Attention attracting device and attention attracting method for vehicle

Abstract

To perform an attention attracting operation for attracting attention of a driver to a preceding vehicle at a more appropriate timing for individual drivers.SOLUTION: When determining that a sudden approach condition established when a preceding vehicle suddenly approaches a user's vehicle is established in a preceding vehicle following up state in which the user's vehicle is following up the preceding vehicle by the driver of the user's vehicle, a driving support ECU 10 of an attention attracting device for a vehicle acquires operation characteristic values indicating characteristics of a deceleration operation performed by the driver (a response time before the driver starts to tread a brake pedal, a maximum deceleration, and a deceleration change rate), and stores an operation characteristic learning value that changes according to the operation characteristic values in a storage device. When determining that a preceding vehicle following-up state occurs anew, the driving support ECU calculates "a required vehicular gap to be maintained" by using the operation characteristic learning value. When determining that an attention attracting condition including a condition that an actual vehicular gap is the required vehicular gap or less is established, the driving support ECU performs an attention attracting operation for attracting attention of the driver.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an attention calling device for a vehicle that performs an attention calling operation to call the attention of a driver of the vehicle when the distance between the vehicle and a preceding vehicle is short. [Background technology]

[0002] The conventional device estimates the maximum reduction in the inter-vehicle distance between the subject vehicle and the preceding vehicle (maximum approach distance) after the preceding vehicle starts to decelerate based on the preceding vehicle speed, the deceleration of the preceding vehicle, the subject vehicle speed, the expected deceleration of the subject vehicle, and the free running time until the subject vehicle starts to brake. The conventional device issues an alarm when the current inter-vehicle distance between the subject vehicle and the preceding vehicle is equal to or less than the "appropriate inter-vehicle distance based on the maximum approach distance" (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-231400 Summary of the Invention

[0004] The time from when a driver releases the accelerator pedal to when he or she starts to press the brake pedal (pedal change time equivalent to the free-running time), and the deceleration of the vehicle caused by depressing the brake pedal, differ from driver to driver. Therefore, the maximum approach distance and appropriate inter-vehicle distance differ from driver to driver. Therefore, the above-mentioned conventional device measures the actual pedal change time, and uses a value based on the measured time as the "free-running time used when calculating the appropriate inter-vehicle distance." Furthermore, the above-mentioned conventional device measures the deceleration of the vehicle caused by depressing the brake pedal, and uses a value based on that deceleration as the "assumed deceleration of the vehicle used when calculating the maximum approach distance."

[0005] However, the "pedal change time and deceleration" measured by the above-mentioned conventional device are measured not only in an imminent situation where the vehicle approaches the preceding vehicle quickly, but also during normal driving. Therefore, the free running time and estimated deceleration are not appropriate values ​​for an imminent situation (a situation where the maximum approach distance is calculated), and as a result, the maximum approach distance and the appropriate inter-vehicle distance deviate from the appropriate values, so there is a risk that the warning cannot be issued at the appropriate time.

[0006] The present invention has been made to solve such problems. That is, one of the objects of the present invention is to provide a vehicle attention calling device and an attention calling method that can perform an attention calling operation (e.g., a warning display and / or an alarm sound) to call the driver's attention to a preceding vehicle at a timing more appropriate for each driver.

[0007] One aspect of the vehicle attention calling device of the present invention (hereinafter also referred to as the "present invention device") is as follows: A first acquisition device (71-76) that acquires host vehicle information including information on a host vehicle speed, which is a speed of the host vehicle, and information on an operation state of a brake pedal of the host vehicle; a second acquisition device (20, 30) that acquires preceding vehicle information including information on a vehicle-to-vehicle distance between the preceding vehicle and the host vehicle and information on a relative speed of the preceding vehicle; an alarm device (40-42) that executes at least one of displaying a warning and emitting an alarm sound as an attention-attracting operation for attracting the attention of a driver of the vehicle; A controller (10) for controlling the alarm device; Equipped with. Further, the controller When the host vehicle is in a preceding vehicle following state in which the host vehicle is following the preceding vehicle due to a driving operation of the driver (S220: Yes) and it is determined based on the host vehicle information and the preceding vehicle information that a predetermined sudden approach condition that is established when the host vehicle and the preceding vehicle begin to approach each other suddenly is established (S230: Yes), an operation characteristic value that represents a characteristic of a deceleration operation for decelerating the host vehicle executed by the driver after the point in time when the sudden approach condition is established is obtained based on the host vehicle information (S340, S450, S455), and an operation characteristic learning value that changes depending on the operation characteristic value is stored in a storage device (S350, S450, S455); If it is determined that the preceding vehicle following state has newly occurred, the required inter-vehicle distance that the host vehicle must maintain between itself and the preceding vehicle is calculated using the operating characteristic learning value (S505-S592), and if it is determined that a warning condition is satisfied, including a condition that is satisfied when the inter-vehicle distance is equal to or less than the required inter-vehicle distance, the warning device is caused to execute the warning activation action (S594).

