Vehicle control device

Abstract

To provide a vehicle control device that can suppress unnecessary operation of an automatic brake that may occur due to occurrence of deceleration in a vehicle, when making the vehicle approach an obstacle existing around the vehicle.SOLUTION: A vehicle control device 10 comprises: an obstacle sensing part 21 that senses a relative distance and relative speed between a vehicle and an obstacle; and an automatic brake control part 23 that operates an automatic brake when a collision predicted time calculated from the relative distance and the relative speed is shorter than a predetermined collision predicted time. When the automatic brake is not operated after a lapse of predetermined time from a timing at which a difference between the relative distance and a distance by which the automatic brake is started at the relative speed is shorter than a predetermined distance, the automatic brake control part 23 delays a timing at which operation of the automatic brake is started, or prohibits the automatic brake from being operated.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a vehicle control device. [Background technology]

[0002] There is a known automatic vehicle braking system that uses the collision time, which is the distance between an obstacle and the vehicle divided by the speed difference between the obstacle and the vehicle, as the threshold for starting automatic braking. The collision time is also called the collision prediction time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-62604 Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle equipped with an automatic brake, even if the vehicle is already decelerating, there are cases where the automatic brake is activated when the vehicle approaches an obstacle in the vicinity, causing the automatic brake to fall below the activation threshold. In such cases, the activation of the automatic brake is unnecessary and it is desirable to suppress it.

[0005] The present invention has been made in consideration of the above-described situation, and provides a vehicle control device that can suppress unnecessary operation of the automatic brake, which may occur when the vehicle decelerates when approaching an obstacle in the vehicle's vicinity. [Means for solving the problem]

[0006] In order to solve the above problem, a vehicle control device according to an embodiment of the present invention comprises an obstacle detection unit that detects the relative distance and relative speed between a vehicle and an obstacle, and an automatic brake control unit that activates an automatic brake when a collision prediction time calculated from the relative distance and the relative speed becomes shorter than a predetermined collision prediction time, and if the automatic brake has not been activated after a predetermined time has elapsed from the point at which the difference between the relative distance and the distance at which the automatic brake is initiated at the relative speed becomes shorter than the predetermined distance, the automatic brake control unit delays the timing at which the automatic brake is initiated or prohibits the activation of the automatic brake. [Effects of the Invention]

[0007] The present invention provides a vehicle control device that can suppress unnecessary operation of the automatic brake, which may occur when the vehicle is decelerating when the vehicle approaches an obstacle in the vicinity. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram of a vehicle control system including a vehicle control device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram showing an example of an operation that does not require automatic braking in a vehicle equipped with a conventional automatic brake. [Figure 3] 10 is a diagram showing the change over time of the difference between the relative distance between the vehicle and an obstacle and the distance at which automatic braking is initiated at a relative speed in the automatic braking suppression control of the vehicle control device according to the embodiment of the present invention; [Figure 4] 4 is an enlarged view of the elapsed time of around 1 second in FIG. 3 and a timing chart showing an example of automatic brake suppression control based on a determination of the driver's intention to decelerate. [Figure 5] 1 is a diagram showing an example of a data table showing a correspondence relationship between a predetermined time and an automatic braking prohibition time in a vehicle control device according to an embodiment of the present invention; [Figure 6] 4 is a flowchart showing an example of automatic brake suppression control by a vehicle control device according to an embodiment of the present invention. [Figure 7]7 is a flowchart showing an alternative process to the process surrounded by the two-dot chain line P in FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of a vehicle control device of the present invention will be described with reference to FIGS.

[0010] FIG. 1 is a block diagram of a vehicle control system including a vehicle control device according to an embodiment of the present invention.

[0011] 1 is an automatic braking device that assists the driver in driving by performing Autonomous Emergency Braking (AEB), or so-called automatic braking, at appropriate times on a vehicle equipped with a vehicle control system 100 including the vehicle control device 10, thereby avoiding a collision between the vehicle and an obstacle. Note that in this embodiment, the vehicle equipped with the vehicle control system 100 is not limited to an engine vehicle, but may also be an electric vehicle, a hybrid vehicle, or a fuel cell vehicle.

[0012] As shown in Fig. 1, the vehicle control system 100 includes a camera 1, a wheel speed sensor 3, a brake control device 5, and a vehicle control device 10. The vehicle control device 10 controls the output of an automatic brake activation signal to the brake control device 5 for activating the automatic brake based on data output from the camera 1 and the wheel speed sensor 3. The camera 1, the wheel speed sensor 3, the brake control device 5, and the vehicle control device 10 are connected to each other so as to be able to communicate with each other via an in-vehicle network 11. The in-vehicle network 11 is, for example, a bus-type network that uses a CAN (Controller Area Network) as a communication protocol.

