U.S. patent application number 09/785426 was filed with the patent office on 2001-08-23 for danger deciding apparatus for motor vehicle and environment monitoring apparatus therefor.
This patent application is currently assigned to Yazaki Corporation. Invention is credited to Ishikawa, Naoto, Ogura, Hiroyuki.
Application Number | 20010016797 09/785426 |
Document ID | / |
Family ID | 18566855 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010016797 |
Kind Code |
A1 |
Ogura, Hiroyuki ; et
al. |
August 23, 2001 |
Danger deciding apparatus for motor vehicle and environment
monitoring apparatus therefor
Abstract
In a danger deciding means for a vehicle, information which
changes according to the road structure around a vehicle concerned
is acquired. When a plurality of images obtained by picking up
different monitoring regions are received, on the basis of the
acquired information, the image of the region which must be
monitored is selected from the plurality of images. The selected
image is processed to detect the approaching degree of an
approaching object. On basis of the approaching degree, danger of
contact or collision with the approaching object is decided.
Inventors: |
Ogura, Hiroyuki; (Shizuoka,
JP) ; Ishikawa, Naoto; (Shizuoka, JP) |
Correspondence
Address: |
ARMSTRONG,WESTERMAN, HATTORI,
MCLELAND & NAUGHTON, LLP
1725 K STREET, NW, SUITE 1000
WASHINGTON
DC
20006
US
|
Assignee: |
Yazaki Corporation
Tokyo
JP
|
Family ID: |
18566855 |
Appl. No.: |
09/785426 |
Filed: |
February 20, 2001 |
Current U.S.
Class: |
701/301 ;
340/436 |
Current CPC
Class: |
G06T 7/246 20170101 |
Class at
Publication: |
701/301 ;
340/436 |
International
Class: |
G06F 017/10 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2000 |
JP |
2000-44026 |
Claims
What is claimed is:
1. A danger deciding apparatus for a vehicle comprising:
information collecting means for acquring information which changes
according to a road structure around a vehicle concerned; selecting
means for selecting an image of the region which must be monitored
from a plurality of images on the basis of the collected
information when they are received, the plurality of images being
obtained by picking up different monitoring regions; detecting
means for processing the selected image to detect the approaching
degree of an approaching object; and deciding means for deciding
danger of contact with the approaching object on basis of the
approaching degree.
2. A danger deciding apparatus for a vehicle according to claim 1,
wherein the plurality of images include a rear-side direction image
obtained when a rear region is picked up and left/right-side
direction images obtained when left/right-direction regions are
obtained.
3. A danger deciding apparatus for a vehicle according to claim 1,
further comprising a speed sensor for detecting a speed of a
vehicle concerned, wherein the information collecting means
collects the speed as the above information.
4. A danger deciding apparatus for a vehicle according to claim 1,
wherein the plurality of images includes an image which is received
only when the road structure around the vehicle concerned becomes a
prescribed structure, and the information collecting means collects
the received image as the information.
5. A danger deciding apparatus for a vehicle according to claim 1,
further comprising: map storage means for storing map information
having road information including the road structure; information
acquiring means for acquiring information indicative of the present
position of the vehicle concerned; and reading means for reading
the road information around the present position of the vehicle
concerned from the map storage means on the basis of the
information acquired by the information acquiring means, wherein
the information collecting means collects the road information read
by the reading means as the information.
6. A danger deciding apparatus for a vehicle according to claim 1,
wherein the selecting means always selects the images of the
regions which must be monitored simultaneously or a single image
when they or it is received.
