Turnaround line construction method, system, turnaround method, and medium

Abstract

The application discloses a U-turn line construction method, system, U-turn method and medium, and belongs to the technical field of automatic driving. The method comprises the following steps: determining a starting point and an ending point of a vehicle for U-turn; determining a plurality of groups of U-turn line control points according to the starting point and the ending point; generating a plurality of Bezier curves corresponding to the starting point, the ending point and the plurality of groups of U-turn line control points; calculating the curvatures of each point in the Bezier curves and the distances between each point and static obstacles; and determining the corresponding Bezier curve as the U-turn line when the distance and the curvature both meet the corresponding preset conditions. When the application generates the U-turn line of the automatic driving vehicle, the U-turn line is generated by using the generation method of the Bezier curve, the curvature and the distance are simultaneously constrained, the smoothness of the U-turn line is ensured, and the automatic driving vehicle has good safety and high driving experience when the automatic driving vehicle performs U-turn according to the U-turn line.

Description

Technical Field

[0001] This application relates to the field of autonomous driving technology, and in particular to a method, system, method and medium for constructing a U-turn lane. Background Technology

[0002] During autonomous driving, autonomous vehicles follow pre-designed routes on high-precision maps. Therefore, the planning and design of these routes are fundamental to ensuring a good driving experience. Especially when making a U-turn, a well-planned U-turn line ensures a smooth turn and a positive driving experience.

[0003] In the process of driving control of autonomous vehicles, when autonomous vehicles are making U-turns, in addition to ensuring that the vehicle avoids collisions with static obstacles such as road edges and ensures driving safety, it is also necessary to ensure that the planned U-turn line is feasible, conforms to the vehicle's own mechanical performance, and ensures the smoothness of the U-turn line to avoid sharp turns that would reduce the driving experience for passengers. Summary of the Invention

[0004] To address the issues of low safety of planned U-turn lines when autonomous vehicles make U-turns, as well as the uneven U-turn lines caused by sharp turns, resulting in a poor driving experience for passengers, this application proposes a U-turn line construction method, system, U-turn method, medium, and equipment.

[0005] In a first aspect, this application provides a method for constructing a U-turn line, comprising: determining the starting point and ending point of a vehicle making a U-turn; determining multiple sets of U-turn line control points based on the starting point and ending point; generating multiple Bézier curves corresponding to the starting point, ending point, and multiple sets of U-turn line control points; calculating the curvature of each point in the Bézier curve and the distance between each point and a static obstacle; and determining the corresponding Bézier curve as a U-turn line under the condition that the distance and curvature both meet the corresponding preset conditions.

[0006] Optionally, multiple sets of U-turn control points are determined based on the starting point and the ending point, including: selecting multiple points as first U-turn control points within a first distance range from the starting point in a first direction and within a second distance range from the starting point in a second direction, wherein the first direction is the longitudinal extension direction of the lane where the vehicle is located, and the second direction is perpendicular to the first direction; selecting multiple points as second U-turn control points on the side of the line connecting the starting point and the first U-turn control points away from the lane into which the vehicle is to make a U-turn, within a third distance range from the starting point in the first direction and within a fourth distance range from the first U-turn control point in the second direction. U-turn control points: Within a first distance from the end point in the first direction and within a second distance from the end point in the second direction, multiple points are selected as third U-turn control points; On the side of the line connecting the end point and the third U-turn control points away from the lane where the vehicle is about to make a U-turn, within a third distance from the end point in the first direction and within a fifth distance from the end point in the second direction, multiple points are selected as fourth U-turn control points. Multiple combinations of single first, second, third, and fourth U-turn control points are obtained to obtain multiple sets of U-turn control points.

[0007] Optionally, if both the distance and curvature meet the corresponding preset conditions, the Bézier curve is determined as a turning line, including: if the distance between each point on the Bézier curve and the static obstacle is greater than or equal to a first preset distance threshold, the Bézier curve is determined as the distance-optimal curve; if the distance is less than the first preset distance threshold but greater than or equal to a second preset distance threshold, the Bézier curve is determined as the distance-second-optimal curve; if the distance is less than the second preset distance threshold, the Bézier curve is eliminated.

[0008] Optionally, if both the distance and curvature meet the corresponding preset conditions, the Bézier curve is determined as a turning line, including: if the curvature of each point in the Bézier curve is less than or equal to a first preset curvature threshold, the Bézier curve is determined as the optimal curvature curve; if the curvature is greater than the first preset curvature threshold but less than or equal to a second preset curvature threshold, the Bézier curve is determined as the second optimal curvature curve; if the curvature is greater than the second preset curvature threshold, the Bézier curve is removed.

[0009] Optionally, if both the distance and curvature meet the corresponding preset conditions, the Bézier curve is determined as a turning line, including: determining the Bézier curve as a turning line when the Bézier curve satisfies the optimal distance curve and the optimal curvature curve; or determining the Bézier curve as a turning line when the Bézier curve satisfies the optimal distance curve and the second-optimal curvature curve; or determining the Bézier curve as a turning line when the Bézier curve satisfies the second-optimal distance curve and the optimal curvature curve; or determining the Bézier curve as a turning line when the Bézier curve satisfies the second-optimal distance curve and the optimal curvature curve.

[0010] Optionally, if the distance and curvature both meet the corresponding preset conditions, the Bézier curve is determined as a U-turn line. This also includes: if the distance and curvature of the Bézier curve both meet the corresponding preset conditions, calculating the entry angle of the Bézier curve between the starting point and the straight extension line of the vehicle and the exit angle of the Bézier curve between the ending point and the straight extension line of the vehicle; if the entry angle is less than a first angle threshold and the second angle is less than a second angle threshold, the Bézier curve is determined as a U-turn line.

