Route generating apparatus and route generating method

Abstract

A path generating device (100) includes: a detection unit (9) that detects an object in a front region of a host vehicle (1); a front recognition unit (11) that recognizes another vehicle traveling on an adjacent lane adjacent to a travel lane in which the host vehicle travels, among the objects detected by the detection unit (9); a reference path generating unit (12) that generates a reference path of the host vehicle on the travel lane; a safety region setting unit (13) that sets a safety region from a side end portion of the another vehicle recognized by the front recognition unit (11) toward the travel lane; and a target path generating unit (14) that generates a target path of the host vehicle based on the reference path generated by the reference path generating unit (12). The target path generating unit sets the reference path as the target path within a prescribed interval in front of the host vehicle, corrects the reference path to generate the target path in such a manner that the safety region set by the safety region setting unit is ensured between the host vehicle and the another vehicle recognized by the front recognition unit in front of the prescribed interval.

Description

Technical Field

[0001] This invention relates to a path generation device and a path generation method for generating a target path for a vehicle with autonomous driving and driving assistance functions. Background Technology

[0002] As such a device, there are known driving assistance devices that set the steering angle of the vehicle based on the identified white line (see, for example, Patent Document 1). In the device described in Patent Document 1, it is set to predict that there will be a forward gaze point of the vehicle after a preset prediction time, and when there is an overtaking vehicle in the adjacent lane behind the vehicle, the forward gaze point is shifted in a direction away from the overtaking vehicle.

[0003] By popularizing vehicles equipped with autonomous driving and driver assistance functions, the overall safety and convenience of the transportation society can be improved, leading to a sustainable transportation system. Furthermore, by enhancing the efficiency and smoothness of transportation, CO2 emissions can be reduced, lessening the environmental impact.

[0004] However, when the target path is shifted away from the overtaking vehicle by a device as described in Patent Document 1, the driving path may change suddenly depending on when the overtaking vehicle is identified, which may cause discomfort to the occupants.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-129021 (JP2014-129021A). Summary of the Invention

[0008] One technical solution of the present invention is a path generation device for generating a target path for a vehicle, comprising: a sensor that detects objects in the area in front of the vehicle; and an electronic control unit having a processor and a memory connected to the processor. The processor is configured to identify other vehicles traveling in an adjacent lane adjacent to the vehicle's lane among the objects detected by the sensor, generate a reference path for the vehicle in the driving lane, set a safety zone from the side of other vehicles toward the driving lane, and generate a target path for the vehicle based on the reference path. Generating the target path includes: setting the reference path as the target path within a predetermined interval in front of the vehicle, modifying the reference path in a manner that ensures a safety zone between the vehicle and other vehicles ahead of the predetermined interval, and generating the target path.

[0009] Another technical solution of the present invention is a path generation method for generating a target path for a vehicle, comprising: identifying other vehicles traveling in an adjacent lane adjacent to the driving lane of the vehicle among objects in the area in front of the vehicle detected by a detection unit; generating a reference path for the vehicle in the driving lane; setting a safety zone from the side of the other vehicles toward the driving lane; and generating a target path for the vehicle based on the reference path. Generating the target path includes: setting the reference path as the target path within a predetermined interval in front of the vehicle; modifying the reference path in a manner that ensures a safety zone between the vehicle and other vehicles ahead of the predetermined interval; and generating the target path. Attached Figure Description

[0010] The objectives, features, and advantages of the present invention are further illustrated by the following description of embodiments in conjunction with the accompanying drawings.

[0011] Figure 1 It is a diagram used to illustrate the target path.

[0012] Figure 2 It is a diagram used to illustrate the changes in the target path.

[0013] Figure 3 This is a block diagram that schematically illustrates the main components and processing flow of a path generation apparatus according to an embodiment of the present invention.

[0014] Figure 4A It is used to explain by Figure 3 The baseline path generation unit and the target path generation unit generate the baseline path and target path graphs.

[0015] Figure 4B It is shown Figure 4A A diagram of a variation.

[0016] Figure 5 This is a flowchart illustrating the path generation process of a path generation apparatus according to an embodiment of the present invention. Detailed Implementation

[0017] The following is for reference Figures 1-5 Embodiments of the present invention will be described. The path generation device of the present invention is applied to a vehicle with driving assistance functions to generate a target path (target driving trajectory) for the vehicle. This driving assistance function controls driving actuators to assist the driver or enable the vehicle to drive automatically. In this embodiment, "driving assistance" includes driving assistance that assists the driver's driving operations and automatic driving that enables the vehicle to drive automatically without the driver's driving operations, equivalent to Levels 1 to 4 of automatic driving as defined by SAE, with "automatic driving" equivalent to Level 5 automatic driving.

