Attention attracting device and attention attracting method for vehicle

Abstract

To perform an attention attracting operation of a vehicle at a more appropriate timing.SOLUTION: When a preceding vehicle suddenly approaches a user's vehicle in the state of following up the preceding vehicle by a driver, a driving support ECU 10 of an attention attracting device for a vehicle acquires operation characteristic values indicating characteristics of a deceleration operation for decelerating the user's vehicle 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. The driving support ECU acquires assumed deceleration of the preceding vehicle on the basis of a road type and / or a traffic flow. When 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, the assumed deceleration of the preceding vehicle, etc. 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 a vehicle attention calling device and an attention calling method that perform an attention calling operation to call the attention of a driver of a vehicle when the inter-vehicle 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 above conventional device calculates the maximum approach distance and the appropriate inter-vehicle distance using the actual deceleration of the preceding vehicle at the time when the preceding vehicle starts to decelerate. However, even if the preceding vehicle starts to decelerate and the vehicle is traveling to follow the preceding vehicle before the preceding vehicle starts to decelerate, it is desired to issue an alarm in preparation for the sudden deceleration of the preceding vehicle when the inter-vehicle distance is short. For this purpose, it is necessary to calculate the maximum approach distance assuming a certain value of the deceleration of the preceding vehicle. However, the deceleration of the preceding vehicle varies greatly depending on the road conditions (whether it is a highway for motor vehicles or a general road, and whether the traffic flow is congested or free, etc.). Therefore, if the maximum approach distance and the appropriate inter-vehicle distance are calculated under the assumption that the preceding vehicle decelerates at a uniform deceleration, there are cases in which they deviate significantly from the appropriate values. As a result, there is a risk that the alarm cannot be issued at the appropriate time.

[0005] The present invention has been made to solve such problems. That is, one of the objects of the present invention is to provide an attention calling device and an attention calling method for a vehicle that can perform an attention calling action (for example, a warning display and / or an alarm sound) at a more appropriate timing.

[0006] 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 (81-86) that acquires host vehicle information regarding a running state of the host vehicle, the host vehicle information including information regarding a host vehicle speed, the host vehicle speed being a speed of the host vehicle; a second acquisition device (20, 30) that acquires preceding vehicle information including information about a distance between the preceding vehicle and the host vehicle; A third acquisition device (60, 61, 70) for acquiring road traffic information including information on the road conditions on which the vehicle is traveling; an alarm device (50-52) 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; In a vehicle attention warning device comprising: The controller: An assumed preceding vehicle deceleration, which is a virtual deceleration of the preceding vehicle, is obtained according to the obtained road traffic information (S305, S510-S540); Calculating a required inter-vehicle distance that the host vehicle should maintain between the host vehicle and the preceding vehicle based on the host vehicle information, the preceding vehicle information, and the acquired assumed preceding vehicle deceleration (S305-S392); When it is determined that a warning condition is satisfied, the warning condition including a condition that is satisfied when the actual inter-vehicle distance obtained is equal to or less than the calculated required inter-vehicle distance, the warning device is caused to execute the warning activation action (S394).

[0007] According to this aspect, the assumed preceding vehicle deceleration, which is the virtual deceleration of the preceding vehicle, is acquired according to road traffic information (e.g., information on the road type and traffic flow), so that the required inter-vehicle distance is calculated based on the deceleration that is likely to occur as the actual deceleration when the preceding vehicle decelerates. Therefore, the attention alert can be activated at a more appropriate timing.

