Vehicle driving assistance systems

Abstract

To provide a vehicle operation support device capable of utilizing information on a recognized speed limit with improved efficiency.SOLUTION: When a collision determination condition is met for a predicted collision between an own vehicle HV and a target, an operation support ECU 10 executes a collision avoidance support operation to prevent a collision between the own vehicle and the target. The operation support ECU recognizes a speed limit applied to a lane in which the own vehicle is traveling. When the current speed limit, newly recognized at the present time, is lower than the previous speed limit recognized up to just before the present time, the operation support ECU modifies the collision determination condition to make the same more likely to be met, allowing the collision avoidance support operation to be executed at an earlier timing compared to when the current speed limit is not lower than the previous speed limit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle driving support device that performs driving support control to reduce the possibility of a host vehicle colliding with an object target.

Background Art

[0002] Conventional devices acquire image data by photographing a scene in front of the host vehicle using an in-vehicle camera, and recognize road signs from the image data. Further, conventional devices extract a speed limit (maximum speed) from the recognized road signs and notify the driver of the host vehicle of the speed limit (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] However, since conventional devices only notify the speed limit, the driver of the host vehicle may not immediately notice that the speed limit has changed. For example, when the speed limit drops significantly and the preceding vehicle decelerates significantly in response to the drop in the speed limit, if the driver of the host vehicle does not notice the drop in the speed limit, the timing of activating the brakes will be delayed. As a result, there is a risk that the host vehicle will approach the preceding vehicle extremely closely. Conventional devices have not been able to effectively utilize the information about the recognized speed limit in such a situation.

[0005] The present invention has been made to solve such problems. That is, one object of the present invention is to provide a vehicle driving support device that can more effectively utilize the information about the recognized speed limit.

[0006] One aspect of the vehicle driving assistance system of the present invention includes a controller (10, 50, 70) configured to perform collision avoidance assistance operations to avoid a collision between the vehicle and a target when a collision determination condition is met (S440, S460) that is met when it is predicted that the vehicle will collide with a target.

[0007] Furthermore, the controller, The vehicle recognizes the speed limit applicable to the lane in which it is traveling, When the current speed limit, which is the newly recognized speed limit at the present moment (S210), is lower than the past speed limit recognized immediately before the present moment (S250: Yes), the collision judgment condition is changed to a condition that makes it easier to satisfy the collision avoidance support operation at an earlier timing compared to when the current speed limit is not lower than the past speed limit (S250: No). It is structured in this way.

[0008] If the newly recognized speed limit (current speed limit) is lower than the previously recognized speed limit (past speed limit), there is a high probability that the preceding vehicle will decelerate rapidly. Therefore, in such cases, the above configuration changes the collision detection conditions to conditions that make it easier for the collision detection conditions to be met so that the collision avoidance support action is executed at an earlier timing. More specifically, the collision detection conditions are those that are met when the collision index value, which indicates the possibility of the vehicle colliding with a target, reaches a threshold. In this case, the collision detection conditions can be changed to conditions that make it easier for the collision detection conditions to be met by changing the threshold or correcting the collision index value. For example, if the collision detection conditions are those that are met when the "collision time as a collision index value," which is the time required for the vehicle to collide with a target, falls below the collision detection time threshold, the collision detection conditions can be changed to conditions that make it easier for the collision detection conditions to be met by increasing the collision detection time threshold or correcting the collision time to a smaller value.

[0009] As a result, even if the driver of the vehicle overlooks the reduction in the speed limit and is slow to react to the sudden deceleration of the preceding vehicle, the collision detection conditions are met early and collision avoidance support actions are executed early, preventing the vehicle from getting too close to the preceding vehicle.

