Vehicle travel control device

Abstract

A travel control device for a vehicle includes a drive assist ECU that calculates a time to collision until a collision between the host vehicle and an automatic braking target object in front of the host vehicle detected by an object information acquisition device, based on a relative relationship between the host vehicle and the automatic braking target object, and executes automatic braking for preventing the collision between the host vehicle and the automatic braking target object when it is determined that the time to collision is below a reference value. The drive assist ECU calculates a ratio of a deceleration of the host vehicle to an amount of brake operation by a driver when the brake operation is performed, in a state where the automatic braking is not executed, and variably sets the reference value according to the ratio so that the smaller the ratio is, the larger the reference value is.

Description

Technical Field

[0001] This invention relates to a driving control device for automobiles and other vehicles, and more specifically, to a driving control device that reduces the risk of collision between the vehicle and obstacles. Background Technology

[0002] As one type of driving control device, there is a known braking control device that, upon detecting a collision, continuously and automatically generates a constant braking force to decelerate the vehicle until the control ends.

[0003] For example, Patent Document 1 describes a braking control device that detects the actual deceleration of a vehicle while automatic braking control is being performed, and sets a longer control end time when the actual deceleration is low compared to when the actual deceleration is high.

[0004] According to this driving control device, for example, when the actual deceleration is low due to the low coefficient of friction of the road surface, the control end time is set to be longer, and the automatic braking control lasts longer. Therefore, compared with the case where the control end time is not set to be longer, the vehicle speed can be reduced more, and the effect of mitigating damage can be improved.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-47980 Summary of the Invention

[0006] The conventional driving control device described in Patent Document 1 can mitigate post-collision damage in situations where the road surface friction coefficient is low. However, in situations where the road surface friction coefficient is low and there is a risk of a vehicle collision, it cannot effectively slow down the vehicle to effectively reduce the risk of a collision.

[0007] The present invention provides a driving control device that is improved to effectively decelerate the vehicle even when there is a risk of collision, under conditions of low road surface friction coefficient.

[0008] [The means used to solve the problem and the effects of the invention]

[0009] According to the present invention, a vehicle driving control device (100) is provided, comprising: a detection device (object information acquisition device 18) that detects an automatically braking object existing in front of the vehicle (102) in the direction of travel; and a control unit (driving assistance ECU 10) configured to calculate the time to collision (TTC) before the vehicle collides with the automatically braking object based on the relative relationship between the automatically braking object and the vehicle (S30), and when it is determined that the time to collision is less than or equal to a reference value (TTC2) (S130), to perform automatic braking to prevent the vehicle from colliding with the automatically braking object (S140).

[0010] The control unit (driving assistance ECU10) is configured to calculate the ratio (Rp) of the vehicle's deceleration to the amount of braking by the driver when the driver performs braking operation without automatic braking (S60), and to variably set a reference value based on the ratio so that the smaller the ratio, the larger the reference value (S70, S80, S90).

[0011] When the vehicle is braked by the driver without automatic braking engaged, the ratio of the vehicle's deceleration to the amount of braking applied by the driver corresponds to the ratio of the vehicle's actual braking force to the amount of braking applied by the driver. The lower the coefficient of friction of the road surface, the smaller this ratio. The lower the ratio of the vehicle's deceleration to the amount of braking applied by the driver, the longer the vehicle requires to decelerate, and the longer the braking distance.

[0012] Based on the aforementioned driving control device, the ratio of the vehicle's deceleration to the driver's braking amount when braking is performed by the driver without automatic braking is calculated. A reference value is variably set based on this ratio, such that the smaller the ratio, the larger the reference value. The larger the reference value, the earlier the determination is made that the time from the vehicle's collision with the object subject to automatic braking is less than or equal to the reference value.

[0013] Therefore, the smaller the ratio of the vehicle's deceleration to the driver's braking input, the larger the reference value can be, and the determination that the collision time is below the reference value can be made earlier. Thus, automatic braking can be initiated earlier, extending the vehicle's deceleration time based on automatic braking. Therefore, compared to the previous method where the reference value was not variably set based on the ratio, the risk of the vehicle colliding with the object being automatically braked can be effectively reduced.

