Driving assistance device and driving assistance method

Abstract

The driving assistance device has an ACC section, an abnormality detection section that detects an abnormality of a detector used to execute ACC, and a parking control section that performs parking control on the host vehicle when an abnormality is detected by the abnormality detection section and a vehicle-to-vehicle distance between the host vehicle and a preceding vehicle satisfies a prescribed condition.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a drive assist device and a drive assist method that assist driving of a vehicle. BACKGROUND

[0002] In recent years, as one of techniques to assist driving of a vehicle, an adaptive cruise control (hereinafter referred to as "ACC") has been attracting attention (for example, refer to Patent Literature 1). The ACC is a technique that acquires a vehicle speed of a vehicle, a relative speed of a preceding vehicle with respect to the vehicle, and a vehicle-to-vehicle distance with the preceding vehicle, and controls a drive system and a brake system of the vehicle to keep the vehicle speed and the vehicle-to-vehicle distance with the preceding vehicle constant.

[0003] Further, in the ACC, in the absence of the preceding vehicle, cruise control (hereinafter referred to as "CC") that controls the speed of the own vehicle to a set speed set in advance is generally performed. The CC is a technique that detects a difference between the set speed set by the driver and an actual vehicle speed (actual speed), and controls engine output and a shift stage (shift ratio) of a transmission based on the speed difference to control in such a manner that the actual speed converges to the set speed.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 7-17295 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, in a vehicle equipped with the ACC function, generally, in the execution of the ACC, in a case where a detector (for example, a millimeter wave radar or a camera, or the like) required for execution of the ACC fails, so that information for execution of the ACC cannot be acquired, the ACC is ended, and a drive mode by the driver is made.

[0009] The ACC end is notified to the driver by an indicator or the like, but the driver who has been relying on the ACC until then does not necessarily make a driving operation promptly, and as a result, an accident can occur. In particular, in a case where the detector fails and the ACC ends just before parking, it is considered that the possibility of causing an accident becomes higher than in other situations.

[0010] In view of the above, the present disclosure provides a drive assist device and a drive assist method that can reduce the possibility of a collision even in a case where a detector required for execution of the ACC fails in the execution of the ACC, so that the usual ACC cannot be executed.

[0011] Means for solving the problem

[0012] One embodiment of the driving assistance device of the present disclosure is a driving assistance device that assists driving of a vehicle, including:

[0013] an ACC (Adaptive Cruise Control) section that performs ACC based on at least an inter-vehicle distance from the host vehicle to a preceding vehicle and a relative speed of the host vehicle with respect to the preceding vehicle;

[0014] an abnormality detection section that detects an abnormality of a detector used to perform the ACC; and

[0015] a parking control section that performs parking control of the host vehicle in a case where an abnormality is detected by the abnormality detection section and a condition is satisfied with respect to the inter-vehicle distance between the host vehicle and the preceding vehicle.

[0016] The driving assistance method of the present disclosure is a driving assistance method that assists driving of a vehicle, the method including:

[0017] an ACC (Adaptive Cruise Control) step of performing ACC based on at least an inter-vehicle distance from the host vehicle to a preceding vehicle and a relative speed of the host vehicle with respect to the preceding vehicle;

[0018] an abnormality detection step of detecting an abnormality of a detector used to perform the ACC;

[0019] a parking control step of performing parking control of the host vehicle in a case where an abnormality is detected in the abnormality detection step and a condition is satisfied with respect to the inter-vehicle distance between the host vehicle and the preceding vehicle.

[0020] Effects of the Invention

[0021] According to the present disclosure, the parking control section performs parking control of the host vehicle in a case where an abnormality is detected by the abnormality detection section and a condition is satisfied with respect to the inter-vehicle distance between the host vehicle and the preceding vehicle, and thus, even in a case where a detector required to perform the ACC fails and thus the ACC cannot be performed as usual in the execution of the ACC, it is possible to reduce the possibility of a collision. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is an appearance view that shows an example of a vehicle to which the driving assistance device according to the embodiment is applied;

[0023] Figure 2 is a block diagram that shows a structure of the vehicle according to the embodiment;

[0024] Figure 3 is a block diagram that shows a configuration of the driving assistance device according to the embodiment;

[0025] Figure 4 is a flowchart for explaining a travel control action of the driving assist device. DETAILED DESCRIPTION

[0026] Hereinafter, one embodiment of the present application will be explained in detail with reference to the drawings.

