Patent ID: 12240444

DESCRIPTION OF EMBODIMENTS

One embodiment of the present invention is described in detail below with reference to the accompanying drawings.

<1> Configuration of Vehicle

First, the configuration of a vehicle including a driving assistance apparatus according to one embodiment of the present disclosure is described.

FIG.1is an external view illustrating an example of vehicle1to which a driving assistance apparatus according to the present embodiment is applied.FIG.2is a block diagram illustrating the configuration of vehicle1. Illustration and description are made by focusing on parts relating to the driving assistance apparatus.

As illustrated inFIG.1, vehicle1is a tractor (traction vehicle) capable of towing trailer2as a result of coupling trailer2to the tractor. Vehicle1has vehicle main-body portion3including a power system such as an engine and driving wheels and a driver's seat, and trailer2coupled to vehicle main-body portion3.

As illustrated inFIG.2, vehicle1has driving system10that causes vehicle1to travel, braking system20that decelerates vehicle1, driving assistance apparatus30that assists the driving of vehicle1by a driver, and the like.

Driving system10has engine11, clutch12, transmission13, propeller shaft14, differential gear15, drive shaft16, wheels17, engine ECU18, and motive power transmission ECU19.

Engine ECU18and motive power transmission ECU19are connected to driving assistance apparatus30by an in-vehicle network such as a controller area network (CAN) and are able to transmit and receive necessary data and control signals to and from each other. Engine ECU18controls the output of engine11in accordance with a drive command from driving assistance apparatus30. Motive power transmission ECU19controls the connection and disconnection of clutch12and the speed change of transmission13in accordance with a drive command from driving assistance apparatus30.

The motive power of engine11is transmitted to transmission13via clutch12. The motive power transmitted to transmission13is further transmitted to wheels17via propeller shaft14, differential gear15, and drive shaft16. As a result, the motive power of engine11is transmitted to wheels17, and vehicle1travels.

Braking system20has service brakes21, auxiliary brakes22,23, a parking brake (not shown), and brake ECU24.

Service brake21is a brake that is generally referred to as a main brake, a friction brake, a foot brake, a foundation brake, or the like. Service brake21is a drum brake that obtains braking force by pressing a brake lining against the inner side of a drum that rotates with wheel17, for example.

Auxiliary brake22is a retarder (hereinafter referred to as “retarder22”) that obtains braking force by directly giving load to the rotation of propeller shaft14, and is an electromagnetic retarder, for example. Auxiliary brake23is an exhaust brake (hereinafter referred to as “exhaust brake23”) that increases an effect of an engine brake with use of rotational resistance of the engine. By providing retarder22and exhaust brake23, the braking force can be increased, and the frequency of usage of service brakes21is reduced. Therefore, the wear-out of brake lining and the like can be suppressed.

Brake ECU24is connected to driving assistance apparatus30by an in-vehicle network such as a CAN and is able to transmit and receive necessary data and control signals to and from each other. Brake ECU24controls the braking force of service brakes21(the brake fluid pressure of wheel cylinders of wheels17) in accordance with a braking command from driving assistance apparatus30.

The braking operation of service brakes21is controlled by driving assistance apparatus30and brake ECU24. The braking operation of retarder22and exhaust brake23is controlled by on/off by driving assistance apparatus30. The braking force of retarder22and exhaust brake23is substantially fixed. Therefore, when a desired braking force is to be accurately generated, service brakes21that can fine-adjust the braking force are suitable.

Information from a millimeter-wave radar and a camera is input to driving assistance apparatus30. Information from the millimeter-wave radar and the camera is information indicating the traffic situation and the road situation ahead of the vehicle. Driving assistance apparatus30has ACC operation section41, accelerator-operation detection section43, brake-operation detection section44, and the like.

Driving assistance apparatus30forms control signals for controlling the operation of driving system10and braking system20. In particular, driving assistance apparatus30of the present embodiment obtains a target acceleration/deceleration speed for realizing ACC and a target acceleration speed for realizing CC and outputs the target acceleration/deceleration speed and the target acceleration speed to engine ECU18, motive power transmission ECU19, and brake ECU24, as appropriate.