[0013] Camera 1 is an imaging device that captures images of the area ahead of the vehicle. Camera 1 has a solid-state imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor), and captures images of a predetermined imaging area at a predetermined frame rate. Camera 1 is typically a stereo camera. Image data captured by camera 1 is output to vehicle control device 10. Camera 1 is attached to the windshield, the back of the rearview mirror, the front of the vehicle, or the like to capture images of the area ahead.

[0014] In this embodiment, the camera 1 is assumed to capture images of obstacles present in front of the vehicle. However, the camera 1 may be assumed to capture images of obstacles present throughout the entire periphery of the vehicle by appropriately changing the installation position, number of installations, and imaging range. Instead of or in addition to the camera 1, at least one of the following combinations and configurations (not shown) may be used. That is, at least one of a combination of a radar sensor and a monocular camera and a radar sensor may be used. Furthermore, there may be multiple combinations of radar sensors and monocular cameras and multiple radar sensors. The radar sensor may be, for example, a millimeter-wave radar sensor that uses millimeter waves as the detection wave, a laser radar sensor that uses a laser as the detection wave, or a sonar radar sensor that uses ultrasound as the detection wave.

[0015] The wheel speed sensors 3 are provided on each wheel of the vehicle and detect the rotational speed of the wheel. The traveling speed of the vehicle, i.e., the vehicle speed, can be detected based on the wheel speeds detected by the wheel speed sensors 3. The vehicle speed is detected, for example, based on the average value of the wheel speeds detected for the four wheels. The wheel speed sensors 3 output the detected wheel speeds of each wheel as detection data to the brake control device 5 and the vehicle control device 10.

[0016] When the brake control device 5 receives an automatic brake activation signal from the vehicle control device 10 and detection data from the wheel speed sensor 3, it activates the brakes and applies a braking force to the vehicle. Specifically, the brake control device 5 includes a brake actuator (not shown) and a brake pedal (not shown). Based on the automatic brake activation signal and the detection data from the wheel speed sensor 3, the brake control device 5 drives the brake actuator to activate a brake mechanism (not shown). As a result, the brake mechanism applies a braking force to the vehicle, and the brakes are activated. The brake control device 5 also activates the brakes in response to the driver's operation of the brake pedal.

[0017] The vehicle control device 10 is configured as a computer equipped with a central processing unit (CPU), an input / output interface, and storage devices such as ROM and RAM. The vehicle control device 10 executes predetermined calculations related to the automatic brake control of the vehicle based on input signals (output data) from the camera 1 and the wheel speed sensor 3, and various setting values ​​previously set in the storage device, and outputs an automatic brake activation signal according to the result to the brake control device 5, causing the brake control device 5 to activate the brakes.

[0018] The vehicle control device 10 includes, for example, an obstacle detection unit 21 that detects the relative distance and relative speed between the vehicle and an obstacle, and an automatic brake control unit 23 that activates an automatic brake when the collision prediction time calculated from the relative distance and relative speed becomes shorter than a predetermined collision prediction time.

[0019] The obstacle detection unit 21 detects obstacles ahead of the vehicle by processing image data input from the camera 1, and detects the position, movement, shape, and distance of the obstacle, i.e., the relative distance from the vehicle. The obstacle detection unit 21 also detects the change per unit time in the detected relative distance as the relative speed between the vehicle and the obstacle. The obstacle detection unit 21 can also determine whether the obstacle is stationary based on the detected relative speed and the wheel speed data input from the wheel speed sensor 3. In this embodiment, the obstacle detection unit 21 detects other vehicles, bicycles, pedestrians, curbs, guardrails, utility poles, traffic signals, road signs, fences, walls, buildings, and the like as obstacles from the image data of the camera 1. The obstacle detection unit 21 may be provided as a unit (e.g., an image processing unit) separate from the vehicle control device 10. That is, the vehicle control system 100 may include an image processing unit (not shown). In this case, the image processing unit outputs various information related to the obstacle to the vehicle control device 10.

[0020] Based on the detection result of the obstacle detection unit 21, the automatic brake control unit 23 calculates a collision prediction time by dividing the relative distance by the relative speed. The collision prediction time is also called TCC (Time To Collision). The collision prediction time is the time until the vehicle collides with an obstacle if the relative speed at a certain point in time is maintained. Typically, as the vehicle and the obstacle approach each other, the collision prediction time gradually shortens, and when it becomes shorter than a predetermined collision prediction time, the automatic brake control unit 23 outputs an automatic brake activation signal to the brake control device 5 to activate the automatic brake. The predetermined collision prediction time is the time within which it is determined that the vehicle can avoid colliding with the obstacle if braking is applied to the vehicle. In addition to outputting the automatic brake activation signal to the brake control device 5, the automatic brake control unit 23 may also notify the driver that the automatic brake will be activated via a display device or an alarm device (neither of which are shown) provided near the driver's seat of the vehicle.