7. An environment monitoring apparatus for a vehicle comprising:
information collecting means for acquring information which changes
according to a road structure around a vehicle concerned; pick-up
means for picking up different monitoring regions to acquire a
plurality of images; selecting means for selecting an image of the
region which must be monitored from a plurality of images on the
basis of the collected information when they are received,
detecting means for processing the selected image to detect the
approaching degree of an approaching object; and deciding means for
deciding danger of contact with the approaching object on basis of
the approaching degree.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a danger deciding apparatus for a
motor vehicle and an environment monitoring apparatus for a motor
vehicle. More specifically, this invention relates to a danger
deciding apparatus for a motor vehicle for detecting the
approaching degree of an approaching object in a picked-up image of
an environment of the vehicle to decide the danger of contact or
collision (hereinafter simply referred to contact) with the
approaching object, and an environment monitoring apparatus for
monitoring the environment of the vehicle to decide the danger of
contact with the approaching object.
[0003] 2. Description of the Related Art
[0004] For example, when a driver of a vehicle running on a road of
one-side two or more lanes of e.g. a speed way intends to change
his running lane, if he changes the lane while he is missing a
vehicle which catches up with his own vehicle on another lane at a
higher speed than his own vehicle from the rear-side direction,
there is strong possibility of a serious accident.
[0005] When the following vehicle on the same lane abruptly
approaches his own vehicle from the rear-side direction, if the
driver makes abrupt braking, there is possibility of
bumping-into-the back. Therefore, it is desired that the driver
surely notices or recognizes other vehicles in the environment.
[0006] A technique for avoiding the danger as described above has
been proposed as an environment monitoring system for a vehicle in
JP-A-7-50769. Now referring to FIGS. 8A-8D, an explanation will be
given of this environment monitoring system.
[0007] FIGS. 8A-8C are views for explaining a change in a
rear/rear-side direction (hereinafter referred to as rear-side
direction) image acquired by a video camera 1. FIG. 8A shows a
status inclusive of the vehicle concerned. FIG. 8B shows an image
acquired by a video camera 13 at timing t in an environment of the
vehicle concerned. FIG. 8C shows an image acquired at timing
t+.DELTA.t.
[0008] Now it is assumed that the vehicle concerned is running
straight on a flat road. The road sign and building residing in the
rear of the vehicle concerned in FIG. 8A are observed as images
shown in FIGS. 8B and 8C at timings t and t+.DELTA.t, respectively.
Coupling the corresponding points in these two images provides
speed vectors as shown in FIG. 8D. There are referred to as
"optical flows".
[0009] It can be seen that the optical flows radially appear from
an FOE (Focus of Expansion) where the road disappears. While the
vehicle concerned runs, the optical flows of an object which leaves
from the vehicle concerned are vectors in a direction converging
toward the FOE. The optical flows on the object which approaches
toward the object concerned are vectors in a direction diverging
from the FOE.
[0010] Therefore, a conventional environment monitoring system
detects the optical flows by processing the rear-side direction
image acquired by a camera 13, and uses to monitor the relationship
between the vehicle concerned and the following vehicle or another
vehicle running on an adjacent lane to detect the other vehicle
approaching the vehicle concerned, thereby deciding danger of the
contact of the vehicle concerned with the approaching object.
[0011] In some prior arts, a technique of searching corresponding
points using two cameras is adopted. Specifically, an edge point Pa
(not shown) of an object is detected in a rear-side direction image
acquired by the one camera. A point Pb (not shown) of the image
acquired by another camera corresponding to the detected edge point
Pa is detected. The position P of the object is acquired by the
pixel coordinates of Pa and Pb. On the basis of the position P of
the approaching object acquired, the existence of the approaching
object such as another vehicle approaching the vehicle concerned is
detected and danger of contact of the approaching object is
decided.
[0012] As an alternative technique, cameras are installed to be
oriented toward both left-side and right-side directions in the
front or rear portion of the vehicle, and the images in both
left-side and right-side directions acquired by the cameras are
processed in the manner similar to the above rear-side direction
image. When the vehicle concerned approaches a side road
intersecting the vehicle concerned such an approaching an
intersection or outgoing from the garage facing a road, the
existence of the approaching object such as a man or another
vehicle approaching from the side road is detected and danger of
collision of the vehicle concerned with the approaching object is
decided.
