JP7729271B2 - Driving assistance device, driving assistance method, and driving assistance program - Google Patents

Description

The present invention relates to a driving assistance device installed in a vehicle, and in particular to a driving assistance device with a lane departure prevention function that prevents the vehicle from departing from the lane in which it is currently traveling.

In recent years, driving assistance devices have been developed to assist drivers in driving a vehicle by determining whether there is a risk that the vehicle will deviate from its driving lane, and if there is a risk of deviation, they provide audio and visual warnings, and also perform lane departure prevention control, such as generating a steering force in the vehicle's steering device in the direction opposite to the direction the vehicle is deviating.

However, if the driver intentionally deviates from the vehicle's lane, the driver may find the activation of the lane departure prevention control annoying. In light of this issue, technology has been disclosed that, when detecting a toll booth, interchange, or turning point leading to a parking or service area on a highway, determines that there is a high possibility that the vehicle will deviate from the lane due to the driver's intention, and prohibits lane departure prevention control (see, for example, Patent Documents 1 and 2).

JP 2012-116436 A Japanese Patent Application Laid-Open No. 2005-18211

However, if lane departure prevention control is uniformly prohibited depending on the location of the vehicle, it may not provide optimal driving assistance.

A driving assistance device according to a first aspect is a driving assistance device that executes a plurality of controls to prevent a vehicle from deviating from its lane, and the controls include at least issuing an alert to the driver and steering assistance, and is characterized in that, when a first condition is met that the vehicle speed is slower than a speed Vth based on a radius of curvature R of a curve on the road on which the vehicle is traveling, and a second condition that the vehicle is traveling in a predetermined area, at least the alert is prohibited, and when the first condition, the second condition, and a third condition is met that the driver performs a predetermined braking operation or the deceleration of the vehicle is equal to or greater than a predetermined value, at least the alert and the steering assistance are prohibited .

The driving assistance device according to the second aspect is characterized in that, when the first condition, the second condition, and the third condition are all satisfied, all of the plurality of controls are suppressed.

A driving assistance device according to a third aspect is characterized in that the predetermined area is an area from an exit of a highway to a toll gate.

A driving assistance control method according to a fourth aspect is a driving assistance control method that executes a plurality of controls to prevent a vehicle from deviating from its lane, the controls including at least warning the driver and steering assistance, and is characterized in that, when a first condition is met that the vehicle speed is slower than a speed Vth based on a radius of curvature R of a curve on a road on which the vehicle is traveling, and a second condition is met that the vehicle is traveling in a predetermined area, at least the warning is prohibited, and when the first condition, the second condition, and a third condition is met that the driver performs a predetermined braking operation or the deceleration of the vehicle is equal to or greater than a predetermined value, at least the warning and the steering assistance are prohibited .

A driving assistance control program according to a fifth aspect is a driving assistance control program that executes a plurality of controls to prevent a vehicle from deviating from its lane, the controls including at least warning the driver and steering assistance, and is characterized in that, when a first condition is met that the vehicle speed is slower than a speed Vth based on a radius of curvature R of a curve on the road on which the vehicle is traveling, and a second condition is met that the vehicle is traveling in a predetermined area, at least the warning is prohibited, and when the first condition, the second condition, and a third condition is met that the driver performs a predetermined braking operation or the deceleration of the vehicle is equal to or greater than a predetermined value, at least the warning and the steering assistance are prohibited .

The driving assistance device of the present invention can suppress some or all of the lane departure prevention control only in certain scenarios when traveling through areas where lane departure prevention control is not required, thereby eliminating the annoyance felt by the driver and allowing driving assistance to continue.

1 is a block diagram showing a configuration of a driving assistance device according to an embodiment; 1 is a table summarizing conditions and concepts according to examples. FIG. 10 is a diagram illustrating the relationship between the radius of curvature of a driving lane and a vehicle speed threshold value. 10 is a flowchart illustrating an execution procedure according to an embodiment.

