Vehicle control method and vehicle control device

Abstract

A vehicle control device (100) controls the travel of an ego vehicle (1) on the basis of a target trajectory and a target inter-vehicle distance between the ego vehicle and a forward object present in front of the ego vehicle (1). A sensor (200) detects, while the ego vehicle (1) is traveling, a preceding vehicle and a next preceding vehicle ahead in the travel lane of the ego vehicle (1). When it has been determined that the next preceding vehicle is stopped and the preceding vehicle is changing lanes to a neighboring lane, the vehicle control device (100) sets, as the target inter-vehicle distance, a distance longer than a first distance, which is the target inter-vehicle distance during normal traveling, or sets a trajectory leading to the neighboring lane as the target trajectory.

Description

Vehicle control method and vehicle control device

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

[0002] In automated driving of a vehicle, there is a technology for controlling lane changes to an adjacent lane depending on the driving conditions of the vehicle or the surrounding conditions (for example, Patent Document 1). The driving assistance method described in Patent Document 1 performs control such that, if it is determined based on the driving conditions of the vehicle that the vehicle does not need to change lanes, a first distance is set as the target distance, and if it is determined that the vehicle needs to change lanes, a second distance longer than the first distance is set as the target distance. It is explained that this ensures the distance necessary for changing lanes between the vehicle in front and the vehicle in front.

[0003] Japanese Patent Application Laid-Open No. 2021-142833

[0004] According to the driving assistance method of Patent Document 1, driving is controlled at the first distance until it is determined that a lane change is necessary. Therefore, if a lane change becomes necessary after the vehicle has stopped following a preceding vehicle, it may not be possible to maintain the distance required for the lane change, and the lane change may not be possible smoothly.

[0005] The present invention has been made in view of the above-mentioned circumstances, and has an object to provide a vehicle control method and a vehicle control device that can perform vehicle control for smooth lane changes.

[0006] In order to achieve the above object, a vehicle control method according to the present invention is a vehicle control method that uses a processor to control driving of a host vehicle based on a target inter-vehicle distance between the host vehicle and a forward object present in front of the host vehicle and a target trajectory of the host vehicle. When the processor determines that a vehicle ahead of the host vehicle is stopped in front of the host vehicle's driving lane and that the preceding vehicle is changing lanes to an adjacent lane while the host vehicle is traveling, the processor sets the target inter-vehicle distance to a distance longer than a first distance, which is the target inter-vehicle distance during normal driving, or sets the target trajectory to a trajectory that pulls over to the adjacent lane.

[0007] According to the present invention, by setting the target inter-vehicle distance to a distance longer than that during normal driving, or by setting the target trajectory to one that moves closer to the adjacent lane, it becomes possible to control the vehicle for smooth lane changes.

[0008] 1 is a block diagram showing an example of a functional configuration of a vehicle control device according to an embodiment of the present invention; FIG. 2 is a diagram showing an example of a hardware configuration of a vehicle control device according to an embodiment; FIG. 3 is a diagram showing an example of the positional relationship between a host vehicle, a preceding vehicle, and a vehicle ahead of the host vehicle; FIG. 4 is a flowchart of vehicle control processing according to an embodiment; FIG. 5 is a diagram showing a target trajectory and target inter-vehicle distance of the host vehicle; FIG. 6 is a diagram showing a target trajectory and target inter-vehicle distance of the host vehicle; FIG. 7 is a diagram showing a target trajectory and target inter-vehicle distance of the host vehicle; FIG. 8 is a flowchart of a process for determining lane change possibility according to a modified example; FIG. 9 is a diagram showing the position of a preceding vehicle used in determining lane change possibility; FIG. 10 is a diagram showing the position of a vehicle ahead of the host vehicle used in determining lane change possibility; FIG. 11 is a diagram showing a set curvature when the vehicle speed is high; and FIG. 12 is a diagram showing a set curvature when the vehicle speed is low.

[0009] A vehicle control method and a vehicle control device according to an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or equivalent parts are designated by the same reference numerals.

[0010] (Embodiment) A vehicle control device 100 according to an embodiment of the present invention is a device that controls the running of a vehicle. For example, the vehicle control device 100 realizes autonomous driving of the vehicle by controlling actuators that drive various parts of the vehicle. In this embodiment, the vehicle control device 100 is assumed to control level 4 autonomous driving, but other levels may also be used.

[0011] 1 is a diagram showing an example of the functional configuration of a vehicle control device 100 according to this embodiment, and illustrates a portion related to vehicle control according to this embodiment. The vehicle control device 100 is mounted on a vehicle and controls vehicle travel by performing acceleration / deceleration, steering, etc. based on a target inter-vehicle distance between the vehicle and an object ahead of the vehicle and a target trajectory set according to the vehicle's travel status and surrounding conditions. The vehicle control device 100 also performs lane keeping control, collision avoidance control, etc. in parallel using functional units not shown.

