JP6011450B2 - Vehicle braking device - Google Patents

Description

  The present invention relates to a vehicle braking device that detects that a driver's arousal level has decreased during traveling of a vehicle and applies braking to the traveling of the vehicle.

As part of driving assistance for the driver of the vehicle, a safe driving of the vehicle is ensured by detecting that the driver feels drowsy or that the concentration is low and alerting the driver. The technology to be developed has been developed.
In addition, when the driver does not wake up due to the warning and the driver has fallen asleep, a technique has been proposed to avoid the occurrence of a collision accident by braking the running of the vehicle (patent) Literature 1, Patent Literature 2).

JP 2008-220424 A JP 2005-108033 A

  However, with the proposed technology, although the risk of collision of the host vehicle can be reduced by braking the running of the vehicle, there is a problem that the risk of collision from another vehicle increases.

  The present invention has been made in view of the above-described problems, and when it is detected that the driver's arousal level has decreased, it is possible to safely brake the running of the vehicle without being collided from another vehicle. The purpose is to provide technology that can

In order to solve the above-described problem, in the vehicle braking device of the present invention, when it is detected that the driver's arousal level has decreased below a threshold value, the vehicle speed is reduced to a stoppable speed by performing deceleration control for decelerating the vehicle. After decelerating, stop control is performed to stop the vehicle. In the vehicle deceleration control, the braking mode stored in accordance with the traveling speed of the vehicle is read, and the vehicle is decelerated by braking the traveling of the vehicle . The braking mode stored in advance is a mode in which the degree of braking is smaller as the traveling speed of the vehicle is lower. Further, in these braking modes, the braking operation is executed a plurality of times, and the first braking operation among the braking operations executed a plurality of times is a stronger braking operation than the subsequent braking operation.

When the running speed of the vehicle is high, the vehicle cannot be decelerated quickly unless a certain amount of braking is applied. However, if the braking is applied at a low running speed, the running speed increases rapidly. There is a risk that the vehicle will fall from the following vehicle. Therefore, when the traveling speed of the vehicle is higher than a predetermined stoppable speed, deceleration control is performed to decelerate the vehicle to the stoppable speed, and then stop control is performed to stop the vehicle. In addition, as a braking mode for decelerating the vehicle by the deceleration control, a braking mode is stored in advance so that the degree of braking decreases as the traveling speed of the vehicle decreases. Furthermore, as those braking modes, the braking operation is executed a plurality of times, and the first braking operation among the braking operations executed a plurality of times is a stronger braking operation than the subsequent braking operation. Such a braking mode is stored. And when a driver | operator's arousal level falls, if the braking mode memorize | stored according to driving speed is read and a vehicle is braked, a vehicle will be decelerated rapidly, without being collided from another vehicle. Is possible.

In the vehicle braking device of the present invention described above, after the vehicle traveling is braked over a predetermined braking time corresponding to the traveling speed , the traveling speed of the vehicle is reduced to the stoppable speed. The operation may be decelerated to a stoppable speed by performing an operation for releasing the braking. And as a braking mode, it is good also as memorize | storing short braking time, so that driving speed becomes low.

  The degree of braking can be changed by changing the braking strength instead of the braking time. However, if the degree of braking is changed by the braking time, it is irrelevant even if the degree of braking is increased. There is no need to apply braking. Therefore, it is possible to safely brake the running of the vehicle without giving an impact to the vehicle.

In the vehicle braking device of the present invention described above, the degree of arousal is detected by taking an image (face image) of the driver's face and extracting the driver's eyes from the face image. Also good. When the extracted driver's eyes are closed, the degree of arousal may be determined to be equal to or less than a threshold value , and the vehicle may be decelerated or stopped .

  In this way, even when the driver is suddenly attacked by strong sleepiness, it is possible to immediately brake the vehicle running.

It is explanatory drawing which shows the whole structure of the vehicle 1 carrying the vehicle braking system. 2 is a block diagram showing a schematic structure of a control device 100. FIG. It is a flowchart of a vehicle braking process. It is a flowchart of the deceleration process performed during a vehicle braking process. It is explanatory drawing about the various patterns which decelerate the vehicle. It is explanatory drawing about the other aspect of the various patterns which decelerate the vehicle. It is explanatory drawing about the various patterns which decelerate the vehicle 1 in a modification. It is explanatory drawing which illustrated a mode that the vehicle 1 was decelerated by the modification.

