Vehicle control method and vehicle control device

Abstract

A controller (30) of a vehicle control device (10) acquires a travel route for a host vehicle, detects a congestion section (85) on the travel route, acquires, for a plurality of traffic lights (82A, 82B) positioned on the travel route before the congestion section (85), a traffic light vehicle stop time pertaining to times during which the vehicle continuously stops at the signal lights, calculates an elimination time up until the congestion in the congestion section (85) is eliminated, sets deceleration sections (84A, 84B) starting from the traffic lights (82A, 82B) to a prescribed distance in the travel direction of the host vehicle, sets a target speed, for each of the deceleration sections (84A, 84B) and on the basis of the traffic light vehicle stop time, such that the arrival time of the host vehicle at the congestion section from the current position is set to be after the time when the congestion is eliminated, and performs vehicle speed control for the host vehicle in the deceleration sections (84A, 84B) at the set target speed.

Description

Vehicle control method and vehicle control device

[0001] The present invention relates to a vehicle control method and a vehicle control device.

[0002] Conventionally, a vehicle control method and a vehicle control device are known that control the travel of an autonomous vehicle so as to alleviate traffic congestion (see, for example, Patent Document 1). In Patent Document 1, when a factor causing traffic congestion exists, a point where the factor causing traffic congestion is generated is detected, and the autonomous vehicle is decelerated so that the deceleration amount decreases as the distance from the factor causing traffic congestion increases.

[0003] JP 2009-151562 A

[0004] However, if the speed of an autonomous vehicle is reduced only based on the distance to the point where the congestion factor occurs, new congestion may occur at intersections where the red light lasts for a long time, or the vehicle speed may not be reduced sufficiently at intersections where the red light lasts for a short time, causing vehicles to flow into the congested section and increasing the number of vehicles stopped in the congested section.

[0005] An object of the present invention is to provide a vehicle control method and a vehicle control device that can alleviate traffic congestion.

[0006] In the present invention, a computer detects a congested section on the vehicle's travel route, obtains the traffic light stop times, which indicate the duration of time the vehicle will be stopped, for multiple traffic lights located along the travel route, and calculates the time required for the congestion in the congested section to be resolved. The computer also sets multiple deceleration sections, each starting from a traffic light, between the vehicle's current position and the congested section, and calculates a target speed for each deceleration section. The target speed for each deceleration section is set based on the traffic light stop times of the traffic lights that are the starting points of each deceleration section, so that if the vehicle travels through the deceleration section at the target speed, the time required to reach the congested section will be a time after the resolution time. The computer then controls the vehicle's speed so that the vehicle travels through the deceleration section at the set target speed.

[0007] This allows for the target speed to be set based on the stop time at each traffic light up to the congested section, thereby preventing vehicles from entering the congested section and preventing new congestion from occurring before reaching the congested section, thereby helping to alleviate congestion.

[0008] The present disclosure relates to a vehicle control device and a vehicle control method for controlling a vehicle, and is a block diagram showing a schematic configuration of the vehicle control device mounted on a vehicle according to an embodiment of the present disclosure. The present disclosure relates to a vehicle control device and a vehicle control method for controlling a vehicle according to an embodiment of the present disclosure. The present disclosure relates to a vehicle control device and a vehicle control method for controlling a vehicle according to an embodiment of the present disclosure.

[0009] An embodiment of the present disclosure will be described below. Fig. 1 is a block diagram showing a schematic configuration of a vehicle control device 10 mounted on a vehicle (host vehicle) according to this embodiment. The vehicle control device 10 mounted on the vehicle according to this embodiment includes a communication unit 11, a sensor group 12, a vehicle drive mechanism 20, and a controller 30. In this embodiment, an autonomous vehicle that performs autonomous driving by controlling the vehicle drive mechanism 20 under the control of the controller 30 is exemplified as the vehicle.

[0010] The communication unit 11 receives various types of information from a predetermined external device 40 via a predetermined wireless communication line such as an Internet line. Examples of the information received from the external device 40 include various types of road traffic information such as information about congested sections on roads and information about traffic lights arranged on roads.

[0011] The sensor group 12 measures various sensor information related to the traveling of the host vehicle. The sensor group 12 includes a position detection sensor 121, a surroundings detection sensor 122, an imaging camera 123, a speed sensor 124, and the like. The position detection sensor 121 may be, for example, a receiver that receives satellite signals from a Global Navigation Satellite System (GNSS) to determine the current position, and detects the current position of the host vehicle. The surroundings detection sensor 122 detects surrounding objects. The surroundings detection sensor 122 may use various types of sensors, such as laser radar, millimeter-wave radar, and ultrasonic radar, and a combination of these may also be used. The imaging camera 123 captures images of the surroundings of the host vehicle to obtain captured images. The speed sensor 124 measures the wheel speed of the host vehicle. Note that, although the position detection sensor 121, the surroundings detection sensor 122, the imaging camera 123, and the speed sensor 124 are exemplified as the sensor group 12, sensors that detect other information may also be provided. For example, an acceleration sensor for measuring acceleration, a yaw rate sensor for detecting the yaw rate of the host vehicle, and the like may be further provided.

[0012] The vehicle drive mechanism 20 has an engine actuator 21, a brake hydraulic actuator 22, and a steering angle actuator 23. The engine actuator 21 is an actuator that controls the engine drive force by receiving a drive control command value based on a target speed from the controller 30. In the case of a hybrid vehicle, an engine actuator and a motor actuator may be used, and in the case of an electric vehicle, a motor actuator may be used.

[0013] The brake hydraulic actuator 22 controls the brake hydraulic braking force by receiving a braking control command value based on the target speed from the controller 30. Note that in the case of an electric vehicle not equipped with a hydraulic booster, an electric booster may be used. The steering angle actuator 23 is a steering angle control motor that controls the steering angle of the steered wheels by receiving a steering angle control command value from the controller 30.

[0014] 2 is a diagram showing a schematic configuration of the controller 30 according to this embodiment and a functional configuration of the processor 32. The controller 30 controls the autonomous driving of the host vehicle. The controller 30 is a computer including a memory 31 as a recording device for recording various information, and a processor 32 including an arithmetic circuit such as a CPU (Central Processing Unit).

