Driving assistance device and driving assistance method

Abstract

The present invention provides a driver assistance device that can inform the driver of the possibility of hydroplaning occurring before it actually happens. [Solution] The driving assistance device includes a LiDAR that detects objects by receiving reflected light that has been reflected by an object, and a control unit that notifies the driver that hydroplaning may occur due to the presence of water or puddles on the road surface in the area where the vehicle is traveling. The control unit identifies a low-intensity region in which the reflected light intensity acquired based on the light reception results of the LiDAR is below a first threshold intensity, and when the road surface condition is met in which a low-intensity region is detected in the driving area for a predetermined time or longer, it makes the above notification.

Description

[Technical Field]

[0001] The present invention relates to a driver assistance device that notifies the driver that hydroplaning may occur due to the presence of water or puddles on the road surface in the area where the vehicle is traveling, and to a driver assistance method by which a computer mounted on the vehicle provides the above notification. [Background technology]

[0002] It has been known for some time that hydroplaning can occur when a vehicle travels at high speed on a road surface that is wet or has puddles. For example, a driving assistance device described in Patent Document 1 (hereinafter referred to as the "conventional device") determines that hydroplaning has occurred when the relative variance of the rotational speeds of the vehicle's wheels is equal to or greater than a predetermined value, and issues a warning to notify the driver of the occurrence of hydroplaning. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2605304 Summary of the Invention

[0004] Conventional devices determine whether or not hydroplaning has occurred based on the rotational speed of the wheels. Therefore, conventional devices cannot inform the driver of the possibility of hydroplaning occurring before it actually happens.

[0005] This invention was made to address the aforementioned problems. Specifically, one of the objectives of this invention is to provide a driver assistance device that can inform the driver of the possibility of hydroplaning occurring before it actually occurs.

[0006] The driving assistance device of the present invention (hereinafter referred to as "the device of the present invention") A LiDAR (26) detects an object by receiving reflected light that has been reflected by the object after emitting light, The system includes a control unit (20) that provides notification to the driver of the vehicle that hydroplaning may occur due to the presence of wet or puddled areas on the road surface in the area where the vehicle is traveling. The control unit Based on the light reception results of the LiDAR, a weak intensity region is identified in which the reflection intensity of the reflected light obtained is less than or equal to a first threshold intensity (step 315). If the road surface condition is met such that the weak intensity region is detected in the aforementioned driving region for a predetermined period of time or longer (step 330 "Yes"), the notification is made (steps 415, 420). It is structured as follows.

[0007] If there is a puddle or wetness on the road surface in the driving area, the reflection intensity of the light reflected from that area will be low. According to the device of the present invention, the presence of a puddle or wetness is determined by determining whether the road surface conditions are met based on the reflection intensity. Therefore, it is possible to determine whether there is a possibility of hydroplaning occurring before hydroplaning actually occurs. Furthermore, if the road surface conditions are met (if there is a puddle or wetness), a warning is issued, so the driver can be notified of the possibility of hydroplaning occurring before hydroplaning actually occurs. [Brief explanation of the drawings]

[0008] [Figure 1] This is a schematic diagram of a driver assistance device according to an embodiment of the present invention. [Figure 2] This is an explanatory diagram of the operation of a driver assistance device according to an embodiment of the present invention. [Figure 3] Figure 1 is a flowchart of the puddle detection routine executed by the CPU of the ECU. [Figure 4] Figure 1 is a flowchart of the puddle notification routine executed by the CPU of the ECU. [Figure 5] Figure 1 is a flowchart of the ACC routine executed by the ECU's CPU. DETAILED DESCRIPTION OF THE INVENTION

[0009] As shown in Figure 1, the driver assistance device according to this embodiment (hereinafter referred to as "the device 10") is applied to a vehicle VA and comprises the components shown in Figure 1.

[0010] The ECU 20 is an electronic control device that includes a microcomputer as its main component. The ECU 20 is also called a control unit, a controller, or a computer. The microcomputer includes a CPU (processor), a ROM, a RAM, an interface (I / F), and the like. The functions realized by the ECU 20 may be realized by multiple ECUs.

