Vehicle driving control system

Abstract

The present invention provides an improved driving control system that can effectively decelerate a vehicle and effectively reduce the risk of collision, even when there is a risk of collision in situations where the coefficient of friction of the road surface is low. [Solution] S30 calculates the time limit TTC until the vehicle collides with the object to be automatically braked in front of the vehicle, based on the relative relationship between the vehicle and the object to be automatically braked in front of the vehicle detected by the object information acquisition device. S130 determines that the time limit is less than or equal to the reference value TTC2, and S140 executes automatic braking to prevent the vehicle from colliding with the object to be automatically braked. The driver support ECU also calculates the ratio of the vehicle's deceleration to the amount of braking performed by the driver when braking is performed by the driver in a situation where automatic braking is not being performed. S70 and S80 variably set the reference value according to the ratio such that the reference value increases as the ratio decreases.

Description

Technical Field

[0001] The present invention relates to a driving control device for vehicles such as automobiles, and more particularly to a driving control device that reduces the risk of a vehicle colliding with an obstacle or the like.

Background Art

[0002] As one type of driving control device, there is known a brake control device that, when a vehicle collision is detected, continuously generates a certain braking force by automatic brake control until the control end time to decelerate the vehicle.

[0003] For example, in Patent Document 1 below, the actual deceleration speed of a vehicle when automatic brake control is being executed is detected, and when the actual deceleration speed is low, the control end time is set longer compared to when the actual deceleration speed is high. A brake control device is described.

[0004] According to this type of driving control device, for example, when the friction coefficient of the road surface is low and the actual deceleration speed is low, the control end time is set longer and the automatic brake control is continued for a longer time. Therefore, compared to the case where the control end time is not set long, the vehicle speed can be lowered and the damage reduction effect can be enhanced.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] 〔Problems to be Solved by the Invention〕 The conventional driving control device described in Patent Document 1 above can reduce the damage after a collision when a vehicle collides in a situation where the friction coefficient of the road surface is low. However, when there is a risk of a vehicle colliding in a situation where the friction coefficient of the road surface is low, the vehicle cannot be effectively decelerated to effectively reduce the risk of the vehicle colliding.

[0007] The present invention provides an improved driving control device that can effectively decelerate a vehicle and effectively reduce the risk of collision, even when there is a risk of collision in situations where the coefficient of friction of the road surface is low.

[0008] [Means for solving the problem and the effects of the invention] According to the present invention, a vehicle driving control device (100) is provided, which includes a detection device (target information acquisition device 18) for detecting an object to be automatically braked that is located in front of the vehicle (102) in the direction of travel, and a control unit (driving support ECU 10) configured to calculate the time to collision (TTC) between the vehicle and the object to be automatically braked based on the relative relationship between the object to be automatically braked and the vehicle (S30), and if it is determined that the time to be automatically braked is less than or equal to a reference value (TTC2) (S130), it performs automatic braking to prevent the vehicle from colliding with the object to be automatically braked (S140).

[0009] The control unit (driving support ECU 10) is configured to determine the ratio (Rp) of the vehicle's deceleration to the amount of braking performed by the driver when automatic braking is not being performed (S60), and to variably set the reference value according to the ratio such that the reference value increases as the ratio decreases (S70, S80, S90).

[0010] When automatic braking is not activated and the driver applies the brakes, the ratio of the vehicle's deceleration to the amount of braking force applied by the driver corresponds to the ratio of the vehicle's actual braking force to the amount of braking force applied by the driver, and this ratio decreases as the coefficient of friction of the road surface decreases. The lower the ratio of the vehicle's deceleration to the amount of braking force applied by the driver, the longer it takes for the vehicle to decelerate, and the longer the braking distance.

