Driving assistance device

Abstract

A driving assistance device is provided with an in-vehicle sensor and a processor. The processor sets a lateral distance between the first long side and the host vehicle to a first predetermined value and a lateral distance between the second long side and the host vehicle to a second predetermined value when the host vehicle travels in a central portion in a width direction of the first lane. When a vehicle is displaced from a center portion in a width direction of the first lane toward a second lane adjacent to the first lane, a lateral distance between the first long side and the vehicle is set to the first predetermined value. And a lateral distance between the second long side and the vehicle is set to a value smaller than the second predetermined value.

Description

Technical Field

[0001] The present invention relates to a driving assistance device that alerts a driver of a host vehicle when there is a three-dimensional object in a predetermined area diagonally behind the host vehicle. Background Art

[0002] A driving assistance device has been proposed that alerts a driver of a host vehicle when there is a three-dimensional object in a predetermined area diagonally behind the host vehicle (for example, see Japanese Patent Laid-Open No. 6-258426 below). This driving assistance device (hereinafter referred to as the "conventional device") emits radio waves to the rear of the host vehicle (diagonally right rear and diagonally left rear). When there is a three-dimensional object diagonally behind the host vehicle, the radio waves emitted from the conventional device are reflected by the three-dimensional object, and the radio waves (reflected waves) travel toward the host vehicle. The conventional device receives this reflected wave. The conventional device calculates physical quantities related to the three-dimensional object (such as the position of the three-dimensional object relative to the host vehicle and the speed of the three-dimensional object relative to the host vehicle) based on physical quantities related to the emitted radio waves and the received reflected waves. The conventional device alerts the driver with a predetermined alert when it determines based on the calculation result that the three-dimensional object is approaching the host vehicle. Summary of the Invention

[0003] As described above, the conventional device emits radio waves for detecting a three-dimensional object to the rear of the host vehicle. In the conventional device, the area that the emitted radio waves can reach (the radius of the fan-shaped area extending diagonally to the rear of the host vehicle (the reachable distance of the radio waves)) corresponds to the area of the object for which the above alert is issued (hereinafter referred to as the alert target area). Generally, the reachable distance of this radio wave is greater than the width of a standard driving lane (3.5 meters). For example, the reachable distance of the radio wave is about 10 meters.

[0004] For example, when the host vehicle is traveling in the first lane (left lane) on a road including a first lane (left lane), a second lane (center lane), and a third lane (right lane), the radio waves emitted from the host vehicle diagonally to the right rear reach at least near the boundary between the second lane and the third lane. That is, in a plan view, the alert target area overlaps with the second lane.

[0005] For example, consider the following scenario: When the driver wants to move the host vehicle from the first lane to the second lane (change lanes) in order to overtake a preceding vehicle, there is another vehicle in the area of the alert target area that overlaps with the second lane. In this scenario, the conventional device detects this other vehicle and issues an alert. As a result, the driver can abort (or postpone) the lane change in order to avoid contact between the other vehicle and the host vehicle.

[0006] On the other hand, if there is no other vehicle in the second lane, no alarm is issued. Therefore, when the driver starts to move his own vehicle to the side of the second lane, along with the movement of the own vehicle (lateral displacement), the alarm target area also moves horizontally and parallel to the right. In this process, the end of the alarm target area sometimes overlaps with the third lane. Imagine a scenario in which there is another vehicle within the end of the alarm target area (in the area overlapping with the third lane). In this scenario, the existing device detects the other vehicle and issues an alarm. In this scenario, the possibility that the other vehicle will cause an obstacle to the movement of the own vehicle from the first lane to the second lane (lane change) is low. Despite this, an alarm will still be issued by the existing device. Therefore, the driver of the own vehicle may be annoyed by the alarm.

[0007] One of the objects of the present invention is to provide a driving assistance device that issues an alarm when a solid object exists diagonally behind a vehicle and that can suppress an alarm that is not originally necessary.