[0011] The camera 22 acquires image data by capturing images of the scenery ahead of the vehicle VA. The millimeter-wave radar 24 acquires radar data about an object by receiving millimeter waves transmitted ahead of the vehicle VA and reflected by the object. The LiDAR (Light Detection And Ranging) 26 is a sensor that measures the distance to an object (detects the object) by receiving light reflected by the object after emitting light. The LiDAR 26 acquires LiDAR data about the object. The LiDAR data includes the "reflection intensity RI of the reflected light and the three-dimensional position of the object relative to the vehicle VA" determined based on the light reception results of the LiDAR 26.

[0012] The ECU 20 acquires image data from the camera 22, object data from the millimeter-wave radar 24, and LiDAR data from the LiDAR 26. Based on the image data and object data, the ECU 20 determines the position of an object in front of the vehicle VA relative to the vehicle VA, and the relative velocity of that object relative to the vehicle VA.

[0013] The vehicle speed sensor 28 measures the vehicle speed Vs, which represents the speed of the vehicle VA. The acceleration sensor 30 measures the longitudinal acceleration G of the vehicle VA. The ECU 20 acquires the measurements from these sensors.

[0014] The powertrain actuator 40 changes the driving force generated by a drive device (e.g., an internal combustion engine and / or an electric motor) of the vehicle VA. The brake actuator 42 controls the braking force applied to the wheels of the vehicle VA. The display device 44 is disposed in a position visible to the driver inside the vehicle VA and displays notification elements, which will be described later. The speaker 46 is disposed inside the vehicle VA and produces notification sounds, which will be described later.

[0015] <ACC(Adaptive Cruise Control)> The ECU20 starts ACC when the ACC button (not shown) is operated. When ACC is started, the ECU20 sets the target vehicle speed Vtgt to a preset set vehicle speed Vset and the target distance Dtgt to a preset set distance Dset. The driver can set the set vehicle speed Vset and set distance Dset to their desired values.

[0016] When a preceding vehicle VB (see FIG. 2) is not present during execution of ACC, the ECU 20 controls the power train actuator 40 and the brake actuator 42 so that the vehicle speed Vs coincides with the target vehicle speed Vtgt. The preceding vehicle VB is another vehicle traveling in the same lane SL as the vehicle VA and located within a predetermined distance ahead of the vehicle VA.

[0017] On the other hand, when ACC is running and a preceding vehicle VB is present, the ECU 20 controls the powertrain actuator 40 and the brake actuator 42 so that the "distance D between vehicle VA and the preceding vehicle VB" matches the target distance Dtgt, within the range where the vehicle speed Vs does not exceed the target vehicle speed Vtgt.

[0018] ACC is sometimes called automatic driving control.

[0019] (Summary of operation) When puddles or wet areas are present on the road surface, the reflected light intensity RI from the puddle or wet area will be lower than the reflected light intensity RI from areas that are neither puddle nor wet.

[0020] Based on LiDAR data, the ECU20 identifies the lane SL (see Figure 2) on which the vehicle VA is traveling as the "driving area on which the vehicle VA is traveling," and identifies the reflectance intensity RI of the reflected light from the lane SL. Based on the reflectance intensity RI, the ECU20 determines whether or not the road surface conditions are met.

[0021] The ECU 20 determines that the road surface condition is met when both the following condition A1 and condition A2 are met. Condition A1: The own lane SL has a "weak intensity area where the reflection intensity RI is equal to or less than the first threshold intensity RIth1." Condition A2: A weak intensity area in the own lane SL is detected continuously for a predetermined time or more.

[0022] When the road conditions are met, there is a higher probability of puddles or wet areas in the vehicle's lane (SL) than when the road conditions are not met. The ECU20 will notify the vehicle VA driver that hydroplaning may occur due to puddles or wet areas. As a result, the driver will drive the vehicle VA carefully to prevent hydroplaning.

[0023] According to this embodiment, it is possible to inform the driver that hydroplaning may occur before it actually occurs.

[0024] (Operation) The detailed operation of this device 10 will be explained with reference to Figure 2. The ECU 20 of this device 10 determines whether the water splash condition is met in addition to the road surface conditions described above. The ECU 20 determines that the water splash condition is met if the following conditions B1 and B2 are met.

[0025] Condition B1: A preceding vehicle VB exists. Condition B2: The reflectance intensity RI from the preceding vehicle VB is less than or equal to the second threshold intensity RIth2. For example, the second threshold intensity RIth2 is set to a value greater than the first threshold intensity RIth1.