[0011] According to the above-described driving control system, when the driver performs a braking operation in a situation where automatic braking is not being performed, the ratio of the vehicle's deceleration to the amount of braking performed by the driver is determined, and the reference value is variably set according to the ratio, with the reference value increasing as the ratio decreases. The larger the reference value, the earlier it is determined that the margin of time before the vehicle collides with an object subject to automatic braking is below the reference value.

[0012] Therefore, the smaller the ratio of the vehicle's deceleration to the driver's braking input, the larger the reference value can be set, and the sooner it can be determined that the margin of safety is below the reference value. Consequently, automatic braking can be initiated earlier, and the deceleration time of the vehicle due to automatic braking can be extended. Compared to conventional cases where the reference value is not variably set according to the ratio, the risk of the vehicle colliding with the object being automatically braked can be effectively reduced.

[0013] Furthermore, the target braking force or target deceleration in the automatic braking control is not increased. Therefore, it is possible to prevent the vehicle's braking force from becoming excessive due to an increase in the target braking force or target deceleration, which could cause the wheels to lock and actually reduce the vehicle's deceleration.

[0014] [Aspects of the Invention] In one embodiment of the present invention, the control unit (driving support ECU 10) is configured to acquire data on the amount of braking performed by the driver and the deceleration of the vehicle for braking performed by the driver over a predetermined period of time up to the present (S61, S91), and to determine the ratio of the deceleration of the vehicle to the amount of braking performed by the driver by calculating the average value of the ratio of the deceleration of the vehicle to the amount of braking performed by the driver for each data (S62, S92).

[0015] According to the above configuration, data on the amount of braking performed by the driver and the degree of deceleration of the vehicle are acquired for braking performed by the driver over a predetermined period of time up to the present, with a minimum number of data points being met. Furthermore, by calculating the average value of the ratio of the degree of deceleration of the vehicle to the amount of braking performed by the driver for each data point, the ratio of the degree of deceleration of the vehicle to the amount of braking performed by the driver can be determined.

[0016] Therefore, it is possible to prevent the acquisition of data on the driver's braking amount and the vehicle's deceleration degree from prior to a predetermined time, and to prevent the calculation of the ratio of the vehicle's deceleration degree to the driver's braking amount based on data including this old data.

[0017] Furthermore, data on the braking force of drivers and the deceleration of the vehicle are acquired for a number of drivers greater than the standard, and the average value of the ratio of the vehicle's deceleration to the driver's braking force for each data point is calculated, thereby determining the ratio of the vehicle's deceleration to the driver's braking force. Therefore, compared to the case where the ratio of the vehicle's deceleration to the driver's braking force is determined based on data on the braking force of drivers and the vehicle's deceleration that is less than the standard, the ratio can be determined more accurately. In particular, the risk of the ratio becoming an inappropriate value and the standard value being set to an inappropriate value due to the ratio of the vehicle's deceleration to the driver's braking force being determined based on instantaneous and unique deceleration data can be reduced.

[0018] In another embodiment of the present invention, the control unit (driving support ECU 10) includes a memory device (non-volatile memory) for storing ratios, and when the control unit determines a new ratio, it increases or decreases a reference value based on the difference between the new ratio and the ratio stored in the memory device (S60, S70), and then overwrites the new ratio and stores it in the memory device (S80).

[0019] According to the above embodiment, when a new ratio is determined, the reference value is increased or decreased based on the difference between the new ratio and the ratio stored in the memory device, and then the new ratio is stored in the memory device by overwriting the existing value. Therefore, by increasing or decreasing the reference value based on the difference between the new ratio and the ratio stored in the memory device, the reference value can be set variably according to the ratio.

[0020] In another aspect of the present invention, when the new ratio is smaller than the ratio stored in the storage device, the control unit (driving support ECU 10) is configured to increase the reference value based on the difference (S71, S72).

[0021] According to the above aspect, when the new ratio is smaller than the ratio stored in the storage device, the reference value is increased based on the difference. Therefore, when the new ratio is obtained and the new ratio is smaller than the ratio stored in the storage device, the reference value can be increased based on the difference.

