U.S. patent application number 15/671839 was filed with the patent office on 2018-03-15 for driving assistance device.
This patent application is currently assigned to SUZUKI MOTOR CORPORATION. The applicant listed for this patent is SUZUKI MOTOR CORPORATION. Invention is credited to Koji KURATA.
Application Number | 20180072314 15/671839 |
Document ID | / |
Family ID | 61247214 |
Filed Date | 2018-03-15 |
United States Patent
Application |
20180072314 |
Kind Code |
A1 |
KURATA; Koji |
March 15, 2018 |
DRIVING ASSISTANCE DEVICE
Abstract
There is provided a driving assistance device. When there is a
possibility that weather influences a detection performance of a
vehicle detection unit configured to detect a preceding vehicle
traveling in front of a subject vehicle and to measure an
inter-vehicular distance to the preceding vehicle, a speed
reduction control assistance unit enables a speed reduction control
unit to perform a primary speed reduction control at a
predetermined distance ahead of an entry or an exit of a
tunnel-shaped road structure. Thereafter, when the vehicle
detection unit detects the preceding vehicle and the
inter-vehicular distance is equal to or smaller than a
predetermined value, the speed reduction control assistance unit
enables the speed reduction control unit to perform a secondary
speed reduction control.
Inventors: |
KURATA; Koji;
(Hamamatsu-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SUZUKI MOTOR CORPORATION |
Hamamatsu-shi |
|
JP |
|
|
Assignee: |
SUZUKI MOTOR CORPORATION
Hamamatsu-shi
JP
|
Family ID: |
61247214 |
Appl. No.: |
15/671839 |
Filed: |
August 8, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60W 10/06 20130101;
B60W 2556/50 20200201; B60W 2552/05 20200201; B60W 2554/00
20200201; B60W 10/18 20130101; B60W 30/143 20130101; B60W 2555/20
20200201; B60K 31/0008 20130101; B60W 30/16 20130101; B60W 2552/00
20200201; B60W 2710/18 20130101; B60T 2201/02 20130101; B60T 7/22
20130101; B60W 2710/0627 20130101; B60W 2710/0616 20130101; B60T
7/12 20130101; B60K 2031/0025 20130101 |
International
Class: |
B60W 30/14 20060101
B60W030/14; B60K 31/00 20060101 B60K031/00; B60T 7/12 20060101
B60T007/12 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 13, 2016 |
JP |
2016-178673 |
Claims
1. A driving assistance device configured to reduce a speed of a
subject vehicle on the basis of an output of a vehicle detection
unit which is configured to detect a preceding vehicle traveling in
front of the subject vehicle and to measure an inter-vehicular
distance between the subject vehicle and the preceding vehicle, the
driving assistance device comprising: a speed reduction control
unit configured to perform a speed reduction control for the
subject vehicle; and a speed reduction control assistance unit
configured to enable the speed reduction control unit to perform
the speed reduction control, wherein when there is a possibility
that weather in a surrounding of the subject vehicle influences a
detection performance of the vehicle detection unit, the speed
reduction control assistance unit enables the speed reduction
control unit to perform a primary speed reduction control at a
predetermined distance ahead of an entry or an exit of a
tunnel-shaped road structure on the basis of information about a
position of the subject vehicle and a road structure on a traveling
road on which the subject vehicle travels, and thereafter, when the
vehicle detection unit detects the preceding vehicle and the
inter-vehicular distance is equal to or smaller than a
predetermined value, the speed reduction control assistance unit
enables the speed reduction control unit to perform a secondary
speed reduction control.
2. The driving assistance device according to claim 1, wherein a
control amount of the primary speed reduction control is less than
a control amount of the secondary speed reduction control.
3. The driving assistance device according to claim 1, wherein the
primary speed reduction control is fuel supply cut, and the
secondary speed reduction control is a brake control.
4. The driving assistance device according to claim 1, wherein at a
side of the entry of the tunnel-shaped road structure, the speed
reduction control assistance unit enables the speed reduction
control unit to perform the primary speed reduction control and the
secondary speed reduction control when the vehicle detection unit
detects a large-sized vehicle.
5. The driving assistance device according to claim 1, wherein at a
side of the exit of the tunnel-shaped road structure, the speed
reduction control assistance unit enables the speed reduction
control unit to perform the primary speed reduction control and the
secondary speed reduction control when the vehicle detection unit
detects the preceding vehicle in the tunnel-shaped road
structure.
6. The driving assistance device according to claim 1, further
comprising a notification unit that notifies a deceleration state
of the subject vehicle to a following vehicle traveling at the rear
of the subject vehicle when the speed reduction control assistance
unit enables the speed reduction control unit to perform the
primary speed reduction control.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The disclosure of Japanese Patent Application No.
2016-178673 filed on Sep. 13, 2016, including specification,
drawings and claims is incorporated herein by reference in its
entirety.
TECHNICAL FIELD
[0002] The disclosure relates to a driving assistance device.
BACKGROUND
[0003] In the related art, regarding an automatic four-wheeled
vehicle, a driving assistance system configured to control a
traveling speed of a subject vehicle so as to secure an
inter-vehicular distance between the subject vehicle and a
preceding vehicle traveling in front of the subject vehicle has
been suggested.
[0004] When detecting the preceding vehicle by means of a radar,
detection performance of the radar is lowered under bad weathers
such as heavy rain, dense fog and the like. As a result, it is
determined that there is no preceding vehicle, so that speed
reduction control is delayed and a passenger should resultantly
operate a brake. In order to solve the problem, a technology of
providing a rainfall amount detection unit configured to detect an
amount of rainfall and stopping the inter-vehicular distance
control when a detected rainfall amount value is equal to or
greater than a predetermined value has been suggested (for example,
refer to Patent Document 1).
[0005] Patent Document 1: Japanese Patent Application Publication
No. H10-081156A
[0006] In the vicinity of a gateway of a tunnel, a flow of wind is
complicated due to an influence of the wind moving in the tunnel.
For this reason, since raindrops, fog and the like move
intricately, the detection environments of the radar are
temporarily deteriorated, so that the detection performance of the
radar is temporarily lowered. As a result, a phenomenon that the
preceding vehicle is late detected or is temporarily missed
occurs.
[0007] When the speed of the subject vehicle is high, even the
phenomenon for an extremely slight time period highly exerts a bad
influence on a driving assistance. The detection delay and the
temporary missing cause a rapid operation of an automatic brake to
deteriorate a ride quality, cause a bad influence on a following
vehicle, such as a harsh braking, and become an origination of a
traffic jam.
[0008] The above phenomena become conspicuous when the preceding
vehicle is a small-sized vehicle, particularly, a saddle-ridden
vehicle.
[0009] Patent Document 1 does not disclose the temporary
deterioration of the detection environments of the radar in the
vicinity of the gateway of the tunnel.
SUMMARY
[0010] It is therefore an object of the disclosure to provide a
driving assistance device capable of improving a ride quality of a
subject vehicle in the vicinity of a gateway of a tunnel and the
like and reducing a bad influence on a following vehicle even under
a bad weather and the like.