The following describes an exemplary lane departure prevention device for a moving vehicle according to this embodiment, with reference to the drawings. The configuration of the following embodiment is merely an example, and the individual components, flowcharts, etc. are not intended to limit the technical scope of the invention to those components alone.

<General configuration of driving assistance device>
The configuration of a driving assistance device according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the configuration of a driving assistance device according to an embodiment.

The driving assistance device 100 is composed of a lane departure prevention assistance unit 1001 that performs lane departure prevention assistance to prevent the vehicle 1 from departing from the lane in which it is currently traveling, and a lane departure prevention assistance suppression unit 1002 that suppresses the lane departure prevention assistance based on predetermined conditions.

The driving assistance device 100 is electrically connected to a camera 101, a navigation system 102, a vehicle speed sensor 103, and a brake pedal 104. Furthermore, the driving assistance device 100 is electrically connected to an alarm device 105 and a steering device 106. Each function of the driving assistance device 100 in FIG. 1 is realized by the CPU and memory (ROM, RAM, etc.) of one or more ECUs (not shown).

The periphery recognition unit 101 recognizes the situation around the vehicle 1 based on the output of detection means capable of detecting the situation outside the vehicle 1, such as millimeter-wave radar, a camera, or LiDAR (Light Detection and Ranging). In particular, the periphery recognition unit 101 recognizes the white lines that define the lane lines based on camera images.

An example of a white line recognition method based on camera images will be described below. The camera, which may be a CCD camera or CMOS camera, is installed, for example, above the center of the windshield inside the vehicle, with its optical axis aligned forward. It captures an image of the road surface ahead of the vehicle, including the white lines on both sides of the lane, and outputs the captured road image data to the surroundings recognition unit 101.

The surroundings recognition unit 101 performs image processing on the road image data. After performing well-known binarization and edge extraction processes on the road image data, it performs pattern matching processing and performs pattern recognition of white lines based on a model corresponding to the white line template.

The location information acquisition unit 102 includes, for example, a navigation device that includes a map database, and an infrastructure information receiving device that obtains traffic volume information and the like from an external source. The navigation device can obtain highly accurate location information for the vehicle by matching the results of measurements of the vehicle's location using GPS or autonomous navigation with roads recorded in the map database. Alternatively, the infrastructure information receiving device may receive traffic information and the like from the infrastructure, and estimate the vehicle's location information based on that information.

The vehicle state acquisition unit 103 acquires vehicle speed and acceleration from a vehicle speed sensor and acceleration sensor mounted on the vehicle. The braking device 104 has a brake pedal and decelerates the vehicle through brake pedal operation by the driver. Operation information such as whether the driver has operated the brake pedal, the amount of depression, and the depression speed are transmitted to the driving assistance device.

The warning device 105 is, for example, a display device or speaker. The driving assistance device issues a warning to the driver by displaying a specified indicator or text on the display device or controlling the speaker to emit a warning sound. The driving assistance device may also issue a warning to the driver by vibrating the steering wheel.

The steering device 106 has, for example, a steering actuator, and the driving assistance device controls the steering actuator to generate a steering force for the vehicle.

<Lane Departure Prevention Assist>
The following describes the operation of the lane departure prevention assist performed by the lane departure prevention assist unit 1001 to prevent the vehicle 1 from departing from the lane in which it is currently traveling. In this embodiment, the lane departure prevention assist is performed by the CPU executing a control program stored in the memory of an ECU (not shown). The control program may also be acquired from an external server or the like via a communication device (not shown).

The lane departure prevention support unit 1001 calculates the distance in the width direction of the road between the white lines pattern-recognized by the periphery recognition unit 101 and the vehicle 1 using a known method. For example, it calculates the distance in the width direction of the vehicle 1 from each of the left and right white lines.

Next, the lane departure prevention support unit 1001 compares the widthwise distance of the vehicle 1 from each of the left and right white lines with a preset first threshold value, and determines whether both are equal to or greater than the first threshold value. The first threshold value is a threshold value that can be used to determine that the possibility of the vehicle 1 deviating from its travel lane is sufficiently low if the distance between the white lines and the vehicle 1 is equal to or greater than this value.

