Driving Support Devices

Abstract

To lessen possibility that causes anxiety to a driver when releasing application of brake force by means of automatic stop control.SOLUTION: A driving support ECU (10) executes automatic stop control which executes automatic brake as one of follow-up inter-vehicle distance control so as to stop an own vehicle in a prescribed position just before a follow-up object vehicle if the follow-up object vehicle stops. The driving support ECU performs stop time notification prompting a driver to perform brake operation by using a notification device (50) at time point when the own vehicle stops by means of the automatic stop control if the own vehicle travels on a flat road. The driving support ECU performs advance notification prompting the driver to perform brake operation by using the notification device (50) at time point earlier than the own vehicle stops by mean of the automatic stop control if the own vehicle travels on a steep slope road.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a driving assistance device capable of issuing a notification to prompt a driver of a vehicle to perform a brake operation. [Background technology]

[0002] Conventionally, there has been known a driving assistance device (hereinafter referred to as a "conventional device") that performs, as one of driving assistance controls, a following distance control that causes the host vehicle to travel so as to follow a vehicle to be followed (a preceding vehicle). When the host vehicle to be followed stops during execution of the following distance control, this conventional device applies a braking force to the host vehicle to decelerate the host vehicle and stop the host vehicle at a predetermined position behind the vehicle to be followed (see, for example, Patent Documents 1 and 2). Hereinafter, the control that automatically applies a braking force to the host vehicle to decelerate and stop the host vehicle may be referred to as an "automatic stop control."

[0003] Furthermore, there is also known a device that notifies the driver when driving assistance control is to be released, and allows the driver to smoothly start manual driving of the vehicle (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-147178 A [Patent Document 2] JP 2009-280014 A [Patent Document 3] JP 2017-043292 A Summary of the Invention

[0005] However, if a conventional device is configured to notify the driver to apply the brakes after the vehicle has stopped due to the execution of automatic stop control, and then terminate driving assistance control by releasing the application of braking force, the following problem occurs.

[0006] For example, when the vehicle is stopped on a flat road, even if the driver does not brake before the application of the braking force is released, the vehicle will only move forward gently due to creep force after the application of the braking force is released. However, when the vehicle is stopped on a steep slope (uphill or downhill), if the driver does not brake before the application of the braking force is released, the vehicle will suddenly move backward or forward due to gravity after the application of the braking force is released. The behavior of the vehicle on such a steep slope is significantly different from the behavior of the vehicle when the road on which the vehicle is traveling is flat, and may make the driver feel uneasy.

[0007] The present invention has been made to solve the above problems. That is, one of the objects of the present invention is to provide a driving assistance device that can reduce the possibility that the driver feels uneasy when the application of braking force by the automatic stop control is released.

[0008] The driving assistance device of the present invention (hereinafter, sometimes referred to as the "device of the present invention") is applied to a host vehicle, An information acquisition device (11-15, 40-42, 60) that acquires information representing a driving environment of the host vehicle and information regarding a driving state of the host vehicle; a braking device (30, 31) that operates to apply a braking force to the vehicle; An alarm device (50-52) for notifying the driver of the vehicle; a control unit (10) that performs driving assistance control including an automatic stop control that automatically applies the braking force to the host vehicle using the braking device based on the information acquired by the information acquisition device to decelerate and stop the host vehicle, and releases the application of the braking force to the host vehicle when a predetermined time has elapsed after the host vehicle has stopped, and causes the notification device to provide a notification related to the driving assistance control; Equipped with.

[0009] Furthermore, the control unit When the host vehicle is stopped by the automatic stop control (see steps 410 to 420), if it is determined based on the information acquired by the information acquisition device that the host vehicle is traveling on a flat road having a gradient smaller than a predetermined threshold gradient (step 425: No), the notification device is caused to issue a stop notification to prompt the driver to perform a brake operation to activate the braking device between the time when the host vehicle stops and the time when the application of the braking force to the host vehicle is released (step 415: No, steps 440 to 450), When the host vehicle is stopped by the automatic stop control (see steps 410 to 420), if it is determined based on the information acquired by the information acquisition device that the host vehicle is traveling on a steep slope having a gradient equal to or greater than the threshold gradient (step 425: Yes), the notification device is caused to issue an advance notification to prompt the driver to perform the brake operation when a predetermined advance notification condition that is established at a time prior to the time the host vehicle is stopped is established (step 430: Yes, step 435). It is structured as follows.

[0010] Therefore, when the vehicle is being stopped by automatic stop control, if the vehicle is traveling on a flat road, a stop-time warning is issued to encourage the driver to apply the brakes after the vehicle has stopped, and if the vehicle is traveling on a steep slope, an advance warning is issued to encourage the driver to apply the brakes before the vehicle stops (i.e., when the advance warning condition is met).

[0011] Therefore, compared to a conventional device that does not execute such advance warning, the device of the present invention can reduce the possibility that "the application of braking force (automatic braking) is released without the driver performing the brake operation, and the vehicle starts to move backward or forward suddenly because it is stopped on a steep slope." As a result, the possibility of making the driver feel uneasy can be reduced.

[0012] In one embodiment of the device of the present invention, The control unit The driving assistance control is configured to execute a following driving control in which the host vehicle drives so as to follow a following target vehicle that is a preceding vehicle driving immediately before the host vehicle (step 410); Furthermore, the control unit In a case where the automatic stop control is performed due to the stop of the vehicle to be followed during the execution of the following travel control, when the vehicle to be followed is stopped (step 420: Yes) and the speed of the host vehicle becomes equal to or lower than a threshold speed that is greater than zero (step 430: Yes), it is determined that the advance warning condition is satisfied. It is structured as follows.

