Intersection trajectory planning method, system, device and medium

Abstract

A method, system, device, and medium for intersection trajectory planning relate to the technical field of vehicle trajectory planning. The method includes: when a stop line is detected, if both lane lines are lost and following is not possible, or if only one lane line exists, then the estimated steering wheel angle under the current reference trajectory is obtained; if both lane lines are lost and following is possible, then the following trajectory is planned based on 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 a 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 is less than the preset angle difference, the predicted trajectory is obtained based on the historical center point of the vehicle. This application fully considers different scenarios such as 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 based on different scenarios, thereby improving safety and user 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] Currently, the development trend of autonomous driving is increasingly leaning toward a "perception-first, map-less" approach. This approach leverages sensory information to reduce reliance on high-definition topology, continuously optimizing the engineering capabilities of core regulatory and control algorithms, and integrating adaptive cruise control into autonomous driving to meet user needs for specific scenarios and functions while reducing costs. Therefore, in intersections without high-precision maps, autonomous vehicle trajectory planning based on sensory information and smooth intersection passage are of great strategic significance to the automotive industry's independent innovation, achieving cost reduction and efficiency gains, and reducing energy consumption and environmental pollution.

[0003] Related technologies can plan a trajectory based on lane markings or a target vehicle ahead of the vehicle. However, when there are no target vehicles or lane markings ahead of the vehicle, it's impossible to accurately plan a trajectory that leads smoothly to the oncoming intersection. Instead, the vehicle can only predict the trajectory based on historical center point fitting. Lateral deviations accumulate and can even be affected by curbs or unusual lane markings, resulting in significant steering wheel angle deviations in lateral control calculations and a poor user experience. Summary of the Invention

[0004] The present application provides a method, system, device and medium for intersection trajectory planning, which can solve the technical problem in the prior art that it is impossible to accurately plan a trajectory to smoothly reach the opposite intersection.

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

[0006] When a 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 based on 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 a preset angle difference, track keeping is performed 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 based on the historical center point of the vehicle.

[0009] In conjunction with the first aspect, in one embodiment, when both lane markings are lost, the method further includes:

[0010] Determine whether following the vehicle is possible, and when the vehicle speed is less than the first speed threshold and the following target is valid, determine that following the vehicle is possible; otherwise, determine that following the vehicle is not possible; 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 conjunction with the first aspect, in one embodiment, after only one lane marking exists or both lane markings 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's 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 based on the new lane line to obtain a center reference line;

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

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

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

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

[0018] Based on the current reference trajectory, estimate the lateral and longitudinal displacements of the vehicle after a first preset time period.

[0019] Calculate the estimated curvature based on 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 conjunction with the first aspect, in one embodiment, performing track keeping based on the steering wheel angle of the previous frame specifically includes:

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

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

[0024] Otherwise, the planned curvature is obtained based on 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 embodiment, before the stop line is detected, the method further includes: setting the intersection sign 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 intersection sign is at position 1, if a lane line is lost, the intersection sign is moved to position 2; if the duration of time the vehicle speed exceeds the third speed threshold exceeds a second preset duration, the intersection sign is moved to position 0;

[0029] When the above intersection sign is in position 1 or 2, if both lane lines are missing, then the intersection sign is set to 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's front is less than the second preset distance, then the intersection mark is moved to position 4;

[0031] 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.

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

[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 a stop line is detected, if both lane lines are lost and following is not possible, or if only one lane line exists; if both lane lines are lost and following is possible, 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 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 to obtain a maintained trajectory when the above-mentioned absolute value is less than the above-mentioned preset angle difference.

