Intersection trajectory planning method, system, equipment and medium

Abstract

An intersection trajectory planning method, system, device and medium relate to the technical field of vehicle trajectory planning, and the method comprises the following steps: when a stop line is detected, if two lane lines are lost and cannot follow a vehicle, or only one lane line exists, obtaining an estimated steering wheel angle under a current reference trajectory; if the two lane lines are lost and the vehicle can be followed, planning a vehicle following track according to a vehicle following target; when the absolute value of the difference between the estimated steering wheel angle and the previous frame of steering wheel angle is larger than or equal to the preset angle difference, track keeping is conducted based on the previous frame of steering wheel angle, and a keeping track is obtained; and when the absolute value is smaller than the preset angle difference, obtaining a predicted trajectory according to the historical center point of the vehicle. According to the invention, the method fully considers the loss of the lane lines at the intersection and different scenes with or without the vehicle-following target, and further plans the optimal track for smooth transition to the opposite intersection according to the different scenes, thereby improving the safety and experience.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle trajectory planning, and in particular to a method, system, device and medium for intersection trajectory planning. Background Art

[0002] At present, the development trend of autonomous driving is increasingly inclined to "focus on perception, not maps", making full use of perception information to reduce dependence on high-definition topological structures, and continuously optimizing the engineering capabilities of core regulatory control algorithms to achieve autonomous driving integrated adaptive cruise function, meet user needs for scenarios and functions, and reduce costs. Therefore, in scenarios where there is no high-precision map at the intersection, based on sensor information, self-vehicle trajectory planning and smooth passage through the intersection is of great strategic significance for the independent innovation of the automotive industry to achieve cost reduction and efficiency improvement, as well as reduce energy consumption and environmental pollution.

[0003] In related technologies, a trajectory can be planned based on lane lines or target vehicles in front of the vehicle. However, when there is no target vehicle or lane line in front of the vehicle, it is impossible to accurately plan a trajectory to smoothly reach the opposite intersection. The trajectory can only be predicted based on the historical center point fitting. The lateral deviation will continue to accumulate and even be deviated by the roadside or abnormal lane line, resulting in a large deviation in the steering wheel angle calculated for lateral control and a poor experience. Summary of the invention

[0004] The present application provides a method, system, device and medium for planning a trajectory at an intersection, which can solve the technical problem in the prior art that a trajectory for smoothly reaching an opposite intersection cannot be accurately planned.

[0005] In a first aspect, the present application provides a method for intersection trajectory planning, the method comprising:

[0006] When the stop line is detected, if both lane lines are lost and the vehicle cannot be followed, or if only one lane line exists, the estimated steering wheel angle under the current reference trajectory is obtained; if both lane lines are lost and the vehicle can be followed, the following trajectory is planned according to the following target;

[0007] When the absolute value of the difference between the estimated steering wheel angle and the steering wheel angle of the previous frame is greater than or equal to the preset angle difference, the track is maintained based on the steering wheel angle of the previous frame to obtain a maintained track;

[0008] When the absolute value is less than the preset angle difference, the predicted trajectory is obtained according to the historical center point of the vehicle.

[0009] In combination with the first aspect, in one implementation, when both lane lines are lost, the method further includes:

[0010] Determine whether it is possible to follow the vehicle, and when the speed of the vehicle is less than the first speed threshold and the following target is valid, determine that it is possible to follow the vehicle, otherwise, determine that it is not possible to follow the vehicle; wherein,

[0011] When there is a following target, and the longitudinal distance from the center of the rear axle of the following target to the center of the front of the vehicle is less than the first preset distance, the target heading angle is not greater than the preset heading angle, and the longitudinal distance change value within a preset period is less than the preset change value, the following target is judged to be valid.

[0012] In combination with the first aspect, in one implementation, after only one lane line exists or both lane lines are lost, the method further includes:

[0013] If a new lane line appears after only one lane line exists, and the longitudinal distance from the starting point of the new lane line to the center of the vehicle head is less than the second preset distance, or if a new lane line appears after two lane lines are lost, and the length of the new lane line is greater than the preset length, trajectory planning is performed according to the new lane line to obtain a center reference line;

[0014] The following track, the maintained track, or the predicted track is smoothly transitioned to the center reference line.

[0015] In combination with the first aspect, in one implementation, planning a vehicle following trajectory according to a vehicle following target specifically includes:

[0016] According to the lateral and longitudinal positions of the following target relative to the ego vehicle, the following trajectory of the ego vehicle is obtained, and the following trajectory coefficient is output.

[0017] In combination with the first aspect, in one implementation, obtaining an estimated steering wheel angle under a current reference trajectory specifically includes:

[0018] According to the current reference trajectory, the lateral and longitudinal displacements of the vehicle are estimated after a first preset time period.

[0019] Calculate the estimated curvature according to the lateral and longitudinal displacements of the vehicle;

[0020] The estimated steering wheel angle is obtained according to the estimated curvature, the wheelbase and the wheelbase transmission ratio of the vehicle.