[0008] According to the present invention, an operation characteristic value that represents the characteristics of the driver's deceleration operation after the point when the vehicle and the preceding vehicle actually start to approach each other rapidly (i.e., the point when the rapid approach condition is established) is acquired, and an operation characteristic learning value is stored according to the operation characteristic value. Furthermore, the operation characteristic learning value is used to calculate the required inter-vehicle distance. Therefore, since the required inter-vehicle distance is a value that corresponds to the deceleration operation characteristics of each individual driver in an urgent situation, the attention alert operation can be performed at an appropriate timing.

[0009] In the above description, in order to facilitate understanding of the present invention, the names and / or symbols used in the embodiments described below are enclosed in parentheses with respect to the configuration of the invention corresponding to the embodiments. However, each component of the present invention is not limited to the embodiments defined by the names and / or symbols. The present invention also covers a vehicle attention-attracting method and a program thereof. [Brief description of the drawings]

[0010] [Figure 1]1 is a schematic configuration diagram of a vehicle attention calling device according to an embodiment of the present invention; [Diagram 2] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Diagram 3] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 4] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Diagram 5] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 6] Graphs (A), (B) and (C) are graphs for explaining the maximum approach distance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The vehicle attention warning device DS (hereinafter referred to as "device DS") according to an embodiment of the present invention has the components shown in FIG. 1 and is applied to (mounted on) the host vehicle. The host vehicle may be any vehicle powered by an internal combustion engine, an electric vehicle, a hybrid vehicle, or the like. In other words, the host vehicle may have any power source. The host vehicle may also be simply referred to as "host vehicle".

[0012] In this specification, an "ECU" is an electronic control unit having a microcomputer including a CPU (processor), ROM, RAM, and a writable non-volatile memory as a main device. The ECU is also called a controller or a computer. The multiple ECUs shown in FIG. 1 are connected to each other via a CAN (Controller Area Network) so that they can exchange information with each other.

[0013] The driving assistance ECU 10 executes "vehicle distance warning control" which will be described in detail later.

[0014] The front camera device 20 includes a front camera 21 and an image ECU 22. The front camera 21 captures an image of a scene in front of the vehicle at predetermined time intervals to obtain image data. The image ECU 22 generates camera information by analyzing the image data from the front camera 21, and transmits the camera information to the driving assistance ECU 10. The camera information includes lane marking information such as the position and type of lane markings on the lane in which the vehicle is traveling, and camera target information such as the "position, relative longitudinal speed, relative lateral speed, and type relative to the vehicle" of the captured target.

[0015] The radar device 30 is a well-known device that acquires information about a target present in front of the vehicle using millimeter wave band radio waves, and includes a radar 31 and a radar ECU 32. The radar 31 transmits information about the transmitted and received millimeter waves to the radar ECU 32. The radar ECU 32 acquires radar information based on the information from the radar 31 and transmits it to the driving assistance ECU 10. The radar information includes the distance to the target, the direction of the target, and the relative speed of the target. Note that the relative speed of the target is defined to be a positive value when the target is approaching the vehicle.

[0016] The driving assistance ECU 10 identifies a preceding vehicle based on camera information and radar information, and acquires the distance between the host vehicle and the preceding vehicle and the relative speed of the preceding vehicle. The preceding vehicle is another vehicle traveling in the lane in which the host vehicle is traveling (host lane), and traveling immediately before the host vehicle in the same direction as the host vehicle. The preceding vehicle is also simply called a "preceding vehicle."

[0017] The brake ECU 40 controls the braking device by driving the brake actuator 41 based on the brake pedal operation amount BP detected by a brake pedal operation amount sensor 73 described later. That is, the brake ECU 40 adjusts the braking force applied to the host vehicle so that the deceleration (magnitude of negative acceleration) of the host vehicle increases as the brake pedal operation amount BP increases.

[0018] The warning ECU 50 displays a warning on the warning display device 51 and generates a warning sound from the warning sound generating device 52 in response to an instruction from the driving assistance ECU 10 .

