Driving assistance device, driving assistance method, and driving assistance program

Abstract

PURPOSE: To provide an operation support device that controls an own vehicle so that the own vehicle starts running as expected by a driver, when a preceding vehicle starts running.SOLUTION: An operation support device 1 controls an own vehicle so that the own vehicle starts running in a predetermined first mode, in a first situation where a first condition for determining that a driver in the own vehicle pays attention to a place ahead of the own vehicle is satisfied, at a first time point at which a first condition for determining that a preceding vehicle has started running is satisfied, and controls the own vehicle so that the own vehicle starts running in a second mode in which acceleration of the own vehicle is suppressed more in comparison with the first mode, in a second situation where a second condition is not satisfied at the first time point and the first condition is satisfied at a second time point following the first time point.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a driving assistance device, a driving assistance method, and a driving assistance program that control a drive device of a vehicle so that the vehicle follows a preceding vehicle (another vehicle traveling immediately in front of the vehicle). [Background technology]

[0002] A driving assistance device has been proposed that, when a preceding vehicle starts moving while the preceding vehicle and the subject vehicle are stopped, causes the subject vehicle to start moving so as to follow the preceding vehicle (see, for example, Patent Document 1 below). When the driving assistance device of Patent Document 1 (hereinafter referred to as the "conventional device") detects that the preceding vehicle has started moving, it controls the subject vehicle so that the subject vehicle starts moving so as to follow the preceding vehicle. In other words, with the conventional device, when the preceding vehicle starts moving, the subject vehicle automatically starts moving without the driver having to operate a switch, accelerator pedal, or the like. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-86874 Summary of the Invention

[0004] Incidentally, when the driver of the host vehicle is looking ahead when the preceding vehicle starts moving (first situation), the driver has a high expectation that the host vehicle will start automatically. In contrast, when the driver of the host vehicle is not looking ahead when the preceding vehicle starts moving and then starts looking ahead after that (second situation), the driver's expectation that the host vehicle will start automatically is not so high. When starting the host vehicle, the conventional device controls the drive unit of the host vehicle so that the host vehicle's starting behavior (e.g., the behavior of acceleration change, the behavior of speed change, etc.) matches a predetermined behavior. In other words, the starting behavior of the host vehicle in the first situation is the same as the starting behavior of the host vehicle in the second situation. Therefore, for example, if the conventional device is configured to start the host vehicle with a relatively large acceleration, the driver may feel that the acceleration of the host vehicle is sudden in the second situation (a situation in which the driver's expectation that the host vehicle will start automatically is low). On the other hand, for example, if a conventional device is configured to allow the vehicle to start with a relatively small acceleration, in the first situation (a situation in which the driver has high expectations that the vehicle will start automatically), the driver may feel that the acceleration of the vehicle is sluggish.

[0005] An object of the present invention is to provide a driving assistance device that controls a vehicle when a preceding vehicle starts moving so that the vehicle starts moving in a manner that meets the driver's expectations.

[0006] To achieve the above object, a driving assistance device (1) of the present invention includes a forward sensor (21, 22, 23) that acquires information about the behavior of a preceding vehicle, a driver sensor (24) that acquires information about the direction in which a driver of the host vehicle is looking, and a processor (10) that controls the host vehicle to start in a predetermined manner when a predetermined first condition (v0>v0th, D>Dth) for determining that the preceding vehicle has started is satisfied in a situation in which the preceding vehicle has stopped and the host vehicle is stopped immediately behind the preceding vehicle. The processor controls the host vehicle to start in a predetermined first manner (Jc) in a first situation in which a second condition (θ≦θth) for determining that the driver of the host vehicle is looking ahead of the host vehicle is satisfied at a first time point when the first condition is satisfied, and controls the host vehicle to start in a second manner (Jd) in which acceleration of the host vehicle is suppressed compared to the first manner in a second situation in which the second condition is not satisfied at the first time point and the second condition is satisfied at a second time point thereafter.