[0010] In the above description, to aid in understanding the present invention, the names and / or reference numerals used in the embodiments described later are indicated in parentheses for the components of the invention corresponding to those embodiments. However, the components of the present invention are not limited to the embodiments defined by the above names and / or reference numerals. The present invention also extends to vehicle driving assistance methods and programs thereof. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram of a vehicle driving assistance device according to an embodiment of the present invention. [Figure 2] This is the routine executed by the CPU of the driver assistance ECU shown in Figure 1. [Figure 3] This is the routine executed by the CPU of the driver assistance ECU shown in Figure 1. [Figure 4] This is the routine executed by the CPU of the driver assistance ECU shown in Figure 1. [Figure 5] Figure 1 shows the screens displayed on the setting input device, where (A) is the menu screen, (B) is the collision avoidance support timing selection screen, (C) is the corrected collision avoidance support timing selection screen, (D) is the speed limit reduction threshold selection screen, and (E) is the support timing correction period length selection screen. [Figure 6] This is the routine executed by the CPU of the driver assistance ECU shown in Figure 1. [Modes for carrying out the invention]

[0012] An embodiment of the present invention, the "vehicle driving assistance device DS (hereinafter referred to as "device DS")", comprises the components shown in Figure 1 and is applied to (mounted on) the vehicle HV. The vehicle HV may be any of the following: a vehicle powered by an internal combustion engine, a vehicle powered by an electric motor (i.e., an electric vehicle), or a hybrid vehicle.

[0013] In this specification, "ECU" refers to an electronic control unit (control unit) that includes a microcomputer comprising a CPU (processor), ROM, RAM, data-writable non-volatile memory, and interfaces. An ECU is also referred to as a controller or computer. The multiple ECUs shown in Figure 1 are connected to each other via a CAN (Controller Area Network) to enable information exchange. Some or all of these multiple ECUs may be integrated into a single ECU.

[0014] The driver assistance ECU 10 uses the components shown in Figure 1 to perform driver assistance control, also known as "collision avoidance support control" or "collision damage reduction control," which reduces the possibility of the vehicle colliding with an object (obstacle).

[0015] The camera device 20 includes a camera 21 and an image ECU 22. The camera 21 captures the scene in front of the vehicle HV at predetermined intervals and acquires image data. The image ECU 22 generates "camera information including the image data itself, camera target information, and lane information" based on the image data from the camera 21 and transmits it to the driver assistance ECU 10.

[0016] The driver assistance ECU 10 extracts road signs indicating speed limits (maximum speeds) from the image data acquired by the camera device 20, and recognizes (acquires) the numerical value shown on the road sign as the speed limit (maximum speed) set / applied to the lane in which the vehicle HV is currently traveling (hereinafter also referred to as "the current lane"). This recognition (acquisition) of the speed limit may also be performed by the image ECU 22.

[0017] The radar device 30 is a well-known device that obtains information about a target present in front of the host vehicle HV using radio waves in the millimeter-wave band, and includes a radar 31 and a radar ECU 32. The radar 31 transmits millimeter waves within a predetermined detection range every time a predetermined time elapses, and receives the millimeter waves reflected by the target. The radar 31 transmits information about the transmitted and received millimeter waves to the radar ECU 32. The radar ECU 32 obtains radar information based on the information from the radar 31, and transmits the radar information to the driving support ECU 10. The radar information includes the distance to the target, the azimuth of the target, the relative speed of the target, and the like.

[0018] The power train ECU 40 controls a drive device including a power source of the host vehicle HV (not shown) by driving a power train actuator 41, thereby generating a driving force.

[0019] The brake ECU 50 controls a braking device of the host vehicle HV (not shown) by driving a brake actuator 51, thereby applying a braking force to the host vehicle HV. When the brake ECU 50 receives an instruction from the driving support ECU 10, it drives the brake actuator 51 to execute an automatic brake that automatically applies a braking force to the host vehicle HV.

[0020] The steering ECU 60 controls a steering device of the host vehicle HV (not shown) by driving a steering motor 61, thereby changing the steering angle of the host vehicle HV. When the steering ECU 60 receives an instruction from the driving support ECU 10, it drives the steering motor 61 to automatically change the steering angle of the host vehicle HV (that is, to execute automatic steering).

