Vehicle control device

Abstract

To provide a vehicle control device which can control an own vehicle so that a contact risk between an oncoming vehicle and the own vehicle is sufficiently reduced when a possibility that the oncoming vehicle passes a mobile object in front thereof is high on a narrow road.SOLUTION: A vehicle control device 1 is constituted so that contact risk determination conditions are alleviated in the case of establishment of a first condition for determining that a road on which an own vehicle travels is a narrow road, a second condition for determining that an oncoming vehicle approaching the own vehicle and a mobile object moving at low speed between the oncoming vehicle and the own vehicle exist within a predetermined range, a third condition for determining that a possibility that the oncoming vehicle reaches a rear end of the mobile object is high before the own vehicle reaches a front end of the mobile object, and a fourth predetermined condition regarding a relative movement of the oncoming vehicle and the mobile object.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device that, when a predetermined condition is met, initiates risk reduction control to control the vehicle so as to reduce the risk of contact between the vehicle and a target (the probability of the two coming into contact, or the damage that occurs if the two come into contact). [Background technology]

[0002] A vehicle control device has been proposed that initiates risk reduction control to control the host vehicle so as to reduce the risk of contact when a condition for determining that the risk of contact between the host vehicle and an oncoming vehicle is high is met in a situation where the width of the road on which the host vehicle and the oncoming vehicle are traveling is relatively narrow (see, for example, Patent Document 1 below).The vehicle control device of Patent Document 1 (hereinafter referred to as the "conventional device") is capable of executing, as risk reduction control, notification control that issues a predetermined alarm to the driver of the host vehicle, braking control that brakes the host vehicle, and automatic steering control that steers the host vehicle so as to move away from the oncoming vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2014 / 027420 Summary of the Invention

[0004] Incidentally, on a narrow road, a situation may arise in which an oncoming vehicle overtakes a moving object moving at a low speed in the section ahead of the oncoming vehicle (the area between the oncoming vehicle and the host vehicle). In this situation, since the width of the road on which the host vehicle and the oncoming vehicle are traveling is relatively narrow, there is a high possibility that the oncoming vehicle will significantly intrude into the area ahead of the host vehicle when overtaking the moving object. In this case, it is highly likely that it will be difficult to steer the host vehicle to avoid the oncoming vehicle. Therefore, on a narrow road, in a situation in which an oncoming vehicle is overtaking a moving object, it is preferable to start braking the host vehicle as early as possible (for example, before the oncoming vehicle starts to overtake the moving object).

[0005] In the conventional device, the initiation condition for risk reduction control is established when the time obtained by dividing the distance between the host vehicle and an oncoming vehicle by the relative speed is equal to or less than a threshold value. In other words, the initiation condition for risk reduction control is unrelated to the behavior of the oncoming vehicle or the moving object. In other words, the conventional device cannot adjust the initiation timing of risk reduction control according to the likelihood that the oncoming vehicle will overtake the moving object on a narrow road. Therefore, the initiation condition may be established after the oncoming vehicle begins to overtake the moving object. In this case, there is a risk that the effect obtained by executing the risk reduction control (the effect of reducing the risk of contact between the host vehicle and the oncoming vehicle) will be minimal.

[0006] One of the objects of the present invention is to provide a vehicle control device that can control a vehicle so as to sufficiently reduce the risk of contact between an oncoming vehicle and the vehicle when there is a high possibility that the oncoming vehicle will overtake a moving object in front of the vehicle on a narrow road.

[0007] In order to solve the above problems, the vehicle control device (1) of the present invention comprises: When a contact risk determination condition is established, which is a condition for determining that there is a high risk of contact between the host vehicle and a target that exists within a predetermined range in the host vehicle's direction of travel, the vehicle control device executes risk reduction control to control the host vehicle so as to reduce the risk of contact. The vehicle control device is configured to relax the contact risk determination condition when a first condition is established for determining that the road on which the host vehicle is traveling is narrow, a second condition is established for determining that an oncoming vehicle approaching the host vehicle and a moving body moving at a low speed between the oncoming vehicle and the host vehicle are present within the predetermined range, a third condition is established for determining that the oncoming vehicle is likely to reach the rear end of the moving body before the host vehicle reaches the front end of the moving body, and a predetermined fourth condition is established regarding the relative movement between the oncoming vehicle and the moving body.