[0007] In a first situation in which the driver is looking ahead at a first time point when the processor determines that the leading vehicle has started moving, the driver has a high expectation that the host vehicle will automatically start moving to follow the leading vehicle. On the other hand, in a second situation in which the driver is not looking ahead at the first time point and then starts looking ahead, the driver's expectation that the host vehicle will automatically start moving to follow the leading vehicle is not so high. The processor starts the host vehicle in a first manner in the first situation, and starts the host vehicle in a second manner in which the acceleration of the host vehicle is suppressed compared to the first manner in the second situation. Thus, according to the present invention, when the leading vehicle starts moving, the host vehicle can be started in a manner that meets the driver's expectations.

[0008] In one embodiment of the driving assistance device of the present invention, an alarm device (50) is provided that presents predetermined information to the driver of the vehicle, and the processor causes the alarm device to present information to encourage the driver of the vehicle to pay attention to what is ahead if the second condition is not met at the first point in time.

[0009] If the driver is not paying attention to what is ahead (if the driver is distracted), there is a risk that the driver will not notice that the preceding vehicle has started moving. According to this aspect, the notification device presents information to the driver. This allows the driver to recognize that the preceding vehicle has started moving and to pay attention to what is ahead.

[0010] In another aspect of the driving assistance device of the present invention, when starting the vehicle in the first situation, the processor controls the vehicle so that the jerk of the vehicle matches a first predetermined value (Jc), and when starting the vehicle in the second situation, the processor controls the vehicle so that the jerk of the vehicle matches a second predetermined value (Jd) that is smaller than the first predetermined value.

[0011] This allows the host vehicle to accelerate relatively slowly when starting in the second situation. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram of a towing determination device according to one embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing the direction (angle θ) in which the driver is looking. [Figure 3] FIG. 3 is a timing chart showing an outline of the follow-up start control in the first situation. [Figure 4] FIG. 4 is a timing chart showing an outline of the follow-up start control in the second situation. [Figure 5] FIG. 5 is a flowchart of a program that realizes the following start function. DETAILED DESCRIPTION OF THE INVENTION

[0013] (Summary) A driving assistance device 1 according to one embodiment of the present invention is applied to, for example, a vehicle V (hereinafter referred to as "host vehicle") equipped with an automatic driving function. When a preceding vehicle PV (a vehicle located immediately in front of the host vehicle) stops and the host vehicle stops immediately thereafter, the driving assistance device 1 has a function (automatic start function) of controlling a drive unit of the host vehicle so that the host vehicle starts following the preceding vehicle PV when a predetermined condition is met at the time when the preceding vehicle PV has started moving or thereafter.

[0014] (Specific configuration) As shown in FIG. 1, the driving assistance device 1 includes a driving assistance ECU 10, an on-vehicle sensor 20, a drive device 30, a braking device 40, and a buzzer 50.

[0015] The driving assistance ECU 10 includes a microcomputer equipped with a CPU 10a, a ROM 10b, a RAM 10c, a timer 10d, etc. The driving assistance ECU 10 is connected to other ECUs provided in the vehicle via a CAN (Controller Area Network).

[0016] The on-board sensor 20 includes a forward sensor that acquires information about the preceding vehicle PV. Specifically, the on-board sensor 20 includes a millimeter wave radar 21, a sonar 22, and a forward camera 23 as forward sensors.

[0017] The millimeter-wave radar 21 includes a transmitter / receiver and a signal processor (not shown). The transmitter / receiver emits millimeter-wave band radio waves (hereinafter referred to as "millimeter waves") ahead of the vehicle and receives millimeter waves (reflected waves) reflected by a three-dimensional object (a leading vehicle PV) located within the emission range. The signal processor calculates the distance between the vehicle and the three-dimensional object, the speed of the three-dimensional object, and the like based on the time from when the transmitter / receiver 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 level of the reflected waves, and the like, and transmits the calculation results to the driving assistance ECU 10.

[0018] The sonar 22 intermittently emits ultrasonic waves into the area surrounding the vehicle and receives the ultrasonic waves (reflected waves) reflected by a three-dimensional object. Based on the time from when the ultrasonic waves are transmitted until when the reflected waves are received, the sonar 22 calculates 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, and transmits the calculation results to the driving assistance ECU 10.

