JP7600938B2 - Driving Support Devices - Google Patents

Description

The present invention relates to a driving assistance device that alerts the driver of a vehicle to traffic lights.

Driving assistance devices that issue the above-mentioned warnings have been known for some time. Such driving assistance devices detect traffic lights in front of the vehicle based on camera images acquired by a camera device capturing an image of the area in front of the vehicle.

For example, the driving assistance device described in Patent Document 1 (hereinafter, "conventional device") issues a warning if it does not detect a traffic light's arrow and the traffic light's main light displays a stop signal (yellow or red) instructing the vehicle to stop. If the conventional device detects an arrow and the main light displays a stop signal and the permitted direction does not match the future traveling direction, it issues a warning.

The permitted direction is the direction in which the arrow light permits the vehicle to travel, and is the direction indicated by the arrow signal displayed by the arrow light.
The future heading is the direction in which the vehicle will travel in the future, and is determined, for example, based on the direction of directional road markings on the lane in which the vehicle is traveling. The directional road markings indicate the direction in which the lane allows the vehicle to travel.

JP 2021-047565 A

When there is a preceding vehicle ahead of the vehicle, the camera device is blocked by the preceding vehicle and cannot capture the traffic light, so the conventional device may not be able to detect the traffic light even if the traffic light is equipped with one. In this case, the conventional device will issue a warning if the main light is displaying a stop signal. For this reason, even if the permitted direction and future traveling direction match (even if a warning should not be issued), the conventional device may issue a warning. A warning issued erroneously may be annoying to the driver.

The present invention has been made to address the above-mentioned problems. That is, one of the objectives of the present invention is to provide a driving assistance device that can reduce the possibility that a driver will find a warning annoying by reducing the possibility that the warning will be issued erroneously.

The driving assistance device of the present invention (hereinafter also referred to as the "device of the present invention") alerts the driver of the vehicle (VA) to a traffic light (TL) detected based on a camera image acquired by a camera device (21) that photographs the area in front of the vehicle (VA).
The device of the present invention comprises:
When there is no preceding vehicle (VB) located in front of the vehicle (step 430 “No”, step 465 “No”),
A first condition is that the main light of the traffic signal is displaying a stop signal instructing the vehicle to stop (step 425 “Yes”), and no arrow light is detected below the main light (step 435 “No”); and
A second condition is that the main light unit is displaying the stop signal (step 425 “Yes”), the arrow light unit is detected (step 435 “Yes”), and the permitted direction in which the arrow light unit permits the vehicle to travel does not match the future travel direction in which the vehicle is estimated to travel in the future (step 455 “No”).
If any of the above is true, the warning is issued (step 440, step 515),
If the preceding vehicle is present (step 430 “Yes”, step 465 “Yes”), the warning is prohibited.
It is structured as follows.

The device of the present invention prohibits warnings when there is a preceding vehicle. This prevents accidental warnings from being issued due to traffic lights not being detected because they are blocked by a preceding vehicle, even if the traffic light is equipped with a warning light. This reduces the possibility that the driver will find the warnings annoying.

In one embodiment of the device of the present invention,
If the vehicle distance (Dv) between the vehicle and another vehicle located ahead of the vehicle is longer than a predetermined threshold distance (Dvth) (step 465 "No"), it is determined that the preceding vehicle does not exist,
If the vehicle distance is equal to or less than the threshold distance (step 465 "Yes"), it is determined that the preceding vehicle is present.
It is structured as follows.

If the distance between the vehicles is longer than the threshold distance, the camera device can capture the arrow light without being blocked by the preceding vehicle, and there is a high possibility that the arrow light will be detected. According to this aspect, even if there is another vehicle in front of the vehicle, if the distance between the vehicles is longer than the threshold distance, the other vehicle will not be detected as a preceding vehicle, and a warning will be issued if either the first condition or the second condition is met. This increases the likelihood that a warning will be issued in a situation where a warning should be issued, even if there is another vehicle.