[0011] Optionally, the starting and ending points of the vehicle's U-turn can be determined, including: taking the midpoint of the intersection stop line of the lane where the vehicle was before making the U-turn as the starting point, and taking the midpoint of the intersection stop line of the lane into which the vehicle is about to make the U-turn as the ending point.

[0012] Secondly, this application provides a U-turn line construction system, comprising: a start-end point determination module, which determines the start and end points of a vehicle making a U-turn; a U-turn line control point determination module, which determines multiple sets of U-turn line control points based on the start and end points; a Bézier curve determination module, which generates multiple Bézier curves corresponding to the start and end points and the multiple sets of U-turn line control points; a calculation module, which calculates the curvature of each point in the Bézier curve and the distance between each point and a static obstacle; and a U-turn line determination module, which determines the Bézier curve as a U-turn line if the distance and curvature both meet the corresponding preset conditions.

[0013] Thirdly, this application provides a U-turn method, comprising: determining the starting point and ending point of the vehicle U-turn; determining multiple sets of U-turn line control points based on the starting point and ending point; generating multiple Bézier curves corresponding to the starting point, ending point, and multiple sets of U-turn line control points; calculating the curvature of each point in the Bézier curve and the distance between each point and a static obstacle; determining the Bézier curve as the U-turn line if the distance and curvature both meet the corresponding preset conditions; and controlling the autonomous vehicle to perform autonomous U-turn according to the U-turn line.

[0014] Fourthly, this application provides a computer-readable storage medium storing computer instructions that, when executed, cause a computer to perform the method in Scheme 1 or Scheme 3.

[0015] Fifthly, this application provides a computer device including a processor and a memory, the memory storing computer instructions, which, when executed by the processor, implement the method as described in Scheme 1 or Scheme 3.

[0016] The technical solution of this application embodiment utilizes the Bézier curve generation method to generate a U-turn line through multiple U-turn line control points. Simultaneously, it constrains the curvature of the U-turn line and the distance to static obstacles to ensure the smoothness of the U-turn line. This improves the safety and driving experience of the vehicle when making a U-turn according to the U-turn line. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description exemplarily illustrate some embodiments of this application.

[0018] Figure 1 This is a schematic diagram of a specific implementation of the method for constructing a turning line in this application;

[0019] Figure 2 This is a schematic diagram of the starting and ending points of the U-turn line in this application;

[0020] Figure 3 This is a schematic diagram illustrating an example of selecting control points for a U-turn line;

[0021] Figure 4 This is a schematic diagram of an example of a Bézier curve;

[0022] Figure 5 This is a schematic diagram illustrating an example of the entry and exit angles of a U-turn line;

[0023] Figure 6 This is a schematic diagram of one embodiment of the U-turn line construction system of this application;

[0024] Figure 7 This is a schematic diagram of one implementation of the turning method of this application.

[0025] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0026] The preferred embodiments of this application will now be described in detail with reference to the accompanying drawings, so that the advantages and features of this application can be more easily understood by those skilled in the art, thereby providing a clearer and more definite definition of the scope of protection of this application.

[0027] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0028] In the process of driving control of autonomous vehicles, when autonomous vehicles are making U-turns, in addition to ensuring that the vehicle avoids collisions with static obstacles such as road edges and ensures driving safety, it is also necessary to ensure that the planned U-turn line is feasible, conforms to the vehicle's own mechanical performance, and ensures the smoothness of the U-turn line to avoid sharp turns that would reduce the driving experience for passengers.

[0029] To address the aforementioned issues, this application employs the generation principle of Bezier curves to generate U-turn lines, ensuring their smoothness and guaranteeing the smoothness of autonomous vehicles when making U-turns along these lines, thus enhancing the driver's driving experience. Simultaneously, it controls the distance between the U-turn line and static obstacles, as well as the curvature of the U-turn line, to ensure the safety of autonomous vehicles making U-turns along these lines, avoiding collisions, while also ensuring compliance with the mechanical properties of the autonomous vehicle itself, guaranteeing the smooth completion of U-turns.

[0030] Therefore, this application proposes a method, system, method, medium, and equipment for constructing a U-turn line. The method for constructing a U-turn line includes: determining the starting and ending points of a vehicle's U-turn; determining multiple sets of U-turn line control points based on the starting and ending points; generating multiple Bézier curves corresponding to the starting and ending points and the multiple sets of U-turn line control points; calculating the curvature of each point in the Bézier curves and the distance between each point and a static obstacle; and determining the corresponding Bézier curve as the U-turn line if the distance and curvature both meet the corresponding preset conditions.

[0031] The technical solution of this application utilizes the Bezier curve generation method to generate the U-turn line through multiple U-turn line control points when generating the U-turn line. At the same time, it constrains the curvature of the U-turn line and the distance to static obstacles to ensure the smoothness of the U-turn line. This improves the safety and driving experience of the vehicle when making a U-turn according to the U-turn line.

[0032] The technical solutions of this application and how they solve the aforementioned technical problems will be described in detail below with specific embodiments. The specific embodiments described below can be combined with each other to form new embodiments. The same or similar ideas or processes described in one embodiment may not be repeated in other embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0033] Figure 1 This is a schematic diagram of a specific implementation of the method for constructing a turning line in this application.

[0034] exist Figure 1 In the embodiment shown, the U-turn line construction method of this application includes process S101, which determines the starting point and ending point of the vehicle making a U-turn.

[0035] In this implementation, when generating the U-turn line for a vehicle making a U-turn, the starting and ending points of the autonomous vehicle's U-turn are determined in a pre-established high-precision map. These starting and ending points are also the start and end points of the U-turn line.

