JP2000211543A - Vehicular driving supporting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular driving supporting device which optimally supports a driving operation according to a concentration degree to a driving operation by a driver. SOLUTION: A controller selects any of driving concentration indexes from α1 to α4 according to an operation state of audio switches on both a dashboard and a steering wheel sides and a direction of a driver's line of sight as a concentration degree to a driving operation by the driver (S1-S14). The controller calculates a future lateral deviation y1 and controlling torque T using the selected value, a front attention distance L, yo which represents a traveling status of the vehicle, a lateral position D (lateral deviation dy) and a yaw angle θ(S15-S17), and outputs the calculated controlling torque T to a steering actuator (S18).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving support system for a vehicle which assists a driving operation of a vehicle driver, for example, to a driving supporting system for a typical automobile.

[0002]

2. Description of the Related Art Conventionally, a driving support device for supporting a driving operation of a vehicle driver has been proposed. As an example of such a driving support device, for example, Japanese Patent Application Laid-Open No. 3-282714
When performing driving support control according to the target trajectory,
There has been proposed a technique for correcting the control content of driving support control according to the operation state of a device operated by a driver.

[0003]

However, in the above-mentioned conventional example, since the driving support control functions even when the driver concentrates on the driving operation, the automatic driving support operation is sometimes performed by the driver. May give a feeling of strangeness.

Accordingly, an object of the present invention is to provide a driving support system for a vehicle that optimally supports a driving operation in accordance with the degree of concentration of the driver on the driving operation.

[0005]

Means for Solving the Problems In order to achieve the above object, a vehicle driving support device according to the present invention has the following configuration.

That is, an applying means for applying a steering assist force to a steering device of a vehicle, a detecting means for detecting a running state of the vehicle, a determining means for determining a degree of concentration of a driver on a driving operation, and the detecting means Control means for causing the vehicle to travel along the predetermined travel trajectory by controlling the providing means based on the detection result,
The control means reduces the control gain of the providing means when the determination means determines that the degree of concentration on the driving operation is high, as compared to when the degree of concentration is low.

Further, for example, the determination means can detect an operation state of an accessory device (for example, an audio operation switch) of the vehicle, and when it is detected that the operation is being performed, the judgment means determines a driving operation. It may be determined that the degree of concentration is low.

Further, for example, an image pickup device for detecting a driver's line of sight is further provided, and the determining means determines a degree of concentration on a driving operation when the driver's line of sight is not directed to the front of the vehicle by the image pickup device. Should be determined to be low.

Alternatively, in order to achieve the above object, a vehicle driving support device according to the present invention has the following configuration.

That is, an applying means for applying a steering assisting force to a steering device of a vehicle, a detecting means for detecting a running state of the vehicle, a determining means for determining a degree of concentration of a driver on a driving operation, and the detecting means Control means for causing the vehicle to travel along the predetermined travel trajectory by controlling the providing means based on the detection result,
The control means increases the control dead zone of the providing means when the determination means determines that the degree of concentration on the driving operation is high as compared to when the degree of concentration is low.

Alternatively, in order to achieve the above object, a vehicle driving support device according to the present invention has the following configuration.

That is, an applying means for applying a steering assist force to a steering device of a vehicle, a detecting means for detecting a running state of the vehicle, a determining means for determining a degree of concentration of a driver on a driving operation, and the detecting means Based on the detection result, a predetermined traveling locus on which the vehicle should travel, a calculating means for calculating a lateral shift amount of the vehicle with respect to the predetermined traveling locus, and a lateral shift amount calculated by the calculating means Control means for causing the vehicle to travel on the predetermined travel trajectory by controlling the providing means based on a detection result by the detection means when the predetermined value is larger than the predetermined value. The predetermined value is set to be larger as the degree of concentration on the determined driving operation is higher.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a driving support system for a vehicle according to the present invention.

FIG. 1 shows a first embodiment of the present invention.
FIG. 1 is a diagram illustrating a system configuration of a vehicle equipped with a driving assistance device according to an embodiment.

