JP2014000854A - Vehicular rearward alarm system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To output a rearward alarm at appropriate timing conformable to the state of a succeeding vehicle.SOLUTION: A vehicular rearward alarm system 1 includes a control device that controls the output timing of a rearward alarm which is outputted to a succeeding vehicle existent behind an own vehicle in relation to deceleration of the own vehicle. The control device varies the output timing of the rearward alarm on the basis of at least one of a degree to which the driver of the succeeding vehicle watches forward, the type of the succeeding vehicle concerning the size or weight of the succeeding vehicle, and a degree to which it is hard for the succeeding vehicle to avoid the own vehicle through steering manipulations.

Description

  The present invention relates to a vehicle rear warning device including an output device that outputs a warning to a subsequent vehicle behind the host vehicle in relation to deceleration of the host vehicle.

  Conventionally, when a situation where braking of the host vehicle is required in front of the host vehicle is detected, information on the following vehicle is detected, and a situation where braking of the host vehicle is required ahead of the host vehicle is detected. 2. Description of the Related Art A vehicle control device that controls turning on / off of a warning light for a following vehicle based on information is known (see, for example, Patent Document 1). In this vehicle control device, a warning light is lit when a succeeding vehicle is detected. However, even if a succeeding vehicle is detected, the warning light is turned on when a deceleration state of the following vehicle or a hazard lamp is lit. It is configured not to light up.

JP 2006-256480 A

  However, in the device disclosed in Patent Document 1, the lighting timing when the warning light is lit on the subsequent vehicle is determined without depending on the state of the subsequent vehicle. There is a problem that the warning light cannot be turned on at the timing.

  Accordingly, an object of the present invention is to provide a vehicle rear warning device that can output a rear warning at an appropriate timing according to the state of the following vehicle.

In order to achieve the above object, according to one aspect of the present invention, the apparatus includes a control device that controls the output timing of a rear alarm that is output to a subsequent vehicle behind the host vehicle in association with the deceleration of the host vehicle.
The control device includes a driver's forward gaze degree of the succeeding vehicle, a type of the succeeding vehicle related to the size or weight of the succeeding vehicle, and a difficulty degree of avoidance when the succeeding vehicle avoids the own vehicle by a steering operation. A vehicle rear warning device is provided, wherein the rear warning output timing is varied based on at least one of them.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle rear warning apparatus which can output a rear warning at the suitable timing according to the state of the following vehicle is obtained.

It is a figure which shows the structure of the vehicle rear warning apparatus 1 by one Example. It is a flowchart which shows an example of the back warning output process performed by system ECU10. It is a flowchart which shows an example of the setting process of the threshold value α for back warnings performed by system ECU10. 7 is a flowchart illustrating another example of a setting process of a rear warning threshold value α executed by the system ECU 10. 7 is a flowchart illustrating another example of a setting process of a rear warning threshold value α executed by the system ECU 10. It is a flowchart which shows an example of the emergency braking process performed by system ECU10 in relation to a front obstacle. FIG. 4 is a conceptual diagram illustrating an example of a relationship between a rear alarm output timing and an emergency braking start timing in relation to the rear alarm threshold value α setting method illustrated in FIG. 3. FIG. 6 is a conceptual diagram showing an example of the relationship between the output timing of the rear warning and the emergency braking start timing in relation to the setting method of the rear warning threshold value α shown in FIG. 5.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram illustrating a configuration of a vehicle rear warning device 1 according to an embodiment. The vehicle rear warning device 1 includes a system ECU 10.

  System ECU10 comprises a microcomputer, for example. The function of the system ECU 10 may be realized by arbitrary hardware, software, firmware, or a combination thereof. For example, any part or all of the functions of the system ECU 10 may be realized by an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or a digital signal processor (DSP). Note that the function of the system ECU 10 may be realized by a single ECU or a plurality of ECUs.

  An output device 12 is connected to the system ECU 10. The output device 12 outputs an alarm (hereinafter referred to as a rear alarm) to a subsequent vehicle behind the host vehicle in association with the operation of the braking device 14. The output device 12 may be a brake lamp, for example. In this case, the rear alarm may be realized by blinking (flashing) of a brake lamp. The output device 12 may be a hazard lamp, for example. In this case, the output of the rear warning may be blinking of a hazard lamp. The output device 12 may be a combination of a brake lamp and a hazard lamp. In this case, the output of the rear warning may be flashing of the brake lamp (flash) and flashing of the hazard lamp. The output mode of the rear alarm of the output device 12 is controlled by the system ECU 10. This will be described later.

  A braking device 14 is connected to the system ECU 10. The braking device 14 generates a braking force of the vehicle. The braking device 14 may be a braking device having an arbitrary configuration, but has a configuration capable of such emergency braking when emergency braking described later is performed. For example, the braking device 14 may be configured to close a master cylinder cut solenoid valve (M / C cut valve) and guide high-pressure oil from the pump to the wheel cylinder during emergency braking. Alternatively, the braking device 14 may include an accumulator, close the M / C cut valve during emergency braking, and guide the high-pressure oil from the accumulator to the wheel cylinder. The braking device 14 may be configured by a brake-by-wire system represented by ECB (Electric Control Braking system).

  A camera ECU 20 is connected to the system ECU 10. The function of the camera ECU 20 may be realized by arbitrary hardware, software, firmware, or a combination thereof, like the system ECU 10. Part or all of the functions of the camera ECU 20 may be realized by the system ECU 10.

