Driving assistance device

Abstract

Driving assistance device (100) configured to initiate deceleration assistance for a driver's vehicle based on a distance between the driver's vehicle and a deceleration-initiating object in front of the driver's vehicle, wherein the driving assistance device (100) comprises: a start condition determination unit (13) configured to determine whether a preset deceleration assist start condition is met, based on a distance between the driver's vehicle and a first deceleration-triggering object in front of the driver's vehicle; a driving assistance unit (14) configured to initiate deceleration assistance for the driver's vehicle relative to the first deceleration-initiating object when the start condition determination unit (13) determines that the deceleration assistance start condition is met; a termination condition determination unit (15) configured to determine whether a preset deceleration assistance termination condition is met, based on the distance between the driver's vehicle and the first deceleration-triggering object or based on a speed of the driver's vehicle during the deceleration assistance for the driver's vehicle relative to the first deceleration-triggering object; a communication unit (18) configured to issue a deceleration assistance termination message to a driver of the driver's vehicle when the termination condition determination unit (15) determines that the deceleration assistance termination condition is met; a unit for detecting a second deceleration-inducing object (16) configured to determine whether a second deceleration-inducing object is detected in front of the driver's vehicle during the deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object; and a unit for determining a quick resumption condition (17) configured to determine, when the termination condition determination unit (15) determines that the deceleration support termination condition for the first deceleration-triggering object is satisfied, and the second deceleration-triggering object detection unit (16) determines that the second deceleration-triggering object is detected, whether a preset quick resumption condition is satisfied, based on a distance between the driver's vehicle and the second deceleration-triggering object and based on a relative speed between the driver's vehicle and the second deceleration-triggering object, wherein the message unit (18) is configured not to issue the slowdown support termination message when the unit for determining a fast resumption condition (17) determines that the fast resumption condition is met, even in a case where the termination condition determination unit (15) determines that the slowdown support termination condition is met for the first slowdown-triggering object, characterized in that the unit for detecting a second slowdown-inducing object (16) is configured to recognize a type of detected second slowdown-inducing object; and The unit for determining a fast resumption condition (17) is configured to use a different condition than the fast resumption condition, depending on the type of the second slowdown-inducing object.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present invention relates to a driving assistance device. 2. Description of the state of the art

[0002] Japanese Unexamined Patent Application Laid-Open No. JP 2019-93882 A is known as a technical document relating to a pre-assist device. JP 2019-93882 A describes a driving assistance device configured to transition a driver's vehicle to a temporary stop mode in which the driver's vehicle stops when the driver's vehicle enters a predetermined range extending from a temporary stop position. In the driving assistance device, the driver is warned of the termination of the temporary stop mode.

[0003] The document DE 10 2019 107 661 A1 discloses a vehicle control device configured to perform deceleration assistance control of automatically decelerating a host vehicle under a condition that a deceleration target requiring deceleration of the host vehicle exists ahead in the traveling direction of the host vehicle. SUMMARY OF THE INVENTION

[0004] Deceleration assistance is known for decelerating a driver's vehicle under a predetermined condition to avoid a situation in which the driver's vehicle approaches a deceleration-triggering object, such as a vehicle ahead or a stop line, at a high speed. With deceleration assistance, the driver is notified when deceleration assistance is terminated.

[0005] Depending on traffic conditions, the termination of deceleration assistance with respect to a first deceleration-triggering object may be followed by the initiation of deceleration assistance with respect to a second deceleration-triggering object within a short period of time. In this case, the second deceleration assistance could be initiated at a time when the driver, who is notified of the termination of the first deceleration assistance, is in the process of accelerating the driver's vehicle. The notification of the termination of deceleration assistance may be a cause of driver discomfort.

[0006] A first aspect of the present invention relates to a driving assistance device configured to start deceleration assistance for a driver's vehicle based on a distance between the driver's vehicle and a deceleration-inducing object in front of the driver's vehicle. The driving assistance device includes a start condition determining unit, a driving assistance unit, a termination condition determining unit, a notification unit, a second deceleration-inducing object detecting unit, and a quick resumption condition determining unit. The start condition determining unit is configured to determine whether a preset deceleration assistance start condition is satisfied based on a distance between the driver's vehicle and a first deceleration-inducing object in front of the driver's vehicle.The driving assistance unit is configured to start the deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object when the start condition determination unit determines that the deceleration assistance start condition is met. The termination condition determination unit is configured to determine whether a preset deceleration assistance termination condition is met based on the distance between the driver's vehicle and the deceleration-inducing object or based on a speed of the driver's vehicle during the deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object.The notification unit is configured to issue a deceleration assistance termination notification to a driver of the driver's vehicle when the termination condition determination unit determines that the deceleration assistance termination condition is met. The second deceleration-triggering object detection unit is configured to determine whether a second deceleration-triggering object is detected in front of the driver's vehicle relative to the first deceleration-triggering object during deceleration assistance for the driver's vehicle.The quick resumption condition determining unit is configured to determine, when the termination condition determining unit determines that the deceleration assistance termination condition for the first deceleration-inducing object is satisfied and the second deceleration-inducing object detecting unit determines that the second deceleration-inducing object is detected, whether a preset quick resumption condition is satisfied based on a distance between the driver's vehicle and the second deceleration-inducing object and based on a relative speed between the driver's vehicle and the second deceleration-inducing object.The notification unit is configured not to issue the deceleration support termination notification when the quick resumption condition determination unit determines that the quick resumption condition is met, even in a case where the termination condition determination unit determines that the deceleration support termination condition is met for the first deceleration-triggering object. The second deceleration-triggering object detection unit is configured to recognize a type of the detected second deceleration-triggering object, and the quick resumption condition determination unit is configured to use a different condition as the quick resumption condition depending on the type of the second deceleration-triggering object.

[0007] In the first aspect, the issuance of the deceleration support termination notification is not executed when the quick resumption condition determining unit determines that the quick resumption condition is met, even if the termination condition determining unit determines that the deceleration support termination condition is met for the first deceleration-triggering object. According to the first aspect, the issuance of the deceleration support termination notification can be avoided in a situation where the termination of the deceleration support to the first deceleration-triggering object is followed by the start of the deceleration support to the second deceleration-triggering object within a short time.Thus, the driver's discomfort due to the deceleration assistance termination notice can be suppressed compared to a case where the deceleration assistance termination notice is output without considering the start of the deceleration assistance to the second deceleration-inducing object.

[0008] According to the configuration described above, the driver may experience discomfort related to the deceleration assistance termination notification at different times depending on the type of the second deceleration-triggering object (e.g., a preceding vehicle or a stop line). Therefore, the rapid resumption condition is provided depending on the type of the second deceleration-triggering object. Thus, driver discomfort due to the deceleration assistance termination notification can be more appropriately suppressed.

[0009] In the first aspect, the quick resumption condition determining unit may be configured to estimate a remaining time until the deceleration assistance start condition for the second deceleration-inducing object is satisfied based on the distance between the driver's vehicle and the second deceleration-inducing object and based on the relative speed between the driver's vehicle and the second deceleration-inducing object, and determine that the quick resumption condition is satisfied when the remaining time is shorter than a preset time determination threshold.

[0010] According to the configuration described above, a determination is made that a rapid resumption condition is satisfied when the time remaining until the deceleration assistance start condition is satisfied for the second deceleration-triggering object is shorter than the time determination threshold. Therefore, the issuance of the deceleration assistance termination notice can be avoided when the deceleration assistance is resumed in a short time (a time shorter than the time determination threshold) after the termination of the deceleration assistance to the first deceleration-triggering object. Thus, driver discomfort due to the deceleration assistance termination notice can be suppressed.

[0011] In the first aspect, the rapid resumption condition determining unit may be configured to estimate a remaining travel distance until the deceleration assistance start condition for the second deceleration-inducing object is satisfied based on the distance between the driver's vehicle and the second deceleration-inducing object and the relative speed between the driver's vehicle and the second deceleration-inducing object, and determine that the rapid resumption condition is satisfied when the remaining travel distance is shorter than a preset distance determination threshold.

[0012] According to the configuration described above, a determination is made that a quick resumption condition is satisfied when the travel distance remaining until the deceleration assistance start condition for the second deceleration-triggering object is satisfied is shorter than the distance condition threshold. Therefore, the issuance of the deceleration assistance termination notice can be avoided when the deceleration assistance is resumed in a short time (a time during which the vehicle travels a distance shorter than the distance determination threshold) after the termination of the deceleration assistance to the first deceleration-triggering object. Thus, the driver's discomfort due to the deceleration assistance termination notice can be suppressed.