[0036] Optionally, the starting and ending points of the vehicle's U-turn can be determined, including: taking the midpoint of the intersection stop line of the lane where the vehicle was before making the U-turn as the starting point, and taking the midpoint of the intersection stop line of the lane into which the vehicle is about to make the U-turn as the ending point.

[0037] In this optional embodiment, when determining the starting and ending points of the U-turn line, the midpoint of the lane where the vehicle was before making the U-turn on the intersection stop line is taken as the starting point of the U-turn on the map; and the midpoint of the intersection stop line of the lane the vehicle is about to enter after making the U-turn is taken as the ending point of the U-turn line.

[0038] Specifically, Figure 2 This is a schematic diagram of the starting and ending points of the U-turn line in this application.

[0039] like Figure 2As shown, point a1 represents the starting point of the U-turn line, which is the end point of the autonomous vehicle's straight-line driving in the high-precision map; point b1 represents the ending point of the U-turn line, which is the starting point of the autonomous vehicle's restarting straight-line driving in the high-precision map; in one embodiment, the midpoint of the intersection stop line of the U-turn lane where the vehicle is located can be selected as the starting point a1 of the U-turn line; in another embodiment, the midpoint of the intersection stop line of the lane the vehicle is to enter after making a U-turn can be selected as the ending point b1 of the U-turn line.

[0040] exist Figure 1 In the embodiment shown, the U-turn line construction method of this application includes process S102, which determines multiple sets of U-turn line control points based on the starting point and the ending point.

[0041] In this implementation, when constructing a U-turn line using the generation principle of Bézier curves, it is necessary to determine multiple corresponding U-turn line control points to generate the U-turn line. These multiple control points, along with the start and end points, form a convex polygon, and the U-turn line is generated using the generation principle of Bézier curves. Therefore, in a high-precision map, multiple U-turn line control points are determined based on the defined start and end points for the generation of the U-turn line.

[0042] Optionally, multiple sets of U-turn control points are determined based on the starting and ending points, including: selecting multiple points as first U-turn control points within a first distance range from the starting point in a first direction and within a second distance range from the starting point in a second direction, wherein the first direction is the longitudinal extension direction of the lane where the vehicle is located, and the second direction is perpendicular to the first direction; selecting multiple points as second U-turn control points on the side of the line connecting the starting point and the first U-turn control points away from the lane into which the vehicle is to make a U-turn, within a third distance range from the starting point in the first direction and within a fourth distance range from the first U-turn control points in the second direction. Control points: Within a first distance from the end point in the first direction and within a second distance from the end point in the second direction, multiple points are selected as third U-turn line control points; On the side of the line connecting the end point and the third U-turn line control points away from the lane where the vehicle is about to make a U-turn, within a third distance from the end point in the first direction and within a fifth distance from the end point in the second direction, multiple points are selected as fourth U-turn line control points. Multiple combinations of single first, second, third, and fourth U-turn line control points are obtained to obtain multiple sets of U-turn line control points.

[0043] In this optional embodiment, when determining the U-turn control point, a point is selected as the first U-turn control point within the U-turn intersection, within a first distance range from the starting point in the first direction and within a second distance range from the starting point in the second direction. To ensure that the polygon formed by connecting multiple U-turn control points is convex, when determining the second U-turn control point, the second U-turn control point is selected on the side of the line connecting the first U-turn control point and the starting point that is furthest from the lane the vehicle is waiting to enter for the U-turn. Simultaneously, the distance between the second U-turn control point and the starting point in the first direction is within a third distance range, and the distance in the second direction is within a fourth distance range. The third U-turn control point is selected based on the location of the termination point. Within the U-turn intersection, a point is selected as the third U-turn control point within a first distance range from the termination point in the first direction and within a second distance range from the termination point in the second direction. Similarly, to ensure that the polygon formed by connecting multiple U-turn control points is convex, when selecting the fourth U-turn control point, the fourth U-turn control point is selected on the side of the line connecting the third U-turn control point and the termination point that is far away from the lane where the vehicle is about to make a U-turn. At the same time, it is ensured that the distance between the fourth U-turn control point and the termination point in the first direction is within the third longitudinal distance range, and in the second direction, the distance between the fourth U-turn control point and the termination point is within the fifth lateral distance range. One or more points are selected as the fourth U-turn control point.

[0044] Through the above process of selecting control points, multiple sets of U-turn line control points can be obtained. The polygon formed by connecting the control points, starting point, and ending point of each set of U-turn line control points in sequence has convexity.

[0045] Optionally, when selecting multiple sets of U-turn line control points, to ensure a better U-turn line, the spacing between adjacent control points is greater than the spacing between the selections of the third control point when selecting the first U-turn line control point multiple times. By using different combinations of the first to fourth U-turn line control points, a large number of sets of U-turn line control points are obtained.

[0046] Optionally, when selecting U-turn control points, the selection range will be determined based on the distance between the starting and ending points. This ensures good adaptability to different intersections.

[0047] Specifically, the distance between the starting point and the ending point is denoted by D. The first distance range is denoted as (D, 6D), and the second distance range is 0.25D on both sides of the starting point, denoted as (-0.25D, 0.25D). The position of the second U-turn control point is determined based on the position of the first U-turn control point to ensure that the polygon formed by the lines connecting the multiple U-turn control points, the starting point, and the ending point is convex. The depth of the first U-turn control point relative to the starting point is denoted by P, where depth P is the first distance range, which is (D, 6D). The third distance range is denoted as (1 / 4P, 2 / 3P). The distance of the second U-turn control point in the second direction, with the starting point as the reference, is the fourth distance range located outside the starting point, denoted as (0, 0.25D). When selecting the third U-turn control point, in the first direction, the distance from the ending point is the first distance range, denoted as (D, 6D), and in the second direction, it is 0.25D on both sides of the starting point, denoted as (-0.25D, 0.25D). The fourth U-turn control point is located in the first direction, at a distance of (1 / 4P, 2 / 3P) from the fourth end point. In the second direction, it is located outside the line connecting the end point and the third U-turn control point, at a distance of (0, 1.25D) from the fifth end point.

