Patent ID: 12214823

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described below with reference to the drawings. In the following description, similar or equivalent elements are denoted by like signs to omit redundant description.

First Embodiment

FIG.1is a block diagram illustrating the configuration of a host vehicle1according to a first embodiment of the present disclosure. The host vehicle1includes an external field sensor11, an internal field sensor12, a map database13, a global positioning system (GPS) unit14, an actuator15, and an electronic control unit (ECU)100. The ECU100is an example of the “vehicle control device” according to the present disclosure and includes, as its functional components, a target travel trajectory generation unit101, a division line detection unit102, a different vehicle detection unit103, an entry operation detection unit104, an initial prediction unit105, an initial determination unit106, and a steering control unit107. The ECU100may be constituted from a processor.

The host vehicle1is configured to be able to implement a drive assist function to assist at least steering, among drive, steering, and braking, using constituent elements including the ECU100. The host vehicle1is an autonomous driving vehicle classified into level2or higher in the autonomous driving levels defined by the Society of Automotive Engineers (SAE), for example.

The external field sensor11is a sensor for detecting the surrounding environment of the host vehicle1. The surrounding environment includes information on the position, shape, speed, etc. of road structures such as road white lines, road signs, guardrails, and poles around the host vehicle1and the different vehicle2, dynamic targets such as surrounding vehicles and pedestrians, static targets such as buildings and signboards, etc. Examples of the external field sensor11include a camera, a millimeter-wave radar, and a laser imaging detection and ranging (LIDAR). The external field sensor11transmits detected information to the ECU100. The external field sensor11may be various sensors mounted on the host vehicle1, or may be various sensors mounted on the different vehicle2or a road facility if such sensors are communicably connected to the ECU100. The sensor11is communicably connected to the ECU100using vehicle-to-vehicle (V2V) communication when a sensor mounted on the different vehicle2is used as the sensor not mounted on the host vehicle1, and using vehicle-to-everything (V2X) communication when a sensor on a road facility is used. The external field sensor11may be a sensor unit constituted from a combination of a plurality of sensors.

The internal field sensor12is mounted on the host vehicle1, and acquires information on the present travel state of the host vehicle1. Examples of the internal field sensor12include a wheel speed sensor, an acceleration sensor, a yaw rate sensor, and a compass. The internal field sensor12may be a sensor unit constituted from a combination of a plurality of sensors.

The map database13is a database that stores map information including road network information, road geometry information, lane information, static obstacle information, etc., and is stored in a storage medium that is accessible from the ECU100such as a hard disk drive (HDD) and a solid state drive (SSD). The storage location of the map database13is not specifically limited as long as the map database13is accessible from the ECU100, and the map database13may be mounted on the host vehicle1or stored in an external server not mounted on the host vehicle1. When an external server is used, the external server is accessed from the ECU100using vehicle-to-everything communication or a mobile terminal communication network such as long term evolution (LTE).

The GPS unit14acquires present position information on the host vehicle1based on radio waves received from global positioning system (GPS) satellites. The acquired present position information is transmitted to the ECU100.

The actuator15is mounted on the host vehicle1. The actuator15is a travel device for varying the state of drive, steering, and braking of the host vehicle1. Various drive assist functions or autonomous driving functions for the host vehicle1are implemented by the actuator15implementing control related to travel of the host vehicle1as instructed by the ECU100.

The ECU100is constituted from one or more computers. The computers include a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), an input port, an output port, etc. A variety of functions are implemented by installing a variety of programs in the computers. The ECU100transmits and receives data to and from various units of the host vehicle1by communicating with the various units through the input port and the output port. In particular, the ECU100receives surrounding environment information from the external field sensor11, receives travel state information on the host vehicle1from the internal field sensor12, receives the map information from the map database13, and receives host vehicle position information from the GPS unit14. The ECU100transmits a control instruction related to travel of the host vehicle1to the actuator15.

Next, the functional configuration of the ECU100will be described.

The target travel trajectory generation unit101generates a target travel trajectory T1for the host vehicle1based on the surrounding environment information acquired by the external field sensor11, the travel state information acquired by the internal field sensor12, the map information acquired by the map database13, and the present position information acquired by the GPS unit14. The target travel trajectory T1is a target trajectory that indicates what positions the host vehicle1will travel through in the future. The target travel trajectory T1may be a trajectory that extends along the lane center of a host vehicle lane L1, for example. The target travel trajectory T1is generated based on the trajectory that extends along the lane center of the host vehicle lane L1by making appropriate corrections from the lane center of the host vehicle lane L1. The correction is based on the surrounding environment such as surrounding targets and road structures and the travel state of the host vehicle1such as vehicle speed, acceleration, and steering angle. The target travel trajectory T1is also corrected by the steering control unit107to be discussed later.