In FIG. 1, reference numeral 2 denotes a controller for controlling the entire operation of the driving support device. Reference numeral 3 denotes a CCD (Charge Couple Device) for imaging the imaging area 100 in front of the vehicle 1.
ice) An imaging device such as a camera. Reference numeral 4 denotes a vehicle speed sensor that detects the vehicle speed of the vehicle 1. Reference numeral 8 denotes a steering actuator such as a motor for driving a steering shaft so as to apply a steering assist force, as an example of a mechanism for actually steering the vehicle 1. Reference numeral 9 denotes an eye camera for detecting the driver's line of sight. 10A is an audio switch provided on the dashboard. And one
OB is an audio switch provided on the steering wheel.

FIG. 2 is a block diagram showing a control configuration of the driving support device according to the first embodiment of the present invention. Each block shown inside the controller 2 controls the control operation performed by the controller 2 by input signals. It is expressed from the viewpoint of the use of.
The actual control processing by the controller 2 is executed by a CPU (not shown) according to software stored in advance in a ROM (not shown) (details will be described later). Also, FIG.
FIG. 2 is a diagram illustrating a positional relationship between a vehicle and a lane according to the first embodiment of the present invention.

In FIG. 2, a controller 2 estimates a target trajectory Lt for the vehicle 1 to travel and detects a lateral position D by a general method based on an image in front of the vehicle 1 captured by the CCD camera 3. , The yaw angle θ is detected. here,
The lateral position D is, for example, the distance between the left white line 200 and the center line 202 of the vehicle 1 (see FIG. 3).

In this embodiment, the target trajectory Lt is estimated by performing general image processing for detecting a roadway dividing line such as a white line included in a captured image on a road surface. A line passing through a position separated by a predetermined distance or a line passing through the center of two detected roadway dividing lines on the road surface (lane center line 201 shown in FIG. 3) is calculated, and the calculated line is set as a target locus. It may be set as Lt.

The controller 2 estimates a forward gaze distance (L) based on the vehicle speed detected by the vehicle speed sensor 4. The controller 2 also controls the driver's driving operation based on the driver's gaze direction detected by the eye camera 9 and the operation states of the dashboard-side audio switch 10A and the steering wheel-side audio switch 10B, which are accessory devices of the vehicle 1. Is estimated (details will be described later).

The controller 2 calculates the calculated target locus L
A future lateral deviation y1 of the vehicle 1 is calculated based on the t, the lateral position D, the yaw angle θ, and the forward fixation distance L. Further, the controller 2 obtains the control gain k by referring to a predetermined control gain map according to the calculated estimated value α indicating the degree of concentration for the driving operation, and calculates the product of the lateral deviation y1 and the control gain k. A control amount (control torque T) based on the output is output to the steering actuator 8. Here, as the characteristic curve set in the control gain map, the lower the degree of concentration on the driving operation (the smaller the estimated value α), the larger the control gain k is set (in the control gain map shown in FIG. 2, an example). When the estimated value α is smaller, the driving torque generated in the steering actuator 8 is larger, and as the estimated value α is larger, the driving torque is smaller. , It is possible to prevent the driver from feeling uncomfortable.

The driving assist system is not limited to the system for actually generating the steering assist force by the steering actuator 8 as described above, and the steering correction is performed by the alarm actuator 8 'as shown by a broken line in FIG. A method may be used to notify the driver of the need. Here, as a specific configuration of the alarm actuator 8 ', for example, notification by voice or notification by applying pulse-like vibration to a steering shaft or a steering wheel by the steering actuator 8 may be employed.

Next, the software executed by the controller 2 will be described with reference to FIGS.

FIG. 4 is a flowchart showing a control process of the driving support device according to the first embodiment of the present invention.
FIG. 5 is a diagram illustrating the positional relationship between the vehicle and the lane in the control processing according to the first embodiment of the present invention.

In FIG. 4, step S1: an image picked up by the CCD camera 3 and the eye camera 9, and input signals from the above-mentioned various sensors and switches such as the own vehicle speed detected by the vehicle speed sensor 4 are stored in a RAM (not shown). Thereby, the operation state of various sensor input signals and switches is updated to the latest state. In the present embodiment, since the degree of concentration on the driver's driving operation is determined based on whether or not the dashboard-side audio switch 10A and the steering wheel-side audio switch 10B are being operated, a change in the operation state of those switches can be detected in step S6. Therefore, at least the operation state of the switch needs to be stored in a predetermined storage area in the RAM for a predetermined control cycle.