In one embodiment of the device of the present invention,
When the preceding vehicle is present (step 430 “Yes” shown in FIG. 7 , step 465 “Yes” shown in FIG. 7 ), and the length (H) between the upper end (UE) of the preceding vehicle and the lower end (BE) of the main light unit is equal to or longer than a predetermined threshold length (Hth) (step 720 “No”), the warning is issued when either the first condition or the second condition is satisfied.
If the preceding vehicle is present (step 430 “Yes” shown in FIG. 7 , step 465 “Yes” shown in FIG. 7 ) and the length is less than the threshold length (step 720 “Yes”), the warning is prohibited.
It is structured as follows.

If the length between the top of the preceding vehicle and the bottom of the main light is equal to or greater than the threshold length, there is a high possibility that the arrow light will be detected if the traffic light is equipped with an arrow light. According to this aspect, even if there is a preceding vehicle, if the length is equal to or greater than the threshold length, a warning is issued when either the first condition or the second condition is met, and if the length is less than the threshold length, warning is prohibited. This increases the likelihood that a warning will be issued in a situation where a warning should be issued, even if there is a preceding vehicle.

In one embodiment of the device of the present invention,
The vehicle is configured to determine the future direction of travel based on the direction in which the lane in which the vehicle is currently traveling allows the vehicle to travel and the indication direction of the turn signals (33L, 33R) of the vehicle.

This method allows the future direction of travel to be determined accurately, reducing the possibility of an erroneous warning being issued.

In the above description, in order to facilitate understanding of the invention, the names and/or symbols used in the embodiments described below are enclosed in parentheses with respect to the configuration of the invention corresponding to the embodiment. However, each component of the invention is not limited to the embodiment defined by the above names and/or symbols.

FIG. 1 is a schematic system configuration diagram of a driving assistance device according to an embodiment of the present invention. FIG. 2 is a plan view of a road near an intersection. FIG. 3 is a diagram illustrating an outline of an embodiment of the present invention. FIG. 4 is a flowchart showing an attention-call start determination routine executed by the CPU of the driving assistance ECU shown in FIG. FIG. 5 is a flowchart showing a warning routine executed by the CPU of the driving assistance ECU shown in FIG. FIG. 6 is a schematic explanatory diagram of a first modified example of the embodiment of the present invention. FIG. 7 is a flowchart showing a part of an attention-call start determination routine executed by the CPU of the driving assistance ECU according to the first modified example of the embodiment of the present invention.

<Configuration>
As shown in FIG. 1, a driving assistance device (hereinafter, referred to as "this assistance device") 10 according to an embodiment of the present invention is mounted on a vehicle VA.

The assistance device 10 is equipped with a driving assistance ECU 20 (hereinafter referred to as "DSECU 20").

An ECU is a control unit (Electronic Control Unit) that includes a microcomputer as its main component, and is sometimes referred to as a "controller." The microcomputer includes a CPU, ROM, RAM, and an interface (I/F), etc. These ECUs are connected to each other via a Controller Area Network (CAN) so that they can exchange data with each other. The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. The functions of this ECU may be distributed among multiple ECUs.

The support device 10 includes a wheel speed sensor 21, a camera device 22, a millimeter wave radar device 23, a brake operation amount sensor 24, a yaw rate sensor 25, a turn signal lever 26, a speaker 31, a display 32, a left turn signal 33L, and a right turn signal 33R. These are connected to the DSECU 20 so as to be able to exchange data.

A wheel speed sensor 21 is provided for each wheel of the vehicle VA. Each wheel speed sensor 21 generates one wheel pulse signal each time the corresponding wheel rotates a predetermined angle. The DSECU 20 counts the number of pulses per unit time of the wheel pulse signal received from each wheel speed sensor 21, and obtains the rotational speed of each wheel based on the number of pulses. The DSECU 20 then obtains a vehicle speed Vs indicating the speed of the vehicle VA based on the wheel speed of each wheel. As an example, the DSECU 20 obtains the average value of the wheel speeds of the four wheels as the vehicle speed Vs.

