Patent ID: 12208816

DETAILED DESCRIPTION OF EMBODIMENTS

An embodiment of the present disclosure will be described with reference to the accompanying drawings.

1. Overview

FIG.1is a conceptual diagram for describing an overview of a driver assistance system10applied to a vehicle1according to the present embodiment. The driver assistance system10performs driver assistance regarding driving of the vehicle1. For example, the driver assistance system10is installed in the vehicle1. Alternatively, at least part of the driver assistance system10may be included in a remote system external from the vehicle1, to remotely perform driver assistance regarding driving the vehicle1. That is to say, the driver assistance system10may be dispersedly disposed in the vehicle1and the remote system. The vehicle1may be subject to remote operation by a remote operator. In this case, the vehicle1and a remote operator terminal on the remote operator side communicate with each other, and exchange information necessary for remote operation. The driver assistance system10may be applied to the vehicle1that performs partially autonomous driving.

In the following description, a case in which a driver onboard the vehicle1drives the vehicle1will be considered. When remote operation is performed by a remote operator, the term “driver” shall be read as “remote operator”, and the term “display device installed in the vehicle1” shall be read as “display device of remote operator terminal on remote operator side”.

The driver assistance system10includes a display device30installed in the vehicle1. The driver assistance system10performs driver assistance for the driver driving the vehicle1, by displaying various types of information on the display device30. For example, the driver assistance system10displays the speed limit at the position where the vehicle1is traveling, on the display device30. Such speed limit information is useful for the driver of the vehicle1. The processing of displaying the speed limit on the display device30of the vehicle1will be hereinafter referred to as “speed limit display processing”.

The speed limit information is obtained, for example, from a speed limit traffic sign S0installed on the wayside of the road. A camera C for taking images of the situation around the vehicle1is installed in the vehicle1. The driver assistance system10acquires images around the vehicle1using the camera C. The driver assistance system10recognizes the speed limit traffic sign S0based on the acquired images. Further, the driver assistance system10recognizes (reads) the speed limit written on the speed limit traffic sign S0, based on the acquired images. The driver assistance system10then displays the speed limit, acquired from the speed limit traffic sign S0, on the display device30.

However, the speed limit traffic signs S0are not necessarily installed on the wayside of the road with high frequency. Also, in some situations, the camera C may not be able to correctly recognize the speed limit traffic sign S0.

Therefore, according to the present embodiment, “map information MAP” is also used in the speed limit display processing. Speed limits set in advance for the road are registered in the map information MAP. The speed limit registered in the map information MAP will be hereinafter referred to as “predetermined speed limit LM”. That is to say, the map information MAP indicates the position and the predetermined speed limit LM in correlation. In other words, the map information MAP gives the predetermined speed limit LM as a function of the position. Here, “position” is a concept including a section, a region, and so forth. In the map information MAP, the position and the road type may be correlated. Note that the map information MAP may be stored in a storage device of the vehicle1, or may be stored in a storage device of a map management system, externally from the vehicle1.

FIG.2is a conceptual diagram for describing speed limit display processing based on the map information MAP. The driver assistance system10reads the predetermined speed limit LM at the position at which the vehicle1is traveling, from the map information MAP. The driver assistance system10displays a predetermined speed limit LM read from the map information MAP on the display device30. A speed limit boundary BD is a position at which the predetermined speed limit LM changes. In many cases, when the road type changes, the predetermined speed limit LM also changes. However, changing of the predetermined speed limit LM is not limited to this. The driver assistance system10updates the predetermined speed limit LM to be displayed on the display device30in conjunction with the vehicle1passing the speed limit boundaries BD. For example, the driver assistance system10updates the predetermined speed limit LM displayed on the display device30immediately prior to or following the vehicle1passing the speed limit boundaries BD.

Using the map information MAP in this way enables displaying the predetermined speed limit LM even in sections in which no speed limit traffic signs S0are installed. Also, the predetermined speed limit LM can be displayed even when the camera C is unable to recognize the speed limit traffic sign S0.

However, there are also situations in which a temporary speed limit is set instead of the predetermined speed limit LM. A temporary speed limit that is not a predetermined speed limit LM will be hereinafter referred to as a “temporary speed limit LMtemp”. A section in which the temporary speed limit LMtemp is set will be hereinafter referred to as a “temporary speed limit section X1” (first section).

