A geometry-based model for road edge detection at intersections

Abstract

A system, map server, and method for navigating a vehicle through an intersection. The map server includes a remote processor and a communication device. The remote processor determines a first road edge of a first road entering the intersection and a second road edge of a second road entering the intersection. The remote processor constructs an intersection edge connecting a first point on the first road edge to a second point on the second road edge. The communication device transmits the intersection edge to a vehicle. A vehicle processor on the vehicle uses the intersection edge to navigate the vehicle through the intersection.

Description

Technical Field

[0001] The subject disclosure relates to constructing road edges in a map, and more particularly, to systems and methods for constructing road edges for intersections in a map. Background Art

[0002] Detecting road edges is integral to creating vehicle paths that guide autonomous vehicles along roads. Intersections are integral to road networks and can have many different configurations, making the task of road and lane edge detection challenging. While aerial imagery can be used for road edge inference, occlusions caused by faded road markings, low-quality images, and / or the presence of foliage, buildings, or other objects hinder detection of road edges at intersections from this source. Furthermore, while crowdsourced vehicle data can be used to detect road edges, this approach requires expensive map matching efforts and is prone to noise and data sparsity. Therefore, it is desirable to be able to construct the road edges at intersections shown in a map based on knowledge of the road edges near the intersection. Summary of the Invention

[0003] In one exemplary embodiment, a method for navigating a vehicle through an intersection is disclosed. A first road edge of a first road entering the intersection is determined at a remote processor. A second road edge of a second road entering the intersection is determined at the remote processor. An intersection edge is constructed at the remote processor, connecting a first point on the first road edge to a second point on the second road edge. The intersection edge is transmitted to a vehicle, which uses the intersection edge to navigate the vehicle through the intersection.

[0004] In addition to one or more features described herein, a nominal turning radius of the intersection edge is determined based on the intersection configuration and the intersection angle between the first road edge and the second road edge. The method also includes determining a tangent distance based on the intersection angle and the nominal turning radius. The method also includes using the tangent distance to determine the position of a first point on the first road edge relative to the intersection and the position of a second point on the second road edge relative to the intersection. The method also includes using a first radial line extending from the first point and a second radial line extending from the second point to determine a turning center of the intersection edge. The method also includes determining the intersection edge by interpolating the intersection radial line based on the rotation angle to coincide with the first point and the second point. The intersection may include at least one of a horizontal curve and a lane change.

[0005] In another exemplary embodiment, a map server for vehicle navigation is disclosed. The map server includes a processor and a communication device. The processor is configured to determine a first road edge of a first road entering an intersection, determine a second road edge of a second road entering the intersection, and construct an intersection edge connecting a first point on the first road edge to a second point on the second road edge. The communication device is configured to transmit the intersection edge to a vehicle for navigating through the intersection using the intersection edge.

[0006] In addition to one or more features described herein, the processor is further configured to determine a nominal turning radius of the intersection edge based on the intersection configuration and the intersection angle between the first road edge and the second road edge. The processor is further configured to determine a tangent distance based on the intersection angle and the nominal turning radius. The processor is further configured to use the tangent distance to determine the position of a first point on the first road edge relative to the intersection point and the position of a second point on the second road edge relative to the intersection point. The processor is further configured to determine a turning center of the intersection edge using a first radial line extending from the first point and a second radial line extending from the second point. The processor is further configured to determine the intersection edge by interpolating the intersection radial line based on the rotation angle to coincide with the first point and the second point. The intersection may include at least one of a horizontal curve and a lane change.

[0007] In yet another exemplary embodiment, a system for navigating a vehicle is disclosed. The system includes a remote processor and a vehicle processor. The remote processor is configured to determine a first road edge of a first road entering an intersection, determine a second road edge of a second road entering the intersection, and construct an intersection edge connecting a first point on the first road edge to a second point on the second road edge. The vehicle processor is configured to use the intersection edge to navigate the vehicle through the intersection.

[0008] In addition to one or more features described herein, the remote processor is further configured to determine a nominal turning radius of the intersection edge based on the intersection configuration and the intersection angle between the first road edge and the second road edge. The remote processor is further configured to determine a tangent distance based on the intersection angle and the nominal turning radius, and use the tangent distance to determine the position of a first point on the first road edge relative to the intersection and the position of a second point on the second road edge relative to the intersection. The remote processor is further configured to determine a turning center of the intersection edge using a first radial line extending from the first point and a second radial line extending from the second point. The remote processor is further configured to determine the intersection edge by interpolating the intersection radial line based on the rotation angle to coincide with the first point and the second point. The intersection may include at least one of a horizontal curve and a lane change.