[0013] In the first aspect, the second deceleration-inducing object detection unit may be configured to detect a type of the detected second deceleration-inducing object. The rapid resumption condition determination unit may be configured to estimate a remaining time until the deceleration assistance start condition for the second deceleration-inducing object is met based on the distance between the driver's vehicle and the second deceleration-inducing object and the relative speed between the driver's vehicle and the second deceleration-inducing object, determine that the rapid resumption condition is met when the type of the second deceleration-inducing object is a preceding vehicle and the remaining time is shorter than a preset vehicle time determination threshold, and determineThe condition for rapid resumption is met if the type of the second deceleration-triggering object is a stationary object and if the remaining time is less than a preset timing threshold for a stationary object. The vehicle timing threshold may be less than the timing threshold for the stationary object.

[0014] According to the above-described configuration, when the second deceleration-inducing object is a preceding vehicle that the driver is easily aware of, the driver can predict the next deceleration assistance to the preceding vehicle even if the acceleration assistance termination notification is issued. Therefore, the vehicle timing threshold is set shorter than the timing threshold for the stationary object. Thus, when a certain time remains until the deceleration assistance is resumed, the driver can be notified of the temporary termination of the deceleration assistance (deceleration assistance to the first deceleration-inducing object) while suppressing excessive driver discomfort.

[0015] In the first aspect, the second deceleration-inducing object detection unit may be configured to detect a type of the detected second deceleration-inducing object. The rapid resumption condition determination unit may be configured to estimate a remaining travel distance until the deceleration assistance start condition for the second deceleration-inducing object is met based on the distance between the driver's vehicle and the second deceleration-inducing object and the relative speed between the driver's vehicle and the second deceleration-inducing object, determining that the rapid resumption condition is met when the type of the second deceleration-inducing object is a preceding vehicle and the remaining travel distance is shorter than a preset vehicle distance determination threshold.and determine that the rapid resumption condition is met if the type of the second deceleration-triggering object is a stationary object and the remaining travel distance is shorter than a distance determination threshold for a stationary object. The vehicle distance determination threshold may be smaller than the distance determination threshold for the stationary object.

[0016] According to the above-described configuration, when the second deceleration-inducing object is a preceding vehicle that the driver is easily aware of, the driver can predict the next deceleration assistance to the preceding vehicle even if the deceleration assistance termination notification is issued. Therefore, the vehicle distance determination threshold can be set smaller than the distance determination threshold for the stationary object. Thus, when a certain time remains until the deceleration assistance is resumed, the driver can be notified of a temporary termination of the deceleration assistance (deceleration assistance to the first deceleration-inducing object) while suppressing excessive driver discomfort.

[0017] A second aspect of the present invention relates to a driving assistance device configured to start deceleration assistance for a driver's vehicle based on a distance between the driver's vehicle and a deceleration-inducing object in front of the driver's vehicle. The driving assistance device includes a start condition determining unit, a driving assistance unit, a termination condition determining unit, a notification unit, a second deceleration-inducing object detecting unit, and a quick resumption condition determining unit. The start condition determining unit is configured to determine whether a preset deceleration-inducing start condition is satisfied based on a distance between the driver's vehicle and a first deceleration-inducing object.The first deceleration-triggering object is a traffic signal or a stop line in front of the driver's vehicle. The driving assistance unit is configured to start deceleration assistance for the driver's vehicle relative to the first deceleration-triggering object when the start condition determination unit determines that the deceleration assistance start condition is met. The termination condition determination unit is configured to determine whether a preset deceleration assistance termination condition is met based on a vehicle speed of the driver's vehicle during deceleration assistance for the driver's vehicle relative to the first deceleration-triggering object.The notification unit is configured to issue a deceleration assistance termination notification to a driver of the driver's vehicle when the termination condition determination unit determines that the deceleration assistance termination condition is met. The second deceleration-triggering object detection unit is configured to determine whether a second deceleration-triggering object is detected during deceleration assistance for the driver's vehicle relative to the first deceleration-triggering object. The second deceleration-triggering object is a preceding vehicle traveling in front of the driver's vehicle.The rapid resumption condition determining unit is configured to determine whether a preset rapid resumption condition is met when the termination condition determining unit determines that the deceleration support termination condition is met for the first deceleration-inducing object and when the second deceleration-inducing object detecting unit determines that the second deceleration-inducing object is detected. The rapid resumption condition determining unit is configured to determine that the rapid resumption condition is met when the second deceleration-inducing object is located beyond the stop line that is the first deceleration-inducing object or beyond a stop line associated with the traffic signal that is the first deceleration-inducing object.The notification unit is configured not to output the deceleration support termination notification when the quick resumption condition determining unit determines that the quick resumption condition is satisfied, even in a case where the termination condition determining unit determines that the deceleration support termination condition is satisfied for the first deceleration-triggering object.

[0018] In the second aspect, the issuance of the deceleration support termination notification is not executed when the quick resumption condition determining unit determines that the quick resumption condition is met, even if the termination condition determining unit determines that the deceleration support termination condition is met for the first deceleration-triggering object. According to the second aspect, the issuance of the deceleration support termination notification can be avoided in the situation where the termination of the deceleration support to the first deceleration-triggering object is followed by the start of the deceleration support to the second deceleration-triggering object in a short time.Thus, the driver's discomfort due to the deceleration assistance termination notice can be suppressed, compared with the case where the deceleration assistance termination notice is issued without considering the start of the deceleration assistance against the second deceleration-triggering object.

[0019] A third aspect of the present invention relates to a driving assistance device configured to start deceleration assistance for a driver's vehicle based on a distance between the driver's vehicle and a deceleration-triggering object in front of the driver's vehicle. The driving assistance device includes a controller. The controller is configured to determine whether a preset deceleration-assistance start condition is met based on a distance between the driver's vehicle and a first deceleration-triggering object in front of the driver's vehicle; start deceleration assistance for the driver's vehicle relative to the first deceleration-triggering object if it is determined that the deceleration-assistance start condition is met; determine whether a preset deceleration-assistance end condition is met;Based on the distance between the driver's vehicle and the first deceleration-inducing object or based on a speed of the driver's vehicle during deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object, issue a deceleration-inducing termination notification to a driver of the driver's vehicle when it is determined that the deceleration-inducing termination condition is met, determine whether a second deceleration-inducing object is detected in front of the driver's vehicle during deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object, and determine, when it is determined that the deceleration-inducing termination condition for the first deceleration-inducing object is met and it is determined that the second deceleration-inducing object is detected,Whether a preset rapid resumption condition is met based on a distance between the driver's vehicle and the second deceleration-inducing object and a relative speed between the driver's vehicle and the second deceleration-inducing object. The controller is configured not to issue the deceleration-assist termination notification when the controller determines that the rapid resumption condition is met, even if the controller determines that the deceleration-assist termination condition is met for the first deceleration-inducing object.

[0020] According to the first aspect, the second aspect and the third aspect of the present invention, a driver's discomfort due to the deceleration assistance termination notification can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Features, advantages and technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, in which like reference numerals designate like elements, and in which: Fig. 1 is a block diagram illustrating the configuration of a driving support device according to a first embodiment; Fig. 2A is a plan view illustrating a situation in which a preceding vehicle crosses a stop line; Fig. 2B is a plan view illustrating a situation where the preceding vehicle stops behind the stop line; Fig. 2C is a plan view illustrating a situation where the preceding vehicle is traveling behind the stop line; Fig. 3A is a diagram for describing a situation in which a long time remains from a satisfaction of the deceleration assistance termination condition for a first deceleration-triggering object to a satisfaction of a deceleration assistance start condition for a second deceleration-triggering object; Fig. 3B is a diagram for describing a situation in which a short time remains from the satisfaction of the deceleration assistance termination condition for the first deceleration-triggering object to the satisfaction of the deceleration assistance start condition for the second deceleration-triggering object; Fig. 4A is a flowchart illustrating an example of a slowdown start process for the first slowdown-triggering object; Fig. 4B is a flowchart illustrating an example of a deceleration support termination process; Fig. 5A is a flowchart illustrating an example of a timing threshold setting process; Fig. 5B is a flowchart illustrating an example of a process for determining a fast resume condition using a remaining time; Fig. 6A is a flowchart illustrating an example of a distance determination threshold setting process; Fig. 6B is a flowchart illustrating an example of a process for determining a quick resume condition using a remaining travel distance; and Fig. Figure 7 is a flowchart illustrating another example of the process for determining a rapid resumption condition. DETAILED DESCRIPTION OF EMBODIMENTS

[0022] An embodiment of the present invention will be described below with reference to the drawings. First embodiment

[0023] A driving support device 100, which in Fig. 1 is mounted on a vehicle such as a passenger automobile (driver's vehicle) and assists a driver in driving the driver's vehicle. The driving assistance device 100 performs deceleration assistance for the driver's vehicle under a predetermined condition when a deceleration-triggering object, such as a preceding vehicle or a traffic signal, is detected in front of the driver's vehicle. The deceleration-triggering object is an object that triggers the deceleration assistance. The deceleration-triggering object includes a preceding vehicle, a traffic signal, and a stop line.The deceleration-inducing object may be a pedestrian, a bicycle, or other moving objects in addition to the preceding vehicle, and may be a pedestrian crossing, a lying or fallen object, a construction-related object, a structure, or other stationary objects in addition to the traffic signal and stop line. The deceleration-inducing object could include only a red or yellow traffic signal and could exclude a green traffic signal.

