Design method of static reference path set of automatic driving in urban traffic working condition

Abstract

The present application belongs to the technical field of autonomous decision-making of automatic driving cars, and particularly relates to a design method of a static reference path set for automatic driving in urban traffic conditions. The present application realizes the generation of a static reference path set for automatic driving in urban traffic conditions through six steps of external landmark determination, internal landmark determination, position information generation, orientation angle calculation, expected speed planning and static reference path set generation, and only relies on the static information of roads provided by a map to realize a pre-planned and pre-stored static reference path set of the whole map, which effectively guarantees the realization of the decision-making and control functions of automatic driving cars. The present application has the advantages of less constraints to be considered, high offline calculation efficiency and small path planning difficulty.

Description

Technical Field

[0001] This invention belongs to the field of autonomous decision-making technology for autonomous vehicles, and specifically relates to a design method for a static reference path set for autonomous driving in urban traffic conditions. Background Technology

[0002] Autonomous vehicles are an emerging product of the deep integration of next-generation information technologies such as artificial intelligence and high-precision maps with the automotive industry. They are gradually becoming the main direction of intelligent development in the current transportation sector, and are progressively moving from single-structured traffic conditions to more complex urban traffic conditions. Compared to structured traffic conditions such as highways, urban traffic conditions involve a mix of pedestrians and vehicles, requiring vehicles to consider more safety constraints during operation. In particular, traffic flow is denser at intersections and roundabouts, which are widely distributed in urban road networks. Different types of traffic participants traveling in different directions intersect and interfere with each other simultaneously, easily leading to conflicts at intersections, resulting in traffic congestion and even accidents. Therefore, the interaction patterns in urban traffic conditions are more complex than in structured traffic conditions, and the decision-making and control of autonomous driving in this scenario is also more difficult. Addressing the traffic flow problems in urban conditions can not only greatly alleviate urban traffic pressure but also ensure road safety. Therefore, the development of high-level autonomous driving is of strategic significance.

[0003] Path planning is a crucial module in existing autonomous driving solutions. However, current planning methods suffer from the problem that designing the desired reference trajectory requires simultaneous consideration of both static constraints (including road geometry, ground markings, and traffic rules) and dynamic constraints (including motion constraints of surrounding pedestrians, bicycles, and motor vehicles, traffic light switching constraints, and vehicle dynamics constraints). Generating this desired reference trajectory necessitates online invocation of planning algorithms, resulting in numerous constraints and low computational efficiency. Therefore, a design method for static reference path sets in urban traffic conditions is needed to meet the requirements of high-level autonomous driving functions. Summary of the Invention

[0004] To address the aforementioned technical problems, the purpose of this invention is to provide a design method for a set of static reference paths for autonomous driving in complex urban traffic scenarios. This method solves the problems of numerous constraints, low online computation efficiency, and high path planning difficulty caused by the need to consider both static and dynamic constraints simultaneously in generating the desired reference trajectory in existing path planning methods. This invention has advantages such as being universally applicable to traffic scenarios, requiring fewer constraints, high offline computation efficiency, and lower path planning difficulty.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for designing a static reference path set for autonomous driving in urban traffic conditions includes the following steps:

[0007] S1. Determination of External Identifier Points: Based on the static road information provided by the high-precision map, determine the road segment information and lane information of the lane where the static reference path to be designed is located. Based on the road segment information and lane information of this lane, select the coordinates of the lateral midpoint of the lane's starting end and the lateral midpoint of the lane's ending end as the coordinates of two external identifier points (X) for generating the position information of the static reference path of this lane. i,1 and X i,2 ;

[0008] S2. Determination of Internal Marker Points: Based on the lane's starting and ending orientation angles, the lane widths of the two lanes connected to this lane, and the coordinates of the two external marker points determined in step S1, calculate the coordinates X of the two internal marker points used to generate the static reference path position information for this lane. i,3 and X i,4 ;

[0009] If the starting point of lane i faces angle θ i,1 and lane end facing angle θ i,2 satisfy: This lane is for a vehicle U-turn scenario, with the coordinates of the two internal marker points X. i,3 and X i,4 Calculated using Formula 1 and Formula 2 respectively; if the lane starting angle θ of lane i is... i,1 and lane end facing angle θ i,2 satisfy: This lane indicates a straight-ahead, turning, or lane-changing scenario, with the coordinates of the two internal marker points X. i,3 and X i,4 Calculated using Formula 3 and Formula 4 respectively;

[0010]

[0011]

[0012]

[0013]

