Drive supporting device

Abstract

To provide a drive supporting device capable of suppressing a frequent change of a drive supporting level.SOLUTION: A drive supporting device comprises: an on-vehicle sensor that acquires target information about a target located around the own vehicle; and a processor capable of executing a drive supporting process that determines a drive supporting level, which is a degree of support for a driving operation, based on the target information, and that controls the own vehicle so that the drive supporting level of assistance is provided to a driver. When a predefined first condition is established as a condition for lowering the drive supporting level while the processor is executing a drive supporting process of a predetermined first level, the processor starts execution of a drive supporting process of a second level, which is lower than the first level, instead of the drive supporting process of the first level, and during a period in which a predefined second condition is established as a condition for determining that the first condition is likely to be established, the processor maintains the drive supporting level at the second level.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a driving assistance device that assists a driver in driving a vehicle. [Background technology]

[0002] A driving assistance device that assists in driving the vehicle has been proposed (see, for example, Patent Document 1 below). This driving assistance device (hereinafter referred to as the "conventional device") has an automatic driving function that automatically moves the vehicle forward. When automatic driving control is being executed, this conventional device controls the braking device (and / or drive device) of the vehicle so that the distance between the vehicle and the preceding vehicle is increased when there is a high possibility that another vehicle will enter (cut in) between the vehicle and the preceding vehicle (the vehicle located immediately in front of the vehicle). This makes it easier for the other vehicle to enter between the vehicle and the preceding vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-153153 A Summary of the Invention

[0004] Incidentally, a driving assistance device having, for example, a hands-on mode and a hands-off mode as operation modes of the automatic driving control has been proposed. In either operation mode, the steering angle is automatically adjusted. In the hands-on mode, the driver needs to lightly touch the steering wheel. On the other hand, in the hands-off mode, the driver is allowed to take his / her hands off the steering wheel (hands-off). However, if a predetermined condition (cancellation condition) is met in the hands-off mode, the mode is forcibly changed from the hands-off mode to the hands-on mode. For example, if the distance between the host vehicle and another vehicle that has entered between the host vehicle and the preceding vehicle in the hands-off mode becomes less than a threshold value, the cancellation condition is met. In this way, the driving assistance device lowers the driving assistance level when the predetermined condition is met.

[0005] In this case, in a scene where a cancellation condition is satisfied, there is a high possibility that the same cancellation condition will be satisfied repeatedly within a short period of time thereafter. If the driving assistance device is configured to return the driving assistance level to the original level when the cancellation condition is no longer satisfied, the driving assistance level may be frequently changed. The driver may find frequent changes in the driving assistance level (chattering) annoying.

[0006] An object of the present invention is to provide a driving assistance device that can prevent the driving assistance level from being changed frequently.

[0007] In order to solve the above problem, a driving assistance device (1) of the present invention assists the driving operation of a vehicle. The driving assistance device includes an on-board sensor (20) that acquires target information related to targets located around the vehicle (V), and a processor (10) capable of executing a driving assistance process that determines a driving assistance level, which is a degree of assistance for the driving operation, based on the target information, and controls the vehicle so that assistance of the driving assistance level is provided to the driver. The processor is configured to start executing a driving assistance process of a second level lower than the first level instead of the driving assistance process of the first level when a first condition (Xn1) that is predefined as a condition for lowering the driving assistance level is satisfied during the execution of a driving assistance process of a predetermined first level, and to maintain the driving assistance level at the second level during a period in which a second condition (Xn2) that is predefined as a condition for determining that a situation is one in which the first condition is likely to be satisfied is satisfied.

[0008] According to the driving assistance device of the present invention, after the driving assistance level is lowered from the first level to the second level, in a situation where the first condition is likely to be satisfied, the driving assistance level of the second level is maintained to be provided to the driver. Thus, compared to the conventional device, the driving assistance level is prevented from being changed frequently.

[0009] In a driving assistance device according to one embodiment of the present invention, when the processor determines that there is a high possibility that another vehicle traveling in a second driving lane adjacent to a first driving lane in which the host vehicle is traveling will enter the first driving lane, the processor executes a distance adjustment process to control the drive device and / or braking device of the host vehicle so that the other vehicle can enter the area immediately in front of the host vehicle, and when the distance (Δd1) between the host vehicle and the other vehicle or the predicted time (TTC1) until contact between the host vehicle and the other vehicle becomes less than a threshold value while the vehicle distance adjustment process is being executed, the processor determines that the first condition is met.