Step S2: A forward gaze distance L, which is a distance from the driver's viewpoint to the gaze point, is estimated. Here, the point where the driver gazes ahead is generally
It is known that the slower the vehicle speed, the closer it is, and the faster the vehicle speed, the farther it is. Therefore, the forward fixation distance L is
A curve representing the characteristic of the front gaze distance L, which becomes longer in accordance with the vehicle speed, is stored in advance in a ROM (not shown) as a look-up table (LUT), and the LUT is stored in this step in accordance with the own vehicle speed detected by the vehicle speed sensor 4. Can be obtained by referring to.

Steps S3 to S5: Based on the image in front of the vehicle 1 captured by the CCD camera 3, detection of the lateral position D (step S3), detection of the yaw angle θ (step S4), by a general method. Then, the target trajectory Lt to which the vehicle 1 should travel is estimated (step S5). still,
In the example shown in FIG. 5, the target locus Lt is set as the lane center line 201, and the case where the lateral position D of the vehicle 1 coincides with the lane center line 201 (the case where the lateral deviation dy = 0) is shown. However, the target locus Lt may be set at a position separated from the lane center line 201 by a predetermined distance as necessary.

Step S6: It is determined whether the switches are being operated by detecting the operation history of the dashboard side audio switch 10A and the steering wheel side audio switch 10B stored in the RAM. . If the determination is NO (not in operation), the process proceeds to step S10.

Step S7: YE is determined in step S6.
In the case of S (during operation), the operated switch is the steering wheel side audio switch 10B.
Is determined.

Step S8, Step S9: Step S
When the determination in Step 7 is YES (while the steering wheel-side audio switch 10B is being operated), it can be determined that the degree of concentration on the driving operation is higher than when the dashboard-side audio switch 10A is being operated. , A predetermined driving concentration index α1 (> α2) is set (step S8), and N is determined in step S7.
When O (Dashboard side audio switch 10A
Is being operated), it can be determined that the degree of concentration on the driving operation is lower than when the steering wheel side audio switch 10B is operated, so a predetermined driving concentration index α2 is set (step S9). ).

Step S10: It is determined whether or not the line of sight of the driver detected by the eye camera 9 is ahead of the vehicle 1. If the determination is YES (when the driver's line of sight is in the forward direction), the process proceeds to step S14.

Step S11: When the determination in step S10 is NO (when the driver's line of sight is not the forward direction)
It is determined whether or not the line of sight is in the lateral direction of the vehicle 1 (the left-right direction of the vehicle 1).

Steps S12 and S13: When the determination in step S11 is YES (when the driver's line of sight is in the lateral direction), the driving operation is performed in comparison with when the driver's line of sight is directed downward (in the passenger compartment). It can be determined that the degree of concentration with respect to is high, so that the predetermined driving concentration index α3 (α3>
α1> α2 ≧ α4) is set (step S12), and when the determination in step S11 is NO (when the driver's line of sight is downward), the driving is performed as compared with when the driver's line of sight is directed in the lateral direction. Since it can be determined that the degree of concentration on the operation is low, a predetermined driving concentration index α4 is set (step S13).

Step S14: The smallest value among the indices α1 to α4 set up to this step is selected,
The selected value is selected as an index α indicating the degree of concentration on the driver's driving operation at the present time in order to actually adopt the drive control of the steering actuator 8.

Step S15: The future lateral deviation y1 is calculated by the following equation: y1 = yo + dy + L × θ.

Here, the lateral deviation dy is a deviation amount of the vehicle 1 from the target locus Lt to the lane side at the present time.
After the target locus Lt is calculated in step S3 and the lateral position D is calculated in step S5, or in this step, the target locus Lt (the lane center line 2 in FIG.
01) and the difference between the horizontal position D and the horizontal position D. Also, yo is the amount of deviation between the target trajectory Lt at the position (point P) of the forward gaze distance L estimated in step S2 and the tangent to the target trajectory Lt at the current position of the vehicle 1 and is determined according to the curvature of the road. , Yo = R-SQR (R ↑ 2-L ↑ 2), where SQR (X) is the square root of X and Z ↑ 2 is Z
And R are the values calculated by the reciprocal of the curvature of the curve (see FIG. 5).