[0024] Deceleration assistance is driving assistance for decelerating the driver's vehicle to a preset target speed. The target speed is not particularly limited and could be 0 km / h or 10 km / h. The target speed could be determined depending on the type of object triggering deceleration. If the deceleration-triggering object is a traffic signal or traffic light, the target speed in the deceleration assistance could be changed depending on the illumination color of the traffic signal or traffic light (illumination color such as green, yellow, or red). The target speed is not limited to the speed of the driver's vehicle and could be a relative speed between the driver's vehicle and the deceleration-triggering object. Configuration of a driving support device of a first embodiment

[0025] The configuration of the driving support device 100 according to the first embodiment will be described with reference to the drawings. As shown in Fig. As shown in Figure 1, the driving assistance device 100 includes a driving assistance electronic control unit (ECU) 10 configured to manage the entire device. The driving assistance ECU 10 is an electronic control unit including a central processing unit (CPU), a read-only memory (ROM), and a random access memory (RAM). For example, the driving assistance ECU 10 implements various functions such that programs stored in the ROM are loaded into the RAM, and the CPU executes the programs loaded into the RAM. The driving assistance ECU 10 may be composed of a variety of electronic units.

[0026] The driving support ECU 10 is connected to an external sensor 1, an internal sensor 2, a human-machine interface (HMI) 3 and an actuator 4.

[0027] The external sensor 1 is a detection device configured to detect conditions around the driver's vehicle. The external sensor 1 includes at least one of a camera and a radar sensor.

[0028] The camera is an imaging device configured to image conditions outside the driver's vehicle. For example, the camera is mounted on the rear side of a windshield of the driver's vehicle to image an area in front of the driver's vehicle. The camera transmits imaging information regarding the conditions outside the driver's vehicle to the driving support ECU 10. The camera may be a monocular camera or a stereo camera.

[0029] The radar sensor is a detection device configured to detect objects around the driver's vehicle using a radio wave (for example, a millimeter wave) or light. Examples of the radar sensor include a millimeter-wave radar and a light detection and ranging (LIDAR) sensor. The radar sensor detects an object by transmitting the radio wave or light to surroundings of the driver's vehicle and receiving the radio wave or light reflected by the object. The radar sensor transmits information about the detected object to the driving support ECU 10. The object includes a guardrail, a building, and other stationary obstacles, as well as a pedestrian, a bicycle, a vehicle other than the driver's vehicle, and other moving obstacles.

[0030] The internal sensor 2 is a detection device configured to detect driving conditions of the driver's vehicle. The internal sensor 2 includes a vehicle speed sensor, an acceleration sensor, and a yaw rate sensor. The vehicle speed sensor is a detection unit configured to detect a speed of the driver's vehicle. Examples of the vehicle speed sensor include a wheel speed sensor provided on each wheel of the driver's vehicle or on a drive shaft that rotates together with the wheel, and configured to detect a rotational speed of the wheel. The vehicle speed sensor transmits information about the detected vehicle speed (wheel speed information) to the driving support ECU 10.

[0031] The acceleration sensor is a detection unit configured to detect acceleration of the driver's vehicle. Examples of the acceleration sensor include a longitudinal acceleration sensor configured to detect longitudinal acceleration of the driver's vehicle and a lateral acceleration sensor configured to detect lateral acceleration of the driver's vehicle. For example, the acceleration sensor transmits acceleration information of the driver's vehicle to the vehicle support ECU 10. The yaw rate sensor is a detection unit configured to detect a yaw rate (rotation angular velocity) about a vertical axis through the center of gravity of the driver's vehicle. Examples of the yaw rate sensor include a gyroscope. The yaw rate sensor transmits information about the detected yaw rate of the driver's vehicle to the driving support ECU 10.

[0032] The HMI 3 is an interface for inputting and outputting information between the driving assistance device 100 and the driver. For example, the HMI 3 includes a display and a speaker. The HMI 3 outputs images on the display and voice and sounds from the speaker in response to a control signal from the driving assistance ECU 10. The display may be a head-up display (HUD).

[0033] The actuator 4 is a device to be used for controlling the driver's vehicle. The actuator 4 includes at least a drive actuator and a brake actuator. The actuator 4 may include a steering actuator. In response to a control signal from the drive assist ECU 10, the drive actuator controls a driving force of the driver's vehicle by controlling the amount of air to be supplied to the engine (throttle opening degree). When the driver's vehicle is a hybrid vehicle, the driving force is controlled by inputting a control signal from a drive assist ECU 10 to a motor serving as a drive source, in addition to the amount of air to be supplied to the engine. When the driver's vehicle is an electric vehicle, the driving force is controlled by inputting a control signal from the drive assist ECU 10 to the motor serving as the drive source.In these cases, the motor, which serves as the drive source, forms the actuator 4.

[0034] In response to a control signal from the drive assist ECU 10, the brake actuator controls a braking force to be applied to each wheel of the driver's vehicle by controlling a braking system. Examples of the braking system include a hydraulic braking system. In response to a control signal from the drive assist ECU 10, the steering actuator controls driving of an assist motor configured to control steering torque in an electric power steering system. Thus, the steering actuator controls the steering torque of the driver's vehicle.

[0035] Next, the functional configuration of the driving support ECU 10 is described. As shown in Fig. 1, the drive support ECU 10 includes a first deceleration-inducing object detection unit 11, a relative condition recognition unit 12, a start condition determination unit 13, a drive support unit 14, a termination condition determination unit 15, a second deceleration-inducing object detection unit 16, a rapid resumption condition determination unit 17, and a notification unit 18. A subset of the functions of the drive support ECU 10, described below, may be performed by a server capable of communicating with the driver's vehicle.

[0036] Based on a detection result of the external sensor 1, the first deceleration-inducing object detection unit 11 determines whether a first deceleration-inducing object is detected in front of the driver's vehicle. The first deceleration-inducing object is first detected in a state where deceleration assistance is not being performed. The deceleration-inducing object includes a second deceleration-inducing object, which will be described later, in addition to the first deceleration-inducing object.

[0037] The first deceleration-inducing object detection unit 11 detects the type of the first deceleration-inducing object (a type such as a preceding vehicle, a traffic signal, or a stop line). For example, the first deceleration-inducing object detection unit 11 detects the deceleration-inducing object and recognizes its type through pattern matching using pre-stored image patterns of individual types based on an image of an area in front of the driver's vehicle captured by the camera. The first deceleration-inducing object detection unit 11 can recognize the type of the deceleration-inducing object based on object information from the radar sensor.

[0038] The relative condition detection unit 12 detects a relative condition between the driver's vehicle and the deceleration-inducing object (first deceleration-inducing object or second deceleration-inducing object). The relative condition includes at least a distance between the driver's vehicle and the deceleration-inducing object (distance in the longitudinal direction or traveling direction of the driver's vehicle). The relative condition may include a relative speed between the driver's vehicle and the deceleration-inducing object.

[0039] For example, the relative condition detection unit 12 detects the relative condition between the driver's vehicle and the deceleration-inducing object based on a detection result from the external sensor 1. When the deceleration-inducing object is a vehicle that can communicate with the driver's vehicle, the relative condition detection unit 12 can detect the relative condition between the driver's vehicle and the deceleration-inducing object using information acquired through inter-vehicle communication. For example, the relative condition detection unit 12 can detect the relative speed between the driver's vehicle and the deceleration-inducing object based on the speed of the driver's vehicle and a speed of the deceleration-inducing object acquired through inter-vehicle communication.

[0040] The start condition determination unit 13 determines whether a deceleration assistance start condition for the deceleration-triggering object is met. The deceleration assistance start condition is a preset condition used to determine whether to start deceleration assistance. The start condition determination unit 13 determines whether the deceleration assistance start condition is met based on at least the distance between the driver's vehicle and the deceleration-triggering object.

[0041] The deceleration assistance start condition is changed depending on the type of deceleration-inducing object. For example, if the type of deceleration-inducing object is a preceding vehicle, the start condition determination unit 13 determines whether the deceleration assistance start condition is satisfied for the preceding vehicle based on the relative condition between the driver's vehicle and the deceleration-inducing object.

[0042] Specifically, the start condition determination unit 13 determines that the preceding vehicle deceleration assistance start condition is satisfied when the speed of the driver's vehicle is higher than the speed of the preceding vehicle (the relative speed is a positive value in an approach direction) and when a time to collision (TTC) between the driver's vehicle and the preceding vehicle is less than a TTC threshold. The TTC is obtained by dividing the distance between the driver's vehicle and the deceleration-inducing object (preceding vehicle) by the relative speed between the driver's vehicle and the deceleration-inducing object (approaching speed). The TTC threshold is a preset value. The threshold to be used in the following description means a threshold that is a preset value.

