Driving assistance device and driving assistance method

Abstract

The invention provides a driving support device and a driving support method capable of notifying a driver of the possibility of a slipping phenomenon before the slipping phenomenon occurs. The driving assistance device is provided with: a LiDAR that detects an object by receiving reflected light obtained by reflecting emitted light by the object; and a control unit that performs a notification for notifying a driver that a slipping phenomenon is likely to occur due to the presence of slippery or accumulated water on a road surface in a travel area in which the vehicle travels. The control means specifies a weak intensity region in which the reflection intensity of the reflected light acquired on the basis of the light reception result of the LiDAR is equal to or less than a first threshold intensity, and performs the notification when a road surface condition that the weak intensity region is detected for a predetermined time or longer in the travel region is satisfied.

Description

TECHNICAL FIELD

[0001] The present application relates to a driving assistance device that performs notification for informing a driver of a possibility of occurrence of a skid phenomenon due to presence of wetness or water on a road surface of a travel area in which a vehicle travels, and a driving assistance method that performs the notification by a computer mounted on the vehicle. BACKGROUND

[0002] Conventionally, it is known that a skid phenomenon occurs when a vehicle travels at high speed on a road surface on which wetness or water is present. For example, a driving assistance device (hereinafter, referred to as "conventional device") described in Patent Literature 1 determines that a skid phenomenon has occurred when a relative difference in rotational speed of wheels of the vehicle is equal to or greater than a predetermined value, and performs notification for informing a driver of the occurrence of the skid phenomenon.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent No. 2605304 SUMMARY

[0006] The conventional device determines whether a skid phenomenon has occurred on the basis of the rotational speed of the wheels. Therefore, the conventional device cannot inform a driver of a possibility of occurrence of a skid phenomenon before the skid phenomenon occurs.

[0007] The present application has been made to solve the problem described above. That is, an object of the present application is to provide a driving assistance device capable of informing a driver of a possibility of occurrence of a skid phenomenon before the skid phenomenon occurs.

[0008] The driving assistance device of the present application (hereinafter, referred to as "device of the present application") includes:

[0009] a LiDAR (26) that detects an object by receiving reflected light of light emitted by the LiDAR and reflected by the object; and

[0010] a control unit (20) that performs notification for informing a driver of a vehicle of a possibility of occurrence of a skid phenomenon due to presence of wetness or water on a road surface of a travel area in which the vehicle travels.

[0011] The control unit is configured to:

[0012] determine that a reflection intensity of the reflected light, which is obtained on the basis of a light-receiving result of the LiDAR, is a weak intensity region that is equal to or less than a first threshold intensity (step 315),

[0013] When the road surface condition that the weak intensity region is detected in the travel region for a predetermined time or more is established (step 330: YES), the notification is performed (step 415, step 420).

[0014] When there is water or wetness on the road surface of the travel region, the reflection intensity of the reflected light from the region becomes low. According to the device of the present application, it is determined whether there is water or wetness by determining whether the road surface condition is established based on the reflection intensity described above. Therefore, it is possible to determine whether there is a possibility of occurrence of the skidding phenomenon before the skidding phenomenon occurs. Also, the notification is performed when the road surface condition is established (when there is water or wetness), so it is possible to notify the driver of the possibility of occurrence of the skidding phenomenon before the skidding phenomenon occurs. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic configuration diagram of a driving assistance device of an embodiment of the present application.

[0016] Figure 2 is an explanatory diagram of the operation of the driving assistance device of the embodiment of the present application.