[0014] Furthermore, the target braking force or target deceleration in the automatic braking control will not increase. Therefore, it can prevent the following situation: the braking force of the vehicle becomes too large due to an increase in the target braking force or target deceleration, causing the wheels to lock up and the vehicle's deceleration to decrease instead.

[0015] [Method of Invention]

[0016] In one embodiment of the present invention, the control unit (driving assistance ECU 10) is configured to acquire data on the amount of braking operation performed by the driver within a predetermined time period up to the present, and the deceleration of the vehicle, up to a reference number (S61, S91), and calculate the average value of the ratio of the vehicle's deceleration to the amount of braking operation performed by the driver for each data point, thereby calculating the ratio of the vehicle's deceleration to the amount of braking operation performed by the driver (S62, S92).

[0017] According to the above method, for braking operations performed by the driver within a predetermined time period up to the present, data on the amount of braking by the driver and the deceleration of the vehicle above a certain threshold are obtained. Furthermore, the average value of the ratio of the vehicle's deceleration to the amount of braking by the driver for each data point is calculated, thereby determining the ratio of the vehicle's deceleration to the amount of braking by the driver when braking is performed.

[0018] Therefore, it is possible to prevent the following situation: obtaining data on the amount of braking by the driver and the deceleration of the vehicle up to a predetermined time ago, and calculating the ratio of the vehicle's deceleration to the amount of braking by the driver based on data including this old data.

[0019] Furthermore, data on the driver's braking input and the vehicle's deceleration for values ​​above a reference number are obtained, and the average of the ratio of the vehicle's deceleration to the driver's braking input for each data point is calculated. This allows for the determination of the ratio of the vehicle's deceleration to the driver's braking input. Therefore, compared to calculating the ratio based on data of the driver's braking input and the vehicle's deceleration for values ​​below the reference number, this method can accurately determine the ratio of the vehicle's deceleration to the driver's braking input. In particular, it reduces the risk that calculating the ratio based on instantaneous abnormal deceleration data could lead to an inappropriate value, or that the reference value could be set inappropriately.

[0020] In another embodiment of the invention, the control unit (driving assistance ECU 10) includes a storage device (non-volatile memory) for storing ratios. The control unit is configured to, when a new ratio is obtained, increase or decrease a reference value based on the difference between the new ratio and the ratio stored in the storage device (S60, S70), and then store the new ratio in the storage device in an overwrite manner (S80).

[0021] According to the above method, when a new ratio is obtained, the reference value is increased or decreased based on the difference between the new ratio and the ratio stored in the storage device, and then the new ratio is stored in the storage device in an overwrite manner. Therefore, by increasing or decreasing the reference value based on the difference between the new ratio and the ratio stored in the storage device, the reference value can be variably set according to the ratio.

[0022] In another embodiment of the invention, the control unit (driving assistance ECU 10) is configured to increase the reference value based on the difference when the new ratio is less than the ratio stored in the storage device (S71, S72).

[0023] According to the above method, when the new ratio is less than the ratio stored in the storage device, the reference value is increased based on the difference. Therefore, when a new ratio is obtained, and the new ratio is less than the ratio stored in the storage device, the reference value can be increased based on the difference.

[0024] In another embodiment of the invention, the control unit (driving assistance ECU 10) includes a storage device (ROM) that stores a standard value of a ratio pre-calculated for a road surface with a standard coefficient of friction. The control unit is configured to variably set a reference value based on the difference between the new ratio and the standard value when a new ratio is calculated (S90).

[0025] According to the above method, when a new ratio is obtained, the reference value is variably set based on the difference between the new ratio and the standard value. Therefore, by variably setting the reference value based on the difference between the new ratio and the standard value, the reference value can be variably set according to the ratio.

[0026] In the foregoing description, to aid in understanding the invention, the names and / or symbols used in the embodiments described below are enclosed in parentheses to indicate the structure of the invention. However, the constituent elements of the invention are not limited to the constituent elements of the embodiments corresponding to the names and / or symbols enclosed in parentheses. Other objects, features, and incidental advantages of the invention can be readily understood by referring to the following description of the embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0027] Figure 1 This is a schematic structural diagram illustrating an embodiment of the vehicle driving control device of the present invention.