[0015] The memory 31 stores various information and programs for controlling the autonomous driving of the vehicle. An example of the various information stored in the memory 31 is map information. The map information is information in which latitude and longitude are associated with points on a map. The map information includes road information defined by nodes and links connecting the nodes. The road information may be recorded in association with various information such as the road width and number of lanes of the road, priority relative to intersecting roads, and speed limits. The nodes or links included in the road information may also include traffic light information related to traffic lights installed at intersections, for example. The traffic light information includes the location of the traffic light and the traffic light stop time. The traffic light stop time in the present disclosure is information related to the duration a vehicle remains stopped at a traffic light, and examples thereof include the duration a traffic light remains red or the duty ratio for the duration a traffic light remains red. Here, "the time the traffic light remains red" does not necessarily mean the exact time from when the traffic light changes color to when it changes color to another color. For example, it may be the average or maximum time a vehicle remains stopped at a traffic light. In this case, the time at the traffic light may include the time (start delay) that a driver of a vehicle takes to check the change in color of the traffic light and the surrounding traffic conditions and actually start the vehicle. Furthermore, the time duty ratio for the time the traffic light remains red may be, for example, the ratio of the time the traffic light remains red to the time the traffic light remains other than red, or the ratio of the time the traffic light remains red to the time it takes for the traffic light to cycle through one color cycle.

[0016] The map information recorded in the memory 31 may be only a map within a predetermined distance range centered on the current location of the vehicle, or only a map within a predetermined distance range centered on the route from the current location of the vehicle to the destination. In this case, new map information may be downloaded from the external device 40 as needed depending on the current location of the vehicle. Furthermore, the map information recorded in the memory 31 may be updated by periodically downloading map information from the external device 40.

[0017] 2, the processor 32 functions as a route acquisition unit 321, a congested section detection unit 322, a traffic light stop time acquisition unit 323, a resolution time acquisition unit 324, a section setting unit 325, a target speed setting unit 326, a vehicle control unit 327, etc. Note that, here, an example is shown in which the processor 32 executes a program to realize the respective functional configurations of the route acquisition unit 321, the congested section detection unit 322, the traffic light stop time acquisition unit 323, the resolution time acquisition unit 324, the section setting unit 325, the target speed setting unit 326, and the vehicle control unit 327, but some or all of these may be realized by individual hardware configurations.

[0018] The route acquisition unit 321 acquires a driving route of the vehicle. Specifically, the route acquisition unit 321 calculates a driving route on a map based on a destination input by a user (e.g., the driver of the vehicle) and the current position of the vehicle detected by the position detection sensor 121. The driving route may be set by a navigation device and acquired from the navigation device. The navigation device may be a navigation device mounted on the vehicle, or may be a mobile terminal such as a smartphone connected to the vehicle control device 10 so as to be able to communicate with the vehicle control device 10.

[0019] The congested section detection unit 322 detects congested sections on the travel route based on road traffic information acquired from the external device 40 via the communication unit 11. Examples of road traffic information include traffic congestion information received from VICS (registered trademark) or a map server that provides a predetermined map guidance service. When map information is received from the external device 40, the traffic congestion information may be received together with the map information.

[0020] The traffic light stop time acquisition unit 323 detects traffic lights present on the travel route and acquires the traffic light stop time at each traffic light.

[0021] The method by which the traffic light stop time acquisition unit 323 detects the traffic light stop time is not particularly limited. For example, the traffic light stop time acquisition unit 323 may acquire the traffic light stop times corresponding to traffic lights on the travel route from an external device 40 that records the traffic light stop times of each traffic light. In this case, the external device 40 may record traffic light information that records the location of each traffic light and the traffic light stop time of the traffic light. An example of the external device 40 is the map server described above that records map information. Alternatively, as described above, the map information recorded in the memory 31 may include traffic light information including the traffic light stop time. In this case, the traffic light stop time acquisition unit 323 may read the traffic light information corresponding to each detected traffic light from the memory 31.

[0022] As another example, the traffic light stop time acquisition unit 323 may calculate the traffic light stop time based on the type of road on which the host vehicle is traveling (host vehicle travel lane) and the type of road (intersection) that intersects the host vehicle travel lane. For example, if the traffic light stop time is determined based on either the ratio of the time the traffic light is red to the time the traffic light is not red, or the ratio of the time the traffic light is red to the time it takes for the traffic light to cycle through one color, the traffic light stop time may be calculated based on the ratio of the road width of the host vehicle travel lane to the road width of the intersection. In other words, roads with larger road widths have shorter traffic light stop times than intersections with smaller road widths. Therefore, the traffic light stop time can be calculated based on the ratio of the road widths of the host vehicle travel lane and the intersection. Alternatively, the traffic light stop time may be calculated based on the priority of the host vehicle travel lane and the priority of the intersection, or based on the speed limit of the host vehicle travel lane and the speed limit of the intersection.

[0023] As yet another example, the traffic light stop time acquisition unit 323 may store and accumulate driving information of the host vehicle as a driving history in the memory 31, and calculate the traffic light stop time for each traffic light based on the accumulated driving history. For example, when the host vehicle stops at a traffic light, the stop time is recorded as driving information. In this case, the average time the host vehicle stops at a traffic light is calculated as the traffic light stop time for that traffic light. Alternatively, the maximum stop time when the host vehicle stops at a traffic light may be calculated as the traffic light stop time.

[0024] The resolution time acquisition unit 324 calculates a resolution time that is predicted to clear the congestion in the detected congested section. In the present disclosure, as an example, the resolution time is the time until the rearmost vehicle in the congested section starts moving. In this case, the resolution time acquisition unit 324 calculates the red duration T Ｒ０ , the departure delay time T ＣＤ , the number of vehicles stopped in the congestion section n is used to calculate the clearance time T Ｏ Calculate T Ｏ =T Ｒ０ + (T ＣＤ ×n) ... (1)

[0025] The red duration T of a traffic light in a congested sectionＲ０ If there are multiple traffic lights in the congestion section, the maximum red duration of these traffic lights is used as the red duration T Ｒ０ Generally, traffic congestion often occurs starting from a traffic light that has a long red light duration. Ｒ０ means the time until the vehicle at the head of the congested section starts moving. Ｒ０ The time that the traffic light remains red is used instead of the time duty ratio. When the time that the traffic light remains red is acquired as the traffic light stop time, the acquired time can be directly applied to equation (1). On the other hand, when the time duty ratio is acquired as the traffic light stop time, the time duty ratio is multiplied by a predetermined reference time to obtain the red light duration time T Ｒ０ The reference time may be set for each traffic light and recorded in the traffic light information, or may be a preset fixed value.