[0017] Figure 3 is a flowchart of a water determination routine executed by the CPU of the ECU shown in Figure 1

[0018] Figure 4 is a flowchart of a water notification routine executed by the CPU of the ECU shown in Figure 1

[0019] Figure 5 is a flowchart of an ACC routine executed by the CPU of the ECU shown in Figure 1

[0020] BRIEF DESCRIPTION OF DRAWINGS

[0021] 10…driving assistance device, 20…ECU, 26…LiDAR, 44…display device, 46…speaker. DETAILED DESCRIPTION

[0022] As shown in Figure 1 , the driving assistance device (hereinafter, referred to as “the present device 10”) of the embodiment is applied to the vehicle VA, and is provided with Figure 1 the constituent elements shown in

[0023] The ECU 20 is an electronic control device provided with a microcomputer as a main part. The ECU 20 is also referred to as a control unit, a controller, and a computer. The microcomputer includes a CPU (processor), a ROM, a RAM, and an interface (I / F), and the like. The functions realized by the ECU 20 can also be realized by a plurality of ECUs.​​​

[0024] The camera 22 acquires image data by taking a view of the front of the vehicle VA. The millimeter wave radar 24 acquires radar data related to an object by receiving a reflected wave of a millimeter wave transmitted toward the front of the vehicle VA, which is reflected by the object. The LiDAR (Light Detection And Ranging) 26 is a sensor that measures a distance to an object (detects the object) by receiving a reflected light of a light emitted, which is reflected by the object. The LiDAR 26 acquires LiDAR data related to the object. The LiDAR data includes a "reflected intensity of the reflected light RI and a three-dimensional position of the object with respect to the vehicle VA" determined based on a light-receiving result of the LiDAR 26.

[0025] The ECU 20 acquires the image data from the camera 22, the object data from the millimeter wave radar 24, and the LiDAR data from the LiDAR 26. The ECU 20 determines a position of an object existing in the front of the vehicle VA with respect to the vehicle VA and a relative speed of the object with respect to the vehicle VA based on the image data and the object data.

[0026] The vehicle speed sensor 28 measures a vehicle speed Vs indicating a speed of the vehicle VA. The acceleration sensor 30 measures an acceleration G in a front-rear direction of the vehicle VA. The ECU 20 acquires the measured values of these sensors.

[0027] The power transmission actuator 40 changes a driving force generated by a driving device (for example, an internal combustion engine and / or an electric motor) of the vehicle VA. The brake actuator 42 controls a braking force applied to a wheel of the vehicle VA. The display device 44 is disposed at a position in a vehicle cabin of the vehicle VA where a driver can visually recognize, and displays a notification element described later. The speaker 46 is disposed in the vehicle cabin of the vehicle VA, and emits a notification sound described later.

[0028] <ACC (Adaptive Cruise Control)>

[0029] The ECU 20 starts the ACC when an ACC button not shown is operated. When the ACC is started, the ECU 20 sets a target vehicle speed Vtgt to a set vehicle speed Vset set in advance, and sets a target distance Dtgt to a set distance Dset set in advance. The driver can set the set vehicle speed Vset and the set distance Dset to desired values.

[0030] The ECU 20 determines whether or not there is a preceding vehicle VB (refer to FIG. 1) in the execution of the ACC based on the radar data and the LiDAR data. When there is the preceding vehicle VB, the ECU 20 determines a distance D to the preceding vehicle VB based on the radar data and the LiDAR data. Figure 2In a case where the preceding vehicle VB exists in the execution of the ACC, the power transmission actuator 40 and the brake actuator 42 are controlled so that the vehicle speed Vs coincides with the target vehicle speed Vtgt. The preceding vehicle VB is another vehicle that travels on the same lane SL in which the vehicle VA travels and is located within a predetermined distance ahead of the vehicle VA.

[0031] On the other hand, in a case where the preceding vehicle VB exists in the execution of the ACC, the power transmission actuator 40 and the brake actuator 42 are controlled so that the inter-vehicle distance D between the vehicle VA and the preceding vehicle VB coincides with the target distance Dtgt in a range where the vehicle speed Vs does not exceed the target vehicle speed Vtgt.

[0032] The ACC is also sometimes referred to as automatic travel control.

[0033] (Summary of Actions)

[0034] In a case where there is water or wetness on the road surface, the reflection intensity RI of light from the area of the water or wetness is smaller than the reflection intensity RI from an area that is neither watered nor wet.