[0012] Fig. 2 is a diagram showing an example of the hardware configuration of the vehicle control device 100. In the example of Fig. 2, the vehicle control device 100 includes a processor 1011, a storage device 1012, and a communication interface (referred to as "communication I / F" in the figure) 1013, which are connected to each other via a bus 1010.

[0013] The processor 1011 includes, for example, one or more CPUs (Central Processing Units) and their peripheral circuits, and executes various types of arithmetic processing. The processor 1011 executes control programs stored in the storage device 1012. The processor 1011 may include a volatile semiconductor memory such as a RAM (Random Access Memory) that functions as a working memory for the CPU. The processor 1011 may also include an arithmetic circuit such as a logical arithmetic unit or a numerical arithmetic unit.

[0014] The storage device 1012 includes a nonvolatile semiconductor memory such as an EEPROM (Electrically Erasable and Programmable Read Only Memory), a flash memory, etc. The storage device 1012 stores the control program executed by the processor 1011 and various data used in the arithmetic processing of the processor 1011.

[0015] The communication interface 1013 includes an interface circuit for connecting the processor 1011 to an in-vehicle network that complies with standards such as a Controller Area Network (CAN). The communication interface 1013 receives signals from in-vehicle components such as the sensor 200, a Global Navigation Satellite System (GNSS) receiver, a map database, and a user interface, and passes the signals to the processor 1011.

[0016] The communication interface 1013 is also communicatively connected to various actuators that operate the vehicle, and transmits control signals generated by the processor 1011 to the various actuators to control the vehicle. The actuators include, for example, a drive device (at least one of an engine and a motor) for accelerating the vehicle, a brake actuator for braking the vehicle, a steering motor for steering the vehicle, etc. In this way, the vehicle control device 100 realizes automatic driving and driving assistance of the vehicle by controlling the actuators.

[0017] The sensors 200 connected to the communication interface 1013 include monitoring sensors that detect roads and objects around the vehicle, including other vehicles. Examples of the monitoring sensors include cameras, LiDAR (Light Detection and Ranging), RADAR (Radio Detection and Ranging), LRF (Laser Range Finder), and SONAR (Sound Navigation and Ranging). The sensors 200 output detected sensor signals to the vehicle control device 100. Based on the output of the monitoring sensors installed at the front of the vehicle, the inter-vehicle distance between the host vehicle and a forward object, such as a preceding vehicle or a vehicle ahead of the vehicle, can be measured. Furthermore, based on the output of the monitoring sensors installed on the sides of the vehicle, the presence and speed of other vehicles on the sides of the vehicle can be measured.

[0018] 1 is realized by the processor 1011 of the vehicle control device 100 executing a vehicle control processing program. That is, the vehicle control device 100 functions as a driving information acquisition unit 101 that acquires information indicating the driving state of the vehicle, a surrounding vehicle information acquisition unit 102 that acquires information about other surrounding vehicles, a lane change determination unit 103 that determines whether or not to execute a lane change based on the driving information and the surrounding vehicle information, a lane change possibility determination unit 104 that determines whether or not there is a possibility of a lane change, and a curvature setting unit 110 that outputs a set curvature that is a parameter used to determine the possibility of a lane change.

[0019] The vehicle control device 100 further functions as an inter-vehicle distance setting unit 105 that sets a target inter-vehicle distance based on the judgment results of the lane change judgment unit 103 and the lane change possibility judgment unit 104, a target vehicle speed generation unit 106 that generates a target vehicle speed for driving while maintaining the target inter-vehicle distance, a target vehicle speed following unit 107 that controls driving at the target vehicle speed, a target trajectory generation unit 108 that generates a target trajectory when executing a lane change, and a target trajectory driving unit 109 that controls driving along the target trajectory.

[0020] In the following description, a vehicle equipped with the vehicle control device 100 and performing vehicle control according to this embodiment will be referred to as the host vehicle 1, a vehicle traveling within a certain range ahead of the host vehicle 1 in the driving lane 501 on which the host vehicle 1 is traveling and one vehicle ahead of the host vehicle 1 will be referred to as the leading vehicle 2, a vehicle traveling within a certain range ahead of the leading vehicle 2 and one vehicle ahead of the leading vehicle 2 will be referred to as the second-leading vehicle 3, and a vehicle traveling in the adjacent lane 502 next to the driving lane 501 will be referred to as the other vehicle 4. In other words, the leading vehicle 2 is the first vehicle ahead of the host vehicle 1, and the second-leading vehicle 3 is the second vehicle ahead of the host vehicle 1. FIG. 3 is a diagram showing an example of the positional relationship between the host vehicle 1, the leading vehicle 2, and the second-leading vehicle 3. Each functional unit of the vehicle control device 100 will be described using FIGS. 2 and 3.