[0019] The forward camera 23 includes an imaging device and an image analysis device. The imaging device is, for example, a digital camera incorporating an imaging element such as a charge coupled device (CCD) or a CMOS image sensor (CIS). The imaging device is positioned above the front windshield glass and faces forward. The imaging device captures images of the front view of the vehicle at a predetermined frame rate to acquire image data. The imaging device transmits the image data to the image analysis device. The image analysis device analyzes the acquired image data and acquires information about objects located in front of the vehicle from the images. For example, the image analysis device identifies (recognizes) the type of object located in front of the vehicle (e.g., another vehicle, a guardrail, etc.) and transmits the identification result to the driving assistance ECU 10.

[0020] Furthermore, the on-vehicle sensor 20 includes a driver sensor (driver monitor) that acquires information about the driver's state (the direction in which the driver is looking). Specifically, the on-vehicle sensor 20 includes an in-vehicle camera 24 as a driver sensor.

[0021] Like the front camera 23, the in-vehicle camera 24 includes an imaging device and an image analysis device. The imaging device is installed, for example, in the dashboard (instrument panel) of the vehicle and faces the driver's seat. The imaging device captures images of the driver at a predetermined frame rate and outputs the acquired image data to the image analysis device. The image analysis device analyzes the acquired image data and calculates the direction in which the driver is looking (for example, as shown in FIG. 2 , the angle θ with respect to the longitudinal direction D0 of the vehicle in a plan view) based on the orientation of the driver's face, the orientation of the driver's eyes, etc. The image analysis device transmits the calculation result (angle θ) to the driving assistance ECU 10.

[0022] Additionally, the on-board sensor 20 includes a vehicle sensor that acquires information about the running state (speed and acceleration) of the vehicle itself. Specifically, the on-board sensor 20 includes a speed sensor 25 and an acceleration sensor 26 as vehicle sensors.

[0023] The speed sensor 25 detects the rotation speed (wheel speed) of each wheel and calculates the speed vs (actual vehicle speed) of the host vehicle based on the wheel speed of each wheel. The speed sensor 25 transmits data representing the speed vs to the driving assistance ECU 10.

[0024] The acceleration sensor 26 detects the acceleration α of the host vehicle in the longitudinal direction. The acceleration sensor 26 transmits data representing the acceleration α to the driving assistance ECU 10. The acceleration sensor 26 also calculates a jerk J (jerk) based on time-series data of the acceleration α. ​​The acceleration sensor 26 transmits the data representing the jerk J to the driving assistance ECU 10.

[0025] Furthermore, the on-board sensors 20 include a resume switch 27 and an accelerator pedal sensor 28 as operation sensors. The resume switch 27 includes a push-button type switch element. The resume switch 27 is incorporated, for example, into a spoke of a steering wheel. The driving assistance ECU 10 monitors the on / off state of the resume switch 27. The accelerator pedal sensor 28 detects the depression depth AD of the accelerator pedal AP of the host vehicle. The accelerator pedal sensor 28 transmits data indicating the detected depression depth AD to the driving assistance ECU 10.

[0026] The drive unit 30 applies drive force to the drive wheels. The drive unit 30 includes an engine ECU, an internal combustion engine, a transmission, a drive force transmission mechanism that transmits drive force to the wheels, and the like. The engine ECU acquires information (target value) indicating a target drive force from another ECU (the driving assistance ECU 10), and based on this information, drives the throttle valve of the internal combustion engine to control the drive force applied to the drive wheels. The drive force generated by the internal combustion engine is transmitted to the drive wheels via the transmission and the drive force transmission mechanism. The engine ECU also acquires information (control signal) related to the shift position of the transmission provided in the vehicle, and controls the shift position based on this information.

[0027] 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 the 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 can be used instead of the engine ECU to control the driving force of the vehicle generated by an electric motor as the vehicle driving source.

[0028] The braking device 40 applies braking force to the wheels (brake discs). The braking device 40 includes a brake ECU, a brake caliper, etc. The brake caliper includes an actuator that presses brake pads against the brake discs. The brake ECU acquires information (control signal) indicating a target braking force from another ECU, and drives the actuator of the brake caliper based on that information. In this way, the braking force applied to the wheels (brake discs) is controlled.

[0029] In response to a command transmitted from the driving assistance ECU 10, the buzzer 50 reproduces (sounds) a predetermined sound (chime).