Hereinafter, examples will be described in order to clarify the contents of the present invention described above.
A. Device configuration :
FIG. 1 shows a rough configuration of a vehicle 1 equipped with a vehicle braking system 10. As shown in the figure, a vehicle braking system 10 according to the present embodiment includes a driver camera 20 that captures a face image of a driver of the vehicle 1 at a certain period, a vehicle speed sensor 30 that outputs a traveling speed (vehicle speed) of the vehicle 1, A brake actuator 42 that moves the brake pedal 40 and a control device 100 that controls the brake actuator 42 to brake the vehicle 1 are provided. The control device 100 is a known microcomputer in which a CPU, a memory, a timer, and the like are connected by a bus. The vehicle 1 is also equipped with a speaker 50 that outputs a warning sound to the driver, and the control device 100 is also connected to the speaker 50.

  FIG. 2 shows a rough internal configuration of the control device 100. As shown in the figure, the control device 100 includes a wakefulness detection unit 102, a vehicle speed detection unit 104, a braking unit 106, a storage unit 108, and a warning unit 110. These five “parts” are classified for convenience in the inside of the control apparatus 100 by paying attention to the function of the control apparatus 100, and the inside of the control apparatus 100 corresponds to each “part”. It does not mean that it is physically divided into parts. Accordingly, each “unit” can be realized as software as a part of a computer program, or can be realized as hardware using an IC chip or a large-scale integrated circuit.

When the driver camera 20 receives the driver's face image acquired by the driver camera 20 at a constant cycle, the arousal level detection unit 102 detects the driver's arousal level by analyzing the face image, and the detected arousal level is applied to the braking unit 106. And output to the warning unit 110.
The vehicle speed detection unit 104 acquires the vehicle speed from the vehicle speed sensor 30 at a constant cycle, and outputs the acquired vehicle speed toward the braking unit 106.
The braking unit 106 controls the braking of the vehicle 1 by operating the brake actuator 42 based on the awakening level received from the awakening level detection unit 102 and the vehicle speed received from the vehicle speed detection unit 104.
The storage unit 108 stores in advance data related to a pattern for braking the vehicle 1, and the braking unit 106 reads the pattern data stored in the storage unit 108 to brake the vehicle 1. Yes.
When the warning unit 110 receives the wakefulness level detected by the wakefulness level detection unit 102, the warning unit 110 determines whether or not a warning sound needs to be output and outputs a warning sound from the speaker 50.

  The arousal level detection unit 102 according to the present embodiment corresponds to the “wakefulness level detection unit” according to the present invention, and the vehicle speed detection unit 104 according to the present embodiment corresponds to the “running speed detection unit” according to the present invention. Further, the storage unit 108 of the present embodiment corresponds to the “storage unit” in the present invention, and the braking unit 106 of the present embodiment corresponds to the “braking unit” in the present invention. Further, the control device 100 according to the present embodiment corresponds to the “vehicle braking device” according to the present invention, and the driver camera 20 according to the present embodiment corresponds to the “photographing unit” according to the present invention.

B. Vehicle braking process:
FIG. 3 shows a flowchart of the vehicle braking process of this embodiment. This process is performed by the control device 100 of the vehicle braking system 10.
In the vehicle braking process, first, a face image photographed by the driver camera 20 is acquired (S100). Then, the driver's arousal level is detected by analyzing the acquired face image (S102). Various known methods can be used to detect the arousal level. For example, the degree of arousal can be detected based on such information by detecting the opening degree of the eye, the blink frequency, and the movement of the line of sight from the driver's face image. In this embodiment, it is assumed that the awakening level decreases as the driver feels sleepy or distracts, and the awakening level increases as the driver's consciousness becomes clearer.

  Subsequently, it is determined whether or not the detected arousal level is equal to or less than a first threshold (S104). When the driver's consciousness is clear, the awakening level does not fall below the first threshold value, so that it is determined as “no” in S104, and the face image is acquired from the driver camera 20 by returning to the top of the process. (S100).

On the other hand, when the arousal level is equal to or lower than the first threshold (S104: yes), it is determined whether the arousal level is equal to or lower than the second threshold (S106). Here, the second threshold value is set to a value smaller than the first threshold value.
If the arousal level is greater than the second threshold (S106: no), it is determined that the driver's arousal level has decreased, but not enough to brake the vehicle 1, and the first warning sound is output from the speaker. 50 (S108). The first warning sound is stored in advance in a memory (not shown) of the control device 100.
By outputting the warning sound from the speaker 50 in this manner, it is possible to avoid a decrease in the driver's arousal level and continue driving safely. Then, after outputting the warning sound, the process returns to the top of the process, the face image is acquired again from the driver camera 20 (S100), and the above-described series of processes are repeated.