The division line detection unit102recognizes division lines of lanes in which the host vehicle1and the different vehicle2travel and surrounding lanes based on a signal received from the external field sensor11. The “division lines” include white lines and yellow lines that indicate the boundary of roads and lanes, and road boundary lines formed from road markers, curbs, etc.

The different vehicle detection unit103detects a different vehicle2that is present around the host vehicle1based on a signal received from the external field sensor11. The different vehicle detection unit103acquires information on the different vehicle2such as position, shape, size, speed, and travel direction.

In the present embodiment, in particular, the different vehicle detection unit103detects a different vehicle2located in a region that is not the host vehicle lane L1, of (among) regions that are adjacent to an adjacent lane L2that is adjacent to the host vehicle lane L1in which the host vehicle1is traveling. Examples of such a position include a position (FIG.2or5) on a second adjacent lane L3for the host vehicle lane L1, a position (FIG.3) on a merging path L4to be merged with the adjacent lane L2for the host vehicle lane L1, and a position (FIG.4) on an entry and exit path L5for a facility3that faces the adjacent lane L2for the host vehicle lane L1. The “adjacent lane” and the “second adjacent lane” in the present embodiment are not limited to lanes with the same travel direction as the host vehicle lane L1, and may also include lanes (so-called “oncoming lanes”) with a different travel direction from the host vehicle lane L1. For example, the lane L2illustrated inFIG.5is included in the “adjacent lane”, and the lane L3illustrated inFIG.5is included in the “second adjacent lane”.

The “position” of the host vehicle1and the different vehicle2is the center position of the host vehicle1and the different vehicle2. Alternatively, the “position” of the host vehicle1and the different vehicle2may be the center position of the front end of the host vehicle1and the different vehicle2.

The entry operation detection unit104detects entry operation of the different vehicle2located in a region that is not the host vehicle lane L1, of regions that are adjacent to the adjacent lane L2for the host vehicle lane L1, to enter the adjacent lane L2for the host vehicle lane L1based on a signal received from the external field sensor11. For example, the entry operation detection unit104detects entry operation (FIG.2or5) of the different vehicle2traveling in the second adjacent lane L3for the host vehicle lane L1to make a lane change to the adjacent lane L2, detects entry operation (FIG.3) of the different vehicle2traveling in the merging path L4that is merged with the adjacent lane L2for the host vehicle lane L1to enter the adjacent lane L2, and detects entry operation (FIG.4) of the different vehicle2located in the entry and exit path L5for a facility3that faces the adjacent lane L2for the host vehicle lane L1to enter the adjacent lane L2. The entry operation is detected based on the vehicle speed of the different vehicle2, acceleration, tilt with respect to the lanes etc., state of lighting of turn signals, etc. The entry operation is considered as being started at the time when a component of the speed of the different vehicle2in the direction of the adjacent lane becomes a predetermined threshold speed or more, for example.

The initial prediction unit105predicts an initial predicted position at the time before the start of steering control by the steering control unit107, the initial predicted position being a predicted position of the different vehicle2at the time when entry operation is completed. The initial predicted position is the position of the different vehicle2relative to the host vehicle1. In the present embodiment, the initial prediction unit105predicts a longitudinal position and a lateral position of the different vehicle2relative to the host vehicle1as an example of the initial predicted position. The initial prediction unit105makes a prediction through the procedure described below.

First, the initial prediction unit105sets a predicted travel trajectory T2of the different vehicle2. The predicted travel trajectory T2is a predicted trajectory that indicates what positions the different vehicle2will travel through in the future. When entry operation of the different vehicle2to enter the adjacent lane L2is detected, the initial prediction unit105first generates a trajectory from the present position of the different vehicle2toward the adjacent lane L2along the present travel direction of the different vehicle2(direction tilted with respect to the lanes). The trajectory is bent into a direction that is parallel to the adjacent lane L2at the point at which the trajectory reaches the center of the adjacent lane L2. After that, the trajectory extends in a direction that is parallel to the adjacent lane L2through the center of the adjacent lane L2. The initial prediction unit105sets a predicted travel trajectory T2of the different vehicle2in the manner described above. For example, the trajectories T2illustrated inFIGS.2to5are examples of the predicted travel trajectory T2set by the initial prediction unit105.

