Driving assistance device

Abstract

To properly execute lane-keeping assistance control even when driving through sharp curves.SOLUTION: A driving assistance device supports driving of a vehicle by a driver. The driving assistance device includes a recognition sensor, a steering actuator, and an electronic control unit. The recognition sensor recognizes the situation in front of the vehicle. The steering actuator steers the vehicle. The electronic control unit controls the steering actuator so as to suppress lane deviation of the vehicle from a traveling lane. The electronic control unit uses the recognition sensor to recognize a curve sign that prompts the driver's attention to a curve ahead of the vehicle, and increases the steering assist amount of the steering actuator for suppressing the lane deviation during passage through the curve in comparison to a case of passing through the curve without recognition of the curve sign when the curve sign is recognized.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a driving assistance device for suppressing lane departure.

Background Art

[0002] Patent Document 1 discloses a vehicle control device that executes lane keep assist control for maintaining the traveling lane of a vehicle on a target traveling lane. When the steering work rate calculated by adding the product of the steering speed and the steering torque and the product of the steering angle and the differential value of the steering torque exceeds a predetermined value, this vehicle control device reduces the control amount by the lane keep assist control compared to when the steering work rate is less than the predetermined value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the technique described in Patent Document 1, when there is a sharp curve ahead of the vehicle, it may be difficult to continue the lane keep assist control without changing the control amount in advance.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a driving assistance device that can appropriately execute lane maintenance support control even when traveling on a sharp curve.

Means for Solving the Problems

[0006] The driving assistance device according to the present disclosure assists a driver in driving a vehicle. The driving assistance device includes a recognition sensor, a steering actuator, and an electronic control unit. The recognition sensor recognizes the situation in front of the vehicle. The steering actuator steers the vehicle. The electronic control unit controls the steering actuator so as to suppress the vehicle from deviating from the traveling lane. The electronic control unit uses the recognition sensor to recognize a curve sign for prompting the driver's attention to a curve in front of the vehicle, and when the curve sign is recognized, increases the steering assist amount of the steering actuator for suppressing lane departure during passage of the curve as compared with the case of passing the curve without recognition of the curve sign.

Advantages of the Invention

[0007] According to the present disclosure, even when driving on a sharp curve, it is possible to appropriately execute lane keeping support control by using a curve sign recognized by a recognition sensor.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] 1. Example of Vehicle Configuration FIG. 1 is a diagram schematically showing an example of the configuration of a vehicle 1 equipped with a driving assistance device according to an embodiment.

[0010] Vehicle 1 is equipped with a driving support electronic control unit (driving support ECU) 10. The driving support ECU (or simply ECU) 10 performs driving support control to assist the driver in driving Vehicle 1. The ECU 10 includes a processing circuit 11 and a memory 12. The processing circuit 11 executes various processes related to the driving support of Vehicle 1. The memory 12 stores various information necessary for the processes by the processing circuit 11. By the processing circuit 11 executing various computer programs, various processes by the processing circuit 11 are realized. The various computer programs are stored in the memory 12 or recorded on a computer-readable recording medium. Note that the ECU 10 may be configured by combining a plurality of ECUs.

[0011] Also, Vehicle 1 is equipped with sensors 20. The sensors 20 include, for example, a camera 21, a vehicle speed sensor 22, and a steering angle sensor 23. The camera 21 is disposed at the front of Vehicle 1 and recognizes the situation in front of Vehicle 1. The "recognition sensor" according to the present disclosure includes a sensor that can be used for sign recognition by the ECU 10, such as the camera 21 for example. The vehicle speed sensor 22 detects the speed (vehicle speed) of Vehicle 1. The steering angle sensor 23 detects the steering angle of Vehicle 1.

[0012] Also, Vehicle 1 is equipped with a steering actuator 30 and an EPS-ECU 31. The steering actuator 30 generates a force for steering the wheels (for example, front wheels) of Vehicle 1. The steering actuator 30 can assist the driver's steering and can also steer the wheels independently of the driver's steering. As an example, the steering actuator 30 is a steering assist motor of an electric power steering system (EPS). The steering actuator 30 is controlled, for example, by the EPS-ECU 31 included in the EPS. The control of the steering actuator 30 by the EPS-ECU 31 also includes control based on a command from the driving support ECU 10 to the EPS-ECU 31.