[0014] In Formula 1 to Formula 4, D i Let X be the coordinates of the two external marker points of lane i. i,1 and X i,2 The distance between them, in meters (m), D i =|X i,1 -X i,2 |,X i,1 That is, the coordinates of the lateral midpoint of the starting end of the lane. (x i,1 ,yi,1 (x) represents the x-axis and y-axis coordinates of the transverse midpoint of the lane's starting end in the geodetic coordinate system; X i,2 That is, the coordinates of the lateral midpoint of the lane's end. (x i,K ,y i,K () represents the x-axis and y-axis coordinates of the lateral midpoint of the lane termination point in the geodetic coordinate system, and K represents the number of lateral midpoints from the lane start point to the lane termination point, i.e., the number of path points. That is, the position coordinates of the last point on the static reference path of lane i; The average lane width, in meters, of lanes l and r connected to lane i. L l L is the lane width of lane l. r Let r be the lane width; θ be the lane width. i,1 θ is the lane-starting angle of lane i, in rad; i,2 The lane termination angle of lane i is expressed in rad.

[0015] S3. Location Information Generation: Based on the coordinates of the two external marker points determined in step S1 and the coordinates of the two internal marker points determined in step S2, as well as the principle of generating third-order Bézier curves, the static reference path location information of the lane is generated using Formula 5.

[0016]

[0017] In formula 5, The position information of lane i is the static reference path; t is the position information of lane i. For the corresponding parameter t∈[0,1], if t takes K values ​​at equal intervals from [0,1], then the discretized value is obtained. k∈{1,2,3,…,K}, where K is the number of path points; X i,1 and X i,2 Here are the coordinates of two external marker points; X i,3 and X i,4 The coordinates of the two internal marker points;

[0018] S4. Orientation Angle Calculation: Based on the static reference path position coordinate information generated in step S3, calculate the orientation angle of the lane's static reference path using Formula 6.

[0019]

[0020] In formula 6, Let be the static reference path orientation angle of the k-th path point in lane i, in rad, k∈{1,2,3,…,K}, where K is the number of path points; and These represent the x-axis coordinates of the k-th and (k+1)-th path points of the static reference path for lane i, respectively, calculated using Formula 5. and These represent the y-axis coordinates of the k-th and (k+1)-th path points of the static reference path for lane i, respectively, calculated using Formula 5.

[0021] S5. Desired Rate Planning: Based on the road segment type and speed limit, plan the desired rate of the static reference path for this lane; the desired rate includes the desired traffic rate and the desired stopping rate.

[0022] S5.1 Desired Traffic Speed ​​Planning:

[0023] If the road segment where the lane is located is a multi-vehicle road segment, the expected traffic rate of the path points of the static reference path of the lane is calculated by formula 7; if the road segment where the lane is located is an intersection or roundabout segment, the expected traffic rate of the path points of the static reference path of the lane is calculated by formula 8.

[0024]

[0025]

[0026] In formulas 7 and 8, This represents the expected traffic speed at the k-th path point of the static reference path for lane i, in m / s. The speed limit for road segment m where lane i is located is given in km / h.

[0027] S5.2 Desired Parking Speed ​​Planning:

[0028] If the road segment in which the lane is located is a multi-vehicle road segment, and the next road segment connected to this road segment is an intersection or roundabout, then the lane is determined based on a fixed distance d before the stop line of the intersection or roundabout. m Including the vehicle's half-length c, the road segment is divided sequentially from the starting point to the ending point into segments with no fixed distance and segments with a fixed distance length d. m -c segment and the remaining fixed distance segment is c segment; where, the expected stopping rate of the path point of the static reference path of this lane that has not entered the fixed distance segment is calculated by formula 9, and the fixed distance segment d is calculated by formula 10. m -The expected stopping rate of the path point of the static reference path of the lane in segment c is calculated by formula 11.

[0029] If the road segment where the lane is located is a multi-vehicle road segment, and the next road segment connected to this road segment is also a multi-vehicle road segment, then the expected stopping rate of the path points of the static reference path of the lane is calculated by formula 9.

[0030] If the road segment where the lane is located is an intersection or roundabout, the expected stopping rate of the path points of the static reference path of the lane is calculated using Formula 11.

[0031]

[0032]

[0033]

[0034] In Formula 9 to Formula 11, This represents the expected stopping speed at the k-th path point of the static reference path for lane i, in m / s. This represents the expected stopping speed at the (k+1)th path point of the static reference path for lane i, in m / s. The speed limit for road segment m containing lane i is given in km / h; Δs is the distance between two adjacent path points on the static reference path of lane i; a i To enter a fixed distance of length d m The uniform deceleration of all lanes in section -c, in m / s², is calculated using formula 12.