[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 a 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; this 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 This is a flow chart of an embodiment of the intersection trajectory planning method of the present application;

[0040] Figure 2 This is a flow chart 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 present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, 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 the intersection trajectory planning method of the present application. The above-mentioned intersection trajectory planning method includes:

[0047] S1. When a stop line is detected, if both lane lines are lost and following is not possible, or if only one lane line exists, obtain the estimated steering wheel angle for the current reference trajectory. If both lane lines are lost and following is possible, plan a following trajectory based on 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, track keeping is performed based on the steering wheel angle of the previous frame to obtain a maintained track;

[0049] S3. When the absolute value is less than the preset angle difference, a predicted trajectory is obtained based on the historical center point of the vehicle.

[0050] The above steps S2 and S3 are in parallel relationship.

[0051] In this embodiment, when a 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 in the related technology that a smooth trajectory to the opposite intersection cannot be accurately planned.

[0052] Furthermore, in one embodiment, in the above step S1, when both lane markings are lost, the following step is further included:

[0053] Whether following the vehicle is permitted is determined. If the vehicle speed is less than a first speed threshold and the following target is valid, following is determined to be permitted. Otherwise, following is determined to be prohibited. Specifically, following is determined to be prohibited if the vehicle speed is greater than or equal to the first speed threshold or the following target is invalid.

[0054] The following target is considered valid if there is a following target, the longitudinal distance from the center of the following target's rear axle to the center of the ego vehicle's front end is less than a first preset distance, the target heading angle is not greater than a preset heading angle, and the change in longitudinal distance within a preset period is less than a preset change value. If any of these conditions are not met, the following target is considered invalid.

[0055] Optionally, the following target in front of the lane is prioritized. 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's 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 based on the new lane line to obtain the 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, when 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, when a new lane line appears after two lane lines are lost 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 previous frame's intersection planning trajectory with the center reference line to determine whether a smooth transition is needed. In this case, the previous frame's intersection planning trajectory can be a following trajectory, a maintained 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, no smooth transition is required.

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

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

[0070] Furthermore, 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] Furthermore, 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 based on the vehicle speed and yaw rate;

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

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

[0081] Optionally, the second speed threshold is 3 m / s. In this embodiment, when the current vehicle speed is greater than 3 m / s, the planned curvature is obtained based on the vehicle speed and yaw rate. When the current vehicle speed is less than or equal to 3 m / s, the planned curvature is obtained based on the steering wheel angle, angular transmission ratio, and wheelbase in 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 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 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 intersection sign is at position 1, if a lane line is lost, the intersection sign is moved to position 2; if the duration of time the vehicle speed exceeds the third speed threshold exceeds a second preset duration, the intersection sign is moved to position 0;

[0088] When the above intersection sign is in position 1 or 2, if both lane lines are missing, then the intersection sign is set to 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's front is less than the second preset distance, then the intersection mark is moved to position 4;

[0090] 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.

[0091] Optionally, the third vehicle speed threshold is 5 km / h, i.e. 1.39 m / s, and the second preset time 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 an intersection mode based on sensor information, considers scenarios with and without following targets, performs ego-vehicle trajectory planning, and plans an optimal trajectory for lateral control tracking. This enables the autonomous vehicle to smoothly pass through the intersection even when at least one lane line is lost, improving vehicle safety and user experience.

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

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

[0095] A2. Make a preliminary assessment of the intersection pattern at which the vehicle is located, so as to plan the vehicle's trajectory through the intersection based on the different intersection patterns.

[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] Based on intersect_phase=1, if there is still one lane line on the left or right side that is not lost, enter intersect_phase=2;

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

[0100] If, based on intersect_phase = 3, a lane line appears and its length is greater than 5m, or if, based on intersect_phase = 2, 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 head is less than 5m, enter intersect_phase = 4;

[0101] Based on 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 a stop line and abnormally entering the hold logic;

[0103] A3: When both left and right lane markings are lost and following is determined to be possible, the following trajectory is planned based on the following target and the vehicle is turned to A7.