[0021] The notification ECU (alarm ECU) 70 is connected to a display 71 disposed at a position visible from the driver's seat and an alarm sound generator 72 that generates an alarm sound (notification sound), and controls these in accordance with an instruction (instruction signal) from the driving support ECU 10. The display 71 is provided with a region 71a for displaying the restricted speed (maximum speed) and an alarm display region 71b for displaying an alarm mark for notifying that there is a risk of collision. The notification ECU 70 displays the restricted speed included in the instruction from the driving support ECU 10 in the region 71a and displays an alarm mark in the alarm display region 71b in accordance with the instruction from the driving support ECU 10.

[0022] The navigation ECU 80 is connected to a GPS receiver 81, a map database 82 storing map information, and a display touch panel 83 for displaying touch buttons, and together with these, constitutes an in-vehicle navigation system. The navigation ECU 80 acquires the current position of the host vehicle HV based on the GPS signal received by the GPS receiver 81, and based on the acquired current position of the host vehicle HV and the map information stored in the map database 82, can acquire the restricted speed set / applied to the current lane at the current time.

[0023] The communication ECU 90 performs wireless communication with devices outside the host vehicle HV (for example, roadside units and information management centers, etc.), and can acquire "various information including information about the restricted speed" from the external devices.

[0024] The driving support ECU 10 inputs the detection values (output values) of the following "sensors and switches". · An accelerator pedal operation amount sensor 91 that detects the accelerator pedal operation amount AP of the host vehicle HV. · A brake pedal operation amount sensor 92 that detects the brake pedal operation amount BP of the host vehicle HV. · A vehicle speed sensor 93 that detects the speed of the host vehicle HV (i.e., the vehicle speed).

[0025] The setting input device 94 is located in a position accessible to the driver and includes a display touch panel that shows touch-sensitive buttons. By operating the setting input device 94, the driver can change the following parameters: the collision detection time threshold TTCth, the execution start timing correction time dTTCth for collision avoidance support control, the magnitude of the speed reduction threshold VLth for control switching, and the length of the control switching period (change time threshold) Tth, etc., as described later.

[0026] (Summary of operation) The device DS acquires (recognizes) the speed limit (maximum speed) VLT of the lane in which the vehicle HV is traveling from image data. If the speed limit VLT decreases significantly, the device increases the collision judgment time threshold TTCth for initiating collision avoidance support operation (in this case, automatic braking) by the timing correction time dTTCth for the period from that point until a time equivalent to the change time threshold Tth has elapsed (correction period). In other words, during the correction period, the device DS changes the collision judgment conditions for initiating collision avoidance support operation (automatic braking) to conditions that are more likely to be met.

[0027] (Specific operation) The CPU 10a of the driver assistance ECU 10 (hereinafter simply referred to as "CPU") executes the routines shown in the flowcharts in Figures 2 to 4 and Figure 6 at predetermined time intervals (calculation cycles) dt. In the following, "step" will be denoted as "S".

[0028] <Correction of collision detection time threshold (correction of the start timing of collision avoidance support actions)> At a predetermined timing, the CPU starts processing from S200 in Figure 2 and proceeds to S210, where it determines whether a new speed limit set for the current lane has been acquired (recognized from the image) based on the image data transmitted from the camera device 20. Alternatively, the CPU may acquire the speed limit set for the current lane from the current position of the vehicle HV and map information via the navigation ECU 80.

[0029] If a new speed limit is acquired, the CPU proceeds from S210 to S220, and stores the newly acquired speed limit in S210 as the current speed limit VLTnow in RAM10c (hereinafter referred to as "RAM"). At this time, the CPU changes the speed limit displayed in area 71a of the display unit 71 to the current speed limit VLTnow.

[0030] Next, the CPU proceeds to S230 and reads the speed reduction threshold VLTth from the non-volatile memory 10d (hereinafter referred to as "non-volatile memory"). Next, the CPU proceeds to S240 and reads the reference threshold TTCthStd from the non-volatile memory.

[0031] Next, the CPU proceeds to S250, where it determines whether the speed reduction dV1, which is the difference between the previously recognized speed limit (past speed limit) VLTold and the current speed limit VLTnow, is greater than the speed reduction threshold VLTth read from non-volatile memory. In other words, in S230, the CPU determines whether the speed limit has decreased by more than the speed reduction threshold Vth.