[0021] In combination with the first aspect, in one implementation, the track keeping is performed based on the steering wheel angle of the previous frame, specifically including:

[0022] Determining whether the vehicle speed is greater than a second vehicle speed threshold;

[0023] If yes, then obtain the planned curvature according to the vehicle speed and yaw rate;

[0024] Otherwise, the planned curvature is obtained according to the steering wheel angle, angular transmission ratio and wheelbase of the previous frame;

[0025] According to the above planned curvature, the current steering curvature is obtained.

[0026] In combination with the first aspect, in one implementation, before the stop line is detected, the method further includes: setting the intersection sign position to 0;

[0027] When the above intersection sign is at position 0, if a stop line is detected, the intersection sign is set to position 1;

[0028] When the above-mentioned intersection sign is at position 1, if a lane line is lost, the intersection sign is at position 2; if the duration of the vehicle speed being greater than the third speed threshold exceeds the second preset duration, the intersection sign is at position 0;

[0029] When the above intersection sign is at position 1 or 2, if both lane lines are missing, then the intersection sign is at position 3;

[0030] When the intersection mark is at position 3, if a new lane line appears and the length of the new lane line is greater than the preset length, or when the intersection mark is at position 2, if a new lane line appears and the longitudinal distance from the starting point of the new lane line to the center of the vehicle head is less than the second preset distance, then the intersection mark is at position 4;

[0031] When the above-mentioned intersection sign position is 4, if the lateral deviation of the vehicle from the center reference line obtained by trajectory planning based on the above-mentioned new lane line is less than the preset lateral deviation, and the heading deviation is less than the preset heading deviation, the intersection sign position is set to 0.

[0032] In a second aspect, the present application provides a road intersection trajectory planning system, the road intersection trajectory planning system comprising:

[0033] A detection module, which is used to detect whether there are stop lines and lane lines;

[0034] The trajectory planning module is used to obtain the estimated steering wheel angle under the current reference trajectory when the stop line is detected if both lane lines are lost and the vehicle cannot be followed, or if only one lane line exists; if both lane lines are lost and the vehicle can be followed, the following trajectory is planned according to the following target; it is also used to maintain the trajectory based on the steering wheel angle of the previous frame to obtain a maintained trajectory when the absolute value of the difference between the above-mentioned estimated steering wheel angle and the steering wheel angle of the previous frame is greater than or equal to the preset angle difference; and when the above-mentioned absolute value is less than the above-mentioned preset angle difference, the predicted trajectory is obtained according to the historical center point of the vehicle.

[0035] In a third aspect, the present application provides an intersection trajectory planning device, which includes a processor, a memory, and an intersection trajectory planning program stored in the memory and executable by the processor, wherein when the intersection trajectory planning program is executed by the processor, the steps of the intersection trajectory planning method are implemented.

[0036] In a fourth aspect, the present application provides a computer-readable storage medium, on which an intersection trajectory planning program is stored, wherein when the intersection trajectory planning program is executed by a processor, the steps of the above-mentioned intersection trajectory planning method are implemented.

[0037] The beneficial effects of the technical solution provided by this application include:

[0038] When the stop line is detected, if both lane lines are lost and following is not possible, or if only one lane line exists, the estimated steering wheel angle under the current reference trajectory is obtained; if both lane lines are lost and following is possible, the following trajectory is planned according to the following target; wherein, when the absolute value of the difference between the above-mentioned estimated steering wheel angle and the steering wheel angle of the previous frame is greater than or equal to the preset angle difference, the trajectory is maintained based on the steering wheel angle of the previous frame to obtain a maintained trajectory; when the absolute value of the difference between the above-mentioned estimated steering wheel angle and the steering wheel angle of the previous frame is less than the above-mentioned preset angle difference, the predicted trajectory is obtained according to the historical center point of the vehicle; the present application fully considers the different scenarios of lane line loss at the intersection and the presence or absence of a following target, and then plans the optimal trajectory for a smooth transition to the opposite intersection according to different scenarios, thereby improving safety and experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram of a flow chart of an embodiment of a method for planning a trajectory at an intersection of the present application;

[0040] Figure 2 A flowchart of another embodiment of the intersection trajectory planning method of the present application;

[0041] Figure 3 A schematic diagram of an intersection according to an embodiment of the present application;

[0042] Figure 4 This is a schematic diagram of the architecture of an embodiment of the intersection trajectory planning system of the present application;

[0043] Figure 5 This is a schematic diagram of the hardware structure of the intersection trajectory planning device involved in the embodiment of the present application. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0045] In a first aspect, an embodiment of the present application provides a method for intersection trajectory planning.

[0046] In one embodiment, referring to Figure 1 , Figure 1 This is a flow chart of an embodiment of a method for planning a trajectory at an intersection of the present application. The above-mentioned method for planning a trajectory at an intersection includes:

[0047] S1. When the stop line is detected, if both lane lines are lost and the vehicle cannot be followed, or if only one lane line exists, obtain the estimated steering wheel angle under the current reference trajectory; if both lane lines are lost and the vehicle can be followed, plan the following trajectory according to the following target;

[0048] S2. When the absolute value of the difference between the estimated steering wheel angle and the steering wheel angle of the previous frame is greater than or equal to the preset angle difference, the track is maintained based on the steering wheel angle of the previous frame to obtain a maintained track;

[0049] S3. When the absolute value is smaller than the preset angle difference, the predicted trajectory is obtained according to the historical center point of the vehicle.