[0027] <1> Structure of vehicle

[0028] First, the structure of a vehicle including a driving assist device related to one embodiment of the present disclosure will be explained.

[0029] Figure 1 is an appearance view showing an example of a vehicle 1 to which the driving assist device related to the present embodiment is applied. Also, Figure 2 is a block diagram showing the structure of the vehicle 1. Also, here, the illustration and explanation are focused on the parts associated with the driving assist device.

[0030] As shown in Figure 1 , the vehicle 1 is a tractor capable of coupling and towing a trailer 2. The vehicle 1 has a vehicle main body portion 3 including a power system such as an engine and drive wheels, a driver's seat, and the trailer 2 coupled to the vehicle main body portion 3.

[0031] As shown in Figure 2 , the vehicle 1 has a drive system 10 that causes the vehicle 1 to travel, a brake system 20 that causes the vehicle 1 to decelerate, a driving assist device 30 that assists a driver in driving the vehicle 1, and the like.

[0032] The drive system 10 has an engine 11, a clutch 12, a transmission 13, a propeller shaft 14, a differential gear 15, a drive shaft 16, a wheel 17, an engine ECU 18, and a power transmission ECU 19.

[0033] The engine ECU 18 and the power transmission ECU 19 are connected to the driving assist device 30 through an in-vehicle network such as a CAN (Controller Area Network), and can mutually transmit and receive required data and control signals. The engine ECU 18 controls the output of the engine 11 in accordance with a drive instruction from the driving assist device 30. The power transmission ECU 19 controls the disconnection of the clutch 12 and the shifting of the transmission 13 in accordance with a drive instruction from the driving assist device 30.

[0034] The power of the engine 11 is transmitted to the transmission 13 via the clutch 12. The power transmitted to the transmission 13 is further transmitted to the wheels 17 via the propeller shaft 14, the differential device 15, and the drive shaft 16. Thus, the power of the engine 11 is transmitted to the wheels 17 to cause the vehicle 1 to travel.

[0035] The brake system 20 has a service brake 21, auxiliary brakes 22, 23, a parking brake (omitted from illustration), and a brake ECU 24.

[0036] The service brake 21 is generally a brake called a main brake, a friction brake, a foot brake, or a foundation brake, etc. The service brake 21 is, for example, a drum brake that obtains a braking force by pressing a brake pad against the inner side of a drum that rotates together with the wheels 17.

[0037] The auxiliary brake 22 is a retarder (hereinafter referred to as "retarder 22") that obtains a braking force by directly applying a load to the rotation of the propeller shaft 14, and is, for example, an electromagnetic retarder. The auxiliary brake 23 is an exhaust brake (hereinafter referred to as "exhaust brake 23") that uses the rotational resistance of the engine to improve the effect of engine braking. By providing the retarder 22 and the exhaust brake 23, it is possible to increase the braking force, and it is possible to reduce the frequency of use of the service brake 21, so it is possible to suppress the consumption of brake pads and the like.

[0038] The brake ECU 24 is connected to the drive assist device 30 via an in-vehicle network such as CAN, and can mutually transmit and receive required data, control signals. The brake ECU 24 controls the braking force of the service brake 21 (brake hydraulic pressure of the wheel cylinder of the wheels 17) in accordance with a brake command from the drive assist device 30.

[0039] The braking action of the service brake 21 is controlled by the drive assist device 30 and the brake ECU 24. The braking action of the retarder 22 and the exhaust brake 23 is controlled by the drive assist device 30 in an on / off manner. Since the braking force of the retarder 22 and the exhaust brake 23 is substantially fixed, it is appropriate to use the service brake 21 that can finely adjust the braking force in the case where the desired braking force is accurately generated.