[0008] In a vehicle control device according to one embodiment of the present invention, the fourth condition is met when the speed difference between the oncoming vehicle and the moving body exceeds a predetermined first threshold and the acceleration of the oncoming vehicle exceeds a second threshold, or when the speed difference is equal to or less than the first threshold and the acceleration of the oncoming vehicle exceeds a predetermined third threshold.

[0009] In a vehicle control device described in another aspect of the present invention, the contact risk judgment condition is met when the predicted time until contact between the host vehicle and the oncoming vehicle is less than or equal to a fourth threshold, and the value assigned to the fourth threshold is determined depending on the relative speed between the host vehicle and the oncoming vehicle, and when at least one of the first condition to the fourth condition is not met and the relative speed is a first speed, a first predetermined value is assigned to the fourth threshold, and when the first condition to the fourth condition are met and the relative speed is a second speed slower than the first speed, a second predetermined value greater than the first predetermined value is assigned to the fourth threshold.

[0010] In another aspect of the vehicle control device of the present invention, the contact risk judgment condition is met when the predicted time until contact between the host vehicle and the oncoming vehicle is equal to or less than a fourth threshold, and the value assigned to the fourth threshold is determined according to an overlap ratio, which is the degree of overlap between the area through which the host vehicle is predicted to pass and the area through which the oncoming vehicle is predicted to pass, and when at least one of the first condition to the fourth condition is not met and the overlap ratio is a first overlap ratio, a first predetermined value is assigned to the fourth threshold, and when the first condition to the fourth condition are met and the overlap ratio is a second overlap ratio smaller than the first overlap ratio, a second predetermined value greater than the first predetermined value is assigned to the fourth threshold.

[0011] In a vehicle control device according to another aspect of the present invention, when the distance between the moving body and the host vehicle is equal to or less than a predetermined fifth threshold, the vehicle speed of the host vehicle is limited to a predetermined upper limit value or less.

[0012] As described above, when the first to fourth conditions are satisfied, the vehicle control device according to the present invention determines that there is a high possibility that an oncoming vehicle will overtake the moving object on a narrow road, and relaxes the start condition for the risk reduction process (contact risk determination condition). That is, in this scenario, the timing for starting execution of risk reduction control is advanced. This sufficiently reduces the risk of contact between the host vehicle and the oncoming vehicle. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a block diagram of a vehicle control device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing the overlap ratio. [Figure 3] FIG. 3 is a plan view showing a scene where an oncoming vehicle is likely to overtake a moving object on a narrow road. [Figure 4] FIG. 4 is a flowchart of a program executed by the CPU to realize the functions of the vehicle control device. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1, a vehicle control device 1 according to one embodiment of the present invention is applied to a vehicle V0 (hereinafter referred to as "host vehicle") equipped with an automatic driving function. The vehicle control device 1 has a function (risk reduction function) for executing risk reduction control that controls the host vehicle (announcement device 30 and braking device 40) so as to reduce the risk of contact between the host vehicle and an oncoming vehicle V1 when the automatic driving function is disabled.

[0015] (Specific Configuration) As shown in FIG. 1, the vehicle control device 1 includes an ECU 10, an on-vehicle sensor 20, a notification device 30, and a braking device 40.

[0016] The ECU 10 includes a CPU 10a, a ROM 10b, a RAM 10c, a timer 10d, etc. The ECU 10 is connected to other ECUs via a CAN (communication line).

[0017] The on-board sensor 20 includes a camera 21 and a millimeter wave radar 22 .

[0018] The camera 21 includes an imaging device and an image analysis device. The imaging device incorporates, for example, a CCD. The imaging device is installed at the front of the vehicle and faces the front of the vehicle. The imaging device captures images of the front of the vehicle at a predetermined frame rate to acquire foreground images (image data). The image analysis device analyzes the foreground images to recognize (identify) targets present within the field of view of the imaging device. The image analysis device recognizes vehicles such as passenger cars and trucks. The image analysis device also recognizes moving objects such as pedestrians and bicycles. In other words, the image recognition device can distinguish between vehicles and moving objects. The image analysis device also recognizes lane marks (such as dividing lines on the road R and guardrails) in the foreground image and acquires lane mark information including the coordinates and extension direction of the lane marks in the image. The image analysis device provides these calculation results to the ECU 10.