[0104] When both lane lines are lost, the ego vehicle's speed is less than 60 km / h, and the preceding vehicle target is valid, the ego vehicle's following trajectory is calculated based on the lateral and longitudinal positions of the preceding vehicle relative to the ego 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 marking is lost, or both lane markings 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 a vehicle is not possible, estimate the steering wheel angle of the current reference trajectory;

[0109] Based on the current reference trajectory, the vehicle's wheelbase, and the wheelbase transmission ratio, the lateral and longitudinal positions of the vehicle before and after the vehicle moves at 1.4 seconds are estimated to calculate the estimated curvature and infer 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] Where prev_curv is the estimated curvature, prev_lat and prev_lon are the lateral and longitudinal displacements of the ego vehicle at 1.4 s, respectively, 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. When the angle increases by no less than 5 degrees, it is determined that the steering wheel is turned sharply and the 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°, track keeping is performed based on the steering wheel angle of the previous frame to obtain a maintained track and turn to A7;

[0115] When a large steering wheel turn is detected, free space planning is performed. Based on the steering wheel angle, vehicle speed, and yaw rate of the previous frame, the current steering curvature is inferred and the vehicle is 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 in the previous frame, in rad, and steer_ratio is the angular 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 a predicted trajectory based on 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 fitting 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 5 meters, or if a new lane line appears after two lane lines are lost, and the new lane line is longer than 5 meters, obtain the center reference line and smoothly transition the following trajectory, maintained trajectory, or predicted trajectory to the center reference line.

[0127] In other embodiments, when intersect_phase = 4, a center reference line can be obtained based on the new lane line, and the lateral deviation and parallelism between the previous frame's intersection planned trajectory and the center reference line are determined. If the lateral deviation is greater than or equal to 0.2, or the parallelism is less than or equal to 0.8, a Bezier curve is used for quadratic 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 plan 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 the trajectory switching can also be smoothed, thereby improving the user experience and sense of security in the scenario 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 above-mentioned intersection trajectory planning system includes a detection module and a trajectory planning module.

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

[0133] The trajectory planning module is used to obtain the estimated steering wheel angle under the current reference trajectory when a stop line is detected. If both lane lines are lost and following is not possible, or if only one lane line exists, the module plans the following trajectory according to the following target if both lane lines are lost and following is possible.

[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 a predicted trajectory based on 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, and detects lane lines, obstacles, targets, road signs, and other information through the front-view camera and the millimeter-wave radar.

[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 after fusion processing to the target screening module.

[0138] The target screening module classifies the target vehicles relative to the ego vehicle based on the ego vehicle coordinate system and outputs the six selected target vehicles in the current lane and the left and right lanes ahead to the trajectory planning module, including information such as the target's horizontal and vertical position, speed, acceleration, and target ID.

[0139] The above-mentioned trajectory planning module judges the intersection mode based on the lane line information and stop line information output by the forward-looking output and the target information transmitted by the target screening module. It determines the intersection stage where the vehicle is located, whether there are any following targets ahead, and whether there are abnormal lane lines expanding outward from the roadside. Then, based on the intersection mode and the vehicle's motion state, it plans the vehicle's driving trajectory through the laneless intersection.

[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 above system further includes a control module, which is used to control the steering wheel angle.

[0142] When the current view outputs the stop line information, the trajectory planning module preliminarily determines the vehicle's entry mode into the intersection and controls the steering wheel angle based on the reference trajectory prediction control module based on lane line planning. If the angle is too large, it is considered that there is an abnormal lane line that expands outward from the roadside and the trajectory cannot be output. A maintenance plan for the current steering wheel angle is required. If there is no abnormal lane line, the output is the predicted trajectory of the vehicle 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, holding trajectory or predicted trajectory to a reference trajectory planned based on the new lane line and output it to the control module.

[0144] Furthermore, in one embodiment, the trajectory planning module is further configured to:

[0145] When both lane lines are lost, determine whether following is allowed. If the vehicle speed is less than the first speed threshold and the following target is valid, then following is allowed. Otherwise, following 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 further configured to:

[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's 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 based on the new lane line to obtain a center reference line;

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

[0150] Furthermore, in one embodiment, the trajectory planning module is further configured to:

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

[0152] Furthermore, in one embodiment, the trajectory planning module is further configured to:

[0153] Based on the current reference trajectory, estimate the lateral and longitudinal displacements of the vehicle after a first preset time period.