[0026] Departure delay time T for each vehicle ＣＤ is the average delay time from when a stopped vehicle in a congested section confirms that a preceding vehicle has started to move until the vehicle itself (stopped vehicle) starts to move, and is stored in advance in the memory 31, for example. Note that a plurality of start delay times T ＣＤ is stored in the memory 31, and the start delay time T ＣＤ may be read from the memory 31.

[0027] The number n of vehicles stopped in the congestion section is calculated based on the length of the congestion section and the estimated inter-vehicle distance between each vehicle, for example, by the formula: number n = (length of congestion section) / (estimated inter-vehicle distance). The length of the congestion section can be received by the congestion section detection unit 322 simultaneously with receiving the congestion section information. The estimated inter-vehicle distance is the distance between multiple stopped vehicles stopped in the congestion section. For example, if one vehicle stopped in the congestion section is designated as a first stopped vehicle and a second stopped vehicle is stopped behind the first stopped vehicle, the estimated inter-vehicle distance is the distance from the front end of the first stopped vehicle to the front end of the second stopped vehicle. The estimated inter-vehicle distance is stored in memory 31 in advance. Note that multiple estimated inter-vehicle distances corresponding to multiple conditions, such as for each road and each time period, may be stored in memory 31, and the estimated inter-vehicle distance corresponding to the conditions of the congestion section may be read from memory 31.

[0028] When a congested section is present on the travel route, the section setting unit 325 sets a deceleration section and a deceleration-prohibited section between the current position of the vehicle and the congested section. That is, the section setting unit 325 functions as the deceleration section setting unit of the present disclosure. Specifically, the section setting unit 325 detects, as the first traffic light, a traffic light existing between the current position of the vehicle and the congested section, whose stop time is equal to or greater than a predetermined value. Here, when the time during which the traffic light remains red is acquired as the stop time, a time threshold value (e.g., 90 seconds) is used as the predetermined value. Therefore, the section setting unit 325 detects, as the first traffic light, a traffic light whose recorded time as the stop time is equal to or greater than the time threshold value. On the other hand, when the time duty ratio is acquired as the stop time, a ratio threshold value is used as the predetermined value. If the traffic light stop time is defined as the ratio of the time the traffic light remains red to the time it remains other than red, the threshold value may be set to, for example, 1.0. If the traffic light stop time is defined as the ratio of the time the traffic light remains red to the time it takes for the traffic light to change colors, the threshold value may be set to, for example, 0.5.

[0029] The section setting unit 325 then sets a predetermined section starting from the first traffic light along the traveling direction of the host vehicle as a deceleration-prohibited section. For example, the section setting unit 325 sets the section from the first traffic light to a predetermined number of traffic lights in the traveling direction of the host vehicle (e.g., the section from the first traffic light to the next traffic light) as a deceleration-prohibited section. Note that the predetermined number may be set appropriately depending on the distance from the first traffic light to each of the following traffic lights. For example, if the distance between the first traffic light and the next traffic light is equal to or less than a predetermined threshold, the section from the first traffic light to the next traffic light may be set as a deceleration-prohibited section, whereas if the distance from the first traffic light to the next traffic light is equal to or less than the predetermined threshold, the section from the first traffic light to the next traffic light may be set as a deceleration-prohibited section.

[0030] Alternatively, the section setting unit 325 may calculate the signal density (the number of traffic lights per unit distance) by dividing the number of traffic lights included between the first traffic light and a predetermined point ahead in the direction of travel of the vehicle by the distance from the first traffic light to the predetermined point, and set the section where the signal density is equal to or greater than a predetermined value as a deceleration-prohibited section. It is preferable to use the locations of traffic lights ahead of the first traffic light as the predetermined point. In this case, it is preferable that the traffic lights included between the first traffic light and the predetermined point have a signal stop time shorter than the signal stop time of the first traffic light. In other words, if there are consecutive traffic lights with signal stop times shorter than the first traffic light following the first traffic light within a short distance, the section including these traffic lights is set as a deceleration-prohibited section.

[0031] On the other hand, the section setting unit 325 detects a traffic light where the stop time is less than a predetermined value as a second traffic light, and sets a predetermined section along the traveling direction of the host vehicle from the second traffic light as a deceleration section. In other words, the section setting unit 325 sets a section that has not been set as a deceleration prohibited section as a deceleration section.

[0032] The target speed setting unit 326 sets a target speed in each deceleration section. The target speed in the deceleration prohibited section is set to a speed that complies with standards and manners, based on the legal speed of the road on which the host vehicle is traveling, or the speeds of preceding vehicles traveling in the host vehicle and other surrounding vehicles. The target speed setting unit 326 calculates the clearance time T Ｏ Thereafter, the target speed is set so that the vehicle reaches the congested section.

[0033] 3 is a diagram showing an example of the target speed for each section set in this embodiment. For example, the target speed setting unit 326 calculates the time it takes for the vehicle to reach the end of the congested section 85 at the legal speed without stopping at any traffic lights as the tentative arrival time. The target speed setting unit 326 also calculates the time it takes for the vehicle to reach the end of the congested section 85 at the legal speed without stopping at any traffic lights as the tentative arrival time. Ｏ The difference between the estimated arrival time and the estimated arrival time is the required delay time T Ｄ Furthermore, the target speed setting unit 326 calculates the required delay time T Ｄ For example, each deceleration section is divided into a plurality of groups according to the time spent stopping at a traffic light, and points are allocated to each group as the time spent stopping at a traffic light becomes shorter. Ｄ is allocated to each deceleration section.