[0050] The above-mentioned step S2 and step S3 are in parallel relationship.

[0051] In this embodiment, when the stop line is detected, if both lane lines are lost and following is not possible, or only one lane line exists, the estimated steering wheel angle under the current reference trajectory is obtained; if both lane lines are lost and following is possible, the following trajectory is planned according to the following target; wherein, when the absolute value of the difference between the above-mentioned estimated steering wheel angle and the steering wheel angle of the previous frame is greater than or equal to the preset angle difference, the trajectory is maintained based on the steering wheel angle of the previous frame to obtain a maintained trajectory; when the absolute value of the difference between the above-mentioned estimated steering wheel angle and the steering wheel angle of the previous frame is less than the above-mentioned preset angle difference, the predicted trajectory is obtained according to the historical center point of the vehicle; the present application fully considers the different scenarios of lane line loss at the intersection and the presence or absence of a following target, and then plans the optimal trajectory for a smooth transition to the opposite intersection according to different scenarios, thereby improving safety and experience, and solving the technical problem that the related technology cannot accurately plan a trajectory for a smooth arrival at the opposite intersection.

[0052] Furthermore, in one embodiment, in the above step S1, when both lane lines are lost, the process further includes:

[0053] It is determined whether the vehicle can be followed, and when the speed of the vehicle is less than the first speed threshold and the following target is valid, it is determined that the vehicle can be followed, otherwise, it is determined that the vehicle cannot be followed. That is, when the speed of the vehicle is greater than or equal to the first speed threshold or the following target is invalid, it is determined that the vehicle cannot be followed.

[0054] The following target is determined to be valid when there is a following target, and the longitudinal distance from the center of the rear axle of the following target to the center of the front of the vehicle is less than the first preset distance, the target heading angle is not greater than the preset heading angle, and the longitudinal distance change value within a preset period is less than the preset change value. If any of the above conditions is not met, the following target is determined to be invalid.

[0055] Optionally, the following target in front of the lane is preferentially selected. If there is no target in front of the lane, the target in the side lane may be considered, that is, the target ID is not 0.

[0056] Optionally, the first vehicle speed threshold is 60 km / h, i.e. 16.67 m / s; the first preset distance is 65 m, the preset heading angle is 0.1 rad, the preset period is 50 ms, and the preset change value is 5 m.

[0057] In this embodiment, when there is a following target, and the longitudinal distance from the center of the rear axle of the following target to the center of the front of the vehicle, that is, the longitudinal deviation OBJ1PosX, is less than 65m, the target heading angle OBJ1HeadingAngle is not greater than 0.1rad, and the longitudinal distance change value of the following target within a cycle of 50ms is less than 5m, that is, there is no sudden approach or sudden distance, it can be considered that the following target has no cutting-in or cutting-out trend, and the following target is judged to be valid.

[0058] Furthermore, in one embodiment, when only one lane line exists or both lane lines are lost, the method further includes:

[0059] First, if a new lane line appears after only one lane line exists, and the longitudinal distance from the starting point of the new lane line to the center of the vehicle head is less than the second preset distance, or if a new lane line appears after two lane lines are lost, and the length of the new lane line is greater than the preset length, trajectory planning is performed according to the new lane line to obtain a center reference line;

[0060] Then, the following trajectory, the maintained trajectory, or the predicted trajectory is smoothly transitioned to the center reference line.

[0061] Optionally, the second preset distance is 5m, and the preset length is 5m.

[0062] In this embodiment, after there is only one lane line, the left or right lane line id jumps to a new lane line, or a new lane line appears directly, and the longitudinal distance from the starting point of the new lane line to the center of the vehicle's front is less than 5m, the center reference line is obtained by trajectory planning based on the above new lane line.

[0063] In this embodiment, after two lane lines are lost, when a new lane line appears and the length of the new lane line is greater than 5m, a center reference line is obtained by trajectory planning based on the new lane line.

[0064] Then, the following trajectory, the maintained trajectory, or the predicted trajectory is smoothly transitioned to the center reference line.

[0065] Optionally, in another embodiment, after obtaining the center reference line by performing trajectory planning according to the new lane line, the method further includes:

[0066] Compare the lateral deviation and parallelism of the intersection planning trajectory of the previous frame with the trajectory of the center reference line to determine whether a smooth transition is required. At this time, the intersection planning trajectory of the previous frame can be a following trajectory, a maintaining trajectory, or a predicted trajectory.

[0067] Among them, if the lateral deviation of the trajectory is greater than or equal to 0.2, or the parallelism is less than or equal to 0.8, the Bezier curve is used for secondary planning to smoothly transition the planned intersection trajectory to the center reference line; if the lateral deviation of the trajectory is less than 0.2 and the parallelism is greater than 0.8, there is no need for smooth transition.

[0068] Furthermore, in one embodiment, in the above step S1, planning the following vehicle trajectory according to the following vehicle target specifically includes:

[0069] According to the lateral and longitudinal positions of the following target relative to the ego vehicle, the following trajectory of the ego vehicle is obtained, and the following trajectory coefficient is output.