[0013] In the environment monitoring apparatus for a vehicle, in
order to recognize an approaching object in the environment, the
camera(s) may be located at various points other than the points
where the rear-side direction image or side direction images can be
acquired.
[0014] However, the above prior art environment monitoring
apparatus individually makes image processing according to the
installed position of the camera to detect the approaching object.
Specifically, where both of rear-side monitoring and side
monitoring are intended simultaneously, two CPUs therefor are
prepared separately. The one is intended for processing the
rear-side direction image to detect the approaching object from the
rear-side direction. The other is intended for processing the side
direction image to detect the approaching object from the side
direction. Where extension of the monitoring range is intended by
provision of cameras in various directions, plural CPUs for image
processing must be prepared. This is problematic from the
standpoint of cost.
[0015] In order to solve the above problem, it can be proposed to
make image processing for plural images sequentially using a single
CPU. However, this lengthens the time required for image
processing, thereby deteriorating the accuracy of detecting the
approaching object. Thus, it is not possible to detect danger of
contact with an environmental approaching object.
SUMMARY OF THE INVENTION
[0016] A first object of this invention is to provide a danger
deciding apparatus for a motor vehicle which can decide danger of
contact with an environmental approaching object inexpensively and
accurately by selecting an image of the region which must be
monitored from a plurality of images in view of a road structure
and processing the selected image to detect the approaching
object.
[0017] A second object of this invention is to provide an
environment monitoring apparatus for a motor vehicle which can
monitor the environment accurately and inexpensively.
[0018] In order to attain the first object, in accordance with this
invention, as shown in FIG. 1, there is provided a danger deciding
apparatus for a vehicle comprising:
[0019] information collecting means 22a-1 for collecting
information which changes according to a road structure around a
vehicle concerned;
[0020] selecting means 22a-2 for selecting an image of the region
which must be monitored from a plurality of images on the basis of
the collected information when they are received, the plurality of
images being obtained by picking up different monitoring
regions;
[0021] detecting means 22a-3 for processing the selected image to
detect the approaching degree of an approaching object; and
[0022] deciding means 22a-4 for deciding danger of contact with the
approaching object on basis of the approaching degree.
[0023] In this configuration, noting that a region which must be
monitored should be determined according to the road structure
around the vehicle concerned, the image selected from a plurality
of images on the basis of the information which changes according
to the road structure is processed. In this case, the approaching
degree detecting means 22a-3, which is adapted to process a
plurality of images, processes only the image of the region which
must be monitored so that the accuracy of detecting the approaching
object is not deteriorated.
[0024] Preferably, the plurality of images include a rear-side
direction image obtained when a rear region is picked up and
left/right-side direction images obtained when left/right-direction
regions are obtained. For example, where the road structure has an
intersection difficult to see ahead of the vehicle concerned, the
left/right-side direction region must be monitored. Where the road
structure is a speedway, the rear-side direction region must be
monitored. Noting this, the image selected from the rear-side
direction image and left/right direction images on the basis of the
information which changes according to the road structure is
processed. In this way, the approaching degree detecting means
22a-3, which is adapted to process a rear-side direction image and
left/right-side direction images, processes only the image of the
region which must be monitored so that the accuracy of detecting
the approaching object is not deteriorated.
[0025] Preferably, the danger deciding apparatus for a vehicle
comprises a speed sensor 23 for detecting a speed of a vehicle
concerned and the information collecting means collects the speed
as the above information. In this configuration, the information
collecting means 22a-1 can divert the speed of the vehicle
concerned from the speed sensor as required information.
[0026] Preferably, the plurality of images include an image which
is received only when the road structure around the vehicle
concerned becomes a prescribed structure, and the information
collecting means collects the received image as the required
information. In this configuration, the information collecting
means can divert such an image as required information.