  A back camera 22 is connected to the camera ECU 20. The back camera 22 is mounted on the vehicle so as to image the environment behind the vehicle. The back camera 22 may be attached to a rear door, for example. The back camera 22 captures an image of the vehicle rear environment (rear environment image) with an image sensor such as a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The back camera 22 may acquire a rear environment image in real time while the vehicle is running, and supply it to the system ECU 10 in a stream format with a predetermined frame period, for example. The back camera 22 may also be used for other purposes (for example, a camera for detecting a rear obstacle situation, a camera for parking assistance control, etc.). Further, the back camera 22 may be configured by a stereo camera.

  The camera ECU 20 detects the rear environment image from the back camera 22 and detects the driver's face direction of the succeeding vehicle, the lateral position of the succeeding vehicle (for example, the lateral position with respect to the own vehicle), and the type of the succeeding vehicle. Good. The detection result by the camera ECU 20 is transmitted to the system ECU 10 at a predetermined cycle. The face orientation of the driver of the following vehicle, the lateral position of the following vehicle, and the type of the following vehicle are used when determining the rear warning output timing described later. However, in a configuration in which only one of the three elements of the face direction of the driver of the succeeding vehicle, the lateral position of the succeeding vehicle, and the type of the succeeding vehicle is used, only the used element needs to be detected.

  Here, the following vehicle is a vehicle that travels behind the host vehicle. The subsequent vehicle to be image-recognized may be a vehicle that travels in the same lane as the own vehicle. Whether the vehicle is traveling in the same lane may be determined by image recognition. Further, the subsequent vehicle to be image-recognized may be a vehicle located within a predetermined distance behind the host vehicle.

  There are various methods for detecting the face orientation of the driver of the following vehicle, and any method may be used. For example, first, representative points (feature points) of the face are extracted from the vehicle rear environment acquired by the back camera 22. This feature extraction method may be any appropriate method, and for example, a technique based on Active Appearance Model (AAM) may be used. An appropriate edge detection algorithm (eg, Sobel's edge detection algorithm) is then applied to extract the boundary between the face and facial features. Next, using the edges and feature points extracted as described above, the facial parts are separated, and the shape of the facial parts is extracted. Next, the current posture (face orientation) is detected by comparing the degree of matching between the position or orientation of the extracted facial part and the position or orientation of the same part stored in advance. The orientation of the face may be represented by, for example, a rotation angle in a horizontal plane with respect to the front direction of the face when in a normal posture.

  Similarly, there are many different methods for detecting the following vehicle, and any method may be used. For example, the following vehicle may be recognized by pattern matching using the extracted edge or feature point. At this time, the type of the following vehicle may be identified by preparing a pattern (master pattern) for each type. Further, the lateral position of the subsequent vehicle may be calculated based on the recognized pixel position of the subsequent vehicle. Note that the type and lateral position of the following vehicle may be detected by a rear radar sensor instead of or in addition to the back camera 22. The rear radar sensor detects the state of the following vehicle behind the vehicle using radio waves (for example, millimeter waves), light waves (for example, lasers), or ultrasonic waves as detection waves. The rear radar sensor detects information indicating a relationship between the following vehicle and the own vehicle, for example, a relative speed, a relative distance, and an azimuth (lateral position) of the following vehicle with the own vehicle as a reference at a predetermined cycle. Further, the type and lateral position of the following vehicle may be determined based on information obtained by communication with the following vehicle (inter-vehicle communication).

  A front radar sensor 32 is connected to the system ECU 10. The front radar sensor 32 detects the state of a front obstacle (typically, the front vehicle) in front of the vehicle using radio waves (for example, millimeter waves), light waves (for example, lasers), or ultrasonic waves as detection waves. The front radar sensor 32 detects information indicating a relationship between the front obstacle and the own vehicle, for example, a relative speed, a relative distance, and an azimuth (lateral position) of the front obstacle based on the own vehicle at a predetermined cycle. When the front radar sensor 32 is a millimeter wave radar sensor, the millimeter wave radar sensor may be, for example, an electronic scan type millimeter wave radar. In this case, the front obstacle is detected using the Doppler frequency (frequency shift) of the radio wave. The relative speed of the front obstacle is detected using the delay time of the reflected wave, and the direction of the front obstacle is detected based on the phase difference of the received wave among the plurality of receiving antennas. These detection data are transmitted to the system ECU 10 at a predetermined cycle.

  A wheel speed sensor 40 disposed on each wheel of the vehicle may be connected to the system ECU 10. The wheel speed sensor 40 may be an active sensor or a passive sensor. Further, a yaw rate sensor 72 may be connected to the system ECU 10. The yaw rate sensor 72 may be attached, for example, under the center console of the vehicle. The yaw rate sensor 72 outputs a signal corresponding to the angular velocity generated around the center of gravity axis of the vehicle. The yaw rate sensor 72 outputs an acceleration sensor unit that outputs a signal corresponding to the acceleration in the vehicle longitudinal direction or the vehicle width direction generated in the vehicle on which it is mounted, and a yaw rate that outputs a signal corresponding to the angular velocity generated around the center of gravity axis of the vehicle. You may implement | achieve by the semiconductor-type sensor which comprised the sensor part integrally.

  FIG. 2 is a flowchart illustrating an example of a rear warning output process executed by the system ECU 10. The processing routine shown in FIG. 2 may be repeatedly executed at predetermined intervals while the vehicle is traveling, for example.