[0019] The driving assistance ECU 10 receives detection values ​​(output values) of the following "sensors and switches." An accelerator pedal operation amount sensor 71 that detects the amount of operation AP of the accelerator pedal of the host vehicle. An accelerator switch 72 that outputs an ON signal when the accelerator pedal of the host vehicle is depressed and outputs an OFF signal when the accelerator pedal is released. A brake pedal operation amount sensor 73 detects an operation amount BP of the brake pedal of the host vehicle. A brake switch 74 that outputs an ON signal when the brake pedal of the host vehicle is depressed and outputs an OFF signal when the brake pedal is released. A vehicle speed sensor 75 detects the speed of the host vehicle (i.e., host vehicle speed Vh). An acceleration sensor 76 that detects the acceleration G in the longitudinal direction of the host vehicle. In this specification, the deceleration (negative acceleration G) in the longitudinal direction of the host vehicle is represented as a positive value Gh (=-G>0).

[0020] (Overview of operation) When the driver of the vehicle is driving the vehicle so as to follow the preceding vehicle at approximately the same speed as the preceding vehicle (i.e., when a preceding vehicle following state is occurring), and the preceding vehicle decelerates and begins to rapidly approach the vehicle, the device DS acquires the value described below as "a value representing the characteristics of the deceleration operation performed by the driver to decelerate the vehicle (i.e., an operation characteristic value)".

[0021] The time from when the sudden approach of the preceding vehicle is detected (the sudden approach detection time when the sudden approach condition is established) to when the driver starts decelerating. This time is also called the "reaction time" or "free running time." The time when the deceleration operation starts is the time when the signal of the brake switch 74 changes from an OFF signal to an ON signal, but it may also be the time when the signal of the accelerator switch 72 changes from an ON signal to an OFF signal. -The maximum deceleration (maximum deceleration) caused by the braking operation (depression of the brake pedal) after the sudden approach of a leading vehicle is detected. The rate of change in deceleration (the amount of increase in deceleration per unit time) caused by braking after the sudden approach of a leading vehicle is detected until the deceleration of the vehicle reaches maximum deceleration.

[0022] Based on the measured operating characteristic values ​​(reaction time, maximum deceleration, deceleration change rate), device DS calculates operating characteristic learning values ​​(reaction time learned value, maximum deceleration learned value and deceleration change rate learned value) for each inter-vehicle time zone (time range) corresponding to the inter-vehicle time (= inter-vehicle distance / host vehicle speed) at the time when the sudden approach of the preceding vehicle was detected, and stores them in non-volatile memory as the operating characteristic learning values ​​for the corresponding inter-vehicle time zone.

[0023] When the vehicle is driven by the driver of the vehicle so as to follow the preceding vehicle, the device DS reads out the above-mentioned operation characteristic learning value corresponding to the vehicle-to-vehicle time at that time from the non-volatile memory, calculates the maximum approach distance using the operation characteristic learning value, and calculates the distance based on the maximum approach distance as the required vehicle-to-vehicle distance. The maximum approach distance is the maximum amount of change (reduced distance) in the vehicle-to-vehicle distance from the time (current time) when it is assumed that the preceding vehicle starts to approach the vehicle to the time when the vehicle approaches the preceding vehicle closest to the preceding vehicle. When the actual vehicle-to-vehicle distance remains below the required vehicle-to-vehicle distance for a certain period of time or more, the device DS displays a warning (a display to call attention) and / or generates an alarm (a sound to call attention).

[0024] (Specific operation) <Learned value acquisition> The CPU of the driving assistance ECU 10 (hereinafter simply referred to as "CPU") executes the routines shown in the flowcharts of FIGS. 2 to 4 every time a predetermined time (calculation period) dt elapses.

[0025] When an appropriate time arrives, the CPU starts the process from step 200 (hereinafter, "step" will be abbreviated as "S") in Fig. 2 and proceeds to S210 to determine whether the value of a data acquisition flag XD is "0." The value of the flag XD is set to "1" when data for calculating a learning value is being acquired (see S250 described later).

[0026] If the value of flag XD is "0", the CPU proceeds from S210 to S220 to determine whether or not the host vehicle is currently traveling so as to follow a preceding vehicle (i.e., whether or not a preceding vehicle following state has occurred). More specifically, the CPU determines that a preceding vehicle following state has occurred when it is determined based on the camera information and radar information that a preceding vehicle exists and the inter-vehicle distance Dint to the preceding vehicle is equal to or less than the threshold distance Dth, and the signal (brake signal) of the brake switch 74 is an off signal.