[0034] An example will be described using FIG. 3 . In FIG. 3 , the "long," "medium," and "short" symbols written in the upper right corner of traffic lights 81, 82A, and 82B indicate the stop times of the traffic lights 81, 82A, and 82B, respectively. A traffic light corresponding to a "long" stop time is the first traffic light 81, whose stop time is equal to or greater than a first threshold (predetermined value). In this embodiment, the section from the first traffic light 81 to the next traffic light 82A is set as a deceleration-prohibited section 83. A traffic light corresponding to a "medium" stop time is the second traffic light 82A, whose stop time is less than the first threshold and equal to or greater than a second time threshold. The section from the second traffic light 82A to the next traffic light is set as a deceleration section 84A. A traffic light corresponding to a "short" stop time is the second traffic light 82B, whose stop time is less than the second time threshold. The section from the second traffic light 82B to the next traffic light is set as a deceleration section 84B. Here, the deceleration section 84A where the traffic light stop time is "medium" is assigned 1 point, and the deceleration section 84B where the traffic light stop time is "short" is assigned 2 points. The total number of points for all deceleration sections 84A and 84B up to the congestion section 85 is set to N, and the number of points is set to P. For each deceleration section 84A and 84B, P x T Ｄ For example, the target delay time for the "medium" deceleration section 84A is T Ｄ / N, and the target delay time for the "short" deceleration section 84A is 2×T Ｄ / N.

[0035] The target speed setting unit 326 then calculates the target travel time for each deceleration section 84A, 84B by subtracting the allocated target delay time from the time it would take to travel through each deceleration section 84A, 84B at the legal speed. The target speed setting unit 326 then calculates the target speed for each deceleration section 84A, 84B based on the distance (section distance) of each deceleration section 84A, 84B and the target travel time. If the calculated target speed is equal to or less than a preset lower limit, the target speed for that deceleration section 84A, 84B is set to the lower limit. The lower limit can be set to a speed that complies with standards and manners based on the speed limit of the road on which the vehicle is traveling or the speeds of other vehicles traveling around the vehicle.

[0036] When the target speed of the deceleration section is set to the lower limit value, the target speed setting unit 326 further reduces the target speed of the other deceleration sections so that the arrival time to the congestion section 85 is shorter than the clearance time T Ｏ For example, if the target speed for a certain deceleration section is below the lower limit, the target speed for that deceleration section is set to the lower limit, and the difference between the time required to travel through that deceleration section at the lower limit and the previously calculated target travel time is calculated. The calculated difference is then equally distributed to the other deceleration sections, or distributed based on the time spent stopping at traffic lights, and the target speeds for the other deceleration sections are recalculated. Note that, as described above, the target speed setting unit 326 sets the target speed for deceleration-prohibited sections to the legal speed.

[0037] The vehicle control unit 327 outputs a control command related to automatic driving to the vehicle drive mechanism 20 based on the target speed set by the target speed setting unit 326. As a result, the engine actuator 21, the brake hydraulic actuator 22, and the steering angle actuator 23 of the vehicle drive mechanism 20 cause the host vehicle to travel at the legal speed in the deceleration prohibited section, and at the set target speed in the deceleration section.

[0038] [Configuration of External Device 40] The external device 40 is a computer capable of communicating with vehicles equipped with the vehicle control device 10 via, for example, an Internet line, and transmits various information to each vehicle. Specifically, the external device 40 transmits map information, road traffic information, traffic light information (traffic light stop times), etc. in response to requests from each vehicle. Note that while FIG. 1 illustrates a single external device 40, the external device 40 may be divided into multiple devices depending on, for example, the distribution area or the content of the information to be transmitted. For example, the external device 40 may include a map distribution device that transmits map information, a traffic information distribution device that transmits road traffic information, and a traffic light information distribution device that transmits traffic light information, each of which is independently provided. Furthermore, these external devices 40 may be configured as a cloud server constructed by connecting multiple computers via a network. Note that in this embodiment, a configuration in which a single external device 40 distributes map information, road traffic information, and traffic light information will be described as an example.

[0039] The external device 40 does not need to distribute all of the map information, road traffic information, and traffic light information, but only needs to distribute corresponding information in response to a request signal from the vehicle as needed. For example, if map information is stored in the memory 31 installed in the vehicle, the external device 40 does not need to distribute the map information, and only needs to distribute the map information when, for example, a map update request is received from the vehicle. The same applies to traffic light information; if traffic light information is associated with map information in the vehicle's memory 31 or if traffic light stop times are calculated based on road categories, there is no need to distribute the traffic light information. If map information is stored in the memory 31 of each vehicle and distribution of traffic light information is not necessary, the external device 40 only needs to distribute at least road traffic information related to congestion on the road.

[0040] As described above, the external device 40 is a computer, and is configured to include a memory for recording various types of information and programs, and a processor for processing various types of information by reading and executing programs.

[0041] Examples of various information recorded in the memory of the external device 40 include map information and traffic light information. The map information is information that associates latitude and longitude with points on a map, and is similar to the map information recorded in the memory 31 of each vehicle. The traffic light information is information about each traffic light located at an intersection or the like on the map, and at least the traffic light stop time is recorded.

[0042] Furthermore, when recording traffic light information in external device 40, external device 40 may acquire driving information from each vehicle, store the information as a driving history, calculate traffic light stop times based on the driving history, and record the calculated traffic light stop times in the traffic light information. In this case, traffic light stop times can be recorded with higher accuracy based on driving information from multiple vehicles. In other words, traffic light stop times can be generated that take into account the delay time from when the traffic light changes from red to another color until the vehicle starts moving.

[0043] The external device 40 constantly receives traffic condition information from monitoring sensors and monitoring cameras that monitor traffic conditions on roads via a communication line such as a dedicated line or the Internet. The traffic conditions include the speed of vehicles traveling on the road, the number of vehicles passing per unit time, and the stopping time of vehicles stopped on the road. Based on the received traffic condition information, the external device 40 then detects congested sections on the road in real time and distributes the detected sections as road traffic information to each vehicle.