[0028] Figure 2 This is a flowchart corresponding to the driving control procedure in the first embodiment.

[0029] Figure 3 It is shown in Figure 2 The flowchart shows the routine for determining the necessity of updating the correction amount ΔT2 in step S60.

[0030] Figure 4It is shown in Figure 2 The flowchart shows the routine for controlling the operation of the correction amount ΔT2 in step S70.

[0031] Figure 5 This is a flowchart corresponding to the driving control procedure in the second embodiment.

[0032] Figure 6 It is shown in Figure 5 The flowchart shows the routine for controlling the operation of the correction amount ΔT2 in step S90. Detailed Implementation

[0033] Hereinafter, with reference to the accompanying drawings, a detailed description of the driving control device according to embodiments of the present invention will be provided.

[0034] like Figure 1 As shown, the driving control device 100 according to the embodiments of the present invention is applicable to a vehicle 102 and includes a driving assistance ECU 10. The vehicle 102 is a vehicle capable of autonomous driving and includes a drive ECU 20, a brake ECU 30, and an instrument ECU 50. ECU refers to an electronic control unit with a microcomputer as its main component. For the purpose of distinguishing it from other vehicles, the vehicle 102 is referred to as this vehicle 102 as needed.

[0035] Each ECU's microcomputer includes a CPU, ROM, RAM, read / write non-volatile memory (N / M), and interfaces (I / F). The CPU executes instructions (programs, routines) stored in the ROM to perform various functions. Furthermore, these ECUs are interconnected via a Controller Area Network (CAN) 104, enabling them to exchange (communicate) data. Therefore, detection values ​​from sensors (including switches) connected to a specific ECU are also sent to other ECUs.

[0036] The driver assistance ECU 10 is a central control device for driving control, including driving assistance functions such as driving control, following distance control, and lane keeping control. In this embodiment, as will be explained in detail below, the driver assistance ECU 10 cooperates with other ECUs to perform driving control for the vehicle 102. In the driving control of this embodiment, when the driver assistance ECU 10 determines that an obstacle in front of the vehicle in the direction of travel, which is an object of automatic braking, may collide with the vehicle, it issues a warning of this possibility. Furthermore, when the driver assistance ECU 10 determines that the probability of a collision with the obstacle has increased and there is a risk of collision, it performs automatic braking control to reduce this risk. The obstacle is an object that, in the event of a collision, would cause damage to the vehicle and / or the other party, such as a stopped vehicle, a vehicle traveling at low speed ahead, or a pedestrian crossing the road.

[0037] A camera sensor 12, a radar sensor 14, and a setting operator 16 are connected to the driver assistance ECU 10. The camera sensor 12 and the radar sensor 14 each include multiple camera devices and multiple radar devices. The camera sensor 12 and the radar sensor 14 function as a landmark information acquisition device 18 for acquiring landmark information around the vehicle 102.

[0038] Although not shown in the figure, each camera device of the camera sensor 12 includes: a camera unit that captures images of the area around the vehicle 102; and an identification unit that analyzes the image data captured by the camera unit to identify road markings, other vehicles, and other objects. The identification unit supplies the identified object-related information to the driver assistance ECU 10 at predetermined intervals.

[0039] Each radar device of radar sensor 14 includes a radar transceiver unit and a signal processing unit (not shown). The radar transceiver unit transmits millimeter-wave radio waves (hereinafter referred to as "millimeter waves") and receives millimeter waves (i.e., reflected waves) reflected by three-dimensional objects (e.g., other vehicles, bicycles, etc.) within the transmission range. The signal processing unit supplies information such as the distance between the vehicle and the three-dimensional object, the relative speed between the vehicle and the three-dimensional object, and the relative position (direction) of the three-dimensional object relative to the vehicle to the driver assistance ECU 10 at predetermined intervals based on the phase difference between the transmitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from the transmission of the millimeter waves to the reception of the reflected waves.

[0040] Alternatively, light detection and ranging (LiDAR) can be used in place of radar sensor 14 or in addition to radar sensor 14.