Although not shown, each of engine ECU18, motive power transmission ECU19, brake ECU24, and driving assistance apparatus30has a central processing unit (CPU), a storage medium such as a read only memory (ROM) in which a control program is stored, a working memory such as a random access memory (RAM), and a communication circuit, for example. In this case, for example, the functions of sections described below constituting driving assistance apparatus30are realized by executing control programs by the CPU. All or some of engine ECU18, motive power transmission ECU19, brake ECU24, and driving assistance apparatus30may be integrated.

ACC operation section41includes an ACC ON/OFF switch for performing ON/OFF control of the operation of the ACC. ACC operation section41includes setting switches for setting various settings of the ACC. A driver can set a target inter-vehicle distance and a target own-vehicle speed, for example, by operating the setting switches. Those switches may be realized by a user interface displayed on a display with a touch screen.

Accelerator-operation detection section43detects the depression amount of an accelerator pedal and outputs the detection result to driving assistance apparatus30. Driving assistance apparatus30transmits drive commands to engine ECU18and motive power transmission ECU19on the basis of the depression amount of the accelerator pedal.

Brake-operation detection section44detects the depression amount of a brake pedal for operating service brakes21. Brake-operation detection section44detects whether an auxiliary brake lever that causes retarder22or exhaust brake23to operate has been operated. Brake-operation detection section44outputs the detection result relating to the brake pedal and the auxiliary brake lever to driving assistance apparatus30. Driving assistance apparatus30transmits a braking command to brake ECU24on the basis of the depression amount of the brake pedal. Driving assistance apparatus30controls the ON/OFF operation of retarder22or exhaust brake23on the basis of the operation of the auxiliary brake lever.

Driving assistance apparatus30outputs various information relating to traveling from information output section50. For example, information output section50outputs that sound and display, to thereby indicate that the ACC is being executed or the ACC is being stopped.

<2> Configuration of Driving Assistance Apparatus

FIG.3is block diagram illustrating the configuration of driving assistance apparatus30of the present embodiment.

Driving assistance apparatus30has inter-vehicle-distance detection section31, ACC section32, abnormality detection section33, and vehicle-stopping control section34.

Inter-vehicle-distance detection section31measures (detects) the inter-vehicle distance between own vehicle1and a leading car on the basis of information obtained by the millimeter-wave radar, the camera, and the like, and outputs the measurement result to ACC section32. Inter-vehicle-distance detection section31may measure the inter-vehicle distance on the basis of information from other sensors such as a laser radar.

ACC section32basically executes known ACC processing. In other words, ACC section32outputs a target acceleration/deceleration speed for causing own car to follow a leading car on the basis of the relative speed and the inter-vehicle distance between the own car and the leading car. As a result, automatic following control is realized. When there are no leading cars, ACC section32outputs a target acceleration speed for causing the speed of the own car to be a set certain speed. As a result, constant-speed traveling control is realized.

Automatic-following traveling control is control that operates driving system10and braking system20such that the inter-vehicle distance is within a predetermined target range and the relative speed approaches zero when a leading vehicle is present in a predetermined range. The constant-speed traveling control is control that operates driving system10and braking system20such that the traveling speed of vehicle1approaches a predetermined target value when there are no leading vehicles in a predetermined range.

The outputs of detectors used to realize the ACC are input to abnormality detection section33, which detects the abnormality of each detector. For example, the detectors used to realize the ACC include the millimeter-wave radar, the camera, the laser radar (not shown), a vehicle speed sensor (not shown), and the like. An abnormality signal is output to abnormality detection section33when the outputs of those detectors are in a state in which the ACC cannot be normally executed (for example, when there is a failure). The abnormality signal is transmitted to ACC section32and vehicle-stopping control section34.