The method of setting the predicted travel trajectory T2is not limited to the method described above, and may be other methods. For example, the predicted travel trajectory T2may be set based on the predicted travel trajectory T2described above by making appropriate corrections based on the surrounding environment such as surrounding targets and road structures and the travel state of the different vehicle2such as vehicle speed, acceleration, and steering angle. For example, a target travel trajectory for the different vehicle2may be received through communication between the different vehicle2and the host vehicle1, and the received target travel trajectory may be set as the predicted travel trajectory T2.

Next, the initial prediction unit105predicts a longitudinal position and a lateral position of the different vehicle2in the future with respect to the host vehicle1. The longitudinal direction is a direction that is parallel to the travel direction of the host vehicle1. The lateral direction is a direction that is perpendicular to the longitudinal direction. The longitudinal direction may be a direction that is parallel to the host vehicle lane L1. When the host vehicle lane L1is curved, the longitudinal direction may be the direction of a tangent to the host vehicle lane L1at the present position of the host vehicle1.

The initial prediction unit105predicts a longitudinal position and a lateral position based on the target travel trajectory T1for the host vehicle1and the predicted travel trajectory T2of the different vehicle2. Specifically, the initial prediction unit105calculates what point on the target travel trajectory T1the host vehicle1will be positioned at and what point on the predicted travel trajectory T2the different vehicle2will be positioned at, at the time of completion of the entry operation of the different vehicle2into the adjacent lane L2. This calculation may be made on the assumption that the host vehicle1and the different vehicle2will maintain the present vehicle speed. Alternatively, vehicle speed plan information may be used when the vehicle speed plan information has been obtained, the vehicle speed plan information indicating a vehicle speed plan that is used for the host vehicle1and the different vehicle2to travel on the target travel trajectory T1and the predicted travel trajectory T2, respectively. The initial prediction unit105predicts a longitudinal position and a lateral position based on the calculated positions of the host vehicle1and the different vehicle2.

The “time of completion” of the entry operation is the time when the travel direction of the different vehicle2has become parallel to the adjacent lane L2after the different vehicle2reaches the center of the adjacent lane L2. The time of completion of the entry operation may be estimated by the ECU100, e.g. by the initial prediction unit105.

The initial determination unit106determines whether the initial predicted position of the different vehicle2is included in a control execution area. The control execution area is a region determined in advance with reference to the position of the host vehicle1. When the initial predicted position of the different vehicle2is included in the control execution area, control for correcting the target travel trajectory T1such that the host vehicle1is moved in a direction away from the adjacent lane is necessary. Conversely, such control is not necessary when the initial predicted position of the different vehicle2is not included in the control execution area.

FIG.6illustrates an example of the control execution area. In the present example, the control execution area is defined as an area with the lateral position ranging from −α to α and with the longitudinal position ranging from −γ to β. The longitudinal position is positive when the host vehicle1is located ahead of the different vehicle2, and is negative when the host vehicle1is located behind the different vehicle2. The lateral position is positive when the host vehicle1is located on the right side of the different vehicle2, and is negative when the host vehicle1is located on the left side of the different vehicle2. In the present example, the control execution area is larger on the negative side in the longitudinal direction than on the positive side (i.e. the absolute value of γ is larger than the absolute value of β). This is because the occupants of the host vehicle1have a relatively great sense of insecurity when the host vehicle1is located behind the different vehicle2compared to the case where the host vehicle1is located ahead of the different vehicle2, in which case the occupants of the host vehicle1have a relatively slight sense of insecurity. The control execution area is not limited to the example inFIG.6. For example, the range of the control execution area in the longitudinal direction may be the same on the positive side and the negative side (i.e. β=γ). Alternatively, other control execution areas may be used.

When the combination of the longitudinal position and the lateral position predicted is included in the control execution area, the steering control unit107instructs the actuator15to perform steering control for the host vehicle1. The steering control unit107performs steering control such that the travel position of the host vehicle1within the host vehicle lane L1in the width direction of the host vehicle lane L1is moved in a direction away from the adjacent lane L2.

In order to perform the steering control, the steering control unit107corrects the target travel trajectory T1into a direction of moving the host vehicle1away from the adjacent lane. The amount of correction may be set to a constant value (e.g. 50 cm) determined in advance, or may be a distance obtained by multiplying the distance from the center to an end of the host vehicle lane L1by a constant proportion (e.g. 50%). After the target travel trajectory T1is corrected, the host vehicle1is steered so as to move the host vehicle1onto a corrected target travel trajectory T′1. The host vehicle1is moved away from the adjacent lane L2through the steering control. The target travel trajectory T1may be corrected, as appropriate, so as not to interfere with the positions of other targets, obstacles, road division lines, etc. based on the information obtained from the external field sensor11, the map database13, and the GPS unit14.