[0008] In addition, one aspect of the controller is As operation characteristic values ​​of the driver of the host vehicle, (1) a reaction time, which is the time from when the sudden approach condition is established to when the operation of the rake pedal is started, (2) a deceleration of the host vehicle caused by the operation of the brake pedal after the sudden approach condition is established, and (3) a deceleration change rate, which is the magnitude of the change per unit time in the deceleration of the host vehicle caused by the operation of the brake pedal after the sudden approach condition is established, are obtained. storing, as operation characteristic learned values, (1A) a reaction time learned value that changes in accordance with the acquired reaction time, (1B) a deceleration learned value that changes in accordance with the acquired deceleration, and (1C) a deceleration change rate learned value that changes in accordance with the acquired deceleration change rate; As the required inter-vehicle distance, a closest approach distance which is the maximum amount of reduction in the inter-vehicle distance up to the time when it is estimated that the host vehicle and the preceding vehicle are closest to each other, or a value based on the closest approach distance, is calculated based on the host vehicle speed, the reaction time learning value, the deceleration learning value, the deceleration change rate learning value, the preceding vehicle speed which is the current speed of the preceding vehicle, and the expected preceding vehicle deceleration.

[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] Graphs (A), (B) and (C) are graphs for explaining the maximum approach distance. [Diagram 5] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 6] Graphs (A) and (B) show the distribution of vehicle deceleration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The vehicle attention calling device (hereinafter referred to as "device DS") according to the embodiment of the present invention includes the components shown in Fig. 1 and is applied to (mounted on) a host vehicle. The host vehicle may be any of a vehicle powered by an internal combustion engine, an electric vehicle, a hybrid vehicle, and the like.

[0012] In this specification, an "ECU" is an electronic control unit equipped with a microcomputer including a CPU (processor), ROM, RAM, and a writable non-volatile memory, and 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 the camera information and the 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.

[0017] The brake ECU 40 controls the braking device by driving the brake actuator 41. That is, the brake ECU 40 adjusts the braking force of 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, in response to an instruction from the driving assistance ECU 10, causes the warning display device 51 to display a warning and causes the warning sound generation device 52 to generate a warning sound.

[0019] The navigation ECU 60 is connected to a GPS receiver 61, a map database 62, and a display touch panel 63. The navigation ECU 60 estimates the current position of the vehicle based on the GPS signal received by the GPS receiver 61. The navigation ECU 60 acquires information about the road to which the current position of the vehicle belongs, based on the estimated current position of the vehicle and the map database 62. The road information includes the type of road on which the vehicle is currently traveling (i.e., road type information about whether the road is a highway for motor vehicles or a general road).

[0020] The communication ECU 70 communicates with devices external to the vehicle (e.g., roadside devices and information centers that provide information including congestion information and road construction information) and acquires various information from the external devices. This information includes the type of road (or lane) on which the vehicle is traveling, and "vehicle density k and traffic volume q" on the road. Density k is the number of vehicles present within a "predetermined distance (e.g., 1 km) per lane" that includes the current position of the vehicle. Traffic volume q is the number of vehicles passing the current position of the vehicle or a nearby position on the lane on which the vehicle is traveling per unit time (e.g., 1 hour).

[0021] The driving assistance ECU 10 receives detection values ​​(output values) of the following "sensors and switches." An accelerator pedal operation amount sensor 81 that detects the operation amount AP of the accelerator pedal of the host vehicle. An accelerator switch 82 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 83 detects an operation amount BP of the brake pedal of the host vehicle. A brake switch 84 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 85 detects the speed of the host vehicle (i.e., host vehicle speed Vh). An acceleration sensor 86 that detects the longitudinal acceleration G of the host vehicle. In this specification, the longitudinal deceleration of the host vehicle (negative acceleration G) is represented as a positive value Gh (=-G>0).

[0022] (Overview of operation) When the driver of the vehicle is driving the vehicle 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 suddenly begins to approach the vehicle, the device DS obtains the value described below as "an operation characteristic value representing the characteristics of the deceleration operation performed by the driver to decelerate the vehicle."

[0023] 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 the deceleration operation (the time when the signal of the brake switch 74 changes from an OFF signal to an ON signal). This time is also called the "reaction time." -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 average 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 reaches maximum deceleration (average deceleration rate).