[0018] Figure 1 and Figure 2 This diagram illustrates a driving scenario where vehicle 1 travels along the centerline 2C of lane 2. In this case, a baseline path 3a is generated, for example, along the centerline 2C of lane 2, based on the recognition results of the driving lane 2 ahead of the vehicle by a camera or the like. Furthermore, based on the recognition results of other vehicles 4a and 4b traveling in adjacent lanes 5a and 5b adjacent to the driving lane 2 of vehicle 1, the baseline path 3a is modified as needed to generate the final target path 3b. More specifically, the baseline path 3a is modified to ensure a defined safety zone 6a and 6b between vehicle 1 and other vehicles 4a and 4b, thus generating the target path 3b. The baseline path 3a and the target path 3b are generated and updated every unit of time based on the latest recognition results.

[0019] During driver assistance or autonomous driving, in addition to controlling the steering mechanism of vehicle 1 to ensure it travels along the target path 3b, the drive and braking mechanisms are also controlled to adjust the vehicle speed based on the distance to other vehicles 4a and 4b, thus avoiding collisions with them. Therefore, even if the target path 3b is generated without considering safety zones 6a and 6b, safety can be ensured. Safety zones 6a and 6b are designed to alleviate the anxiety felt by occupants when vehicle 1 is close to other vehicles 4a and 4b.

[0020] However, as Figure 2 As illustrated, when a large truck or other vehicle 4a traveling close to the lane 2 of vehicle 1 overtakes vehicle 1, the target path 3b may suddenly change immediately after the overtake, potentially causing unease among the occupants. Specifically, if the latest identification result immediately after the overtake determines that there is no safe zone 6a between vehicle 1 and other vehicles 4a, the target path 3b is suddenly changed by correcting the reference path 3a (the immediate target path 3b) to ensure the safe zone 6a. Therefore, in this embodiment, the path generation device is configured as follows to suppress such sudden changes in the target path 3b.

[0021] Figure 3 This is a block diagram that schematically illustrates an example of the main components and processing flow of a path generation apparatus (hereinafter referred to as apparatus) 100 according to an embodiment of the present invention. Figure 3As shown, the device 100 is mainly composed of an electronic control unit (ECU) 10. The ECU 10 is a computer that includes a CPU (processor), RAM (random access memory), ROM (read-only memory), I / O interfaces, and other peripheral circuits. For example, the ECU 10 is configured as part of a group of multiple ECUs mounted on the vehicle 1 and controlling the operation of the vehicle 1. Figure 3 The process, for example, begins when vehicle 1 is started and ECU 10 is activated, and is repeated at a predetermined interval.

[0022] The driving actuator 7, vehicle speed sensor 8, and external sensor 9 mounted on the vehicle 1 are connected to the ECU 10. The driving actuator 7 includes a drive mechanism such as an engine or electric motor that drives the vehicle 1, a braking mechanism such as a brake that brakes the vehicle 1, and a steering mechanism such as a steering gear that steers the vehicle 1. The vehicle speed sensor 8 is, for example, a wheel speed sensor that detects the rotational speed of the wheels, and detects the vehicle speed V.

[0023] External sensor 9 detects external conditions, including the position of objects in the area in front of vehicle 1. External sensor 9 includes a camera 9a with an imaging element such as a CCD (charge-coupled device) or CMOS (complementary metal-oxide-semiconductor) to capture images of the area in front of vehicle 1, and a distance detection unit 9b that detects the distance from vehicle 1 to objects in the area in front. The distance detection unit 9b may be, for example, a millimeter-wave radar that illuminates millimeter waves (radio waves) and determines the distance and direction to the object based on the time it takes for the illuminated wave to travel from the object. Alternatively, the distance detection unit 9b may be a lidar (LiDAR) system that illuminates a laser beam and determines the distance and direction to the object based on the time it takes for the laser beam to travel from the object.

[0024] The ECU 10 has a functional structure that includes a forward recognition unit 11, a reference path generation unit 12, a safety zone setting unit 13, a target path generation unit 14, and a driving control unit 15 as its computing unit. That is, the computing unit of the ECU 10 functions as the forward recognition unit 11, the reference path generation unit 12, the safety zone setting unit 13, the target path generation unit 14, and the driving control unit 15.

[0025] The forward recognition unit 11 identifies the positions of road markings, curbs, guardrails, etc., on the road in front of the vehicle 1, centered on the direction of travel of the vehicle 1, based on signals from the external sensor 9. This allows it to identify the driving lane 2 of the vehicle 1 and adjacent lanes 5a and 5b. Furthermore, it identifies other vehicles 4a and 4b by recognizing the positions of their outlines in adjacent lanes 5a and 5b.