The amount of correction for the target travel trajectory T1may be determined in accordance with the lateral speed of the different vehicle2. During the entry operation of the different vehicle2, the occupants of the host vehicle1have a greater sense of insecurity as the different vehicle2approach the host vehicle1at a higher speed. In order to suppress their sense of insecurity, the amount of correction for the target travel trajectory T1may be rendered larger as the lateral speed (i.e. the speed at which the different vehicle2approaches the host vehicle1) during the entry operation of the different vehicle2is higher. This makes it possible for the host vehicle1to travel farther away from the adjacent lane L2as the lateral speed of the different vehicle2is higher, which makes it possible to effectively suppress the sense of insecurity to be had by the occupants of the host vehicle1.

Next, scenes to which the first embodiment of the present disclosure is applied will be described with reference toFIGS.2to5.FIGS.2to5merely illustrate specific scenes, and the scenes to which the present disclosure is applicable are not limited to the scenes inFIGS.2to5.

FIG.2illustrates a scene in which a different vehicle2that is present within a second adjacent lane L3for the host vehicle lane L1makes a lane change to an adjacent lane L2. The host vehicle1is traveling along the target travel trajectory T1within the host vehicle lane L1. The different vehicle2in the second adjacent lane L3tilts its vehicle body in the direction of the adjacent lane L2. At this time, the initial prediction unit105generates a predicted travel trajectory T2of the different vehicle2. The predicted travel trajectory T2is a trajectory that allows the different vehicle2to travel straight to the center of the adjacent lane L2along the present travel direction of the different vehicle2(direction tilted with respect to the lanes), thereafter be curved into a direction that is parallel to the adjacent lane L2, and thereafter travel in a direction that is parallel to the adjacent lane L2through the center of the adjacent lane L2. The initial prediction unit105predicts a longitudinal position and a lateral position of the different vehicle2with respect to the host vehicle1based on the target travel trajectory T1for the host vehicle1and the predicted travel trajectory T2of the different vehicle2. The steering control unit107corrects the target travel trajectory T1for the host vehicle1into a target travel trajectory T′1based on the fact that the combination of the longitudinal position and the lateral position is included in the control execution area. That is, the steering control unit107performs steering control for the host vehicle1into a direction away from the adjacent lane L2. Thus, steering control is performed to move the host vehicle1away from the adjacent lane L2since before the different vehicle2completes a lane change to the adjacent lane L2(in particular without waiting for the lane change to be completed), which makes it possible to suppress the sense of insecurity of the occupants of the host vehicle1.

FIG.3illustrates a scene in which the different vehicle2that is present in the merging path L4to be merged with the adjacent lane L2for the host vehicle lane L1enters the adjacent lane L2. The host vehicle1is traveling along the target travel trajectory T1within the host vehicle lane L1. The different vehicle2in the merging path L4is detected, and entry operation of the different vehicle2to travel obliquely in the direction of the adjacent lane L2is detected. At this time, as in the case inFIG.2, a predicted travel trajectory T2of the different vehicle2is generated, and a longitudinal position and a lateral position of the different vehicle2in the future are predicted. The steering control unit107corrects the target travel trajectory T1for the host vehicle1into a target travel trajectory T′1, and performs steering control for the host vehicle1into a direction away from the adjacent lane L2, based on the fact that the combination of the longitudinal position and the lateral position in the future is included in the control execution area. Thus, steering control is performed to move the host vehicle1away from the adjacent lane L2since before the different vehicle2finishes entering the adjacent lane L2(in particular without waiting for the lane change to be completed), which makes it possible to suppress the sense of insecurity of the occupants of the host vehicle1.

FIG.4illustrates a scene in which a different vehicle2that is present within an entry and exit path L5for a facility3that faces an adjacent lane L2enters the adjacent lane L2. The host vehicle1is traveling along the target travel trajectory T1within the host vehicle lane L1. The different vehicle2in the entry and exit path L5is detected, and entry operation of the different vehicle2to travel in the direction of the adjacent lane L2is detected. At this time, as in the case inFIG.2, a predicted travel trajectory T2of the different vehicle2is generated, and a longitudinal position and a lateral position of the different vehicle2in the future are predicted. The steering control unit107corrects the target travel trajectory T1for the host vehicle1into a target travel trajectory T′1based on the fact that the combination of the longitudinal position and the lateral position in the future is included in the control execution area. That is, the steering control unit107performs steering control for the host vehicle1into a direction away from the adjacent lane L2. Thus, steering control is performed to move the host vehicle1away from the adjacent lane L2since before the different vehicle2completes entry into the adjacent lane L2(in particular without waiting for the lane change to be completed), which makes it possible to suppress the sense of insecurity of the occupants of the host vehicle1.