[0048] By determining the location of the corresponding U-turn line control points according to different intersection widths, the reliability of the selection of U-turn line control points is ensured, and the rationality of the final determined U-turn line is guaranteed.

[0049] Specifically, Figure 3 An example of selecting a U-turn line control point is shown.

[0050] exist Figure 3 In the example shown, point a1 represents the starting point of the autonomous vehicle's U-turn, point b1 represents the ending point of the autonomous vehicle's U-turn, point a2 represents the first U-turn control point, and point a3 represents the second U-turn control point; the selection range of both is determined by the starting point a1. Point b2 represents the third U-turn control point, and point b3 represents the fourth U-turn control point; the selection range of both is determined by the ending point b1. The polygon formed by the lines connecting points a1, a3, a2, b2, b3, and b1 must be convex; that is, the polygon formed by connecting points a1, a3, a2, b2, b3, and b1 is a convex polygon.

[0051] It should be noted that, Figure 3This is just one example of selecting a U-turn line. In the specific process of selecting a U-turn line, one or more control points can be selected at each location. Then, the Bézier curve is determined based on six or more points, including the start point and the end point. However, it is necessary to ensure that the polygon formed by connecting multiple control points, the start point, and the end point in sequence has convexity.

[0052] exist Figure 1 In the embodiment shown, the U-turn line construction method of this application includes process S103, which generates multiple Bézier curves by using the starting point, the ending point, and multiple sets of U-turn line control points.

[0053] In this embodiment, after determining multiple sets of U-turn line control points, corresponding Bézier curves are generated using the starting point, ending point, and U-turn line control points. The Bézier curves are smooth, thereby ensuring that the U-turn lines selected from the Bézier curves are smooth.

[0054] Specifically, Figure 4 An example of a Bézier curve is shown.

[0055] exist Figure 4 In the example shown, the corresponding Bézier curve can be determined based on multiple U-turn line control points. Then, the appropriate Bézier curve is used as the U-turn line, and the autonomous vehicle makes a U-turn according to the determined U-turn line, thereby ensuring the safety and feasibility of the autonomous vehicle when making a U-turn and ensuring the driving experience.

[0056] exist Figure 1 In the embodiment shown, the U-turn line construction method of this application includes process S104, which calculates the curvature of each point in the Bézier curve and the distance between each point and the static obstacle.

[0057] In this implementation, multiple Bézier curves are generated based on the starting point, ending point, and multiple sets of U-turn control points. The curvature of each point on each Bézier curve and the distance from each point to a static obstacle are then calculated. Through curvature and distance filtering, the safest curve, conforming to vehicle driving patterns, is selected as the final U-turn line. The distance to the static obstacle is calculated; this distance represents the distance between the autonomous vehicle and the obstacle during the U-turn. A greater distance indicates a safer driving experience and reduces the risk of collision. The curvature is calculated and compared with the autonomous vehicle's own turning curvature to determine the feasibility of using the Bézier curve as the U-turn line. Static obstacles include the edges of the road the autonomous vehicle is traveling on.

[0058] When calculating the distance between each point on a Bézier curve and a static obstacle, the distance can be calculated based on the specific locations of the Bézier curve and the static obstacle in the high-precision map.

[0059] exist Figure 1 In the embodiment shown, the method for constructing a turning line in this application includes process S105, in which the corresponding Bézier curve is determined as the turning line under the condition that both the distance and curvature meet the corresponding preset conditions.

[0060] In this embodiment, after calculating the curvature of each point in each Bézier curve and the distance to the static obstacle, the Bézier curves are screened based on the curvature and distance, and finally the turning line is determined from a large number of Bézier curves.

[0061] Optionally, if both the distance and curvature meet the corresponding preset conditions, the Bézier curve is determined as a turning line, including: if the distance between each point on the Bézier curve and the static obstacle is greater than or equal to a first preset distance threshold, the Bézier curve is determined as the distance-optimal curve; if the distance is less than the first preset distance threshold but greater than or equal to a second preset distance threshold, the Bézier curve is determined as the distance-second-optimal curve; if the distance is less than the second preset distance threshold, the Bézier curve is eliminated.

[0062] In this optional embodiment, when filtering distances, the Bézier curves are graded according to the calculated distance values. A Bézier curve is determined to be the optimal distance curve if the distance between each point on the curve and the static obstacle is greater than or equal to a first preset distance threshold. The optimal distance curve indicates that the autonomous vehicle is far from the static obstacle, such as the edge of the lane, and making a U-turn along this curve provides good safety.

[0063] Specifically, the first preset distance threshold can be selected as 1.7 meters. When the distance between each point on the Bézier curve and the static obstacle is greater than or equal to 1.7 meters, the corresponding Bézier curve is determined as the distance-optimal curve. When determining the final turning line, the selection will be prioritized from the distance-optimal curve.

[0064] In this optional embodiment, if there are distances less than a first preset distance threshold but all are greater than or equal to a second preset distance threshold, the Bézier curve is determined as the second-best distance curve. If none of the obtained Bézier curves satisfy the optimal distance curve, the second-best distance curve can also be selected as the turning point.