[0035]

[0036] In Formula 12, v stop The stopping speed at the lane stop line, in m / s; The speed limit for road segment m containing lane i, in km / h; d m is a fixed distance in meters from the stop line of the intersection or roundabout section where lane i is located; c is the half length of the vehicle body in meters.

[0037] S6. Static reference path set generation: The lane static reference path position information obtained in step S3, the lane static reference path orientation angle obtained in step S4, and the lane static reference path expected rate obtained in step S5 are combined sequentially using formula 13 to obtain the complete information of each path point of the static reference path. The full map static reference path set is obtained using formula 14.

[0038]

[0039]

[0040] In formulas 13 and 14, Pi For lane i, a static reference path containing complete information. The location information of the kth path point of the static reference path for lane i; The static reference path orientation angle of the kth path point of the static reference path for lane i, in rad; Let be the expected traffic speed at the k-th path point of the static reference path for lane i, in m / s; Let K be the expected stopping speed at the k-th path point of the static reference path for lane i, in m / s; K is the number of path points. is the set of static reference paths on the entire map; I is the number of lanes.

[0041] The static road information includes road segment information and lane information;

[0042] The road segment information includes road segment ID, road segment type, and road segment speed limit; the road segment type includes multi-vehicle road segment, intersection road segment, and roundabout road segment; among which, roundabout road segments are divided into three types of sub-segments: roundabout entrance sub-segment, roundabout exit sub-segment, and roundabout interior sub-segment;

[0043] The lane information includes lane ID, lane type, lane width, coordinates of the lateral midpoint of the lane's starting end, coordinates of the lateral midpoint of the lane's ending end, lane's starting angle, lane's ending angle, and road connectivity.

[0044] The lane types include real lanes with lane markings in multi-vehicle road sections and roundabout sections, as well as virtual lanes that are passable but do not have lane markings in intersection sections.

[0045] The orientation angle is the angle between the lane orientation and the positive x-axis of the geodetic coordinate system;

[0046] The road connectivity relationship is the next connecting road segment ID and lane ID that connects to the current lane.

[0047] The fixed distance d before the stop line of a road segment entering an intersection or roundabout. m That is, the prescribed length of the solid lane line when approaching an intersection or roundabout, d m =30m.

[0048] The distance Δs between two adjacent path points of the static reference path of lane i is 0.05m.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] This invention generates a static reference path set for autonomous driving in urban traffic conditions through six steps: external marker point determination, internal marker point determination, location information generation, orientation angle calculation, desired rate planning, and static reference path set generation. It relies solely on the static road information provided by the map to realize a full map static reference path set that can be planned and stored in advance, effectively ensuring the realization of autonomous vehicle decision control functions. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of the overall process of an embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram of static reference path location information in a typical scenario according to an embodiment of the present invention;

[0054] Figure 4 This is a schematic diagram of the expected rate planning in an embodiment of the present invention. Detailed Implementation

[0055] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0056] like Figure 1 and Figure 2 As shown, a method for designing a static reference path set for autonomous driving in urban traffic conditions includes the following steps:

[0057] S1. Determination of External Identifier Points: Based on the static road information provided by the high-precision map, determine the road segment information and lane information of the lane where the static reference path to be designed is located. Based on the road segment information and lane information of this lane, select the coordinates of the lateral midpoint of the lane's starting end and the lateral midpoint of the lane's ending end as the coordinates of two external identifier points (X) for generating the position information of the static reference path of this lane. i,1 and X i,2 ;

[0058] The static road information includes road segment information and lane information;

[0059] The road segment information includes road segment ID, road segment type, and road segment speed limit; the road segment type includes multi-vehicle road segment, intersection road segment, and roundabout road segment; among which, the roundabout road segment is divided into three types of sub-segments: roundabout entrance sub-segment, roundabout exit sub-segment, and roundabout interior sub-segment.

[0060] The lane information includes lane ID, lane type, lane width, coordinates of the lateral midpoint of the lane's starting end, coordinates of the lateral midpoint of the lane's ending end, lane's starting angle, lane's ending angle, and road connectivity.

[0061] The lane types include real lanes with lane markings in multi-vehicle road sections and roundabout sections, as well as virtual lanes that are passable but do not have lane markings in intersection sections.

[0062] The orientation angle is the angle between the lane orientation and the positive x-axis of the geodetic coordinate system;

[0063] The road connectivity relationship is the next connecting road segment ID and lane ID that connects to the current lane.

