Driving assistance devices

Abstract

The driving assistance device includes: an automatic braking unit, which is configured to perform automatic braking control; a stop and hold unit, which is configured to perform stop and hold control to keep the own vehicle in a stopped state; a stop and hold release unit, which is configured to release the stop and hold control when it is determined that a predetermined release condition is met; a surrounding information acquisition unit, which is configured to acquire surrounding information, which is information indicating the conditions around the own vehicle; an operation information acquisition unit, which is configured to acquire operation information about the driver's driving operation; an operation determination unit, which is configured to determine whether the driving operation is appropriate with respect to the surrounding conditions based on the surrounding information and the operation information; and a prohibition unit, which is configured to prohibit the release of the stop and hold control when it is determined that the driving operation is inappropriate.

Description

[0001] This application is a divisional application of the Chinese patent application with an application date of August 3, 2020, application number 202010768055.2, and invention name “Driving Assistance Device”. Technical Field

[0002] The present invention relates to a driving assistance device for stopping a vehicle by automatic braking and maintaining the stopped vehicle in a stopped state. Background Art

[0003] Technologies for forcibly stopping a vehicle using automatic braking are known. For example, conventional collision avoidance assistance systems, when a front sensor such as a camera or radar sensor detects an obstacle with a high probability of collision with the vehicle, increase the hydraulic oil pressure supplied to the brake system (brake oil pressure), activating the automatic brakes to stop the vehicle. After stopping the vehicle using the automatic brake, such assistance systems also maintain the vehicle in a stopped state by executing stop-hold control to maintain the brake oil pressure at a high level for a predetermined period of time (e.g., two seconds).

[0004] Furthermore, the assist device proposed in Japanese Patent Application Laid-Open No. 2019-84984 (referred to as a related art device) cancels (ends) stop-and-hold control at the time the driver's operation (e.g., accelerator pedal operation, brake pedal operation, etc.) is detected, if it is determined that the vehicle is to be kept stopped for a period exceeding a predetermined time from the time the vehicle is stopped by the automatic brake. For example, in situations such as when the vehicle is stopped immediately before an intersection or when the vehicle detects a vehicle crossing its direction of travel and stops, it is determined that the vehicle is to be kept stopped for a period exceeding a predetermined time, and the stop-and-hold control is canceled at the time the driver's operation is detected. Summary of the Invention

[0005] However, the related art device only releases the stop and hold control based on the detection of the driver's operation. Therefore, there is a possibility that the driver's erroneous pedal operation is detected and the stop and hold control is released. In this case, even if the stopped state should be maintained, it will not be maintained.

[0006] When the automatic brake is engaged, the driver may become distracted and fail to perform appropriate driving operations. For example, the driver may mistakenly press the accelerator pedal instead of the brake pedal. In this case, the accelerator pedal operation may release the stop-and-hold control, causing the vehicle to accelerate rapidly in response to the accelerator pedal operation.

[0007] Furthermore, when the related art device detects a driver's operation and releases stop-and-hold control, it does so without considering the surrounding conditions of the vehicle. Therefore, if the driver releases stop-and-hold control due to an incorrect pedal operation, the vehicle could collide with an obstacle or start in violation of regulations.

[0008] The present invention provides a technique for canceling stop and hold control when it is estimated that the vehicle itself is safe even if the stop and hold control is canceled.

[0009] A technical solution of the present invention relates to a driving assistance device. The driving assistance device comprises: an automatic braking unit configured to execute automatic braking control when it is determined that a predetermined automatic stop condition is satisfied, wherein the automatic braking control is a control for automatically stopping the own vehicle by providing a braking force to the own vehicle; a stop holding unit configured to execute stop holding control so that the own vehicle in a state stopped by the automatic braking unit neither moves forward nor moves backward, wherein the stop holding control is a control for continuously stopping the own vehicle by providing a braking force to the own vehicle; and a stop holding release unit configured to release the stop holding control when it is determined that a predetermined release condition is satisfied, when the stop holding control is executed by the stop holding unit. a surrounding information acquisition unit configured to acquire surrounding information, the surrounding information being information indicating conditions surrounding the own vehicle; an operation information acquisition unit configured to acquire operation information, the operation information being information regarding a driving operation of a driver of the own vehicle; an operation determination unit configured to determine, based on the acquired surrounding information and the acquired operation information, whether the driving operation when executing the stop and hold control is appropriate with respect to the surrounding conditions; and a prohibition unit configured to prohibit the stop and hold release unit from causing the stop and hold unit to release the stop and hold control if the operation determination unit determines that the driving operation is inappropriate, even when the release condition is satisfied.

[0010] The driving assistance device of the above technical solution includes an automatic braking unit, a stop holding unit, and a stop holding release unit. The automatic braking unit applies braking force to the vehicle to automatically stop the vehicle when it determines that a predetermined automatic stop condition has been met. For example, if the automatic braking unit detects an obstacle with a high probability of collision with the vehicle, it applies the brakes (generates braking force) to stop the vehicle without the driver having to operate the brake pedal.

[0011] The stop-holding unit executes stop-hold control, which applies braking force to the vehicle so that the vehicle, which has been stopped by the automatic braking unit, neither moves forward nor moves backward, thereby maintaining the vehicle's stop. This maintains the vehicle in a stopped state. The stop-hold release unit releases the stop-hold control when it determines that a predetermined release condition has been met while the stop-hold control is in effect. Hereinafter, "release of the stop-hold control" may also be referred to as "release of the stop-hold."

[0012] The release of the vehicle's stop hold must be performed safely. To this end, the present invention includes a surrounding information acquisition unit, an operation information acquisition unit, an operation determination unit, and a prohibition unit. The surrounding information acquisition unit acquires surrounding information, which is information indicating the conditions surrounding the vehicle. For example, the surrounding information acquisition unit acquires information regarding obstacles surrounding the vehicle. Alternatively, the surrounding information acquisition unit may acquire information indicating the contents of traffic infrastructure equipment such as traffic lights located around the vehicle.

[0013] The operation information acquisition unit acquires operation information related to the driving operation of the driver of the own vehicle. For example, the operation information acquisition unit acquires information related to the driver's pedal operation (accelerator pedal operation information and brake pedal operation information).

[0014] The operation determination unit determines whether the driving operation when the stop and hold control is executed is appropriate with respect to the surrounding conditions based on the acquired surrounding information and the acquired operation information.

[0015] For example, if stop-and-hold control is released, the driver's driving operation that may cause the vehicle to approach an obstacle or the driver's driving operation that may cause the vehicle to violate regulations is determined to be inappropriate for the surrounding conditions as a driving operation when stop-and-hold control is executed.