[0035] The ECU 20 determines the same lane SL in which the vehicle VA travels (refer to FIG. 1) as a "traveling area in which the vehicle VA travels" on the basis of the LiDAR data, and determines the reflection intensity RI of the reflected light from the same lane SL. The ECU 20 determines whether or not the road surface condition is established on the basis of the reflection intensity RI. Figure 2

[0036] The ECU 20 determines that the road surface condition is established in a case where both of the following conditions Al and A2 are established.

[0037] Condition Al: There is a weak intensity area in which the reflection intensity RI is equal to or smaller than a first threshold intensity RIthl in the same lane SL.

[0038] Condition A2: The weak intensity area in the same lane SL is detected for a predetermined time or more.

[0039] In a case where the road surface condition is established, there is a high possibility that there is water or wetness in the same lane SL compared to a case where the road surface condition is not established. The ECU 20 performs notification to inform the driver of the vehicle VA that there is a possibility that a skid phenomenon occurs due to the water or wetness. Thus, the driver is likely to pay attention to not cause the skid phenomenon to drive the vehicle VA.

[0040] According to the present embodiment, it is possible to inform the driver of the possibility that the skid phenomenon occurs before the skid phenomenon occurs.

[0041] (Work)

[0042] Reference Signs Figure 2 ​The detailed operation of the device 10 will be described. The ECU 20 of the device 10 determines whether or not the water spray condition is established in addition to the road surface condition described above. The ECU 20 determines that the water spray condition is established when the following conditions B1 and B2 are established.

[0043] Condition B1: The preceding vehicle VB exists.

[0044] Condition B2: The reflection intensity RI from the preceding vehicle VB is equal to or less than the second threshold intensity RIth2.

[0045] For example, the second threshold intensity RIth2 is set to a value larger than the first threshold intensity RIthl.

[0046] In the case where water or slush exists on the road surface, the possibility that the preceding vehicle VB runs while rolling up water (while splashing water) increases. In the case where the preceding vehicle VB runs while rolling up water, water spray exists behind the preceding vehicle VB. The reflection intensity RI of the reflected light from the preceding vehicle VB is weakened by the water spray.

[0047] Therefore, in the case where the water spray condition is established, the possibility that the preceding vehicle VB runs while rolling up water is high. That is, in the case where the water spray condition is established, the possibility that water or slush exists on the road surface of the subject lane SL increases.

[0048] In the case where both the road surface condition and the water spray condition are established, the possibility that water or slush exists increases compared to the case where either the road surface condition or the water spray condition is established. The ECU 20 performs the first notification in the case where both the road surface condition and the water spray condition are established, and performs the second notification, which is suppressed compared to the first notification, in the case where either the road surface condition or the water spray condition is established.

[0049] For example, in the first notification, the ECU 20 displays a notification element for notifying the driver of the meaning that the slip phenomenon is likely to occur due to water or slush on the display device 44, and outputs a predetermined notification sound (puff) from the speaker 46. In the second notification, the ECU 20 displays the notification element on the display device 44, and does not output a sound from the speaker 46. As an example, the notification element is a message of "The slip phenomenon is likely to occur, so please decelerate". In addition, the notification sound can be a voice of the above message.

[0050] Thus, the notification is suppressed (in other words, the intensity of the notification is changed) in accordance with the possibility that water or slush exists. It is possible to reduce the possibility that the driver feels tired because a strong notification is performed although water or slush does not exist.

[0051] In the case where the road surface condition is established and the water spray condition is not established, Figure 2In the example shown, there is wetness in the subject lane SL and a water splash behind the preceding vehicle VB. Therefore, both the road surface condition and the water splash condition are established, and the first notification is made.

[0052] In a case where at least one of the road surface condition and the water splash condition is established in the execution of the ACC, the ECU 20 suppresses the ACC as compared to a case where both the road surface condition and the water splash condition are not established. Specifically, the ECU 20 sets the target vehicle speed Vtgt to "a vehicle speed smaller than the set vehicle speed Vset" and sets the target distance Dtgt to "a distance longer than the set distance Dset".