[0064] In an embodiment of the present invention, Figure 3 The example demonstrates how to determine the external marker points required to generate static reference path location information for a lane in a multi-vehicle road segment, a left-turn virtual lane and a U-turn virtual lane in an intersection segment, and a roundabout entrance sub-segment lane, a roundabout exit sub-segment lane, and a roundabout internal sub-segment lane in a roundabout segment. Specifically, in multi-vehicle road segment M, for a straight-to-right-turn lane, the coordinates of the starting lateral midpoint M1 of that lane are selected. The position coordinates of the lateral midpoint M2 at the termination end The coordinates of two external marker points are used to generate the static reference path position information on this lane.

[0065] In an intersection, for a left-turn virtual lane within the intersection, select the coordinates of the lateral midpoint J1 at the starting end of the virtual lane. That is, the coordinate X in the figure i,1 The position coordinates of the lateral midpoint J2 at the termination end That is, the coordinate X in the figure i,2 These are two external marker points used to generate the static reference path location information for the left-turn virtual lane.

[0066] In an intersection, for a virtual U-turn lane within the intersection, select the coordinates of the lateral midpoint U1 at the starting end of the virtual lane. The position coordinates of the lateral midpoint U2 at the termination end Two external markers are used to generate the static reference path location information for the left-turn virtual lane. In a roundabout segment, one roundabout entrance sub-segment is divided by line segments OA and OB, one roundabout interior sub-segment is divided by line segments OB and OC, and one roundabout exit sub-segment is divided by line segments OC and OD. The division of other sub-segments within the same roundabout is similar to the above-mentioned roundabout sub-segment division method.

[0067] For a roundabout entrance sub-segment defined by line segments OA and OB, for a straight-turning right-turn lane within this sub-segment, select the coordinates of the transverse midpoint E1 at the starting end of that lane. The coordinates of the lateral midpoint E2 at the termination end These serve as two external marker points for generating static reference path location information for this lane.

[0068] For a sub-segment within a roundabout defined by line segments OB and OC, for each lane within this sub-segment, select the coordinates of the transverse midpoint F1 at the starting end of that lane. The position coordinates of the lateral midpoint F2 at the termination end These serve as two external marker points for generating static reference path location information for this lane.

[0069] For a roundabout exit sub-segment defined by line segments OC and OD, for one lane within this sub-segment, select the coordinates of the transverse midpoint G1 at the starting end of that lane. The position coordinates of the lateral midpoint G2 at the termination end These serve as two external marker points for generating static reference path location information for this lane.

[0070] The method for determining the external markers required to generate static reference path location information for other lanes on the map is the same as that shown in this example.

[0071] S2. Determination of Internal Marker Points: Based on the lane's starting and ending orientation angles, the lane widths of the two lanes connected to this lane, and the coordinates of the two external marker points determined in step S1, calculate the coordinates X of the two internal marker points used to generate the static reference path position information for this lane. i,3 and X i,4 ;

[0072] If the starting point of lane i faces angle θ i,1 and lane end facing angle θ i,2 satisfy: This lane is for a vehicle U-turn scenario, with the coordinates of the two internal marker points X. i,3 and X i,4 Calculated using Formula 1 and Formula 2 respectively; if the lane starting angle θ of lane i is... i,1 and lane end facing angle θ i,2 satisfy: This lane indicates a straight-ahead, turning, or lane-changing scenario, with the coordinates of the two internal marker points X. i,3 and X i,4 Calculated using Formula 3 and Formula 4 respectively;

[0073]

[0074]

[0075]

[0076]

[0077] In Formula 1 to Formula 4, D i Let X be the coordinates of the two external marker points of lane i. i,1 and X i,2 The distance between them, in meters (m), D i =|X i,1 -X i,2 |,X i,1 That is, the coordinates of the lateral midpoint of the starting end of the lane. (x i,1 ,y i,1 (x) represents the x-axis and y-axis coordinates of the transverse midpoint of the lane's starting end in the geodetic coordinate system; X i,2 That is, the coordinates of the lateral midpoint of the lane's end. (x i,K ,y i,K () represents the x-axis and y-axis coordinates of the lateral midpoint of the lane termination point in the geodetic coordinate system, and K represents the number of lateral midpoints from the lane start point to the lane termination point, i.e., the number of path points. That is, the position coordinates of the last point on the static reference path of lane i; The average lane width, in meters, of lanes l and r connected to lane i. L l L is the lane width of lane l. r Let r be the lane width; θ be the lane width. i,1 θ is the lane-starting angle of lane i, in rad; i,2 The lane termination angle of lane i is expressed in rad.