  In step 200, it is determined whether or not a predetermined forward obstacle has been detected by the front radar sensor 32. The predetermined forward obstacle is an obstacle ahead of the host vehicle in which the host vehicle may collide. The predetermined front obstacle may be an obstacle traveling on the same lane as the own vehicle. Whether or not the vehicle is traveling in the same lane may be determined based on the lateral position of the front obstacle detected by the front radar sensor 32 or the like. The predetermined front obstacle may be an obstacle located within a predetermined distance in front of the host vehicle. The detection of a predetermined front obstacle may be realized based on the image of the front monitoring camera instead of or in addition to the front radar sensor 32, or communication with the front obstacle (the front obstacle is the vehicle's The case may be realized based on information obtained by inter-vehicle communication).

  In step 202, the rear warning threshold value α is read. The rear alarm threshold value α is not a fixed value, but is changed as described later. A setting method (variable method) of the rear warning threshold value α will be described later.

  In step 204, based on information from the front radar sensor 32, a time until the host vehicle collides with a front obstacle: TTC (Time to Collision) is calculated (monitored). The TTC may be calculated by dividing the distance between the current front obstacle and the own vehicle by the relative speed between the current front obstacle and the own vehicle.

  In step 206, it is determined whether or not the TTC calculated in step 204 is equal to or less than the rear warning threshold value α. If the TTC is less than or equal to the rear warning threshold value α, the process proceeds to step 208. On the other hand, in other cases, the process returns to step 204, and the latest TTC is calculated in the next processing cycle. Thus, when a predetermined forward obstacle is detected in step 200, the TTC related to the forward obstacle is monitored thereafter, and the process proceeds to step 208 when the TTC becomes equal to or lower than the rear warning threshold value α. . In addition, when the predetermined monitoring cancellation condition is satisfied before the TTC becomes equal to or less than the rear warning threshold value α (for example, when the front obstacle detected in step 200 is not detected), the front The processing of this processing routine for the obstacle may be terminated.

  In step 208, the rear warning is output by the output device 12. Note that the output of the rear alarm may be the flashing of the brake lamp and / or the flashing of the hazard lamp as described above. The rear warning may be continuously output until a predetermined termination condition is satisfied (for example, while TTC is equal to or lower than the rear warning threshold value α).

  In this way, according to the processing shown in FIG. 2, when a predetermined front obstacle is detected, the TTC related to the front obstacle is monitored, and when the TTC becomes equal to or lower than the rear warning threshold value α. A rear warning is output by the output device 12.

  In the process shown in FIG. 2, when a predetermined forward obstacle is detected, the rear alarm threshold value α used in the determination in step 206 does not change during the monitoring of the forward obstacle thereafter (step 202). The rear alarm threshold value α read out in step (3) is continuously used). However, when the rear warning threshold value α is changed by the setting method of the rear warning threshold value α described later during monitoring of the front obstacle, the changed rear warning threshold value α may be used accordingly. Good.

  FIG. 3 is a flowchart showing an example of a rear alarm threshold value α setting process executed by the system ECU 10. Note that the rear alarm threshold value α set by the processing shown in FIG. 3 is read out in step 202 of the processing shown in FIG. 2 and used in the determination in step 206. The processing routine shown in FIG. 3 may be repeatedly executed at predetermined intervals while the vehicle is traveling, for example. Note that the processing routine shown in FIG. 3 may be executed in parallel with the processing routine shown in FIG. 2 described above or may be executed in an integrated manner.

  In step 300, it is determined whether or not a predetermined succeeding vehicle is detected by the camera ECU 20. The predetermined succeeding vehicle is a vehicle that should be notified when the braking device 14 is operated by the own vehicle (especially when emergency braking described later) is performed. Specifically, the predetermined succeeding vehicle may be a vehicle that travels in the same lane as the host vehicle, for example. Whether the vehicle is traveling in the same lane may be determined by image recognition. The predetermined succeeding vehicle may be a vehicle located within a predetermined distance behind the host vehicle. The predetermined succeeding vehicle may be detected based on information from the rear radar sensor instead of or in addition to the camera ECU 20 (back camera 22), or obtained by communication with the following vehicle (inter-vehicle communication). It may be detected based on the information to be obtained. If a predetermined subsequent vehicle is detected, the process proceeds to step 304. If a predetermined subsequent vehicle is not detected, the process proceeds to step 302.

In step 302, the rear warning threshold value α is set to the first threshold value α1. A configuration may be adopted in which a rear warning is not output when a predetermined succeeding vehicle is not detected. In this case, the first threshold value α1 may be substantially zero (that is, the predetermined succeeding vehicle is If not detected, the process shown in FIG. 2 may not be executed)
In step 304, based on the detection result from the camera ECU 20 (the driver's face direction information of the following vehicle), it is determined whether or not the driver's face direction of the following vehicle is the front direction. That is, it is determined whether or not the driver of the following vehicle is paying attention to the front without looking aside. When the face direction of the driver of the following vehicle is the front direction, the process proceeds to step 308, and when the face direction of the driver of the following vehicle is not the front direction (for example, when the driver of the following vehicle is looking aside) ), Go to Step 306.

  In step 306, the rear warning threshold value α is set to the second threshold value α2.

  In step 308, the rear warning threshold value α is set to the third threshold value α3.