[0027] If the vehicle is currently following the preceding vehicle, the CPU proceeds from S220 to S230 to determine whether the inter-vehicle distance between the vehicle and the preceding vehicle is decreasing rapidly (whether the vehicle is rapidly approaching the preceding vehicle). More specifically, the CPU determines whether a rapid approach condition is established, that is, a relative speed increase amount dVr, which is a value obtained by subtracting the relative speed Vrold from a predetermined time ago, is equal to or greater than a threshold relative speed dVrth.

[0028] If the relative speed increase amount dVr is greater than or equal to the threshold relative speed dVrth (if the rapid approach condition is met), the CPU judges "Yes" in S230 and executes the "processing of S240 to S260" described below, and then proceeds to S295 and temporarily ends this routine.

[0029] S240: The CPU stores the current inter-vehicle time Tint (=the current inter-vehicle distance Dint divided by the current vehicle speed Vh) as a value indicating the current situation.

[0030] S250: The CPU sets the value of the data acquisition flag XD to "1." S260: The CPU sets the value of a timer Timer to "0" in order to start measuring the elapsed time from the point in time when the relative speed Vr begins to increase rapidly (the point in time when the rapid approach condition is established).

[0031] If the value of flag XD is not "0" when the CPU proceeds to S210, the CPU proceeds from S210 to S270 to determine whether or not a preceding vehicle still exists. If a preceding vehicle still exists, the CPU proceeds directly to S295. If a preceding vehicle does not exist, the CPU proceeds from S270 to S280 to set the value of flag XD to "0" and proceeds to S295.

[0032] If the preceding vehicle following state is not occurring when the CPU proceeds to S220, the CPU proceeds from S220 to S280. In addition, if the relative speed Vr has not increased sharply when the CPU proceeds to S230, the CPU proceeds from S230 to S280.

[0033] 3, the CPU starts the process from S300 and proceeds to S310 to determine whether the value of the data acquisition flag XD is 1. If the value of the flag XD is not 1, the CPU proceeds directly from S310 to S395 and ends this routine.

[0034] On the other hand, when the value of flag XD is "1", the CPU proceeds from S310 to S320, and determines whether a deceleration operation has been performed by determining whether the signal of brake switch 74 has changed from an off signal to an on signal. Note that the CPU may determine that a deceleration operation has been performed when the signal of accelerator switch 72 has changed from an on signal to an off signal.

[0035] If it is determined that no deceleration operation has been performed, the CPU proceeds from S320 to S330, where it increments the value of the timer Timer by a predetermined fixed time (calculation period) dt, and then proceeds to S395.

[0036] On the other hand, if it is determined in S320 that a deceleration operation has been performed, the CPU proceeds from S320 to S340, where it obtains the value of the timer Timer as the reaction time for the inter-vehicle time period (time range) to which the inter-vehicle time Tint stored in S240 of Fig. 2 belongs. Furthermore, in S350, the CPU calculates a reaction time learned value Tr for the inter-vehicle time period based on the reaction time, and then proceeds to S395. The driving assistance ECU 10 stores the lookup table shown in block B1 of Fig. 3 in a non-volatile memory. For example, when the inter-vehicle time Tint stored in S240 of Fig. 2 is between time T2 and time T3, the CPU reads out the reaction time learned value Tr2 of the inter-vehicle time zone to which the inter-vehicle time Tint belongs from the lookup table, updates the reaction time learned value Tr2 by substituting the "read out reaction time learned value Tr2" and the "value of the timer Timer at that time (i.e., the acquired reaction time)" into the right-hand side of the following equation, and stores the updated reaction time learned value Tr2 in the corresponding area of ​​the lookup table. α is a predetermined value between "0" and "1", and the left-hand side of the following equation is the updated reaction time learned value. Tr2 = α · Timer + (1-α) · Tr2

[0037] 4, the CPU starts the process at S400 and proceeds to S405 to determine whether the value of the data acquisition flag XD is 1. If the value of the flag XD is not 1, the CPU proceeds directly to S495 and ends this routine.

