Road reference line generation method and road reference line generation apparatus

Abstract

To reduce a feeling of discomfort of an occupant with respect to vehicle characteristics during operation of a vehicle.SOLUTION: In a road reference line generation method, information on map node points indicating reference points on a map of a traveling area in which an own vehicle is currently traveling and information on map link lines connecting the map node points are acquired from map information (S1), a current position and a traveling direction of the own vehicle are measured (S2), the map node points and the map link lines are corrected on the basis of the measured current position and traveling direction (S6, S8). In correction of the map node points, the map node points are corrected in a direction perpendicular to the measured traveling direction or to the map link lines (S6).SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a road reference line generating method and a road reference line generating device. [Background technology]

[0002] Patent Document 1 describes a lane link generating device that automatically generates lane links (lane center lines) from the recognition results of lane markings. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 080257 Brochure Summary of the Invention [Problem to be solved by the invention]

[0004] The lane link generation device described in Patent Document 1 does not take into account errors in the estimated position and attitude of the vehicle, and therefore, in situations where these errors are large, there is a risk that the accuracy of the lane link will decrease. An object of the present invention is to accurately correct the shape of map link lines that represent a vehicle's driving area. [Means for solving the problem]

[0005] In one aspect of the present invention, a road reference line generation method acquires, from map information, information on map node points that indicate reference points on a map of a driving area in which the vehicle is currently traveling and information on map link lines that connect the map node points, measures the current position and traveling direction of the vehicle, and corrects the map node points and map link lines based on the measured current position and traveling direction. In correcting the map node points, the map node points are corrected in a direction perpendicular to the measured traveling direction or map link lines. [Effects of the Invention]

[0006] According to the present invention, the shape of a map link line representing a vehicle's travel area can be corrected with high accuracy. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of an example of a road reference line generating device according to an embodiment; [Figure 2] FIG. 2 is a block diagram illustrating an example of a functional configuration of a controller. [Figure 3] FIG. 2 is a schematic diagram of an example of map information. [Figure 4] 10(a) and 10(b) are schematic diagrams illustrating an example of correction of map node points and map link lines. [Figure 5] FIG. 10 is a schematic diagram of an example of a map node point that is an intersection of map link lines. [Figure 6] 10(a) and 10(b) are schematic diagrams illustrating an example of a road dividing line detection method. [Figure 7] 1 is a flowchart illustrating an example of a road reference line generating method according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are schematic and may differ from the actual product. Furthermore, the embodiments of the present invention shown below are examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the structure, arrangement, etc. of component parts to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0009] (composition) 1 is a schematic diagram of an example of a road reference line generating device according to an embodiment. A vehicle 1 is equipped with a road reference line generating device 10 that corrects information about a road reference line based on measurement results from a positioning device mounted on the vehicle 1. A road reference line is a reference line (e.g., a center line of a road) that indicates the aspect (position, shape, etc.) of a driving area (road, lane, etc.) in which a vehicle can travel. The road reference line generating device 10 includes an object sensor 11, a positioning device 12, a map database (map DB) 13, and a controller 14.

[0010] The object sensor 11 is an on-board sensor that detects objects around the host vehicle 1. The object sensor 11 detects the environment around the host vehicle 1, such as the relative position between the host vehicle 1 and objects present around the host vehicle 1, the distance between the host vehicle 1 and the objects, and the direction in which the objects are present. The object sensor 11 may include, for example, a camera that captures images of the environment around the host vehicle 1.

[0011] Furthermore, for example, the host vehicle 1 may include a distance measuring device such as a laser range finder (LRF), radar, or LiDAR (Light Detection and Ranging) laser radar, or a sonar sensor that detects objects around the host vehicle 1. The object sensor 11 outputs surrounding environment information, which is information about the detected surrounding environment of the host vehicle 1, to the controller 14.

[0012] The positioning device 12 is equipped with a Global Navigation System (GNSS) receiver and receives radio waves from multiple navigation satellites to measure the current position of the vehicle 1 and the attitude of the vehicle body (e.g., the azimuth angle in the longitudinal direction of the vehicle body). The GNSS receiver may be, for example, a Global Positioning System (GPS) receiver. The positioning device 12 may be, for example, an inertial navigation system. The positioning device 12 outputs information on the measured current position and attitude of the vehicle 1 (current position information) to the controller 14.

