Driving assistance device and program

Abstract

To prevent unintentional prohibition or release of deceleration control.SOLUTION: A drive assistance device comprises an object recognition unit 40 and a processor 10. The processor 10 comprises: a first control unit 150 for executing a first control for avoiding a collision or reducing damage when a first condition indicating a possibility of the collision with an object is satisfied; a second control unit 160 for executing, when a second condition indicating that steering operation of a driver is in a predetermined operation state is satisfied, a second control for prohibiting or releasing the execution of the first control even when the first condition is satisfied; and a condition changing unit 160 for determining whether the steering operation state of the driver or behavior of an own vehicle is in a specific state that is inappropriate for a traveling road on which the own vehicle is traveling, and when determining to be in the specific state, changing a determination condition for determining whether the second condition is satisfied so that the second condition is more difficult to be satisfied than when determining not to be in the specific state.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a driving assistance device and a program that perform control based on the possibility of a collision with an object detected in front of a vehicle. [Background technology]

[0002] Patent Document 1 discloses a device that makes it more difficult to establish the conditions for executing a steering override in a control (Pre-Crash Safety Control: hereinafter referred to as PCS control) for avoiding a collision or reducing damage caused by a collision when it is determined that the driver of a vehicle has erroneously pressed the accelerator pedal, compared to when it is not determined that an erroneous operation has occurred. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-079904 Summary of the Invention

[0004] If the driver is in an inattentive state while driving, such as when the driver is fatigued and not paying attention to the surroundings, the driver may not perform the steering operation appropriately. In such a situation where the reliability of the driver's steering operation is reduced, if the conditions for executing the steer override are easily met, there is a risk that the deceleration control by the PCS control may be unintentionally prohibited or canceled.

[0005] The technology disclosed herein aims to effectively prevent deceleration control by PCS control from being unintentionally prohibited or canceled by steering override.

[0006] The present disclosure provides a driving assistance device for a vehicle, the driving assistance device including: a target recognition unit that recognizes targets present around the host vehicle; and a processor. The processor includes: a first control unit that, when a first condition is met that there is a possibility that the host vehicle will collide with the target recognized by the target recognition unit, executes a first control to avoid a collision between the target and the host vehicle or to reduce damage caused by the collision; a second control unit that, when a second condition is met that a steering operation by a driver of the host vehicle is in a predetermined operating state, executes a second control to prohibit execution of the first control if the first control has not yet been executed, and to cancel the first control if the first control is being executed; and a condition change unit that determines whether the steering operation state of the driver or the behavior of the host vehicle due to the steering operation by the driver is in a specific state that is inappropriate for a road on which the host vehicle is traveling, and, when it is determined that the specific state is met, changes a determination condition for determining whether the second condition is met so that the second condition is less likely to be met than when it is determined that the specific state is not met. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram showing a hardware configuration of a vehicle according to an embodiment of the present invention. [Figure 2] 1A is a schematic diagram showing the software configuration of a control device according to the present embodiment, and FIGS. 1B to 1D are schematic diagrams illustrating an example in which the vehicle's behavior is unstable. [Figure 3] 1 is a flowchart illustrating a processing routine according to the present embodiment. [Figure 4] 1 is a flowchart illustrating a processing routine according to the present embodiment. [Figure 5] 1 is a flowchart illustrating a processing routine according to the present embodiment. [Figure 6] 10 is a flowchart illustrating a processing routine of a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, a driving assistance device and a program according to this embodiment will be described with reference to the drawings.

[0009] [Hardware configuration] 1 is a schematic diagram showing the hardware configuration of a vehicle SV to which a driving assistance device according to this embodiment is applied. Hereinafter, the vehicle SV may also be referred to as the host vehicle when it is necessary to distinguish it from other vehicles.

[0010] The vehicle SV has an ECU (Electronic Control Unit) 10. The ECU 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, and an interface device 14. The CPU 11 is a processor that executes various programs stored in the ROM 12. The ROM 12 is a non-volatile memory that stores data and the like required for the CPU 11 to execute the various programs. The RAM 13 is a volatile memory that provides a working area into which the various programs are expanded when the CPU 11 executes them. The interface device 14 is a communication device for communicating with external devices.