[0011] According to an aspect of the embodiments of the present
invention, there is provided a driving assistance device configured
to reduce a speed of a subject vehicle on the basis of an output of
a vehicle detection unit which is configured to detect a preceding
vehicle traveling in front of the subject vehicle and to measure an
inter-vehicular distance between the subject vehicle and the
preceding vehicle, the driving assistance device comprising: a
speed reduction control unit configured to perform a speed
reduction control for the subject vehicle; and a speed reduction
control assistance unit configured to enable the speed reduction
control unit to perform the speed reduction control, wherein when
there is a possibility that weather in a surrounding of the subject
vehicle influences a detection performance of the vehicle detection
unit, the speed reduction control assistance unit enables the speed
reduction control unit to perform a primary speed reduction control
at a predetermined distance ahead of an entry or an exit of a
tunnel-shaped road structure on the basis of information about a
position of the subject vehicle and a road structure on a traveling
road on which the subject vehicle travels, and thereafter, when the
vehicle detection unit detects the preceding vehicle and the
inter-vehicular distance is equal to or smaller than a
predetermined value, the speed reduction control assistance unit
enables the speed reduction control unit to perform a secondary
speed reduction control.
[0012] According to the disclosure, it is possible to improve the
ride quality of the subject vehicle in the vicinity of the gateway
of the tunnel and the like and reducing the bad influence on the
following vehicle even under the bad weather and the like.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In the accompanying drawings:
[0014] FIGS. 1A and 1B are pictorial views depicting a relation
between a subject vehicle and other detection target in the
vicinity of an entry of a tunnel;
[0015] FIGS. 2A and 2B are pictorial views depicting a relation
between the subject vehicle and other detection target in the
vicinity of an exit of the tunnel;
[0016] FIG. 3 is a pictorial view depicting a relation between the
subject vehicle and other detection target in the vicinity of the
entry of the tunnel in which a road is passable on both sides;
[0017] FIG. 4 is a pictorial view depicting a relation between the
subject vehicle and other detection target in the vicinity of the
exit of the tunnel in which a road is passable on both sides;
[0018] FIG. 5 is a schematic configuration view of a driving
assistance device in accordance with an illustrative
embodiment;
[0019] FIG. 6 is a control flow of the driving assistance device in
accordance with the illustrative embodiment;
[0020] FIG. 7 is a control flow of the driving assistance device in
accordance with the illustrative embodiment; and
[0021] FIG. 8 is a control flow of the driving assistance device in
accordance with the illustrative embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0022] Hereinafter, an illustrative embodiment of the disclosure
will be described in detail with reference to the accompanying
drawings. Meanwhile, in below descriptions, an example where a
driving assistance device of the disclosure is applied to an
automatic four-wheeled vehicle of an automatic driving type will be
described. However, the target to be applied is not limited thereto
and can be changed. For example, the driving assistance device of
the disclosure can also be applied to a vehicle of other type (for
example, a saddle-ridden vehicle such as an automatic three-wheeled
vehicle).
[0023] In the meantime, the disclosure can also be effectively
applied to a manual driving-type vehicle, not the automatic driving
type. Specifically, a case where a driver is in an inattentive
driving state (a state where attentiveness is lower than usual) due
to fatigue or the like can be exemplified. In the inattentive
driving state, since a subject of vehicle control with a preceding
vehicle during the driving relies on a driving assistance device
mounted on the subject vehicle, not the driver, in many cases, the
disclosure can be effectively applied.
[0024] A problem in a tunnel to which the driving assistance device
of the illustrative embodiment is to be applied is described with
reference to FIGS. 1A to 4. FIGS. 1A and 1B are pictorial views
depicting a relation between a subject vehicle and other detection
target in the vicinity of an entry of a tunnel. FIG. 1A is a top
view, as seen from above of a subject vehicle 1, and FIG. 1B is a
side view, as seen from a side of the subject vehicle 1. As shown
in FIGS. 1A and 1B, a tunnel 3 exists in front of a road 2 on which
the subject vehicle 1 is traveling. Also, a motorcycle 4, which is
an example of the saddle-ridden vehicle, is traveling in front of
the subject vehicle 1. A large truck 5, which is an example of the
large-sized vehicle, is traveling in front of the motorcycle 4.
[0025] In FIGS. 1A and 1B, a broken line A indicates a radar
illumination range of a millimeter wave radar (which will be
described later), which is provided on a front surface of the
subject vehicle 1 and is an example of the vehicle detection
unit.
[0026] Also, in FIGS. 1A and 1B, an arrow shown with a solid line
around the large truck 5 indicates a flow of wind that is generated
by the large truck 5. Also, in FIG. 1B, an arrow B shown with a
broken line indicates rain at the entry-side of the tunnel 3. Also,
an arrow C shown with a dotted line indicates a flow of wind that
is generated in the tunnel 3.
[0027] As shown in FIGS. 1A and 1B, in the vicinity of the entry of
the tunnel 3, a complicated flow of wind is generated around the
large truck 5 in front of the subject vehicle 1. For example, when
a front part of the large truck 5 collides against the wind (the
arrow C) blowing in the tunnel 3, a wind directed from the front
part towards an upper side of a roof of a cargo compartment of the
large truck 5 is generated. Also, a wind that curls up from a road
surface of the road 2 and blows rearwards when tires of the large
truck 5 rotate is generated. Also, at the rear part of the large
truck 5, the wind blows from a ceiling of the cargo compartment
towards a rear surface part-side thereof, thereby generating a
turbulence flow.
[0028] When it rains heavily (the arrow B) at the state where the
complicated flows of winds are generated, for example, numberless
raindrops move with being intricately disturbed on the wind in a
range X denoted with the dashed-two dotted line in FIGS. 1A and 1B.
Also, the wind, curling up from the tires of the large truck 5
curls up the water from the road surface of the road 2, so that the
raindrops become denser.
[0029] The detection environments by a millimeter wave radar in the
range X are likely to be deteriorated, as compared to the road 2
except for the vicinity of the gateway of the tunnel 3. In the
detection environments, a possibility that a vehicle detection
unit, for which the millimeter wave radar is used, will overlook or
miss the motorcycle 4 traveling between the subject vehicle 1 and
the large truck 5 increases.
[0030] FIGS. 2A and 2B are pictorial views depicting a relation
between the subject vehicle 1 and other detection target in the
vicinity of an exit of the tunnel 3. FIG. 2A is a top view, as seen
from above of the subject vehicle 1, and FIG. 1B is a side view, as
seen from a side of the subject vehicle 1. The same configurations
as FIGS. 1A and 1B are denoted with the same reference numerals,
and the descriptions thereof are omitted.