[0053] In a case where there is a possibility of the presence of water or wetness in the execution of the ACC, the ACC is suppressed. Thereby, it is possible to reduce the possibility of occurrence of the slip phenomenon.

[0054] In a case where both the road surface condition and the water splash condition are established in the execution of the ACC, the ECU 20 suppresses the ACC as compared to a case where either one of the road surface condition and the water splash condition is established.

[0055] Specifically, in a case where either one of the road surface condition and the water splash condition is established in the execution of the ACC, the ECU 20 sets the target vehicle speed Vtgt to "a first vehicle speed VI smaller than the set vehicle speed Vset" and sets the target distance Dtgt to "a first distance Dl longer than the set distance Dset". On the other hand, in a case where both the road surface condition and the water splash condition are established in the execution of the ACC, the ECU 20 sets the target vehicle speed Vtgt to "a second vehicle speed V2 smaller than the first vehicle speed VI" and sets the target distance Dtgt to "a second distance D2 longer than the first distance Dl". Further, at least the second vehicle speed V2 among the first vehicle speed VI and the second vehicle speed V2 is preferably set to a relatively small vehicle speed at which the slip phenomenon does not occur.

[0056] Thereby, it is possible to reduce the possibility that the driver feels uncomfortable with the ACC although there is no water or wetness because the ACC is strongly suppressed.

[0057] (Detailed Operation)

[0058] The CPU of the ECU 20 executes the routine shown by the flowchart in the Figures 3 to 5 every time a predetermined time elapses.

[0059] <Water determination routine>

[0060] If the appropriate timing comes, the CPU starts the process from step 300 of the Figure 3 and executes steps 305 to 315.

[0061] Step 305: The CPU acquires the LiDAR data from the LiDAR 26.

[0062] Step 310: The CPU determines the home lane SL based on the LiDAR data. For example, the CPU determines the white line on the left side of the vehicle VA and the white line on the right side of the vehicle VA based on the reflection intensity RI of the LiDAR data, and determines the area between them as the home lane SL.

[0063] Step 315: The CPU determines whether there is a weak intensity region whose reflection intensity RI is below the first threshold intensity RIthl.

[0064] In the case where there is a weak intensity region, the CPU determines "Yes" in step 315, and the processing proceeds to step 320. In step 320, the CPU determines whether the weak intensity region is present in the home lane SL. In more detail, the CPU determines the three-dimensional position of the weak intensity region with respect to the vehicle VA based on the LiDAR data. Also, the CPU determines that the weak intensity region is present in the home lane SL in the case where the position is in the home lane SL.

[0065] In the case where the weak intensity region is present in the home lane SL, the CPU determines "Yes" in step 320, and executes step 325 and step 330.

[0066] Step 325: The CPU adds "1" to the timer T. The timer T is a timer for counting the time during which the weak intensity region is detected in the home lane SL. The timer T is set to "0" in the case where the weak intensity region is not detected in the home lane SL and in the initialization routine.

[0067] The initialization routine is executed by the CPU when the unillustrated ignition key switch of the vehicle VA is changed from the off position to the on position.

[0068] Step 330: The CPU determines whether the timer T is above the threshold value Tth. The threshold value Tth is set to a value at which the time during which the weak intensity region is detected becomes above a predetermined time in the case where the timer T becomes above the threshold value Tth.

[0069] In the case where the timer T is above the threshold value Tth, the CPU determines that the road surface condition is established. In this case, the CPU determines "Yes" in step 330, and executes step 335 and step 340.

[0070] Step 335: The CPU sets the road surface condition flag Xr to "1".

[0071] The road surface condition flag Xr is set to "1" in the case where the road surface condition is established, and is set to "0" in the case where the road surface condition is not established. Also, the road surface condition flag Xr is set to "0" in the initialization routine.

[0072] Step 340: The CPU determines whether the preceding vehicle VB exists based on the image data and the radar data.