[0013] According to this, when the host vehicle is about to stop due to the automatic stop control being executed as part of the following distance control, if the host vehicle is traveling on a steep slope, an advance warning is given before the host vehicle stops (i.e., when the speed of the host vehicle becomes equal to or lower than a threshold speed that is greater than zero). As a result, when the host vehicle stops due to the execution of the following distance control, the possibility of causing anxiety to the driver can be reduced.

[0014] In one embodiment of the device of the present invention, The control unit When the brake operation is detected during the execution of the advance warning (step 510: Yes, step 530: Yes), the advance warning by the warning device is terminated (step 560). When the vehicle stops without detecting the brake operation during the execution of the advance warning, the warning device is caused to perform the stop warning (step 510: Yes, step 530: No, step 415: No, step 440: Yes, step 450). It is structured as follows.

[0015] According to this, automatic stop control is executed as part of the following distance control, and an advance warning is given when the vehicle is about to stop, and if the driver does not brake even after the advance warning, a stop warning is given after the vehicle has stopped. Therefore, it is possible to increase the possibility that the driver will brake before the application of the braking force is released on a steep slope, thereby reducing the possibility of the driver feeling uneasy.

[0016] In the above description, in order to facilitate understanding of the present invention, the names and / or symbols used in the embodiments described below are enclosed in parentheses with respect to the configuration of the invention corresponding to the embodiments. However, each component of the present invention is not limited to the embodiments defined by the names and / or symbols. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic configuration diagram of a driving support device (the driving support device) according to an embodiment of the present invention. [Diagram 2] 4 is a time chart for explaining the operation of the implementation support device. [Diagram 3] 4 is a time chart for explaining the operation of the implementation support device. [Figure 4] 4 is a flowchart showing a routine executed by a CPU of the implementation support device. [Diagram 5] 4 is a flowchart showing a routine executed by a CPU of the implementation support device. [Figure 6] 11 is a diagram for explaining the operation of the implementation support device. FIG. [Figure 7] 11 is a diagram for explaining the operation of the implementation support device. FIG. [Figure 8] 11 is a diagram for explaining the operation of the implementation support device. FIG. [Figure 9] 11 is a diagram for explaining the operation of the implementation support device. FIG. [Figure 10] 11 is a diagram for explaining the operation of the implementation support device. FIG. [Figure 11]11 is a diagram for explaining the operation of the implementation support device. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] A driving assistance device according to an embodiment of the present invention (hereinafter, may be referred to as "the driving assistance device") is applied to and installed in a vehicle (hereinafter, may be referred to as "the own vehicle" to distinguish it from other vehicles), as shown in Fig. 1. The driving assistance device includes a driving assistance ECU 10, a driving force ECU 20, a brake ECU 30, a navigation ECU 40, and a notification ECU 50.

[0019] These ECUs are electronic control units that include a microcomputer as a main component, and are connected to each other via a controller area network (CAN) (not shown) so that they can transmit and receive information to each other. The microcomputer includes a CPU, ROM, RAM, non-volatile memory, an interface I / F, etc. The CPU is adapted to realize various functions by executing instructions (programs, routines) stored in the ROM. Some or all of these ECUs may be integrated into one ECU.

[0020] The driving assistance ECU 10 is connected to the sensors (including switches) listed below and receives detection signals or output signals from these sensors. Each sensor may be connected to an ECU other than the driving assistance ECU 10. In this case, the driving assistance ECU 10 receives a signal indicating a "value based on the detection signal of the sensor" from the ECU to which the sensor is connected via the CAN.

[0021] The accelerator pedal operation amount sensor 11 detects the operation amount (accelerator opening) of an accelerator pedal 11a of the host vehicle, and outputs a signal indicative of the accelerator pedal operation amount AP.

[0022] The brake pedal operation amount sensor 12 detects the operation amount of a brake pedal 12a of the host vehicle, and outputs a signal indicative of the brake pedal operation amount BP.

[0023] The stop lamp switch 13 outputs a stop lamp signal Stp that is at a low level when the brake pedal 12a is not depressed (not operated) and is at a high level when the brake pedal 12a is depressed (operated).

[0024] The vehicle speed sensor 14 detects the traveling speed (vehicle speed) of the host vehicle and outputs a signal indicating the vehicle speed SPDh. The host vehicle is provided with a wheel speed sensor (not shown) for each wheel, which outputs a wheel speed signal indicating the wheel speed of each wheel. The driving assistance ECU 10 may calculate an average value of the wheel speeds of each wheel and obtain the average value as the vehicle speed SPDh of the host vehicle.

[0025] The vehicle environment detection sensor (ambient sensor) 15 is a device that acquires information about the driving environment of the host vehicle, and includes a radar sensor 15a and a camera sensor 15b.

[0026] The radar sensor 15a is adapted to obtain information on the road ahead of the vehicle and on three-dimensional objects existing on the road by using radio waves in the millimeter wave band. The three-dimensional objects include, for example, moving objects such as pedestrians, bicycles, and automobiles, as well as fixed objects such as utility poles, trees, and guardrails. Hereinafter, these three-dimensional objects may be referred to as "objects". The radar sensor 15a is well known. The radar sensor 15a obtains target information including the following distance (vertical distance) Dfx(n), the relative speed Vfx(n), the lateral distance Dfy(n), and the relative lateral speed Vfy(n) for each detected target (n) at predetermined time intervals.

