Driving assistance device

Abstract

The purpose of the present invention is to optimize deceleration assistance in accordance with a driver's desired value. The present invention is provided with: an intersection recognition unit (100) that recognizes an intersection located ahead of a vehicle (VH) in the direction of travel; a left-right turn prediction unit (110) that predicts whether or not the vehicle (VH) will turn right or left at the intersection recognized by the intersection recognition unit (100); a deceleration control unit (120, 130, 140) that performs deceleration control for decelerating the vehicle (VH) to a target vehicle speed (Vt) before the vehicle (VH) reaches the target position (Pt) when the left / right turn prediction unit (100) predicts that the vehicle will turn right or left; and an external information acquisition unit (40, 60, 70, 80) that acquires information about the vehicle and pedestrian in the opposite direction and information about the color of the traffic light, and the deceleration control unit (130, 140) sets the target vehicle speed and / or the start time at which the deceleration control starts on the basis of the information acquired by the external information acquisition unit (40, 60, 70, 80).

Description

Technical Field

[0001] The present disclosure relates to a driving assistance device, and more particularly to a technique applicable to deceleration assistance for a vehicle. Background Art

[0002] For example, Patent Document 1 discloses a device that performs deceleration assistance to decelerate a vehicle to a target vehicle speed before the vehicle reaches a deceleration target location when the vehicle is turning right or left at an intersection and passing through, and when it is predicted that the vehicle is turning left, sets the deceleration target location closer to the front side than when it is predicted that the vehicle is turning right. Prior Art Documents Patent Documents

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-199241 Summary of the Invention

[0004] The vehicle speed expected by a driver for deceleration assistance varies depending on the presence or absence of oncoming vehicles, crossing pedestrians, or the timing of signal color change when the vehicle turns left or right at an intersection. Therefore, when changing the deceleration target location only based on whether the vehicle is turning right or left at an intersection as in the device described in Patent Document 1, sometimes the deceleration of the vehicle caused by deceleration assistance may become excessive or insufficient compared to the driver's expectation. That is, it can be said that there is room for improvement in optimizing deceleration assistance corresponding to the driver's expectation.

[0005] The technology of the present disclosure has been completed in view of the above circumstances, and its object is to realize optimization of deceleration assistance corresponding to the driver's expectation.

[0006] The driving assistance device of the present disclosure is characterized by including: An intersection recognition unit that recognizes an intersection located ahead of the traveling direction of the vehicle; A left / right turn prediction unit that predicts whether the vehicle will turn right or left at the intersection recognized by the intersection recognition unit; and A deceleration control unit that, when the left / right turn prediction unit predicts that the vehicle will turn right or left at the intersection, performs deceleration control to decelerate the vehicle to a specified target vehicle speed before the vehicle reaches a specified target position, The driving assistance device further includes an external information acquisition unit that acquires information on oncoming vehicles and / or information on pedestrians and / or information on the signal color of the intersection, The deceleration control unit sets the target vehicle speed and / or the start time of starting the deceleration control based on the information acquired by the external information acquisition unit. Brief Description of the Drawings

[0007] Figure 1 is a schematic diagram showing the hardware configuration of the vehicle according to the present embodiment. Figure 2A is a schematic diagram showing the software configuration of the control device according to the present embodiment. Figure 2B is a schematic diagram for explaining the deceleration control according to the present embodiment. Figure 2C is a schematic diagram for explaining the deceleration setting map according to the present embodiment. FIG. 3 is a schematic diagram for explaining a specific example of the change process of the target vehicle speed according to the present embodiment. Figure 4 is a flowchart for explaining the routine of the deceleration assist process according to the present embodiment. Figure 5 is a schematic diagram for explaining a modified example. Detailed Embodiment

[0008] Next, the driving assist device according to the present embodiment will be described with reference to the drawings.

[0009] [Hardware Configuration] Figure 1 is a schematic diagram showing the hardware configuration of the vehicle VH according to the present embodiment. Hereinafter, the vehicle VH may sometimes be referred to as the own vehicle when it needs to be distinguished from other vehicles or the like.

[0010] The vehicle VH 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, an interface device 14, etc. 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 various programs. The RAM 13 is a volatile memory that provides a work area into which various programs are loaded when executed by the CPU 11. The interface device 14 is a communication device for communicating with external devices.