[0016] Even when the cancellation condition is satisfied, the prohibiting unit prohibits the stop and hold cancellation unit from causing the stop and hold unit to cancel the stop and hold control if the operation determination unit determines that the driving operation is inappropriate.

[0017] Therefore, according to the present invention, it is possible to release the stop hold of the own vehicle in a safe situation even if the stop hold is released. Thus, it is possible to suppress the driver's unintentional start of the own vehicle. In addition, it is possible to suppress collision with an obstacle accompanying the release of the stop hold.

[0018] In the driving assistance device of the above technical solution, the stop and hold release unit can also be configured to determine that the release condition is met when the stop and hold time is greater than a predetermined release threshold time and the accelerator pedal is not operated, and the stop and hold time is the time for continuously executing the stop and hold control.

[0019] When the automatic brake is in operation, it is believed that a certain degree of time is required before the driver can calmly make a judgment and perform the operation. Therefore, the stopped state of the own vehicle should be maintained for a certain degree of time. Therefore, in one technical solution of the present invention, when the stop hold time, which is the time for continuously executing the stop hold control, is longer than a predetermined release threshold time and the accelerator pedal is not operated, it is determined that the release condition is met. In this case, when the stop hold time becomes longer than the predetermined release threshold time, if the operation determination unit determines that the driving operation is appropriate with respect to the surrounding conditions, the stop hold control is released at that time point, but if the operation determination unit determines that the driving operation is inappropriate with respect to the surrounding conditions, the stop hold control is not released and the stop hold control is continued. Therefore, according to the above technical solution, the stop hold of the own vehicle can be released in a safe manner even if the stop hold of the own vehicle is released.

[0020] In the driving assistance device of the above technical solution, the stop and hold release unit can also be configured to determine whether a specific operation that can be inferred to be an operation based on the driver's intention has been performed during the execution of the stop and hold control. If it is determined that the specific operation has been performed, even if the stop and hold time is less than the release threshold time, it is determined that the release condition is met.

[0021] There are also situations where the driver performs a driving operation based on their own intentions within a short period of time after the automatic brake is activated and the vehicle stops. In this case, it is desirable to release the stop hold of the vehicle even before the stop hold time reaches the release threshold time. Therefore, in one technical solution of the present invention, a stop hold release unit determines whether a specific operation that can be inferred to be an operation based on the driver's intention has been performed during the execution of the stop hold control. If it is determined that the specific operation has been performed, the release condition is determined to be met even if the stop hold time is less than the release threshold time. However, even in this case, if the operation determination unit determines that the driving operation is appropriate relative to the surrounding conditions when the specific operation is determined to have been performed, the stop hold control is released. If the operation determination unit determines that the driving operation is inappropriate relative to the surrounding conditions, the stop hold control is not released and continues.

[0022] Therefore, according to one aspect of the present invention, the stop holding of the own vehicle can be released at an appropriate timing, thereby allowing the driver to start the own vehicle before the stop holding time reaches the release threshold time.

[0023] In the driving assistance device of the above aspect, the specific operation may be a re-depression operation of the accelerator pedal performed during execution of the stop hold control.

[0024] In other words, the accelerator pedal may be depressed, the foot may be released from the accelerator pedal, and then the accelerator pedal may be depressed again. The accelerator pedal depression operation can be inferred as a driving operation based on the driver's intention. Therefore, if the accelerator pedal depression operation is detected and the operation is appropriate given the surrounding conditions, the vehicle's stop hold is released.

[0025] In the driving assistance device of the above technical solution, the specific operation may be a brake pedal operation performed while the accelerator pedal operation amount is zero during the execution of the stop and hold control. A brake pedal operation performed without depressing the accelerator pedal while automatic braking control is in effect can be inferred as a driving operation based on the driver's intention. This driving operation does not cause the vehicle to start and is therefore appropriate given the surrounding conditions. Therefore, the stop and hold control of the vehicle can be released at the timing of detecting this brake pedal operation.

[0026] In the driving assistance device of the above technical solution, the operation judgment unit can also be configured as follows: during the execution of the stop and hold control, if it is determined based on the acquired surrounding information that there is an obstacle that may collide with the own vehicle, and if it is determined based on the acquired operation information that the accelerator pedal is operated, the driving operation is determined to be inappropriate.

[0027] Thus, even if the driver mistakenly operates the accelerator pedal, the stop hold of the own vehicle is not cancelled, and thus a collision between the own vehicle and an obstacle can be suppressed.

[0028] In the driving assistance device of the above technical solution, the operation judgment unit can also be configured as follows: during the execution of the stop and hold control, if it is determined based on the acquired surrounding information that there is an obstacle that may collide with the own vehicle, and if it is determined based on the acquired operation information that the brake pedal is not operated, the driving operation is judged to be inappropriate.

[0029] If the hold function is released without the brake pedal being operated, the vehicle may start moving due to creeping. In one embodiment of the present invention, if there is an obstacle with the potential for collision with the vehicle, the hold function is not released without the brake pedal being operated. This prevents collisions between the vehicle and the obstacle caused by creeping.

[0030] In the driving assistance device of the above technical solution, the operation judgment unit can also be configured as follows: during the execution of the stop and hold control, if it is determined based on the acquired surrounding information that a situation has occurred in which the starting of the own vehicle is prohibited by law, and if it is determined based on the acquired operation information that the accelerator pedal has been operated, the driving operation is determined to be inappropriate.

[0031] For example, if your own vehicle is stopped before an intersection and the traffic light at the intersection turns red, you are prohibited from entering the intersection. In one aspect of the present invention, even if the driver operates the accelerator pedal in a manner inconsistent with their intention, the vehicle's stopped position is not released. This ensures compliance with regulations and prevents collisions with other vehicles, pedestrians, and the like.

[0032] In the driving assistance device of the above technical solution, the operation judgment unit can also be configured as follows: during the execution of the stop and hold control, if it is determined based on the acquired surrounding information that a situation has occurred in which the starting of the own vehicle is prohibited by law, and if it is determined based on the acquired operation information that the brake pedal has not been operated, the driving operation is judged to be inappropriate.

[0033] In one embodiment of the present invention, if the driver does not operate the brake pedal and a situation occurs where starting the vehicle is prohibited by law, the vehicle's stop hold is not released. This ensures compliance with laws and regulations. Furthermore, collisions with other vehicles, pedestrians, and the like can be prevented.

[0034] In the driving assistance device of the above technical solution, the operation determination unit may also be configured to determine whether the driver is sitting in the driver's seat during the execution of the stop and hold control, and determine that the driving operation is inappropriate if it is determined that the driver is not sitting in the driver's seat. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals represent like elements, and wherein:

[0036] Figure 1It is a schematic diagram of the configuration of a driving assistance device according to an embodiment of the present invention.