[0021] The driving information acquisition unit 101 acquires driving information indicating the driving state of the vehicle 1, such as the speed, steering direction, and autonomous driving state of the vehicle 1. The driving information acquisition unit 101 acquires driving information from on-board components such as various sensors, a GNSS receiver, a map database, and a user interface via a communication interface 1013.

[0022] The surrounding vehicle information acquisition unit 102 acquires information about vehicles present in front of and to the sides of the host vehicle 1. More specifically, the surrounding vehicle information acquisition unit 102 can acquire the position, movement, and speed of the leading vehicle 2 and the vehicle ahead of the leading vehicle 3 based on the output of a monitoring sensor provided at the front of the host vehicle 1 and its change over time. In addition, the surrounding vehicle information acquisition unit 102 can acquire the position, movement, and speed of another vehicle 4 traveling in the adjacent lane 502 based on the output of a monitoring sensor provided at the side of the host vehicle 1 and its change over time.

[0023] The lane change determination unit 103 determines whether or not to execute a lane change depending on the necessity of a lane change, based on the driving information acquired by the driving information acquisition unit 101 and the surrounding vehicle information acquisition unit 102. For example, when it determines that a lane change is necessary based on the traffic environment ahead of the vehicle 1, the driving plan of the vehicle 1, the driver's or user's intention, the traffic flow in the driving lane 501 and the adjacent lane 502, etc., it instructs the inter-vehicle distance setting unit 105 to perform a calculation to execute the lane change.

[0024] The lane change possibility determination unit 104 determines whether or not there is a possibility of changing lanes within a predetermined time based on the driving information acquired by the driving information acquisition unit 101 and the surrounding vehicle information acquired by the surrounding vehicle information acquisition unit 102. More specifically, when the lane change possibility determination unit 104 determines that the second-ahead vehicle 3 is stopped and the preceding vehicle 2 is changing lanes to the adjacent lane 502 while the host vehicle 1 is traveling, the lane change possibility determination unit 104 determines that there is a possibility of changing lanes to avoid the stopped second-ahead vehicle 3, and instructs the inter-vehicle distance setting unit 105 to perform a calculation to perform an operation in preparation for a lane change.

[0025] The curvature setting unit 110 transmits a set curvature used for setting the inter-vehicle distance to the inter-vehicle distance setting unit 105. The set curvature is a predetermined upper limit value of the curvature for changing lanes along a smooth trajectory. The set curvature may be variable depending on the speed of the host vehicle 1 when determining whether or not it is possible to change lanes.

[0026] The inter-vehicle distance setting unit 105 sets a target inter-vehicle distance based on the determination results of the lane change determination unit 103 and the lane change possibility determination unit 104, and issues a command to correct the trajectory if necessary depending on the target inter-vehicle distance. More specifically, when the lane change determination unit 103 determines to execute a lane change, the inter-vehicle distance setting unit 105 sets the target inter-vehicle distance to a distance longer than the first distance, which is the target inter-vehicle distance during normal driving, in order to change lanes smoothly at or below a set curvature. The inter-vehicle distance setting unit 105 also issues a command to correct the target trajectory to a trajectory for changing lanes to the adjacent lane 502.

[0027] In this embodiment, when the lane change possibility determination unit 104 determines that there is a possibility of a lane change, the following distance setting unit 105 acquires a predetermined second distance that is longer than the first distance, which is the target following distance during normal driving. For example, the second distance is set to the distance between the lane change start position and the rear end of the second-preceding vehicle 3 when the curvature of the lane change trajectory to avoid the stopped second-preceding vehicle 3 is a set curvature. The following distance setting unit 105 sets the second distance as the target following distance when the expected deceleration (-a: a is acceleration) expected for stopping at a position the second distance from the second-preceding vehicle 3 is equal to or less than a predetermined threshold. That is, when it is expected that the vehicle can stop at the second distance, which is the lower limit of the distance at which a smooth lane change is possible, with an acceptable deceleration, the second distance is set as the target following distance.

[0028] Furthermore, when it is determined that there is a possibility of a lane change and the assumed deceleration assumed for stopping at a position the second distance from the second-leading vehicle 3 is higher than a predetermined threshold and becomes an unacceptable deceleration, the inter-vehicle distance setting unit 105 sets the target inter-vehicle distance to the longer of a third distance from the stopping position when stopping at the threshold deceleration to the rear end of the second-leading vehicle 3, or the first distance, which is the target inter-vehicle distance during normal driving. In this case, the inter-vehicle distance setting unit 105 instructs to correct the target trajectory to a trajectory of moving closer to the adjacent lane 502 than the center of the traveling lane 501. In other words, when it is expected that an unacceptable deceleration will occur in stopping at the second distance, the first distance or the third distance, which is shorter than the second distance, is set as the target inter-vehicle distance, but an instruction is given to correct the target trajectory to a trajectory of moving closer to the adjacent lane 502 so as to make subsequent lane changes easier.