[0019] The millimeter-wave radar 22 includes a transmitter / receiver and a signal processor. The transmitter / receiver emits millimeter-wave band radio waves (hereinafter referred to as "millimeter waves") ahead of the vehicle and receives millimeter waves (reflected waves) reflected by three-dimensional objects located within that area. The signal processor acquires various information about each reflection point of the millimeter waves based on physical quantities related to the emitted waves and the reflected waves. For example, the signal processor calculates the position (relative position (distance and direction)) of each reflection point relative to the vehicle. The signal processor also calculates the speed of each reflection point relative to the vehicle (change per unit time in the distance between the vehicle and the reflection point (relative speed)). The calculation result (reflection point distribution data (data including relative position and relative speed)) is then provided to the ECU 10.

[0020] The image capturing range of the camera 21 and the area where millimeter waves are emitted by the millimeter-wave radar 22 overlap. In the following description, the overlapping area between the two is referred to as the field of view FOV of the target detection sensor DS. In a planar view, the field of view FOV is fan-shaped. Based on fusion information that combines information acquired from the camera 21 and information acquired from the millimeter-wave radar 22, the ECU 10 can acquire information about each target present within the field of view FOV (such as the type of target (vehicle, moving object, etc.), the position of the target relative to the host vehicle (relative position), and the speed of the target relative to the host vehicle (relative speed (vector))).

[0021] The on-vehicle sensors 20 further include a vehicle speed sensor 23. The vehicle speed sensor 23 acquires the speed sp0 of the host vehicle (speed (scalar) relative to the road R) based on the number of wheel rotations per unit time. The vehicle speed sensor 23 then provides the speed sp0 to the ECU 10.

[0022] The notification device 30 includes an image display device and an audio device. The image display device displays an image in accordance with an image display command received from the ECU 10. The audio device reproduces audio in accordance with an audio reproduction command received from the ECU 10.

[0023] The braking device 40 applies braking force to the wheels. The braking device 40 includes a brake caliper, a brake ECU, etc. The brake ECU controls the brake caliper based on a command (a target value of braking force (deceleration)) acquired from another ECU. This causes the host vehicle to brake.

[0024] (Risk Reduction Function) When the ignition switch of the host vehicle is on, the ECU 10 sequentially acquires various information from the on-board sensors 20 and performs various calculations based on this information. Specifically, the ECU 10 detects a target OB located within the field of view (FOV) based on the fusion information. Then, the ECU 10 predicts the time TTC until contact between the host vehicle and the target OB. Specifically, the ECU 10 acquires the distance ΔD between the host vehicle and the target OB and the relative speed rv of the target OB relative to the host vehicle. The ECU 10 obtains the value obtained by dividing the distance ΔD by the relative speed rv as the predicted time TTC. When the following condition X is satisfied, the ECU 10 determines that there is a high risk of contact between the host vehicle and the target OB and executes risk reduction control to control the host vehicle so as to reduce the risk of contact. Note that the condition X is also referred to as a "contact risk determination condition" or a "start condition for risk reduction control," etc. [Condition X]: The predicted time TTC is equal to or less than a threshold value TTCth (TTC≦TTCth). The ECU 10 can execute notification control and automatic braking control as risk reduction control.

[0025] (Notification Control) The ECU 10 displays an icon indicating that there is a high risk of contact with the object OB to the driver, and transmits a command to the notification device 30 to play an alarm sound.

[0026] (Automatic Braking Control) The ECU 10 transmits a command to decelerate the vehicle (a target value of the deceleration) to the braking device 40 .

[0027] Here, the threshold value TTCth is not a fixed value, but a value depending on the situation is assigned to the threshold value TTCth as will be described below. The ECU 10 executes the following calculation to determine the value to be assigned to the threshold value TTCth.

[0028] As shown in Figure 2, ECU10 calculates a predicted trajectory TR0, which is an area through which the host vehicle is predicted to pass, and a predicted trajectory TRob, which is an area through which a target OB (an oncoming vehicle V1 in the example of Figure 2) is predicted to pass.

