-i
in which the map data item is discarded. The number 71 of accessing
applications is updated whenever the status of accesses from the
applications changes.
[0068] The other aspects of the operation according to the third
embodiment are identical to the corresponding aspects of the second
embodiment so that the description thereof is omitted.
[0069] As described, according to the third embodiment, the number
71 of accessing applications is referred to so as to select the map
data item not accessed by the applications before discarding the
map data stored in the map data cache 42. With this, the map data
is being accessed prevented from being discarded without locking
the map data while the application is accessing the map data.
[0070] Fourth Embodiment
[0071] FIG. 9 is a block diagram showing a construction of the data
management unit in an on-vehicle information processor according to
a fourth embodiment of the present invention. Referring to FIG. 9,
reference numeral 81 indicates a chronological sequence data
containing information relating to a sequence of storage of map
data or time when an access to map data occurs. The other
components of the on-vehicle information processor according to the
fourth embodiment are identical to the corresponding components of
the third embodiment so that the description thereof is
omitted.
[0072] A description will now be given of the operation according
to the fourth embodiment.
[0073] The map data storage area identification unit 61 refers to
the chronological sequence data 81 for each of the map data items,
so as to determine the map data item in the map data cache 42 to be
discarded based on the chronological sequence information. The map
data item associated with the oldest access time or the map data
associated with the oldest storage time may be selected.
[0074] The other aspects of the fourth embodiment are identical to
the corresponding aspects according to the third embodiment so that
the description thereof is omitted.
[0075] As described, according to the fourth embodiment, the
chronological sequence data 81 is referred to before discarding the
map data stored in the map data cache 42. Accordingly, the map data
that is relatively less likely to be accessed in the near future by
any of the applications 12-14 can be discarded. With this, the
frequency of accesses to the map data in the recording medium 4 is
reduced so that the efficiency in processing is improved.
[0076] The present invention is not limited to the above-described
embodiments, and variations and modifications may be made without
departing from the scope of the present invention.
* * * * *