[0078] S3. Location Information Generation: Based on the coordinates of the two external marker points determined in step S1 and the coordinates of the two internal marker points determined in step S2, as well as the principle of generating third-order Bézier curves, the static reference path location information of the lane is generated using Formula 5.

[0079]

[0080] In formula 5, The position information of lane i is the static reference path; t is the position information of lane i. For the corresponding parameter t∈[0,1], if t takes K values ​​at equal intervals from [0,1], then the discretized value is obtained. k∈{1,2,3,…,K}, where K is the number of path points; X i,1 and X i,2 Here are the coordinates of two external marker points; X i,3 and X i,4The coordinates of the two internal marker points;

[0081] S4. Orientation Angle Calculation: Based on the static reference path position coordinate information generated in step S3, calculate the orientation angle of the lane's static reference path using Formula 6.

[0082]

[0083] In formula 6, Let be the static reference path orientation angle of the k-th path point in lane i, in rad, k∈{1,2,3,…,K}, where K is the number of path points; and These represent the x-axis coordinates of the k-th and (k+1)-th path points of the static reference path for lane i, respectively, calculated using Formula 5. and These represent the y-axis coordinates of the k-th and (k+1)-th path points of the static reference path for lane i, respectively, calculated using Formula 5.

[0084] S5. Desired Rate Planning: Based on the road segment type and speed limit, plan the desired rate of the static reference path for this lane; the desired rate includes the desired traffic rate and the desired stopping rate.

[0085] S5.1 Desired Traffic Speed ​​Planning:

[0086] If the road segment where the lane is located is a multi-vehicle road segment, the expected traffic rate of the path points of the static reference path of the lane is calculated by formula 7; if the road segment where the lane is located is an intersection or roundabout segment, the expected traffic rate of the path points of the static reference path of the lane is calculated by formula 8.

[0087]

[0088]

[0089] In formulas 7 and 8, This represents the expected traffic speed at the k-th path point of the static reference path for lane i, in m / s. The speed limit for road segment m where lane i is located is given in km / h.

[0090] S5.2 Desired Parking Speed ​​Planning:

[0091] If the road segment in which the lane is located is a multi-vehicle road segment, and the next road segment connected to this road segment is an intersection or roundabout, then the lane is determined based on a fixed distance d before the stop line of the intersection or roundabout. m(i.e., the prescribed length of the solid lane line when approaching an intersection or roundabout, usually taken as 30m) and the half-length of the vehicle c, the road segment is divided sequentially from the beginning to the end into a segment that has not entered the fixed distance and a segment that has entered the fixed distance with a length of d. m -c segment and the remaining fixed distance segment is c segment; where, the expected stopping rate of the path point of the static reference path of this lane that has not entered the fixed distance segment is calculated by formula 9, and the fixed distance segment d is calculated by formula 10. m -The expected stopping rate of the path point of the static reference path of the lane in segment c is calculated by formula 11.

[0092] If the road segment where the lane is located is a multi-vehicle road segment, and the next road segment connected to this road segment is also a multi-vehicle road segment, then the expected stopping rate of the path points of the static reference path of the lane is calculated by formula 9.

[0093] If the road segment where the lane is located is an intersection or roundabout, the expected stopping rate of the path points of the static reference path of the lane is calculated using Formula 11.

[0094]

[0095]

[0096]

[0097] In Formula 9 to Formula 11, This represents the expected stopping speed at the k-th path point of the static reference path for lane i, in m / s. This represents the expected stopping speed at the (k+1)th path point of the static reference path for lane i, in m / s. The speed limit for road segment m containing lane i is given in km / h; Δs is the distance between two adjacent path points on the static reference path of lane i, typically taken as 0.05m; a i To enter a fixed distance of length d m The uniform deceleration of all lanes in section -c, in m / s², is calculated using formula 12.

[0098]

[0099] In Formula 12, v stop The stopping speed at the lane stop line, in m / s; The speed limit for road segment m containing lane i, in km / h; d mis a fixed distance in meters from the stop line of the intersection or roundabout section where lane i is located; c is the half length of the vehicle body in meters.

[0100] S6. Static reference path set generation: The lane static reference path position information obtained in step S3, the lane static reference path orientation angle obtained in step S4, and the lane static reference path expected rate obtained in step S5 are combined sequentially using formula 13 to obtain the complete information of each path point of the static reference path. The full map static reference path set is obtained using formula 14.

[0101]

[0102]

[0103] In formulas 13 and 14, P i For lane i, a static reference path containing complete information. The location information of the kth path point of the static reference path for lane i; The static reference path orientation angle of the kth path point of the static reference path for lane i, in rad; Let be the expected traffic speed at the k-th path point of the static reference path for lane i, in m / s; Let K be the expected stopping speed at the k-th path point of the static reference path for lane i, in m / s; K is the number of path points. is the set of static reference paths on the entire map; I is the number of lanes.