[0011] The ECU 10 is a central device for performing driving assistance such as deceleration assistance. Driving assistance includes the concept of autonomous driving. The ECU 10 is communicably connected to a drive device 20, a steering device 21, a braking device 22, an in-vehicle sensor device 30, an external sensor device 40, a turn signal switch 50, turn signals 58L, 58R, a position information acquisition device 60, a map database 70, a communication device 80, etc.

[0012] The drive device 20 generates a driving force transmitted to the drive wheels of the vehicle VH. As the drive device 20, for example, an electric motor or an engine can be cited. In the present embodiment, the vehicle VH can be any one of a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), a fuel cell vehicle (FCEV), a battery electric vehicle (BEV), and an engine vehicle. The steering device 21 applies a steering force to the wheels of the vehicle VH. The braking device 22 applies a braking force to the wheels of the vehicle VH.

[0013] The in-vehicle sensor device 30 is a sensor group that detects the state of the vehicle VH. Specifically, the in-vehicle 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 of the vehicle VH (hereinafter referred to as the vehicle speed). The accelerator sensor 32 detects the operation amount of an accelerator pedal (not shown) by the driver. The brake sensor 33 detects the operation amount of a brake pedal (not shown) by the driver. The steering angle sensor 34 detects the rotation angle of a steering wheel or a steering shaft (not shown) of the vehicle VH, that is, the steering angle. The yaw rate sensor 35 detects the yaw rate of the vehicle VH. The in-vehicle sensor device 30 transmits the state of the vehicle VH detected by each of the sensors 31 to 35 to the ECU 10 at a predetermined cycle.

[0015] The external sensor device 40 is a sensor group that identifies target object information related to target objects around the vehicle VH. Specifically, the external sensor device 40 includes a radar sensor 41, a camera sensor 42, and the like. Here, as the target object information, for example, surrounding vehicles, pedestrians, traffic lights, white lines on the road, signs, and the like can be cited.

[0016] The radar sensor 41 detects target objects existing around the vehicle VH. The radar sensor 41 includes a millimeter-wave radar and / or a lidar. The millimeter-wave radar emits radio waves in the millimeter-wave band (millimeter waves) and receives the millimeter waves (reflected waves) reflected by target objects existing within the emission range. The millimeter-wave radar obtains the relative distance between the vehicle VH and the target object, the relative speed between the vehicle VH and the target object, etc., 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 pulsed laser light having a wavelength shorter than that of millimeter waves in multiple directions and receives the reflected light reflected by the target object, thereby obtaining the shape of the target object detected in front of the vehicle VH, the relative distance between the vehicle VH and the target object, the relative speed between the vehicle VH and the target object, etc.

[0017] The camera sensor 42 captures the surroundings of the vehicle VH and processes the captured image data to obtain information on the objects around the vehicle VH. As the camera sensor 42, for example, a digital camera having a photographing element such as a CMOS or a CCD can be used. The object information is information indicating the type of the object detected around the vehicle VH, the relative distance between the vehicle VH and the object, the relative speed between the vehicle VH and the object, and the like. The type of the object can be identified, for example, by machine learning such as pattern matching.

[0018] The external sensor device 40 repeatedly transmits the obtained object information to the ECU 10 every predetermined time. The ECU 10 determines the relative relationship between the vehicle VH and the object by synthesizing the relative relationship between the vehicle VH and the object obtained by the radar sensor 41 and the relative relationship between the vehicle VH and the object obtained by the camera sensor 42. In addition, the external sensor device 40 does not necessarily have to include both the radar sensor 41 and the camera sensor 42, and for example, it may include only the camera sensor 42.

[0019] The turn indicator lever 51 is an operator for the driver to blink the left and right turn indicators 58L and 58R. The turn indicator switch 50 detects the operation direction of the driver on the turn indicator lever 51. When the driver operates the turn indicator lever 51, the turn indicator switch 50 transmits a blink instruction signal corresponding to the operation direction to the ECU 10. When the ECU 10 receives the blink instruction signal, it blinks the turn indicators 58L and 58R corresponding to the operation direction of the turn indicator lever 51.