[0013] The map DB 13 stores, as map information, information on road reference lines that represent the state of a driving area such as roads, lanes, etc. The map information stored in the map DB 13 will be described later. The controller 14 is an electronic control unit (ECU) that corrects information about the road reference line based on the measurement results of the positioning device 12. The controller 14 includes a processor 15 and peripheral components such as a storage device 16. The processor 15 may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit).

[0014] The storage device 16 may include a semiconductor storage device, a magnetic storage device, an optical storage device, etc. The storage device 16 may include memories such as a ROM (Read Only Memory) and RAM used as main storage devices, as well as registers and cache memories. The functions of the controller 14 described below are realized by, for example, the processor 15 executing a computer program stored in the storage device 16.

[0015] The controller 14 may be formed by dedicated hardware for executing each of the information processes described below. For example, the controller 14 may include a functional logic circuit configured in a general-purpose semiconductor integrated circuit, such as a programmable logic device (PLD) such as a field-programmable gate array (FPGA).

[0016] 2 is a block diagram showing an example of the functional configuration of the controller 14. The controller 14 includes a position acquisition unit 30, a traveling direction acquisition unit 31, a traveling link assignment unit 32, a traveling node assignment unit 33, an angle registration unit 34, a map correction unit 35, and a lane marking detection unit 36. The position acquisition unit 30 acquires information on the current position of the vehicle 1 on a map based on the measurement results of the positioning device 12.

[0017] The traveling direction acquisition unit 31 acquires information about the traveling direction θv of the host vehicle 1 on the map based on the measurement results of the positioning device 12. For example, the traveling link assignment unit 32 may acquire the attitude of the body of the host vehicle 1 measured by the positioning device 12 as the traveling direction θv, or may acquire the moving direction of the host vehicle 1 as the traveling direction θv based on a change in the current position of the host vehicle 1 measured by the positioning device 12.

[0018] The travel link allocation unit 32 acquires map information from the map DB 13. Fig. 3 is a schematic diagram of an example of map information. For example, the map information may be map data for navigation that includes information on road reference lines for each road. The map information is expressed as a collection of unit sections W1, W2, ... that make up a road. In the following description, the unit sections W1, W2, ... may be collectively referred to as "unit section W."

[0019] Each unit section W has a connection relationship with other unit sections W, and represents the topology of the road. In addition, the unit section is stored in the map DB 13 in association with the road type, such as whether the road to which it belongs is a one-way road or a two-way road. Each unit section W includes information on a string of multiple map node points (in the example of unit section W1, map node points n1 to n5). In the following description, map node points n1 to n5, ... may be collectively referred to as "map node point n."

[0020] The information for each map node point n includes coordinate information (x, y) that indicates the position of the map node point n in a coordinate system (hereinafter referred to as the "map coordinate system") that uses a fixed point as the reference point, and angle information θ that indicates the extension direction of the driving area (or the direction of vehicle traffic on the driving area) at the position of the map node point n, and expresses the approximate shape of the road.

[0021] The information about each map node point n also includes an S value, which is the distance from the starting point of the unit section W that includes the map node point n to the map node point n. The map node points may be arranged at intervals of, for example, about 1 m. The map coordinate system may be, for example, a global coordinate system.

[0022] Furthermore, the unit section W includes information on map link lines L1 to L4 that connect the map node points n included in the unit section W. For example, the map link line L1 connecting the map node points n1 and n2 represents the connection relationship between the map node points n1 and n2, the map link line L2 connecting the map node points n2 and n3 represents the connection relationship between the map node points n2 and n3, the map link line L3 connecting the map node points n3 and n4 represents the connection relationship between the map node points n3 and n4, and the map link line L4 connecting the map node points n4 and n5 represents the connection relationship between the map node points n4 and n6. In the following description, the map link lines L1 to L4, ... may be collectively referred to as "map link lines L."