[0031] As shown in FIGS. 2A and 2B, in the vicinity of the exit of
the tunnel 3, a complicated flow of wind is generated around the
large truck 5 in front of the subject vehicle 1. For example, a
wind directed from the front part of the large truck 5 towards the
upper side of the roof of the cargo compartment of the large truck
5 is generated. Also, a wind that curls up from the road surface of
the road 2 and blows rearwards when the tires of the large truck 5
rotate is generated. Further, at the rear part of the large truck
5, the wind blows from the ceiling of the cargo compartment towards
the rear surface part-side thereof, thereby generating a turbulence
flow. The turbulence flow is further complicated due to the wind
(the arrow C) blowing in the tunnel 3.
[0032] When it rains heavily (the arrow B) at the state where the
complicated flows of winds are generated, for example, numberless
raindrops move with being intricately disturbed on the wind in the
range X denoted with the dashed-two dotted line in FIGS. 2A and 2B.
Also, the wind curling up from the tires of the large truck 5 curls
up the water from the road surface of the road 2, so that the
raindrops become denser. Furthermore, the raindrops having collided
with the roof of the large truck 5 blow towards the rear of the
large truck 5 on the wind, so that the raindrops become further
denser.
[0033] The detection environments by the millimeter wave radar in
the range X are likely to be deteriorated, as compared to the road
2 except for the vicinity of the gateway of the tunnel 3. In the
detection environments, there is a possibility that the vehicle
detection unit, for which the millimeter wave radar is used, will
miss the motorcycle 4 traveling between the subject vehicle 1 and
the large truck 5.
[0034] In FIGS. 1A, 1B, 2A and 2B, the example where the road 2 is
a one-way traffic has been described. When the road 2 is passable
on both sides, the possibility that the detection environments will
be further deteriorated due to an influence of an opposite vehicle
increases. FIGS. 3 and 4 are pictorial views depicting a relation
between the subject vehicle 1 and other detection target in the
vicinity of the gateway of the tunnel 3 in which a road is passable
on both sides.
[0035] As shown in FIGS. 3 and 4, in the vicinity of the gateway of
the tunnel 3, the wind denoted with an arrow a blows from an
opposite vehicle 6, which is traveling on an opposite lane 2b
opposite to a lane 2a of the road 2 on which the subject vehicle 1
is traveling, towards the rear of the large truck 5. For this
reason, the turbulence flow at the rear of the large truck 5 is
further complicated, so that the detection environments by the
millimeter wave radar in the range X are more likely to be
deteriorated. In the detection environments, the possibility that
the vehicle detection unit, for which the millimeter wave radar is
used, will miss the motorcycle 4 traveling between the subject
vehicle 1 and the large truck 5 increases.
[0036] As described above, when the large truck 5 travels in front
of the subject vehicle 1, in the vicinity of the gateway of the
tunnel 3, the detection environments of the vehicle detection unit
of the subject vehicle 1, for example, the millimeter wave radar,
are very poor, as compared to the fair weather. For this reason,
there is a possibility that the detection of the small-sized
vehicle, particularly, the motorcycle 4, which is an example of the
saddle-ridden vehicle of which a reflection area of radar waves is
small, will be delayed or the small-sized vehicle will be
temporarily overlooked.
[0037] When the speed of the subject vehicle 1 is high, the
situations change even in very little time. For example, when the
subject vehicle 1 travels at speed of 100 km/H, the subject vehicle
1 moves forward about 28 m in one second. In this case, at the
corresponding speed, when the motorcycle 4 in front of the subject
vehicle 1 moves at low speed due to the traffic jam in the tunnel 3
(when the motorcycle has to travel at low speed on a sudden), for
example, it is necessary to take measures against the detection
(finding) delay and temporary missing.
[0038] As an example of the detection delay in the vicinity of the
entry of the tunnel 3 as shown in FIGS. 1A, 1B and 3, a case where
when the subject vehicle 1 catches up with the motorcycle 4 in
front of the subject vehicle 1 in the vicinity of the entry of the
tunnel 3, the vehicle detection unit of the subject vehicle 1 can
detect the motorcycle 4 under normal circumstances but cannot
detect the same due to the deterioration of the detection
environments may be exemplified.
[0039] In this case, when the subject vehicle 1 enters the tunnel 3
and is not influenced by the bad weather outside the tunnel 3, the
vehicle detection unit detects the motorcycle 4. Thus, the driving
assistance device falsely recognizes that the motorcycle suddenly
appears, and performs speed reduction control if a predetermined
inter-vehicular distance is not secured, and the rapid speed
reduction control is required, depending on the situations.
[0040] As an example of the temporary missing, as shown in FIGS. 1A
and 1B, a case where when a large-sized vehicle such as the large
truck 5 travels in front of the subject vehicle 1 and the
motorcycle 4 travels at the rear of the large-sized vehicle and in
front of the subject vehicle 1, the driving assistance device can
normally detect the motorcycle 4 ahead of the entry of the tunnel 3
but the vehicle detection unit cannot detect the motorcycle 4 due
to the temporary deterioration of the detection environments in the
vicinity of the entry of the tunnel 3 may be exemplified.
[0041] In this case, since the subject vehicle 1 travels as if
there were no the motorcycle 4 ahead of the subject vehicle even
though the motorcycle 4 actually exists, the inter-vehicular
distance between the subject vehicle 1 and the motorcycle 4 may not
be sufficiently secured.
[0042] At this situation, when the subject vehicle 1 enters the
tunnel 3 and is not influenced by the bad weather outside the
tunnel 3, the vehicle detection unit again detects the motorcycle
4. Thus, the driving assistance device falsely recognizes that the
motorcycle suddenly appears, and performs the speed reduction
control if a predetermined inter-vehicular distance is not secured,
and the rapid speed reduction control is required, depending on the
situations.
[0043] In the meantime, in the vicinity of the exit of the tunnel 3
as shown in FIGS. 2A, 2B and 4, since the subject vehicle 1 is
still in the tunnel 3, the subject vehicle is not directly
influenced by the bad weather but is influenced by the raindrops
blowing into the tunnel on the wind from the outside of the tunnel
3. For this reason, the detection environments are temporarily
deteriorated, so that the vehicle detection unit may temporarily
miss the motorcycle 4.
[0044] When the subject vehicle 1 goes out of the tunnel 3 and the
detection environments are improved, the vehicle detection unit
again detects the motorcycle 4. In this case, when the sufficient
inter-vehicular distance between the subject vehicle 1 and the
motorcycle 4 is not secured, the speed reduction control is
performed in the subject vehicle and the rapid speed reduction
control is required, depending on the situations.
[0045] The rapid speed reduction control in the vicinity of the
gateway of the tunnel deteriorates a ride quality and exerts a bad
influences on the following vehicle, so that it may become an
origination of a traffic jam. As an example of the bad influence on
the following vehicle, a case where the following vehicle is caused
to make a hard stop when the inter-vehicular distance between the
subject vehicle and the following vehicle is not sufficient may be
exemplified.
[0046] In particular, when the subject vehicle 1 is an automatic
driving vehicle, it is very important to improve the ride quality
and to reduce the bad influence on the following vehicle.
