Driving assistance device

Abstract

A driving assistance device is provided with: an in-vehicle sensor that acquires target information relating to a target located in the periphery of a host vehicle; and a processor capable of determining a driving assistance level, which is the degree of assistance of the driving operation, on the basis of the target object information, and executing a driving assistance process for controlling the host vehicle so as to provide assistance of the driving assistance level to the driver. When a first condition is satisfied during execution of a predetermined first-level driving assistance process, the processor starts execution of a second-level driving assistance process lower than the first-level driving assistance process in place of the first-level driving assistance process, and starts execution of the second-level driving assistance process in place of the second-level driving assistance process in place of the second-level driving assistance process in place of the second-level driving assistance process during a period in which a second condition is satisfied. And maintaining the driving assistance level at the second level.

Description

Technical Field

[0001] The present invention relates to a driving assistance device for assisting driving operation of a vehicle. Background Art

[0002] A driving assistance device that assists the driving operation of a vehicle is proposed (for example, refer to Japanese Patent Application Laid-Open No. 2015-153153). The driving assistance device (hereinafter referred to as "the conventional device") has an automatic driving function that enables the vehicle to move automatically. When there is a high possibility that another vehicle enters (intersects) between the vehicle and the preceding vehicle (the vehicle directly in front of the vehicle) during the execution of the automatic driving control, the conventional device controls the braking device (and / or driving device) of the vehicle in such a way as to increase the distance between the vehicle and the preceding vehicle. As a result, the other vehicle can easily enter between the vehicle and the preceding vehicle. Summary of the invention

[0003] A driving assistance device is proposed that has, for example, a hands-on mode and a hands-off mode as action modes for automatic driving control. The steering angle is automatically adjusted in any action mode. In the hands-on mode, the driver needs to touch the steering wheel lightly. On the other hand, in the hands-off mode, it is allowed to take the hands off the steering wheel (let go). However, in the hands-off mode, when a predetermined condition (cancellation condition) is met, the hands-off mode is forcibly changed to the hands-on mode. For example, in the hands-off mode, when the distance between the vehicle and another vehicle that has entered between the vehicle and the preceding vehicle becomes less than a threshold value, the cancellation condition is met. In this way, the driving assistance device reduces the driving assistance level when the predetermined condition is met.

[0004] Here, in a scenario where the cancellation condition is met, there is a high possibility that the same cancellation condition is met repeatedly in a short period of time thereafter. In a case where the driving assistance device is configured to restore the driving assistance level at a point in time when the cancellation condition becomes unmet, the driving assistance level may change frequently. The driver may become annoyed by the frequent changes (tremors) in the driving assistance level.

[0005] One of the objects of the present invention is to provide a driving assistance device capable of suppressing “frequent changes in driving assistance levels”.

[0006] In order to solve the above-mentioned problem, a driving assistance device (1) according to one embodiment of the present invention assists driving operation of a host vehicle (V).

[0007] The driving assistance device has:

[0008] A vehicle-mounted sensor (20) acquires object information related to objects (object targets) located around the vehicle (V); and

[0009] A processor (10) is capable of determining a driving assistance level as a degree of assistance for the driving operation based on the object information, and executing driving assistance processing for controlling the host vehicle in a manner that provides assistance of the driving assistance level to the driver.

[0010] The processor is configured to start executing a second level of driving assistance processing lower than the first level instead of the first level of driving assistance processing when a first condition (Xn1) predetermined as a condition for lowering the driving assistance level is satisfied during execution of the predetermined first level of driving assistance processing.

[0011] The processor is configured to maintain the driving assistance level at the second level while a second condition (Xn2) predetermined as a condition for determining that the situation is likely to be met with a high probability that the first condition is met is met.

[0012] According to the driving assistance device of the technical solution of the present invention, after the driving assistance level is reduced from the first level to the second level, the state of "providing the second level of driving assistance to the driver" is maintained under the condition that the first condition is likely to be satisfied. Therefore, compared with the above-mentioned conventional device, the situation where the driving assistance level is frequently changed can be suppressed.