The camera device 22 is disposed at the top center of the front window inside the vehicle VA. The camera device 22 acquires an image (hereinafter also referred to as a "camera image") of a predetermined area in front of the vehicle VA every time a predetermined time elapses, and transmits the camera image to the driving assistance ECU 20.

The millimeter-wave radar device 23 transmits millimeter waves ahead of the vehicle VA. The millimeter-wave radar device 23 is a well-known sensor that detects objects by receiving millimeter waves (reflected waves) reflected by the object. Based on the received reflected waves, the millimeter-wave radar device 23 obtains the distance to the object (object distance), the object's relative speed (object relative speed) Vr with respect to the vehicle VA, and the object's direction. Then, every time a predetermined time elapses, the millimeter-wave radar device 23 transmits "radar object information including the object distance, object relative speed Vr, and object direction" to the DSECU 20.

The brake operation amount sensor 24 detects the amount of operation of the brake pedal (not shown) of the vehicle VA (i.e., the brake pedal operation amount BP) and generates a detection signal representing the brake pedal operation amount BP. Note that the support device 10 may be provided with a brake switch that detects whether or not the brake pedal is being operated instead of the brake operation amount sensor 24.

The yaw rate sensor 25 detects the yaw rate of the vehicle VA and generates a detection signal representing the yaw rate. The sign of the yaw rate determines whether the yaw rate is in the left or right direction.

The turn signal lever 26 is disposed near a steering wheel (not shown). When the driver operates the turn signal lever 26 in a left blinking direction (e.g., upward), the left turn signal 33L blinks. When the driver operates the turn signal lever 26 in a right blinking direction (e.g., downward), the right turn signal 33R blinks.

The speaker 31 is disposed within the passenger compartment of the vehicle VA and emits a buzzer sound in response to an attention-attracting command from the driving assistance ECU 20 .
The display 32 is disposed in a position inside the vehicle VA that is "visible to the driver seated in the driver's seat."

The detection process based on the camera image performed by the driving assistance ECU 20 will be described with reference to FIG. 2. In the detection process, the DSECU 20 detects traffic lights TL, white lines WL, and other vehicles.

<Detection of Traffic Light TL>
The DSECU 20 detects a traffic light TL present ahead of the vehicle VA based on the camera image. More specifically, the DSECU 20 detects a main light ML of the traffic light TL that is disposed opposite the vehicle VA at the intersection CP where the vehicle VA is about to enter.

The DSECU 20 identifies (detects) whether the main light ML of the traffic light TL is displaying a green signal B, a yellow signal Y, or a red signal R, based on the camera image. If the main light ML is displaying a yellow signal Y or a red signal R, the main light ML is instructing the vehicle VA to stop. The yellow signal Y and the red signal R may be referred to as "stop signals." The green signal B may be referred to as "permission signal."

When the DSECU 20 detects the arrow light AL of the traffic light TL based on the camera image, it detects the direction of the arrow signal displayed by the arrow light AL (left arrow signal LL, straight arrow signal SL, right arrow signal RL). The direction of this arrow signal is the direction in which the vehicle VA is permitted to travel.

Furthermore, the DSECU 20 detects the relative position (direction and distance) of the traffic light TL with respect to the vehicle VA based on the camera image.

<Recognition of white lines WL>
The DSECU 20 detects white lines WL (lane dividing lines) on the road based on the camera image, and identifies the relative position of the white lines WL with respect to the vehicle VA.
Based on the relative positions of the white lines WL, the DSECU 20 identifies the white line WL located on the left side of the vehicle VA and closest to the vehicle VA as the left white line LWL. Similarly, based on the relative positions of the white lines WL, the DSECU 20 identifies the white line WL located on the right side of the vehicle VA and closest to the vehicle VA as the right white line RWL. Then, the DSECU 20 identifies the lane divided by the left white line LWL and the right white line RWR as the driving lane LA in which the vehicle VA is currently traveling.