[0047] Therefore, the inventors found that when there is a
possibility that the detection of a preceding vehicle (the
motorcycle 4) will be delayed or the preceding vehicle will be
temporarily missed due to the bad weather in the vicinity of the
gateway of the tunnel 3 (refer to FIGS. 1A to 4), if the subject
vehicle 1 is enabled to once perform gentle speed reduction in
advance and then to perform the speed reduction control in a
stepwise manner, it is possible to avoid the harsh braking and to
improve the ride quality, and conceived the disclosure.
[0048] That is, an aspect of the driving assistance device of the
disclosure is a driving assistance device configured to reduce a
speed of a subject vehicle on the basis of an output of a vehicle
detection unit configured to detect a preceding vehicle traveling
in front of the subject vehicle and to measure an inter-vehicular
distance between the subject vehicle and the preceding vehicle. The
driving assistance device includes a speed reduction control unit
configured to perform speed reduction control for the subject
vehicle, and a speed reduction control assistance unit that, when
there is a possibility that a surrounding weather of the subject
vehicle will influence detection performance of the vehicle
detection unit, enables the speed reduction control unit to perform
primary speed reduction control at a predetermined distance ahead
of an entry or an exit of a tunnel-shaped road structure on the
basis of information about a position of the subject vehicle and a
road structure on a traveling road on which the subject vehicle
travels, and then when the vehicle detection unit detects the
preceding vehicle and the inter-vehicular distance is equal to or
smaller than a predetermined value, enables the speed reduction
control unit to perform secondary speed reduction control.
[0049] In an aspect of the driving assistance device of the
disclosure, the subject vehicle is an automatic four-wheeled
vehicle (including a mini vehicle, a large truck, a large bus and
the like) or a saddle-ridden vehicle (including a motorcycle, an
automatic three-wheeled vehicle and the like). The subject vehicle
is an automatic driving vehicle configured to perform automatic
driving on the basis of an output from the vehicle detection unit
configured to detect the preceding vehicle.
[0050] In an aspect of the driving assistance device of the
disclosure, the preceding vehicle is a vehicle that is likely to be
overlooked in the detection, specifically, a small-sized vehicle
including an automatic four-wheeled vehicle such as a mini vehicle
and a sports car and a saddle-ridden vehicle. The saddle-ridden
vehicle is a motorcycle or an automatic three-wheeled vehicle, for
example. Since the saddle-ridden vehicle has a size smaller than
the automatic four-wheeled vehicle, a reflection area of radar
waves is small and movement is agile.
[0051] Also, in an aspect of the driving assistance device of the
disclosure, the vehicle detection unit is a detection unit
configured to use reflected waves, such as a millimeter wave radar,
an infrared radar, an ultrasonic radar and the like and a camera
such as a CCD camera, an infrared camera and the like. In the
illustrative embodiment, the vehicle detection unit, for which the
millimeter wave radar is used, is exemplified.
[0052] Also, in an aspect of the driving assistance device of the
disclosure, the description "when there is a possibility that the
surrounding weather of the subject vehicle will influence the
detection performance of the vehicle detection unit" means a bad
weather such as heavy rain, heavy snow, dense fog, smog and the
like.
[0053] Also, in an aspect of the driving assistance device of the
disclosure, the road structure indicates a structure that is built
on the road or around the road. Also, the tunnel-shaped road
structure indicates a space that is elongated in an axial
direction, as compared to a height or a width of a section, such as
the tunnel 3 (refer to FIGS. 1A to 4), i.e., a structure having a
ceiling or walls higher than a vehicle and built at both sides of
the vehicle. The tunnel-shaped structure includes a sidewall built
along a road and a space surrounded by an elevated bridge
(including a highway, a railroad and the like) located at a
position higher than a road surface of the road, for example.
[0054] Also, in an aspect of the driving assistance device of the
disclosure, the predetermined distance ahead of the entry or exit
of the tunnel-shaped road structure indicates a distance within
which the subject vehicle 1 under traveling can safely stop with
respect to the motorcycle 4 (refer to FIGS. 1A, 1B, 2A and 2B)
positioned at the entry or exit of the tunnel-shaped road
structure. Herein, the safely stoppable distance may be a value
determined on the basis of a traveling speed of the subject vehicle
1 or a value determined in consideration of relative speeds of the
subject vehicle 1 and the motorcycle 4 while assuming that the
motorcycle 4 is traveling.
[0055] According to an aspect of the driving assistance device of
the disclosure, at a situation where the surrounding weather of the
subject vehicle 1 such as a bad weather may influence the detection
performance of the vehicle detection unit, in the vicinity of the
gateway of the tunnel-shaped structure, after the speed of the
subject vehicle 1 is reduced, when the detection environments are
improved and the preceding vehicle is thus detected, it is possible
to avoid the rapid speed reduction, as compared to a configuration
where the brake control is performed in one step without performing
the primary speed reduction control. As a result, it is possible to
achieve the effects of improving the ride quality of the subject
vehicle 1 and reducing the bad influence on the following
vehicle.
[0056] In an aspect of the driving assistance device of the
disclosure, a control amount of the primary speed reduction control
is preferably less than a control amount of the secondary speed
reduction control.
[0057] Also, in an aspect of the driving assistance device of the
disclosure, preferably, the primary speed reduction control is fuel
supply cut, and the secondary speed reduction control is brake
control. The brake control indicates speed reduction that is to be
performed using a brake device.
[0058] In this case, it is possible to approximate the ride quality
of the subject vehicle 1 to the speed reduction control that is to
be performed by a passenger, so that it is possible to achieve the
effects of further improving the ride quality of the subject
vehicle 1 and further reducing the bad influence on the following
vehicle.
[0059] Also, in an aspect of the driving assistance device of the
disclosure, the speed reduction control assistance unit preferably
enables the speed reduction control unit to perform the primary
speed reduction control and the secondary speed reduction control
when the vehicle detection unit detects a large-sized vehicle at
the entry-side of the tunnel 3. As shown in FIGS. 1A and 1B, even
though the motorcycle 4 is traveling at the rear of the large truck
5, the vehicle detection unit may not detect the motorcycle 4 due
to the deteriorated detection environments. For this reason, when
the large-sized vehicle is detected, the primary speed reduction
control of the subject vehicle 1 is performed in advance. Thereby,
the speed reduction necessary to secure the safe inter-vehicular
distance is performed in a stepwise manner, so that it is possible
to avoid the rapid speed reduction when the motorcycle 4 is
thereafter detected.
[0060] In the illustrative embodiment, the large-sized vehicle
indicates a vehicle of which a vehicle height is higher than a
saddle-ridden vehicle at a state where a passenger gets on the
saddle-ridden vehicle such as the motorcycle 4, for example. In
particular, the large-sized vehicle includes a vehicle that can
easily blow off droplets and the like on a traveling wind towards
the saddle-ridden vehicle from a luggage carrier, a cargo
compartment and the like of a truck, one box car and the like.