[0154] Calculate the estimated curvature based on 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 further configured to:

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

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

[0159] Otherwise, the planned curvature is obtained based on 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 further configured to:

[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 intersection sign is at position 1, if a lane line is lost, the intersection sign is moved to position 2; if the duration of time the vehicle speed exceeds the third speed threshold exceeds a second preset duration, the intersection sign is moved to position 0;

[0165] When the above intersection sign is in position 1 or 2, if both lane lines are missing, then the intersection sign is set to 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's front is less than the second preset distance, then the intersection mark is moved to position 4;

[0167] 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.

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

[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, memory, and communication interface.

[0172] Communication interfaces include input / output (I / O) interfaces, physical interfaces, and logical interfaces, which interconnect components within the intersection trajectory planning device and other devices (such as other computing devices or user devices). Physical interfaces can include Ethernet, fiber, or ATM interfaces; user devices can include displays and keyboards.

[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, which 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, and 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 to the present application and may include more or fewer components than shown in the figure, or a combination of certain components, or a different arrangement of components.

[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 this 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 for description only 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 the "first", "second" and "third" to different types.

[0181] In the description of the embodiments of this application, the words "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 this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[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; “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 are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed 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 the necessary general hardware platform, of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, 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, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling 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 do not 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 a 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 based on 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 a preset angle difference, performing trajectory keeping based on the steering wheel angle of the previous frame to obtain a maintained trajectory; When the absolute value is less than the preset angle difference, a predicted trajectory is obtained based on the historical center point of the vehicle.

2. The intersection trajectory planning method according to claim 1, wherein: When both lane markings are lost, also includes: Determine whether following the vehicle is possible, and when the vehicle speed is less than the first speed threshold and the following target is valid, determine that following the vehicle is possible; otherwise, determine that following the vehicle is not possible; 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, wherein: When only one lane line exists or both lane lines are missing, the following also applies: 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 head is less than a 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 a preset length, trajectory planning is performed based on 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, wherein: Plan the following trajectory based on the following target, including: According to the lateral and longitudinal positions of the following target relative to the ego vehicle, the ego vehicle's following trajectory is obtained and the following trajectory coefficient is output.

5. The intersection trajectory planning method according to claim 1, wherein: Get the estimated steering wheel angle under the current reference trajectory, including: Based on the current reference trajectory, estimate the lateral and longitudinal displacements of the vehicle after a first preset time period. Calculating an estimated curvature based on 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, wherein: Track keeping is performed based on the steering wheel angle of the previous frame, specifically including: Determining whether the vehicle speed is greater than a second vehicle speed threshold; If yes, then obtain the planned curvature based on the vehicle speed and yaw rate; Otherwise, the planned curvature is obtained based on the steering wheel angle, angular transmission ratio and wheelbase of the previous frame; According to the planned curvature, the current steering curvature is obtained.

7. The intersection trajectory planning method according to claim 1, wherein: Before the stop line is detected, the method further includes: setting the intersection sign 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 moved to position 2; if the duration of the time when the vehicle speed is greater than the third speed threshold exceeds a second preset duration, the intersection sign is moved to position 0; When the intersection sign is at position 1 or 2, if both lane lines are missing, then 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 a 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's head is less than a second preset distance, then the intersection mark is moved to 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; The trajectory planning module is used to obtain the estimated steering wheel angle under the current reference trajectory when a stop line is detected if both lane lines are lost and following is not possible, or if only one lane line exists; if both lane lines are lost and following is possible, plan the following trajectory 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 a predicted trajectory based on 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 according to 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 the processor, the steps of the intersection trajectory planning method according to any one of claims 1 to 7 are implemented.

Images