[0026] Figure 4AThis diagram illustrates the generation of a reference path 3a and a target path 3b by the reference path generation unit 12 and the target path generation unit 14. The reference path generation unit 12 generates a reference path 3a for the vehicle 1 in the driving lane 2 based on the recognition result of the forward recognition unit 11. The general road shape is designed using a spiral curve with curvature varying proportionally, and a portion of the spiral curve corresponding to the road shape can be approximated using higher-order functions such as cubic functions.

[0027] Based on the recognition result from the forward recognition unit 11, the reference path generation unit 12 determines the direction of travel of the vehicle 1 relative to the driving lane 2. Taking the current location of the vehicle 1 as the origin O and the determined direction of travel as the X-axis, it derives a cubic function F(X) representing the centerline 2C of the driving lane 2. That is, using curve fitting methods such as the least squares method, it derives the cubic function F(X) of the following equations (i) and (ii) that approximate the left and right road markings (or curbs, guardrails, etc.) 2L and 2R recognized by the forward recognition unit 11. L (X), F R (X).

[0028] F L (X)=C 3L X 3 +C 2L X 2 +C 1L X+C 0L (i)

[0029] F R (X)=C 3R X 3 +C 2R X 2 +C 1R X+C 0R (ii)

[0030] Next, based on the cubic function F corresponding to the left and right road markings 2L and 2R... L (X), F R (X), derive the cubic function F(X) of equation (iii) corresponding to the center line 2C of the driving lane line 2, and generate the reference path 3a along the center line 2C represented by the derived cubic function F(X).

[0031] F(X) = C3X 3 + C2X 2 + C1X + C0 (iii)

[0032] C3=(C 3L +C 3R ) / 2, C2=(C 2L +C 2R) / 2

[0033] C1=(C 1L +C 1R ) / 2, C0=(C 0L +C 0R ) / 2

[0034] The safety zone setting unit 13 sets a safety zone 6a within a predetermined distance W from the side end of other vehicles 4a identified by the forward recognition unit 11 toward the reference path 3a of the vehicle 1 in the driving lane 2. More specifically, as shown in FIG4a, the Y coordinate Y of the side end of other vehicles 4a is determined based on the recognition result of the forward recognition unit 11. a And determine the Y coordinate of the side end of the safety zone 6a. R (Y R =Y a +W), thereby setting the safe zone 6a(Y) a ≤Y≤Y R ).

[0035] Within the identification cutoff interval AR (0≤X≤L) set ahead of vehicle 1 at a predetermined distance L from vehicle 1, the target path generation unit 14 does not modify the reference path 3a generated by the reference path generation unit 12, but directly sets it as the target path 3b of vehicle 1. More specifically, even if there is no guaranteed safety zone 6a between the reference path 3a of vehicle 1 and other vehicles 4a (Y R ≥F(X)), as long as the location of the safe zone 6a is not guaranteed to be within the identification cutoff interval AR (0≤X≤L), the reference path 3a is not modified and the target path 3b is set instead. Thus, even if another vehicle 4a traveling close to the driving lane 2 of this vehicle 1 is identified immediately after passing this vehicle 1, unnecessary sudden changes to the target path 3b can be suppressed.

[0036] Based on the vehicle speed V detected by the vehicle speed sensor 8, the specified distance L for identifying the cut-off interval AR is set to the distance reached by the vehicle 1 after a specified time t0 (e.g., approximately 0.9 seconds) (L = Vt0). The specified distance L for identifying the cut-off interval AR can also be set to a constant distance independent of the vehicle speed V. The specified distance L for identifying the cut-off interval AR can also be set according to the speed limit of the road, etc.

[0037] Figure 4B This diagram illustrates a variation of identifying the cut-off interval AR. Identifying the cut-off interval AR can be done as follows: Figure 4A As shown, the area is defined as a roughly rectangular region extending in the left and right directions in front of the vehicle 1 when viewed from above. Alternatively, it can be as follows: Figure 4BAs shown, the area is defined as roughly trapezoidal in shape when viewed from above, extending to the left and right sides in front of the vehicle 1. In this case, for example, the specified distance L is set to be shorter the farther away from the driving lane 2.

[0038] The target path generation unit 14 is located in front of the identified cut-off interval AR (X > L), such as... Figure 2 As shown, the baseline path 3a is modified to generate the target path 3b in a manner that ensures a safe area 6a between vehicle 1 and other vehicles 4a. More specifically, if it is determined that a safe area 6a cannot be ensured between vehicle 1's baseline path 3a and other vehicles 4a at a location that crosses the identification cutoff interval AR (Y... R ≥F(X), X>L), in order to ensure the safe area 6a, correct the baseline path 3a and generate the target path 3b.