[0024] Based on the measured operating characteristic values, device DS calculates an operating characteristic learning 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 the calculated operating characteristic learning value for that inter-vehicle time zone in non-volatile memory.

[0025] 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 values ​​(reaction time learning value, maximum deceleration learning value, and deceleration change rate learning value) corresponding to the vehicle headway time at that time from the non-volatile memory. Furthermore, the device DS sets the expected preceding vehicle deceleration Gp to a value that changes based on at least one of "the type of road on which the vehicle is traveling" and "distinguishing between free flow and congested flow" as described later, obtains the current vehicle speed Vh, and calculates the current preceding vehicle speed Vp from the vehicle speed Vh and the relative speed Vr. The device DS then calculates the maximum approach distance using these values, and calculates the distance based on the maximum approach distance as the required vehicle headway distance. The maximum approach distance is the change (reduced distance) in the vehicle headway distance from the time when the preceding vehicle starts to approach the vehicle to the time when the vehicle is closest to the preceding vehicle. The device DS displays a warning and / or generates an alarm when a condition that is satisfied when the actual inter-vehicle distance is equal to or smaller than the required inter-vehicle distance continues for a certain period of time or longer.

[0026] (Specific operation) <Learned value acquisition> The CPU of the driving assistance ECU 10 (hereinafter simply referred to as "CPU") executes a routine shown in the flowchart of FIG. 2 every time a predetermined time (calculation period) dt elapses.

[0027] When an appropriate time arrives, the CPU starts processing from step 200 (hereinafter, "step" will be written as "S") in FIG. 2 and proceeds to S210 to determine whether or not a sudden approach condition that is established when the host vehicle and the preceding vehicle suddenly approach each other is established. The sudden approach condition is established when a preceding vehicle is present and the inter-vehicle distance between the preceding vehicle and the host vehicle is suddenly decreasing. More specifically, in S210, the CPU determines whether or not a sudden approach condition is established in which a relative speed increase amount dVr, which is a value obtained by subtracting the relative speed Vrold from the current relative speed Vr a predetermined time ago, is equal to or greater than a threshold relative speed dVrth. If the sudden approach condition is not established, the CPU proceeds directly from S210 to S295 and ends this routine for the time being.

[0028] On the other hand, if the CPU determines that the sudden approach condition is established, the process proceeds from S210 to S220, where it determines whether the preceding vehicle following state has continued for a threshold time or more up to the time point immediately before the current time point. When the CPU determines that a preceding vehicle exists based on the camera information and radar information, determines that the inter-vehicle distance Dint between the host vehicle and the preceding vehicle acquired based on the camera information and radar information is equal to or less than the threshold distance Dth, and determines that the signal (brake signal) of the brake switch 84 is an off signal, it determines that the preceding vehicle following condition is established and that the preceding vehicle following state is occurring.

[0029] If the CPU determines that the preceding vehicle following state has continued for a threshold time or longer up to the current time point, the process proceeds from S220 to S230, and stores the inter-vehicle time Tint, which is the inter-vehicle distance Dint divided by the host vehicle speed Vh, as a value indicating the situation at the time when the sudden approach condition was established.

[0030] Next, the CPU proceeds to S240 and obtains operation characteristic values ​​(reaction time Tre, maximum deceleration Gmx, and average deceleration change rate Ja) for a single deceleration operation performed while the preceding vehicle continues to be present after the sudden approach condition is met (S210: Yes).

[0031] The reaction time Tre is the time from when it is determined that the sudden approach condition is satisfied to when a deceleration operation is performed. Whether or not a deceleration operation has been performed is determined by determining whether or not the signal of the brake switch 84 has changed from an off signal to an on signal. The CPU may determine that a deceleration operation has been performed when the signal of the accelerator switch 82 has changed from an on signal to an off signal.

[0032] The maximum deceleration Gmx is the maximum value of the deceleration Gm of the vehicle during the deceleration period from the point at which the deceleration operation is performed after it is determined that the sudden approach condition is met to the point at which the deceleration operation is ended or the vehicle stops, whichever occurs first.