[0037] Figure 2 Flowchart showing the stop hold release control routine.

[0038] Figure 3 This is a timing diagram related to the embodiment.

[0039] Figure 4 This is a timing diagram related to the embodiment.

[0040] Figure 5 This is a timing chart related to a comparative example.

[0041] Figure 6 This is a flowchart showing a modified example of the stop hold release control routine. DETAILED DESCRIPTION

[0042] Hereinafter, a driving assistance device according to an embodiment of the present invention will be described with reference to the drawings.

[0043] The driving assistance device according to the embodiment of the present invention is applied to a vehicle (hereinafter referred to as "own vehicle" to distinguish it from other vehicles). Figure 1 As shown, a driving support ECU 10 , a brake ECU 20 , an engine ECU 30 , a meter ECU 40 , an external communication ECU 50 , and a navigation ECU 60 are provided.

[0044] These ECUs are electronic control units (ECUs) with microcomputers as their main components. They are connected via a CAN (Controller Area Network) (not shown) so that they can send and receive information to and from each other. In this specification, a microcomputer includes a CPU (central processing unit), ROM (read-only memory), RAM (random access memory), non-volatile memory, and interface I / F. The CPU performs various functions by executing instructions (programs, routines) stored in ROM. Some or all of these ECUs can also be combined into a single ECU.

[0045] The driving assistance ECU 10 is a central control unit that provides driver assistance and implements collision avoidance assistance control. This collision avoidance assistance control alerts the driver when an obstacle is detected in front of the vehicle. If the likelihood of a collision increases, the vehicle automatically applies the brakes to avoid a collision between the vehicle and the obstacle. This collision avoidance assistance control is generally referred to as PCS control (pre-crash safety control). Therefore, it will be referred to as PCS control below.

[0046] The driving assistance ECU 10 is connected to a front camera sensor 70 , a front radar sensor 75 , a rear side radar sensor 80 , a vehicle state sensor 90 , an operation state sensor 95 , and a buzzer 100 .

[0047] The front camera sensor 70 is located above the front window in the vehicle's interior and captures the scenery in front of the vehicle. Based on the captured images, the front camera sensor 70 identifies the white lines on the road and any three-dimensional objects in front of the vehicle, and periodically supplies this information (white line information and three-dimensional object information) to the driving assistance ECU 10. The white line information indicates the shape of the white lines and the relative position of the vehicle to the white lines. The three-dimensional object information indicates the type, size, and relative position of any three-dimensional object detected in front of the vehicle.

[0048] The front camera sensor 70 also recognizes the content displayed by traffic infrastructure devices, such as traffic lights and road signs, that regulate vehicle movement. The front camera sensor 70 also periodically supplies information indicating the content displayed by the traffic infrastructure devices (referred to as traffic infrastructure information) to the driving assistance ECU 10. Furthermore, recognition of the type of three-dimensional objects and the content displayed by the traffic infrastructure devices is achieved, for example, through machine learning.

[0049] The front radar sensor 75 is set in the front center of the vehicle body and detects three-dimensional objects in the area in front of the vehicle. The front radar sensor 75 transmits radio waves in the millimeter wave band (hereinafter referred to as "millimeter waves") and receives millimeter waves (i.e., reflected waves) reflected by three-dimensional objects (such as other vehicles, pedestrians, bicycles, buildings, etc.) within the transmission range. The front radar sensor 75 calculates the distance between the vehicle and the three-dimensional object, the relative speed between the vehicle and the three-dimensional object, the relative position (direction) of the three-dimensional object relative to the vehicle based on the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation level of the reflected wave, and the time from transmitting the millimeter wave to receiving the reflected wave, and supplies information representing the calculation results (three-dimensional object information) to the driving assistance ECU 10 at a predetermined period.

[0050] The driving support ECU 10 synthesizes the three-dimensional object information supplied from the front camera sensor 70 and the three-dimensional object information supplied from the front radar sensor 75 to obtain highly accurate three-dimensional object information.

[0051] Hereinafter, the front camera sensor 70 and the front radar sensor 75 are collectively referred to as front sensors, and information in front of the own vehicle obtained from the front camera sensor 70 and the front radar sensor 75 is referred to as front sensor information.

[0052] The rear radar sensor 80 consists of a left rear radar sensor 80L and a right rear radar sensor 80R. The left rear radar sensor 80L is located at the left rear corner of the vehicle, while the right rear radar sensor 80R is located at the right rear corner of the vehicle. The left rear radar sensor 80L has its radar axis facing obliquely rearward to the left, detecting three-dimensional objects in the area behind it. The right rear radar sensor 80R has its radar axis facing obliquely rearward to the right, detecting three-dimensional objects in the area behind it. The three-dimensional object detection method used by the rear radar sensor 80 is the same as that used by the front radar sensor 75.

[0053] The rear side radar sensor 80 supplies 3D object information related to detected 3D objects to the driving assistance ECU 10 at a predetermined interval. Hereinafter, the information about the left and right diagonally rearward directions of the vehicle obtained by the rear side radar sensor 80 is referred to as rear sensor information. Furthermore, information obtained using the front camera sensor 70, the front radar sensor 75, and the rear side radar sensor 80 indicates the conditions surrounding the vehicle and is also referred to as surrounding information.

[0054] The vehicle state sensor 90 includes, for example, a vehicle speed sensor for detecting the vehicle's running speed, a longitudinal acceleration sensor for detecting the vehicle's longitudinal acceleration, a lateral acceleration sensor for detecting the vehicle's lateral acceleration, and a yaw rate sensor for detecting the vehicle's yaw rate.

[0055] The operating state sensor 95 is a sensor or switch that detects the driver's operations (driving operations). The operating state sensor 95 includes an accelerator operation amount sensor that detects the amount of accelerator pedal operation, a brake operation amount sensor that detects the amount of brake pedal operation, a brake switch that detects whether the brake pedal is operated, a steering angle sensor that detects the steering angle, a steering torque sensor that detects the steering torque, and a gear position sensor that detects the gear position of the transmission. Information acquired using the operating state sensor 95 is information about the driver's driving operations of the vehicle, also known as operating information.

[0056] Information detected by the vehicle state sensor 90 and the operation state sensor 95 (referred to as sensor information) is supplied to the driving support ECU 10 via a CAN (not shown) at a predetermined cycle.

[0057] The buzzer 100 sounds in accordance with an instruction from the driving support ECU 10. When the driving support ECU 10 needs to call the driver's attention, it sends a sounding instruction to the buzzer 100 to sound the buzzer 100. This can call the driver's attention.