[0041] Setting the operator 16 to such Figure 1It is a position that can be operated by the driver, as shown in the diagram, and is operated by the driver. Although not in Figure 1 As shown, the setting operator 16 includes a driving assistance switch. As detailed below, when the driving assistance switch is on, the driving assistance ECU 10 performs driving control.

[0042] The drive ECU 20 is connected to a drive unit 22 that accelerates the vehicle 102 by applying driving force to the drive wheels 24. Under normal circumstances, the drive ECU 20 controls the drive unit 22 so that the driving force generated by the drive unit 22 changes according to the driving operation performed by the driver. When it receives a command signal from the driving assistance ECU 10, it controls the drive unit 22 based on the command signal.

[0043] A braking device 32 is connected to the braking ECU 30. The braking device 32 decelerates the vehicle 102 by applying braking force to the wheels 34. Under normal circumstances, the braking ECU 30 controls the braking device so that the braking force generated by the braking device 32 varies according to the braking operation performed by the driver. When a command signal is received from the driving assistance ECU 10, the braking device 32 is controlled based on the command signal, thereby performing automatic braking.

[0044] Therefore, the braking ECU 30 and the braking device 32 cooperate to function as the automatic braking device 36. Furthermore, when applying braking force to the wheels through driving control, etc., [the system] does not [operate in a controlled manner]. Figure 1 The brake lights shown in the image are illuminated.

[0045] A touch panel-type display 52, which displays the status of control based on the driver assistance ECU 10, and an alarm device 54, which issues warnings, are connected to the instrument cluster ECU 50. The display 52 may be, for example, a multi-information display showing instrument-related and various information, or it may be the display of the navigation device 80 described later. As will be described later, when the display 52 receives a signal from the driver assistance ECU 10, it displays the status of driving control.

[0046] When it is determined that there is a risk of collision between vehicle 102 and a controlled object such as an obstacle, the alarm device 54 activates and issues an alarm indicating that there is a risk of collision between vehicle 102 and the controlled object. The alarm device 54 can be any one of the following: a visual alarm device such as a warning light; an auditory alarm device such as an alarm buzzer; or a tactile alarm device such as seat vibration; or any combination thereof.

[0047] The driving operation sensor 60 and the vehicle status sensor 70 are also connected to the CAN 104. Information detected by the driving operation sensor 60 and the vehicle status sensor 70 (referred to as sensor information) is sent to the CAN 104. The sensor information sent to the CAN 104 can be appropriately utilized in each ECU. Furthermore, the sensor information can be information from sensors connected to a specific ECU, and can be sent from that specific ECU to the CAN 104.

[0048] The driving operation sensor 60 includes a drive operation sensor that detects the amount of accelerator pedal operation, a brake operation sensor that detects master cylinder pressure or the force Fbp applied to the brake pedal, and a brake switch that detects whether the brake pedal has been operated. Furthermore, the driving operation sensor 60 includes a steering angle sensor that detects the steering angle, a steering torque sensor that detects the steering torque, and so on.

[0049] The vehicle status sensor 70 includes a vehicle speed sensor for detecting the vehicle speed V of the vehicle 102, a front-rear acceleration sensor for detecting the vehicle's front-to-back acceleration Gx, a lateral acceleration sensor for detecting the vehicle's lateral acceleration, and a yaw rate sensor for detecting the vehicle's yaw rate.

[0050] In the first embodiment, the ROM of the driving assistance ECU 10 stores information related to... Figures 2 to 4 The flowchart shown corresponds to the driving control program. Furthermore, in the second embodiment, the ROM of the driving assistance ECU 10 stores the driving control program... Figure 5 and Figure 6 The flowchart shown corresponds to the driving control program.

[0051] [First Implementation Method]

[0052] <Driving control ( Figures 2 to 4 >

[0053] Next, refer to Figures 2 to 4 The flowchart shown illustrates the driving control in the first embodiment. Figures 2 to 4 The driving control shown in the flowchart is repeatedly executed by the CPU of the driving assistance ECU10 at predetermined intervals when the driving assistance switch is turned on.