[0021] FIG. 2 is a diagram showing an example of an operation that does not require the automatic brake in a vehicle equipped with a conventional automatic brake.

[0022] As mentioned above, in vehicles equipped with conventional automatic brakes, there are situations in which, even though the vehicle is already decelerating, the automatic brake activation threshold is exceeded when the vehicle approaches an obstacle in the vicinity, causing the automatic brake to be activated unnecessarily.

[0023] An example of a situation in which the automatic brake operates unnecessarily will be described with reference to FIG. 2. In FIG. 2, the horizontal axis represents elapsed time, the left vertical axis (first vertical axis) represents distance, and the right vertical axis (second vertical axis) represents speed. FIG. 2 also shows, with solid lines, the relative distance Dre between a vehicle and an obstacle and the relative speed Vre between the vehicle and the obstacle when a vehicle not equipped with an automatic brake system is stopped by approaching the obstacle. For ease of explanation, the obstacle is a stationary object, such as a wall. In this case, the relative speed Vre between the vehicle and the obstacle is the vehicle speed. Note that the relationship between time, distance, and speed shown in FIG. 2 is merely an example to facilitate understanding of the following explanation. The same applies to FIGS. 3 and 4 described below.

[0024] As shown in FIG. 2, the time variation of the relative distance Dre and the relative speed Vre indicates that, as the vehicle approaches the obstacle, the driver manually applies the brakes, causing the vehicle to decelerate, and then the vehicle is stopped several tens of centimeters in front of the obstacle, between 1 and 3 seconds. Meanwhile, in the figure, the automatic braking initiation distance Dbs, which represents the distance at which automatic braking is initiated at the relative speed Vre, is shown by a dashed line, representing the time variation of the distance at which automatic braking is initiated in a vehicle equipped with a conventional automatic braking device. The automatic braking is activated when the relative distance Dre becomes shorter than the automatic braking initiation distance Dbs. The automatic braking initiation distance Dbs is the distance obtained by multiplying the predetermined collision prediction time by the relative speed Vre. When the predetermined collision prediction time is a constant value, the automatic braking initiation distance Dbs changes depending on the relative speed Vre. In the example of FIG. 2, when the elapsed time is t seconds, the relative distance Dre becomes shorter than the automatic braking initiation distance Dbs, and the automatic braking is activated. In other words, in the case of a vehicle equipped with a conventional automatic braking device, the automatic brakes are activated after t seconds have elapsed even if the vehicle is not in a state of colliding with an obstacle. This unnecessary activation of the automatic brakes may impede the vehicle's travel.

[0025] Therefore, the automatic braking control unit 23 of the vehicle control device 10 of this embodiment delays the timing of starting the automatic braking or prohibits the operation of the automatic braking if the automatic braking does not occur after a predetermined time Tdw (see Figure 4) has elapsed from the point at which the difference between the relative distance Dre between the vehicle and the obstacle and the automatic braking initiation distance Dbs, which is the distance at which automatic braking is initiated at the relative speed Vre between the vehicle and the obstacle, becomes shorter than a predetermined distance Dth (see Figure 3).

[0026] Specifically, a driver typically decelerates the vehicle when approaching an obstacle to close the distance between the vehicle and the obstacle. At this time, the difference between the relative distance Dre and the automatic braking initiation distance Dbs decreases more slowly when deceleration is occurring than when no deceleration is occurring; that is, it takes longer for the difference to become zero. Therefore, if the automatic braking is not activated after a predetermined time Tdw has elapsed, during which the automatic braking would have been activated if the vehicle had not decelerated, the automatic braking control unit 23 assumes that the vehicle is approaching the obstacle while being decelerated, and prevents unnecessary automatic braking from occurring. In this way, the automatic braking control unit 23 suppresses unnecessary automatic braking. Furthermore, deceleration can occur not only due to the driver's own braking operation, but also due to factors such as uphill roads, road surfaces with a high rolling resistance coefficient, and / or headwinds. The automatic braking control unit 23 similarly suppresses unnecessary automatic braking from occurring for these factors that cause deceleration. The control by the automatic brake control unit 23, that is, the vehicle control device 10, to suppress the operation of the automatic brake under such predetermined conditions will be referred to as "automatic brake suppression control" hereinafter.

[0027] The predetermined time Tdw is a variable time that is longer as the deceleration of the vehicle increases and shorter as the deceleration of the vehicle decreases. Delaying the timing to start the automatic braking operation means, for example, offsetting the automatic braking start distance Dbs in the direction of shortening it, thereby lengthening the difference between the relative distance Dre and the automatic braking start distance Dbs and delaying the time until it becomes zero.

[0028] FIG. 3 is a diagram showing the change over time of the difference between the relative distance between the vehicle and an obstacle and the distance at which automatic braking is initiated at the relative speed in the automatic braking suppression control of the vehicle control device according to the embodiment of the present invention.