[0070] Further, in one embodiment, in the above step S1, obtaining the estimated steering wheel angle under the current reference trajectory specifically includes:

[0071] First, based on the current reference trajectory, the lateral and longitudinal displacements of the vehicle after a first preset time period are estimated.

[0072] Then, the estimated curvature is calculated based on the lateral and longitudinal displacements of the vehicle.

[0073] Finally, the estimated steering wheel angle is obtained according to the estimated curvature, the wheelbase and the wheelbase transmission ratio of the vehicle.

[0074] Optionally, the first preset time length is 1.4s.

[0075] In this embodiment, the lateral and longitudinal positions of the vehicle before and after the vehicle moves after 1.4 seconds can be estimated to calculate the estimated curvature, and then the estimated steering wheel angle can be obtained to prepare for determining whether the steering wheel is turned sharply.

[0076] Further, in one embodiment, in the above step S2, the track keeping is performed based on the steering wheel angle of the previous frame, specifically including:

[0077] First, it is determined whether the vehicle speed is greater than a second vehicle speed threshold.

[0078] If yes, then obtain the planned curvature according to the vehicle speed and yaw rate;

[0079] Otherwise, the planned curvature is obtained according to the steering wheel angle, angular transmission ratio and wheelbase of the previous frame;

[0080] Then, according to the above-mentioned planned curvature, the current turning curvature is obtained, and then the maintained trajectory can be obtained.

[0081] Optionally, the second vehicle speed threshold is 3 m / s. In this embodiment, when the current vehicle speed of the vehicle is greater than 3 m / s, the planned curvature is obtained according to the vehicle speed and yaw rate; when the current vehicle speed of the vehicle is less than or equal to 3 m / s, the planned curvature is obtained according to the steering wheel angle, angular transmission ratio and wheelbase of the previous frame.

[0082] Optionally, the current steering curvature is 35% of the planned curvature.

[0083] In this embodiment, by obtaining different planned curvatures when the vehicle speed is in different speed ranges, a more suitable current steering curvature can be obtained, and then a slow return to center can be performed according to the current steering curvature.

[0084] Furthermore, in one embodiment, a preliminary judgment can be made on the intersection mode where the vehicle is located.

[0085] Before the stop line is detected, the method further includes: setting the intersection sign position to 0;

[0086] When the above intersection sign is at position 0, if a stop line is detected, the intersection sign is set to position 1;

[0087] When the above-mentioned intersection sign is at position 1, if a lane line is lost, the intersection sign is at position 2; if the duration of the vehicle speed being greater than the third speed threshold exceeds the second preset duration, the intersection sign is at position 0;

[0088] When the above intersection sign is at position 1 or 2, if both lane lines are missing, then the intersection sign is at position 3;

[0089] When the intersection mark is at position 3, if a new lane line appears and the length of the new lane line is greater than the preset length, or when the intersection mark is at position 2, if a new lane line appears and the longitudinal distance from the starting point of the new lane line to the center of the vehicle head is less than the second preset distance, then the intersection mark is at position 4;

[0090] When the above-mentioned intersection sign position is 4, if the lateral deviation of the vehicle from the center reference line obtained by trajectory planning based on the above-mentioned new lane line is less than the preset lateral deviation, and the heading deviation is less than the preset heading deviation, the intersection sign position is set to 0.

[0091] Optionally, the third vehicle speed threshold is 5 km / h, i.e. 1.39 m / s, and the second preset time length is 2.5 s; the preset length is 5 m, and the second preset distance is 5 m; the preset lateral deviation is 0.2 m, and the preset heading deviation is 0.05 rad.

[0092] The method of this embodiment sets the intersection mode based on the sensor information, and considers the scenarios with and without following targets to perform self-vehicle trajectory planning, and plans an optimal trajectory for lateral control tracking, so that the autonomous driving vehicle can pass through the intersection smoothly when at least one lane line is lost, thereby improving the safety and experience of the vehicle.

[0093] like Figure 2 and Figure 3 As shown, in one embodiment, the above-mentioned intersection trajectory planning method specifically includes:

[0094] A1. Detect obstacle targets, lane lines, stop lines and other sensor information through sensors, and screen the following vehicle targets;

[0095] A2. Make a preliminary judgment on the intersection mode where the vehicle is located, so as to plan the driving trajectory of the vehicle through the intersection according to different intersection modes;

[0096] Among them, the initialization intersection flag bit intersect_phase=0, which is the non-intersection mode;

[0097] On the basis of intersect_phase=0, when the stop line is detected, enter the intersection intersect_phase=1;

[0098] On the basis of intersect_phase=1, when there is still one lane line on the left and right sides that is not lost, enter intersect_phase=2;

[0099] When intersect_phase=2 or intersect_phase=1, if the lane lines on both sides are lost at the same time, enter intersect_phase=3;

[0100] On the basis of intersect_phase=3, if a lane line appears and the length of the lane line is greater than 5m, or, on the basis of intersect_phase=2, if the left or right lane line ID jumps to a new lane line, or a new lane line appears directly, and the longitudinal distance from the starting point of the new lane line to the center of the vehicle head is less than 5m, enter intersect_phase=4;