[0054] First, in step S10, the CPU determines, for example, whether there is an obstacle such as a stopped vehicle in front of the vehicle 102 using camera sensor 12 or radar sensor 14. If a negative determination is made, step S10 is repeated; if a positive determination is made, the control proceeds to step S20.

[0055] In step S20, the CPU determines whether to perform automatic braking to prevent the vehicle 102 from colliding with an obstacle. If the determination is positive, the control proceeds to step S100; if the determination is negative, the control proceeds to step S30.

[0056] In step S30, the CPU acquires, for example, information about the relative distance Lr between the vehicle and the obstacle, and the relative speed Vr of the vehicle relative to the obstacle, detected by the camera sensor 12 or the radar sensor 14. Furthermore, based on the relative distance Lr and relative speed Vr, the CPU determines whether a collision is likely and whether a collision warning should be issued. If a positive determination is made, the control proceeds to step S120; if a negative determination is made, the control proceeds to step S40. Additionally, in the case of a negative determination, if a warning has already been issued, the issuance of the warning is terminated.

[0057] Furthermore, the predicted time until the vehicle collides with the obstacle, i.e., the collision prediction time (TTC), is calculated by dividing the relative distance Lr by the relative speed Vr. When the TTC is below the first reference value TTC1 (a positive constant), it is determined that the vehicle is likely to collide with the obstacle. The collision prediction time TTC is an indicator of the probability of the vehicle colliding with the vehicle in front; the smaller the value, the higher the probability (danger) of the vehicle colliding with the vehicle in front. In addition, the first reference value TTC1 can be variably set to large, medium, or small values ​​(each a positive constant) by the setting device included in the setting operator 16.

[0058] In step S40, the CPU determines whether the driver has performed the braking operation based on the braking operation amount detected by the braking operation amount detection sensor, the state of the brake switch, etc. If a negative determination is made, the control returns to step S10; if a positive determination is made, the control proceeds to step S50.

[0059] In step S50, the CPU acquires information about the braking force Fbp detected by the braking operation amount detection sensor and the acceleration Gx in the longitudinal direction of the vehicle 102, i.e., the deceleration Gb of the vehicle, detected by the front and rear acceleration sensors. Furthermore, the deceleration Gb becomes a positive value when the acceleration Gx is negative, and its magnitude is the same as the absolute value of the acceleration Gx.

[0060] In step S60, the CPU determines whether it needs to follow... Figure 3 The subroutine shown updates the correction amount ΔT2 of the second reference value TTC2 (a positive value less than TTC1) used to determine the probability of a collision between the vehicle and an obstacle. When a negative determination is made, this control temporarily terminates; when a positive determination is made, this control proceeds to step S70.

[0061] In step S70, the CPU follows Figure 4 The subroutine shown calculates the correction amount ΔT2 of the second reference value TTC2.

[0062] In step S80, the CPU updates the correction amount ΔT2 by overwriting the correction amount ΔT2 in the non-volatile memory. Furthermore, the correction amount ΔT2 stored in the non-volatile memory can be 0 when the vehicle leaves the parking space. Also, the CPU updates the ratio Rm by overwriting the ratio Rp of deceleration Gb to pedaling force Fbp in the non-volatile memory.

[0063] In step S100, the CPU determines whether the alarm and automatic braking termination conditions are met. If a negative determination is made, the control proceeds to step S140; if a positive determination is made, it proceeds to step S110.

[0064] Additionally, for example, if any one of E1 to E3 below is met, it can be determined that the alarm and automatic braking termination conditions are met.

[0065] E1: TTC becomes the end baseline value or higher.

[0066] E2: This vehicle has changed lanes.

[0067] E3: This vehicle has stopped.

[0068] In step S110, the CPU outputs a command signal to the instrument ECU 50 to end the display of the warning on the display 52 indicating that the vehicle may collide with the vehicle in front, and also ends the operation of the warning device 54. Furthermore, the CPU outputs a command signal to the brake ECU 30 to end the automatic braking based on the automatic braking device 36.

[0069] In step S120, the CPU outputs a command signal to the instrument ECU 50 to display a warning on the display 52 that the vehicle may collide with the vehicle in front, and activates the warning device 54 to issue a warning that the vehicle may collide with the vehicle in front.