[0029] FIG. 4 is an enlarged view of the elapsed time of about 1 second in FIG. 3, and a timing chart showing an example of automatic brake suppression control based on a determination of the driver's intention to decelerate.

[0030] Now, with reference to FIGS. 3 and 4, the automatic braking suppression control of the vehicle control device 10 of this embodiment will be described in more detail. In the upper graphs of FIGS. 3 and 4 and the timing chart in the lower part of FIG. 4, the horizontal axis represents elapsed time, and in the upper graphs of FIGS. 3 and 4, the left vertical axis (first vertical axis) represents distance, and the right vertical axis (second vertical axis) represents speed. FIG. 3 shows the time change in the relative speed Vre between the vehicle and the obstacle when a vehicle equipped with a vehicle control system 100 including the vehicle control device 10 approaches the obstacle and stops it, using a solid line; the time change in the difference (Dre - Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs, using a dashed dotted line; and the predetermined distance Dth, which is a threshold for the difference (Dre - Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs, using a solid line. For convenience of explanation, the obstacle is a stationary object, such as a wall. In this case, the relative speed Vre between the vehicle and the obstacle is the vehicle speed.

[0031] As shown in FIG. 3, the relative velocity Vre, which is the vehicle speed, changes over time. As the vehicle approaches an obstacle, for example, the driver manually applies the brakes, causing the vehicle to decelerate, and then stops the vehicle several tens of centimeters before the obstacle, between 1 and 3 seconds. In other words, FIG. 3 assumes the same situation as FIG. 2. When the relative velocity Vre is constant (between 0 and 1 second), the difference (Dre - Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs decreases at the same rate. On the other hand, when the vehicle deceleration occurs between 1 and 2 seconds, the rate of decrease of the difference (Dre - Dbs) gradually decreases. In other words, the decrease of the difference (Dre - Dbs) becomes more gradual. The predetermined distance Dth is a threshold for determining the driver's intention to decelerate. The automatic brake control unit 23 determines that the driver intends to decelerate when the difference (Dre - Dbs) becomes shorter than the predetermined distance Dth and a certain time has passed. In addition, the vehicle control device 10 may further include a deceleration intention determination unit (not shown) that determines the driver's intention to decelerate, and the deceleration intention determination unit may perform the determination process to determine whether or not the driver intends to decelerate, instead of the automatic brake control unit 23.

[0032] Specifically, as shown in the lower timing chart of FIG. 4, the driver's intention to decelerate is determined to be valid (intention to decelerate) after 1.2 seconds have elapsed. Here, the "certain time" refers to the predetermined time Tdw (the time from t1 second to 1.2 seconds) shown in the lower timing chart of FIG. 4. In the example of the timing chart, once the driver's intention to decelerate is determined to be valid, an automatic braking prohibition time Tap is set, prohibiting automatic braking operation. Automatic braking is then permitted after the automatic braking prohibition time Tap has elapsed. Note that in the upper graph of FIG. 4, the change over time of the difference (Dre - Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs does not reflect the effect of braking that occurs when the automatic braking is turned on after t3 seconds have elapsed in the lower timing chart of FIG. 4.

[0033] On the other hand, if the driver has no intention of decelerating, the relative distance Dre will become shorter than the automatic braking start distance Dbs before a certain time has passed, and the automatic braking will be activated. That is, as shown in the upper graph of Figure 4, if the driver has no intention of decelerating and the vehicle does not decelerate, after 1 second has elapsed, the difference (Dre - Dbs) between the relative distance Dre and the automatic braking start distance Dbs will follow the course of dashed line H, and will become 0 at t2 seconds after the elapsed time, after which the automatic braking will be activated.

[0034] In this embodiment, the driver's intention to decelerate includes not only the driver's own braking operation but also the intention to tolerate deceleration caused by factors such as an uphill slope, a road surface with a high rolling resistance coefficient, and / or a headwind. Furthermore, when the automatic brake operation is prohibited, the automatic brake operation may be prohibited without setting the automatic brake prohibition time Tap. For example, in the timing chart at the bottom of FIG. 4, the prohibition of the automatic brake operation may be maintained until the vehicle is stopped after 1.2 seconds have elapsed. Furthermore, the automatic brake suppression control by the vehicle control device 10 of this embodiment is more preferably executed when the vehicle speed is relatively low. Specifically, assuming that the vehicle is stopped near a stationary obstacle, the relative speed Vre, i.e., the vehicle speed, is preferably 15 km / h or less, and more preferably 10 km / h or less.

[0035] Furthermore, it is preferable that the obstacle is stationary, in other words, it is preferable that the obstacle is a stationary body that does not move.

