Collision avoidance method, and collision avoidance system

Abstract

To provide a collision avoidance method, and a collision avoidance system which can avoid collision with a preceding vehicle.SOLUTION: A controller of a collision avoidance system comprises the steps of: acquiring position and speed of an own vehicle; acquiring position and speed of a preceding vehicle; calculating a collision prediction time based on the position and the speed of the own vehicle and the position and the speed of the preceding vehicle; detecting an adjacent vehicle traveling on an adjacent lane; detecting boundary of a traffic lane; predicting the position and the speed of the preceding vehicle at the timing when the collision prediction time becomes the time of brake avoidance limit and the position and the speed of the own vehicle at the brake avoidance limit; securing a distance of more than safety margin relative to the position of the preceding vehicle and selecting a free space where the own vehicle approaches based on the positions and the speeds of the own vehicle and the preceding vehicle at the brake avoidance limit, the position of the adjacent vehicle, and the position of the boundary of the own traffic lane; moving, when the collision prediction time is the time of the brake avoidance limit or less, the own vehicle into the free space.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method and device for avoiding a collision in a vehicle. [Background technology]

[0002] Known technology relating to automatic driving of vehicles is one in which a vehicle performs steering operations to avoid a collision with a preceding vehicle based on the lateral speed of the preceding vehicle traveling in front of the vehicle (see, for example, Patent Document 1). In Patent Document 1, the lateral speed and acceleration of the preceding vehicle are calculated, and a decision is made as to whether the vehicle should be directed left or right to avoid collision depending on the direction and degree of the lateral speed and acceleration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 066646 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 only considers avoidance actions when the leading vehicle avoids an obstacle, that is, when lateral acceleration or speed occurs. Therefore, when the leading vehicle does not move lateral, such as by suddenly stopping, or when the lateral movement is delayed, avoidance becomes difficult and the possibility of a collision increases.

[0005] An object of the present invention is to provide a collision avoidance method and a collision avoidance device that reduce the possibility of a collision with a preceding vehicle. [Means for solving the problem]

[0006] The collision avoidance method of the present invention is a collision avoidance method that uses a computer to avoid a collision between the subject vehicle and a preceding vehicle, in which the computer calculates a collision prediction time based on the position and speed of the subject vehicle and the position and speed of the preceding vehicle, detects adjacent vehicles traveling in adjacent lanes and the boundaries of the lanes, selects a free space that is at a distance greater than or equal to a safety margin from the preceding vehicle based on the positions and speeds of the subject vehicle and the preceding vehicle at the time when the collision prediction time becomes the braking avoidance limit, the position of the adjacent vehicle, and the boundaries of the lanes, and moves the subject vehicle toward the selected free space when the collision prediction time becomes the braking avoidance time or less. [Effects of the Invention]

[0007] In the collision avoidance method of the present invention, a free space in which a collision with the preceding vehicle can be avoided is selected based on the relative position and relative speed between the host vehicle and the preceding vehicle at the braking avoidance limit, the position of an adjacent vehicle, and the boundary of a lane, and when the collision prediction time is equal to or less than the braking prediction limit, the host vehicle is braked and steered toward the free space. This reduces the possibility of the host vehicle colliding with the preceding vehicle regardless of whether the preceding vehicle is moving laterally. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a general configuration of a vehicle equipped with a collision avoidance device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing the configuration of a controller and the functional configuration of a processor according to the present embodiment. [Figure 3] FIG. 4 is a schematic diagram showing an example of a free space selected by a free space selection unit. [Figure 4] 4 is a flowchart showing an example of a rear-end collision avoidance method according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A collision avoidance method and a collision avoidance device according to an embodiment of the present disclosure will be described below. 1 is a schematic diagram showing the general configuration of a vehicle equipped with a collision avoidance device according to this embodiment. As shown in FIG. 1, the vehicle according to this embodiment includes a driving unit 10, an external environment recognition sensor 20, a driving measurement device 30, and a controller 40. The traveling drive unit 10 includes, for example, a drive source 101, a drive transmission mechanism 102, drive wheels 103, a steering mechanism 104, a braking mechanism 105, a drive control device 106, a steering control device 107, and a braking control device 108. The drive source 101 is composed of an electric motor, an engine, etc., and generates a drive force. The drive transmission mechanism 102 reduces the drive force of the drive source 101 at a predetermined gear ratio and transmits it to the drive wheels 103, driving the drive wheels 103 to run the vehicle. The steering mechanism 104 is a mechanism that controls the traveling direction of the vehicle by changing the angle of the drive wheels 103 (front wheels). The steering mechanism 104 can be exemplified by a well-known configuration, for example, by converting the rotation of the steering shaft into a linear direction using a steering box and transmitting it to a tie rod, which then changes the angle of the left and right drive wheels 103 (front wheels). The braking mechanism 105 is a mechanism for braking the running of the vehicle. There are no particular limitations on the braking mechanism 105, and various devices such as drum brakes, disc brakes, and engine brakes can be used.

[0010] The drive control device 106 controls the output of the drive source 101 and the gear ratio in the drive transmission mechanism 102 based on the accelerator operation by the user or a drive command from the controller 40, and causes the vehicle to run. The steering control device 107 controls the steering mechanism 104 based on the steering operation of the user or a steering command from the controller 40, and causes the vehicle to travel in a desired direction. The braking control device 108 controls the braking mechanism 105 based on the braking operation of the user or a braking command from the controller 40, and brakes the vehicle.

[0011] The external environment recognition sensor 20 is a sensor that detects objects around the vehicle, and may be, for example, a general imaging camera, a laser radar, a millimeter wave radar, or the like. Objects detected by the external environment recognition sensor 20 include, for example, vehicles around the host vehicle, marked lines printed on the road surface, and obstacles erected on the road. Vehicles around the host vehicle include a preceding vehicle traveling in front of the host vehicle in the lane in which the host vehicle is traveling (host lane), and an adjacent vehicle traveling in an adjacent lane adjacent to the host lane. Marked lines printed on the road surface include soft boundaries such as dividing lines (white lines, yellow lines, etc.) that indicate the boundaries of each lane. Obstacles erected on the road include hard boundaries such as guardrails that indicate the boundaries of lanes.