[0009] The above features and advantages and other features and advantages of the present disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Additional features, advantages, and details appear, by way of example only, in the following detailed description, which refers to the accompanying drawings, in which:

[0011] Figure 1 A vehicle in an illustrative embodiment is shown;

[0012] Figure 2 An aerial image of the intersection provided in the illustrative map is shown;

[0013] Figure 3 An aerial image is shown with an extension line extending the edge of the road to the intersection;

[0014] Figure 4 The nominal turning radius associated with the intersection is shown;

[0015] Figure 5 The locations of the curvature points and tangent points in the aerial image are shown;

[0016] Figure 6 The turning center PO determined by the curvature point and the tangent point is shown;

[0017] Figure 7 shows the intersection edges drawn on an aerial image;

[0018] Figure 8 Shows the use Figure 2-7 A flowchart of a method for generating intersection edges from a geometric model outlined in;

[0019] Figure 9 A schematic map showing a four-branch intersection of two roads intersecting at right angles;

[0020] Figure 10 shows the use of drawing to Figure 9 Points in the map and road edges constructed by the method disclosed in this article;

[0021] Figure 11 an exemplary map showing a T-intersection between a first road and a second road; and

[0022] Figure 12 shows the use of drawing to Figure 11 The points in the map and the road edges completed by the method disclosed in this article. DETAILED DESCRIPTION

[0023] The following description is merely exemplary in nature and is in no way intended to limit the present disclosure, its application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0024] According to an exemplary embodiment, Figure 1 A system 100 for navigating a vehicle 102 is shown. The system 100 includes the vehicle 102 and a remote server 104 in communication with the vehicle 102. In various embodiments, the remote server 104 is a map server. The map server includes a remote processor 106, a memory storage device 108, and a server communication device 110. The memory storage device 108 stores a map including map features. The remote processor utilizes the map from the memory storage device 108 and constructs a map feature from the map using the methods disclosed herein, which can be used by the vehicle 102 for navigation purposes. Specifically, the remote processor 106 can fill in missing road edges in the map. In particular, the remote processor 106 can fill in missing road edges in the map, particularly at intersections shown in the map. The server communication device 110 transmits the map or map feature to the vehicle 102.

[0025] Vehicle 102 includes at least a controller 112 and a vehicle communication device 116. Vehicle communication device 116 communicates with remote server 104 via server communication device 110. Controller 112 receives a map or map features and navigates vehicle 102 through its environment and surroundings based on the map or map features. Controller 112 includes a vehicle processor 118 for navigating the vehicle using the map or map features. Vehicle processor 118 can control various vehicle systems, such as steering, braking, and propulsion.

[0026] Figure 2 An aerial image 200 of an intersection provided in an illustrative map is shown. The aerial image 200 includes an intersection between two roads and known road edges that can be used to generate intersection edges. The aerial image 200 or map includes a first road 202 and a second road 204 that intersect at an intersection 206. The first road 202 includes a first road edge 208 that extends to the intersection 206. The second road 204 includes a second road edge 210 that extends to the intersection 206. The first road edge 208 and the second road edge 210 can be provided from a map server (e.g., the remote server 104) that provides the aerial image 200. The first road edge 208 and the second road edge 210 are drawn for an illustrative scenario in which the vehicle 102 turns right from the first road 202 onto the second road 204 at the intersection 206. In alternative embodiments, the road edges and intersection edges can be selected for any suitable turn or maneuver to be performed by the vehicle 102. Figure 2As shown, the intersection edge is not available in the aerial image 200. The lack of the intersection edge may be caused by various reasons, such as occlusion, faded road markings, low image quality, etc. The method described herein fills the intersection edge using the first road edge 208 and the second road edge 210.

[0027] A circle 212 is drawn around intersection 206. Circle 212 represents an area of ​​interest relative to intersection 206. Generally, circle 212 is centered on intersection 206 and is drawn large enough to include intersection 206 and at least a portion of first road 202 and second road 204. Circle 212 intersects both first road edge 208 and second road edge 210. Circle 212 intersects first road edge 208 at a first perimeter point P1 and intersects second road edge 210 at a second perimeter point P2.

[0028] Figure 3 Aerial image 200 is shown with extension lines extending road edges into an intersection. By selecting two points along first road edge 208 (e.g., first perimeter point P1 and another point along first road edge 208), a first extension line 302 extending first road edge 208 into intersection 206 can be drawn, formed, or constructed. Similarly, by selecting two points on second road edge 210 (e.g., second perimeter point P2 and another point along second road edge 210), a second extension line 304 extending second road edge 210 into intersection 206 can be drawn. First extension line 302 and second extension line 304 intersect at intersection point 306 (PI). First extension line 302 and second extension line 304 form an intersection angle Δ at intersection point PI. When vehicle 102 turns from traveling along first road 202 to traveling along second road 204, it turns through intersection angle Δ.