Step S16: The control gain k is obtained by referring to the control gain map (see FIG. 2) stored in advance in the ROM or the like according to the index α set in step S16.

Step S17: The product of the future lateral deviation y1 calculated in step S17 and the control gain k calculated in step S16 is calculated as the control torque T of the steering actuator 8.

Step S18: The control torque T calculated in step S17 is output to the steering actuator 8, and the routine returns.

In the above embodiment, the controller 2
Is the control gain k prior to calculating the control torque T.
Is determined, the driver's concentration index α is selected in accordance with the operation state of the dashboard-side audio switch 10A and the steering wheel-side audio switch 10B by the driver, and the driver's line of sight, and the determined value is actually determined. This is used to drive and control the steering actuator 8. Further, the controller 2 calculates the future lateral deviation y1 together with the forward fixation distance L,
Yo representing the running state of the vehicle 1 and the lateral position D (lateral deviation d
y), and the yaw angle θ is used. For this reason, even if the degree of concentration on the driver's driving operation changes every moment, the driving operation can be optimally supported according to the change, and the driver's uncomfortable feeling due to the automatic steering support is eliminated. be able to.

<Modification of First Embodiment> In the above-described embodiment, the steering assist force is continuously generated by the steering actuator 8 as a driving assist system. In this modified example, an example will be described in which on / off control of the steering assist force by the steering actuator 8 or the notification by the alarm actuator 8 ′ is performed based on a predetermined threshold value y2 based on the configuration of the driving assistance device in the above-described embodiment. I do. For this reason, in the following description, the characteristic portions of the present modified example will be mainly described, and redundant description will be omitted.

FIG. 6 is a block diagram showing a control configuration of a driving support device according to a modification of the first embodiment of the present invention. The difference from the block diagram of FIG. 2 in the first embodiment is that the control gain is different. A threshold map is provided in place of the map, a threshold y2 is selected from the threshold map according to the calculated index α, and the steering assist force by the steering actuator 8 or the notification by the alarm actuator 8 'is selected according to the selected threshold y2. In that on / off control of whether or not to perform is performed.

Here, the characteristic curve set in the threshold map includes a driving concentration index α such that the lower the degree of concentration on the driving operation, the more reliable the operation support control is performed.
Is smaller, the threshold value y2 is smaller, and the larger the driving concentration index α is, the larger the threshold value y2 should be set (in the threshold map shown in FIG. 6, linear characteristics are set as an example).

FIG. 7 is a flowchart showing an excerpted part different from FIG. 4 in the flowchart showing the control processing of the driving support device in a modification of the first embodiment of the present invention. In the control processing according to the present modification, the processing up to step S15 is the same as the flowchart in FIG.

In the figure, steps S16A and S17A: threshold value y for determining whether to drive steering actuator 8 or warning actuator 8 '
2 is selected from a threshold map (see FIG. 6) stored in advance in a ROM or the like according to the index α selected in step S14 (step S16A), and the future lateral deviation y1 (the absolute value of y1) calculated in step S15 is selected. ) Is the selected threshold value y
It is determined whether it is greater than 2 (step S17A).
If the determination is NO (| y1 | <y2), there is no need to drive the steering actuator 8 and the alarm actuator 8 ', so the routine returns.

Step S18A: If the determination in step S17A is YES (| y1 | .gtoreq.y2), the control by the steering actuator 8 or the alarm actuator 8 'is executed, and the routine returns. Here, as the control operation by the alarm actuator 8 ′, for example, notification by voice or pulse-shaped vibration generated on the steering shaft or the steering wheel by the steering actuator 8 may be used.

According to this modification, the driver's concentration on the driving operation is reduced, and the driving operation can be properly supported only when the lateral deviation y1 is large in the future. It is possible to eliminate the driver's discomfort due to the automatic support.