Therefore, if the lane departure prevention support unit 1001 determines that at least one of the widthwise distances of the vehicle 1 from the left and right white lines is narrower than the first threshold, it determines that there is a risk that the vehicle 1 will deviate from its driving lane.

If the lane departure prevention assist unit 1001 determines that the vehicle 1 is at risk of deviating from its lane, it controls the steering device 106 of the vehicle 1 so that a steering force is generated in the direction opposite to the direction in which the vehicle 1 is deviating. However, if it determines that the widthwise distance of the vehicle 1 from each of the left and right white lines is equal to or greater than the first threshold, it terminates control of the steering device 106.

Furthermore, in this embodiment, priority is given to steering operation by the driver over control of the steering device 106 by the driving assistance device 100. Therefore, even if lane departure prevention assistance is performed by controlling the steering device 106, if the driver performs steering operation in the direction of lane departure, the widthwise distance of the vehicle 1 from the white line will become even narrower than the first threshold value, increasing the risk that the vehicle 1 will depart from its driving lane.

If the widthwise distance of vehicle 1 from the white line becomes narrower than the first threshold, the lane departure prevention support unit 1001 compares the widthwise distance of vehicle 1 from each of the left and right white lines with a second threshold that is smaller than the first threshold, and determines whether both are maintained at or above the second threshold. The second threshold is a threshold that can be used to determine that there is a high possibility that vehicle 1 will deviate from its driving lane if the distance between vehicle 1 and the white line is not maintained at or above this value.

Therefore, when the lane departure prevention assist unit 1001 determines that at least one of the widthwise distances of the vehicle 1 from the left and right white lines is narrower than the second threshold, it issues a warning to the driver via the warning device 105. For example, it outputs a warning message on the display indicating that the vehicle 1 is at risk of deviating from its lane, and outputs a warning sound from the speaker. It may also vibrate the steering wheel to alert the driver.

In the above embodiment, lane departure prevention assistance was performed in the order of "controlling the steering device" and "issuing a warning to the driver" as the widthwise distance of the vehicle 1 from the white line narrowed. However, the order of "controlling the steering device" and "issuing a warning to the driver" may be reversed, or they may occur simultaneously. Furthermore, the steering device control and driver warning may be changed based on the widthwise distance.

<Lane Departure Prevention Assist Unit>
However, if lane departure prevention assistance is always implemented in a situation where the vehicle 1 deviates from the driving lane at the driver's will, there is a concern that an alarm will be activated even when the driver deviates from the driving lane at the driver's will, which will be a source of annoyance to the driver.

Therefore, the lane departure prevention assist suppression unit 1002 suppresses unnecessary lane departure prevention assist when certain conditions are met when traveling through a specified location. However, as shown in the following examples, embodiments of the present invention also include modes in which suppression is prohibited.

The specific processing performed by the lane departure prevention assist suppression unit 1002 will be explained below using Figure 2. Figure 2 is a table summarizing the conditions and concepts for lane departure prevention assist suppression according to this embodiment.

The shaded area in Figure 2 represents the content of the lane departure prevention assist suppression, which changes from A to D depending on the conditions. Condition A indicates that the vehicle's driving area is outside a specified area, in which case lane departure prevention assist is not prohibited or suppressed and normal lane departure prevention assist is executed. Outside the specified area, it is unlikely that the driver will cause vehicle 1 to deviate from its driving lane, so by executing normal lane departure prevention assist, lane departure can be suppressed and the driver's driving can be optimally supported.

2, when the driving area of the host vehicle is a predetermined area and the vehicle speed is equal to or greater than a predetermined speed Vth, the lane departure prevention assist is not prohibited or suppressed, and normal lane departure prevention assist is performed. Speed Vth means the maximum vehicle speed at which the vehicle can safely complete a turn in the driving lane. Under condition B, a situation may occur in which the driver intends to cause the vehicle 1 to deviate from the driving lane, but the vehicle speed is high and it is determined that the vehicle cannot safely complete the turn, so normal lane departure prevention assist is performed.