FIG.3is a conceptual diagram for describing examples of temporary speed limit sections X1. For example, the speed limit in road construction sections is generally set lower than the predetermined speed limit LM. The start of a road construction section is often indicated by a road construction sign. In some cases, a speed limit traffic sign indicating the temporary speed limit LMtemp that is applied to this road construction section is attached to the road construction sign.

As another example, there are cases in which the temporary speed limit LMtemp is variably set depending on weather conditions or time of the day. Such a temporary speed limit LMtemp is indicated, for example, by a variable electronic traffic sign of which the display can be changed. As another example, there also are cases in which a supplementary traffic sign indicating conditions of application of the temporary speed limit LMtemp is attached to the speed limit traffic sign.

The temporary speed limit LMtemp is not registered in the map information MAP. Accordingly, when the speed limit displayed on the display device30is updated based on the predetermined speed limit LM read from the map information MAP, an incorrect speed limit that is deviated from the actual state (temporary speed limit LMtemp) will be displayed.

FIG.4is a conceptual diagram for describing a comparative example. There is a temporary speed limit section X1ahead of the vehicle1. In the temporary speed limit section X1, there are speed limit boundaries BD at which the predetermined speed limit LM changes. In the case of the comparative example, when the vehicle1passes the speed limit boundaries BD, the speed limit displayed on the display device30is updated based on the map information MAP. However, the predetermined speed limit LM read from the map information MAP is different from the temporary speed limit LMtemp set for the temporary speed limit section X1. That is to say, an incorrect speed limit, which is deviated from the actual state (temporary speed limit LMtemp), will be displayed on the display device30. It is undesirable from the perspective of driver assistance that a speed limit deviated from the actual state (temporary speed limit LMtemp) would be displayed on the display device30.

Accordingly, the driver assistance system10according to the present embodiment is configured to suppress incorrect speed limits that are deviated from the actual state from being displayed on the display device30. More specifically, in the temporary speed limit section X1, even when the predetermined speed limit LM registered in the map information MAP changes, the driver assistance system10disables updating of the speed limit displayed on the display device30(based on the map information MAP). This processing will be hereinafter referred to as “display update disabling processing”.

FIG.5is a conceptual diagram for describing an example of the display update disabling processing. There is a temporary speed limit section X1ahead of the vehicle1. There is a first traffic sign S1, indicating the start of the temporary speed limit section X1, in the vicinity of the start point of the temporary speed limit section X1. The traffic signs illustrated inFIG.3are exemplified as the first traffic sign S1. The driver assistance system recognizes the start of the temporary speed limit section X1by recognizing the first traffic sign S1using the camera C. When the first traffic sign S1indicates a temporary speed limit LMtemp, the driver assistance system10may display the temporary speed limit LMtemp read from the first traffic sign S1on the display device30. The vehicle1passes the speed limit boundaries BD while traveling in the temporary speed limit section X1. That is to say, the predetermined speed limit LM changes while the vehicle1travels in the temporary speed limit section X1. Even in such a case, the driver assistance system10disables updating of the speed limit displayed on the display device30based on the map information MAP.

As described above, according to the present embodiment, even when the predetermined speed limit LM registered in the map information MAP changes in the temporary speed limit section X1in which the temporary speed limit LMtemp is set, the speed limit displayed on the display device30is not updated. Accordingly, an incorrect speed limit, which is deviated from the actual state (temporary speed limit LMtemp), can be suppressed from being displayed on the display device30.

The driver assistance system10according to the present embodiment will be described in further detail below.

2. Example of Driver Assistance System

2-1. Configuration Example

FIG.6is a block diagram illustrating a configuration example of the driver assistance system10according to the present embodiment. The driver assistance system10includes a sensor group20, the display device30, an alarm device40, a traveling device50, and a control device100.

The sensor group20is installed in the vehicle1. The sensor group20includes a recognition sensor21, a vehicle state sensor22, a position sensor23, and so forth.

The recognition sensor21recognizes (detects) the situation around the vehicle1. The recognition sensor21includes the camera C. The recognition sensor21may include a Light Imaging Detection and Ranging sensor (LIDAR sensor), a radar device, and so forth.