[0061] Also, in an aspect of the driving assistance device of the
disclosure, the speed reduction control assistance unit preferably
enables the speed reduction control unit to perform the primary
speed reduction control and the secondary speed reduction control
when the vehicle detection unit detects the motorcycle 4 in the
tunnel 3, at the exit-side of the tunnel 3 (refer to FIGS. 2A and
2B). Since the subject vehicle is not influenced by the bad weather
in the tunnel 3, the vehicle detection unit of the subject vehicle
1 (refer to FIGS. 1A, 1B, 2A and 2B) can detect the motorcycle 4
but may temporarily miss the motorcycle 4 due to the influence of
the bad weather in the vicinity of the exit of the tunnel 3. For
this reason, the primary speed reduction control of the subject
vehicle 1 is performed in advance. Thereby, the speed reduction
necessary to secure the safe inter-vehicular distance is performed
in a stepwise manner, so that it is possible to avoid the rapid
speed reduction when the motorcycle 4 is thereafter detected.
[0062] Also, in an aspect of the driving assistance device of the
disclosure, the driving assistance device preferably further
includes a notification unit that notifies a deceleration state of
the subject vehicle 1 to a following vehicle traveling at the rear
of the subject vehicle 1 when the speed reduction control
assistance unit enables the speed reduction control unit to perform
the primary speed reduction control. Thereby, it is possible to get
the attention of the following vehicle, so that it is possible to
suppress the following vehicle from making a hard stop when the
subject vehicle 1 performs the secondary speed reduction
control.
[0063] In the below, the illustrative embodiment of the disclosure
is described in more detail with reference to the drawings. First,
a configuration of a driving assistance device 100 of the
illustrative embodiment is described. FIG. 5 is a schematic
configuration view of a driving assistance device in accordance
with the illustrative embodiment. Meanwhile, the subject vehicle 1
(refer to FIGS. 1A to 4) to which the driving assistance device 100
is applied has the configurations (an engine, tires and the like)
that the automatic four-wheeled vehicle (the automatic driving
vehicle) normally has, and the descriptions thereof are omitted.
Also, in below descriptions, the preceding vehicle in front of the
subject vehicle 1 is described as the motorcycle 4 (refer to FIGS.
1A to 4).
[0064] The driving assistance device 100 (refer to FIG. 5) of the
illustrative embodiment includes a speed reduction control
assistance unit 101, a driving control unit (the speed reduction
control unit) 102 configured to control automatic driving of the
subject vehicle 1, a millimeter wave radar 103, a storage unit 104,
a GPS reception unit 105, a gyro sensor 106, an acceleration sensor
107, a vehicle speed sensor 108, a notification unit 109, a speed
reduction unit 110 and a raindrop amount sensor 111.
[0065] The speed reduction control assistance unit 101 and the
driving control unit 102 are provided in an ECU (Electronic Control
Unit) and are configured by a processor configured to execute a
variety of processing, for example.
[0066] The speed reduction control assistance unit 101 is
configured to output, to the driving control unit 102, a
determination result as to whether or not to reduce a speed of the
subject vehicle 1 on the basis of an output from the millimeter
wave radar 103, as driving assistance information.
[0067] The storage unit 104 is configured by one or more storage
media such as a ROM (Read Only Memory), a RAM (Random Access
Memory) and the like, depending on utilities. In the storage unit
104, information about the tunnel-shaped structure (which will be
described later) is stored.
[0068] The millimeter wave radar 103, which is an example of the
vehicle detection unit, is a radar system for front obstacle
detection using radio waves in millimeter waveband. The millimeter
wave radar 103 is provided at a front side of the subject vehicle 1
(refer to FIGS. 1A to 4), for example. The millimeter wave radar
103 is configured to illuminate millimeter wave radar ahead of the
subject vehicle 1, to receive reflected waves reflected on a
detection target by an antenna, to analyze the received reflected
waves, to calculate an inter-vehicular distance between the subject
vehicle and the preceding vehicle (the motorcycle 4), relative
speeds, azimuth angles and a size of the detection target, and to
output the same to the speed reduction control assistance unit
101.
[0069] The speed reduction control assistance unit 101 is
configured to determine whether the inter-vehicular distance
between the subject vehicle 1 and the preceding vehicle is equal to
or smaller than a predetermined value, based on the inter-vehicular
distance between the subject vehicle 1 and the preceding vehicle
input from the millimeter wave radar 103, and to output a
determination result thereof to the driving control unit 102, like
a general driving assistance control device.
[0070] Meanwhile, the predetermined value in the corresponding
determination indicates a distance within which the subject vehicle
1 (refer to FIGS. 1A to 4) under traveling can safely stop with
respect to the preceding vehicle at a stop. Herein, the safely
stoppable distance may be a value determined on the basis of a
traveling speed of the subject vehicle 1 or a value determined in
consideration of relative speeds (which can be measured by the
millimeter wave radar 103) of the subject vehicle 1 and the
preceding vehicle while assuming that the preceding vehicle (the
motorcycle 4) is traveling.
[0071] Also, the speed reduction control assistance unit 101 is
configured to determine whether a surrounding weather of the
subject vehicle 1 may influence detection performance of the
millimeter wave radar 103, based on an output of the raindrop
amount sensor 111.
[0072] The raindrop amount sensor 111 is configured to measure and
output an amount of raindrops attached to a front window of the
subject vehicle 1, for example. The raindrop amount sensor 111 has
a CCD camera, for example, and is configured to capture a
predetermined range of a surface of the front window, to recognize
and count raindrops from obtained image information and to output
the counted value, as a measurement result.
[0073] The weather that may influence the detection performance of
the millimeter wave radar 103 is a weather generally referred to as
a bad weather or a heavy weather. The bad weather includes heavy
rain, heavy snow, typhoon, dense fog, smog and the like.
[0074] The speed reduction control assistance unit 101 determines
that it is a bad weather when the amount of raindrops measured by
the raindrop amount sensor 111 is equal to or greater than a
predetermined value. The bad weather may be determined by
determining whether a cause of the raindrops is snow or not or
whether the rain is strongly blowing due to a strong wind such as
typhoon, in consideration of an output of a temperature sensor (not
shown) or a wind-force sensor (not shown), for example.
[0075] In the illustrative embodiment, the raindrop amount sensor
111 is used. However, other sensors can also be used. Also, the
example where the sensors are provided for the subject vehicle 1
has been described. However, the disclosure is not limited thereto.
For example, a wireless communication unit (not shown) may be
connected to the speed reduction control assistance unit 101, and
information about a weather of a place in which the subject vehicle
1 is traveling may be received from an external device of the
subject vehicle 1. The external device is a server connected to the
Internet and a weather observation facility equipped in the
vicinity of the road, for example.
[0076] Also, the speed reduction control assistance unit 101 is
configured to calculate a distance from the entry or exit of the
tunnel 3 to the subject vehicle 1 on the basis of a position of the
subject vehicle 1 output from the GPS reception unit 105 and the
information (which is stored in the storage unit 104) about the
road structure on the road 2 on which the subject vehicle 1
travels.