[0012] The travel measurement device 30 detects the travel state of the vehicle. Specifically, the travel measurement device 30 includes a speed sensor to detect the speed of the vehicle. The travel measurement device 30 also includes a receiver that receives satellite signals from the Global Navigation Satellite System (GNSS) to determine the current position of the vehicle. The travel measurement device 30 may also include an acceleration sensor to detect the acceleration of the vehicle, and may also detect various other information.

[0013] FIG. 2 is a block diagram showing the configuration of the controller 40 and the functional configuration of the processor 42 of this embodiment. The controller 40 is a computer that controls the automatic driving of the vehicle, and is communicably connected to the drive control device 106, the steering control device 107, the braking control device 108, the external environment recognition sensor 20, and the travel measurement device 30. The controller 40 is a computer and includes, for example, a storage unit 41 including a memory, a processor 42 including a CPU (Central Processing Unit), and an input / output interface (not shown). The processor 42 reads and executes various programs, such as an autonomous driving program, stored in the storage unit 41, thereby functioning as a host vehicle driving information acquisition unit 43, a preceding vehicle driving information acquisition unit 44, an adjacent vehicle detection unit 45, a lane boundary detection unit 46, and a driving control unit 50, as shown in Fig. 2. The driving control unit 50 functions as a normal driving control unit 51, an avoidance assistance control unit 52, and a control amount adjustment unit 53. The avoidance assistance control unit 52 functions as a path width acquisition unit 521, a collision prediction time calculation unit 522, a braking limit situation calculation unit 523, a free space selection unit 524, a priority determination unit 525, a braking request calculation unit 526, and a steering request calculation unit 527. Here, an example is shown in which the processor 42 executes a vehicle control program to realize the functional configurations of the host vehicle driving information acquisition unit 43, the preceding vehicle driving information acquisition unit 44, the adjacent vehicle detection unit 45, the lane boundary detection unit 46, and the driving control unit 50, but some or all of these may also be realized by individual hardware configurations.

[0014] The host vehicle travel information acquisition unit 43 acquires the position and speed of the host vehicle as host vehicle travel information from information about the surrounding conditions detected by the external environment recognition sensor 20 and various information measured by the travel measurement device 30. The host vehicle position may be calculated by receiving GNSS satellite signals to calculate the current longitude and latitude of the host vehicle, or may be calculated based on known objects detected by the external environment recognition sensor 20 to calculate, for example, the relative position of the host vehicle with respect to soft boundaries, hard boundaries, etc., or the relative position of the host vehicle with respect to other vehicles.

[0015] The leading vehicle travel information acquisition unit 44 acquires leading vehicle travel information relating to the travel state of the leading vehicle from various information relating to the travel state of the leading vehicle detected by the external environment recognition sensor 20. Specifically, the leading vehicle travel information acquisition unit 44 calculates the position of the leading vehicle relative to the host vehicle, the speed of the leading vehicle, and the acceleration of the leading vehicle as the leading vehicle travel information. Here, the position of the leading vehicle is calculated as the relative position of the leading vehicle relative to the host vehicle. Furthermore, the leading vehicle travel information acquisition unit 44 calculates, as the speed and acceleration of the leading vehicle, not only the speed and acceleration in the direction of travel of the leading vehicle along the direction in which the lane extends (lane direction), but also the lateral speed and lateral acceleration of the leading vehicle in the lateral direction perpendicular to the lane direction, i.e., the lane width direction.

[0016] The adjacent vehicle detection unit 45 detects the presence or absence of an adjacent vehicle and its position based on information about the surrounding conditions detected by the external environment recognition sensor 20. At this time, the adjacent vehicle detection unit 45 further detects whether the relative position of the adjacent vehicle to the host vehicle is moving away or approaching over time. If the relative positions of the host vehicle and the adjacent vehicle are moving away over time, it can be determined that the host vehicle can proceed into the adjacent lane, and if the relative positions of the host vehicle and the adjacent vehicle are approaching over time, it can be determined that there is a risk of contact with the adjacent vehicle if the host vehicle proceeds into the adjacent lane.

[0017] The lane boundary detection unit 46 detects lane boundaries. The lanes to be detected include at least the current lane and adjacent lanes adjacent to the current lane. As described above, the boundaries include soft boundaries printed on the road surface and hard boundaries installed on the road.

[0018] The driving control unit 50 outputs commands to the driving drive unit 10 based on a predetermined driving route to perform automatic driving of the vehicle, and also appropriately corrects the driving route according to the surrounding conditions detected by the external environment recognition sensor 20, etc. As described above, the traveling control unit 50 includes the normal driving control unit 51, the avoidance support control unit 52, and the control amount adjustment unit 53. The normal driving control unit 51 sets a route along which the vehicle will actually travel, for example, according to a route to a destination set by a navigation device (not shown), calculates a driving force, a steering amount, and a braking amount so that the vehicle travels along the route, and outputs the calculated driving force, steering amount, and braking amount to the control amount adjustment unit 53. When emergency avoidance is not required, the control amount adjustment unit 53 outputs a driving command, a steering command, and a braking command corresponding to the calculated driving force, steering amount, and braking amount to the drive control device 106, the steering control device 107, and the braking control device 108, respectively. As a result, the drive control device 106, to which the drive command has been input, outputs a driving force from the drive source in accordance with the drive command. Furthermore, the steering control device 107, to which the steering command has been input, controls the steering mechanism 104 in accordance with the steering command. Furthermore, the braking control device 108, to which a braking command has been input, controls the braking mechanism 105 in accordance with the braking command.

[0019] The avoidance assistance control unit 52 determines whether or not emergency avoidance is necessary in the event of a collision, and if emergency avoidance is necessary, sets an emergency avoidance destination and calculates the steering amount and braking amount for moving to and stopping at the emergency avoidance destination. As described above, the avoidance assistance control unit 52 includes the functional configuration of a path width acquisition unit 521, a collision prediction time calculation unit 522, a braking limit situation calculation unit 523, a free space selection unit 524, a priority determination unit 525, a steering request calculation unit 527, and a braking request calculation unit 526.

[0020] The path width acquisition unit 521 acquires the path width that the host vehicle can enter. The path width can be, for example, a dimension obtained by adding a predetermined margin to the vehicle width of the host vehicle, and may be stored in the storage unit 41 in advance.