[0036] Specifically, as shown in FIG. 2, the timing at which the automatic brake operates in a vehicle equipped with a conventional automatic braking device (the timing at which the normal automatic brake operates) is a linear function when the obstacle is stationary. In other words, in the example of FIG. 2, the automatic braking initiation distance Dbs is expressed as a linear function with the elapsed time as a variable during the elapsed time from 1 second to 3 seconds when the vehicle is decelerating. Therefore, when the vehicle decelerates, the difference (Dre-Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs changes gradually over time. The automatic brake control unit 23 determines whether the driver intends to decelerate based on the gradual change in the difference (Dre-Dbs). A gradual change in the difference (Dre-Dbs) is best achieved when the obstacle is stationary. Therefore, defining the obstacle as a stationary object improves the reliability of the automatic brake suppression control, which suppresses unnecessary automatic braking based on the driver's intention to decelerate.

[0037] The predetermined distance Dth may also be determined based on the limit distance at which a collision between the vehicle and an obstacle can be avoided when the automatic brake is activated and the variation in the limit distance. In other words, the predetermined distance Dth may be determined by adding a distance that takes variation into consideration to the limit distance at which the automatic brake must be activated to avoid a collision between the vehicle and an obstacle.

[0038] Specifically, the delay in automatic braking caused by delaying the timing of starting automatic braking or by setting an automatic braking prohibition time Tap that prohibits automatic braking is assumed to be the time it takes for the vehicle to travel a predetermined distance Dth. By setting the predetermined distance Dth based on this assumption, safety is ensured by preventing the vehicle from colliding with an obstacle, even if there is a delay in automatic braking.

[0039] In this embodiment, the predetermined distance Dth is typically determined by a vehicle safety test conducted in advance. For example, a test to avoid a collision between a vehicle and an obstacle by activating the automatic brake is conducted multiple times to obtain data on the distance at which the collision could be avoided. From the obtained data, the average value and standard error of the distance at which the collision could be avoided are calculated, and the average value is set as the limit distance, and the standard error is set as the variation. Furthermore, the predetermined distance Dth may not be determined based on the results of the safety test, but may also be determined by further considering, for example, the characteristics of individual vehicles, variations in braking performance, etc. Furthermore, the determined predetermined distance Dth may be stored in advance as a set value in a storage device of a computer that configures the vehicle control device 10.

[0040] Furthermore, it is preferable that the minimum value of the predetermined time Tdw is the time until the automatic brake is activated when no deceleration is occurring in the vehicle (the time from t1 second to t2 second in FIG. 4).

[0041] Specifically, a situation in which the vehicle is not decelerating when approaching an obstacle is different from a situation in which the driver intends to decelerate and moves the vehicle closer to an obstacle ahead. Therefore, when the vehicle is not decelerating, the vehicle control device 10 operates the automatic brake as usual and controls the automatic brake in consideration of the driver's intention to decelerate.

[0042] In addition, the automatic braking prohibition time Tap, which is the time during which the operation of the automatic brake is prohibited, may be determined based on the time from when the difference (Dre-Dbs) between the relative distance Dre between the vehicle and an obstacle and the automatic braking initiation distance Dbs, which is the distance at which automatic braking is initiated at the relative speed Vre between the vehicle and the obstacle, becomes shorter than a predetermined distance Dth until it reaches 0 when deceleration of the vehicle occurs.

[0043] Specifically, when the vehicle is decelerating, the time from when the difference (Dre-Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs becomes shorter than the predetermined distance Dth until it reaches 0 is, for example, the predetermined time Tdw. It can be seen that the longer the predetermined time Tdw, the greater the deceleration of the vehicle. In other words, the length of the predetermined time Tdw can be used to determine the tendency of deceleration occurring in the vehicle. By determining the tendency of deceleration, it becomes possible to more appropriately set the automatic braking inhibition time Tap, which enables collision between the vehicle and an obstacle to be avoided. Note that the automatic braking inhibition time Tap is usually set longer if the deceleration is large, and shorter if the deceleration is small.

[0044] Another possible approach to determining the vehicle's deceleration trend is to use values ​​obtained by smoothing the output values ​​from a standard acceleration sensor installed in the vehicle, for example, by passing the output values ​​through a low-pass filter or by taking a moving average. However, deceleration detected by an acceleration sensor is prone to sudden fluctuations over time. Therefore, in a vehicle whose driving conditions change significantly from moment to moment, it is difficult to accurately determine the vehicle's deceleration from the value obtained by smoothing the output values ​​from the acceleration sensor. On the other hand, as described above, the difference in distance and the time from when the difference becomes smaller than a threshold to when the difference becomes zero can be used to estimate the deceleration trend without using the output value from the acceleration sensor. This is because, for example, distance is the second-order time integral of acceleration, and its change over time is relatively small and stable compared to the deceleration obtained from an acceleration sensor.

[0045] FIG. 5 is a diagram showing an example of a data table showing the correspondence relationship between the predetermined time and the automatic braking prohibition time in the vehicle control device according to the embodiment of the present invention.