[0030] (Activation) When an ACC switch (not shown) mounted on the host vehicle is in an on state, the driving assistance ECU 10 determines whether or not a preceding vehicle PV is present, as will be described below, and controls the drive device 30 and braking device 40 (hereinafter referred to as "drive device, etc.") of the host vehicle based on the determination result. This control is sometimes referred to as adaptive cruise control (ACC). ACC includes constant speed traveling control and inter-vehicle distance maintenance control.

[0031] [Constant-Speed ​​Cruise Control] The driving assistance ECU 10 determines whether or not a preceding vehicle PV exists based on information acquired from forward sensors (millimeter-wave radar 21, sonar 22, and forward camera 23). If a preceding vehicle PV does not exist, the driving assistance ECU 10 executes constant-speed cruise control. Specifically, the driving assistance ECU 10 controls the drive device and the like so that the speed vs of the host vehicle coincides with a predetermined speed vd (for example, the speed at which the fuel consumption rate is lowest).

[0032] [Inter-vehicle distance maintenance control] On the other hand, when the driving assistance ECU 10 determines that a preceding vehicle PV is present, it executes inter-vehicle distance maintenance control. Specifically, the driving assistance ECU 10 acquires the inter-vehicle distance D between the preceding vehicle PV and the subject vehicle and the speed v0 of the preceding vehicle PV from a forward sensor. Furthermore, the driving assistance ECU 10 acquires the speed vs of the subject vehicle from the speed sensor 25. The driving assistance ECU 10 calculates a target distance Dd for the inter-vehicle distance D based on the speed vs of the subject vehicle and the speed v0 of the preceding vehicle PV, etc.

[0033] When the speed v0 of the preceding vehicle PV relative to the speed vs of the host vehicle (relative speed vr = v0 - vs) is greater than "0", the inter-vehicle distance D increases. When the inter-vehicle distance D is greater than the target distance Dd, the driving assistance ECU 10 sets the target value of the acceleration α of the host vehicle to a predetermined value α1 (>0) so that the speed vs of the host vehicle becomes greater than the speed v0 of the preceding vehicle PV. Then, the driving assistance ECU 10 controls the drive devices and the like so that the acceleration α (actual measured value) of the host vehicle matches the predetermined value α1 (acceleration control). As a result, the inter-vehicle distance D decreases and approaches the target distance Dd. Then, when the inter-vehicle distance D matches the target distance Dd, the driving assistance ECU 10 sets the target value of the acceleration α of the host vehicle to "0". In other words, the driving assistance ECU 10 controls the drive devices and the like so that the host vehicle travels at the same speed as the preceding vehicle PV.

[0034] On the other hand, when the relative speed vr is smaller than "0", the inter-vehicle distance D decreases. When the inter-vehicle distance D is smaller than the target distance Dd, the driving assistance ECU 10 sets the target value of the acceleration α to a predetermined value α2 (<0) so that the speed vs of the host vehicle becomes smaller than the speed v0 of the preceding vehicle PV. Then, the driving assistance ECU 10 controls the drive device, etc. so that the acceleration α (actual measured value) of the host vehicle matches the predetermined value α2 (deceleration control). As a result, the inter-vehicle distance D increases and approaches the target distance Dd. Then, when the inter-vehicle distance D matches the target distance Dd, the driving assistance ECU 10 sets the target value of the acceleration α of the host vehicle to "0".

[0035] The target distance Dd is correlated with the speed vs of the host vehicle and the speed v0 of the preceding vehicle PV. For example, the target distance Dd when the speed vs and the speed v0 are relatively small is shorter than the target distance Dd when the speed vs and the speed v0 are relatively large. A database (table) showing the relationship between the speed vs, v0 and the target distance Dd or parameters defining an arithmetic expression for calculating the target distance Dd are stored in the ROM 10b. The driving assistance ECU 10 determines the target distance Dd based on the database or the arithmetic expression.

[0036] If the preceding vehicle PV stops (v0=0 km / h) while the vehicle distance maintenance control is being executed, the driving assistance ECU 10 stops the host vehicle behind the preceding vehicle PV (vs=0 km / h). After that, when the preceding vehicle PV starts moving, the driving assistance ECU 10 has a function (following start function) to execute follow-up start control that controls the drive device and the like so that the host vehicle starts moving in a manner following the preceding vehicle PV, as will be described below.