[0040] The drive assist device 30 inputs information from a millimeter wave radar, a camera. The information from the millimeter wave radar, the camera is information indicating the traffic situation, the road situation in front of the vehicle. In addition, the drive assist device 30 has an ACC operation section 41, an accelerator operation detection section 43, a brake operation detection section 44, etc.

[0041] The drive assist device 30 forms control signals for controlling the actions of the drive system 10 and the brake system 20. In particular, the drive assist device 30 of the present embodiment calculates a target acceleration / deceleration for realizing ACC, a target acceleration for realizing CC, and outputs them to the engine ECU 18, the power transmission ECU 19, and the brake ECU 24 as appropriate.

[0042] In addition, although not shown, the engine ECU 18, the power transmission ECU 19, the brake ECU 24, and the drive assist device 30 each have, for example, a CPU (Central Processing Unit), a storage medium such as a ROM (Read Only Memory) in which a control program is stored, a work memory such as a RAM (Random Access Memory), and a communication circuit. In this case, the functions of the respective parts described later that constitute the drive assist device 30 are realized by the CPU executing the control program. Furthermore, all or a part of the engine ECU 18, the power transmission ECU 19, the brake ECU 24, and the drive assist device 30 can be integrally constituted.

[0043] The ACC operation section 41 includes an ACC on / off switch for performing on / off control of the action of ACC. In addition, the ACC operation section 41 includes a setting switch for performing various settings of ACC. The driver can set, for example, a target inter-vehicle distance and a target vehicle speed, and the like by operating the setting switch. Furthermore, these switches can also be realized by a user interface displayed on a display with a touch panel.

[0044] The accelerator operation detection section 43 detects the amount of depression of the accelerator pedal and outputs the detection result to the drive assist device 30. The drive assist device 30 sends a drive command to the engine ECU 18 and the power transmission ECU 19 on the basis of the amount of depression of the accelerator pedal.

[0045] The brake operation detection section 44 detects the amount of depression of the brake pedal for actuating the main brake 21. In addition, the brake operation detection section 44 detects whether or not the auxiliary brake lever for actuating the retarder 22 or the exhaust brake 23 is operated. Furthermore, the brake operation detection section 44 outputs the detection results related to the brake pedal and the auxiliary brake lever to the drive assist device 30. The drive assist device 30 sends a brake command to the brake ECU 24 on the basis of the amount of depression of the brake pedal. In addition, the drive assist device 30 controls the on / off action of the retarder 22 or the exhaust brake 23 on the basis of the operation of the auxiliary brake lever.

[0046] In addition, the drive assist device 30 outputs various kinds of information related to driving from the information output section 50. For example, it is outputted from the information output section 50 by sound, display that the ACC is being executed, the ACC is being stopped, and the like.

[0047] <2> Configuration of Drive Assist Device

[0048] Figure 3 is a block diagram showing the configuration of the drive assist device 30 of the present embodiment.

[0049] The drive assist device 30 has an inter-vehicle distance detection section 31, an ACC section 32, an abnormality detection section 33, and a parking control section 34.

[0050] The inter-vehicle distance detection section 31 measures (detects) the inter-vehicle distance between the host vehicle 1 and the preceding vehicle on the basis of information obtained by a millimeter wave radar, a camera, or the like, and outputs the measurement result to the ACC section 32. In addition, the inter-vehicle distance detection section 31 can measure the inter-vehicle distance on the basis of information from other sensors such as a laser radar.

[0051] The ACC section 32 basically executes a known ACC process. That is, the ACC section 32 outputs a target acceleration and deceleration for causing the host vehicle to follow the preceding vehicle on the basis of the relative speed and the inter-vehicle distance between the host vehicle and the preceding vehicle. Thereby, automatic follow-up control can be realized. In addition, in the absence of the preceding vehicle, the ACC section 32 outputs a target acceleration for causing the speed of the host vehicle to be a set constant speed. Thereby, constant speed driving control can be realized.

[0052] The automatic follow-up driving control refers to control for causing the drive system 10 and the brake system 20 to act so as to cause the inter-vehicle distance to converge within a prescribed target range and the relative speed to approach zero in the presence of the preceding vehicle within a prescribed range. The constant speed driving control refers to control for causing the drive system 10 and the brake system 20 to act so as to cause the driving speed of the vehicle 1 to approach a prescribed target value in the absence of the preceding vehicle within a prescribed range.