[0020] The position information acquisition device 60 acquires the current position information of the vehicle VH. As the position information acquisition device 60, for example, a GPS (Global Positioning System), a GNSS (Global Navigation Satellite System), etc. included in a navigation system (not shown) can be used. The position information acquisition device 60 transmits the acquired current position information of the vehicle VH to the ECU 10 at a predetermined cycle. In addition, the position information of the vehicle VH can also be acquired by V2X (Vehicle-to-Everything) communication using the communication device 80 described later.

[0021] The map database 70 is a database of map information and is stored in a storage device (hard disk, flash memory, etc.) provided in the vehicle VH. The map information includes the positions of intersections of roads and the like. In addition, the map database 70 can also be stored in an external server capable of communicating with the vehicle VH. In this case, the vehicle VH can obtain the map information from the external server using the communication device 80.

[0022] The communication device 80 performs V2X communication. Specifically, the communication device 80 performs V2V communication (Vehicle to Vehicle) between the host vehicle VH and other vehicles, V2I communication (Vehicle to Infrastructure) between the host vehicle VH and infrastructure, and V2P communication (Vehicle to Pedestrian) between the host vehicle VH and pedestrians. The communication device 80 can obtain information about the surroundings of the host vehicle VH through V2X communication. As the information about the surroundings, for example, it includes the position of intersections, the light color of traffic lights, the travel route information such as straight or left / right turns of other vehicles, the position information of pedestrians, etc. The communication device 80 sends the obtained information about the surroundings to the ECU 10 at a predetermined cycle.

[0023] [Software Configuration] Figure 2A It is a schematic diagram showing the software configuration of the ECU 10 according to the present embodiment. As Figure 2A shown, the ECU 10 includes a junction recognition unit 100, a left / right turn prediction unit 110, a target deceleration calculation unit 120, a deceleration control unit 130, a target vehicle speed change unit 140, etc. as functional elements. These functional elements 100 to 140 are realized by the CPU 11 of the ECU 10 reading the program stored in the ROM 12 into the RAM 13 and executing it. In addition, all or part of the functional elements 100 to 140 may also be provided in another ECU separate from the ECU 10 or an information processing device of a facility (such as a management center) capable of communicating with the vehicle VH.

[0024] The junction recognition unit 100 recognizes the position of the intersection (in the case of multiple consecutive intersections ahead, it refers to the nearest intersection) ahead of the traveling direction of the vehicle VH based on the target object information obtained by the external sensor device 40. The camera sensor 42 of the external sensor device 40 will obtain the traffic lights and signs set at the intersection before obtaining the stop line of the intersection. Therefore, the junction recognition unit 100 recognizes the intersection by obtaining the traffic lights and signs from the image data in front of the vehicle VH captured by the camera sensor 42. The traffic lights and signs can be discriminated by machine learning such as pattern matching. When the junction recognition unit 100 recognizes an intersection, it performs image processing on the image data captured by the camera sensor 42, and thus recognizes the position of the intersection (relative position with respect to the vehicle VH) by a known method.

[0025] In addition, the intersection recognition unit 100 may also identify the position of the intersection based on the target information obtained by the radar sensor 41. Alternatively, the intersection recognition unit 100 may also identify the position of the intersection based on the information received by the communication device 80 through V2I communication from an advanced road traffic system (ITS: Intelligent Transport Systems) or the like. Alternatively, the intersection recognition unit 100 may also identify the position of the intersection based on the current position of the vehicle VH obtained by the position information acquisition device 60 and the map database 70.

[0026] When the intersection recognition unit 100 recognizes an intersection in front of the vehicle VH, the left / right turn prediction unit 110 predicts whether the vehicle VH will turn right or left at the intersection. After the intersection recognition unit 100 recognizes an intersection in front of the vehicle VH, when the left / right turn prediction unit 110 receives a flashing indication signal indicating either the right direction or the left direction from the direction indicator switch 50, it predicts that the vehicle VH will turn right or left at the intersection. In addition, when the left / right turn prediction unit 110 predicts that the vehicle VH will turn right or left at the intersection, it determines whether the vehicle VH will turn right or left toward the oncoming lane side based on the detection result of the external sensor device 40.