[0037] [Follow-Start Control] The driving assistance ECU 10 measures the time Δt that has elapsed since the time t0 when the host vehicle stopped behind the stopped preceding vehicle PV. The driving assistance ECU 10 also sequentially determines whether the preceding vehicle PV has started moving based on information acquired from a forward sensor. For example, the driving assistance ECU 10 determines that the preceding vehicle PV has started moving (preceding vehicle start flag FPS="1") when the speed v0 of the preceding vehicle PV acquired from the millimeter-wave radar 21 exceeds a predetermined threshold v0th (when the first condition is met). Alternatively, for example, the driving assistance ECU 10 may determine that the preceding vehicle PV has started moving when the distance D between the preceding vehicle PV and the host vehicle exceeds a threshold Dth.

[0038] If the time Δt from time t0 when the host vehicle stops behind the preceding vehicle PV to time t1 when it is determined that the preceding vehicle PV has started is equal to or less than a threshold value Δtth (e.g., 3 seconds), the driving assistance ECU 10 controls the drive devices and the like so that the host vehicle starts to move following the preceding vehicle PV. After the host vehicle starts to move, the driving assistance ECU 10 controls the drive devices and the like so that the acceleration α of the host vehicle gradually increases and reaches a predetermined value α1. In this case, the driving assistance ECU 10 controls the drive devices and the like so that the jerk J of the host vehicle matches the predetermined value Ja.

[0039] Furthermore, if the time Δt from time t0 to time t1 exceeds the threshold value Δtth, the driving assistance ECU 10 controls the host vehicle as follows.

[0040] The driving assistance ECU 10 starts the host vehicle when it detects that the driver has performed a predetermined operation. The predetermined operation is an operation that indicates that the driver intends to start the host vehicle. Specifically, the driving assistance ECU 10 starts the host vehicle when it detects, for example, that the resume switch 27 has been pressed. Furthermore, the driving assistance ECU 10 starts the host vehicle when it detects, for example, based on information acquired from the accelerator pedal sensor 28, that the depression depth AD of the accelerator pedal AP has returned to "0" (released state) immediately after exceeding a relatively shallow threshold.

[0041] When the driver operates the resume switch 27 or the accelerator pedal AP as a trigger to start the host vehicle, the driving assistance ECU 10 controls the drive devices, etc. so that the acceleration α of the host vehicle gradually increases and reaches a predetermined value α1. The driving assistance ECU 10 controls the drive devices, etc. so that the jerk J at that time matches a predetermined value Jb. Note that the predetermined value Jb is, for example, larger than the predetermined value Ja. However, the predetermined value Jb may be the same as the predetermined value Ja or may be smaller than the predetermined value Ja.

[0042] Furthermore, if the time Δt from time t0 to time t1 exceeds the threshold value Δtth, the driving assistance ECU 10 starts the host vehicle even if the resume switch 27 or the accelerator pedal AP is not operated, only if the driver of the host vehicle is looking ahead at time t1 when it is determined that the preceding vehicle PV has started (the time when the preceding vehicle start flag FPS transitions from "0" to "1") or thereafter. FIG. 3 is a timing chart showing an outline of the follow-up start control when the driver of the host vehicle is looking ahead at time t1. FIG. 4 is a timing chart showing an outline of the follow-up start control when the driver of the host vehicle is not looking ahead at time t1 but is looking ahead at time t2, which is later than time t1.

[0043] Specifically, in a situation where the time Δt exceeds a threshold value Δtth, as shown in FIG. 3, the driving assistance ECU 10 sequentially acquires the angle θ from the in-vehicle camera 24 and determines whether the driver is looking ahead based on the angle θ. If the angle θ is equal to or less than the threshold value θth (if the second condition is met), the driving assistance ECU 10 determines that the driver is looking ahead. If the driving assistance ECU 10 determines that the driver is looking ahead at time t1 (i.e., if the forward attention flag FA=1 at time t1), it controls the drive system and the like so that the host vehicle starts following the preceding vehicle PV. That is, the host vehicle start flag FVS is set to 1 at time t1. This causes the host vehicle to start at time t1.