[0038] On the other hand, if the value of the flag XD is "1", the CPU proceeds from S405 to S410 and determines whether the value of the braking in progress flag XB is "0". The flag XB is set to "1" when a braking operation as a deceleration operation is started when the value of the flag XD is "1" (see S420). If a braking operation has not been performed since the value of the flag XD was set to "1", the value of the flag XB is "0", so the CPU proceeds from S410 to S415 and determines whether a braking operation has been started. That is, the CPU determines whether the signal of the brake switch 74 has changed from an off signal to an on signal. If a braking operation has not been started, the CPU proceeds directly from S415 to S435. If a braking operation is started, the CPU proceeds from S415 to S420, sets the value of the flag XB to "1", and proceeds to S435.

[0039] On the other hand, if the value of flag XB is "1" when the CPU proceeds to S410, the CPU proceeds from S410 to S425 to determine whether the braking operation has ended (whether the signal of the brake switch 74 has changed from an on signal to an off signal) and whether the vehicle speed Vh has become "0" or less (whether the vehicle has stopped). If the braking operation has not ended and the vehicle has not stopped, the CPU proceeds directly from S425 to S435. In contrast, if the braking operation has ended or the vehicle has stopped, the CPU proceeds from S425 to S430 to set the value of flag XB to "0", and then proceeds to S435.

[0040] In S435, the CPU determines whether the value of the braking in progress flag XB is "1". If the value of the braking in progress flag XB is "1", the CPU proceeds from S435 to S440, where it stores the deceleration Gh and the deceleration change rate (amount of change in deceleration per unit time) Jh at that point in time in the RAM in association with the time at that point in time. Thereafter, the CPU proceeds to S495, where it temporarily ends this routine. Note that the deceleration change rate is a value obtained by inverting the sign of the jerk (acceleration change rate).

[0041] On the other hand, if the value of the braking in progress flag XB is "0" when the CPU proceeds to S435, the CPU proceeds from S435 to S445 to determine whether the current time is immediately after the "point in time when the value of the braking in progress flag XB changed from "1" to "0" (the point in time of change)." If the current time is not immediately after the point in time of change, the CPU proceeds directly from S445 to S495.

[0042] When the CPU proceeds to S445, if that point in time is immediately after the point in time of change, the CPU executes "the processing of S450 and S455" described below, and then proceeds to S495.

[0043] S450: The CPU selects (acquires) the maximum deceleration Gmx from among the decelerations Gh stored in S440. The CPU then updates (learns) "the maximum deceleration learned value Gm of the inter-vehicle time zone (time range) to which the inter-vehicle time Tint stored in S240 of FIG. 2 belongs" based on the maximum deceleration Gmx. For example, when the inter-vehicle time Tint stored in S240 of FIG. 2 is between time T2 and time T3, the CPU reads out the maximum deceleration learned value Gm2 of the inter-vehicle time zone to which the inter-vehicle time Tint belongs from the lookup table shown in block B1 of FIG. 3, and updates the maximum deceleration learned value Gm2 by substituting the acquired maximum deceleration Gmx and the read maximum deceleration learned value Gm2 into the right side of the equation "Gm2=α·Gmx+(1-α)·Gm2", and stores the updated maximum deceleration learned value Gm2 in the corresponding area of ​​the lookup table.

[0044] S455: The CPU selects "the deceleration change rate during the period until the deceleration Gh reaches the maximum deceleration Gmx" from the deceleration change rates Jh stored in S440, and obtains the average value of the deceleration change rates as the deceleration change rate Ja. Then, the CPU updates (learns) "the deceleration change rate learning value Jm for the inter-vehicle time zone (time range) to which the inter-vehicle time Tint stored in S240 of FIG. 2 belongs" based on the deceleration change rate Ja. For example, when the time headway Tint stored in S240 of FIG. 2 is between time T2 and time T3, the CPU reads out the deceleration change rate learned value Jm2 for the time period to which the time headway Tint belongs from the lookup table shown in block B1 of FIG. 3, updates the deceleration change rate learned value Jm2 by substituting the acquired deceleration change rate Ja and the read deceleration change rate learned value Jm2 into the right side of the equation "Jm2=α·Ja+(1-α)·Jm2," and stores the updated deceleration change rate learned value Jm2 in the corresponding area of ​​the lookup table.

[0045] <Calculation of required vehicle distance and warning control> When the same condition as that described in S220 is met, the CPU determines that a new state of following the preceding vehicle has occurred, and executes the routine shown in the flowchart of Figure 5 every time a predetermined time dt has elapsed as long as the preceding vehicle following state continues.