[0010] According to this, when there is a high possibility that another vehicle will enter the area immediately in front of the vehicle and there is a high possibility that the vehicle will come into contact with the other vehicle, the driving assistance level is lowered. This allows the driver to smoothly start an operation to avoid the emergency in the event of an emergency (for example, when the vehicle and the other vehicle suddenly approach each other).

[0011] In a driving assistance device according to another aspect of the present invention, the processor determines that the second condition is satisfied when the host vehicle is traveling in a merging section of a travel lane.

[0012] In the merging section, there is a possibility that a plurality of other vehicles may successively enter the area immediately in front of the host vehicle, and it is highly likely that the first condition will be satisfied relatively frequently. According to the present invention, while traveling in the section, the driving assistance level is maintained at the second level. In other words, frequent changes in the driving assistance level are suppressed.

[0013] In a driving assistance device according to another aspect of the present invention, the processor determines that the second condition is satisfied in a situation in which there is a high possibility that a vehicle different from the other vehicle will enter the area.

[0014] A scene is assumed in which the driving assistance level is lowered as a trigger when a vehicle (first other vehicle) that is about to enter an area immediately in front of the vehicle approaches the vehicle, and then another vehicle (second other vehicle) is about to enter the area. In this case, even if the first condition is not satisfied at the present time for the second other vehicle, there is a high possibility that the first condition will be satisfied thereafter. According to the driving assistance device of this aspect, in the scene, the driving assistance level is maintained at the second level. That is, frequent changes in the driving assistance level are suppressed.

[0015] In a driving assistance device according to another aspect of the present invention, the processor measures the elapsed time (Δt) from a first point in time at which it is determined that the first condition is satisfied, and if the other vehicle cannot be detected after the first point in time, it determines that the second condition is satisfied when the elapsed time is less than a threshold value (Δtth).

[0016] For example, at night or in rainy weather, it may be difficult for the on-board sensor to accurately recognize other vehicles. In this case, the driving assistance level is maintained at the second level when the elapsed time is less than a threshold value (for example, the average time required for a general vehicle to change lanes). That is, frequent changes in the driving assistance level are suppressed. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a block diagram of a driving assistance device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view of the merging section of the expressway and its surroundings. [Diagram 3] FIG. 3 is a plan view showing a section of an expressway other than the merging section. [Figure 4] FIG. 4 is a flow chart of a program for setting the flag FH. [Diagram 5] FIG. 5 is a flowchart of a program for setting the flag FXn. [Figure 6]FIG. 6 is a flowchart of a program for determining whether a particular condition is met. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] (Overview) A driving assistance device 1 according to one embodiment of the present invention is mounted on a vehicle V (hereinafter referred to as "host vehicle"). The driving assistance device 1 assists the driver in driving operations. For example, the driving assistance device 1 has a function (automatic driving function) of executing automatic driving control for controlling the host vehicle so that the host vehicle runs automatically. The driving assistance device 1 changes the degree of assistance for driving operations (driving assistance level) depending on the situation.

[0019] (Specific Configuration) As shown in FIG. 1, the driving assistance device 1 includes a driving assistance ECU 10, an in-vehicle sensor 20, a drive device 30, a braking device 40, and a steering device 50.

[0020] The driving assistance ECU 10 includes a CPU 10a, a ROM 10b, a RAM 10c, a timer 10d, etc. The driving assistance ECU 10 is connected to other ECUs (for example, ECUs of a drive device 30, a braking device 40, and a steering device 50, which will be described later) via a CAN.

[0021] The on-board sensor 20 includes a radar 21, a sonar 22, and a camera 23 as surrounding sensors for acquiring information (target information) about targets present around the host vehicle.

[0022] The radar 21 includes a transmission / reception unit and a signal processing unit. The transmission / reception unit emits millimeter wave band radio waves (hereinafter referred to as "millimeter waves") forward of the vehicle and receives millimeter waves (reflected waves) reflected by a three-dimensional object located within the emission range. The signal processing unit recognizes the distance between the vehicle and the three-dimensional object, the relative position (direction) of the three-dimensional object with respect to the vehicle, and the like based on the time from when the transmission / reception unit emits the millimeter waves to when it receives the reflected waves, the phase difference between the transmitted millimeter waves and the received reflected waves, the attenuation of the reflected waves, and the like, and transmits the recognition result to the driving assistance ECU 10.