[0070] In step S130, the CPU determines whether the collision prediction time TTC is below the second reference value TTC2, i.e., whether automatic braking based on the automatic braking device 36 is required. If a negative determination is made, the control temporarily terminates; if a positive determination is made, the control proceeds to step S140. The second reference value TTC2 is the sum of the standard value TTC2b stored in the ROM and the correction amount ΔT2 stored in the volatile memory (TTC2b + ΔT2), and is a positive value less than the first reference value TTC1. Furthermore, the standard value TTC2b can be variably set to large, medium, or small values ​​(positive constants) using the setting device included in the setting operator 16.

[0071] In step S140, the CPU calculates a target deceleration Gbt for the vehicle to prevent a collision with the obstacle based on the relative distance Lr between the vehicle 102 and the obstacle and the relative speed Vr of the vehicle relative to the obstacle. Furthermore, the CPU executes automatic braking based on the automatic braking device 36 by outputting a command signal to the braking ECU 30 to decelerate the vehicle at the target deceleration Gbt, thereby making the vehicle's deceleration the target deceleration Gbt.

[0072] <The determination and control of the necessity of updating the correction amount ΔT2 ( Figure 3 >

[0073] Next, refer to Figure 3 The flowchart shown illustrates the determination and control of the necessity of updating the correction amount ΔT2 performed in step S60 above.

[0074] In step S61, the CPU determines whether there are more than n data points for pedal force Fbp and deceleration Gb within the past m minutes. Furthermore, m and n are pre-set positive fixed integers. If a negative determination is made, this control temporarily terminates; if a positive determination is made, this control proceeds to step S62.

[0075] In step S62, the CPU calculates the ratio R of deceleration Gb to pedaling force Fbp based on the data from the past m minutes, and calculates Rp of the ratio of deceleration Gb to pedaling force Fbp as their average value.

[0076] In step S63, the CPU reads the ratio Rm of the deceleration Gb to the pedaling force Fbp stored in the non-volatile memory.

[0077] In step S64, the CPU calculates the difference ΔRm (=Rp-Rm) between the ratio Rp and the ratio Rm, and determines whether the absolute value of the difference ΔRm is greater than or equal to the reference value ΔRc (a positive constant). If a negative determination is made, the control temporarily terminates; if a positive determination is made, the control proceeds to step S70.

[0078] < Operational control of correction amount ΔT2 ( Figure 4 >

[0079] Next, refer to Figure 4 The flowchart shown illustrates the operation control of the correction amount ΔT2 performed in step S70 above.

[0080] In step S71, the CPU determines whether the difference ΔRm between ratio Rp and ratio Rm is negative. If a negative determination is made, the control proceeds to step S73; if a positive determination is made, the control proceeds to step S72.

[0081] In step S72, the CPU calculates the correction amount ΔT2 based on the difference ΔRm, such that the larger the absolute value of the difference ΔRm, the larger the correction amount ΔT2 of the second reference value TTC2 becomes as a positive value. Therefore, the larger the absolute value of the correction amount ΔT2, the larger the second reference value TTC2, and the earlier the affirmative determination in step S130 is made, thus the start of automatic braking is brought forward.

[0082] In step S73, the CPU calculates the correction amount ΔT2 based on the difference ΔRm, such that the larger the difference ΔRm, the smaller the negative value of the correction amount ΔT2 becomes (the larger the absolute value becomes). Therefore, the larger the correction amount ΔT2, the smaller the second reference value TTC2, and the delay in the affirmative determination in step S130, thus delaying the start of automatic braking.

[0083] [Second Implementation]

[0084] <Driving control ( Figure 5 and Figure 6 >

[0085] In the second embodiment, the ROM of the driver assistance ECU 10 stores a standard value Rs (a positive constant) of the ratio R of deceleration Gb to pedal force Fbp. Furthermore, the standard value Rs is the ratio R of deceleration Gb to pedal force Fbp calculated in advance when the vehicle 102 is traveling on a road with a standard coefficient of friction and braking is applied to decelerate the vehicle.