Furthermore, the DSECU 20 detects road markings D based on the camera image. The road markings D include a stop line SD provided just before the intersection CP, and a directional road marking AD that indicates with an arrow the direction in which the vehicle VA can proceed (the direction in which the vehicle VA is permitted to proceed). Note that the arrow indicated by the directional road marking AD may indicate not only one direction but also two directions.

Furthermore, the DSECU 20 determines the distance from the vehicle VA to the stop line SD of the driving lane LA. Furthermore, the DSECU 20 determines the direction permitted by the driving lane LA based on the directional road marking AD of the driving lane LA. Since the vehicle VA is highly likely to travel in the direction of the directional road marking AD, the direction of the directional road marking AD is also expressed as the "future travel direction, which is the future travel direction of the vehicle VA."

The DSECU 20 also detects other vehicles based on the camera images and identifies the relative positions of the other vehicles with respect to the vehicle VA (the distance to the other vehicles and the direction of the other vehicles).The DSECU 20 then determines the relative positions of the other vehicles with respect to the vehicle VA based on the identified relative positions and the radar object information.

＜Caution＞
When either the first or second condition below is satisfied, the DSECU 20 determines that the start condition is satisfied and issues a warning. Specifically, the DSECU 20 transmits an attention warning command to the speaker 31 to cause the speaker 31 to emit a buzzer sound.

First condition: the main light ML displays a stop signal and the DSECU 20 does not detect the arrow light AL.
Second condition: The main light unit ML displays a stop signal, the DSECU 20 detects the arrow light unit AL, and the direction of the arrow signal displayed on the arrow light unit AL (permitted direction) does not match the direction of the directional road marking AD (future travel direction).

When the arrow light AL displays multiple arrow signals, if the future travel direction does not match any of the directions of these arrow signals (permitted directions), the DSECU 20 determines that the permitted direction does not match the future travel direction. When the directional road marking AD displays multiple arrows, if the permitted direction does not match any of the directions of these arrows (future travel direction), the DSECU 20 determines that the permitted direction does not match the future travel direction.

In the example shown in FIG. 2, the main light ML displays a red signal R, and the DSECU 20 detects the arrow light AL. Furthermore, the arrow light AL displays a left arrow signal LL (i.e., the permitted direction is to the left), and the directional road marking AD of the travel lane LA is a straight-ahead direction (the future travel direction is a straight-ahead direction), so the permitted direction and the future travel direction do not match. Therefore, the DSECU 20 issues a warning because the second condition is met.

<Outline of operation>
An outline of the operation of the DSECU 20 of the device 10 of the present invention will now be described with reference to FIG.
When a preceding vehicle VB is present in front of the vehicle VA, the camera device 22 may be unable to capture the arrow light AL disposed below the main light ML because the arrow light AL is blocked by the preceding vehicle VB. In this case, the camera image does not include an image of the arrow light AL, so the DSECU 20 cannot detect the arrow light AL. Therefore, if the main light ML is displaying a stop signal, the first condition is met and the DSECU 20 issues a warning.

Even if the direction of the arrow signal displayed by an arrow light AL that is not detected by the DSECU20 (i.e., the permitted direction) matches the future traveling direction, the DSECU20 may erroneously issue a warning.

Therefore, in this embodiment, the DSECU 20 prohibits a warning when a preceding vehicle VB is present ahead of the vehicle VA. This reduces the possibility of a warning being issued erroneously even in a situation where a warning is likely to be issued erroneously due to the presence of the preceding vehicle VB.

(Specific operation)
<Caution start determination routine>
The CPU of the DSECU 20 (hereinafter, when the term "CPU" is used, it refers to the CPU of the DSECU 20 unless otherwise specified) executes a warning start determination routine shown in the flowchart of FIG. 4 every time a predetermined time has elapsed.

Therefore, at a predetermined timing, the CPU starts processing from step 400 in FIG. 4 and proceeds to step 405. In step 405, the CPU determines whether the value of the execution flag Xexe is "0".