[0046] Therefore, if a preceding vehicle following state occurs, the CPU starts the process from S500 in FIG. 5 and proceeds to S505, where it reads out the learned values ​​(reaction time learned value Tr, maximum deceleration learned value Gm, deceleration change rate learned value Jm) corresponding to the current inter-vehicle time Tint from the look-up table (see block B1 in FIG. 3). Furthermore, the CPU sets the expected preceding vehicle deceleration Gp to a predetermined value, acquires the current host vehicle speed Vh, and calculates the current preceding vehicle speed Vp from the host vehicle speed Vh and the relative speed Vr. Note that the expected preceding vehicle deceleration Gp is ​​set to a value equivalent to 2σ or σ on the larger side of the deceleration distribution based on big data on the deceleration of many vehicles so that the attention alert operation is executed at a safer time.

[0047] In S510, the CPU resets the calculation variables (the elapsed time Ti from the current time, the host vehicle deceleration Gh, the host vehicle's travel distance Dh which is the distance the host vehicle has traveled from the current time, the preceding vehicle's travel distance Dp which is the distance the preceding vehicle has traveled from the current time, and the maximum approach distance Dmax).

[0048] Next, if the calculated preceding vehicle speed Vp is equal to or less than "0" through the processing of S515 and S520 (i.e., if the preceding vehicle is stopped, S515: No), the CPU sets the assumed preceding vehicle deceleration Gp and preceding vehicle speed Vp to "0" (S520). If the preceding vehicle speed Vp is greater than "0", the assumed preceding vehicle deceleration Gp and preceding vehicle speed Vp are maintained at their current values. Thereafter, the CPU performs the processing of "S525 and S530" described below.

[0049] S525: The CPU updates the preceding vehicle speed Vp at that time by adding the "product (-Gp·dt) of the preceding vehicle acceleration (-Gp) and the calculation period dt" to the preceding vehicle speed Vp. S530: The CPU updates the preceding vehicle travel distance Dp by adding the "product (Vp·dt) of the preceding vehicle speed Vp and the calculation period dt" to the preceding vehicle travel distance Dp at that time.

[0050] Next, the CPU updates the host vehicle deceleration Gh by performing the processing of an appropriate step among S535 to S555. That is, the CPU sets the host vehicle deceleration Gh to "0" (S540) until the elapsed time Ti reaches the reaction time learning value Tr (S535: No). On the other hand, if the elapsed time Ti is longer than the reaction time learning value Tr (S535: Yes) and the absolute value of the host vehicle deceleration Gh is equal to or less than the absolute value of the maximum deceleration learning value Gm (S545: No), the CPU updates the host vehicle deceleration Gh by adding the "product (Jm·dt) of the deceleration change rate learning value Jm and the calculation period dt" to the host vehicle deceleration Gh at that time (S550). If the absolute value of the host vehicle deceleration Gh is greater than the absolute value of the maximum deceleration learning value Gm (S545: Yes), the CPU sets the host vehicle deceleration Gh to the maximum deceleration learning value Gm (S555).

[0051] Next, the CPU performs the processes of "S560 to S570" described below. S560: The CPU updates the host vehicle speed Vh by adding the "product (-Gh·dt) of the host vehicle acceleration (-vehicle deceleration Gh) and the calculation period dt" to the host vehicle speed Vh at that time. S565: The CPU updates the host vehicle travel distance Dh by adding the "product (Vh·dt) of the host vehicle speed Vh and the calculation period dt" to the host vehicle travel distance Dh at that time. S570: The CPU calculates the approach distance Da by subtracting the preceding vehicle travel distance Dp from the host vehicle travel distance Dh.

[0052] Next, the CPU performs the processes of S575 and S580, and if the approach distance Da calculated in S570 is greater than the "maximum approach distance Dmax held at that time" (S575: Yes), it sets the maximum approach distance Dmax to the approach distance Da calculated in S570. If the approach distance Da calculated in S570 is less than or equal to the "maximum approach distance Dmax held at that time" (S575: No), the CPU holds the maximum approach distance Dmax at that time.

[0053] Next, the CPU proceeds to S585 to determine whether the vehicle speed Vh is equal to or less than "0" (i.e., whether the vehicle has been mathematically stopped), and if the vehicle speed Vh is greater than "0", the CPU proceeds to S590 to increase the elapsed time Ti by the calculation period dt, and returns to S515.

[0054] On the other hand, if the host vehicle speed Vh is equal to or less than "0", the CPU proceeds from S585 to S592 and sets the required inter-vehicle distance Dreq to the maximum approach distance Dmax. In other words, the required inter-vehicle distance Dreq is the maximum approach distance Dmax during the period until the host vehicle stops. The CPU may set the required inter-vehicle distance Dreq to "a value obtained by adding a predetermined positive value Ds to the maximum approach distance Dmax".