[0058] The brake ECU 20 is connected to a brake actuator (brake Act) 21. The brake actuator 21 is provided in a hydraulic circuit between a master cylinder (not shown) that pressurizes the working oil according to the pedal force of the brake pedal and a friction brake mechanism 22 provided on the left and right front and rear wheels. The friction brake mechanism 22 includes a brake disc 22a fixed to the wheel and a brake caliper 22b fixed to the vehicle body. The brake actuator 21 adjusts the oil pressure supplied to the wheel brake pump built into the brake caliper 22b according to instructions from the brake ECU 20. This oil pressure activates the wheel brake pump, thereby pressing the brake pads against the brake disc 22a, generating friction braking force. The brake ECU 20 sets the driver's required deceleration based on the brake pedal operation amount detected by the brake operation amount sensor, and controls the operation of the brake actuator 21 so that the vehicle decelerates at the driver's required deceleration. Furthermore, upon receiving the PCS brake command transmitted from the driving support ECU 10 , the brake ECU 20 controls the operation of the brake actuator 21 so that the vehicle decelerates at the PCS required deceleration rate included in the PCS brake command.

[0059] The engine ECU 30 is connected to the engine actuator (engine Act) 31. The engine actuator 31 is an actuator for changing the operating state of the engine 32 (internal combustion engine), for example, including a throttle actuator that changes the opening of the throttle valve. The engine ECU 30 sets the driver's required torque based on the accelerator pedal operation amount detected by the accelerator operation amount sensor and the vehicle speed detected by the vehicle speed sensor, and controls the operation of the engine actuator 31 so that the engine 32 outputs the driver's required torque. In addition, when the engine ECU 30 receives an output limitation instruction sent from the driving assistance ECU 10, it controls the operation of the engine actuator 31 so as to limit the output torque generated by the engine 32. In addition, when the vehicle is an electric vehicle, the engine actuator 31 is a drive device for the electric motor, and when the vehicle is a hybrid vehicle, the engine actuator 31 is a drive device for the above-mentioned engine actuator and the electric motor.

[0060] The meter ECU 40 is connected to a display 41 and a parking lamp 42. The meter ECU 40 can display driving assistance-related information on the display 41 in accordance with instructions from the driving assistance ECU 10. Furthermore, the meter ECU 40 can illuminate the parking lamp 42 in accordance with instructions from the driving assistance ECU 10 or the brake ECU 20.

[0061] The external communication ECU 50 is connected to a wireless communication device 51. The wireless communication device 51 receives traffic infrastructure information transmitted from roadside equipment, etc. The wireless communication device 51 supplies the received traffic infrastructure information to the external communication ECU 50. Upon receiving a request to obtain traffic infrastructure information from the driving assistance ECU 10, the external communication ECU 50 supplies the traffic infrastructure information received by the wireless communication device 51 to the driving assistance ECU 10.

[0062] Traffic infrastructure information includes intersection information and road information. Intersection information includes traffic light information for intersections equipped with roadside equipment, vehicle detection information regarding vehicles detected near the intersection (e.g., within a predetermined distance from the center of the intersection), pedestrian detection information regarding pedestrians detected near the intersection, and intersection map information showing the shape of the intersection's roads and the shapes of the roads connecting to it. Traffic light information includes information that can be used to determine the period during which a traffic light is red (or blue) based on the lighting cycle and lighting time of the blue, yellow, and red signals. Traffic infrastructure information is also included in the aforementioned surrounding information.

[0063] The navigation ECU 60 is connected to a GPS receiver 61 that receives GPS signals for detecting the current position of the vehicle, a map database (map DB) 62 that stores map information, and a human-machine interface 63 (HMI 63) using a touch-panel display. The navigation ECU 60 determines the current position of the vehicle based on the GPS signals, performs various calculations based on the vehicle's position and map information stored in the map DB 62, and provides route guidance using the HMI 63.

[0064] PCS Control

[0065] Next, the PCS control performed by the automatic brake will be described. Focusing on its functions, the driving support ECU 10 includes a collision determination unit 11 , a notification unit 12 , an automatic braking unit 13 , a stop hold unit 14 , a stop hold release unit 15 , an operation determination unit 16 , and a prohibition unit 17 .

[0066] The collision determination unit 11 determines whether the vehicle will collide with a three-dimensional object ahead based on the forward sensor information supplied by the forward sensor and the vehicle state detected by the vehicle state sensor 90. For example, the collision determination unit 11 determines whether the vehicle will collide with the three-dimensional object if the three-dimensional object maintains its current moving state (or, if the three-dimensional object is stationary, stops) and the vehicle maintains its current driving state. If the collision determination unit 11 determines that the vehicle will collide with the three-dimensional object based on the determination result, the vehicle identifies the three-dimensional object as an obstacle.

[0067] When the collision determination unit 11 detects an obstacle, it calculates a predicted time to collision (TTC), which is the predicted time until the vehicle collides with the obstacle. This TTC is calculated using the following equation (1) based on the distance d between the obstacle and the vehicle and the relative speed Vr of the vehicle relative to the obstacle.

[0068] TTC=d / Vr···(1)

[0069] The collision prediction time TTC is used as an index indicating the probability of the host vehicle colliding with an obstacle. The smaller the value, the higher the probability (danger) of the host vehicle colliding with the obstacle.

[0070] In the PCS control of this embodiment, the probability of a collision between the vehicle and an obstacle is divided into two levels based on the predicted collision time TTC. In the initial first level, the notification unit 12 warns the driver using the buzzer 100 and the display 41. In the second level, which is higher than the first level, the automatic braking unit 13 applies brake control (automatic braking control) to assist in avoiding a collision.

[0071] In this case, the collision determination unit 11 determines that the level of the possibility of a collision between the host vehicle and the obstacle has reached level 1 when the collision prediction time TTC decreases below the warning threshold value TTCw. When the collision prediction time TTC further decreases and becomes below the action threshold value TTCa (<TTCw), the collision determination unit 11 determines that the level of the possibility of a collision between the host vehicle and the obstacle has reached level 2. In this example, when the level of the possibility of a collision between the host vehicle and the obstacle reaches level 2, it is determined that the pre-set automatic stop condition has been met.

[0072] When the automatic braking unit 13 determines that the level of possibility of the collision between the vehicle and the obstacle has reached level 2, it transmits a PCS braking command to the brake ECU 20. The PCS braking command includes information indicating the PCS required deceleration Gpcs.

[0073] The PCS required deceleration Gpcs can be calculated as follows. For example, in the case of a vehicle that has stopped at an obstacle, the vehicle's current speed (relative speed) is V, the vehicle's deceleration is a (<0), and the time until the vehicle stops is t. The distance X traveled until the vehicle stops can be expressed as follows: Equation (2).