[0026] If there are puddles or wet spots on the road surface, the preceding vehicle VB is more likely to kick up water (splashing water) as it drives. If the preceding vehicle VB is kicking up water as it drives, water spray will be present behind the preceding vehicle VB. This water spray will weaken the reflection intensity RI of the light reflected from the preceding vehicle VB.

[0027] Therefore, if the conditions for splashing water are met, there is a high probability that the preceding vehicle VB is driving while kicking up water. In other words, if the conditions for splashing water are met, there is a higher probability that there are puddles or wet surfaces on the road surface of your own lane SL.

[0028] When both the road surface condition and the water splash condition are met, the possibility of the presence of puddles or wetness is higher than when only one of the road surface condition and the water splash condition is met. The ECU 20 issues a first notification when both the road surface condition and the water splash condition are met, and issues a "second notification that is more suppressed than the first notification" when either the road surface condition or the water splash condition is met.

[0029] For example, in the first notification, the ECU 20 displays an alert element on the display device 44 to notify the driver that hydroplaning may occur due to a puddle or wetness, and outputs a predetermined alert sound (a "pon" sound) from the speaker 46. In the second notification, the ECU 20 displays the alert element on the display device 44, but does not output any sound from the speaker 46. As an example, the alert element is a message saying, "There is a possibility of hydroplaning occurring, so please slow down." The alert sound may be the audio version of the message.

[0030] This allows the alert to be suppressed (in other words, the strength of the alert is changed) depending on the likelihood of puddles or wet areas being present. This reduces the possibility of a strong alert being issued when no puddles or wet areas are present, which could be annoying to the driver.

[0031] In the example shown in Figure 2, there is water on the vehicle's lane SL and water spray behind the preceding vehicle VB. Therefore, both the road surface condition and the water spray condition are met, and the first notification is issued.

[0032] When at least one of the road surface condition and the water splash condition is met while ACC is being executed, the ECU 20 suppresses ACC more than when neither the road surface condition nor the water splash condition is met. Specifically, the ECU 20 sets the target vehicle speed Vtgt to a vehicle speed lower than the set vehicle speed Vset, and sets the target distance Dtgt to a distance longer than the set distance Dset.

[0033] If puddles or wet areas are present while ACC is running, ACC will be suppressed. This reduces the likelihood of hydroplaning occurring.

[0034] If both road surface conditions and water splash conditions are met while ACC is in operation, the ECU20 will suppress ACC more than when either the road surface conditions or the water splash conditions are met. Specifically, if either the road surface condition or the water splash condition is met while ACC is being executed, the ECU 20 sets the target vehicle speed Vtgt to a "first vehicle speed V1 that is smaller than the set vehicle speed Vset" and sets the target distance Dtgt to a "first distance D1 that is longer than the set distance Dset." On the other hand, if both the road surface condition and the water splash condition are met while ACC is being executed, the ECU 20 sets the target vehicle speed Vtgt to a "second vehicle speed V2 that is smaller than the first vehicle speed V1" and sets the target distance Dtgt to a "second distance D2 that is longer than the first distance D1." It is desirable that at least the second vehicle speed V2 of the first vehicle speed V1 and the second vehicle speed V2 be set to a relatively small vehicle speed at which hydroplaning does not occur.

[0035] This reduces the possibility that the driver may feel uneasy about the ACC due to it being strongly suppressed even though there are no puddles or wet areas.

[0036] (Specific operation) The CPU of ECU20 executes the routines shown in the flowcharts in Figures 3 to 5 at predetermined intervals.

[0037] <Puddle detection routine> When an appropriate time arrives, the CPU starts processing from step 300 in Figure 3 and executes steps 305 to 315.

[0038] Step 305: The CPU acquires LiDAR data from LiDAR26. Step 310: The CPU identifies the local lane SL based on the LiDAR data. For example, the CPU identifies the white lines to the left and right of the vehicle VA based on the reflectance RI of the LiDAR data, and identifies the area between them as the local lane SL. Step 315: The CPU determines whether or not there is a weak intensity region where the reflection intensity RI is less than or equal to the first threshold intensity RIth1.