  Here, the second threshold value α2 is a value larger than the third threshold value α3. Note that even when a predetermined succeeding vehicle is not detected, the third threshold value α3 may be the same as the first threshold value α1 when a configuration in which a rear alarm is output by the process shown in FIG. 2 is adopted. For example, the third threshold value α3 may correspond to the start timing of the brake operation by the driver to be performed in order to avoid a collision with a predetermined forward obstacle. Therefore, the third threshold value α3 may be the same as the threshold value when emergency braking (interventional braking) is started, or may be slightly larger than the threshold value when emergency braking is started. . In addition, in the configuration in which a gentle preliminary emergency braking (interventional braking for prompting the driver to perform a voluntary braking operation) is performed first, followed by the two-stage emergency braking in which the emergency braking is performed (see FIG. 6), The third threshold value α3 may correspond to the timing for performing preliminary emergency braking.

  Thus, according to the process shown in FIG. 3, when the face direction of the driver of the following vehicle is not the front direction, the threshold value for the rear warning is larger than when the face direction of the driver of the following vehicle is the front direction. α (second threshold α2) is set. As a result, when the face direction of the driver of the following vehicle is not the front direction, the TTC is the rear warning threshold value α in the process shown in FIG. 2 rather than when the face direction of the driver of the following vehicle is the front direction. The following time point (the time point when affirmative determination is made in step 206) becomes earlier. Accordingly, when the face direction of the driver of the following vehicle is not the front direction, the output timing of the rear warning is advanced compared to the case where the face direction of the driver of the following vehicle is the front direction.

  Here, when the driver of the following vehicle is not in the front direction, even if a rear warning is output, the driver of the following vehicle is not immediately aware of the rear warning and performs a collision avoiding operation (for example, a brake pedal). May be delayed. On the other hand, when the face direction of the driver of the following vehicle is the front direction, the driver of the following vehicle is immediately aware of the rear warning, and is likely to immediately perform the collision avoidance operation.

  In this regard, according to the processing shown in FIG. 3, when the driver's face direction of the following vehicle is not the front direction, the output timing of the rear warning is advanced, so that the driver of the following vehicle moves forward (the direction of the own vehicle). ) Can be given time to focus on. Therefore, even if the driver of the following vehicle does not immediately notice the rear warning, the collision avoidance operation can be performed by noticing the rear warning thereafter. On the other hand, when the driver of the following vehicle faces in the front direction, the output timing of the rear warning is not advanced, and the annoyance that can be given to the driver of the subsequent vehicle due to the unnecessary rear warning is prevented. can do.

  In the process shown in FIG. 3, the rear warning threshold value α is varied depending on whether the driver's face direction of the following vehicle is the front direction. It is also possible to vary the rear warning threshold value α by evaluating the above factors. For example, the forward gaze degree of the driver of the succeeding vehicle is determined by the direction of the driver's face of the succeeding vehicle, the frequency of change of the driver's gaze direction of the succeeding vehicle and the face direction of the driver of the succeeding vehicle, and the good visibility. Or the like. For example, when the change frequency of the driver's face direction in the following vehicle is large, it is determined that the driver's forward gaze degree is low, and a larger rear warning threshold value α (for example, the second threshold value α2) is set. It's okay. Further, when a drowsiness state of the driver of the following vehicle is detected (a state where the arousal level is lower than a predetermined reference), it is determined that the driver's forward gaze degree is low, and the larger rear warning threshold α (For example, the second threshold value α2) may be set. If the forward visibility is poor due to rain, fog, snow, or the like, it is determined that the driver's forward gaze degree is low, and a larger rear warning threshold value α (for example, the second threshold value α2) is set. It's okay. Further, the degree of forward gaze may be evaluated in three or more stages, and the rear warning threshold value α may be varied in three or more stages.

  In the process shown in FIG. 3, the face orientation of the driver of the following vehicle is determined based on information from the camera ECU 20 (back camera 22) of the own vehicle. The determination may be made based on information from a camera that images the driver of the vehicle. In this case, the information from the camera mounted on the following vehicle may be acquired through communication (inter-vehicle communication) with the following vehicle.

  FIG. 4 is a flowchart showing another example of the rear alarm threshold value α setting process executed by the system ECU 10. Note that the rear alarm threshold value α set by the process shown in FIG. 4 is read out in step 202 of the process shown in FIG. 2 and used in the determination in step 206. The processing routine shown in FIG. 4 may be repeatedly executed at predetermined intervals while the vehicle is traveling, for example. Note that the processing routine shown in FIG. 4 may be executed in parallel with the processing routine shown in FIG. 2 described above or may be executed in an integrated manner.

  The processes in steps 400, 402, 406, and 408 may be the same as the processes in steps 300, 302, 306, and 308 shown in FIG.

  In step 404, based on the detection result from the camera ECU 20 (vehicle type information of the following vehicle), it is determined whether or not the subsequent vehicle is a large vehicle type (for example, a large truck or a medium or larger truck). If the succeeding vehicle is a large vehicle type, the process proceeds to step 406, and if it is any other vehicle type (for example, a normal car, a light vehicle, a motorcycle), the process proceeds to step 408.

  As described above, according to the processing shown in FIG. 4, when the succeeding vehicle is a large vehicle type, a larger rear warning threshold value α (second threshold value α2) is set than when the following vehicle is other than the large vehicle type. The As a result, when the following vehicle is a large vehicle type, the time point when the TTC becomes equal to or lower than the rear warning threshold value α in the process shown in FIG. Will be earlier). Therefore, when the subsequent vehicle is a large vehicle type, the output timing of the rear warning is advanced compared to the case where the subsequent vehicle is other than the large vehicle type.

