JP7537548B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device that starts a vehicle.

JP Patent Publication No. 2017-87784 is known as a technical document related to a device for starting a vehicle. This publication describes a driving assistance system that causes the host vehicle to creep when a traffic jam is detected and the host vehicle is stopped, and the preceding vehicle starts moving and the inter-vehicle distance between the preceding vehicle and the host vehicle becomes equal to or greater than a predetermined distance.

JP 2017-87784 A

A stop control is known that automatically stops the vehicle when the preceding vehicle stops and the distance between the preceding vehicle and the vehicle falls below a stop threshold. It is possible that such a stop control and start control of the vehicle are used in combination. However, if the stop control and start control are simply combined, there is a risk that the vehicle will follow suit and repeatedly start and stop when the preceding vehicle repeatedly starts (moves forward slightly) and stops, and there is room for improvement.

Therefore, in this technical field, it is desirable to provide a vehicle control device that can appropriately start and stop the vehicle according to the distance between the vehicle and the preceding vehicle.

In order to solve the above problem, one aspect of the present invention is a vehicle control device that stops the host vehicle when the distance between the stopped preceding vehicle and the host vehicle becomes equal to or less than the stop threshold, and includes a start determination unit that determines whether the preceding vehicle starts and the distance between the preceding vehicle and the host vehicle becomes equal to or greater than the start threshold, which is a value greater than the stop threshold, when the preceding vehicle and the host vehicle are stopped, a vehicle control unit that starts the host vehicle when the start determination unit determines that the distance between the preceding vehicle and the host vehicle becomes equal to or greater than the start threshold, and an other vehicle status determination unit that determines the status of surrounding vehicles in adjacent lanes adjacent to the lane in which the host vehicle is traveling, and the start determination unit changes the start threshold to a value greater than the stop threshold based on the determination result of the other vehicle status determination unit.

The vehicle control device according to one aspect of the present invention can appropriately start and stop the host vehicle according to the distance between the host vehicle and the preceding vehicle.

In a vehicle control device according to one aspect of the present invention, the vehicle control unit may be configured to make it more difficult for the host vehicle to start after the preceding vehicle and the host vehicle have stopped and until the start determination unit determines that the vehicle-to-vehicle distance between the preceding vehicle and the host vehicle is equal to or greater than the start threshold, compared to when it is determined that the vehicle-to-vehicle distance is equal to or greater than the start threshold.

In a vehicle control device according to one aspect of the present invention, the vehicle control unit may maintain the stopped state of the host vehicle from when the preceding vehicle and the host vehicle have stopped until the departure determination unit determines that the inter-vehicle distance between the preceding vehicle and the host vehicle is equal to or greater than the departure threshold.

In a vehicle control device according to an aspect of the present invention, the other vehicle status determination unit may be configured to determine the status of the surrounding vehicles when the preceding vehicle and the host vehicle are stopped in front of a traffic light. In a vehicle control device according to an aspect of the present invention, the adjacent lane may be a lane traveling in the same direction as the lane in which the host vehicle is traveling. In a vehicle control device according to an aspect of the present invention, the surrounding vehicles may be other vehicles that are in front of a traffic light. In a vehicle control device according to an aspect of the present invention, the other vehicle status determination unit may determine the traveling status of the surrounding vehicles in the adjacent lane, and the departure determination unit may set a departure threshold in accordance with the determination result. In a vehicle control device according to an aspect of the present invention, the other vehicle status determination unit may determine whether or not a surrounding vehicle in the adjacent lane is traveling, and the departure determination unit may set a departure threshold in accordance with the determination result.

As described above, a vehicle control device according to one aspect of the present invention can appropriately start and stop the vehicle according to the distance between the vehicle and the preceding vehicle.

1 is a block diagram showing a vehicle control device according to an embodiment; FIG. 2 is a plan view showing a situation in which the vehicle ahead and the vehicle are stopped at an intersection. 1A is a graph showing the time change in the speed of a preceding vehicle and the speed of the own vehicle, and FIG. 1B is a graph showing the time change in the inter-vehicle distance between the preceding vehicle and the own vehicle. 13 is a flowchart showing a start determination process. 13 is a flowchart showing a start threshold setting process.

The following describes an embodiment of the present invention with reference to the drawings.

The vehicle control device 100 shown in FIG. 1 is mounted on a vehicle (host vehicle) such as a passenger car, and controls the running of the host vehicle. The vehicle control device 100 performs start and stop control of the host vehicle based on the inter-vehicle distance between the host vehicle and a preceding vehicle running immediately ahead of the host vehicle. The start and stop control of the host vehicle may be executed as part of an automatic driving function that automatically runs the vehicle.

[Configuration of the vehicle control device]
The configuration of the vehicle control device 100 will be described below with reference to the drawings. As shown in FIG. 1, the vehicle control device 100 includes an ECU (Electronic Control Unit) 10 that controls the running of the vehicle. The ECU 10 is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ECU 10 loads a program stored in the ROM into the RAM and executes the program with the CPU to perform various vehicle controls. The ECU 10 may be composed of multiple electronic control units.

The ECU 10 is connected to a GPS receiver 1, an external sensor 2, an internal sensor 3, a map database 4, and an actuator 5.

The GPS receiver 1 measures the vehicle's position (e.g., the latitude and longitude of the vehicle) by receiving signals from three or more GPS satellites. The GPS receiver 1 transmits the measured vehicle's position information to the ECU 10.