[0022] In another aspect of the present invention, the control unit (driving support ECU 10) includes a storage device (ROM) that stores a standard value of a ratio obtained in advance for a road surface with a standard coefficient of friction. When the control unit obtains a new ratio, it is configured to variably set the reference value based on the difference between the new ratio and the standard value (S90).

[0023] According to the above aspect, 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.

[0024] In the above description, for the purpose of assisting the understanding of the present invention, the names and / or symbols used in the embodiments corresponding to the configurations of the invention described below are attached in parentheses. However, each component of the present invention is not limited to the components of the embodiments corresponding to the names and / or symbols attached in parentheses. Other objects, other features, and accompanying advantages of the present invention will be easily understood from the description of the embodiments of the present invention described while referring to the following drawings.

Brief Description of Drawings

[0025] [Figure 1] It is a schematic configuration diagram showing an embodiment of a vehicle driving control device according to the present invention. [Figure 2]It is a flowchart corresponding to the driving control program in the first embodiment. [Figure 3] It is a flowchart showing the routine for determining whether to update the correction amount ΔT2 executed in step S60 of FIG. 2. [Figure 4] It is a flowchart showing the routine for arithmetic control of the correction amount ΔT2 executed in step S70 of FIG. 2. [Figure 5] It is a flowchart corresponding to the driving control program in the second embodiment. [Figure 6] It is a flowchart showing the routine for arithmetic control of the correction amount ΔT2 executed in step S90 of FIG. 5.

Mode for Carrying Out the Invention

[0026] The driving control device according to an embodiment of the present invention will be described in detail below with reference to the attached drawings.

[0027] As shown in FIG. 1, the driving control device 100 according to an embodiment of the present invention is applied to a vehicle 102 and includes a driving support ECU 10. The vehicle 102 is a vehicle capable of autonomous driving and includes a drive ECU 20, a brake ECU 30, and a meter ECU 50. An ECU means an electronic control unit (Electronic Control Unit) having a microcomputer as a main part. The vehicle 102 is referred to as the host vehicle 102 as necessary to distinguish it from other vehicles.

[0028] Each ECU's microcomputer includes a CPU, ROM, RAM, read / write non-volatile memory (N / M), and an interface (I / F). The CPU implements various functions by executing instructions (programs, routines) stored in ROM. Furthermore, these ECUs are interconnected via CAN (Controller Area Network) 104, enabling data exchange (communication). Therefore, detection values ​​from sensors (including switches) connected to a specific ECU are transmitted to other ECUs.

[0029] The driver assistance ECU 10 is a central control unit that performs driving control for driver assistance, such as driving control, following distance control, and lane keeping control. In this embodiment, the driver assistance ECU 10 works in cooperation with other ECUs to perform driving control for the vehicle 102, as will be described in detail later. In the driving control of this embodiment, if the driver assistance ECU 10 determines that there is a possibility of collision between the vehicle and an obstacle that is an object to be automatically braked and is located in front of the vehicle in the direction of travel, it issues a warning to alert the driver of this possibility. Furthermore, if the driver assistance ECU 10 determines that the possibility of collision between the obstacle and the vehicle has increased and there is a risk of collision, it performs automatic braking control to reduce that risk. Note that the obstacle is an object that, if it collides with the vehicle, will cause damage to the vehicle and / or the other party, such as a stationary vehicle, a slow-moving preceding vehicle, or a pedestrian crossing the road.

[0030] The driver assistance ECU 10 is connected to a camera sensor 12, a radar sensor 14, and a setting control unit 16. The camera sensor 12 and radar sensor 14 each include multiple camera devices and multiple radar devices, respectively. The camera sensor 12 and radar sensor 14 function as a target information acquisition device 18 that acquires target information around the vehicle 102.