The value of the execution flag Xexe is set to "1" when either the first condition or the second condition is met (i.e., when the start condition is met), and is set to "0" when the end condition described below is met. The value of the execution flag Xexe is also set to "0" in the initial routine. The initial routine is a routine executed by the CPU when the ignition key switch (not shown) of the vehicle VA is changed from the off position to the on position.

If the value of the execution flag Xexe is "0", the CPU judges "Yes" in step 405 and executes steps 410 to 420 in order.
Step 410 : The CPU acquires a camera image from the camera device 22 .
Step 415: The CPU acquires radar object information from the millimeter wave radar device 23.
Step 420: The CPU determines whether or not a traffic light TL exists based on the camera image.
If no traffic light TL is present, the CPU makes a "No" determination in step 420, proceeds to step 495, and temporarily ends this routine.

On the other hand, if a traffic light TL is present when the CPU proceeds to step 420, the CPU determines "Yes" in step 420 and proceeds to step 425. In step 425, the CPU determines whether or not the main light unit ML of the traffic light TL is displaying a stop signal.
If the main light unit ML is not displaying a stop signal, the CPU judges "No" in step 425, proceeds to step 495, and temporarily ends this routine.

On the other hand, if the main light ML is displaying a stop signal when the CPU proceeds to step 425, the CPU judges "Yes" in step 425 and proceeds to step 430. In step 430, the CPU determines whether or not another vehicle is present in front of the vehicle VA.

If there is no vehicle ahead of vehicle VA, the CPU determines "No" in step 430 and proceeds to step 435. In step 435, the CPU determines whether or not an arrow light AL is detected below the main light ML in the camera image.

If the arrow light AL is not detected, the CPU determines "No" in step 435 and proceeds to step 440. In step 440, the CPU determines whether the brake pedal operation amount BP is equal to or less than a predetermined threshold operation amount BPth.

If the brake pedal operation amount BP is equal to or less than the threshold operation amount BPth, the CPU determines that the driver has not depressed the brake pedal to stop the vehicle VA before the traffic light TL. In other words, the CPU determines that the driver does not intend to decelerate in order to stop the vehicle VA before the traffic light TL. In this case, the CPU determines that the first condition is satisfied. Then, the CPU determines "Yes" in step 440 and proceeds to step 445, where it sets the value of the execution flag Xexe to "1". After that, the CPU proceeds to step 495 and temporarily ends this routine.
In this routine, each of the first and second conditions further includes a condition that the brake pedal operation amount BP is equal to or less than a threshold operation amount BPth.

On the other hand, if the brake pedal operation amount BP is greater than the threshold operation amount BPth, the CPU determines that the driver intends to decelerate. In this case, the CPU determines "No" in step 440, proceeds to step 495, and temporarily ends this routine.

On the other hand, if the arrow light AL is detected when the CPU proceeds to step 435, the CPU judges "Yes" in step 435 and executes steps 450 to 460 in order.
Step 450: The CPU identifies the permitted direction based on the arrow signal displayed by the arrow light AL.
Step 455: The CPU determines the future direction of travel based on the directional road marking AD.
Step 460: The CPU determines whether or not the permitted direction and the future traveling direction match.

If the permitted direction and the future traveling direction do not match, the CPU determines "No" in step 460 and proceeds to step 440. If the brake pedal operation amount BP is equal to or less than the threshold operation amount BPth, the CPU determines that the second condition is met. Then, the CPU determines "Yes" in step 440 and sets the value of the execution flag Xexe to "1" in step 445. After that, the CPU proceeds to step 495 and temporarily ends this routine.

If the permitted direction and the future travel direction match when the CPU proceeds to step 460, the CPU judges "Yes" in step 460, proceeds to step 495, and temporarily ends this routine.