  The above describes the case where the driver's arousal level has decreased, but has not decreased to the second threshold. On the other hand, when it is determined that the driver's arousal level is equal to or lower than the second threshold (S106: yes), a second warning sound is output from the speaker 50 (S110). The second warning sound is output at a louder volume than the first warning sound so that it can be recognized even by a driver whose awakening level has been lowered. The warning content also strongly warns the driver of the danger. It has become contents to do. Further, the second warning sound may be a sound for notifying that the vehicle 1 is braked. The second warning sound is also stored in advance in a memory (not shown) of the control device 100.

Then, it is determined whether or not the vehicle speed acquired from the vehicle speed sensor 30 is smaller than the stoppable speed (S112). The stoppable speed is a travel speed at which the vehicle 1 can be safely stopped. That is, when the vehicle is stopped by applying braking suddenly from a state where the vehicle speed is high, not only a large impact is applied to the occupant of the vehicle 1 including the driver, but also there is a possibility that the vehicle will be collided with the following vehicle. The stoppable speed is set as a vehicle speed at which the vehicle 1 can be safely stopped without causing such a problem, and is typically set at 20 km / h.
As a result, when it is determined that the vehicle speed is higher than the stoppable speed (S112: no), a deceleration process described below is started (S200).

  FIG. 4 shows a flowchart of the deceleration process performed in the vehicle braking process. In the deceleration process, first, it is determined whether or not the vehicle speed is equal to or higher than a first threshold speed (S202). The first threshold speed is a speed that becomes a threshold for determining whether or not the vehicle 1 is traveling at a relatively high speed, and is typically set to 60 km / h. As a result, when the vehicle speed is equal to or higher than the first threshold speed (S202: yes), it is determined that the vehicle 1 is traveling at a high speed, and a braking operation of a first pattern described later is performed (S204). .

On the other hand, when the vehicle speed is smaller than the first threshold speed (S202: no), it is determined whether or not the vehicle speed is equal to or higher than the second threshold speed (S206). The second threshold speed is a speed that is a threshold for determining whether or not the vehicle 1 is traveling at a standard speed, and is typically set to 40 kilometers per hour. As a result, if the vehicle speed is smaller than the first threshold speed but greater than or equal to the second threshold speed (S206: yes), it is determined that the vehicle 1 is traveling at the standard speed, and the second described later. A pattern braking operation is performed (S208).
On the other hand, when the vehicle speed is lower than the second threshold speed (S206: no), it is determined that the vehicle 1 is traveling at a relatively low speed although it is higher than the stoppable speed. Three patterns of braking operation are performed (S210).

  FIG. 5 illustrates various patterns for decelerating the vehicle 1. In the first pattern, the brake actuator 42 is operated to depress the brake pedal 40 for a time T1, and then a braking operation is performed to hold the depressed state for a time t1. Here, it is assumed that the amount of depression does not change even when the brake pedal 40 is depressed. In the braking operation of this embodiment, after the brake pedal 40 is depressed for the time T1, the operation of holding the state where the depression is released for the time t1 is performed once. This operation may be repeated a plurality of times (for example, three times).

On the other hand, in the second pattern, the time during which the brake pedal 40 is depressed is shortened from the time T1 to the time T2 than in the first pattern, and instead, the time during which the depression is released is extended from the time t1 to the time t2. Has been.
Further, in the third pattern, the time during which the brake pedal 40 is depressed is shortened from the time T2 to the time T3, and instead, the time during which the depression is released is extended from the time t2 to the time t3. Yes.
In this embodiment, the time required for one braking operation is set to be the same in any pattern, and accordingly, the total time of time T1 and time t1, the total time of time T2 and time t2, The total time of time T1 and time t1 is the same. In any pattern, the depression amount of the brake pedal 40 is the same.

  In the deceleration process shown in FIG. 4, after performing any pattern of braking operation according to the vehicle speed of the vehicle 1 (S <b> 204, S <b> 206, S <b> 210), the deceleration process ends and the process returns to the vehicle braking process of FIG. 3. . Then, after returning from the deceleration process, the process returns to the head of the vehicle braking process to acquire the face image from the driver camera 20 again (S100), and then starts the series of processes described above.