[0077] Based on a calculation result, the speed reduction control
assistance unit 101 is configured to determine whether the subject
vehicle is ahead of the predetermined distance from the entry or
exit of the tunnel 3.
[0078] The information about the road structure is information
(coordinates and the like) about a position of the road structure
included in map data including the road structure, for example.
[0079] The driving control unit 102 is configured to mainly execute
the automatic driving control of the subject vehicle 1, and to
accelerate, decelerate and steer the subject vehicle 1 on the basis
of outputs from the GPS reception unit 105, the gyro sensor 106,
the acceleration sensor 107 and the vehicle speed sensor 108 and
the map data stored in the storage unit.
[0080] The driving control unit 102 is configured to function as
the speed reduction control unit for enabling the speed reduction
unit 110 to reduce the speed of the subject vehicle 1 in accordance
with a determination result from the speed reduction control
assistance unit 101.
[0081] The driving control unit 102 is configured to enable the
notification unit 109 to issue a notification in accordance with an
output from the speed reduction control assistance unit 101.
[0082] The notification unit 109 is to notify a deceleration state
of the subject vehicle 1 to the following vehicle (not shown),
which travels at the rear of the subject vehicle 1 (refer to FIGS.
1A to 4). The notification unit 109 is a tail lamp of the subject
vehicle 1, for example, but is not particularly limited.
[0083] The speed reduction unit 110 is to reduce the speed of the
subject vehicle 1. As the speed reduction unit 110, a brake device
configured to brake rotations of wheels may be exemplified. In the
meantime, the speed reduction unit 110 is not limited to the brake
device that is to be operated in accordance with a direct operation
of a driver and includes a unit that is to be automatically
controlled by the ECU or the like, such as a regeneration brake of
a hybrid vehicle or an electric car, an engine brake associated
with shift transmission, and the like.
[0084] Also, the driving control unit 102 is configured to input an
output from the GPS reception unit 105 to the speed reduction
control assistance unit 101. The subject vehicle position
information from the GPS reception unit 105 is used to determine
whether the subject vehicle 1 is in the tunnel 3, in ST101 of FIG.
6 (which will be described later).
[0085] Subsequently, a control flow of the driving assistance
device of the illustrative embodiment is described. FIGS. 6 to 8
depict a control flow of the driving assistance device of the
illustrative embodiment.
[0086] First, the determination of the bad weather is described. As
shown in FIG. 6, the speed reduction control assistance unit 101
(refer to FIG. 5) determines whether the subject vehicle 1 is in
the tunnel 3 (refer to FIGS. 1A, 1B, 2A and 2B) (ST101). This
determination can be performed on the basis of the subject vehicle
position information (for example, coordinates) input from the GPS
reception unit 105 and the information (for example, coordinates of
the tunnel 3 of the map data) about the tunnel-shaped road
structure stored in the storage unit 104, for example. In addition,
the speed reduction control assistance unit 101 can determine
whether the subject vehicle is in the tunnel 3 by using the
information from an external device such as a beacon, an RFID tag
and the like, for example.
[0087] When a result of the determination in ST101 is YES, the
speed reduction control assistance unit 101 returns to ST101. On
the other hand, when a result of the determination in ST101 is NO,
the speed reduction control assistance unit 101 determines whether
an amount of raindrops attached on the front window and the like is
equal to or greater than a threshold value, based on the output
from the raindrop amount sensor 111 (ST102).
[0088] When a result of the determination in ST102 is YES, the
speed reduction control assistance unit 101 sets a bad weather flag
(which will be described later) stored in the storage unit 104 to
ON (ST103) and proceeds to ST105. On the other hand, when a result
of the determination in ST102 is NO, the speed reduction control
assistance unit 101 sets the bad weather flag to OFF (ST104) and
proceeds to ST105.
[0089] In ST105, the speed reduction control assistance unit 101
determines whether an engine is at an ON state, based on the output
from the driving control unit 102. When a result of the
determination in ST105 is YES, the speed reduction control
assistance unit 101 returns to ST101 and repeats the determination
as to the bad weather. When a result of the determination in ST105
is NO, the speed reduction control assistance unit 101 ends the
processing.
[0090] Thereby, when the engine is at the ON state, the
determination as to the bad weather is continuously performed, and
when the engine is at an OFF state, the determination as to the bad
weather is not performed. Also, when the subject vehicle 1 is in
the tunnel 3, the rewriting of the bad weather flag is not
performed.
[0091] Subsequently, processing that is to be performed by the
speed reduction control assistance unit 101 in the vicinity of the
entry of the tunnel 3 is described with reference to FIG. 7. First,
the speed reduction control assistance unit 101 (refer to FIG. 5)
determines whether the bad weather flag stored in the storage unit
104 is ON (ST201). When a result of the determination in ST201 is
NO, the speed reduction control assistance unit 101 proceeds to
ST210.
[0092] When a result of the determination in ST201 is YES, the
speed reduction control assistance unit 101 determines whether a
distance from the subject vehicle 1 to the entry of the tunnel 3
(refer to FIGS. 1A and 1B) is within the predetermined distance
(ST202). This determination can be performed on the basis of the
subject vehicle position information (for example, coordinates)
input from the GPS reception unit 105 and the information (for
example, coordinates of the tunnel 3 of the map data) about the
tunnel-shaped road structure stored in the storage unit 104, for
example. In the meantime, the predetermined distance has been
described above.
[0093] When a result of the determination in ST202 is NO, the speed
reduction control assistance unit 101 proceeds to ST210. On the
other hand, when a result of the determination in ST202 is YES, the
speed reduction control assistance unit 101 determines whether
there is a large-sized vehicle in front of the subject vehicle 1
(ST203). This determination can be performed on the basis of the
information of the size of the detection target included in the
output from the millimeter wave radar 103 (refer to FIG. 5), for
example. More specifically, when the size of the detection target
is greater than a size of the saddle-ridden vehicle stored in the
storage unit 104 and becoming a reference, the speed reduction
control assistance unit 101 determines that there is a large-sized
vehicle in front of the subject vehicle 1.
[0094] When a result of the determination in ST203 is NO, the speed
reduction control assistance unit 101 proceeds to ST210. On the
other hand, when a result of the determination in ST203 is YES, the
speed reduction control assistance unit 101 outputs the
determination result to the driving control unit 102, as the
driving assistance information, and enables the driving control
unit 102 to control the speed reduction unit 110 to perform the
fuel supply cut, as the primary speed reduction control (ST204).
Also, the speed reduction control assistance unit 101 enables the
driving control unit 102 to control the notification unit 109 to
turn on the brake lamp, for example (ST205).
[0095] Subsequently, the speed reduction control assistance unit
101 determines whether the millimeter wave radar 103 (refer to FIG.
