Driving assistance devices

Abstract

The present invention provides a driving assistance device that can reduce the possibility that a driver who is unaware of the deceleration of a vehicle will feel uncomfortable when notified of the deceleration. [Solution] A driving assistance device issues a deceleration notification to inform the driver that the vehicle has decelerated when the vehicle is automatically decelerated. The driving assistance device determines whether a suppression condition is met based on a deceleration index value that indicates the degree of deceleration of the vehicle and the vehicle's driving conditions. Meeting the suppression condition indicates that the driver is more likely to not notice the vehicle's deceleration than when the suppression condition is not met, and when the suppression condition is met, the deceleration notification is suppressed compared to when the suppression condition is not met.

Description

[Technical Field]

[0001] The present invention relates to a driving assistance device configured to issue a deceleration notification to inform a driver that the vehicle has decelerated when the vehicle is automatically decelerated. [Background technology]

[0002] Driving assistance devices that issue deceleration notifications have been known for some time. For example, a driving assistance device described in Patent Document 1 (hereinafter referred to as the "conventional device") automatically decelerates the vehicle when it detects an object that requires the vehicle to decelerate, and issues a deceleration notification by displaying a deceleration screen that notifies the driver of the object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-023731 Summary of the Invention

[0004] If a deceleration notification is issued when the driver is unaware of the deceleration of the vehicle, the driver may feel uncomfortable.

[0005] The present invention has been made to address the above-mentioned problems. That is, one of the objects of the present invention is to provide a driving assistance device that can reduce the possibility that a driver who is unaware of the deceleration of the vehicle will feel uncomfortable when receiving a deceleration notification.

[0006] The driving assistance device of the present invention (hereinafter referred to as "the device of the present invention") When the vehicle is automatically decelerated, a deceleration notification is performed to notify the driver that the vehicle has been decelerated (steps 340 and 345). The driving assistance device determining whether a suppression condition is satisfied based on a deceleration index value indicating the degree of deceleration of the vehicle and the driving conditions of the vehicle (steps 405 to 430); the satisfaction of the suppression condition indicates that the driver is more likely to not notice the deceleration of the vehicle than when the suppression condition is not satisfied; When the suppression condition is satisfied (step 335 "Yes"), the deceleration notification is suppressed (step 345) compared to when the suppression condition is not satisfied (step 335 "No"). It is configured as follows.

[0007] The satisfaction of the suppression condition indicates that the driver is more likely to be unaware of the vehicle's deceleration than when the suppression condition is not satisfied. Therefore, the device of the present invention suppresses the deceleration notification when the suppression condition is satisfied compared to when the suppression condition is not satisfied. This reduces the possibility that a driver who is unaware of the vehicle's deceleration will feel uncomfortable with the deceleration notification. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic system configuration diagram of a driving assistance device according to an embodiment of the present invention; [Figure 2] 2 is a flowchart of a start / end determination routine executed by a CPU of the ECU shown in FIG. 1. [Figure 3] 2 is a flowchart of a deceleration control routine executed by a CPU of the ECU shown in FIG. 1. [Figure 4] 2 is a flowchart of a suppression condition determination subroutine executed by a CPU of the ECU shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] A driving assistance device 10 according to an embodiment of the present invention (hereinafter also referred to as "the device 10") is applied to a vehicle VA and includes the components shown in FIG. 1. In this specification, "ECU 20" refers to an electronic control device including a microcomputer as its main component. The ECU 20 is also referred to as a control unit, a controller, and a computer. The microcomputer includes a CPU (processor), a ROM, a RAM, an interface (I / F), and the like. The functions realized by the ECU 20 may be realized by multiple ECUs.

[0010] The forward camera 22 acquires image data by capturing images of the scenery ahead of the vehicle VA. The millimeter-wave radar 24 receives millimeter waves transmitted ahead of the vehicle VA that are reflected by an object, and acquires radar data related to the object. The radar data includes the object's position with respect to the vehicle VA and the object's relative speed with respect to the vehicle VA. The ECU 20 acquires image data from the forward camera 22 and radar data from the millimeter-wave radar 24. The ECU 20 recognizes objects ahead of the vehicle VA based on the image data and radar data.