[0039] If a weak intensity region exists, the CPU determines "Yes" in step 315, and the process proceeds to step 320. In step 320, the CPU determines whether the weak intensity region exists in the current lane SL. More specifically, the CPU identifies the three-dimensional position of the weak intensity region relative to the vehicle VA based on the LiDAR data. Then, if the position is on the current lane SL, the CPU determines that the weak intensity region exists in the current lane SL.

[0040] If a weak intensity zone exists in the lane SL, the CPU determines "Yes" in step 320 and executes steps 325 and 330. Step 325: The CPU adds "1" to Timer T. Timer T is a timer used to count the time during which a weak intensity area is detected in the local lane SL. Timer T is set to "0" if no weak intensity area is detected in the local lane SL, and during the initialization routine. The initialization routine is executed by the CPU when the ignition key switch (not shown) of the vehicle VA is changed from the OFF position to the ON position.

[0041] Step 330: The CPU determines whether Timer T is greater than or equal to the threshold Tth. The threshold Tth is set to a value such that when Timer T is greater than or equal to the threshold Tth, the time during which the weak intensity region is detected is greater than or equal to a predetermined time.

[0042] If timer T is greater than or equal to threshold Tth, the CPU determines that the road surface conditions are met. In this case, the CPU determines "Yes" in step 330 and executes steps 335 and 340.

[0043] Step 335: The CPU sets the road surface condition flag Xr to “1”. The road surface condition flag Xr is set to "1" when the road surface conditions are met, and to "0" when the road surface conditions are not met. Furthermore, the road surface condition flag Xr is set to "0" during the initialization routine.

[0044] Step 340: The CPU determines whether or not a preceding vehicle VB is present based on the image data and radar data.

[0045] If a 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 reflected light intensity RI from the position of the preceding vehicle VB, identified based on the image data and radar data, is less than or equal to the second threshold intensity RIth2.

[0046] If the reflection intensity RI is equal to or less than the second threshold intensity RIth2, the CPU determines that the water splash condition is met. In this case, the CPU determines "Yes" in step 345, and the process proceeds to step 350. In step 350, the CPU sets the water splash condition flag Xw to "1." Thereafter, the process proceeds to step 395, and the CPU temporarily ends this routine.

[0047] The water splash condition flag Xw is set to "1" when the water splash condition is met, and is set to "0" when the water splash condition is not met. Furthermore, the water splash condition flag Xw is set to "0" in the initialization routine.

[0048] If there is no preceding vehicle ("No" in step 340) and if the reflection intensity RI is greater than the second threshold intensity RIth2 ("No" in step 345), the water splash condition is not met. In this case, the process proceeds to step 355. In step 355, the CPU sets the water splash condition flag Xw to "0." Thereafter, the process proceeds to step 395, where the CPU temporarily ends this routine.

[0049] If there is no weak intensity area when the process proceeds to step 315 ("No" in step 315), and if there is no weak intensity area in the current lane SL when the process proceeds to step 320 ("No" in step 320), the road surface condition is not met. In this case, the process proceeds to step 360. In step 360, the CPU sets the road surface condition flag Xr to "0" and the timer T to "0". Then, the process proceeds to step 340.

[0050] If the timer T is less than the threshold value Tth when the process proceeds to step 330 , the CPU determines “No” in step 330 and the process proceeds to step 340 .

[0051] <Puddle Notification Routine> When an appropriate time arrives, the CPU starts the process from step 400 in FIG.

[0052] In step 405, the CPU determines whether the road surface condition flag Xr is "0" and the water splash condition flag Xw is "0".

[0053] If the road surface condition flag Xr is "0" and the water splash condition flag Xw is "0", the CPU determines "Yes" in step 405. In this case, the process proceeds to step 495, and the CPU terminates this routine.

[0054] If at least one of the road surface condition flag Xr and the water splash condition flag Xw is "1", the CPU determines "No" in step 405 and proceeds to step 410. In step 410, the CPU determines whether the road surface condition flag Xr is "1" and the water splash condition flag Xw is "1".

[0055] If the road surface condition flag Xr is "1" and the water splash condition flag Xw is "1", the CPU determines "Yes" in step 410, and the process proceeds to step 415. In step 415, the CPU makes the first notification described above. After that, the process proceeds to step 495, and the CPU terminates this routine.