5) has detected the motorcycle 4 (refer to FIGS. 1A and 1B)
(ST206). This determination can be performed on the basis of the
size of the detection target included in the output from the
millimeter wave radar 103, for example. When a result of the
determination in ST206 is NO, the speed reduction control
assistance unit 101 proceeds to ST210. On the other hand, when a
result of the determination in ST206 is YES, the speed reduction
control assistance unit 101 determines whether the inter-vehicular
distance between the subject vehicle 1 and the motorcycle 4 is
equal to or smaller than the predetermined value (ST207). This
determination is performed on the basis of the inter-vehicular
distance output from the millimeter wave radar 103.
[0096] When a result of the determination in ST207 is NO, the speed
reduction control assistance unit 101 proceeds to ST210. On the
other hand, when a result of the determination in ST207 is YES, the
speed reduction control assistance unit 101 outputs the
determination result to the driving control unit 102, as the
driving assistance information. Thereby, the speed reduction
control assistance unit 101 enables the driving control unit 102 to
control the speed reduction unit 110 to perform the brake control,
as the secondary speed reduction control (ST208). As a result, the
subject vehicle 1 (refer to FIGS. 1A and 1B) reduces the speed so
as to avoid the contact with the motorcycle 4. Also, the speed
reduction control assistance unit 101 enables the driving control
unit 102 to control the notification unit 109 to turn on the brake
lamp, for example (ST209).
[0097] Continuously to ST209 and when the results of the
determinations in ST201 to ST203, ST206 and ST207 are NO, the speed
reduction control assistance unit 101 determines whether the engine
is at the ON state, based on the output from the driving control
unit 102 (ST210). When a result of the determination in ST210 is
YES, the speed reduction control assistance unit 101 returns to
ST201. On the other hand, when a result of the determination in
ST210 is NO, the speed reduction control assistance unit 101 ends
the processing. Thereby, when the engine is at the ON state, the
processing of ST201 to ST209 is continuously performed at the
entry-side of the tunnel 3, and when the engine is at the OFF
state, the processing is over.
[0098] Subsequently, processing that is to be performed by the
speed reduction control assistance unit 101 in the vicinity of the
exit of the tunnel 3 is described with reference to FIG. 8. The
same processing as the processing of the speed reduction control
assistance unit 101 in the vicinity of the entry of the tunnel 3,
which has been described with reference to FIG. 7, are simply
described.
[0099] First, the speed reduction control assistance unit 101
(refer to FIG. 5) determines whether the bad weather flag stored in
the storage unit 104 is ON (ST301). When a result of the
determination in ST301 is NO, the speed reduction control
assistance unit 101 proceeds to ST311.
[0100] When a result of the determination in ST301 is YES, the
speed reduction control assistance unit 101 determines whether a
distance to the exit of the tunnel 3 (refer to FIGS. 2A and 2B) is
within the predetermined distance (ST302).
[0101] When a result of the determination in ST302 is NO, the speed
reduction control assistance unit 101 proceeds to ST311. On the
other hand, when a result of the determination in ST302 is YES, the
speed reduction control assistance unit 101 determines whether
there is the motorcycle 4 (refer to FIGS. 2A and 2B) in front of
the subject vehicle 1 (ST303).
[0102] When a result of the determination in ST303 is NO, the speed
reduction control assistance unit 101 proceeds to ST311. On the
other hand, when a result of the determination in ST303 is YES, the
speed reduction control assistance unit 101 (refer to FIG. 5)
outputs the determination result to the driving control unit 102,
as the driving assistance information, and enables the driving
control unit 102 to control the speed reduction unit 110 to perform
the fuel supply cut, as the primary speed reduction control
(ST304). Also, the speed reduction control assistance unit 101
enables the driving control unit 102 to control the notification
unit 109 to turn on the brake lamp, for example (ST305).
[0103] Subsequently, the speed reduction control assistance unit
101 determines whether the millimeter wave radar 103 did not detect
the motorcycle 4 (refer to FIGS. 2A and 2B), i.e., whether the
motorcycle 4 is missed (ST306). When a result of the determination
in ST306 is NO, the speed reduction control assistance unit 101
proceeds to ST308.
[0104] On the other hand, when a result of the determination in
ST306 is YES, the speed reduction control assistance unit 101
determines whether the millimeter wave radar 103 has again detected
the motorcycle 4 (ST307). That is, when the millimeter wave radar
103 cannot detect the motorcycle 4, which could be detected in the
tunnel 3, due to the deterioration of the detection environments in
the vicinity of the exit of the tunnel 3, the speed reduction
control assistance unit 101 determines whether the motorcycle 4 can
be again detected as the subject vehicle 1 gets out of the tunnel
3.
[0105] When a result of the determination in ST307 is NO, the speed
reduction control assistance unit 101 proceeds to ST311. On the
other hand, when a result of the determination in ST307 is YES, the
speed reduction control assistance unit 101 determines whether the
inter-vehicular distance between the subject vehicle 1 and the
motorcycle 4 is equal to or smaller than the predetermined value
(ST308). This determination is performed on the basis of the
inter-vehicular distance output from the millimeter wave radar
103.
[0106] When a result of the determination in ST308 is NO, the speed
reduction control assistance unit 101 proceeds to ST311. On the
other hand, when a result of the determination in ST308 is YES, the
speed reduction control assistance unit 101 outputs the
determination result to the driving control unit 102, as the
driving assistance information. Thereby, the speed reduction
control assistance unit 101 enables the driving control unit 102 to
control the speed reduction unit 110 to perform the brake control,
as the secondary speed reduction control (ST309). As a result, the
subject vehicle 1 (refer to FIGS. 2A and 2B) reduces the speed so
as to avoid the contact with the motorcycle 4. Also, the speed
reduction control assistance unit 101 enables the driving control
unit 102 to control the notification unit 109 to turn on the brake
lamp, for example (ST310).
[0107] Continuously to ST310 and when the results of the
determinations in ST301 to ST303, ST307 and ST308 are NO, the speed
reduction control assistance unit 101 determines whether the engine
is at the ON state, based on the output from the driving control
unit 102 (ST311). When a result of the determination in ST311 is
YES, the speed reduction control assistance unit 101 returns to
ST301. On the other hand, when a result of the determination in
ST311 is NO, the speed reduction control assistance unit 101 ends
the processing. Thereby, when the engine is at the ON state, the
processing of ST301 to ST310 is continuously performed at the
exit-side of the tunnel 3, and when the engine is at the OFF state,
the processing is over.
[0108] In FIGS. 6 to 8, the sequence of the processing is simply
exemplary and one skilled in the art can appropriately change the
sequence of the processing. For example, the brake control of ST208
in FIG. 7 and the lighting of the brake lamp of ST209 in FIG. 7 may
be performed in a reverse sequence and may be performed in parallel
at the same time.