[0021] The collision prediction time calculation unit 522 calculates a collision prediction time before the host vehicle collides with the preceding vehicle based on the host vehicle travel information and the preceding vehicle travel information. That is, the collision prediction time calculation unit 522 calculates a collision prediction time until the host vehicle collides with the preceding vehicle based on the relative position and relative speed of the preceding vehicle with respect to the host vehicle. The collision prediction time calculation unit 522 determines that there is a possibility of a collision if the speed of the preceding vehicle is slower than the speed of the host vehicle and calculates the collision prediction time. If the speed of the preceding vehicle is faster than the speed of the host vehicle or if the speeds are the same, it determines that there is no possibility of a collision.

[0022] The braking limit situation calculation unit 523 estimates the position, speed, and acceleration of the preceding vehicle relative to the subject vehicle at the timing when the predicted collision time reaches the braking avoidance limit, that is, the timing when the time reaches the limit for avoiding a collision by braking alone. At this time, the braking limit situation calculation unit 523 also estimates the lateral speed and lateral acceleration as the speed and acceleration of the preceding vehicle. This makes it possible to estimate the behavior of the preceding vehicle at the timing when the braking avoidance limit is reached, that is, to estimate whether the preceding vehicle is traveling straight along the subject vehicle's lane or is steering to the left or right.

[0023] The free space selection unit 524 selects an emergency avoidance destination (free space) to which the host vehicle should head when the host vehicle and the preceding vehicle approach each other and fall below the braking avoidance limit, based on the relative position and relative speed between the host vehicle and the preceding vehicle at the braking avoidance limit (the position and speed of the preceding vehicle at the braking avoidance limit, and the position and speed of the host vehicle at the braking avoidance limit), the presence or absence of an adjacent vehicle, the position of the adjacent vehicle if an adjacent vehicle is present, and the position of the boundary of the host lane. A free space is a space that is a predetermined safety margin away from the preceding vehicle and other obstacles (adjacent vehicles and hard boundaries) and has a width equal to or greater than the width of the path that the host vehicle can enter. The safety margin may be a preset distance, or a distance that changes depending on the speed of the host vehicle and the degree of road congestion. Furthermore, it is preferable that the free space selection unit 524 estimates the amount of movement of the preceding vehicle from the braking avoidance limit to the collision prediction time based on the lateral speed and lateral acceleration of the preceding vehicle at the estimated braking avoidance limit, and estimates the position of the preceding vehicle at the collision prediction time based on the amount of movement. This makes it possible to select a free space in which a collision of the host vehicle can be avoided based on the amount of movement of the preceding vehicle from the braking avoidance limit to the collision prediction time.

[0024] 3A and 3B are schematic diagrams showing examples of free spaces selected by the free space selection unit 524. FIG. 3A is a diagram showing an example of a free space 94A in the adjacent lane 82 selected when there is no adjacent vehicle 93. FIG. 3B is a diagram showing examples of free spaces 94B, 94C, and 94D near the own lane 81 selected when there is an adjacent vehicle 93. In FIG. 3, the own vehicle 91 is the vehicle of this embodiment shown in FIG. 1. When there is no adjacent vehicle 93 traveling in the adjacent lane 82, the free space selection unit 524 selects a free space 94A in the adjacent lane 82, as shown in Fig. 3(A). In this case, it is more preferable to select a free space 94A located farther away from the preceding vehicle 92 based on the boundary (soft boundary 83) of the adjacent lane 82 on the opposite side from the own lane 81 and the position of the preceding vehicle 92.

[0025] In determining whether or not an adjacent vehicle 93 is present in the adjacent lane 82, even if the adjacent vehicle 93 is detected, if the relative position of the adjacent vehicle 93 traveling in the adjacent lane 82 and the host vehicle 91 increases over time, it is determined that the adjacent vehicle 93 does not exist. For example, even if the adjacent vehicle 93 is present behind the host vehicle 91, if the speed of the adjacent vehicle 93 is slower than the speed of the host vehicle 91, the relative position of the adjacent vehicle 93 to the host vehicle 91 increases over time, and it is determined that the adjacent vehicle 93 does not exist. Also, even if the adjacent vehicle 93 is present ahead of the host vehicle 91, if the speed of the adjacent vehicle 93 is faster than the speed of the host vehicle 91, the relative position of the adjacent vehicle 93 to the host vehicle 91 increases over time, and it is determined that the adjacent vehicle 93 does not exist. On the other hand, if the relative positions of the adjacent vehicle 93 and the subject vehicle 91 become closer over time, it is determined that the adjacent vehicle 93 exists even if the distance to the adjacent vehicle 93 is large. For example, if the adjacent vehicle 93 exists behind the subject vehicle 91 and the speed of the adjacent vehicle 93 is faster than the speed of the subject vehicle 91, the relative position of the adjacent vehicle 93 to the subject vehicle 91 becomes closer over time, and it is determined that the adjacent vehicle 93 exists. Also, if the adjacent vehicle 93 exists ahead of the subject vehicle 91 and the speed of the adjacent vehicle 93 is slower than the speed of the subject vehicle 91, the relative position of the adjacent vehicle 93 to the subject vehicle 91 becomes closer over time, and it is determined that the adjacent vehicle 93 exists. Furthermore, when the external environment recognition sensor 20 cannot detect an adjacent vehicle due to obstruction by a large vehicle or the like, it is preferable to determine that an adjacent vehicle 93 is present.

[0026] Furthermore, when the free space selection unit 524 determines that an adjacent vehicle 93 is present, it selects a free space near the own lane 81 at a position different from that of the adjacent vehicle 93. Specifically, it selects one or more of the free spaces 94B, 94C, and 94D shown in FIG. 3(B) as the free space near the own lane 81. Here, the free space 94B is the space between the preceding vehicle 92 and the soft boundary 84 of the own lane 81. The soft boundary 84 of the own lane 81 is the soft boundary 84 on the opposite side of the adjacent lane 82 in which it is determined that the adjacent vehicle 93 exists. The free space 94C is the space between the leading vehicle 92 and the hard boundary 85 of the vehicle's own lane 81. The free space 94D is the space between the leading vehicle 92 and the adjacent vehicle 93.

[0027] Although one or more of free spaces 94B, 94C, and 94D are selected when an adjacent vehicle 93 is present, one or more of free spaces 94B, 94C, and 94D may also be selected when an adjacent vehicle 93 is not present.