[0023] Each unit section W may be provided with information for determining whether the unit section W is a section inside an intersection or a section outside the intersection. The traveling link assignment unit 32 identifies the unit section W in which the vehicle 1 is currently traveling based on the current position and traveling direction θv of the vehicle 1 acquired by the position acquisition unit 30 and the traveling direction acquisition unit 31, and the shape of the map link line L around the vehicle 1 acquired from the map DB 13.

[0024] 2, the travel node allocation unit 33 selects the map node point n that is closest to the current position of the vehicle 1 from among the map node points n included in the unit section W identified by the travel link allocation unit 32. n Identify. The angle registration unit 34 registers the nearest node point n that is closest to the vehicle 1 at the time when the traveling direction θv of the vehicle 1 is acquired. n The angle information θ of the nearest node point n is corrected based on the traveling direction θv acquired at that time. n The value of the angle information θ may be updated to the value of the traveling direction θv.

[0025] For example, when the vehicle 1 is changing lanes, the angle registration unit 34 registers the nearest node point n n It is also possible to prohibit the correction of the angle information θ. As a method for determining whether the host vehicle 1 is changing lanes, an existing method can be used. Further, for example, the angle registration unit 34 may register the nearest node point n n are the same map node point, the nearest node point n is determined based on the average value of the traveling direction θv measured multiple times. n The angle information θ may be corrected.

[0026] The map correction unit 35 corrects the position information of each map node point n based on the angle information θ of each map node point n corrected by the angle registration unit 34. For example, the map correction unit 35 may calculate an estimated position of one of a pair of adjacent map node points, which is located closer to the vehicle in the traveling direction θv of the vehicle 1 (or the direction represented by the angle information θ of each map node point n), based on the angle information θ at the position of the other map node point, which is located further back in the traveling direction of the vehicle 1, and correct the position of the other map node point so as to reduce the error from the calculated estimated position.

[0027] Please refer to Figures 4(a) and 4(b). Figure 4(a) shows a state in which the vehicle 1 is traveling on a road in a traveling area RT in a traveling direction θv. Map node points n1 to n N The map link lines L connecting these map node points n represent the road reference lines of the driving area RT. N is an integer of 2 or more. An enlarged view of the area M enclosed by the dashed line in FIG. 4(a) is shown in FIG. 4(b).

[0028] Map node point n in Figure 4(b) i and map node point n i+1 is an example of a pair of adjacent map node points. Also, map node point n i+1 and map node point n i+2 is another example of a pair of adjacent map node points. As mentioned above, the map node point n i , n i+1 , n i+2 The angle information θ is corrected by the angle registration unit 34 based on the traveling direction θv of the vehicle 1. In FIG. 4(b) and the following description, the corrected map node point n i , ni+1 , n i+2 The angle information θ of each i , g i+1 , g i+2 This indicates:

[0029] The map correction unit 35 calculates the distance between a pair of adjacent map node points n i , n i+1 Among these, one map node point n is located on the near side in the traveling direction θv of the vehicle 1. i Angle information g at the position i Based on this, the other map node point n located on the far side in the traveling direction of the vehicle 1 is i+1 Correct the position of For example, the map correction unit 35 may set the map node point n i+1 Auxiliary line e passing through i+1 For example, set the auxiliary line e i+1 is the map node point n i , n i+1 and the map link line connecting the map node point n i+1 , n i+2 The line may be a line extending in the direction of the bisector of the angle formed by the map link line connecting the two points. i+1 may be a straight line extending perpendicular to any of these map link lines. i+1 is the angle g i+1 It may be a straight line extending perpendicular to the line.

[0030] The map correction unit 35 corrects the map node point n i Through angle g i A straight line extending in the direction of (the dashed line in Figure 4(b)) and an auxiliary line e i+1 The intersection point Pc with the new map node point n i+1 The map correction unit 35 calculates the estimated position of the map node point n so that the difference from the calculated estimated position Pc becomes small. i+1 Correct the position of Map node point n i+1 By correcting the position of the map node point n i+1The position of the end point of the map link line L connecting to the map node point n is also corrected. As a result, the shape of the road reference line formed by the map node point n and the map link line L is corrected.