[0043] The start condition determination unit 13 may determine that the deceleration assistance start condition for the preceding vehicle is satisfied when a time headway (THW) obtained by dividing a distance between the driver's vehicle and the preceding vehicle by the speed of the driver's vehicle is less than a THW threshold, instead of using the TTC. The start condition determination unit 13 may determine that the deceleration assistance start condition for the preceding vehicle is satisfied when the distance between the driver's vehicle and the preceding vehicle is shorter than a distance threshold, instead of using the TTC.

[0044] The start condition determination unit 13 may determine that the preceding vehicle deceleration assistance start condition is met when the speed of the driver's vehicle is higher than the speed of the preceding vehicle, and when a required deceleration of the driver's vehicle is equal to or higher than a deceleration threshold. For example, the required deceleration may be a deceleration required to avoid a situation where the distance between the driver's vehicle and the preceding vehicle is shorter than a threshold determined in advance for each speed. The required deceleration may be a deceleration required to avoid a situation where the distance between the driver's vehicle and the preceding vehicle is shorter than a fixed value.

[0045] When the type of deceleration-triggering object is a stop line (stationary object), the start condition determining unit 13 determines whether the deceleration assistance start condition for the stop line is satisfied based on the speed of the driver's vehicle detected by the internal sensor 2 (vehicle speed sensor) and a relative condition between the driver's vehicle and the stop line.

[0046] Specifically, the start condition determination unit 13 may determine that the deceleration assistance start condition for the stop line is met when the speed of the driver's vehicle is equal to or higher than an assistance start speed threshold, and when a TTC between the driver's vehicle and the stop line is less than a TCC threshold. In this case, the TTC corresponds to a time required for the driver's vehicle to reach the stop line. The start condition determination unit 13 may determine that the deceleration assistance start condition for the stop line is met when a distance between the driver's vehicle and the stop line is shorter than the distance threshold, instead of using the TTC.

[0047] The start condition determination unit 13 can determine that the deceleration assistance start condition for the stop line is met when the speed of the driver's vehicle is equal to or higher than the assistance start speed threshold, and when the required deceleration of the driver's vehicle is equal to or higher than the deceleration threshold. In this case, the required deceleration is a deceleration required, for example, to stop the driver's vehicle at the stop line position. The TTC threshold, the distance threshold, and the deceleration threshold may vary depending on the type of deceleration-triggering object.

[0048] When the type of deceleration-inducing object is a traffic signal, the start condition determining unit 13 determines the deceleration-assistance start condition based on a stop line behind the traffic signal. When the type of deceleration-inducing object is a traffic signal, and the external sensor 1 fails to detect a stop line behind the traffic signal because the stop line has faded, the start condition determining unit 13 determines the deceleration-assistance start condition assuming that the stop line exists at a position a predetermined distance behind the traffic signal. The determination of the deceleration-assistance start condition for the stop line is applicable to the case where the type of deceleration-inducing object is a stationary object.

[0049] The driving support unit 14 starts the deceleration assistance as the driving support for the driver's vehicle when the start condition determination unit 13 determines that the deceleration assistance start condition is met. The driving support unit 14 performs the deceleration assistance for the driver's vehicle by transmitting a control signal to the actuator 4. For example, the driving support unit 14 performs the deceleration assistance to decelerate the driver's vehicle to a preset target speed based on the distance between the driver's vehicle and the deceleration-triggering object and the speed of the driver's vehicle.

[0050] The driving support unit 14 terminates the deceleration support when the termination condition determination unit 15, which will be described later, determines that a deceleration support termination condition is met during execution of the deceleration support. Details of the deceleration support are not limited to those described above, and various known deceleration support methods can be employed.

[0051] The termination condition determination unit 15 determines whether the deceleration assistance termination condition is met during the execution of the deceleration assistance against the deceleration-inducing object. The deceleration assistance termination condition is a preset condition for use in determining whether to terminate the deceleration assistance. The termination condition determination unit 15 determines whether the deceleration assistance termination condition is met based on at least the distance between the driver's vehicle and the deceleration-inducing object. The deceleration assistance termination condition is changed depending on the type of the deceleration-inducing object.

[0052] Specifically, when the deceleration-triggering object is a preceding vehicle, the termination condition determination unit 15 determines whether the deceleration assistance termination condition is satisfied based on a relative condition between the driver's vehicle and the preceding vehicle. The termination condition determination unit determines that the deceleration assistance termination condition for the preceding vehicle is satisfied when a relative speed between the driver's vehicle and the preceding vehicle is less than 0 (relative speed at which the driver's vehicle is moving away from the preceding vehicle), and when a THW between the driver's vehicle and the preceding vehicle is equal to or higher than a termination THW threshold.The termination condition determining unit 15 may determine that the deceleration assistance termination condition for the preceding vehicle is satisfied when a distance between the driver's vehicle and the preceding vehicle is equal to or longer than a termination distance threshold, instead of using the THW.

[0053] The termination condition determination unit 15 may determine whether the deceleration assistance termination condition is met based on the speed of the driver's vehicle. The termination condition determination unit 15 determines that the deceleration assistance termination condition is met when the deceleration-triggering object is a stationary object, such as a stop line, and when the speed of the driver's vehicle reaches the target speed (target speed in deceleration assistance). The termination condition determination unit 15 may determine that the deceleration assistance termination condition is met when the driver's vehicle is decelerated to a degree equal to or higher than a predetermined value.

[0054] The second deceleration-triggering object detection unit 16 determines whether the second deceleration-triggering object is detected during the execution of deceleration assistance relative to the first deceleration-triggering object (the deceleration-triggering object first detected in the state where deceleration assistance is not executed). The second deceleration-triggering object detection unit 16 determines whether the second deceleration-triggering object is detected based on a detection result from the external sensor 1. The second deceleration-triggering object is detected during the execution of deceleration assistance relative to the first deceleration-triggering object.

[0055] The quick resumption condition determining unit 17 determines whether a quick resumption condition is satisfied when the termination condition determining unit 15 determines that the deceleration assistance termination condition for the first deceleration-inducing object is satisfied, and when the second deceleration-inducing object detecting unit 16 determines that the second deceleration-inducing object is detected. The quick resumption condition is a preset condition for determining whether deceleration assistance to the second deceleration-inducing object is started (resumed) in a short time after the termination of deceleration assistance to the first deceleration-inducing object.As the quick resumption condition, the quick resumption condition determining unit 17 uses a condition that varies depending on the type of the second deceleration-inducing object.

[0056] The quick resumption condition determining unit 17 determines whether the quick resumption condition is met based on a distance between the second deceleration-inducing object and the driver's vehicle and a relative speed between the second deceleration-inducing object and the driver's vehicle. Specifically, the quick resumption condition determining unit 17 determines whether the quick resumption condition is met using, for example, a time remaining until the deceleration-assist start condition for the second deceleration-inducing object is met (hereinafter referred to as an "assistance resumption remaining time"). The driver's vehicle maintains a current vehicle speed.The rapid resumption condition determining unit 17 may estimate the assistance resumption remaining time based on the distance between the driver's vehicle and the second deceleration-inducing object and the relative speed between the driver's vehicle and the second deceleration-inducing object.

[0057] For example, when the type of the second deceleration-inducing object is a preceding vehicle and when the speed of the driver's vehicle is higher than the speed of the preceding vehicle, the rapid resumption condition determining unit 17 estimates a time remaining until a TTC between the driver's vehicle and the preceding vehicle is smaller than the TTC threshold as the assist resumption remaining time based on a distance between the driver's vehicle and the preceding vehicle and a relative speed between the preceding vehicle and the driver's vehicle.When the type of the second deceleration-triggering object is a stationary object such as a stop line, and when the speed of the driver's vehicle is equal to or higher than the assistance start speed threshold, the rapid resumption condition determining unit 17 may estimate a time remaining until a TTC between the driver's vehicle and the stop line is less than the TCC threshold as the assistance resumption remaining time based on a distance between the stop line and the driver's vehicle and the speed of the driver's vehicle. The deceleration assistance start condition for use in estimating the assistance resumption remaining time is not limited to the details described above, and various conditions may be employed.

[0058] If the assistance resumption remaining time is shorter than a timing threshold, the rapid resumption condition determining unit 17 determines that the rapid resumption condition is met for the second deceleration-inducing object. The timing threshold may be a fixed value or a threshold that varies depending on the type of the second deceleration-inducing object. For example, the timing threshold may be a vehicle timing threshold if the type of the second deceleration-inducing object is a preceding vehicle, or may be a stationary object timing threshold if the type of the second deceleration-inducing object is a stationary object. The vehicle timing threshold is less than the stationary object timing threshold.If the type of the second deceleration-triggering object is neither the preceding vehicle nor the stationary object (for example, the type is a pedestrian or bicycle), a general timing threshold may be used. The general timing threshold may be equal to or less than the vehicle timing threshold.