[0028] The priority determination unit 525 determines the priority of each free space when multiple free spaces are selected by the free space selection unit 524. For example, in this embodiment, the priority determination unit 525 determines the priority in the following order: free space 94A in the adjacent lane 82, free space 94B between the preceding vehicle 92 and the soft boundary 84, free space 94C between the preceding vehicle 92 and the hard boundary 85, and free space 94D between the preceding vehicle 92 and the adjacent vehicle 93.

[0029] The braking request calculation unit 526 and the steering request calculation unit 527 correspond to the steering braking control unit of the present disclosure, and calculate a steering request value and a braking request value for causing the vehicle 91 to enter the free space with the highest priority when the predicted collision time becomes equal to or less than the braking avoidance limit.

[0030] When the steering demand calculation unit 527 and the braking demand calculation unit 526 do not calculate a steering demand value and a braking demand value, the control amount adjustment unit 53 outputs a driving command, a steering command, and a braking command corresponding to the driving force, steering amount, and braking amount calculated by the normal driving control unit 51 to the driving control device 106, the steering control device 107, and the braking control device 108, respectively. Furthermore, when the steering demand calculation unit 527 and the braking demand calculation unit 526 calculate a steering demand value and a braking demand value, the control amount adjustment unit 53 outputs the steering demand value and the braking demand value as a steering command and a braking command to the steering control device 107 and the braking control device 108. As a result, the host vehicle 91 is subjected to steering and braking control toward a free space based on the steering demand value and the braking demand value, thereby performing emergency avoidance.

[0031] [Collision avoidance method] Next, a collision avoidance method for the vehicle described above will be explained. FIG. 4 is a flowchart showing an example of a rear-end collision avoidance method according to this embodiment. Here, it is assumed that a route to a predetermined destination is set, and the normal driving control unit 51 of the driving control unit 50 sets the route of the vehicle 91 according to the actual traffic conditions and performs automatic driving.

[0032] In this embodiment, while the vehicle 91 is traveling by automatic driving, the vehicle traveling information acquisition unit 43 of the controller 40 continuously acquires vehicle traveling information such as the speed and acceleration of the vehicle 91 and the position of the vehicle 91 using various sensors that constitute the traveling measurement device 30 (step S1: vehicle traveling information acquisition step).

[0033] In addition, the preceding vehicle driving information acquisition unit 44, adjacent vehicle detection unit 45, and lane boundary detection unit 46 continuously acquire surrounding obstacles and lane boundaries using the external environment recognition sensor 20 (step S2: preceding vehicle driving information acquisition step, adjacent vehicle detection step, lane boundary detection step). That is, the preceding vehicle travel information acquisition unit 44 not only determines whether or not there is a preceding vehicle, but also acquires the position, speed, and acceleration of the preceding vehicle 92 if there is a preceding vehicle, based on information obtained from the external environment recognition sensor 20. This makes it possible to calculate the relative position and relative acceleration of the preceding vehicle 92 with respect to the host vehicle 91. Furthermore, the preceding vehicle travel information acquisition unit 44 also calculates the lateral speed and lateral acceleration as the speed and acceleration of the preceding vehicle 92. Furthermore, the adjacent vehicle detection unit 45 determines whether or not there is an adjacent vehicle 93 traveling in the adjacent lane 82, based on information obtained from the external environment recognition sensor 20. At this time, as described above, if it is difficult to confirm the adjacent vehicle 93 because the adjacent lane 82 is blocked, for example, the adjacent vehicle detection unit 45 determines that there is an adjacent vehicle 93. Furthermore, the adjacent vehicle detection unit 45 determines that there is an adjacent vehicle 93 if the relative positions of the host vehicle 91 and the adjacent vehicle 93 become closer over time, and if the relative positions of the adjacent vehicle 93 and the host vehicle 91 do not change much (they are moving at approximately the same speed). On the other hand, the adjacent vehicle detection unit 45 determines that there is no adjacent vehicle 93 if the relative positions of the host vehicle 91 and the adjacent vehicle 93 become farther apart over time, or if the adjacent vehicle 93 is not detected. The lane boundary detection unit 46 detects a soft boundary 84 of the current lane 81, a soft boundary 83 of an adjacent lane 82, and a hard boundary 85 of the current lane 81 based on information obtained from the external environment recognition sensor 20.

[0034] During the execution of the automatic driving, if there is a possibility of a collision between the host vehicle 91 and the preceding vehicle 92, the avoidance assistance control unit 52 of the driving control unit 50 performs the following processing to avoid the collision.

[0035] First, the collision prediction time calculation unit 522 calculates a collision prediction time based on the host vehicle travel information acquired in step S1, the preceding vehicle travel information acquired in step S2, and the preceding vehicle travel information acquired in step S2 (step S3: collision prediction time calculation step). Here, the collision prediction time is calculated when the speed of the preceding vehicle 92 is slower than the speed of the host vehicle 91, and the collision prediction time is not calculated when the speed of the preceding vehicle 92 is faster than the speed of the host vehicle 91 or the same speed as the host vehicle 91, or when there is no preceding vehicle 92. Therefore, when the speed of the preceding vehicle 92 is slower than the speed of the host vehicle 91 and the collision prediction time calculation unit 522 calculates the collision prediction time, it can be determined that there is a possibility of a collision between the host vehicle 91 and the preceding vehicle 92. Furthermore, the collision prediction time calculation unit 522 calculates a collision braking limit, which is the minimum time in which a collision between the host vehicle 91 and the preceding vehicle 92 can be avoided by braking alone. The collision braking limit can be calculated using known technology, for example, based on the relative speed between the host vehicle 91 and the preceding vehicle 92, the acceleration (deceleration) of the host vehicle 91 and the preceding vehicle 92, etc.

[0036] Thereafter, the braking limit situation calculation unit 523 estimates the traveling states (position, speed, and acceleration) of the host vehicle 91 and the preceding vehicle 92 at the timing when the collision braking limit is reached (step S4: braking limit situation calculation step). As described above, by continuously performing steps S1 and S2, it is possible to detect changes over time in the traveling information of the preceding vehicle, and this allows the braking limit situation calculation unit 523 to estimate the relative position and relative speed of the preceding vehicle 92 with respect to the host vehicle 91, and the lateral speed and lateral acceleration of the preceding vehicle 92 at the timing when the collision braking limit is reached.