[0031] For example, the map correction unit 35 calculates the map node point n j (j=1, 2, ...N) is the coordinate (x j ,y j ) and the angle information is g j Let us consider the auxiliary line e j+1 The equation of the line is a j x j +b j y j =c j Let the map node point n j+1 The length from to the estimated position Pc <g j ,e j+1 > and the weight coefficient is w j The coordinate values ​​of the start and end points are x1, y1, x N ,y N is a constant, and the following equation (1) is set to the minimum value or less than the threshold value, and each map node point n j The position of may be optimized.

[0032]

number

[0033] In addition, the angle information g based on the traveling direction θv of the vehicle 1 with low measurement accuracy j The corrected map node point n j and angle information g based on the traveling direction θv of the host vehicle 1. j Uncorrected map node point n j Weighting coefficient w in j By setting small, such a map node point n j Position (x j ,y j ) may be reduced in correction amount.

[0034] In addition, the angle information g is calculated based on the traveling direction θv of the vehicle 1 with high measurement accuracy. j The corrected map node point n jWeighting coefficient w in j By setting small, such a map node point n j Position (x j ,y j ) may be corrected by a larger amount. The map correction unit 35 may prohibit correction of the position of a map node point n that is an intersection of map link lines (that is, a map node point n that is connected to three or more map link lines L). FIG. 5 is a schematic diagram of an example of a map node point that is an intersection of map link lines.

[0035] Map link line L1 connects map node points n1 and n2, map link line L2 connects map node points n1 and n3, map link line L3 connects map node points n1 and n4, and map link line L4 connects map node points n1 and n5. As a result, map node point n1 is an intersection where map link lines L1 and L2 connecting map node points n2 and n3 intersect with map link lines L3 and L4 connecting map node points n4 and n5. The map correction unit 35 may prohibit correction of map node point n1, which is an intersection.

[0036] See Figure 2. The lane marking detection unit 36 ​​detects lane markings based on point sequence information obtained by detecting the positions of lane markings using the object sensor 11, and the map node points n and map link lines L corrected by the map correction unit 35. 6(a) and 6(b) are schematic diagrams illustrating an example of a road-dividing line detection method. The dashed-dotted line BL indicates the road reference line represented by the map node point n and the map link line L, and the circular plots PS indicate the sequence of points of the road-dividing line detected by the object sensor 11.

[0037] For example, the lane marking detection unit 36 ​​acquires the coordinate information of the sequence of points PS detected by the object sensor 11 as coordinate information in a vehicle coordinate system based on the host vehicle 1. The lane marking detection unit 36 ​​converts the coordinate information of the sequence of points PS into coordinate information (x r ,y r) Fig. 6(a) shows the arrangement of the point sequence PS and the road reference line BL in the map coordinate system.

[0038] Next, the lane line detection unit 36 ​​calculates the coordinate information (x r ,y r ) into coordinate information (x w ,y w Here, the reference line coordinate system is a coordinate system in which the direction along the road reference line is the first coordinate axis (for example, the horizontal axis) and the direction perpendicular to the road reference line (i.e., the road width direction, the horizontal direction) is the second coordinate axis (for example, the vertical axis).

[0039] For example, let us consider a matrix N that represents the orientation of each map node point n and a coordinate P of the point sequence in the map coordinate system. raw and the coordinates P of the sequence of points in the base line coordinate system way is expressed as the following equations (2), (3), and (4), and the S value at each map node point n is defined as "s n ", then the coordinate P in the map coordinate system raw is calculated by the following equation (5) as the coordinate p way is converted to

[0040]

number

[0041] FIG. 6(b) shows the arrangement of the point sequence PS and the road reference line BL in the reference line coordinate system. The lane marking detection unit 36 ​​detects road markings based on the sequence of points PS transformed into the reference line coordinate system. For example, the lane marking detection unit 36 ​​may detect road markings by clustering the sequence of points PS, whose direction along the road reference line is aligned in the first coordinate axis direction, into the same classification.