[Second Embodiment] In the present embodiment, the control torque T is applied to the steering actuator 8 based on the configuration of the driving support device in the first embodiment described above.
When the control torque T is generated, instead of changing the magnitude of the control gain k, the width of the control dead zone for determining whether or not to generate the control torque T is referred to by referring to a dead zone map stored in advance in a ROM or the like. To change. For this reason, in the following description, the characteristic portions of the present embodiment will be mainly described, and redundant description will be omitted.

FIG. 8 is a block diagram showing a control configuration of the driving support device according to the second embodiment of the present invention.
The difference from the block diagram of FIG. 2 in the embodiment is that a dead zone map is provided instead of the control gain map, and the width W of the control dead zone is selected from the dead zone map according to the calculated index α, and the selection is performed. Control dead zone width W
Is different in that the control torque T is determined according to the following equation.

Here, as the characteristic curve set in the dead zone map, the width W of the control dead zone is set to be smaller as the driving concentration index α is smaller (in the dead zone map shown in FIG. The smaller the index α is, the narrower the control dead zone is set, so that the driving support is more positively performed. Conversely, when the index α is large, the control dead zone is set wide, and in this case, the degree of freedom of the steering operation by the driver itself increases. Therefore, it is possible to prevent the driver from feeling uncomfortable with the steering assist operation that is automatically performed, and to optimally assist the driving operation in accordance with the degree of concentration of the driver on the driving operation.

FIG. 9 is a flowchart showing the control processing of the driving support apparatus according to the second embodiment of the present invention.
5 is a flowchart showing an excerpt part different from FIG. 4. In the control processing according to the present embodiment, the processing up to step S15 is the same as the flowchart in FIG.

In the figure, steps S16B and S17B: The width W of the control dead zone is selected from the dead zone map according to the index α set in step S14 (step S16B), and the future lateral deviation y1 calculated in step S15 is selected. It is determined whether (absolute value of y1) is larger than the selected width W (step S17B).

Step S18C: If the determination in step S17B is YES (| y1 | ≧ W), the control torque T
= (Y1-W) xk, and outputs the calculated control torque T to the steering actuator 8, and returns.

Step S18D: If the determination in step S17B is NO (| y1 | <W), there is no need to generate the control torque T, and the control returns as control torque T = 0.

In this embodiment, similarly to the modification of the first embodiment, the alarm actuator 8 'may be controlled instead of controlling the steering actuator 8.

[0055]

As described above, according to the present invention,
It is possible to provide a driving assistance device for a vehicle that optimally assists a driving operation in accordance with a degree of concentration of the driver on the driving operation.

That is, according to the first, seventh, and eighth aspects of the present invention, the estimation is made by detecting the operation state of the audio operation switch (claim 3) as the accessory device (claim 2). However, when the degree of concentration of the driver on the driving operation is high, the driver's operation support is eased as compared to when the driver's concentration is low, so that the driver can be optimally supported by preventing the driver from feeling uncomfortable.

According to the fourth aspect of the present invention, when the driver is operating a device provided on the steering wheel, the driver's line of sight is not largely deviated from the front of the vehicle. It can be determined that the degree of concentration on the driving operation is higher than when the accessory device provided on the dashboard etc., which must be directed to the driver, is operated, and the driving operation is prevented by preventing the driver from feeling uncomfortable Can be optimally supported.

According to the fifth and sixth aspects of the present invention, when the driver's line of sight is directed toward the front of the vehicle, the driver's gaze is compared with when the driver is directed in another direction (eg, downward). It can be determined that the degree of concentration on the operation is high, and it is possible to prevent the driver from feeling uncomfortable and to optimally assist the driving operation.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration of a vehicle equipped with a driving assistance device according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a control configuration of the driving support device according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a positional relationship between a vehicle and a lane according to the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating a control process of the driving support device according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a positional relationship between a vehicle and a lane in a control process according to the first embodiment of the present invention.

FIG. 6 is a block diagram illustrating a control configuration of a driving assistance device according to a modification of the first embodiment of the present invention.

FIG. 7 is a flowchart showing control processing of the driving assistance device according to a modification of the first embodiment of the present invention;
It is a flowchart which shows the extract part different from.

FIG. 8 is a block diagram illustrating a control configuration of a driving support device according to a second embodiment of the present invention.