[0037] Then, the free space selection unit 524 selects a free space near the own vehicle lane 81 and the adjacent lane 82 where a collision with the preceding vehicle can be avoided (step S5: free space selection step). As described with reference to FIG. 3, the free space selection unit 524 selects a plurality of free spaces around the own vehicle 91. That is, depending on whether or not there is an adjacent vehicle 93, if the adjacent lane 82 is usable, the free space selection unit 524 selects a free space 94A in the adjacent lane 82 between the leading vehicle 92 and the soft boundary 83 of the adjacent lane 82. Furthermore, if there is a space between the leading vehicle 92 and the soft boundary 84 of the own vehicle lane 81 that ensures a predetermined safety margin and is equal to or greater than the path width, the free space selection unit 524 selects the space as a free space 94B. Furthermore, if a predetermined safety margin is ensured between the leading vehicle 92 and the hard boundary 85 of the own vehicle lane 81 and there is a space that is equal to or greater than the width of the lane, the free space selection unit 524 selects the space as a free space 94C. Furthermore, if a predetermined safety margin is ensured between the leading vehicle 92 and the adjacent vehicle 93 and there is a space that is equal to or greater than the width of the lane, the free space selection unit 524 selects the space as a free space 94D.

[0038] Thereafter, the priority determination unit 525 determines the priority of the free spaces selected in step S5 (step S6). In this embodiment, as described above, the priority is determined in the following order: the free space 94A in the adjacent lane 82, the free space 94B between the preceding vehicle 92 and the soft boundary 84, the free space 94C between the preceding vehicle 92 and the hard boundary 85, and the free space 94D between the preceding vehicle 92 and the adjacent vehicle 93.

[0039] Then, the steering demand calculation unit 527 and the braking demand calculation unit 526 calculate the steering demand value and the braking demand value for entering the free space with the highest priority at the timing when the collision prediction time becomes equal to or less than the braking avoidance limit, more preferably at the timing when the collision prediction time becomes equal to or less than the braking avoidance limit (step S7).

[0040] Incidentally, when the normal driving control unit 51 is controlled to travel following the preceding vehicle 92, normally, even if the preceding vehicle 92 decelerates, if the collision avoidance time is equal to or greater than the braking avoidance limit, there is a high possibility that the collision can be avoided by braking alone. However, for example, when the preceding vehicle 92 suddenly decelerates while traveling at high speed, the time to avoid a collision may become less than the braking limit, making it difficult to avoid the collision by braking alone. Therefore, in this embodiment, the avoidance assistance control unit 52 determines whether or not a collision between the host vehicle 91 and the preceding vehicle 92 can be avoided by braking alone, based on the collision prediction time and the braking avoidance limit, that is, whether or not the collision prediction time is equal to or greater than the braking avoidance limit (step S8). If the determination in step S8 is YES (if the collision can be avoided by braking alone), the normal driving control unit 51 performs deceleration processing, and is controlled to avoid the collision by braking (step S9). In this case, the control amount adjustment unit 53 outputs a braking command according to the braking amount calculated by the normal driving control unit 51 to the braking control device 108, and the braking mechanism 105 brakes the host vehicle 91.

[0041] On the other hand, if the determination in step S8 is NO, the control amount adjustment unit 53 outputs a steering command and a braking command according to the steering demand value and the braking demand value calculated in step S7 to the steering control device 107 and the braking control device 108 (step S10). As a result, the steering mechanism 104 and the braking mechanism 105 perform travel control so as to make the host vehicle 91 enter the free space with the highest priority, and control is performed so as to avoid a collision with the leading vehicle 92.

[0042] [Effects of this embodiment] In this embodiment, controller 40 configured by a computer functions as host vehicle driving information acquisition unit 43, preceding vehicle driving information acquisition unit 44, adjacent vehicle detection unit 45, lane boundary detection unit 46, collision prediction time calculation unit 522, braking limit situation calculation unit 523, free space selection unit 524, steering request calculation unit 527, and braking request calculation unit 526. Controller 40 performs at least a host vehicle driving information acquisition step (step S1), a preceding vehicle driving information acquisition step (step S2), an adjacent vehicle detection step (step S2), a boundary detection step (step S2), a collision prediction time calculation step (step S3), a braking limit situation calculation step (step S4), a free space selection step (step S5), and a braking steering control step (steps S7 to S10). In step S1, the host vehicle travel information acquisition unit 43 acquires host vehicle travel information relating to at least the position and speed of the host vehicle 91. In step S2, the preceding vehicle travel information acquisition unit 44 acquires preceding vehicle information including at least the position and speed of the preceding vehicle 92. In step S3, the adjacent vehicle detection unit 45 detects an adjacent vehicle 93 traveling in the adjacent lane 82. In step S3, the collision prediction time calculation unit 522 calculates a collision prediction time based on the host vehicle travel information and the preceding vehicle travel information. In step S4, the collision prediction time calculation unit 522 estimates the position and speed of the preceding vehicle 92 and the position and speed of the host vehicle 91 at the timing when the collision prediction time becomes the braking avoidance limit. In step S5, the free space selection unit 524 selects a free space that ensures a distance of at least a predetermined safety margin from the position of the preceding vehicle 92 and that the host vehicle 91 can enter, based on the position and speed of the preceding vehicle 92 at the braking avoidance limit, the position and speed of the host vehicle 91 at the braking avoidance limit, the position of the adjacent vehicle 93, and the boundary of the host lane 81. In steps S7 to S10, the braking request calculation unit 526 and the steering request calculation unit 527 calculate a steering request value and a braking request value for moving the host vehicle 91 toward the free space when the collision prediction time is equal to or less than the braking avoidance limit, and cause the host vehicle 91 to enter the free space. This allows the host vehicle 91 to move to a free space where it will not collide with the preceding vehicle 92 regardless of whether the preceding vehicle 92 moves laterally, thereby reducing the possibility of a collision between the host vehicle 91 and the preceding vehicle 92.

[0043] In this embodiment, if an adjacent vehicle 93 is not detected in step S2, the free space selection unit 524 selects a free space 94A in the adjacent lane 82 in step S5. When there is no adjacent vehicle 93, the vehicle 91 can be evacuated to the safe free space 94A in the adjacent lane 82 in which the preceding vehicle 92 can keep the shortest distance by selecting the free space 94A in the adjacent lane 82 in which the preceding vehicle 92 can keep the shortest distance.