[0008] In order to solve the above problems, the driving assistance device (1) of the present invention comprises:

[0009] A vehicle-mounted sensor (20) for acquiring information related to a target object existing around the own vehicle (V); and

[0010] The processor (10) controls the notification device (30) to issue an alarm when a three-dimensional object exists in a strip-shaped alarm target area (Aa, Ab) extending in the front-rear direction obliquely behind the own vehicle.

[0011] The processor is configured as follows:

[0012] When the own vehicle is traveling in the center portion in the width direction of the first lane (L1), a lateral distance (D3a, D3b) between the first long side (E3a, E3b) and the own vehicle is set to a first predetermined value (Δd3), and a lateral distance (D4a, D4b) between the second long side (E4a, E4b) and the own vehicle is set to a second predetermined value (Δd4[0]), wherein the first long side (E3a, E3b) is a long side of the alarm target area and is located on the own vehicle side, and the second long side (E4a, E4b) is a long side of the alarm target area and is located on the opposite side of the own vehicle,

[0013] When the own vehicle shifts from the center of the first lane in the width direction to the side of the second lane (L2a, L2b) adjacent to the first lane, the lateral distance between the first long side and the own vehicle is set to the first predetermined value, and the lateral distance between the second long side and the own vehicle is set to a value smaller than the second predetermined value (Δd4[ΔYa], Δd4[ΔYb]).

[0014] In addition, the driving assistance method according to the present invention includes:

[0015] an information acquisition step of acquiring information related to a target present around the host vehicle; and

[0016] a notification step of controlling a notification device to issue an alarm when there is a three-dimensional object in a strip-shaped alarm target area extending in the front-rear direction obliquely rearward of the host vehicle.

[0017] The notification step is configured to include:

[0018] a step of setting a lateral distance between a first long side and the host vehicle to a first predetermined value and setting a lateral distance between a second long side and the host vehicle to a second predetermined value when the host vehicle is traveling at the center in the width direction of a first lane, where the first long side is a long side of the alarm target area and is located on the host vehicle side, and the second long side is a long side of the alarm target area and is located on the opposite side of the host vehicle; and

[0019] a step of setting the lateral distance between the first long side and the host vehicle to the first predetermined value and setting the lateral distance between the second long side and the host vehicle to a value smaller than the second predetermined value when the host vehicle shifts from the center in the width direction of the first lane to the second lane side adjacent to the first lane.

[0020] In addition, the driving assistance program according to the present invention causes a computer provided in the host vehicle to execute the information acquisition step and the notification step.

[0021] In the information acquisition step, information related to a target present around the host vehicle is acquired.

[0022] In the notification step, when there is a three-dimensional object in a strip-shaped alarm target area extending in the front-rear direction obliquely rearward of the host vehicle, the notification device is controlled to issue an alarm.

[0023] The notification step is configured to include:

[0024] a step of setting a lateral distance between a first long side and the host vehicle to a first predetermined value and setting a lateral distance between a second long side and the host vehicle to a second predetermined value when the host vehicle is traveling at the center in the width direction of a first lane, where the first long side is a long side of the alarm target area and is located on the host vehicle side, and the second long side is a long side of the alarm target area and is located on the opposite side of the host vehicle; and

[0025] A step of setting the lateral distance between the first long side and the host vehicle to the first predetermined value and setting the lateral distance between the second long side and the host vehicle to a value smaller than the second predetermined value when the host vehicle shifts from the central portion in the width direction of the first lane to the second lane side adjacent to the first lane.

[0026] When the host vehicle equipped with the existing device shifts laterally, the warning target area is shifted laterally (parallelly) in the same manner as the shift of the host vehicle without changing the size of the warning target area. Therefore, a part of the warning target area may extend to the third lane (the lane on the side opposite to the first lane) adjacent to the second lane, and as the lateral shift amount of the host vehicle increases, the amount of extension of the warning target area to the third lane (the width of the overlapping part with the third lane) increases.