[0027] In addition, the left / right turn prediction unit 110 may also predict that the vehicle VH will turn right or left at the intersection after the intersection recognition unit 100 recognizes an intersection in front of the vehicle VH and the driver releases the depression of the accelerator pedal (accelerator OFF). Alternatively, the left / right turn prediction unit 110 may also predict that the vehicle VH will turn right or left at the intersection when it is determined through the external sensor device 40 that the vehicle VH is traveling in a right-turn only lane or a left-turn only lane at the intersection. Alternatively, the left / right turn prediction unit 110 may also predict that the vehicle VH will turn right or left at the intersection when the route set by the navigation system is set to a route that turns right or left at the intersection.

[0028] As Figure 2BAs shown, the target deceleration calculation unit 120 calculates the target deceleration Gt required to decelerate the vehicle VH to a prescribed reference target vehicle speed Vt suitable for a right turn or a left turn before the vehicle VH reaches a prescribed target position Pt closer to the front side than the intersection from a prescribed deceleration start position Ps. The deceleration start position Ps is not particularly limited. For example, a position at a prescribed first distance D1 closer to the vehicle VH side than the position Pc of the intersection recognized by the intersection recognition unit 100 may be set as the deceleration start position Ps. The first distance D1 is a distance that is at least longer than the distance from the position Pc of the intersection to the position of the stop line. The target position Pt is not particularly limited either, but in the present embodiment, the position of the stop line of the intersection where the vehicle VH is going to make a right turn or a left turn is set as the target position Pt. In addition, at the moment when the intersection recognition unit 100 recognizes the intersection, the camera sensor 42 of the external sensor device 40 has not acquired the stop line of the intersection. Therefore, the target deceleration calculation unit 120, for example, recognizes the position of the stop line as the position at a prescribed second distance D2 (where D2 is shorter than the first distance D1) closer to the vehicle VH side than the position Pc of the intersection recognized by the intersection recognition unit 100.

[0029] The target deceleration calculation unit 120 calculates the target deceleration Gt according to a deceleration setting map M (refer to Figure 2C ) stored in advance in the ROM 12 of the ECU 10 and the like. The deceleration setting map M is, for example, a map referred to according to the distance D from the deceleration start position Ps to the target position Pt and the current vehicle speed V of the vehicle VH, and is set such that the higher the vehicle speed V and the shorter the distance D, the larger the target deceleration Gt (absolute value). The target deceleration calculation unit 120 refers to the deceleration setting map M based on the distance D from the deceleration start position Ps to the target position Pt and the vehicle speed V detected by the vehicle speed sensor 31, and thereby calculates the target deceleration Gt.

[0030] When the left / right turn prediction unit 110 predicts that the vehicle VH will make a right turn or a left turn at the intersection, the deceleration control unit 130 performs deceleration control to decelerate the vehicle VH at the target deceleration Gt calculated by the target deceleration calculation unit 120. When the vehicle VH reaches the deceleration start position Ps, the deceleration control unit 130 starts the deceleration control to decelerate the vehicle VH at the target deceleration Gt. Regarding whether the vehicle VH has reached the deceleration start position Ps, for example, it can be identified based on the movement amount of the vehicle VH calculated by the odometer from the detection results of the vehicle speed sensor 31 and the yaw rate sensor 35, or it can also be identified based on the movement trajectory of the vehicle VH acquired by the position information acquisition device 60.

[0031] The deceleration control unit 130 performs deceleration control by controlling the operation of the braking device 22 based on the deviation between the actual deceleration Ga of the vehicle VH and the target deceleration Gt. In addition, for deceleration control, not only the braking force of the braking device 22 can be used, but also engine braking can be used when the drive device 20 is an engine, and regenerative braking can be used when the drive device 20 is an electric motor. The actual deceleration Ga of the vehicle VH can be obtained by differentiating the vehicle speed V detected by the vehicle speed sensor 31, or can also be obtained by the acceleration sensor if the in-vehicle sensor device 30 is equipped with an acceleration sensor.