[0029] Specifically, the ECU 10 acquires the direction dir0 of the host vehicle with respect to the road R based on the lane mark information. The ECU 10 also acquires the speed sp0 from the vehicle speed sensor 23. The ECU 10 acquires the speed sp0 and the direction dir0 as the speed v0 (vector) of the host vehicle with respect to the road R. The ECU 10 acquires the trajectory of the host vehicle within the most recent predetermined period based on changes in the speed v0 (time-series data of the speed v0 acquired within the most recent predetermined period), and acquires a band-like area extending the trajectory forward as the predicted trajectory TR0. Note that the ECU 10 may acquire the predicted trajectory TR0 based on information acquired from a steering angle sensor, a yaw rate sensor, etc. (not shown) in addition to the lane mark information.

[0030] Furthermore, the ECU 10 acquires the velocity vob of the target OB (the velocity (speed, direction) of the target OB relative to the road R) by performing a vector calculation to subtract the velocity v0 of the host vehicle from the relative velocity rv between the host vehicle and the target OB. The ECU 10 acquires the predicted trajectory TRob based on the change in the velocity vob. The band width of the predicted trajectory TR0 is equal to the vehicle width of the host vehicle, and the band width of the predicted trajectory TRob is equal to the width of the target OB.

[0031] The ECU 10 obtains the value obtained by dividing the width Δw of the overlapping portion between the predicted trajectory TR0 and the predicted trajectory TRob by the vehicle width of the host vehicle as the overlap ratio wr. Note that if the width Δw of the overlapping portion between the predicted trajectory TR0 and the predicted trajectory TRob is not constant (if the two trajectories are not parallel), the ECU 10 obtains the value obtained by dividing the maximum value of the width Δw by the vehicle width of the host vehicle as the overlap ratio wr.

[0032] The ECU 10 determines the value to be assigned to the threshold TTCth according to the relative speed rv and the overlap ratio wr. The ECU 10 assigns a larger value to the threshold TTCth as the relative speed rv increases. In other words, the start timing of the risk reduction control is advanced. The ECU 10 also assigns a larger value to the threshold TTCth as the overlap ratio wr increases. In other words, the start timing of the risk reduction control is advanced as the overlap ratio wr increases. For example, the ECU 10 assigns to the threshold TTCth a value obtained according to the following equation (1) defined using the coefficient k1, the relative speed rv, and the overlap ratio wr. TTCth=rv×wr×k1 …(1) In addition, ECU10 may obtain values corresponding to the current relative speed rv and lap ratio wr by referring to a map (not shown) that specifies the relationship between the "relative speed rv and lap ratio wr" and the "value to be assigned to the threshold value TTCth."

[0033] As shown in Fig. 3, a situation may arise where an oncoming vehicle V1 overtakes a moving object M moving at a low speed on a narrow road. On a narrow road, it is highly likely that it will be difficult to steer the vehicle to avoid the oncoming vehicle V1. Therefore, in such a situation (particularly, in a situation where the oncoming vehicle V1 overtakes the moving object M despite the fact that the vehicle and the oncoming vehicle V1 are in close proximity to each other), it is preferable to brake the vehicle as early as possible.

[0034] Therefore, when there is a high possibility that the oncoming vehicle V1 will overtake the moving object M on a narrow road, the ECU 10 reduces the risk of contact between the oncoming vehicle V1 and the own vehicle in the manner described below.

[0035] Specifically, the ECU 10 sequentially executes a process (scene determination process) to determine whether "the host vehicle, the oncoming vehicle V1, and the moving object M (hereinafter referred to as the "host vehicle, etc.") are traveling on a narrow road and whether there is a high possibility that the oncoming vehicle V1 will overtake the moving object M ahead of the host vehicle." The scene determination process includes the following first to fourth processes.

[0036] (First Process) The first process is a process for determining whether or not the road R on which the vehicle or the like is traveling is a narrow road (narrow road determination process). The ECU 10 acquires the width W of the road R based on lane mark information (the distance between a pair of left and right lane marks in the foreground image). The ECU 10 determines that the road R is a narrow road when the following condition A is met: [Condition A]: The width W is equal to or smaller than the threshold value Wth. The threshold value Wth is, for example, about 2.5 times the vehicle width of the host vehicle. The ECU 10 may also obtain the width W from map information of a navigation system (not shown). The ECU 10 may also determine that the road R is narrow when there is no center line.