[0031] Each camera device of the camera sensor 12, although not shown in the figure, includes a camera unit that photographs the area around the vehicle 102 and a recognition unit that analyzes the image data obtained from the camera unit to recognize road markings, other vehicles, and other objects. The recognition unit supplies information about the recognized objects to the driver assistance ECU 10 at predetermined intervals.

[0032] Each radar device of the radar sensor 14 is equipped with a radar transceiver and a signal processing unit (not shown). The radar transceiver emits 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 emission range. The signal processing unit supplies information representing 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 to the vehicle 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. LiDAR (Light Detection And Ranging) may be used instead of or in addition to the radar sensor 14.

[0033] The setting control unit 16 is located in a position accessible to the driver, similar to a steering wheel (not shown in Figure 1), and is operated by the driver. Although not shown in Figure 1, the setting control unit 16 includes a driver assistance switch. The driver assistance ECU 10 performs driving control when the driver assistance switch is turned on, as will be described in detail later.

[0034] 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. Normally, the drive ECU 20 controls the drive unit 22 so that the driving force generated by the drive unit 22 changes in accordance with the driver's driving operation, and when it receives a command signal from the driver assistance ECU 10, it controls the drive unit 22 based on the command signal.

[0035] The braking ECU 30 is connected to a braking device 32 that decelerates the vehicle 102 by applying braking force to the wheels 34. Normally, the braking ECU 30 controls the braking device 32 so that the braking force generated by the braking device 32 changes in accordance with the braking operation by the driver. When it receives a command signal from the driver assistance ECU 10, it performs automatic braking by controlling the braking device 32 based on the command signal.

[0036] Therefore, the braking ECU 30 and the braking device 32 work together to function as an automatic braking device 36. When braking force is applied to the wheels due to driving control or other means, brake lights (not shown in Figure 1) are illuminated.

[0037] The meter ECU 50 is connected to a touch-panel display 52 that displays the control status by the driver assistance ECU 10 and a warning device 54 that issues warnings. The display 52 may be, for example, a multi-information display that displays meters and various other information, or it may be the display of the navigation device 80 described later. As described later, when the display 52 receives a signal from the driver assistance ECU 10, it displays the status of the driving control.

[0038] The warning device 54 is activated when it is determined that there is a risk of the vehicle 102 colliding with an object to be controlled, such as an obstacle, and issues a warning that there is a risk of the vehicle 102 colliding with the object to be controlled. The warning device 54 may be any of the following: a warning device that emits a visual warning, such as a warning lamp; a warning device that emits an auditory warning, such as a warning buzzer; or a warning device that emits a tactile warning, such as seat vibration; or any combination thereof.

[0039] The driving operation sensor 60 and the vehicle condition sensor 70 are also connected to CAN 104. Information detected by the driving operation sensor 60 and the vehicle condition sensor 70 (referred to as sensor information) is transmitted to CAN 104. The sensor information transmitted to CAN 104 can be used as appropriate by each ECU. Note that the sensor information may be information from a sensor connected to a specific ECU and transmitted to CAN 104 from that specific ECU.

[0040] The driving operation sensor 60 includes a drive operation amount sensor for detecting the amount of operation of the accelerator pedal, a braking operation amount sensor for detecting master cylinder pressure or braking force Fbp applied to the brake pedal, and a brake switch for detecting whether or not the brake pedal is operated. The driving operation sensor 60 also includes a steering angle sensor for detecting the steering angle, a steering torque sensor for detecting the steering torque, and the like.

[0041] The vehicle state sensor 70 includes a vehicle speed sensor for detecting the vehicle speed V of the vehicle 102, a longitudinal acceleration sensor for detecting the longitudinal acceleration Gx of the vehicle, a lateral acceleration sensor for detecting the lateral acceleration of the vehicle, and a yaw rate sensor for detecting the yaw rate of the vehicle.

[0042] In the first embodiment, the ROM of the driver assistance ECU 10 stores a driving control program corresponding to the flowcharts shown in Figures 2 to 4. In the second embodiment, the ROM of the driver assistance ECU 10 stores a driving control program corresponding to the flowcharts shown in Figures 5 and 6.