[0032] When the vehicle VH reaches the target position Pt, the deceleration control unit 130 ends the deceleration control. Regarding whether the vehicle VH has reached the target position Pt, for example, it can be identified based on the movement amount of the vehicle VH calculated by the odometer from the detection results of the vehicle speed sensor 31 and the yaw rate sensor 35, or can also be identified based on the movement trajectory of the vehicle VH obtained by the position information acquisition device 60. In addition, during the process in which the vehicle VH approaches the target position Pt, the camera sensor 42 of the external sensor device 40 starts to acquire the stop line of the intersection. When the camera sensor 42 starts to acquire the stop line of the intersection, the deceleration control unit 130 switches the target position Pt to the position of the stop line identified from the image data of the camera sensor 42.

[0033] Here, if deceleration control is performed based on the unified reference target vehicle speed Vt, depending on the surrounding conditions such as the presence or absence of oncoming vehicles, crossing pedestrians, or the switching timing of the traffic signal color, sometimes the deceleration of the vehicle VH caused by the deceleration control may become excessive or insufficient compared to the driver's expectation. The target vehicle speed change unit 140 changes the target vehicle speed used in the deceleration control from the reference target vehicle speed Vt according to the surrounding conditions, thereby realizing the optimization of the deceleration assistance corresponding to the driver's expectation. Hereinafter, a specific example of the target vehicle speed change process performed by the target vehicle speed change unit 140 will be described with reference to FIG. 3. In addition, in FIG. 3, the case of driving on the left side is described. In the case of driving on the right side, since it is only a left-right reversal, the description is omitted.

[0034] Figure 3A This is a case where there is an oncoming lane L2 in the direction in which the own vehicle VH is about to turn right from the own lane L1, and there is another vehicle VH2 (oncoming vehicle) approaching the own vehicle VH in the oncoming lane L2. If deceleration control is performed based on the unified reference target vehicle speed Vt at the moment when the own vehicle VH reaches the target position Pt and the oncoming vehicle VH2 enters the intersection, sometimes the driver of the own vehicle VH may feel insufficient deceleration. That is, the deceleration of the vehicle VH caused by the deceleration control becomes too little compared to the driver's expectation, which may cause uneasiness to the driver.

[0035] When it is predicted that the oncoming vehicle VH2 will enter the intersection within a range around the time when the host vehicle VH reaches the target position Pt by a specified time before and after, the target vehicle speed used in the deceleration control is changed to a first target vehicle speed Vt1 (<Vt) lower than the reference target vehicle speed Vt. Thereby, in the situation where it is predicted that the oncoming vehicle VH2 will enter the intersection, deceleration of the vehicle VH close to the driver's expectation value can be achieved. That is, it is possible to effectively prevent the deceleration of the vehicle VH caused by the deceleration control from becoming too small relative to the driver's expectation value. The time when the oncoming vehicle VH2 enters the intersection can be identified based on the information received from the oncoming vehicle VH2 through V2V communication by the communication device 80, or can also be identified based on the relative position and relative speed of the oncoming vehicle VH2 obtained by the external sensor device 40.

[0036] When it is not predicted that the oncoming vehicle VH2 will enter the intersection within a range around the time when the host vehicle VH reaches the target position Pt by a specified time before and after, and when the oncoming vehicle VH2 is going to turn right to the host vehicle lane L1 side, the target vehicle speed used in the deceleration control is not changed. That is, deceleration control based on the normal reference target vehicle speed Vt is implemented. Whether the oncoming vehicle VH2 is going to turn right to the host vehicle lane L1 side can be identified based on the information received from the oncoming vehicle VH2 through V2V communication by the communication device 80, or can also be identified based on the flashing state of the direction indicator of the oncoming vehicle VH2 obtained by the external sensor device 40.

[0037] Figure 3B This is the case where there are crosswalks PC1, PC2 on the traveling route of the host vehicle VH where the host vehicle VH is going to turn right or left at the intersection, and there are pedestrians (including bicycles) who are currently passing or going to pass on the crosswalks PC1, PC2. If deceleration control is performed based on the unified reference target vehicle speed Vt when the pedestrians are passing or going to pass on the crosswalks PC1, PC2 at the time when the host vehicle VH reaches the target position Pt, sometimes the driver of the host vehicle VH may feel that the deceleration is insufficient. That is, the deceleration of the vehicle VH caused by the deceleration control becomes too small relative to the driver's expectation value, and it may cause uneasiness to the driver.