[0027] Preferably, the danger deciding apparatus for a vehicle
further comprises map storage means 25c for storing map information
having road information including the road structure; information
acquiring means 25b for acquiring information indicative of the
present position of the vehicle concerned; and reading means 22a-5
for reading the road information around the present position of the
vehicle concerned from the map storage means on the basis of the
information acquired by the information acquiring means. The
information collecting means collects the road information read by
the reading means as the information. In this configuration, the
information collecting means 22a-1 collects the road information
including the road structure around the present position read from
the map storage means 25c by the reading means 22a-5. Therefore,
the map storage means 25c and information acquiring means 25b of
the car navigation system installed in the vehicle concerned can be
used to collect the necessary information. In addition, the road
information including the road structure can be collected as the
required information.
[0028] Preferably, the selecting means always selects the images of
the regions which must be monitored simultaneously or a single
image when it is received. In this configuration, the
left/right-side direction images which must be processed
simultaneously or the single image which is not selected according
the road structure can be processed all the time.
[0029] In order to attain the second object, in accordance with
this invention, there is provided an environment monitoring
apparatus for a vehicle comprising:
[0030] information collecting means for acquiring information which
changes according to a road structure around a vehicle
concerned;
[0031] pick-up means for picking up different monitoring regions to
acquire a plurality of images;
[0032] selecting means for selecting an image of the region which
must be monitored from a plurality of images on the basis of the
collected information when they are received,
[0033] detecting means for processing the selected image to detect
the approaching degree of an approaching object; and
[0034] deciding means for deciding danger of contact with the
approaching object on basis of the approaching degree.
[0035] In this configuration, noting that a region which must be
monitored should be determined according to the road structure
around the vehicle concerned, the image selected from a plurality
of images on the basis of the information which changes according
to the road structure is processed. In this case, the approaching
degree detecting means 22a-3, which is adapted to process a
plurality of images, processes only the image of the region which
must be monitored so that the accuracy of detecting the approaching
object is not deteriorated.
[0036] The above and other objects and features of this invention
will be more apparent from the following description taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1 is a block diagram showing the basic configuration of
a danger deciding apparatus for a motor vehicle and an environment
monitoring apparatus for a motor vehicle according to this
invention;
[0038] FIG. 2 is a block diagram showing a first embodiment of an
environment monitoring apparatus equipped with the danger deciding
apparatus according to this invention;
[0039] FIGS. 3A and 3B are views for explaining the positions where
a rear-side direction camera, a right-side direction camera and a
left-side direction camera are attached;
[0040] FIG. 4 is a flowchart for explaining the processing
procedure of a CPU shown in FIG. 1;
[0041] FIG. 5 is a flowchart for explaining collection/selection of
information according to the first embodiment;
[0042] FIGS. 6A and 6B are views for explaining the processing of
detection of an optical flow in FIG. 4;
[0043] FIG. 7 is a flowchart for explaining collection/selection of
information according to the third embodiment;
[0044] FIG. 8A to 8D are views for explaining a change in the road
image in a rear-side direction acquired by a camera.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0045] Embodiment 1
[0046] An explanation will be given of the first embodiment of this
invention.
[0047] FIG. 2 is an environment monitoring apparatus for a motor
vehicle equipped with a danger deciding apparatus for a motor
vehicle according this invention. As seen from FIG. 1, the
environment monitoring apparatus includes an image pick-up section
1 picking up different monitoring regions to acquire a plurality of
images; and a danger deciding apparatus for a motor vehicle for
detecting the approaching degree of an approaching object such as
an approaching vehicle residing within a monitoring region picked
up by the image pick-up section 1.
[0048] As shown in FIGS. 2 and 3, at the front of a vehicle for
example, the image pick-up means 1 includes a right-side direction
camera 11R which is attached to the right-side position of the
front and picks up the right-side direction region of the vehicle
to acquire a right-side direction image, a right image plane 12R on
which the right-side direction image is imaged, a left-side
direction camera 11L which is attached to the left-side position of
the front and picks up the left-side direction region of the
vehicle to acquire a left-side direction image, and a left image
plane 12R on which the left-side direction image is imaged.