The external sensor 2 is a detection device that detects the situation around the vehicle. The external sensor 2 includes at least one of a camera and a radar sensor.

The camera is an imaging device that captures images of the external conditions of the vehicle. The camera is installed behind the windshield of the vehicle. The camera transmits imaging information related to the external conditions of the vehicle to the ECU 10. The camera may be a monocular camera or a stereo camera. The stereo camera has two imaging units arranged to reproduce binocular parallax. The imaging information of the stereo camera also includes information in the depth direction.

A radar sensor is a detection device that uses radio waves (e.g., millimeter waves) or light to detect obstacles around the vehicle. Radar sensors include, for example, millimeter wave radar or LIDAR (Light Detection and Ranging). A radar sensor detects obstacles by transmitting radio waves or light to the vicinity of the vehicle and receiving the radio waves or light reflected by the obstacles. The radar sensor transmits information about the detected obstacles to the ECU 10. Obstacles include fixed obstacles such as guardrails and buildings, as well as moving obstacles such as pedestrians, bicycles, and other vehicles.

The internal sensor 3 is a detection device that detects the traveling state of the host vehicle. The internal sensor 3 includes a vehicle speed sensor, an acceleration sensor, and a yaw rate sensor. The vehicle speed sensor is a detector that detects the speed of the host vehicle. For example, a wheel speed sensor is used as the vehicle speed sensor, which is provided on the wheels of the host vehicle or on a drive shaft that rotates integrally with the wheels, and detects the rotation speed of the wheels. The vehicle speed sensor transmits the detected vehicle speed information (wheel speed information) to the ECU 10.

The acceleration sensor is a detector that detects the acceleration of the host vehicle. The acceleration sensor includes, for example, a longitudinal acceleration sensor that detects the acceleration in the longitudinal direction of the host vehicle, and a lateral acceleration sensor that detects the lateral acceleration of the host vehicle. The acceleration sensor transmits, for example, acceleration information of the host vehicle to the ECU 10. The yaw rate sensor is a detector that detects the yaw rate (rotational angular velocity) around the vertical axis of the center of gravity of the host vehicle. For example, a gyro sensor can be used as the yaw rate sensor. The yaw rate sensor transmits the detected yaw rate information of the host vehicle to the ECU 10.

The map database 4 is a database that stores map information. The map database 4 is formed, for example, in a HDD [Hard Disk Drive] mounted on the vehicle. The map information includes road position information (position information for each lane), road shape information (for example, types of curves and straight sections, curvature, etc.), and position information of intersections and branching points. The map information also includes position information of traffic lights and information on the lanes corresponding to the traffic lights.

The actuators 5 are devices used to control the vehicle. The actuators 5 include at least a drive actuator, a brake actuator, and a steering actuator. The drive actuator controls the amount of air supplied to the engine (throttle opening) in response to a control signal from the ECU 10, thereby controlling the driving force of the vehicle. If the vehicle is a hybrid vehicle, in addition to the amount of air supplied to the engine, a control signal from the ECU 10 is input to the motor serving as a power source to control the driving force. If the vehicle is an electric vehicle, a control signal from the ECU 10 is input to the motor serving as a power source to control the driving force. The motor serving as a power source in these cases constitutes the actuator 5.

The brake actuator controls the brake system in response to a control signal from the ECU 10, and controls the braking force applied to the wheels of the vehicle. For example, a hydraulic brake system can be used as the brake system. The steering actuator controls the drive of an assist motor that controls the steering torque of the electric power steering system in response to a control signal from the ECU 10. In this way, the steering actuator controls the steering torque of the vehicle.

Next, the functional configuration of the ECU 10 will be described. The ECU 10 has a vehicle position recognition unit 11, a stop determination unit 12, a traffic light determination unit 13, an other vehicle situation determination unit 14, a departure determination unit 15, a speed profile generation unit 16, and a vehicle control unit 17.

The vehicle position recognition unit 11 recognizes the position of the host vehicle on the map based on the position information of the GPS receiver unit 1 and the map information of the map database 4. The vehicle position recognition unit 11 also recognizes the position of the host vehicle by SLAM [Simultaneous Localization and Mapping] technology using position information of fixed obstacles such as utility poles included in the map information of the map database 4 and the detection results of the external sensor 2. The vehicle position recognition unit 11 also recognizes the driving lane in which the host vehicle is traveling. The vehicle position recognition unit 11 may also recognize the position of the host vehicle on the map by other well-known methods.

The stop determination unit 12 determines whether the distance between the host vehicle and a stopped preceding vehicle becomes equal to or less than the stop threshold Ds while the host vehicle is traveling. The stop threshold Ds is a preset value. The value of the stop threshold Ds may be changed depending on the vehicle speed of the host vehicle and other parameters. The stop determination unit 12 can recognize the distance between the host vehicle and a stopped preceding vehicle based on the detection result of the external sensor 2.

When the preceding vehicle and the vehicle itself are stopped in front of a traffic light, the traffic light determination unit 13 determines whether the lighted signal of the traffic light is a pass permission signal. "In front of the traffic light" can be within a first distance from the traffic light or a reference point corresponding to the criteria of the traffic light (such as a stop line or an intersection). The first distance is a distance of a preset value. A pass permission signal is a signal that permits the vehicle to pass (e.g. a green light).