[0038] When it is predicted that a pedestrian (including a moving object such as a bicycle) will pass or be about to pass on the crosswalks PC1 and PC2 within a range around the time when the host vehicle VH reaches the target position Pt by a specified time before and after, the target vehicle speed changing unit 140 changes the target vehicle speed used in the deceleration control to a second target vehicle speed Vt2 (<Vt) lower than the reference target vehicle speed Vt. Thereby, in a situation where it is predicted that a pedestrian will pass or be about to pass on the crosswalks PC1 and PC2, deceleration of the vehicle VH closer to the driver's expectation value can be achieved. That is, it is possible to effectively prevent a situation where the deceleration of the vehicle VH caused by the deceleration control becomes too small relative to the driver's expectation value. The second target vehicle speed Vt2 may be the same vehicle speed as the first target vehicle speed Vt1, or may be a different vehicle speed. Whether a pedestrian will pass on the crosswalks PC1 and PC2 can be identified based on information received by the communication device 80 through V2P communication from a portable terminal or the like held by the pedestrian, or can also be identified based on the relative position and relative speed of the pedestrian obtained by the external sensor device 40.

[0039] When it is not predicted that a pedestrian will pass or be about to pass on the crosswalks PC1 and PC2 within a range around the time when the host vehicle VH reaches the target position Pt by a specified time before and after, the target vehicle speed used in the deceleration control is not changed. That is, deceleration control based on the normal reference target vehicle speed Vt is implemented. In addition, the distance from the target position Pt to the crosswalk PC2 on the oncoming lane L2 side is longer than the distance from the target position Pt to the crosswalk PC1 on the own lane L1 side. Therefore, when there is a crosswalk PC2 on the oncoming lane L2 side, that is, when the host vehicle VH is to turn right, on the traveling route that the host vehicle VH is about to travel, the target vehicle speed changing unit 140 may also set a wider range of the specified time used in the pedestrian determination.

[0040] Figure 3C This is a situation where the lighting color of the traffic light TL provided at the intersection changes to a lighting color that prohibits the host vehicle VH from entering the intersection (for example, red) at the time when the host vehicle VH enters the intersection. If deceleration control is performed based on the unified reference target vehicle speed Vt in a situation where the lighting color of the traffic light TL changes to red at the time when the host vehicle VH reaches the target position Pt, sometimes the deceleration of the vehicle VH caused by the deceleration control becomes excessive relative to the driver's expectation value. That is, when the host vehicle VH fails to pass through the intersection due to the deceleration control operation, it causes trouble to the driver.

[0041] When it is predicted that within a range around a specified time before and after the time when the host vehicle VH reaches the target position Pt, the lighting color of the traffic signal TL will change to a lighting color (e.g., red) that prohibits the host vehicle VH from entering the intersection, the target vehicle speed used in the deceleration control is changed to a third target vehicle speed Vt3 (> Vt) that is higher than the reference target vehicle speed Vt. Thereby, in a situation where it is predicted that the lighting color of the traffic signal TL will change to a lighting color that prohibits the host vehicle VH from entering the intersection, deceleration of the host vehicle VH closer to the driver's expectation value can be achieved. That is, it is possible to effectively prevent a situation where the deceleration of the host vehicle VH caused by the deceleration control becomes excessive relative to the driver's expectation value. Regarding whether the lighting color of the traffic signal TL will change to a lighting color that prohibits the host vehicle VH from entering the intersection, it can be predicted based on changes in the lighting color of the pedestrian traffic signal acquired by the external sensor device 40, the lighting of the arrow lamp allowing a right turn, etc., or it can also be identified based on information received by the communication device 80 through V2I communication from an ITS or the like.

[0042] When it is not predicted that within a range around a specified time before and after the time when the host vehicle VH reaches the target position Pt, the lighting color of the traffic signal TL will change to a lighting color that prohibits the host vehicle VH from entering the intersection, the target vehicle speed used in the deceleration control is not changed. That is, the deceleration control is performed based on the normal reference target vehicle speed Vt. In addition, when it is predicted that at the time when the host vehicle VH reaches the target position Pt, the lighting color of the traffic signal TL is already a lighting color that prohibits the host vehicle VH from entering the intersection, stop control for stopping the host vehicle VH at the target position Pt may also be performed.