[0053] The abnormality detection section 33 inputs the outputs of detectors for realizing the ACC, and detects abnormalities of the respective detectors. For example, as the detectors for realizing the ACC, there are a millimeter wave radar, a camera, a laser radar (not shown), a vehicle speed sensor (not shown), and the like. The abnormality detection section 33 outputs an abnormality signal in the case where the outputs of these detectors become a state in which the ACC cannot be normally executed (for example, in the case of failure). This abnormality signal is sent to the ACC section 32 and the parking control section 34.

[0054] The parking control section 34 inputs the output of the abnormality detection section 33, the output of the inter-vehicle distance detection section 31, and information of the millimeter wave radar or the camera, and outputs a parking control signal (target deceleration) for performing parking control of the host vehicle in a case where an abnormality is detected by the abnormality detection section 33 and the inter-vehicle distance with the preceding vehicle satisfies a prescribed condition. The target deceleration is a target deceleration that is independent of the determined value of the detector that detected the abnormality. The target deceleration is sent to the ECU 24 for the brake.

[0055] <3> Travel control action of the driving assistance device

[0056] Next, the travel control action of the driving assistance device 30 will be described. Figure 4 is a flowchart for explaining the travel control action of the driving assistance device 30.

[0057] First, the driving assistance device 30 performs ACC based on the ACC section 32 in step Sll. The driving assistance device 30, in the next step S12, the abnormality detection section 33 performs abnormality determination of the detector for ACC, and in a case where there is no abnormality in the detector (step S12: No), returns to step Sll to continue ACC.

[0058] In contrast, the driving assistance device 30, in a case where there is an abnormality in the detector (step S12: Yes), proceeds to step S13. In addition, in a case where there is an abnormality in the detector, an abnormality detection signal is output from the abnormality detection section 33 to the ACC section 32 and the parking control section 34, whereby the ACC section 32 and the parking control section 34 can recognize that there is an abnormality in the detector.

[0059] In step S13, it is determined whether the inter-vehicle distance with the preceding vehicle is below the threshold value D, and in step S14, it is determined whether the inter-vehicle distance with the preceding vehicle has a decreasing tendency. These determinations are performed by the parking control section 34.

[0060] When affirmative results are obtained in both step S13 and step S14, that is, when the inter-vehicle distance with the preceding vehicle is below the threshold value D and the inter-vehicle distance with the preceding vehicle has a decreasing tendency, the processing proceeds to step S15. In step S15, parking control is performed by the parking control section 34, and ACC is released. In addition, the case where parking control is performed by the parking control section 34 and the case where ACC is released are notified to the driver by the information output section 50.

[0061] In this case, the affirmative result in both of steps S13 and S14 means a situation in which the inter-vehicle distance with the preceding vehicle is short and the distance with the preceding vehicle is shortened, and in such a situation, if the ACC is released, it is likely to cause an accident. Therefore, the driving assistance device 30 of the present embodiment performs the stop control of the stop control section 34 together with the release of the ACC in step S15. At this time, the stop control signal (target deceleration) is output from the stop control section 34 to the brake ECU 24, as a result of which the vehicle 1 is stopped at the target deceleration.

[0062] On the other hand, in the case where the negative result is obtained in either of steps S13 and S14, i.e., in the case where the inter-vehicle distance with the preceding vehicle is greater than the threshold value D or the inter-vehicle distance with the preceding vehicle has no tendency to decrease, the process proceeds to step S16. In step S16, the ACC is released without performing the stop control of the stop control section 34. In addition, the release of the ACC is notified to the driver by the information output section 50.

[0063] In this case, the negative result in either of steps S13 and S14 means a situation in which the likelihood of causing an accident even if the ACC is released is very small. Therefore, the driving assistance device 30 of the present embodiment does not perform the stop control of the stop control section 34 in step S16, but only performs the release of the ACC. That is, the release of the ACC is performed, and the driving operation of the driver is entrusted.