[0056] If either the road surface condition flag Xr or the water splash condition flag Xw is "1", the CPU determines "No" in step 410, and the process proceeds to step 420. In step 420, the CPU makes the second notification described above. After that, the process proceeds to step 495, and the CPU terminates this routine.

[0057] <ACCルーチン> When the appropriate time arrives, the CPU starts processing from step 500 in Figure 5, and the processing proceeds to step 505.

[0058] In step 505, the CPU determines whether the ACC flag Xacc is "1". The ACC flag Xacc is set to "1" when ACC is started by operating an ACC button (not shown), and is set to "0" when ACC is ended by the establishment of a predetermined end condition. For example, the end condition is established when an ACC end button (not shown) is operated or when the vehicle VA is stopped. The ACC flag Xacc is set to "0" in the initialization routine.

[0059] If the ACC flag Xacc is "0", the CPU determines "No" in step 505. In this case, the process proceeds to step 595, and the CPU terminates this routine.

[0060] 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".

[0061] If the road surface condition flag Xr is "0" and the water splash condition flag Xw is "0", the CPU determines "Yes" in step 510 and executes steps 515 to 530.

[0062] Step 515: The CPU sets the target vehicle speed Vtgt to the set vehicle speed Vset. Step 520: The CPU sets the target distance Dtgt to the set distance Dset. Step 525: The CPU acquires a vehicle acceleration Gvt that causes the vehicle speed Vs to coincide with the target vehicle speed Vtgt. Step 530: The CPU determines whether or not a preceding vehicle VB exists based on the image data and radar data.

[0063] If there is a preceding vehicle VB, the CPU determines "Yes" in step 530 and executes steps 535 to 545. Step 535: The CPU obtains a distance acceleration Gdt that causes the inter-vehicle distance D to coincide with the target distance Dtgt. Step 540: The CPU sets the target acceleration Gtgt to the smaller of the vehicle speed acceleration Gvt and the distance acceleration Gdt. Step 545: The CPU controls the power train actuator 40 and the brake actuator 42 so that the acceleration G coincides with the target acceleration Gtgt. Thereafter, the process proceeds to step 595, where the CPU temporarily ends this routine.

[0064] If the preceding vehicle VB does not exist when the process proceeds to step 530, the CPU determines "No" in step 530, and the process proceeds to step 550. In step 550, the CPU sets the target acceleration Gtgt to the vehicle acceleration Gvt. Thereafter, the process proceeds to step 545.

[0065] When the process proceeds to step 510 , if at least one of the road surface condition flag Xr and the water splash condition flag Xw is “1”, the CPU determines “No” in step 510 and the process proceeds to step 555 .

[0066] In step 555, the CPU determines whether the road surface condition flag Xr is "1" and the water splash condition flag Xw is "1".

[0067] If either the road surface condition flag Xr or the water splash condition flag Xw is “1”, the CPU determines “No” in step 555 and executes steps 560 and 565 .

[0068] Step 560: The CPU sets the target vehicle speed Vtgt to the first vehicle speed V1. Step 565: The CPU sets the target distance Dtgt to the first distance D1. The process then proceeds to step 525.

[0069] On the other hand, if 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 steps 570 and 575 .

[0070] Step 570: The CPU sets the target vehicle speed Vtgt to the second vehicle speed V2. Step 575: The CPU sets the target distance Dtgt to the second distance D2. The process then proceeds to step 525.

[0071] According to this embodiment, since the presence or absence of puddles or wet areas is determined based on the reflectance RI of the LiDAR 26, the driver can be notified of the possibility of hydroplaning occurring before it actually happens.

[0072] In the above embodiment, the ECU 20 suppresses ACC by reducing the target vehicle speed Vtgt and increasing the target distance Dtgt, but this is not limited to this. The ECU 20 may suppress ACC by reducing the target vehicle speed Vtgt or increasing the target distance Dtgt. Furthermore, during execution of ACC, the ECU 20 sets the target acceleration Gtgt so that the acceleration G does not exceed a preset upper limit acceleration. The ECU 20 may suppress ACC by reducing the upper limit acceleration.