If there is another vehicle ahead of vehicle VA when the CPU proceeds to step 430, the CPU judges "Yes" at step 430 and proceeds to step 465. At step 435, the CPU identifies the inter-vehicle distance Dv between vehicle VA and the other vehicle, and determines whether the inter-vehicle distance Dv is equal to or less than a predetermined threshold distance Dvth.

If the vehicle distance Dv is longer than the threshold distance Dvth, the CPU does not detect another vehicle in front of the vehicle VA as the preceding vehicle VB (i.e., it determines that the preceding vehicle VB does not exist). In this case, the CPU determines "No" in step 465 and executes the processing from step 435 onwards. Therefore, if either the first condition or the second condition is met, the value of the execution flag Xexe is set to "1".

On the other hand, if the vehicle distance Dv is equal to or less than the threshold distance Dvth, the CPU detects another vehicle in front of the vehicle VA as the preceding vehicle VB (i.e., determines that the preceding vehicle VB is present). In this case, the CPU determines "Yes" in step 465, proceeds to step 495, and temporarily ends this routine. Therefore, if the preceding vehicle VB is detected, the value of the execution flag Xexe is not set to "1", so the CPU does not issue a warning (i.e., prohibits warning) even if either the first condition or the second condition is met.

If the value of the execution flag Xexe is "1" when the CPU proceeds to step 405, the CPU determines "No" in step 405, proceeds to step 495, and temporarily ends this routine.

<Attention routine>
The CPU executes a warning routine shown in the flowchart of FIG. 5 every time a predetermined time elapses.

Therefore, at a predetermined timing, the CPU starts processing from step 500 in FIG. 5 and proceeds to step 505. In step 505, the CPU determines whether the value of the execution flag Xexe is "1".

If the value of the execution flag Xexe is "0", the CPU judges "No" in step 505 and proceeds to step 595 to temporarily end this routine.

If the value of the execution flag Xexe is "1", the CPU determines "Yes" in step 505 and proceeds to step 510. In step 510, the CPU determines whether a predetermined termination condition is met by meeting at least one of the following conditions 1 to 5:

Condition 1: The CPU no longer detects the traffic light TL that was detected when either the first condition or the second condition was satisfied.
Condition 2: The distance traveled by the vehicle VA from the time the warning was initiated has exceeded a predetermined distance.
Condition 3: The vehicle VA makes a right turn or a left turn (hereinafter referred to as a "right/left turn").
Condition 4: The vehicle VA has stopped.
Condition 5: The main light unit ML starts displaying the green signal B.

Condition 1
The CPU acquires a new camera image, and if the camera image does not include an image of the traffic light TL, determines that condition 1 is satisfied.
Condition 2
The CPU determines the distance traveled by the vehicle VA based on the number of wheel pulse signals generated by the wheel speed sensor 21 from the time when the attention warning is started, and determines whether the distance traveled has reached or exceeded a predetermined distance.
Condition 3
The CPU determines the yaw rate based on the detection signal from the yaw rate sensor 25, and if the magnitude of the yaw rate is equal to or greater than a predetermined value, determines that the vehicle VA has made a right or left turn.

Condition 4
The CPU determines whether the vehicle VA has stopped based on the vehicle speed Vs determined based on the wheel pulse signal from the wheel speed sensor 21.
Condition 5
The CPU determines whether or not the main light unit ML should display the green signal B based on the newly acquired camera image.

If none of the above conditions 1 to 5 are met (i.e., the termination condition is not met), the CPU determines "No" in step 510 and proceeds to step 515. In step 515, the CPU sends an attention command to the speaker 31, proceeds to step 595, and ends this routine. When the speaker 31 receives the attention command, it emits a buzzer sound.

On the other hand, if at least one of the above conditions 1 to 5 is met (i.e., if the end condition is met), the CPU determines "Yes" in step 510 and proceeds to step 520. In step 520, the CPU sets the value of the execution flag Xexe to "0" and proceeds to step 595 to temporarily end this routine.