[0042] FIG. 7 is a flowchart illustrating an example of a road reference line generating method according to the embodiment. In step S1, the traveling link assignment unit 32 acquires information on the map node point n and information on the map link line L from the map DB 13. In step S2, the position acquisition unit 30 and the traveling direction acquisition unit 31 acquire information on the current position of the host vehicle 1 on the map and information on the traveling direction θv.

[0043] In step S3, the traveling link allocation unit 32 identifies the unit section W in which the host vehicle 1 is currently traveling. In step S4, the traveling node allocation unit 33 selects the nearest node point n n Identify.

[0044] In step S5, the angle registration unit 34 determines whether the vehicle 1 is changing lanes. If the vehicle 1 is changing lanes (step S5: Y), the angle registration unit 34 registers the nearest node point n n The angle information θ is not corrected. Then, the process proceeds to step S7. If the vehicle 1 is not changing lanes (step S5: N), the process proceeds to step S6. In step S6, the angle registration unit 34 registers the nearest node point n n The angle information θ is corrected based on the traveling direction θv. Then, the process proceeds to step S7.

[0045] In step S7, the map correction unit 35 determines whether the host vehicle 1 has traveled a predetermined distance since the last time the position information of the map node point n was corrected. If the host vehicle 1 has not traveled the predetermined distance (step S7: N), the process returns to step S1. If the host vehicle 1 has traveled the predetermined distance (step S7: Y), the process proceeds to step S2. In step S8, the map correction unit 35 corrects the position information of each map node point n based on the angle information θ of each map node point n corrected by the angle registration unit 34. Thereafter, the process proceeds to step S9.

[0046] In step S9, the controller 14 determines whether the ignition key (IGN) of the host vehicle 1 has been turned off. If the ignition key has not been turned off (step S9: N), the process returns to step S2. If the ignition key has been turned off (step S9: Y), the process ends.

[0047] (Effects of the embodiment) (1) In the road reference line generation method, information on map node points that indicate reference points on a map of a driving area in which the vehicle is currently driving and information on map link lines that connect the map node points are obtained from map information, the current position and traveling direction of the vehicle are measured, and the map node points and map link lines are corrected based on the measured current position and traveling direction, and the correction of the map node points is performed by correcting the positions of the map node points in a direction perpendicular to the measured traveling direction or map link lines.

[0048] For example, positioning methods such as GNSS have high angular accuracy and road direction position accuracy. Therefore, the vehicle's traveling direction and longitudinal position can be estimated more accurately than its lateral position. Therefore, by correcting map node points and map link lines based on the vehicle's traveling direction, the map link line shape can be corrected more accurately than by correcting it based on the vehicle's position.

[0049] Furthermore, the lane link generating device according to Patent Document 1 generates lane links based on dividing lines, and therefore cannot generate lane links when dividing lines cannot be detected due to blurring or the like. On the other hand, the road reference line generation method of the embodiment uses link line information of road reference lines stored in a map database and measurement results of the current position and traveling direction of the vehicle 1, so there is no section where map link lines cannot be generated.

[0050] (2) The information on the map node point may include angle information that indicates the direction in which the driving area extends at the position of the map node point. In the road reference line generation method, an estimated position of one of a pair of adjacent map node points, which is located on the front side of the vehicle in the traveling direction, may be calculated based on the extending direction of the driving area at the position of the other map node point, which is located on the rear side of the vehicle in the traveling direction, and the position of the other map node point may be corrected to reduce an error from the calculated estimated position. This allows the shape of the map link line to be corrected to better match the shape of the roadway.

[0051] (3) When the measurement accuracy of the measured current position and traveling direction is low, the correction amount of the map node point may be reduced compared to when the measurement accuracy is high. This makes it possible to reduce the correction error caused by a large error in the estimated position or direction of travel of the vehicle.

[0052] (4) The information on the map node point may include angle information that indicates the extension direction of the driving area at the position of the map node point. The angle information of the map node point that is closest to the measured current position may be corrected based on the measured traveling direction. This makes it possible to reduce correction errors due to measurement errors (estimation errors) of the lateral position of the vehicle.