[0032] If the speed limit reduction amount dV1 is less than or equal to the speed limit reduction amount threshold VLTth (i.e., the speed limit has not decreased significantly below the speed limit reduction amount threshold Vth), the CPU proceeds from S250 to S260 and sets the collision detection time threshold TTCth to the reference threshold TTCthStd read from non-volatile memory and stores it in RAM. Note that S260 may be omitted. The collision detection time threshold TTCth is set to the "reference threshold TTCthStd read from non-volatile memory" when the vehicle HV is started. Next, the CPU proceeds to S270 and sets the past speed limit VLTold to the current speed limit VLTnow. That is, the CPU stores the current speed limit VLTnow, which was stored in RAM in S220, as the past speed limit VLTold in RAM. After that, the CPU proceeds to S295 and terminates this routine.

[0033] In contrast, when the CPU proceeds to S250, if the speed reduction amount dV1 is greater than the speed reduction amount threshold VLTth (i.e., the speed has decreased by more than the speed reduction amount threshold VLTth), the CPU proceeds from S250 to S280. In S280, the CPU reads the timing correction time dTTCth from non-volatile memory. Next, the CPU proceeds to S290 and sets the collision detection time threshold TTCth to "the value obtained by adding the timing correction time dTTCth to the reference threshold TTCthStd" and stores it in RAM. "The value obtained by adding the timing correction time dTTCth to the reference threshold TTCthStd" is also called the corrected collision detection time threshold. After that, the CPU proceeds to S270 and then to S295.

[0034] <Completion of collision detection time threshold correction> When a predetermined timing occurs, the CPU starts processing from S300 in Figure 3 and proceeds to S310, where it determines whether the collision detection time threshold TTCth stored in RAM is equal to the corrected detection time threshold (i.e., "the value obtained by adding the timing correction time dTTCth to the reference threshold TTCthStd") (i.e., whether the collision detection time threshold TTCth is in a corrected state).

[0035] If the collision detection time threshold TTCth is equal to the corrected detection time threshold (=TTCthStd+dTTCth), the CPU proceeds from S310 to S320 and reads the change time threshold Tth from non-volatile memory.

[0036] Next, the CPU proceeds to S330, where it determines whether the duration since the collision detection time threshold TTCth was changed to the corrected detection time threshold (=TTCthStd+dTTCth) is greater than or equal to the change time threshold Tth. In other words, in S330, the CPU determines whether the change time threshold Tth has elapsed since the point in time when the speed limit decreased significantly below the speed limit reduction threshold VLTth.

[0037] If the change time threshold Tth has elapsed since the collision detection time threshold TTCth was changed to the corrected detection time threshold (=TTCthStd+dTTCth), the CPU proceeds from S330 to S340 and sets the collision detection time threshold TTCth to the reference threshold TTCthStd. In other words, the CPU returns the collision detection time threshold TTCth to the value before the change in which the timing correction time dTTCth was added (before the change). After that, the CPU proceeds to S395 and terminates this routine.

[0038] Furthermore, when the CPU proceeds to S310, if the collision detection time threshold TTCth is not equal to the corrected detection time threshold (=TTCthStd+dTTCth) (i.e., if the collision detection time threshold TTCth has not been corrected), the CPU proceeds directly from S310 to S395.

[0039] Furthermore, when the CPU proceeds to S330, if the change time threshold Tth has not elapsed since the time the collision detection time threshold TTCth was changed to the corrected detection time threshold (=TTCthStd+dTTCth), the CPU proceeds directly from S330 to S395. As a result, the collision detection time threshold TTCth is maintained at the corrected detection time threshold (=TTCthStd+dTTCth) for the period from the time the speed limit falls significantly below the speed limit reduction threshold VLTth until the change time threshold Tth has elapsed.

[0040] <Collision Avoidance Support Control> At a predetermined time, the CPU starts processing from S400 in Figure 4 and proceeds to S410, where it determines, based on camera information and radar information, whether or not there are targets (obstacles) in the area that the HV vehicle is expected to travel within a certain time. If there are no targets (obstacles) in the area that the HV vehicle is expected to travel within a certain time, the CPU proceeds directly from S410 to S495 and terminates this routine.