[0039] The driving control unit 15 controls the driving actuator 7 based on the target path 3b generated by the target path generation unit 14 to assist the driver of the vehicle 1 or enable the vehicle 1 to drive automatically. This suppresses sudden changes in the target path 3b, allowing the vehicle 1 to travel along a stable target path 3b.

[0040] Figure 5 This is a flowchart illustrating the path generation process of device 100, showing the process of the program executed by the arithmetic unit of device 100. Figure 5 The process, for example, begins when vehicle 1 is started and ECU 10 is activated, and is repeated at a predetermined interval.

[0041] First, in step S1 (S: processing step), based on signals from external sensor 9, the driving lane 2 of vehicle 1 and other vehicles 4a and 4b traveling in adjacent lanes 5a and 5b are identified. A baseline path 3a is generated based on the identification results, and safe zones 6a and 6b are set. Next, in step S2, it is determined whether the baseline path 3a generated in S1 ensures safe zones 6a and 6b are maintained between the baseline path 3a and other vehicles 4a and 4b as set in S2. If S2 is negative (S2: No), the process proceeds to step S3; if it is positive (S2: Yes), the process proceeds to step S5.

[0042] In S3, it is determined whether the locations where safe zones 6a and 6b cannot be guaranteed are within the identification cutoff interval AR. If S3 is negative (S3: No), the process proceeds to S4; if it is positive (S3: Yes), the process proceeds to S5. In S4, the reference path 3a generated in S1 is corrected to ensure the safe zones 6a and 6b set in S2 between the reference path 3a generated in S1 and other vehicles 4a and 4b. In S5, the reference path 3a generated in S1 is not corrected, and the target path 3b is generated instead.

[0043] The following effects can be achieved by adopting this implementation method.

[0044] (1) The device 100 includes: an external sensor 9 that detects objects in the area in front of the vehicle 1; a forward recognition unit 11 that identifies other vehicles 4a, 4b among the objects detected by the external sensor 9 that are traveling in adjacent lanes 5a, 5b adjacent to the driving lane 2 of the vehicle 1; a reference path generation unit 12 that generates a reference path 3a for the vehicle 1 in the driving lane 2; a safety zone setting unit 13 that sets safety zones 6a, 6b from the side ends of the other vehicles 4a, 4b identified by the forward recognition unit 11 toward the driving lane 2; and a target path generation unit 14 that generates a target path 3b for the vehicle 1 based on the reference path 3a generated by the reference path generation unit 12. Figure 3 ).

[0045] The target path generation unit 14 sets the reference path 3a as the target path 3b within the identification cutoff zone AR in front of the vehicle 1, and generates the target path 3b by correcting the reference path 3a in a manner that ensures the safety zones 6a and 6b set by the safety zone setting unit 13 between the vehicle 1 and other vehicles 4a and 4b identified by the forward identification unit 11 in front of the identification cutoff zone AR. Figure 4A , Figure 4B Therefore, even if another vehicle 4a traveling close to vehicle 1 in the same lane 2 is detected immediately after passing vehicle 1, unnecessary sudden changes to the target path 3b can be suppressed.

[0046] (2) The identification cut-off interval AR is set as a defined area that extends in the left and right directions in front of the vehicle 1 and is roughly rectangular or trapezoidal in shape when viewed from above. Figure 4A , Figure 4B By setting up identification cut-off intervals AR throughout the left and right directions in the area immediately in front of this vehicle 1, it is possible to reliably suppress unnecessary sudden changes in the target path 3b even if other vehicles 4a and 4b are identified immediately in front of this vehicle 1.

[0047] (3) The device 100 also includes a driving control unit 15. Figure 3 The driving control unit 15 controls the driving actuator 7 to assist the driver of the vehicle 1 or enable the vehicle 1 to drive automatically. The driving control unit 15 controls the driving actuator 7 according to the target path 3b generated by the target path generation unit 14. As a result, sudden changes in the target path 3b can be suppressed, and the vehicle 1 can travel along the stable target path 3b.

[0048] In the above embodiment, an external sensor 9 including a camera 9a and a distance detection unit 9b such as millimeter-wave radar or lidar was described as an example. However, the detection unit for detecting objects in the area in front of the vehicle is not limited to this. For example, the distance from the vehicle 1 to an object in the area in front can be detected based on image data of the area in front of the vehicle captured by the camera 9a. In this case, the external sensor 9 may consist solely of the camera 9a.