[0046] Furthermore, when the vehicle is decelerating, the automatic braking prohibition time Tap, which is the time for which automatic braking is prohibited, may be lengthened as the time from when the difference (Dre - Dbs) between the relative distance Dre between the vehicle and an obstacle and the automatic braking initiation distance Dbs, which is the distance at which automatic braking is initiated at the relative speed Vre between the vehicle and the obstacle, becomes shorter than the predetermined distance Dth to when it reaches 0, increases due to the deceleration occurring in the vehicle. By doing so, when the driver intends to decelerate the vehicle and the vehicle is actually decelerating, the automatic braking prohibition time Tap also delays the time until the automatic braking is activated, thereby suppressing unnecessary automatic braking that occurs in conventional automatic braking devices.

[0047] The time from when the difference (Dre - Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs becomes shorter than the predetermined distance Dth until it reaches 0 is, for example, the predetermined time Tdw when the vehicle is decelerating. In this case, as shown in FIG. 5, the longer the predetermined time Tdw becomes due to the deceleration occurring in the vehicle, the longer the automatic braking inhibition time Tap becomes. However, if the predetermined time Tdw is excessively long, the automatic braking inhibition time Tap does not need to be increased in accordance with the length of the predetermined time Tdw. In the example of FIG. 5, when the predetermined time Tdw is 500 ms and 600 ms, the automatic braking inhibition time Tap remains at 1000 ms and does not increase. Furthermore, the automatic braking control unit 23 sequentially calculates the predetermined time Tdw and calculates the corresponding automatic braking inhibition time Tap. 5, the automatic brake control unit 23 calculates the automatic braking inhibition time Tap of 550 ms by performing linear interpolation between the automatic braking inhibition time Tap of 500 ms when the predetermined time Tdw is 200 ms, which means that 250 ms falls between the automatic braking inhibition time Tap of 500 ms, and the automatic braking inhibition time Tap of 600 ms when the predetermined time Tdw is 300 ms. Alternatively, the vehicle control device 10 may further include a calculation processing unit (not shown), which performs calculation processing of the predetermined time Tdw and the automatic braking inhibition time Tap instead of the automatic brake control unit 23.

[0048] The vehicle control device 10 may also learn the distance from the vehicle's stopped position to a stationary obstacle, and the shorter this distance tends to be, the later the timing for initiating automatic braking or the longer the automatic braking prohibition time Tap, which is the time for prohibiting automatic braking. This allows automatic braking control that provides the driver with a sense of comfort and security, since unnecessary automatic braking is suppressed as the distance between the stopped vehicle and the stationary obstacle tends to be shorter, and automatic braking is prevented from being delayed as the distance between the stopped vehicle and the stationary obstacle tends to be longer. The vehicle control device 10 may further include a learning unit (not shown), which may perform the learning instead of the automatic brake control unit 23.

[0049] FIG. 6 is a flowchart showing an example of automatic brake suppression control by the vehicle control device according to the embodiment of the present invention.

[0050] FIG. 7 is a flowchart showing an alternative process to the process enclosed by the two-dot chain line P in FIG.

[0051] Here, the operation (automatic brake suppression control) of the vehicle control device 10 according to the present embodiment described above will be described with reference to Figures 6 and 7. For ease of explanation, it is assumed that the obstacle is stationary, that is, a stationary body that does not move. In this case, the relative speed Vre between the vehicle and the obstacle means the speed of the vehicle.

[0052] As shown in Fig. 6, first, in step S1, the vehicle control device 10 determines whether the difference (Dre - Dbs) between the relative distance Dre between the vehicle and an obstacle and the automatic braking initiation distance Dbs, which is the distance at which automatic braking is initiated at the relative speed Vre between the vehicle and the obstacle, has become shorter than a predetermined distance Dth. If the difference (Dre - Dbs) is shorter than the predetermined distance Dth (YES in step S1), the process proceeds to step S2. If the difference (Dre - Dbs) is not shorter than the predetermined distance Dth (NO in step S1), the process repeats step S1 and waits until the difference (Dre - Dbs) becomes shorter than the predetermined distance Dth.

[0053] In step S2 following YES in step S1, the vehicle control device 10 determines whether or not deceleration is occurring in the vehicle. If deceleration is occurring in the vehicle (YES in step S2), the process proceeds to step S3, and if deceleration is not occurring in the vehicle (NO in step S2), the process repeats step S2 and waits until deceleration occurs in the vehicle.

[0054] Here, the processing of step S2 surrounded by a two-dot chain line P in Fig. 6 can be replaced with steps S11 and S12 surrounded by a two-dot chain line P', which are alternative processing shown in Fig. 7. The processing of steps S11 and S12, which are performed instead of the processing of step S2, will be described below with reference to Fig. 7.