[0037] (Second Processing) When the condition A is satisfied, the ECU 10 executes a second processing, which includes an oncoming vehicle detection processing and a moving object detection processing.

[0038] (Oncoming vehicle detection process) The oncoming vehicle detection process is a process for determining whether or not an oncoming vehicle V1 is present. When the ECU 10 detects the presence of a vehicle ahead of the host vehicle based on the fusion information, it acquires the speed v1 (speed sp1 and direction dir1) of the vehicle based on the relative speed vr01 of the vehicle with respect to the host vehicle and the speed v0 of the host vehicle. The ECU 10 determines that an oncoming vehicle V1 is present when the following condition B1 is met: [Condition B1]: The speed sp1 exceeds a threshold sp1th, and the direction dir1 is within a predetermined angle range θ1 on the host vehicle side (sp1>sp1th, dir1εθ1).

[0039] (Moving object detection process) The moving object detection process is a process for determining whether or not a moving object M (a slow-moving object) is present. When the ECU 10 detects, based on the fusion information, that a moving object (pedestrian, bicycle, etc.) is present between the host vehicle and the oncoming vehicle V1 in the section ahead of the oncoming vehicle V1, it acquires the speed vm (speed spm, direction dirm) of the moving object based on the relative speed vrm of the moving object with respect to the host vehicle and the speed v0 of the host vehicle. The ECU 10 determines that the moving object M is present when the following condition B is met: [Condition B2]: The speed spm is greater than "0" and is equal to or less than the threshold spmth, and the direction dirm is within a predetermined angle range θm opposite to the direction dir0 of the host vehicle. <spm≦spmth,dirm∈θm) The ECU 10 determines that the condition B is satisfied when the conditions B1 and B2 are satisfied.

[0040] (Third Process) When condition B is satisfied, ECU 10 executes third process. The third process is a process for determining whether condition C related to the positional relationship of the host vehicle and the like is satisfied. The third process includes the following first approach determination process, first-arrival determination process, and second approach determination process.

[0041] (First Proximity Determination Process) The first proximity determination process is a process for determining whether the host vehicle and the oncoming vehicle V1 are in close proximity to each other. The ECU 10 acquires the distance ΔD01 between the host vehicle and the oncoming vehicle V1 based on the fusion information. The ECU 10 determines that the host vehicle and the oncoming vehicle V1 are in close proximity to each other if the following condition C1 is met: [Condition C1]: The distance ΔD01 is equal to or less than a threshold value ΔD01th (ΔD01≦ΔD01th).

[0042] (First-arrival determination process) The first-arrival determination process is a process for determining whether or not there is a high possibility that the oncoming vehicle V1 will reach the rear end of the moving object M before the host vehicle reaches the front end of the moving object M. The ECU 10 acquires the time Δt0m until the host vehicle reaches the front end of the moving object M based on the distance ΔD0m between the host vehicle and the moving object M and the relative speed rv0m between the host vehicle and the moving object M. The ECU 10 also acquires the time Δt1m until the oncoming vehicle V1 reaches the rear end of the moving object M based on the distance ΔD1m between the oncoming vehicle V1 and the moving object M and the relative speed rv1m between the oncoming vehicle V1 and the moving object M. The ECU 10 determines that there is a high possibility that the oncoming vehicle V1 will reach the rear end of the moving object M before the host vehicle reaches the front end of the moving object M when the following condition C2 is established: [Condition C2]: The time Δt1m is equal to or less than the value obtained by adding a predetermined margin Δt to the time Δt0m (Δt1m≦Δt0m+Δt). If the condition C2 is not satisfied, the ECU 10 determines that there is a high possibility that the host vehicle will pass by the side of the moving object M before the oncoming vehicle V1, and therefore that there is a low possibility that the oncoming vehicle V1 will overtake the moving object M ahead of the host vehicle. Alternatively, for simplicity, the ECU 10 may determine that the condition C2 is satisfied if the distance ΔD1m is smaller than the distance ΔD0m.

[0043] (Second proximity determination process) The second proximity determination process is a process for determining whether or not the oncoming vehicle V1 and the moving body M are in close proximity to each other. The ECU 10 acquires the distance ΔD1m between the oncoming vehicle V1 and the moving body M based on the fusion information. The ECU 10 determines that the host vehicle and the oncoming vehicle V1 are in close proximity to each other when the following condition C3 is met: [Condition C3]: The distance ΔD1m is equal to or less than a threshold value ΔD1mth (ΔD1m≦ΔD1mth).