[0023] The sonar 22 intermittently emits ultrasonic waves to the surrounding area of ​​the vehicle and receives ultrasonic waves (reflected waves) reflected by a three-dimensional object. The sonar 22 recognizes the distance between the vehicle and the three-dimensional object, the relative position (direction) of the three-dimensional object with respect to the vehicle, etc. based on the time from when the ultrasonic waves are transmitted to when the reflected waves are received, and transmits the recognition result to the driving assistance ECU 10.

[0024] The camera 23 includes an imaging device and an image analysis device. The imaging device has, for example, a built-in CCD. The imaging device is installed at the front of the vehicle. The imaging device captures the foreground of the vehicle at a predetermined frame rate to obtain image data. The image analysis device analyzes the image data and recognizes targets and signs present around the vehicle from the image. For example, the image analysis device recognizes other vehicles, lane marks (division lines, curbs, median strips, etc. that divide the driving lanes), etc., and transmits the recognition results to the driving assistance ECU 10. The image analysis device can identify multiple other vehicles based on the shape, color, number on the license plate, etc. of the other vehicles.

[0025] The on-vehicle sensor 20 also includes a vehicle speed sensor 24 that detects the speed of the vehicle. The on-vehicle sensor 20 also includes a switch 25. The switch 25 includes a push-button type start switch 25a for the driver to request the driving assistance device 1 to start an automatic driving process, which will be described later. Each time the start switch 25a is pressed, the on / off state of the switch 25a is alternately switched.

[0026] Furthermore, the on-board sensor 20 includes a navigation system 26. In addition, the on-board sensor 20 includes a sensor (not shown) that detects the depth of depression of the brake pedal, a sensor (not shown) that detects whether the driver is touching the steering wheel, and the like.

[0027] The drive unit 30 applies a driving force to the drive wheels. The drive unit 30 includes an engine ECU, an internal combustion engine, a transmission, a driving force transmission mechanism that transmits the driving force to the wheels, and the like. The engine ECU controls a throttle valve so that the output of the internal combustion engine matches a target value. The engine ECU also controls the transmission of the host vehicle so that the shift position of the transmission matches a target position.

[0028] If the vehicle to which the driving assistance device 1 is applied is a hybrid vehicle (HEV), the engine ECU can control the driving force of the vehicle generated by either or both of an internal combustion engine and an electric motor as a vehicle driving source. Also, if the vehicle to which the driving assistance device 1 is applied is an electric vehicle (BEV), an electric motor ECU is used instead of the engine ECU to control the driving force of the vehicle generated by an electric motor as a vehicle driving source.

[0029] The braking device 40 applies a braking force to the wheels (brake discs). The braking device 40 includes a brake ECU, a brake caliper, etc. The brake ECU controls the brake caliper so that the braking force applied to the wheels matches a target value.

[0030] The steering device 50 controls the steering angle of the steered wheels (left front wheel and right front wheel). The steering device 50 includes a steering ECU, a steering mechanism, etc. The steering device 50 further includes an actuator that drives the steering mechanism to change the steering angle. The steering ECU controls the actuator so that the steering angle coincides with a target value.

[0031] (Automatic driving function) When the driving assistance ECU 10 detects that the start switch 25a has transitioned to the on state, it starts the automatic driving process (driving assistance process). That is, the driving assistance ECU 10 controls the drive device 30, the braking device 40, and the steering device 50 (hereinafter referred to as "drive devices, etc.") so that the vehicle automatically advances along the current driving lane (or a preset route). The driving assistance device 1 has a hands-off mode and a hands-on mode, similar to the above-mentioned conventional device, as the operation mode MD of the automatic driving function. When the driving assistance ECU 10 detects that the driver is not touching the steering wheel in the hands-on mode, it controls the notification device so that a predetermined alarm is issued.

[0032] The driving assistance ECU 10 uses a flag FXn (n=1, 2, . . . , max) and a flag FH to switch the operation mode MD in the autonomous driving process.