[0055] In step S11, the vehicle control device 10 determines whether a predetermined time Tdw has elapsed since the difference (Dre-Dbs) between the relative distance Dre between the vehicle and the obstacle and the automatic braking start distance Dbs becomes shorter than the predetermined distance Dth. If the predetermined time Tdw has elapsed (YES in step S11), the process proceeds to step S12, and if the predetermined time Tdw has not elapsed (NO in step S11), the process repeats step S11 and waits until the predetermined time Tdw has elapsed.

[0056] In step S12 following YES in step S11, the vehicle control device 10 determines whether or not the automatic brake is operating. If the automatic brake is not operating (YES in step S12), the process proceeds to step S3, and if the automatic brake is operating (NO in step S12), the process proceeds to END, where the current control is terminated. Note that step S2, step S11, and step S12 each represent one aspect of this embodiment. In other words, step S11 and step S12 can be said to perform the determination of whether or not the vehicle is decelerating, which is performed in step S2, based on whether or not the predetermined time Tdw has elapsed and whether or not the automatic brake is operating.

[0057] Returning to Figure 6, in step S3 following a YES in step S2, or a YES in step S12 when steps S11 and S12 are performed instead of step S2, the vehicle control device 10 calculates the time from the point when the difference (Dre-Dbs) between the relative distance Dre and the automatic braking start distance Dbs becomes shorter than the predetermined distance Dth until it becomes 0.

[0058] In step S4 following step S3, the vehicle control device 10 determines the automatic braking prohibition time Tap based on the time calculated in step S3.

[0059] In step S5 following step S4, the vehicle control device 10 prohibits the operation of the automatic brake for the automatic brake prohibition time Tap. Note that although the automatic brake will not operate during the automatic brake prohibition time Tap, the setting of the predetermined distance Dth ensures safety by making it possible to avoid a collision between the vehicle and an obstacle.

[0060] In step S6 following step S5, the vehicle control device 10 determines whether the automatic braking prohibition time Tap has elapsed. If the automatic braking prohibition time Tap has elapsed (YES in step S6), the process proceeds to step S7, and if the automatic braking prohibition time Tap has not elapsed (NO in step S6), the process returns to step S5 and continues.

[0061] In step S7 following YES in step S6, the vehicle control device 10 permits the operation of the automatic brake.

[0062] After executing the process of step S7, the vehicle control device 10 ends the current control.

[0063] The vehicle control device 10 executes automatic braking suppression control according to the control flows shown in FIGS. 5 and 6, and suppresses unnecessary automatic braking.

[0064] As described above, the vehicle control device 10 according to this embodiment includes an automatic brake control unit 23 that delays the timing of initiating automatic braking or prohibits automatic braking if automatic braking is not initiated after a predetermined time Tdw has elapsed since the time point when the difference (Dre - Dbs) between the relative distance Dre between the vehicle and an obstacle and the automatic braking initiation distance Dbs, which is the distance at which automatic braking is initiated at the relative speed Vre between the vehicle and the obstacle, becomes shorter than the predetermined distance Dth. If automatic braking is not initiated after a predetermined time Tdw, which would be assumed to be the time when no deceleration is occurring, based on the time change in the difference (Dre - Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs, which reflects the deceleration occurring in the vehicle, the vehicle control device 10 determines that the vehicle is approaching an obstacle while decelerating. Based on this determination, the vehicle control device 10 suppresses unnecessary automatic braking. In other words, the vehicle control device 10 can suppress unnecessary automatic braking, which may occur when the vehicle decelerates as the vehicle approaches a surrounding obstacle.

[0065] In order to suppress the activation of the automatic brake, it is conceivable to determine whether the vehicle is decelerating based on whether the driver is braking. However, in this case, unnecessary automatic braking cannot be suppressed when the vehicle deceleration occurs due to factors other than the driver's braking. On the other hand, the vehicle control device 10 according to this embodiment can detect deceleration caused by factors other than the driver's braking, such as uphill slopes, roads with high rolling resistance coefficients, and headwinds, from the time change in the difference (Dre - Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs. Furthermore, the vehicle control device 10 can suppress unnecessary automatic braking even when deceleration occurs with the driver's accelerator pedal off, for example, in an electric vehicle equipped with a one-pedal drive function that controls the vehicle's acceleration / deceleration solely by operating the accelerator pedal.

[0066] Furthermore, in the vehicle control device 10 according to this embodiment, the obstacle is a stationary object. Therefore, the vehicle control device 10 can determine whether or not the driver intends to decelerate from a gradual change in the difference (Dre-Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs, which occurs because the obstacle is a stationary object. Therefore, the vehicle control device 10 can improve the reliability of the automatic braking suppression control, which suppresses unnecessary automatic braking operations based on the driver's intention to decelerate.