[0044] [Vehicle Control Method] Next, the vehicle control method of this embodiment will be described. Fig. 4 is a flowchart showing the vehicle control method of this embodiment. In this embodiment, when a destination is input by a user operation and a command is input requesting a search for a driving route from the current position of the vehicle to the destination, the route acquisition unit 321 acquires (searches for) a driving route from the current position of the vehicle detected by the position detection sensor 121 to the destination based on map information (step S1).

[0045] In addition, when a command requesting that the vehicle be driven automatically is input by user operation, the vehicle control unit 327 outputs a control command to the vehicle drive mechanism 20 to drive the vehicle along the driving route, and starts the vehicle driving automatically (step S2).

[0046] In this autonomous driving process, the congested section detection unit 322 detects a congested section occurring ahead of the vehicle on the driving route (step S3). Specifically, the congested section detection unit 322 transmits the current position of the vehicle and the driving route to the external device 40, and requests the congested section on the driving route. In this way, the congested section detection unit 322 acquires the congested section on the driving route from the external device 40. The congested section includes the position of the starting point of the congested section and the length of the congested section.

[0047] Next, the congested section detection unit 322 determines whether there is a congested section on the travel route (step S4). If the determination in step S4 is NO, the target speed is not set taking congestion into account, but is set as a normal target speed (step S5). In other words, the target speed setting unit 326 sets the target speed on the travel route to a speed that complies with standards and manners, based on the legal speed of the road on which the vehicle is traveling, or the speeds of vehicles traveling ahead of the vehicle and other vehicles around the vehicle.

[0048] On the other hand, if step S4 returns YES, the traffic light stop time acquisition unit 323 detects each traffic light between the current location and the congested section and acquires the traffic light stop time of each detected traffic light (step S6). As described above, various methods can be used to acquire the traffic light stop time. If traffic light information including traffic light stop times is recorded in the memory 31 along with map information, the traffic light stop time can be acquired from the memory 31. When acquiring the traffic light stop time from the external device 40, a request for transmitting traffic light stop time and the position information of the corresponding traffic light are transmitted to the external device 40, and the request is received from the external device 40. When receiving the request from the external device 40, the traffic light stop time for the traffic lights between the current location and the congested section may also be received in step S3, along with the congested section. Alternatively, the traffic light stop time acquisition unit 323 may calculate the traffic light stop time based on differences in road type, road width, and speed limit between the vehicle's path and the intersection. In this case, since the time duty ratio is calculated as the traffic light stop time, it may be converted into time units by multiplying the time duty ratio by a predetermined reference time, for example.

[0049] Next, the resolution time acquisition unit 324 acquires a resolution time that is predicted to be required for the congestion in the congested section to be resolved (step S7). In step S7, the resolution time acquisition unit 324 may calculate the resolution time using, for example, the above-mentioned formula (1), or may acquire the resolution time of the congested section from the external device 40.

[0050] Next, the section setting unit 325 sets deceleration-prohibited sections and deceleration sections on the travel route from the current location to the congested section based on the stop time at each traffic light from the current location of the vehicle to the congested section (step S8). Specifically, the section setting unit 325 first detects a first traffic light from each traffic light from the current location to the congested section where the stop time is equal to or greater than a predetermined value, and sets the deceleration-prohibited section in a predetermined section in the direction of travel of the vehicle, starting from the first traffic light. As described above, the deceleration-prohibited section may be a section from the first traffic light to a predetermined number of traffic lights, or a section where the signal density is equal to or greater than a predetermined value. Furthermore, the section setting unit 325 detects a traffic light where the stop time is less than a predetermined value as a second traffic light, and sets the sections from the second traffic light to the next traffic light ahead in the direction of travel of the vehicle as deceleration sections.

[0051] Next, the target speed setting unit 326 sets a target speed for each of the deceleration prohibition sections and the deceleration section (step S9). At this time, the target speed setting unit 326 sets the legal speed for the deceleration prohibition section. Furthermore, the target speed setting unit 326 calculates the target speed for each deceleration section based on the traffic light stop time of the second traffic light. As described above, the target speed is calculated by, for example, calculating the provisional arrival time for the section from the current position to the congested section when traveling at the legal speed without stopping at each traffic light. Furthermore, the target speed setting unit 326 calculates the required delay time T , which is the difference between the provisional arrival time and the resolution time calculated in step S7. Ｄ Calculate the required delay time T Ｄ The target running time for each deceleration section is calculated by allocating the time to each deceleration section based on the stop time at the traffic light. The target speed for each deceleration section is then calculated based on the section distance and the target running time for each deceleration section.

[0052] After this, the vehicle control unit 327 outputs a control command related to automated driving to the vehicle drive mechanism 20 based on the target speed set in step S5 or the target speed set in step S9, thereby controlling the automated driving speed of the host vehicle in each section (step S10). As a result, if no congested section is detected, the host vehicle is automatically driven at the legal speed. If a congested section is detected, the host vehicle is automatically driven so as to decelerate in each deceleration section so that the host vehicle will arrive at the congested section after the congestion in the congested section has cleared. Furthermore, the detection of congested sections in step S3 is performed periodically. As a result, the above process is performed based on the latest congestion information, and the target speed is updated as appropriate. Therefore, even if it is determined that there is no congested section and the host vehicle is traveling at the normal legal speed, if a new congested section is detected, a new target speed is immediately set, thereby preventing vehicles from entering the congested section.

[0053] As a result, it is possible to prevent the host vehicle from entering the congestion in the congested section, thereby facilitating the alleviation of the congestion. By installing the vehicle control device 10 of this embodiment in many vehicles traveling on the road, the number of vehicles entering the congestion can be significantly reduced, further facilitating the alleviation of the congestion. Furthermore, by preventing vehicles from entering an already congested congested section, the inconvenience of an increased congestion distance can be prevented. Furthermore, if the host vehicle slows down after passing a first traffic light with a short stop time, when the first traffic light changes color to red, many following vehicles traveling behind the host vehicle are likely to stop at the first traffic light, which could result in a new congestion. However, in this embodiment, by setting a no-deceleration section after the first traffic light, it is possible to prevent the occurrence of a new congestion near the first traffic light.