[0041] In contrast, if there is a target (obstacle) in the area that the vehicle HV is expected to travel within a certain time, the CPU proceeds from S410 to S420 and calculates the collision time TTC by dividing the distance between the obstacle and the vehicle HV by the relative velocity of the obstacle. That is, the CPU calculates the time required for the vehicle to collide with the obstacle as the collision time TTC. Next, the CPU proceeds to S430 and reads the collision detection time threshold TTCth from RAM.

[0042] Next, the CPU proceeds to S440 and determines whether the time to impact (TTC) is less than or equal to "the value obtained by adding the warning difference time (DTW) to the collision judgment time threshold (TTCth)". That is, in S440, the CPU determines whether the first collision judgment condition (warning condition), which is met when it is predicted that the vehicle will collide with the target, has been met. If the time to impact (TTC) is less than or equal to "the value obtained by adding the warning difference time (DTW) to the collision judgment time threshold (TTCth)", the CPU proceeds from S440 to S450 and sends an instruction signal to the notification ECU 70, causing a warning mark to be displayed in the warning display area 71b of the display unit 71 and an warning sound to be generated by the warning sound generator 72. The display of this warning mark and / or the generation of the warning sound are one of the collision avoidance support operations to avoid a collision between the vehicle and the target. After that, the CPU proceeds to S460.

[0043] On the other hand, if the collision time TTC is longer than "the collision detection time threshold TTCth plus the warning difference time DTW", the CPU proceeds directly from S440 to S460.

[0044] In S460, the CPU determines whether the time to impact (TTC) is less than or equal to the collision detection time threshold (TTCth). That is, in S460, the CPU determines whether the second collision detection condition (automatic braking execution condition), which is met when it is predicted that the vehicle will collide with the target, has been met. If the time to impact (TTC) is less than or equal to the collision detection time threshold (TTCth), the CPU proceeds from S460 to S470 and sends an instruction signal to the brake ECU 50 to execute automatic braking so that the vehicle HV stops before the obstacle (automatically applying braking force to the vehicle HV). This execution of automatic braking is one of the collision avoidance support operations to avoid a collision between the vehicle and the target. After that, the CPU proceeds to S495 and terminates this routine. On the other hand, if the time to impact (TTC) is longer than the collision detection time threshold (TTCth), the CPU proceeds directly from S460 to S495 and terminates this routine.

[0045] <ETC settings> Incidentally, the setting input device 94 is equipped with a display touch panel that shows touch-sensitive buttons, and under normal circumstances, it displays the menu screen 500 shown in Figure 5(A).

[0046] When the driver touches the display button 501 to change the "collision avoidance support timing," the setting input device 94 displays the collision avoidance support timing selection screen 510 shown in Figure 5(B). By touching one of the display buttons "early 511, normal 512, or late 513" on this selection screen 510, the driver can change the reference threshold TTCthStd for determining the collision avoidance support timing according to the routine shown in Figure 6, which will be described later. In the default state (initial state), "normal 512" is automatically selected, and the reference threshold TTCthStd is set to the standard value TStdN and stored in the non-volatile memory of the driver assistance ECU 100.

[0047] When the driver touches the display button 502 on the menu screen 500 to change the "corrected collision avoidance support timing," the setting input device 94 displays the corrected collision avoidance support timing selection screen 520 shown in Figure 5(C). By touching one of the display buttons "early 521, normal 522, or late 523" on this selection screen 520, the driver can change the timing correction time dTTCth that determines the corrected collision avoidance support timing according to the routine shown in Figure 6, which will be described later. In the default state (initial state), "normal 522" is automatically selected, and the timing correction time dTTCth is set to "2 / 3 times the maximum correctable value TS" and stored in the non-volatile memory of the driver assistance ECU 100. The maximum correctable value TS is also called the "difference value TS," and its details will be described later.