[0011] The acceleration sensor 26 measures the acceleration Gx in the longitudinal direction of the vehicle VA and the acceleration Gy in the vertical direction of the vehicle VA. When the vehicle VA accelerates forward, the acceleration Gx is a positive value, and when the vehicle VA accelerates backward (i.e., when the vehicle VA decelerates), the acceleration Gx is a negative value. Deceleration is a negative acceleration Gx. The vehicle speed sensor 28 measures the vehicle speed Vs, which represents the speed of the vehicle VA. The gradient sensor 30 measures the gradient θ of the road surface on which the vehicle VA is traveling. If the road surface is an upslope, the gradient θ is a positive value, and if the road surface is a downslope, the gradient θ is a negative value. The acceleration operation amount sensor 32 measures the acceleration operation amount AP, which represents the amount of operation of the accelerator pedal 32a. The accelerator pedal 32a is sometimes referred to as the "acceleration operator." The deceleration operation amount sensor 34 measures the deceleration operation amount BP, which represents the amount of operation of the brake pedal 34a. The ECU 20 acquires the measured values ​​of these sensors 26 to 34. The brake pedal 34a may also be referred to as a "deceleration operator."

[0012] The regenerative braking device 40 includes a generator motor 42, an inverter 44, and a battery 46. The generator motor 42 is, for example, an AC synchronous motor. The output shaft of the generator motor 42 is connected to the drive wheels (48) so that the power generated at the output shaft is transmitted to the drive wheels. The battery 46 is an electricity storage device that can be charged and discharged. When the accelerator pedal 32a is depressed, the regenerative braking device 40 functions as a "drive device that drives the drive wheels."

[0013] The inverter 44 is electrically connected to the battery 46. When the generator motor 42 operates as a generator (when the regenerative braking device 40 functions as a braking device), the generator motor 42 converts the rotational (kinetic) energy of the drive wheels into electrical energy (AC power). The inverter 44 converts the AC power supplied from the generator motor 42 into DC power and supplies the DC power to the battery 46. In this way, the battery 46 is charged. When the generator motor 42 operates as a generator, a regenerative braking force is generated in the drive wheels. On the other hand, when the generator motor 42 operates as a motor (when the regenerative braking device 40 functions as a drive device), the inverter 44 converts the DC power supplied from the battery 46 into AC power and supplies it to the generator motor 21. This drives the generator motor 21, and driving force is imparted to the drive wheels.

[0014] As described above, the generator motor 21 is a braking actuator that applies regenerative braking force to the drive wheels, and a driving actuator that applies driving force to the drive wheels.

[0015] The friction braking device 50 includes a hydraulic circuit 52 that functions as a brake actuator. The hydraulic circuit 31 supplies hydraulic pressure to wheel cylinders (not shown) provided for each wheel, thereby actuating the wheel cylinders. When the wheel cylinders are actuated, brake pads (not shown) are pressed against the brake discs of each wheel 48, generating a friction braking force on each wheel 48.

[0016] The display 60 is disposed in the interior of the vehicle VA. The display 60 displays a deceleration screen, which will be described later.

[0017] (Overview of operation) When a start condition described below is satisfied, the ECU 20 of the present device 10 determines whether or not it is necessary to decelerate the vehicle VA based on the relationship between the vehicle VA and, for example, a preceding vehicle (object to be decelerated). When it is necessary to decelerate the vehicle VA, the ECU 20 automatically decelerates the vehicle VA. When the vehicle VA is automatically decelerated, the ECU 20 determines whether or not a suppression condition is satisfied. Satisfaction of the suppression condition indicates a higher possibility that the driver will not notice the deceleration of the vehicle VA than when the suppression condition is not satisfied.

[0018] If the suppression condition is not satisfied, the ECU 20 issues a deceleration notification by displaying a deceleration screen on the display 60. The deceleration screen is a screen for informing the driver that the vehicle VA has decelerated and the cause of the deceleration of the vehicle VA (object of deceleration). On the other hand, if the suppression condition is not satisfied, the ECU 20 suppresses the deceleration notification. For example, the ECU 20 suppresses the deceleration notification by not displaying the deceleration screen.

[0019] As a result, when there is a high possibility that the driver will not notice the deceleration of the vehicle VA, the deceleration notification is suppressed. Therefore, according to the present invention, it is possible to reduce the possibility that a driver who does not notice the deceleration of the vehicle VA will feel uncomfortable when notified of the deceleration.