[0033] The flag FXn is associated with each condition Xn1 for determining that it is preferable to set the operation mode MD to the hands-on mode. When the condition Xn1 is satisfied, the driving assistance ECU 10 sets the flag FXn to "1". On the other hand, when the condition Xn1 is not satisfied, the driving assistance ECU 10 sets the flag FXn to "0". However, after the driving assistance ECU 10 sets the flag FXn (n=a,b,c,..) to "1" triggered by the satisfaction of a specific condition Xn1 (n=a,b,c,..), even if the specific condition Xn1 is not satisfied, the driving assistance ECU 10 maintains the flag FXn at "1" during a period in which a condition Xn2 for determining that the specific condition Xn1 is likely to be satisfied is satisfied. After that, when the condition Xn1 is not satisfied and the condition Xn2 is not satisfied, the driving assistance ECU 10 sets the flag FXn to "0". In this way, the condition for changing a specific flag FXn (n=a, b, c, . . . ) from "1" to "0" is stricter than the condition for changing the specific flag FXn (n=a, b, c, . . . ) from "0" to "1".

[0034] The flag FH indicates whether or not hands-off is permitted. When the flag FH is "0", hands-off is prohibited, and when the flag FH is "1", hands-off is permitted. When at least one flag FXn is "1" (when the logical sum of all flags FXn is "1"), the driving assistance ECU 10 sets the flag FH to "0". That is, the driving assistance ECU 10 prohibits hands-off. That is, the driving assistance ECU 10 sets the operation mode MD to the hands-on mode. On the other hand, when all flags FXn are "0" (when the logical sum of all flags FXn is "0"), the driving assistance ECU 10 sets the flag FH to "1". That is, the driving assistance ECU 10 permits hands-off. That is, the driving assistance ECU 10 sets the operation mode MD to the hands-off mode.

[0035] For example, when the vehicle is traveling on a general road or on an expressway at a relatively high speed (e.g., 40 km / h or higher), the driving assistance ECU 10 determines that the condition X11 is satisfied and sets the flag FX1 to "1." On the other hand, when the vehicle is traveling on an expressway at a relatively low speed (less than 40 km / h), the driving assistance ECU 10 determines that the condition X11 is not satisfied and sets the flag FX1 to "0." Note that service areas (rest spots) provided on expressways are included in general roads in this embodiment.

[0036] Also, for example, when the distance Δd0 between the host vehicle and the preceding vehicle (vehicle V2) is less than the threshold Δd0th (or when the predicted time TTC0 until the host vehicle collides with the vehicle V2 is less than the threshold TTC0th), the driving assistance ECU 10 determines that the condition X21 is satisfied and sets the flag FX2 to "1". On the other hand, when the distance Δd0 is equal to or greater than the threshold Δd0th (or when the predicted time TTC0 is equal to or greater than the threshold ΔTTC0th), the driving assistance ECU 10 determines that the condition X21 is not satisfied and sets the flag FX2 to "0". In this embodiment, the "preceding vehicle" (vehicle V2) refers to a vehicle that is traveling in the same traveling lane as the traveling lane L0 in which the host vehicle is traveling, and is traveling immediately before the host vehicle. A vehicle that is straddling a dividing line that divides the traveling lane L0 from the traveling lane L1 adjacent to the traveling lane L0 is not included in the "preceding vehicle".