The traffic light determination unit 13, for example, determines whether the preceding vehicle and the vehicle are stopped in front of a traffic light based on the position information of the traffic light included in the map information of the map database 4, the position of the vehicle on the map recognized by the vehicle position recognition unit 11, the detection results of the external sensor 2, and the detection results of the internal sensor 3 (detection results of the vehicle speed sensor).

When the traffic light determination unit 13 determines that the preceding vehicle and the vehicle itself are stopped in front of a traffic light, it determines whether the traffic light's on signal is a pass permission signal or not based on the detection result of the external sensor 2 (image captured by the camera). The traffic light's on signal is not determined to be a pass permission signal when the traffic light's on state is a pass prohibition signal (e.g., a red light) or a transition signal (e.g., a yellow light), or when the traffic light's on state is unknown. A transition signal is a signal that turns on when transitioning from a pass permission signal to a pass prohibition signal. A transition signal is not required.

The traffic light determination unit 13 may perform the above determination by acquiring information on the traffic light's illumination signal through communication with a wireless network (Internet, optical beacon, etc.) via a communication device in the vehicle.

When the preceding vehicle and the vehicle itself are stopped in front of a traffic light, the other vehicle status determination unit 14 determines whether a nearby vehicle is traveling in an adjacent lane in front of the traffic light that is traveling in the same direction as the lane in which the vehicle itself is traveling. An adjacent lane in the same direction as the lane in which the vehicle itself is traveling means that it does not include an adjacent lane that is exclusively for right turns when the lane in which the vehicle itself is traveling is going straight.

When determining nearby vehicles, "in front of a traffic light" can be defined as within a second distance from the traffic light or a reference point corresponding to the criterion of the traffic light (such as a stop line or an intersection). The second distance is a preset distance. The second distance may be the same as the first distance that is the criterion for whether the vehicle is stopped in front of a traffic light, or it may be a different distance.

The other vehicle status determination unit 14 recognizes whether there is an adjacent lane in the same direction as the driving lane, based on the map information in the map database 4 and the position of the vehicle on the map recognized by the vehicle position recognition unit 11. The other vehicle status determination unit 14 determines whether a nearby vehicle is traveling in front of a traffic light in the adjacent lane, based on the detection results of the external sensor 2, the map information, and the position of the vehicle on the map.

The other vehicle status determination unit 14 determines that no nearby vehicles are traveling in the adjacent lane in front of the traffic light if there is no adjacent lane traveling in the same direction as the driving lane or if there are no nearby vehicles on the adjacent lane. The other vehicle status determination unit 14 may determine that no nearby vehicles are traveling if the speed of the nearby vehicles is equal to or less than a first predetermined value (e.g., 3 km/h) even if there are nearby vehicles. The other vehicle status determination unit 14 may also determine that no nearby vehicles are traveling if the speed of the nearby vehicles is equal to or less than a second predetermined value (e.g., 10 km/h) and the deceleration of the nearby vehicles is equal to or greater than a predetermined value.

In addition, when the preceding vehicle and the vehicle itself are stopped in front of a traffic light, the other vehicle status determination unit 14 determines whether or not an oncoming vehicle is traveling in front of the traffic light in the oncoming lane of the vehicle itself. The other vehicle status determination unit 14 can make the above determination based on the detection results of the external sensor 2, map information, and the position of the vehicle itself on the map.

The oncoming lane of the lane in which the vehicle is traveling is a lane that has a traveling direction opposite to the traveling direction of the lane in which the vehicle is traveling. The oncoming lane's traffic light can be within a third distance from the oncoming lane's traffic light or a reference point corresponding to the traffic light's criteria (such as a stop line or an intersection). The third distance is a preset distance. The third distance may be the same as the first distance or may be a different distance. The third distance may also be the same as the second distance or may be a different distance.

The other vehicle status determination unit 14 determines that there is no oncoming vehicle in the oncoming lane in front of the traffic light when there is no oncoming lane in the driving lane (including a case where the oncoming lane cannot be detected by the external sensor 2 in a tunnel, etc.) or when there is no oncoming vehicle on the oncoming lane. The other vehicle status determination unit 14 may determine that there is no oncoming vehicle traveling in the oncoming lane if the oncoming vehicle's speed is equal to or lower than a third predetermined value (e.g., 3 km/h) even if there is an oncoming vehicle. The other vehicle status determination unit 14 may also determine that there is no oncoming vehicle traveling if the oncoming vehicle's speed is equal to or lower than a fourth predetermined value (e.g., 10 km/h) and the deceleration of the oncoming vehicle is equal to or higher than a predetermined value.

When the preceding vehicle and the host vehicle are stopped, the departure determination unit 15 determines whether the preceding vehicle has started moving and the distance between the preceding vehicle and the host vehicle has become equal to or greater than the departure threshold Dth. The departure threshold Dth is a threshold value that is preset as a value greater than the stop threshold Ds. The departure threshold Dth may be changed as long as it is a value greater than the stop threshold Ds under the same conditions. The departure determination unit 15 can make the above determination based on the detection result of the external sensor 2.

The departure determination unit 15 determines whether the inter-vehicle distance is equal to or greater than the departure threshold not only when the preceding vehicle and the vehicle are stopped in front of a traffic light, but also when the preceding vehicle and the vehicle are stopped due to a traffic jam on the road, a stop line without a traffic light, etc.