[0029] The target vehicle speed generating unit 106 generates a target vehicle speed that realizes the target inter-vehicle distance set by the inter-vehicle distance setting unit 105. Specifically, when the lane change determining unit 103 determines to execute a lane change, the target vehicle speed when changing lanes while maintaining an inter-vehicle distance equal to or greater than the target inter-vehicle distance is calculated.

[0030] The target vehicle speed following unit 107 controls the actuators to realize following travel at the target vehicle speed generated by the target vehicle speed generating unit 106. When changing lanes based on the determination of lane change execution by the lane change determining unit 103, the target vehicle speed following unit 107 controls each actuator to travel at the target vehicle speed while following the preceding vehicle 2 or another vehicle 4 traveling in the adjacent lane 502 to which the lane will be changed.

[0031] The target trajectory generation unit 108 generates a target trajectory in accordance with a target trajectory correction instruction from the inter-vehicle distance setting unit 105. More specifically, the target trajectory generation unit 108 generates a target trajectory for changing lanes to the adjacent lane 502 based on the determination of lane change execution by the lane change determination unit 103. Furthermore, based on the determination of the lane change possibility determination unit 104 that there is a possibility of a lane change, the target trajectory generation unit 108 generates a trajectory for pulling over to the adjacent lane 502 side as the target trajectory when an estimated deceleration estimated for stopping at a position a second distance from the vehicle 3 ahead of the vehicle 3 is higher than a predetermined threshold.

[0032] The target trajectory running unit 109 controls each actuator so that the host vehicle 1 runs according to the target trajectory generated by the target trajectory generating unit 108 .

[0033] The operation of the vehicle control device 100 configured as above will be described in detail using Fig. 4 and Figs. 5A, 5B, and 5C. Fig. 4 is a flowchart of vehicle control processing executed by the vehicle control device 100 of the host vehicle 1. Figs. 5A, 5B, and 5C are diagrams showing a target trajectory and a target inter-vehicle distance of the host vehicle 1. The processing shown in the flowchart of Fig. 4 is executed, for example, at predetermined time intervals in parallel with other vehicle control processing such as lane keeping control processing and collision avoidance processing.

[0034] First, the lane change possibility determination unit 104 determines whether or not it has detected that the second-to-first vehicle 3 is stopped and that the preceding vehicle 2 is changing lanes (step S101). Specifically, it determines whether or not the information acquired by the traveling information acquisition unit 101 and the surrounding vehicle information acquisition unit 102 based on the output of the sensor 200 indicates that the change in the position of the second-to-first vehicle 3 over time is constant and that the position of the preceding vehicle 2 is moving from the traveling lane 501 to the adjacent lane 502 over time. The states of the second-to-first vehicle 3 and the preceding vehicle 2 are determined by detecting them simultaneously or within a certain time period.

[0035] When at least one of the stop of the second-to-last vehicle 3 and the lane change of the leading vehicle 2 is not detected (step S101: No), the inter-vehicle distance setting unit 105 sets the first distance during normal driving as the target inter-vehicle distance (step S102), and sets the normal trajectory as the target trajectory (step S103). The normal trajectory is, for example, a trajectory that travels in the center of the left and right dividing lines, i.e., the center of the driving lane 501, as shown by the arrow in Figure 5A.

[0036] When the lane-changing possibility determination unit 104 determines that the vehicle 3 ahead of the vehicle 3 is stopped and that the preceding vehicle 2 is changing lanes (step S101: Yes), it determines that there is a possibility of a lane change and corrects the target inter-vehicle distance and the target trajectory, and acquires a set curvature, which is a parameter required for the calculation (step S104). The set curvature is an upper limit value of the curvature for changing lanes on a smooth trajectory as shown in FIG. 5B , and is set in advance and stored in the storage device 1012.

[0037] Next, the inter-vehicle distance setting unit 105 acquires a second distance, which is a parameter for determining the target inter-vehicle distance and is longer than the first distance. For example, the inter-vehicle distance setting unit 105 calculates the second distance as the distance between the start position of a lane change when changing lanes at a set curvature and the rear end of the vehicle 3 ahead of the vehicle 3, as shown in FIG. 5B (step S105).