[0037] In addition, when there is a high risk of contact between the host vehicle and another vehicle (vehicle V1) traveling in the travel lane L1, the driving assistance ECU 10 determines that the condition X31 is satisfied and sets the flag FX3 to "1". Specifically, the driving assistance ECU 10 monitors the behavior of the vehicle V1 traveling in the travel lane L1 adjacent to the travel lane L0 in which the host vehicle is traveling. For example, as shown in FIG. 2, when the vehicle V1 located in a region R1 diagonally forward of the host vehicle, which is a predetermined region in the travel lane L1, is blinking a turn signal light on the travel lane L0 side, the driving assistance ECU 10 determines that there is a high possibility that the vehicle V1 will enter the region R0 immediately in front of the host vehicle. The region R0 is a rectangular region extending forward from the front end of the host vehicle. The width of the region R0 is the same as the width of the travel lane L0. In addition, the length of the region R0 is the same as the distance between the rear end of the vehicle V2 and the front end of the host vehicle. When the vehicle V2 does not exist, the length of the region R0 is about twice the overall length of the host vehicle. In addition, when the vehicle V1 is straddling a dividing line dividing the driving lane L0 and the driving lane L1 in front of the host vehicle, the driving assistance ECU 10 determines that the vehicle V1 is likely to enter the region R0. When the driving assistance ECU 10 determines that the vehicle V1 is likely to enter the region R0, the driving assistance ECU 10 executes a vehicle-to-vehicle distance adjustment process to control the driving device 30 and / or the braking device 40 of the host vehicle so that the distance Δd1 (distance in the front-rear direction) between the host vehicle and the vehicle V1 becomes equal to or greater than a threshold Δd1th (>Δd0th) (or the predicted time TTC1 becomes equal to or greater than a threshold TTC1th (>TTC0th)). The driving assistance ECU 10 executes the vehicle-to-vehicle distance adjustment process to prompt the vehicle V1 to enter the region R0, but for example, when the vehicle V1 suddenly decelerates, the distance Δd1 may temporarily become less than the threshold Δd1th. In this case, the driving assistance ECU 10 determines that there is a high risk of contact between the vehicle V1 and the host vehicle. In this case, the driving assistance ECU 10 determines that the condition X31 (the first condition of the present invention) is satisfied, and sets the flag FX3 to "1." That is, hands-off is prohibited. As a result, for example, if the vehicle V1 further decelerates and approaches the host vehicle, the driver can immediately operate the steering wheel (steering override) to avoid contact between the host vehicle and the vehicle V1.

[0038] After setting the flag FX3 to "1," the driving assistance ECU 10 continues to monitor the behavior of the vehicle V1. Even if the condition X31 becomes temporarily unsatisfied after the condition X31 is satisfied, the condition X31 may become satisfied again immediately thereafter.

[0039] For example, even if, after condition X31 is satisfied (before vehicle V1 has completed entering area R0), the distance Δd1 temporarily increases to equal to or exceed the threshold value Δd1th, causing condition X31 to become unsatisfied, there is a possibility that the distance Δd1 will subsequently decrease (before vehicle V1 has completed entering area R0) again to fall below the threshold value Δd1th, causing condition X31 to be satisfied.

[0040] In addition, when the host vehicle is traveling in a merging section M of the travel lanes L1 and L0, there is a possibility that another vehicle V3 will follow the vehicle V1 and enter the area R0 from the area R1. In addition, as shown in Fig. 3, while the host vehicle is traveling in a section other than the merging section of the expressway, there is a possibility that the vehicle V3 will follow the vehicle V1 (the vehicle that has completed the lane change (vehicle V2 in the figure)) and enter the area R0. In these cases, even if the condition X31 is not satisfied for the vehicle V1, there is a high possibility that the condition X31 is satisfied for the vehicle V3.

[0041] Therefore, as described below, the driving assistance ECU 10 maintains the flag FX3 at "1" during the period in which a condition X32 for determining that the situation is highly likely to result in the satisfaction of the condition X31 is satisfied.

[0042] Specifically, the driving assistance ECU 10 determines that the condition X32 is satisfied when the vehicle V1 is entering the region R0. The driving assistance ECU 10 also determines that the condition X32 is satisfied when the host vehicle is traveling in the merging section M. The driving assistance ECU 10 also determines that the condition X32 is satisfied when the host vehicle is traveling in a section that is not the merging section M (a non-merging section) and a vehicle V3 is present in the region R1 with its turn signal light flashing on the driving lane L0 side, regardless of the distance Δd1.

[0043] On the other hand, when the driving assistance ECU 10 recognizes that the vehicle V1 has completed entering the area R0, and the vehicle is not traveling in the merging section M and there is no vehicle V3 attempting to enter the area R0, the driving assistance ECU 10 determines that the condition X32 is not satisfied.

[0044] In addition, under circumstances where the accuracy of image recognition by the camera 23 is reduced (rainy weather, nighttime, etc.), the driving assistance ECU 10 may have difficulty recognizing that the vehicle V1 has completed entering the area R0. In this manner, if the driving assistance ECU 10 is unable to recognize (loses sight of) the vehicle V1 after time t0 when the flag FX3 is set to "1", the driving assistance ECU 10 considers that the entry of the vehicle V1 into the area R0 has been completed at time t1 when the elapsed time Δt from time t0 reaches the threshold value Δtth.