[0059] Specifically, the quick resumption condition determining unit 17 determines that the quick resumption condition is satisfied for the second deceleration-inducing object when the type of the second deceleration-inducing object is a preceding vehicle, and when the assist resumption remaining time is shorter than the vehicle time determination threshold. The quick resumption condition determining unit 17 does not determine that the quick resumption condition is satisfied for the second deceleration-inducing object when the type of the second deceleration-inducing object is a preceding vehicle, and when the assist resumption remaining time is equal to or longer than the vehicle time determination threshold.The rapid resumption condition determining unit 17 determines that the rapid resumption condition is satisfied for the second deceleration-triggering object when the type of the second deceleration-triggering object is a stationary object, and when the assist resumption remaining time is shorter than the time determination threshold for the stationary object. The rapid resumption condition determining unit 17 does not determine that the rapid resumption condition is satisfied for the second deceleration-triggering object when the type of the deceleration-triggering object is the stationary object, and when the assist resumption remaining time is equal to or longer than the time determination threshold for the stationary object.

[0060] The rapid resumption condition determining unit 17 may determine whether the rapid resumption condition is satisfied using a travel distance remaining until the deceleration assistance start condition for the second deceleration-inducing object is satisfied (hereinafter referred to as an "assistance resumption remaining travel distance"). The rapid resumption condition determining unit 17 may estimate the assist resumption remaining travel distance based on the distance between the second deceleration-inducing object and the driver's vehicle and the relative speed between the second deceleration-inducing object and the driver's vehicle (or the speed of the driver's vehicle).

[0061] For example, when the type of the second deceleration-inducing object is a preceding vehicle and when the speed of the driver's vehicle is higher than the speed of the preceding vehicle, the rapid resumption condition determining unit 17 estimates a traveling distance remaining until a TTC between the driver's vehicle and the preceding vehicle is smaller than the TTC threshold as the assist resumption remaining traveling distance based on a distance between the preceding vehicle and the driver's vehicle and a relative speed between the second deceleration-inducing object and the driver's vehicle.When the type of the second deceleration-triggering object is a stationary object, such as a stop line, and the speed of the driver's vehicle is equal to or higher than the assistance start speed threshold, the rapid resumption condition determining unit 17 may estimate a travel distance remaining until a TTC between the driver's vehicle and the stop line is less than the TCC threshold as the assistance resumption remaining travel distance based on a distance between the stop line and the driver's vehicle and the speed of the driver's vehicle. The deceleration assistance start condition for use in estimating the assistance resumption remaining travel distance is not limited to the details described above, and various conditions may be employed.

[0062] If the assist resumption remaining travel distance is shorter than a travel distance determination threshold, the rapid resumption condition determination unit 17 determines that the rapid resumption condition is met for the second deceleration-triggering object. The travel distance determination threshold may be a fixed value or a threshold that varies depending on the type of the second deceleration-triggering object. For example, the travel distance determination threshold may be a vehicle travel distance determination threshold when the type of the second deceleration-triggering object is a preceding vehicle, and may be a stationary object travel distance determination threshold when the type of the second deceleration-triggering object is a stationary object.The vehicle travel distance determination threshold is less than the stationary object travel distance determination threshold. If the type of the second deceleration-triggering object is neither a preceding vehicle nor a stationary object (for example, the type is a pedestrian or a bicycle), a general travel distance determination threshold may be used. The general travel distance determination threshold may be equal to the vehicle travel distance determination threshold or may be less than the vehicle travel distance determination threshold.

[0063] When the type of the first deceleration-inducing object is a stop line and the type of the second deceleration-inducing object is a preceding vehicle, the rapid resumption condition determining unit 17 may determine whether the rapid resumption condition is met based on a distance between the driver's vehicle and the stop line (first deceleration-inducing object) and a distance between the driver's vehicle and the preceding vehicle (second deceleration-inducing object). Specifically, the rapid resumption condition determining unit 17 may determine that the rapid resumption condition is met when the preceding vehicle, which is the second deceleration-inducing object, is behind the stop line, which is the first deceleration-inducing object.The rapid resumption condition determining unit 17 may determine that the rapid resumption condition is met when the type of the first deceleration-inducing object is a traffic signal, when the type of the second deceleration-inducing object is a preceding vehicle, and when the preceding vehicle, which is the second deceleration-inducing object, is located behind a stop line associated with the traffic signal.

[0064] If the type of the first deceleration-inducing object is a traffic signal, if the type of the second deceleration-inducing object is a preceding vehicle, and if the preceding vehicle decelerates behind a stop line while traveling, the rapid resumption condition determining unit 17 may estimate a stop position of the preceding vehicle. The rapid resumption condition determining unit 17 may determine that the rapid resumption condition is satisfied if the rapid resumption condition determining unit 17 estimates that the preceding vehicle, which is the second deceleration-inducing object, stops behind the stop line associated with the traffic signal.

[0065] The notification unit 18 informs the driver of the driver's vehicle about the driving assistance. The notification unit 18 transmits a control signal to the HMI 3 to output a notification including at least one of an image displayed on the display and a sound output from the speaker. When the start condition determination unit 13 determines that the deceleration assistance start condition is met, the notification unit 18 can output a deceleration assistance start notification. The deceleration assistance start notification is output to inform the driver of the start of the deceleration assistance. Details of the deceleration assistance start notification are not particularly limited.

[0066] When the termination condition determination unit 15 determines that the deceleration assistance termination condition is met, the notification unit 18 outputs a deceleration assistance termination notification to the driver of the vehicle. The deceleration assistance termination condition is output to notify the driver of the termination of the deceleration assistance. Details of the deceleration assistance termination notification are not particularly limited. The deceleration assistance termination notification may be output through image output, audio output (including output of only mechanical sound), or both image output and audio output.

[0067] The notification unit 18 avoids issuing the deceleration support termination notification when the termination condition determination unit 15 determines that the deceleration support termination condition is met, but when the quick resumption condition determination unit 17 determines that the quick resumption condition is met. If the deceleration support termination notification has already been started, the notification unit 18 may continue the deceleration support termination notification.

[0068] Next, specific examples of the driving support device 100 will be described with reference to the drawings. Fig. Figure 2A is a plan view illustrating a situation where a preceding vehicle crosses a stop line. Fig. 2A represents a vehicle of a driver M, a red traffic signal C (stop), a stop line PL and a preceding vehicle N. The stop line PL is linked to the traffic signal C.

[0069] In the Fig. In the situation illustrated in FIG. 2A, the preceding vehicle N crosses the stop line PL. The driving assistance device 100 detects the preceding vehicle N as the second deceleration-inducing object after starting the deceleration assistance by detecting the red traffic signal C as the first deceleration-inducing object. In this case, a distance between the driver M's vehicle and the preceding vehicle N (distance to the preceding vehicle) is longer than a distance between the driver M's vehicle and the stop line PL (distance to the stop line). Since the rapid resumption condition for the preceding vehicle N (second deceleration-inducing object) is not satisfied, the driving assistance device 100 outputs the deceleration assistance termination notification to the driver when the deceleration assistance termination condition for the traffic signal C (stop line PL) is satisfied.The deceleration support termination notice is not issued when the rapid resumption condition is met, for example, because the preceding vehicle N is traveling at a very slow speed immediately after passing the stop line PL.

[0070] Fig. 2B is a plan view illustrating a situation in which the preceding vehicle N is stopped behind the stop line PL. The driving assistance device 100 detects the preceding vehicle N as the second deceleration-triggering object after the deceleration assistance is started by detecting the red traffic signal C as the first deceleration-triggering object. Fig. In the situation illustrated in Figure 2B, a relationship of "distance to the preceding vehicle < distance to the stop line" applies, and the preceding vehicle N stops. In this case, the rapid resumption condition determining unit 17 determines that the rapid resumption condition is satisfied because the preceding vehicle N, which is the second deceleration-triggering object, is located behind the stop line PL associated with the traffic signal C, which is the first deceleration-triggering object.

[0071] Even if the deceleration assistance termination condition is satisfied for the traffic signal C, which is the first deceleration-inducing object, the driving assistance device 100 can avoid outputting the deceleration assistance termination notification in a state where the stopped preceding vehicle N (second deceleration-inducing object) exists at a short distance and is easily known to the driver of the preceding vehicle N. When the stop line PL cannot be detected, the driving assistance device 100 can detect a distance to an assumed stop line, assuming that the stop line PL exists at a position a predetermined distance behind the traffic signal C.

[0072] Fig. 2C is a plan view showing a situation in which the preceding vehicle N is traveling (slowing down) behind the stop line PL. In the Fig. 2C, a relationship of “distance to the preceding vehicle < distance to the stop line” holds, and the preceding vehicle N decelerates. In this case, the rapid resumption condition determining unit 17 estimates a stop position of the preceding vehicle N based on the distance to the preceding vehicle and a speed or deceleration of the preceding vehicle N. The rapid resumption condition determining unit 17 determines that the rapid resumption condition is satisfied when the rapid resumption condition determining unit 17 estimates that the preceding vehicle, which is the second deceleration-triggering object, stops beyond the stop line associated with the traffic signal.Even if the deceleration assistance termination condition is satisfied for the traffic signal C, which is the first deceleration-inducing object, the driving assistance device 100 can avoid outputting the deceleration assistance termination notification in a state where the preceding vehicle N (second deceleration-inducing object) travels in front of the driver M's vehicle and is easily aware of the driver of the preceding vehicle N.