In addition, when the preceding vehicle and the vehicle itself stop in front of a traffic light and the traffic light determination unit 13 does not determine that the light on the traffic light is a passage permission signal, the departure determination unit 15 sets the departure threshold to a larger value than when the light on the traffic light is determined to be a passage permission signal.

When the preceding vehicle and the subject vehicle are stopped in front of a traffic light and the other vehicle status determination unit 14 determines that a surrounding vehicle is not traveling in front of the traffic light in an adjacent lane that is traveling in the same direction as the lane in which the subject vehicle is traveling, the departure determination unit 15 sets the departure threshold to a larger value than when it is determined that the surrounding vehicle is traveling.

When there are multiple surrounding vehicles in a line on an adjacent lane, the departure determination unit 15 may set the departure threshold based on the leading surrounding vehicle, which is the surrounding vehicle closest to the traffic light. In this case, the other vehicle status determination unit 14 determines whether the leading surrounding vehicle is traveling or not based on the detection results of the external sensor 2, the map information, and the position of the host vehicle on the map. When it is determined that the leading surrounding vehicle is not traveling, the departure determination unit 15 sets the departure threshold to a larger value than when it is determined that the leading surrounding vehicle is traveling. In this case, it is not necessary to use the presence or absence of surrounding vehicles following the leading surrounding vehicle in setting the departure threshold.

When there are multiple adjacent lanes in the same traveling direction as the lane in which the vehicle is traveling, the departure determination unit 15 may set the departure threshold to a larger value when all leading surrounding vehicles in each adjacent lane are not traveling, compared to when at least one leading surrounding vehicle in each adjacent lane is traveling.

In addition, when the preceding vehicle and the host vehicle are stopped in front of a traffic light and the other vehicle status determination unit 14 determines that there is no oncoming vehicle in front of the traffic light in the oncoming lane of the host vehicle's traveling lane, the departure determination unit 15 sets the departure threshold to a larger value than when it is determined that an oncoming vehicle is traveling.

When there are multiple oncoming vehicles in a line in the oncoming lane, the departure determination unit 15 may set the departure threshold based on the leading oncoming vehicle, which is the oncoming vehicle closest to the traffic light in the oncoming lane. In this case, the other vehicle status determination unit 14 determines whether or not the leading oncoming vehicle is traveling based on the detection results of the external sensor 2, the map information, and the position of the host vehicle on the map. When it is determined that the leading oncoming vehicle is not traveling, the departure determination unit 15 sets the departure threshold to a larger value than when it is determined that the leading oncoming vehicle is traveling. In this case, it is not necessary to use the presence or absence of oncoming vehicles following the leading oncoming vehicle in setting the departure threshold.

When there are multiple oncoming lanes, the departure determination unit 15 may set the departure threshold to a larger value when none of the leading oncoming vehicles in each oncoming lane are traveling, compared to when at least one leading oncoming vehicle in each oncoming lane is traveling.

When the preceding vehicle and the subject vehicle are stopped in front of a traffic light, and the vehicle closest to the traffic light in the subject vehicle's driving lane is not the preceding vehicle (the vehicle immediately preceding the subject vehicle), the departure determination unit 15 may set the departure threshold based on the leading vehicle closest to the traffic light in the driving lane. In this case, when it is determined that the leading vehicle is not moving, the departure determination unit 15 sets the departure threshold to a larger value than when it is determined that the leading vehicle is moving. Whether or not the leading vehicle is moving can be recognized from the detection result of the external sensor 2.

The speed profile generation unit 16 generates a speed profile of the host vehicle. The speed profile is a vehicle speed plan used to control the vehicle speed of the host vehicle. The speed profile includes a target vehicle speed according to the position of the host vehicle.

The generation of the speed profile is described in detail below. The speed profile generation unit 16 generates a speed profile based on the surrounding environment of the vehicle recognized from the detection results of the external sensor 2, the running state of the vehicle recognized from the detection results of the internal sensor 3, the map information of the map database 4, and the position of the vehicle on the map recognized by the vehicle position recognition unit 11.

The speed profile generator 16 calculates a preset upper speed limit, the speed limit at a speed limit point included in the map information, a curvature-based speed according to the curvature of the lane in which the vehicle is traveling, and an obstacle situation speed according to the situation of moving obstacles around the vehicle.

Specifically, the speed profile generating unit 16 sets the set maximum speed (e.g., the legal maximum speed) for the vehicle's travel lane as the upper speed limit. Furthermore, the speed profile generating unit 16 recognizes the speed limit at speed limit points included in the map information based on the vehicle's position on the map and the map information. Speed limit points are points where speed is restricted, such as stop lines and pedestrian crossing markings. For example, the speed limit for stop lines can be 0 km/h, and the speed limit for pedestrian crossing markings can be 20 km/h. The speed limit may be included in the map information, or may be stored in a database (e.g., a traffic rule map database) separate from the map database 4.

The speed profile generator 16 calculates a curvature-corresponding speed according to the curvature of the lane in which the vehicle is traveling, based on the vehicle's position on the map and the map information. As an example, the speed profile generator 16 calculates the curvature-corresponding speed from the curvature, using a curvature-vehicle speed map in which the curvature and the vehicle speed are previously associated.