[0101] On the basis of intersect_phase=4, if the left or right lane line is selected to plan the center reference line, and the lateral deviation between the center reference line and the vehicle is less than 0.2m, and the heading deviation is less than 0.05rad, return to intersect_phase=0;

[0102] If the state is intersect_phase=1 and the vehicle speed is greater than 5km / h for more than 2.5s, it returns to intersect_phase=0, that is, the stop line exists but the lane line has not been lost, and the intersection mode is directly exited to avoid memorizing the next scene without stop line and abnormally entering the hold logic;

[0103] A3: When both left and right lane lines are lost and it is determined that following is possible, the following trajectory is planned according to the following target and the vehicle turns to A7;

[0104] Among them, when two lane lines are lost, the vehicle speed is less than 60km / h, and the front following target is valid, the following trajectory of the vehicle is calculated based on the lateral and longitudinal positions of the front vehicle relative to the vehicle, and the following trajectory coefficient VFM_A2 is directly output:

[0105] VFM_A2=ACC_Target_PosY / ACC_Target_PosX

[0106] Among them, ACC_Target_PosY is the lateral deviation of the following target relative to the vehicle, in meters, which is equal to OBJ1PosY. ACC_Target_PosX is the distance between the following target and the vehicle, in meters. 2 , which is equal to the sum of the squares of the longitudinal deviations OBJ1PosX and OBJ1PosY of the following target relative to the vehicle.

[0107] A4. When only one lane line is lost, or both lane lines are lost and following is not possible, obtain the estimated steering wheel angle under the current reference trajectory;

[0108] When intersect_phase=2, or intersect_phase=3 and following vehicle is not possible, estimate the steering wheel angle of the current reference trajectory;

[0109] Based on the current reference trajectory and the vehicle's wheelbase and wheelbase transmission ratio, the lateral and longitudinal positions of the vehicle before and after the vehicle moves at 1.4s are estimated to calculate the estimated curvature and deduce the estimated steering wheel angle;

[0110] prev_curv=2*prev_lat / (prev_lat^2+prev_lon^2)

[0111] steer_ang=wheel_base*prev_curv*steer_ratio*180 / pi

[0112] Among them, prev_curv is the estimated curvature, prev_lat and prev_lon are the lateral and longitudinal displacements of the vehicle at a time interval of 1.4s, wheel_base is the wheelbase, steer_ang is the estimated steering wheel angle, and pi is π.

[0113] Subsequently, the estimated steering wheel angle can be compared with the actual steering wheel angle of the vehicle in the previous frame, and when the angle increases by no less than 5 degrees, it is determined that the steering wheel is turned sharply and a steering wheel holding plan is performed.

[0114] A5, when the absolute value of the difference between the estimated steering wheel angle and the steering wheel angle of the previous frame is greater than or equal to 5°, the track is maintained based on the steering wheel angle of the previous frame to obtain the maintained track, and the steering is turned to A7;

[0115] When it is determined that the steering wheel is turned too far, free space planning is performed. Based on the steering wheel angle of the previous frame, the vehicle speed and yaw rate, the current steering curvature is inferred and slowly returned to the center.

[0116] When the vehicle speed is greater than 3m / s, the planned curvature is:

[0117] curvature=-yaw_rate_rps / hv_spd_mps

[0118] Among them, yaw_rate_rps is the yaw angular rate; hv_spd_mps is the vehicle speed;

[0119] When the vehicle speed is less than or equal to 3m / s, the planned curvature is:

[0120] curvature=tan(wheel_angle_rad) / wheel_base

[0121] Among them, wheel_angle_rad=steer_angle_rad / steer_ratio;

[0122] wheel_base is the wheelbase, steer_angle_rad is the steering wheel angle of the previous frame, in rad, and steer_ratio is the angle transmission ratio.

[0123] Finally, the current steering curvature is: current_steer_curvature=0.7*(0.5*curvature).

[0124] A6. When the absolute value of the difference between the estimated steering wheel angle and the steering wheel angle of the previous frame is less than 5°, obtain the predicted trajectory according to the historical center point of the vehicle;

[0125] Among them, if it is judged that there is no major trend in the steering wheel, the fitted prediction trajectory is calculated based on the historical center point.

[0126] A7. If a new lane line appears after only one lane line exists, and the longitudinal distance from the starting point of the new lane line to the center of the vehicle's front is less than 5m, or if a new lane line appears after two lane lines are lost, and the length of the new lane line is greater than 5m, then obtain the center reference line and smoothly transition the following track, maintained track, or predicted track to the center reference line;

[0127] In other embodiments, when intersect_phase=4, the center reference line can also be obtained according to the new lane line, and the lateral deviation and parallelism of the intersection planning trajectory and the center reference line of the previous frame are determined. If the lateral deviation of the trajectory is greater than or equal to 0.2, or the parallelism is less than or equal to 0.8, the Bezier curve is used for secondary planning to smoothly transition the intersection trajectory to the center reference line.

[0128] A8. Output the trajectory with the minimum steering wheel angle cost of the smooth transition planning to the control module.