[0065] Specifically, the second preset distance threshold can be selected as 1.5 meters. When the distance from each point on the Bézier curve to the static obstacle is less than the first preset distance threshold of 1.7 meters, but greater than or equal to the second preset distance threshold of 1.5 meters, the corresponding Bézier curve is determined as the second-optimal distance curve. If none of the Bézier curves meet the optimal distance curve requirement, a suitable curve can be selected from the second-optimal distance curves as the turning line.

[0066] In this optional embodiment, the Bezier curve is removed if the distance is less than a second preset distance threshold.

[0067] Specifically, if the distance between each point on the obtained Bézier curve and the static obstacle is less than the second preset distance threshold, it indicates that the Bézier curve is too close to the static obstacle. If a curve is selected from this Bézier curve as a U-turn line, the autonomous vehicle is prone to colliding with the obstacle when making a U-turn based on this line, leading to a driving hazard. Therefore, when there is a point on the Bézier curve whose distance is less than the second preset distance threshold, this Bézier curve is discarded and will not be considered when determining the U-turn line.

[0068] By calculating and judging the distances between various points on multiple Bézier curves and static obstacles, the safety of the U-turn line is ensured when determining it. It should be noted that the selection of the preset distance threshold can be reasonably chosen based on different vehicle requirements and the safety requirements of the U-turn line construction. The above selection of distance thresholds is merely a preferred example and does not limit the scope of protection of this application.

[0069] Optionally, if both the distance and curvature meet the corresponding preset conditions, the Bézier curve is determined as a turning line, including: if the curvature of each point in the Bézier curve is less than or equal to a first preset curvature threshold, the Bézier curve is determined as the optimal curvature curve; if the curvature is greater than the first preset curvature threshold but less than or equal to a second preset curvature threshold, the Bézier curve is determined as the second optimal curvature curve; if the curvature is greater than the second preset curvature threshold, the Bézier curve is removed.

[0070] In this optional embodiment, during curvature screening, the Bézier curves are graded according to the calculated curvature values. A Bézier curve is determined as the optimal curvature curve if the curvature at each point is greater than or equal to a first preset curvature threshold. The optimal curvature curve indicates that the autonomous vehicle can smoothly make a U-turn according to this curve. When an autonomous vehicle makes a U-turn, the turning radius is related to the vehicle's mechanical performance. Therefore, calculating and screening the curvature of the Bézier curves ensures the feasibility of the determined U-turn line, enabling the autonomous vehicle to turn according to the U-turn line and avoiding problems caused by the vehicle's wheelbase design preventing it from making a U-turn.

[0071] Specifically, the preset curvature threshold value varies depending on the vehicle model. For example, the turning radius of a large truck is significantly larger than that of a small car. Therefore, the preset curvature threshold value is determined based on the maximum curvature value corresponding to different vehicle models. For instance, for small vehicles such as cars, the maximum curvature value is 0.2, corresponding to a turning radius of 5 meters. When determining the first preset curvature value, a certain proportion of the maximum curvature value is taken as the first preset curvature. The first preset curvature threshold can be determined as 0.8 times the maximum curvature value, which is 0.16. That is, for small vehicles such as cars, when the curvature value at each point of the Bézier curve is less than 0.16, the corresponding Bézier curve is determined as the curve with optimal curvature. When determining the final U-turn line, the curve with optimal curvature will be selected first.

[0072] In this optional embodiment, if the curvature is greater than a first preset curvature threshold but less than or equal to a second preset curvature threshold, the Bézier curve is determined as a suboptimal curvature curve. If the generated Bézier curve cannot meet the requirements of an optimal curvature curve, a suboptimal curvature curve determination is performed. It is determined whether the curvature value at each point in the Bézier curve is less than or equal to the second preset curvature threshold. If the condition is met, the Bézier curve is determined as a suboptimal curvature curve.

[0073] Specifically, the second preset curvature threshold is also reasonably selected based on the vehicle model. For small vehicles such as sedans, the maximum curvature value is 0.2, and the second preset curvature threshold can be determined as 0.9 times the maximum curvature value, which is 0.18. That is, for small vehicles such as sedans, when the curvature value of each point of the Bézier curve is less than 0.18, the corresponding Bézier curve is determined as a second-optimal curvature curve. When determining the final turning line, priority will be given to selecting from the optimal curvature curve. If there is no Bézier curve that meets the optimal curvature curve, then a second-optimal curvature curve will be selected.

[0074] In this optional embodiment, for Bézier curves that do not meet the second preset curvature threshold, the corresponding curves are directly eliminated. Such curves have a large curvature and no longer meet the mechanical performance of the vehicle, making it impossible for the vehicle to turn around according to the indication of the Bézier curve.

[0075] Optionally, if both the distance and curvature meet the corresponding preset conditions, the Bézier curve is determined as a turning line, including: determining the Bézier curve as a turning line when the Bézier curve satisfies the optimal distance curve and the optimal curvature curve; or determining the Bézier curve as a turning line when the Bézier curve satisfies the optimal distance curve and the optimal curvature curve; or determining the Bézier curve as a turning line when the Bézier curve satisfies the second-optimal distance curve and the optimal curvature curve; or determining the Bézier curve as a turning line when the Bézier curve satisfies the second-optimal distance curve and the optimal curvature curve.

[0076] In this optional embodiment, during the selection of a U-turn line from multiple Bézier curves, distance and curvature factors are fully considered, and the optimal Bézier curve is ultimately selected as the final U-turn line. When selecting the U-turn line, it can be determined from any of the above-mentioned Bézier curves that satisfy the conditions mentioned above. Preferably, to ensure that a better U-turn line is ultimately selected, it is first selected from Bézier curves that satisfy both the optimal distance curve and the optimal curvature curve. The selected Bézier curve, as the U-turn line, can well meet the safety and feasibility requirements of autonomous vehicles making U-turns. If the obtained multiple Bézier curves do not satisfy both the optimal distance curve and the optimal curvature curve, then a selection is made from the second-best distance curve and the optimal distance curve, lowering the selection level to find a suitable Bézier curve as the U-turn line.