[0013] Furthermore, the vehicle 1 includes a brake ECU 40, a meter panel 50, and a navigation device 60. The brake ECU 40 controls a brake actuator that generates the braking force of the vehicle 1. The control of the brake actuator by the brake ECU 40 includes control based on a command from the driving support ECU 10 to the brake ECU 40. The meter panel 50 is disposed inside the vehicle 1 and is an example of a display device that displays display information to the driver. The navigation device 60 is configured to be able to communicate with an external system via a wireless communication network and can acquire various information such as road information and the position information of the vehicle from the external system.

[0014] In an example of the vehicle 1 having the above-described configuration, the "driving support device" according to the present disclosure includes the driving support ECU 10, the camera 21, and the steering actuator 30.

[0015] 2. Lane Keeping Support Control The driving support control of the vehicle 1 executed by the driving support ECU 10 includes "lane keeping support control". In the following description, the lane keeping support control is referred to as LTA (Lane Tracing Assist). LTA includes controlling the steering actuator 30 so as to suppress the deviation (lane departure) of the vehicle 1 from the traveling lane.

[0016] 2-1. Basic Configuration When LTA is requested by an operation of a predetermined operator by the driver, the driving support ECU 10 executes LTA. In LTA, the ECU 10 applies a steering torque to the steering mechanism so that the position of the vehicle 1 (own vehicle) is maintained near the target travel line TL within the traveling lane L (see FIG. 1), and assists the driver's steering operation. The target travel line TL is, for example, the lane center line CL, but may be offset in the lane width direction by a predetermined distance from the lane center line CL.

[0017] The ECU 10 calculates the target steering angle δt of the LTA at a predetermined calculation cycle based on, for example, the curvature R, the yaw angle θy, and the lateral deviation Dy. The curvature R is the curvature R of the curve of the lane center line CL (see FIG. 2(B) described later). The yaw angle θy is the angle formed by the direction of the lane center line CL and the direction in which the vehicle 1 is facing. The lateral deviation Dy is the distance in the lane width direction between the center of gravity point P of the vehicle 1 and the lane center line CL. The ECU 10 can acquire information on the left and right white lines WL that demarcate the driving lane L of the vehicle 1, the lane center line CL, the curvature R, the yaw angle θy, and the lateral deviation Dy based on the image information of the camera 21. Note that for the yaw angle θy and the lateral deviation Dy, the left - right direction with respect to the lane center line CL is specified by the sign (positive or negative). Also, for the curvature R, the turning direction (right or left) of the curve is specified by the sign (positive or negative).

[0018] The calculation formula for the target steering angle δt includes, for example, the product of the curvature R and the control gain (the first term), the product of the yaw angle θy and the control gain (the second term), and the product of the lateral deviation Dy and the control gain (the third term). The first term is a steering angle component that is determined according to the curvature R of the road and acts in a feed - forward manner. The second term is a steering angle component that acts in a feedback manner so as to reduce the yaw angle θy (that is, so as to reduce the deviation of the direction of the vehicle 1 with respect to the lane center line CL). That is, it is a steering angle component calculated by feedback control with the target value of the yaw angle θy set to zero. The third term is a steering angle component that acts in a feedback manner so as to reduce the lateral deviation Dy, which is the deviation (position deviation) of the vehicle 1 in the lane width direction with respect to the lane center line CL. That is, it is a steering angle component calculated by feedback control with the target value of the lateral deviation Dy set to zero.

[0019] According to the LTA, for example, when the center line CL of the lane curves to the left, when the vehicle 1 has a lateral shift to the right with respect to the center line CL of the lane, or when the vehicle 1 is facing to the right with respect to the center line CL of the lane, the target steering angle δt is calculated so that the target steering angle δ becomes a steering angle in the left direction. The target steering angle δt calculated in this way, or the target steering torque for obtaining the target steering angle δt, corresponds to the steering amount by the LTA. And the steering amount by the LTA corresponds to an example of the "steering assist amount" according to the present disclosure.

[0020] 2-2. Correction of Steering Assist Amount Using Curve Sign FIG. 2(A) is a diagram for explaining the problems of lane keeping support control. FIG. 2(A) illustrates a driving scene in which a curve C1 exists in front of the vehicle 100 on a driving road such as a mountain road. The curve C1 is a sharp curve. For this reason, a curve sign (warning sign) S1 for prompting the driver's attention with respect to the curve C1 is installed on the side of the road in front of the vehicle 100 before entering the curve C1.