[0074] X=V·t+(1 / 2)·a·t 2 ···(2)

[0075] In addition, the time t until the vehicle stops can be expressed by the following equation (3).

[0076] t=-V / a···(3)

[0077] Therefore, by introducing equation (3) into equation (2), the travel distance X until the vehicle stops can be expressed by the following equation (4).

[0078] X=-V 2 / 2a···(4)

[0079] To stop the vehicle at a distance β from an obstacle, set the travel distance X to the distance d detected by the front sensor minus the distance β (d - β), and calculate the deceleration a. Alternatively, when traveling around an obstacle, the relative speed and deceleration relative to the obstacle can be used for calculation.

[0080] The deceleration a calculated in this manner can be applied to the PCS requested deceleration Gpcs. Furthermore, an upper limit Gmax is set for the PCS requested deceleration Gpcs. When the calculated PCS requested deceleration Gpcs exceeds the upper limit Gmax, the PCS requested deceleration Gpcs is set to the upper limit Gmax.

[0081] Upon receiving the PCS brake command, the brake ECU 20 controls the brake actuator 21 to achieve the PCS requested deceleration Gpcs. This generates friction braking force on the left and right front and rear wheels, forcibly stopping the vehicle, without the driver having to operate the brake pedal. Once the vehicle is stopped, the stop-maintaining unit 14 replaces the automatic braking unit 13 to control the brake ECU 20. This constitutes automatic braking control.

[0082] When the stop-hold unit 14 confirms that the vehicle has stopped due to the automatic brake, it sends a stop-hold command to the brake ECU 20 to maintain the vehicle in a stopped state (the vehicle is neither moving forward nor backward). Upon receiving the stop-hold command, the brake ECU 20 controls the brake actuator 21 to supply the oil pressure set for stop-holding to the wheel brake pumps of the friction brake mechanisms 22 of the left and right front and rear wheels. The vehicle's stopped state is thereby maintained. Hereinafter, maintaining the vehicle's stopped state may also be referred to as stop-hold. Control to maintain the vehicle's stopped state is also referred to as stop-hold control.

[0083] Furthermore, during the execution of automatic braking control and stop-and-hold control, the driving assistance ECU 10 sends an output limiting instruction to the engine ECU 30 to limit the engine output torque (e.g., to zero). Furthermore, during the execution of automatic braking control and stop-and-hold control, the brake ECU 20 sends a lighting instruction to the meter ECU 40 to turn on the parking lamp 42.

[0084] The stop hold release unit 15 determines whether a pre-set release condition, described in detail later, has been met. If the release condition is met, it sends a stop hold release command to the brake ECU 20. The brake ECU 20 then terminates the previously performed control of the brake actuator 21 for the stop hold. Consequently, the vehicle's stop hold is released (i.e., the stop hold control is released), and PCS control ends. Furthermore, the stop hold release unit 15 sends an output restriction release command to the engine ECU 30. This returns the vehicle to its normal state, enabling acceleration and deceleration in response to accelerator and brake pedal operation.

[0085] Stop holding release control

[0086] The cancellation of the stop hold of the own vehicle (cancellation of the stop hold control) needs to be performed only under conditions that ensure safety. For example, in the past, the following device has been known: the stop hold is cancelled (the stop hold control is ended) at a time point after the stop hold (stop hold control) of the own vehicle has continued for a predetermined time. In this previous device, when the stop hold is cancelled in the presence of an obstacle in front of the own vehicle and the driver does not step on the brake pedal at that time, the own vehicle will start due to the creep phenomenon. As a result, there is a possibility that the own vehicle will collide with the obstacle or get abnormally close to it. In addition, if the driver becomes unsure about the operation of the automatic brake and continues to step on the accelerator pedal when he should step on the brake pedal, there is a possibility that the own vehicle will accelerate rapidly as the stop hold is cancelled.

[0087] Furthermore, a device is also conceivable that, when it is determined that it is desired to maintain the vehicle in a stopped state even after a predetermined time has passed since the vehicle was stopped by automatic braking control (continuation of stop-and-hold control), continues stop-and-hold control and then releases the vehicle's stop-and-hold control (termination of stop-and-hold control) when a driver's driving operation is detected. However, with this device, the vehicle's stop-and-hold control may be released due to an erroneous driver operation, such as a misstep on a pedal. In this case, stop-and-hold control is not maintained even when it should be.

[0088] Therefore, in this embodiment, when the release condition has been met (i.e., when the stop and hold is released), based on information about the driver's driving operation (operation information) and information indicating the conditions around the own vehicle (surrounding information), it is determined whether the driver's driving operation during the execution of the stop and hold control is appropriate relative to the conditions around the own vehicle.

[0089] This determination includes not only determining whether the driver's driving operation is appropriate relative to the surrounding conditions, but also determining whether the driver has performed appropriate driving operations relative to the surrounding conditions. In other words, if the driver does not perform appropriate driving operations relative to the surrounding conditions, the driver's driving operation can be determined to be inappropriate. Hereinafter, the driver's driving operation will be referred to as simply the driver's operation.

[0090] Inappropriate driver operations include operations by a driver who may cause the vehicle to approach an obstacle when stop hold is released, and operations by a driver who may cause the vehicle to violate regulations.

[0091] The operation determination unit 16 determines whether the driver's operation is appropriate with respect to the surrounding conditions when the vehicle is maintained in a stopped state by the stop hold control based on the surrounding information and the operation information.

[0092] The prohibition unit 17 prohibits the stop holding release unit 15 from causing the stop holding unit 14 to release the stop holding control when the operation determination unit 16 determines that the driver's operation while the vehicle is kept stopped is inappropriate with respect to the surrounding conditions.

[0093] The following describes an example in which the operation determination unit 16 determines that the driver's operation is inappropriate with respect to the surrounding situation. In a conventional device, in such an example, the stop and hold control may be canceled.

[0094] The brake pedal is not operated when an obstacle is detected in front of (directly in front of) the vehicle.

[0095] The accelerator pedal was operated while an obstacle was detected in front of the vehicle.

[0096] When the steering wheel and accelerator pedal are operated, an obstacle is detected in the estimated direction of travel of the own vehicle.

[0097] The accelerator pedal is operated when a moving object (another vehicle, pedestrian, bicycle, etc.) is predicted to cross in front of the vehicle in the left or right direction.

[0098] The accelerator pedal is operated while a moving object (another vehicle, pedestrian, bicycle, etc.) is predicted to cut in from the rear or side of the vehicle.

[0099] The accelerator pedal is operated while the traffic light in front of the vehicle is red.

[0100] The accelerator pedal was depressed before the automatic brake was applied, and the accelerator pedal remained depressed without being depressed again.