[0033] The average deceleration change rate Ja is the average value of the deceleration change rate (the amount of increase in deceleration per unit time, which is a value obtained by inverting the sign of the jerk) from the time when it is determined that the sudden approach condition is satisfied to the time when the deceleration of the host vehicle reaches the maximum deceleration. If the preceding vehicle no longer exists during the deceleration period, the CPU stops obtaining the operation characteristic value and proceeds to S295.

[0034] When the CPU finishes acquiring the operation characteristic values ​​in S240, it proceeds to S250, where it updates the operation characteristic learned values ​​(reaction time learned value Tr, maximum deceleration learned value Gm, and deceleration change rate learned value Jm) for the "time interval Tint indicating the situation at the time when the sudden approach condition is established" stored in S230 based on each of the operation characteristic values ​​acquired in S240 (reaction time Tre, maximum deceleration Gmx, and average deceleration change rate Ja) as described below.Then, the CPU proceeds to S295.

[0035] The driving assistance ECU 10 stores in a non-volatile memory the look-up table LT shown in Fig. 2. This look-up table LT is configured to divide the inter-vehicle time into a plurality of inter-vehicle time periods (time ranges) and to store the operation characteristic learning values ​​(Tr, Gm, and Jm) for each inter-vehicle time period.

[0036] The CPU reads out from the lookup table LT the reaction time learning value Tr which belongs to the inter-vehicle time zone to which the inter-vehicle time Tint stored in S230 belongs. For example, if the inter-vehicle time Tint is between time T2 and time T3, the CPU reads out from the lookup table LT the reaction time learning value Trn (n=2) of the inter-vehicle time zone to which the inter-vehicle time Tint belongs. Next, the CPU updates the reaction time learning value Tr (=Trn) by substituting the reaction time Tre acquired in S240 and the read reaction time learning value Trn (n is a natural number from 1 to m) into the right side of the formula (Tr=α·Tre+(1-α)·Trn), and stores the updated reaction time learning value Tr in the table LT as the reaction time learning value Tr which belongs to the inter-vehicle time zone to which the inter-vehicle time Tint stored in S230 belongs. "α" is a predetermined value between "0" and "1".

[0037] The CPU reads out from the lookup table LT the maximum deceleration learned value Gm which belongs to the time interval to which the time headway Tint stored in S230 belongs. For example, if the time headway Tint is between time T2 and time T3, the CPU reads out from the lookup table LT the maximum deceleration learned value Gmn (n=2) for the time interval to which the time headway Tint belongs. Next, the CPU updates the maximum deceleration learned value Gm (=Gmn) by substituting the maximum deceleration Gmx acquired in S240 and the read maximum deceleration Gmn (n is a natural number from 1 to m) into the right side of the equation (Gm=α·Gmx+(1-α)·Gmn), and stores the updated maximum deceleration learned value Gm in the lookup table LT as the maximum deceleration learned value Gm which belongs to the time interval to which the time headway Tint stored in S230 belongs.

[0038] The CPU reads out from the lookup table LT the deceleration change rate learning value Jm which belongs to the time interval to which the time headway Tint stored in S230 belongs. For example, if the time headway Tint is between time T2 and time T3, the CPU reads out from the lookup table LT the deceleration change rate learning value Jmn (n=2) for the time interval to which the time headway Tint belongs. Next, the CPU updates the deceleration change rate learning value Jm (=Jmn) by substituting the average deceleration change rate Ja acquired in S240 and the read deceleration change rate learning value Jmn (n is a natural number from 1 to m) into the right side of the equation (Jm=α·Ja+(1-α)·Jmn), and stores the updated deceleration change rate learning value Jm in the lookup table LT as the deceleration change rate learning value Jm which belongs to the time interval to which the time headway Tint stored in S230 belongs.