[0027] The inter-vehicle distance Dfx(n) is the distance between the host vehicle and a target (n) (eg, a preceding vehicle) along the central axis of the host vehicle. The relative speed Vfx(n) is the difference (=Vs-Vj) between the speed Vs of the target (n) and the speed Vj of the host vehicle. The speed Vs of the target (n) is the speed of the target (n) in the traveling direction of the host vehicle. When the target (n) is a vehicle to be followed, which will be described later, its speed Vs is expressed as vehicle speed SPDp. Also, as described above, the vehicle speed Vj of the host vehicle is expressed as vehicle speed SPDh. That is, when the target (n) is a vehicle to be followed, which will be described later, the following formula is established. Vfx(n) = SPDp - SPDh

[0028] The lateral distance Dfy(n) is the distance from the central axis of the host vehicle to the "center position of the target (n) (e.g., the center position of the preceding vehicle in terms of vehicle width)" in a direction perpendicular to the central axis of the host vehicle. The lateral distance Dfy(n) is also referred to as the "lateral position." The relative lateral velocity Vfy(n) is the velocity of the center position of the target (n) (for example, the widthwise center position of the preceding vehicle) in a direction perpendicular to the center axis of the host vehicle.

[0029] The camera sensor 15b includes a "stereo camera and an image processing unit," neither of which is shown. The stereo camera captures images of the scenery in the left and right areas in front of the vehicle to obtain a pair of image data for the left and right sides. The image processing unit acquires information such as the presence or absence of a target, the relative relationship between the vehicle and the target (target information), the illumination status of traffic lights, and road signs based on a pair of left and right image data captured by the stereo camera.

[0030] The driving assistance ECU 10 determines final target information by combining the target information obtained by the radar sensor 15a and the target information obtained by the camera sensor 15b. Furthermore, the driving assistance ECU 10 recognizes lane markers such as left and right white lines on the road (hereinafter simply referred to as "white lines") based on a pair of left and right image data (road image data) captured by the camera sensor 15b, and obtains the shape of the road (the curvature radius of the road) and the positional relationship between the road and the vehicle in the vehicle width direction, etc.

[0031] The operation switches 60 are switches for generating various signals (request signals, setting signals, etc.) for the ACC (one of the driving assistance controls) described later, and include a main switch 61, a cancel switch 62, a time interval setting switch 63, and an automatic start switch 64. These switches 61 to 64 are arranged in positions where they can be operated by the driver.

[0032] The driving force ECU 20 is connected to a driving force actuator 21. The driving force actuator 21 is an actuator for changing the operating state of the driving force source of the vehicle (in this case, an internal combustion engine). In this example, the internal combustion engine is a gasoline fuel injection, spark ignition, multi-cylinder engine, and is equipped with a throttle valve for adjusting the amount of intake air. The driving force actuator 21 includes at least a throttle valve actuator for changing the opening degree of the throttle valve.

[0033] The driving force ECU 20 can change the torque generated by the internal combustion engine by driving the driving force actuator 21. The torque generated by the internal combustion engine is transmitted to driving wheels (not shown) via a transmission (not shown). Therefore, the driving force ECU 20 can control the driving force of the host vehicle and change the acceleration state (acceleration) by controlling the driving force actuator 21. In other words, the driving force ECU 20, the driving force actuator 21, the driving force source, etc. constitute a drive device that applies driving force to the host vehicle.

[0034] The driving force source of the host vehicle may be an electric motor. In other words, the host vehicle may be an electric vehicle, in which case the driving force actuator 21 is an inverter capable of changing the torque of the electric motor. The driving force source of the host vehicle may be both an internal combustion engine and an electric motor. In other words, the host vehicle may be a hybrid vehicle, in which case the driving force actuator 21 includes an inverter capable of changing the torque of the electric motor and a throttle valve actuator of the internal combustion engine.

[0035] The brake ECU 30 is connected to the brake actuator 31. The brake actuator 31 is provided in a hydraulic circuit between a master cylinder (not shown) that pressurizes hydraulic oil by the depression force of the brake pedal 12a, and friction brake mechanisms provided on the left, right, front and rear wheels. The brake actuator 31 adjusts the hydraulic pressure supplied to the friction brake mechanism in response to an instruction from the brake ECU 30, and presses a brake pad (not shown) against a brake disc (not shown) with the hydraulic pressure to generate a friction braking force. Therefore, the brake ECU 30 can control the braking force of the host vehicle by controlling the brake actuator 31. Furthermore, the driver of the host vehicle can change the braking force applied to the host vehicle via the brake ECU 30 and the brake actuator 31 by operating the brake pedal 12a. In this way, the brake ECU 30, the brake actuator 31, the friction brake mechanism, etc. configure a braking device that applies a braking force to the host vehicle.

[0036] The navigation ECU 40 is connected to a GPS receiver 41 that receives a GPS signal for detecting the position of the vehicle, a map database 42 that stores map information and the like, and a touch panel display 43 that is a human-machine interface. The navigation ECU 40 identifies the current position (present position) Pnow of the vehicle based on the GPS signal, and performs various calculation processes based on the position Pnow of the vehicle and the map information stored in the map database 42, and provides route guidance using the display 43.

[0037] The map information stored in the map database 42 includes road information. The road information includes parameters indicating the shape of the road at each position (for example, the curvature of the road) and the road gradient (inclination angle) Inc. Note that the gradient Inc is defined so that in the traveling direction of the vehicle on the road (in Japan, the forward direction of the vehicle in the lane to the left of the center line), if the road is an uphill road, the angle is positive, and if the road is a downhill road, the angle is negative. The magnitude of the gradient Inc (|Inc|) is expressed as abs(Inc).

[0038] The notification ECU 50 is connected to a display 51 and a speaker 52. In response to an instruction from the driving assistance ECU 10, the notification ECU 50 can display a predetermined display (for example, a brake operation request mark and a message, which will be described later, etc.) on the display 51 and generate a voice message, a warning sound, etc. from the speaker 52. The speaker 52 may be a buzzer device that can generate a predetermined sound.

[0039] (Overview of ACC) The driving assistance ECU 10 is capable of executing ACC (adaptive cruise control) as one of driving assistance controls. The ACC itself is well known (see, for example, the above-mentioned Patent Document 1, the above-mentioned Patent Document 2, Japanese Patent Application Publication No. 2014-148293, Japanese Patent Application Publication No. 2006-315491, Japanese Patent No. 4172434, and Japanese Patent No. 4929777, etc.). However, the driving assistance ECU 10 can execute ACC even when the vehicle speed SPDh of the host vehicle is low.