[0064] In addition, strictly speaking, the determination result that the detector has an abnormality is obtained in step S12 means a situation in which the inter-vehicle distance with the preceding vehicle cannot be detected, and therefore the determinations of steps S13 and S14 cannot be performed. In order to avoid such a situation, in the present embodiment, the stop control section 34 always inputs the inter-vehicle distance with the preceding vehicle and stores it, and the determinations of steps S13 and S14 are performed using the inter-vehicle distance before the abnormality of the detector occurs.

[0065] <4>Effects of the Embodiment

[0066] As described above, according to the present embodiment, the driving assistance device 30 has: the ACC section 32; the abnormality detection section 33 that detects an abnormality of a detector used to execute the ACC; and the stop control section 34 that performs stop control of the host vehicle in the case where the abnormality is detected by the abnormality detection section 33 and the inter-vehicle distance with the preceding vehicle satisfies a prescribed condition. Thereby, it is possible to realize the driving assistance device 30 that can reduce the likelihood of collision even in the case where the detector required to execute the ACC fails in the execution of the ACC, and thus the normal ACC cannot be executed.

[0067] <5>Other Embodiments

[0068] The above-described embodiments merely show one example of the embodiment of the present application, and the technical scope of the present application should not be interpreted restrictively based on these embodiments. That is, the present application can be implemented in various forms without departing from the spirit or main features thereof.

[0069] <5-1> In the above-described embodiment, the stop control section 34 is described as a different component from the ACC section 32, but the stop control section 34 can be included in the ACC section 32. That is, in the above-described embodiment, the stop control is described as a control different from the ACC, but the stop control can be performed as a part of the ACC. In the processing of the above-described embodiment, in a case where an abnormality is detected by the abnormality detection section 33 and the inter-vehicle distance with the preceding vehicle satisfies a prescribed condition, the ACC that outputs a predetermined target deceleration regardless of the detector that detects the abnormality can also be performed.

[0070] <5-2> In the above-described embodiment, the case where the stop control is performed on the host vehicle in a case where an abnormality is detected by the abnormality detection section 33 and the inter-vehicle distance is equal to or less than a prescribed threshold value D and the inter-vehicle distance has a decreasing tendency is described, but the present application is not limited to this. For example, the stop control section 34 can perform the stop control on the host vehicle in a case where an abnormality is detected by the abnormality detection section 33 and the inter-vehicle distance has a decreasing tendency.

[0071] <5-3> The stop control by the stop control section 34 can also be performed in a case where the state determination section determines that the host vehicle is about to stop, on the basis of the above-described embodiment. In this way, the stop control is performed at the time of the stop in which the possibility of collision if the ACC is released is high, compared to other cases.

[0072] In addition, the state determination section can determine whether the host vehicle is about to stop on the basis of the inter-vehicle distance with the preceding vehicle and the speed of the host vehicle. In addition, the inter-vehicle distance with the preceding vehicle used in the determination of whether the host vehicle is about to stop is preferably a distance shorter than the inter-vehicle distance set for the ACC.

[0073] <5-4> The stop control by the stop control section 34 can also continue until there is a driver's operation related to travel, on the basis of the above-described embodiment. In other words, the stop control by the stop control section 34 is released in a case where there is a driver's operation related to travel. Thus, it is possible to prevent the stop control by the stop control section 34 from interfering with the driver's operation related to travel. For example, it is possible to prevent the brake control by the stop control section 34 despite the fact that the driver has depressed the accelerator.

[0074] <5-5> In the above-described embodiment, the vehicle 1 to which the driving assistance apparatus and method of the present application is applied is a towing vehicle that is capable of coupling a trailer 2 and towing it, but the vehicle to which the present application can be applied is not limited to this, and can be, for example, a passenger car or the like.

[0075] This application is based on Japanese Patent Application No. 2020-33761 filed on February 28, 2020, and the entire contents thereof are incorporated herein by reference.

[0076] Industrial Applicability

[0077] The driving assistance apparatus and driving assistance method of the present disclosure are useful as a driving assistance apparatus and driving assistance method that can reduce the likelihood of collision even in a case where a detector required for execution of ACC fails to function in the execution of ACC, so that the usual ACC cannot be executed.