[0013] In the driving assistance device involved in the above technical solution of the present invention,

[0014] The processor can perform a vehicle-to-vehicle distance adjustment process to control the drive unit and / or braking unit of the vehicle in such a manner that the other vehicle can enter the area directly in front of the vehicle when it is determined that there is a high possibility that the other vehicle traveling in the second driving lane adjacent to the first driving lane in which the vehicle is traveling will enter the first driving lane.

[0015] The processor determines that the first condition is satisfied when the distance (Δd1) between the host vehicle and the other vehicle or the predicted time (TTC1) until the host vehicle and the other vehicle come into contact becomes smaller than a threshold value while the inter-vehicle distance adjustment process is being executed.

[0016] Accordingly, when there is a high possibility that another vehicle will enter the area directly in front of the vehicle and when there is a high possibility that the vehicle will come into contact with another vehicle, the driving assistance level is reduced. Thus, in an emergency (for example, when the vehicle is approaching another vehicle quickly), the driver can start operations to avoid risks that may be caused by the emergency without stopping.

[0017] In the driving assistance device involved in the above technical solution of the present invention,

[0018] The processor may determine that the second condition is satisfied when the host vehicle is traveling in a merging section of a driving lane.

[0019] In the merging section, it is possible that a plurality of other vehicles may successively enter the area directly in front of the vehicle, and the first condition is likely to be satisfied relatively frequently. According to the present invention, the driving assistance level is maintained at the second level during driving in this section. That is, the situation where the driving assistance level is frequently changed can be suppressed.

[0020] In the driving assistance device involved in the above technical solution of the present invention,

[0021] The processor may determine that the second condition is satisfied when there is a high possibility that another vehicle different from the other vehicle enters the area.

[0022] Assume the following scenario: after the driving assistance level is lowered with "another vehicle (first other vehicle) that is about to enter the area directly in front of the vehicle approaches the vehicle" as a trigger condition, another other vehicle (second other vehicle) is about to enter the area. In this case, even if the first condition is not satisfied at the current time point with respect to the second other vehicle, there is a high possibility that the first condition will be satisfied later. According to the driving assistance device involved in the present technical solution, in this scenario, the driving assistance level is maintained at the second level. That is, the situation where the driving assistance level is frequently changed can be suppressed.

[0023] In the driving assistance device involved in the above technical solution of the present invention,

[0024] The processor may measure an elapsed time (Δt) from a first time point at which it is determined that the first condition is satisfied,

[0025] When the other vehicle cannot be detected after the first time point, it is determined that the second condition is satisfied if the elapsed time is less than a threshold value (Δtth).

[0026] For example, sometimes at night or in rainy days, it is difficult for the on-board sensor to identify other vehicles with high accuracy. In this case, when the elapsed time is less than a threshold value (for example, the average time required for lane changes of ordinary vehicles), the driving assistance level is maintained at the second level. That is, the situation where the driving assistance level is frequently changed can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0028] Figure 1 is a block diagram of a driving assistance device according to an embodiment of the present invention;

[0029] Figure 2 It is a bird's-eye view of the merging section of the expressway and its surroundings;

[0030] Figure 3 is a plan view showing a section other than a merging section of the expressway;

[0031] Figure 4 is a flowchart of the procedure for setting the flag FH;

[0032] Figure 5A is a flowchart of a procedure for setting flag FXn;

[0033] Figure 5B is a flowchart of a procedure for setting flag FXn;

[0034] Fig. 6A It is a flowchart of a procedure for determining whether a specific condition is met;

[0035] Figure 6B This is a flowchart of a program for determining whether a specific condition is satisfied. DETAILED DESCRIPTION

[0036] outline

[0037] A driving assistance device 1 according to one embodiment of the present invention is mounted on a vehicle V (hereinafter referred to as "this vehicle"). The driving assistance device 1 assists the driver's driving operation. For example, the driving assistance device 1 has a function of performing automatic driving control (automatic driving function), which is to control the vehicle in a manner that allows the vehicle to travel automatically. The driving assistance device 1 changes the degree of assistance for the driving operation (driving assistance level) according to the situation.