The speed profile generating unit 16 calculates an obstacle situation speed according to the situation of moving obstacles around the vehicle, based on the surrounding environment of the vehicle recognized from the detection results of the external sensor 2. As an example, when a preceding vehicle is traveling, the speed profile generating unit 16 adopts the vehicle speed of the preceding vehicle as the upper limit speed as the obstacle situation speed. In addition, the speed profile generating unit 16 can calculate an obstacle situation speed according to the situation of moving obstacles around the vehicle using various well-known methods.

The speed profile generating unit 16 sets a target vehicle speed that is equal to or lower than the minimum of the upper speed limit, the speed limit, the curvature-compliant speed, and the obstacle situation speed for each preset position along the travel lane. The preset positions along the travel lane are positions that are set at regular intervals on the travel lane. As an example, the target vehicle speed can be set to the same value as the minimum speed. In the case of autonomous driving, the preset positions can be set along a preset target route.

The speed profile generator 16 generates a speed profile by interpolating the target vehicle speed for each set position using a pre-set smooth interpolation process. As an example, spline interpolation can be used for the smooth interpolation process.

The speed profile generating unit 16 generates a speed profile for starting and stopping the host vehicle. The speed profile at the time of starting is generated, for example, so as to provide faster acceleration than creep driving due to creep torque. Note that the speed profile generating unit 16 is not limited to the above-mentioned speed profile generating method, and may employ various well-known speed profile generating methods.

When the stop determination unit 12 determines that the distance between the stopped preceding vehicle and the vehicle itself is equal to or less than the stop threshold Ds, the vehicle control unit 17 performs stop control of the vehicle itself. Based on the speed profile, the vehicle control unit 17 transmits a control signal to the actuator 5 to decelerate and stop the vehicle itself.

When the departure determination unit 15 determines that the distance between the preceding vehicle and the host vehicle is equal to or greater than the departure threshold, the vehicle control unit 17 performs departure control of the host vehicle. The vehicle control unit 17 starts the host vehicle by sending a control signal to the actuator 5 based on the speed profile. When the preceding vehicle and the host vehicle are stopped, the vehicle control unit 17 maintains the stopped state of the host vehicle until the departure determination unit 15 determines that the distance between the preceding vehicle and the host vehicle is equal to or greater than the departure threshold Dth.

Here, FIG. 2 is a plan view showing a situation where the vehicle ahead and the vehicle itself are stopped at an intersection. FIG. 2 shows the vehicle itself M, the vehicle ahead Ns, the distance L between the vehicle itself M and the vehicle ahead Ns, the lane R1 in which the vehicle itself M is traveling, the adjacent lane R2 adjacent to the lane R1, the oncoming lanes R3 and R4 opposite the lane R1, a traffic light TL1 ahead of the vehicle itself M, and a traffic light TL2 in the oncoming lane. In FIG. 2, the traffic lights TL1 and TL2 are set to no-passing signals (e.g., red lights).

In the driving lane R1, in addition to the host vehicle M and the preceding vehicle Ns, the vehicle Na ahead of the preceding vehicle Ns and the vehicle Nb following the host vehicle M are stopped. In the adjacent lane R2, the surrounding vehicles Nr1 to Nr4 are stopped. In the oncoming lane R3, the oncoming vehicle Nt is stopped. In FIG. 2, the vehicle Na ahead of the preceding vehicle is the leading vehicle closest to the traffic light TL1 in the driving lane R1. The surrounding vehicle Nr1 is the leading surrounding vehicle closest to the traffic light TL1 in the adjacent lane R2. The oncoming vehicle Nt is the leading oncoming vehicle closest to the traffic light TL2 in the oncoming lane R3.

Consider the case where the preceding vehicle Ns moves forward slightly and stops in the situation shown in Figure 2. Here, Figure 3(a) is a graph showing the time change in the speed of the preceding vehicle Ns and the speed of the host vehicle M. The vertical axis of Figure 3(a) is speed [km/h], and the horizontal axis is time [sec]. Figure 3(a) shows the preceding vehicle speed Vn (dash line), the conventional host vehicle speed Vp (dashed line), and the current host vehicle speed Vm (solid line). A conventional case will be described where the stop threshold Ds determined by the stop determination unit 12 and the start threshold Dth determined by the start determination unit 15 are the same value.

Figure 3(b) is a graph showing the change over time in the distance between the preceding vehicle Ns and the vehicle M. The vertical axis of Figure 3(b) is the distance between the vehicles [m], and the horizontal axis is time [sec]. Figure 3(b) shows the conventional distance between the vehicles Lp (dashed line) and the current distance between the vehicles L (solid line). The vertical axis shows the stop threshold Ds and the start threshold Dth.

The horizontal axis also shows times T1 to T7. Time T1 is the time when the preceding vehicle Ns starts moving. Time T2 is the time when the conventional host vehicle M starts moving following the preceding vehicle Ns. Time T3 is the time when the preceding vehicle Ns stops. Time T4 is the time when the conventional host vehicle M stops moving following the preceding vehicle Ns. Time T5 is the time when the light signal of traffic light TL1 is switched to a pass permission signal. Time T6 is the time when the preceding vehicle Ns starts moving. Time T7 is the time when the current host vehicle M starts moving following the preceding vehicle Ns.