[0073] Fig. 3A is a diagram for describing a situation in which a long time remains from the satisfaction of the deceleration support termination condition for the first deceleration-triggering object to the satisfaction of the deceleration support start condition for the second deceleration-triggering object. Fig. 3A illustrates a first deceleration assistance termination time t1e when the deceleration assistance termination condition for the first deceleration-inducing object is satisfied, a second deceleration assistance start time t2s when the deceleration assistance start condition for the second deceleration-inducing object is satisfied, and an assistance resumption time Ta between the first deceleration assistance termination time t1e and the second deceleration assistance start time t2s.

[0074] In the Fig. In the situation illustrated in FIG. 3A, the assistance resumption time Ta is long, and the rapid resumption condition for the second deceleration assistance is not met at the first deceleration assistance termination time t1e. Therefore, the deceleration assistance termination notification is issued to notify the driver of the termination of the deceleration assistance to the first deceleration-inducing object. In this case, the notification unit 18 issues the deceleration assistance termination notification from the first deceleration assistance termination time t1e. The deceleration assistance termination notification may be terminated before the second deceleration assistance start time t2s.

[0075] Fig. 3B is a diagram for describing a situation in which a short time remains from the satisfaction of the deceleration support termination condition for the first deceleration-triggering object to the satisfaction of the deceleration support start condition for the second deceleration-triggering object. Fig. 3B illustrates an assistance resumption time Tb between the first deceleration assistance termination time t1e and the second deceleration assistance start time t2s. The assistance resumption time Tb is shorter than the assistance resumption time Ta in Fig. 3A.

[0076] In the Fig. In the situation illustrated in FIG. 3B, the assistance resumption time Tb is short, and the rapid resumption condition for the second deceleration assistance is met at the first deceleration assistance termination time t1e. Therefore, the deceleration assistance termination notice for the first deceleration-inducing object is not output. Thus, the driving assistance device 100 can suppress driver discomfort due to the deceleration assistance termination notice output when the termination of the deceleration assistance to the first deceleration-inducing object is followed by the resumption of the deceleration assistance to the second deceleration-inducing object in a short time. Processes in the driving support device of the first embodiment

[0077] Next, processes in the driving support device 100 of the first embodiment will be described with reference to the drawings. Fig. Figure 4A is a flowchart illustrating an example of a deceleration start process for the first deceleration-triggering object. The deceleration start process is performed during execution of the drive assistance function.

[0078] As in Fig. As shown in FIG. 4A, the driving support ECU 10 of the driving support device 100 determines in S10 whether the first deceleration-inducing object detecting unit 11 detects the first deceleration-inducing object. The first deceleration-inducing object detecting unit 11 detects the first deceleration-inducing object in front of the driver's vehicle based on a detection result of the external sensor 1. If the driving support ECU 10 determines that the first deceleration-inducing object is detected (S10: YES), the driving support ECU 10 proceeds to S12. If the driving support ECU 10 does not determine that the first deceleration-inducing object is detected (S10: NO), the driving support ECU 10 ends the current process. After a lapse of a predetermined time, the driving support ECU 10 repeats the process of S10.

[0079] In S12, the driving support ECU 10 causes the first deceleration-inducing object detection unit 11 to detect the type of the first deceleration-inducing object. For example, the first deceleration-inducing object detection unit 11 detects the type of the deceleration-inducing object through pattern matching using pre-stored image patterns of individual types based on an image around an area in front of the driver's vehicle captured by the camera. The relative condition detection unit 12 detects a relative condition between the driver's vehicle and the deceleration-inducing object (first deceleration-inducing object or second deceleration-inducing object).

[0080] In S14, the driving support ECU 10 causes the start condition determination unit 13 to determine whether the deceleration assistance start condition for the first deceleration-inducing object is satisfied. For example, if the type of deceleration-inducing object is a preceding vehicle, the start condition determination unit 13 determines whether the deceleration assistance start condition for the preceding vehicle is satisfied based on the relative condition between the driver's vehicle and the deceleration-inducing object. If a determination is made that the deceleration assistance start condition is satisfied (S14: YES), the driving support ECU 10 proceeds to S16. If a determination is not made that the deceleration assistance start condition is satisfied (S14: NO), the driving support ECU 10 ends the current process.After a lapse of a predetermined time, the driving support ECU 10 repeats the process of S10.

[0081] In S16, the driving assistance ECU 10 causes the driving assistance unit 14 to perform deceleration assistance against the first deceleration-triggering object. The driving assistance unit 14 performs deceleration assistance for the driver's vehicle by transmitting a control signal to the actuator 4.

[0082] Fig. Figure 4B is a flowchart illustrating an example of a slowdown support termination process. The slowdown support termination process is performed during the execution of the slowdown support against the first slowdown-triggering object.

[0083] As in Fig. As shown in FIG. 4B, in S20, the driving support ECU 10 causes the termination condition determination unit 15 to determine whether the deceleration support termination condition for the first deceleration-inducing object is satisfied. For example, when the deceleration-inducing object is a preceding vehicle, the termination condition determination unit 15 determines whether the deceleration support termination condition is satisfied based on a relative condition between the driver's vehicle and the preceding vehicle. If a determination is made that the deceleration support termination condition for the first deceleration-inducing object is satisfied (S20: YES), the driving support ECU 10 proceeds to S22.If the determination is not made that the deceleration assistance termination condition is met for the first deceleration-triggering object (S20: NO), the drive assistance ECU 10 terminates the current process. After a predetermined time has elapsed, the drive assistance ECU 10 repeats the process of S20.

[0084] In S22, the driving support ECU 10 determines whether the second deceleration-inducing object detection unit 16 detects the second deceleration-inducing object. The second deceleration-inducing object detection unit 16 determines whether the second deceleration-inducing object is detected based on a detection result from the external sensor 1. If the driving support ECU 10 determines that the second deceleration-inducing object is detected (S22: YES), the driving support ECU 10 proceeds to S24. If the driving support ECU 10 does not determine that the second deceleration-inducing object is detected (S22: NO), the driving support ECU 10 proceeds to S28.

[0085] In S24, the drive support ECU 10 causes the second deceleration-inducing object detection unit 16 to detect the type of the second deceleration-inducing object. For example, the second deceleration-inducing object detection unit 16 detects the type of the second deceleration-inducing object similarly to the first deceleration-inducing object detection unit 11.

[0086] In S26, the driving support ECU 10 causes the quick resumption condition determining unit 17 to determine whether the quick resumption condition is satisfied depending on the type of the second deceleration-inducing object. For example, the quick resumption condition determining unit 17 determines whether the quick resumption condition is satisfied using a time or a travel distance remaining until the deceleration-assist start condition for the second deceleration-inducing object is satisfied. If a determination is made that the quick resumption condition is satisfied (S26: YES), the driving support ECU 10 ends the current process. In this case, the driving support ECU 10 avoids outputting the deceleration-assist termination notification regarding the first deceleration-inducing object.If no determination is made that the quick resumption condition is satisfied (S26: NO), the drive support ECU 10 proceeds to S28.

[0087] In S28, the driving support ECU 10 causes the notification unit 18 to output the deceleration support termination notification. The notification unit 18 transmits a control signal to the HMI 3 to output the deceleration support termination notification through at least one of an image output on the display and an audio output from the speaker.

[0088] Next, a description will be given of a specific example of the determination regarding the quick resumption condition by the quick resumption condition determination unit 17 (S26). First, a description will be given of the setting of the time determination threshold for use in the determination of the quick resumption condition using a remaining time.

[0089] Fig. 5A is a flowchart illustrating an example of the timing threshold setting process. As shown in Fig. As shown in Figure 5A, in S40, the drive support ECU 10 causes the second deceleration-inducing object detecting unit 16 to determine whether the type of the second deceleration-inducing object is a preceding vehicle. If a determination is made that the type of the second deceleration-inducing object is a preceding vehicle (S40: YES), the drive support ECU 10 proceeds to S42. If no determination is made that the type of the second deceleration-inducing object is a preceding vehicle (S40: NO), the drive support ECU 10 proceeds to S44.

[0090] In S42, the driving support ECU 10 causes the quick resumption condition determining unit 17 to set the vehicle time determination threshold as the time determination threshold for use in the quick resumption condition.

[0091] In S44, the driving support ECU 10 causes the second deceleration-triggering object detection unit 16 to determine whether the type of the second deceleration-triggering object is a stationary object. If a determination is made that the type of the second deceleration-triggering object is a stationary object (S44: YES), the driving support ECU 10 proceeds to S46. If no determination is made that the type of the second deceleration-triggering object is a stationary object (S44: NO), the driving support ECU 10 proceeds to S48.