[0044] If the conditions C1 to C3 are satisfied, the ECU 10 determines that the condition C is satisfied.

[0045] (Fourth Process) When the condition C is satisfied, the ECU 10 executes the fourth process. The fourth process is a process for determining whether the condition D regarding the speed relationship (movement) between the oncoming vehicle V1 and the moving body M is satisfied. The third process includes the following speed difference determination process, deceleration determination process, and acceleration determination process.

[0046] (Speed Difference Determination Process) The speed difference determination process is a process for determining whether the speed difference Δsp (=sp1-spm) between the oncoming vehicle V1 and the moving body M is large to a certain extent (large enough to indicate that the driver of the oncoming vehicle V1 intends to overtake the moving body M). The ECU 10 determines that the speed difference Δsp is large to a certain extent when the following condition D1 is satisfied: [Condition D1]...The speed difference Δsp exceeds the threshold value Δspth (sp1-spm>Δspth).

[0047] Here, even if the speed difference Δsp is relatively large, if the oncoming vehicle V1 is decelerating, there is a low possibility that the oncoming vehicle V1 will overtake the moving object M. On the other hand, even if the speed difference Δsp is not that large, if the oncoming vehicle V1 is accelerating, there is a possibility that the oncoming vehicle V1 will overtake the moving object M. Therefore, the ECU 10 executes the following deceleration determination process or acceleration determination process depending on whether the condition D1 is satisfied.

[0048] (Deceleration Determination Process) The deceleration determination process is a process for determining whether the oncoming vehicle V1 is decelerating. The ECU 10 executes the deceleration determination process when the condition D1 is satisfied. The ECU 10 acquires the acceleration a1 (acceleration relative to the road R) of the oncoming vehicle V1 based on the change in the speed sp1 of the oncoming vehicle V1 (time-series data of the speed sp1 within the most recent predetermined time). The ECU 10 determines that the oncoming vehicle V1 is decelerating when the following condition D2 is satisfied. [Condition D2]: The acceleration a1 is equal to or less than a negative threshold value na1th (a1≦na1th).

[0049] (Acceleration Determination Process) The deceleration determination process is a process for determining whether the oncoming vehicle V1 is accelerating. The ECU 10 executes the acceleration determination process when the condition D1 is not satisfied. The ECU 10 determines that the oncoming vehicle V1 is accelerating when the following condition D3 is satisfied. [Condition D3]...The acceleration a1 exceeds the positive threshold pa1th (a1>pa1th).

[0050] The ECU 10 determines that the condition D is satisfied when the condition D1 is satisfied and the condition D2 is not satisfied (when the speed difference Δsp is large to a certain extent and the oncoming vehicle V1 is not decelerating).The ECU 10 also determines that the condition D is satisfied when the condition D1 is not satisfied and the condition D3 is satisfied (when the speed difference Δsp is not so large but the oncoming vehicle V1 is accelerating).

[0051] If conditions A to D are satisfied, the ECU 10 determines that "the host vehicle, the oncoming vehicle V1, and the moving object M are traveling on a narrow road, and there is a high possibility that the oncoming vehicle V1 will overtake the moving object M ahead of the host vehicle." In this case, in order to determine the level of risk of contact between the host vehicle and the oncoming vehicle V1 in a predetermined area RLX near the oncoming vehicle V1, as shown in Fig. 3, the ECU 10 determines the threshold value TTCth based on the following equation (2) instead of equation (1). That is, the relative speed rv01 between the host vehicle and the oncoming vehicle V1 and the overlap ratio wr01 between the host vehicle and the oncoming vehicle V1 are substituted for the relative speed vr and the overlap ratio wr in equation (2). TTCth=rv×wr×k2 …(2) Here, coefficient k2 in equation (2) is greater than coefficient k1 in equation (1). Therefore, the threshold TTCth is larger when equation (2) is used than when equation (1) is used. In other words, the conditions for starting risk reduction control (conditions for determining that the risk of contact is high) are relaxed in the region RLX. In plan view, region RLX has a rectangular shape extending in the longitudinal direction of road R. The width of region RLX is equal to the width W of road R. One end and the other end in the longitudinal direction of region RLX are located near the windshield of oncoming vehicle V1 and near the front end of moving object M, respectively. Furthermore, ECU 10 may determine TTCth by referring to a map (not shown).