[0045] Furthermore, when the brake pedal is depressed, the driving assistance ECU 10 determines that the condition X41 is satisfied, and sets the flag FX4 to "1." On the other hand, when the brake pedal is released, the driving assistance ECU 10 determines that the condition X41 is not satisfied, and sets the flag FX3 to "0." However, when the brake pedal is depressed while the vehicle distance adjustment process is being performed, the driving assistance ECU 10 determines that the condition X31 is satisfied in addition to the condition X41. That is, the driving assistance ECU 10 sets the flag FX4 to "1," and sets the flag FX3 to "1" regardless of the distance Δd1 (even if the distance Δd1 is equal to or greater than the threshold value Δd1th).

[0046] Next, referring to Figures 4 and 5, the programs PR1, PR2, and PR3 executed by the CPU 10a (hereinafter simply referred to as "CPU") to realize the function of switching the operation mode MD according to the situation will be described. When the CPU detects that the start switch 25a has transitioned to the on state, it starts executing the programs PR1 to PR3. Note that when the CPU detects that the switch 25a is in the off state, it suspends the execution of the programs PR1 to PR3.

[0047] (Program PR1) The CPU starts execution of the program PR1 (FIG. 4) from step 100 and advances the process to step 101.

[0048] In step 101, the CPU calculates the logical sum of flags FX1 to FXmax, and determines whether the logical sum is "0." The CPU executes program PR1, and also executes programs PR2 and PR3 (parallel processing) described below, to set flags FX1 to FXmax to "1" or "0," respectively. If the CPU determines that the logical sum is "0" (101: Yes), the CPU proceeds to step 102. On the other hand, if the CPU does not determine that the logical sum is "0" (101: No), the CPU proceeds to step 103.

[0049] In step 102, the CPU sets the flag FH to "1" (permits hands-off) and returns the process to step 101. On the other hand, in step 103, the CPU sets the flag FH to "0" (prohibits hands-off) and returns the process to step 101.

[0050] (Program PR2) Program PR2 includes a process (step) of sequentially selecting flag FXn (n=1, 2, 3, . . . , max) to be processed, and changing flag FXn from "0" to "1" if condition Xn1 is satisfied. Note that the process of changing flag FXn from "1" to "0" is not included in program PR2, but is included in program PR3, which will be described later.

[0051] The CPU starts the execution of the program PR2 (FIG. 5(A)) from step 200, and proceeds to step 201.

[0052] In step 201, the CPU sets an index n for designating (selecting) the flag FXn to be processed to “1.” Next, the CPU advances the process to step 202.

[0053] In step 202, the CPU determines whether or not the flag FXn is "0." If the CPU determines that the flag FXn is "0" (202: Yes), the CPU proceeds to step 203. On the other hand, if the CPU does not determine that the flag FXn is "0" (202: No), the CPU proceeds to step 205, which will be described later.

[0054] The CPU determines whether or not the condition Xn1 is satisfied in step 203. If the CPU determines that the condition Xn1 is satisfied (203: Yes), the process proceeds to step 204. On the other hand, if the CPU does not determine that the condition Xn1 is satisfied (203: No), the process proceeds to step 205.

[0055] In step 204, the CPU sets the flag FXn to “1.” Next, the CPU proceeds to step 205.

[0056] In step 205, the CPU determines whether or not index n is less than the maximum value max. If the CPU determines that index n is less than the maximum value max (205: Yes), the CPU proceeds to step 206. On the other hand, if the CPU does not determine that index n is less than the maximum value max (205: No), the CPU returns to step 201.

[0057] The CPU increments the index n in step 206. Then, the CPU returns the process to step 202.

[0058] (Program PR3) Program PR3 includes a process (step) of sequentially selecting flag FXn (n = 1, 2, 3, ..., max) to be processed, and changing the flag FXn from "1" to "0" if condition Xn1 (condition Xn1 and condition Xn2 for a specific flag FXn) is not satisfied.

[0059] The CPU starts the execution of the program PR3 (FIG. 5(B)) from step 300, and proceeds to step 301.