[0040] ACC includes adaptive cruise control and constant speed control. However, in this example, ACC mainly refers to adaptive cruise control. Adaptive cruise control is a control that makes the vehicle follow the preceding vehicle (i.e., the vehicle to be followed) traveling just before the vehicle while maintaining the distance between the vehicle and the preceding vehicle at a predetermined target distance without requiring the driver to operate the accelerator pedal 11a and the brake pedal 12a.

[0041] When ACC is started (for example, when the main switch 61 is changed from an off state to an on state), the driving assistance ECU 10 determines whether or not a vehicle to be followed is present based on the target information acquired by the vehicle environment detection sensor 15. The vehicle to be followed is a vehicle that travels ahead of (immediately before) the host vehicle and that the host vehicle should follow. For example, the driving assistance ECU 10 determines whether or not the relative position of the target (n) identified from the lateral distance Dfy(n) and longitudinal distance Dfx(n) of the detected target (n) is present within a predetermined area (i.e., a vehicle to be followed area) in the traveling direction of the host vehicle that is determined in advance.

[0042] When a target object (n) exists within the target vehicle area for a predetermined period of time or more, the driving assistance ECU 10 selects the target object (n) as a target vehicle (a) to be followed, and executes a following vehicle distance control for the target vehicle (a).

[0043] The driving assistance ECU 10 calculates the target acceleration Gtgt according to the following formula (1). In formula (1), Vfx(a) is the relative speed of the vehicle (a) to be followed, ka1, k1, and k2 are predetermined positive gains (coefficients), and ΔD1 is the inter-vehicle deviation obtained by subtracting the "target inter-vehicle distance Dtgt" from the "longitudinal distance (inter-vehicle distance) Dfx(a) of the vehicle (a) to be followed." The target inter-vehicle distance Dtgt is calculated by multiplying the target inter-vehicle time Ttgt set using the inter-vehicle time setting switch 63 by the vehicle speed SPDh of the host vehicle (i.e., Dtgt=Ttgt·SPDh). However, when the vehicle speed SPDh of the host vehicle is equal to or lower than a predetermined vehicle speed (low vehicle speed) threshold SPDLth, the target inter-vehicle distance Dtgt is set to a predetermined constant distance Dp. As a result, when the vehicle to be followed (a) stops, the host vehicle is stopped at a position a certain distance Dp (or a distance close to the certain distance Dp) in front of the vehicle to be followed (a). Gtgt=ka1·(k1·ΔD1+k2·Vfx(a)) …(1)

[0044] The driving assistance ECU 10 controls the driving force actuator 21 using the driving force ECU 20 to control the driving force of the vehicle so that the acceleration of the vehicle matches the target acceleration Gtgt, and, if necessary, controls the brake actuator 31 using the brake ECU 30 to control the braking force of the vehicle.

[0045] As described above, when the following target vehicle (a) stops during execution of the following distance control, the driving assistance ECU 10 applies a braking force to the host vehicle to decelerate the host vehicle and automatically stops the host vehicle at a position a predetermined distance away from the rear end of the following target vehicle (a). This control is also called automatic stop control. In addition, after the driving assistance ECU 10 stops the host vehicle in response to the following target vehicle (a) stopping, if the following target vehicle (a) starts before the predetermined waiting time Tsth has elapsed, the driving assistance ECU 10 automatically starts the host vehicle if the automatic start switch 64 is in an on state and the brake pedal 12a is not operated. This control is also called automatic start control. In this case, the ACC is continued.

[0046] When the vehicle to be followed (a) starts moving before a predetermined waiting time Tsth has elapsed after the vehicle to be followed (a) stops, if the automatic start switch 64 is in the OFF state or the brake pedal 12a is operated by that time, the driving assistance ECU 10 does not automatically start the vehicle. However, the driving assistance ECU 10 automatically starts the vehicle when a resume switch (not shown) is operated. In this case, the ACC is resumed.

[0047] If the vehicle to be followed (a) does not start moving until a predetermined waiting time Tsth has elapsed after the vehicle to be followed (a) stops as a result of the vehicle to be followed (a) stopping, the driving assistance ECU 10 cancels the automatic application of braking force to the vehicle to be followed (releases the automatic brake) and ends ACC regardless of the state of the automatic start switch 64.

[0048] When the driving assistance ECU 10 determines that there is no vehicle to be followed after the ACC is started, the driving assistance ECU 10 executes constant speed traveling control. That is, the driving assistance ECU 10 drives the host vehicle so that the traveling speed of the host vehicle matches the target speed (set speed Vset) without the driver's operation of the accelerator pedal 11a and the brake pedal 12a.

[0049] (Overview of operation) When executing the above-mentioned automatic stop control to stop the host vehicle, the driving assistance ECU 10 performs the following notification control depending on whether the road on which the host vehicle is traveling is flat or not. A flat road is a road whose gradient (inclination angle) magnitude abs(Inc) is less than a positive predetermined threshold gradient Ith.

[0050] 1. Flat road When the host vehicle is traveling on a flat road by the following vehicle distance control and the following vehicle stops, the automatic stop control is activated and a braking force is automatically applied to the host vehicle. As a result, the vehicle speed SDPh of the host vehicle gradually decreases during the period from time t1 to time t2 in FIG. 2, and reaches "0" at time t2. That is, the host vehicle stops at time t2. At this time t2, the driving assistance ECU 10 displays "notification to prompt the driver to brake" shown in block B1 in FIG. 2 on the display 51 and generates a first buzzer sound (warning sound) for a certain period of time from the speaker 52. The display and generation of the first buzzer sound at the time when the host vehicle stops may be referred to as "stop brake operation request notification" or "stop time notification". The driving assistance ECU 10 may start the stop time notification from a time that is delayed by a predetermined time Tw (for example, 0.2 seconds) from the time when the host vehicle stops by the automatic stop control (time t2). In this case, the predetermined time Tw is set to a time shorter than a waiting time Tsth, which will be described later.