[0038] Specific composition

[0039] like Figure 1 As shown, the driving assistance device 1 includes a driving assistance ECU 10 , an on-vehicle sensor 20 , a drive device 30 , a brake device 40 , and a steering device 50 .

[0040] 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 via a CAN. The other ECUs are, for example, ECUs of a drive device 30, a brake device 40, and a steering device 50 described later.

[0041] The vehicle-mounted sensor 20 includes a radar 21 , a sonar 22 , and a camera 23 as surrounding sensors that acquire information on a target object (target object information) that exists around the vehicle.

[0042] The radar 21 includes a transceiver and a signal processing unit. The transceiver transmits radio waves in the millimeter wave band (hereinafter referred to as "millimeter waves") to the front of the vehicle, and receives millimeter waves (reflected waves) reflected by a solid object within the transmission range. The signal processing unit identifies the distance between the vehicle and the solid object, the relative position (direction) of the solid object relative to the vehicle, etc. based on the time from the transmission of the millimeter wave to the reception of the reflected wave by the transceiver, the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation degree of the reflected wave, etc. The signal processing unit sends the recognition result to the driving assistance ECU 10.

[0043] The sonar 22 intermittently transmits ultrasonic waves to the surrounding area of ​​the host vehicle and receives ultrasonic waves (reflected waves) reflected by the three-dimensional object. The sonar 22 recognizes the distance between the host vehicle and the three-dimensional object, the relative position (direction) of the three-dimensional object relative to the host vehicle, etc. based on the time from transmitting the ultrasonic waves to receiving the reflected waves. The sonar 22 sends the recognition result to the driving assistance ECU 10.

[0044] The camera 23 includes a photographing device and an image analyzing device. The photographing device has a built-in CCD, for example. The photographing device is disposed at the front of the vehicle. The photographing device photographs the scene in front of the vehicle at a predetermined frame rate to obtain image data. The image analyzing device analyzes the image data and identifies objects and signs existing around the vehicle based on the image. For example, the image analyzing device identifies other vehicles, lane markings (dividing lines, curbs, separation strips, etc. that divide driving lanes), etc., and sends the recognition result to the driving assistance ECU 10. In addition, the image analyzing device can identify multiple other vehicles based on the shape, color, number recorded on the license plate, etc. of the other vehicles.

[0045] In addition, the vehicle-mounted sensor 20 includes a vehicle speed sensor 24 for detecting the vehicle speed of the vehicle. Furthermore, the vehicle-mounted sensor 20 includes a switch 25. The switch 25 includes a push-button start switch 25a for the driver to request the driving assistance device 1 to start the automatic driving process described later. Each time the start switch 25a is pressed, the on / off state of the switch 25a is alternately switched.

[0046] Furthermore, the vehicle-mounted sensor 20 includes a navigation system 26. In addition, the vehicle-mounted sensor 20 includes a sensor (not shown) for detecting the depression depth of the brake pedal, a sensor (not shown) for detecting whether the driver is touching the steering wheel, and the like.

[0047] The drive device 30 applies driving force to the driving wheels. The drive device 30 includes an engine ECU, an internal combustion engine, a transmission, a driving force transmission mechanism that transmits driving force to the wheels, etc. The engine ECU controls the throttle so that the output of the internal combustion engine is consistent with the target value. In addition, the engine ECU controls the transmission so that the gear position of the transmission equipped in the vehicle is consistent with the target gear position.

[0048] Furthermore, when the vehicle to which the driving assistance device 1 is applied is a hybrid electric vehicle (HEV), the engine ECU can control the driving force of the vehicle generated by either or both of the "internal combustion engine and the electric motor" as the vehicle driving source. Furthermore, when the vehicle to which the driving assistance device 1 is applied is an electric vehicle (BEV), a motor ECU that controls the driving force of the vehicle generated by the "electric motor" as the vehicle driving source is used instead of the engine ECU.