[0011] The ECU 10 is a central device that performs driving assistance controls such as PCS control, adaptive cruise control (hereinafter referred to as ACC), lane trace assist control (hereinafter referred to as LTA), and lane departure alert control (hereinafter referred to as LDA). Driving assistance control is a concept that includes autonomous driving control. The ECU 10 is communicably connected to a drive unit 20, a steering unit 21, a braking unit 22, an internal sensor unit 30, a steering touch sensor (hereinafter referred to as touch sensor) 38, an external sensor unit 40, an LTA start switch 65, a display unit 90, a speaker 95, and the like.

[0012] The drive device 20 generates a drive force to be transmitted to the drive wheels of the vehicle SV. Examples of the drive device 20 include an electric motor and an engine. In this embodiment, the vehicle SV may be a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), a fuel cell vehicle (FCEV), an electric vehicle (BEV), or an engine vehicle. The steering device 21 applies a steering force to the wheels of the vehicle SV. The braking device 22 applies a braking force to the wheels of the vehicle SV.

[0013] The internal sensor device 30 is a group of sensors that detect the state of the vehicle SV. Specifically, the internal sensor device 30 includes a vehicle speed sensor 31, an accelerator sensor 32, a brake sensor 33, a steering angle sensor 34, a yaw rate sensor 35, and the like.

[0014] The vehicle speed sensor 31 detects the traveling speed (vehicle speed V) of the vehicle SV. The accelerator sensor 32 detects the amount of operation of an accelerator pedal (not shown) by the driver. The brake sensor 33 detects the amount of operation of a brake pedal (not shown) by the driver. The steering angle sensor 34 detects the rotation angle of a steering wheel or steering shaft (not shown) of the vehicle SV, i.e., the steering angle. The yaw rate sensor 35 detects the yaw rate of the vehicle SV. The internal sensor device 30 transmits the state of the vehicle SV detected by each sensor 31 to 35 to the ECU 10 at a predetermined interval.

[0015] The touch sensor 38 is a sensor that detects whether or not the driver is gripping the steering wheel. When the driver is gripping the steering wheel, the touch sensor 38 transmits a gripping signal to the ECU 10. Note that, if the internal sensor device 30 includes a steering torque sensor that detects steering torque, the driver's gripping of the steering wheel may be detected based on the steering torque.

[0016] The external sensor device 40 is a type of sensor that recognizes target information related to targets around the vehicle SV. Specifically, the external sensor device 40 includes a radar sensor 41, a camera sensor 42, etc. Examples of target information include nearby vehicles, pedestrians, traffic lights, white lines on the road, signs, fallen objects, etc.

[0017] The radar sensor 41 is provided, for example, at the front of the vehicle SV and detects targets present in the area ahead of the vehicle SV. The radar sensor 41 includes a millimeter-wave radar and / or a lidar. The millimeter-wave radar emits millimeter-wave radio waves (millimeter waves) and receives millimeter waves (reflected waves) reflected by targets present within the emission range. The millimeter-wave radar acquires the relative distance and relative speed between the vehicle SV and the target based on the phase difference between the transmitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from transmitting the millimeter waves to receiving the reflected waves. The lidar sequentially scans a pulsed laser beam with a wavelength shorter than that of millimeter waves in multiple directions and receives the reflected light reflected by the target to acquire the shape of the target detected ahead of the vehicle SV, the relative distance and relative speed between the vehicle SV and the target, etc.

[0018] The camera sensor 42 is, for example, a stereo camera or a monocular camera, and a digital camera having an imaging element such as a CMOS or CCD can be used. The camera sensor 42 is disposed, for example, above the front windshield glass of the vehicle SV. The camera sensor 42 captures an image of the area ahead of the vehicle SV and processes the captured image data to acquire target information ahead of the vehicle SV. The target information is information that indicates the type of target detected ahead of the vehicle SV, the relative distance between the vehicle SV and the target, the relative speed between the vehicle SV and the target, etc. The type of target may be recognized, for example, by machine learning such as pattern matching.