[0038] Here, when it is determined in step S101 that there is a possibility of a lane change, the host vehicle 1 is located behind the leading vehicle 2, and therefore the inter-vehicle distance from the second-leading vehicle 3 is predicted to be longer than the second distance. At this time, it is determined whether the host vehicle 1 has already stopped (step S106). If the host vehicle 1 has already stopped at a distance from the second-leading vehicle 3 that is longer than the second distance (step S106: Yes), the inter-vehicle distance setting unit 105 sets the fourth distance, which is the inter-vehicle distance between the host vehicle 1 and the second-leading vehicle 3 at that time, as the target inter-vehicle distance, as shown in FIG. 5B (step S107), and terminates the processing. Here, the fourth distance is the distance between the host vehicle 1, which is stopped behind the leading vehicle 2, and the second-leading vehicle 3 when it is determined that the leading vehicle 2 is changing lanes, and is therefore predicted to be a distance long enough for the host vehicle 1 to change lanes.

[0039] After step S107, the host vehicle 1 continues to be stopped at a position that is the fourth distance from the second-to-first vehicle 3, but if the lane change determination unit 103 determines that a lane change is necessary while the host vehicle 1 is stopped, the target trajectory generation unit 108 corrects the target trajectory to a lane change trajectory, and the target trajectory travel unit 109 performs vehicle control to change lanes. At this time, the host vehicle 1 is stopped at a sufficiently long distance that is longer than the second distance from the second-to-first vehicle 3, and therefore can change lanes along a smooth trajectory.

[0040] In step S106, if the host vehicle 1 is traveling at a position where the inter-vehicle distance from the second-leading vehicle 3 is longer than the second distance (step S106: No), the inter-vehicle distance setting unit 105 calculates an estimated deceleration when the host vehicle 1 stops at the inter-vehicle distance of the second distance from the second-leading vehicle 3 (step S108). That is, the estimated deceleration for making the speed zero at a position where the inter-vehicle distance is the second distance from the second-leading vehicle 3 is calculated from the current speed of the host vehicle 1.

[0041] If the expected deceleration calculated in step S108 is equal to or less than a predetermined threshold (step S109: Yes), the inter-vehicle distance setting unit 105 sets the second distance calculated in step S105 as the target inter-vehicle distance (step S110), and ends the processing. Thereafter, if the lane change determination unit 103 determines that a lane change is necessary, the target trajectory generation unit 108 corrects the target trajectory to a lane change trajectory, and the target trajectory travel unit 109 performs vehicle control to change lanes. At this time, the host vehicle 1 may stop before changing lanes, or may change lanes while decelerating. In this case, the host vehicle 1 decelerates at a gradual deceleration that allows it to stop at a second distance from the vehicle 3 ahead of it, and a lane change is performed as necessary. This makes it possible to change lanes along a smooth trajectory after decelerating at an allowable deceleration.

[0042] If the expected deceleration calculated in step S108 is higher than the predetermined threshold (step S109: No), as shown in FIG. 5C , the inter-vehicle distance setting unit 105 sets the target inter-vehicle distance to the longer of the third distance, which is the inter-vehicle distance between the host vehicle 1 and the second-leading vehicle 3 when stopped at the threshold deceleration, and the first distance, which is the target inter-vehicle distance during normal driving (step S111). FIG. 5C illustrates a case where the third distance is longer. That is, if the expected deceleration is higher than the threshold but an inter-vehicle distance of at least the first distance can be ensured at the threshold deceleration, as shown in FIG. 5C , control is performed to decelerate at the threshold deceleration. On the other hand, if the inter-vehicle distance is expected to be shorter than the first distance at the threshold deceleration, control is performed to stop at a deceleration exceeding the threshold in order to ensure at least the first distance, which is the normal inter-vehicle distance.

[0043] In this case, the target inter-vehicle distance is set to the longer of the third distance and the first distance, and therefore the target inter-vehicle distance is shorter than the second distance. Therefore, in order to make the subsequent lane change as smooth as possible, as shown in Figure 5C, the inter-vehicle distance setting unit 105 issues an instruction to change the target trajectory to one that moves closer to the adjacent lane 502 than during normal driving (step S112), and then ends the processing.

[0044] Thereafter, when the lane change determination unit 103 determines that a lane change is necessary, the target trajectory generation unit 108 corrects the lane change trajectory to the target trajectory, and the target trajectory running unit 109 performs vehicle control to change lanes. The target trajectory at this time may be a trajectory that stops the vehicle at a target position that is the longer of the third distance and the first distance and that is closer to the adjacent lane 502 than during normal driving. Alternatively, the lane change may be executed without stopping based on the determination of the lane change determination unit 103. Setting a trajectory that is closer to the adjacent lane as the target trajectory makes it easier to change lanes than a trajectory when changing lanes from the center of the lane.