[0027] In contrast, in the driving assistance device according to the present invention, when the host vehicle shifts laterally from the central portion (hereinafter referred to as "neutral position") in the width direction (lateral direction) of the first lane, the lateral distance between the host vehicle and the first long side is maintained constant, and the lateral distance between the host vehicle and the second long side is shortened. That is, the width (lateral size) of the warning target area is reduced. Thereby, it is possible to suppress the situation where the warning target area extends to the third lane side (or the amount of extension increases) when the host vehicle shifts laterally from the neutral position. Thereby, it is possible to suppress the situation where an unnecessary warning is issued.

[0028] In the driving assistance device according to one aspect of the present invention,

[0029] The processor obtains the lateral shift amount when the host vehicle shifts from the central portion in the width direction of the first lane to the second lane side, and sets the lateral distance between the second long side and the host vehicle to a value obtained by subtracting the lateral shift amount from the second predetermined value.

[0030] Accordingly, even when the host vehicle shifts laterally from the neutral position, the position of the second long side relative to the road surface remains unchanged.

[0031] In addition, in the driving assistance device according to another aspect of the present invention,

[0032] The processor is configured to set the second predetermined value based on the width of the first lane.

[0033] In this technical solution, the processor regards the width of the second lane as the same as that of the first lane, and sets a second predetermined value based on the width of the first lane. For example, the second predetermined value is set to be the same as the width of the first lane or a value slightly larger than the width of the first lane (a value obtained by adding a predetermined margin). This can increase the possibility of setting the warning target area in such a way that the second long side is within the second lane. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Hereinafter, the features, advantages, and technical and industrial significance of the exemplary embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals denote the same elements, and:

[0035] Figure 1 is a block diagram of a driving assistance device according to an embodiment of the present invention.

[0036] Figure 2A is a plan view showing a detectable range.

[0037] Figure 2B is a plan view showing a detectable range.

[0038] Figure 3 A in is a plan view for explaining a warning target area when the host vehicle shifts to the right from the neutral position.

[0039] Figure 3 B in is a plan view for explaining a warning target area when the host vehicle shifts to the right from the neutral position.

[0040] Figure 4A is a plan view for explaining a warning target area when the host vehicle shifts to the left from the neutral position.

[0041] Figure 4B is a plan view for explaining a warning target area when the host vehicle shifts to the left from the neutral position.

[0042] Figure 5 is a flowchart of a program executed by the CPU to implement the function of setting the warning target area based on the lateral displacement amount of the host vehicle.

[0043] Figure 6A is a plan view for explaining the difference between the maximum value of the width of the warning target area of the driving assistance device according to the first embodiment of the present invention and the maximum value of the width of the warning target area of the driving assistance device according to the second embodiment.

[0044] Figure 6BIt is a plan view for explaining the difference between the maximum width of the warning target area of the driving assistance device according to the first embodiment of the present invention and the maximum width of the warning target area of the driving assistance device according to the second embodiment. Detailed Embodiment

[0045] <First Embodiment>

[0046] (Schematic)

[0047] As Figure 1 shown, the driving assistance device 1 according to the first embodiment of the present invention is applicable to a vehicle V (hereinafter referred to as "own vehicle") equipped with an automatic driving function. The driving assistance device 1 has a function (warning function) of issuing a predetermined warning when a three-dimensional object (another vehicle) is detected behind the own vehicle diagonally in a state where the automatic driving function is invalidated (a state where driving operation is mainly performed by the driver).

[0048] (Specific Configuration)

[0049] As Figure 1 shown, the driving assistance device 1 includes an ECU 10, an in-vehicle sensor 20, and a notification device 30.

[0050] The ECU 10 includes a microcomputer including a CPU 10a, a ROM 10b (rewritable non-volatile memory), a RAM 10c, a timer 10d, etc. The CPU 10a realizes various functions by executing a program (instruction) stored in the ROM 10b. The ROM 10b and the RAM 10c are examples of storage media. The ECU 10 is connected to other ECUs via a CAN (Controller Area Network).

[0051] The in-vehicle sensor 20 includes a millimeter-wave radar 21, a sonar 22, and a camera 23.