[0049] The brake device 40 applies a braking force to the wheels (brake discs). The brake 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.

[0050] The steering device 50 controls the steering angle of the steering wheels (left front wheel and right front wheel). The steering device 50 includes a steering ECU, a steering mechanism, etc. The steering device 50 also includes an actuator that drives the steering mechanism to change the steering angle. The steering ECU controls the actuator in such a way that the steering angle is consistent with the target value.

[0051] Autonomous driving features

[0052] When the driving assistance ECU 10 detects that the start switch 25a has been turned to the on state, the automatic driving process (driving assistance process) is started. That is, the driving assistance ECU 10 controls the drive device 30, the brake device 40 and the steering device 50 (hereinafter referred to as "drive device, etc.") in such a way that the vehicle automatically moves along the driving lane (or the pre-set path) currently being driven. The driving assistance device 1 has the same hands-free mode and hand-held mode as the above-mentioned conventional devices as the action mode MD of the automatic driving function. When the driving assistance ECU 10 detects that "the driver does not touch the steering wheel" in the hand-held mode, the control notification device issues a predetermined alarm.

[0053] The driving assistance ECU 10 switches the operation mode MD using a flag FXn (n=1, 2, . . . , max) and a flag FH during the automatic driving process.

[0054] The flag FXn is associated with each condition Xn1 for determining that "it is preferable to set the action mode MD to the hand-held mode". The driving assistance ECU 10 sets the flag FXn to "1" when the condition Xn1 is satisfied. On the other hand, the driving assistance ECU 10 sets the flag FXn to "0" when the condition Xn1 is not satisfied. However, after the driving assistance ECU 10 sets the flag FXn (n = a, b, c, ...) to "1" with the satisfaction of a specific condition Xn1 (n = a, b, c, ...) as a trigger condition, the driving assistance ECU 10 maintains the flag FXn to "1" during the period when the condition Xn2 for determining that the possibility of the specific condition Xn1 being satisfied is high is satisfied, even if the specific condition Xn1 becomes unsatisfied. Thereafter, 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". As described above, the condition for changing a specific flag FXn (n=a, b, c, ...) from "1" to "0" is stricter than the condition for changing a specific flag FXn (n=a, b, c, ...) from "0" to "1".

[0055] The flag FH indicates whether hands-off is allowed. 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. In other words, the driving assistance ECU 10 sets the action mode MD to the hand-holding 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. In other words, the driving assistance ECU 10 sets the action mode MD to the hands-off mode.

[0056] For example, when the host vehicle is traveling on a general road or traveling on a highway at a relatively high speed (for example, 40 km / h or more), 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 host vehicle is traveling on a highway 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". In addition, service areas (resting spots) provided on highways are included in general roads in this embodiment.

[0057] In addition, for example, when the distance Δd0 between the host vehicle and the preceding vehicle (vehicle V2) is less than the threshold value Δd0th (or when the predicted time TTC0 until the host vehicle collides with the vehicle V2 is less than the threshold value 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 greater than the threshold value Δd0th (or when the predicted time TTC0 is greater than the threshold value ΔTTC0th), the driving assistance ECU 10 determines that the condition X21 is not satisfied and sets the flag FX2 to "0". In addition, in the present embodiment, the "preceding vehicle" (vehicle V2) refers to a vehicle traveling in the same driving lane as the driving lane L0 in which the host vehicle is traveling and is traveling directly in front of the host vehicle. A vehicle crossing the dividing line that divides the driving lane L0 and the driving lane L1 adjacent thereto is not included in the "preceding vehicle".