[0039] <Calculation of required vehicle distance and warning control> The CPU determines whether the current state is a new state of following the preceding vehicle (whether the preceding vehicle following condition described above is satisfied) by a routine not shown (see S220 in FIG. 2). If the CPU determines that a new state of following the preceding vehicle has occurred, it executes the routine shown in the flowchart in FIG. 3 every time a predetermined time dt elapses as long as the preceding vehicle following state continues.

[0040] Therefore, if a preceding vehicle following state occurs, the CPU starts the process from S300 in Fig. 3 and proceeds to S305, where it reads out the learned values ​​(reaction time learned value Tr, maximum deceleration learned value Gm, and deceleration change rate learned value Jm) corresponding to the current inter-vehicle time Tint from the lookup table LT shown in Fig. 2. Furthermore, the CPU sets the expected preceding vehicle deceleration Gp to a predetermined value according to the "type of road on which the host vehicle is traveling" and "distinguishing between free flow and congested flow" as described in detail later (see Fig. 5). In addition, the CPU obtains 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.

[0041] In S310, 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).

[0042] Next, if the calculated preceding vehicle speed Vp is equal to or less than "0" through the processing of S315 and S320 (i.e., if the preceding vehicle is calculated to be stopped, S315: No), the CPU sets the assumed preceding vehicle deceleration Gp and preceding vehicle speed Vp to "0" (S320). 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 "S325 and S330" described below.

[0043] S325: 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. S330: 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.

[0044] Next, the CPU updates the host vehicle deceleration Gh by performing the processing of an appropriate step among S335 to S355. That is, the CPU sets the host vehicle deceleration Gh to "0" (S340) until the elapsed time Ti reaches the reaction time learning value Tr (S335: No). On the other hand, if the elapsed time Ti is longer than the reaction time learning value Tr (S335: Yes) and the absolute value of the host vehicle deceleration Gh is equal to or smaller than the absolute value of the maximum deceleration learning value Gm (S345: 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 (S350). If the absolute value of the host vehicle deceleration Gh is greater than the absolute value of the maximum deceleration learning value Gm (S345: Yes), the CPU sets the host vehicle deceleration Gh to the maximum deceleration learning value Gm (S355).

[0045] Next, the CPU performs the processes of "S360 to S370" described below. S360: 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. S365: 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. S370: The CPU calculates the approach distance Da by subtracting the preceding vehicle travel distance Dp from the host vehicle travel distance Dh.

[0046] Next, the CPU performs the processes of S375 and S380, and if the approach distance Da calculated in S370 is greater than the "maximum approach distance Dmax held at that time" (S375: Yes), it sets the maximum approach distance Dmax to the approach distance Da calculated in S370. If the approach distance Da calculated in S370 is less than or equal to the "maximum approach distance Dmax held at that time" (S375: No), the CPU holds the maximum approach distance Dmax at that time.

[0047] Next, the CPU proceeds to S385, where it determines whether the host vehicle speed Vh is equal to or less than "0" (i.e., whether the host vehicle has been mathematically stopped). If the host vehicle speed Vh is greater than "0", the CPU proceeds from S385 to S390, where it increases the elapsed time Ti by the calculation cycle dt, and then returns to S315.

[0048] On the other hand, if the host vehicle speed Vh is equal to or less than "0", the CPU proceeds from S385 to S392 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".

[0049] Next, the CPU proceeds to S394, where it determines whether or not a state in which the actual inter-vehicle distance Dint is equal to or shorter than the required inter-vehicle distance Dreq (short inter-vehicle distance state) continues for a certain period of time or more, and performs an attention-calling operation if the short inter-vehicle distance state continues for a certain period of time or more. That is, the CPU causes the warning display device 51 to display an attention-calling pattern and / or characters that notify the driver that the inter-vehicle distance is too short, and causes the warning sound generating device 52 to generate an attention-calling sound (or voice message that notifies the driver that the inter-vehicle distance is too short).