FIG. 9 is a flowchart showing an excerpted part different from FIG. 4 in the flowchart showing the control processing of the driving support device in the second embodiment of the present invention.

[Explanation of symbols]

 1: vehicle, 2: controller, 3: CCD camera, 4: vehicle speed sensor, 8: steering actuator, 8 ': alarm actuator, 9: eye camera, 10A: dashboard side audio switch, 10B: steering wheel side audio switch , 100: imaging area of the CCD camera 3, 200: white line, 201: lane center line, 202: vehicle center line, 203: tangent to the target trajectory,

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI theme coat ゛ (Reference) B62D 137: 00 (72) Inventor Masafumi Yamamoto 3-1, Fuchu-cho, Shinchu, Aki-gun, Hiroshima Mazda Co., Ltd. ( 72) Inventor Masaki Chiba 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima F-term (reference) 3D032 CC08 CC39 CC40 CC50 DA23 DA27 DA32 DA84 DA98 DB01 DB02 DB03 DB11 DC31 DD01 DD02 DD05 DD13 DE09 EA01 EA02 EA04 EB11 EC21 EC22 GG01 3D037 FA01 FA23 FA26 FB00 FB10 FB11 5H180 AA01 CC04 CC24 LL01 LL06 LL09

Claims (8)

[Claims] An application unit configured to apply a steering assist force to a steering device of a vehicle; a detection unit configured to detect a traveling state of the vehicle; a determination unit configured to determine a degree of concentration of a driver on a driving operation; Control means for causing the vehicle to travel on the predetermined traveling locus by controlling the providing means based on the detection result. The control means determines that the degree of concentration on the driving operation is high by the determination means. And a control gain of the providing means is reduced when the degree of concentration is low. 2. The method according to claim 1, wherein the determining unit is configured to detect an operation state of the accessory device of the vehicle, and determine that a degree of concentration on the driving operation is low when detecting that the operation is being performed. The driving assistance device for a vehicle according to claim 1, wherein 3. The apparatus according to claim 2, wherein the determining unit determines that the degree of concentration on the driving operation is low when detecting that the audio operation switch as the accessory device is operated. Vehicle driving assistance device. 4. The method according to claim 1, wherein the determining unit determines that the degree of concentration on the driving operation is high when detecting that an apparatus provided on a steering wheel among the accessory apparatuses is being operated. The vehicle driving support device according to claim 2. 5. An image pickup device for detecting a driver's line of sight, wherein the determination unit determines a degree of concentration on a driving operation when the driver's line of sight is not directed forward of the vehicle by the image pickup device. The driving assistance device for a vehicle according to claim 1, wherein it is determined that the vehicle is low. 6. The driving method according to claim 1, wherein the determining unit detects that the driver's line of sight is directed in a lateral direction of the vehicle by the imaging device, as compared with when the driver's line of sight is directed downward. The driving assistance device for a vehicle according to claim 5, wherein it is determined that the degree of concentration on the operation is high. 7. An applying means for applying a steering assisting force to a steering device of a vehicle, a detecting means for detecting a running state of the vehicle, a determining means for determining a degree of concentration on a driving operation of a driver, and the detecting means Control means for causing the vehicle to travel on the predetermined traveling locus by controlling the providing means based on the detection result. The control means determines that the degree of concentration on the driving operation is high by the determination means. A driving assistance apparatus for a vehicle, characterized in that, when the degree of concentration is low, the control dead zone of the providing means is increased as compared with when the degree of concentration is low. 8. An applying means for applying a steering assisting force to a steering device of a vehicle, a detecting means for detecting a running state of the vehicle, a determining means for determining a degree of concentration on a driver's driving operation, and a detecting means Based on the detection result, a predetermined traveling trajectory on which the vehicle should travel, and calculating means for calculating a lateral shift amount of the vehicle with respect to the predetermined traveling trajectory; Control means for causing the vehicle to travel on the predetermined travel trajectory by controlling the providing means based on a detection result by the detection means when the predetermined value is larger than the predetermined value. The driving support apparatus for a vehicle, wherein the predetermined value is set to be larger as the degree of concentration on the determined driving operation is higher.