[0058] In addition, when the risk of contact between the host vehicle and another vehicle (vehicle V1) traveling in the driving lane L1 is high, 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 driving lane L1 adjacent to the driving lane L0 in which the host vehicle is traveling. For example, in the case of Figure 2As shown in FIG. 1 , when a vehicle V1 located in an area R1 obliquely in front of the vehicle, which is a predetermined area in the driving lane L1, flashes the direction indicator light on the driving lane L0 side, the driving assistance ECU 10 determines that there is a high possibility that the vehicle V1 enters the area R0 directly in front of the vehicle. In addition, the area R0 is a rectangular area extending forward from the front end of the vehicle. The width of the area R0 is the same as the width of the driving lane L0. In addition, the length of the area R0 is the same as the "distance between the rear end of the vehicle V2 and the front end of the vehicle". In the absence of the vehicle V2, the length of the area R0 is about twice the total length of the vehicle. In addition, when the vehicle V1 is crossing the dividing line that divides the driving lane L0 and the driving lane L1 in front of the vehicle, the driving assistance ECU 10 determines that there is a high possibility that the vehicle V1 enters the area R0. When the driving assistance ECU 10 determines that there is a high possibility that the vehicle V1 enters the region R0, the driving assistance ECU 10 performs an inter-vehicle distance adjustment process for controlling 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 greater than the threshold value Δd1th (>Δd0th) (or the predicted time TTC1 becomes greater than the threshold value TTC1th (>TTC0th)). The driving assistance ECU 10 promotes the vehicle V1 to enter the region R0 by performing the inter-vehicle distance adjustment process. However, for example, when the vehicle V1 decelerates suddenly, the distance Δd1 may temporarily become less than the threshold value Δd1th. In this case, the driving assistance ECU 10 determines that there is a high risk that the vehicle V1 contacts 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. Thus, for example, when 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.

[0059] The driving support ECU 10 continues to monitor the behavior of the vehicle V1 after setting the flag FX3 to "1". Here, after the condition X31 is satisfied, even if the condition X31 temporarily becomes unsatisfactory, the condition X31 may be satisfied again immediately thereafter.

[0060] Before the vehicle V1 completes its entry into the area R0, for example, after the condition X31 is satisfied, even if the condition X31 temporarily becomes unsatisfactory due to the distance Δd1 increasing to be greater than the threshold Δd1th, there is a possibility that the distance Δd1 decreases again and becomes less than the threshold Δd1th, thereby satisfying the condition X31.

[0061] In addition, when the host vehicle is traveling in the merging section M between the driving lane L1 and the driving lane L0, another vehicle V3 may follow the vehicle V1 and enter the area R0 from the area R1. Figure 3 As shown in FIG. 1 , while traveling in a section other than the merging section of the highway, the vehicle V3 may follow the vehicle V1 into the area R0. The vehicle V1 is a vehicle that has completed the lane change. Figure 3 In the above case, even if the condition X31 does not hold for the vehicle V1, there is a high possibility that the condition X31 holds for the vehicle V3.

[0062] Therefore, as described below, while the condition X32 for determining that the condition X31 is likely to be satisfied is satisfied, the driving support ECU 10 maintains the flag FX3 at “1”.

[0063] Specifically, the driving assistance ECU 10 determines that the condition X32 is satisfied when the vehicle V1 is in the middle of entering the region R0. In addition, the driving assistance ECU 10 determines that the condition X32 is satisfied when the host vehicle is traveling in the merging section M. In addition, when the host vehicle is traveling in a section other than the merging section M (non-merging section) and there is a vehicle V3 flashing the direction indicator on the driving lane L0 side in the region R1, the driving assistance ECU 10 determines that the condition X32 is satisfied regardless of the distance Δd1.

[0064] On the other hand, when recognizing that “the vehicle V1 has completed entering the area R0 ”, the host vehicle is not traveling in the merging section M, and there is no vehicle V3 that is about to enter the area R0 , the driving support ECU 10 determines that the condition X32 is not satisfied.