  Here, the braking distance of the vehicle is different for each vehicle type. In particular, a large vehicle type is significantly heavier than an ordinary automobile, and therefore has a longer braking distance. Therefore, when the following vehicle is a large vehicle type, it is highly necessary to perform a collision avoidance operation (for example, a brake pedal depression operation) at a timing earlier than that of a normal automobile.

  In this regard, according to the process shown in FIG. 4, when the following vehicle is a large vehicle type, the output timing of the rear warning is advanced, so the driver of the following vehicle is prompted to perform a collision avoidance operation at an appropriate timing. be able to. On the other hand, when the following vehicle is other than a large vehicle type, the output timing of the rear warning is not advanced, and the troublesomeness that can be given to the driver of the subsequent vehicle due to the unnecessary rear warning is prevented.

  In the process shown in FIG. 4, the rear warning threshold value α is varied depending on whether the following vehicle is a large vehicle type, but other factors indicating the braking distance of the following vehicle are evaluated, and the rear warning threshold value is evaluated. It is also possible to vary the threshold value α. For example, since the braking distance of the following vehicle depends on the actual weight (vehicle weight + loading weight) of the following vehicle, it may be determined based on the weight information of the following vehicle. For example, when the weight of the following vehicle is large, a larger rear warning threshold value α (for example, the second threshold value α2) may be set. In this case, the weight information may be acquired via vehicle-to-vehicle communication. Further, the vehicle type may be classified into three or more types, and the rear warning threshold value α may be varied in three or more stages. For example, when the following vehicle is a large vehicle type, the second threshold value α2 is set as the rear warning threshold value α. When the following vehicle is a motorcycle, the third threshold value α3 is set as the rear warning threshold value α, and the following vehicle is large. In the case other than the vehicle type and the motorcycle, the fourth threshold value α4 (where α3 <α4 <α2) may be set as the rear warning threshold value α.

  In the process shown in FIG. 4, the vehicle type of the following vehicle is determined based on information from the camera ECU 20 (back camera 22) of the own vehicle, but the vehicle type information of the following vehicle is communicated with the following vehicle ( May be obtained via inter-vehicle communication).

  FIG. 5 is a flowchart showing another example of the rear alarm threshold value α setting process executed by the system ECU 10. Note that the rear alarm threshold value α set by the process shown in FIG. 5 is read out in step 202 of the process shown in FIG. 2 and used in the determination in step 206. The processing routine shown in FIG. 5 may be repeatedly executed at predetermined intervals while the vehicle is traveling, for example. The processing routine shown in FIG. 5 may be executed in parallel with the processing routine shown in FIG. 2 described above or may be executed in an integrated manner.

  The processes in steps 500, 502, 506 and 508 may be the same as the processes in steps 300, 302, 306 and 308 shown in FIG.

  In step 504, based on the detection result (lateral position information of the succeeding vehicle) from the camera ECU 20, the lateral movement distance (hereinafter referred to as collision avoidance) necessary for the succeeding vehicle to avoid a collision with the vehicle (own vehicle) is determined. It is determined whether or not (referred to as distance) is greater than or equal to a predetermined distance. The predetermined distance may be an arbitrary value smaller than the vehicle width of the vehicle (own vehicle) and larger than half the vehicle width of the vehicle (own vehicle), for example. The collision avoidance distance may be calculated in consideration of the left and right sides where collision can be avoided. For example, when there is a guard rail or wall on the left side and collision avoidance on the left side is impossible, the collision avoidance distance when avoiding the right lane may be calculated. Further, in a situation where collision avoidance by steering is not required, such as when the road is a one-lane road, a fixed value greater than a predetermined distance may be used as the collision avoidance distance. However, in these cases, the vehicle width or type of the following vehicle may be considered. For example, when the following vehicle is a motorcycle, even if it is a one-lane road, collision avoidance may be possible using the space on the side of the vehicle (own vehicle). If the collision avoidance distance is greater than or equal to the predetermined distance, the process proceeds to step 506. Otherwise (ie, the collision avoidance distance is less than the predetermined distance), the process proceeds to step 508.

  As described above, according to the processing shown in FIG. 5, when the collision avoidance distance is large, a larger rear warning threshold value α (second threshold value α2) is set than when the collision avoidance distance is small. As a result, when the collision avoidance distance is large, the time point when the TTC is equal to or less than the rear warning threshold α in the process shown in FIG. Get faster. Therefore, when the collision avoidance distance is large, the rear alarm output timing is advanced compared to when the collision avoidance distance is small.

  Here, the greater the collision avoidance distance, the higher the necessity of performing a collision avoidance operation (for example, steering for collision avoidance) at an earlier timing. In this regard, according to the process shown in FIG. 5, when the collision avoidance distance is large, the output timing of the rear warning is advanced, so the collision avoidance is performed at an appropriate timing for the driver of the following vehicle having a large collision avoidance distance. The operation can be prompted. On the other hand, when the collision avoidance distance is not large, the output timing of the rear warning is not advanced, and the troublesomeness that can be given to the driver of the following vehicle due to the unnecessary rear warning is prevented.