[0019] The external sensor device 40 repeatedly transmits the acquired target object information to the ECU 10 every time a predetermined time period has elapsed. The ECU 10 determines the relative relationship between the vehicle SV and the target by combining the relative relationship between the vehicle SV and the target obtained by the radar sensor 41 and the relative relationship between the vehicle SV and the target obtained by the camera sensor 42. Note that the external sensor device 40 does not necessarily have to include both the radar sensor 41 and the camera sensor 42, and may include, for example, only the radar sensor 41 or only the camera sensor 42.

[0020] The LTA activation switch 65 is provided near the driver's seat (for example, on the steering wheel, etc.) The LTA activation switch 65 is an ON / OFF switch that allows the driver to select whether to activate or terminate the LTA.

[0021] The display device 90 is, for example, a multi-information display, a head-up display, a display of a navigation system, or the like, and displays various images in response to commands from the ECU 10. The speaker 95 is, for example, a speaker of an audio system or a navigation system, and outputs warning sounds and the like in response to commands from the ECU 10.

[0022] [Software configuration] 2A is a schematic diagram showing the software configuration of the ECU 10 according to this embodiment. As shown in FIG. 2A, the ECU 10 includes, as functional elements, an LTA control unit 110, a sway determination unit 120, a hands-off determination unit 130, an inattention determination unit 140, a PCS control unit 150, and a steering override control unit 160. These functional elements 110-160 are realized by the CPU 11 of the ECU 10 reading a program stored in the ROM 12 into the RAM 13 and executing the program. Note that all or part of the functional elements 110-160 may be provided in another ECU separate from the ECU 10, or in an information processing device in a facility (such as a management center) that can communicate with the vehicle SV.

[0023] The LTA control unit 110 executes the LTA, which automatically changes the steering angle (the steering angle of the steered wheels) so that the position of the host vehicle SV is maintained near a target driving line within the driving lane. Since the LTA itself is well known, it will be briefly described below. When the LTA activation switch 65 is turned on, the LTA control unit 110 sets a target driving line for the host vehicle SV based on either or both of the white lines recognized by the external sensor device 40 and the driving trajectory (hereinafter referred to as the preceding vehicle trajectory) of a vehicle to be followed by ACC (i.e., a preceding vehicle). The preceding vehicle trajectory may be acquired based on target object information transmitted from the external sensor device 40. The LTA control unit 110 changes the steering angle of the host vehicle SV by controlling the operation of the steering device 21 so that the lateral position of the host vehicle SV (i.e., the position of the host vehicle SV in the vehicle width direction relative to the road) is maintained near the target driving line within the driving lane. Note that the execution condition of the LTA may include, in addition to the LTA activation switch 65 being turned on, the ACC being in operation.

[0024] The sway determination unit 120 determines whether the vehicle SV is in a "swaying state" where the driving behavior is unstable, based on the detection results of the internal sensor device 30 and the external sensor device 40. FIGS. 2B to 2D are schematic diagrams illustrating examples of the vehicle SV's swaying behavior. The sway determination unit 120 acquires the driver's steering operation amount based on the detection result of the steering angle sensor 34. As shown in FIG. 2B, the sway determination unit 120 determines the vehicle SV to be in a swaying state when the lateral behavior of the vehicle SV increases instantaneously, specifically, when the driver turns the steering wheel more than a predetermined threshold operation amount within a predetermined first threshold time and then turns it back. Furthermore, as shown in FIG. 2C, the sway determination unit 120 determines the vehicle SV to be in a swaying state when the vehicle SV travels while repeatedly changing its lateral behavior over a long period of time, specifically, when the driver turns the steering wheel more than a predetermined threshold operation amount within a predetermined second threshold time. The second threshold time is longer than the first threshold time.

[0025] Furthermore, the sway determination unit 120 recognizes the boundary line of the lane in which the vehicle SV is traveling based on the detection results of the external sensor device 40 and counts the number of lane departures, in which at least a portion of the vehicle SV crosses the boundary line. As shown in FIG. 2(D), the sway determination unit 120 determines that the vehicle SV is in a swaying state when the vehicle SV continuously deviates from the lane, specifically, when the number of lane departures exceeds a predetermined threshold number within a predetermined third threshold time. The third threshold time is at least longer than the first threshold time and may be the same as the second threshold time. When the sway determination unit 120 determines that the vehicle SV is in a swaying state, it issues a sway warning via the display device 90 and / or the speaker 95 to urge the driver to take a break, etc. Note that the sway determination unit 120 is not limited to the above example and may also determine the swaying state of the vehicle SV based on, for example, the frequency of LDA execution.