[0065] In addition, in a situation where the image recognition accuracy of the camera 23 is reduced (rainy days, nighttime, etc.), it is sometimes difficult for the driving assistance ECU 10 to recognize that "the vehicle V1 has completed entering the area R0". In this case, after the time point t0 at which the driving assistance ECU 10 sets the flag FX3 to "1", when the vehicle V1 is no longer recognized (lost), the driving assistance ECU 10 regards that "the vehicle V1 has completed entering the area R0" at the time point t1 when the elapsed time Δt from the time point t0 reaches the threshold Δtth.

[0066] In addition, when the brake pedal is stepped on, 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 stepped on during the execution of the inter-vehicle distance adjustment process, 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 greater than the threshold Δd1th).

[0067] Next, refer to Figure 4 , Figure 5A and Figure 5B , the program PR1, the program PR2, and the program PR3 executed by the CPU 10a (hereinafter referred to as "CPU") to realize the function of switching the operation mode MD according to the situation are described. When the CPU detects that the start switch 25a is turned to the on state, the execution of the program PR1 to the program PR3 is started. In addition, when the CPU detects that the switch 25a is in the off state, the execution of the program PR1 to the program PR3 is interrupted.

[0068] Program PR1

[0069] The CPU starts procedure PR1 at step 100 ( Figure 4 ) is executed, causing the processing to enter step 101.

[0070] In step 101, the CPU calculates the logical sum of flags FX1 to FXmax and determines whether the logical sum is "0". In addition, the CPU sets flags FX1 to FXmax to "1" or "0" respectively by "executing programs PR2 and PR3 described later while executing program PR1" (parallel processing). When the CPU determines that the logical sum is "0" (101: Yes), the CPU proceeds to step 102. On the other hand, when the CPU does not determine that the logical sum is "0" (101: No), the CPU proceeds to step 103.

[0071] In step 102 , the CPU sets the flag FH to “1” (hands-off permitted), and returns the process to step 101 . On the other hand, in step 103 , the CPU sets the flag FH to “0” (hands-off prohibited), and returns the process to step 101 .

[0072] Program PR2

[0073] The program PR2 includes the following processing (step): sequentially selecting the flag FXn (n=1, 2, 3, ..., max) to be processed, and when the condition Xn1 is satisfied, changing the flag FXn from "0" to "1". In addition, the processing of changing the flag FXn from "1" to "0" is not included in the program PR2, but is included in the program PR3 described later.

[0074] The CPU starts procedure PR2 at step 200 ( Figure 5A ) is executed, causing the processing to enter step 201.

[0075] In step 201 , the CPU sets the index n of the flag FXn for specifying (selecting) a processing target to “1.” Next, the CPU advances the processing to step 202 .

[0076] In step 202, the CPU determines whether the flag FXn is "0". When the CPU determines that the flag FXn is "0" (202: Yes), the CPU proceeds to step 203. On the other hand, when the CPU does not determine that the flag FXn is "0" (202: No), the CPU proceeds to step 205 described later.

[0077] The CPU determines whether the condition Xn1 is satisfied in step 203. If the CPU determines that the condition Xn1 is satisfied (203: Yes), the CPU proceeds to step 204. On the other hand, if the CPU does not determine that the condition Xn1 is satisfied (203: No), the CPU proceeds to step 205.

[0078] In step 204 , the CPU sets a flag FXn to “1.” Next, the CPU advances the processing to step 205 .

[0079] The CPU determines whether the index n is less than the maximum value max in step 205. If the CPU determines that the 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 the index n is less than the maximum value max (205: No), the CPU returns the process to step 201.

[0080] The CPU increments the index n in step 206 . Then, the CPU returns the process to step 202 .

[0081] Program PR3

[0082] Program PR3 includes the following processing (steps): sequentially selecting flags FXn (n=1, 2, 3, ..., max) as processing objects, and when condition Xn1 (condition Xn1 and condition Xn2 in a specific flag FXn) is not satisfied, changing the flag FXn from "1" to "0".

[0083] The CPU starts procedure PR3 ( Figure 5B ) is executed, causing the processing to enter step 301.