[0048] When the driver touches the display button 503 on the menu screen 500 to change the "speed limit reduction threshold," the setting input device 94 displays the speed limit reduction threshold selection screen 530 shown in Figure 5(D). The driver can change the speed limit reduction threshold VLTth by touching one of the display buttons "larger 531, normal 532, or smaller 533" on this selection screen 530, according to the routine shown in Figure 6 described later. In the default state (initial state), "normal 532" is automatically selected, and the speed limit reduction threshold Vth is set to the standard value VLTthN and stored in the non-volatile memory of the driver assistance ECU 100.

[0049] When the driver touches the display button 504 on the menu screen 500 to change the "length of the collision avoidance support timing correction period," the setting input device 94 displays the support timing correction period length selection screen 540 shown in Figure 5(E). The driver can change the change time threshold Tth by touching one of the display buttons "longer 541, normal 542, or shorter 543" on this selection screen 540, according to the routine shown in Figure 6 described later. In the default state (initial state), "normal 542" is automatically selected, and the change time threshold Tth is set to the standard value TthN and stored in the non-volatile memory of the driver assistance ECU 100.

[0050] When the predetermined timing arrives, the CPU starts processing from S600 in Figure 6 and proceeds to S605, where it determines whether the display button selected by the collision avoidance support timing selection screen 510 shown in Figure 5(B) is "early 511, normal 512, or late 513".

[0051] If "Early 511" is selected, the CPU performs the S610 process described below. If "Normal 512" is selected, the CPU performs the S615 process described below. If "Late 513" is selected, the CPU performs the S620 process described below. After performing one of these processes, the CPU proceeds to S625.

[0052] S610: The CPU sets the reference threshold TTCthStd to a value (first value) TStdL that corresponds to a relatively longer time, and stores it in the non-volatile memory of the driver assistance ECU 100. S615: The CPU sets the reference threshold TTCthStd to a standard value TStdN, which corresponds to a moderate amount of time, and stores it in the non-volatile memory of the driver assistance ECU 100. S620: The CPU sets the reference threshold TTCthStd to a value (second value) TStdS that corresponds to a relatively shorter time, and stores it in the non-volatile memory of the driver assistance ECU 100. Furthermore, the above values ​​are set such that the following inequality holds. TStdL>TStdN>TStdS

[0053] When the CPU proceeds to S625, it subtracts the reference threshold TTCthStd set in any of S610 to S620 from the value TStdL corresponding to a relatively longer time (TStdL - TTCthStd) and stores this value as a correction margin TS in the non-volatile memory of the driver assistance ECU 100. After that, the CPU proceeds to S630.

[0054] The CPU S630 determines whether the display button selected by the corrected collision avoidance support timing selection screen 520 shown in Figure 5(C) is "early 521, normal 522, or late 523".

[0055] If "Early 521" is selected, the CPU performs the S635 process described below. If "Normal 522" is selected, the CPU performs the S640 process described below. If "Late 523" is selected, the CPU performs the S645 process described below. After performing one of these processes, the CPU proceeds to S650.

[0056] S635: The CPU sets the timing correction time dTTCth to the maximum correctable value TS, which corresponds to a relatively longer time, and stores it in the non-volatile memory of the driver assistance ECU 100. S640: The CPU sets the timing correction time dTTCth to a value equivalent to a moderate time, which is "2 / 3 times the maximum correctable value TS," and stores it in the non-volatile memory of the driver assistance ECU 100. S645: The CPU sets the timing correction time dTTCth to a value equivalent to a relatively short time, which is "1 / 3 the maximum correctable value TS", and stores it in the non-volatile memory of the driver assistance ECU 100. Since the maximum correctable value TS is a positive value, the inequality "TS > (2 / 3)·TS > (1 / 3)·TS" naturally holds for each of the above values.