[0021] In the vehicle 100 according to the comparative example shown in FIG. 2(A), different from the present embodiment, an LTA that does not use the recognition of the curve sign S1 of the curve C1 by the camera is executed. As a result, although the sharp curve C1 where the curve sign S1 is installed is in front of the vehicle 100, the vehicle 100 enters the curve C1 without the steering assist amount of the LTA being appropriately changed in advance in consideration of the existence of the curve C1. As a result, in this comparative example, the LTA cannot be continued during the passage of the curve C1, and the LTA has ended. Additionally, from the image information of the camera, the curvature R of the curve C1 can be obtained before entering the curve C1. However, for example, when the curve C1 is a curve that turns greatly, it may be difficult to grasp the entire curvature R of the curve C1 before entering the curve C1 only with the above driving road information.

[0022] In view of the above problems, the driving support ECU 10 executes a "recognition process" of recognizing the curve sign S using the camera 21. Specifically, in this recognition process, the ECU 10 recognizes the curve sign S by analyzing the image of the camera 21 using, for example, an image recognition AI (Artificial Intelligence) generated in advance by machine learning.

[0023] When the ECU 10 recognizes the curve sign S, it executes an "assist increase process" of increasing the steering assist amount AS of the steering actuator 30 for suppressing lane departure during curve passage compared to the case of passing the curve C without recognizing the curve sign S.

[0024] 2-2-1. First specific example FIG. 2(B) is a diagram for explaining a first specific example of the lane keeping support control according to the embodiment. In the first specific example, the target steering angle δt calculated as the "steering amount in the direction of steering the wheels toward the inside of the curve C1" corresponds to the steering assist amount AS in the above assist increase process.

[0025] In the first specific example, when a sharp curve C1 exists in front of the vehicle 1, the curve sign S1 is recognized by the recognition process as shown in FIG. 2(B). Then, by the assist increase process, the target steering angle δt is calculated to be a larger value compared to the case without recognizing the curve sign S1 (FIG. 2(A)). As a result, the steering assist amount AS when the vehicle 1 subsequently passes the curve C1 is increased compared to the case of passing the curve C1 without recognizing the curve sign S1.

[0026] According to the first specific example, it is possible to appropriately continue the LTA even when driving on a sharp curve C1.

[0027] 2-2-2. Second specific example FIG. 2(C) is a diagram for explaining a second specific example of the lane keeping support control according to the embodiment. In the second specific example, the "offset amount OS for offsetting the running position of the vehicle 1 in the lane width direction on the running lane L to the inside of the curve C1 with respect to the center of the running lane L" corresponds to the steering assist amount AS in the assist increase process described above. The offset amount OS is specified by the target travel line TL.

[0028] In the second specific example, when a sharp curve C1 exists in front of the vehicle 1, a curve sign S1 is recognized by the recognition process as shown in FIG. 2(C). Then, the increase in the steering assist amount AS by the assist increase process in the second specific example is realized by setting an offset amount OS1 that is largely offset to the inside of the curve C1 compared to the offset amount OS0 specified by the target travel line TL0 when the curve sign S1 is not recognized prior to entering the curve C1. In the example shown in FIG. 2(C), the offset amount OS0 of the target travel line TL0 is zero. That is, the target travel line TL0 is equal to the lane center line CL. However, the target travel line TL0 may be different from the lane center line CL.

[0029] According to the second specific example, by increasing the offset amount OS prior to entering the curve C1, even if the lateral deviation Dy expands toward the outside of the curve C1 during passage of the sharp curve C1, it becomes possible to facilitate the continuation of the LTA.

[0030] As described using the first and second specific examples, according to the driving support device according to the present embodiment, even when driving on a sharp curve, the lane keeping support control can be appropriately executed using the curve sign S recognized by the camera 21.

[0031] In addition, the present method that utilizes the recognition information of the curve sign S has the following advantages as compared with the method that utilizes the road information of the navigation device 60. That is, for example, when a new curve sign S is installed, it takes time until the information of the newly installed curve sign S is reflected in the road information of the navigation device 60. In contrast, according to the present method, the newly installed curve sign S can be recognized and reflected in the LTA without such a time delay. Also, in a place where the communication environment is not good, such as in a mountainous area, there is a possibility that the information of the navigation device 60 cannot be utilized. According to the present method, such a problem does not occur either.