[0026] The hands-off determination unit 130 determines whether the driver is in a "hands-off state" where the driver is not gripping the steering wheel while using the LTA, based on the detection result of the touch sensor 38. The hands-off determination unit 130 determines that the driver is in a hands-off state when the LTA activation switch 65 is in an ON state and a state in which no grip signal is received from the touch sensor 38 continues for a predetermined fourth threshold time. In this case, the hands-off determination unit 130 issues a hands-off warning using the display device 90 and / or the speaker 95. Furthermore, when the LTA activation switch 65 is in an ON state and a state in which no grip signal is received from the touch sensor 38 continues for a predetermined upper threshold time that is longer than the fourth threshold time, the hands-off determination unit 130 forcibly ends (cancels) the currently running LTA.

[0027] The inattention determination unit 140 determines whether the driver is in an inattentive state, that is, not paying attention to the surroundings due to fatigue or the like while driving the vehicle SV. Specifically, the inattention determination unit 140 determines that the driver is in an inattentive state when the sway determination unit 120 determines that the behavior of the vehicle SV is in a swaying state, and / or when the hands-off determination unit 130 determines that the driver is in a hands-off state. When the inattention determination unit 140 determines that the driver is in an inattentive state, it transmits the determination result to the PCS control unit 150 and the steering override control unit 160, respectively.

[0028] The PCS control unit 150 executes PCS control to avoid a collision between the host vehicle SV and a forward target or to mitigate damage from a collision. The PCS control unit 150 acquires coordinate information of an object present ahead of the host vehicle SV based on target information transmitted from the external sensor device 40. The PCS control unit 150 also calculates the turning radius of the host vehicle SV based on the detection results of the vehicle speed sensor 31, the steering angle sensor 34, and the yaw rate sensor 35, and calculates the trajectory of the host vehicle SV based on this turning radius. The PCS control unit 150 determines whether a moving object or a stationary object ahead of the host vehicle SV is an obstacle that may collide with the host vehicle SV. If the object is a moving object, the PCS control unit 150 calculates the trajectory of the moving object based on the coordinate information of the moving object, and determines the moving object as an obstacle if the trajectory of the moving object intersects with the trajectory of the host vehicle SV. If the object is a stationary object, the PCS control unit 150 determines the stationary object as an obstacle if the trajectory of the host vehicle SV intersects with the current position of the stationary object.

[0029] When the PCS control unit 150 determines that an object is an obstacle, it calculates a time to collision (TTC) until the host vehicle SV collides with the obstacle based on the distance L from the host vehicle SV to the obstacle and the relative speed Vr of the host vehicle SV with respect to the obstacle. The TTC is an index value indicating the possibility that the host vehicle SV will collide with the obstacle. The TTC can be calculated by dividing the distance L from the host vehicle SV to the obstacle by the relative speed Vr (TTC = L / vr). If the state in which the TTC is equal to or less than a predetermined collision determination threshold Tv continues for a predetermined first waiting time T1 or more, the PCS control unit 150 determines that there is a high possibility that the host vehicle SV will collide with the obstacle. When it determines that there is a high possibility of a collision, the PCS control unit 150 issues an alarm via the speaker 95 and starts deceleration control. The deceleration control is a control that controls the operation of the braking device 22 to decelerate the vehicle SV so that the deceleration of the vehicle SV matches a predetermined target deceleration. In this way, by setting the condition for executing deceleration control or warning as being that the TTC remains below the collision judgment threshold Tv for more than the first waiting time T1, unnecessary operation of these deceleration controls or warnings can be effectively suppressed.