[0045] 4 at the next timing, if it is detected that the second-leading vehicle 3 has started traveling from a stopped state (step S101: No), the target inter-vehicle distance is returned to the first distance for normal traveling (step S102), and the target trajectory is returned to the trajectory for normal traveling (step S103). This makes it possible to control traveling to follow the second-leading vehicle 3 at the normal inter-vehicle distance and trajectory.

[0046] As described above, in the vehicle control device 100 according to this embodiment, the lane change possibility determination unit 104 determines that there is a possibility of a lane change when it detects a stopped second-to-first vehicle 3 and detects that the preceding vehicle 2 is changing lanes to the adjacent lane 502. The inter-vehicle distance setting unit 105 calculates a second distance, which is the distance from the lane change start position to the position of the second-to-first vehicle 3 when changing lanes at a set curvature. If the estimated deceleration expected for the host vehicle 1 to stop at a position the second distance from the second-to-first vehicle 3 is equal to or less than a predetermined threshold, the target inter-vehicle distance is set to the second distance, which is longer than the normal inter-vehicle distance. This allows the host vehicle 1 to stop with ample time to allow for a lane change at an allowable deceleration. Furthermore, if the estimated deceleration is higher than the predetermined threshold, the target trajectory is set to a trajectory that moves the host vehicle 1 closer to the adjacent lane 502, and the host vehicle 1 is controlled accordingly. This makes it possible to facilitate a lane change even when stopping at an inter-vehicle distance equal to or less than the second distance to avoid unacceptable deceleration by setting the target trajectory to a trajectory that moves the host vehicle 1 closer to the adjacent lane 502.

[0047] 6 is a flowchart of a lane change possibility determination process that is part of a vehicle control process according to a modified example, and FIGS. 7A and 7B are diagrams showing the positional relationships among the host vehicle 1, the preceding vehicle 2, and the vehicle ahead of the preceding vehicle 3 according to a modified example.

[0048] In the above embodiment, the lane change possibility determination unit 104 determines that there is a possibility of a lane change when it determines that the second-leading vehicle 3 is stopped and that the preceding vehicle 2 is changing lanes to the adjacent lane 502. In contrast, in this modified example, if it determines that the second-leading vehicle 3 is stopped within a certain time after the position of the preceding vehicle 2 at the time when the lane change of the preceding vehicle 2 is detected is saved, and if the positional relationship between the saved position of the preceding vehicle 2 and the stopped position of the second-leading vehicle 3 is a predetermined relationship, the lane change possibility determination unit 104 determines that there is a possibility of a lane change. Here, the certain time is a predetermined time, which is an upper limit of the time from when a lane change of the preceding vehicle 2 is detected to when it is detected that the second-leading vehicle 3 is stopped, in order to determine the possibility of a lane change.

[0049] The processing of this modified example will be described with reference to Figures 6, 7A, and 7B. First, the lane change possibility determination unit 104 determines whether the leading vehicle 2 is changing lanes (step S201), and if it detects that the leading vehicle 2 is changing lanes as shown in Figure 7A (step S201: Yes), it stores the detected position of the leading vehicle 2 in the storage device 1012 (step S202).

[0050] Next, the lane change possibility determination unit 104 determines whether or not a stopped second-to-first vehicle 3 is detected (step S204). If a stopped second-to-first vehicle 3 is detected (step S204: Yes), the lane change possibility determination unit 104 acquires the stored positional relationship between the position of the preceding vehicle 2 and the position of the second-to-first vehicle 3 (step S205). If the acquired positional relationship is a predetermined positional relationship, such as being within a certain distance in the travel lane 501 (step S206: Yes), the lane change possibility determination unit 104 determines that there is a possibility of a lane change (step S207) and ends the processing. If it is determined in step S207 that there is a possibility of a lane change, the result of step S101 in FIG. 4 is determined as Yes.

[0051] After detecting the preceding vehicle 2 (step S201: Yes) and storing the position of the preceding vehicle 2 (step S202), if the stopped vehicle before the preceding vehicle is not detected (step S204: No), or if the positional relationship between the stored position of the preceding vehicle 2 and the position of the preceding vehicle 3 is not a predetermined positional relationship (step S206: No), the lane change possibility determination unit 104 determines that there is no possibility of a lane change (step S208) and ends the processing. When it is determined in step S208 that there is no possibility of a lane change, the determination in step S101 in FIG. 4 is No.

[0052] On the other hand, if the preceding vehicle 2 is not detected as changing lanes (step S201: No) and the position of the preceding vehicle 2 is not saved within the certain time period (step S203: No), the lane change possibility determination unit 104 determines that there is no possibility of a lane change (step S208) and ends the process. In this case, the determination is made as No in step S101 in FIG. 4, and the vehicle continues traveling at the normal target inter-vehicle distance and normal target trajectory.