[0104] like Figure 3 The embodiment shown illustrates the static reference path location information corresponding to one lane in a multi-lane network, one virtual left-turn lane and one virtual U-turn lane in an intersection, and one roundabout entrance sub-segment lane, one roundabout exit sub-segment lane and one roundabout internal sub-segment lane in a roundabout. The static reference path location information of other lanes on the generated map is similar to that shown in this example.

[0105] In multi-vehicle road segment M, for the straight-to-right-turn lane, the coordinates of two external marker points M1 and M2, which generate the static reference path position information for this lane, are known. and two internal markers M3 and M4 and their coordinates The location information of the path points of the static reference path on this lane is calculated according to Formula 5. Figure 3 The connection points M1 and M2 are shown in bold black dashed lines.

[0106] In an intersection, for a left-turn virtual lane within the intersection, two external marker points J1 and J2, along with their coordinates, are known to generate the static reference path position information for this virtual lane. and two internal markers J3 and J4 and their coordinates The location information of the path points of the static reference path on this lane is calculated according to Formula 5. Figure 3 The connection points J1 and J2 are shown in bold black dashed lines.

[0107] In an intersection, for a virtual U-turn lane within the intersection, two external marker points U1 and U2, along with their coordinates, are known to generate the static reference path location information for this virtual lane. and two internal markers U3 and U4 and their coordinates The location information of the path points of the static reference path on this lane is calculated according to Formula 5. Figure 3 The connection points U1 and U2 are shown in bold black dashed lines.

[0108] In a roundabout section, for a sub-segment of the roundabout entrance defined by line segments OA and OB, for a straight-to-right-turn lane within this sub-segment, two external marker points E1 and E2, along with their coordinates, are known to generate the static reference path position information for this lane. and two internal markers E3 and E4 and their coordinates The location information of the path points of the static reference path on this lane is calculated according to Formula 5. Figure 3 The connection points E1 and E2 are shown in bold black dashed lines.

[0109] For a sub-segment within a roundabout defined by line segments OB and OC, for one lane within this sub-segment, two external marker points F1 and F2, along with their coordinates, are known to generate the static reference path position information for that lane. and two internal markers F3 and F4 and their coordinates The location information of the path points of the static reference path on this lane is calculated according to Formula 5. Figure 3 The connection points F1 and F2 are shown in bold black dashed lines.

[0110] For a roundabout exit sub-segment defined by line segments OC and OD, for one lane within this sub-segment, two external marker points G1 and G2, along with their coordinates, are known to generate the static reference path position information for that lane. and two internal marker points G3 and G4 and their coordinates The location information of the discrete points of the static reference path on this lane is calculated according to Formula 5. Figure 3The connection points G1 and G2 are shown in bold black dashed lines.

[0111] Figure 4 Combination Figure 3 The example demonstrates the expected speed of the static reference path corresponding to one lane in a multi-lane road plan, one virtual left-turn lane and one virtual U-turn lane in an intersection, and one lane at the entrance of a roundabout. The expected speed of the static reference path of other lanes on the planning map is similar to that shown in this example.

[0112] For one lane in a multi-lane road, by Figure 3 As can be seen, the road segment type where points M1 and M2 are located is multi-lane. For the desired traffic rate planning, the desired traffic rate of the static reference path on this lane can be planned using Formula 7, i.e., the corresponding... Figure 4 Desired traffic speed planning for segment Q1Q2. Regarding the desired stopping speed planning, since the next road segment connecting to the lanes containing points M1 and M2 is still multi-lane, the desired stopping speed of the static reference path on the lanes containing points M1 and M2 can be planned using Formula 9, i.e., corresponding to... Figure 4 Desired parking speed planning for section H1H2.

[0113] For a virtual left-turn lane at the intersection, by Figure 3 As can be seen, the road segment type of the left-turn virtual lanes where points J1 and J2 are located is an intersection. For the desired traffic rate planning, the desired traffic rate of the static reference path on this left-turn virtual lane can be planned using Formula 8, i.e., the corresponding... Figure 4 Desired traffic speed planning for section Q2Q3. For desired stopping speed planning, the desired stopping speed of the static reference path on this left-turn virtual lane can be planned using Formula 11, i.e., corresponding to... Figure 4 Desired parking speed planning for sections H3 and H4.