[0101] The stop hold release unit 15 determines that the release condition is met when any of the following conditions is met.

[0102] Release condition 1: The time during which the stop hold control is continuously executed from the time when the own vehicle is stopped by the automatic braking control (hereinafter sometimes referred to as "holding time") is longer than a set time, and the accelerator pedal is not operated.

[0103] Release condition 2: While the stop and hold control is being continuously executed (during the stop and hold), a specific operation that can be estimated to be an operation based on the driver's intention is performed.

[0104] The specific operation in the release condition 2 is an accelerator pedal re-depression operation performed during the stop and hold and / or a brake pedal operation performed while the accelerator pedal is not operated during the stop and hold.

[0105] Furthermore, with regard to brake pedal, accelerator pedal, and steering wheel operations, if the operation is instantaneous or the amount of operation (brake pedal, accelerator, and steering wheel) is minute, and therefore does not result in a substantial function (deceleration, acceleration, and steering), it is not considered a driver's operation. Therefore, in order to be considered a driver's operation, the operation must be detected for a certain period of time or more and the amount of operation must be greater than a certain amount.

[0106] Stop hold release control routine

[0107] Next, a specific stop and hold release control process executed by the driving support ECU 10 (functional units corresponding to the stop and hold release unit 15 , the operation determination unit 16 , and the prohibition unit 17 ) will be described. Figure 2 2 shows a stop and hold release control routine executed by the driving support ECU 10. The driving support ECU 10 starts the stop and hold release control routine when the vehicle is stopped by PCS control (automatic braking control) and stop holding is started by the stop and hold control.

[0108] When the stop hold release control routine is activated, the driving support ECU 10 determines whether the accelerator pedal is operated in step S11. In this case, the accelerator pedal is operated sufficiently to activate the acceleration function based on the accelerator pedal operation amount detected by the accelerator operation amount sensor.

[0109] If no accelerator pedal operation is detected (S11: No), the driving support ECU 10 proceeds to step S12 to determine whether the brake pedal is being operated. In this case, the ECU determines whether the brake pedal is being operated to a degree sufficient to substantially activate the deceleration function based on the brake pedal operation amount detected by the brake operation amount sensor.

[0110] The case where it is determined as "yes" in step S12 is the case where the driver is not stepping on the accelerator pedal and is stepping on the brake pedal. In this case, it can be inferred that the brake pedal operation is being performed according to the driver's own intention. In addition, even if the stop and hold control is released (ended) and the stop and hold is released, the own vehicle will not start. Therefore, in this case, the driving assistance ECU10 causes its processing to enter step S13 to release the stop and hold control. When described more specifically, the driving assistance ECU10 sends a stop and hold release instruction to the brake ECU20 in step S13, and sends an output limit release instruction to the engine ECU30. Thus, the PCS control including the stop and hold control is terminated, and thereafter, it becomes a state in which the own vehicle can perform acceleration and deceleration movements corresponding to the driver's accelerator pedal operation and brake pedal operation.

[0111] When the driving assistance ECU 10 performs the processing of step S13 (releasing the stop and hold control), it terminates the release control routine. In addition, when the driving assistance ECU 10 temporarily terminates the stop and hold control routine, it does not subsequently execute the stop and hold release control routine until the vehicle stops by the automatic braking control and the stop and hold control is started.

[0112] On the other hand, if no brake pedal operation is detected (S12: No), that is, if neither the accelerator pedal nor the brake pedal is being operated, the driving assistance ECU 10 proceeds to step S14, where it obtains surrounding information, including forward sensor information from the forward sensor and rearward sensor information from the rear side radar sensor 80. Next, in step S15, the driving assistance ECU 10 determines whether the vehicle can be started (whether the vehicle's safety can be guaranteed) based on the surrounding information. In this case, the start is caused by the release of stop and hold control. In other words, it is caused by the creep phenomenon.

[0113] For example, if there is an obstacle directly in front of the vehicle, there is a risk that the vehicle may start to move and collide with the obstacle due to creeping if stop and hold control is released. Therefore, if there is no sufficient clearance (the distance between the vehicle and the obstacle) for the driver to stop the vehicle by operating the brake pedal before colliding with the obstacle, the driver determines that the vehicle cannot be started (S15: No). Furthermore, the driving assistance ECU 10 may also determine that the vehicle cannot be started if the traffic light in front of the vehicle is red (i.e., if starting the vehicle is not permitted under regulations).

[0114] If the driving assistance ECU 10 determines that the vehicle can be started (S15: Yes), the process proceeds to step S16. In step S16, the driving assistance ECU 10 determines whether the time elapsed since the start of the current stop and hold control (hold time) has exceeded a set time (e.g., 2 seconds). For example, when the stop and hold control is started, the driving assistance ECU 10 starts timing using a timer, reads the timer value, and makes the determination in step S16. This set time corresponds to the "release threshold time."

[0115] When the holding time has not reached the set time ( S16 : NO), the driving support ECU 10 returns the process to step S11 and repeats the above-mentioned process.

[0116] After the hold time reaches the set time, if neither the accelerator pedal nor the brake pedal is operated ( S12 : NO) and it is determined that there is no problem even if the vehicle is creeping ( S15 : YES), the driving support ECU 10 proceeds to step S13 , thereby releasing the stop hold control.

[0117] In addition, before the holding time reaches the set time, if the brake pedal operation is detected (S12: Yes) without the accelerator pedal operation (S11: No), the stop holding control is released at the time the brake pedal operation is detected even if the holding time has not reached the set time.

[0118] On the other hand, if the judgment in step S15 is "No", for example, when an obstacle that may collide when the vehicle is creeping is detected, the driving assistance ECU 10 causes its processing to enter step S17, determines that the driver's operation is inappropriate, and returns its processing to step S11.

[0119] Next, the case of accelerator pedal operation will be described. If the driving support ECU 10 determines in step S11 that the accelerator pedal operation is being performed (S11: Yes), the process proceeds to step S18. In step S18, the driving support ECU 10 determines whether there is a history record indicating that the driver's foot has been released from the accelerator pedal (i.e., the accelerator pedal operation has been released) after the vehicle's automatic braking control has been stopped (after the start of stop hold control).

[0120] When the automatic brake is engaged, the driver may become confused and lose their ability to make proper judgment. Consequently, the driver may mistakenly apply the pedals and continue to press the accelerator pedal despite their intention to apply the brake pedal. In this situation, if stop-and-hold control is released, the vehicle may suddenly start (accelerate) in response to the accelerator pedal application.