In the situation shown in FIG. 2, if the stop threshold Ds and the start threshold Dth are the same value as in the conventional case, when the preceding vehicle Ns moves forward slightly and the inter-vehicle distance Lp between the preceding vehicle Ns and the host vehicle M exceeds the stop threshold Ds (see FIG. 3(b)), the host vehicle M will immediately follow and start moving. After that, as shown in FIG. 3(a), when the preceding vehicle Ns decelerates, the conventional host vehicle M also decelerates and stops, resulting in unnecessary start and stop of the host vehicle M.

In response to this, as shown in Figures 3(a) and 3(b), the vehicle control device 100 sets the starting threshold Dth to a value greater than the stopping threshold Ds, so that even if the preceding vehicle Ns moves forward slightly and stops, the current vehicle M can be prevented from following and starting and stopping. The effects of such a vehicle control device 100 will be described in detail later.

In FIG. 3(a) and FIG. 3(b), there is a time lag between when the inter-vehicle distance L between the preceding vehicle Ns and the host vehicle M falls below the stop threshold Ds and when the host vehicle M starts to decelerate. Also, in FIG. 3(b), the value of the departure threshold Dth is not changed when the light signal of the traffic light TL1 is switched to a pass permission signal.

[Vehicle control device start determination process]

Next, the start determination process of the vehicle control device 100 according to one embodiment will be described with reference to FIG. 4. FIG. 4 is a flowchart showing the start process. The process of the flowchart shown in FIG. 4 is executed when the preceding vehicle and the host vehicle are stopped. The process of this flowchart is not limited to the case where the preceding vehicle and the host vehicle are stopped in front of a traffic light.

As shown in FIG. 4, the ECU 10 of the vehicle control device 100 determines in S10 whether the preceding vehicle has started and the distance between the preceding vehicle and the host vehicle has become equal to or greater than the start threshold Dth using the start determination unit 15. The start threshold Dth is a threshold value that is preset as a value greater than the stop threshold Ds. If the ECU 10 does not determine that the distance between the preceding vehicle and the host vehicle has become equal to or greater than the start threshold Dth (S10: NO), the ECU 10 ends this processing. The ECU 10 repeats the processing from S10 again after a certain period of time has elapsed. If the ECU 10 determines that the distance between the preceding vehicle and the host vehicle has become equal to or greater than the start threshold Dth (S10: YES), the ECU 10 proceeds to S12.

In S12, the ECU 10 controls the start of the host vehicle using the vehicle control unit 17. The vehicle control unit 17 starts the host vehicle by sending a control signal to the actuator 5 based on the speed profile generated in advance. After that, the ECU 10 ends this processing.

The speed profile may be generated when the preceding vehicle and the vehicle itself stop, or when the departure determination unit 15 determines that the vehicle distance is equal to or greater than the departure threshold Dth.

[Vehicle control device start threshold setting process]
Next, the start threshold setting process of the vehicle control device 100 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the start threshold setting process. The process of the flowchart shown in Fig. 5 is executed, as an example, when the host vehicle stops.

As shown in FIG. 5, in step S20, the ECU 10 uses the traffic light determination unit 13 to determine whether the preceding vehicle and the vehicle are stopped in front of a traffic light. The traffic light determination unit 13 can determine whether the preceding vehicle and the vehicle are stopped in front of a traffic light based on the traffic light position information included in the map information in the map database 4, the position of the vehicle on the map recognized by the vehicle position recognition unit 11, and the detection results of the external sensor 2 and the internal sensor 3 (detection results of the vehicle speed sensor).

If the ECU 10 does not determine that the preceding vehicle and the vehicle are stopped in front of the traffic light (S20: NO), the process ends. In this case, the starting threshold Dth is set to, for example, an initial value. If the ECU 10 determines that the preceding vehicle and the vehicle are stopped in front of the traffic light (S20: YES), the process proceeds to S22.

In S22, the ECU 10 determines whether the traffic light's light signal is a pass permission signal using the traffic light determination unit 13. The traffic light determination unit 13 can make the above determination based on the detection result of the external sensor 2 (image captured by the camera). If the ECU 10 determines that the traffic light's light signal is a pass permission signal (S22: YES), it proceeds to S24. If the ECU 10 does not determine that the traffic light's light signal is a pass permission signal (S22: NO), it proceeds to S26.

In S24, the ECU 10 sets the value of the starting threshold Dth to D1 by the starting determination unit 15. Then, the ECU 10 ends this processing.

In S26, the ECU 10 uses the other vehicle status determination unit 14 to determine whether or not a nearby vehicle is traveling in front of a traffic light in an adjacent lane that is traveling in the same direction as the lane in which the vehicle is traveling. The other vehicle status determination unit 14 can make the above determination based on the detection results of the external sensor 2, map information, and the position of the vehicle on the map. If the ECU 10 determines that a nearby vehicle is traveling (S26: YES), it proceeds to S32. If the ECU 10 does not determine that a nearby vehicle is traveling (S26: NO), it proceeds to S28.

In S28, the ECU 10 determines whether or not an oncoming vehicle is traveling in front of a traffic light in the oncoming lane of the host vehicle using the other vehicle status determination unit 14. The other vehicle status determination unit 14 can make the above determination based on the detection results of the external sensor 2, map information, and the position of the host vehicle on the map. If the ECU 10 determines that an oncoming vehicle is not traveling (S28: YES), it transitions to S30. If the ECU 10 determines that an oncoming vehicle is traveling (S28: NO), it transitions to S24.