[0129] This embodiment can be applied to intersection scenarios where the lane line is lost and the stop line is recognized. Based on the lane line, stop line and target information output by forward vision and target screening, a preliminary judgment is made on the intersection mode where the vehicle is located, and different intersection crossing strategies are determined for different intersection conditions. Relying on sensor information, the driving trajectory of the intersection is planned with the minimum steering wheel angle cost, and smooth processing can be performed when the trajectory is switched, thereby improving the user experience and sense of security in scenarios where the lane line is lost.

[0130] In a second aspect, an embodiment of the present application also provides an intersection trajectory planning system.

[0131] In one embodiment, referring to Figure 4 , Figure 4 The schematic diagram of the architecture of an embodiment of the intersection trajectory planning system of the present application is shown in FIG. The intersection trajectory planning system includes a detection module and a trajectory planning module.

[0132] The detection module is used to detect whether there are stop lines and lane lines.

[0133] The above-mentioned trajectory planning module is used to obtain the estimated steering wheel angle under the current reference trajectory when the stop line is detected, if both lane lines are lost and the vehicle cannot be followed, or if only one lane line exists; if both lane lines are lost and the vehicle can be followed, the following trajectory is planned according to the following target.

[0134] The above-mentioned trajectory planning module is also used to maintain the trajectory based on the steering wheel angle of the previous frame to obtain a maintained trajectory when the absolute value of the difference between the above-mentioned estimated steering wheel angle and the steering wheel angle of the previous frame is greater than or equal to the preset angle difference; and when the above-mentioned absolute value is less than the above-mentioned preset angle difference, obtain the predicted trajectory according to the historical center point of the vehicle.

[0135] Optionally, the detection module includes sensors such as a front-view camera and a millimeter-wave radar, etc. The front-view camera, millimeter-wave radar and other sensors are used to detect information such as lane lines, obstacle targets and road signs.

[0136] Optionally, the above-mentioned intersection trajectory planning system also includes a perception fusion processing module and a target screening module.

[0137] The above-mentioned perception fusion processing module is connected to the detection module, and outputs the detected targets to the target screening module after fusion processing.

[0138] The target screening module classifies the position of target vehicles relative to the ego vehicle based on the ego vehicle coordinate system, and outputs the screened six target vehicles in the lane and the left and right lanes to the trajectory planning module, including information such as the target lateral and longitudinal position, speed, acceleration, and target ID.

[0139] The above-mentioned trajectory planning module judges the intersection mode based on the lane line information, stop line information output by the forward vision and the target information transmitted by the target screening module, determines the intersection stage where the vehicle is located, whether there are any following targets in front, whether there are abnormal lane lines expanding outward along the roadside, etc., and then plans the driving trajectory of the vehicle through the intersection without lanes based on the intersection mode and the movement status of the vehicle.

[0140] Among them, when there is a following target in front and the vehicle speed is less than 60km / h, you can enter the following mode, and then confirm the validity of the following target based on the target information; when the following target is valid, the following trajectory can be fitted based on the horizontal and vertical positions of the target.

[0141] Optionally, the system further comprises a control module, wherein the control module is used to control a steering wheel angle.

[0142] When the current view outputs the stop line information, the trajectory planning module preliminarily determines the mode of the vehicle entering the intersection, and estimates the reference trajectory based on the lane line planning. The control module controls the steering wheel angle. If the angle is too large, it is considered that there is an abnormal lane line that expands outward along the roadside, and the trajectory cannot be output. A maintenance plan is required for the current steering wheel angle; if there is no abnormal lane line, the output is the predicted trajectory of the vehicle that is fitted forward based on the historical center point of the vehicle.

[0143] When a new lane line appears, the trajectory planning module is also used to smoothly transition the planned following trajectory, maintaining trajectory or predicted trajectory to a reference trajectory based on the new lane line planning and output it to the control module.

[0144] Furthermore, in one embodiment, the trajectory planning module is also used for:

[0145] When both lane lines are lost, it is determined whether the following vehicle is allowed. If the speed of the vehicle is less than the first speed threshold and the following target is valid, it is determined that the following vehicle is allowed. Otherwise, it is determined that the following vehicle is not allowed.

[0146] When there is a following target, and the longitudinal distance from the center of the rear axle of the following target to the center of the front of the vehicle is less than the first preset distance, the target heading angle is not greater than the preset heading angle, and the longitudinal distance change value within a preset period is less than the preset change value, the following target is judged to be valid.

[0147] Furthermore, in one embodiment, the trajectory planning module is also used for:

[0148] If a new lane line appears after only one lane line exists, and the longitudinal distance from the starting point of the new lane line to the center of the vehicle head is less than the second preset distance, or if a new lane line appears after two lane lines are lost, and the length of the new lane line is greater than the preset length, trajectory planning is performed according to the new lane line to obtain a center reference line;

[0149] The following track, the maintained track, or the predicted track is smoothly transitioned to the center reference line.

[0150] Furthermore, in one embodiment, the trajectory planning module is also used for:

[0151] According to the lateral and longitudinal positions of the following target relative to the ego vehicle, the following trajectory of the ego vehicle is obtained, and the following trajectory coefficient is output.