FIG.5illustrates a scene in which a different vehicle2that is present within a second adjacent lane L3as an oncoming lane makes a lane change to an adjacent lane L2as an oncoming lane. In the present embodiment, control is performed similarly even when the travel direction of the adjacent lane L2and the second adjacent lane L3is different from that of the host vehicle lane L1. Thus, control that is similar to the scene inFIG.2is performed also in the scene inFIG.5, which makes it possible to suppress the sense of insecurity of the occupants.

Next, cases where the steering control is not performed will be described with reference toFIGS.7A and7B.FIGS.7A and7Beach illustrate a case where steering control is not performed since a combination of the longitudinal position and the lateral position predicted is not included in the control execution area.

In the case illustrated inFIG.7A, the position of the different vehicle2is farther away from the host vehicle1in the longitudinal direction than in the case inFIG.2. In this case, a sufficient longitudinal distance is kept between the different vehicle2and the host vehicle1even at the time when a lane change of the different vehicle2is completed. Hence, the combination of the longitudinal position and the lateral position of the different vehicle2predicted is not included in the control execution area. Therefore, steering control for moving the host vehicle1away from the adjacent lane L2is not performed. It is conceivable that the longitudinal distance and the lateral distance are reduced with the host vehicle1catching up with the different vehicle2, or with the host vehicle1and the different vehicle2moved laterally in their respective lanes, after a lane change of the different vehicle2to the adjacent lane L2is completed. In such a case, steering control may be performed for the different vehicle in the adjacent lane L2.

In the case illustrated inFIG.7B, the host vehicle1is located ahead of the different vehicle2and away from the different vehicle2in the longitudinal direction. Also in this case, the combination of the longitudinal position and the lateral position predicted is not included in the control execution area, and therefore correction of the target travel trajectory T1and steering control for moving the host vehicle1away from the adjacent lane L2is not performed. When the longitudinal distance and the lateral distance are reduced after lane change operation is completed, steering control may be performed for the different vehicle in the adjacent lane L2, as in the case inFIG.7A.

The flow of processes according to the present embodiment will be described with reference to the flowchart inFIG.8. The processes related to the present flow are repeatedly performed by the ECU100at predetermined intervals.

In step S1, determination is made whether a different vehicle2located in a region (second adjacent lane) that is not the host vehicle lane, of regions that are adjacent to the adjacent lane L2for the host vehicle lane L1, is detected. When a different vehicle2is not detected (step S1: No), the process is ended. When a different vehicle2is detected (step S1: Yes), the process proceeds to step S2. In step S2, determination is made whether entry operation of the different vehicle2is detected. When entry operation is not detected (step S2: No), the process is ended. When entry operation is detected (step S2: Yes), the process proceeds to step S3.

In step S3, the initial prediction unit105predicts a longitudinal position and a lateral position of the different vehicle2with respect to the host vehicle1at the time when the entry operation of the different vehicle2is completed. In step S4, the initial determination unit106determines whether the combination of the longitudinal position and the lateral position predicted is included in the control execution area. When the combination of the longitudinal position and the lateral position predicted is not included in the control execution area (step S4: No), the process is ended. When the combination of the longitudinal position and the lateral position predicted is included in the control execution area (step S4: Yes), the target travel trajectory T1is corrected and steering control is performed such that the host vehicle1is moved away from the adjacent lane L2in step S5.

The timings of the processes performed in the host vehicle1will be described with reference toFIG.9. When the different vehicle2starts entry operation, the entry operation detection unit104of the host vehicle1detects the entry operation of the different vehicle2. Subsequently, the initial prediction unit105predicts positions of the host vehicle1and the different vehicle2, the initial determination unit106determines whether the different vehicle2is included in the control execution area, and the steering control unit107corrects a target trajectory for the host vehicle1and performs steering control for the host vehicle1. After that, the different vehicle2completes the entry operation. Thus, a sequence of processes by the host vehicle1is performed at the time before the different vehicle2completes the entry operation. At least, the sequence of process is initiated by the ECU100without waiting for completion of the entry operation.

In the first embodiment described above, the ECU100detects the different vehicle2located in a region that is not the host vehicle lane L1in which the host vehicle1is traveling, of regions that are adjacent to the adjacent lane L2for the host vehicle lane L1. When entry operation of the different vehicle2to enter the adjacent lane L2is detected, the target travel trajectory T1is corrected such that the host vehicle1is moved away from the adjacent lane and steering control is performed before the entry operation is completed. Thus, control for moving the host vehicle1away from the adjacent lane L2can be performed at a timing before the different vehicle2completes the entry operation. Therefore, it is possible to effectively suppress the sense of insecurity of the occupants of the host vehicle1.