[0049] In the above embodiment, an example of the reference path generation unit 12 generating a reference path 3a along the center line 2C of the driving lane 2 was described. However, the reference path generation unit that generates a reference path for the vehicle in the driving lane is not limited to this. For example, a reference path 3a along the driving lane 2 that is closer to the outer edge of the road than the center line 2C may also be generated.

[0050] In the above embodiment, an example of the device 100 including the driving control unit 15 was described, but the path generation device is not limited to such a device. For example, a display control unit may be included, which controls a display unit such as a head-up display to overlay the target path 3b generated by the target path generation unit 14 onto the road in front of the vehicle.

[0051] One or more of the above embodiments and variations can be combined arbitrarily, and variations can also be combined with each other.

[0052] Using this invention, sudden changes in the target path can be suppressed.

[0053] The present invention has been described above in conjunction with preferred embodiments, but those skilled in the art should understand that various modifications and alterations can be made without departing from the scope of the following claims.

Claims

1. A path generation device (100), characterized in that, have: The detection unit (9) detects objects in the area in front of the vehicle (1); The forward identification unit (11) identifies other vehicles traveling in an adjacent lane that is adjacent to the driving lane of the vehicle (1) among the objects detected by the detection unit (9); The reference path generation unit (12) generates a reference path for the vehicle (1) in the driving lane; The safety zone setting unit (13) sets a safety zone from the side end of other vehicles identified by the front recognition unit (11) toward the driving lane; as well as The target path generation unit (14) generates the target path for the current vehicle (1) based on the reference path generated by the reference path generation unit (12). The target path generation unit (14) sets the target path without modifying the reference path within a predetermined interval ahead of the vehicle (1), even if there is no safe area between the vehicle (1) and the other vehicles identified by the forward identification unit (11) as defined by the safe area setting unit (13). This is done in a way that the safe area set by the safe area setting unit (13) is ensured between the vehicle (1) and the other vehicles identified by the forward identification unit (11) ahead of the predetermined interval.

2. The path generation device (100) according to claim 1, characterized in that, The specified interval is defined as a specified area extending in the left and right directions in front of the vehicle (1), which is roughly rectangular or roughly trapezoidal in shape when viewed from above.

3. The path generation device (100) according to claim 1 or 2, characterized in that, It also includes a driving control unit (15), which controls the driving actuator (7) to assist the driver of the vehicle (1) or enable the vehicle (1) to drive automatically. The driving control unit (15) controls the driving actuator (7) according to the target path generated by the target path generation unit (14).

4. The path generation device (100) according to claim 1 or 2, characterized in that, The detection unit (9) includes a camera.

5. The path generation device (100) according to claim 1 or 2, characterized in that, The specified interval is set as the specified distance in front of this vehicle (1).

6. The path generation device according to claim 5, characterized in that, The specified distance is set as the distance that the vehicle (1) will reach after a specified time, based on the speed of the vehicle (1) or the speed limit of the driving lane.

7. A path generation method for generating a target path for the vehicle (1), characterized in that, include: Identify other vehicles traveling in an adjacent lane that is adjacent to the driving lane of the vehicle (1) in the area in front of the vehicle (1) detected by the detection unit (9); Generate a baseline path for the vehicle (1) in the driving lane; A safety zone is established from the side end of the other vehicles toward the driving lane; The target path of the cost vehicle (1) is generated based on the baseline path. Generating the target path includes: starting from the vehicle (1), within a predetermined interval ahead of it, even if there is no established safe zone between the vehicle (1) and the identified other vehicles, without modifying the baseline path and setting it as the target path, in order to ensure the safe zone between the vehicle (1) and the other vehicles ahead of the predetermined interval, modifying the baseline path to generate the target path.

8. The path generation method according to claim 7, characterized in that, The specified interval is defined as a specified area extending in the left and right directions in front of the vehicle (1), which is roughly rectangular or roughly trapezoidal in shape when viewed from above.

9. The path generation method according to claim 7 or 8, characterized in that, It also includes controlling the driving actuator (7) to assist the driver of the vehicle (1) or to enable the vehicle (1) to drive automatically. The control includes controlling the driving actuator (7) according to the target path.

10. The path generation method according to claim 7 or 8, characterized in that, The detection unit (9) includes a camera.

11. The path generation method according to claim 7 or 8, characterized in that, The specified interval is set as the specified distance in front of this vehicle (1).

12. The path generation method according to claim 11, characterized in that, The specified distance is set as the distance that the vehicle (1) will reach after a specified time, based on the speed of the vehicle (1) or the speed limit of the driving lane.

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