[0073] In the case where the preceding vehicle VB exists, the CPU determines "Yes" in step 340, and the process proceeds to step 345. In step 345, the CPU determines whether the reflection intensity RI of the reflected light from the position of the preceding vehicle VB determined based on the image data and the radar data is equal to or less than the second threshold intensity RIth2.

[0074] In the case where the above reflection intensity RI is equal to or less than the second threshold intensity RIth2, the CPU determines that the splash condition is established. In this case, the CPU determines "Yes" in step 345, and the process proceeds to step 350. In step 350, the CPU sets the splash condition flag Xw to "1". Thereafter, the process proceeds to step 395, and the CPU temporarily ends the routine.

[0075] The splash condition flag Xw is set to "1" in the case where the splash condition is established, and is set to "0" in the case where the splash condition is not established. Further, the splash condition flag Xw is set to "0" in the initialization routine.

[0076] In the case where the preceding vehicle does not exist (step 340: No), and in the case where the reflection intensity RI is greater than the second threshold intensity RIth2 (step 345: No), the splash condition is not established. In this case, the process proceeds to step 355. In step 355, the CPU sets the splash condition flag Xw to "0". Thereafter, the process proceeds to step 395, and the CPU temporarily ends the routine.

[0077] In the case where the weak intensity region does not exist when the process proceeds to step 315 (step 315: No), and in the case where the weak intensity region does not exist in the subject lane SL when the process proceeds to step 320 (step 320: No), the road surface condition is not established. In this case, the process proceeds to step 360. In step 360, the CPU sets the road surface condition flag Xr to "0", and sets the timer T to "0". Then, the process proceeds to step 340.

[0078] In the case where the timer T is less than the threshold Tth when the process proceeds to step 330, the CPU determines "No" in step 330, and the process proceeds to step 340.

[0079] <Water Accumulation Notification Routine> If the appropriate timing comes, the CPU starts the process from step 400 of the water accumulation notification routine, and the process proceeds to step 405.

[0080] Figure 4 In the case where the preceding vehicle VB exists, the CPU determines "Yes" in step 340, and the process proceeds to step 345. In step 345, the CPU determines whether the reflection intensity RI of the reflected light from the position of the preceding vehicle VB determined based on the image data and the radar data is equal to or less than the second threshold intensity RIth2.

[0081] In step 405, the CPU determines whether the road surface condition flag Xr is "0" and the splash condition flag Xw is "0".

[0082] In the case where the road surface condition flag Xr is "0" and the splash condition flag Xw is "0", the CPU determines "Yes" in step 405. In this case, the processing proceeds to step 495, and the CPU temporarily ends the present routine.

[0083] In the case where at least one of the road surface condition flag Xr and the splash condition flag Xw is "1", the CPU determines "No" in step 405, and the processing proceeds to step 410. In step 410, the CPU determines whether the road surface condition flag Xr is "1" and the splash condition flag Xw is "1".

[0084] In the case where the road surface condition flag Xr is "1" and the splash condition flag Xw is "1", the CPU determines "Yes" in step 410, and the processing proceeds to step 415. In step 415, the CPU performs the first notification described above. Thereafter, the processing proceeds to step 495, and the CPU temporarily ends the present routine.

[0085] In the case where either one of the road surface condition flag Xr and the splash condition flag Xw is "1", the CPU determines "No" in step 410, and the processing proceeds to step 420. In step 420, the CPU performs the second notification described above. Thereafter, the processing proceeds to step 495, and the CPU temporarily ends the present routine.

[0086] <ACC routine>

[0087] If the appropriate timing comes, the CPU starts the processing from step 500 of the ACC routine, and the processing proceeds to step 505. Figure 5

[0088] In step 505, the CPU determines whether the ACC flag Xacc is "1".

[0089] The ACC flag Xacc is set to "1" in the case where the ACC is started by operating an ACC button not shown, and is set to "0" in the case where the ACC is ended by a predetermined end condition being satisfied. For example, the end condition is satisfied in the case where an ACC end button not shown is operated, and in the case where the vehicle VA is parked, and the like. The ACC flag Xacc is set to "0" in the initialization routine.