In S30, the ECU 10 sets the value of the starting threshold Dth to D2 by the starting determination unit 15. D2 is a value greater than D1. Then, the ECU 10 ends this processing.

In S32, the ECU 10 uses the other vehicle status determination unit 14 to determine whether or not an oncoming vehicle is traveling in front of a traffic light in the oncoming lane of the vehicle. S32 and S28 are the same determination process. If the ECU 10 determines that an oncoming vehicle is traveling (S32: NO), it transitions to S30. If the ECU 10 determines that an oncoming vehicle is not traveling (S32: YES), it transitions to S34.

In S34, the ECU 10 sets the value of the starting threshold Dth to D3 by the starting determination unit 15. D3 is a value greater than D2 and D1. Then, the ECU 10 ends this processing.

In the flowchart shown in FIG. 5, the departure threshold Dth is changed to three values D1 to D3, but it may also be two values. If the vehicle control device 100 determines that neither nearby vehicles nor oncoming vehicles are traveling, it may set the value of the departure threshold Dth to D1, and if it determines that either nearby vehicles or oncoming vehicles are traveling, it may set the value of the departure threshold Dth to D2.

[Functions and Effects of the Vehicle Control Device]
According to the vehicle control device 100 of the embodiment described above, when the inter-vehicle distance L between a stopped preceding vehicle Ns and the host vehicle M becomes equal to or less than the stop threshold Ds, the host vehicle M is stopped, and the stopped state of the host vehicle M is maintained until the preceding vehicle Ns starts moving and the inter-vehicle distance L between the preceding vehicle Ns and the host vehicle M becomes equal to or greater than the start threshold Dth, which is a value greater than the stop threshold Ds.Therefore, compared to when the stop threshold Ds and the start threshold Dth are the same value, when the preceding vehicle Ns makes a small start (slight forward movement) and stops, the host vehicle M is prevented from following and starting and stopping, and the host vehicle M can be appropriately started and stopped in accordance with the inter-vehicle distance L between the preceding vehicle Ns and the host vehicle M.

That is, as shown in FIG. 3(a) and FIG. 3(b), in the vehicle control device 100, even if the preceding vehicle Ns moves forward slightly, the preceding vehicle Ns maintains a stopped state without starting until the inter-vehicle distance L between the preceding vehicle Ns and the host vehicle M reaches the start threshold Dth, which is greater than the stop threshold Ds. This makes it possible to suppress unnecessary starting and stopping by the host vehicle M, thereby reducing deterioration in the drivability of the host vehicle M. In addition, the vehicle control device 100 can also suppress unnecessary starting and stopping by vehicles following the host vehicle M, thereby avoiding deterioration in the drivability of the following vehicles.

As shown in FIG. 3(b), in the vehicle control device 100, even if the preceding vehicle Ns moves forward slightly and stops, the host vehicle M does not follow, so the inter-vehicle distance L between the preceding vehicle Ns and the host vehicle M is maintained close to the departure threshold Dth. Therefore, as shown in FIG. 3(a), when the lighted state of the traffic light TL1 becomes a passage permission signal and the preceding vehicle Ns starts, the host vehicle M can follow the departure of the preceding vehicle Ns earlier than in the conventional case, and the possibility of cutting in ahead of the host vehicle M from the adjacent lane R2 can be reduced.

Further operational effects of the vehicle control device 100 will be described below. Note that Figures 3(a) and 3(b) do not reflect changes to the value of the departure threshold Dth based on the judgment results of the traffic light judgment unit 13, which will be described below, and changes to the value of the departure threshold Dth based on the judgment results of the other vehicle status judgment unit 14.

In the vehicle control device 100, when the traffic light determination unit 13 does not determine that the on signal of the traffic light TL1 is a pass permission signal, the preceding vehicle Ns that has started is more likely to stop again in front of the traffic light TL1 than when the on signal of the traffic light TL1 is determined to be a pass permission signal. Therefore, by setting the start threshold Dth to a large value, it is possible to appropriately suppress the host vehicle M from following the slight start and stop of the preceding vehicle Ns. On the other hand, according to the vehicle control device 100, when the on signal of the traffic light TL1 is determined to be a pass permission signal, the preceding vehicle Ns that has started is more likely to pass through the traffic light TL1. Therefore, by setting the start threshold Dth to a small value, it is possible to realize a smooth start of the host vehicle M in response to the start of the preceding vehicle Ns.

In the vehicle control device 100, when the other vehicle status determination unit 14 determines that the surrounding vehicle Nr1 in front of the traffic light TL1 is not traveling in the adjacent lane R2 that is traveling in the same direction as the lane R1 of the host vehicle M, the preceding vehicle Ns that has started off is more likely to stop again in front of the traffic light TL1 than when the surrounding vehicle Nr1 is traveling. Therefore, by setting the start threshold Dth to a large value, it is possible to appropriately suppress the host vehicle M from following the slight starts and stops of the preceding vehicle Ns.

In addition, in the vehicle control device 100, when there is no oncoming vehicle Nt traveling in front of the traffic light TL1 in the oncoming lane R3, the preceding vehicle Ns that has started off is more likely to stop again in front of the traffic light compared to when an oncoming vehicle Nt is traveling. Therefore, by setting the start threshold Dth to a large value, it is possible to appropriately suppress the host vehicle M from following the slight starts and stops of the preceding vehicle Ns.