[0114] For a virtual U-turn lane at the intersection, by Figure 3 As can be seen, the road segment type of the U-turn virtual lanes where points U1 and U2 are located is an intersection. The expected traffic speed of the static reference path on this U-turn virtual lane can be planned using Formula 8, that is, the corresponding... Figure 4 Desired traffic speed planning for section Q2Q3. For desired stopping speed planning, the desired stopping speed of the static reference path on this U-turn virtual lane can be planned using Formula 11, i.e., corresponding to... Figure 4 Desired parking speed planning for sections H3 and H4.

[0115] For one of the sub-lanes at the roundabout entrance, by Figure 3As can be seen, the road segment type of the roundabout entrance sub-segment lanes where points E1 and E2 are located is a roundabout. The expected traffic speed of the static reference path on the roundabout entrance sub-segment lanes can be planned using Formula 8, that is, the corresponding... Figure 4 Desired traffic speed planning for section Q2Q3. For desired stopping speed planning, the desired stopping speed of the static reference path on the lanes of this roundabout entrance sub-section can be planned using Formula 11, i.e., corresponding to... Figure 4 Desired parking speed planning for sections H3 and H4.

Claims

1. A method for designing a static reference path set for automated driving in urban traffic conditions, characterized in that, The method includes the following steps: S1. External Identifier Point Determination: Based on the static road information provided by the high-precision map, determine the road segment information and lane information of the lane where the static reference path to be designed is located. Based on the road segment information and lane information of this lane, select the coordinates of the lateral midpoint of the lane's starting end and the lateral midpoint of the lane's ending end as the coordinates of two external identifier points (X) for generating the position information of the static reference path of this lane. i,1 and X i,2 ; S2. Determination of Internal Marker Points: Based on the lane's starting and ending orientation angles, the lane widths of the two lanes connected to this lane, and the coordinates of the two external marker points determined in step S1, calculate the coordinates X of the two internal marker points used to generate the static reference path position information for this lane. i,3 and X i,4 ; If the starting point of lane i faces angle θ i,1 and lane end facing angle θ i,2 satisfy: This lane is for a vehicle U-turn scenario, with the coordinates of the two internal marker points X. i,3 and X i,4 Calculated using Formula 1 and Formula 2 respectively; if the lane starting angle θ of lane i is... i,1 and lane end facing angle θ i,2 satisfy: This lane indicates a straight-ahead, turning, or lane-changing scenario, with the coordinates of the two internal marker points X. i,3 and X i,4 Calculated using Formula 3 and Formula 4 respectively; In Formula 1 to Formula 4, D i Let X be the coordinates of the two external marker points of lane i. i,1 and X i,2 The distance between them, in meters (m), D i =|X i,1 -X i,2 |,X i,1 That is, the coordinates of the lateral midpoint of the starting end of the lane. (x i,1 ,y i,1 (x) represents the x-axis and y-axis coordinates of the transverse midpoint of the lane's starting end in the geodetic coordinate system; X i,2 That is, the coordinates of the lateral midpoint of the lane's end. (x i,K ,y i,K () represents the x-axis and y-axis coordinates of the lateral midpoint of the lane termination point in the geodetic coordinate system, and K represents the number of lateral midpoints from the lane start point to the lane termination point, i.e., the number of path points. That is, the position coordinates of the last point on the static reference path of lane i; The average lane width, in meters, of lanes l and r connected to lane i. L l L is the lane width of lane l. r Let r be the lane width; θ be the lane width. i,1 θ is the lane-starting angle of lane i, in rad; i,2 The lane termination angle of lane i is expressed in rad. S3. Location Information Generation: Based on the coordinates of the two external marker points determined in step S1 and the coordinates of the two internal marker points determined in step S2, as well as the principle of generating third-order Bézier curves, the static reference path location information of the lane is generated using Formula 5. In formula 5, The position information of lane i is the static reference path; t is the position information of lane i. For the corresponding parameter t∈[0,1], if t takes K values ​​at equal intervals from [0,1], then the discretized value is obtained. K is the number of path points; X i,1 and X i,2 Here are the coordinates of two external marker points; X i,3 and X i,4 The coordinates of the two internal marker points; S4. Orientation Angle Calculation: Based on the static reference path position coordinate information generated in step S3, calculate the orientation angle of the lane's static reference path using Formula 6. In formula 6, Let be the static reference path orientation angle of the k-th path point in lane i, in rad, k∈{1,2,3,…,k}, and K be the number of path points; and These represent the x-axis coordinates of the k-th and (k+1)-th path points of the static reference path for lane i, respectively, calculated using Formula 5. and These represent the y-axis coordinates of the k-th and (k+1)-th path points of the static reference path for lane i, respectively, calculated using Formula 5. S5. Desired Rate Planning: Based on the road segment type and speed limit, plan the desired rate of the static reference path for this lane; the desired rate includes the desired