[0060] In step 301, the CPU sets an index n for designating (selecting) the flag FXn to be processed to “1.” Next, the CPU advances the process to step 302.

[0061] In step 302, the CPU determines whether or not the flag FXn is "1." If the CPU determines that the flag FXn is "1" (302: Yes), the CPU proceeds to step 303. On the other hand, if the CPU does not determine that the flag FXn is "1" (302: No), the CPU proceeds to step 307, which will be described later.

[0062] The CPU determines whether or not the condition Xn1 is not satisfied in step 303. If the CPU determines that the condition Xn1 is not satisfied (303: Yes), the CPU proceeds to step 304. On the other hand, if the CPU does not determine that the condition Xn1 is not satisfied (303: No), the CPU proceeds to step 306, which will be described later.

[0063] In step 304, the CPU determines whether or not a specific flag FXn has been selected as the processing target. That is, the CPU determines whether or not the index n corresponds to any of the specific values ​​[a, b, c, ...]. If the CPU determines that a specific flag FXn has been selected as the processing target (304: Yes), the CPU proceeds to step 305. On the other hand, if the CPU does not determine that a specific flag FXn has been selected as the processing target (304: No), the CPU proceeds to step 306.

[0064] In step 305, the CPU determines whether or not condition Xn2 is satisfied. If the CPU determines that condition Xn2 is satisfied (305: Yes), the process proceeds to step 307. That is, in this case, the flag FXn is not changed. That is, the CPU maintains the state in which hands-off is prohibited (a state in which the hands-on mode, which has a lower driving assistance level than the hands-off mode, is set). On the other hand, if the CPU does not determine that condition Xn2 is satisfied (305: No), the process proceeds to step 306.

[0065] In step 306, the CPU sets the flag FXn to “0.” Next, the CPU proceeds to step 307.

[0066] In step 307, the CPU determines whether or not index n is less than the maximum value max. If the CPU determines that index n is less than the maximum value max (307: Yes), the CPU proceeds to step 308. On the other hand, if the CPU does not determine that index n is less than the maximum value max (307: No), the CPU returns to step 301.

[0067] The CPU increments the index n in step 308. Then, the CPU returns the process to step 302.

[0068] Next, a specific example of the process for determining whether conditions Xn1 and Xn2 are satisfied will be described. When the brake pedal is not depressed, the CPU executes program PR4 (FIG. 6(A)) to determine whether condition X31 is satisfied. The CPU also executes program PR5 (FIG. 6(B)) to determine whether condition X32 is satisfied.

[0069] (Program PR4) The CPU starts the execution of program PR4 from step 400 and proceeds to step 401.

[0070] In step 401, the CPU determines whether or not there is a vehicle V1 that is likely to enter the area R0. If the CPU determines that the vehicle V1 is present (401: Yes), it starts the distance adjustment process and proceeds to step 402. On the other hand, if the CPU does not determine that the vehicle V1 is present (401: No), it proceeds to step 404, which will be described later.

[0071] In step 402, the CPU determines whether the distance Δd1 (predicted time TTC1) is less than the threshold Δd1th (threshold TTC1th). If the CPU determines that the distance Δd1 (predicted time TTC1) is less than the threshold Δd1th (threshold TTC1th) (402; Yes), the CPU proceeds to step 403. On the other hand, if the CPU does not determine that the distance Δd1 (predicted time TTC1) is less than the threshold Δd1th (threshold TTC1th) (402; No), the CPU proceeds to step 404.

[0072] The CPU determines that the condition X31 is satisfied in step 403. In this case, the CPU starts measuring the elapsed time Δt. Then, the CPU ends the execution of the program PR4 in step 405.

[0073] Moreover, the CPU determines that the condition X31 is not satisfied in step 404. Next, the CPU proceeds to the process of step 405, where it ends the execution of the program PR4.

[0074] (Program PR5) The CPU starts execution of the program PR5 (FIG. 6B) from step 500 and advances the process to step 501.

[0075] In step 501, the CPU determines whether or not the vehicle V1 has entered area R0 (whether or not the CPU has detected completion of the interruption). If the CPU determines that the vehicle V1 has entered area R0 (501: Yes), the CPU proceeds to step 504, which will be described later. On the other hand, if the CPU does not determine that the vehicle V1 has entered area R0 (if the vehicle V1 is in the middle of entering area R0 or if the vehicle V1 has been lost (501: No)), the CPU proceeds to step 502.