As shown in Figure 3, the larger the radius of curvature R, the gentler the curve, and therefore the higher the maximum vehicle speed (speed Vth) at which the vehicle can safely complete the turn. Furthermore, the radius of curvature R can be obtained by calculation using a known method based on the vehicle's position information from the navigation device in the position information acquisition unit 102, road information in a map database, and camera information from the surroundings recognition unit 101.

In Figure 2, C prohibits or suppresses the operation of both the "controlling the steering device" and "issuing a warning to the driver" functions of the lane departure prevention assist under the following conditions: the vehicle is traveling in a specified area, the vehicle speed is less than a specified speed Vth, and the driver is braking or the vehicle's deceleration is equal to or greater than a specified value. Under condition C, lane departure prevention assist is prohibited or suppressed in situations where the vehicle can be driven safely and it is determined that the driver intends to decelerate, thereby eliminating the annoyance felt by the driver due to lane departure prevention assist while allowing driving assistance to continue.

In Figure 2, D prohibits or suppresses the "issue warning to the driver" lane departure prevention assist function when the vehicle is traveling in a specified area, the vehicle speed is less than a specified speed Vth, and the driver is not braking or the vehicle's deceleration is less than a specified value. Under condition D, the vehicle speed is such that the driver can safely complete the turn by operating the driver, but it cannot be determined that the driver intends to decelerate. Therefore, by activating the "control the steering device" lane departure prevention assist function, it is possible to continue driving assistance while at the same time reducing the annoyance felt by the driver due to the lane departure prevention assist.

Alternatively, an embodiment may be adopted in which "controlling the steering device" of the lane departure prevention assist is prohibited or suppressed, and "issuing an alert to the driver" is activated. In this case, driving assistance cannot be continued, but the driver can be informed that the vehicle is about to depart while minimizing any discomfort felt by the driver due to the driving assistance.

The specific processing performed by the lane departure prevention assist suppression unit 1002 will be explained below using a flowchart. Figure 4 is a flowchart showing the processing performed by the lane departure prevention control according to this embodiment. The program according to the flowchart is pre-stored in an ECU (not shown) and is repeatedly executed by the ECU. The control program may also be obtained from an external server or the like via a communication device (not shown).

At S500, the lane departure prevention assistance described above is executed. Specifically, the lane departure prevention assistance unit 1001 controls the steering device 106 to generate a steering force in the direction opposite to the direction in which the vehicle 1 is deviating, and issues a warning to the driver.

In S501, it is determined whether vehicle 1 is traveling in a predetermined area. The predetermined area is, for example, the area from the expressway exit to the toll gate, and this determination is made based on the vehicle 1's position information obtained by the position information acquisition unit 102. If the determination is negative, the process returns to S500 (A in Figure 2) and normal lane departure prevention assistance is executed. On the other hand, if the determination is positive, the process proceeds to S502.

In S502, it is determined whether the vehicle speed of vehicle 1 is lower than the speed Vth based on the radius of curvature R. If the determination is negative, the vehicle speed is high and there is a high possibility that the vehicle will not be able to safely complete the curve without lane departure prevention assistance, so the process returns to S500 (B in Figure 2) and normal lane departure prevention assistance is performed. On the other hand, if the determination is positive, the process proceeds to S503.

In S503, it is determined whether the driver is applying the brakes, or whether the deceleration of vehicle 1 is equal to or greater than a predetermined value. Specifically, it is determined whether the driver is applying the brakes based on information such as the amount and speed of brake pedal depression sent from the brake device 104 to the driving assistance device 100. Alternatively, the deceleration of vehicle 1 may be calculated based on acceleration information of vehicle 1 sent from the vehicle state acquisition unit 103 to the driving assistance device 100, and a determination may be made whether it is equal to or greater than a predetermined value. The predetermined value is set to a value that can be used to determine that the driver intends to decelerate. If a positive determination is made, the process proceeds to S504 (C in Figure 2), and if a negative determination is made, the process proceeds to S505 (D in Figure 2).