[0152] Furthermore, in one embodiment, the trajectory planning module is also used for:

[0153] According to the current reference trajectory, the lateral and longitudinal displacements of the vehicle are estimated after a first preset time period.

[0154] Calculate the estimated curvature according to the lateral and longitudinal displacements of the vehicle;

[0155] The estimated steering wheel angle is obtained according to the estimated curvature, the wheelbase and the wheelbase transmission ratio of the vehicle.

[0156] Furthermore, in one embodiment, the trajectory planning module is also used for:

[0157] Determining whether the vehicle speed is greater than a second vehicle speed threshold;

[0158] If yes, then obtain the planned curvature according to the vehicle speed and yaw rate;

[0159] Otherwise, the planned curvature is obtained according to the steering wheel angle, angular transmission ratio and wheelbase of the previous frame;

[0160] According to the above planned curvature, the current steering curvature is obtained.

[0161] Furthermore, in one embodiment, the trajectory planning module is also used for:

[0162] Before the stop line is detected, the intersection sign is set to 0;

[0163] When the above intersection sign is at position 0, if a stop line is detected, the intersection sign is set to position 1;

[0164] When the above-mentioned intersection sign is at position 1, if a lane line is lost, the intersection sign is at position 2; if the duration of the vehicle speed being greater than the third speed threshold exceeds the second preset duration, the intersection sign is at position 0;

[0165] When the above intersection sign is at position 1 or 2, if both lane lines are missing, then the intersection sign is at position 3;

[0166] When the intersection mark is at position 3, if a new lane line appears and the length of the new lane line is greater than the preset length, or when the intersection mark is at position 2, if a new lane line appears and the longitudinal distance from the starting point of the new lane line to the center of the vehicle head is less than the second preset distance, then the intersection mark is at position 4;

[0167] When the above-mentioned intersection sign position is 4, if the lateral deviation of the vehicle from the center reference line obtained by trajectory planning based on the above-mentioned new lane line is less than the preset lateral deviation, and the heading deviation is less than the preset heading deviation, the intersection sign position is set to 0.

[0168] Among them, the functional implementation of each module in the above-mentioned intersection trajectory planning system corresponds to the steps in the above-mentioned intersection trajectory planning method embodiment, and its functions and implementation processes are no longer repeated here one by one.

[0169] In a third aspect, an embodiment of the present application provides a road intersection trajectory planning device, which may be a computer terminal, a vehicle-mounted terminal, a server, or other device with data processing capabilities.

[0170] Reference Figure 5 , Figure 5 Schematic diagram of the hardware structure of the intersection trajectory planning device involved in the embodiment of the present application. In the embodiment of the present application, the intersection trajectory planning device may include a processor, a memory, a communication interface and a communication bus.

[0171] The communication bus may be of any type and is used to interconnect the processor, the memory, and the communication interface.

[0172] The communication interface includes input / output (I / O) interface, physical interface and logical interface, etc., which are used to realize the interconnection of devices inside the intersection trajectory planning device, and the interface used to realize the interconnection of the intersection trajectory planning device with other devices (such as other computing devices or user devices). The physical interface can be an Ethernet interface, a fiber optic interface, an ATM interface, etc.; the user device can be a display (Display), a keyboard (Keyboard), etc.

[0173] The memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0174] The processor may be a general-purpose processor, and the general-purpose processor may call the intersection trajectory planning program stored in the memory and execute the intersection trajectory planning method provided by the embodiment of the present application. For example, the general-purpose processor may be a central processing unit (CPU). The method executed when the intersection trajectory planning program is called may refer to the various embodiments of the intersection trajectory planning method of the present application, which will not be repeated here.

[0175] Those skilled in the art will understand that Figure 5 The hardware structure shown in the figure does not constitute a limitation on the present application, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0176] In a fourth aspect, an embodiment of the present application also provides a computer-readable storage medium.

[0177] The computer-readable storage medium of the present application stores an intersection trajectory planning program, wherein when the intersection trajectory planning program is executed by a processor, the steps of the intersection trajectory planning method as described above are implemented.

[0178] Among them, the method implemented when the intersection trajectory planning program is executed can refer to the various embodiments of the intersection trajectory planning method of the present application, and will not be repeated here.

[0179] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are only for description and do not represent the advantages or disadvantages of the embodiments.

[0180] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit "first", "second" and "third" to different types.

[0181] In the description of the embodiments of the present application, "exemplary", "for example" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary", "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "for example" or "for example" is intended to present related concepts in a specific way.

[0182] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; the “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0183] In some processes described in the embodiments of the present application, multiple operations or steps that appear in a specific order are included, but it should be understood that these operations or steps may not be executed in the order in which they appear in the embodiments of the present application or in parallel, and the sequence number of the operation is only used to distinguish the different operations, and the sequence number itself does not represent any execution order. In addition, these processes may include more or fewer operations, and these operations or steps may be executed in sequence or in parallel, and these operations or steps may be combined.

[0184] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, disk, CD) as described above, and includes a number of instructions for a terminal device to execute the methods described in each embodiment of the present application.