As explained above, the device of the present invention does not set the value of the execution flag Xexe to "1" when a preceding vehicle VB is present (i.e., prohibits warning). Even if the traffic light TL is equipped with an arrow light AL and the permitted direction and future traveling direction match, the arrow light AL is blocked by the preceding vehicle VB and cannot be detected, reducing the possibility of a mistaken warning being issued.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention.

(First Modification)
An outline of the operation of the DSECU 20 of the vehicle control device 10 according to the first modified example will be described with reference to FIG.
Even if the preceding vehicle VB is detected, if the vertical length H between the upper end UE of the preceding vehicle VB and the lower end BE of the main light unit ML is equal to or greater than a predetermined threshold length Hth, and if either the first condition or the second condition is satisfied, the DSECU 20 issues a warning. Note that if the length H is less than the threshold length Hth, the DSECU 20 prohibits the warning.

The DSECU 20 obtains the threshold length Hth by adding the "main lamp length Hml, which represents the vertical length between the upper end UE' and the lower end BE of the main lamp ML" to a predetermined length Hd. Note that the length used in this modified example may be any length in the camera image.

When the length H is equal to or greater than the threshold length Hth, the camera device 22 can capture an image of the arrow light AL provided on the traffic light TL without being blocked by the preceding vehicle VB. Therefore, the DSECU 20 can reliably detect the arrow light AL when the traffic light TL is equipped with the arrow light AL. According to the first modified example, even if the preceding vehicle VB is detected, if the length H is equal to or greater than the threshold length Hth and either the first condition or the second condition is satisfied, a warning is issued. This increases the likelihood that a warning will be issued in a situation where one should be issued, while reducing the likelihood that a warning will be issued erroneously.

The CPU of the DSECU 20 of the first modification executes the routine shown in Fig. 7 every time a predetermined time elapses instead of the attention-call start determination routine shown in Fig. 4, executes the routine shown in Fig. 5 every time a predetermined time elapses, and executes the routines shown in Fig. 8 to Fig. 10 every time a predetermined time elapses.
In FIG. 7, steps that perform the same processes as the steps shown in FIG. 4 are given the same reference numerals as those used in FIG. 7, and the description thereof will be omitted.

<Caution start determination routine>
At a predetermined timing, the CPU starts the process from step 700, and if the value of the execution flag Xexe is "0", it makes a "Yes" determination in step 405 shown in Fig. 7. Thereafter, the CPU executes steps 410 to 420 shown in Fig. 7.

If the traffic light TL is detected and the traffic light TL is displaying a stop signal, the CPU judges "Yes" at each of steps 420 and 425 shown in FIG. 7 and proceeds to step 430 shown in FIG. 7.

If another vehicle is present ahead of vehicle VA and the vehicle distance Dv is equal to or less than the threshold distance Dvth, the CPU judges "Yes" in each of steps 430 and 465 shown in FIG. 7 and executes steps 705 to 720 in sequence.

Step 705: The CPU identifies the upper end UE' and the lower end BE of the main lamp unit ML based on the camera image, and identifies the main lamp unit length Hml in the vertical direction between the upper end UE' and the lower end BE.
Step 710: The CPU obtains the threshold length Hth by adding the main lamp length Hml and the predetermined length Hd.
Step 715: The CPU determines the length H based on the camera image.
Step 720: The CPU determines whether the length H is less than the threshold length Hth.

If the length H is equal to or greater than the threshold length Hth, the CPU determines "No" in step 720 and proceeds to the processing of step 435 and subsequent steps shown in FIG. 7. If either the first condition or the second condition is met, the CPU sets the value of the execution flag Xexe to "1."

On the other hand, if the length H is less than the threshold length Hth, the CPU judges "Yes" in step 720 and proceeds to step 795 to temporarily end this routine. Therefore, if the length H is less than the threshold length Hth, the CPU will not set the value of the execution flag Xexe to "1" (i.e., prohibits issuing a warning) even if either the first or second condition is met.