[0076] In step 502, the CPU determines whether or not the vehicle V1 (the vehicle related to the cause for setting flag FX3 to "1") has been lost (cannot be recognized). If the CPU determines that the vehicle V1 has been lost (502: Yes), the process proceeds to step 503. On the other hand, if the CPU does not determine that the vehicle V1 has been lost (502: No), the process proceeds to step 506.

[0077] In step 503, the CPU determines whether the elapsed time Δt is equal to or greater than a threshold value Δtth. If the CPU determines that the elapsed time Δt is equal to or greater than the threshold value Δtth (503: Yes), the CPU proceeds to step 504, which will be described later. On the other hand, if the CPU does not determine that the elapsed time Δt is equal to or greater than the threshold value Δtth (503: No), the CPU proceeds to step 506.

[0078] In step 504, the CPU determines whether or not the host vehicle is traveling in the merging section M. If the CPU determines that the host vehicle is traveling in the merging section M (504: Yes), the CPU proceeds to step 506. On the other hand, if the CPU does not determine that the host vehicle is traveling in the merging section M (504: No), the CPU proceeds to step 505.

[0079] In step 505, the CPU determines whether or not there is a vehicle V3 that is likely to enter the region R0. If the CPU determines that the vehicle V3 is present (505: Yes), the CPU proceeds to step 506. On the other hand, if the CPU does not determine that the vehicle V3 is present (505: No), the CPU proceeds to step 507.

[0080] The CPU determines that the condition X32 is satisfied in step 506. The CPU also determines that the condition X32 is not satisfied in step 507. Then, the CPU ends the execution of the program PR5 in step 508.

[0081] (Effect) According to the driving support device 1, after the operation mode MD (driving support level) is changed from the hands-off mode (first level) to the hands-on mode (second level), in a situation where the condition Xn1 (first condition) is likely to be satisfied (a situation where the condition Xn2 is satisfied), the operation mode MD is maintained in the hands-on mode. Therefore, compared to the above-mentioned conventional device, frequent changes in the driving support level are suppressed. [Explanation of symbols]

[0082] Reference Signs List 1... driving assistance device, 10... driving assistance ECU, 20... vehicle-mounted sensor, 30... driving device, 40... braking device, 50... steering device

Claims

1. A driving assistance device that assists driving operation of a vehicle, An on-board sensor that acquires target information regarding targets located around the host vehicle; A processor capable of executing a driving assistance process that determines a driving assistance level, which is a degree of assistance for the driving operation, based on the target information and controls the host vehicle so that assistance of the driving assistance level is provided to the driver; Equipped with A driving assistance device configured to, when a first condition predefined as a condition for lowering a driving assistance level is satisfied while a predetermined first level driving assistance processing is being executed, start executing driving assistance processing of a second level lower than the first level instead of the first level driving assistance processing, and maintain the driving assistance level at the second level during a period during which a second condition predefined as a condition for determining that a situation is one in which the first condition is likely to be satisfied is satisfied.

2. The driving assistance device according to claim 1, The driving assistance device is configured so that, when the processor determines that there is a high possibility that another vehicle traveling in a second driving lane adjacent to a first driving lane in which the host vehicle is traveling will enter the first driving lane, the processor executes a distance adjustment process to control the drive device and / or braking device of the host vehicle so that the other vehicle can enter the area immediately in front of the host vehicle, and when the distance between the host vehicle and the other vehicle or the predicted time until contact between the host vehicle and the other vehicle becomes less than a threshold value while the vehicle distance adjustment process is being executed, the processor determines that the first condition is met.

3. The driving assistance device according to claim 2, The processor determines that the second condition is satisfied when the host vehicle is traveling in a merging section of a travel lane. A driving assistance device configured as above.

4. The driving assistance device according to claim 2, A driving assistance device configured such that the processor determines that the second condition is satisfied in a situation in which there is a high possibility that a vehicle other than the other vehicle will enter the area.

5. The driving assistance device according to claim 2, The processor measures the elapsed time from a first point in time at which it is determined that the first condition is satisfied, and if the other vehicle cannot be detected after the first point in time, determines that the second condition is satisfied under a situation where the elapsed time is less than a threshold value.

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