[0109] As described above, according to the illustrative
embodiment, at the entry-side of the tunnel 3 (refer to FIGS. 1A
and 1B), the fuel supply cut (ST204 in FIG. 7) is performed as the
primary speed reduction control (the minor speed reduction
processing), on condition that it is the bad weather (a result of
the determination in ST201 of FIG. 7 is YES), the position of the
subject vehicle 1 is ahead of the predetermined distance from the
entry of the tunnel 3 (a result of the determination in ST202 of
FIG. 7 is YES) and the large-sized vehicle is in front of the
subject vehicle 1 (a result of the determination in ST203 of FIG. 7
is YES). Thereby, after the speed of the subject vehicle 1 is
slightly reduced, when the subject vehicle 1 enters the tunnel 3,
the detection environments by the millimeter wave radar 103 are
improved and the motorcycle 4 is detected (a result of the
determination in ST206 of FIG. 7 is YES), it is possible to avoid
the rapid speed reduction, as compared to a configuration where the
brake control is performed in one step without performing the
primary speed reduction control. As a result, it is possible to
improve the ride quality of the subject vehicle 1 and to reduce the
bad influence on the following vehicle.
[0110] In the meantime, at the exit-side of the tunnel 3 (refer to
FIGS. 2A and 2B), the fuel supply cut (ST304 in FIG. 8) is
performed as the primary speed reduction control (the minor speed
reduction processing), on condition that it is the bad weather (a
result of the determination in ST301 of FIG. 8 is YES) before the
subject vehicle enters the tunnel 3, the position of the subject
vehicle is ahead of the predetermined distance to the exit of the
tunnel 3 (a result of the determination in ST302 of FIG. 8 is YES)
and the motorcycle 4 is in front of the subject vehicle 1 in the
tunnel 3 (a result of the determination in ST303 of FIG. 8 is YES).
Thereby, after the speed of the subject vehicle 1 is slightly
reduced, when the subject vehicle 1 comes close to the exit of the
tunnel 3, the detection environments by the millimeter wave radar
103 are deteriorated due to the bad weather and the motorcycle 4 is
missed (a result of the determination in ST306 of FIG. 8 is YES)
and is then detected (a result of the determination in ST307 of
FIG. 8 is YES), it is possible to avoid the rapid speed reduction,
as compared to a configuration where the brake control is performed
in one step without performing the primary speed reduction control.
As a result, it is possible to improve the ride quality of the
subject vehicle 1 and to reduce the bad influence on the following
vehicle.
[0111] Like this, according to the driving assistance device 100
(refer to FIG. 5) of the illustrative embodiment, when the
overlooked motorcycle 4 is detected and when the motorcycle 4
temporarily missed is again detected in the vicinity of the gateway
of the tunnel 3, it is possible to prevent the rapid speed
reduction control of the subject vehicle 1. Thereby, it is possible
to prevent the ride quality of the subject vehicle 1, which is an
automatic driving vehicle, from being deteriorated. Also, it is
possible to reduce the bad influence of the subject vehicle 1 on
the following vehicle, thereby preventing the subject vehicle from
becoming an origination of a traffic jam.
[0112] Also, in the illustrative embodiment, while performing the
primary speed reduction control, the deceleration state of the
subject vehicle 1 is notified to the following vehicle by the
lighting (ST205 in FIG. 7, ST305 in FIG. 8) of the brake lamp,
which is an example of the notification unit 109. Thereby, it is
possible to get the attention of the following vehicle, so that it
is possible to suppress the following vehicle from making a hard
stop when the subject vehicle 1 performs the secondary speed
reduction control. Therefore, it is possible to further reduce the
bad influence on the following vehicle.
[0113] In the meantime, the disclosure is not limited to the
illustrative embodiment and can be diversely changed and
implemented. In the illustrative embodiment, the sizes, shapes and
the like shown in the accompanying drawings are not limited thereto
and can be appropriately changed within the scope in which the
effects of the disclosure are to be accomplished. In addition, the
illustrative embodiment can be appropriately changed and
implemented without departing from the object of the
disclosure.
[0114] For example, in the illustrative embodiment, only when it is
determined in ST203 of FIG. 7 that the large-sized vehicle exists
in front of the subject vehicle, the primary speed reduction
control (ST204 in FIG. 7) is performed. However, the primary speed
reduction control may be performed, irrespective of whether there
is the large-sized vehicle.
[0115] Also, in the illustrative embodiment, the millimeter wave
radar 103 (refer to FIG. 5) has been exemplified as the vehicle
detection unit. However, the vehicle detection unit is not
particularly limited, and a detection unit configured to use the
reflected waves, such as an infrared radar, an ultrasonic radar and
the like, and a camera such as a CCD camera, an infrared camera and
the like can also be applied.
[0116] Also, in the illustrative embodiment, the tunnel 3 has been
exemplified. However, the disclosure can also be applied to the
other tunnel-shaped road structure, such as a space below an
elevated bridge including a highway, a railroad and the like.
[0117] Also, in the illustrative embodiment, as the determination
condition as to whether or not to perform the primary speed
reduction control, the condition whether the subject vehicle 1 is
positioned at the predetermined distance ahead of the entry or the
exit of the tunnel 3 (refer to FIGS. 1A, 1B, 2A and 2B) is adopted
(refer to ST202 in FIG. 7 and ST302 in FIG. 8). Instead, a
determination condition whether a distance from the subject vehicle
1 to the entry or exit of the tunnel 3 is within a predetermined
range may be adopted.
[0118] Herein, the predetermined range is a range from a
predetermined position ahead of the entry of the tunnel 3 (refer to
FIGS. 1A and 1B) to the entry of the tunnel 3, for example. In
other words, when a predetermined distance is denoted with Xm and a
front of the tunnel 3 is denoted with minus and an inner side of
the tunnel 3 is denoted with plus on the basis of the entry of the
tunnel 3 (which is a starting point (an origin)), the predetermined
range is a range from -Xm to 0m. In the meantime, the predetermined
distance is the same as the illustrative embodiment. Also, only an
arbitrary distance (Ym) from the entry of the tunnel 3 may be set
to the range to the inner side, and a range from -Xm to +Ym may be
set.
[0119] The above is the same as the exit-side of the tunnel 3. In
this case, the predetermined range is a range from a predetermined
position ahead of the exit of the tunnel 3 (refer to FIGS. 2A and
2B) to the exit of the tunnel 3, for example. In other words, when
a predetermined distance is denoted with X'm and a front of the
tunnel 3 (i.e., the inner side of the tunnel 3) is denoted with
minus and an outer side of the tunnel 3 is denoted with plus on the
basis of the exit of the tunnel 3 (which is a starting point (an
origin)), the predetermined range is a range from -X'm to 0m. Also,
only an arbitrary distance (Y'm) from the exit of the tunnel 3 may
be set to the range to the outer side, and a range from -X'm to
+Y'm may be set.
[0120] As described above, the disclosure accomplishes the effects
of preventing the subject vehicle from making a hard stop by the
driving assistance device when the vehicle detection unit overlooks
or temporarily misses the preceding vehicle due to the bad weather
and the like and then again detects the preceding vehicle in the
vicinity of the gateway of the tunnel-shaped structure, thereby
improving the ride quality and reducing the bad influence on the
following vehicle. In particular, the disclosure can be usefully
applied to the driving assistance device of the automatic driving
vehicle.
* * * * *