[0054] [Effects of the Present Embodiment] In the vehicle control device 10 of the present embodiment, the processor 32 of the controller 30 reads and executes the programs recorded in the memory 31, thereby functioning as a route acquisition unit 321, a congested section detection unit 322, a traffic light stop time acquisition unit 323, a resolution time acquisition unit 324, a section setting unit 325, a target speed setting unit 326, and a vehicle control unit 327. The route acquisition unit 321 acquires the driving route of the vehicle. The congested section detection unit 322 detects congested sections on the driving route. The traffic light stop time acquisition unit 323 acquires traffic light stop times for multiple traffic lights arranged on the driving route. The resolution time acquisition unit 324 calculates the resolution time T until congestion in the congested section is resolved. Ｏ The section setting unit 325 sets a plurality of deceleration sections, each having a predetermined distance in the direction of travel of the vehicle, between the current position of the vehicle and the congestion section, starting from a traffic light (second traffic light). The target speed setting unit 326 calculates the resolution time T Ｏ The target speed for each deceleration section is set so that the host vehicle will subsequently reach the congestion section. The vehicle control unit 327 then controls the vehicle speed of the host vehicle so that the host vehicle travels through the deceleration section at the set target speed.

[0055] As a result, the vehicle speed is controlled in each deceleration section so that the vehicle reaches the congested section after the time when the congested section is resolved, and the inflow of the vehicle into the congested section can be suppressed, thereby easing the congestion. By installing the vehicle control device 10 of the present disclosure in multiple vehicles traveling on a road, the number of vehicles that enter the congested section can be significantly reduced, and congestion can be more effectively alleviated.

[0056] In this embodiment, the target speed setting unit 326 reduces the target speed when the stop time of the second signal that is the starting point of the deceleration section is shorter (the time the vehicle stops at the traffic light is shorter) compared to when the stop time of the second signal that is the starting point of the deceleration section is longer. Traffic lights where the continuous red light stays red for a short period of time and the time when the light is not red is longer are less likely to cause congestion, even if the target speed is low. In contrast, traffic lights where the continuous red light stays red for a long period of time are more likely to cause new congestion when following vehicles stop at the traffic light. In this embodiment, as described above, the shorter the stop time of the second signal, the smaller the target speed, which prevents vehicles from entering the congestion section, and the longer the stop time of the second signal, the larger the target speed, which prevents new congestion.

[0057] In this embodiment, the resolution time acquisition unit 324 calculates the time required to travel from the current position to the end of the congested section at the legal speed as the resolution time T Ｏ Then, the target speed setting unit 326 calculates the difference between the required time and the resolution time as the required delay time T Ｄ The required delay time T Ｄ is distributed to each deceleration section based on the traffic light stop time, and the target delay time is set. Then, the target speed in each deceleration section is set based on the deceleration amount corresponding to the distributed target delay time. Ｏ A target delay time can be set for each deceleration section so that the vehicle can reach the congested section later, and a target speed corresponding to the target delay time can be set. By setting such a target speed, the vehicle does not decelerate too much in some sections or not decelerate enough in other sections. Therefore, the occurrence of new congestion can be suppressed while easing congestion in the congested section.

[0058] In this embodiment, the resolution time acquisition unit 324 acquires the resolution time T Ｏ The time that the traffic lights in the congested section are stopped (red duration T Ｒ０ ) and the departure delay time T ＣＤBased on the number n of stopped vehicles in the congested section, the time until the last vehicle starts moving is calculated using equation (1). Ｏ By setting the target speed for each deceleration section as described below, the vehicle can be controlled so that the vehicle can reach the congested section when the congestion in the congested section is resolved, thereby facilitating the alleviation of congestion in the congested section.

[0059] In this embodiment, when a congestion section includes multiple traffic lights, the resolution time acquisition unit 324 calculates the resolution time T Ｏ The traffic light with the maximum stop time is the time when a vehicle stops at the traffic light and the waiting time for the signal is the longest. Ｒ０ By using a larger resolution time T Ｏ can be calculated, and such a resolution time T Ｏ By setting the target speed in each deceleration section so that the vehicle will reach the congested section after that, the possibility of the vehicle entering the congestion can be further reduced, and congestion can be alleviated.

[0060] In this embodiment, the section setting unit 325 detects a traffic light where the stop time at the traffic light is equal to or longer than a predetermined value as a first traffic light, and further sets a no-deceleration section starting from the first traffic light. The target speed setting unit 326 then sets the target speed for the no-deceleration section to the legal speed. As a result, deceleration is prohibited in the no-deceleration section beyond the first traffic light where the stop time at the traffic light is long, and the target speed is set to the normal legal speed. When a vehicle stops at the first traffic light, the stop time becomes long. If the target speed for the vehicle in the section beyond the first traffic light is set lower than the normal speed (legal speed), the number of vehicles stopping at the first traffic light may increase, potentially causing new congestion. In contrast, in this embodiment, the target speed is set to the legal speed in the no-deceleration section starting from the first traffic light, thereby preventing congestion at the first traffic light.

[0061] In this embodiment, the section setting unit 325 sets the deceleration-prohibited section as a section that starts from a first traffic light where the traffic light stop time is equal to or longer than a predetermined value and extends to a predetermined number of traffic lights in the direction of travel of the host vehicle. Even if a deceleration-prohibited section is set starting from the first traffic light, if the section distance is short, the possibility of a new traffic jam occurring cannot be sufficiently reduced. In contrast, in this embodiment, by setting the deceleration-prohibited section as a section that extends from the first traffic light to a predetermined number of traffic lights in the direction of travel of the host vehicle (for example, the section to the next traffic light), it is possible to effectively prevent traffic jams at the first traffic light.

[0062] In this embodiment, the section setting unit 325 may calculate the signal density for each point by dividing the number of traffic lights included in a section from the starting point to a predetermined point in the direction of travel of the vehicle by the distance from the starting point to the predetermined point, starting from a first traffic light where the traffic light stop time is equal to or greater than a predetermined value, and set the section where the signal density is equal to or greater than the predetermined value as a deceleration-prohibited section. A section with high signal density is a section where multiple traffic lights are closely spaced within a short distance. In such a case, if only the section from the first traffic light to the next traffic light is set as a deceleration-prohibited section, the section distance of the deceleration-prohibited section will be short, which may not sufficiently prevent congestion at the first traffic light. In contrast, by setting the deceleration-prohibited section up to a point where the signal density is equal to or greater than a predetermined value, congestion at the first traffic light can be effectively prevented.