[0032] Note that the steering assist amount AS may be both (a combination of) the steering amount (target steering angle δt) and the offset amount OS.

[0033] 2-2-3. Flow of Processing In order to execute the processing related to the LTA, the driving support ECU 10 includes, as functional blocks, a sign determination unit 13, a travel path calculation unit 14, and an assist amount calculation unit 15 (see FIG. 1). These functional blocks are realized by the cooperation of a processing circuit 11 that executes a computer program and a memory 12.

[0034] FIG. 3 is a flowchart showing the processing of the sign determination unit 13 shown in FIG. 1. The processing of this flowchart and the processing of the flowcharts shown in FIGS. 4 and 5 described later are executed in parallel by the ECU 10 (processing circuit 11). Here, the above-described first specific example in which the steering assist amount AS is the target steering angle δt as the "steering amount in the direction of steering the wheels toward the inside of the curve C1" will be mainly described.

[0035] The sign determination unit 13 determines and classifies what kind of sign the sign recognized using the camera 21 is.

[0036] Specifically, in step S100, it is determined whether a sign is detected based on the image information of the camera 21. As a result, if no sign is detected, the process of step S100 is repeated. On the other hand, if a sign is detected, the process proceeds to step S102.

[0037] In step S102, it is determined whether the detected sign is the curve sign S. As a result, if the detected sign is not the curve sign S, the process returns to step S100. On the other hand, if the detected sign is the curve sign S, the process proceeds to step S104. Additionally, the processes of steps S100 and S102 correspond to the above-mentioned "recognition process".

[0038] In step S104, a process of displaying an icon indicating the curve sign S on the meter panel 50 is executed. Specifically, the memory 12 of the ECU 10 stores data of an icon indicating the curve sign S. The process of step S104 includes a process of reading out the data of the icon indicating the curve sign S from the memory 12. The icon displayed on the meter panel 50 is, for example, a specific one icon. Further, in step S104, a process of transmitting "curve sign information Ic" to the assist amount calculation unit 15 is also executed. The curve sign information Ic includes at least information indicating that the curve sign S has been recognized by the sign determination unit 13.

[0039] Additionally, as exemplified in FIGS. 6(A) to 6(C) described later, there are various types of curve signs S. Therefore, the process of step S104 may include a process of specifying the type of the curve sign S using, for example, image recognition AI. The process of specifying the type of the curve sign S in this way also corresponds to the above-mentioned "recognition process". And the memory 12 may store data of icons indicating various curve signs S. The process of step S104 may include a process of reading out the data of the icon of the specified type of curve sign S from the memory 12 and displaying it on the meter panel 50.

[0040] In addition, the curve identification information Ic transmitted from the identification determination unit 13 to the assist amount calculation unit 15 may include identification type information Ic1 indicating the type of the curve identification S specified as described above. Specifically, the identification type information Ic1 may include, for example, information on the total angle a, which will be described later together with FIGS. 6(A) to 6(C), for each type of the curve identification S. Further, the identification type information Ic1 may include, for example, turning direction information indicating whether the curve identification S is a curve that turns only to one of the left and right or a curve that turns to both the left and right, for each type of the curve identification S.

[0041] FIG. 4 is a flowchart showing the processing of the travel path calculation unit 14 shown in FIG. 1. The travel path calculation unit 14 calculates the curvature R of the travel path ahead of the vehicle 1 using the travel path information based on the image of the camera 21. The travel path information includes, for example, the left and right white lines WL partitioning the travel lane L and the lane center line CL. As already described, the curvature R is the curvature of the curve of the lane center line CL of the travel lane L of the vehicle 1.

[0042] Specifically, in step S200, the travel path information is acquired from the camera 21. Next, in step S202, it is determined whether there is travel path information in the navigation device 60 (that is, whether the travel path information has been received by the ECU 10).

[0043] As a result, when there is also travel path information in the navigation device 60, the curvature R is calculated from the travel path information of each of the camera 21 and the navigation device 60 (step S204). On the other hand, when there is no travel path information in the navigation device 60, the curvature R is calculated from only the travel path information of the camera 21 (step S206). These calculations of the curvature R can be performed using known methods. The curvature R calculated in step S204 or S206 is transmitted from the travel path calculation unit 14 to the assist amount calculation unit 15.