[0030] Here, when the driver is inattentive, it is desirable to ease the conditions for executing deceleration control or warning, thereby accelerating the activation of deceleration control or warning. When the inattention determination unit 140 determines that the driver is inattentive, the PCS control unit 150 turns on the early activation flag F1 (F1=1). Furthermore, when the early activation flag F1 is turned on, the PCS control unit 150 determines whether to execute deceleration control or warning based on the relaxed threshold time T1' (=T1-Td1), which is obtained by subtracting the predetermined time Td1 from the first standby time T1. As a result, when the driver is inattentive, the deceleration control or warning is activated earlier, making it possible to notify the driver of danger earlier. The predetermined time Td1 that shortens the first standby time T1 may be a fixed value or a variable value. If the predetermined time Td1 is a variable value, for example, the higher the vehicle speed V, the longer the predetermined time Td1 may be.

[0031] The steer override control unit 160 performs steer override control in response to the driver's steering operation. The steer override control prohibits the execution of deceleration control before the start of deceleration control under PCS control, and cancels (forces termination of) deceleration control during the execution of deceleration control under PCS control. There are cases in which the driver recognizes an obstacle and attempts to avoid a collision by operating the steering wheel himself. In such cases, if deceleration control under PCS control is started or the deceleration control currently being executed continues, the vehicle SV will not be able to travel along the trajectory intended by the driver. The steer override control unit 160 performs steer override control to prohibit or cancel the deceleration control under PCS control when the steering angle detected by the steering angle sensor 34 exceeds a predetermined threshold steering angle for a predetermined second waiting time T2 or longer.

[0032] Here, if the driver is inattentive, the reliability of the driver's steering operation is considered to be low. In other words, if the driver is inattentive, even if the steering angle exceeds the threshold steering angle continuously for at least the second waiting time T2, the driver's steering operation may not actually be intended to steer override. When the inattention determination unit 140 determines that the driver is inattentive, the steer override control unit 160 turns on the condition-hardening flag F2 (F2 = 1). Furthermore, when the steer override control unit 160 turns on the condition-hardening flag F2, it determines whether to execute steer override control based on the hardening threshold time T2' (= T2 + Td2), which is obtained by adding a predetermined time Td2 to the second waiting time T2. This prevents unintended deceleration control caused by steer override from being prohibited or released when the driver is inattentive, thereby improving safety. The predetermined time Td2 added to the second waiting time T2 may be a fixed value or a variable value.

[0033] 3A is a flowchart illustrating a routine for driver inattention determination processing by the CPU 11 of the ECU 10. This routine is started, for example, when the vehicle SV starts moving.

[0034] The ECU 10 executes the processes of steps S100 and S110 in parallel. Specifically, in step S100, the ECU 10 determines whether the driving behavior of the vehicle SV is in an unstable, swaying state based on the detection results of the internal sensor device 30 and the external sensor device 40. If the determination result is affirmative (Yes), the ECU 10 proceeds to the process of step S120, and if the determination result is negative (No), the ECU 10 returns from this routine. On the other hand, in step S110, the ECU 10 determines, based on the detection result of the touch sensor 38, whether the driver is in a hands-off state where he or she is not gripping the steering wheel while using the LTA. If the determination result is affirmative (Yes), the ECU 10 proceeds to the process of step S120, and if the determination result is negative (No), the ECU 10 returns from this routine.

[0035] In step S120, the ECU 10 determines that the driver is inattentive, and then returns from this routine.

[0036] Fig. 3(B) is a flowchart illustrating a routine for the early activation process and the difficult condition process by the CPU 11 of the ECU 10. This routine is executed in parallel with the driver inattention determination process routine shown in Fig. 3(A). At the start of this routine, it is assumed that the early activation flag F1 and the difficult condition flag F2 are both set to off (F1=0, F2=0).

[0037] In step S200, the ECU 10 determines whether the driver is determined to be inattentive by the driver inattention determination process shown in Fig. 3(A). If the driver is determined to be inattentive (Yes), the ECU 10 proceeds to the process of step S210. On the other hand, if the driver is not determined to be inattentive (No), the ECU 10 returns from this routine.

[0038] In step S210, the ECU 10 turns on the early activation flag F1 and the difficult condition flag F2 (F1=1, F2=1). Next, in step S220, the ECU 10 determines whether the driver is still determined to be in an inattentive state by the driver inattention determination process shown in FIG. 3A. If the driver is determined to be in an inattentive state (Yes), the ECU 10 returns to the process of step S210. That is, the ECU 10 keeps the early activation flag F1 and the difficult condition flag F2 on. On the other hand, if the driver is not determined to be in an inattentive state (No), the ECU 10 proceeds to the process of step S230, switches the early activation flag F1 and the difficult condition flag F2 off (F1=0, F2=0), and then returns to this routine.