  In the process shown in FIG. 5, the rear warning threshold value α is varied depending on whether or not the collision avoidance distance is equal to or greater than the predetermined distance. It is also possible to vary the threshold value α. For example, the rear warning threshold value α may be varied according to the time required for the subsequent vehicle to move the collision avoidance distance. Further, the rear warning threshold value α may be varied in accordance with the traffic volume of the lane on the collision avoidance side, for example. For example, when the traffic volume of the lane on the collision avoidance side is large, a larger rear warning threshold value α (for example, the second threshold value α2) may be set. Further, the threshold value α for the rear warning is the number of collision avoidable sides (2 if collision can be avoided on both the left and right sides, 1 if collision can be avoided on one of the left and right sides, and if both sides cannot be avoided) 0). For example, when the number of collision avoidable sides is 0 (or 1 or less), a larger rear warning threshold value α (for example, the second threshold value α2) may be set. Further, the degree of difficulty in avoidance may be classified into three or more types, and the rear warning threshold value α may be varied in three or more stages.

  In the process shown in FIG. 5, the collision avoidance distance is determined based on information from the camera ECU 20 (back camera 22) of the own vehicle. May be obtained via inter-vehicle communication). The information acquired from the following vehicle via inter-vehicle communication may be information that directly represents the collision avoidance distance, or information that is indirectly represented (for example, information that represents the relationship between the following vehicle and the white line of the lane). It may be.

  Note that the three rear alarm threshold values α shown in FIG. 3 to FIG. 5 described above can be realized by any two or more combinations. That is, the rearward alarm threshold value α is varied according to any two or three of the following vehicle driver's face direction (forward gaze degree), the vehicle type of the subsequent vehicle, and the collision avoidance distance (avoidance difficulty level). Also good. For example, when considering these three factors, the rear warning threshold value α may be evaluated in the same manner as the three factors, or may be evaluated with weighting a particular factor over other factors. Good.

  FIG. 6 is a flowchart illustrating an example of an emergency braking process executed by the system ECU 10 in relation to a front obstacle. The processing routine shown in FIG. 6 may be repeatedly executed at predetermined intervals while the vehicle is traveling, for example. Note that the processing routine shown in FIG. 6 may be executed in parallel with the processing routine shown in FIG. 2 described above or may be executed in an integrated manner.

  The processes in steps 600 and 602 are the same as the processes in steps 200 and 204 in FIG.

  In step 604, it is determined whether or not the TTC calculated in step 602 is equal to or less than the preliminary emergency braking threshold value β1. If TTC is equal to or less than the preliminary emergency braking threshold value β1, the process proceeds to step 606. On the other hand, in other cases, the process returns to step 602, and the latest TTC is calculated in the next processing cycle. In this way, when a predetermined forward obstacle is detected in step 600, the TTC related to the forward obstacle is monitored, and when the TTC becomes equal to or less than the preliminary emergency braking threshold β1, the process proceeds to step 606. move on. In addition, when a predetermined monitoring cancellation condition is satisfied before the TTC becomes equal to or less than the preliminary emergency braking threshold β1 (for example, when the front obstacle detected in the above step 600 is not detected) The processing of this processing routine for the front obstacle may be terminated.

  In step 606, it is determined whether or not the TTC calculated in step 602 is equal to or less than the emergency braking threshold β2. The emergency braking threshold value β2 is set to a value smaller than the preliminary emergency braking threshold value β1.

  In step 608, preliminary emergency braking is performed. The preliminary emergency braking is an emergency braking that is gentler than the main emergency braking described later, and also has a function of prompting the driver to perform an independent braking operation to avoid a collision with a front obstacle. The preliminary emergency braking may be continued until the later-described emergency braking is executed while the TTC is equal to or less than the emergency braking threshold β2. It should be noted that before the TTC becomes equal to or less than the emergency braking threshold β2, a predetermined preliminary emergency braking termination condition is satisfied (for example, the operation of the brake pedal by the driver is detected based on, for example, a pedaling force switch, and the TTC is For example, when the emergency braking threshold β1 becomes larger, the preliminary emergency braking may be ended (or interrupted).

  In step 610, the emergency braking is executed. This emergency braking is emergency braking that is steeper than the above-described preliminary emergency braking (braking that generates a high braking force), and is intended to urgently avoid a collision with a front obstacle. For example, when the preliminary emergency braking is realized by, for example, setting the target value of the pressure increase gradient with respect to the wheel cylinder pressure to the first value, the emergency brake sets the target value of the pressure increase gradient to the second value. It may be realized by setting (a value larger than the first value or an upper limit value). Note that the target control value itself for performing emergency braking is arbitrary, and instead of the target value of the pressure increase gradient, the target value of the differential pressure instruction value (applied current value) for the M / C cut valve is used. Also good.

  Note that emergency braking is typically performed under a situation where the driver does not operate the brake pedal. That is, the target control value used in steps 608 and 610 is a value (including a fixed value) determined based on factors other than the operation amount of the brake pedal. In addition, when the operation of the brake pedal by the driver is detected after the emergency braking is started, for example, the operation of the brake pedal may be ignored and the emergency braking may be continued. Alternatively, after the emergency braking is started, when the operation of the brake pedal by the driver is detected, for example, when the master cylinder pressure becomes equal to or higher than a predetermined pressure, the normal braking may be performed, or Both hydraulic pressures may be added together (or selected to be larger) and applied to the wheel cylinder.

  In the process shown in FIG. 6, the main emergency braking is started when the TTC becomes equal to or less than the main emergency braking threshold β2, but the main emergency braking has been performed for a predetermined time from the start of the preliminary emergency braking. It may be executed at that time. In this case, the emergency braking may not be executed if the driver's operation of the brake pedal is detected within a predetermined time from the start of the preliminary emergency braking, or the emergency braking may be performed for a predetermined time from the start of the preliminary emergency braking. If an operation of the brake pedal by the driver is detected, the execution of the emergency braking may be waited until the TTC becomes equal to or less than the emergency braking threshold β2.