The vehicle state sensor22detects the state of the vehicle1. The vehicle state sensor22includes, for example, a speed sensor, an acceleration sensor, a yaw rate sensor, a steering angle sensor, and so forth.

The position sensor23detects the position and orientation of the vehicle1. Examples of the position sensor23include a Global Positioning System (GPS) sensor.

The display device30(display) is installed in the vehicle1, and displays various types of information. The display device30is installed at a position visible to the driver of the vehicle1. For example, the display device30is included in a meter panel. As another example, the display device30may be a head-up display (HUD).

The alarm device40is installed in the vehicle1, and outputs visual or audible alarms. For example, the alarm device40includes a display device. As another example, the alarm device40includes a speaker. The alarm device40and the display device may be the same device.

The traveling device50includes a steering device, a drive device, and a braking device. The steering device performs steering of wheels. Examples of the steering device include an electric power steering (EPS) device. The drive device is a power source that generates a drive force. Examples of the drive device include an engine, an electric motor, in-wheel motors, and so forth. The braking device generates a braking force.

The control device100controls the vehicle1. The control device100includes one or a plurality of processors110(hereinafter simply referred to as “processor110”) and one or a plurality of storage devices120(hereinafter simply referred to as “storage device120”). The processor110executes various types of processing. For example, the processor110includes a central processing unit (CPU). The storage device120stores various types of information. Examples of the storage device120include volatile memory, non-volatile memory, a hard disk drive (HDD), a solid state drive (SSD), and so forth. The control device100may include one or a plurality of electronic control units (ECUs). Part of the control device100may be an information processing device that is external from the vehicle1. In this case, the part of the control device100communicates with the vehicle1to remotely control the vehicle1.

A driver assistance program PROG is a computer program for controlling the vehicle1. Various types of processing are realized by the control device100, by the processor110executing the driver assistance program PROG. The driver assistance program PROG is stored in the storage device120. Alternatively, the driver assistance program PROG may be recorded in a computer-readable recording medium.

2-2. Driving Environment Information

The control device100acquires driving environment information200that indicates the driving environment of the vehicle1. The driving environment information200is stored in the storage device120.

FIG.7is a block diagram illustrating an example of the driving environment information200. The driving environment information200includes the map information MAP, a surrounding situation information210, a vehicle state information220, and a vehicle position information230.

The map information MAP contains a general navigation map. The map information MAP may show lane layouts and road profiles. The map information MAP may include position information of structures, traffic lights, traffic signs, and so forth. Further, predetermined speed limits LM are registered in the map information MAP. That is to say, the map information MAP indicates the position and the predetermined speed limit LM in correlation. In the map information MAP, the position and the road type may be correlated. The control device100acquires map information MAP for a necessary area from a map information base. The map information base may be stored in the storage device120, or may be stored in a map management system that is external from the vehicle1. In the case of the latter, the control device100communicates with the map management system to acquire the necessary map information MAP.

The surrounding situation information210is information that indicates the situation around the vehicle1. The control device100recognizes the situation around the vehicle1using the recognition sensor21, and acquires the surrounding situation information210. For example, the surrounding situation information210includes images IMG taken by the camera C. As another example, the surrounding situation information210includes point group information obtained by a LIDAR sensor.

The surrounding situation information210further includes object information about objects that are present around the vehicle1. Examples of objects include pedestrians, bicycles, other vehicles (such as vehicles traveling ahead, parked vehicles, and so forth), traffic demarcation lines, traffic signs, traffic lights, structures, and so forth. The object information indicates the relative position and relative speed of the objects with respect to the vehicle1. For example, the objects can be identified and the relative positions of the objects can be calculated, by analyzing images IMG obtained by the camera C. Also, the objects can be identified and the relative positions and the relative speeds of the objects can be acquired based on point group information obtained by a LIDAR sensor.