[0039] 4 is a flowchart illustrating a routine for PCS control processing by the CPU 11 of the ECU 10. This routine is started when the vehicle SV starts to move, and is executed in parallel with the processing routines shown in FIGS.

[0040] In step S300, the ECU 10 acquires coordinate information of an object present in the area ahead of the host vehicle SV based on target information transmitted from the external sensor device 40. Next, in step S310, the ECU 10 calculates the trajectory of the host vehicle SV based on the detection results of the vehicle speed sensor 31, the steering angle sensor 34, and the yaw rate sensor 35. Note that the processing of steps S300 and S310 may be performed in any order, or may be performed simultaneously.

[0041] In step S320, the ECU 10 determines whether an object ahead of the host vehicle SV is an obstacle that may collide with the host vehicle SV. If the object is a moving object, the ECU 10 determines the moving object to be an obstacle if the trajectory of the moving object intersects with the trajectory of the host vehicle SV. Also, if the object is a stationary object, the ECU 10 determines the stationary object to be an obstacle if the trajectory of the host vehicle SV intersects with the current position of the stationary object. If the ECU 10 determines that the object ahead of the host vehicle SV is an obstacle (Yes), the ECU 10 proceeds to processing of step S330. On the other hand, if the ECU 10 determines that the object ahead of the host vehicle SV is not an obstacle (No), the ECU 10 returns from this routine.

[0042] In step S330, the ECU 10 calculates the TTC (=L / vr) by dividing the distance L from the host vehicle SV to the obstacle by the relative speed Vr. Next, in step S340, the ECU 10 determines whether the TTC is equal to or less than the collision determination threshold Tv. If the TTC is equal to or less than the collision determination threshold Tv (Yes), the ECU 10 proceeds to the processing of step S350. On the other hand, if the TTC is greater than the collision determination threshold Tv (No), the ECU 10 returns from this routine.

[0043] In step S350, the ECU 10 determines whether the early actuation flag F1 is turned on by the early actuation processing shown in Fig. 3(B). If the early actuation flag F1 is turned on (Yes), the ECU 10 proceeds to the processing of step S360.

[0044] In step S360, the ECU 10 determines whether or not there is a high possibility that the host vehicle SV will collide with an obstacle based on a mitigation threshold time T1' (=T1-Td1) obtained by subtracting a predetermined time Td1 from the first waiting time T1, in order to accelerate the activation of deceleration control and warning. Specifically, the ECU 10 determines whether or not the state in which the TTC is equal to or less than the collision determination threshold Tv continues for the mitigation threshold time T1' or more. If the determination result is negative (No), the ECU 10 returns from this routine. On the other hand, if the determination result is positive (Yes), the ECU 10 proceeds to step S380, executes warning and deceleration control, and returns from this routine.

[0045] If the determination in step S350 is negative (No), that is, if the early activation flag F1 is off (F1=0), the ECU 10 proceeds to processing in step S370. In step S370, the ECU 10 determines whether or not there is a high possibility that the host vehicle SV will collide with an obstacle based on the normal first waiting time T1. Specifically, the ECU 10 determines whether or not the state in which the TTC is equal to or less than the collision determination threshold Tv continues for the first waiting time T1 or more. If the determination result is negative (No), the ECU 10 returns from this routine. On the other hand, if the determination result is positive (Yes), the ECU 10 proceeds to step S380, issues a warning and executes deceleration control, and then returns from this routine.

[0046] 5 is a flowchart illustrating a processing routine for steering override control by the CUP 11 of the ECU 10. This routine is started when it is determined in step S340 of the PCS control routine shown in FIG. 4 that the TTC is equal to or less than the collision determination threshold Tv.