  Here, a preferred example of the relationship between the above-described rear alarm output timing and emergency braking start timing will be described. As described above, the threshold value α for the rear warning includes the second threshold value α2 corresponding to the quick-start timing and the third threshold value α3 corresponding to the normal timing in a situation where a predetermined succeeding vehicle is detected. Set selectively. The second threshold value α2 may be a value larger than the emergency braking threshold value β2, but is preferably set to a value larger than the preliminary emergency braking threshold value β1. In this case, the rear alarm whose timing is advanced is output at a timing earlier than the operation timing of the preliminary emergency braking. In the configuration in which the emergency braking is performed without performing the preliminary emergency braking, the second threshold α2 may be set to a value larger than the emergency braking threshold β2. In this case, the rear alarm that is advanced in timing is output at a timing earlier than the operation timing of the emergency braking.

  Further, as long as the third threshold value α3 is a value smaller than the second threshold value α2, the third threshold value α3 may be a value larger than the preliminary emergency braking threshold value β1 or the same value as the preliminary emergency braking threshold value β1. It may be the same value as the emergency braking threshold β2. When the third threshold value α3 is the same value as the preliminary emergency braking threshold value β1, the rear warning is output at a timing that coincides with the operation timing of the preliminary emergency braking.

  FIG. 7 is a conceptual diagram showing an example of the relationship between the output timing of the rear warning and the start timing of emergency braking in relation to the method for setting the rear warning threshold value α shown in FIG. FIG. 7A shows a case where the third threshold value α3 is set as the rear warning threshold value α due to the driver of the following vehicle paying attention to the front, and FIG. The case where the second threshold value α2 is set as the rear warning threshold value α because the driver of the vehicle is driving aside is shown. 7A and 7B, the traveling conditions of the two vehicles (the own vehicle and the following vehicle) are the same, and the relative speed between the front obstacle and the own vehicle is constant. Furthermore, the front obstacle is assumed to be a stationary object (moving speed 0) for the sake of preventing the explanation from becoming complicated.

  When the third threshold value α3 is set as the rear warning threshold value α due to the driver of the following vehicle paying attention to the front, as shown in FIG. 7A, the TTC is set to the third threshold value α3. At the time t1, the rear alarm is output. In FIG. 7, the timing at time t2 when TTC becomes the threshold value for emergency braking β2 is shown as “timing for emergency braking”. In this way, when the driver of the following vehicle pays attention to the front, a rear warning is output at the time t1 when the TTC becomes the third threshold value α3, and then the TTC becomes the emergency braking threshold value β2. The emergency braking is executed at time t2.

  On the other hand, when the second threshold value α2 is set as the rear warning threshold value α because the driver of the following vehicle is driving aside, as shown in FIG. 7B, the TTC is the second threshold value. A rear warning is output at time t0 when α2 is reached. This time point t0 is earlier than the rear alarm output time point t1 in the example shown in FIG. 7A because the second threshold value α2 is larger than the third threshold value α3. That is, in the example shown in FIG. 7B, the rear warning is issued early for the time (t1-t0) as compared to the example shown in FIG. Thereby, it is possible to secure a margin until the driver of the following vehicle reacts to the rear warning. Similarly, after that, the emergency braking is executed at time t2 when the TTC becomes the emergency braking threshold β2. Therefore, in the example shown in FIG. 7B, the time from the rear alarm output time to the execution time of the emergency braking is longer than the time shown in FIG. 7A by the time (t1-t0). .

  FIG. 8 is a conceptual diagram showing an example of the relationship between the rear alarm output timing and the emergency braking start timing in relation to the rear alarm threshold value α shown in FIG. 5. FIG. 8A shows a case where the third threshold value α3 is set as the rear warning threshold value α due to the small collision avoidance distance, and FIG. 8B shows that the collision avoidance distance is large. In this case, the second threshold value α2 is set as the rear warning threshold value α. In the example shown in FIG. 8, the succeeding vehicle is a motorcycle. Similarly, in FIGS. 8A and 8B, the traveling conditions of the two vehicles (the own vehicle and the following vehicle) are the same, and the relative speed between the front obstacle and the own vehicle is constant. Further, it is assumed that the front obstacle is a stationary object (moving speed 0) for the convenience of preventing the explanation from becoming complicated.

  When the third threshold value α3 is set as the rear warning threshold value α due to the small collision avoidance distance, as shown in FIG. 8A, the rear side at the time t1 when the TTC becomes the third threshold value α3. An alarm is output. In FIG. 8, the timing at the time point t2 when the TTC becomes the threshold value for emergency braking β2 is indicated as “timing for emergency braking”. In this way, when the collision avoidance distance is small, the rear warning is output at the time t1 when the TTC becomes the third threshold α3, and then the emergency braking at the time t2 when the TTC becomes the emergency braking threshold β2. Is executed.