In the vehicle control device 100, when the leading vehicle Na closest to the traffic light TL1 in the driving lane R1 is not traveling, the preceding vehicle Ns that has started moving is more likely to stop again in front of the traffic light compared to when the leading vehicle Na is traveling. Therefore, by setting the starting threshold Dth to a large value, it is possible to appropriately suppress the host vehicle M from following the slight starting and stopping of the preceding vehicle Ns.

The above describes a preferred embodiment of the present invention, but the present invention is not limited to the above-mentioned embodiment. The present invention can be implemented in various forms, including the above-mentioned embodiment, with various modifications and improvements based on the knowledge of those skilled in the art.

The vehicle control device 100 does not necessarily have to have a traffic light determination unit 13, and does not need to change the starting threshold Dth depending on the lighting state of the traffic light. In this case, the map information does not need to include the position information of the traffic light and the information of the lane corresponding to the traffic light.

The vehicle control device 100 does not necessarily have an other vehicle status determination unit 14, and does not need to change the departure threshold Dth depending on whether or not nearby vehicles, oncoming vehicles, or the leading vehicle (the leading vehicle in the lane in which the vehicle is traveling) are traveling.

Alternatively, the vehicle control device 100 may change the departure threshold Dth using at least one of the surrounding vehicles, oncoming vehicles, and the leading vehicle. In this case, the other vehicle status determination unit 14 may determine whether at least one of the surrounding vehicles, oncoming vehicles, and the leading vehicle is traveling. Note that the other vehicle status determination unit 14 may determine whether at least one of the surrounding vehicles, oncoming vehicles, and the leading vehicle is traveling by acquiring information about each vehicle through vehicle-to-vehicle communication, not limited to the detection results of the external sensor 2.

1...GPS receiver, 2...external sensor, 3...internal sensor, 4...map database, 5...actuator, 10...ECU, 11...vehicle position recognition unit, 12...stop determination unit, 13...traffic light determination unit, 14...other vehicle status determination unit, 15...start determination unit, 16...speed profile generation unit, 17...vehicle control unit, 100...vehicle control device.

Claims (7)

A vehicle control device that stops a host vehicle when a vehicle-to-vehicle distance between a stopped preceding vehicle and the host vehicle becomes equal to or less than a stopping threshold,
a start determination unit that determines, when the preceding vehicle and the host vehicle are stopped, whether or not the preceding vehicle starts and the inter-vehicle distance between the preceding vehicle and the host vehicle becomes equal to or greater than a start threshold that is greater than the stop threshold;
a vehicle control unit that starts the host vehicle when the start determination unit determines that the inter-vehicle distance between the preceding vehicle and the host vehicle is equal to or greater than the start threshold;
an other vehicle status determination unit that determines the status of a surrounding vehicle in an adjacent lane adjacent to the lane in which the host vehicle is traveling;
Equipped with
The vehicle control device, wherein the departure judgment unit sets the departure threshold from among values greater than the stop threshold based on the judgment result of the other vehicle status judgment unit, and when the other vehicle status judgment unit determines that the surrounding vehicle is not traveling, the departure threshold is set to a value greater than when it is determined that the surrounding vehicle is traveling . The vehicle control device according to claim 1, wherein the vehicle control unit is configured to make the host vehicle less likely to start from the time when the preceding vehicle and the host vehicle have stopped until the start determination unit determines that the inter-vehicle distance between the preceding vehicle and the host vehicle is equal to or greater than the start threshold, compared to when it is determined that the inter-vehicle distance is equal to or greater than the start threshold. The vehicle control device according to claim 1, wherein the vehicle control unit maintains the stopped state of the host vehicle from when the preceding vehicle and the host vehicle have stopped until the departure determination unit determines that the inter-vehicle distance between the preceding vehicle and the host vehicle is equal to or greater than the departure threshold. A vehicle control device that stops a host vehicle when a vehicle-to-vehicle distance between a stopped preceding vehicle and the host vehicle becomes equal to or less than a stopping threshold,
a start determination unit that determines, when the preceding vehicle and the host vehicle are stopped, whether or not the preceding vehicle starts and the inter-vehicle distance between the preceding vehicle and the host vehicle becomes equal to or greater than a start threshold that is greater than the stop threshold;
a vehicle control unit that starts the host vehicle when the start determination unit determines that the inter-vehicle distance between the preceding vehicle and the host vehicle is equal to or greater than the start threshold;
an other vehicle status determination unit that determines the status of a surrounding vehicle in an adjacent lane adjacent to the lane in which the host vehicle is traveling;
Equipped with
the other vehicle status determination unit is configured to determine a status of the surrounding vehicles when the host vehicle is located in front of an intersection,
The vehicle control device, wherein the start determination unit sets the start threshold from among values greater than the stop threshold based on a determination result of the other vehicle situation determination unit. The vehicle control device according to claim 1 , wherein the other vehicle status determination unit is configured to determine the status of the surrounding vehicles when the preceding vehicle and the host vehicle are stopped in front of a traffic light. The vehicle control device according to claim 1 or 4 , wherein the adjacent lane is a lane traveling in the same direction as the lane in which the host vehicle is traveling. The vehicle control device according to claim 5 , wherein the nearby vehicle is another vehicle that is present in front of the traffic light.

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