[0020] When automatically decelerating the vehicle VA, the ECU 20 acquires a target deceleration Gtgt that prevents the inter-vehicle distance D between the preceding vehicle and the vehicle VA from becoming equal to or smaller than a set distance Dset, and acquires a required braking force Ftgt that causes the current acceleration Gx to coincide with the target deceleration Gtgt. The ECU 20 controls at least the regenerative braking device 40 so that the braking force F generated in the vehicle VA coincides with the required braking force Ftgt.

[0021] The maximum regenerative braking force Fkmax, which represents the maximum regenerative braking force that the regenerative braking device 40 can generate, is determined based on, for example, the charging rate of the battery 46. When the required braking force Ftgt is equal to or less than the maximum regenerative braking force Fkmax, the ECU 20 controls the regenerative braking device 40 so that the braking force F matches the required braking force Ftgt. When the required braking force Ftgt is greater than the maximum regenerative braking force Fkmax, the ECU 20 causes the regenerative braking device 40 to generate the maximum regenerative braking force Fkmax, and causes the friction braking device 50 to generate a braking force of a value obtained by subtracting the maximum regenerative braking force Fkmax from the required braking force Ftgt.

[0022] When the vehicle VA is decelerated solely by regenerative braking force, the deceleration starts seamlessly and the change in deceleration rate is also smooth. For this reason, when the vehicle VA is decelerated solely by regenerative braking force, the driver is unlikely to notice the automatic deceleration of the vehicle VA.

[0023] The ECU 20 determines that the suppression condition is met when the first condition is met and at least one of the second to fifth conditions is met.

[0024] First condition: No frictional braking force is generated (that is, the required braking force Ftgt is equal to or less than the maximum regenerative braking force Fkmax). Second condition: The gradient θ of the road surface on which the vehicle VA is traveling is equal to or greater than a threshold gradient θth. Note that the threshold gradient θth is set to a value greater than "0." When the vehicle VA is climbing an uphill slope, the driver is unlikely to notice the "automatic deceleration of the vehicle VA." Third condition: An evaluation value E, which indicates the possibility that the driver will not notice deceleration due to the influence of vertical vibrations of the vehicle VA, is equal to or less than a threshold value Eth. This evaluation value E is acquired based on the acceleration Gx and the acceleration Gy. When this evaluation value E is equal to or less than the threshold value Eth, it indicates that the influence of vertical vibrations of the vehicle VA is so great that the driver will not notice deceleration. Details of the evaluation value E will be described later. Fourth condition: A subtraction value ΔAP obtained by subtracting the start operation amount APs from the current acceleration operation amount AP is equal to or greater than a threshold change amount ΔAPth1. The start operation amount APs is the acceleration operation amount AP at the time the start condition is met. If the fourth condition is met, it is highly likely that the driver is operating the accelerator pedal 32a with the intention of accelerating. If a deceleration notification is issued when the driver intends to accelerate, the driver is likely to feel uncomfortable with the deceleration notification. Furthermore, even if deceleration control is being executed, if the accelerator pedal 32a is operated, a driving force corresponding to the acceleration operation amount AP is applied to the wheels 48, making it highly likely that the driver will not notice the deceleration of the vehicle VA. For this reason, in this embodiment, if the fourth condition is met, it is determined that the suppression condition is met. Fifth condition: The deceleration operation amount BP is equal to or greater than a threshold deceleration operation amount BPth1. When the fifth condition is met, the vehicle VA is decelerated by the driver's brake pedal 34a, so the driver is unlikely to notice the "automatic deceleration of the vehicle VA."

[0025] (Specific operation) The CPU of the ECU 20 executes the routine shown in the flowcharts of FIGS. 2 and 3 every time a predetermined time elapses.

[0026] <Start / End Judgment Routine> When an appropriate time arrives, the CPU starts the process from step 200 in Fig. 2, and the process proceeds to step 205. In step 205, the CPU determines whether the execution flag Xexe is "0".

[0027] The execution flag Xexe is set to "1" when deceleration control is executed, and is set to "0" when deceleration control is not executed. The execution flag Xexe is set to "0" in the initialization routine. The CPU executes the initialization routine when the ignition key switch (not shown) of the vehicle VA is changed from the OFF position to the ON position.

[0028] If the execution flag Xexe is "0", the CPU determines "Yes" in step 205, and the process proceeds to step 210. In step 210, the CPU determines whether the vehicle speed Vs is equal to or greater than the threshold vehicle speed Vsth.

[0029] If the vehicle speed Vs is equal to or greater than the threshold vehicle speed Vsth, the CPU determines "Yes" in step 210, and the process proceeds to step 215. In step 215, the CPU determines whether the acceleration operation amount AP is equal to or less than the threshold operation amount APsth.