The output of abnormality detection section33, the output of inter-vehicle-distance detection section31, and information from the millimeter-wave radar and the camera are input to vehicle-stopping control section34. When an abnormality is detected by abnormality detection section33and the inter-vehicle distance from the leading car satisfies a predetermined condition, vehicle-stopping control section34outputs a vehicle-stopping control signal (target deceleration speed) for performing vehicle-stopping control of the own car. The target deceleration speed is a target deceleration speed at a fixed value independent of the detector in which an abnormality is detected. The target deceleration speed is transmitted to brake ECU24.

<3> Traveling Control Operation of Driving Assistance Apparatus

Next, a traveling control operation of driving assistance apparatus30is described.FIG.4is a flowchart provided for the description of the traveling control operation of driving assistance apparatus30.

First, driving assistance apparatus30executes the ACC by ACC section32in Step S11. In following Step S12, abnormality detection section33performs abnormality determination of the detector used in the ACC, and driving assistance apparatus30returns to Step S11and continues the ACC when there are no abnormalities in the detector (Step S12; NO).

Meanwhile, when there is an abnormality in the detector (Step S12; YES), driving assistance apparatus30transitions to Step S13. When there is an abnormality in the detector, an abnormality detection signal is output to ACC section32and vehicle-stopping control section34from abnormality detection section33. As a result, ACC section32and vehicle-stopping control section34can recognize that there is an abnormality in the detector.

In Step13, it is determined whether the inter-vehicle distance from the leading car is equal to or less than threshold value D. In Step S14, it is determined whether the inter-vehicle distance from the leading car is on a decreasing trend. Those determinations are performed by vehicle-stopping control section34.

When an affirmative result is obtained in both of Step S13and Step S14, in other words, when the inter-vehicle distance from the leading car is equal to or less than threshold value D and the inter-vehicle distance from the leading car is on a decreasing trend, the processing transitions to Step S15. In Step S15, vehicle-stopping control by vehicle-stopping control section34is performed and the ACC is removed. The driver is to be notified of the fact that the vehicle-stopping control by vehicle-stopping control section34is being performed and the ACC is removed by information output section50.

When an affirmative result is obtained in both of Step S13and Step S14, it means that the inter-vehicle distance from the leading car is short and the distance from the leading car is to be decreased. When the ACC is removed in such a situation, there is a risk that an accident is caused. Thus, in Step S15, driving assistance apparatus30of the present embodiment performs vehicle-stopping control by vehicle-stopping control section34with the removal of the ACC. At this time, the vehicle-stopping control signal (target deceleration speed) is output to brake ECU24from vehicle-stopping control section34. As a result, vehicle1stops in accordance with the target deceleration speed.

Meanwhile, when a negative result is obtained in either one of Step S13and Step S14, in other words, when the inter-vehicle distance from the leading car is greater than threshold value D or the inter-vehicle distance from the leading car is not on a decreasing trend, the processing transitions to Step S16. In Step S16, the ACC is removed, and the vehicle-stopping control by vehicle-stopping control section34is not performed. The driver is to be notified of the fact that the ACC is removed by information output section50.

When a negative result is obtained in either one of Step S13and Step S14, it means that a possibility that an accident is caused is extremely low even when the ACC is removed. Thus, driving assistance apparatus30of the present embodiment does not perform the vehicle-stopping control by vehicle-stopping control section34and only performs the removal of the ACC in Step S16. In other words, the removal of the ACC is performed, and the driving operation of the driver is relied on.

Strictly speaking, when a determination result indicating that there is an abnormality in the detector is obtained in Step S12, it means that the inter-vehicle distance from the leading car cannot be detected, and hence the determination in Step S13and Step S14cannot be performed. In order to avoid the above, in the present embodiment, vehicle-stopping control section34constantly has the inter-vehicle distance from the leading car input thereto and stored therein and performs the determination in Step S13and Step S14with use of the inter-vehicle distance immediately before an abnormality occurs in the detector.

<4> Effects of Embodiment

As described above, according to the present embodiment, driving assistance apparatus30includes: ACC section32; abnormality detection section33that detects an abnormality of the detector used to execute the ACC; and vehicle-stopping control section34that performs the vehicle-stopping control of the own car when an abnormality is detected by abnormality detection section33and the inter-vehicle distance from the leading car satisfies a predetermined condition. As a result, driving assistance apparatus30capable of reducing the possibility of collision even when the detector necessary for executing the ACC fails during the execution of the ACC and normal ACC cannot be executed.