[0121] On the other hand, if the driver steps on the accelerator pedal again during the execution of the stop and hold control, that is, if the driver substantially takes his foot off the accelerator pedal and steps on the accelerator pedal again, the accelerator pedal operation can be inferred to be an operation performed by the driver with the intention to start his own vehicle.

[0122] Therefore, the processing of step S18 is to determine whether the accelerator pedal operation at the current time point is an accelerator pedal operation not based on the driver's intention (S18: No) or an accelerator pedal operation performed by the driver with the intention to start his own vehicle (S18: Yes).

[0123] When the driving support ECU 10 determines that the depressed state of the accelerator pedal continues ( S18 : NO), the processing proceeds to step S17 , determines that the driver's operation is inappropriate, and returns the processing to step S11 .

[0124] On the other hand, if it is determined that the accelerator pedal has been re-depressed (S18: YES), the driving support ECU 10 advances the process to step S19, where it obtains surrounding information (forward sensor information supplied by the front sensor and rear sensor information supplied by the rear side radar sensor 80). Next, in step S20, the driving support ECU 10 determines whether the vehicle can be started based on the surrounding information. In this case, starting refers to starting due to the release of stop hold control and the accelerator pedal being operated.

[0125] For example, in one of the following situations, the determination in step S20 is “No”.

[0126] 1. An obstacle is detected in front of the vehicle (for example, within a predetermined distance from the vehicle).

[0127] 2. While the steering wheel is being operated, an obstacle is detected in the estimated direction of travel of the own vehicle.

[0128] 3. Predicting that a moving object (other vehicles, pedestrians, bicycles, etc.) will cross in front of the vehicle in the left or right direction.

[0129] 4. Predicting the possibility of a moving object (other vehicle, pedestrian, bicycle, etc.) approaching the vehicle from behind or to the side of the vehicle.

[0130] 5. The signal light in front of your vehicle is red.

[0131] When the determination result in step S20 is “NO”, the driving support ECU 10 advances the process to step S17 , determines that the driver's operation is inappropriate, and returns the process to step S11 .

[0132] The driving support ECU 10 repeatedly performs such processing. Therefore, as long as it is determined that the driver's operation is inappropriate, the stop and hold control is not released.

[0133] If the determination in step S20 is "YES", the driving support ECU 10 proceeds to step S13 to release the stop and hold control, thereby terminating the PCS control.

[0134] Figure 3 This is a timing diagram showing an example of the timing at which stop and hold is released. At time t1, automatic braking control is initiated. At time t2, the vehicle stops and stop and hold control is initiated. In this example, even after stop and hold control is initiated, the driver's accelerator pedal operation continues. Therefore, after stop and hold control is initiated, it is determined that the driver's operation is inappropriate. Even if the driver's accelerator pedal continues to be depressed even after a set time (for example, 2 seconds) has passed after the start of stop and hold control, it is determined that the driver's driving operation is inappropriate and stop and hold control is continued.

[0135] At time t3, it is detected that the driver's accelerator pedal operation has ended. At this point in time, if there is no obstacle to starting the own vehicle (S15: YES), the stop hold is released.

[0136] Figure 4 This example shows an example where the driver re-depresses the accelerator pedal during the stop-and-hold period. The driver's re-depression of the accelerator pedal is detected at time t4. In this case, even before the hold time reaches the set time, if there are no obstacles to starting the vehicle (S20: Yes), the stop-and-hold control is released. As a result, the vehicle starts as intended by the driver.

[0137] Figure 5This is a timing diagram showing an example of the timing at which stop-and-hold control is released in a conventional device, serving as a comparative example. At time t11, the automatic brake is applied. At time t12, the vehicle stops and stop-and-hold control is initiated. In this example, even after stop-and-hold control is initiated, the driver continues to operate the accelerator pedal. At time t13, a set time (e.g., 2 seconds) has passed since the start of stop-and-hold control, stop-and-hold control is released. At this time, the accelerator pedal remains depressed, so the vehicle starts abruptly in response to the release of stop-and-hold control.

[0138] As described above, according to the driving assistance device of this embodiment, based on information about the driver's driving operation and information indicating the conditions surrounding the own vehicle, when releasing the stop and hold control, it is determined whether the driver's driving operation while the own vehicle is in a stopped state is appropriate or inappropriate relative to the conditions surrounding the own vehicle. If it is determined that the driver's driving operation is inappropriate relative to the conditions surrounding the own vehicle, the release of the stop and hold control is prohibited. On the other hand, if the driver's driving operation is not determined to be inappropriate relative to the conditions surrounding the own vehicle when the release condition is met, the stop and hold control is released. Therefore, the stop and hold of the own vehicle can be released in a safe manner even if the stop and hold (stop and hold control) is released. As a result, the driver's unintentional start of the own vehicle is suppressed. In addition, collisions with obstacles associated with the release of the stop and hold control are suppressed.

[0139] Furthermore, if a driving operation that can be presumed to be intentional by the driver is determined to have been performed during the execution of stop and hold control, the stop and hold control is released even before the hold time reaches the set time, provided that the driver's driving operation is not determined to be inappropriate for the conditions surrounding the own vehicle. Therefore, the driver can intentionally start the own vehicle before the hold time reaches the set time.

[0140] For example, the accelerator pedal re-depression operation can be inferred as an operation based on the driver's intention. Therefore, when the accelerator pedal re-depression operation is detected, if the situation around the own vehicle is that there is no obstacle to the starting of the own vehicle, the own vehicle can be started directly and smoothly.

[0141] Furthermore, if the accelerator pedal is continuously depressed, the driver's operation is determined to be inappropriate, regardless of the surrounding conditions of the vehicle, and the cancellation of the stop and hold control is prohibited.

[0142] Modifications

[0143] For example, Figure 6 As shown, a determination process of step S21 may be added between steps S12 and S14. Step S21 determines whether the driver is seated in the driver's seat (whether the driver has exited the vehicle). For example, in step S21, the driving assistance ECU 10 reads a signal indicating the status of a driver's seat belt switch (not shown) to determine whether the driver is seated in the driver's seat. Alternatively, instead of the seat belt switch, the determination may be made by reading a signal from another sensor, such as a seat sensor that detects whether the driver is seated in the driver's seat.

[0144] If it is determined that the driver is sitting in the driver's seat, the driving support ECU 10 advances the processing to step S14 . On the other hand, if it is determined that the driver is not sitting in the driver's seat, the driving support ECU 10 advances the processing to step S17 .

[0145] In a situation where the driver is not sitting in the driver's seat, neither accelerator pedal operation nor brake pedal operation is detected. Therefore, when there is no obstacle in front of the own vehicle, the stop and hold control will be released when the holding time exceeds the set time. However, according to this variant example 1, even in such a situation, the release of the stop and hold control can be effectively prohibited.