[0030] If the acceleration operation amount AP is equal to or less than the threshold operation amount APsth, the CPU determines "Yes" in step 215, and the process proceeds to step 220. In step 220, the CPU determines whether or not there is an object to be decelerated within a predetermined distance ahead of the vehicle VA. The object to be decelerated is an object that requires the vehicle VA to decelerate. For example, the object to be decelerated is a preceding vehicle, a traffic light, a stop line, a curved road, etc.

[0031] If an object to be decelerated exists, the start condition is met. In this case, the CPU determines "Yes" in step 220, and the process proceeds to step 225. In step 225, the CPU sets the execution flag Xexe to "1" and stores the current acceleration operation amount AP as the start operation amount APs. Thereafter, the process proceeds to step 295, and the CPU temporarily ends this routine.

[0032] If the vehicle speed Vs is less than the threshold vehicle speed Vsth ("No" in step 210), if the acceleration operation amount AP is greater than the threshold operation amount APsth ("No" in step 215), or if there is no object to be decelerated ("No" in step 220), the start condition is not met. In this case, the process proceeds to step 295, and the CPU temporarily ends this routine.

[0033] If the execution flag Xexe is "1" when the process proceeds to step 205, the CPU determines "No" in step 205, and the process proceeds to step 230. In step 230, the CPU determines whether or not the termination condition is met. Specifically, the CPU determines that the termination condition is met when at least one of the first to third termination conditions is met.

[0034] First termination condition: The subtraction value ΔAP used in the fourth condition is equal to or greater than the threshold change amount ΔAPth2. The threshold change amount ΔAPth2 is set to a value greater than the threshold change amount ΔAPth1. If the driver depresses the accelerator pedal 32a by the threshold change amount ΔAPth2 or more from the initial operation amount APs, the driver clearly intends to accelerate, so the deceleration control is terminated. Second end condition: The deceleration operation amount BP is equal to or greater than the threshold deceleration operation amount BPth2. The threshold deceleration operation amount BPth2 is set to a value greater than the threshold deceleration operation amount BPth1. If the deceleration operation amount BP is equal to or greater than the threshold deceleration operation amount BPth2, the driver clearly intends to decelerate, so the deceleration control is terminated. Third termination condition: The vehicle VA stops.

[0035] If the termination condition is met, the CPU determines "Yes" in step 230, and the process proceeds to step 235. In step 235, the CPU sets the execution flag Xexe to "0." Thereafter, the process proceeds to step 295, and the CPU temporarily ends this routine.

[0036] If the termination condition is not met, the CPU determines "No" in step 230, the process proceeds to step 295, and the CPU temporarily terminates this routine.

[0037] <Deceleration control routine> When an appropriate time arrives, the CPU starts the process from step 300 in Fig. 3, and the process proceeds to step 305. In step 305, the CPU determines whether the execution flag Xexe is "1".

[0038] If the execution flag Xexe is "1", the CPU determines "Yes" in step 305 and executes steps 310 to 320. Step 310: The CPU obtains a target deceleration Gtgt from the relationship between the vehicle VA and the object to be decelerated. The target deceleration Gtgt is a negative acceleration Gx. For example, when the object to be decelerated is a preceding vehicle, the CPU acquires a target deceleration Gtgt that prevents the inter-vehicle distance D from becoming equal to or smaller than a preset distance Dset. In other words, when the inter-vehicle distance D is equal to or smaller than the set distance Dset, a value greater than "0" is acquired as the target deceleration Gtgt, and when the inter-vehicle distance D is longer than the set distance Dset, "0" is acquired as the target deceleration Gtgt (the vehicle VA is not decelerated).

[0039] Step 315: The CPU acquires a required braking force Ftgt for matching the acceleration Gx of the vehicle VA with the target deceleration Gtgt. If the subtraction value ΔG obtained by subtracting the current acceleration Gx from the target deceleration Gtgt is a negative value, the required braking force Ftgt becomes greater than "0." The larger the subtraction value ΔG, the larger the required braking force Ftgt. Note that when the subtraction value ΔG is acquired, the target deceleration Gtgt is used as a negative value. When the target deceleration Gtgt is "0", the vehicle VA is not decelerated, and therefore the required braking force Ftgt is "0". Step 320: The CPU determines whether the required braking force Ftgt is greater than "0".