[0050] Fig. 4 is a graph showing "own vehicle speed, preceding vehicle speed, approach distance, and maximum approach distance" calculated by the above-mentioned method. Fig. 4(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. 4(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. 4(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.

[0051] <Acquisition of expected preceding vehicle deceleration Gp> As described above, the CPU sets the expected preceding vehicle deceleration Gp to a predetermined value according to the "type of road on which the host vehicle is traveling" and "whether the road is free flow or congested flow" in S305 of Fig. 3. This point will be described below.

[0052] When the CPU proceeds to S305 in Fig. 3, it starts the process from S500 in Fig. 5 and sequentially performs the processes of "S510 to S540" described below. After that, the CPU proceeds to S595 to temporarily end this routine and returns to S305 in Fig. 3.

[0053] S510: The CPU acquires "road type information indicating the type of the road on which the vehicle is currently traveling" via the navigation ECU 60. The CPU may acquire the road type information from the communication ECU 70 or an external device.

[0054] S520: The CPU acquires the "density k and traffic volume q" of the road (lane) on which the host vehicle is currently traveling from an external device via the communication ECU 70. The CPU may acquire the density k and traffic volume q via the navigation ECU 60.

[0055] S530: The CPU applies the traffic information point determined by the density k and the traffic volume q to the map shown in S530 of FIG. 5, and judges whether the traffic state point is above the line L1. If the traffic state point is above the line L1, the CPU judges that the traffic flow of the road on which the vehicle is traveling is a free flow (a natural flow without congestion). If the traffic state point is below the line L1, the CPU judges that the traffic flow of the road on which the vehicle is traveling is a jammed flow (a flow with congestion). According to the analysis of big data, it has been found that when the traffic flow is a free flow, the traffic state point is located within the range AFree centered on the line L2. According to the analysis of big data, it has been found that when the traffic flow is a jammed flow, the traffic state point is located within the range AJam centered on the line L3. Furthermore, analysis of big data revealed that when the speed of the traffic flow (the average speed of multiple vehicles belonging to a specific section of the road in question) is higher than 45 km / h (see line L1), the traffic flow is free flowing, and when the speed of the traffic flow is lower than 45 km / h, the traffic flow is congested.

[0056] S540: The CPU determines the expected preceding vehicle deceleration Gp by applying the road type (whether a motorway or a general road) and traffic flow (free flow or congested flow) as the road traffic information acquired in S510 to S530 to a lookup table LU stored in the non-volatile memory shown in S540. For example, when the road type is a motorway and the traffic flow is free flow, the expected preceding vehicle deceleration Gp is ​​set to a value Gphf.

[0057] Incidentally, Figure 6 (A) shows the frequency distribution of deceleration when traffic is free flowing and the road type is an expressway and an ordinary road. As can be seen from this graph, there are practically no intersections or pedestrians on an expressway, so there are fewer factors that cause deceleration compared to ordinary roads. Therefore, the frequency with which large deceleration occurs is lower on an expressway than on ordinary roads. For example, the 2σ (standard deviation = σ) deceleration on one expressway among expressways is 1.4 m / s 2 The 2σ deceleration on a general road is 2.6m / s 2 It is.

[0058] FIG. 6B shows the frequency distribution of deceleration when the road type is a general road and when the traffic flow is free flow and when the traffic flow is congested flow. As can be seen from this graph, when the traffic flow is congested flow, the vehicle deceleration occurs frequently. Therefore, when the traffic flow is congested flow, the frequency of large deceleration occurring is higher compared to when the traffic flow is free flow. Based on such data, the assumed deceleration of the above-mentioned lookup table LU is determined. In order to prevent a delay in the attention alert activation, each value of the preceding vehicle deceleration in the lookup table LU is set to a value equivalent to about 2σ in the frequency distribution of deceleration in each case.