[0044] At this time, the free space selection unit 524 selects a free space 94A between the preceding vehicle 92 and the boundary (soft boundary 83) of the adjacent lane 82 on the opposite side of the own lane 81. This allows the host vehicle 91 to move to a position farther away from the leading vehicle 92, thereby further reducing the possibility of a collision with the leading vehicle 92.

[0045] In this embodiment, the free space selection unit 524 selects a free space 94A in the adjacent lane 82 in step S5 when the relative positions of the host vehicle 91 and the adjacent vehicle 93 become increasingly distant over time. Examples of cases in which the relative positions of the host vehicle 91 and the adjacent vehicle 93 become more distant over time include a pattern in which the adjacent vehicle 93 is ahead of the host vehicle 91 and is traveling faster than the host vehicle 91, and a pattern in which the adjacent vehicle 93 is behind the host vehicle 91 and is traveling slower than the host vehicle 91. In these patterns, the adjacent vehicle 93 moves away from the host vehicle 91. Therefore, even if a space is created in the adjacent lane 82 and it is determined that there is no adjacent vehicle 93, and the host vehicle 91 is evaded into the free space 94A in the adjacent lane 82, the possibility of a collision between the host vehicle 91 and the adjacent vehicle 93 is low. Furthermore, by selecting a relatively wide free space 94A in the adjacent lane 82, the possibility of a collision between the host vehicle 91 and the preceding vehicle 92 can be further reduced.

[0046] In this embodiment, if an adjacent vehicle 93 is detected in step S2, the free space selection unit 524 selects a free space near the own lane 81 at a position different from the adjacent lane 82 in step S5. This makes it possible to select a free space where the possibility of collision between the vehicle 91 and the adjacent vehicle 93 is low, and also where the possibility of collision between the vehicle 91 and the leading vehicle 92 is low.

[0047] In this embodiment, if the relative positions of the vehicle 91 and the adjacent vehicle 93 become closer over time, the free space selection unit 524 selects a free space near the vehicle lane 81 at a position different from the adjacent lane 82 in step S5. Examples of cases in which the relative positions of the host vehicle 91 and the adjacent vehicle 93 become closer over time include a pattern in which the adjacent vehicle 93 is ahead of the host vehicle 91 and is traveling slower than the host vehicle 91, and a pattern in which the adjacent vehicle 93 is behind the host vehicle 91 and is traveling faster than the host vehicle 91. In these patterns, even if the adjacent vehicle 93 is not traveling near the host vehicle 91 at the time the adjacent vehicle 93 is detected, there is a possibility that the adjacent vehicle 93 will be located near the host vehicle 91 when the host vehicle 91 performs a collision avoidance operation. Therefore, in such cases, by determining that the adjacent vehicle 93 is present and selecting a free space in a position other than the adjacent lane 82, it is possible to reduce both the possibility of a collision between the host vehicle 91 and the preceding vehicle 92 and the possibility of a collision between the host vehicle 91 and the adjacent vehicle 93.

[0048] In this embodiment, in step S5, the free space selection unit 524 selects a free space 94B between the leading vehicle 92 and the soft boundary 84 of the own lane 81. When an adjacent vehicle 93 is traveling in the adjacent lane 82, a free space 94B is selected between the leading vehicle 92 and the soft boundary 84 of the own vehicle's lane 81. This reduces the possibility of a collision with the adjacent vehicle 93, and also reduces the possibility of a collision with the leading vehicle 92. In particular, by selecting the free space 94B between the adjacent lane 82 and the soft boundary 84 on the opposite side of the own vehicle's lane 81, it is possible to distance the own vehicle 91 from the adjacent vehicle 93. In other words, when the own vehicle 91 is evaded toward the adjacent lane 82, the risk of a collision with the adjacent vehicle 93 increases in addition to the leading vehicle 92. In contrast, by evading the own vehicle 91 to a side away from the adjacent lane 82, it is only necessary to consider the possibility of a collision with the leading vehicle 92, and the possibility of a collision between the own vehicle 91 and the leading vehicle 92 can be further reduced.

[0049] In this embodiment, in step S5, the free space selection unit 524 selects a free space 94C between the leading vehicle 92 and the hard boundary 85 of the own lane 81. As described above, when an adjacent vehicle 93 is traveling in the adjacent lane 82, the possibility of a collision with the adjacent vehicle 93 can be reduced, and the possibility of a collision with the preceding vehicle 92 can also be reduced. Furthermore, if there is insufficient space between the soft boundary 84 and the preceding vehicle 92, the possibility of a collision with the preceding vehicle 92 increases even if a free space is set between the soft boundary 84 and the preceding vehicle 92. In contrast, there is often a wider space between the preceding vehicle 92 and the hard boundary 85, which is erected at a position farther from the own lane 81 than the soft boundary 84, and the hard boundary 85 than the space between the soft boundary 84 and the preceding vehicle 92, and by making this area the free space 94C, the possibility of a collision with the preceding vehicle 92 can be further reduced.

[0050] In this embodiment, the free space selection unit 524 selects the free space 94D between the adjacent vehicle 93 and the leading vehicle 92 in step S5. When the leading vehicle 92 is positioned on the opposite side of the adjacent lane 82 or when the leading vehicle 92 is predicted to move away from the adjacent lane 82, a space is created between the leading vehicle 92 and the adjacent vehicle 93. In this case, by selecting a free space 94D between the leading vehicle 92 and the adjacent vehicle 93, the possibility of a collision with the leading vehicle 92 can be reduced. Furthermore, the free space 94D is close to the leading vehicle 92 and the adjacent vehicle 93, and by selecting such a space in advance as one of the candidates, the options for emergency avoidance can be increased. Increasing the options for free spaces makes it possible to flexibly select a free space with a lower possibility of collision that corresponds to the driving state of the leading vehicle 92 and the adjacent vehicle 93, thereby further reducing the possibility of a collision with the leading vehicle 92 and the adjacent vehicle 93.