[0086] Next, refer to Figure 5 and Figure 6 The flowchart shown illustrates the driving control in the second embodiment. Based on Figure 5 and Figure 6 The driving control shown in the flowchart is repeatedly executed by the CPU of the driving assistance ECU10 at predetermined intervals when the driving assistance switch is turned on.

[0087] As from Figure 5 and Figure 2A comparison shows that when step S50 is completed, step S90 is executed to replace steps S60 to S80 in the first embodiment, and the other steps are executed in the same manner as in the first embodiment. Step S90 is performed according to... Figure 6 The flowchart shown is used to execute the procedure.

[0088] < Operational control of correction amount ΔT2 ( Figure 6 >

[0089] Next, refer to Figure 6 The flowchart shown illustrates the calculation control of the correction amount ΔT2 performed in step S90 above. For example, from... Figure 6 and Figure 3 A comparison shows that steps S91 and S92 are performed in the same manner as steps S61 and S62 in the first embodiment.

[0090] In step S93, the CPU reads the standard value Rs of the ratio R of deceleration Gb to pedaling force Fbp stored in ROM.

[0091] In step S94, the CPU calculates the difference ΔRs between the ratio Rp and the ratio Rs (=Rp-Rs). Furthermore, the CPU bases its calculations on the difference ΔRs from... Figure 6 The correction amount ΔT2 is calculated in the mapping diagram shown in step S94. When the difference ΔRs is negative, it is calculated as follows: the larger the absolute value of the difference ΔRm, the larger the correction amount ΔT2 becomes as a positive value. Therefore, the larger the absolute value of the correction amount ΔT2, the larger the second reference value TTC2, and the earlier the affirmative determination in step S130, thus the earlier the start of automatic braking.

[0092] In contrast, when the difference ΔRs is positive, the correction amount ΔT2 is calculated as follows: the larger the difference ΔRm, the smaller the correction amount ΔT2 becomes as a negative value (the larger the absolute value becomes). Therefore, the larger the correction amount ΔT2, the smaller the second reference value TTC2, the delayed affirmative determination in step S130, and thus the delayed start of automatic braking.

[0093] As can be seen from the above description, the driving control device according to the present invention, when automatic braking is not performed, calculates the ratio (Rp) of the vehicle's deceleration to the amount of braking operation by the driver when the driver performs the braking operation (S60). Furthermore, a reference value is variably set based on this ratio, so that the smaller the ratio, the larger the reference value (TTC2) (S70, S80, S90). The larger the reference value, the earlier the determination is made that the time to collision (TTC) before the vehicle collides with the object subject to automatic braking is below the reference value (TTC2).

[0094] Therefore, the smaller the ratio (Rp) of the vehicle's deceleration to the driver's braking input, the larger the reference value (TTC2) can be, and the determination that the collision time is below the reference value can be made earlier. As a result, automatic braking can be initiated earlier, and the deceleration time of the vehicle based on automatic braking can be extended. Therefore, compared with the previous situation where the reference value was not set according to the ratio, the risk of the vehicle colliding with the object being automatically braked can be effectively reduced.

[0095] In particular, according to the first and second embodiments, for braking performed by the driver within a predetermined time period up to the present, data on the amount of braking operation by the driver and the deceleration of the vehicle are obtained (S61, S91). Furthermore, by calculating the average of the ratio of the vehicle's deceleration to the amount of braking operation by the driver for each data point, the ratio of the vehicle's deceleration to the amount of braking operation when the driver performs the braking operation is calculated (S62, S92).

[0096] Therefore, it is possible to prevent the following situation: obtaining data on the amount of braking by the driver and the deceleration of the vehicle up to a predetermined time ago, and calculating the ratio of the vehicle's deceleration to the amount of braking by the driver based on data including this old data.

[0097] In particular, according to the first embodiment, the control unit (driving assistance ECU 10) includes a storage device (non-volatile memory) for storing ratio (Rm). Furthermore, when a new ratio (Rp) is calculated, a reference value (TTC2) is increased or decreased based on the difference (ΔRm) between the new ratio and the ratio (Rm) stored in the storage device, and thereafter the new ratio is stored in the storage device in an overwrite manner. Therefore, by increasing or decreasing the reference value based on the difference between the new ratio and the ratio stored in the storage device, the reference value can be variably set according to the ratio.