[0040] If the required braking force Ftgt is greater than "0", the CPU determines "Yes" in step 320 and executes steps 325 and 335. Step 325: The CPU generates a required braking force Ftgt. As described above, when the required braking force Ftgt is equal to or less than the maximum regenerative braking force Fkmax, the CPU causes the regenerative braking device 40 to generate the required braking force Ftgt. On the other hand, when the required braking force Ftgt is greater than the maximum regenerative braking force Fkmax, the CPU causes the regenerative braking device 40 to generate the maximum regenerative braking force, and causes the friction braking device 50 to generate "a braking force of a value obtained by subtracting the maximum regenerative braking force Fkmax from the required braking force Ftgt."

[0041] Step 330: The CPU executes a suppression condition determination subroutine to determine whether the suppression condition is met. The suppression condition determination subroutine will be described in detail later. Step 335: The CPU determines whether the suppression condition is met.

[0042] If the suppression condition is not satisfied, the CPU determines "No" in step 335, and the process proceeds to step 340. In step 340, the CPU notifies the driver of deceleration by displaying a deceleration screen on the display 60. Thereafter, the process proceeds to step 395, and the CPU temporarily ends this routine.

[0043] If the suppression condition is met, the CPU determines "Yes" in step 335, and the process proceeds to step 345. In step 345, the CPU suppresses the deceleration notification. Specifically, the CPU does not display the deceleration screen. Thereafter, the process proceeds to step 395, and the CPU temporarily ends this routine.

[0044] If the execution flag Xexe is "0" ("No" in step 305) and the required braking force Ftgt is "0" ("No" in step 320), the process proceeds to step 395, and the CPU temporarily ends this routine.

[0045] <Suppression condition determination subroutine> When the process proceeds to step 330, the CPU starts the process from step 400 shown in Fig. 4, and then proceeds to step 405. In step 405, the CPU determines whether or not a frictional braking force has been generated in step 325 shown in Fig. 3 (that is, determines whether or not the required braking force Ftgt is greater than the maximum regenerative braking force Fkmax).

[0046] If a frictional braking force is generated (if the required braking force Ftgt is greater than the maximum regenerative braking force Fkmax), the CPU determines that the first condition is not met. In this case, the CPU determines "Yes" in step 405 shown in FIG. 4, and the process proceeds to step 410. In step 410, the CPU determines that the suppression condition is not met. The process proceeds to step 495, and the CPU temporarily ends this routine. Thereafter, the process proceeds to step 335 shown in FIG. 3.

[0047] If no frictional braking force is generated (if the required braking force Ftgt is equal to or less than the maximum regenerative braking force Fkmax), the CPU determines that the first condition is met. In this case, the CPU determines "No" in step 405 shown in Fig. 4, and the process proceeds to step 415. In step 415, the CPU determines whether the gradient θ is equal to or greater than the threshold gradient θth.

[0048] If the gradient θ is less than the threshold gradient θth, the CPU determines “No” in step 415 and executes steps 415 and 420 .

[0049] Step 415: The CPU acquires the evaluation value E.

[0050] First, the CPU performs weighting filter processing on the waveforms of acceleration Gx(t) and acceleration Gy(t) in the evaluation interval Tn (tn to tn+1) from "a point in time a predetermined time before the present time" to the present time, to obtain acceleration Gxf(t) and acceleration Gyf(t).

[0051] For example, a weighting filter specified in ISO 2631-1 is used for the acceleration Gx, and a weighting filter specified in ISO 2631-4 is used for the acceleration Gy. These weighting filters specify a weighting coefficient for each frequency component. The weighting coefficient for frequency components that passengers perceive as uncomfortable is set high, and the weighting coefficient for frequency components that passengers do not perceive as uncomfortable is set low.

[0052] Next, the CPU obtains a ride comfort evaluation value Ey(t) that evaluates the ride comfort in the vertical direction of the vehicle VA using equation (1).

[0053]

number

[0054] Furthermore, the CPU acquires a ride comfort evaluation value Exy(t) that comprehensively evaluates the ride comfort in the longitudinal direction and the vertical direction of the vehicle VA. First, the CPU acquires the magnitude of the resultant vector Gxyf(t) of the acceleration Gxf(t) and the acceleration Gyf(t) using equation (2).

[0055]

number

[0056] Then, the CPU obtains the ride comfort evaluation value Exy(t) using equation (3).