[0043] Next, based on Figure 4 , a routine of the deceleration assistance process performed by the CPU 11 of the ECU 10 will be described. This routine starts when the vehicle VH is traveling.

[0044] In step S100, the ECU 10 determines whether an intersection is recognized in front of the host vehicle VH. When an intersection is recognized ("Yes"), the ECU 10 proceeds to the process of step S110. On the other hand, when an intersection is not recognized ("No"), the ECU 10 returns to the determination process of step S100.

[0045] In step S110, the ECU 10 predicts whether the vehicle VH will turn right or left at the intersection. When it is predicted that the vehicle VH will turn right or left at the intersection ("Yes"), the ECU 10 proceeds to the process of step S120. On the other hand, when it is not predicted that the vehicle VH will turn right or left at the intersection ("No"), the ECU 10 returns to the determination process of step S100.

[0046] In step S120, the ECU 10 determines whether the host vehicle VH is to turn right toward the oncoming lane L2 (or turn left in the case of driving on the right). When the host vehicle VH is to turn right toward the oncoming lane L2 ("Yes"), the ECU 10 proceeds to the process of step S130. On the other hand, when the host vehicle VH is not to turn right toward the oncoming lane L2 ("No"), the ECU 10 proceeds to the process of step S140.

[0047] In step S130, the ECU 10 determines whether it is predicted that the oncoming vehicle VH2 will enter the intersection within a range around a specified time before and after the time when the host vehicle VH reaches the target position Pt. When it is predicted that the oncoming vehicle VH2 will enter the intersection ("Yes"), the ECU 10 proceeds to the process of step S135. On the other hand, when it is not predicted that the oncoming vehicle VH2 will enter the intersection ("No"), the ECU 10 proceeds to the process of step S140.

[0048] In step S135, the ECU 10 changes the target vehicle speed to a first target vehicle speed Vt1 lower than the reference target vehicle speed Vt and performs deceleration control, and then returns from this routine.

[0049] When entering the process of step S140 from step S120 or step S130, the ECU 10 determines whether it is predicted that a pedestrian will be passing or about to pass on the crosswalks PC1, PC2 within a range around a specified time before and after the time when the host vehicle VH reaches the target position Pt. When it is predicted that a pedestrian will be passing or about to pass on the crosswalks PC1, PC2 ("Yes"), the ECU 10 proceeds to the process of step S145. On the other hand, when it is not predicted that a pedestrian will be passing or about to pass on the crosswalks PC1, PC2 ("No"), the ECU 10 proceeds to the process of step S150. Additionally, when the host vehicle VH is to turn right toward the oncoming lane L2 (or turn left in the case of driving on the right), the range of the specified time used in the pedestrian determination in step S140 may be set wider.

[0050] In step S145, the ECU 10 changes the target vehicle speed to a second target vehicle speed Vt2 lower than the reference target vehicle speed Vt and performs deceleration control, and then returns from this routine.

[0051] When entering the process of step S150 from step S140, the ECU 10 determines whether it is predicted that within a range around the time when the own vehicle VH reaches the target position Pt by a specified time before and after, the lighting color of the traffic signal TL will change to a lighting color (red) that prohibits the own vehicle VH from entering the intersection. In the case where it is predicted that the lighting color will change to a lighting color that prohibits entry ("Yes"), the ECU 10 enters the process of step S155. On the other hand, in the case where it is not predicted that the lighting color will change to a lighting color that prohibits entry ("No"), the ECU 10 enters the process of step S160.

[0052] In step S155, the ECU 10 changes the target vehicle speed to a third target vehicle speed Vt3 that is higher than the reference target vehicle speed Vt and executes deceleration control, and then returns from this routine. On the other hand, when entering the process of step S160 from step S150, the ECU 10 executes deceleration control using the normal reference target vehicle speed Vt without changing the target vehicle speed, and then returns from this routine. In addition, in the determination process of step S150, when it is predicted that at the time when the own vehicle VH reaches the target position Pt, the lighting color of the traffic signal TL is already a lighting color that prohibits the own vehicle VH from entering the intersection, stop control for stopping the own vehicle VH at the target position Pt can also be implemented.