[0077] Specifically, Table 1 below lists the feasible U-turn options, as follows:

[0078] Table 1: Selection Order of U-turn Line

[0079] Optimal curvature curve 1 3 Second-best curvature curve 2 4

[0080] As shown in the table above, the numbers indicate the selection order when choosing the turning line. First, curves that satisfy both the optimal distance and optimal curvature are selected. Finally, curves satisfying the second-best distance and second-best curvature are selected. If none of the resulting Bézier curves meet the above conditions, it indicates an error in the curve generation process. In this case, the Bézier curves are regenerated to obtain a feasible turning line.

[0081] Optionally, if the distance and curvature both meet the corresponding preset conditions, the Bézier curve is determined as a U-turn line. This also includes: if the distance and curvature of the Bézier curve both meet the corresponding preset conditions, calculating the entry angle of the Bézier curve between the starting point and the straight extension line of the vehicle and the exit angle of the Bézier curve between the ending point and the straight extension line of the vehicle; if the entry angle is less than a first angle threshold and the exit angle is less than a second angle threshold, the Bézier curve is determined as a U-turn line.

[0082] In this optional embodiment, in order to make the U-turn line selected from multiple Bézier curves smoother and improve the U-turn experience for drivers and passengers, this application considers the entry angle and exit angle of the U-turn line, taking into account distance and curvature factors. When the entry angle is less than a first angle threshold and the exit angle is less than a second angle threshold, the Bézier curve that meets the distance and curvature conditions is determined as the U-turn line.

[0083] Specifically, Figure 5 An example of the entry and exit angles of a U-turn line is shown.

[0084] like Figure 5 As shown, the entry angle is the angle between the starting point of the Bézier curve and the straight extension of the vehicle, as shown by angle x in the figure; the exit angle is the angle between the ending point of the Bézier curve and the straight extension of the vehicle, as shown by angle y in the figure. By constraining the entry and exit angles, the abrupt change in vehicle direction during U-turns by autonomous vehicles is avoided, thus improving the driving experience.

[0085] Specifically, the first threshold for the entry angle can be set to 5 degrees, and the second threshold for the exit angle can be set to 10 degrees. It should be noted that the angle thresholds can be reasonably set according to different driving experience requirements. The above values ​​are merely examples of optimal choices and are not intended to limit the selection of angle thresholds.

[0086] The U-turn line construction method of this application generates the U-turn line by using a Bézier curve generation method and generating the U-turn line through multiple U-turn line control points. Simultaneously, it constrains the curvature of the U-turn line and the distance to static obstacles to ensure the smoothness of the U-turn line, improving safety and driving experience when the vehicle makes a U-turn along this line. Furthermore, the restrictions on the entry and exit angles of the U-turn line further enhance the driving experience during U-turns.

[0087] Figure 6 An embodiment of the U-turn line construction system of this application is shown.

[0088] exist Figure 6In the illustrated embodiment, the U-turn line construction system of this application includes a start-end point determination module 601, which determines the start and end points of a vehicle's U-turn; a U-turn line control point determination module 602, which determines multiple sets of U-turn line control points based on the start and end points; a Bézier curve determination module 603, which generates multiple Bézier curves corresponding to the start and end points and the multiple sets of U-turn line control points; a calculation module 604, which calculates the curvature of each point in the Bézier curve and the distance between each point and a static obstacle; and a U-turn line determination module 605, which determines the Bézier curve as a U-turn line if the distance and curvature both meet the corresponding preset conditions.

[0089] Optionally, in the U-turn line control point determination module 602, multiple points are selected as first U-turn line control points within a first distance range from the starting point in a first direction and within a second distance range from the starting point in a second direction. The first direction is the longitudinal extension direction of the lane where the vehicle is located, and the second direction is perpendicular to the first direction. On the side of the line connecting the starting point and the first U-turn line control points away from the lane the vehicle is about to enter, multiple points are selected as second U-turn line control points within a third distance range from the starting point in the first direction and within a fourth distance range from the first U-turn line control point in the second direction. Multiple points are selected as third U-turn line control points within a first distance range from the end point in the first direction and within a second distance range from the end point in the second direction. On the side of the line connecting the end point and the third U-turn line control points away from the lane where the vehicle is about to make a U-turn, multiple points are selected as fourth U-turn line control points within a third distance range from the end point in the first direction and within a fifth distance range from the end point in the second direction. Multiple sets of U-turn line control points are obtained by combining individual first, second, third, and fourth U-turn line control points.

[0090] Optionally, if both the distance and curvature meet the corresponding preset conditions, the Bézier curve is determined as a turning line, including: if the distance between each point on the Bézier curve and the static obstacle is greater than or equal to a first preset distance threshold, the Bézier curve is determined as the distance-optimal curve; if the distance is less than the first preset distance threshold but greater than or equal to a second preset distance threshold, the Bézier curve is determined as the distance-second-optimal curve; if the distance is less than the second preset distance threshold, the Bézier curve is eliminated.

[0091] Optionally, in the U-turn line determination module 605, if the curvature of each point in the Bézier curve is less than or equal to the first preset curvature threshold, the Bézier curve is determined as the curve with optimal curvature; if the curvature is greater than the first preset curvature threshold but less than or equal to the second preset curvature threshold, the Bézier curve is determined as the curve with suboptimal curvature; if the curvature is greater than the second preset curvature threshold, the Bézier curve is discarded.