[0073] The ECU 20 issues a notification (first notification or second notification) to inform the driver that hydroplaning may occur when at least one of the road surface conditions and the water splash conditions is met, regardless of whether ACC is being executed or the vehicle speed Vs. However, the ECU 20 may also issue the notification when at least one of the conditions that ACC is being executed and that the vehicle speed Vs is equal to or greater than a threshold vehicle speed Vsth is met. The threshold vehicle speed Vsth is set to a relatively high value (e.g., 60 km / h). It is known that the possibility of hydroplaning occurring increases when the vehicle speed Vs is equal to or greater than 60 km / h.

[0074] Although the ECU 20 suppresses the second notification more than the first notification by not outputting an alert sound for the second notification, this is not limiting. For example, under the assumption that alert sounds are output without displaying alert elements for the first and second notifications, the ECU 20 may suppress the second notification more than the first notification by lowering the volume of the alert sound for the second notification compared to the volume of the alert sound for the first notification. Furthermore, under the assumption that alert elements are displayed without outputting alert sounds for the first and second notifications, the ECU 20 may suppress the second notification more than the first notification by displaying the alert elements for the second notification in a manner that does not attract the driver's attention as much as the alert elements for the first notification. For example, if the alert elements for the first notification are displayed in red, the alert elements for the first notification may be displayed in white. Furthermore, the size of the alert elements for the second notification may be smaller than the size of the alert elements for the first notification.

[0075] This device 10 is applicable to vehicles such as engine-powered vehicles, hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles, and electric vehicles. Furthermore, this device 10 is also applicable to vehicles that perform autonomous driving, including ACC, which is one of the driver assistance functions. [Explanation of symbols]

[0076] 10...Driving assistance system, 20...ECU, 26...LiDAR, 44...Display device, 46...Speaker.

Claims

1. A LiDAR that detects an object by receiving reflected light that has been reflected by the object after being emitted, a control unit that issues a warning to inform a driver of the vehicle that there is a possibility of hydroplaning occurring due to wetness or the presence of puddles on a road surface in a driving area in which the vehicle is traveling, The control unit Based on the light reception results of the LiDAR, a weak intensity region is identified in which the reflection intensity of the reflected light obtained is less than or equal to a first threshold intensity. If the road surface condition is met such that the weak intensity region is detected continuously for a predetermined period of time or longer within the aforementioned driving region, the notification is made. A driving assistance device configured as follows.

2. In the driving support device according to claim 1, The control unit determining whether a water splash condition is satisfied, that is, whether a preceding vehicle is present in front of the vehicle and the reflection intensity of the light reflected from the preceding vehicle is equal to or less than a second threshold intensity; When either the road surface condition or the water splash condition is satisfied, the notification is suppressed more than when both the road surface condition and the water splash condition are satisfied. A driving assistance device configured as follows.

3. In the driving support device according to claim 2, The control unit When there is no preceding vehicle ahead of the vehicle, the vehicle is automatically driven so that a vehicle speed representing the speed of the vehicle coincides with a target vehicle speed set to a preset set vehicle speed, and when there is a preceding vehicle, the vehicle is automatically driven so that a vehicle distance between the vehicle and the preceding vehicle coincides with a target distance set to a preset set distance within a range not exceeding the target vehicle speed, When at least one of the road surface condition and the water splash condition is satisfied during execution of the automatic driving control, the automatic driving control is suppressed more than when neither the road surface condition nor the water splash condition is satisfied. A driving assistance device configured as follows.

4. In the driving support device according to claim 3, The driving assistance device is configured to suppress the automatic driving control when both the road surface condition and the water splash condition are satisfied during execution of the automatic driving control, more than when either one of the road surface condition or the water splash condition is satisfied. Driving assistance device.

5. A driving assistance method in which a computer mounted on a vehicle issues a notification to notify a driver of the vehicle that there is a possibility of hydroplaning occurring due to wetness or the presence of puddles on a road surface in a driving area in which the vehicle is traveling, The aforementioned driving assistance method is A first step in which the computer identifies a weak intensity region in which the reflection intensity of the reflected light obtained based on the light reception result of a LiDAR configured to detect an object by receiving light reflected by the object, is equal to or less than a first threshold intensity; a second step of the computer issuing the notification when a road surface condition is established in which the weak intensity area has been continuously detected in the driving area for a predetermined time or more; Driving assistance methods, including those mentioned above.

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