[0052] The millimeter-wave radar 21 includes a transceiver unit and a signal processing unit. The transceiver unit emits millimeter-wave band radio waves (hereinafter referred to as "millimeter waves") to the right rear and left rear of the own vehicle, and receives the millimeter waves (reflected waves) reflected by three-dimensional objects (other vehicles, pedestrians, etc.) within the emission range. The signal processing unit identifies the distance between the own vehicle and the three-dimensional object, the relative position (direction) of the three-dimensional object with respect to the own vehicle, etc. based on the time from the emission of the millimeter wave to the reception of the reflected wave by the transceiver unit, the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation degree of the reflected wave, etc., and provides the identification result to the ECU 10.

[0053] The sonar 22 intermittently emits ultrasonic waves to the right and left rear diagonals of the host vehicle and receives the ultrasonic waves (reflected waves) reflected by the solid object. The sonar 22 identifies the distance between the host vehicle and the solid object, the relative position (direction) of the solid object with respect to the host vehicle, etc. based on the time from when the ultrasonic wave is transmitted until the reflected wave is received, and provides the identification result to the ECU 10.

[0054] The camera 23 includes a photographing device and an image analysis device. The photographing device has a built-in CCD, for example. The photographing device is provided at the front of the host vehicle and faces the front of the host vehicle. The photographing device photographs the scene in front of the host vehicle at a predetermined frame rate to obtain image data. The image analysis device analyzes the image data obtained from the photographing device and identifies the target objects existing around the host vehicle from the image. The image analysis device identifies lane markings (dividing lines, curbstones, median strips, etc. that divide the driving lane), for example, and provides the identification result to the ECU 10.

[0055] In addition, as shown in 2A and Figure 2B the regions Ma and Mb (the ranges where millimeter waves can reach) where the millimeter waves are respectively emitted by the millimeter wave radar 21 are substantially fan-shaped in a plan view. The regions Ma and Mb overlap not only with the driving lanes L2a and L2b adjacent to the driving lane L1 on which the host vehicle is traveling, but also with the driving lanes L3a and L3b adjacent to the driving lanes L2a and L2b. On the other hand, the regions Sa and Sb (the ranges where ultrasonic waves can reach) where the ultrasonic waves are emitted by the sonar 22 are also substantially fan-shaped in a plan view. The regions Sa and Sb overlap with the regions Ma and Mb. The regions Sa and Sb are narrower than the regions Ma and Mb. The sonar 22 is used to improve the detection accuracy of solid objects relatively close to the host vehicle.

[0056] The notification device 30 includes an image display device and an audio device. The image display device displays an image based on an image display instruction obtained from the ECU 10. The audio device emits a sound based on a sound emission instruction obtained from the ECU 10.

[0057] (Alarm function)

[0058] The ECU 10 can detect the presence of a solid object in the rear diagonal of the host vehicle based on the information obtained by combining the information obtained from the in-vehicle sensor 20. The region (the maximum range) in which the ECU 10 can detect the solid object is called the "detectable regions DTa and DTb". As shown in Figure 2A and Figure 2BAs shown, the detectable regions DTa and DTb are substantially the same as the regions Ma and Mb. The ECU 10 respectively sets the following-described alarm target regions Aa and Ab within the detectable regions DTa and DTb, and when a three-dimensional object (another vehicle or a pedestrian) exists within the alarm target regions Aa and Ab, controls the notification device 30 to issue a predetermined alarm. Specifically, the ECU 10 causes the notification device 30 to display a predetermined image and issue a predetermined sound.

[0059] In a plan view, the alarm target regions Aa and Ab are rectangular (strip-shaped) extending along the front-rear direction (longitudinal direction) respectively at the right rear and left rear of the host vehicle. That is, the alarm target region Aa corresponds to the region surrounded by the front edge E1a, the rear edge E2a, the left edge E3a, and the right edge E4a. In addition, the alarm target region Ab corresponds to the region surrounded by the front edge E1b, the rear edge E2b, the right edge E3b, and the left edge E4b.