[0051] During the period from time t2 to time t3 when a predetermined waiting time Tsth (for example, 2 seconds) has elapsed, the driving support ECU 10 continues to apply the braking force (automatic braking). Therefore, the vehicle speed SDPh of the vehicle is maintained at "0". When time t3 arrives, the driving support ECU 10 releases the application of the braking force (automatic braking). At this time t3, the driving support ECU 10 displays "a notice to prompt the driver to apply the brakes" shown in block B2 of FIG. 2 on the display 51 for a certain period of time, and generates a second buzzer sound from the speaker 52 for a certain period of time. The display performed at the time of releasing the automatic braking and the generation of the second buzzer sound may be referred to as "a brake operation request notice when releasing the automatic braking". In this case, the display on the display 51 due to the brake operation request notice when stopped continues, so the display on the display 51 does not change. The first buzzer sound (the buzzer sound when the vehicle is stopped) and the second buzzer sound (the buzzer sound when the brake is released) may be different or may be the same.

[0052] If the driver does not operate the brake pedal 12a during this period (the period from time t1 to time t2), only a creep force acts on the host vehicle from time t3 onwards, and the vehicle speed SPDh of the host vehicle gradually increases because the road is flat.

[0053] 2. Uphill road (steep gradient) When the host vehicle is traveling on a steep uphill road under the following vehicle distance control and the following vehicle stops, the automatic stop control is activated and braking force is automatically applied to the host vehicle. As a result, the vehicle speed SDPh of the host vehicle gradually decreases during the period from time t11 to time t12 in FIG. 3, and reaches a positive predetermined vehicle speed threshold value SPDth at time t12. At this point in time, the advance warning condition is satisfied. At this time t12, the driving assistance ECU 10 displays on the display 51 a "notification urging the driver to brake due to a steep slope" shown in block B3 in FIG. 3, and generates a third buzzer sound (advance warning buzzer sound) from the speaker 52 for a certain period of time. The display performed at the time when the vehicle speed SPDh decreases to the vehicle speed threshold value SPDth and the generation of the third buzzer sound are sometimes referred to as "a notification of a brake operation request before stopping when on a steep slope" or "advance warning". The third buzzer sound may be different from the first buzzer sound and the second buzzer sound, or may be the same as the first buzzer sound and the second buzzer sound.

[0054] If the driver does not operate the brake pedal 12a after time t12 even when the "notification of brake operation request before stopping when traveling on steep slope" is executed, the automatic stop control continues to operate and braking force continues to be automatically applied to the host vehicle. As a result, in the period from time t12 to time t13 in FIG. 3, the vehicle speed SDPh of the host vehicle further decreases and reaches "0" at time t13. That is, the host vehicle stops at time t13. At this time t13, the driving assistance ECU 10 executes the above-mentioned "notification of brake operation request when stopping" as shown in block B4 in FIG. 3.

[0055] Furthermore, during the period from time t13 to time t14 when the standby time Tsth has elapsed, the driving assistance ECU 10 continues to apply braking force (automatic braking). Therefore, the vehicle speed SDPh of the host vehicle is maintained at "0". When time t14 arrives, the driving assistance ECU 10 releases the application of braking force (automatic braking). At this time t14, the driving assistance ECU 10 executes the above-mentioned "notification of brake operation request when releasing automatic braking" as shown in block B5 of FIG. 3.

[0056] If the driver does not operate the brake pedal 12a during this period (the period from time t12 to time t14), a creep force that moves the vehicle forward and a force due to gravity that moves the vehicle backward act on the vehicle from time t14 onwards. In this case, since the road is a steep uphill road, the force due to gravity is greater than the creep force, and the vehicle starts to move backward (i.e., the vehicle speed SPDh becomes a negative value and its magnitude gradually increases).

[0057] In this way, when the vehicle is traveling on a steep uphill road by adaptive vehicle distance control, if the automatic stop control is activated and the vehicle speed SDPh drops to the vehicle speed threshold SPDth, thereby satisfying the advance warning condition, the steep slope pre-stop brake operation request warning is executed. Therefore, the driver is more likely to operate the brake pedal 12a before the vehicle stops. Therefore, compared to a device in which such a steep slope pre-stop brake operation request warning is not executed, it is possible to reduce the "possibility that the vehicle starts to move backward suddenly because the automatic brake is released after the waiting time Tsth has elapsed without the driver operating the brake pedal 12a." Therefore, it is possible to reduce the possibility of causing anxiety to the driver.

[0058] 3. Downhill road (steep gradient) The steep gradient pre-stop brake operation request notification is also executed when the vehicle is traveling on a steep downhill road by adaptive vehicle distance control. That is, when the vehicle is traveling on a steep downhill road and the automatic stop control is activated and the vehicle speed SDPh drops to the vehicle speed threshold SPDth, the steep gradient pre-stop brake operation request notification is executed. Therefore, the driver is more likely to operate the brake pedal 12a before the vehicle stops. Therefore, compared to a device in which such a steep gradient pre-stop brake operation request notification is not executed, it is possible to reduce the "probability that the vehicle starts to move forward suddenly because the automatic brake is released after the waiting time Tsth has elapsed without the driver operating the brake pedal 12a." Therefore, it is possible to reduce the possibility of causing anxiety to the driver.

[0059] (Specific operation) The following describes the operation of the CPU (hereinafter simply referred to as the "CPU") of the driving assistance ECU 10. The CPU executes the routines shown in the flowcharts of Figs. 4 and 5 every time a predetermined time elapses.