[0043] [First Embodiment] <Driving control (Figures 2 to 4)> Next, the driving control in the first embodiment will be described with reference to the flowcharts shown in Figures 2 to 4. The driving control according to the flowcharts shown in Figures 2 to 4 is repeatedly executed at predetermined intervals by the CPU of the driver assistance ECU 10 when the driver assistance switch is ON.

[0044] First, in step S10, the CPU determines, for example, whether there is an obstacle such as a stationary vehicle in front of the vehicle 102 using the camera sensor 12 or the radar sensor 14. If a negative determination is made, step S10 is repeated, and if a positive determination is made, the control proceeds to step S20.

[0045] In step S20, the CPU determines whether or not it is performing 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.

[0046] In step S30, the CPU acquires information on the relative distance Lr between the vehicle and the obstacle, detected by, for example, the camera sensor 12 or the radar sensor 14, and the relative speed Vr of the vehicle relative to the obstacle. Furthermore, based on the relative distance Lr and the relative speed Vr, the CPU determines whether there is a possibility of the vehicle colliding with the obstacle and whether it is necessary to issue a warning indicating the possibility of collision. If an affirmative determination is made, the control proceeds to step S120; if a negative determination is made, the control proceeds to step S40. If a negative determination is made and a warning has already been issued, the warning issuance is terminated.

[0047] The collision prediction time TTC, which is the predicted time until the vehicle collides with an obstacle, is calculated as the value obtained by dividing the relative distance Lr by the relative speed Vr. When TTC is less than or equal to the first reference value TTC1 (a positive constant), it is determined that the vehicle may collide with an obstacle. The collision prediction time TTC is an indicator of the likelihood of the vehicle colliding with the preceding vehicle; the smaller the value, the higher the likelihood (risk) of the vehicle colliding with the preceding vehicle. The first reference value TTC1 may be variably set to large, medium, or small values ​​(each a positive constant) by a setting device included in the setting control device 16.

[0048] In step S40, the CPU determines whether or not the driver is performing a 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.

[0049] In step S50, the CPU acquires information on the braking force Fbp applied to the brake pedal detected by the braking operation amount detection sensor and the vehicle's deceleration Gb, which is the longitudinal acceleration Gx of the vehicle 102 detected by the longitudinal acceleration sensor. The deceleration Gb is positive when the acceleration Gx is negative, and its magnitude is the same as the absolute value of the acceleration Gx.

[0050] In step S60, the CPU determines, according to the subroutine shown in Figure 3, whether or not it is necessary to update the correction amount ΔT2 of the second reference value TTC2 (a positive value smaller than TTC1) of TTC used to determine the possibility of the vehicle colliding with an obstacle. If a negative determination is made, this control is terminated; if a positive determination is made, this control proceeds to step S70.

[0051] In step S70, the CPU calculates the correction amount ΔT2 for the second reference value TTC2 of TTC, according to the subroutine shown in Figure 4.

[0052] In step S80, the CPU updates the correction amount ΔT2 by overwriting and storing it in non-volatile memory. Note that the correction amount ΔT2 stored in non-volatile memory when the vehicle leaves the depot may be 0. The CPU also updates the ratio Rm by overwriting and storing the ratio Rp of deceleration Gb to pedal force Fbp as the ratio Rm in non-volatile memory.

[0053] In step S100, the CPU determines whether the alarm and automatic braking termination conditions are met. If a negative determination is made, the control determination proceeds to step S140; if a positive determination is made, the determination proceeds to step S110.

[0054] Furthermore, for example, if any of the following E1 to E3 conditions are met, it may be determined that the alarm and automatic braking termination conditions have been met. E1:TTC has exceeded the termination threshold. E2: The vehicle changed lanes. E3: Your vehicle has stopped.