[0053] As described above, the driving assistance device according to the present embodiment has been described, but the present disclosure is not limited to the above embodiment, and various modifications can be made without departing from the purpose of the present disclosure.

[0054] [Modification Example 1] For example, in the above embodiment, in Figure 4 the step S135, step S145, and step S155 shown, the process of changing the target vehicle speed from the reference target vehicle speed Vt (target vehicle speed change process) is implemented, but in addition to the target vehicle speed change process, a start time change process of changing the deceleration start position Ps (that is, changing the start time of the deceleration control) can also be implemented, or the start time change process can be implemented instead of the target vehicle speed change process.

[0055] Specifically, in step S135 and step S145, the deceleration start position Ps is made closer to the front side of the own vehicle VH to advance the start time. If the start time of the deceleration control is advanced, the time required for the own vehicle VH to reach the target position Pt will become longer, and it is possible to effectively prevent the situation where the deceleration of the own vehicle VH caused by the deceleration control becomes too small compared to the driver's expectation. In addition, in step S155, the deceleration start position Ps is made farther from the own vehicle VH to delay the start time. If the start time of the deceleration control is delayed, the time required for the own vehicle VH to reach the target position Pt will become shorter, and it is possible to effectively prevent the situation where the own vehicle VH cannot pass through the intersection due to the operation of the deceleration assistance.

[0056] [Modified Example 2] Figure 5 It is a schematic diagram for explaining Modified Example 2. In Modified Example 2, there is a straight-through lane L3 for priority vehicles such as buses (including streetcars, etc.) to travel between the own lane L1 and the oncoming lane L2. In such a case, based on the information of other vehicles traveling in the straight-through lane L3, it is only necessary to perform target vehicle speed change processing and / or start time change processing. Specifically, when it is predicted that the own vehicle VH will turn right toward the oncoming lane L2 side and the following vehicle traveling in the straight-through lane L3 will enter the intersection, the target vehicle speed can be changed to the first target vehicle speed Vt1, or the start time can be advanced. In this way, it is possible to effectively prevent the situation where the deceleration of the own vehicle VH caused by the deceleration control becomes too small compared to the driver's expectation.

Claims

1. A driving assistance device, characterized in that: have: an intersection recognition unit that recognizes an intersection located ahead in the traveling direction of the vehicle; a left-right turn prediction unit, which predicts whether the vehicle will turn right or left at the intersection identified by the intersection identification unit; and a deceleration control unit for implementing deceleration control to decelerate the vehicle to a predetermined target vehicle speed before the vehicle reaches a predetermined target position when the left-right turn prediction unit predicts that the vehicle will turn right or left at the intersection, The driving assistance device further includes an external information acquisition unit that acquires information about oncoming vehicles and / or information about pedestrians and / or information about the color of a traffic light at the intersection. The deceleration control unit sets the target vehicle speed and / or a start time of starting the deceleration control based on the information acquired by the external information acquisition unit.

2. The driving assistance device according to claim 1, characterized in that: When the left or right turn prediction unit predicts that the vehicle will turn right or left toward the opposite lane, and the external information acquisition unit obtains information about an oncoming vehicle predicted to enter the intersection within a range of a specified time before or after the vehicle arrives at the target position, the deceleration control unit performs a target vehicle speed change process to lower the target vehicle speed and / or a start time change process to advance the start time.

3. The driving assistance device according to claim 1, characterized in that: When the external information acquisition unit obtains information about pedestrians who are predicted to cross a crosswalk on the route of the vehicle that is turning right or left within a range of a specified time before and after the vehicle arrives at the target position, the deceleration control unit performs a target vehicle speed change process to reduce the target vehicle speed and / or a start time change process to advance the start time.

4. The driving assistance device according to claim 1, wherein: When it is predicted, based on the information on the traffic light color obtained by the external information acquisition unit, that the traffic light color will change to a light color that prohibits the vehicle from entering the intersection within a specified time range before and after the vehicle arrives at the target position, the deceleration control unit performs a target vehicle speed change process to increase the target vehicle speed and / or a start time change process to delay the start time.

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