[0078] Explanation of Symbols

[0079] 1 Vehicle

[0080] 2 Trailer

[0081] 3 Vehicle main body portion

[0082] 10 Drive system

[0083] 11 Engine

[0084] 12 Clutch

[0085] 13 Transmission

[0086] 14 Propeller shaft

[0087] 15 Differential

[0088] 16 Drive shaft

[0089] 17 Wheel

[0090] 18 Engine ECU

[0091] 19 Power transmission ECU

[0092] 20 Brake system

[0093] 21 Service brake

[0094] 22 Retarder

[0095] 23 Exhaust brake

[0096] 24 Brake ECU

[0097] 30 Driving assistance apparatus

[0098] 31 inter-vehicle distance detection section

[0099] 32 ACC section

[0100] 33 abnormality detection section

[0101] 34 parking control section

[0102] 41 ACC operation section

[0103] 43 accelerator operation detection section

[0104] 44 brake operation detection section

[0105] 50 information output section

Claims

1. A driving assist apparatus that assists driving of a vehicle, the driving assist apparatus comprising: an ACC section that performs ACC based on at least an inter-vehicle distance from a host vehicle to a preceding vehicle and a relative speed of the host vehicle to the preceding vehicle; an abnormality detection section that detects an abnormality of a detector used to perform the ACC; and a stop control section that performs stop control of the host vehicle in a case where an abnormality is detected by the abnormality detection section and the inter-vehicle distance between the host vehicle and the preceding vehicle satisfies a prescribed condition, wherein, in a case where an abnormality is detected by the abnormality detection section, if the inter-vehicle distance is greater than a prescribed threshold or if the inter-vehicle distance has no decreasing tendency, ACC processing by the ACC section is released and the stop control by the stop control section is not performed.

2. The driving assist apparatus according to claim 1, wherein the stop control section performs stop control of the host vehicle in a case where an abnormality is detected by the abnormality detection section and the inter-vehicle distance has a decreasing tendency.

3. The driving assist apparatus according to claim 1, wherein the stop control section performs stop control of the host vehicle in a case where an abnormality is detected by the abnormality detection section and the inter-vehicle distance is equal to or less than a prescribed threshold and the inter-vehicle distance has a decreasing tendency.

4. The driving assist apparatus according to claim 1, wherein the ACC processing by the ACC section is released when the stop control by the stop control section is performed.

5. The driving assist apparatus according to claim 1, wherein the stop control section outputs a target deceleration that is independent of a determination value of the detector in which an abnormality is detected.

6. The driving assist apparatus according to claim 1, further comprising: a state determination section that determines that the host vehicle is about to stop, wherein the stop control by the stop control section is performed in a case where it is determined by the state determination section that the host vehicle is about to stop.

7. The driving assist apparatus according to claim 6, wherein the state determination section determines whether or not the host vehicle is about to stop based on the inter-vehicle distance between the host vehicle and the preceding vehicle and a host vehicle speed.

8. The driving assist apparatus according to claim 7, wherein the inter-vehicle distance between the host vehicle and the preceding vehicle used to determine whether or not the host vehicle is about to stop is a distance shorter than an inter-vehicle distance set for the ACC.

9. The driving assist apparatus according to claim 1, wherein the stop control by the stop control section continues until there is a driver's operation related to travel.

10. A driving assist method that assists driving of a vehicle, the method comprising: an ACC step of performing ACC based on at least an inter-vehicle distance from a host vehicle to a preceding vehicle and a relative speed of the host vehicle to the preceding vehicle; an abnormality detection step of detecting an abnormality of a detector used to perform the ACC; a stop control step of performing stop control of the host vehicle in a case where an abnormality is detected in the abnormality detection step and the inter-vehicle distance between the host vehicle and the preceding vehicle satisfies a prescribed condition, ​ When an abnormality is detected in the abnormality detection step, if the inter-vehicle distance is greater than a prescribed threshold, or if the inter-vehicle distance has no tendency to decrease, the ACC processing by the ACC step is canceled, and the stop control by the stop control step is not performed.

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