[0055] In step S110, the CPU outputs a command signal to the meter ECU 50, thereby ending the display on the display unit 52 that indicates the vehicle may collide with the preceding vehicle, and also ending the operation of the warning device 54. The CPU also outputs a command signal to the brake ECU 30, thereby ending the automatic braking by the automatic braking device 36.

[0056] In step S120, the CPU outputs a command signal to the meter ECU 50, which displays a warning on the display unit 52 indicating that the vehicle may collide with the preceding vehicle, and also activates the warning device 54 to issue a warning that the vehicle may collide with the preceding vehicle.

[0057] In step S130, the CPU determines whether the collision prediction time TTC is less than or equal to the second reference value TTC2, that is, whether or not automatic braking by the automatic braking device 36 is necessary. If a negative determination is made, this control is terminated; if a positive determination is made, this control proceeds to step S140. The second reference value TTC2 is the sum of the standard value TTC2b stored in ROM and the correction amount ΔT2 stored in volatile memory, TTC2b+ΔT2, and is a positive value smaller than the first reference value TTC1. The standard value TTC2b may be variably set to a large, medium, or small value (each a positive constant) by a setting device included in the setting control device 16.

[0058] In step S140, the CPU calculates a target deceleration Gbt for the vehicle to prevent it from colliding with the obstacle, based on the relative distance Lr between the vehicle 102 and the obstacle and the relative speed Vr of the vehicle with respect to the obstacle. Furthermore, the CPU outputs a command signal to the braking ECU 30 to decelerate the vehicle at the target deceleration Gbt, thereby executing automatic braking by the automatic braking device 36 so that the vehicle's deceleration becomes the target deceleration Gbt.

[0059] <Determination control for whether or not to update the correction amount ΔT2 (Figure 3)> Next, referring to the flowchart shown in Figure 3, we will explain the control for determining whether or not to update the correction amount ΔT2, which is performed in step S60 described above.

[0060] In step S61, the CPU determines whether there are n or more data points for pedal force Fbp and deceleration Gb within the m minutes up to the present. m and n are predetermined positive integers. If a negative determination is made, this control process ends; if a positive determination is made, this control process proceeds to step S62.

[0061] In step S62, the CPU calculates the ratio R of deceleration Gb to pedaling force Fbp based on each data point for the m minutes up to the present, and calculates the ratio Rp of deceleration Gb to pedaling force Fbp as the average value of these values.

[0062] In step S63, the CPU reads out the ratio Rm of deceleration Gb to pedal force Fbp stored in non-volatile memory.

[0063] 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, this control is terminated; if a positive determination is made, this control proceeds to step S70.

[0064] <Calculation and control of the correction amount ΔT2 (Figure 4)> Next, with reference to the flowchart shown in Figure 4, the calculation control of the correction amount ΔT2 performed in step S70 described above will be explained.

[0065] In step S71, the CPU determines whether the difference ΔRm between the ratio Rp and the ratio Rm is a negative value. If a negative determination is made, the control proceeds to step S73; if a positive determination is made, the control proceeds to step S72.

[0066] 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 of TTC2 becomes. Therefore, the larger the absolute value of the correction amount ΔT2, the larger the second reference value TTC2 becomes, and the earlier the positive judgment in step S130, the earlier the start of automatic braking.

[0067] 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 correction amount ΔT2 becomes (the larger its absolute value). Therefore, the larger the correction amount ΔT2, the smaller the second reference value TTC2 becomes, and the later the affirmative judgment in step S130, the later the start of automatic braking.

[0068] [Second Embodiment] <Driving control (Figures 5 and 6)> 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. The standard value Rs is the ratio R of deceleration Gb to pedal force Fbp that has been determined in advance for the case where the vehicle 102 is traveling on a road where the friction coefficient of the road surface is a standard value, and braking is performed and the vehicle is decelerated.