[0060] As Figure 3 shown in A of, the ECU 10 respectively sets the longitudinal distances D1a and D2a between the rear end of the host vehicle and the front edge E1a and the rear edge E2a to a predetermined value Δd1 and a predetermined value Δd2. In addition, the ECU 10 sets the lateral distance D3a between the right end (right side surface) of the host vehicle and the left edge E3a to a predetermined value Δd3. In addition, the predetermined values Δd1, Δd2, and Δd3 are stored in the ROM 10b. That is, these values are fixed values. In contrast, the value assigned to the lateral distance D4a between the right end (right side surface) of the host vehicle and the right edge E4a is a variable value. The ECU 10 sets the distance D4a as follows.

[0061] Specifically, the ECU 10 obtains (calculates) the displacement amount ΔYa of the position of the center of gravity of the host vehicle in the right direction from the central portion (hereinafter referred to as the "neutral position") in the width direction of the driving lane L1 based on the information obtained from the camera 23 (the position (coordinates) of the lane marking in the image obtained by photographing the front scene of the host vehicle). Then, the ECU 10 obtains a calculated value Δd4[ΔYa] based on the following calculation formula (1), and sets the distance D4a to the calculated value Δd4[ΔYa].

[0062] Δd4[ΔYa] = Δd3 + W - ΔYa…(1)

[0063] Here, the predetermined width W (fixed value) is, for example, "4 meters" (a value slightly larger than the width of the standard driving lane (3.5 meters)).

[0064] In addition, when the center of gravity of the host vehicle is displaced leftward from the neutral position, the ECU 10 regards the displacement amount ΔYa as "0". Therefore, when the center of gravity of the host vehicle is in the neutral position (and the area to its left) (ΔYa = 0), the width ΔWAa (D4a - D3a) of the warning target area Aa is the largest (refer to Figure 4B ). When the center of gravity of the host vehicle is in the neutral position, the right edge E4a of the warning target area Aa is located, for example, at a position slightly to the left of the right end of the driving lane L2a adjacent to the right side of the driving lane L1 (within the driving lane L2a) (refer to Figure 3 A). As shown in Figure 3 B, when the center of gravity of the host vehicle is displaced rightward from the neutral position, the warning target area Aa shrinks in its width direction. The difference between the width of the warning target area Aa before shrinking (when the center of gravity is in the neutral position) and the width of the warning target area Aa after shrinking is the same as the displacement amount ΔYa. Therefore, even when the host vehicle is displaced rightward from the neutral position, the lateral position of the right edge E4a of the warning target area Aa with respect to the road surface remains unchanged.

[0065] In addition, the ECU 10 sets the warning target area Ab according to the same steps as the above-described steps for setting the warning target area Aa. That is, as shown in Figure 3 B, the ECU 10 sets the distance D1b and the distance D2b to the predetermined values Δd1 and Δd2, respectively (refer to Figure 4A ). In addition, the ECU 10 sets the distance D3b to the predetermined value Δd3. In addition, the ECU 10 obtains the calculated value Δd4[ΔYb] based on the following arithmetic expression (2) defined by the displacement amount ΔYb from the neutral position of the center of gravity of the host vehicle to the left, and sets the distance D4b to the calculated value Δd4[ΔYb].

[0066] Δd4[ΔYb] = Δd3 + W - ΔYb…(2)

[0067] In addition, when the center of gravity of the host vehicle is displaced rightward from the neutral position, the ECU 10 regards the displacement amount ΔYb as "0". Therefore, when the center of gravity of the host vehicle is in the neutral position (and the area to its right) (ΔYb = 0), the width ΔWAb (D4b - D3b) of the warning target area Ab is the largest (refer to Figure 3 B). When the center of gravity of the host vehicle is in the neutral position, the left edge E4b of the warning target area Ab is located, for example, at a position slightly to the right of the left end of the driving lane L2b adjacent to the left side of the driving lane L1 (within the driving lane L2b) (refer to Figure 4A ). As shown in Figure 4BAs shown, when the center of gravity of the host vehicle is displaced leftward from the neutral position, the warning target area Ab shrinks in its width direction. The difference between the width of the warning target area Ab before the shrinkage (when the center of gravity is in the neutral position) and the width of the warning target area Ab after the shrinkage is the same as the displacement amount ΔYb. Therefore, even if the host vehicle is displaced leftward from the neutral position, the lateral position of the left edge E4b of the warning target area Ab relative to the road surface remains unchanged.