[0092] Optionally, in the U-turn line determination module 605, the Bézier curve is determined as a U-turn line if it satisfies the conditions of the optimal distance curve and the optimal curvature curve; or if it satisfies the conditions of the optimal distance curve and the optimal curvature curve; or if it satisfies the conditions of the second-optimal distance curve and the optimal curvature curve; or if it satisfies the conditions of the second-optimal distance curve and the optimal curvature curve.

[0093] Optionally, in the U-turn line determination module 605, under the condition that the distance and curvature of the Bézier curve both meet the corresponding preset conditions, the entry angle of the Bézier curve between the starting point and the straight extension line of the vehicle and the exit angle of the Bézier curve between the ending point and the straight extension line of the vehicle are calculated; under the condition that the entry angle is less than the first angle threshold and the second angle is less than the second angle threshold, the Bézier curve is determined as the U-turn line.

[0094] The U-turn line construction system of this application generates U-turn lines using a Bézier curve generation method. It generates the U-turn line through multiple control points while simultaneously constraining the curvature and distance from static obstacles to ensure smoothness. This improves safety and driving experience when the vehicle makes a U-turn along the designated line. Furthermore, restrictions on the entry and exit angles of the U-turn line further enhance the driving experience during U-turns.

[0095] Figure 7 An embodiment of the turning method of this application is shown.

[0096] exist Figure 7In the illustrated embodiment, the U-turn method of this application includes process S701, determining the starting point and ending point of the vehicle U-turn; process S702, determining multiple sets of U-turn line control points based on the starting point and ending point; process S703, generating multiple Bézier curves corresponding to the starting point, ending point, and multiple sets of U-turn line control points; process S704, calculating the curvature of each point in the Bézier curve and the distance between each point and a static obstacle; process S705, determining the Bézier curve as the U-turn line if the distance and curvature both meet the corresponding preset conditions; and process S706, the autonomous vehicle performs autonomous U-turn control according to the U-turn line.

[0097] The part regarding the determination of the U-turn line in the autonomous driving U-turn method of this application is the same as the U-turn line construction method in the above embodiments, and will not be repeated here. After obtaining the U-turn line, the vehicle makes a U-turn according to the indication of the U-turn line, ensuring the safety and feasibility of the U-turn and improving the driving experience during the U-turn.

[0098] In one specific embodiment of this application, a computer-readable storage medium stores computer instructions, wherein the computer instructions are operated to perform the method for constructing a turning line or a turning method described in any embodiment. The storage medium may be located directly in hardware, in a software module executed by a processor, or in a combination of both.

[0099] Software modules may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in this art. An exemplary storage medium is coupled to the processor, enabling the processor to read information from and write information to the storage medium.

[0100] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof. A general-purpose processor can be a microprocessor, but alternatively, it can be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors incorporating a DSP core, or any other such configuration. Alternatively, the storage medium can be integrated with the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in the user terminal. Alternatively, the processor and storage medium can reside as discrete components in the user terminal.

[0101] In one specific embodiment of this application, a computer device includes a processor and a memory, the memory storing computer instructions, wherein the processor operates the computer instructions to execute the turning line construction method or turning method described in any embodiment.

[0102] In the embodiments provided in this application, it should be understood that the disclosed apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0103] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0104] The above are merely embodiments of this application and do not limit the scope of this patent application. Any equivalent structural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A method for constructing a turning line, characterized in that, include: Determine the starting and ending points for the vehicle to make a U-turn; Multiple sets of U-turn line control points are determined based on the starting point and the ending point; Multiple Bézier curves are generated using the starting point, the ending point, and multiple sets of turning line control points. Calculate the curvature of each point in the Bézier curve and the distance between each point and the static obstacle; Under the condition that both the distance and the curvature meet the corresponding preset conditions, the corresponding Bézier curve is determined as the turning line; The determination of multiple sets of U-turn control points based on the starting point and the ending point includes: Within a first distance from the starting point in a first direction and within a second distance from the starting point in a second direction, multiple points are selected as first U-turn line control points, wherein the first direction is the longitudinal extension direction of the lane where the vehicle is located, and the second direction is perpendicular to the first direction; On the side of the line connecting the starting point and the first U-turn control point that is far from the lane into which the vehicle is about to make a U-turn, within a third distance from the starting point in the first direction and within a fourth distance from the first U-turn control point in the second direction, multiple points are selected as the second U-turn control points. Within the first distance from the termination point in the first direction and within the second distance from the termination point in the second direction, multiple points are selected as third U-turn line control points respectively; On the side of the line connecting the termination point and the third U-turn line control point that is far from the lane where the vehicle is about to make a U-turn, within the third distance from the termination point in the first direction and within the fifth distance from the termination point in the second direction, multiple points are selected as the fourth U-turn line control points. Multiple sets of U-turn line control points are obtained by repeatedly selecting and combining a single first U-turn line control point, second U-turn line control point, third U-turn line control point, and fourth U-turn line control point.

2. The method for constructing a turning line according to claim 1, characterized in that, When both the distance and the curvature meet the corresponding preset conditions, the Bézier curve is determined as a turning line, including: Under the condition that the distance between each point in the Bézier curve and the static obstacle is greater than or equal to a first preset distance threshold, the Bézier curve is determined as the distance-optimal curve; Under the condition that the distance is less than the first preset distance threshold but is greater than or equal to the second preset distance threshold, the Bézier curve is determined as the distance suboptimal curve; If the distance is less than a second preset distance threshold, the Bezier curve is removed.