[0069] Next, the driving control in the second embodiment will be described with reference to the flowcharts shown in Figures 5 and 6. The driving control according to the flowcharts shown in Figures 5 and 6 is repeatedly executed at predetermined intervals by the CPU of the driver assistance ECU 10 when the driver assistance switch is ON.

[0070] As can be seen from comparing Figure 5 with Figure 2, once step S50 is completed, step S90 is executed instead of steps S60 to S80 in the first embodiment, and the other steps are executed in the same way as in the first embodiment. Step S90 is executed according to the flowchart shown in Figure 6.

[0071] <Calculation and control of the correction amount ΔT2 (Figure 6)> Next, with reference to the flowchart shown in Figure 6, the calculation control of the correction amount ΔT2 performed in step S90 described above will be explained. As can be seen from the comparison between Figure 6 and Figure 3, steps SS91 and S92 are performed in the same way as steps S61 and S62 in the first embodiment.

[0072] In step S93, the CPU reads the standard value Rs of the ratio R of deceleration Gb to pedal force Fbp stored in ROM.

[0073] In step S94, the CPU calculates the difference ΔRs (=Rp-Rs) between the ratio Rp and the ratio Rs. Furthermore, based on the difference ΔRs, the CPU calculates the correction amount ΔT2 from the map shown in step S94 of Figure 6. When the difference ΔRs is a negative value, the correction amount ΔT2 is calculated to increase as the absolute value of the difference ΔRm increases, resulting in a positive value. Therefore, the larger the absolute value of the correction amount ΔT2, the larger the second reference value TTC2 becomes, and the earlier the positive judgment in step S130, thus allowing automatic braking to start earlier.

[0074] In contrast, when the difference ΔRs is a positive value, the correction amount ΔT2 is calculated such that the larger the difference ΔRm, the smaller the correction amount ΔT2 becomes (the larger its absolute value). Therefore, the larger the correction amount ΔT2, the smaller the second reference value TTC2 becomes, and the later the affirmative judgment in step S130, the later the start of automatic braking.

[0075] As can be seen from the above explanation, the driving control device of the present invention determines the ratio (Rp) of the vehicle's deceleration to the amount of braking performed by the driver when braking is performed by the driver in a situation where automatic braking is not being performed (S60). Furthermore, the reference value is variably set according to the ratio such that the smaller the ratio, the larger the reference value (TTC2) becomes (S70, S80, S90). The larger the reference value, the earlier it is determined that the time to travel (TTC) before the vehicle collides with the object to be automatically braked is less than or equal to the reference value (TTC2).

[0076] Therefore, the smaller the ratio of the vehicle's deceleration to the driver's braking input (Rp), the larger the reference value (TTC2) can be set, allowing for an earlier determination that the margin of safety is below the reference value. Consequently, automatic braking can be initiated earlier, and the vehicle's deceleration time due to automatic braking can be extended. This effectively reduces the risk of the vehicle colliding with the object being automatically braked, compared to conventional cases where the reference value is not variably set according to the ratio.

[0077] In particular, according to the first and second embodiments, data on the amount of braking performed by the driver and the degree of deceleration of the vehicle are acquired for braking performed by the driver over a predetermined period of time up to the present (S61, S91). Furthermore, by calculating the average value of the ratio of the degree of deceleration of the vehicle to the amount of braking performed by the driver for each data set, the ratio of the degree of deceleration of the vehicle to the amount of braking performed by the driver is determined (S62, S92). (S60, S80).

[0078] Therefore, it is possible to prevent the acquisition of data on the driver's braking amount and the vehicle's deceleration degree from prior to a predetermined time, and to prevent the calculation of the ratio of the vehicle's deceleration degree to the driver's braking amount based on data including this old data.