[0055] Next, the CPU proceeds to S594 and determines whether the condition that is satisfied when the actual following distance Dint is equal to or less than the required following distance Dreq continues for a certain period of time or more. The state in which the actual following distance Dint is equal to or less than the required following distance Dreq is called a short following distance state. If the short following distance state continues for a certain period of time or more, the CPU performs an attention-calling operation. That is, the CPU displays a warning on the warning display device 51 ("a pattern and / or text for attention" that notifies the driver that the following distance is too short) and causes the warning sound generating device 52 to generate an alarm ("an alarm sound and / or a voice message for attention" that notifies the driver that the following distance is too short). In addition, the CPU may calculate the required inter-vehicle time, which is the required inter-vehicle distance Dreq divided by the current actual vehicle speed Vh, and determine that a short inter-vehicle distance state is occurring when the "actual inter-vehicle time" calculated by dividing the actual inter-vehicle distance Dint by the current actual vehicle speed Vh is less than or equal to the "required inter-vehicle time."

[0056] Fig. 6 is a graph showing "own vehicle speed, preceding vehicle speed, approach distance, and maximum approach distance" calculated by the above-mentioned method. Fig. 6(A) shows each value when the maximum deceleration learning value Gm is smaller than the assumed preceding vehicle deceleration Gp (i.e., when the own vehicle deceleration is weaker than the preceding vehicle deceleration). Fig. 6(B) shows each value when the maximum deceleration learning value Gm is larger than the assumed preceding vehicle deceleration Gp (i.e., when the own vehicle deceleration is stronger than the preceding vehicle deceleration). Fig. 6(C) shows each value when the driver's response is slow (reaction time learning value Tr is relatively long) but the maximum deceleration learning value Gm is larger than the assumed preceding vehicle deceleration Gp.

[0057] As described above, according to the embodiment of the present invention, the operation characteristic learning value is updated based on the "operation characteristic value representing the characteristics of the deceleration operation for decelerating the vehicle performed by the driver" measured in the tense state where the sudden approach condition is satisfied, so that the operation characteristic learning value becomes a value that appropriately represents the operation characteristic of the driver in the "tense state when the preceding vehicle suddenly starts to decelerate suddenly". Therefore, the required inter-vehicle distance calculated based on the operation characteristic learning value becomes an appropriate value for the driver. Furthermore, since the operation characteristic learning value is set for each inter-vehicle time zone, the operation characteristic learning value for the state that is closer to the actual state when the preceding vehicle approaches the subject vehicle is used to calculate the required inter-vehicle distance. From the above, the device DS of the embodiment can perform the attention alert activation operation at a more appropriate timing.

[0058] The present invention is not limited to the above embodiment and modified examples, and various modified examples can be adopted within the scope of the present invention. For example, the CPU may store a combination of the inter-vehicle distance Dint and the vehicle speed Vh as a value indicating the current situation, instead of the inter-vehicle time Tint, in S240. In this case, the lookup table (lookup table for storing the operation characteristic learning value) shown in block B1 of FIG. 3 is set to have an operation characteristic learning value for each combination of the inter-vehicle distance Dint and the vehicle speed Vh. Furthermore, in S505, the CPU reads out the operation characteristic learning value corresponding to the combination of the inter-vehicle distance Dint and the vehicle speed Vh at that time from the lookup table. Also, for example, the present invention is applicable to an autonomous vehicle in which the driving mode has transitioned from autonomous driving to driving by the driver. [Explanation of symbols]

[0059] 10...driving assistance ECU, 20...forward camera device, 30...radar device, 40...brake ECU, 41...brake actuator, 50...alarm ECU, 51...alarm display device, 52...alarm sound generating device, 73...brake pedal operation amount sensor, 74...brake switch, 75...vehicle speed sensor, 76...acceleration sensor.