[0044] FIG. 5 is a flowchart showing the processing of the assist amount calculation unit 15 shown in FIG. 1. When the marking determination unit 13 recognizes that the marking is the curve marking S, the assist amount calculation unit 15 increases the steering assist amount AS based on the curvature R calculated by the travel path calculation unit 14 to be greater than the normal value AS0.

[0045] Specifically, in step S300, the curve marking information Ic transmitted from the marking determination unit 13 is acquired. Next, in step S302, the curvature R transmitted from the travel path calculation unit 14 is acquired.

[0046] Next, in step S304, it is determined whether or not the curve marking S exists based on the curve marking information Ic (that is, whether or not the curve marking S is recognized). As a result, if the curve marking S does not exist, the process proceeds to step S306.

[0047] In step S306, the normal value AS0 of the steering assist amount AS of the LTA is calculated. Specifically, in the above first specific example, the normal value δt0 of the target steering angle δt corresponding to the normal value AS0 is calculated based on the lateral deviation Dy and the yaw angle θy together with the curvature R by, for example, the method described in section 2-1 of the basic configuration of the LTA. In the second specific example where the steering assist amount AS is the offset amount OS, the normal value OS0 of the offset amount OS corresponding to the normal value AS0 is specified based on the target travel line TL0. For example, when the target travel line TL0 is equal to the lane center line CL, the offset amount OS0, which is zero, corresponds to the normal value AS0.

[0048] On the other hand, when the curve sign S exists (step S304; Yes), the process proceeds to step S308. In step S308, the corrected steering assist amount AS1 using the curve sign S is calculated. Specifically, after calculating the normal value AS0 in the same manner as the process of step S306, the steering assist amount AS1 is calculated by multiplying the normal value AS0 by the correction coefficient K. In the second specific example where the steering assist amount AS is the offset amount OS, the offset amount OS1 corresponding to the corrected steering assist amount AS1 is calculated by multiplying the offset amount OS0 corresponding to the normal value AS0 by the correction coefficient K.

[0049] (Various setting examples of the correction coefficient K) The correction coefficient K is a positive value and can be set using various methods as follows, for example.

[0050] The first setting example described first targets the first specific example in which the target steering angle δt is used as the steering assist amount AS. Under the condition where the vehicle speed can be regarded as constant, the lateral acceleration Gy of the vehicle 1 during turning can be specified by the steering angle δ. In this setting example, the relationship among such vehicle speed, steering angle δ, and lateral acceleration Gy is used. Specifically, the correction coefficient K is determined such that, at the current vehicle speed, the target steering angle δt1 corresponding to the corrected steering assist amount AS1 generates a lateral acceleration Gy1 (for example, 0.3G) that is a predetermined amount higher than the normal lateral acceleration Gy0 (for example, 0.2G). The normal lateral acceleration Gy0 is the value of the lateral acceleration Gy generated when steering is performed using the normal value δt0.

[0051] Alternatively, the correction coefficient K may be, for example, a pre-set fixed value.

[0052] Also, in an example where the curve sign information Ic includes the sign type information Ic1, the correction coefficient K may be set using, for example, the following method. FIGS. 6(A) to 6(C) are diagrams each showing a specific example of the curve sign S, namely curve signs S1 to S3. The curve mark M1 in the curve sign S1 illustrates a curve that bends only to one side (e.g., the left) of the left and right. The curve mark M2 in the curve sign S2 illustrates a curve that bends only to one side (e.g., the right) of the left and right, and more specifically, a curve that greatly turns to the right. The curve mark M3 in the curve sign S3 illustrates a curve that bends to both sides of the left and right, and more specifically, a curve that greatly turns to both sides of the left and right.

[0053] The angle a1 in FIG. 6(A) indicates the angle of the arc ( = total angle) included in the curve mark M1. The angle a2 in FIG. 6(B) indicates the angle of the arc ( = total angle) included in the curve mark M2. The angles a3_1 and a3_2 in FIG. 6(C) indicate the respective angles of the two arcs included in the curve mark M3, and the sum of the angles a3_1 and a3_2 is the total angle a3. As can be seen by comparing the respective figures, the total angle a of the arc is the largest for the curve mark M3, followed in order by the curve marks M2 and M1. In other words, the total angle a indicates the magnitude of the degree of turning of the curve represented by the curve mark M. This degree of turning is the largest for the curve mark M3, followed in order by the curve marks M2 and M1.