[0053] On the other hand, if the preceding vehicle 2 is not initially detected as changing lanes (step S201: No), but the position of the preceding vehicle 2 is stored in step S202 within a certain time prior to the determination (step S203: Yes), the lane change possibility determination unit 104 proceeds to step S204. Thereafter, as shown in FIG. 7B , when the second preceding vehicle 3 is detected as stopped (step S204: Yes), the lane change possibility determination unit 104 acquires the positional relationship between the stored position of the preceding vehicle 2 and the position of the second preceding vehicle 3 (step S205). If the acquired positional relationship is a predetermined positional relationship, such as being within a certain distance in the travel lane 501 (step S206: Yes), the lane change possibility determination unit 104 determines that there is a possibility of a lane change (step S207) and terminates the processing. When it is determined in step S207 that there is a possibility of a lane change, the result of step S101 in FIG. 4 is determined as Yes.

[0054] Even if the position of the preceding vehicle 2 is stored in step S202 within a certain time period (step S203: Yes), if the stopped state of the second preceding vehicle 3 is not detected (step S204: No), or if the positional relationship between the stored positions of the preceding vehicle 2 and the second preceding vehicle 3 is not a predetermined positional relationship (step S206: No), the lane change possibility determination unit 104 determines that there is no possibility of a lane change (step S208) and ends the processing. When it is determined in step S208 that there is no possibility of a lane change, the result of step S101 in FIG. 4 is No.

[0055] As described above, the lane change possibility determination unit 104 of the vehicle control device 100 according to this modification stores the position of the preceding vehicle 2 when it detects a lane change by the preceding vehicle 2, and when it detects a stop of the second preceding vehicle 3 within a certain period thereafter, if the positional relationship between the stored position of the preceding vehicle 2 and the position of the stopped second preceding vehicle 3 satisfies a predetermined relationship, it determines that there is a possibility that the host vehicle 1 will change lanes. This makes it possible to determine the possibility of a future lane change even when it is not possible to simultaneously detect the stopping of the preceding vehicle 2 and the lane change of the second preceding vehicle 3, for example, when the preceding vehicle 2 is too large to monitor the second preceding vehicle 3.

[0056] The hardware configurations and flowcharts shown in the above-described embodiment and modified examples are merely examples and can be modified or applied as desired. For example, in the above-described embodiment, the set curvature used by the inter-vehicle distance setting unit 105 to calculate the target inter-vehicle distance is a predetermined curvature, but the set curvature may be changeable. For example, since the curvature that feels smooth varies depending on the speed at the time of lane change, the set curvature may be a value that changes depending on the speed of the host vehicle 1 at the time when the stopped vehicle ahead 3 is detected and the preceding vehicle 2 is detected changing lanes to the adjacent lane 502.

[0057] For example, as shown in FIG. 8A , a low curvature may be set as the set curvature when the vehicle speed of the host vehicle 1 is high, and as shown in FIG. 8B , a high curvature may be set as the set curvature when the vehicle speed of the host vehicle 1 is low. For example, a table defining the correspondence between the set curvature and the vehicle speed may be stored in the storage device 1012, and the inter-vehicle distance setting unit 105 may acquire the set curvature by referring to the table. Furthermore, as shown in FIGS. 8A and 8B , the set curvature may be selected depending on the movement of another vehicle 4 traveling in the adjacent lane 502. For example, as shown in FIG. 8A , when the speed of the other vehicle 4 is high, it is necessary to change lanes at high speed to keep up with the flow of traffic, so a low curvature may be set as the set curvature. Alternatively, the set curvature may be changed depending on traffic conditions, driving habits, and preferences.

[0058] In the above embodiment, the second distance used to calculate the expected deceleration is the distance between the lane change start position and the second-leading vehicle 3 when the lane change trajectory to avoid the second-leading vehicle 3 has a set curvature, but it may be any predetermined distance as long as it is longer than the first distance. Similarly to the above-mentioned set curvature, the second distance may be a value that is set in advance depending on the vehicle speed, traffic conditions, driving habits, and preferences.

[0059] In addition, in the above embodiment, an example was described in which each function is realized by the processor 1011 executing a control program, but the vehicle control device 100 may also be configured using dedicated hardware that realizes each function.

[0060] Furthermore, the vehicle control device 100 may be configured to realize each function by storing and distributing a control program for executing the operations of the above-described embodiments on a computer-readable recording medium such as a CD-ROM (Compact Disc Read-Only Memory), a DVD (Digital Versatile Disc), an MO (Magneto Optical Disc), or a memory card, and installing the program on a computer. When each function is realized by sharing the work between an OS (Operating System) and an application, or by cooperation between the OS and an application, only the parts other than the OS may be stored on the recording medium.