Therefore, as shown in FIG. 3A, when the vehicle concerned is
located at a position A before the approaching position of an
intersection, the left- and right-side direction cameras 11R and
11L can monitor the side direction road which intersects the lane
concerned on which the vehicle concerned runs.
[0049] The image pick-up means 1 further includes a rear-side
direction camera 14 which is attached to the top or rear of a rear
trunk of the vehicle toward the rear of the vehicle and picks up
the rear-side direction region to acquire a rear direction image
and a rear image plane 14 on which the rear-side direction image is
imaged. Therefore, as seen from FIG. 3B, the rear-side direction
camera 13 can monitor the lane concerned behind the vehicle
concerned and lanes adjacent to the vehicle concerned.
[0050] The danger deciding apparatus for a vehicle includes a
storage unit 21 for storing the image acquired from the image
pick-up unit 1, a microcomputer A22 (hereinafter referred to as
".mu.COM A22") which performs the processing based on the image
acquired by the image pick-up unit 1 and processing of deciding
danger of contact with another vehicle, a speed sensor 23 for
detecting the speed of the vehicle concerned to supply speed
information to the .mu.COM A22, and a warning unit 24 which gives a
warning when it is decided by the .mu.COM A22 that there is danger
of contact with another vehicle.
[0051] The storage unit 21 includes a first frame memory 21a, a
second frame memory 21b and an optical flow memory 21c. The first
and the second frame memories 21a and 21b temporarily store pixel
data with m rows and n columns of e.g. 512.times.512 pixels and
luminance of 0-255 levels which have been converted from the image
acquired by the image pick-up unit 1 and supplies them to the
.mu.COM A22.
[0052] These first and second frame memories 21a and 21b
successively store the images in such a fashion that the images are
stored in the first frame memory 21a at timing t, in the second
frame memory 21b at timing t+.DELTA.t, again in the first frame
memory 21a at timing t+2.DELTA.t . . .
[0053] The optical flow which is a movement quantity of an
approaching object between two images acquired apart by a
prescribed time .DELTA.t from each other is temporarily stored in
the optical flow memory 21c.
[0054] The .mu.COM 22 includes a CPU 22a for perfuming various
computations according to a prescribed control program, a ROM 22b
for storing the control program and prescribed values and a RAM 22c
for temporarily storing data necessary for performing the
computation.
[0055] The CPU 22a performs processing of collecting information
which changes according to the road structure around a vehicle
concerned (as information collecting means); processing of
selecting, on the basis of the collected information, an image
acquired by picking up a region which must be monitored from the
plurality of images when a rear-side direction image, left-side and
right-side direction images are received (as selecting means);
processing of detecting, as an optical flow, a movement quantity of
an approaching object in the selected images apart by a prescribed
time from each other (as means for detecting an approaching degree)
and processing of deciding danger of contact with an approaching
vehicle on the magnitude or position of the optical flow (as danger
deciding means).
[0056] A speed sensor 23 has a running sensor (not shown) which
generates a pulse signal whenever the vehicle runs by a unit
distance and others and detects the speed information on the pulse
signal from the running sensor. The speed information changes
according to the road structure around the vehicle concerned. This
is because the vehicle speed falls e.g. when there is an
intersection difficult to see ahead of the vehicle concerned, a
stopping line ahead of the vehicle, or the width of the lane
concerned is narrow, and rises e.g. when the lane concerned is a
speedway.
[0057] The warning unit 24 includes a display 24a and a speaker
24b. The display 24a informs the driver of danger in such a manner
that the image acquired by the image pick-up unit 1 is displayed,
or message is displayed when the CPU 22a within the .mu.COM A22
decides that there is danger of contact with another vehicle. The
speaker 24b informs the driver of danger by audio guidance or
warning sound.