[0068] Next, with reference to Figure 5 , a description will be given of a program PR1 executed by the CPU10a (hereinafter simply referred to as "CPU") of the ECU10 to implement the function of setting the warning target areas Aa and Ab based on the above displacement amounts ΔYa and ΔYb.

[0069] When the CPU validates the warning function, it starts the execution of the program PR1. The CPU starts the execution of the program PR1 from step 100 and advances the process to step 101.

[0070] In step 101, the CPU executes initialization processing. Specifically, the CPU sets the distances D1a and D1b to a predetermined value Δd1. In addition, the CPU sets the distances D2a and D2b to a predetermined value Δd2. In addition, the CPU sets the distances D3a and D3b to a predetermined value Δd3. Next, the CPU advances the process to step 102.

[0071] In step 102, based on the information obtained from the camera 23, the CPU determines whether the host vehicle (the center of gravity of the host vehicle) has been displaced rightward from the neutral position. When the CPU determines that the host vehicle has been displaced rightward from the neutral position (102: Yes), it advances the process to step 103. On the other hand, when it determines that the host vehicle has not been displaced rightward from the neutral position (102: No), it advances the process to step 106.

[0072] In step 103, the CPU obtains the displacement amount ΔYa. Next, the CPU advances the process to step 104.

[0073] In step 104, based on the arithmetic expression (1), the CPU obtains a calculated value Δd4[ΔYa] (Δd3 + W - ΔYa) and sets the distance D4a to the calculated value Δd4[ΔYa]. Next, the CPU advances the process to step 105.

[0074] In step 105, the CPU sets the distance D4b to the maximum value. That is, the CPU regards the displacement amount ΔYb in the arithmetic expression (2) as "0", obtains a calculated value Δd4[0] (Δd3 + W), and sets the distance D4b to the calculated value Δd4[0]. Next, the CPU returns the process to step 102.

[0075] In step 106, the CPU determines whether the host vehicle has shifted from the neutral position to the left based on the information obtained from the camera 23. When the CPU determines that the host vehicle has shifted from the neutral position to the left (106: Yes), the process proceeds to step 107. On the other hand, when the CPU determines that the host vehicle has not shifted to the left from the neutral position (106: No), the process proceeds to step 110.

[0076] In step 107, the CPU obtains the shift amount ΔYb. Then, the CPU makes the process proceed to step 108.

[0077] In step 108, the CPU sets the distance D4a to the maximum value. That is, the CPU regards the shift amount ΔYa in the arithmetic expression (1) as "0", obtains the calculated value Δd4[0] (Δd3 + W), and sets the distance D4a to the calculated value Δd4[0]. Then, the CPU makes the process proceed to step 109.

[0078] In step 109, the CPU obtains the calculated value Δd4[ΔYb] (Δd3 + W - ΔYb) based on the arithmetic expression (2), and sets the distance D4b to the calculated value Δd4[Yb]. Then, the CPU makes the process return to step 102.

[0079] In step 110, the CPU sets the distance D4a to the maximum value. That is, the CPU regards the shift amount ΔYa in the arithmetic expression (1) as "0", obtains the calculated value Δd4[0] (Δd3 + W), and sets the distance D4a to the calculated value Δd4[0]. Then, the CPU makes the process proceed to step 111.

[0080] In step 111, the CPU sets the distance D4b to the maximum value. That is, the CPU regards the shift amount ΔYb in the arithmetic expression (2) as "0", obtains the calculated value Δd4[0] (Δd3 + W), and sets the distance D4b to the calculated value Δd4[0]. Then, the CPU makes the process return to step 102.