[0084] In step 301 , the CPU sets the index n of the flag FXn for specifying (selecting) a processing target to “1.” Next, the CPU advances the processing to step 302 .

[0085] The CPU determines whether the flag FXn is "1" in step 302. When the CPU determines that the flag FXn is "1" (302: Yes), the CPU proceeds to step 303. On the other hand, when the CPU does not determine that the flag FXn is "1" (302: No), the CPU proceeds to step 307 described later.

[0086] The CPU determines whether 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 described later.

[0087] In step 304, the CPU determines whether a specific flag FXn is selected as a processing target. That is, the CPU determines whether the index n matches (corresponds to) any one of the specific values ​​[a, b, c, ...]. If the CPU determines that the specific flag FXn is selected as the processing target (304: Yes), the CPU proceeds to step 305. On the other hand, if the CPU does not determine that the specific flag FXn is selected as the processing target (304: No), the CPU proceeds to step 306.

[0088] In step 305, the CPU determines whether condition Xn2 is satisfied. When the CPU determines that condition Xn2 is satisfied (305: Yes), the CPU proceeds to step 307. That is, in this case, the flag FXn is not changed. In other words, the CPU maintains the state of prohibiting hands-off. The state of prohibiting hands-off includes a state of setting a hand-holding mode with a lower driving assistance level than the hands-off mode. On the other hand, when the CPU does not determine that condition Xn2 is satisfied (305: No), the CPU proceeds to step 306.

[0089] In step 306 , the CPU sets the flag FXn to “0.” Next, the CPU advances the processing to step 307 .

[0090] The CPU determines whether the index n is less than the maximum value max in step 307. If the CPU determines that the 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 the index n is less than the maximum value max (307: No), the CPU returns the process to step 301.

[0091] The CPU increments the index n in step 308 . Then, the CPU returns the process to step 302 .

[0092] Next, a specific example of the process of determining whether the conditions Xn1 and Xn2 are satisfied will be described. When the brake pedal is not stepped on, the CPU executes program PR4 ( Fig. 6A ). In addition, the CPU executes program PR5 ( Figure 6B ).

[0093] Program PR4

[0094] The CPU starts execution of the program PR4 from step 400 , and proceeds to step 401 .

[0095] In step 401, the CPU determines whether there is a vehicle V1 that is likely to enter the area R0. When the CPU determines that the vehicle V1 exists (401: Yes), the CPU starts the inter-vehicle distance adjustment process and proceeds to step 402. On the other hand, when the CPU does not determine that the vehicle V1 exists (401: No), the CPU proceeds to step 404 described later.

[0096] In step 402, the CPU determines whether the distance Δd1 (predicted time TTC1) is smaller than the threshold value Δd1th (threshold value TTC1th). When the CPU determines that the distance Δd1 (predicted time TTC1) is smaller than the threshold value Δd1th (threshold value TTC1th) (402: Yes), the CPU proceeds to step 403. On the other hand, when the CPU does not determine that the distance Δd1 (predicted time TTC1) is smaller than the threshold value Δd1th (threshold value TTC1th) (402: No), the CPU proceeds to step 404.

[0097] 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 .

[0098] Furthermore, the CPU determines that the condition X31 is not satisfied in step 404. Next, the CPU advances the process to step 405, and in step 405, the execution of the program PR4 is terminated.

[0099] Program PR5

[0100] The CPU starts procedure PR5 from step 500 ( Figure 6B ) is executed, causing the processing to enter step 501.

[0101] In step 501, the CPU determines whether the vehicle V1 has entered the area R0. That is, the CPU determines whether it has detected that "the vehicle V1 has completed the jam (merging)". When the CPU determines that the vehicle V1 has entered the area R0 (501: Yes), the CPU causes the processing to proceed to step 504 described later. On the other hand, when the CPU does not determine that the vehicle V1 has entered the area R0 (501: No), the CPU causes the processing to proceed to step 502. "It is not determined that the vehicle V1 has entered the area R0" includes "the vehicle V1 is halfway into the area R0" and "the vehicle V1 has been lost".