Second Embodiment

A second embodiment is characterized by determining whether control is required based on the size of the different vehicle2. Elements that are similar or equivalent to those according to the first embodiment are denoted by like signs to omit redundant description.

In the second embodiment, when a different vehicle2located in a region that is not the host vehicle lane L1, of regions that are adjacent to the adjacent lane L2for the host vehicle lane L1, is detected, the different vehicle detection unit103acquires the size of the different vehicle2in the lateral direction. For example, the vehicle width of the different vehicle2is acquired. Then, the different vehicle detection unit103determines whether the acquired size in the lateral direction is more than a predetermined threshold. When the size in the lateral direction is more than the predetermined threshold, the occupants of the host vehicle1have a relatively great sense of insecurity when the different vehicle2travels in the adjacent lane L2. Therefore, the target travel trajectory T1is corrected, and the steering control is performed. When the size in the lateral direction is not more than the predetermined threshold, on the other hand, the occupants may feel annoyed if the target travel trajectory T1is corrected and the steering control is performed even though the occupants have a relatively slight sense of insecurity. Thus, correction of the target travel trajectory T1and steering control are not performed when the size in the lateral direction is less than the predetermined threshold.

FIG.10illustrates a case where steering control is not performed since the vehicle width of a different vehicle2is less than a threshold. The vehicle width of the different vehicle2illustrated inFIG.10is less than the vehicle width of the different vehicle2illustrated inFIG.2. In this case, correction of the target travel trajectory T1and steering control are not performed, and the host vehicle1continues traveling along the original target travel trajectory T1, even when the longitudinal positions and the lateral positions of the host vehicle1and the different vehicle2are included in the control execution area. Thus, it is possible to suppress unnecessary steering control and avoid the occupants feeling annoyed.

The predetermined threshold may be determined in accordance with the lane width of the host vehicle lane L1or the adjacent lane L2. For example, the predetermined threshold may be rendered smaller as the lane width of the host vehicle lane L1or the adjacent lane L2is smaller. This is because the host vehicle lane L1tends to be close in the lateral position to the adjacent lane L2and the occupants tend to have a sense of insecurity when the lane width is small.

The flow of processes for determining whether the steering control is required according to the second embodiment will be described with reference to the flowchart inFIG.11. The processes in the flowchart inFIG.11are performed immediately after step S1(immediately before step S2) in the flowchart inFIG.8when the determination made in step S1is Yes. This makes it possible to omit the processes in and after step S2when determination is made that the steering control is not required. In particular, the processes related to the prediction of a longitudinal position and a lateral position require a large amount of processing and may be a factor that increases a load on the ECU100. Therefore, a large contribution can be made to reduce the processing load when the steering control is determined to be unnecessary and omitted. The time when the processes in the flowchart inFIG.11are performed is not limited to immediately after step S1(immediately before step S2), and the processes may be performed before or after a different step. Alternatively, the processes in the flowchart inFIG.11may be performed separately from the processes in the flowchart inFIG.8.

In step S21in the flowchart inFIG.11, determination is made whether the size of the different vehicle2in the lateral direction is more than a predetermined threshold. When the size of the different vehicle2in the lateral direction is more than the predetermined threshold (step S21: Yes), the process proceeds to step S22. In step S22, determination is made that correction of the target travel trajectory T1and steering control are necessary. When the size of the different vehicle2in the lateral direction is not more than the predetermined threshold (step S21: No), on the other hand, determination is made in step S23that correction of the target travel trajectory T1and steering control are not necessary.

In the second embodiment described above, the ECU100acquires the size, in the lateral direction, of a different vehicle2located in a region that is not the host vehicle lane L1, of regions that are adjacent to the adjacent lane L2for the host vehicle lane L1. When the size in the lateral direction is less than a predetermined threshold, correction of the target travel trajectory T1and steering control are not performed. Thus, it is possible to avoid the occupants feeling annoyed as the target travel trajectory T1is corrected and steering control is performed even though the occupants have a relatively slight sense of insecurity.

Third Embodiment

A third embodiment is characterized by performing cancellation steering control for returning the travel position of the host vehicle1to its position before the start of steering control when entry operation of the different vehicle2into the adjacent lane L2is canceled. Elements that are similar or equivalent to those according to the first and second embodiments are denoted by like signs to omit redundant description.