[0058] FIG. 4 is a flowchart showing the procedure of processing
performed by the CPU 22a. Now referring to the flowchart of FIG. 4,
an explanation will be given of the operation of the environment
monitoring apparatus for a vehicle.
[0059] First, in response to "ON" of an ignition switch, the CPU
22a proceeds to an initial step (not shown) where the left-side
direction flag F1, right-side direction flag F2 and rear-side
direction flag F3 are reset to 0, and thereafter proceeds to a next
step S1.
[0060] In step S1, the CPU 22a decides whether or not both the
rear-side direction image and left/right-side direction image have
been received. If only one of the rear-side direction image and the
left/right-side direction image has been received ("NO" in step
S1), the CPU 22a sets the flag corresponding to the received image
at `1` (step S2) and proceeds to step S4. Namely, if only the
left/right-side direction images are received, the CPU 22a sets the
flag F1 for selecting the left-side direction image at `1`, and if
only the rear-side direction image is received, the CPU 22a sets
the flag F3 for selecting the rear-side direction image at `1`.
[0061] In these steps S1 and S2, when only the rear-side direction
image is received, i.e. only one image is received, or only the
left/right-side image is received, i.e. although two or more images
are received, only the images acquired when the regions which must
be monitored simultaneously are picked up, the input image (s) can
be monitored all the time irrespectively of the road structure.
[0062] On the other hand, if both images are received ("YES" in
step S1), the CPU 22a performs the processing of collecting
information which changes according to the road structure around
the vehicle concerned and selecting one of the rear-side direction
image and the left/right-side direction image on the basis of the
collected information (step S3). Referring to the flowchart of FIG.
5, an explanation will be given of the details of the processing of
information collection and selection. First, CPU 22a collects speed
information from the speed sensor 23 (step S301) , and decides
whether or not the speed of the vehicle concerned is not higher
than e.g. 3 Km/h (step S302).
[0063] If the vehicle speed is not higher than 3 km/h ("YES" in
step S302), CPU 22a decides that the road structure has an
intersection difficult to see ahead of the vehicle concerned, a
stopping line ahead of the vehicle, and/or narrow lane concerned.
Where the environment around the vehicle concerned has such a road
structure, it is necessary to detect an approaching object such as
another vehicle which approaches from a side road intersecting the
lane concerned. Therefore, CPU 22a sets the left-side direction
flag F1 at `1` to select the left-side direction image (step S303)
and proceeds to step S4.
[0064] On the other hand, if the vehicle speed is not lower than 60
km/h ("NO" in step S302 and "YES" in step S304), CPU 22a decides
that the road structure is a speedway or road of high priority.
Where the environment around the vehicle concerned has such a road
structure, it is necessary to detect an approaching object such as
another vehicle which approaches from the rear of the vehicle
concerned. Therefore, CPU 22a sets the rear-side direction flag F3
at `1` to select the rear-side direction image (step S305) and
proceeds to step S4. If the vehicle speed is not higher than 3 km/h
nor lower than 60 km/h, CPU 22a decides that the road structure
around the vehicle concerned does not include the left/right-side
direction monitoring and rear-side direction monitoring regions,
and returns to step S11.
[0065] In step S4 in FIG. 4, CPU 22a takes in the image
(hereinafter referred to as "selected image") corresponding to the
flag with `1` among the left-side direction flag F1, right-side
direction flag F2 and rear-side direction flag F3, and stores it in
the first frame memory 21a (step S5). After a prescribed time
.DELTA.t, CPU 22a takes in the selected image and stores it in the
second frame memory 21b.
[0066] CPU 22a performs the processing of detecting an optical flow
indicative of the movement quantity of the approaching object in
the selected images apart by the prescribed time, and stores the
detected optical flow in the optical flow memory 21c (step S6).