[0044] On the other hand, as shown in Fig. 4, if it is determined that the driver is not paying attention to the road ahead (looking aside) at time t1 (i.e., if the forward attention flag FA = 0 at time t1), the driving assistance ECU 10 sounds the buzzer 50 (buzzer flag FB = 1) to prompt the driver to pay attention to the road ahead, while continuing to sequentially acquire the angle θ from the in-vehicle camera 24. If the driving assistance ECU 10 determines that the driver is paying attention to the road ahead at time t2, which is later than time t1, it controls the drive device and the like so that the host vehicle starts following the leading vehicle PV. That is, the host vehicle start flag FVS is set to 1 at time t2, which is later than time t1. This causes the host vehicle to start at time t2.

[0045] As described above, if the driver is looking ahead at time t1 when it is determined that the preceding vehicle PV has started moving (hereinafter referred to as the "first situation"), the driving assistance ECU 10 starts the host vehicle without sounding the buzzer 50. In this case, the driving assistance ECU 10 controls the drive device, etc. so that the jerk J matches the predetermined value Jc. On the other hand, if the driver is not looking ahead at time t1, the driving assistance ECU 10 sounds the buzzer 50. If the driver then starts looking ahead (hereinafter referred to as the "second situation"), the driving assistance ECU 10 starts the host vehicle. In this case (when the host vehicle is started after sounding the buzzer 50), the driving assistance ECU 10 controls the drive device, etc. so that the jerk J matches a predetermined value Jd that is smaller than the predetermined value Jc. Note that the predetermined value Jc is smaller than the predetermined value Ja, for example. However, the predetermined value Jc may be the same as the predetermined value Ja or the predetermined value Jb, or may be greater than the predetermined value Ja or the predetermined value Jb.

[0046] Next, referring to Figure 5, a program PR1 executed by the CPU 10a (hereinafter referred to as "CPU") of the driving assistance ECU 10 to realize the following start function will be described. When the preceding vehicle PV stops while the CPU is executing the following distance maintenance control, the CPU stops the host vehicle behind the preceding vehicle PV. At this time t0, the CPU starts execution of the program PR1. The CPU starts execution of the program PR1 from step 100 and proceeds to step 101.

[0047] When the CPU proceeds to step 101, it causes the timer 10d to start measuring the time Δt. Then, the CPU proceeds to step 102, where it determines whether the leading vehicle PV has started moving based on information acquired from the forward sensors (at least one of the millimeter-wave radar 21, the sonar 22, and the forward camera 23). If the CPU determines that the leading vehicle PV has started moving (102: Yes), it proceeds to step 103. On the other hand, if the CPU determines that the leading vehicle PV has not started moving (102: No), it returns to step 102.

[0048] When the CPU proceeds to step 103, it determines whether the measured time Δt is equal to or less than the threshold value Δtth. If the time Δt is equal to or less than the threshold value Δtth (103: Yes), the CPU proceeds to step 104 and controls the drive device, etc. so that the host vehicle starts following the preceding vehicle PV. At that time, the CPU controls the drive device, etc. so that the jerk J matches a predetermined value Ja. Then, the CPU proceeds to step 113 and ends execution of the program PR1.

[0049] On the other hand, if the measured time Δt exceeds the threshold value Δtth (103: No), the CPU proceeds to step 105, where it determines whether or not an operating device of the host vehicle (resume switch 27 or accelerator pedal AP) has been operated. If the CPU determines that an operating device has been operated (105: Yes), it proceeds to step 106, where it controls the drive system and the like so that the host vehicle starts to follow the preceding vehicle PV. At that time, the CPU controls the drive system and the like so that the jerk J coincides with a predetermined value Jb. Then, the CPU proceeds to step 113, where it ends execution of program PR1.

[0050] On the other hand, if it is determined in step 105 that the operating device has not been operated (105: No), the CPU proceeds to step 107, where it determines whether the driver is looking ahead based on the information acquired from the in-vehicle camera 24. If the CPU determines that the driver is looking ahead (FA = 1) (107: Yes), it proceeds to step 109, which will be described later. On the other hand, if the CPU determines that the driver is not looking ahead (FA = 0) (107: No), it proceeds to step 108, where it sounds the buzzer 50 for a predetermined period of time (FB←1). Then, the CPU returns to step 105. Here, the buzzer flag FB indicates whether or not a warning by sounding the buzzer 50 has been issued. If the warning has not been issued, the buzzer flag FB is "0," and if the warning has been issued, the buzzer flag FB is "1." The CPU may sound the buzzer 50 continuously or intermittently until the host vehicle starts moving.