[0081] (Effect)

[0082] In the driving assistance device 1, when the center of gravity of the host vehicle is displaced from the neutral position of the driving lane L1 to the right (left), the lateral distance D3a (D3b) between the right side surface (left side surface) of the host vehicle and the left side E3a (right side E3b) is maintained constant, but the distance D4a (D4b) between the right side surface (left side surface) of the host vehicle and the right side E4a (left side E4b) is shortened. That is, the width ΔWAa (ΔWAb) of the warning target area Aa (Ab) is reduced. Thereby, when the host vehicle is displaced from the neutral position to the right (left), the situation where the warning target area Aa (Ab) extends beyond (or the amount of extension increases) toward the driving lane L3a (L3b) is suppressed. Thereby, the situation of issuing an unnecessary warning is suppressed.

[0083] <Second Embodiment>

[0084] (Configuration)

[0085] Next, the driving assistance device 2 according to the second embodiment of the present invention will be described. The configuration of the driving assistance device 2 is the same as that of the driving assistance device 1.

[0086] (Warning Function)

[0087] In the driving assistance device 1, regardless of the width of the driving lane, the ECU 10 uses the value obtained by subtracting the displacement amount ΔYa from the value obtained by adding a predetermined width W to a predetermined value Δd3 as the distance D4a (D4b). As Figure 6A shown, when the width WL of the driving lane is relatively narrow with respect to the predetermined value W, the warning target area Aa (Ab) may extend beyond toward the driving lane L3a (L3b). On the contrary, when the width WL of the driving lane is relatively large with respect to the predetermined value W (the maximum value of the widths of the warning target areas Aa, Ab), a gap (an area where no warning is issued even if there are vehicles or pedestrians) may be formed between the right side E4a (E4b) of the warning target area Aa (Ab) and the right end (left end) of the driving lane L2a (L2b).

[0088] Therefore, in the driving assistance device 2, the ECU 10 uses the calculated value W[WL, WV] obtained based on the width WL of the driving lane and the vehicle width WV of its own vehicle instead of the predetermined value W as the maximum value of the widths of the warning target areas Aa and Ab (the widths of the warning target areas Aa and Ab when the center of gravity of its own vehicle is in the neutral position). Specifically, the ECU 10 obtains the width WL of the driving lane L1 based on the information acquired from the camera 23. Here, in many cases, the ECU 10 cannot accurately obtain the widths of the driving lanes L2a and L2b based on the information acquired from the camera 23. Therefore, the ECU 10 uses the width WL of the driving lane L1 as the widths of the driving lanes L2a and L2b. Next, the ECU 10 obtains the calculated value W[WL, WV] (WAa, WAb) based on the following arithmetic expression (3). In addition, the vehicle width WV is pre-stored in the ROM 10b.

[0089] W[WL, WV] = WL / 2 - WV / 2 - Δd3 + WL…(3)

[0090] Next, the ECU 10 obtains the calculated values Δd4[ΔYa] and Δd4[ΔYb] by applying the calculated value W[WL, WV] (the value obtained according to the arithmetic expression (3)) to the following arithmetic expressions (4) and (5) which are the same as the arithmetic expressions (1) and (2) of the first embodiment. Then, the ECU 10 sets the distances D4a and D4b to the calculated values Δd4[ΔYa] and Δd4[ΔYb] respectively.

[0091] Δd4[ΔYa] = Δd3 + W[WL, WV] - ΔYa…(4)

[0092] Δd4[ΔYb] = Δd3 + W[WL, WV] - ΔYb…(5)

[0093] In addition, the distances D1a, D1b, D2a, D2b, D3a, and D3b are set in the same manner as in the first embodiment.

[0094] (Effect)

[0095] According to this embodiment, as Figure 6B shown, the right end (left end) of the warning target area Aa (Ab) can always be made to coincide with the right end (left end) of the driving lane L2a (L2b). That is, it is possible to prevent the warning target areas Aa and Ab from extending beyond the driving lanes L3a and L3b. Thereby, it is possible to prevent the occurrence of unnecessary warnings.