[0053] (5) In sections where the vehicle is changing lanes, correction of angle information of map node points may be prohibited. This prevents erroneous correction due to the vehicle's direction of travel during lane changes (i.e., a direction of travel that does not follow the vehicle alignment). (6) Correction of map node points that are intersections of map link lines may be prohibited. This prevents the shape of map link lines of other roads from being changed due to correction of the positions of map node points.

[0054] (7) When the vehicle's traveling direction is measured multiple times and the same map node point is closest to the vehicle's position at each time, the same map node point may be corrected based on the average value of the traveling direction measured multiple times. As a result, the more driving data is obtained, the more the shape of the map link line can be corrected to match the shape of the vehicle line.

[0055] (8) The coordinates of the sequence of points on the road-dividing line detected by the on-board sensor may be converted into a reference line coordinate system in which the direction along the map link line corrected by the above-described road reference line generation method is the first coordinate axis and the direction perpendicular to the map link line is the second coordinate axis, and the road-dividing line may be detected based on the coordinates of the converted sequence of points. This makes it possible to apply the road reference line generation methods (1) to (7) above to the detection of road dividing lines, thereby preventing erroneous detection of road dividing lines due to low accuracy of link linear shapes in map information. [Explanation of symbols]

[0056] 1... Vehicle, 10... Road reference line generating device, 11... Object sensor, 12... Positioning device, 13... Map database, 14... Controller, 15... Processor, 16... Storage device, 30... Position acquisition unit, 31... Travel direction acquisition unit, 32... Travel link assignment unit, 33... Travel node assignment unit, 34... Angle registration unit, 35... Map correction unit, 36... Lane line detection unit

Claims

1. Acquires, from map information, information on map node points that indicate reference points on a map of a driving area in which the vehicle is currently driving, and information on map link lines that connect the map node points; measuring the current position and traveling direction of the vehicle; correcting the map node points and the map link lines based on the measured current position and traveling direction; The correction of the map node points comprises correcting the positions of the map node points in the measured traveling direction or in a direction perpendicular to the map link line.

2. the information on the map node point includes angle information representing an extension direction of the driving area at the position of the map node point; calculating an estimated position of one of the pair of adjacent map node points, which is located on the front side in the traveling direction of the vehicle, based on the extending direction of the driving area at the position of the other map node point, which is located on the rear side in the traveling direction of the vehicle; correcting the position of the other map node point so as to reduce an error from the calculated estimated position; 2. The road reference line generating method according to claim 1.

3. 2. The road reference line generating method according to claim 1, wherein the correction amount of the map node point is reduced when the measurement accuracy of the measured current position and traveling direction is low compared to when the measurement accuracy is high.

4. the information on the map node point includes angle information representing an extension direction of the driving area at the position of the map node point; 2. The road reference line generating method according to claim 1, wherein the angle information of the map node point that is closest to the measured current position is corrected based on the measured traveling direction.

5. 5. The road reference line generating method according to claim 4, wherein correction of the angle information of the map node points is prohibited in a section where the vehicle is changing lanes.

6. 2. The road reference line generating method according to claim 1, wherein correction of the map node points that are intersections of the map link lines is prohibited.

7. 2. The road reference line generating method according to claim 1, wherein, when the traveling direction of the host vehicle is measured a plurality of times and the same map node point is closest to the position of the host vehicle at each time point, the same map node point is corrected based on an average value of the traveling direction measured a plurality of times.

8. a road-delimiting line detection method for detecting road-delimiting lines, the road-delimiting line detection method comprising: converting coordinates of a sequence of points on a road-delimiting line detected by an on-board sensor into a reference line coordinate system in which a direction along the map link line corrected by the road reference line generation method according to any one of claims 1 to 7 is a first coordinate axis and a direction perpendicular to the map link line is a second coordinate axis; and detecting road-delimiting lines based on the coordinates of the sequence of points after the conversion.

9. a positioning device that measures the current position and traveling direction of the vehicle; a controller that executes a process of acquiring, from map information, information on map node points that indicate reference points on a map of a driving area in which the vehicle is currently driving and information on map link lines that connect the map node points, and a process of correcting the map node points and the map link lines based on the measured current position and traveling direction; wherein the controller corrects the positions of the map node points in a direction perpendicular to the measured traveling direction or the map link line.

Images