[0029] Once the intersection point PI is determined, the nominal turning radius R, which represents the radius of the arc, can be found. The nominal turning radius R can be a constant value or calculated as a function of the intersection angle Δ, as shown in equation (1):

[0030]

[0031] When the intersection angle Δ is a basic 90-degree angle, the nominal turning radius is a standardized value (ie, 6.1 meters). For intersection angles outside the 90°±5° range, the nominal turning radius can be calculated using the equation shown in the second row of equation (1).

[0032] Figure 4The nominal turning radius R relative to intersection 206 is shown. Line AB drawn perpendicular to first road edge 208 and line CB drawn perpendicular to second road edge 210 will intersect to form quadrilateral ABC(PI). From simple geometry, it can be seen that angle ABC is the same as intersection angle Δ. Therefore, the nominal turning radius R is obtained by equation (1), and intersection angle Δ can be used to determine the tangent distance T, as shown in equation (2):

[0033]

[0034] The tangent distance T is used to determine the position of the curvature point PC and the position of the tangent point PT.

[0035] Figure 5 The positions of the curvature point PC and the tangent point PT in the aerial image are shown. The curvature point PC is located along the first extension line 302 (or the first road edge 208) and is separated from the intersection point PI by a tangent distance T. The tangent point PT is located along the second extension line 304 (or the second road edge 210) and is separated from the intersection point PI by a tangent distance T.

[0036] Figure 6 The turning center PO is shown, which is determined by the curvature point PC and the tangent point PT. Once the locations of PC and PT are determined, a first radial line 602 is drawn perpendicularly from the curvature point PC to the first extension line 302 (or the first road edge 208), and a second radial line 604 is drawn perpendicularly from the tangent point PT to the second extension line 304 (or the second road edge 210). The first radial line 602 and the second radial line 604 intersect at the turning center PO. A reference line 606 can be drawn from point PO, which can be used to determine the angle drawn in the intersection edge based on the first radial line 602 and the second radial line 604. The reference line 606 can be an east-west line within the aerial image 200.

[0037] Figure 7 The intersection edge 702 is shown drawn on the aerial image 200. The aerial image 200 shows the respective angles of the first radial line 602 and the second radial line 604 relative to the reference line 606. A first angle θ0 is drawn between the reference line 606 and the first radial line 602. A second angle θ is drawn between the reference line 606 and the second radial line 604. N The intersecting radial line 704 is at a first angle θ0 to a second angle θ N to draw the intersection edge 702. The length of the intersecting radial line 704 increases with the rotation angle θ. n changes to meet the boundary conditions. For example, when θ n =θ0, then R n =R0, when θ n =θ NWhen R n =R N When the intersection edge 702 is parameterized by equations (3) and (4), these boundary conditions are satisfied:

[0038]

[0039] and

[0040]

[0041] Wherein, 0<=n<=N. The intersection edge 702 is formed on the radial line R opposite to the turning center PO. n The interpolation for constructing the intersection edge 702 is performed using equations (3) and (4).

[0042] Figure 8 Shows the use Figure 2-7 Flowchart 800 of a method for generating intersection edges from a geometric model is outlined.

[0043] At block 802, two points are selected along the first road edge 208 and used to draw the first extension line 302. Additionally, two points are selected along the second road edge 210 and used to draw the second extension line 304. Assuming that the first extension line 302 is based on the coordinates of the two points selected from the first road edge 208, the first extension line is described by a suitable linear equation. Similarly, the second extension line 304 is described by a suitable linear equation.

[0044] At block 804, the intersection point PI between the first extension line 302 and the second extension line 304 is calculated or located. Then, using the equations for the first extension line 302 and the second extension line 304, the intersection angle Δ is found at the intersection point PI. At block 806, the nominal turning radius R of the intersection is determined. The nominal turning radius R can be a standard value or a calculated value. The nominal turning radius and the intersection angle are used to determine the tangent distance T.

[0045] At block 808, a connection point is determined using the tangent distances and intersection point PI. The first connection point is located along the first road edge and is also referred to herein as the point of curvature (PC), marking the start of the curve in intersection edge 702. The first connection point is separated from intersection point PI by a tangent distance T along first extension line 302. The second connection point is located along the second road edge and is also referred to herein as the point of tangent (PT), marking the end of the curve in intersection edge 702. The second connection point is located along the second road edge and is also referred to herein as the point of tangent (PT), marking the end of the curve in intersection edge 702. The second connection point is separated from intersection point PI by a tangent distance T along second extension line 304. The first radial line 602 extends perpendicularly to the first extension line 302 at the first connection point. The second radial line 604 extends perpendicularly to the second extension line 304 at the second connection point.