[0090] In the case where the ACC flag Xacc is "0", the CPU determines "No" in step 505. In this case, the processing proceeds to step 595, and the CPU temporarily ends the present routine.

[0091] ​If the ACC flag Xacc is "1", the CPU determines "yes" in step 505 and proceeds to step 510. In step 510, the CPU determines whether the road surface condition flag Xr is "0" and the water splash condition flag Xw is "0".

[0092] If the road surface condition indicator Xr is "0" and the water splash condition indicator Xw is "0", the CPU determines "yes" in step 510 and executes steps 515-530.

[0093] Step 515: The CPU sets the target vehicle speed Vtgt to the set vehicle speed Vset.

[0094] Step 520: The CPU sets the target distance Dtgt to the set distance Dset.

[0095] Step 525: The CPU obtains the vehicle speed acceleration Gvt to make the vehicle speed Vs match the target vehicle speed Vtgt.

[0096] Step 530: The CPU determines whether there is a vehicle VB ahead based on image data and radar data.

[0097] If the preceding vehicle VB exists, the CPU determines "yes" in step 530 and executes steps 535-545.

[0098] Step 535: The CPU obtains the distance acceleration Gdt to make the workshop distance D consistent with the target distance Dtgt.

[0099] Step 540: The CPU sets the target acceleration Gtgt to the smaller of the vehicle speed acceleration Gvt and the distance acceleration Gdt.

[0100] Step 545: The CPU controls the power transmission actuator 40 and the braking actuator 42 to make the acceleration G consistent with the target acceleration Gtgt.

[0101] After that, the process proceeds to step 595, and the CPU temporarily terminates this routine.

[0102] If no preceding vehicle VB exists when proceeding to step 530, the CPU determines "No" in step 530 and proceeds to step 550. In step 550, the CPU sets the target acceleration Gtgt to the vehicle speed acceleration Gvt. Then, the process proceeds to step 545.

[0103] If at least one of the road surface condition indicator Xr and the water splash condition indicator Xw is "1" when processing proceeds to step 510, the CPU determines "No" in step 510 and proceeds to step 555.

[0104] In step 555, the CPU determines whether the road surface condition flag Xr is "1" and the water splash condition flag Xw is "1".

[0105] In a case where either of the road surface condition flag Xr and the water splash condition flag Xw is "1", the CPU determines "No" in step 555, and executes step 560 and step 565.

[0106] Step 560: The CPU sets the target vehicle speed Vtgt to the first vehicle speed V1 described above.

[0107] Step 565: The CPU sets the target distance Dtgt to the first distance D1 described above.

[0108] Then, the process proceeds to step 525.

[0109] On the other hand, in a case where the road surface condition flag Xr is "1" and the water splash condition flag Xw is "1", the CPU determines "Yes" in step 555, and executes step 570 and step 575.

[0110] Step 570: The CPU sets the target vehicle speed Vtgt to the second vehicle speed V2 described above.

[0111] Step 575: The CPU sets the target distance Dtgt to the second distance D2 described above.

[0112] Then, the process proceeds to step 525.

[0113] According to the present embodiment, it is determined whether there is standing water or wetness based on the reflection intensity RI of the LiDAR 26, and thus it is possible to notify the driver of the possibility of a skid phenomenon occurring before the skid phenomenon occurs.

[0114] In the above-described embodiment, the ECU 20 suppresses the ACC by reducing the target vehicle speed Vtgt and extending the target distance Dtgt, but is not limited thereto. The ECU 20 can also suppress the ACC by reducing the target vehicle speed Vtgt or extending the target distance Dtgt. Also, in the execution of the ACC, the ECU 20 sets the target acceleration Gtgt in such a way that the acceleration G is not greater than a pre-set upper limit acceleration. The ECU 20 can also suppress the ACC by reducing the upper limit acceleration.