In the third embodiment, the steering control unit107determines that entry operation of the different vehicle2to enter the adjacent lane L2has been canceled based on information received from the external field sensor11at the time during execution of the steering control or after completion of the steering control. Cancellation of the entry operation means that the different vehicle2stops attempting to enter the adjacent lane L2. Cancellation of the entry operation is determined based on the different vehicle2being stopped, the travel direction of the different vehicle2being varied into a direction that is parallel to the adjacent lane L2or a direction of moving away from the adjacent lane L2, etc. When cancellation of the entry operation is determined, the steering control unit107controls steering so as to return the host vehicle1to its position in the width direction within the host vehicle lane L1before the steering control is performed. That is, cancellation steering control is executed.

FIG.12illustrates an example of a scene according to the third embodiment. The host vehicle1is traveling on the corrected target travel trajectory T′1under the steering control by the steering control unit107based on detecting lane change operation of the different vehicle2. After that, operation of the different vehicle2to vary its travel direction and return from the adjacent lane L2to the second adjacent lane L3, that is, cancellation of the lane change operation, is detected. Accordingly, cancellation steering control for the host vehicle1is executed, and the host vehicle1is returned onto the original target travel trajectory T1.

FIG.13is a flowchart illustrating the flow of processes according to the third embodiment. The processes in the present flowchart are repeatedly executed by the ECU100at predetermined intervals. In step S31, the steering control unit107determines whether the steering control is being executed or has been completed. When the steering control is not being executed or has not been completed (step S31: No), the process is ended. When the steering control is being executed or has been completed (step S31: Yes), determination is made in step S32whether the different vehicle2has canceled the entry operation. When the entry operation has not been canceled (step S32: No), the process is ended. When the entry operation has been canceled (step S32: Yes), the steering control unit107performs the cancellation steering control in step S33.

In the third embodiment described above, when entry operation of the different vehicle2to enter the adjacent lane L2is canceled, cancellation steering control is executed such that the travel position of the host vehicle1is returned to the original position. Thus, it is possible to avoid the occupants having a sense of insecurity as the host vehicle1continues traveling off the original target travel trajectory even though the entry operation has been canceled.

Fourth Embodiment

A fourth embodiment is characterized by updating the prediction of the longitudinal positions and the lateral positions of the host vehicle1and the different vehicle2during entry operation of the different vehicle2to enter the adjacent lane L2and performing the cancellation steering control when the longitudinal positions and the lateral positions are no longer included in the predetermined control continuation area. Elements that are similar or equivalent to those according to the first to third embodiments are denoted by like signs to omit redundant description.

As illustrated inFIG.14, the ECU100according to the fourth embodiment includes a during-execution prediction unit108and a during-execution determination unit109.

In the fourth embodiment, the during-execution prediction unit108predicts a longitudinal position and a lateral position of the different vehicle2with respect to the host vehicle1at the time of completion of the entry operation, at the time when the steering control unit107is executing the steering control or has completed the steering control. The method of prediction may be the same as the prediction by the initial prediction unit105. The during-execution determination unit109determines whether the longitudinal position and the lateral position predicted by the during-execution prediction unit108are included in a predetermined control continuation area. The control continuation area is a region determined in advance with reference to the position of the host vehicle1. When the combination of the longitudinal position and the lateral position is included in the control continuation area, the cancellation steering control is not executed. When the combination of the longitudinal position and the lateral position is not included in the control continuation area, on the other hand, the cancellation steering control is executed. The content of the cancellation steering control may be the same as that according to the third embodiment.

The above processes are repeatedly performed at predetermined intervals until the entry operation of the different vehicle2is completed. That is, the during-execution predicted position of the different vehicle2is repeatedly updated.

The control continuation area may be the same region as the control execution area. Alternatively, the control continuation area may be a region that is larger than the control execution area (a control continuation condition is easily met compared to a control execution condition).

FIG.15illustrates an example of a scene according to the fourth embodiment. The host vehicle1is traveling on the corrected target travel trajectory T′1based on detecting lane change operation of the different vehicle2. After that, the behavior of the different vehicle2is varied, and the tilt of the different vehicle2with respect to the lanes becomes gentle. Accordingly, the longitudinal distance between the host vehicle1and the different vehicle2at the time of completion of the lane change is increased. Thus, the combination of the longitudinal position and the lateral position predicted by the during-execution prediction unit108is not included in the control continuation area, and the cancellation steering control for the host vehicle1is executed, and the host vehicle1is returned onto the original target travel trajectory T1.