[0096] The present invention is not limited to the above embodiments, and various modifications can be adopted within the scope of the present invention as follows.

[0097] <Modification Example 1>

[0098] In the above-described embodiment, the millimeter-wave radar 21 and the sonar 22 are used to detect a three-dimensional object located diagonally behind the host vehicle. Alternatively or in addition thereto, a camera, a LiDAR sensor, etc. facing the rear of the host vehicle may be used to detect a three-dimensional object located diagonally behind the host vehicle.

[0099] <Modification Example 2>

[0100] In the above-described embodiment, the warning target regions Aa and Ab are rectangular shapes extending in the front-rear direction. In the case where the host vehicle turns (when traveling on a curved road), the warning target regions Aa and Ab may also curve along the road.

Claims

1. A driving assistance device comprising: A vehicle-mounted sensor that acquires information related to a target object existing around the vehicle; and The processor controls the notification device to issue an alarm when a solid object exists in a strip-shaped alarm target area extending in the front-rear direction obliquely behind the own vehicle, The processor is configured as follows: When the own vehicle is traveling in the center portion in the width direction of the first lane, a lateral distance between the first long side and the own vehicle is set to a first predetermined value, and a lateral distance between the second long side and the own vehicle is set to a second predetermined value, the first long side being the long side of the alarm target area and being located on the own vehicle side, and the second long side being the long side of the alarm target area and being located on the opposite side of the own vehicle, When the own vehicle shifts from the center of the first lane in the width direction to the side of a second lane adjacent to the first lane, the lateral distance between the first long side and the own vehicle is set to the first predetermined value, and the lateral distance between the second long side and the own vehicle is set to a value smaller than the second predetermined value.

2. The driving assistance device according to claim 1, The processor is configured to obtain a lateral displacement amount when the host vehicle is displaced from the center portion in the width direction of the first lane to the second lane side, and set a lateral distance between the second long side and the host vehicle to a value obtained by subtracting the lateral displacement amount from the second predetermined value.

3. The driving assistance device according to claim 1 or 2, The processor is configured to set the second predetermined value based on the width of the first lane.

4. A driving assistance method, It includes information acquisition step and notification step. In the information acquisition step, information related to a target object existing around the own vehicle is acquired, In the notification step, when a solid object exists in a strip-shaped alarm target area extending in the front-rear direction behind the own vehicle, the notification device is controlled to issue an alarm, The notification step is constituted to include: The step of setting a lateral distance between a first long side and the own vehicle to a first predetermined value, and setting a lateral distance between a second long side and the own vehicle to a second predetermined value, when the own vehicle is traveling in the center portion in the width direction of the first lane, wherein the first long side is a long side of the warning target area and is located on the own vehicle side, and the second long side is a long side of the warning target area and is located on the opposite side of the own vehicle; and The step of setting the lateral distance between the first long side and the own vehicle to the first predetermined value and setting the lateral distance between the second long side and the own vehicle to a value smaller than the second predetermined value when the own vehicle shifts from the center portion in the width direction of the first lane to the side of a second lane adjacent to the first lane.

5. A driving assistance program, The computer of the vehicle executes the information acquisition step and the notification step. In the information acquisition step, information related to a target object existing around the own vehicle is acquired, In the notification step, when a solid object exists in a strip-shaped alarm target area extending in the front-rear direction behind the own vehicle, the notification device is controlled to issue an alarm, The notification step is constituted to include: The step of setting a lateral distance between a first long side and the own vehicle to a first predetermined value, and setting a lateral distance between a second long side and the own vehicle to a second predetermined value, when the own vehicle is traveling in the center portion in the width direction of the first lane, wherein the first long side is a long side of the warning target area and is located on the own vehicle side, and the second long side is a long side of the warning target area and is located on the opposite side of the own vehicle; and The step of setting the lateral distance between the first long side and the own vehicle to the first predetermined value and setting the lateral distance between the second long side and the own vehicle to a value smaller than the second predetermined value when the own vehicle shifts from the center portion in the width direction of the first lane to the side of a second lane adjacent to the first lane.

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