  On the other hand, when the second threshold value α2 is set as the rear warning threshold value α due to the large collision avoidance distance, as shown in FIG. 8B, at the time t0 when the TTC becomes the second threshold value α2. And a rear warning is output. Since the second threshold value α2 is larger than the third threshold value α3, the time point t0 is earlier than the rear alarm output time point t1 in the example shown in FIG. That is, in the example shown in FIG. 8B, the rear alarm is issued early for the time (t1-t0) as compared to the example shown in FIG. Thereby, it is possible to secure a margin until the driver of the following vehicle reacts to the rear warning. Similarly, after that, the emergency braking is executed at time t2 when the TTC becomes the emergency braking threshold β2.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

For example, in the above-described embodiment, the timing of emergency braking (preliminary emergency braking or main emergency braking) is determined based on TTC, but the timing of emergency braking may be determined based on any other method. . For example, the collision inevitable determination map may be referred to based on the relative speed with the front obstacle and the TTC to determine whether or not the collision with the front obstacle is inevitable. Specifically, the deceleration G (m / s ² ) and the deceleration speed V (m / s) t seconds after the emergency braking is started are the maximum speed G _MAX (m / s ² ) and the deceleration, respectively. When the gradient is J (m / s ³ ), the following relationship is established.
When _{t ≦ G MAX / J, G} = Jt, V = J × t 2/2
When G _MAX / J <t, G = G _MAX , V = G _MAX ² / (2J) + G _MAX (t−G _MAX / J)
In this case, a collision unavoidable determination map may be created by regarding a relative speed larger than the deceleration speed V after t seconds as a collision unavoidable relative speed. Alternatively, the collision inevitable determination map using the relative distance as a parameter may be created by obtaining the relative distance by integrating the deceleration speed V. Alternatively, as a more complicated algorithm, acceleration of a front obstacle may be considered.

  In the above-described embodiment, the timing of the rear alarm is determined based on the TTC. However, the timing of the rear alarm may be determined based on any other method. For example, the timing of the rear warning may be determined with reference to a map similar to the above-described collision inevitable determination map that can be used for emergency braking. In this case, if the rear warning map is set to a milder condition (a condition that is satisfied at an earlier timing) than the collision unavoidable determination map, the rear warning output timing can be set earlier than the emergency braking operation timing. Good. Two or more types of rear warning maps may be prepared, and the timing of the rear warning may be varied according to the situation of the following vehicle as described above. Further, the timing of the rear warning is not necessarily determined using the same parameter as the parameter for determining the emergency braking operation timing, and the rear warning timing is a parameter for determining the emergency braking operation timing. May be determined using different parameters.

  In the above-described embodiment, emergency braking is performed when requested by the pre-crash safety system, but a system other than the pre-crash safety system (preceding vehicle follow-up control, auto cruise control, or the like) It may be executed when there is a request from a system that performs operation control.

  In the above-described embodiment, the configuration in which emergency braking is performed has been described with reference to FIG. 6 and the like, but a configuration in which emergency braking is not performed may be used. In this case as well, the driver's own vehicle deceleration (particularly sudden deceleration) may occur due to a braking operation by the driver or a collision with a front obstacle, and it is necessary to notify the driver of the following vehicle of such sudden deceleration. . In this case, in the same manner as described above, the timing of the rear warning may be determined based on the TTC, or the start timing of the sudden deceleration of the host vehicle is predicted, and the rear warning is issued based on the predicted start timing. Timing may be determined. In any case, the timing of the rear warning may be determined in a manner that is variable according to the situation of the following vehicle, as described above.

  In the above-described embodiment, the output of the rear warning is realized by the output device 12 of the own vehicle, but may be realized by an alarm device mounted on the following vehicle. In this case, the system ECU 10 issues an alarm output request to the succeeding vehicle via, for example, a wireless communication device so that the alert is output by the alarm device mounted on the succeeding vehicle at the timing of the rear alarm determined as described above. May be sent.

1 Vehicle rear warning device 10 System ECU
12 Output device 14 Braking device 20 Camera ECU
22 Back camera 32 Forward radar sensor 40 Wheel speed sensor 72 Yaw rate sensor

Claims (6)

A control device that controls the output timing of a rear warning that is output to a subsequent vehicle behind the host vehicle in relation to the deceleration of the host vehicle,
The control device includes a driver's forward gaze degree of the succeeding vehicle, a type of the succeeding vehicle related to the size or weight of the succeeding vehicle, and a degree of difficulty in avoiding when the succeeding vehicle avoids the own vehicle by a steering operation. A vehicle rear alarm device, wherein the rear alarm output timing is varied based on at least one of them.   2. The control device determines a forward gaze degree of a driver of the following vehicle, and when the front gaze degree is low, the output timing of the rear warning is advanced compared to a case where the front gaze degree is high. The vehicle rear warning device according to the above.   The control device determines a type of the following vehicle, and when the following vehicle is a large vehicle type, the output timing of the rear warning is advanced compared to a case where the following vehicle is other than a large vehicle type. Or the vehicle rear warning device according to 2;   4. The control device according to claim 1, wherein the control device determines the degree of difficulty of avoidance, and when the degree of difficulty of avoidance is high, the output timing of the rear alarm is advanced as compared with the case where the degree of difficulty of avoidance is low. The vehicle rear warning device according to claim 1.   The output timing of the advanced rear warning is earlier than the operation timing of a braking device that is operated to intervene in order to avoid a collision between a front obstacle ahead of the host vehicle and the host vehicle. The vehicle rear warning device according to any one of the preceding claims.   The variable range of the output timing of the rear warning includes the same timing as the operation timing of the braking device that is intervened to avoid a collision between a front obstacle ahead of the host vehicle and the host vehicle. The vehicle rear warning device as described.

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