[0052] (Speed Limit Control) In addition, when conditions A to D are met, execution of the following speed limit control is permitted. Specifically, the ECU 10 controls the braking device 40 so that the speed sp0 of the host vehicle within an area SPL near the moving object M is equal to or less than an upper limit value sp0th. Here, the area SPL is a rectangle extending in the longitudinal direction of the road R in a plan view, and a portion of it overlaps with the area RLX. The width of the area SPL is equal to the width of the road R. One end and the other end in the longitudinal direction of the area SPL are located near the front end of the oncoming vehicle V1 and ahead of the moving object M in the traveling direction, respectively. The distance Δd between the other end and the front end of the moving object M is set to a predetermined value Δdth. In other words, when the distance ΔD0m between the host vehicle and the moving object M is equal to or less than the predetermined value Δdth, the ECU 10 executes the speed limit control. Note that the deceleration of the host vehicle due to the speed limit control is gentler than the deceleration of the host vehicle due to automatic braking control. In the region S where the region RLX and the region SPL overlap, if the condition X is not satisfied, the speed limit control is executed, and the notification control and the automatic braking control are not executed. On the other hand, in the region S, if the condition X is satisfied, the notification control and the automatic braking control are executed, and the speed limit control (gradual deceleration) is not executed.

[0053] Next, with reference to FIG. 5, a program PR1 executed by the CPU 10a (hereinafter simply referred to as "CPU") of the ECU 10 to realize the above-mentioned functions of the vehicle control device 1 will be described.

[0054] (Program PR1) The CPU starts executing the program PR1 at a predetermined cycle. The CPU starts executing the program PR1 from step 100 and proceeds to step 101.

[0055] In step 101, the CPU determines whether condition A is met. If the CPU determines that condition A is met (101: Yes), the CPU proceeds to step 102. On the other hand, if the CPU does not determine that condition A is met (101: No), the CPU proceeds to step 111, which will be described later.

[0056] In step 102, the CPU determines whether condition B is met. If the CPU determines that condition B is met (102: Yes), the CPU proceeds to step 103. On the other hand, if the CPU does not determine that condition B is met (102: No), the CPU proceeds to step 111, which will be described later.

[0057] In step 103, the CPU determines whether condition C is met. If the CPU determines that condition C is met (103: Yes), the CPU proceeds to step 104. On the other hand, if the CPU does not determine that condition C is met (103: No), the CPU proceeds to step 111, which will be described later.

[0058] The CPU determines whether condition D1 is met in step 104. If the CPU determines that condition D1 is met (104: Yes), the process proceeds to step 105. On the other hand, if the CPU does not determine that condition D1 is met (104: No), the process proceeds to step 106, which will be described later.

[0059] The CPU determines whether condition D2 is met in step 105. If the CPU determines that condition D2 is met (105: Yes), the CPU proceeds to step 112, which will be described later. On the other hand, if the CPU does not determine that condition D2 is met (105: No), the CPU proceeds to step 107, which will be described later.

[0060] The CPU determines whether condition D3 is met in step 106. If the CPU determines that condition D3 is met (106: Yes), the process proceeds to step 107. On the other hand, if the CPU does not determine that condition D3 is met (106: No), the process proceeds to step 107, which will be described later.

[0061] In step 107, the CPU determines whether or not the host vehicle is located within the area SPL. If the CPU determines that the host vehicle is located within the area SPL (107: Yes), the CPU proceeds to step 108. On the other hand, if the CPU does not determine that the host vehicle is located within the area SPL (107: No), the CPU proceeds to step 111.

[0062] The CPU executes speed limit control in step 108. That is, the CPU sends a deceleration command to the braking device 40 so that the speed sp0 of the host vehicle becomes equal to or less than the upper limit value sp0th. Next, the CPU proceeds to step 109.

[0063] In step 109, the CPU determines whether or not the host vehicle is located within the region RLX. If the CPU determines that the host vehicle is located within the region RLX (109: Yes), the CPU proceeds to step 110. On the other hand, if the CPU does not determine that the host vehicle is located within the region RLX (109: No), the CPU proceeds to step 111.