[0060] - Driving assistance control (Adaptive Adaptive Cruise Control (ACC) and brake operation notification) At a predetermined timing, the CPU starts the process from step 400 in FIG. 4 and proceeds to step 405 to determine whether or not the following vehicle distance control is currently being executed.

[0061] If the following vehicle distance control is not currently being executed, the CPU determines "No" in step 405, proceeds directly to step 495, and ends this routine for the time being. Note that if the following vehicle distance control is not currently being executed, the CPU starts the following vehicle distance control when the main switch 61 is changed from the OFF state to the ON state.

[0062] On the other hand, if the following vehicle distance control is currently being executed, the CPU judges "Yes" in step 405 and proceeds to step 410 to execute the following vehicle distance control described above. Next, the CPU proceeds to step 415 to determine whether the vehicle speed SPDh of the host vehicle at the current time is greater than "0" (i.e., whether the host vehicle is not stopped).

[0063] If the current vehicle speed SPDh of the host vehicle is greater than "0" (i.e., the host vehicle is moving), the CPU judges "Yes" in step 415 and proceeds to step 420 to judge whether the vehicle speed SPDp of the vehicle to be followed is "0" or not. That is, the CPU judges in step 420 whether the vehicle to be followed is stopped or not. If step 420 is established while the following vehicle distance control is being executed (if the vehicle to be followed is stopped), the CPU judges that the automatic stop control is being executed. The CPU calculates the vehicle speed SPDp of the vehicle to be followed according to the following equation (2). Vehicle speed SPDp of the vehicle to be followed = relative speed Vfx(n) + vehicle speed SPDh of the own vehicle... (2)

[0064] If the vehicle speed SPDp of the vehicle to be followed is not "0", the CPU judges "No" in step 420 and proceeds directly to step 495 to temporarily end this routine. In contrast, if the vehicle speed SPDp of the vehicle to be followed is "0", the CPU judges "Yes" in step 420 and proceeds to step 425 to obtain the gradient Inc of the road (road surface) on which the host vehicle is traveling from the navigation ECU 40. The navigation ECU 40 obtains the gradient Inc of the road on which the host vehicle is traveling based on the current position (current position) Pnow of the host vehicle and information stored in the map database 42. Furthermore, in step 425, the CPU determines whether the magnitude abs(Inc) of the gradient Inc is equal to or greater than a predetermined positive threshold gradient Ith.

[0065] If the gradient magnitude abs(Inc) is not equal to or greater than the threshold gradient Ith, the CPU determines "No" in step 425, proceeds directly to step 495, and temporarily ends this routine. In contrast, if the gradient magnitude abs(Inc) is equal to or greater than the threshold gradient Ith, the CPU determines "Yes" in step 425, proceeds to step 430, and determines whether the host vehicle speed SPDh is equal to or less than the above-mentioned positive vehicle speed threshold SPDth.

[0066] If the vehicle speed SPDh of the vehicle is greater than the vehicle speed threshold SPDth, the CPU judges "No" in step 430 and proceeds directly to step 495 to end this routine. On the other hand, if the vehicle speed SPDh of the vehicle is equal to or less than the vehicle speed threshold SPDth, the CPU judges that the advance warning condition is satisfied (judgments "Yes" in step 430) and proceeds to step 435. Then, in step 435, the CPU executes the steep slope pre-stop brake operation request notification described above using the display 51 and the speaker 52. After that, the CPU proceeds directly to step 495 to end this routine. The CPU generates the third buzzer sound for a certain period of time from the point in time when all steps from step 420 to step 430 have been judged "Yes."

[0067] On the other hand, when the CPU proceeds to step 415, if the vehicle speed SPDh of the host vehicle at the current time is "0" (i.e., the host vehicle is stopped), the CPU determines "No" in step 415 and proceeds to step 440. In step 440, the CPU determines whether the current time is within the waiting time (threshold time) Tsth since the vehicle speed SPDh of the host vehicle became "0".

[0068] If the current time is within the period from "the point when the vehicle speed SPDh of the vehicle becomes '0' to the point when the standby time Tsth has elapsed," the CPU judges "Yes" in step 440 and proceeds to step 445, where it continues to automatically apply braking force to the vehicle using the braking device (i.e., continues automatic braking) and keeps the vehicle stopped.

[0069] Next, the CPU proceeds to step 450 and executes the above-mentioned brake operation request notification when the vehicle is stopped. The CPU generates the first buzzer sound for a certain period of time from the point in time when the vehicle speed SPDh of the host vehicle becomes "0". After that, the CPU proceeds directly to step 495 and ends this routine.

[0070] If this state continues and the waiting time Tsth has elapsed since the vehicle speed SPDh of the host vehicle became "0", the CPU determines "No" at step 440 when it proceeds to step 440. Then, the CPU sequentially performs the processes of steps 455 to 465 described below, proceeds to step 495, and temporarily ends this routine.

[0071] Step 455: The CPU ends the following vehicle distance control. Step 460: The CPU stops automatically applying a braking force to the host vehicle using the braking device. That is, the CPU releases the automatic brake. Step 465: The CPU executes the above-mentioned brake operation request notification at the time of automatic brake release for a certain period of time. After that, the CPU proceeds directly to step 495 and ends this routine for the time being.

[0072] Brake operation request notification ends At a predetermined timing, the CPU starts the process from step 500 in FIG. 5 and proceeds to step 510 to determine whether or not a display is currently being executed on the display 51 in response to a steep slope pre-stop brake operation request notification.

[0073] If a display on the display 51 is currently being executed in response to the notification of a brake operation request before stopping on a steep slope, the CPU determines "Yes" in step 510 and proceeds to step 530. On the other hand, if a display on the display 51 is not currently being executed in response to the notification of a brake operation request before stopping on a steep slope, the CPU determines "No" in step 510 and proceeds to step 520.