FIG.16is a flowchart illustrating the flow of processes according to the fourth embodiment. The processes in the present flowchart are repeatedly executed by the ECU100at predetermined intervals until the entry operation of the different vehicle2is completed. In step S41, the during-execution prediction unit108determines whether the steering control unit107is executing or has completed the steering control and the different vehicle2is yet to complete the entry operation. When the steering control unit107is not executing or has not completed the steering control or the different vehicle2is not yet to complete the entry operation (step S41: No), the process is ended. When the steering control unit107is executing or has completed the steering control and the different vehicle2is yet to complete the entry operation (step S41: Yes), the during-execution prediction unit108predicts a longitudinal position and a lateral position of the different vehicle2with respect to the host vehicle1at the time of completion of the entry operation in step S42. In step S43, the during-execution determination unit109determines whether the combination of the longitudinal position and the lateral position predicted is included in the control continuation area. When the combination of the longitudinal position and the lateral position predicted is included in the control continuation area (step S43: Yes), the process is ended. When the combination of the longitudinal position and the lateral position predicted is not included in the control continuation area (step S43: No), the steering control unit107executes the cancellation steering control in step S44.

In the fourth embodiment described above, the prediction of the longitudinal position and the lateral position is updated, and the cancellation steering control is executed such that the travel position of the host vehicle1is returned to the original position when the longitudinal position and the lateral position are not included in the control continuation area. Thus, it is possible to avoid the occupants having a sense of insecurity as the host vehicle1continues traveling off the original target travel trajectory even though it is no longer expected that the host vehicle1and the different vehicle2approach each other.

Other Embodiments

In the first to fourth embodiments, the ECU100may not include the initial prediction unit105and the initial determination unit106. That is, the steering control may be performed when entry operation is detected alone, without predicting longitudinal positions and lateral positions of the host vehicle1and the different vehicle2at the time of completion of the entry operation. The processes related to the prediction of a longitudinal position and a lateral position require a large amount of processing and may be a factor that increases a load on the ECU100. When the initial prediction unit105and the initial determination unit106are not provided, it is possible to suppress the processing load until the steering control is performed after the detection of the entry operation. In addition, the steering control can be started immediately as a part of the processes after the detection of the entry operation is omitted. On the other hand, it is possible to suppress unnecessary steering control when the initial prediction unit105and the initial determination unit106are provided.

In the first to fourth embodiments, the mobile body located in a region that is not the host vehicle lane L1, of regions that are adjacent to the adjacent lane L2for the host vehicle lane L1, may not be a different vehicle2, and may be a different mobile body. Specifically, the mobile body may be a pedestrian, a bicycle, etc.

In the first to fourth embodiments, the steering control unit107corrects the target travel trajectory T1, and thereafter performs the steering control so as to move onto the corrected target travel trajectory T′1. However, the steering control may be performed in a different mode. For example, in a mode in which feedback control is performed so as to follow the center of the travel lane, rather than using a target travel trajectory, the target travel position in the lane may be changed to a position a predetermined distance away from the center of the lane.

In the first to fourth embodiments, a longitudinal position and a lateral position are predicted using the target travel trajectory T1for the host vehicle1and the predicted travel trajectory T2of the different vehicle2. However, a longitudinal position and a lateral position may be predicted by a different method. For example, the present longitudinal speeds and lateral speeds of the host vehicle1and the different vehicle2may be detected, and the longitudinal positions and the lateral positions of the host vehicle1and the different vehicle2at the time of completion of a lane change may be predicted based on such present longitudinal speeds and lateral speeds. That is, a completion time when a lane change is completed is calculated based on the lateral speed of the different vehicle2and the lateral distance of the different vehicle2to the adjacent lane L2. After that, the longitudinal positions of the host vehicle1and the different vehicle2at the completion time are calculated based on the longitudinal speeds of the host vehicle1and the different vehicle2. The lateral position is defined as the distance from the host vehicle1to the center of the adjacent lane L2. The longitudinal positions and the lateral positions may be predicted in the manner described above.

In the first to fourth embodiments, it is conceivable that a different vehicle2enters each of adjacent lanes on both the right and left sides of the host vehicle1. For example, it is conceivable that, when there are five or more lanes in the road in which the host vehicle1is traveling, a different vehicle2makes a lane change from each of second adjacent lanes on the right and left sides of the host vehicle1to each of adjacent lanes on the right and left sides of the host vehicle1. In such a case, the steering control according to the present disclosure may be performed on the different vehicle2that started the entry operation earlier. The steering control according to the present disclosure may not be performed when both the different vehicles2on the right and left sides started the entry operation at the same time.

The programs related to the present disclosure may be provided as stored in a computer-readable non-transitory storage medium. Examples of the computer-readable storage medium include a magnetic storage medium, an optical storage medium, and a semiconductor memory.

While the first to fourth embodiments and other embodiments of the present disclosure have been described above, the present disclosure is not limited thereto. The present disclosure may be implemented in such embodiments and various forms with a variety of changes and improvements made based on the knowledge of a person skilled in the art.