[0046] At block 810, the turning center (PO) is found as the intersection of the first radial line 602 and the second radial line 604. At block 812, the polar coordinates of the first radial line and the second radial line are determined relative to the reference line 606. In various embodiments, the reference line 606 is an east-west line. The first length R of the first radial line 602 is N The first angle θ is measured between the turning center PO and the first connection point PC. N is measured between the reference line 606 and the first radial line 602. Similarly, a second length R0 is measured between the turning center PO and the second connection point PT, and a second angle θ0 is measured between the reference line 606 and the second radial line 604.

[0047] At block 814, the intersection edge 702 is created using the polar coordinates determined in block 812 and the parameterized equations (3) and (4). At block 816, edge points of a curve are created from the intersection edge 702, the first road edge 208, and the second road edge 210.

[0048] Figure 9 An illustrative aerial image 900 of an intersection of two roads intersecting at a right angle is shown. A first perimeter point P1 and a second perimeter point P2 are plotted for each road of the intersection, along with a point of curvature PC and a point of tangency PT. Figure 10 An aerial image 1000 is shown including road edges (1001, 1002, 1003, 1004) that are obtained using Figure 9 An illustrative aerial image 900 of points and constructed using the methods disclosed herein.

[0049] Figure 11 An illustrative aerial image 1100 is shown of a T-intersection between a first road 1102 and a second road 1104. First road 1102 terminates at second road 1104, forming a T-intersection. First and second perimeter points P1 and P2, as well as a curvature point PC and a tangent point PT, are drawn for each road edge of the intersection. Figure 12 An aerial image 1200 is shown including road edges (1201, 1202) that are drawn using Figure 11 An illustrative aerial image 1100 of the points and the methods disclosed herein are completed.

[0050] Although the method for determining intersection edges disclosed herein is shown as being performed on aerial imagery or a map, the method can be performed without requiring aerial imagery or crowdsourced vehicle data. In one embodiment, equations for a first road edge and a second road edge can be received, and the first road edge and the second road edge can be used to perform calculations for determining the intersection edge. In an alternative embodiment, a map including the first road edge and the second road edge can be provided, and these edges can then be extracted from the map and used independently of the map to determine the intersection edge. Determining intersection edges without requiring aerial imagery or crowdsourced vehicle data significantly reduces computational power and time.

[0051] While the method for constructing indicated edges has been discussed with respect to roads entering an intersection, this is not intended to limit the present invention. In various embodiments, the method can be used to fill gaps in road edges that do not follow easily defined trajectories. For example, the method can be used to determine horizontal curves along a road or lane transitions, such as from a two-lane road to a single lane.

[0052] Although the above disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope of the present disclosure. Therefore, it is intended that the present disclosure is not limited to the particular embodiments disclosed, but is intended to include all embodiments falling within its scope.

Claims

1. A method for navigating a vehicle through an intersection, comprising: determining, at the remote processor, a first road edge of a first road entering the intersection; determining, at a remote processor, a second road edge of a second road entering the intersection, wherein an intersection edge between the first road edge and the second road is unknown; drawing a first extension line along the first road edge into the intersection; drawing a second extension line along the second road edge into the intersection; determining an intersection point between the first extension line and the second extension line; determining a nominal turning radius of the intersection edge based on an intersection configuration and an intersection angle between the first road edge and the second road edge, and determining a tangent distance based on the intersection angle and the nominal turning radius; determining a position of a first point on the first road edge relative to an intersection and a position of a second point on the second road edge relative to the intersection using the tangent distance; determining a turning center of the intersection edge using a first radial line extending from the first point and a second radial line extending from the second point; determining the intersection edge by interpolating an intersection radial line based on the rotation angle to coincide with the first point and the second point; At the remote processor, constructing an intersection edge connecting a first point on a first road edge to a second point on a second road edge using a nominal turning radius; as well as The intersection edges are communicated to the vehicle to navigate the vehicle through the intersection using the intersection edges.

2. A map server for vehicle navigation, comprising: Processor, which is configured as: determining a first road edge of a first road entering the intersection; determining a second road edge of a second road entering the intersection, wherein an intersection edge between the first road edge and the second road is unknown; drawing a first extension line along the first road edge into the intersection; drawing a second extension line along the second road edge into the intersection; determining an intersection point between the first extension line and the second extension line; determining a nominal turning radius of the intersection edge based on an intersection configuration and an intersection angle between the first road edge and the second road edge, and determining a tangent distance based on the intersection angle and the nominal turning radius; The processor is further configured to determine a position of a first point on the first road edge relative to an intersection and a position of a second point on the second road edge relative to the intersection using the tangent distance; The processor is further configured to determine a turning center of the intersection edge using a first radial line extending from the first point and a second radial line extending from the second point; The processor is further configured to determine the intersection edge by interpolating an intersection radial line based on the rotation angle to coincide with the first point and the second point; constructing an intersection edge connecting a first point on a first road edge to a second point on a second road edge using a nominal turning radius; as well as A communication device is configured to communicate the intersection edge to a vehicle for navigating through the intersection using the intersection edge.

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