[0067] An explanation will be given of the details of the
processing of detecting an optical flow.
[0068] As described in connection with the prior art, the
approaching object moves in a diverging direction of the optical
flow from the point where the road and others vanishes from the
selected image, i.e. FOE. Noting this fact, referring to FIGS. 6A
and 6B, the procedure of detecting the optical flow will be
explained.
[0069] First, on the selected image picked up at timing t, a
slender window W1 is set around a certain characteristic point P in
a radial direction of the FOE set as described above (i.e. in the
direction of connecting the FOE 1 to the characteristic point P)
(FIG. 6A). Subsequently, on the selected image at timing t+t.DELTA.
acquired from the second frame memory 21b, while a window W2
corresponding to the window W1 is shifted one point by one point in
the radial direction from the FOE, its correlated value with the
window W1 (FIG. 6B). The point Q of the window W2 where the
correlated value is the maximum is taken as the point corresponding
to the point P, i.e. the point on the same object. The movement PQ
is detected as the optical flow which represents the movement
quantity of the approaching object. The detected optical flow is
stored in the optical flow memory 21c.
[0070] Incidentally, the characteristic point may be a pixel having
a prescribed luminance difference from that of its adjacent pixel.
The FOE may be a crossing point of the extended lines of the white
lines located on both sides of the road picked up on the selected
image.
[0071] CPU 22a performs the processing of deciding danger of the
contact with another vehicle on the basis of the size of the
optical flow stored in the optical flow memory 21c (Step S7).
[0072] If it is decided that there is danger of contact ("YES" in
step S8), in order to inform the driver of this fact, CPU 22a
performs the processing of warning of issuing a warning sound
signal and/or a warning image signal to the warning unit 24 (step
S9), and proceeds to step S10. In response to the warning signal, a
warning indication "there is an approaching vehicle" is displayed
on the display 24a, or a warning guidance "there is an approaching
vehicle" is issued by sound from e.g. the speaker 5a.
[0073] On the other hand, if it is decided in the processing of
danger deciding that there is no danger of contact with another
vehicle ("NO" in step S8), CPU 22a directly proceeds to step S10.
In step S10, it is decided whether or not the left-side direction
flag F1 is 1. If the left-side direction flag F1 has been set at 1
in the processing of step S2 or S3 ("YES" in step S10), in order to
monitor the right-side direction region, CPU 22a sets the left-side
direction flag F1 at 0 and the right-side direction flag F2 at 1,
and returns to step S2 (step S11). In step S1, after the processing
has been made on the left-side direction image, the processing will
be automatically made on the right-side direction image.
[0074] On the other hand, if the rear-side direction flag F3 is 1
or the right-direction flag F2 is 1 after completion of the
left/right monitoring by the processing of step S2 or step S3 ("NO"
in step S10), CPU 22a resets the left/right-side direction flags
F1, F2 and rear-side direction flag F3 (step S12) and returns to
step S1.
[0075] As described above, the processing is made on the image
selected from the rear-side direction image and the left/right-side
direction image on the basis of the speed information which changes
according to the road structure. Therefore, where CPU 22a is adpted
to process both the rear-side direction image and the
left/right-side direction images, the processing is made on only
the image acquired by picking up the region which must be
monitored. Thus, it is possible to decide the danger of contact
with an approaching object in the environment of the vehicle
concerned inexpensively and accurately without deteriorating the
detecting accuracy of the object.
[0076] Since the speed information from the speed sensor 23 mounted
on the vehicle is used as the information which changes according
to the road structure, there is no need of providing additional
means for producing necessary information. This contributes to cost
reduction of the monitoring apparatus.
[0077] Embodiment 2
[0078] In the first embodiment, the speed information of the
vehicle was collected as the information which changes according to
the road structure. Meanwhile, in a main conventional monitoring
apparatus, the side-direction monitoring has been made while the
driver is seeing the left/right-side direction image displayed on
the display 24a.