When the vehicle speed of the vehicle 1 decreases to a stoppable speed by repeating such processing (S112: yes), the vehicle is operated by depressing the brake pedal 40 by operating the brake actuator 42 while turning on a hazard lamp (not shown). 1 is stopped (S114), and the vehicle braking process of FIG. 3 is terminated.
Further, the driver's arousal level is detected while the vehicle speed of the vehicle 1 is reduced to a stoppable speed, and the arousal level is compared with the first threshold value and the second threshold value (S100, S102, S104, S106). . Therefore, when the driver wakes up while the vehicle 1 is decelerating, the deceleration process is stopped.

  In the vehicle deceleration process described above, the driver's arousal level has dropped below the second threshold value, but when the vehicle speed of the vehicle 1 exceeds the stoppable speed, the deceleration process shown in FIG. 4 is performed. The vehicle 1 is stopped after being decelerated. In the deceleration process, the vehicle 1 is decelerated with a pattern corresponding to the vehicle speed. For this reason, the vehicle 1 can be safely stopped after decelerating the vehicle 1 safely without being collided with the following vehicle. Hereinafter, this point will be described in detail.

As described above with reference to FIG. 5, the time for which the brake pedal 40 is depressed is shortened as the vehicle speed of the vehicle 1 decreases, and accordingly, the degree of braking of the vehicle 1 is set to be small. This is because if the vehicle is braked when the vehicle speed is low, the vehicle 1 is decelerated suddenly, and there is a possibility that the vehicle 1 may collide with the following vehicle.
However, when the vehicle 1 is traveling at a relatively high speed, the vehicle 1 does not decelerate suddenly even if a large amount of braking is applied (unless extremely large braking is applied). Rather, unless the vehicle is braked to a certain extent, it takes too much time for the vehicle 1 to decelerate. Therefore, the vehicle braking system 10 according to the present embodiment is set so that as the vehicle speed of the vehicle 1 increases, the time that the brake pedal 40 is depressed is lengthened and large braking can be applied.
As a result, it is possible to quickly decelerate the vehicle 1 to the stoppable speed, and it is possible to safely stop the vehicle 1 without causing a risk of being collided with a succeeding vehicle.

When detecting the degree of arousal from the face image (S102 in FIG. 3), if the driver's eyes are closed continuously for a certain time (for example, 2 to 3 seconds), it has been detected so far. Regardless of the value of the arousal level, a small arousal level equal to or less than the second threshold may be immediately set.
In this way, even when the driver suddenly feels strong sleepiness while driving the vehicle 1, the vehicle 1 can be immediately decelerated and stopped safely.

  Further, in the above-described embodiment, it has been described that the degree to which the vehicle 1 is braked is changed by changing the time during which the brake pedal 42 is depressed by operating the brake actuator 42. However, as long as the degree of braking can be varied, it is not necessarily limited to changing the depression time of the brake pedal 40. For example, the degree of braking may be varied by changing the amount of depression of the brake pedal 40.

FIG. 6 illustrates a case where the degree of braking is varied by changing the depression amount of the brake pedal 40. In the illustrated first pattern, after the brake pedal 40 is depressed at the depression amount P1 for the time T0, a braking operation is performed to maintain the state where the depression is released for the time t0.
In the second pattern and the third pattern, the time T0 when the brake pedal 40 is depressed and the time t0 when the depression is released are the same as those in the first pattern, but the depression amount decreases to P2 in the second pattern. However, in the third pattern, it decreases to P3.
Even in this case, when the vehicle 1 is traveling at a relatively high speed, the vehicle speed of the vehicle 1 is quickly decelerated by applying large braking, and the degree of braking is reduced when the vehicle speed decreases. Thus, the vehicle 1 can be stopped without causing the possibility of a rear-end collision with the following vehicle.
Needless to say, the present invention is not limited to the patterns illustrated in FIGS. 5 and 6, and the degree of braking may be varied by changing the depression time and depression amount of the brake pedal 40.

C. Modified example:
In the embodiment described above, the braking operation has been described as being performed exclusively for safely decelerating the vehicle 1. However, the braking operation of the vehicle 1 can be used not only to decelerate the vehicle 1 but also to wake up the driver.

  FIG. 7 illustrates a braking operation used in a vehicle braking system 10 according to a modified example. As shown in the figure, in the modification, for each of the first pattern, the second pattern, and the third pattern, two types of braking operations are set, that is, a braking operation at the first braking and a braking operation at the second and subsequent braking. Has been. The second and subsequent braking operations are the same as the braking operation of the present embodiment described above with reference to FIG. That is, the amount of depression of the brake pedal 40 is constant, and the degree of braking is changed by varying the depression time.