[0047] In step S400, the ECU 10 determines whether the difficult condition flag F2 is set to on (F2=1) by the difficult condition processing shown in Fig. 3(B). If the difficult condition flag F2 is set to on (Yes), the ECU 10 proceeds to the processing of step S410. On the other hand, if the difficult condition flag F2 is not set to on (No), that is, if the difficult condition flag F2 is set to off (F2=0), the ECU 10 proceeds to the processing of step S460.

[0048] When the process proceeds to step S460, the ECU 10 determines whether or not to execute steering override control based on the normal second waiting time T2. Specifically, the ECU 10 determines whether the steering angle detected by the steering angle sensor 34 has exceeded a predetermined threshold steering angle continuously for at least the second waiting time T2. If the determination result is negative (No), the ECU 10 returns from this routine. On the other hand, if the determination result is positive (Yes), the ECU 10 proceeds to step S470.

[0049] If the determination in step S400 is affirmative (Yes), i.e., if the condition-hardening flag F2 is on, the ECU 10 proceeds to processing in step S410, where it determines whether or not to execute steering override control based on a hardening threshold time T2' (=T2+Td2) obtained by adding a predetermined time Td2 to the second waiting time T2, in order to make the steering override execution conditions more difficult. Specifically, it determines whether the steering angle detected by the steering angle sensor 34 has exceeded a predetermined threshold steering angle continuously for at least the hardening threshold time T2'. If the determination result is negative (No), the ECU 10 returns from this routine. In other words, unintended prohibition or release of deceleration control is prevented. On the other hand, if the determination result is affirmative (Yes), the ECU 10 proceeds to processing in step S470.

[0050] In step S470, ECU 10 determines whether warning and / or deceleration control under PCS control is currently being executed. If warning and / or deceleration control is not currently being executed (No), ECU 10 proceeds to processing of step S480, prohibits execution of warning and / or deceleration control under PCS control, and returns from this routine. On the other hand, if warning and / or deceleration control is currently being executed (Yes), ECU 10 proceeds to processing of step S490, cancels warning and / or deceleration control under PCS control, and returns from this routine.

[0051] The above describes the driving assistance device and program according to this embodiment, but the present disclosure is not limited to the above embodiment, and various modifications are possible as long as they do not deviate from the purpose of the present disclosure.

[0052] [Variations] For example, the ECU 10 may calculate a cumulative number Ns of times the vehicle SV is determined to be in a swaying state and / or the number of times the driver is determined to be in a hands-off state, and may determine that the driver is in an inattentive state if the cumulative number Ns reaches a predetermined upper threshold number Nm between the start of the calculation and the lapse of a predetermined first time TM1. Alternatively, the ECU 10 may keep the earlier activation flag F1 and the more difficult condition flag F2 on from the time the driver was determined to be in an inattentive state because the cumulative number Ns has reached the upper threshold number Nm until the lapse of a predetermined second time TM2.

[0053] FIG. 6A is a flowchart illustrating a routine of driver inattention determination processing executed by the ECU 10 (CPU 11) according to a modified example.

[0054] In step S500, the ECU 10 accumulates the number of times the vehicle SV is determined to be in a swaying state and / or the number of times the driver is determined to be in a hands-off state. Next, in step S510, the ECU 10 determines whether the accumulated number Ns has reached the upper threshold number Nm. If the accumulated number Ns has reached the upper threshold number Nm (Yes), the ECU 10 proceeds to processing in step S530. On the other hand, if the accumulated number Ns has not reached the upper threshold number Nm (No), the ECU 10 proceeds to processing in step S570, where it determines whether the elapsed time from the start of accumulation has reached a first time TM1. If the elapsed time has reached the first time TM1 (Yes), the ECU 10 proceeds to processing in step S580, where it resets the accumulated number Ns and returns from this routine. On the other hand, if the elapsed time has not reached the first time TM1 (No), the ECU 10 returns to processing in step S500. The upper threshold number of times Nm and the first time TM1 may be fixed values, or may be variable values ​​depending on the type of road on which the vehicle SV is traveling, traffic conditions, time of day, and the like.

[0055] If the determination in step S510 is affirmative (Yes), that is, if the cumulative number Ns reaches the upper threshold number Nm, the ECU 10 proceeds to the process of step S520, determines that the driver is in an inattentive state, and then returns from this routine.