[0074] In step 520, the CPU determines whether or not a display on the display 51 due to a brake operation request notification when stopped is currently being executed. If a display on the display 51 due to a brake operation request notification when stopped is currently being executed, the CPU determines "Yes" in step 520 and proceeds to step 530. In contrast, if a display on the display 51 due to a brake operation request notification when stopped is not currently being executed, the CPU determines "No" in step 520 and proceeds directly to step 595 to temporarily end this routine.

[0075] When the CPU proceeds to step 530, the CPU determines whether the current time is immediately after "the time when the driver operated the brake pedal 12a." The CPU determines whether the brake pedal 12a has been operated based on whether the brake pedal operation amount BP detected by the brake pedal operation amount sensor 12 has changed from "0" to "a value greater than 0" or whether the stop lamp signal Stp from the stop lamp switch 13 has changed from a low level to a high level.

[0076] If the current time is not immediately after the driver has operated the brake pedal 12a, the CPU makes a "No" determination in step 530, proceeds directly to step 595, and temporarily ends this routine.

[0077] In contrast, if the current time is immediately after the driver operates the brake pedal 12a, the CPU judges "Yes" in step 530, sequentially performs the processing of steps 540 to 560 described below, and proceeds to step 595 to temporarily end this routine.

[0078] Step 540: The CPU ends the adaptive vehicle distance control. Step 550: The CPU stops automatically applying a braking force to the host vehicle using the braking device. That is, the CPU releases the automatic brake. Step 560: The CPU stops the execution of the brake operation request notification currently being executed (that is, either the brake operation request notification before stopping when on a steep slope or the brake operation request notification when stopping).

[0079] Note that the CPU may be configured to determine whether the vehicle speed SPDp of the vehicle to be followed is greater than the "running start threshold SPDpth set to 0 or greater" when determining "Yes" in step 510, and to perform processing of steps 550 and 560 when the vehicle speed SPDp of the vehicle to be followed is greater than the running start threshold SPDpth. In other words, the CPU may be configured to stop the steep slope pre-stop brake operation request notification when the vehicle to be followed starts running and its vehicle speed becomes greater than the running start threshold SPDpth during execution of the steep slope pre-stop brake operation request notification.

[0080] According to the implementation support device configured in this manner, for example, as shown in FIG. 6, even if the preceding vehicle V1 of the vehicle to be followed Vp is stopped, if the vehicle to be followed Vp is traveling at, for example, 20 km / h and the inter-vehicle distance between the vehicle to be followed Vp and the host vehicle Vh is maintained at a constant distance Dp as the target inter-vehicle distance, the host vehicle Vh is made to travel at 20 km / h.

[0081] In this state, when the host vehicle Vh enters a steep uphill road and the following target vehicle Vp stops due to the stop of the preceding vehicle V1 as shown in Fig. 7, the implementation support device starts automatic stop control. Then, the implementation support device executes steep slope pre-stop brake operation request notification when the vehicle speed SPDh of the host vehicle Vh drops to the vehicle speed threshold SPDth (i.e., at a predetermined time before the host vehicle Vh stops).

[0082] Furthermore, as shown in FIG. 8, when the host vehicle Vh stops without the driver operating the brake pedal 12a, the implementation support device executes a brake operation request notification when the host vehicle Vh stops.

[0083] Furthermore, as shown in Figure 9, when the time during which the vehicle Vh is stopped without the driver operating the brake pedal 12a becomes longer than the waiting time Tsth, the implementation support device executes a brake operation request notification when the automatic brake is released at this point and releases the automatic brake.

[0084] As shown in FIG. 10, if the vehicle to be followed Vp starts before the host vehicle Vh stops while the steep slope brake operation request notification before stopping is being executed (more precisely, when the steep slope brake operation request notification before stopping is being displayed on the display 51), the implementation support device stops the execution of the steep slope brake operation request notification before stopping and continues the following vehicle distance control. Therefore, the vehicle speed SPDh of the host vehicle Vh gradually increases. After that, as shown in FIG. 11, if the vehicle to be followed Vp continues to accelerate, the implementation support device continues the following vehicle distance control. As a result, the host vehicle Vh continues to accelerate.

[0085] As described above, according to this implementation support device, when the vehicle is being stopped by automatic stop control, if the vehicle is traveling on a flat road, a stop-time warning (brake operation request warning when stopped) is issued to encourage the driver to apply the brakes after the vehicle has stopped, and if the vehicle is traveling on a steep slope, an advance warning (brake operation request warning before stopping on steep slope) is issued to encourage the driver to apply the brakes when an advance warning condition is met before the vehicle stops.

[0086] Therefore, the implementation support device can reduce the possibility that the application of braking force (automatic braking) is released without the driver performing the brake operation, and the vehicle starts to move backward or forward suddenly because it is stopped on a steep slope. As a result, the possibility of making the driver feel uneasy can be reduced.

[0087] The present invention is not limited to the above embodiment, and various modifications can be adopted within the scope of the present invention. For example, when the implementation support device executes the automatic stop control in the following distance control, the implementation support device executes the brake operation request notification before stopping when the vehicle is on a steep slope and the brake operation request notification when the vehicle is stopped. In contrast, the present invention can also be applied to the case where the automatic stop control at a red light or the automatic stop control at a stop sign is executed.

[0088] In brief, the red light automatic stop control is a control that judges whether or not the red light of a traffic light located in front of the vehicle is on from an image (image in front of the vehicle) acquired by the camera sensor 15b, and stops the vehicle by automatic stop control in front of an intersection where the traffic light is installed if it is judged that the red light is on. Furthermore, the stop sign automatic stop control is a control that judges whether or not a stop sign exists in front of the vehicle from an image (image in front of the vehicle) acquired by the camera sensor 15b, and stops the vehicle by automatic stop control in front of the sign if it is judged that a stop sign exists. Furthermore, the present invention can also be applied to a case where the vehicle is stopped by automatic stop control when it is judged that an abnormality has occurred in a device (for example, a steering device) other than the braking device among the driving support devices.