At S504, the lane departure prevention assist functions of "controlling the steering device" and "issuing a warning to the driver" are both prohibited. By prohibiting lane departure prevention assist in a safe situation and when it is determined that the driver intends to decelerate, it is possible to eliminate the annoyance felt by the driver due to lane departure prevention assist while also allowing driving assistance to continue.

In S505, the lane departure prevention assist function "issue a warning to the driver" is prohibited. Although the vehicle speed is such that the driver can safely complete the turn by operating the vehicle, S503 does not determine that the driver intends to decelerate. Therefore, by activating the lane departure prevention assist function "control the steering device," it is possible to continue driving assistance while at the same time alleviating at least some of the annoyance felt by the driver by the lane departure prevention assist.

The flowchart in Figure 4 mainly describes a configuration in which lane departure prevention assistance, which can be a nuisance to the driver, is prohibited, but it is also possible to suppress some or all lane departure prevention assistance, and the configuration is not necessarily limited to the above example.

For example, when "controlling the steering device" in lane departure prevention assist is suppressed, the steering force in the direction opposite to the direction of departure may be reduced compared to the steering force used in normal lane departure prevention assist. Furthermore, by setting the first threshold lower than the normal value, the control of the steering device may be delayed compared to normal lane departure prevention assist.

For example, when suppressing the "warning to the driver" in lane departure prevention assistance, whereas normal lane departure prevention assistance sounds an alarm and displays a specified indicator or text on the display device, the alarm may be prohibited and only the alarm displayed on the display device may be suppressed. Furthermore, by setting the second threshold lower than the normal value, the warning to the driver may be delayed compared to normal lane departure prevention assistance.

The above describes an embodiment of the present invention, but the present invention is not limited to the above example and various modifications are possible.

REFERENCE SIGNS LIST 100 Driving assistance device 101 Surroundings recognition device 102 Position information acquisition device 103 Vehicle state acquisition device 104 Brake device 105 Warning device 106 Steering device

Claims (5)

A driving assistance device that performs a plurality of controls to prevent a vehicle from deviating from a driving lane,
The control includes at least a warning to the driver and steering assistance,
prohibiting at least the warning when both a first condition that the vehicle speed is lower than a speed Vth based on a curvature radius R of a curve on a road on which the vehicle is traveling and a second condition that the vehicle is traveling in a predetermined area are satisfied;
a driving assistance device that prohibits at least the warning and the steering assistance when all of the first condition, the second condition, and a third condition that the driver performs a predetermined brake operation or the deceleration of the vehicle is equal to or greater than a predetermined value are satisfied . If the first condition, the second condition, and the third condition are all met,
The driving assistance device according to claim 1 , wherein all of the plurality of controls are suppressed. The driving assistance device of claim 1, wherein the specified area is the area from the expressway exit to the toll gate. A driving assistance control method that executes a plurality of controls to suppress deviation of a vehicle from a driving lane,
The control includes at least a warning to the driver and steering assistance,
prohibiting at least the warning when both a first condition that the vehicle speed is lower than a speed Vth based on a curvature radius R of a curve on a road on which the vehicle is traveling and a second condition that the vehicle is traveling in a predetermined area are satisfied;
a driving assistance control method characterized by prohibiting at least the warning and the steering assistance when all of the first condition, the second condition, and a third condition that the driver performs a predetermined braking operation or the deceleration of the vehicle is equal to or greater than a predetermined value are satisfied . A driving assistance control program that executes a plurality of controls to prevent a vehicle from deviating from a driving lane,
The control includes at least a warning to the driver and steering assistance,
prohibiting at least the warning when both a first condition that the vehicle speed is lower than a speed Vth based on a curvature radius R of a curve on a road on which the vehicle is traveling and a second condition that the vehicle is traveling in a predetermined area are satisfied;
A driving assistance control program characterized by prohibiting at least the warning and the steering assistance when all of the first condition, the second condition, and a third condition that the driver performs a predetermined brake operation or the deceleration of the vehicle is equal to or greater than a predetermined value are met .