[0092] In S46, the driving support ECU 10 causes the quick resumption condition determining unit 17 to set the stationary object timing threshold as the timing threshold for use in the quick resumption condition. In S48, the driving support ECU 10 causes the quick resumption condition determining unit 17 to set the general timing threshold as the timing threshold for use in the quick resumption condition.

[0093] Fig. Figure 5B is a flowchart illustrating an example of a process for determining a fast resume condition using a remaining time. As shown in Fig. 5B, in S50, the driving support ECU 10 causes the quick resumption condition determining unit 17 to determine whether the time remaining until the deceleration assistance start condition for the second deceleration-triggering object is satisfied (assistance resumption remaining time) is shorter than the time determination threshold (time determination threshold set by the time determination threshold setting process).

[0094] If a determination is made that the assist resumption remaining time is shorter than the time determination threshold (S50: YES), the driving assistance ECU 10 proceeds to S52. If no determination is made that the assist resumption remaining time is shorter than the time determination threshold (S50: NO), the driving assistance ECU 10 ends the current process.

[0095] In S52, the driving support ECU 10 causes the quick resumption condition determining unit 17 to determine that the quick resumption condition is satisfied.

[0096] Next, a description will be given of setting the distance determination threshold for use in the determination on the quick resumption condition using a remaining travel distance. Fig. 6A is a flowchart illustrating an example of a distance determination threshold setting process.

[0097] As in Fig. As shown in Fig. 6A, in S60, the drive support ECU 10 causes the second deceleration-inducing object detecting unit 16 to determine whether the type of the second deceleration-inducing object is a preceding vehicle. If a determination is made that the type of the second deceleration-inducing object is a preceding vehicle (S60: YES), the drive support ECU 10 proceeds to S62. If no determination is made that the type of the second deceleration-inducing object is a preceding vehicle (S60: NO), the drive support ECU 10 proceeds to S64.

[0098] In S62, the driving support ECU 10 causes the quick resumption condition determining unit 17 to set the vehicle distance determination threshold as the distance determination threshold for use in the quick resumption condition.

[0099] In S64, the driving support ECU 10 causes the second deceleration-triggering object detection unit 16 to determine whether the type of the second deceleration-triggering object is a stationary object. If a determination is made that the type of the second deceleration-triggering object is a stationary object (S64: YES), the driving support ECU 10 proceeds to S66. If no determination is made that the type of the second deceleration-triggering object is a stationary object (S64: NO), the driving support ECU 10 proceeds to S68.

[0100] In S66, the driving support ECU 10 causes the quick resumption condition determining unit 16 to set the stationary object distance determination threshold as the distance determination threshold for use in the quick resumption condition. In S68, the driving support ECU 10 causes the quick resumption condition determining unit 17 to set the general distance determination threshold as the distance determination threshold for use in the quick resumption condition.

[0101] Fig. Figure 6B is a flowchart illustrating an example of a process for determining a fast resumption condition using a remaining travel distance. As shown in Fig. 6B, in S70, the driving support ECU 10 causes the rapid resumption condition determining unit 17 to determine whether a traveling distance remaining until the deceleration assistance start condition for the second deceleration-triggering object is satisfied (assistance resumption remaining traveling distance) is shorter than the distance determination threshold (distance determination threshold set by the distance determination threshold setting process).

[0102] If a determination is made that the assistance resumption remaining travel distance is shorter than the distance determination threshold (S70: YES), the driving assistance ECU 10 proceeds to S72. If no determination is made that the assistance resumption remaining travel distance is shorter than the distance determination threshold (S70: NO), the driving assistance ECU 10 ends the current process.

[0103] In S72, the driving support ECU 10 causes the quick resumption condition determining unit 17 to determine that the quick resumption condition is satisfied.

[0104] Fig. Figure 7 is a flowchart illustrating another example of the process for determining a fast resumption condition. The process for determining a fast resumption condition shown in Fig. 7 may be used when the type of first deceleration-inducing object is a stop line or traffic signal and when the type of second deceleration-inducing object is a preceding vehicle.

[0105] As in Fig.As shown in Fig. 7, in S80, the driving support ECU 10 causes the rapid resumption condition determining unit 17 to determine whether the preceding vehicle, which is the second deceleration-inducing object, is located behind the stop line, which is the first deceleration-inducing object, or behind a stop line associated with the traffic signal, which is the first deceleration-inducing object. When the preceding vehicle is decelerating, an estimated stop position of the preceding vehicle is used. If a determination is made that the preceding vehicle is located behind the stop line (S80: YES), the driving support ECU 10 proceeds to S82. If no determination is made that the preceding vehicle is located behind the stop line (S80: NO), the driving support ECU 10 ends the current process.

[0106] In S82, the driving support ECU 10 causes the quick resumption condition determining unit 17 to determine that the quick resumption condition is satisfied.

[0107] The driving assistance device 100 according to the first embodiment does not output the deceleration assistance termination notification when the rapid resumption condition determining unit determines that the rapid resumption condition is satisfied, even when the termination condition determining unit determines that the deceleration assistance termination condition is satisfied for the first deceleration-inducing object. Therefore, the driving assistance device 100 can avoid outputting the deceleration assistance termination notification in a situation where the termination of the deceleration assistance to the first deceleration-inducing object is followed by the start of the deceleration assistance to the second deceleration-inducing object within a short time.Thus, the driver's discomfort due to the deceleration assistance termination notice can be suppressed, compared with a case where the deceleration assistance termination notice is issued without considering the start of the deceleration assistance against the second deceleration-triggering object.

[0108] According to the driving assistance device 100, the driver may experience discomfort about the deceleration assistance termination notification at different times depending on the type of the second deceleration-triggering object (e.g., a preceding vehicle or a stop line). Therefore, the rapid resumption condition is provided depending on the type of the second deceleration-triggering object. Thus, driver discomfort due to the deceleration assistance termination notification can be more appropriately suppressed.

[0109] The driving assistance device 100 determines that the rapid resumption condition is satisfied when a time remaining until the deceleration assistance start condition is satisfied for the second deceleration-triggering object is shorter than the time determination threshold. Therefore, the driving assistance device 100 can avoid issuing the deceleration assistance termination notification when the deceleration assistance is resumed in a short time (a time shorter than the time determination threshold) after the termination of the deceleration assistance to the first deceleration-triggering object. Thus, the driver's discomfort due to the deceleration assistance termination notification can be suppressed.According to the driving assistance device 100, when the second deceleration-inducing object is a preceding vehicle that the driver is easily aware of, the driver can predict the next deceleration assistance against the preceding vehicle even if the deceleration assistance termination notification is issued. Therefore, the vehicle timing threshold is set shorter than the timing threshold for the stationary object. Thus, when a certain time remains until the deceleration assistance is resumed, the driver can be notified of a temporary termination of the deceleration assistance (deceleration assistance against the first deceleration-inducing object) while suppressing excessive driver discomfort.

[0110] The driving assistance device 100 determines that the rapid resumption condition is satisfied when a travel distance remaining until the deceleration assistance start condition for the second deceleration-triggering object is satisfied is shorter than the distance determination threshold. Therefore, the driving assistance device 100 can avoid issuing the deceleration assistance termination notice when the deceleration assistance is resumed within a short time (time during which the vehicle travels a distance shorter than the distance determination threshold) after the termination of the deceleration assistance from the first deceleration-triggering object. Thus, the driver's discomfort due to the deceleration assistance termination notice can be suppressed.

[0111] Furthermore, the driving assistance device determines that the quick resumption condition is met again when the type of the second deceleration-triggering object is a stationary object, and when the travel distance remaining until the deceleration-triggering start condition for the second deceleration-triggering object is met is shorter than the distance determination threshold for the stationary object, which is greater than the vehicle distance determination threshold. The driving assistance device reduces the output of the deceleration-assistance termination notification when the second deceleration-triggering object is a stationary object and the driver is simply aware of the stationary object and simply predicts the next deceleration assistance against the stationary object. Thus, the driver's discomfort due to the deceleration-assistance termination notification can be more appropriately suppressed.

[0112] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. The present invention can be implemented not only in the above-described embodiment, but also in various embodiments, to which various changes and modifications can be made based on the knowledge of those skilled in the art.

[0113] The driving assistance device 100 does not necessarily need to recognize the types of the first deceleration-triggering object and the second deceleration-triggering object. Furthermore, the deceleration-assistance start condition, the deceleration-assistance end condition, and the rapid resumption condition may be fixed conditions instead of conditions that vary depending on the types.

[0114] The rapid resumption condition determination unit 17 may, for example, use a pedestrian time determination threshold or a bicycle time determination threshold instead of the general time determination threshold. The rapid resumption condition determination unit 17 does not need to change the threshold depending on the type. The rapid resumption condition determination unit 17 may make the determination of the rapid resumption condition using a fixed time determination threshold or a fixed distance determination threshold regardless of the type.