3. The method for constructing a turning line according to claim 2, characterized in that, The step of determining the Bézier curve as a turning line when both the distance and the curvature meet the corresponding preset conditions further includes: Under the condition that the curvature at each point in the Bézier curve is less than or equal to a first preset curvature threshold, the Bézier curve is determined as the curve with optimal curvature. Under the condition that the curvature is greater than the first preset curvature threshold but less than or equal to the second preset curvature threshold, the Bézier curve is determined as a curvature suboptimal curve. If the curvature is greater than a second preset curvature threshold, the Bézier curve is removed.

4. The method for constructing a turning line according to claim 3, characterized in that, The step of determining the Bézier curve as a turning line when both the distance and the curvature meet the corresponding preset conditions further includes: Under the condition that the Bézier curve satisfies the optimal distance curve and the optimal curvature curve, the Bézier curve is determined as the turning line; or Under the condition that the Bézier curve satisfies the optimal distance curve and the suboptimal curvature curve, the Bézier curve is determined as the turning line; or Under the condition that the Bézier curve satisfies the suboptimal distance curve and the optimal curvature curve, the Bézier curve is determined as the turning line; or Under the condition that the Bézier curve satisfies the second-best distance curve and the best curvature curve, the Bézier curve is determined as the turning line.

5. The method for constructing a turning line according to claim 1, characterized in that, The step of determining the Bézier curve as a turning line when both the distance and the curvature meet the corresponding preset conditions further includes: Under the condition that the distance and curvature of the Bézier curve both meet the corresponding preset conditions, calculate the entry angle of the Bézier curve between the starting point and the straight extension line of the vehicle and the exit angle of the Bézier curve between the ending point and the straight extension line of the vehicle. Under the condition that the entry angle is less than a first angle threshold and the exit angle is less than a second angle threshold, the Bézier curve is determined as a U-turn line.

6. The method for constructing a turning line according to claim 1, characterized in that, The determination of the starting and ending points for the vehicle to make a U-turn includes: taking the midpoint of the intersection stop line of the lane where the vehicle was before making the U-turn as the starting point, and taking the midpoint of the intersection stop line of the lane into which the vehicle is about to make the U-turn as the ending point.

7. A U-turn line construction system, characterized in that, include: The start and end point determination module determines the starting and ending points for a vehicle to make a U-turn. The U-turn line control point determination module determines multiple sets of U-turn line control points based on the starting point and the ending point; The Bézier curve determination module generates multiple Bézier curves using the starting point, the ending point, and multiple sets of turning line control points. The calculation module calculates the curvature of each point in the Bézier curve and the distance between each point and the static obstacle; The U-turn line determination module determines the Bézier curve as a U-turn line if both the distance and the curvature meet the corresponding preset conditions. The determination of multiple sets of U-turn control points based on the starting point and the ending point includes: Within a first distance from the starting point in a first direction and within a second distance from the starting point in a second direction, multiple points are selected as first U-turn line control points, wherein the first direction is the longitudinal extension direction of the lane where the vehicle is located, and the second direction is perpendicular to the first direction; On the side of the line connecting the starting point and the first U-turn control point that is far from the lane into which the vehicle is about to make a U-turn, within a third distance from the starting point in the first direction and within a fourth distance from the first U-turn control point in the second direction, multiple points are selected as the second U-turn control points. Within the first distance from the termination point in the first direction and within the second distance from the termination point in the second direction, multiple points are selected as third U-turn line control points respectively; On the side of the line connecting the termination point and the third U-turn line control point that is far from the lane where the vehicle is about to make a U-turn, within the third distance from the termination point in the first direction and within the fifth distance from the termination point in the second direction, multiple points are selected as the fourth U-turn line control points. Multiple sets of U-turn line control points are obtained by repeatedly selecting and combining a single first U-turn line control point, second U-turn line control point, third U-turn line control point, and fourth U-turn line control point.

8. A method for making a U-turn, characterized in that, include: Determine the starting and ending points for the vehicle to make a U-turn; Multiple sets of U-turn line control points are determined based on the starting point and the ending point; Multiple Bézier curves are generated using the starting point, the ending point, and multiple sets of turning line control points. Calculate the curvature of each point in the Bézier curve and the distance between each point and the static obstacle; If both the distance and the curvature meet the corresponding preset conditions, then the Bézier curve is determined as a turning line; The vehicle performs autonomous driving U-turn control according to the U-turn line; The determination of multiple sets of U-turn control points based on the starting point and the ending point includes: Within a first distance from the starting point in a first direction and within a second distance from the starting point in a second direction, multiple points are selected as first U-turn line control points, wherein the first direction is the longitudinal extension direction of the lane where the vehicle is located, and the second direction is perpendicular to the first direction; On the side of the line connecting the starting point and the first U-turn control point that is far from the lane into which the vehicle is about to make a U-turn, within a third distance from the starting point in the first direction and within a fourth distance from the first U-turn control point in the second direction, multiple points are selected as the second U-turn control points. Within the first distance from the termination point in the first direction and within the second distance from the termination point in the second direction, multiple points are selected as third U-turn line control points respectively; On the side of the line connecting the termination point and the third U-turn line control point that is far from the lane where the vehicle is about to make a U-turn, within the third distance from the termination point in the first direction and within the fifth distance from the termination point in the second direction, multiple points are selected as the fourth U-turn line control points. Multiple sets of U-turn line control points are obtained by repeatedly selecting and combining a single first U-turn line control point, second U-turn line control point, third U-turn line control point, and fourth U-turn line control point.

9. A computer-readable storage medium storing computer instructions, characterized in that, When the computer instructions are executed, the computer performs the method of any one of claims 1-6 or 8.

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