[0057] As the timing correction time dTTCth is set in this way, the post-correction judgment time threshold (=TTCthStd+dTTCth) changes between "TStdL, a value corresponding to a relatively longer time" and "the reference threshold TTCthStd set in any of S610 to S620 (more precisely, TTCthStd+(1 / 3)·TS)". Therefore, during the period from when the speed limit falls significantly below the speed limit reduction threshold VLTth until the change time threshold Tth has elapsed (correction period), the start timing of the collision avoidance support operation is set between the start timing of the collision avoidance support operation desired by the driver during normal driving and the earliest start timing of the collision avoidance support operation that the system allows. For this reason, during the correction period, the collision avoidance support operation starts earlier than the start timing of the collision avoidance support operation desired by the driver during normal driving, but the situation where the collision avoidance support operation starts earlier than necessary is avoided.

[0058] The CPU, S650, determines whether the display button selected by the speed reduction threshold selection screen 530 shown in Figure 5(D) is "larger 531, normal 532, or smaller 533".

[0059] If "Larger 531" is selected, the CPU performs the S655 process described below. If "Normal 532" is selected, the CPU performs the S660 process described below. If "Smaller 533" is selected, the CPU performs the S665 process described below. After performing one of these processes, the CPU proceeds to S670.

[0060] S655: The CPU sets the speed reduction threshold VLTth to a relatively large value VLTthL and stores it in the non-volatile memory of the driver assistance ECU 100. S660: The CPU sets the speed reduction threshold VLTth to a moderate value VLTthN and stores it in the non-volatile memory of the driver assistance ECU 100. S665: The CPU sets the speed reduction threshold VLTth to a relatively small value VLTthS and stores it in the non-volatile memory of the driver assistance ECU 100. Furthermore, the above values ​​are set such that the following inequality holds. VLTthL>VLTthN>VLTthS

[0061] The CPU S670 determines whether the display button selected by the support timing correction period length selection screen 540 shown in Figure 5(E) is "longer 541, normal 542, or shorter 543".

[0062] If "Longer 541" is selected, the CPU performs the process in S675 described below. If "Normal 542" is selected, the CPU performs the process in S680 described below. If "Shorter 543" is selected, the CPU performs the process in S685 described below. After performing one of these processes, the CPU proceeds to S695 and terminates this routine.

[0063] S675: The CPU sets the change time threshold Tth to a value TthL that corresponds to a relatively longer time, and stores it in the non-volatile memory of the driver assistance ECU 100. S680: The CPU sets the change time threshold Tth to a value TthN that corresponds to a moderate length of time and stores it in the non-volatile memory of the driver assistance ECU 100. S685: The CPU sets the change time threshold Tth to a value TthS that corresponds to a relatively short time, and stores it in the non-volatile memory of the driver assistance ECU 100. Furthermore, the above values ​​are set such that the following inequality holds. TthL > TthN > TthS

[0064] As explained above, when the current speed limit falls significantly below the speed limit reduction threshold VLTth from the past speed limit, the device DS changes the collision judgment time threshold TTCth to the corrected judgment time threshold (=TTCthStd+dTTCth), thereby changing the collision judgment conditions for the collision avoidance support operation to conditions that are more likely to be met. Therefore, even if the driver of the vehicle overlooks the reduction in the speed limit and is slow to react to the sudden deceleration of the preceding vehicle, the collision judgment conditions will be met earlier and the collision avoidance support operation will be executed earlier, thus preventing the vehicle from getting too close to the preceding vehicle.

[0065] It should be noted that the present invention is not limited to the above embodiments and modifications, and various modifications can be adopted within the scope of the present invention. For example, in S210, the CPU may recognize the current speed limit by receiving the speed limit from the roadside unit via the communication ECU 90. Furthermore, the present invention is applicable to the vehicle in an autonomous driving vehicle that has transitioned from autonomous driving to driver-operated driving mode. There were three types of values ​​that can be changed by operating the setting input device 94, but there may be N types (where N is an integer of 2 or more). Furthermore, when the CPU determines "No" in S330, it may determine whether the current speed limit is greater than the past speed limit, and if the current speed limit is greater than the past speed limit, it may proceed to S340, and if it is not greater, it may proceed to S395. [Explanation of symbols]

[0066] 10... Driver assistance ECU, 20... Camera system, 30... Radar system, 50... Brake ECU.