[0102] The CPU determines in step 502 whether the vehicle V1 has been lost (can no longer be recognized). The vehicle V1 is the vehicle involved in the factor for setting the flag FX3 to "1". When the CPU determines that the vehicle V1 has been lost (502: Yes), the CPU proceeds to step 503. On the other hand, when the CPU does not determine that the vehicle V1 has been lost (502: No), the CPU proceeds to step 506.

[0103] The CPU determines whether the elapsed time Δt is greater than or equal to the threshold value Δtth in step 503. When the CPU determines that the elapsed time Δt is greater than or equal to the threshold value Δtth (503: Yes), the CPU proceeds to step 504 described later. On the other hand, when the CPU does not determine that the elapsed time Δt is greater than or equal to the threshold value Δtth (503: No), the CPU proceeds to step 506.

[0104] In step 504, the CPU determines whether the vehicle is traveling in the merging section M. When the CPU determines that the vehicle is traveling in the merging section M (504: Yes), the CPU proceeds to step 506. On the other hand, when the CPU does not determine that the vehicle is traveling in the merging section M (504: No), the CPU proceeds to step 505.

[0105] The CPU determines whether there is a vehicle V3 that is likely to enter the area R0 in step 505. If the CPU determines that the vehicle V3 exists (505: Yes), the CPU proceeds to step 506. On the other hand, if the CPU does not determine that the vehicle V3 exists (505: No), the CPU proceeds to step 507.

[0106] The CPU determines that the condition X32 is satisfied in step 506. In addition, the CPU determines that the condition X32 is not satisfied in step 507. Then, the CPU ends the execution of the program PR5 in step 508.

[0107] Effect

[0108] According to the driving assistance device 1, after the action mode MD (driving assistance level) is changed from the hands-off mode (first level) to the hands-on mode (second level), in a situation where the possibility that the condition Xn1 (first condition) is satisfied is high (in a situation where the condition Xn2 is satisfied), the action mode MD is maintained in the hands-on mode. Therefore, compared with the above-mentioned conventional device, frequent changes in the driving assistance level can be suppressed.

Claims

1. A driving assistance device that assists the driving operation of the vehicle. The driving assistance device comprises: The vehicle-mounted sensor acquires object information related to objects located around the vehicle; and a processor capable of determining a driving assistance level as a degree of assistance for the driving operation based on the object information, and executing driving assistance processing for controlling the host vehicle in a manner of providing assistance of the driving assistance level to the driver, The processor is configured as follows: During execution of a predetermined first-level driving assistance process, when a first condition, which is predetermined as a condition for lowering the driving assistance level, is satisfied, execution of a second-level driving assistance process lower than the first-level driving assistance process is started in place of the first-level driving assistance process, The driving assistance level is maintained at the second level while a second condition, which is predetermined as a condition for determining that the first condition is likely to be satisfied, is satisfied.

2. The driving assistance device according to claim 1, The processor is configured as follows: When it is determined that there is a high possibility that another vehicle traveling in a second driving lane adjacent to the first driving lane in which the host vehicle is traveling will enter the first driving lane, a vehicle distance adjustment process is performed to control a driving device and / or a braking device of the host vehicle in such a manner that the other vehicle can enter an area directly in front of the host vehicle. When the distance between the host vehicle and the other vehicle or the predicted time until the host vehicle and the other vehicle come into contact becomes smaller than a threshold value while the inter-vehicle distance adjustment process is being executed, it is determined that the first condition is satisfied.

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

4. The driving assistance device according to claim 2, The processor is configured to determine that the second condition is satisfied when there is a high possibility that another vehicle different from the other vehicle will enter the area.

5. The driving assistance device according to claim 2, The processor is configured to measure an elapsed time from a first time point at which the first condition is determined to be satisfied, and determine that the second condition is satisfied when the elapsed time is less than a threshold value if the other vehicle cannot be detected after the first time point.

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