traffic rate and the desired stopping rate. S5.1 Desired Traffic Speed ​​Planning: If the road segment where the lane is located is a multi-vehicle road segment, the expected traffic rate of the path points of the static reference path of the lane is calculated by formula 7; if the road segment where the lane is located is an intersection or roundabout segment, the expected traffic rate of the path points of the static reference path of the lane is calculated by formula 8. In formulas 7 and 8, This represents the expected traffic speed at the k-th path point of the static reference path for lane i, in m / s. The speed limit for road segment m where lane i is located is given in km / h. S5.2 Desired Parking Speed ​​Planning: If the road segment in which the lane is located is a multi-vehicle road segment, and the next road segment connected to this road segment is an intersection or roundabout, then the lane is determined based on a fixed distance d before the stop line of the intersection or roundabout. m Including the vehicle's half-length c, the road segment is divided sequentially from the starting point to the ending point into segments with no fixed distance and segments with a fixed distance length d. m -c segment and the remaining fixed distance segment is c segment; where, the expected stopping rate of the path point of the static reference path of this lane that has not entered the fixed distance segment is calculated by formula 9, and the fixed distance segment d is calculated by formula 10. m -The expected stopping rate of the path point of the static reference path of the lane in segment c is calculated by formula 11. If the road segment where the lane is located is a multi-vehicle road segment, and the next road segment connected to this road segment is also a multi-vehicle road segment, then the expected stopping rate of the path points of the static reference path of the lane is calculated by formula 9. If the road segment where the lane is located is an intersection or roundabout, the expected stopping rate of the path points of the static reference path of the lane is calculated using Formula 11. In Formula 9 to Formula 11, This represents the expected stopping speed at the k-th path point of the static reference path for lane i, in m / s. This represents the expected stopping speed at the (k+1)th path point of the static reference path for lane i, in m / s. The speed limit for road segment m containing lane i is given in km / h; Δs is the distance between two adjacent path points on the static reference path of lane i; a i To enter a fixed distance of length d m The uniform deceleration of all lanes in section -c, in m / s², is calculated using formula 12. In Formula 12, v stop The stopping speed at the lane stop line, in m / s; The speed limit for road segment m containing lane i, in km / h; d m is a fixed distance in meters from the stop line of the intersection or roundabout section where lane i is located; c is the half length of the vehicle body in meters. S6. Static reference path set generation: The lane static reference path position information obtained in step S3, the lane static reference path orientation angle obtained in step S4, and the lane static reference path expected rate obtained in step S5 are combined sequentially using formula 13 to obtain the complete information of each path point of the static reference path. The full map static reference path set is obtained using formula 14. In formulas 13 and 14, P i For lane i, a static reference path containing complete information. The location information of the kth path point of the static reference path for lane i; The static reference path orientation angle of the kth path point of the static reference path for lane i, in rad; Let be the expected traffic speed at the k-th path point of the static reference path for lane i, in m / s; Let K be the expected stopping speed at the k-th path point of the static reference path for lane i, in m / s; K is the number of path points. is the set of static reference paths on the entire map; I is the number of lanes.

2. The method according to claim 1, characterized in that, The static road information includes road segment information and lane information; The road segment information includes road segment ID, road segment type, and road segment speed limit; the road segment type includes multi-vehicle road segment, intersection road segment, and roundabout road segment; among which, roundabout road segments are divided into three types of sub-segments: roundabout entrance sub-segment, roundabout exit sub-segment, and roundabout interior sub-segment; The lane information includes lane ID, lane type, lane width, coordinates of the lateral midpoint of the lane's starting end, coordinates of the lateral midpoint of the lane's ending end, lane's starting angle, lane's ending angle, and road connectivity. The lane types include real lanes with lane markings in multi-vehicle road sections and roundabout sections, as well as virtual lanes that are passable but do not have lane markings in intersection sections. The orientation angle is the angle between the lane orientation and the positive x-axis of the geodetic coordinate system; The road connectivity relationship is the next connecting road segment ID and lane ID that connects to the current lane.

3. The method according to claim 1, characterized in that, The fixed distance d before the stop line of a road segment entering an intersection or roundabout. m That is, the prescribed length of the solid lane line when approaching an intersection or roundabout, d m =30m.

4. The method according to claim 1, characterized in that, The distance Δs between two adjacent path points of the static reference path of lane i is 0.05m.

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