[0051] When the CPU proceeds to step 109, it determines whether the buzzer 50 has performed notification. If the notification has not been performed (FB = 0, 109: No), the CPU proceeds to step 110 and controls a driving device or the like so that the host vehicle starts following the preceding vehicle PV. At that time, the CPU controls the driving device or the like so that the jerk J matches a predetermined value Jc. Then, the CPU proceeds to step 113 and ends the execution of the program PR1.

[0052] On the other hand, if the notification has been performed (FB = 1, 109: Yes), the CPU proceeds from step 109 to step 111 and controls a driving device or the like so that the host vehicle starts following the preceding vehicle PV. At that time, the CPU controls the driving device or the like so that the jerk J matches a predetermined value Jd (<Jc). Then, the CPU proceeds to step 112.

[0053] When the CPU proceeds to step 112, it initializes the buzzer flag FB (FB ← 0), proceeds to step 113, and ends the execution of the program PR1.

[0054] When the CPU proceeds from step 105 to step 106, if the buzzer 50 was sounding, it stops the sounding of the buzzer 50.

[0055] (Effect) In a first situation where the driver is looking ahead at time t1 when the driving assistance ECU 10 determines that the preceding vehicle PV has started moving, the driver has a high expectation that the host vehicle will start moving in a manner following the preceding vehicle PV. On the other hand, in a second situation where the driver is not looking ahead at time t1 and then starts looking ahead, the driver's expectation that the host vehicle will start moving in a manner following the preceding vehicle PV is not so high. The driving assistance ECU 10 controls the drive device, etc. so that the jerk J matches a predetermined value Jc in the first situation and so that the jerk J matches a predetermined value Jd that is smaller than the predetermined value Jc in the second situation. Therefore, the acceleration of the host vehicle in the second situation is gentler than the acceleration of the host vehicle in the first situation. In other words, the driving assistance ECU 10 starts the host vehicle in a first manner in the first situation and starts the host vehicle in a second manner in the second situation in which the acceleration of the host vehicle is suppressed compared to the first manner. Therefore, when the preceding vehicle PV starts moving, the driving support device 1 can make the host vehicle start moving in a manner that meets the driver's expectations.

[0056] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

[0057] <Modification 1> In the above embodiment, the driving assistance ECU 10 controls the drive devices, etc. so that the jerk J coincides with a predetermined value Jc in the first situation and coincides with a predetermined value Jd, which is smaller than the predetermined value Jc, in the second situation. That is, the rate of change of the acceleration α in the first situation and the rate of change of the acceleration α in the second situation are constant. The rate of change of the acceleration α in the first situation and the second situation do not have to be constant. For example, the driving assistance ECU 10 may store predetermined acceleration increase characteristics corresponding to the first situation and the second situation, respectively, and control the drive devices, etc. so that the acceleration α changes in accordance with the acceleration increase characteristics corresponding to each situation in the first situation and the second situation. In this case, the acceleration increase characteristic in the second situation is set to be gentler than the acceleration increase characteristic in the first situation. The driving assistance ECU 10 may also store predetermined speed increase characteristics indicating changes in the target value of the host vehicle's speed vs for the first situation and the second situation, respectively. In the first situation and the second situation, the driving assistance ECU 10 may control the drive device, etc., so that the speed vs of the host vehicle changes according to the speed characteristics respectively set for the first situation and the second situation. Furthermore, the start timing of the host vehicle in the second situation may be delayed compared to the start timing of the host vehicle in the first situation. According to these configurations, the acceleration of the host vehicle in the second situation is suppressed compared to the acceleration of the host vehicle in the first situation.