In particular, traffic sign information SGN is object information about traffic signs that are present around the vehicle1. Traffic signs include a general speed limit traffic sign S0(seeFIG.1) installed on the wayside of a road. Traffic signs also include a first traffic sign S1that indicates a start of a temporary speed limit section X1. Examples of the first traffic sign S1include a road construction sign indicating the start of a road construction section, a variable electronic traffic sign for changeably displaying the speed limit, a speed limit traffic sign to which is attached a supplementary traffic sign indicating the application conditions of the speed limit, and so forth (seeFIG.3). Traffic signs also include a second traffic sign that indicates an end of the temporary speed limit section X1. The traffic sign information SGN indicates the relative position and the type of traffic sign. The traffic sign information SGN may indicate the content of the traffic sign (speed limit or the like). The control device100acquires the traffic sign information SGN based on images IMG obtained by the camera C. For example, the control device100may use image-recognition artificial intelligence (AI) obtained by machine learning to recognize the traffic signs and the types and contents thereof in the images IMG.

The vehicle state information220is information that indicates the state of the vehicle1. The vehicle state information220includes vehicle speed, acceleration, yaw rate, steering angle, and so forth. The control device100acquires the vehicle state information220from the vehicle state sensor22.

The vehicle position information230is information that indicates the current position of the vehicle1. The control device100acquires the vehicle position information230from the results of detection by the position sensor23. Also, the control device100may acquire high-precision vehicle position information230through well-known self-position estimation processing (localization), in which the object information and the map information MAP are used.

2-3. Speed Limit Display Processing

The control device100performs speed limit display processing for displaying the speed limit on the display device30. For example, the control device100displays the speed limit obtained from the speed limit traffic sign S0on the display device30, based on the traffic sign information SGN. As another example, the control device100may display a temporary speed limit LMtemp obtained from the first traffic sign S1on the display device30, based on the traffic sign information SGN. Further, the control device100performs speed limit display processing based on the map information MAP. The speed limit display processing based on the map information MAP will be described again in Section3below.

2-4. Warning Processing

The control device100may warn the driver by the alarm device40. For example, the control device100compares the current speed of the vehicle1with the speed limit at the position at which the vehicle1is traveling. The current speed of vehicle1is obtained from the vehicle state information220. The speed limit is the speed limit displayed on the display device30, and is the predetermined speed limit LM or a temporary speed limit LMtemp. When the current speed of the vehicle1exceeds the speed limit, the control device100warns the driver by the alarm device40.

2-5. Vehicle Traveling Control

The control device100performs vehicle traveling control for controlling traveling of the vehicle1. The vehicle traveling control includes steering control, acceleration control, and deceleration control. The control device100performs vehicle traveling control by controlling the traveling device50(steering device, drive device, and braking device).

The control device100may perform adaptive speed control to control the speed of the vehicle1based on the speed limit. The speed limit here is the speed limit displayed on the display device30, and is the predetermined speed limit LM or a temporary speed limit LMtemp. For example, the control device100performs adaptive cruise control (ACC) based on the speed limit. As another example, the control device100may automatically control the vehicle speed so as to be no faster than the speed limit.

3. Processing Related to Speed Limit Display Processing

FIG.8is a flowchart showing processing for recognizing the temporary speed limit section X1. The flow ofFIG.8may be initiated when the vehicle1starts traveling.

In step S110, the control device100determines whether the first traffic sign S1is present around the vehicle1(typically ahead of the vehicle1), based on the traffic sign information SGN. The first traffic sign S1is a traffic sign indicating the start of the temporary speed limit section X1. For example, the first traffic sign S1is one of a road construction sign indicating the start of a road construction section, a variable electronic traffic sign for changeably displaying the speed limit, and a speed limit traffic sign to which is attached a supplementary traffic sign indicating the application conditions of the speed limit (seeFIG.3). As described above, the first traffic sign S1may be recognized based on images IMG obtained by the camera C installed in the vehicle1. When there is presence of the first traffic sign S1around the vehicle1(YES in step S110), the processing advances to step S120. Otherwise (NO in step S110), the processing ends for the current cycle.

In step S120, the control device100recognizes the section beyond the first traffic sign S1as being the temporary speed limit section X1. When the vehicle1is positioned in the section beyond the first traffic sign S1, the control device100determines that the vehicle1is in the temporary speed limit section X1. Thereafter, the processing advances to step S130.

In step S130, the control device100determines whether an ending condition is satisfied. The ending condition is a condition for determining the end of the temporary speed limit section X1.