[0063] In this embodiment, the traffic light stop time acquisition unit 323 acquires the traffic light stop time of each traffic light via wireless communication from a predetermined external device 40. This allows the preset traffic light stop time to be acquired immediately, thereby reducing the processing time required to set the target speed.

[0064] In this embodiment, the traffic light stop time acquisition unit 323 may calculate the traffic light stop time of a traffic light at an intersection based on the type of lane the vehicle is traveling on and the type of intersection. This makes it possible to calculate the traffic light stop time of a target traffic light even if the traffic light stop time of the corresponding traffic light is not recorded in the memory 31 or if traffic light information cannot be acquired from the external device 40.

[0065] Furthermore, the traffic light stop time acquisition unit 323 may calculate the traffic light stop time based on the driving history of the vehicle. The driving history of the vehicle includes the stop time when the vehicle has stopped at a traffic light. Therefore, by setting the average or maximum stop time when the vehicle has stopped at a traffic light in the past driving history as the traffic light stop time, it is possible to calculate the traffic light stop time taking into account not only the time until the traffic light changes from red to another color but also the vehicle's departure delay time.

[0066] [Modifications] The present invention is not limited to the above-described embodiment, and includes the following modifications within the scope of achieving the object of the present invention. [Modification 1] In the above-described embodiment, the resolution time acquisition unit 324 calculates the resolution time T Ｏ When calculating the red duration T Ｒ０ However, the present invention is not limited to this. That is, the first term in the formula (1) is the red duration T Ｒ０ means the time until the leading vehicle starts moving in a congested section, and the average start time of the leading vehicle may be used. For example, in a congested section, the start of the leading vehicle may be delayed due to waiting to turn right, and in this case, the leading vehicle may not be able to start moving even if the traffic light is green. Therefore, the time from when the leading vehicle stops until when it starts moving is used as the red duration time T in equation (1), not the time the red light continues at an actual traffic light. Ｒ０ It may also be used as.

[0067] When the traffic light stop time acquisition unit 323 calculates the traffic light stop time based on the travel history of the vehicle, the traffic light stop time is the time from when the vehicle stops at the traffic light to when it starts moving. Therefore, as described above, the time from when the leading vehicle stops to when it starts moving is called the red light duration time T Ｒ０ From equation (1), the resolution time T Ｏ When calculating the traffic light stop time, it is preferable that the traffic light stop time acquisition unit 323 calculates the traffic light stop time based on the driving history of the vehicle.

[0068] In the above example, the red light duration is calculated based on the driving history of the vehicle recorded in the memory 31 of the vehicle. However, driving information may be transmitted from multiple vehicles to a predetermined external device 40 via a network. In this case, the external device 40 accumulates a large amount of received driving information and calculates the traffic light stop time from the accumulated driving information, taking into account the departure delay time of the leading vehicle. This allows for more accurate calculation of traffic light stop times based on a large number of samples. Furthermore, in this case, even if the user is visiting an area for the first time, the traffic light stop time of each traffic light can be calculated based on the driving history of other vehicles.

[0069] [Modification 2] In the above embodiment, the target speed setting unit 326 sets the tentative arrival time and the cancellation time T Ｏ The required delay time T Ｄ When allocating the time to each deceleration section, each deceleration section is divided into multiple groups, and points are given to each group according to the time spent stopping at a signal. Ｄ In response to this, the target speed setting unit 326 divides each deceleration section into a plurality of groups based on the signal stop time, and then assigns a required delay time T Ｄ may be allocated.

[0070] For example, as in the example shown in FIG. 3, a point "1" is assigned to a "medium" deceleration section where the traffic light stop time is less than a predetermined first threshold and equal to or greater than a second time threshold, and a point "2" is assigned to a "short" deceleration section where the traffic light stop time is less than the second time threshold. Also, the total number of points for all deceleration sections existing on the travel route is set to N. Then, the number of deceleration sections included in the set of "medium" deceleration sections with 1 point is set to N. １ Let the number of deceleration sections included in the set of two "short" deceleration sections be N ２ In this case, the target speed setting unit 326 sets N １ × (T Ｄ / N), and for the "short" deceleration section set, 2 × N ２ × (T Ｄ / N) are allocated as target delay times for each section.

[0071] Furthermore, the target speed setting unit 326 calculates the target section travel time by subtracting the section target delay time from the time it would take to travel all sections of the set of "medium" deceleration sections at the legal speed. Then, the target speed setting unit 326 calculates the target speed for the "medium" deceleration section based on the total section distance of all sections of the set of "medium" deceleration sections and the target section travel time. The same applies to the target speed for the "short" deceleration section. In this case, if the target speed is equal to or less than a predetermined lower limit, the target speed setting unit 326 further reduces the target speed for the other deceleration sections to shorten the time to reach the congestion section to within the clearance time T Ｏ The target speed is adjusted so that it is equal to or greater than the target speed for a "short" deceleration section. For example, if the target speed for a "short" deceleration section is below the lower limit, the target speed for that "short" deceleration section is set to the lower limit, and the difference between the time required to travel through that "short" deceleration section at the lower limit and the previously calculated target section travel time is calculated. The calculated difference is equally distributed to the other deceleration sections or distributed based on the traffic light stop time, and the target speeds for the other deceleration sections are recalculated. In the above embodiment, calculating the target speed for each section may change the target speed for each deceleration section. However, in the second modification, the target speed is unified for the same set of deceleration sections, thereby preventing the inconvenience of frequent changes in vehicle speed. Furthermore, the processing load when recalculating the target speed is reduced. Note that the calculation of the target speed described in the above embodiment and the second modification is merely an example, and other methods may be used to set the target speed for a deceleration section that is slower than the legal speed depending on the traffic light stop time.