[0185] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for intersection trajectory planning, characterized in that: The method comprises: When the stop line is detected, if both lane lines are lost and the vehicle cannot be followed, or if only one lane line exists, the estimated steering wheel angle under the current reference trajectory is obtained; if both lane lines are lost and the vehicle can be followed, the following trajectory is planned according to the following target; When the absolute value of the difference between the estimated steering wheel angle and the steering wheel angle of the previous frame is greater than or equal to the preset angle difference, performing trajectory keeping based on the steering wheel angle of the previous frame to obtain a kept trajectory; When the absolute value is less than the preset angle difference, the predicted trajectory is obtained according to the historical center point of the vehicle.

2. The intersection trajectory planning method according to claim 1, characterized in that: When both lane lines are lost, it also includes: Determine whether it is possible to follow the vehicle, and when the speed of the vehicle is less than the first speed threshold and the following target is valid, determine that it is possible to follow the vehicle, otherwise, determine that it is not possible to follow the vehicle; wherein, When there is a following target, and the longitudinal distance from the center of the rear axle of the following target to the center of the front of the vehicle is less than the first preset distance, the target heading angle is not greater than the preset heading angle, and the longitudinal distance change value within a preset period is less than the preset change value, the following target is judged to be valid.

3. The intersection trajectory planning method according to claim 1, characterized in that: When only one lane line exists or both lane lines are lost, it also includes: If a new lane line appears after only one lane line exists, and the longitudinal distance from the starting point of the new lane line to the center of the vehicle head is less than the second preset distance, or if a new lane line appears after two lane lines are lost, and the length of the new lane line is greater than the preset length, trajectory planning is performed according to the new lane line to obtain a center reference line; The following trajectory, the maintained trajectory, or the predicted trajectory is smoothly transitioned to the center reference line.

4. The intersection trajectory planning method according to claim 1, characterized in that: Plan the following trajectory according to the following target, including: According to the lateral and longitudinal positions of the following target relative to the ego vehicle, the following trajectory of the ego vehicle is obtained, and the following trajectory coefficient is output.

5. The intersection trajectory planning method according to claim 1, characterized in that: Get the estimated steering wheel angle under the current reference trajectory, including: According to the current reference trajectory, the lateral and longitudinal displacements of the vehicle are estimated after a first preset time period. Calculating an estimated curvature according to the lateral and longitudinal displacements of the vehicle; The estimated steering wheel angle is obtained according to the estimated curvature, the wheelbase and the wheelbase transmission ratio of the vehicle.

6. The intersection trajectory planning method according to claim 1, characterized in that: Track keeping is performed based on the steering wheel angle of the previous frame, including: Determining whether the vehicle speed is greater than a second vehicle speed threshold; If yes, then obtain the planned curvature according to the vehicle speed and yaw rate; Otherwise, the planned curvature is obtained according to the steering wheel angle, angular transmission ratio and wheelbase of the previous frame; According to the planned curvature, the current turning curvature is obtained.

7. The intersection trajectory planning method according to claim 1, characterized in that: Before the stop line is detected, the method further includes: setting the intersection sign position to 0; When the intersection sign is at position 0, if a stop line is detected, the intersection sign is set to position 1; When the intersection sign is at position 1, if a lane line is lost, the intersection sign is at position 2; if the duration of the vehicle speed being greater than the third speed threshold exceeds a second preset duration, the intersection sign is at position 0; When the intersection sign is at position 1 or 2, if both lane lines are lost, the intersection sign is at position 3; When the intersection mark is at position 3, if a new lane line appears and the length of the new lane line is greater than the preset length, or when the intersection mark is at position 2, if a new lane line appears and the longitudinal distance from the starting point of the new lane line to the center of the vehicle head is less than the second preset distance, then the intersection mark is at position 4; When the intersection sign is at position 4, if the lateral deviation of the vehicle from the center reference line obtained by trajectory planning based on the new lane line is less than the preset lateral deviation, and the heading deviation is less than the preset heading deviation, the intersection sign is set to position 0.

8. A road intersection trajectory planning system, characterized in that: The system comprises: A detection module, which is used to detect whether there are stop lines and lane lines; A trajectory planning module is used to obtain the estimated steering wheel angle under the current reference trajectory when the stop line is detected if both lane lines are lost and the vehicle cannot be followed, or if only one lane line exists; if both lane lines are lost and the vehicle can be followed, then the following trajectory is planned according to the following target; it is also used to maintain the trajectory based on the steering wheel angle of the previous frame to obtain a maintained trajectory when the absolute value of the difference between the estimated steering wheel angle and the steering wheel angle of the previous frame is greater than or equal to a preset angle difference; and when the absolute value is less than the preset angle difference, obtain the predicted trajectory according to the historical center point of the vehicle.

9. A road intersection trajectory planning device, characterized in that: The intersection trajectory planning device includes a processor, a memory, and an intersection trajectory planning program stored in the memory and executable by the processor, wherein when the intersection trajectory planning program is executed by the processor, the steps of the intersection trajectory planning method as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores an intersection trajectory planning program, wherein when the intersection trajectory planning program is executed by a processor, the steps of the intersection trajectory planning method according to any one of claims 1 to 7 are implemented.

Images