[0115] The ECU 20 performs the notification (first notification or second notification) for notifying the driver of the possibility of the occurrence of the skidding phenomenon, regardless of whether the ACC is being executed, regardless of the vehicle speed Vs, and when at least one of the road surface condition and the splash condition is satisfied. However, the ECU 20 can perform the above notification when at least one of the condition that the ACC is being executed and the condition that the vehicle speed Vs is equal to or higher than the threshold vehicle speed Vsth is satisfied. Further, the threshold vehicle speed Vsth is set to a relatively high value (for example, 60 km / h). It is known that the possibility of the occurrence of the skidding phenomenon increases when the vehicle speed Vs is equal to or higher than 60 km / h.

[0116] The ECU 20 suppresses the second notification as compared with the first notification by not outputting the notification sound in the second notification, but is not limited thereto. For example, under the premise that the notification sound is output without the notification element being displayed in the first notification and the second notification, the ECU 20 can suppress the second notification as compared with the first notification by making the volume of the notification sound of the second notification smaller than the volume of the notification sound of the first notification. Also, under the premise that the notification sound is not output and the notification element is displayed in the first notification and the second notification, the ECU 20 can suppress the second notification as compared with the first notification by displaying the notification element of the second notification in such a manner that the driver's attention is not drawn as compared with the notification element of the first notification. For example, in the case where the notification element of the first notification is displayed in red, the notification element of the first notification can be displayed in white. Also, the size of the notification element of the second notification can be made smaller than the size of the notification element of the first notification.

[0117] The device 10 can be applied to a vehicle such as an engine automobile, a hybrid vehicle, a plug-in automobile, a fuel cell vehicle, and an electric automobile. Also, the device 10 can be applied to a vehicle that performs automatic driving including the ACC as one of the driving assist functions.

Claims

1. A drive assist device, comprising: a LiDAR that detects an object by receiving reflected light of emitted light reflected by the object; and a control unit that performs notification for informing a driver of a vehicle that a slip phenomenon is likely to occur due to the presence of wetness or water on a road surface of a travel area in which the vehicle travels, the control unit determining that a weak intensity region in which a reflection intensity of the reflected light obtained based on a light reception result of the LiDAR is below a first threshold intensity, and performing the notification in a case where a road surface condition in which the weak intensity region is detected in the travel area for a predetermined time or more is established.

2. The drive assist device according to claim 1, the control unit determining whether a splash condition in which a preceding vehicle exists in front of the vehicle and a reflection intensity of the reflected light from the preceding vehicle is below a second threshold intensity is established, and suppressing the notification in a case where either of the road surface condition and the splash condition is established, as compared with a case where both of the road surface condition and the splash condition are established.

3. The drive assist device according to claim 2, the control unit performing automatic travel control in which the vehicle is automatically traveled in such a manner that a vehicle speed indicating a speed of the vehicle coincides with a target vehicle speed set to a preset set vehicle speed in a case where no preceding vehicle exists in front of the vehicle, and in such a manner that a vehicle-to-vehicle distance between the vehicle and the preceding vehicle coincides with a target distance set to a preset set distance within a range in which the target vehicle speed is not exceeded in a case where the preceding vehicle exists, and suppressing the automatic travel control in a case where at least one of the road surface condition and the splash condition is established during execution of the automatic travel control, as compared with a case where neither of the road surface condition and the splash condition is established.

4. The drive assist device according to claim 3, the drive assist device being configured to suppress the automatic travel control in a case where both of the road surface condition and the splash condition are established during execution of the automatic travel control, as compared with a case where either of the road surface condition and the splash condition is established.

5. A drive assist method that is a drive assist method in which a computer mounted on a vehicle performs notification for informing a driver of the vehicle that a slip phenomenon is likely to occur due to the presence of wetness or water on a road surface of a travel area in which the vehicle travels, the drive assist method comprising: a first step in which the computer determines that a weak intensity region in which a reflection intensity of reflected light obtained based on a light reception result of a LiDAR is below a first threshold intensity, the LiDAR being configured to detect an object by receiving reflected light of emitted light reflected by the object; and a second step in which the computer performs the notification in a case where a road surface condition in which the weak intensity region is detected in the travel area for a predetermined time or more is established. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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