[0079] In particular, according to the first embodiment, the control unit (driving support ECU 10) includes a memory device (non-volatile memory) that stores the ratio (Rm). Furthermore, when a new ratio (Rp) is determined, the reference value (TTC2) is increased or decreased based on the difference (ΔRm) between the new ratio and the ratio (Rm) stored in the memory device, and then the new ratio is stored in the memory device by overwriting the existing value. Therefore, by increasing or decreasing the reference value based on the difference between the new ratio and the ratio stored in the memory device, the reference value can be variably set according to the ratio.

[0080] Furthermore, according to the first embodiment, when the new ratio (Rp) is smaller than the ratio (Rm) stored in the memory device, the reference value (TTC2) is increased based on the difference (S71, S72). Therefore, when a new ratio is determined and the new ratio is smaller than the ratio stored in the memory device, the reference value can be increased based on the difference. Conversely, when the new ratio (Rp) is larger than the ratio (Rm) stored in the memory device, the reference value (TTC2) is decreased based on the difference (S71, S73). Therefore, when a new ratio is determined and the new ratio is larger than the ratio stored in the memory device, the reference value can be decreased based on the difference.

[0081] Furthermore, according to the second embodiment, the control unit (driving support ECU 10) includes a memory device (ROM) that stores standard values ​​of ratios predetermined for road surfaces with a standard coefficient of friction. Furthermore, when a new ratio is determined, the 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. It is possible.

[0082] Although the present invention has been described in detail above with respect to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to the embodiments described above, and that various other embodiments are possible within the scope of the present invention.

[0083] For example, in the first and second embodiments described above, the second reference value TTC2 of the TTC is calculated to be larger the smaller the ratio R of deceleration Gb to pedal force Fbp, thereby enabling early automatic braking, but the first reference value TTC1 of the TTC is not variably set. However, the first reference value TTC1 may also be calculated to be larger the smaller the ratio R of deceleration Gb to pedal force Fbp, thereby enabling early alarm activation.

[0084] Furthermore, in the first and second embodiments described above, in step S64, it is determined whether or not the correction amount ΔT2 needs to be updated by determining whether or not the absolute value of the difference ΔRm between ratio Rp and ratio Rm is greater than or equal to the reference value ΔRc. However, the reference value used in determining whether or not the magnitude of the difference ΔRm is the reference value may differ depending on whether the difference ΔRm is a negative or positive value. [Explanation of Symbols]

[0085] 10…Driver assistance ECU, 12…Camera sensor, 14…Radar sensor, 18…Target information acquisition device, 22…Drive system, 32…Braking system, 36…Automatic braking system, 100…Driving control device, 102…Vehicle

Claims

1. A vehicle driving control device includes: a detection device for detecting an object to be automatically braked located in front of the vehicle's direction of travel; and a control unit configured to calculate the margin of time before the vehicle collides with the object based on the relative relationship between the object and the vehicle, and to execute automatic braking to prevent the vehicle from colliding with the object if it determines that the margin of time is less than or equal to a reference value; The control unit is configured to determine the ratio of the vehicle's deceleration to the amount of braking performed by the driver when the driver performs a braking operation in a situation where automatic braking is not being performed, and to variably set the reference value according to the ratio such that the reference value increases as the ratio decreases.

2. A vehicle driving control device according to claim 1, wherein the control unit is configured to acquire data on the amount of braking performed by the driver and the deceleration of the vehicle, which are equal to or greater than a standard number, for braking performed by the driver over a preset time up to the present, and to calculate the ratio by calculating the average value of the ratio of the degree of deceleration of the vehicle to the amount of braking performed by the driver for each data set.

3. A vehicle driving control device according to claim 1, wherein the control unit includes a memory device for storing the ratio, and 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 memory device, and then overwrite and store the new ratio in the memory device.

4. A vehicle driving control device according to claim 3, wherein the control unit is configured to increase the reference value based on the difference when the new ratio is smaller than the ratio stored in the memory device.

5. A vehicle driving control device according to claim 1, wherein the control unit includes a memory device that stores a standard value of the ratio that has been determined in advance for a road surface with a standard coefficient of friction, and 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 determined.

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