A first example of the ending condition is that “the vehicle1has made a right turn or a left turn”. A right turn or a left turn of the vehicle1can be detected based on the vehicle position information230and the map information MAP. Alternatively, a right turn or a left turn of the vehicle1may be detected based on the vehicle state information220(vehicle speed, steering angle, or the like).

A second example of the ending condition is “recognizing a second traffic sign indicating ending of the temporary speed limit section X1”. The second traffic sign explicitly indicates the end (cancellation) of the temporary speed limit section X1. As described above, the second traffic sign may be recognized based on images IMG obtained by the camera C installed in the vehicle1.

A third example of the ending condition is that “the vehicle1has traveled a certain distance from the start of the temporary speed limit section X1”. Whether the vehicle1has traveled a certain distance can be determined based on the vehicle position information230and the map information MAP. Alternatively, whether the vehicle1has traveled a certain distance may be determined based on an integral of the vehicle speed.

The ending condition includes any one of the first to third examples described above. When the ending condition is not satisfied (NO in step S130), the processing returns to step S120. On the other hand, when the ending condition is satisfied (YES in step S130), the control device100determines that the temporary speed limit section X1has ended.

FIG.9is a flowchart showing processing related to speed limit display processing. The flow ofFIG.9may be initiated when the vehicle1starts traveling.

In step S140, the control device100determines presence or absence of a display update trigger.

A first example of a display update trigger is “the vehicle1passing a speed limit boundary BD”. A speed limit boundary BD is a position at which the predetermined speed limit LM changes. The vehicle1passing the speed limit boundary BD is detectable based on the vehicle position information230and the map information MAP.

A second example of a display update trigger is “recognizing the speed limit traffic sign S0” or “recognizing the first traffic sign S1”. As described above, the speed limit traffic sign S0and the first traffic sign S1may be recognized based on images IMG obtained by the camera C installed in the vehicle1.

When there is no display update trigger (NO in step S140), the processing ends for the current cycle. On the other hand, when there is a display update trigger (YES in step S140), the processing advances to step S150.

In step S150, the control device100determines whether the vehicle1is in the temporary speed limit section X1. Whether the vehicle1is in the temporary speed limit section X1is determined by the processing flow shown inFIG.8above.

When the vehicle1is not in the temporary speed limit section X1(NO in step S150), the processing advances to step S160. In step S160, the control device100reads the predetermined speed limit LM at the position at which the vehicle1is traveling, from the map information MAP. Then, in step S170, the control device100displays the predetermined speed limit LM read from the map information MAP on the display device30. That is to say, the control device100updates the speed limit displayed on the display device30, in response to the display update trigger.

On the other hand, when the vehicle1is in the temporary speed limit section X1(YES in step S150), the processing advances to step S180. In step S180, the control device100performs display update disabling processing. That is to say, the control device100disables updating of the speed limit to be displayed on the display device30(based on the map information MAP), even when there is a display update trigger.

Note that there are cases in which the first traffic sign S1indicating the start of the temporary speed limit section X1indicates a temporary speed limit LMtemp applied to that temporary speed limit section X1(seeFIG.3). In such a case, when the vehicle1is in the temporary speed limit section X1(YES in step S150), the control device100may display the temporary speed limit LMtemp acquired from the first traffic sign S1on the display device30.

When the first traffic sign S1does not indicate a temporary speed limit LMtemp, the control device100may maintain the speed limit displayed on the display device at the speed limit before reaching the temporary speed limit section X1. Alternatively, the control device100may temporarily turn off the speed limit display processing until the temporary speed limit section X1ends. In this case, an arrangement may be made in which the display device30does not display the speed limit, until the temporary speed limit section X1ends.

4. Effects

As described above, according to the present embodiment, even when the predetermined speed limit LM registered in the map information MAP changes in the temporary speed limit section X1in which the temporary speed limit LMtemp is set, the speed limit displayed on the display device30is not updated. Thus, an incorrect speed limit that is deviated from the actual state is suppressed from being displayed on the display device30.

Also, situations in which the speed of the vehicle1is erroneously determined to be exceeding the speed limit are suppressed. As a result, incorrect warnings are suppressed from being issued to the driver.

Further, in adaptive speed control based on the speed limit, setting of an incorrect vehicle speed is suppressed. As a result, the precision of adaptive speed control is improved.