[0064] In step 110, the CPU assigns the value obtained according to the equation (2) to the threshold value TTCth. Then, the CPU proceeds to step 113.

[0065] In step 111, the CPU assigns the value obtained according to the arithmetic expression (1) to the threshold value TTCth. Then, the CPU proceeds to step 113. In step 112, the CPU executes the same process as in step 111.

[0066] In step 113, the CPU determines whether condition X is met. If the CPU determines that condition X is met (113: Yes), the CPU proceeds to step 114. On the other hand, if the CPU does not determine that condition X is met (113: No), the CPU proceeds to step 115.

[0067] The CPU executes risk reduction control in step 114. Then, the ECU 10 proceeds to step 115, where it ends the execution of the program PR1.

[0068] (Effect) When conditions A to D are satisfied, the vehicle control device 1 determines that there is a high possibility that the oncoming vehicle V1 will overtake the moving body M on a narrow road, and relaxes condition X as a condition for starting risk reduction control. That is, in this scenario, the timing for starting execution of risk reduction control is advanced. This sufficiently reduces the risk of contact between the host vehicle and an oncoming vehicle.

[0069] <Modification> Of the functions of the vehicle control device 1, the function of executing the speed limit control may be omitted. [Explanation of symbols]

[0070] 1...vehicle control device, 10...ECU, 20...vehicle-mounted sensor, 30...alarm device, 40...braking device

Claims

1. A vehicle control device that executes risk reduction control to control a host vehicle so as to reduce a risk of contact when a contact risk determination condition is satisfied, the condition being a condition for determining that there is a high risk of contact between the host vehicle and a target that exists within a predetermined range in a traveling direction of the host vehicle, a first condition for determining that the road on which the host vehicle is traveling is a narrow road; an oncoming vehicle approaching the host vehicle within the predetermined range, and the oncoming vehicle; a second condition for determining that a moving object moving at a low speed exists between the host vehicle and the vehicle; and a third condition for determining that there is a high possibility that the oncoming vehicle will reach the rear end of the moving body before the host vehicle reaches the front end of the moving body; a fourth predetermined condition regarding relative movement between the oncoming vehicle and the moving object; The vehicle control device is configured to relax the contact risk determination condition when the following condition is met.

2. 2. The vehicle control device according to claim 1, A vehicle control device configured so that the fourth condition is met when the speed difference between the oncoming vehicle and the moving body exceeds a predetermined first threshold and the acceleration of the oncoming vehicle exceeds a second threshold, or when the speed difference is equal to or less than the first threshold and the acceleration of the oncoming vehicle exceeds a predetermined third threshold.

3. 2. The vehicle control device according to claim 1, The contact risk determination condition is met when a predicted time until contact between the host vehicle and the oncoming vehicle is equal to or less than a fourth threshold value, a value assigned to the fourth threshold value is determined according to a relative speed between the host vehicle and the oncoming vehicle; When at least one of the first condition to the fourth condition is not satisfied and the relative speed is a first speed, a first predetermined value is assigned to the fourth threshold value, When the first condition to the fourth condition are satisfied and the relative speed is a second speed that is slower than the first speed, a second predetermined value that is greater than the first predetermined value is assigned to the fourth threshold value. A vehicle control device configured as above.

4. 2. The vehicle control device according to claim 1, The contact risk determination condition is met when a predicted time until contact between the host vehicle and the oncoming vehicle is equal to or less than a fourth threshold value, a value to be assigned to the fourth threshold is determined according to an overlap ratio, which is a degree of overlap between an area in which the host vehicle is predicted to pass and an area in which the oncoming vehicle is predicted to pass; When at least one of the first condition to the fourth condition is not satisfied and the overlap rate is a first overlap rate, a first predetermined value is assigned to the fourth threshold value; When the first condition to the fourth condition are satisfied and the overlap rate is a second overlap rate that is smaller than the first overlap rate, a second predetermined value that is larger than the first predetermined value is assigned to the fourth threshold value. A vehicle control device configured as above.

5. 2. The vehicle control device according to claim 1, The vehicle control device is configured to limit the speed of the host vehicle to a predetermined upper limit value or less when the distance between the moving object and the host vehicle is equal to or less than a predetermined fifth threshold value.

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