[0115] A driving assistance device (100) is configured to determine whether a preset deceleration assistance start condition is met, start deceleration assistance for a driver's vehicle relative to a first deceleration-inducing object, determine whether a preset deceleration assistance termination condition is met, issue a deceleration assistance termination notification to a driver of the driver's vehicle, determine whether a second deceleration-inducing object is detected ahead of the driver's vehicle, and determine whether a preset rapid resumption condition is met.The driving assistance device (100) is configured not to output the deceleration assistance termination notification when the driving assistance device (100) determines that the rapid resumption condition is satisfied, even in a case where the driving assistance device (100) determines that the deceleration assistance termination condition is satisfied for the first deceleration-triggering object.

Claims

[1] A driving assistance device (100) configured to start deceleration assistance for a driver's vehicle based on a distance between the driver's vehicle and a deceleration-triggering object in front of the driver's vehicle, the driving assistance device (100) comprising: a start condition determining unit (13) configured to determine whether a preset deceleration assistance start condition is satisfied based on a distance between the driver's vehicle and a first deceleration-triggering object in front of the driver's vehicle; a driving assistance unit (14) configured to start the deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object when the start condition determining unit (13) determines that the deceleration assistance start condition is satisfied; a termination condition determination unit (15) configured to determine whether a preset deceleration assistance termination condition is satisfied based on the distance between the driver's vehicle and the first deceleration-inducing object or based on a speed of the driver's vehicle during deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object; a notification unit (18) configured to issue a deceleration assistance termination notification to a driver of the driver's vehicle when the termination condition determination unit (15) determines that the deceleration assistance termination condition is satisfied; a second deceleration-triggering object detection unit (16) configured to determine whether a second deceleration-triggering object is detected in front of the driver's vehicle during deceleration assistance for the driver's vehicle relative to the first deceleration-triggering object; and a quick resumption condition determination unit (17) configured to determine, when the termination condition determination unit (15) determines that the deceleration assistance termination condition for the first deceleration-inducing object is satisfied, and the second deceleration-inducing object detection unit (16) determines that the second deceleration-inducing object is detected, whether a preset quick resumption condition is satisfied based on a distance between the driver's vehicle and the second deceleration-inducing object and based on a relative speed between the driver's vehicle and the second deceleration-inducing object, wherein the notification unit (18) is configured not to issue the deceleration support termination notification when the rapid resumption condition determining unit (17) determines that the rapid resumption condition is satisfied, even in a case where the termination condition determining unit (15) determines that the deceleration support termination condition is satisfied for the first deceleration-triggering object, characterized by , that the second deceleration-triggering object detection unit (16) is configured to detect a type of the detected second deceleration-triggering object; and the quick resumption condition determining unit (17) is configured to use a different condition as the quick resumption condition depending on the type of the second deceleration-triggering object. [2] The driving support device (100) according to claim 1, wherein the quick resumption condition determining unit (17) is configured to: estimate a remaining time until the deceleration assistance start condition for the second deceleration-inducing object is met based on the distance between the driver's vehicle and the second deceleration-inducing object and based on the relative speed between the driver's vehicle and the second deceleration-inducing object; and to determine that the fast resumption condition is met when the remaining time is less than a preset timing threshold. [3] The driving support device (100) according to claim 1, wherein the quick resumption condition determining unit (17) is configured to: estimate a remaining travel distance until the deceleration assistance start condition for the second deceleration-inducing object is met, based on the distance between the driver's vehicle and the second deceleration-inducing object and based on the relative speed between the driver's vehicle and the second deceleration-inducing object; and to determine that the quick resumption condition is met when the remaining travel distance is shorter than a preset distance determination threshold. [4] Driving assistance device (100) according to claim 1, wherein: the second deceleration-triggering object detection unit (16) is configured to detect a type of the detected second deceleration-triggering object; the rapid resumption condition determination unit (17) is configured to estimate a remaining time until the deceleration assistance start condition for the second deceleration-triggering object is met, based on the distance between the driver's vehicle and the second deceleration-triggering object and based on the relative speed between the driver's vehicle and the second deceleration-triggering object, to determine that the rapid resumption condition is met if the type of the second deceleration-triggering object is a preceding vehicle and the remaining time is less than a preset vehicle time determination threshold, and to determine that the rapid resumption condition is met if the type of the second deceleration-triggering object is a stationary object and the remaining time is less than a preset timing threshold for the stationary object; and the vehicle timing threshold is smaller than the stationary object timing threshold. [5] Driving assistance device (100) according to claim 1, wherein: the second deceleration-triggering object detection unit (16) is configured to detect a type of the detected second deceleration-triggering object; the rapid resumption condition determination unit (17) is configured to estimate a remaining travel distance until the deceleration assistance start condition for the second deceleration-triggering object is met, based on the distance between the driver's vehicle and the second deceleration-triggering object and based on the relative speed between the driver's vehicle and the second deceleration-triggering object, to determine that the rapid resumption condition is met if the type of the second deceleration-triggering object is a preceding vehicle and the remaining travel distance is shorter than a preset vehicle distance determination threshold, and to determine that the rapid resumption condition is met if the type of the second deceleration-triggering object is a stationary object and the remaining travel distance is shorter than a preset distance determination threshold for the stationary object; and the vehicle distance determination threshold is smaller than the distance determination threshold for the stationary object. [6] A driving assistance device (100) configured to start deceleration assistance for a driver's vehicle based on a distance between the driver's vehicle and a deceleration-triggering object in front of the driver's vehicle, the driving assistance device (100) comprising: a start condition determination unit (13) configured to determine whether a preset deceleration assistance start condition is met based on a distance between the driver's vehicle and a first deceleration-triggering object, wherein the first deceleration-triggering object is a traffic signal or a stop line in front of the driver's vehicle; a driving assistance unit (14) configured to start the deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object when the start condition determining unit (13) determines that the deceleration assistance start condition is satisfied; a termination condition determination unit (15) configured to determine whether a preset deceleration assistance termination condition is satisfied based on a vehicle speed of the driver's vehicle during the deceleration assistance for the driver's vehicle relative to the first deceleration-triggering object; a notification unit (18) configured to issue a deceleration assistance termination notification to a driver of the driver's vehicle when the termination condition determination unit (15) determines that the deceleration assistance termination condition is satisfied; a second deceleration-inducing object detection unit (16) configured to determine whether a second deceleration-inducing object is detected during deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object, wherein the second deceleration-inducing object is a preceding vehicle traveling in front of the driver's vehicle; and a quick resumption condition determination unit (17) configured to determine whether a quick resumption condition is satisfied when the termination condition determination unit (15) determines that the deceleration support termination condition for the first deceleration-triggering object is satisfied, and the second deceleration-triggering object detection unit (16) determines that the second deceleration-triggering object is detected, wherein the rapid resumption condition determining unit (17) is configured to determine that the rapid resumption condition is met when the second deceleration-triggering object is located behind the stop line that is the first deceleration-triggering object or behind a stop line associated with a traffic signal that is the first deceleration-triggering object, and the notification unit (18) is configured not to output the deceleration support termination notification when the quick resumption condition determining unit (17) determines that the quick resumption condition is satisfied, even in a case where the termination condition determining unit (15) determines that the deceleration support termination condition is satisfied for the first deceleration-triggering object. [7] A driving assistance device (100) configured to start deceleration assistance for a driver's vehicle based on a distance between the driver's vehicle and a deceleration-triggering object in front of the driver's vehicle, the driving assistance device (100) comprising a controller (10) configured to: determine whether a preset deceleration assist start condition is met based on a distance between the driver's vehicle and a first deceleration-triggering object in front of the driver's vehicle; to start the deceleration assistance for the driver's vehicle relative to the first deceleration-triggering object when it is determined that the deceleration assistance start condition is met; determine whether a preset deceleration assistance termination condition is met based on the distance between the driver's vehicle and the first deceleration-inducing object, or based on a speed of the driver's vehicle during deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object; issue a deceleration support termination notice to a driver of the driver's vehicle when it is determined that the deceleration support termination condition is met; to determine whether a second deceleration-inducing object is detected in front of the driver's vehicle during deceleration assistance for the driver's vehicle relative to the first deceleration-inducing object; and to determine, when it is determined that the deceleration support termination condition for the first deceleration-inducing object is satisfied and it is determined that the second deceleration-inducing object is detected, whether a preset condition for rapid resumption is satisfied based on a distance between the driver's vehicle and the second deceleration-inducing object and based on a relative speed between the driver's vehicle and the second deceleration-inducing object, wherein the controller (10) is configured not to output the deceleration support termination notification when the controller (10) determines that the rapid resumption condition is met, even in a case where the controller (10) determines that the deceleration support termination condition is met for the first deceleration-triggering object, characterized by , that the controller (10) is configured to to identify a type of the detected second deceleration-triggering object; and as the condition for a fast resumption, to use a different condition depending on the type of the second slowdown-triggering object.

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