[0057]

number

[0058] The CPU obtains the ratio (Exy(t) / Ey(t)) of the ride comfort evaluation value Exy(t) to the ride comfort evaluation value Ey(t) as the evaluation value E. When this evaluation value E is greater than "1", it indicates that the ride comfort is deteriorating due to the longitudinal acceleration Gx(t). In other words, when the evaluation value E is greater than "1", it indicates that the driver is more likely to notice deceleration.

[0059] Step 420: The CPU determines whether the evaluation value E is equal to or less than a threshold value Eth. The threshold value Eth is set to a value greater than 1. For example, the threshold value Eth is set to 1.2. If the evaluation value E is equal to or less than the threshold value Eth, the discomfort caused by the deceleration of the vehicle VA is likely to be overshadowed by the discomfort caused by the vertical vibration of the vehicle VA, and the driver will not likely notice the deceleration of the vehicle VA.

[0060] If the evaluation value E is greater than the threshold value Eth, there is a high possibility that the driver will notice the deceleration. In this case, the CPU determines "No" in step 420, and the process proceeds to step 425. In step 425, the CPU determines whether the subtraction value ΔAP is equal to or greater than the threshold change amount ΔAPth1.

[0061] If the subtraction value ΔAP is less than the threshold change amount ΔAPth1, the CPU determines "No" in step 425, and the process proceeds to step 430. In step 430, it is determined whether the deceleration operation amount BP is equal to or greater than the threshold deceleration operation amount BPth1.

[0062] If the deceleration operation amount BP is less than the threshold deceleration operation amount BPth1, the CPU determines "No" in step 430, and the process proceeds to step 410. As a result, the CPU determines that the suppression condition is not met.

[0063] If the gradient θ is equal to or greater than the threshold gradient θth (step 415 "Yes"), if the evaluation value E is equal to or less than the threshold Eth (step 420 "Yes"), if the subtraction value ΔAP is equal to or greater than the threshold change amount ΔAPth1 (step 425 "Yes"), or if the deceleration operation amount BP is equal to or greater than the threshold deceleration operation amount BPth1 (step 430 "Yes"), the process proceeds to step 435. In step 435, the CPU determines that the suppression condition is met. The process proceeds to step 495, where the CPU temporarily ends this routine. Thereafter, the process proceeds to step 335 shown in FIG. 3.

[0064] According to this embodiment, when the suppression condition is met, the deceleration notification is suppressed compared to when the suppression condition is not met, thereby reducing the possibility that a driver who is unaware of the deceleration of the vehicle VA will feel uncomfortable with the deceleration notification.

[0065] (First Modification) In the above embodiment, when the CPU suppresses the deceleration notification, the CPU does not display the deceleration screen. Suppression of the deceleration notification is not limited to this. For example, when the suppression condition is met, the CPU may display the "display element indicating that the vehicle VA has decelerated" and the "display element indicating the cause of the deceleration of the vehicle VA" smaller than when the suppression condition is not met. Furthermore, when the suppression condition is met, the CPU may display these display elements in a lighter color than when the suppression condition is not met.

[0066] Furthermore, when the suppression condition is met, the CPU may display the deceleration screen later than when the suppression condition is not met. A modified example of delaying the display of the deceleration screen will be described below. In this modification, the CPU executes steps 310 to 335 shown in FIG. 3 after executing step 225 shown in FIG. 2. That is, when the start condition is satisfied, it is determined whether the suppression condition is satisfied. If the suppression condition is not satisfied, the CPU immediately displays the deceleration screen. On the other hand, if the suppression condition is satisfied, the CPU displays the deceleration screen when a predetermined time has elapsed since it was determined that the suppression condition was satisfied. The deceleration screen is displayed until the end condition is satisfied. In this modification, the deceleration control routine shown in FIG. 3 does not determine whether the suppression condition is satisfied or notify the deceleration.

[0067] Furthermore, the deceleration notification is not limited to the display of the deceleration screen. For example, the CPU may notify the driver of the deceleration by outputting a voice message from a speaker (not shown) to inform the driver that the vehicle VA has automatically decelerated.

[0068] (Second Modification) The evaluation value E may be a ride comfort evaluation value Ey(t) in the vertical direction of the vehicle VA. The worse the ride comfort in the vertical direction, the more likely the driver will not notice the deceleration of the vehicle VA. In this modification, if the evaluation value E (i.e., the ride comfort evaluation value Ey(t)) is equal to or greater than "a threshold value Eth' set to a value different from the threshold value Eth," the CPU determines that the suppression condition is met.