[0089] In the implementation support device, the first buzzer sound, the second buzzer sound, and the third buzzer sound are generated together with the notification display on the display 51, but these buzzer sounds do not have to be generated. In addition, instead of the first buzzer sound, a voice message such as "Please press the brake pedal" may be generated from the speaker 52. Instead of the second buzzer sound, a voice message such as "The automatic brake will be released, so please press the brake pedal" may be generated from the speaker 52. Furthermore, instead of the third buzzer sound, a voice message such as "Please press the brake pedal as the slope is steep" may be generated from the speaker 52.

[0090] The implementation support device may be configured to issue a brake operation request notification before stopping on a steep slope for a "fixed period of time shorter than the time required for the host vehicle to stop" from the time when the vehicle speed SDPh of the host vehicle drops to the vehicle speed threshold SPDth. Similarly, the implementation support device may be configured to issue a brake operation request notification when stopping for a "fixed period of time shorter than the standby time" from the time when the host vehicle stops. Furthermore, in this embodiment, the brake operation request notification when the automatic brake is released may be started from a point in time a predetermined time before the standby time has elapsed.

[0091] The implementation support device may detect the gradient (inclination angle) Inc of the road on which the host vehicle is traveling by a known method using an acceleration sensor that detects the longitudinal acceleration of the host vehicle. In addition, the present embodiment may include an inclination angle sensor capable of directly measuring the gradient Inc of the road on which the host vehicle is traveling, and may detect the gradient (inclination angle) Inc of the road on which the host vehicle is traveling based on the output signal of the inclination angle sensor. The map database 42 may store an area in which the magnitude of the gradient of the road is equal to or greater than a threshold gradient, and the navigation ECU 40 may determine whether the road on which the host vehicle is traveling is a road having a gradient greater than the gradient threshold based on the position of the host vehicle. In this case, the driving support ECU may obtain the result of the determination by the navigation ECU 40 from the navigation ECU 40 and use it for the determination in step 425.

[0092] The implementation support device may determine that the advance warning condition is met and execute the steep slope brake operation request notification before stopping when all of the following conditions (a) to (d) are met. (a) Automatic stop control using adaptive vehicle distance control is being executed. (b) The vehicle to be followed is stopped. Note that the condition (b) may be included as a condition for the condition (a) to be satisfied. (c) The gradient abs(Inc) of the road on which the vehicle is traveling is equal to or greater than the threshold gradient Ith. (d) The vehicle is moving (not stopped). (e) The distance from the host vehicle to the “target stopping position by automatic stop control” has changed from a distance greater than a threshold distance to a distance equal to or less than the threshold distance. Furthermore, the above condition (e) may be the following condition (f). (f) The distance between the host vehicle and the vehicle to be followed becomes equal to or smaller than a predetermined distance. In addition, the above conditions (a) and (b) can be replaced with a condition that the red light automatic stop control and the stop sign automatic stop control are being executed. [Explanation of symbols]

[0093] 10...driving assistance ECU, 12...brake pedal operation amount sensor, 12a...brake pedal, 13...stop lamp switch, 14...vehicle speed sensor, 15...vehicle environment detection sensor (ambient sensor), 15a...radar sensor, 15b...camera sensor, 30...brake ECU, 31...brake actuator, 40...navigation ECU, 41...GPS receiver, 42...map database, 50...alarm ECU, 51...display, 52...speaker.

Claims

1. A driving assistance device applied to a vehicle, an information acquisition device that acquires information representing a driving environment of the host vehicle and information regarding a driving state of the host vehicle; a braking device that operates to apply a braking force to the host vehicle; An alarm device that notifies a driver of the vehicle; a control unit that performs driving assistance control including an automatic stop control that automatically applies the braking force to the host vehicle using the braking device based on the information acquired by the information acquisition device to decelerate and stop the host vehicle, and releases the application of the braking force to the host vehicle when a predetermined time has elapsed after the host vehicle has stopped, and causes the notification device to provide a notification related to the driving assistance control; Equipped with The control unit When the host vehicle is stopped by the automatic stop control, if it is determined based on the information acquired by the information acquisition device that the host vehicle is traveling on a flat road having a gradient smaller than a predetermined threshold gradient, the notification device is caused to issue a stop time notification that prompts the driver to perform a brake operation to activate the braking device during the period from when the host vehicle stops to when the application of the braking force to the host vehicle is released, When the host vehicle is stopped by the automatic stop control, if it is determined based on the information acquired by the information acquisition device that the host vehicle is traveling on a steep slope road having a gradient equal to or greater than the threshold gradient, the notification device is caused to issue an advance notification to prompt the driver to perform the brake operation at a time point when a predetermined advance notification condition that is established at a time point prior to the time point when the host vehicle is stopped is established. A driving assistance device configured as above.

2. The driving assistance device according to claim 1, The control unit The driving assistance control is configured to execute a following driving control in which the host vehicle is driven so as to follow a following target vehicle that is a preceding vehicle traveling immediately before the host vehicle, Furthermore, the control unit When the automatic stop control is performed due to the stop of the vehicle to be followed during the execution of the following travel control, it is determined that the advance warning condition is satisfied when the vehicle to be followed is stopped and the speed of the host vehicle becomes equal to or lower than a threshold speed that is greater than zero. It was configured as follows: Driving assistance device.

3. The driving support device according to claim 1 or 2, The control unit When the brake operation is detected during the execution of the advance warning, the advance warning by the warning device is terminated. when the vehicle stops without detecting the brake operation during execution of the advance warning, the warning device is caused to perform the stop warning. It was configured as follows: Driving assistance device.

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