Claims

1. The system includes a controller configured to perform collision avoidance support actions to avoid a collision between the vehicle and a target when a collision determination condition is met, which is met when it is predicted that the vehicle will collide with the target. The aforementioned controller, The vehicle recognizes the speed limit applicable to the lane in which it is traveling, When the current speed limit, which is the newly recognized speed limit at the present moment, is lower than the past speed limit, which was recognized immediately before the present moment, the collision detection conditions are changed to conditions that make it easier for the collision avoidance support operation to be executed at an earlier timing compared to when the current speed limit has not decreased from the past speed limit. It is configured in such a way. A vehicle driving assistance system, The vehicle is equipped with a setting input device operated by the occupants of the vehicle, The aforementioned controller, The system is configured to change the collision determination condition to a condition that is more likely to be met when the current speed limit has decreased by more than a threshold amount from the past speed limit. The controller further, The setting input device is configured to allow the threshold value of the speed reduction to be changed based on the input to the setting input device. A vehicle driver assistance system.

2. A controller configured to perform collision avoidance support operations to avoid a collision between the vehicle and a target when a collision determination condition is met, which is met when it is predicted that the vehicle will collide with a target, The aforementioned controller, The vehicle recognizes the speed limit applicable to the lane in which it is traveling, When the current speed limit, which is the newly recognized speed limit at the present moment, is lower than the past speed limit, which was recognized immediately before the present moment, the collision detection conditions are changed to conditions that make it easier for the collision avoidance support operation to be executed at an earlier timing compared to when the current speed limit has not decreased from the past speed limit. It is configured in such a way. A vehicle driving assistance system, The vehicle is equipped with a setting input device operated by the occupants of the vehicle, The aforementioned controller, The system is configured to revert the collision determination condition to its original state when the elapsed time since the collision determination condition was changed to the condition that is more likely to be met reaches the change time threshold. The controller further, The change time threshold is configured to be changeable based on the input to the setting input device. A vehicle driver assistance system.

3. A controller configured to perform collision avoidance support operations to avoid a collision between the vehicle and a target when a collision determination condition is met, which is met when it is predicted that the vehicle will collide with a target, The aforementioned controller, The vehicle recognizes the speed limit applicable to the lane in which it is traveling, When the current speed limit, which is the newly recognized speed limit at the present moment, is lower than the past speed limit, which was recognized immediately before the present moment, the collision detection conditions are changed to conditions that make it easier for the collision avoidance support operation to be executed at an earlier timing compared to when the current speed limit has not decreased from the past speed limit. It is configured in such a way. A vehicle driving assistance system, The vehicle is equipped with a setting input device operated by the occupants of the vehicle, The controller further, The system is configured to allow the degree to which the conditions that are likely to be met can be changed based on the input to the setting input device. A vehicle driver assistance system.

4. A controller configured to perform collision avoidance support operations to avoid a collision between the vehicle and a target when a collision determination condition is met, which is met when it is predicted that the vehicle will collide with a target, The aforementioned controller, The vehicle recognizes the speed limit applicable to the lane in which it is traveling, When the current speed limit, which is the newly recognized speed limit at the present moment, is lower than the past speed limit, which was recognized immediately before the present moment, the collision detection conditions are changed to conditions that make it easier for the collision avoidance support operation to be executed at an earlier timing compared to when the current speed limit has not decreased from the past speed limit. It is configured in such a way. A vehicle driving assistance system, The vehicle is equipped with a setting input device operated by the occupants of the vehicle, The aforementioned controller, The time required for the vehicle to collide with the target is calculated. The system is configured to determine that the collision determination condition has been met when the collision time falls below the collision determination time threshold. The controller further, Based on the input to the setting input device, the collision determination time threshold used to determine whether the collision determination condition has been met when the collision determination condition has not been changed is configured to be changeable as a reference threshold between a first value and a second value smaller than the first value. The collision determination time threshold is changed to a value obtained by adding a timing correction time to the reference threshold, thereby changing the collision determination condition to the easily changeable condition. The timing correction time is configured to be changeable based on the input to the setting input device. The timing correction time is set to be less than or equal to the difference obtained by subtracting the reference threshold from the first value. A vehicle driver assistance system.

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