[0056] 6B is a flowchart illustrating a routine for the modified earlier activation process and the more difficult condition process executed by the CPU 11 of the ECU 10. At the start of this routine, the earlier activation flag F1 and the more difficult condition flag F2 are both set to OFF (F1=0, F2=0).

[0057] In step S600, the ECU 10 determines whether the driver is determined to be inattentive by the driver inattention determination process shown in Fig. 6(A). If the driver is determined to be inattentive (Yes), the ECU 10 proceeds to the process of step S610. On the other hand, if the driver is not determined to be inattentive (No), the ECU 10 returns from this routine.

[0058] In step S610, the ECU 10 turns on the earlier activation flag F1 and the more difficult conditions flag F2 (F1=1, F2=1). Next, in step S620, it is determined whether the elapsed time since the earlier activation flag F1 and the more difficult conditions flag F2 were turned on has reached a second time TM2. If the elapsed time has reached the second time TM2 (Yes), the ECU 10 proceeds to processing in step S630, turns off the earlier activation flag F1 and the more difficult conditions flag F2 (F1=0, F2=0), and returns from this routine. On the other hand, if the elapsed time has not reached the second time TM2 (No), the ECU 10 returns to processing in step S620. The second time TM2 may be a fixed value or may be a variable value depending on the type of road on which the vehicle SV is traveling, traffic conditions, time of day, etc.

Claims

1. A driving assistance device for a vehicle, The driving assistance device includes a target recognition unit that recognizes targets present around the vehicle, and a processor; the processor is configured to: a first control unit that, when a first condition that there is a possibility that the host vehicle will collide with a target recognized by the target recognition unit is satisfied, executes a first control to avoid a collision between the target and the host vehicle or to reduce damage caused by the collision; a second control unit that, when a second condition that a steering operation by a driver of the host vehicle is in a predetermined operating state is satisfied, executes a second control that prohibits execution of the first control if the first control has not yet been executed, and cancels the first control if the first control is being executed; and a condition change unit that determines whether the steering operation state of the driver or the behavior of the host vehicle due to the steering operation by the driver is in a specific state that is inappropriate for a road on which the host vehicle is traveling, and, when it is determined that the specific state is satisfied, changes a determination condition for determining whether the second condition is satisfied so that the second condition is less likely to be satisfied than when it is determined that the specific state is not satisfied.

2. The driving assistance device according to claim 1, The condition change unit accumulates the number of times that the specific state is determined to be in, and when the accumulated number reaches a predetermined upper limit number within a predetermined first time period, changes the judgment condition so that the second condition becomes less likely to be met from the time the upper limit number is reached until a predetermined second time period has elapsed.

3. The driving assistance device according to claim 1 or 2, The condition change unit is a driving assistance device that determines whether or not the specific state is in place based on a change in the lateral behavior of the vehicle, or a deviation of the vehicle from the lane in which the vehicle is traveling, or a state in which the driver is gripping the steering wheel while lane keeping control is being executed to keep the vehicle in the lane in which the vehicle is traveling.

4. The driving assistance device according to claim 1, When the condition change unit determines that the vehicle is in the specific state, the condition change unit relaxes the judgment conditions for determining whether the first condition is met so that the first condition is more likely to be met than when the vehicle is determined not to be in the specific state.

5. A processor of a driving assistance device for a vehicle including a target recognition unit that recognizes targets present around the vehicle, a first control process that, when a first condition that there is a possibility that the host vehicle will collide with a target recognized by the target recognition unit is satisfied, executes a first control to avoid a collision between the target and the host vehicle or to reduce damage caused by the collision; a second control process that, when a second condition that the steering operation by the driver of the host vehicle is in a predetermined operating state is satisfied, executes a second control that prohibits execution of the first control if the first control is not yet executed and cancels the first control if the first control is being executed, even if the first condition is satisfied; and a condition change process that determines whether the steering operation state of the driver or the behavior of the host vehicle due to the steering operation by the driver is in a specific state that is inappropriate for the road on which the host vehicle is traveling, and, when it is determined that the specific state is satisfied, changes the determination condition for determining whether the second condition is satisfied so that the second condition is less likely to be satisfied than when it is determined that the specific state is not satisfied.

Images