  On the other hand, at the time of the first braking, in any pattern, a braking operation is performed in which the brake pedal 40 is momentarily depressed for a short time. That is, in any of the first pattern, the second pattern, and the third pattern, the depression time of the brake pedal 40 is set to a short time T4, and the depression amount is set for the second and subsequent braking. It is set to a larger depression amount. Furthermore, when the amount of depression at the time of initial braking of each pattern is compared, the amount of depression of the first pattern is the largest, and a smaller amount of depression is set as the second pattern and the third pattern are reached.

  FIG. 8 illustrates a state where the vehicle 1 is decelerated by the vehicle braking system 10 according to the modification. FIG. 8A shows a case where the braking operation is started from the first pattern because the vehicle speed at the start of braking is larger than the first threshold speed. FIG. 8B shows a case where the braking operation is started from the second pattern because the vehicle speed at the start of braking is smaller than the first threshold speed but larger than the second threshold speed. . In any case, the first brake operation is instantaneous and stronger than the second and subsequent brake operations.

  In this way, in the modified example, in the first braking operation, a stronger braking operation is performed instantaneously, so that the vehicle 1 moves differently from that up to that moment. This movement acts to surprise the driver and restore the reduced arousal level. As a result, if the driver's arousal level recovers to a normal level, the vehicle 1 can continue to travel.

In the above-described modification example, it has been described that the operation of momentarily stepping on the brake pedal 40 is performed in the first braking operation. Accordingly, even when the braking operation of the first pattern is switched to the second pattern and the third pattern as the vehicle 1 decelerates, only the first braking operation of such a series of braking operations is normally performed. Unlike the above description, it is assumed that the operation of depressing the brake pedal 40 for a short time is performed.
However, in the first braking operation after switching from the first pattern to the second pattern and the first braking operation after switching from the second pattern to the third pattern, the brake operation different from normal is performed. Also good. This makes it possible to surprise the driver even during deceleration of the vehicle 1 and obtain an opportunity to recover the awakening level.

  As mentioned above, although the present Example and the modification were demonstrated, this invention is not restricted to said Example and a modification, It can implement in a various aspect in the range which does not deviate from the summary.

DESCRIPTION OF SYMBOLS 1 ... Vehicle, 10 ... Vehicle braking system, 20 ... Driver camera,
30 ... Vehicle speed sensor, 40 ... Brake pedal, 42 ... Brake actuator,
50 ... Speaker, 100 ... Control device, 102 ... Arousal level detection unit,
104 ... Vehicle speed detection unit, 106 ... Braking unit, 108 ... Storage unit,
110: Warning section.

Claims (3)

A vehicle braking device that detects that the driver's arousal level has decreased during traveling of the vehicle and applies braking to the traveling of the vehicle,
Wakefulness detection means for detecting the driver's wakefulness;
Travel speed detecting means for detecting the travel speed of the vehicle;
When the arousal level is equal to or less than a predetermined threshold and the traveling speed exceeds a predetermined stoppable speed, the vehicle is decelerated to the stoppable speed by braking the travel of the vehicle. Deceleration control means for performing control,
Stop control means for performing control to stop the vehicle when the arousal level is equal to or lower than the threshold and the traveling speed is equal to or lower than the stoppable speed;
Storage means for storing a braking mode for decelerating the vehicle to the stoppable speed in association with the traveling speed ;
The storage means stores the braking mode in which the degree of braking is smaller as the traveling speed is lower,
A vehicle braking device in which the braking operation is executed a plurality of times, and the initial braking is stored so that the braking operation is stronger than the subsequent braking operation. The vehicle braking device according to claim 1,
Said deceleration control means, after braked to travel of the vehicle over a predetermined braking time according to the prior SL running speed, a means for decelerating the vehicle by repeating the operation for releasing the said braking,
The storage device is a vehicle braking device that stores the braking time that is shorter as the traveling speed becomes lower as the braking mode. The vehicle braking device according to claim 1 or 2,
A photographing means for photographing an image of the driver's face;
The arousal level detection means is a means for detecting the awakening level by extracting the driver's eyes from an image of the driver's face.
The deceleration control means and the stop control means are vehicle braking devices that are means for determining that the arousal level is not more than the threshold value when the driver's eyes are closed.

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