[0051] In the present embodiment, the controller 40 also functions as a priority determination unit 525. When a plurality of free spaces are selected by the free space selection unit 524 in step S5, the priority determination unit 525 determines the priority of the selected free spaces in step S7. That is, the priority determination unit 525 sets the priority order in the following order: free space 94A in the adjacent lane 82, free space 94B between the preceding vehicle 92 and the soft boundary 84, free space 94C between the preceding vehicle 92 and the hard boundary 85, and free space 94D between the preceding vehicle 92 and the adjacent vehicle 93. Then, the steering demand calculation unit 527 and the braking demand calculation unit 526 calculate a braking demand value and a steering demand value for the host vehicle 91 moving toward the free space with the highest priority, whereby the host vehicle 91 moves toward the free space with the highest priority in step S10. In other words, when it is determined that there is no adjacent vehicle 93, there is sufficient space in the adjacent lane 82 for the preceding vehicle 92 to avoid it, and the free space 94A in the adjacent lane 82 is the location where the possibility of a collision between the host vehicle 91 and the preceding vehicle 92 is lowest. Therefore, by giving the highest priority to the free space 94A, the possibility of a collision with the preceding vehicle 92 can be further reduced. When an adjacent vehicle 93 is present in the adjacent lane 82, it is necessary to avoid a collision not only with the preceding vehicle 92 but also with the adjacent vehicle 93. In this case, the free space 94B between the preceding vehicle 92 and the soft boundary 84 and the free space 94B between the preceding vehicle 92 and the soft boundary 84 or the hard boundary 85 are closer to the preceding vehicle 92 than the free space 94A in the adjacent lane 82, but they can reduce the possibility of a collision with the adjacent vehicle 93 and also reduce the possibility of a collision with the preceding vehicle 92. However, for the free space 94C between the adjacent lane 82 and the hard boundary 85, it is necessary to consider a collision with the hard boundary 85 in addition to the preceding vehicle 92. The free space 94D between the leading vehicle 92 and the adjacent vehicle 93 must be a space that will prevent collisions between both the leading vehicle 92 and the adjacent vehicle 93. Therefore, by setting the priority order as follows: free space 94A in the adjacent lane 82, free space 94B between the preceding vehicle 92 and the soft boundary 84, free space 94C between the preceding vehicle 92 and the hard boundary 85, and free space 94D between the preceding vehicle 92 and the adjacent vehicle 93, a free space with a higher degree of safety can be selected as the avoidance destination.

[0052] In this embodiment, in step S2, the preceding vehicle driving information acquisition unit 44 calculates the lateral speed and lateral acceleration of the preceding vehicle 92, and in step S4, the braking limit situation calculation unit 523 estimates the driving situation of the preceding vehicle 92 based on the lateral speed and lateral acceleration of the preceding vehicle 92. This allows the braking limit situation calculation unit 523 to estimate in which lateral direction the preceding vehicle 92 will move at the braking avoidance limit.

[0053] Then, the free space selection unit 524 calculates the amount of movement of the preceding vehicle 92 from the braking avoidance limit to the collision prediction time based on the lateral speed and lateral acceleration of the preceding vehicle 92, and selects a free space based on the position of the preceding vehicle 92 to which it will move based on the amount of movement. By selecting a free space based on the estimated position of the preceding vehicle 92 after the collision prediction time has elapsed, rather than the position of the preceding vehicle 92 at the braking avoidance limit or the position of the preceding vehicle 92 detected by the external environment recognition sensor 20, it is possible to properly determine to which position the vehicle 91 should be moved after the collision prediction time has elapsed in order to further reduce the possibility of a collision, and to select the optimal free space.

[0054] [Variations] The present invention is not limited to the above-described embodiment, but also includes the following modifications within the scope of achieving the object of the present invention.

[0055] [Variation 1] In the above embodiment, an adjacent lane 82 exists on one side of the own lane 81 (the left in the example of FIG. 3 ). However, when adjacent lanes 82 exist on the left and right sides of the own lane 81, a free space is selected based on the presence or absence of adjacent vehicles 93 in both adjacent lanes 82. When an adjacent vehicle 93 does not exist in one adjacent lane 82, the free space selection unit 524 selects a free space 94A in the adjacent lane 82 on the side where no adjacent vehicle 93 exists, as in the above embodiment. When an adjacent vehicle 93 does not exist in both adjacent lanes 82, the free space selection unit 524 selects a free space 94A in both adjacent lanes 82. In this case, priority is given to the free space 94A in the adjacent lane 82 on the opposite side from the predicted position of the leading vehicle 92 after the collision prediction time has elapsed. If there is no adjacent vehicle 93, the priority of either the free space 94B or the free space 94C is determined.

[0056] [Variation 2] In the above embodiment, the priority determination unit 525 sets priorities in the following order: the free space 94A in the adjacent lane 82, the free space 94B between the preceding vehicle 92 and the soft boundary 84, the free space 94C between the preceding vehicle 92 and the hard boundary 85, and the free space 94D between the preceding vehicle 92 and the adjacent vehicle 93. However, the present invention is not limited to this. The priority determination unit 525 may change the priorities based on the estimated position of the preceding vehicle 92 at the collision prediction time or the width of the free space. For example, even if it is estimated that the preceding vehicle 92 will move in the opposite direction from the adjacent lane 82 and there are free spaces 94B, 94C between the preceding vehicle 91 and the soft boundary 84 or hard boundary 85 on the opposite side of the preceding lane 81 from the adjacent lane 82 and the preceding vehicle 92, the free space 94D between the preceding vehicle 92 and the adjacent vehicle 93 may be given priority if the approach width of the free space 94D is wider. Alternatively, the priority may be set in descending order of the approach width among the free spaces 94B, 94C, and 94D.

[0057] [Variation 3] In the above embodiment, multiple free spaces are selected regardless of whether or not there is an adjacent vehicle 93 in the adjacent lane 82. However, if there is no adjacent vehicle 93, the free space 94A in the adjacent lane 82 may be determined as the space for collision avoidance without selecting another free space.