[0061] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to explain the present invention and do not limit the scope of the present invention. In other words, the scope of the present invention is defined by the claims, not by the embodiments. Various modifications made within the scope of the claims and the meaning of the disclosure equivalent thereto are considered to be within the scope of the present invention.

[0062] 1 Vehicle, 2 Leading vehicle, 3 Next-to-leading vehicle, 4 Other vehicles, 100 Vehicle control device, 101 Traveling information acquisition unit, 102 Surrounding vehicle information acquisition unit, 103 Lane change determination unit, 104 Lane change possibility determination unit, 105 Inter-vehicle distance setting unit, 106 Target vehicle speed generation unit, 107 Target vehicle speed following unit, 108 Target trajectory generation unit, 109 Target trajectory travel unit, 110 Curvature setting unit, 200 Sensor, 1010 Bus, 1011 Processor, 1012 Storage device, 1013 Communication interface, 501 Traveling lane, 502 Adjacent lane.

Claims

1. A vehicle control method that uses a processor to control the driving of a host vehicle based on a target inter-vehicle distance between the host vehicle and a forward object in front of the host vehicle and a target trajectory of the host vehicle, wherein when the processor determines that a vehicle ahead of the host vehicle is stopped in front of the host vehicle's driving lane and that the preceding vehicle is changing lanes to an adjacent lane while the host vehicle is driving, the processor sets the target inter-vehicle distance to a distance longer than a first distance, which is the target inter-vehicle distance during normal driving, or sets the target trajectory to a trajectory that will pull over to the adjacent lane.

2. The vehicle control method described in claim 1, wherein the processor acquires in advance a second distance longer than the first distance, and sets the second distance as the target inter-vehicle distance if the expected deceleration expected to stop the vehicle at a position the second distance from the preceding vehicle is equal to or less than a predetermined threshold.

3. The vehicle control method according to claim 2, wherein the processor calculates, as the second distance, the distance between the lane change start position and the second preceding vehicle when the curvature of the lane change trajectory to avoid the second preceding vehicle is a predetermined set curvature.

4. The vehicle control method according to claim 2 or 3, wherein the processor sets the target trajectory to a trajectory that moves the vehicle closer to the adjacent lane when the expected deceleration is higher than the threshold value.

5. A vehicle control method according to any one of claims 2 to 4, wherein the processor sets the second distance according to the speed of the host vehicle when it determines that the vehicle ahead of the host vehicle is stopped and has changed lanes into the adjacent lane.

6. The vehicle control method according to claim 3, wherein the processor sets the set curvature according to the speed of the subject vehicle when it is determined that the vehicle ahead of the subject vehicle is stopped and has changed lanes into the adjacent lane.

7. A vehicle control method as described in any one of claims 2 to 6, wherein, when the expected deceleration is higher than the threshold value, the processor sets the target inter-vehicle distance to the longer of a third distance, which is the inter-vehicle distance between the vehicle and the vehicle ahead when stopped at the threshold deceleration, or the first distance.

8. A vehicle control method as described in claim 7, wherein the processor sets the target trajectory to a trajectory that stops the vehicle at a target position that is closer to the adjacent lane than during normal driving, at a position that is the set target inter-vehicle distance from the vehicle ahead.

9. A vehicle control method according to any one of claims 1 to 8, wherein the processor sets the first distance as the target inter-vehicle distance when the second-leading vehicle starts moving.

10. A vehicle control method according to any one of claims 1 to 9, wherein the processor sets the target trajectory for normal driving as the target trajectory when the second preceding vehicle starts driving.

11. A vehicle control method according to any one of claims 1 to 10, wherein the processor stores the position of the preceding vehicle at the time when it determines that the preceding vehicle is changing lanes to the adjacent lane, and when it determines that the second preceding vehicle is stopped within a certain time from the time when it determines the operation of the preceding vehicle, if the positional relationship between the position of the second preceding vehicle and the saved position of the preceding vehicle is a predetermined relationship, it determines that the second preceding vehicle is stopped and that the preceding vehicle is changing lanes to the adjacent lane.

12. A vehicle control device comprising: a sensor installed at the front of the host vehicle; and a processor that, when it is determined based on the output of the sensor that a vehicle ahead of the host vehicle is stopped and has changed lanes into an adjacent lane while the host vehicle is traveling, sets the target inter-vehicle distance to a distance longer than a first distance, which is the target inter-vehicle distance during normal traveling, or sets the target trajectory to a trajectory that moves the host vehicle closer to the adjacent lane, and controls the vehicle to travel based on the target inter-vehicle distance or the target trajectory.

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