(Second Modification)
In the above embodiment, the DSECU 20 determines the future traveling direction based on the directional road marking AD. In the second modified example, the DSECU 20 determines the future traveling direction based on the indication direction of the blinkers 33L and 33R.

When the turn signal lever 26 is operated in a left blinking direction (e.g., upward), the left turn signal 33L blinks. In this case, since the driver is likely to move the vehicle VA to the left, the DSECU 20 determines that the future traveling direction is the left direction.
When the turn signal lever 26 is operated in a right blinking direction (e.g., downward), if the right turn signal switch 26R detects the driver's operation, the right turn signal 33R blinks. In this case, since the driver is likely to move the vehicle VA to the right, the DSECU 20 determines that the future traveling direction will be to the right.
If the turn signal lever 26 is not operated, the driver is likely to drive the vehicle VA straight, and therefore the DSECU 20 determines that the future traveling direction will be a straight direction.

The DSECU 20 may determine the future direction of travel based on road signs indicating the direction in which lanes allow travel of the vehicle VA.

(Third Modification)
The first condition and the second condition may further include a condition that the distance Dt from the vehicle VA to the traffic light TL is a predetermined threshold distance Dtth.
The DSECU 20 may obtain the threshold distance Dtth based on the current vehicle speed Vs as follows.
The DSECU 20 calculates a required stopping distance Dn that the vehicle VA needs to travel before stopping at a position a predetermined distance Dd before the traffic light TL, based on the current vehicle speed Vs, under the assumption that the vehicle VA has decelerated at a predetermined deceleration. Then, the DSECU 20 obtains a value obtained by adding the required stopping distance Dn and the predetermined distance Dd as a threshold distance Dtth.

(Fourth Modification)
In the above embodiment, the CPU, as a warning, generates a buzzer sound from the speaker 31. In the third modification, the CPU, as a warning, flashes a "traffic light icon representing the traffic light TL" on the display 32. The CPU may flash the traffic light icon on the display 32 while generating a buzzer sound from the speaker 31.

(Fifth Modification)
The millimeter wave radar device 23 may be a remote sensing device that can detect an object by transmitting a wireless medium instead of a millimeter wave and receiving the reflected wireless medium. Furthermore, the vehicle control device 10 does not need to be equipped with the millimeter wave radar device 23.

(Sixth Modification)
This assistance device 10 is applicable not only to the above-mentioned engine vehicles, but also to hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), fuel cell electric vehicles (FCEVs), and battery electric vehicles (BEVs).

10...driving assistance device, 20...driving assistance ECU, 22...camera device, 31...speaker, 32...display, TL...traffic light, ML...main light, AL...arrow light, AD...directional road marking, VB...vehicle ahead.

Claims (3)

A driving assistance device that alerts a driver of a vehicle to a detected traffic signal based on a camera image acquired by a camera device that captures an image of a scene ahead of the vehicle,
When there is no preceding vehicle in front of the vehicle,
A first condition is that a main light of the traffic signal is displaying a stop signal instructing the vehicle to stop, and an arrow light is not detected below the main light; and
A second condition that the main light unit is displaying the stop signal, the arrow light unit is detected, and the permitted direction in which the arrow light unit permits the vehicle to travel does not match a future travel direction that is a future travel direction of the vehicle;
When any of the above is true, the above-mentioned warning is issued,
prohibiting the warning when the preceding vehicle is present;
It was configured as follows:
Driving assistance device. The driving assistance device according to claim 1,
If the distance between the vehicle and another vehicle located ahead of the vehicle is longer than a predetermined threshold distance, it is determined that the preceding vehicle does not exist;
If the vehicle-to-vehicle distance is equal to or less than the threshold distance, it is determined that the preceding vehicle is present.
It was configured as follows:
Driving assistance device. In the driving assistance device according to any one of claims 1 and 2,
determining the future direction of travel based on a direction in which the lane in which the vehicle is currently traveling permits the vehicle to travel and a direction in which a turn signal of the vehicle is indicated;
Driving assistance device.

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