[0058] [Variation 4] In the above embodiment, an example is shown in which it is determined that an adjacent vehicle 93 does not exist when the relative position between the adjacent vehicle 93 in the adjacent lane 82 and the own vehicle 91 becomes distant, but it may also be determined that an adjacent vehicle 93 exists when the adjacent vehicle 93 is detected regardless of a change in the relative position between the adjacent vehicle 93 and the own vehicle 91. [Explanation of symbols]

[0059] 10...driving unit, 20...external environment recognition sensor, 30...driving measurement device, 40...controller, 41...memory unit, 42...processor, 43...subject vehicle driving information acquisition unit, 44...preceding vehicle driving information acquisition unit, 45...adjacent vehicle detection unit, 46...lane boundary detection unit, 50...driving control unit, 51...normal driving control unit, 52...avoidance assistance control unit, 53...control amount adjustment unit, 81...subject vehicle lane, 82...adjacent lane, 83, 84...soft boundary, 85...hard boundary, 91...subject vehicle, 92...preceding vehicle, 93...adjacent vehicle, 94A, 94B, 94C, 94D...free space, 522...collision prediction time calculation unit, 523...braking limit situation calculation unit, 524...free space selection unit, 525...priority determination unit, 526...braking request calculation unit, 527...steering request calculation unit.

Claims

1. 1. A collision avoidance method for avoiding a collision of a host vehicle with a preceding vehicle traveling ahead of the host vehicle using a computer, comprising: a host vehicle travel information acquisition step of acquiring the position and speed of the host vehicle; a preceding vehicle travel information acquisition step for acquiring the position and speed of the preceding vehicle; a collision prediction time calculation step of calculating a collision prediction time based on the position and speed of the host vehicle and the position and speed of the preceding vehicle; an adjacent vehicle detection step of detecting an adjacent vehicle that is another vehicle traveling in an adjacent lane adjacent to the own lane in which the own vehicle is traveling; a lane boundary detection step of detecting lane boundaries; a braking limit state calculation step of estimating a position and a speed of the preceding vehicle at a timing when the collision prediction time becomes a braking avoidance limit, and a position and a speed of the host vehicle at the braking avoidance limit; a free space selection step of selecting a free space into which the host vehicle can enter and which ensures a distance of at least a predetermined safety margin from the position of the preceding vehicle, based on the position and speed of the preceding vehicle at the braking avoidance limit, the position and speed of the host vehicle at the braking avoidance limit, the position of the adjacent vehicle, and the position of the boundary of the host lane; a braking / steering control step of moving the host vehicle toward the free space when the position and speed of the host vehicle and the collision prediction time are equal to or less than the braking avoidance limit; A collision avoidance method that implements the above.

2. If the adjacent vehicle is not detected in the adjacent vehicle detection step, the free space in the adjacent lane is selected in the free space selection step. The collision avoidance method according to claim 1 .

3. In the free space selection step, the free space between the preceding vehicle and the boundary of the adjacent lane on the opposite side to the own lane is selected. The collision avoidance method according to claim 2 .

4. When the relative positions of the host vehicle and the adjacent vehicle become increasingly distant over time, the free space selection step selects the free space in the adjacent lane. The collision avoidance method according to claim 2 .

5. When the adjacent vehicle is detected in the adjacent vehicle detection step, the free space selection step selects the free space near the own vehicle lane at a position different from the adjacent lane. The collision avoidance method according to claim 1 .

6. When the relative positions of the own vehicle and the adjacent vehicle become closer over time, the free space selection step selects the free space near the own vehicle lane at a position different from the adjacent lane. The collision avoidance method according to claim 5.

7. The boundaries include soft boundaries printed on the road surface and hard boundaries erected on the road surface, In the free space selection step, the free space is selected between the preceding vehicle and the soft boundary of the own lane. The collision avoidance method according to claim 6.

8. The boundaries include soft boundaries printed on the road surface and hard boundaries erected on the road surface, In the free space selection step, the free space between the preceding vehicle and the hard boundary of the own lane is selected. The collision avoidance method according to claim 6.

9. In the free space selection step, the free space between the adjacent vehicle and the preceding vehicle is selected. The collision avoidance method according to claim 6.

10. The boundaries include soft boundaries printed on the road surface and hard boundaries erected on the road surface, When a plurality of free spaces are detected in the free space selection step, the brake steering control step moves the host vehicle toward a free space in the following order of priority: the free space in the adjacent lane, the free space between the preceding vehicle and the soft boundary of the host vehicle's lane, the free space between the preceding vehicle and the hard boundary of the host vehicle's lane, and the free space between the adjacent vehicle and the preceding vehicle. The collision avoidance method according to claim 1 .

11. In the preceding vehicle driving information acquisition step, information on the position and speed of the preceding vehicle is acquired from an external environment recognition sensor that detects obstacles around the host vehicle, and a lateral speed and a lateral acceleration of the preceding vehicle are calculated, with a direction perpendicular to a lane direction in which the host vehicle lane extends being defined as a lateral direction; In the braking limit state calculation step, a traveling state of the preceding vehicle is estimated based on the lateral speed and the lateral acceleration of the preceding vehicle. The collision avoidance method according to claim 1 .

12. In the free space selection step, a movement amount of the preceding vehicle from the braking avoidance limit to the collision prediction time is calculated based on the lateral speed and the lateral acceleration of the preceding vehicle, and the free space is selected based on the distance between the preceding vehicle and the boundary or the relative distance between the preceding vehicle and the adjacent vehicle and the movement amount. The collision avoidance method of claim 11.

13. a host vehicle travel information acquisition unit that acquires the position and speed of the host vehicle; a preceding vehicle travel information acquisition unit that acquires the position and speed of a preceding vehicle traveling ahead of the host vehicle; a collision prediction time calculation unit that calculates a collision prediction time based on the position and speed of the host vehicle and the position and speed of the preceding vehicle; an adjacent vehicle detection unit that detects adjacent vehicles that are other vehicles traveling in adjacent lanes adjacent to the lane in which the host vehicle is traveling; a lane boundary detection unit that detects lane boundaries; a braking limit state calculation unit that estimates a position and a speed of the preceding vehicle at a timing when the collision prediction time becomes a braking avoidance limit, and a position and a speed of the host vehicle at the braking avoidance limit; a free space selection unit that selects a free space into which the host vehicle can enter while ensuring a distance of at least a predetermined safety margin from the position of the preceding vehicle, based on the position and speed of the preceding vehicle at the braking avoidance limit, the position and speed of the host vehicle at the braking avoidance limit, the position of the adjacent vehicle, and the position of the boundary of the host lane; a braking / steering control unit that calculates a braking demand value and a steering demand value for moving the host vehicle toward the free space at a timing when a collision prediction time calculated based on a position and a speed of the host vehicle and a position and a speed of the preceding vehicle becomes equal to or less than the braking avoidance limit; A collision avoidance device comprising:

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