[0146] Furthermore, the driving support ECU 10 may determine whether other switches provided on the driver's seat have been operated in addition to the seatbelt switch, and may also determine that the driver is sitting in the driver's seat when the operation of other switches is detected.

[0147] As mentioned above, the driving assistance device according to the present embodiment has been described. However, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the purpose of the present invention.

[0148] For example, in this embodiment, stop-and-hold release control is applied to automatic braking performed by PCS control, but the automatic braking to which stop-and-hold release control is applied is not limited to PCS control. For example, it can also be applied to a driving assistance system that activates the automatic brake when it is estimated that the driver wishes to stop the vehicle at a predetermined stopping position (for example, if the driver missed a traffic light) despite legally requiring the vehicle to stop based on traffic infrastructure information (information displayed by traffic lights and road signs) obtained by the front sensor. Furthermore, traffic infrastructure information does not necessarily need to be obtained from the front camera sensor 70. For example, a configuration can be employed in which traffic infrastructure information transmitted wirelessly from a roadside device or the like is obtained via the wireless communication device 51.

[0149] Furthermore, the present invention can also be applied to a wrong start prevention system that detects a driver's pedal misstep (incorrectly stepping on the accelerator pedal while intending to step on the brake pedal) and activates the automatic brake to prevent the vehicle from suddenly starting against the driver's will.

[0150] In addition, the front sensor may be modified as appropriate. For example, the front camera sensor 70 may not have the function of recognizing traffic infrastructure equipment such as traffic lights.

[0151] In the present embodiment, in step S20 , traffic infrastructure information (eg, traffic light: red) is included as one of the determination conditions. However, such traffic infrastructure information does not necessarily need to be included, and only the presence or absence of an obstacle may be determined.

[0152] In addition, in this embodiment, when the vehicle is kept in a stopped state, the brake actuator 21 is controlled to supply the oil pressure set for stopping and maintaining the vehicle to the wheel brake pumps of the friction brake mechanisms 22 of the left and right front and rear wheels, but for example, an electric parking brake (not shown) can also be operated.

Claims

1. A driving assistance device, characterized in that: include: an automatic braking unit configured to execute automatic braking control for automatically stopping the vehicle by applying a braking force to the vehicle when it is determined that a predetermined automatic stopping condition is satisfied; a stop holding unit configured to execute stop holding control for continuously stopping the own vehicle by applying a braking force to the own vehicle so that the own vehicle, which is in a state stopped by the automatic braking unit, does not move forward or backward; a stop and hold release unit configured to, when the stop and hold control is being executed by the stop and hold unit, cause the stop and hold unit to release the stop and hold control upon determining that a predetermined release condition is satisfied; and The prohibition unit is configured to prohibit the stop and hold release unit from causing the stop and hold unit to release the stop and hold control if, during the execution of the stop and hold control, there is an obstacle within a predetermined distance in front of the own vehicle and the brake pedal is not operated by the driver of the own vehicle, even if the release condition is met.

2. A driving assistance device, characterized in that: include: an automatic braking unit configured to execute automatic braking control for automatically stopping the vehicle by applying a braking force to the vehicle when it is determined that a predetermined automatic stopping condition is satisfied; a stop holding unit configured to execute stop holding control for continuously stopping the own vehicle by applying a braking force to the own vehicle so that the own vehicle, which is in a state stopped by the automatic braking unit, does not move forward or backward; a stop and hold release unit configured to, when the stop and hold control is being executed by the stop and hold unit, cause the stop and hold unit to release the stop and hold control upon determining that a predetermined release condition is satisfied; and The prohibition unit is configured to prohibit the stop and hold release unit from releasing the stop and hold control when the traffic light in front of the own vehicle indicates red and the brake pedal is not operated by the driver of the own vehicle during the execution of the stop and hold control, even if the release condition is met.

3. A driving assistance device, characterized in that: include: an automatic braking unit configured to execute automatic braking control for automatically stopping the vehicle by applying a braking force to the vehicle when it is determined that a predetermined automatic stopping condition is satisfied; a stop holding unit configured to execute stop holding control for continuously stopping the own vehicle by applying a braking force to the own vehicle so that the own vehicle, which is in a state stopped by the automatic braking unit, does not move forward or backward; a stop and hold release unit configured to, when the stop and hold control is being executed by the stop and hold unit, cause the stop and hold unit to release the stop and hold control upon determining that a predetermined release condition is satisfied; and The prohibition unit is configured to prohibit the stop and hold release unit from causing the stop and hold unit to release the stop and hold control when the traffic light in front of the own vehicle indicates red and the accelerator pedal is operated by the driver of the own vehicle during the execution of the stop and hold control, even if the release condition is met.

4. A driving assistance device, characterized in that: include: an automatic braking unit configured to execute automatic braking control for automatically stopping the vehicle by applying a braking force to the vehicle when it is determined that a predetermined automatic stopping condition is satisfied; a stop holding unit configured to execute stop holding control for continuously stopping the own vehicle by applying a braking force to the own vehicle so that the own vehicle, which is in a state stopped by the automatic braking unit, does not move forward or backward; a stop and hold release unit configured to, when the stop and hold control is being executed by the stop and hold unit, cause the stop and hold unit to release the stop and hold control upon determining that a predetermined release condition is satisfied; and The prohibition unit is configured to prohibit the stop and hold release unit from causing the stop and hold unit to release the stop and hold control when the driver of the own vehicle is not sitting in the driver's seat of the own vehicle during execution of the stop and hold control, even when the release condition is satisfied.

5. The driving assistance device according to any one of claims 1 to 4, characterized in that: The stop hold release unit is configured to determine that the release condition is satisfied when a stop hold time is equal to or longer than a predetermined release threshold time and the accelerator pedal is not operated, the stop hold time being a time during which the stop hold control is continuously executed.

6. The driving assistance device according to claim 5, characterized in that The stop and hold release unit is configured to determine whether a specific operation that can be inferred to be based on the driver's intention has been performed during the execution of the stop and hold control. If it is determined that the specific operation has been performed, the release condition is determined to be met even if the stop and hold time is less than the release threshold time.

7. The driving assistance device according to claim 6, characterized in that: The specific operation is a renewed depression operation of the accelerator pedal performed while the stop hold control is being executed.

8. The driving assistance device according to claim 6, wherein: The specific operation is an operation of the brake pedal performed when the operation amount of the accelerator pedal is zero while the stop holding control is being executed.

9. The driving assistance device according to any one of claims 1 to 4, characterized in that: The prohibition unit is configured to prohibit the stop holding release unit from causing the stop holding unit to release the stop holding control if the driver of the own vehicle continues to depress the accelerator pedal while the stop holding control is being executed.

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