<5> Other Embodiments

The abovementioned embodiment is merely an example of a realization for carrying out the present invention, and the interpretation of the technical scope of the present invention is not to be limited by those embodiments. In other words, the present invention can be carried out in various forms without departing from the gist or the main features of the present invention.

<5-1> In the abovementioned embodiment, vehicle-stopping control section34is described to be separate from ACC section32, but vehicle-stopping control section34may be included in ACC section32. In other words, in the abovementioned embodiment, the vehicle-stopping control is described to be a control different from the ACC, but the vehicle-stopping control may be performed as a part of the ACC. It can also be said that the processing of the abovementioned embodiment performs the ACC that outputs a predetermined target deceleration speed that is independent of the detector in which an abnormality is detected when an abnormality is detected by abnormality detection section33and the inter-vehicle distance from the leading car satisfies a predetermined condition.

<5-2> In the abovementioned embodiment, a case where the vehicle-stopping control of the own car is performed when an abnormality is detected by abnormality detection section33, the inter-vehicle distance is equal to or less than predetermined threshold value D, and the inter-vehicle distance is on a decreasing trend, but the present invention is not limited thereto. For example, vehicle-stopping control section34may perform the vehicle-stopping control of the own car when an abnormality is detected by abnormality detection section33and the inter-vehicle distance is on a decreasing trend.

<5-3> In addition to the abovementioned embodiment, a state determination section that determines that the own car is about to be stopped may be further included, and the vehicle-stopping control by vehicle-stopping control section34may be executed when the state determination section determines that the own car is about to be stopped. By the above, as compared to other cases, the vehicle-stopping control is performed when the vehicle is about to be stopped, that is, when the possibility of collision is high when the ACC is removed.

The state determination section may determine whether the vehicle is about to be stopped on the basis of the inter-vehicle distance from the leading car and the own car speed. The inter-vehicle distance from the leading car used in the determination of whether the vehicle is about to be stopped is preferably a distance shorter than an inter-vehicle distance set for the ACC.

<5-4> In addition to the abovementioned embodiment, the vehicle-stopping control by vehicle-stopping control section34may be continued until there is an operation relating to traveling by the driver. In other words, when there is an operation relating to traveling by the driver, the vehicle-stopping control by vehicle-stopping control section34is removed. By the above, the vehicle-stopping control by vehicle-stopping control section34can be prevented from hindering the operation relating to traveling by the driver. For example, a case where brake control is performed by vehicle-stopping control section34even when the driver is stepping on an accelerator is prevented.

<5-5> In the present embodiment, a case where vehicle1to which the driving assistance apparatus and method of the present invention are applied is a tractor capable of towing trailer2by coupling trailer2to the tractor is described. However, the vehicle to which the present invention is applicable is not limited thereto and may be a vehicle such as a passenger car.

The present application is based on Japanese Patent Application (Japanese Patent Application No. 2020-33761) filed on Feb. 28, 2020, the entire content of which is incorporated herein by reference.

INDUSTRIAL APPLICABILITY

The driving assistance apparatus and the driving assistance method of the present disclosure are suitable for use as a driving assistance apparatus and a driving assistance method capable of reducing the possibility of collision even when a detector necessary for executing ACC fails during the execution of the ACC and normal ACC cannot be executed.

REFERENCE SIGNS LIST

1Vehicle2Trailer3Vehicle main-body portion10Driving system11Engine12Clutch13Transmission14Propeller shaft15Differential gear16Drive shaft17Wheel18Engine ECU19Motive power transmission ECU20Braking system21Service brake22Retarder23Exhaust brake24Brake ECU30Driving assistance apparatus31Inter-vehicle-distance detection section32ACC section33Abnormality detection section34Vehicle-stopping control section41ACC operation section43Accelerator-operation detection section44Brake-operation detection section50Information output section