[0059] As described above, according to the embodiment of the present invention, the "operation characteristic learning value used when calculating the required inter-vehicle distance" is updated based on the operation characteristic value measured in a tense state where the sudden approach condition is satisfied, so that the operation characteristic learning value becomes a value that appropriately represents the driver's operation characteristic in a "tense state when the preceding vehicle suddenly starts to decelerate rapidly." Furthermore, the expected preceding vehicle deceleration, which is the virtual deceleration of the preceding vehicle, is acquired according to road traffic information (information about the road type and traffic flow), so that the required inter-vehicle distance is calculated based on the deceleration that the preceding vehicle is likely to actually occur. Therefore, the attention alert operation can be performed at a more appropriate timing.

[0060] The present invention is not limited to the above-described embodiment and modified examples, and various modified examples can be adopted within the scope of the present invention. The present invention can be applied to an autonomous vehicle in which the driving mode has transitioned from autonomous driving to driving by a driver. Furthermore, the CPU may determine the expected preceding vehicle deceleration based on only one of the road type and the traffic flow. Furthermore, the road type may be further divided into specific expressways, specific sections of general roads, and the like. Furthermore, the road traffic information acquired by the ECU 60 or ECU 70 may include information indicating whether the traffic flow on the road on which the host vehicle is traveling is a congested flow or a free flow, in which case S520 and S530 may be omitted. [Explanation of symbols]

[0061] 10... driving assistance ECU, 20... front camera device, 30... radar device, 50... warning ECU, 60... navigation ECU, 70... communication ECU.

Claims

1. A first acquisition device that acquires host vehicle information regarding a running state of the host vehicle, the host vehicle information including information regarding a host vehicle speed, the host vehicle being a speed of the host vehicle; a second acquisition device that acquires preceding vehicle information including information about a distance between the preceding vehicle and the host vehicle; a third acquisition device that acquires road traffic information including information on a road condition on which the host vehicle is traveling; 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: acquiring an assumed preceding vehicle deceleration, which is a virtual deceleration of the preceding vehicle, in accordance with the acquired road traffic information; calculating a required inter-vehicle distance that the host vehicle should maintain between the host vehicle and the preceding vehicle based on the host vehicle information, the preceding vehicle information, and the acquired assumed preceding vehicle deceleration; causing the warning device to execute the attention-calling operation when it is determined that an attention-calling condition is satisfied, the attention-calling condition including a condition that is satisfied when the acquired actual inter-vehicle distance is equal to or shorter than the calculated required inter-vehicle distance; It was configured as follows: Vehicle attention warning device.

2. The vehicle attention warning device according to claim 1, The third acquisition device is configured to acquire, as the road traffic information, a type of a road on which the host vehicle is traveling; The controller is configured to acquire the expected preceding vehicle deceleration according to the road type. Vehicle attention warning device.

3. The vehicle attention calling device according to claim 1 or 2, the third acquisition device is configured to acquire, as the road traffic information, congestion information indicating whether a traffic flow on a road on which the host vehicle is traveling is a congestion flow or a free flow, The controller is configured to obtain the expected preceding vehicle deceleration in response to the congestion information. Vehicle attention warning device.

4. The vehicle attention calling device according to claim 3, 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 driving operation by the driver of the host vehicle, 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, 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 required inter-vehicle distance is calculated using the subject vehicle information, the preceding vehicle information, the acquired assumed preceding vehicle deceleration, and the operation characteristic learning value; 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; acquiring road traffic information including information about a road on which the host vehicle is traveling; acquiring an assumed preceding vehicle deceleration, which is a virtual deceleration of the preceding vehicle, in accordance with the acquired road traffic information; calculating a required inter-vehicle distance that the host vehicle should maintain between the host vehicle and the preceding vehicle based on at least the acquired assumed deceleration of the preceding vehicle; executing the attention calling operation when it is determined that an attention calling condition is satisfied, the attention calling condition including a condition that is satisfied when the acquired inter-vehicle distance is equal to or shorter than the required inter-vehicle distance; A method for alerting a vehicle, comprising:

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