Claims

1. A first acquisition device that acquires host vehicle information including information on a host vehicle speed, which is a speed of the host vehicle, and information on an operation state of a brake pedal of the host vehicle; a second acquisition device that acquires preceding vehicle information including information on a vehicle-to-vehicle distance between the preceding vehicle and the host vehicle and information on a relative speed of the preceding vehicle; an alarm device that executes at least one of displaying a warning and emitting an alarm sound as an attention-attracting operation for attracting the attention of a driver of the vehicle; A controller for controlling the alarm device; In a vehicle attention warning device comprising: The controller: when it is determined based on the host vehicle information and the preceding vehicle information that a predetermined sudden approach condition has been established, which is established when the host vehicle and the preceding vehicle begin to suddenly approach each other in a preceding vehicle following state in which the host vehicle is following the preceding vehicle due to a driving operation by the driver, an operation characteristic value that represents a characteristic of a deceleration operation for decelerating the host vehicle executed by the driver after the sudden approach condition is established is obtained based on the host vehicle information, and an operation characteristic learning value that changes according to the operation characteristic value is stored in a storage device; when it is determined that the preceding vehicle following state has newly occurred, the control device calculates a required inter-vehicle distance that the host vehicle should maintain between the host vehicle and the preceding vehicle using the operation characteristic learning value, and when it is determined that a warning condition is satisfied, the warning condition including a condition that is satisfied when the inter-vehicle distance is equal to or less than the required inter-vehicle distance, causes the warning device to execute the warning activation operation. It was configured as follows: Vehicle attention warning device.

2. The vehicle attention warning device according to claim 1, The controller: and determining whether or not the sudden approach condition is satisfied by determining whether or not a condition is satisfied in which the magnitude of the decrease amount of the inter-vehicle distance per unit time is equal to or greater than a threshold value in the preceding vehicle following state, based on the inter-vehicle distance or the relative speed. Vehicle attention warning device.

3. 3. The vehicle attention warning device according to claim 2, The controller: As the operational characteristic value, A reaction time that is the time from when the sudden approach condition is established to when the brake pedal operation is started; The deceleration of the host vehicle caused by the operation of the brake pedal after the sudden approach condition is satisfied, and a deceleration change rate, which is a magnitude of a change per unit time in the deceleration of the host vehicle caused by operation of the brake pedal after the sudden approach condition is satisfied; Get As the operation characteristic learning value, A reaction time learning value that changes depending on the acquired reaction time; A deceleration learning value that changes depending on the acquired deceleration; and a deceleration change rate learning value that changes according to the acquired deceleration change rate; storing the above in the storage device; The required vehicle distance is: a maximum approach distance, which is a maximum value of the magnitude of the reduction in the inter-vehicle distance until the time when the host vehicle and the preceding vehicle are estimated to be closest to each other, or a value based on the maximum approach distance, is calculated based on the reaction time learned value, the deceleration learned value, the deceleration change rate learned value, a preceding vehicle speed which is the current speed of the preceding vehicle calculated based on the host vehicle speed at the current time and the relative speed at the current time, and an assumed preceding vehicle deceleration which is a predetermined hypothetical deceleration of the preceding vehicle; It was configured as follows: Vehicle attention warning device.

4. The vehicle attention calling device according to claim 3, The controller: storing the operation characteristic learning value in association with one of a plurality of time ranges including a sudden approach time interval, the sudden approach time interval being a value obtained by dividing the inter-vehicle distance at the time when the sudden approach condition is satisfied by the host vehicle speed at the same time; calculating the required inter-vehicle distance using the operation characteristic learning value stored in association with one of the plurality of time ranges to which a new inter-vehicle time, which is a value obtained by dividing the inter-vehicle distance at the time when it is determined that the preceding vehicle following state has newly occurred by the host vehicle speed at the same time, belongs; It was configured as follows: Vehicle attention warning device.

5. A vehicle attention-attracting method for a vehicle, the method comprising: executing at least one of displaying a warning and emitting an alarm sound as an attention-attracting operation in order to attract the attention of a driver of the vehicle to a preceding vehicle; a step of determining whether or not a predetermined sudden approach condition is established when the host vehicle and the preceding vehicle start to suddenly approach each other in a preceding vehicle following state in which the host vehicle is following the preceding vehicle due to a driving operation by the driver; when it is determined that the sudden approach condition is satisfied, acquiring an operation characteristic value representing a characteristic of a deceleration operation for decelerating the host vehicle, which is executed by the driver after the time point when the sudden approach condition is satisfied, and storing an operation characteristic learning value that changes according to the operation characteristic value in a storage device; calculating a required inter-vehicle distance that the host vehicle should maintain between the host vehicle and the preceding vehicle using the operation characteristic learned value when it is determined that the preceding vehicle following state has newly occurred; executing the attention calling operation when it is determined that an attention calling condition including a condition that the inter-vehicle distance is equal to or less than the required inter-vehicle distance is satisfied; A method for alerting a vehicle, comprising:

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