[0069] Therefore, the evaluation value E can be expressed as a value acquired based on at least the ride comfort evaluation value Ey(t). Furthermore, if the relationship between the evaluation value E and the threshold value satisfies a predetermined condition indicating that the deceleration of the vehicle VA is likely to go unnoticed, the CPU determines that the suppression condition is met.

[0070] (Third Modification) The object for decelerating is not limited to the preceding vehicle, but may be any of a traffic light, a stop line, and a curved road. When the deceleration object is either a traffic light or a stop line, the CPU obtains a target deceleration Gtgt that will cause the vehicle VA to stop before the traffic light or the stop line. When the deceleration object is a curved road, the CPU obtains a target deceleration Gtgt that makes the vehicle speed Vs coincide with "a vehicle speed appropriate for the vehicle VA to travel on the curved road."

[0071] (Fourth Modification) In the first condition, whether or not a frictional braking force is generated is determined based on the required braking force Ftgt, but this is not limiting. As described above, the required braking force Ftgt is obtained based on the subtraction value ΔG, and therefore whether or not a frictional braking force is generated may be determined based on the subtraction value ΔG. The required braking force Ftgt and the subtraction value ΔG are values ​​that represent the degree of deceleration in deceleration control, and are therefore sometimes referred to as deceleration index values. Whether or not the first condition is satisfied is determined based on the deceleration index value, and whether or not the second to fourth conditions are satisfied is determined based on the traveling conditions of the vehicle VA.

[0072] The present device is applicable to vehicles such as hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles, and electric vehicles. Furthermore, the present device is also applicable to autonomous vehicles. [Explanation of symbols]

[0073] 10...driving assistance device, 20...ECU, 40...regenerative braking device, 50...friction braking device, 60...display.

Claims

1. A driving assistance device configured to perform a deceleration notification to notify a driver that a vehicle has been decelerated when the vehicle is automatically decelerated, The driving assistance device determining whether a suppression condition is satisfied based on a deceleration index value indicating a degree of deceleration of the vehicle and a driving situation of the vehicle, where satisfaction of the suppression condition indicates that the driver is more likely to not notice the deceleration of the vehicle than when the suppression condition is not satisfied; When the suppression condition is satisfied, the deceleration notification is suppressed compared to when the suppression condition is not satisfied. A driving assistance device configured as follows.

2. The driving assistance device according to claim 1, The driving assistance device a friction braking device that generates a friction braking force on a wheel of the vehicle; a regenerative braking device that generates a regenerative braking force on the wheels; Equipped with When the vehicle is automatically decelerated, a required braking force to be used as the deceleration index value is obtained; When the required braking force is equal to or less than a maximum regenerative braking force that represents a maximum regenerative braking force that can be generated by the regenerative braking device, the required braking force is generated by the regenerative braking device; When the required braking force is greater than the maximum regenerative braking force, the regenerative braking device generates the maximum regenerative braking force, and the friction braking device generates the friction braking force obtained by subtracting the maximum regenerative braking force from the required braking force, determining whether the frictional braking force is not generated based on the required braking force; It is configured as follows: The suppression condition includes at least a condition that the friction braking force is not generated. Driving assistance device.

3. The driving assistance device according to claim 1 or 2, The driving assistance device a condition that the gradient of the road surface on which the vehicle is traveling is an uphill gradient for the vehicle, and the magnitude of the gradient is equal to or greater than a threshold gradient; a condition that a relationship between a threshold value and an evaluation value obtained based on a ride comfort evaluation value indicating the ride comfort in the vertical direction, which is obtained based on the acceleration of the vehicle in the vertical direction, satisfies a predetermined condition; If at least one of the above conditions is met, it is determined that the suppression condition is met. A driving assistance device configured as follows.

4. The driving assistance device according to claim 3, The driving assistance device When a predetermined start condition is satisfied, a deceleration control is started to automatically decelerate the vehicle when it is necessary to decelerate the vehicle; A condition that the operation amount of the acceleration operator of the vehicle has increased by a threshold change amount or more from the operation amount when the start condition is satisfied; and a condition that the operation amount of a deceleration operation element of the vehicle is equal to or greater than a threshold operation amount; If at least one of the above conditions is met, it is determined that the suppression condition is met. A driving assistance device configured as follows.

Images