[0079] In some monitoring apparatus, when the vehicle speed becomes
3 Km/h or lower, on the basis of the decision that the road
structure around the vehicle concerned has a prescribed structure
e. g. there is an intersection difficult to see ahead of the
vehicle concerned, the left/right-side direction image pick-up
cameras 11 are automatically tuned on to acquire the
left/right-side direction images and display them on the display
24a. Therefore, for the purpose of image selection, the acquired
information on the left/right-side direction image from the
monitoring apparatus can be used as the information which changes
according to the road structure in the environment of the vehicle
concerned. In this case also, there is no need of providing
additional means for producing necessary information. This
contributes to cost reduction of the monitoring apparatus.
[0080] Embodiment 3
[0081] In place of the speed information, the information taken
from a car navigation system 25 which is mounted in the vehicle can
be used for the purpose of image selection. An explanation will be
given of an environment monitoring apparatus for a vehicle equipped
with a danger deciding apparatus using the car navigation
system.
[0082] As shown in FIG. 2, the car navigation system 25 includes a
GPS receiver 25b (information acquisition means) for receiving the
present position information representative of the present position
of the vehicle on an earth through a GPS antenna 25a, a map data
base 25c in which the map information having road information
containing a road structure is stored, and .mu. COM A 22 for
computing the passage of the vehicle concerned to a destination.
The .mu. COM A22 receives the present position information from the
GPS receiver 25b, map information from the map data base 25c and
the passage information from the .mu. COM B 25d.
[0083] The environment monitoring apparatus according to the third
embodiment operates in the same manner as the first embodiment
except the processing of information collection/selection. Now
referring to the flowchart of FIG. 7 showing the information
collection/selection by the CPU 22a, an explanation will be given
of the operation of the third embodiment.
[0084] First, the CPU 22a acquires the present position information
from the GPS receiver 25a (step S306), and reads, from the map data
base 25c, the environmental road information of the vehicle
concerned corresponding to the present position information thus
acquired (step S307). In step S307, the CPU 22a operates as a
reading means.
[0085] On the basis of the road information thus acquired and the
passage information from the .mu. COMB 25d, in step S308, it is
decided whether or not the environment of the vehicle concerned has
a road structure for which the side direction region must be
monitored (e.g. there is an intersection difficult to see or a
temporarily stopping line ahead of the vehicle concerned, the width
of the road on which the vehicle concerned is running is narrow,
the present position is an exit from a car park or a facility to a
road). If YES, in order to select the left/right-side direction
images, the left-side flag F1 is first set at 1 so that the
left-side direction image is selected (step S309).
[0086] If NO in step S308, it is decided that the rear-side
direction must be monitored. In this case, the rear-side direction
image flag F3 is set at 1 to select the rear-side direction image
(step S310).
[0087] As described above, since the environment road information
of the vehicle concerned acquired from the map data base 25c is
collected as information which changes according to the road
structure, the map data base 25c and GPS receiver 25b of the car
navigation apparatus can be used to acquire the information.
Therefore, there is no need of providing means for producing the
information corresponding to the road structure. This simplifies
the structure of the environment monitoring apparatus and further
reduces the production cost thereof. Further, since the road
information including the road structure is acquired, it is
possible to decide accurately the danger of contact with an
approaching object.
[0088] Where the .mu. COMB 25d reads the road information of the
present position from the map data base 25c and produces the read
information thus read, as in the third embodiment, the CPU 22a does
not read the road information, but the .mu. COM B 25d has only to
acquire the road information.
[0089] In the first to the third embodiments, the CPU 22a could
operate as the means for detecting the approaching degree by way of
detection of the optical flow. However, the CPU 22a can operate as
the means for detecting the approaching degree by way of detection
of the distance from the object using two cameras apart from each
other by a prescribed distance in a sterescopic system.
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