[0058] <Modification 2> In the above embodiment, if the driver is not paying attention to the road ahead at time t1, the driving assistance ECU 10 sounds the buzzer 50. However, even if the buzzer 50 is not sounded, the driver may notice that the preceding vehicle has started moving and may start paying attention to the road ahead. Therefore, if the driver is not paying attention to the road ahead at time t1, the driving assistance ECU 10 may wait without sounding the buzzer 50. In this case, if the driving assistance ECU 10 determines that the driver has started paying attention to the road ahead after time t1, it may start the vehicle in a manner in which acceleration of the vehicle is suppressed, as in the above embodiment. [Explanation of symbols]

[0059] 1... Driving assistance device, 10... Driving assistance ECU, 20... In-vehicle sensor

Claims

1. a forward sensor that acquires information about the behavior of a preceding vehicle; a driver sensor that acquires information about the direction in which the driver of the vehicle is looking; a processor that controls the host vehicle so that the host vehicle starts in a predetermined manner when a predetermined first condition for determining that the preceding vehicle has started is satisfied in a situation where the preceding vehicle has stopped and the host vehicle has stopped immediately behind the preceding vehicle; A driving assistance device comprising: The processor: controlling the host vehicle so that the host vehicle starts in a predetermined first manner in a first situation in which a second condition for determining that the driver of the host vehicle has been paying attention to a road ahead of the host vehicle is satisfied at a first time point in time when the first condition is satisfied; In a second situation in which the second condition is not satisfied at the first time point and the second condition is satisfied at a subsequent second time point, the host vehicle is controlled so that the host vehicle starts in a second manner in which acceleration of the host vehicle is suppressed compared to the first manner. A driving assistance device configured as follows.

2. The driving assistance device according to claim 1, a notification device that presents predetermined information to a driver of the vehicle; The processor is configured to cause the notification device to present information to encourage the driver of the vehicle to pay attention to the road ahead if the second condition is not met at the first point in time.

3. The driving assistance device according to claim 1 or 2, The processor: When starting the host vehicle in the first situation, the host vehicle is controlled so that a jerk of the host vehicle coincides with a first predetermined value; When starting the host vehicle in the second situation, the host vehicle is controlled so that the jerk of the host vehicle coincides with a second predetermined value that is smaller than the first predetermined value. A driving assistance device configured as follows.

4. a first information acquisition step of acquiring information about the behavior of a preceding vehicle from a forward sensor; a second information acquisition step of acquiring information relating to a direction in which a driver of the host vehicle is looking from a driver sensor; a following start step of controlling the host vehicle so that the host vehicle starts in a predetermined manner when a predetermined first condition for determining that the preceding vehicle has started is satisfied in a situation where the preceding vehicle has stopped and the host vehicle has stopped immediately behind the preceding vehicle; A driving assistance method including: The following starting step includes: controlling the host vehicle so that the host vehicle starts in a predetermined first manner in a first situation in which a second condition for determining that the driver of the host vehicle has been paying attention to a road ahead of the host vehicle is satisfied at a first time point in time when the first condition is satisfied; and controlling the host vehicle so that, in a second situation in which the second condition is not satisfied at the first time point and the second condition is satisfied at a subsequent second time point, the host vehicle starts in a second manner in which acceleration of the host vehicle is suppressed compared to the first manner. The driving assistance method is configured as follows.

5. The computer installed in the vehicle a first information acquisition step of acquiring information about the behavior of a preceding vehicle from a forward sensor; a second information acquisition step of acquiring information about a direction in which a driver of the vehicle is looking from a driver sensor; a following start step of controlling the host vehicle so that the host vehicle starts in a predetermined manner when a predetermined first condition for determining that the preceding vehicle has started is satisfied in a situation where the preceding vehicle has stopped and the host vehicle has stopped immediately behind the preceding vehicle; A driving assistance program that executes The following starting step includes: controlling the host vehicle so that the host vehicle starts in a predetermined first manner in a first situation in which a second condition for determining that the driver of the host vehicle has been paying attention to a road ahead of the host vehicle is satisfied at a first time point in time when the first condition is satisfied; and controlling the host vehicle so that, in a second situation in which the second condition is not satisfied at the first time point and the second condition is satisfied at a subsequent second time point, the host vehicle starts in a second manner in which acceleration of the host vehicle is suppressed compared to the first manner. This is a driving assistance program designed to:

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