[0054] The correction coefficient K may be set as follows in consideration of the type of the curve sign S. That is, the correction coefficient K may be set to be larger when the total angle a is greater than a predetermined threshold (for example, a2 and a3) than when the total angle a is less than or equal to the threshold (for example, a1). Alternatively, the correction coefficient K may be set to increase as the total angle a increases, for example. According to these setting examples, the steering assist amount AS1 after correction becomes larger when the total angle a is large than when the total angle a is small. Thereby, the steering assist amount AS1 can be appropriately determined according to the degree of turning around the curve C by using the recognition result of the curve sign S. As a result, the LTA can be continued more appropriately compared with an example where this point is not considered. Additionally, the total angle a can be obtained, for example, by reading information on the total angle a about the recognized curve sign S from the sign type information Ic1 in the memory 12. Alternatively, the total angle a may be directly obtained, for example, by analyzing an image of the curve mark M of the curve sign S obtained by the camera 21.

[0055] Further, the correction coefficient K may be set as follows in consideration of the type of the curve sign S. That is, when the curve mark M indicates a curve that bends both to the left and right (for example, M3), it may be set to be larger than when the curve mark M indicates a curve that bends only to one of the left and right (for example, M1 and M2). As a result, the steering assist amount AS1 after correction becomes larger when the curve mark M indicates a curve that bends both to the left and right than when the curve mark M indicates a curve that bends only to one of the left and right. According to this setting example, by using the recognition result of the curve sign S, the steering assist amount AS1 can be appropriately determined according to whether the curve C is a continuous curve (more specifically, according to whether the curve C is a series of sharp curves that require a change in the steering direction). As a result, compared with an example where this point is not considered, the LTA can be continued more appropriately. In addition, the turning direction information of the curve C can be obtained, for example, by reading the turning direction information about the recognized curve sign S from the sign type information Ic1 in the memory 12. Alternatively, the turning direction information may be directly obtained, for example, by analyzing the image of the curve mark M of the curve sign S obtained by the camera 21.

[0056] In FIG. 5, in step S310 following step S306 or S308, the steering assist amount AS (that is, AS0 or AS1) is transmitted to the EPS-ECU 31. As a result, the EPS-ECU 31 controls the steering actuator 30 so as to realize the steering assist amount AS. Note that the driving support control of the vehicle 1 may include, together with the LTA, for example, an automatic acceleration / deceleration control (for example, adaptive cruise control) that automatically performs the acceleration and deceleration of the vehicle 1. And when the automatic acceleration / deceleration control is executed together with the LTA, the information on the steering assist amount AS may also be transmitted to the brake ECU 40 for the control of the deceleration of the vehicle 1.

Explanation of Signs

[0057] 1 Vehicle, 10 Driving Support ECU, 11 Processing Circuit, 12 Memory, 13 Sign Judgment Unit, 14 Travel Route Calculation Unit, 15 Assist Amount Calculation Unit, 21 Camera, 30 Steering Actuator

Claims

1. A driving assistance device for assisting a driver in driving a vehicle, comprising: a recognition sensor for recognizing the situation in front of the vehicle; a steering actuator for steering the vehicle; an electronic control unit for controlling the steering actuator so as to suppress lane departure of the vehicle from the traveling lane; The electronic control unit: uses the recognition sensor to recognize a curve sign for prompting the driver's attention to a curve in front of the vehicle; when the curve sign is recognized, increases the steering assist amount of the steering actuator for suppressing lane departure during passage of the curve as compared with the case of passing the curve without recognition of the curve sign. A driving assistance device characterized by the above.

2. The driving assistance device according to claim 1, wherein the steering assist amount is at least one of a steering amount in a direction of steering the wheels toward the inside of the curve and an offset amount for offsetting the traveling position of the vehicle in the lane width direction on the traveling lane toward the inside of the curve with respect to the center of the traveling lane. A driving assistance device characterized by the above.

3. The driving assistance device according to claim 1 or 2, wherein the electronic control unit increases the steering assist amount when the total angle of the arcs included in the curve marks in the recognized curve sign is large as compared with the case where the total angle is small. A driving assistance device characterized by the above.

4. The driving assistance device according to claim 1 or 2, wherein the electronic control unit increases the steering assist amount when the curve mark in the recognized curve sign indicates a curve that bends in both the left and right directions as compared with the case where the curve mark indicates a curve that bends only in one of the left and right directions. A driving assistance device characterized by the above. ​

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