[0067] Furthermore, in the vehicle control device 10 according to this embodiment, the predetermined distance Dth is determined based on the limit distance at which a collision between the vehicle and an obstacle can be avoided when the automatic brake is activated and the variance of the limit distance. The predetermined distance Dth determined in this manner compensates for a delay in the automatic brake operation that occurs when delaying the timing at which the automatic brake is activated or when setting an automatic brake prohibition time Tap that prohibits the automatic brake operation. Therefore, the vehicle control device 10 can ensure safety by preventing the vehicle from colliding with an obstacle even if a delay in the automatic brake operation occurs.

[0068] Furthermore, in the vehicle control device 10 according to this embodiment, the minimum value of the predetermined time Tdw is the time until the automatic brake is activated when the vehicle is not decelerating. Therefore, the vehicle control device 10 distinguishes between when the vehicle is not decelerating and when the vehicle is decelerating based on the predetermined time Tdw and the operation status of the automatic brake, and activates the automatic brake as usual when the vehicle is not decelerating. In other words, the vehicle control device 10 can be configured as a system that performs characteristic automatic brake suppression control when the vehicle is decelerating, that is, when the driver intends to decelerate.

[0069] Furthermore, the vehicle control device 10 according to this embodiment determines the automatic braking inhibition time Tap based on the time from when the difference (Dre-Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs becomes shorter than the predetermined distance Dth until it reaches 0 when the vehicle is decelerating. Therefore, the vehicle control device 10 can grasp the tendency of the deceleration occurring in the vehicle from the length of time from when the difference (Dre-Dbs) becomes shorter than the predetermined distance Dth until it reaches 0, and can more appropriately set the automatic braking inhibition time Tap that enables avoidance of a collision between the vehicle and an obstacle.

[0070] Furthermore, when the vehicle is decelerating, the vehicle control device 10 according to this embodiment lengthens the automatic braking prohibition time Tap, which is the time for prohibiting automatic braking, the longer the time it takes for the difference (Dre-Dbs) between the relative distance Dre and the automatic braking initiation distance Dbs to become 0 after becoming shorter than the predetermined distance Dth, due to the deceleration occurring in the vehicle. Therefore, the vehicle control device 10 lengthens the automatic braking prohibition time Tap the longer the time it takes for the difference (Dre-Dbs) to become 0 after becoming shorter than the predetermined distance Dth, thereby suppressing unnecessary automatic braking that occurs in conventional automatic braking devices.

[0071] Furthermore, the vehicle control device 10 according to this embodiment learns the distance from the vehicle's stopped position to a stationary obstacle, and the shorter this distance tends to be, the later the timing for starting automatic braking or the longer the automatic braking prohibition time Tap for prohibiting automatic braking. Therefore, the vehicle control device 10 can perform automatic braking suppression control according to the driver based on the vehicle's stopping history, and can realize automatic braking control that gives the driver a sense of comfort and security.

[0072] Therefore, according to the vehicle control device 10 of this embodiment, unnecessary operation of the automatic brake, which may occur when the vehicle decelerates when approaching an obstacle in the vicinity, can be suppressed.

[0073] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0074] 1...camera, 3...wheel speed sensor, 5...brake control device, 10...vehicle control device, 21...obstacle detection unit, 23...automatic brake control unit, 100...vehicle control system.

Claims

1. an obstacle detection unit that detects a relative distance and a relative speed between the vehicle and an obstacle; an automatic brake control unit that activates an automatic brake when a collision prediction time calculated from the relative distance and the relative speed becomes shorter than a predetermined collision prediction time, The automatic brake control unit is a vehicle control device that delays the timing of starting the operation of the automatic brake or prohibits the operation of the automatic brake if the automatic brake is not activated after a predetermined time has elapsed from the point at which the difference between the relative distance and the distance at which the automatic brake is initiated at the relative speed becomes shorter than a predetermined distance.

2. The vehicle control device according to claim 1 , wherein the obstacle is stationary.

3. 2. The vehicle control device according to claim 1, wherein the predetermined distance is determined based on a limit distance at which a collision between the vehicle and the obstacle can be avoided when the automatic brake is activated, and a variation in the limit distance.

4. The vehicle control device according to claim 1 , wherein the minimum value of the predetermined time is the time until the automatic brake is activated when no deceleration occurs in the vehicle.

5. 2. The vehicle control device according to claim 1, wherein the time for which the automatic brake operation is prohibited is determined based on the time from when the difference becomes shorter than the predetermined distance to when the difference becomes zero when the vehicle is decelerating.

6. 2. The vehicle control device according to claim 1, wherein when the vehicle is decelerating, the time for which the automatic braking is prohibited is lengthened as the time from when the difference becomes shorter than the predetermined distance to when it becomes zero becomes longer due to the deceleration.

7. learning the distance from the position where the vehicle is stopped to the stationary obstacle; The vehicle control device according to claim 1 , wherein the timing for starting the operation of the automatic brake is delayed or the time for prohibiting the operation of the automatic brake is lengthened as the distance tends to be shorter.

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