[0072] [Variation 3] In the above embodiment, an example is shown in which the resolution time acquisition unit 324 calculates the resolution time based on equation (1), but the present invention is not limited to this. For example, when acquiring the congested section from the external device 40 in step S3, the resolution time acquisition unit 324 may acquire the estimated congestion resolution time along with the origin of the congested section and the length of the congested section.

[0073] [Variation 4] In the above embodiment, the zone setting unit 325 sets a deceleration-prohibited zone in addition to a deceleration zone, but a deceleration-prohibited zone does not have to be set. If a deceleration-prohibited zone is not set, a deceleration zone starting from the first traffic light is set. However, since the stop time of the first traffic light is longer than the stop time of other second traffic lights, the deceleration amount is smaller than in other deceleration zones, and the speed can be set close to the legal speed. This makes it possible to prevent congestion at the first traffic light.

[0074] In the above embodiment, the vehicle control device 10 is mounted on an autonomous vehicle, and a vehicle control method for suppressing congestion during autonomous driving is described as an example. However, the present invention can also be applied to a normal vehicle that does not perform autonomous driving, or to an autonomous vehicle that is not performing autonomous driving control. In this case, the target speed calculated by the target speed setting unit 326 may be notified to the driver by voice, by displaying it on a display, or the like.

[0075] 10...vehicle control device, 11...communication unit, 12...sensor group, 20...vehicle drive mechanism, 30...controller, 31...memory, 32...processor, 40...external device, 81...first traffic light, 82A, 82B...second traffic light, 83...no deceleration section, 84A, 84B...deceleration section, 85...congestion section, 321...route acquisition unit, 322...congestion section detection unit, 323...signal stop time acquisition unit, 324...resolution time acquisition unit, 325...section setting unit, 326...target speed setting unit, 327...vehicle control unit.

Claims

1. A vehicle control method for controlling a host vehicle using a computer, wherein the computer: acquires a driving route of the host vehicle; detects a congested section ahead on the driving route; acquires a traffic light stop time for a plurality of traffic lights located on the driving route, which is the time the vehicle will be continuously stopped at the traffic light; calculates a time until congestion in the congested section is resolved; sets a deceleration section, starting from the traffic light and spanning a predetermined distance in the direction of travel of the host vehicle, between the current position of the host vehicle and the congested section; sets a target speed for each deceleration section based on the traffic light stop time of the traffic light that is the starting point of the deceleration section, such that if the host vehicle travels through the deceleration section at the target speed, the time it takes for the host vehicle to reach the congested section from the current position will be a time after the time until congestion is resolved; and controls the vehicle speed of the host vehicle in the deceleration section at the set target speed.

2. The vehicle control method of claim 1, wherein the computer sets the target speed to be smaller when the stop time of the traffic light at the starting point of the deceleration section is shorter than when the stop time of the traffic light at the starting point of the deceleration section is longer.

3. A vehicle control method as described in claim 1 or claim 2, wherein, when setting the target speed, the computer: calculates the time required for the vehicle to travel from the current position to the end of the congestion section at the legal speed as a tentative arrival time; calculates the difference between the tentative arrival time and the resolution time as a required delay time; distributes the required delay time to each of the deceleration sections based on the traffic light stop time; calculates the target travel time by subtracting the distributed required delay time from the time it would take to travel through the deceleration section at the legal speed; and calculates the target speed based on the section distance of each of the deceleration sections and the target travel time.

4. A vehicle control method as claimed in any one of claims 1 to 3, wherein the computer calculates the time until the last vehicle in the congested section starts moving based on the stop time of the traffic light included in the congested section, the departure delay time of vehicles stopped in the congested section, and the number of stopped vehicles included in the congested section, as the resolution time.

5. The vehicle control method according to claim 4, wherein, when the congestion section includes a plurality of traffic lights, the computer calculates the clearance time using the maximum value of the traffic light stop times for each of the traffic lights.

6. A vehicle control method as described in any one of claims 1 to 5, wherein the computer further sets a no-deceleration section starting from the traffic light where the traffic light stop time is equal to or longer than a predetermined value, and controls the vehicle speed of the vehicle at a legal speed in the no-deceleration section.

7. The vehicle control method described in claim 6, wherein the computer sets the traffic light where the traffic light stop time is equal to or longer than the predetermined value as the starting point, and sets the section up to a predetermined number of traffic lights in the direction of travel of the vehicle as the no-deceleration section.

8. The vehicle control method described in claim 6, wherein the computer sets the traffic light where the traffic light stop time is equal to or greater than the predetermined value as the starting point, and sets the section where the signal density obtained by dividing the number of traffic lights included from the starting point to a predetermined point ahead in the direction of travel of the vehicle by the distance from the starting point to the predetermined point is equal to or greater than a predetermined value as the deceleration prohibited section.

9. A vehicle control method according to any one of claims 1 to 8, wherein the computer acquires the traffic light stop time of each of the traffic lights from a predetermined external device via wireless communication.

10. A vehicle control method as described in any one of claims 1 to 8, wherein the computer calculates the traffic light stop time of the traffic light based on the type of vehicle lane on which the vehicle is traveling and the type of intersection that intersects with the vehicle lane.

11. A vehicle control method according to any one of claims 1 to 8, wherein the computer accumulates a driving history of the vehicle and calculates the stop time of the traffic light based on the driving history.

12. A vehicle control device comprising: a route acquisition unit that acquires a driving route of the host vehicle; a congestion section detection unit that detects a congestion section ahead on the driving route; a traffic light stop time acquisition unit that acquires traffic light stop times related to the time the vehicle will be continuously stopped at a plurality of traffic lights located on the driving route; a resolution time acquisition unit that calculates the resolution time until congestion in the congestion section is resolved; a deceleration section setting unit that sets a plurality of deceleration sections that are a predetermined distance in the traveling direction of the host vehicle, starting from the traffic light, between the current position of the host vehicle and the congestion section; a target speed setting unit that sets a target speed for each deceleration section based on the traffic light stop time of the traffic light that is the starting point of the deceleration section, the target speed being set so that when the host vehicle travels through the deceleration section at the target speed, the time it takes for the host vehicle to reach the congestion section from the current position is a time after the resolution time; and a vehicle speed control unit that controls the vehicle speed in the deceleration section at the set target speed.

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