[0098] Furthermore, according to the first embodiment, when the new ratio (Rp) is less than the ratio (Rm) stored in the storage device, the reference value (TTC2) is increased based on the difference (S71, S72). Therefore, when a new ratio is obtained and the new ratio is less than the ratio stored in the storage device, the reference value can be increased based on the difference. Conversely, when the new ratio (Rp) is greater than the ratio (Rm) stored in the storage device, the reference value (TTC2) is decreased based on the difference (S71, S73). Therefore, when a new ratio is obtained and the new ratio is greater than the ratio stored in the storage device, the reference value can be decreased based on the difference.

[0099] Furthermore, according to the second embodiment, the control unit (driving assistance ECU 10) includes a storage device (ROM) that stores a standard value of the ratio pre-calculated for a road surface with a standard coefficient of friction. Moreover, when a new ratio is calculated, a reference value is variably set based on the difference between the new ratio and the standard value (S90). Therefore, by variably setting the reference value based on the difference between the new ratio and the standard value, the reference value can be variably set according to the ratio.

[0100] The specific embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. It is obvious to those skilled in the art that other various embodiments can be implemented within the scope of the present invention.

[0101] For example, in the first and second embodiments described above, calculations are performed to make the second reference value TTC2 of TTC larger as the ratio R of deceleration Gb to pedal force Fbp decreases, thereby enabling automatic braking to start earlier. However, the first reference value TTC1 of TTC is not variably set. Alternatively, calculations can be performed to make the first reference value TTC1 larger as the ratio R of deceleration Gb to pedal force Fbp decreases, which could also trigger an earlier alarm.

[0102] Furthermore, in the first and second embodiments described above, in step S64, it is determined whether the correction amount ΔT2 needs to be updated by judging whether the absolute value of the difference ΔRm between the ratio Rp and the ratio Rm is greater than or equal to the reference value ΔRc. However, the reference value for determining whether the difference ΔRm is a reference value can vary depending on whether the difference ΔRm is a negative or positive value.

[0103] Symbol Explanation

[0104] 10-Driver assistance ECU, 12-Camera sensor, 14-Radar sensor, 18-Beacon information acquisition device, 22-Drive device, 32-Braking device, 36-Automatic braking device, 100-Driving control device, 102-Vehicle.

Claims

1. A vehicle driving control device, characterized in that, include: The vehicle driving control device includes a detection device that detects an automatically braking object located in front of the vehicle in its direction of travel; and a control unit configured to calculate the time to collision before a collision occurs between the vehicle and the automatically braking object based on the relative relationship between the automatically braking object and the vehicle, and to execute automatic braking to prevent a collision between the vehicle and the automatically braking object when the time to collision is determined to be below a reference value. The control unit is configured to, when the automatic braking is not performed, calculate the ratio of the vehicle's deceleration to the amount of braking operation performed by the driver when the driver performs the braking operation, and variably set the reference value based on the ratio so that the smaller the ratio, the larger the reference value.

2. The vehicle driving control device according to claim 1, characterized in that, The control unit is configured to acquire data on the amount of braking performed by the driver within a predetermined time period up to the present, as well as the deceleration of the vehicle, and calculate the average value of the ratio of the vehicle's deceleration to the amount of braking performed by the driver for each data point.

3. The vehicle driving control device according to claim 1, characterized in that, The control unit includes a storage device for storing the ratio. The control unit is configured to, when a new ratio is determined, increase or decrease the reference value based on the difference between the new ratio and the ratio stored in the storage device, and then store the new ratio in the storage device in an overwrite manner.

4. The vehicle driving control device according to claim 3, characterized in that, The control unit is configured to increase the reference value based on the difference when the new ratio is less than the ratio stored in the storage device.

5. The vehicle driving control device according to claim 1, characterized in that, The control unit includes a storage device that stores a standard value of the ratio pre-calculated for a road surface with a standard coefficient of friction. The control unit is configured to variably set the reference value based on the difference between the new ratio and the standard value when a new ratio is calculated.

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